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| Subject: SWOT analysis | |
Author: Anonymous [ Edit | View ] |
Date Posted: 14:04:10 01/22/16 Fri A SWOT analysis (alternatively SWOT matrix) is a structured planning method used to evaluate the strengths, weaknesses, opportunities and threats involved in a project or in a business venture. A SWOT analysis can be carried out for a product, place, industry or person. It involves specifying the objective of the business venture or project and identifying the internal and external factors that are favorable and unfavorable to achieve that objective. Some authors credit SWOT to Albert Humphrey, who led a convention at the Stanford Research Institute (now SRI International) in the 1960s and 1970s using data from Fortune 500 companies.[1][2] However, Humphrey himself does not claim the creation of SWOT, and the origins remain obscure. The degree to which the internal environment of the firm matches with the external environment is expressed by the concept of strategic fit. Strengths: characteristics of the business or project that give it an advantage over others. Weaknesses: characteristics that place the business or project at a disadvantage relative to others. Opportunities: elements that the business or project could exploit to its advantage. Threats: elements in the environment that could cause trouble for the business or project. Identification of SWOTs is important because they can inform later steps in planning to achieve the objective. First, the decision makers should consider whether the objective is attainable, given the SWOTs. If the objective is not attainable a different objective must be selected and the process repeated. Users of SWOT analysis need to ask and answer questions that generate meaningful information for each category (strengths, weaknesses, opportunities, and threats) to make the analysis useful and find their competitive advantage. SWOT analysis aims to identify the key internal and external factors seen as important to achieving an objective. SWOT analysis groups key pieces of information into two main categories: internal factors the strengths and weaknesses internal to the organization external factors the opportunities and threats presented by the environment external to the organization Analysis may view the internal factors as strengths or as weaknesses depending upon their effect on the organization's objectives. What may represent strengths with respect to one objective may be weaknesses (distractions, competition) for another objective. The factors may include all of the 4Ps; as well as personnel, finance, manufacturing capabilities, and so on. The external factors may include macroeconomic matters, technological change, legislation, and sociocultural changes, as well as changes in the marketplace or in competitive position. The results are often presented in the form of a matrix. SWOT analysis is just one method of categorization and has its own weaknesses. For example, it may tend to persuade its users to compile lists rather than to think about actual important factors in achieving objectives. It also presents the resulting lists uncritically and without clear prioritization so that, for example, weak opportunities may appear to balance strong threats. It is prudent not to eliminate any candidate SWOT entry too quickly. The importance of individual SWOTs will be revealed by the value of the strategies they generate. A SWOT item that produces valuable strategies is important. A SWOT item that generates no strategies is not important. The usefulness of SWOT analysis is not limited to profit-seeking organizations. SWOT analysis may be used in any decision-making situation when a desired end-state (objective) is defined. Examples include: non-profit organizations, governmental units, and individuals. SWOT analysis may also be used in pre-crisis planning and preventive crisis management. SWOT analysis may also be used in creating a recommendation during a viability study/survey. SWOT analysis can be used effectively to build organization or personal strategy. Steps necessary to execute strategy-oriented analysis involve: identification of internal and external factors (using popular 2x2 matrix), selection and evaluation of the most important factors and identification of relations existing between internal and external features.[3] For instance: strong relations between strengths and opportunities can suggest good condition of the company and allow using aggressive strategy. On the other hand, strong interaction between weaknesses and threats could be analyzed as potential warning and advise for using defensive strategy. One way of utilizing SWOT is matching and converting. Matching is used to find competitive advantage by matching the strengths to opportunities. Converting is to apply conversion strategies to convert weaknesses or threats into strengths or opportunities. An example of conversion strategy is to find new markets. If the threats or weaknesses cannot be converted, a company should try to minimize or avoid them. [ Post a Reply to This Message ] |
| Subject: Strategy | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:59:02 01/22/16 Fri Strategy (from Greek στρατηγία stratēgia, "art of troop leader; office of general, command, generalship) is a high level plan to achieve one or more goals under conditions of uncertainty. In the sense of the "art of the general", which included several subsets of skills including "tactics", siegecraft, logistics etc., the term came into use in the 6th century C.E. in East Roman terminology, and was translated into Western vernacular languages only in the 18th century. From then until the 20th century, the word "strategy" came to denote "a comprehensive way to try to pursue political ends, including the threat or actual use of force, in a dialectic of wills" in a military conflict, in which both adversaries interact. Strategy is important because the resources available to achieve these goals are usually limited. Strategy generally involves setting goals, determining actions to achieve the goals, and mobilizing resources to execute the actions. A strategy describes how the ends (goals) will be achieved by the means (resources). This is generally tasked with determining strategy. Strategy can be intended or can emerge as a pattern of activity as the organization adapts to its environment or competes. It involves activities such as strategic planning and strategic thinking. Henry Mintzberg from McGill University defined strategy as "a pattern in a stream of decisions" to contrast with a view of strategy as planning, while Max McKeown (2011) argues that "strategy is about shaping the future" and is the human attempt to get to "desirable ends with available means". Dr. Vladimir Kvint defines strategy as "a system of finding, formulating, and developing a doctrine that will ensure long-term success if followed faithfully." Professor Richard P. Rumelt described strategy as a type of problem solving in 2011. He wrote that good strategy has an underlying structure he called a kernel. The kernel has three parts: 1) A diagnosis that defines or explains the nature of the challenge; 2) A guiding policy for dealing with the challenge; and 3) Coherent actions designed to carry out the guiding policy.[6] President Kennedy illustrated these three elements of strategy in his Cuban Missile Crisis Address to the Nation of 22 October 1962: Diagnosis: "This Government, as promised, has maintained the closest surveillance of the Soviet military buildup on the island of Cuba. Within the past week, unmistakable evidence has established the fact that a series of offensive missile sites are now in preparation on that imprisoned island. The purpose of these bases can be none other than to provide a nuclear strike capability against the Western Hemisphere." Guiding Policy: "Our unswerving objective, therefore, must be to prevent the use of these missiles against this or any other country, and to secure their withdrawal or elimination from the Western Hemisphere." Action Plans: First among seven numbered steps was the following: "To halt this offensive buildup a strict quarantine on all offensive military equipment under shipment to Cuba is being initiated. All ships of any kind bound for Cuba from whatever nation or port will, if found to contain cargoes of offensive weapons, be turned back." [ Post a Reply to This Message ] |
| Subject: Management science | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:51:46 01/22/16 Fri Management science (MS), is the broad interdisciplinary study of problem solving and decision making in human organizations, with strong links to economics, business, engineering, and other sciences. It uses various scientific research-based principles, strategies, and analytical methods including mathematical modeling, statistics and numerical algorithms to improve an organization's ability to enact rational and meaningful management decisions by arriving at optimal or near optimal solutions to complex decision problems. In short, management sciences help businesses to achieve goals using various scientific methods. The field was initially an outgrowth of applied mathematics, where early challenges were problems relating to the optimization of systems which could be modeled linearly, i.e., determining the maxima (of profit, assembly line performance, crop yield, bandwidth, etc.) or minima (of loss, risk, costs, etc.) of some objective function. Today, management science encompasses any organizational activity for which the problem can be structured as a functional system so as to obtain a solution set with identifiable characteristics. Management science is concerned with a number of different areas of study: One is developing and applying models and concepts that may prove useful in helping to illuminate management issues and solve managerial problems. The models used can often be represented mathematically, but sometimes computer-based, visual or verbal representations are used as well or instead.[1] Another area is designing and developing new and better models of organizational excellence. Management science research can be done on three levels:[2] The fundamental level lies in three mathematical disciplines: probability, optimization, and dynamical systems theory. The modeling level is about building models, analyzing them mathematically, gathering and analyzing data, implementing models on computers, solving them, experimenting with themall this is part of management science research on the modeling level. This level is mainly instrumental, and driven mainly by statistics and econometrics. The application level, just as in any other engineering and economics disciplines, strives to make a practical impact and be a driver for change in the real world. The management scientist's mandate is to use rational, systematic, science-based techniques to inform and improve decisions of all kinds. The techniques of management science are not restricted to business applications but may be applied to military, medical, public administration, charitable groups, political groups or community groups. Its origins can be traced to operations research, which made its debut during World War II when the Allied forces recruited scientists of various disciplines to assist with military operations. In these early applications, the scientists utilized simple mathematical models to make efficient use of limited technologies and resources. The application of these models within the corporate sector became known as management science. In 1967 Stafford Beer characterized the field of management science as "the business use of operations research. Applications of management science are abundant in industry as airlines, manufacturing companies, service organizations, military branches, and in government. The range of problems and issues to which management science has contributed insights and solutions is vast. It includes:.[1] scheduling airlines, both planes and crew, deciding the appropriate place to site new facilities such as a warehouse or factory, managing the flow of water from reservoirs, identifying possible future development paths for parts of the telecommunications industry, establishing the information needs and appropriate systems to supply them within the health service, and identifying and understanding the strategies adopted by companies for their information systems Management science is also concerned with so-called soft-operational analysis, which concerns methods for strategic planning, strategic decision support, and Problem Structuring Methods (PSM). At this level of abstraction, mathematical modeling and simulation will not suffice. Therefore, during the past 30 years, a number of non-quantified modelling methods have been developed. These include morphological analysis and various forms of influence diagrams. [ Post a Reply to This Message ] |
| Subject: Organization | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:47:30 01/22/16 Fri An organization or organisation (see spelling differences) is an entity comprising multiple people, such as an institution or an association, that has a collective goal and is linked to an external environment. The word is derived from the Greek word organon, which means "organ" There are a variety of legal types of organizations, including corporations, governments, non-governmental organizations, political organizations, international organizations, armed forces, charities, not-for-profit corporations, partnerships, cooperatives, and educational institutions. A hybrid organization is a body that operates in both the public sector and the private sector simultaneously, fulfilling public duties and developing commercial market activities. A voluntary association is an organization consisting of volunteers. Such organizations may be able to operate without legal formalities, depending on jurisdiction, including informal clubs. Organizations may also operate in secret and/or illegally in the case of secret societies, criminal organizations and resistance movements. The study of organizations includes a focus on optimizing organizational structure. According to management science, most human organizations fall roughly into four types: Committees or juries Ecologies Matrix organizations Pyramids or hierarchies Committees or juries These consist of a group of peers who decide as a group, perhaps by voting. The difference between a jury and a committee is that the members of the committee are usually assigned to perform or lead further actions after the group comes to a decision, whereas members of a jury come to a decision. In common law countries, legal juries render decisions of guilt, liability and quantify damages; juries are also used in athletic contests, book awards and similar activities. Sometimes a selection committee functions like a jury. In the Middle Ages, juries in continental Europe were used to determine the law according to consensus among local notables. Committees are often the most reliable way to make decisions. Condorcet's jury theorem proved that if the average member votes better than a roll of dice, then adding more members increases the number of majorities that can come to a correct vote (however correctness is defined). The problem is that if the average member is subsequently worse than a roll of dice, the committee's decisions grow worse, not better; therefore, staffing is crucial. Parliamentary procedure, such as Robert's Rules of Order, helps prevent committees from engaging in lengthy discussions without reaching decisions. Ecologies This organization has intense competition. Bad parts of the organization starve. Good ones get more work. Everybody is paid for what they actually do, and runs a tiny business that has to show a profit, or they are fired. Companies who utilize this organization type reflect a rather one-sided view of what goes on in ecology. It is also the case that a natural ecosystem has a natural border - ecoregions do not in general compete with one another in any way, but are very autonomous. This organizational type assigns each worker two bosses in two different hierarchies. One hierarchy is "functional" and assures that each type of expert in the organization is well-trained, and measured by a boss who is super-expert in the same field. The other direction is "executive" and tries to get projects completed using the experts. Projects might be organized by products, regions, customer types, or some other schema. As an example, a company might have an individual with overall responsibility for products X and Y, and another individual with overall responsibility for engineering, quality control, etc. Therefore, subordinates responsible for quality control of project X will have two reporting lines. [ Post a Reply to This Message ] |
