Security is freedom from, or resilience against, potential harm caused by others. Beneficiaries of security may be of persons and social groups and institutions, ecosystems or any other entity or phenomenon vulnerable to unwanted change by its environment. Security refers to protection from hostile forces, but it has a wide range of other senses: for example, as the absence of harm; the term is used to refer to acts and systems whose purpose may be to provide security. The word'secure' entered the English language in the 16th century, it is derived from Latin securus, meaning freedom from anxiety: se + cura. A security referent is the focus of a security discourse. Security referents may be persons or social groups, institutions, ecosystems, or any other phenomenon vulnerable to unwanted change by the forces of its environment; the referent in question may combine many referents, in the same way that, for example, a nation state is composed of many individual citizens. The security context is the relationships between its environment.
From this perspective and insecurity depend first on whether the environment is beneficial or hostile to the referent, how capable is the referent of responding to its/their environment in order to survive and thrive. The means by which a referent provides for security vary widely, they include, for example: Coercive capabilities, including the capacity to project coercive power into the environment. Any action intended to provide security may have multiple effects. For example, an action may have wide benefit, enhancing security for several or all security referents in the context. Approaches to security are the subject of debate. For example, in debate about national security strategies, some argue that security depends principally on developing protective and coercive capabilities in order to protect the security referent in a hostile environment. Others argue that security depends principally on building the conditions in which equitable relationships can develop by reducing antagonism between actors, ensuring that fundamental needs can be met, that differences of interest can be negotiated effectively.
The table shows some of the main domains. The range of security contexts is illustrated by the following examples: Computer security known as cybersecurity or IT security, refers to the security of computing devices such as computers and smartphones, as well as computer networks such as private and public networks, the Internet; the field has growing importance due to the increasing reliance on computer systems in most societies. It concerns the protection of hardware, data and the procedures by which systems are accessed; the means of computer security include the physical security of systems and security of information held on them. Corporate security refers to the resilience of corporations against espionage, theft and other threats; the security of corporations has become more complex as reliance on IT systems has increased, their physical presence has become more distributed across several countries, including environments that are, or may become, hostile to them. Ecological security known as environmental security, refers to the integrity of ecosystems and the biosphere in relation to their capacity to sustain a diversity of life-forms.
The security of ecosystems has attracted greater attention as the impact of ecological damage by humans has grown. Food security refers to the ready supply of, access to, safe and nutritious food. Food security is gaining in importance as the world's population has grown and productive land has diminished through overuse and climate change. Home security refers to the security systems used on a property used as a dwelling; the concept is supported by the United Nations General Assembly, which has stressed "the right of people to live in freedom and dignity" and recognized "t
Video is an electronic medium for the recording, playback and display of moving visual media. Video was first developed for mechanical television systems, which were replaced by cathode ray tube systems which were replaced by flat panel displays of several types. Video systems vary in display resolution, aspect ratio, refresh rate, color capabilities and other qualities. Analog and digital variants exist and can be carried on a variety of media, including radio broadcast, magnetic tape, optical discs, computer files, network streaming. Video technology was first developed for mechanical television systems, which were replaced by cathode ray tube television systems, but several new technologies for video display devices have since been invented. Video was exclusively a live technology. Charles Ginsburg led an Ampex research team developing one of the first practical video tape recorder. In 1951 the first video tape recorder captured live images from television cameras by converting the camera's electrical impulses and saving the information onto magnetic video tape.
Video recorders were sold for US $50,000 in 1956, videotapes cost US $300 per one-hour reel. However, prices dropped over the years; the use of digital techniques in video created digital video, which allows higher quality and much lower cost than earlier analog technology. After the invention of the DVD in 1997 and Blu-ray Disc in 2006, sales of videotape and recording equipment plummeted. Advances in computer technology allows inexpensive personal computers and smartphones to capture, store and transmit digital video, further reducing the cost of video production, allowing program-makers and broadcasters to move to tapeless production; the advent of digital broadcasting and the subsequent digital television transition is in the process of relegating analog video to the status of a legacy technology in most parts of the world. As of 2015, with the increasing use of high-resolution video cameras with improved dynamic range and color gamuts, high-dynamic-range digital intermediate data formats with improved color depth, modern digital video technology is converging with digital film technology.
Frame rate, the number of still pictures per unit of time of video, ranges from six or eight frames per second for old mechanical cameras to 120 or more frames per second for new professional cameras. PAL standards and SECAM specify 25 frame/s. Film is shot at the slower frame rate of 24 frames per second, which complicates the process of transferring a cinematic motion picture to video; the minimum frame rate to achieve a comfortable illusion of a moving image is about sixteen frames per second. Video can be progressive. In progressive scan systems, each refresh period updates all scan lines in each frame in sequence; when displaying a natively progressive broadcast or recorded signal, the result is optimum spatial resolution of both the stationary and moving parts of the image. Interlacing was invented as a way to reduce flicker in early mechanical and CRT video displays without increasing the number of complete frames per second. Interlacing retains detail while requiring lower bandwidth compared to progressive scanning.