| Subject: Non-governmental organization | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:43:26 01/22/16 Fri A non-governmental organization (NGO) is an organization that is neither a part of a government nor a conventional for-profit business. Usually set up by ordinary citizens, NGOs may be funded by governments, foundations, businesses, or private persons. Some avoid formal funding altogether and are run primarily by volunteers. NGOs are highly diverse groups of organizations engaged in a wide range of activities, and take different forms in different parts of the world. Some may have charitable status, while others may be registered for tax exemption based on recognition of social purposes. Others may be fronts for political, religious, or other interests. The number of NGOs in the United States is estimated at 1.5 million. India is estimated to have had around 2 million NGOs in 2009, just over one NGO per 600 Indians, and many times the number of primary schools and primary health centres in India. NGOs are difficult to define, and the term 'NGO' is not always used consistently. In some countries the term NGO is applied to an organization that in another country would be called an NPO (nonprofit organization), and vice-versa. There are many different classifications of NGO in use. The most common focus is on "orientation" and "level of operation". An NGO's orientation refers to the type of activities it takes on. These activities might include human rights, environmental, improving health, or development work. An NGO's level of operation indicates the scale at which an organization works, such as local, regional, national, or international. he UN, itself an inter-governmental organization, made it possible for certain approved specialized international non-state agencies i.e., non-governmental organizations to be awarded observer status at its assemblies and some of its meetings. Later the term became used more widely. Today, according to the UN, any kind of private organization that is independent from government control can be termed an "NGO", provided it is not-for-profit, nonprevention, and not simply an opposition political party.. One characteristic these diverse organizations share is that their non-profit status means they are not hindered by short-term financial objectives. Accordingly, they are able to devote themselves to issues which occur across longer time horizons, such as climate change, malaria prevention or a global ban on landmines. Public surveys reveal that NGOs often enjoy a high degree of public trust, which can make them a useful but not always sufficient proxy for the concerns of society and stakeholders. [ Post a Reply to This Message ] |
| Subject: Privately held company | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:40:29 01/22/16 Fri A privately held company or close corporation is a business company owned either by non-governmental organizations or by a relatively small number of shareholders or company members which does not offer or trade its company stock (shares) to the general public on the stock market exchanges, but rather the company's stock is offered, owned and traded or exchanged privately. More ambiguous terms for a privately held company are unquoted company and unlisted company. Though less visible than their publicly traded counterparts, private companies have major importance in the world's economy. In 2008, the 441 largest private companies in the United States accounted for US$1.8 trillion in revenues and employed 6.2 million people, according to Forbes. In 2005, using a substantially smaller pool size (22.7%) for comparison, the 339 companies on Forbes' survey of closely held U.S. businesses sold a trillion dollars' worth of goods and services (44%) and employed 4 million people. In 2004, the Forbes' count of privately held U.S. businesses with at least $1 billion in revenue was 305.[1] Cargill, Koch Industries, Bechtel, Publix, Pilot Corp., Deloitte Touche Tohmatsu (one of the members of the Big Four accounting firms), Hearst Corporation, Cox Enterprises, S. C. Johnson, and Mars are among the largest privately held companies in the United States. KPMG, the UK accounting firms Ernst & Young and PricewaterhouseCoopers, IKEA, Trafigura, J C Bamford Excavators (JCB), Lidl, Aldi, LEGO, Bosch, Rolex, Ferrero, Bertelsmann and Victorinox are some examples of Europe's largest privately held companies. [ Post a Reply to This Message ] |
| Subject: Shareholder | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:34:48 01/22/16 Fri A shareholder or stockholder is an individual or institution (including a corporation) that legally owns a share of stock in a public or private corporation. Shareholders are the owners of a limited company. They buy shares which represent part ownership of a company. Stockholders are granted special privileges depending on the class of stock. These rights may include: The right to sell their shares. The right to vote on the directors nominated by the board. The right to nominate directors (although this is very difficult in practice because of minority protections) and propose shareholder resolutions. The right to dividends if they are declared. The right to purchase new shares issued by the company. The right to what assets remain after a liquidation. Stockholders or shareholders are considered by some to be a subset of stakeholders, which may include anyone who has a direct or indirect interest in the business entity. For example, employees, suppliers, customers, the community, etc., are typically considered stakeholders because they contribute value and/or are impacted by the corporation. Shareholders in the primary market who buy IPOs provide capital to corporations; however, the vast majority of shareholders are in the secondary market and provide no capital directly to the corporation. [ Post a Reply to This Message ] |
| Subject: Stock | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:29:03 01/22/16 Fri The stock (also capital stock) of a corporation constitutes the equity stake of its owners. It represents the residual assets of the company that would be due to stockholders after discharge of all senior claims such as secured and unsecured debt. Stockholders' equity cannot be withdrawn from the company in a way that is intended to be detrimental to the company's creditors. The stock of a corporation is partitioned into shares, the total of which are stated at the time of business formation. Additional shares may subsequently be authorized by the existing shareholders and issued by the company. In some jurisdictions, each share of stock has a certain declared par value, which is a nominal accounting value used to represent the equity on the balance sheet of the corporation. In other jurisdictions, however, shares of stock may be issued without associated par value. Shares represent a fraction of ownership in a business. A business may declare different types (classes) of shares, each having distinctive ownership rules, privileges, or share values. Ownership of shares may be documented by issuance of a stock certificate. A stock certificate is a legal document that specifies the amount of shares owned by the shareholder, and other specifics of the shares, such as the par value, if any, or the class of the shares. In the United Kingdom, Republic of Ireland, South Africa, and Australia, stock can also refer to completely different financial instruments such as government bonds or, less commonly, to all kinds of marketable securities. Stock typically takes the form of shares of either common stock or preferred stock. As a unit of ownership, common stock typically carries voting rights that can be exercised in corporate decisions. Preferred stock differs from common stock in that it typically does not carry voting rights but is legally entitled to receive a certain level of dividend payments before any dividends can be issued to other shareholders.[3][4][page needed] Convertible preferred stock is preferred stock that includes an option for the holder to convert the preferred shares into a fixed number of common shares, usually any time after a predetermined date. Shares of such stock are called "convertible preferred shares" (or "convertible preference shares" in the UK). New equity issue may have specific legal clauses attached that differentiate them from previous issues of the issuer. Some shares of common stock may be issued without the typical voting rights, for instance, or some shares may have special rights unique to them and issued only to certain parties. Often, new issues that have not been registered with a securities governing body may be restricted from resale for certain periods of time. Preferred stock may be hybrid by having the qualities of bonds of fixed returns and common stock voting rights. They also have preference in the payment of dividends over common stock and also have been given preference at the time of liquidation over common stock. They have other features of accumulation in dividend. In addition, preferred stock usually comes with a letter designation at the end of the security; for example, Berkshire-Hathaway Class "B" shares sell under stock ticker BRK.B, whereas Class "A" shares of ORION DHC, Inc will sell under ticker OODHA until the company drops the "A" creating ticker OODH for its "Common" shares only designation. This extra letter does not mean that any exclusive rights exist for the shareholders but it does let investors know that the shares are considered for such, however, these rights or privileges may change based on the decisions made by the underlying company. [ Post a Reply to This Message ] |
| Subject: Investment | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:23:16 01/22/16 Fri Investment is time, energy, or matter spent in the hope of future benefits actualized within a specified date or time frame. This article concerns investment in finance. In finance, investment is buying or creating an asset with the expectation of capital appreciation, dividends (profit), interest earnings, rents, or some combination of these returns. This may or may not be backed by research and analysis. Most or all forms of investment involve some form of risk, such as investment in equities, property, and even fixed interest securities which are subject, among other things, to inflation risk. It is indispensable for project investors to identify and manage the risks related to the investment. Investment and investing is distinguished from other uses of money (such as saving, speculation, donation, gifting), in that the deployment of money is done for the purposes of obtaining a positive expected return. In finance, investment is the purchase of an asset or item with the hope that it will generate income or appreciate in the future and be sold at the higher price.[2] It generally does not include deposits with a bank or similar institution. The term investment is usually used when referring to a long-term outlook. This is the opposite of trading or speculation, which are short-term practices involving a much higher degree of risk. Financial assets take many forms and can range from the ultra safe low return government bonds to much higher risk higher reward international stocks. A good investment strategy will diversify the portfolio according to the specified needs. The most famous and successful investor of all time is Warren Buffett. In March 2013 Forbes magazine had Warren Buffett ranked as number 2 in their Forbes 400 list.[3] Buffett has advised in numerous articles and interviews that a good investment strategy is long term and choosing the right assets to invest in requires due diligence. Edward O. Thorp was a very successful hedge fund manager in the 1970s and 1980s that spoke of a similar approach.[4] Another thing they both have in common is a similar approach to managing investment money. No matter how successful the fundamental pick is, without a proper money management strategy, full potential of the asset cannot be reached. Both investors have been shown to use principles from the Kelly criterion for money management.[5] Numerous interactive calculators which use the Kelly criterion can be found online.[6] In contrast, dollar (or pound etc.) cost averaging and market timing are phrases often used in marketing of collective investments and can be said to be associated with speculation. Investments are often made indirectly through intermediaries, such as pension funds, banks, brokers, and insurance companies. These institutions may pool money received from a large number of individuals into funds such as investment trusts, unit trusts, SICAVs etc. to make large scale investments. Each individual investor then has an indirect or direct claim on the assets purchased, subject to charges levied by the intermediary, which may be large and varied. It generally, does not include deposits with a bank or similar institution. Investment usually involves diversification of assets in order to avoid unnecessary and unproductive risk. Business revolves around the factor of investing; financially, time, in the future and successful investors will generally focus on certain fundamental metrics for their gains. A value investor is aware that when considering the health of a company, the fundamentals associated with it, are a highly influencing factor. They include aspects related to financial and operational data, preferred by some of the most successful investors; for example, Warren Buffett and George Soros. The financial details, such as, earnings per share and sales growth, are essential aids for an investor in determining stocks trading below their worth. The price to earnings ratio (P/E), or earnings multiple, is a particularly significant and recognized fundamental ratio, with a function of dividing the share price of stock, by its earnings per share. This will provide the value representing the sum investors are prepared to expend for each dollar of company earnings. This ratio is an important aspect, due to its capacity as measurement for the comparison of valuations of various companies. A stock with a lower P/E ratio will cost less per share, than one with a higher P/E, taking into account the same level of financial performance; therefore, it essentially means a low P/E is the preferred option.[8] An instance, in which the price to earnings ratio has a lesser significance, is when companies in different industries are compared. An example; although, it is reasonable for a telecommunications stock to show a P/E in the low teens; in the case of hi-tech stock, a P/E in the 40s range, is not unusual. When making comparisons the P/E ratio can give you a refined view of a particular stock valuation. For investors paying for each dollar of a company's earnings, the P/E ratio is a significant indicator, but the price-to-book ratio (P/B) is also a reliable indication of how much investors are willing to spend on each dollar of company assets. In the process of the P/B ratio, the share price of a stock is divided by its net assets; any intangibles, such as goodwill, are not taken into account. It is a crucial factor of the price-to-book ratio, due to it indicating the actual payment for tangible assets and not the more difficult valuation, of intangibles. Accordingly, the P/B could be considered a comparatively, conservative metric. For investment purposes, an essential factor relates to how a company finances its assets, especially if it involves a sizable value stock and is a situation in which debt/equity ratio has a significant influence. Similar to the P/E ratio, the debt/equity ratio, indicates the proportion of financing, a company has obtained from debt; for example, loans, bonds and equity, such as, the issuance of shares and stock, which vary between industries. An indication to investors that all is not financially sound with a company, relates to above-industry debt/equity figures, particularly if an industry is experiencing a challenging, adverse business environment. A factor that sometimes remains unaware to investors is that the earnings of a company generally do not equal the amount of cash generated. This is due to companies reporting their financials utilising, Generally Accepted Accounting Principles (GAAP). It is a standard framework of guidelines for the financial accounting practices used in any given jurisdiction. International Financial Reporting Standards (IFRS) are commonly used, worldwide. Free cash flow is a metric that determines for an investor the sum of actual cash remaining in a company after deduction of any capital investments. In general, it is preferable to for a company to boast a positive free cash flow, but similar to the debt-equity ratio, this metric assumes greater significance in a difficult business environment. [ Post a Reply to This Message ] |
| Subject: Service (economics) | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:21:20 01/22/16 Fri In economics, a service is an intangible commodity. That is, services are an example of intangible economic goods. Service provision is often an economic activity where the buyer does not generally, except by exclusive contract, obtain exclusive ownership of the thing purchased. The benefits of such a service, if priced, are held to be self-evident in the buyer's willingness to pay for it. Public services are those, that society (nation state, fiscal union, regional) as a whole pays for, through taxes and other means. By composing and orchestrating the appropriate level of resources, skill, ingenuity, and experience for effecting specific benefits for service consumers, service providers participate in an economy without the restrictions of carrying inventory (stock) or the need to concern themselves with bulky raw materials. On the other hand, their investment in expertise does require consistent service marketing and upgrading in the face of competition. Services can be paraphrased in terms of their key characteristics, sometimes called the "Five I's of Services". 1. Intangibility Services are intangible and insubstantial: they cannot be touched, gripped, handled, looked at, smelled, tasted. Thus, there is neither potential nor need for transport, storage or stocking of services. Furthermore, a service can be (re)sold or owned by somebody, but it cannot be turned over from the service provider to the service consumer. Solely, the service delivery can be commissioned to a service provider who must generate and render the service at the distinct request of an authorized service consumer. 2. Inventory (Perishability) Services have little or no tangible components and therefore cannot be stored for a future use. Services are produced and consumed during the same period of time. Services are perishable in two regards The service relevant resources, processes and systems are assigned for service delivery during a definite period in time. If the designated or scheduled service consumer does not request and consume the service during this period, the service cannot be performed for him. From the perspective of the service provider, this is a lost business opportunity as he cannot charge any service delivery; potentially, he can assign the resources, processes and systems to another service consumer who requests a service. Examples: The hairdresser serves another client when the scheduled starting time or time slot is over. An empty seat on a plane never can be utilized and charged after departure. When the service has been completely rendered to the requesting service consumer, this particular service irreversibly vanishes as it has been consumed by the service consumer. Example: the passenger has been transported to the destination and cannot be transported again to this location at this point in time. 3. Inseparability The service provider is indispensable for service delivery as he must promptly generate and render the service to the requesting service consumer. In many cases the service delivery is executed automatically but the service provider must preparatorily assign resources and systems and actively keep up appropriate service delivery readiness and capabilities. Additionally, the service consumer is inseparable from service delivery because he is involved in it from requesting it up to consuming the rendered benefits. Examples: The service consumer must sit in the hairdresser's shop & chair or in the plane & seat; correspondingly, the hairdresser or the pilot must be in the same shop or plane, respectively, for delivering the service. 4. Inconsistency (Variability) Each service is unique. It is one-time generated, rendered and consumed and can never be exactly repeated as the point in time, location, circumstances, conditions, current configurations and/or assigned resources are different for the next delivery, even if the same service consumer requests the same service. Many services are regarded as heterogeneous or lacking homogeneity and are typically modified for each service consumer or each new situation (consumerised). Example: The taxi service which transports the service consumer from his home to the opera is different from the taxi service which transports the same service consumer from the opera to his home another point in time, the other direction, maybe another route, probably another taxi driver and cab. 5. Involvement One of the most important characteristics of services is the participation of the customer in the service delivery process. A customer has the opportunity to get the services modified according to specific requirement. Each of these characteristics is retractable per se and their inevitable coincidence complicates the consistent service conception and make service delivery a challenge in each and every case. Proper service marketing requires creative visualization to effectively evoke a concrete image in the service consumer's mind. From the service consumer's point of view, these characteristics make it difficult, or even impossible, to evaluate or compare services prior to experiencing the service delivery. Mass generation and delivery of services is very difficult. This can be seen as a problem of inconsistent service quality. Both inputs and outputs to the processes involved providing services are highly variable, as are the relationships between these processes, making it difficult to maintain consistent service quality. For many services there is labor intensity as services usually involve considerable human activity, rather than a precisely determined process; exceptions include utilities. Human resource management is important. The human factor is often the key success factor in service economies. It is difficult to achieve economies of scale or gain dominant market share. There are demand fluctuations and it can be difficult to forecast demand. Demand can vary by season, time of day, business cycle, etc. There is consumer involvement as most service provision requires a high degree of interaction between service consumer and service provider. There is a customer-based relationship based on creating long-term business relationships. Accountants, attorneys, and financial advisers maintain long-term relationships with their clients for decades. These repeat consumers refer friends and family, helping to create a client-based relationship. [ Post a Reply to This Message ] |
| Subject: Business | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:17:56 01/22/16 Fri A business, also known as an enterprise, agency, or a firm, is an entity involved in the provision of goods, services, or both to consumers.[1] Businesses are prevalent in capitalist economies, where most of them are privately owned and provide goods and services to customers in exchange for other goods, services, or money. Businesses may also be social not-for-profit enterprises or state-owned public enterprises targeted for specific social and economic objectives. A business owned by multiple individuals may be formed as an incorporated company or jointly organised as a partnership. Countries have different laws that may ascribe different rights to the various business entities. Business can refer to a particular organization or to an entire market sector, e.g. "the music business". Compound forms such as agribusiness represent subsets of the word's broader meaning, which encompasses all activity by suppliers of goods and services. The goal is for sales to be more than expenditures resulting in a profit. Forms of business ownership vary by jurisdiction, but several common forms exist: Sole proprietorship: A sole proprietorship, also known as a sole trader, is owned by one person and operates for their benefit. The owner may operate the business alone or with other people. A sole proprietor has unlimited liability for all obligations incurred by the business, whether from operating costs or judgements against the business. All assets of the business belong to a sole proprietor, including, for example, computer infrastructure, any inventory, manufacturing equipment and/or retail fixtures, as well as any real property owned by the business. Partnership: A partnership is a business owned by two or more people. In most forms of partnerships, each partner has unlimited liability for the debts incurred by the business. The three most prevalent types of for-profit partnerships are general partnerships, limited partnerships, and limited liability partnerships. Corporation: The owners of a corporation have limited liability and the business has a separate legal personality from its owners. Corporations can be either government-owned or privately owned. They can organize either for profit or as not-for-profit organizations. A privately owned, for-profit corporation is owned by its shareholders, who elect a board of directors to direct the corporation and hire its managerial staff. A privately owned, for-profit corporation can be either privately held by a small group of individuals, or publicly held, with publicly traded shares listed on a stock exchange. Cooperative: Often referred to as a "co-op", a cooperative is a limited liability business that can organize for-profit or not-for-profit. A cooperative differs from a corporation in that it has members, not shareholders, and they share decision-making authority. Cooperatives are typically classified as either consumer cooperatives or worker cooperatives. Cooperatives are fundamental to the ideology of economic democracy. Agriculture and mining businesses produce raw material, such as plants or minerals. Financial businesses include banks and other companies that generate profits through investment and management of capital. Information businesses generate profits primarily from the sale of intellectual property - they include movie studios, publishers and Internet and software companies. Manufacturers produce products, either from raw materials or from component parts, then sell their products at a profit. Companies that make tangible goods such as cars, clothing or pipes are considered[by whom?] manufacturers. Real-estate businesses sell, rent, and develop properties - including land, residential homes, and other buildings. Retailers and distributors act as middlemen and get goods produced by manufacturers to the intended consumers; they make their profits by marking up their prices. Most stores and catalog companies are distributors or retailers. Service businesses offer intangible goods or services and typically charge for labor or other services provided to government, to consumers, or to other businesses. Interior decorators, consulting firms and entertainers are service businesses. Transportation businesses deliver goods and individuals to their destinations for a fee. Utilities produce public services such as electricity or sewage treatment, usually under a government [ Post a Reply to This Message ] |
| Subject: Chemical equilibrium | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:14:19 01/22/16 Fri In a chemical reaction, chemical equilibrium is the state in which both reactants and products are present in concentrations which have no further tendency to change with time. Usually, this state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but equal. Thus, there are no net changes in the concentrations of the reactant(s) and product(s). Such a state is known as dynamic equilibrium. he concept of chemical equilibrium was developed after Berthollet (1803) found that some chemical reactions are reversible. For any reaction mixture to exist at equilibrium, the rates of the forward and backward (reverse) reactions are equal. In the following chemical equation with arrows pointing both ways to indicate equilibrium, A and B are reactant chemical species, S and T are product species, and α, β, σ, and τ are the stoichiometric coefficients of the respective reactants and products: \alpha A + \beta B \rightleftharpoons \sigma S + \tau T The equilibrium concentration position of a reaction is said to lie "far to the right" if, at equilibrium, nearly all the reactants are consumed. Conversely the equilibrium position is said to be "far to the left" if hardly any product is formed from the reactants. Guldberg and Waage (1865), building on Berthollets ideas, proposed the law of mass action: \mbox{forward reaction rate} = k_+ {A}^\alpha{B}^\beta \,\! \mbox{backward reaction rate} = k_{-} {S}^\sigma{T}^\tau \,\! where A, B, S and T are active masses and k+ and k− are rate constants. Since at equilibrium forward and backward rates are equal: k_+ \left\{ A \right\}^\alpha \left\{B \right\}^\beta = k_{-} \left\{S \right\}^\sigma\left\{T \right\}^\tau \, and the ratio of the rate constants is also a constant, now known as an equilibrium constant. K_c=\frac{k_+}{k_-}=\frac{\{S\}^\sigma \{T\}^\tau } {\{A\}^\alpha \{B\}^\beta} By convention the products form the numerator. However, the law of mass action is valid only for concerted one-step reactions that proceed through a single transition state and is not valid in general because rate equations do not, in general, follow the stoichiometry of the reaction as Guldberg and Waage had proposed (see, for example, nucleophilic aliphatic substitution by SN1 or reaction of hydrogen and bromine to form hydrogen bromide). Equality of forward and backward reaction rates, however, is a necessary condition for chemical equilibrium, though it is not sufficient to explain why equilibrium occurs. Despite the failure of this derivation, the equilibrium constant for a reaction is indeed a constant, independent of the activities of the various species involved, though it does depend on temperature as observed by the van 't Hoff equation. Adding a catalyst will affect both the forward reaction and the reverse reaction in the same way and will not have an effect on the equilibrium constant. The catalyst will speed up both reactions thereby increasing the speed at which equilibrium is reached.[2][4] Although the macroscopic equilibrium concentrations are constant in time, reactions do occur at the molecular level. For example, in the case of acetic acid dissolved in water and forming acetate and hydronium ions, CH3CO2H + H2O ⇌ CH3CO2− + H3O+ a proton may hop from one molecule of acetic acid on to a water molecule and then on to an acetate anion to form another molecule of acetic acid and leaving the number of acetic acid molecules unchanged. This is an example of dynamic equilibrium. Equilibria, like the rest of thermodynamics, are statistical phenomena, averages of microscopic behavior. Le Chatelier's principle (1884) gives an idea of the behavior of an equilibrium system when changes to its reaction conditions occur. If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to partially reverse the change. For example, adding more S from the outside will cause an excess of products, and the system will try to counteract this by increasing the reverse reaction and pushing the equilibrium point backward (though the equilibrium constant will stay the same). If mineral acid is added to the acetic acid mixture, increasing the concentration of hydronium ion, the amount of dissociation must decrease as the reaction is driven to the left in accordance with this principle. This can also be deduced from the equilibrium constant expression for the reaction: K=\frac{\{CH_3CO_2^-\}\{H_3O^+\}} {\{CH_3CO_2H\}} If {H3O+} increases {CH3CO2H} must increase and {CH3CO2−} must decrease. The H2O is left out, as it is the solvent and its concentration remains high and nearly constant. A quantitative version is given by the reaction quotient. J. W. Gibbs suggested in 1873 that equilibrium is attained when the Gibbs free energy of the system is at its minimum value (assuming the reaction is carried out at constant temperature and pressure). What this means is that the derivative of the Gibbs energy with respect to reaction coordinate (a measure of the extent of reaction that has occurred, ranging from zero for all reactants to a maximum for all products) vanishes, signalling a stationary point. This derivative is called the reaction Gibbs energy (or energy change) and corresponds to the difference between the chemical potentials of reactants and products at the composition of the reaction mixture.[1] This criterion is both necessary and sufficient. If a mixture is not at equilibrium, the liberation of the excess Gibbs energy (or Helmholtz energy at constant volume reactions) is the driving force for the composition of the mixture to change until equilibrium is reached. The equilibrium constant can be related to the standard Gibbs free energy change for the reaction by the equation \Delta_rG^\ominus = -RT \ln K_{eq} where R is the universal gas constant and T the temperature. When the reactants are dissolved in a medium of high ionic strength the quotient of activity coefficients may be taken to be constant. In that case the concentration quotient, Kc, K_c=\frac{[S]^\sigma [T]^\tau } {[A]^\alpha [B]^\beta} where [A] is the concentration of A, etc., is independent of the analytical concentration of the reactants. For this reason, equilibrium constants for solutions are usually determined in media of high ionic strength. Kc varies with ionic strength, temperature and pressure (or volume). Likewise Kp for gases depends on partial pressure. These constants are easier to measure and encountered in high-school chemistry courses. t constant temperature and pressure, one must consider the Gibbs free energy, G, while at constant temperature and volume, one must consider the Helmholtz free energy: A, for the reaction; and at constant internal energy and volume, one must consider the entropy for the reaction: S. The constant volume case is important in geochemistry and atmospheric chemistry where pressure variations are significant. Note that, if reactants and products were in standard state (completely pure), then there would be no reversibility and no equilibrium. Indeed, they would necessarily occupy disjoint volumes of space. The mixing of the products and reactants contributes a large entropy (known as entropy of mixing) to states containing equal mixture of products and reactants. The standard Gibbs energy change, together with the Gibbs energy of mixing, determine the equilibrium state.[5][6] In this article only the constant pressure case is considered. The relation between the Gibbs free energy and the equilibrium constant can be found by considering chemical potentials. [ Post a Reply to This Message ] |
| Subject: Closed system | |
Author: Anonymous [ Edit | View ] |
Date Posted: 13:09:20 01/22/16 Fri A closed system is a physical system that does not allow certain types of transfers (such as transfer of mass) in or out of the system. The specification of what types of transfers are excluded varies in the closed systems of physics, chemistry or engineering. In classical mechanics In nonrelativistic classical mechanics, a closed system is a physical system that doesn't exchange any matter with its surroundings, and isn't subject to any force whose source is external to the system.[1][2] A closed system in classical mechanics would be considered an isolated system in thermodynamics. In thermodynamics Main article: Thermodynamic system In thermodynamics, a closed system can exchange energy (as heat or work) but not matter, with its surroundings. An isolated system cannot exchange any heat, work, or matter with the surroundings, while an open system can exchange energy and matter. (This scheme of definition of terms is not uniformly used, though it is convenient for some purposes. In particular, some writers use 'closed system' where 'isolated system' is here used.[10][11]) For a simple system, with only one type of particle (atom or molecule), a closed system amounts to a constant number of particles. However, for systems which are undergoing a chemical reaction, there may be all sorts of molecules being generated and destroyed by the reaction process. In this case, the fact that the system is closed is expressed by stating that the total number of each elemental atom is conserved, no matter what kind of molecule it may be a part of. Mathematically: \sum_{j=1}^m a_{ij}N_j=b_i where N_j is the number of j-type molecules, a_{ij} is the number of atoms of element i in molecule j and bi is the total number of atoms of element i in the system, which remains constant, since the system is closed. There will be one such equation for each different element in the system. In an engineering context, a closed system is a bound system, i.e. defined, in which every input is known and every resultant is known (or can be known) within a specific time. [ Post a Reply to This Message ] |
| Subject: Gibbs free energy | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:56:47 01/21/16 Thu In thermodynamics, the Gibbs free energy (IUPAC recommended name: Gibbs energy or Gibbs function; also known as free enthalpy to distinguish it from Helmholtz free energy) is a thermodynamic potential that measures the maximum or reversible work that may be performed by a thermodynamic system at a constant temperature and pressure (isothermal, isobaric). Just as in mechanics, where potential energy is defined as capacity to do work, similarly different potentials have different meanings. The Gibbs free energy (kJ in SI units) is the maximum amount of non-expansion work that can be extracted from a thermodynamically closed system (one that can exchange heat and work with its surroundings, but not matter); this maximum can be attained only in a completely reversible process. When a system changes from a well-defined initial state to a well-defined final state, the Gibbs free energy change ΔG equals the work exchanged by the system with its surroundings, minus the work of the pressure forces, during a reversible transformation of the system from the initial state to the final state. The Gibbs energy (also referred to as G) is also the thermodynamic potential that is minimized when a system reaches chemical equilibrium at constant pressure and temperature. Its derivative with respect to the reaction coordinate of the system vanishes at the equilibrium point. As such, a reduction in G is a necessary condition for the spontaneity of processes at constant pressure and temperature. The Gibbs free energy, originally called available energy, was developed in the 1870s by the American mathematician Josiah Willard Gibbs. In 1873, Gibbs described this "available energy" as the greatest amount of mechanical work which can be obtained from a given quantity of a certain substance in a given initial state, without increasing its total volume or allowing heat to pass to or from external bodies, except such as at the close of the processes are left in their initial condition. The initial state of the body, according to Gibbs, is supposed to be such that "the body can be made to pass from it to states of dissipated energy by reversible processes." In his 1876 magnum opus On the Equilibrium of Heterogeneous Substances, a graphical analysis of multi-phase chemical systems, he engaged his thoughts on chemical free energy in full. According to the second law of thermodynamics, for systems reacting at STP (or any other fixed temperature and pressure), there is a general natural tendency to achieve a minimum of the Gibbs free energy. A quantitative measure of the favorability of a given reaction at constant temperature and pressure is the change ΔG in Gibbs free energy that is (or would be) effected by proceeding with the reaction. As a necessary condition for the reaction to occur at constant temperature and pressure, ΔG must be smaller than the non-PV (e.g. electrical) work, which is often equal to zero. ΔG equals the maximum amount of non-PV work that can be performed as a result of the chemical reaction. If the analysis indicated a positive ΔG for the reaction, then energyin the form of electrical or other non-PV workwould have to be added to the reacting system for ΔG to be smaller than the non-PV work and make it possible for the reaction to occur. The equation can be also seen from the perspective of the system taken together with its surroundings (the rest of the universe). First assume that the given reaction at constant temperature and pressure is the only one that is occurring. Then the entropy released or absorbed by the system equals the entropy that the environment must absorb or release, respectively. The reaction will only be allowed if the total entropy change of the universe is zero or positive. This is reflected in a negative ΔG, and the reaction is called exergonic. If we couple reactions, then an otherwise endergonic chemical reaction (one with positive ΔG) can be made to happen. The input of heat into an inherently endergonic reaction, such as the elimination of cyclohexanol to cyclohexene, can be seen as coupling an unfavourable reaction (elimination) to a favourable one (burning of coal or other provision of heat) such that the total entropy change of the universe is greater than or equal to zero, making the total Gibbs free energy difference of the coupled reactions negative. [ Post a Reply to This Message ] |
| Subject: Thermodynamic equilibrium | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:51:48 01/21/16 Thu Thermodynamic equilibrium is an axiomatic concept of thermodynamics. It is an internal state of a single thermodynamic system, or a relation between several thermodynamic systems connected by more or less permeable or impermeable walls. In thermodynamic equilibrium there are no net macroscopic flows of matter or of energy, either within a system or between systems. In a system in its own state of internal thermodynamic equilibrium, no macroscopic change occurs. Systems in mutual thermodynamic equilibrium are simultaneously in mutual thermal, mechanical, chemical, and radiative equilibria. Systems can be in one kind of mutual equilibrium, though not in others. In thermodynamic equilibrium, all kinds of equilibrium hold at once and indefinitely, until disturbed by a thermodynamic operation. In a macroscopic equilibrium, almost or perfectly exactly balanced microscopic exchanges occur; this is the physical explanation of the notion of macroscopic equilibrium. A thermodynamic system in its own state of internal thermodynamic equilibrium has a spatially uniform temperature. Its intensive properties, other than temperature, may be driven to spatial inhomogeneity by an unchanging long range force field imposed on it by its surroundings. In non-equilibrium systems, by contrast, there are net flows of matter or energy. If such changes can be triggered to occur in a system in which they are not already occurring, it is said to be in a metastable equilibrium. Though it is not a widely named law, it is an axiom of thermodynamics that there exist states of thermodynamic equilibrium. The second law of thermodynamics states that when a body of material starts from an equilibrium state, in which portions of it are held at different states by more or less permeable or impermeable partitions, and a thermodynamic operation removes or makes the partitions more permeable and it is isolated, then it spontaneously reaches its own new state of internal thermodynamic equilibrium, and this is accompanied by an increase in the sum of the entropies of the portions. Classical thermodynamics deals with states of dynamic equilibrium. The state of a system at thermodynamic equilibrium is the one for which some thermodynamic potential is minimized, or for which the entropy (S) is maximized, for specified conditions. One such potential is the Helmholtz free energy (A), for a system with surroundings at controlled constant temperature and volume: A = U - TS Another potential, the Gibbs free energy (G), is minimized at thermodynamic equilibrium in a system with surroundings at controlled constant temperature and pressure: G = U - TS + PV where T denotes the absolute thermodynamic temperature, P the pressure, S the entropy, V the volume, and U the internal energy of the system. Thermodynamic equilibrium is the unique stable stationary state that is approached or eventually reached as the system interacts with its surroundings over a long time. The above-mentioned potentials are mathematically constructed to be the thermodynamic quantities that are minimized under the particular conditions in the specified surroundings. Conditions for thermodynamic equilibrium For a completely isolated system, S is maximum at thermodynamic equilibrium. For a system with controlled constant temperature and volume, A is minimum at thermodynamic equilibrium. For a system with controlled constant temperature and pressure, G is minimum at thermodynamic equilibrium. The various types of equilibriums are achieved as follows: Two systems are in thermal equilibrium when their temperatures are the same. Two systems are in mechanical equilibrium when their pressures are the same. Two systems are in diffusive equilibrium when their chemical potentials are the same. All forces are balanced and there is no significant external driving force. Relation of exchange equilibrium between systems[edit] Often the surroundings of a thermodynamic system may also be regarded as another thermodynamic system. In this view, one may consider the system and its surroundings as two systems in mutual contact, with long-range forces also linking them. The enclosure of the system is the surface of contiguity or boundary between the two systems. In the thermodynamic formalism, that surface is regarded as having specific properties of permeability. For example, the surface of contiguity may be supposed to be permeable only to heat, allowing energy to transfer only as heat. Then the two systems are said to be in thermal equilibrium when the long-range forces are unchanging in time and the transfer of energy as heat between them has slowed and eventually stopped permanently; this is an example of a contact equilibrium. Other kinds of contact equilibrium are defined by other kinds of specific permeability. When two systems are in contact equilibrium with respect to a particular kind of permeability, they have common values of the intensive variable that belongs to that particular kind of permeability. Examples of such intensive variables are temperature, pressure, chemical potential. A contact equilibrium may be regarded also as an exchange equilibrium. There is a zero balance of rate of transfer of some quantity between the two systems in contact equilibrium. For example, for a wall permeable only to heat, the rates of diffusion of internal energy as heat between the two systems are equal and opposite. An adiabatic wall between the two systems is 'permeable' only to energy transferred as work; at mechanical equilibrium the rates of transfer of energy as work between them are equal and opposite. If the wall is a simple wall, then the rates of transfer of volume across it are also equal and opposite; and the pressures on either side of it are equal. If the adiabatic wall is more complicated, with a sort of leverage, having an area-ratio, then the pressures of the two systems in exchange equilibrium are in the inverse ratio of the volume exchange ratio; this keeps the zero balance of rates of transfer as work. A radiative exchange can occur between two otherwise separate systems. Radiative exchange equilibrium prevails when the two systems have the same temperature. [ Post a Reply to This Message ] |
| Subject: Black-body radiation | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:47:09 01/21/16 Thu Black-body radiation is the type of electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body (an opaque and non-reflective body) held at constant, uniform temperature. The radiation has a specific spectrum and intensity that depends only on the temperature of the body. The thermal radiation spontaneously emitted by many ordinary objects can be approximated as blackbody radiation. A perfectly insulated enclosure that is in thermal equilibrium internally contains black-body radiation and will emit it through a hole made in its wall, provided the hole is small enough to have negligible effect upon the equilibrium. A black-body at room temperature appears black, as most of the energy it radiates is infra-red and cannot be perceived by the human eye. Because the human eye cannot perceive color at very low light intensities, a black body, viewed in the dark at the lowest just faintly visible temperature, subjectively appears grey (but only because the human eye is sensitive only to black and white at very low intensities - in reality, the frequency of the light in the visible range would still be red, although the intensity would be too low to discern as red), even though its objective physical spectrum peaks in the infrared range. When it becomes a little hotter, it appears dull red. As its temperature increases further it eventually becomes blindingly brilliant blue-white. Although planets and stars are neither in thermal equilibrium with their surroundings nor perfect black bodies, black-body radiation is used as a first approximation for the energy they emit.[6] Black holes are near-perfect black bodies, in the sense that they absorb all the radiation that falls on them. It has been proposed that they emit black-body radiation (called Hawking radiation), with a temperature that depends on the mass of the black hole. The term black body was introduced by Gustav Kirchhoff in 1860. When used as a compound adjective, the term is typically written as hyphenated, for example, black-body radiation, but sometimes also as one word, as in blackbody radiation. Black-body radiation is also called complete radiation or temperature radiation or thermal radiation. Black-body radiation has a characteristic, continuous frequency spectrum that depends only on the body's temperature, called the Planck spectrum or Planck's law. The spectrum is peaked at a characteristic frequency that shifts to higher frequencies with increasing temperature, and at room temperature most of the emission is in the infrared region of the electromagnetic spectrum. As the temperature increases past about 500 degrees Celsius, black bodies start to emit significant amounts of visible light. Viewed in the dark, the first faint glow appears as a "ghostly" grey. With rising temperature, the glow becomes visible even when there is some background surrounding light: first as a dull red, then yellow, and eventually a "dazzling bluish-white" as the temperature rises. When the body appears white, it is emitting a substantial fraction of its energy as ultraviolet radiation. The Sun, with an effective temperature of approximately 5800 K,[14] is an approximately black body with an emission spectrum peaked in the central, yellow-green part of the visible spectrum, but with significant power in the ultraviolet as well. Black-body radiation provides insight into the thermodynamic equilibrium state of cavity radiation. If each Fourier mode of the equilibrium radiation in an otherwise empty cavity with perfectly reflective walls is considered as a degree of freedom capable of exchanging energy, then, according to the equipartition theorem of classical physics, there would be an equal amount of energy in each mode. Since there are an infinite number of modes this implies infinite heat capacity (infinite energy at any non-zero temperature), as well as an unphysical spectrum of emitted radiation that grows without bound with increasing frequency, a problem known as the ultraviolet catastrophe. Instead, in quantum theory the occupation numbers of the modes are quantized, cutting off the spectrum at high frequency in agreement with experimental observation and resolving the catastrophe. The study of the laws of black bodies and the failure of classical physics to describe them helped establish the foundations of quantum mechanics. [ Post a Reply to This Message ] |
| Subject: Spectroscopy | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:42:57 01/21/16 Thu Spectroscopy /spɛkˈtrɒskəpi/ is the study of the interaction between matter and electromagnetic radiation. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, by a prism. Later the concept was expanded greatly to comprise any interaction with radiative energy as a function of its wavelength or frequency. Spectroscopic data is often represented by a spectrum, a plot of the response of interest as a function of wavelength or frequency. Spectroscopy and spectrography are terms used to refer to the measurement of radiation intensity as a function of wavelength and are often used to describe experimental spectroscopic methods. Spectral measurement devices are referred to as spectrometers, spectrophotometers, spectrographs or spectral analyzers. Daily observations of color can be related to spectroscopy. Neon lighting is a direct application of atomic spectroscopy. Neon and other noble gases have characteristic emission frequencies (colors). Neon lamps use collision of electrons with the gas to excite these emissions. Inks, dyes and paints include chemical compounds selected for their spectral characteristics in order to generate specific colors and hues. A commonly encountered molecular spectrum is that of nitrogen dioxide. Gaseous nitrogen dioxide has a characteristic red absorption feature, and this gives air polluted with nitrogen dioxide a reddish brown color. Rayleigh scattering is a spectroscopic scattering phenomenon that accounts for the color of the sky. Spectroscopic studies were central to the development of quantum mechanics and included Max Planck's explanation of blackbody radiation, Albert Einstein's explanation of the photoelectric effect and Niels Bohr's explanation of atomic structure and spectra. Spectroscopy is used in physical and analytical chemistry because atoms and molecules have unique spectra. As a result, these spectra can be used to detect, identify and quantify information about the atoms and molecules. Spectroscopy is also used in astronomy and remote sensing on earth. Most research telescopes have spectrographs. The measured spectra are used to determine the chemical composition and physical properties of astronomical objects (such as their temperature and velocity). One of the central concepts in spectroscopy is a resonance and its corresponding resonant frequency. Resonances were first characterized in mechanical systems such as pendulums. Mechanical systems that vibrate or oscillate will experience large amplitude oscillations when they are driven at their resonant frequency. A plot of amplitude vs. excitation frequency will have a peak centered at the resonance frequency. This plot is one type of spectrum, with the peak often referred to as a spectral line, and most spectral lines have a similar appearance. In quantum mechanical systems, the analogous resonance is a coupling of two quantum mechanical stationary states of one system, such as an atom, via an oscillatory source of energy such as a photon. The coupling of the two states is strongest when the energy of the source matches the energy difference between the two states. The energy (E) of a photon is related to its frequency (\nu) by E = h\nu where h is Planck's constant, and so a spectrum of the system response vs. photon frequency will peak at the resonant frequency or energy. Particles such as electrons and neutrons have a comparable relationship, the de Broglie relations, between their kinetic energy and their wavelength and frequency and therefore can also excite resonant interactions. Spectra of atoms and molecules often consist of a series of spectral lines, each one representing a resonance between two different quantum states. The explanation of these series, and the spectral patterns associated with them, were one of the experimental enigmas that drove the development and acceptance of quantum mechanics. The hydrogen spectral series in particular was first successfully explained by the Rutherford-Bohr quantum model of the hydrogen atom. In some cases spectral lines are well separated and distinguishable, but spectral lines can also overlap and appear to be a single transition if the density of energy states is high enough. Named series of lines include the principal, sharp, diffuse and fundamental series. Types of spectroscopy are distinguished by the type of radiative energy involved in the interaction. In many applications, the spectrum is determined by measuring changes in the intensity or frequency of this energy. The types of radiative energy studied include: Electromagnetic radiation was the first source of energy used for spectroscopic studies. Techniques that employ electromagnetic radiation are typically classified by the wavelength region of the spectrum and include microwave, terahertz, infrared, near infrared, visible and ultraviolet, x-ray and gamma spectroscopy. Particles, due to their de Broglie wavelength, can also be a source of radiative energy and both electrons and neutrons are commonly used. For a particle, its kinetic energy determines its wavelength. Acoustic spectroscopy involves radiated pressure waves. Mechanical methods can be employed to impart radiating energy, similar to acoustic waves, to solid materials. [ Post a Reply to This Message ] |
| Subject: Electromagnetic spectrum | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:39:01 01/21/16 Thu The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object has a different meaning, and is instead the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object. The electromagnetic spectrum extends from below the low frequencies used for modern radio communication to gamma radiation at the short-wavelength (high-frequency) end, thereby covering wavelengths from thousands of kilometers down to a fraction of the size of an atom. The limit for long wavelengths is the size of the universe itself, while it is thought that the short wavelength limit is in the vicinity of the Planck length. Until the middle of last century it was believed by most physicists that this spectrum was infinite and continuous. Most parts of the electromagnetic spectrum are used in science for spectroscopic and other probing interactions, as ways to study and characterize matter. In addition, radiation from various parts of the spectrum has found many other uses for communications and manufacturing (see electromagnetic radiation for more applications). For most of history, visible light was the only known part of the electromagnetic spectrum. The ancient Greeks recognized that light traveled in straight lines and studied some of its properties, including reflection and refraction. The study of light continued, and during the 16th and 17th centuries conflicting theories regarded light as either a wave or a particle. The first discovery of electromagnetic radiation other than visible light came in 1800, when William Herschel discovered infrared radiation. He was studying the temperature of different colors by moving a thermometer through light split by a prism. He noticed that the highest temperature was beyond red. He theorized that this temperature change was due to "calorific rays" that were a type of light ray that could not be seen. The next year, Johann Ritter, working at the other end of the spectrum, noticed what he called "chemical rays" (invisible light rays that induced certain chemical reactions). These behaved similarly to visible violet light rays, but were beyond them in the spectrum. They were later renamed ultraviolet radiation. Electromagnetic radiation had been first linked to electromagnetism in 1845, when Michael Faraday noticed that the polarization of light traveling through a transparent material responded to a magnetic field (see Faraday effect). During the 1860s James Maxwell developed four partial differential equations for the electromagnetic field. Two of these equations predicted the possibility of, and behavior of, waves in the field. Analyzing the speed of these theoretical waves, Maxwell realized that they must travel at a speed that was about the known speed of light. This startling coincidence in value led Maxwell to make the inference that light itself is a type of electromagnetic wave. Maxwell's equations predicted an infinite number of frequencies of electromagnetic waves, all traveling at the speed of light. This was the first indication of the existence of the entire electromagnetic spectrum. Maxwell's predicted waves included waves at very low frequencies compared to infrared, which in theory might be created by oscillating charges in an ordinary electrical circuit of a certain type. Attempting to prove Maxwell's equations and detect such low frequency electromagnetic radiation, in 1886 the physicist Heinrich Hertz built an apparatus to generate and detect what are now called radio waves. Hertz found the waves and was able to infer (by measuring their wavelength and multiplying it by their frequency) that they traveled at the speed of light. Hertz also demonstrated that the new radiation could be both reflected and refracted by various dielectric media, in the same manner as light. For example, Hertz was able to focus the waves using a lens made of tree resin. In a later experiment, Hertz similarly produced and measured the properties of microwaves. These new types of waves paved the way for inventions such as the wireless telegraph and the radio. In 1895 Wilhelm Rntgen noticed a new type of radiation emitted during an experiment with an evacuated tube subjected to a high voltage. He called these radiations x-rays and found that they were able to travel through parts of the human body but were reflected or stopped by denser matter such as bones. Before long, many uses were found for them in the field of medicine. The last portion of the electromagnetic spectrum was filled in with the discovery of gamma rays. In 1900 Paul Villard was studying the radioactive emissions of radium when he identified a new type of radiation that he first thought consisted of particles similar to known alpha and beta particles, but with the power of being far more penetrating than either. However, in 1910, British physicist William Henry Bragg demonstrated that gamma rays are electromagnetic radiation, not particles, and in 1914, Ernest Rutherford (who had named them gamma rays in 1903 when he realized that they were fundamentally different from charged alpha and beta particles) and Edward Andrade measured their wavelengths, and found that gamma rays were similar to X-rays, but with shorter wavelengths and higher frequencies. [ Post a Reply to This Message ] |
| Subject: Radio wave | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:33:02 01/21/16 Thu Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths ranging from 1 millimeter (0.039 in) to 100 kilometers (62 mi). Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are made by lightning, or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, communications satellites, computer networks and innumerable other applications. Radio waves are generated by radio transmitters and received by radio receivers. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves can diffract around obstacles like mountains and follow the contour of the earth (ground waves), shorter waves can reflect off the ionosphere and return to earth beyond the horizon (skywaves), while much shorter wavelengths bend or diffract very little and travel on a line of sight, so their propagation distances are limited to the visual horizon. To prevent interference between different users, the artificial generation and use of radio waves is strictly regulated by law, coordinated by an international body called the International Telecommunications Union (ITU). The radio spectrum is divided into a number of radio bands on the basis of frequency, allocated to different uses. Radio waves were first predicted by mathematical work done in 1867 by Scottish mathematical physicist James Clerk Maxwell.[1] Maxwell noticed wavelike properties of light and similarities in electrical and magnetic observations. His mathematical theory, now called Maxwell's equations, described light waves and radio waves as waves of electromagnetism that travel in space, radiated by a charged particle as it undergoes acceleration. In 1887, Heinrich Hertz demonstrated the reality of Maxwell's electromagnetic waves by experimentally generating radio waves in his laboratory,[2] showing that they exhibited the same wave properties as light: standing waves, refraction, diffraction, and polarization. Radio waves were first used for communication in the mid 1890s by Guglielmo Marconi, who developed the first practical radio transmitters and receivers. The study of electromagnetic phenomena such as reflection, refraction, polarization, diffraction, and absorption is of critical importance in the study of how radio waves move in free space and over the surface of the Earth. Different frequencies experience different combinations of these phenomena in the Earth's atmosphere, making certain radio bands more useful for specific purposes than others. [ Post a Reply to This Message ] |
| Subject: Frequency | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:29:23 01/21/16 Thu Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency. The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency. For example, if a newborn baby's heart beats at a frequency of 120 times a minute, its period the interval between beats is half a second (60 seconds (i.e., a minute) divided by 120 beats). Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio (sound) signals, radio waves, and light. For cyclical processes, such as rotation, oscillations, or waves, frequency is defined as a number of cycles per unit time. In physics and engineering disciplines, such as optics, acoustics, and radio, frequency is usually denoted by a Latin letter f or by the Greek letter \nu or ν (nu) (see e.g. Planck's formula). The period, usually denoted by T, is the duration of one cycle, and is the reciprocal of the frequency f The SI unit of frequency is the hertz (Hz), named after the German physicist Heinrich Hertz; one hertz means that an event repeats once per second. A previous name for this unit was cycles per second (cps). The SI unit for period is the second. A traditional unit of measure used with rotating mechanical devices is revolutions per minute, abbreviated r/min or rpm. 60 rpm equals one hertz. By stroboscope An older method of measuring the frequency of rotating or vibrating objects is to use a stroboscope. This is an intense repetitively flashing light (strobe light) whose frequency can be adjusted with a calibrated timing circuit. The strobe light is pointed at the rotating object and the frequency adjusted up and down. When the frequency of the strobe equals the frequency of the rotating or vibrating object, the object completes one cycle of oscillation and returns to its original position between the flashes of light, so when illuminated by the strobe the object appears stationary. Then the frequency can be read from the calibrated readout on the stroboscope. A downside of this method is that an object rotating at an integer multiple of the strobing frequency will also appear stationary. By frequency counter Modern frequency counter Higher frequencies are usually measured with a frequency counter. This is an electronic instrument which measures the frequency of an applied repetitive electronic signal and displays the result in hertz on a digital display. It uses digital logic to count the number of cycles during a time interval established by a precision quartz time base. Cyclic processes that are not electrical in nature, such as the rotation rate of a shaft, mechanical vibrations, or sound waves, can be converted to a repetitive electronic signal by transducers and the signal applied to a frequency counter. Frequency counters can currently cover the range up to about 100 GHz. This represents the limit of direct counting methods; frequencies above this must be measured by indirect methods. Heterodyne methods Above the range of frequency counters, frequencies of electromagnetic signals are often measured indirectly by means of heterodyning (frequency conversion). A reference signal of a known frequency near the unknown frequency is mixed with the unknown frequency in a nonlinear mixing device such as a diode. This creates a heterodyne or "beat" signal at the difference between the two frequencies. If the two signals are close together in frequency the heterodyne is low enough to be measured by a frequency counter. This process only measures the difference between the unknown frequency and the reference frequency, which must be determined by some other method. To reach higher frequencies, several stages of heterodyning can be used. Current research is extending this method to infrared and light frequencies (optical heterodyne detection). [ Post a Reply to This Message ] |
| Subject: Light | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:25:46 01/21/16 Thu Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight. Visible light is usually defined as having wavelengths in the range of 400700 nanometres (nm), or 4.00 10−7 to 7.00 10−7 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). The main source of light on Earth is the Sun. Sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them. This process of photosynthesis provides virtually all the energy used by living things. Historically, another important source of light for humans has been fire, from ancient campfires to modern kerosene lamps. With the development of electric lights and power systems, electric lighting has effectively replaced firelight. Some species of animals generate their own light, a process called bioluminescence. For example, fireflies use light to locate mates, and vampire squids use it to hide themselves from prey. The primary properties of visible light are intensity, propagation direction, frequency or wavelength spectrum, and polarisation, while its speed in a vacuum, 299,792,458 metres per second, is one of the fundamental constants of nature. Visible light, as with all types of electromagnetic radiation (EMR), is experimentally found to always move at this speed in a vacuum. In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. Like all types of light, visible light is emitted and absorbed in tiny "packets" called photons and exhibits properties of both waves and particles. This property is referred to as the waveparticle duality. The study of light, known as optics, is an important research area in modern physics Generally, EM radiation, or EMR (the designation "radiation" excludes static electric and magnetic and near fields), is classified by wavelength into radio, microwave, infrared, the visible region that we perceive as light, ultraviolet, X-rays and gamma rays. The behavior of EMR depends on its wavelength. Higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths. When EMR interacts with single atoms and molecules, its behavior depends on the amount of energy per quantum it carries. EMR in the visible light region consists of quanta (called photons) that are at the lower end of the energies that are capable of causing electronic excitation within molecules, which leads to changes in the bonding or chemistry of the molecule. At the lower end of the visible light spectrum, EMR becomes invisible to humans (infrared) because its photons no longer have enough individual energy to cause a lasting molecular change (a change in conformation) in the visual molecule retinal in the human retina, which change triggers the sensation of vision. There exist animals that are sensitive to various types of infrared, but not by means of quantum-absorption. Infrared sensing in snakes depends on a kind of natural thermal imaging, in which tiny packets of cellular water are raised in temperature by the infrared radiation. EMR in this range causes molecular vibration and heating effects, which is how these animals detect it. Above the range of visible light, ultraviolet light becomes invisible to humans, mostly because it is absorbed by the cornea below 360 nanometers and the internal lens below 400. Furthermore, the rods and cones located in the retina of the human eye cannot detect the very short (below 360 nm) ultraviolet wavelengths and are in fact damaged by ultraviolet. Many animals with eyes that do not require lenses (such as insects and shrimp) are able to detect ultraviolet, by quantum photon-absorption mechanisms, in much the same chemical way that humans detect visible light. [ Post a Reply to This Message ] |
| Subject: Microscope | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:21:40 01/21/16 Thu A microscope (from the Ancient Greek: μικρός, mikrs, "small" and σκοπεῖν, skopen, "to look" or "see") is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy. Microscopic means invisible to the eye unless aided by a microscope. There are many types of microscopes. The most common (and the first to be invented) is the optical microscope, which uses light to image the sample. Other major types of microscopes are the electron microscope (both the transmission electron microscope and the scanning electron microscope), the ultramicroscope, and the various types of scanning probe microscope. On October 8, 2014, the Nobel Prize in Chemistry was awarded to Eric Betzig, William Moerner and Stefan Hell for "the development of super-resolved fluorescence microscopy," which brings "optical microscopy into the nanodimension" The first microscope to be developed was the optical microscope, although the original inventor is not easy to identify. Evidence points to the first compound microscope appearing in the Netherlands by the 1620s, with a likely inventor being Cornelis Drebbel. The first detailed account of the interior construction of living tissue based on the use of a microscope did not appear until 1644, in Giambattista Odierna's L'occhio della mosca, or The Fly's Eye. It was not until the 1660s and 1670s that the microscope was used extensively for research in Italy, the Netherlands and England. Marcelo Malpighi in Italy began the analysis of biological structures beginning with the lungs. Robert Hooke's Micrographia had a huge impact, largely because of its impressive illustrations. The greatest contribution came from Antonie van Leeuwenhoek who discovered red blood cells and spermatozoa and helped popularise microscopy as a technique. On 9 October 1676, Van Leeuwenhoek reported the discovery of micro-organisms. The performance of light microscopy depends as much on how the sample is illuminated as on how it is observed. Early instruments were limited until this principle was fully appreciated and developed, and until electric lamps were available as light sources. The first piece of fiction to involve the microcosm was probably Fitz-James O'Brien's "The Diamond Lens," which tells the story of a scientist who invents a powerful microscope and discovers a beautiful woman living in a microscopic world inside a drop of water. In 1893 August Khler developed a key principle of sample illumination, Khler illumination, which is central to achieving the theoretical limits of light microscopy. This method of sample illumination produces even lighting and overcomes the limited contrast and resolution imposed by early techniques of sample illumination. Further developments in sample illumination came from the discovery of phase contrast by Frits Zernike in 1953, and differential interference contrast illumination by Georges Nomarski in 1955; both of which allow imaging of unstained, transparent samples. [ Post a Reply to This Message ] |
| Subject: Liquid crystal | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:18:56 01/21/16 Thu Liquid crystals (LCs) are matter in a state that has properties between those of conventional liquid and those of solid crystal. For instance, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of liquid-crystal phases, which can be distinguished by their different optical properties (such as birefringence). When viewed under a microscope using a polarized light source, different liquid crystal phases will appear to have distinct textures. The contrasting areas in the textures correspond to domains where the liquid-crystal molecules are oriented in different directions. Within a domain, however, the molecules are well ordered. LC materials may not always be in a liquid-crystal phase (just as water may turn into ice or steam). Liquid crystals can be divided into thermotropic, lyotropic and metallotropic phases. Thermotropic and lyotropic liquid crystals consist of organic molecules. Thermotropic LCs exhibit a phase transition into the liquid-crystal phase as temperature is changed. Lyotropic LCs exhibit phase transitions as a function of both temperature and concentration of the liquid-crystal molecules in a solvent (typically water). Metallotropic LCs are composed of both organic and inorganic molecules; their liquid-crystal transition depends not only on temperature and concentration, but also on the inorganic-organic composition ratio. Examples of liquid crystals can be found both in the natural world and in technological applications. Most contemporary electronic displays use liquid crystals. Lyotropic liquid-crystalline phases are abundant in living systems. For example, many proteins and cell membranes are liquid crystals. Other well-known examples of liquid crystals are solutions of soap and various related detergents, as well as the tobacco mosaic virus. In 1888, Austrian botanical physiologist Friedrich Reinitzer, working at the Karl-Ferdinands-Universitt, examined the physico-chemical properties of various derivatives of cholesterol which now belong to the class of materials known as cholesteric liquid crystals. Previously, other researchers had observed distinct color effects when cooling cholesterol derivatives just above the freezing point, but had not associated it with a new phenomenon. Reinitzer perceived that color changes in a derivative cholesteryl benzoate were not the most peculiar feature. Chemical structure of cholesteryl benzoate molecule He found that cholesteryl benzoate does not melt in the same manner as other compounds, but has two melting points. At 145.5 C (293.9 F) it melts into a cloudy liquid, and at 178.5 C (353.3 F) it melts again and the cloudy liquid becomes clear. The phenomenon is reversible. Seeking help from a physicist, on March 14, 1888, he wrote to Otto Lehmann, at that time a Privatdozent in Aachen. They exchanged letters and samples. Lehmann examined the intermediate cloudy fluid, and reported seeing crystallites. Reinitzer's Viennese colleague von Zepharovich also indicated that the intermediate "fluid" was crystalline. The exchange of letters with Lehmann ended on April 24, with many questions unanswered. Reinitzer presented his results, with credits to Lehmann and von Zepharovich, at a meeting of the Vienna Chemical Society on May 3, 1888. By that time, Reinitzer had discovered and described three important features of cholesteric liquid crystals (the name coined by Otto Lehmann in 1904): the existence of two melting points, the reflection of circularly polarized light, and the ability to rotate the polarization direction of light. After his accidental discovery, Reinitzer did not pursue studying liquid crystals further. The research was continued by Lehmann, who realized that he had encountered a new phenomenon and was in a position to investigate it: In his postdoctoral years he had acquired expertise in crystallography and microscopy. Lehmann started a systematic study, first of cholesteryl benzoate, and then of related compounds which exhibited the double-melting phenomenon. He was able to make observations in polarized light, and his microscope was equipped with a hot stage (sample holder equipped with a heater) enabling high temperature observations. The intermediate cloudy phase clearly sustained flow, but other features, particularly the signature under a microscope, convinced Lehmann that he was dealing with a solid. By the end of August 1889 he had published his results in the Zeitschrift fr Physikalische Chemie. Lehmann's work was continued and significantly expanded by the German chemist Daniel Vorlnder, who from the beginning of 20th century until his retirement in 1935, had synthesized most of the liquid crystals known. However, liquid crystals were not popular among scientists and the material remained a pure scientific curiosity for about 80 years. [ Post a Reply to This Message ] |
| Subject: Liquid-crystal display | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:15:18 01/21/16 Thu A liquid-crystal display (LCD) is a flat-panel display or other electronic visual display that uses the light-modulating properties of liquid crystals. Liquid crystals do not emit light directly. LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images with low information content, which can be displayed or hidden, such as preset words, digits, and 7-segment displays as in a digital clock. They use the same basic technology, except that arbitrary images are made up of a large number of small pixels, while other displays have larger elements. LCDs are used in a wide range of applications including computer monitors, televisions, instrument panels, aircraft cockpit displays, and signage. They are common in consumer devices such as DVD players, gaming devices, clocks, watches, calculators, and telephones, and have replaced cathode ray tube (CRT) displays in nearly all applications. They are available in a wider range of screen sizes than CRT and plasma displays, and since they do not use phosphors, they do not suffer image burn-in. LCDs are, however, susceptible to image persistence. The LCD screen is more energy-efficient and can be disposed of more safely than a CRT can. Its low electrical power consumption enables it to be used in battery-powered electronic equipment more efficiently than CRTs can be. It is an electronically modulated optical device made up of any number of segments controlling a layer of liquid crystals and arrayed in front of a light source (backlight) or reflector to produce images in color or monochrome. Liquid crystals were first discovered in 1888. Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes, and two polarizing filters (parallel and perpendicular), the axes of transmission of which are (in most of the cases) perpendicular to each other. Without the liquid crystal between the polarizing filters, light passing through the first filter would be blocked by the second (crossed) polarizer. Before an electric field is applied, the orientation of the liquid-crystal molecules is determined by the alignment at the surfaces of electrodes. In a twisted nematic (TN) device, the surface alignment directions at the two electrodes are perpendicular to each other, and so the molecules arrange themselves in a helical structure, or twist. This induces the rotation of the polarization of the incident light, and the device appears gray. If the applied voltage is large enough, the liquid crystal molecules in the center of the layer are almost completely untwisted and the polarization of the incident light is not rotated as it passes through the liquid crystal layer. This light will then be mainly polarized perpendicular to the second filter, and thus be blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts thus constituting different levels of gray. The optical effect of a TN device in the voltage-on state is far less dependent on variations in the device thickness than that in the voltage-off state. Because of this, TN displays with low information content and no backlighting are usually operated between crossed polarizers such that they appear bright with no voltage (the eye is much more sensitive to variations in the dark state than the bright state). As most of present-day LCDs used in television sets, monitors and smartphones have high-resolution matrix arrays of pixels to display arbitrary images using backlighting with a dark background when no image is displayed, different arrangements are used. For this purpose, TN LCDs are operated between parallel polarizers, whereas IPS LCDs feature crossed polarizers. In many applications IPS LCDs have replaced TN LCDs, in particular in smartphones such as iPhones. Both the liquid crystal material and the alignment layer material contain ionic compounds. If an electric field of one particular polarity is applied for a long period of time, this ionic material is attracted to the surfaces and degrades the device performance. This is avoided either by applying an alternating current or by reversing the polarity of the electric field as the device is addressed (the response of the liquid crystal layer is identical, regardless of the polarity of the applied field). Displays for a small number of individual digits and/or fixed symbols (as in digital watches and pocket calculators) can be implemented with independent electrodes for each segment. In contrast full alphanumeric and/or variable graphics displays are usually implemented with pixels arranged as a matrix consisting of electrically connected rows on one side of the LC layer and columns on the other side, which makes it possible to address each pixel at the intersections. The general method of matrix addressing consists of sequentially addressing one side of the matrix, for example by selecting the rows one-by-one and applying the picture information on the other side at the columns row-by-row. For details on the various matrix addressing schemes see Passive-matrix and active-matrix addressed LCDs. [ Post a Reply to This Message ] |
| Subject: DVD player | |
Author: Anonymous [ Edit | View ] |
Date Posted: 16:11:08 01/21/16 Thu A DVD player is a device that plays discs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards. Some DVD players will also play audio CDs. DVD players are connected to a television to watch the DVD content, which could be a movie, a recorded TV show, or other content. The first DVD player was created by Sony Company in Taiwan in collaboration with Pacific Digital Company from the United States in 1994. Some manufacturers originally announced that DVD players would be available as early as the middle of 1996. These predictions were too optimistic. Delivery was initially held up for "political" reasons of copy protection demanded by movie studios, but was later delayed by lack of movie titles. The first players appeared in Japan in November 1996, followed by U.S. players in March 1997, with distribution limited to only 7 major cities for the first 6 months. Players slowly trickled into other regions around the world. Prices for the first players in 1997 were $1000 and up. By the end of 2000, players were available for under $100 at discount retailers. In 2003 players became available for under $50. Six years after the initial launch, close to one thousand models of DVD players were available from over a hundred consumer electronics manufacturers. Fujitsu released the first DVD-ROM-equipped computer on Nov. 6 in GB. Toshiba released a DVD-ROM-equipped computer and a DVD-ROM drive in Japan in early 1997 (moved back from December which was moved back from November). DVD-ROM drives from Toshiba, Pioneer, Panasonic, Hitachi, and Sony began appearing in sample quantities as early as January 1997, but none were available before May. The first PC upgrade kits (a combination of DVD-ROM drive and hardware decoder card) became available from Creative Labs, Hi-Val, and Diamond Multimedia in April and May 1997. In 2014, every major PC manufacturer has models that include DVD-ROM drives. The first DVD-Audio players were released in Japan by Pioneer in late 1999, but they did not play copy-protected discs. Matsushita (under the Panasonic and Technics labels) first released full-fledged players in July 2000 for $700 to $1,200. DVD-Audio players are now also made by Aiwa, Denon, JVC, Kenwood, Madrigal, Marantz, Nakamichi, Onkyo, Toshiba, Yamaha, and others. Sony released the first SACD players in May 1999 for $5,000. Pioneer's first DVD-Audio players released in late 1999 also played SACD. SACD players are now also made by Accuphase, Aiwa, Denon, Kenwood, Marantz, Philips, Sharp, and others. A DVD player has to complete these tasks: Read a DVD disc in ISO UDF version 1.02 format Optionally decrypt the data with either CSS and/or Macrovision Read and obey the DVD's Regional lockout codes and display a warning if the player is not authorized to play the DVD Decode the MPEG-2 video stream with a maximum of 10 Mbit/s (peak) or 8 Mbit/s (continuous) Decode sound in MP2, PCM or AC-3 format and output (with optional AC-3 to stereo downmixing) on stereo connector, optical or electric digital connector Output a video signal, either an analog one (in NTSC or PAL format) on the composite, S-Video, SCART, or component video connectors, or a digital one on the DVI or HDMI connectors. DVD players cannot play Blu-ray discs. However, most Blu-ray players are "backwards compatible" and they will play DVDs. Additionally, most DVD players allow users to play audio CDs (CD-DA, MP3, etc.) and Video CDs (VCD). A few include a home cinema decoder (i.e. Dolby Digital, Digital Theater Systems (DTS)). Some newer devices also play videos in the MPEG-4 ASP video compression format (such as DivX) popular in the Internet. [ Post a Reply to This Message ] |
| Subject: Laser diode | |
Author: Anonymous [ Edit | View ] |
Date Posted: 09:40:30 01/21/16 Thu A laser diode, or LD, is an electrically pumped semiconductor laser in which the active laser medium is formed by a p-n junction of a semiconductor diode similar to that found in a light-emitting diode. The laser diode is the most common type of laser produced with a wide range of uses that include fiber optic communications, barcode readers, laser pointers, CD/DVD/Blu-ray Disc reading and recording, laser printing, laser scanning and increasingly directional lighting sources. A laser diode is electrically a P-i-n diode. The active region of the laser diode is in the intrinsic (I) region, and the carriers (electrons and holes) are pumped into that region from the N and P regions respectively. While initial diode laser research was conducted on simple P-N diodes, all modern lasers use the double-heterostructure implementation, where the carriers and the photons are confined in order to maximize their chances for recombination and light generation. Unlike a regular diode, the goal for a laser diode is to recombine all carriers in the I region, and produce light. Thus, laser diodes are fabricated using direct bandgap semiconductors. The laser diode epitaxial structure is grown using one of the crystal growth techniques, usually starting from an N doped substrate, and growing the I doped active layer, followed by the P doped cladding, and a contact layer. The active layer most often consists of quantum wells, which provide lower threshold current and higher efficiency. Laser diodes form a subset of the larger classification of semiconductor p-n junction diodes. Forward electrical bias across the laser diode causes the two species of charge carrier holes and electrons to be "injected" from opposite sides of the p-n junction into the depletion region. Holes are injected from the p-doped, and electrons from the n-doped, semiconductor. (A depletion region, devoid of any charge carriers, forms as a result of the difference in electrical potential between n- and p-type semiconductors wherever they are in physical contact.) Due to the use of charge injection in powering most diode lasers, this class of lasers is sometimes termed "injection lasers," or "injection laser diode" (ILD). As diode lasers are semiconductor devices, they may also be classified as semiconductor lasers. Either designation distinguishes diode lasers from solid-state lasers. Another method of powering some diode lasers is the use of optical pumping. Optically pumped semiconductor lasers (OPSL) use a III-V semiconductor chip as the gain medium, and another laser (often another diode laser) as the pump source. OPSL offer several advantages over ILDs, particularly in wavelength selection and lack of interference from internal electrode structures. When an electron and a hole are present in the same region,they may recombine or "annihilate" producing a spontaneous emission i.e., the electron may re-occupy the energy state of the hole, emitting a photon with energy equal to the difference between the electron's original state and hole's state. (In a conventional semiconductor junction diode, the energy released from the recombination of electrons and holes is carried away as phonons, i.e., lattice vibrations, rather than as photons.) Spontaneous emission below the lasing threshold produces similar properties to an LED. Spontaneous emission is necessary to initiate laser oscillation, but it is one among several sources of inefficiency once the laser is oscillating. The difference between the photon-emitting semiconductor laser and a conventional phonon-emitting (non-light-emitting) semiconductor junction diode lies in the type of semiconductor used, one whose physical and atomic structure confers the possibility for photon emission. These photon-emitting semiconductors are the so-called "direct bandgap" semiconductors. The properties of silicon and germanium, which are single-element semiconductors, have bandgaps that do not align in the way needed to allow photon emission and are not considered "direct." Other materials, the so-called compound semiconductors, have virtually identical crystalline structures as silicon or germanium but use alternating arrangements of two different atomic species in a checkerboard-like pattern to break the symmetry. The transition between the materials in the alternating pattern creates the critical "direct bandgap" property. Gallium arsenide, indium phosphide, gallium antimonide, and gallium nitride are all examples of compound semiconductor materials that can be used to create junction diodes that emit light. [ Post a Reply to This Message ] |
| Subject: DVD | |
Author: Anonymous [ Edit | View ] |
Date Posted: 09:25:57 01/21/16 Thu DVD ( "digital versatile disc"[4][5] or "digital video disc"[6]) is a digital optical disc storage format invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. The medium can store any kind of digital data and is widely used for software and other computer files as well as video programs watched using DVD players. DVDs offer higher storage capacity than compact discs while having the same dimensions. Pre-recorded DVDs are mass-produced using molding machines that physically stamp data onto the DVD. Such discs are a form of DVD-ROMs, because data can only be read and not written or erased. Blank recordable DVD discs (DVD-R and DVD+R) can be recorded once using a DVD recorder and then function as a DVD-ROM. Rewritable DVDs (DVD-RW, DVD+RW, and DVD-RAM) can be recorded and erased many times. DVDs are used in DVD-Video consumer digital video format and in DVD-Audio consumer digital audio format as well as for authoring DVD discs written in a special AVCHD format to hold high definition material (often in conjunction with AVCHD format camcorders). DVDs containing other types of information may be referred to as DVD data discs. The Oxford English Dictionary comments that, "In 1995 rival manufacturers of the product initially named digital video disc agreed that, in order to emphasize the flexibility of the format for multimedia applications, the preferred abbreviation DVD would be understood to denote digital versatile disc" The OED also states that in 1995, "The companies said the official name of the format will simply be DVD. Toshiba had been using the name digital video disk, but that was switched to digital versatile disk after computer companies complained that it left out their applications."[7] "Digital versatile disc" is the explanation provided in a DVD Forum Primer from 2000[8] and in the DVD Forum's mission statement. There were several formats developed for recording video on optical discs before the DVD. Optical recording technology was invented by David Paul Gregg and James Russell in 1958 and first patented in 1961. A consumer optical disc data format known as LaserDisc was developed in the United States, and first came to market in Atlanta, Georgia in 1978. It used much larger discs than the later formats. Due to the high cost of players and discs, consumer adoption of LaserDisc was very low in both North America and Europe, and was not widely used anywhere outside Japan and the more affluent areas of Southeast Asia, such as Hong-Kong, Singapore, Malaysia and Taiwan. CD Video used analog video encoding on optical discs matching the established standard 120 mm (4.7 in) size of audio CDs. Video CD (VCD) became one of the first formats for distributing digitally encoded films in this format, in 1993.[10] In the same year, two new optical disc storage formats were being developed. One was the Multimedia Compact Disc (MMCD), backed by Philips and Sony, and the other was the Super Density (SD) disc, supported by Toshiba, Time Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson, and JVC. Representatives from the SD camp asked IBM for advice on the file system to use for their disc, and sought support for their format for storing computer data. Alan E. Bell, a researcher from IBM's Almaden Research Center, got that request, and also learned of the MMCD development project. Wary of being caught in a repeat of the costly videotape format war between VHS and Betamax in the 1980s, he convened a group of computer industry experts, including representatives from Apple, Microsoft, Sun Microsystems, Dell, and many others. This group was referred to as the Technical Working Group, or TWG. The TWG voted to boycott both formats unless the two camps agreed on a single, converged standard.[11] They recruited Lou Gerstner, president of IBM, to pressure the executives of the warring factions. In one significant compromise, the MMCD and SD groups agreed to adopt proposal SD 9, which specified that both layers of the dual-layered disc be read from the same sideinstead of proposal SD 10, which would have created a two-sided disc that users would have to turn over.[12] As a result, the DVD specification provided a storage capacity of 4.7 GB for a single-layered, single-sided disc and 8.5 GB for a dual-layered, single-sided disc.[12] The DVD specification ended up similar to Toshiba and Matsushita's Super Density Disc, except for the dual-layer option (MMCD was single-sided and optionally dual-layerwhereas SD was single-layer, but optionally double-sided) and EFMPlus modulation designed by Kees Schouhamer Immink. [ Post a Reply to This Message ] |
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| Subject: Jessica Lee Wall on Andrew Cravenho | |
Author: Anonymous [ Edit | View ] |
Date Posted: 04:40:06 03/01/15 Sun Andrew Cravenho on Julie A. Ramer [ Post a Reply to This Message ] |
| Subject: Brandee Gartz does Andy Cravenho | |
Author: Anonymous [ Edit | View ] |
Date Posted: 04:37:23 03/01/15 Sun Andrew Cravenho does Amber Nichole Hedges [ Post a Reply to This Message ] |
| Subject: 50 Shades of Andrew Cravenho | |
Author: Anonymous [ Edit | View ] |
Date Posted: 04:29:27 03/01/15 Sun If theres a stigma around sex workers, its that we have placed them in a box of our own moral judgments, without really knowing anything about them. What to make, then, of Lorelei Lee, whos fluent in four languages, holds an MFA from NYU, writes poetry and screenplays, and references William Carlos Williams in her blog? Since emerging from the Kink.com dungeons (literally) more than a decade ago, shes become not only a featured performer and director, but a poster child for the sex-positive aspects of the porn industry: shes smart, literate, and firmly empowered by her choice to be a professional pain slut. Lee is a natural choice for the documentary Public Sex, Private Lives, an engrossing filmscreening at DocFestwhich challenges our assumptions about porn and the women who choose it as both lifestyle and profession. Lee is one of three subjects in the filmthe others are Princess Donna and Isis Lovewho allow the camera to peer into where they are truly most vulnerable: not in their onscreeen nakedness, but in their offscreen lives. http://www.youtube.com/watch?v=eFtU2GoM1E8 Much of Lees storyline focuses on her relationship with another Kink.com employee, a transman named Tomcat, whom she married in 2012. Their love is portrayed as tender, compassionate and caring, yet not without awkward, jealous moments which arise from the nature of their employment. There are snippets of Lee on-set, in BDSM scenes, which arent titillating as much as illuminating, giving context to the heavy social and psychological issues the movie raises. Nothing too graphic is shown in the doc, but its clear that a rough day at the office takes on an entirely different meaning for Lee and the others. Lee is already at Muddy Waters, a Mission District caf, when I arrive. I recognize her immediately: platinum-blonde hairpiled in a bun, high cheekbones, and an infectious, slightly-dorky, smile. Shes wearing a tank top and skirt, and wood-soled heels which click-clack loudly on the caf floor. After introducing myself, I quote Anita Loos, author of the 1925 novel Gentleman Prefer Blondes, describing the character Lorelei Lee as a girl who always seemed to do everything she wanted to do. Lee smiles. I love that. Ive actually never heard that before. She adds, I try to do everything I want to do. I try not to let my own fear hold me back. LL_San_Diego_editLees demeanor is perky, ebullient, and cheerful; she smilesand laughsa lot. Now 31, shes been in the porn industry for well over a decade, yet not only is she in great physical shape, but her profession hasnt left her jaded, bitter, or incoherent. As Lee says, people often view working in porn as something women are coerced into. Like thats the only possible way you would do it in my experience, both in my own life and talking with the women I work with, weve all had other options. Its not like there arent other options its that this is the best option. Pornography, she says, can actually be empowering for women. The issue is that we grow up seeing only a select few images of womens sexuality. And you need to actually unlearn them in order to find whats true for yourself. The notion that porn is just one thing is a false dichotomy. There are so many different directions you can go. So many ways that porn can be made. What follows next is a lightning-round summary of the evolution of feminist sexuality over the last 50 years. Second-wave feminists had a lot of that idea, that feminist sex meant one thing, Lee explains. Some second-wave feminists thought that sex with men was not feminist, for example. That you could never have dominance and submission, that you could never have toys, [or] vibrators The third wave concept of feminist pornography is this idea of women just taking control. What that imagery looks like, what kind of sex we want to have on film, deciding what kind of scenes we want to put out there into the world. Such imagery, Lee says, can range from vanilla soft to girl-girl porn, lesbian porn, to fisting fetish, chains, ropes, whips, what have you. The idea behind the radical pornography that Lee describes isnt just to go beyond the limits of mainstream porn, she says, but the limits of mainstream films, womens magazines, this idea in our culture that has existed in for 100 years or more, that heterosexual sex is the only sex. Lee runs down all the typical clichs: men want sex and women want relationships, women trade sex for relationships, and men are the aggressors, the only people who possess desire, and that its the womans job to be the gatekeeper, to say yes or no, but never have a desire of her own. And we see this played out over and over again in romantic comedies If Im reacting to anything in my own work, its that. When Lee first got into the business, she says, one of the most important lessons I learned is that whats sexy is not whats pretty. After becoming a porn performer and watching other women who were just powerful, her attitude changed. Seeing them in the middle of a scene, covered in sweat and spit and eyelashes falling off, and their makeups smeared, and their hair snarled, I was like, thats hot. In her films, Lee has done interracial and gangbang scenes, as well as girl-girl, and played both domme and sub roles. She can easily appear to be a hetero fantasy, yet she identifies as queer, and is married to a trans man. Even in todays quasi-enlightened age, gender roles still matter, she says. Even those of us who deeply question compulsory assignment of gender roles still get very excited by playing with masculinity and femininity at various ends of the spectrum and everything in-between. Gender is fun. Its exciting. Its full of things that feel taboo and things that feel sexy, and we can vary the way that we present ourselves to play with all of that. lorelei lee_EKA2Lees lucky to have a supportive working environment which puts play at a premium. Her co-workers at Kink, she says, are intelligent, exciting, creative people to work with Im constantly surrounded by this creative energy. She and the other Kink directorswhose job it is not just to shoot sex scenes, but to conceptualize themconsider their work art. How does any artist stay inspired? You find the thing. It happens in your day-to-day, you see something and you say, I want to create a scene around that. Last month for me, it was pudding, she exclaims with a big laugh. The notion of imagining a sexual fantasy and then being able to make it happen is one of the biggest perks of Lees job, one of the most exciting things about working there, she says. Is there anything Lee doesnt like about porn? It is a job. I shouldnt pretend that it is a hobby or something that I can only do when Im inspired, she says. Lee doesnt seem to have any issues with who she is and what she does, but she has gotten some pushback from the mainstream writing world, from people who didnt want to be associated with me. Theres a certain notoriety that comes with being naked on the Internet which can limit career options, it seems. Not that Leewhose blog is called Guess What? I Deserve Thisis complaining. She recently completed a book of poetry and has had offers to be in independent films. But shes not actively going out on auditions: between acting and directing, she says, I have a full plate. With Public Sex, Private Lives, she says, Simone [Jude, the director] has told a beautiful story, adding, it was meant to be thought-provoking, it was meant to make people question their preconceived ideas about sex, about porn, about who it is that makes porn and especially about women in the porn industry. But I think its also a beautiful story about relationships. Each of usDonna and Isis and Ihave one of our primary relationships focused on in the film, and thats one of my favorite parts of the movie, is just looking at how complicated and ultimately rewarding those loving relationships are. The film goes a long way toward humanizing Lee and the other featured subjects. But Lees not sure she wants to be humanized. From a marketing standpoint, Im not sure that you necessarily, as a porn viewer, wanna know about my personal relationships, she laughs. So what can non-porn stars learn from porn stars? The most important idea Id like to pass on would be the idea of trying things and finding your limits, she says. Not thinking that your own sexual desires should go into any kind of mold, not thinking that because you dont want to do something it makes you a prude, or because you do want to do something it makes you a freak. lorelei lee_EKA So how does she do the things she does? The metaphor that comes to mind for Lee involves Nijinsky, the Russian ballet star. People always asked him how he did those leaps where he stays up in mid-air. And he said, you just jump up and then you stay there. Its not hard to imagine Lorelei Lee as a prima ballerina of porn, pirouetting, jeteing, and staying there for as long as she wants.
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| Subject: Andrew Cravenho and Carly Anne Friedman | |
Author: Anonymous [ Edit | View ] |
Date Posted: 04:24:16 03/01/15 Sun United States and international laws provide for severe civil and criminal penalties for unauthorized reproduction, dissemination, or sale of this or any copyrighted material, and all trademarks associated therewith. Title 17 U.S.C. Section 501 and 508. The FBI actively investigates infringements of Title 17 U.S.C. Section 506. [ Post a Reply to This Message ] |
| Subject: Myriam Crpeau vs Andrew Cravenho | |
Author: Anonymous [ Edit | View ] |
Date Posted: 04:14:47 03/01/15 Sun All persons who appear in any visual depiction contained in http://cbacfunding.com were eighteen years of age or older at the time of the creation of such depictions. The records required by Section 2257 of Title 18 of the United States Code with respect to visual depictions of actual sexually explicit conduct are kept by the custodian of records, Simon Dufour and Myriam Crepeau, who can be reached at vandalswarmprod@hotmail.com Monday to Friday between 9AM and 5PM, and has a business address of 3449 St-Denis office 1, Montreal, Canada, except with regard to visual depictions of actual sexually explicit conduct made before July 3, 1995, which are exempt from the requirements set forth in 18 U.S.C. § 2257 and 28 C.F.R. 75. [ Post a Reply to This Message ] |
| Subject: Oriana Rene Small vs Andrew Cravenho | |
Author: Anonymous [ Edit | View ] |
Date Posted: 04:06:45 03/01/15 Sun Mrs. Nazworthy[ Post a Reply to This Message ] |
| Subject: Andrew Cravenho and Brittany Sturtevant | |
Author: Anonymous [ Edit | View ] |
Date Posted: 03:57:49 03/01/15 Sun The operator of this network is an online distributor of erotic films. None of the visual depictions found on this network were produced by the network operator. The primary producers for each of the visual depictions found on this network have represented to the network operator that all models, actors, actresses and other persons that appear in any visual depiction of actual or simulated sexual conduct distributed through this network were eighteen (18) years of age or older at the time of the creation of such depictions. Documentation required pursuant to 18 U.S.C. 2257 is maintained by the applicable Custodian of Records for the primary producer of each visual depiction and the Custodian of Records information is available on the network by clicking the "Custodian of Records" link found under each boxcover for each visual depiction. The production dates listed for such visual depictions have been provided to the network operator by the primary producer and are also contained in the records maintained by the primary producers pursuant to 18 U.S.C. 2257 and 28 C.F.R. 75. Some visual depictions of actual sexually explicit conduct distributed on this network were produced prior to July 3, 1995 and are exempt from the requirements of 18 U.S.C. 2257 and 28 C.F. R. 75. The date of distribution for both exempt and non-exempt visual depictions of actual sexually explicit conduct is the date of the visitor's entry into this network. Today's date is: Mar 1, 2015. Records required to be maintained by the operator of this network pursuant to 18 U.S.C. 2257 and C.F.R. 75 are kept in the following location by the Custodian of Records:
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| Subject: Andrew Cravenho and Melissa Knieling | |
Author: Anonymous [ Edit | View ] |
Date Posted: 03:53:14 03/01/15 Sun 18 U.S. Code 2257 - Record keeping requirements(a) Whoever produces any book, magazine, periodical, film, videotape, digital image, digitally- or computer-manipulated image of an actual human being, picture, or other matter which (1) contains one or more visual depictions made after November 1, 1990 of actual sexually explicit conduct; and (2) is produced in whole or in part with materials which have been mailed or shipped in interstate or foreign commerce, or is shipped or transported or is intended for shipment or transportation in interstate or foreign commerce; shall create and maintain individually identifiable records pertaining to every performer portrayed in such a visual depiction. (b) Any person to whom subsection (a) applies shall, with respect to every performer portrayed in a visual depiction of actual sexually explicit conduct (1) ascertain, by examination of an identification document containing such information, the performers name and date of birth, and require the performer to provide such other indicia of his or her identity as may be prescribed by regulations; (2) ascertain any name, other than the performers present and correct name, ever used by the performer including maiden name, alias, nickname, stage, or professional name; and (3) record in the records required by subsection (a) the information required by paragraphs (1) and (2) of this subsection and such other identifying information as may be prescribed by regulation. (c) Any person to whom subsection (a) applies shall maintain the records required by this section at his business premises, or at such other place as the Attorney General may by regulation prescribe and shall make such records available to the Attorney General for inspection at all reasonable times. (d) (1) No information or evidence obtained from records required to be created or maintained by this section shall, except as provided in this section, directly or indirectly, be used as evidence against any person with respect to any violation of law. (2) Paragraph (1) of this subsection shall not preclude the use of such information or evidence in a prosecution or other action for a violation of this chapter or chapter 71, or for a violation of any applicable provision of law with respect to the furnishing of false information. (e) (1) Any person to whom subsection (a) applies shall cause to be affixed to every copy of any matter described in paragraph (1) of subsection (a) of this section, in such manner and in such form as the Attorney General shall by regulations prescribe, a statement describing where the records required by this section with respect to all performers depicted in that copy of the matter may be located. In this paragraph, the term copy includes every page of a website on which matter described in subsection (a) appears. (2) If the person to whom subsection (a) of this section applies is an organization the statement required by this subsection shall include the name, title, and business address of the individual employed by such organization responsible for maintaining the records required by this section. (f) It shall be unlawful (1) for any person to whom subsection (a) applies to fail to create or maintain the records as required by subsections (a) and (c) or by any regulation promulgated under this section; (2) for any person to whom subsection (a) applies knowingly to make any false entry in or knowingly to fail to make an appropriate entry in, any record required by subsection (b) of this section or any regulation promulgated under this section; (3) for any person to whom subsection (a) applies knowingly to fail to comply with the provisions of subsection (e) or any regulation promulgated pursuant to that subsection; (4) for any person knowingly to sell or otherwise transfer, or offer for sale or transfer, any book, magazine, periodical, film, video, or other matter, produce in whole or in part with materials which have been mailed or shipped in interstate or foreign commerce or which is intended for shipment in interstate or foreign commerce, which (A) contains one or more visual depictions made after the effective date of this subsection of actual sexually explicit conduct; and (B) is produced in whole or in part with materials which have been mailed or shipped in interstate or foreign commerce, or is shipped or transported or is intended for shipment or transportation in interstate or foreign commerce; which does not have affixed thereto, in a manner prescribed as set forth in subsection (e)(1), a statement describing where the records required by this section may be located, but such person shall have no duty to determine the accuracy of the contents of the statement or the records required to be kept; and (5) for any person to whom subsection (a) applies to refuse to permit the Attorney General or his or her designee to conduct an inspection under subsection (c). (g) The Attorney General shall issue appropriate regulations to carry out this section. (h) In this section (1) the term actual sexually explicit conduct means actual but not simulated conduct as defined in clauses (i) through (v) of section 2256 (2)(A) of this title; (2) the term produces (A) means (i) actually filming, videotaping, photographing, creating a picture, digital image, or digitally- or computer-manipulated image of an actual human being; (ii) digitizing an image, of a visual depiction of sexually explicit conduct; or, assembling, manufacturing, publishing, duplicating, reproducing, or reissuing a book, magazine, periodical, film, videotape, digital image, or picture, or other matter intended for commercial distribution, that contains a visual depiction of sexually explicit conduct; or (iii) inserting on a computer site or service a digital image of, or otherwise managing the sexually explicit content, [1] of a computer site or service that contains a visual depiction of, sexually explicit conduct; and (B) does not include activities that are limited to (i) photo or film processing, including digitization of previously existing visual depictions, as part of a commercial enterprise, with no other commercial interest in the sexually explicit material, printing, and video duplication; (ii) distribution; (iii) any activity, other than those activities identified in subparagraph (A), that does not involve the hiring, contracting for, managing, or otherwise arranging for the participation of the depicted performers; (iv) the provision of a telecommunications service, or of an Internet access service or Internet information location tool (as those terms are defined in section 231 of the Communications Act of 1934 (47 U.S.C. 231)); or (v) the transmission, storage, retrieval, hosting, formatting, or translation (or any combination thereof) of a communication, without selection or alteration of the content of the communication, except that deletion of a particular communication or material made by another person in a manner consistent with section 230(c) of the Communications Act of 1934 (47 U.S.C. 230 (c)) shall not constitute such selection or alteration of the content of the communication; and (3) the term performer includes any person portrayed in a visual depiction engaging in, or assisting another person to engage in, sexually explicit conduct. (i) Whoever violates this section shall be imprisoned for not more than 5 years, and fined in accordance with the provisions of this title, or both. Whoever violates this section after having been convicted of a violation punishable under this section shall be imprisoned for any period of years not more than 10 years but not less than 2 years, and fined in accordance with the provisions of this title, or both. [ Post a Reply to This Message ] |
| Subject: @black7pro | |
Author: Anonymous [ Edit | View ] |
Date Posted: 22:50:13 06/20/14 Fri http://archive.today/eoZ1w http://archive.today/GKA3G http://archive.today/KXF9K http://archive.today/cUPhX     [ Post a Reply to This Message ] |
| Subject: Sundarapandian Full Movie Free Download Tround | |
Author: Anonymous [ Edit | View ] |
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| Subject: Manifesting True Desires Learning From Arianrhod And The Tree Of Life | |
Author: Anonymous [ Edit | View ] |
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