In interlaced video, the horizontal scan lines of each complete frame are treated as if numbered consecutively, captured as two fields: an odd field consisting of the odd-numbered lines and an field consisting of the even-numbered lines. Analog display devices reproduce each frame doubling the frame rate as far as perceptible overall flicker is concerned; when the image capture device acquires the fields one at a time, rather than dividing up a complete frame after it is captured, the frame rate for motion is doubled as well, resulting in smoother, more lifelike reproduction of moving parts of the image when viewed on an interlaced CRT display. NTSC, PAL and SECAM are interlaced formats. Abbreviated video resolution specifications include an i to indicate interlacing. For example, PAL video format is described as 576i50, where 576 indicates the total number of horizontal scan lines, i indicates interlacing, 50 indicates 50 fields per second; when displaying a natively interlaced signal on a progressive scan device, overall spatial resolution is degraded by simple line doubling—artifacts such as flickering or "comb" effects in moving parts of the image which appear unless special signal processing eliminates them.
A procedure known as deinterlacing can optimize the display of an interlaced video signal from an analog, DVD or satellite source on a progressive scan device such as an LCD television, digital video projector or plasma panel. Deinterlacing cannot, produce video quality, equivalent to true progressive scan source material. Aspect ratio describes the proportional relationship between the width and height of video screens and video picture elements. All popular video formats are rectangular, so can be described by a ratio between width and height; the ratio width to height for a traditional television screen is 4:3, or about 1.33:1. High definition televisions use an aspect ratio of 16:9, or about 1.78:1. The aspect ratio of a full 35 mm film frame with soundtrack is 1.375:1. Pixels on computer monitors are square, but pixels used in digital video have non-square aspect ratios, such as those used in the PAL and NTSC variants of the CCIR 601 digital video
General Services Administration
The General Services Administration, an independent agency of the United States government, was established in 1949 to help manage and support the basic functioning of federal agencies. GSA supplies products and communications for U. S. government offices, provides transportation and office space to federal employees, develops government-wide cost-minimizing policies and other management tasks. GSA employs about 12,000 federal workers and has an annual operating budget of $20.9 billion. GSA oversees $66 billion of procurement annually, it contributes to the management of about $500 billion in U. S. federal property, divided chiefly among 8,700 owned and leased buildings and a 215,000 vehicle motor pool. Among the real estate assets managed by GSA are the Ronald Reagan Building and International Trade Center in Washington, D. C. – the largest U. S. federal building after the Pentagon – and the Hart-Dole-Inouye Federal Center. GSA's business lines include the Federal Acquisition Service and the Public Buildings Service, as well as several Staff Offices including the Office of Government-wide Policy, the Office of Small Business Utilization, the Office of Mission Assurance.
As part of FAS, GSA's Technology Transformation Services helps federal agencies improve delivery of information and services to the public. Key initiatives include FedRAMP, Cloud.gov, the USAGov platform, Data.gov, Performance.gov, Challenge.gov. GSA is a member of the Procurement G6, an informal group leading the use of framework agreements and e-procurement instruments in public procurement. In 1947 President Harry Truman asked former President Herbert Hoover to lead what became known as the Hoover Commission to make recommendations to reorganize the operations of the federal government. One of the recommendations of the commission was the establishment of an "Office of the General Services." This proposed office would combine the responsibilities of the following organizations: U. S. Treasury Department's Bureau of Federal Supply U. S. Treasury Department's Office of Contract Settlement National Archives Establishment All functions of the Federal Works Agency, including the Public Buildings Administration and the Public Roads Administration War Assets AdministrationGSA became an independent agency on July 1, 1949, after the passage of the Federal Property and Administrative Services Act.
General Jess Larson, Administrator of the War Assets Administration, was named GSA's first Administrator. The first job awaiting Administrator Larson and the newly formed GSA was a complete renovation of the White House; the structure had fallen into such a state of disrepair by 1949 that one inspector of the time said the historic structure was standing "purely from habit." Larson explained the nature of the total renovation in depth by saying, "In order to make the White House structurally sound, it was necessary to dismantle, I mean dismantle, everything from the White House except the four walls, which were constructed of stone. Everything, except the four walls without a roof, was stripped down, that's where the work started." GSA worked with President Truman and First Lady Bess Truman to ensure that the new agency's first major project would be a success. GSA completed the renovation in 1952. In 1986 GSA headquarters, U. S. General Services Administration Building, located at Eighteenth and F Streets, NW, was listed on the National Register of Historic Places, at the time serving as Interior Department offices.
In 1960 GSA created the Federal Telecommunications System, a government-wide intercity telephone system. In 1962 the Ad Hoc Committee on Federal Office Space created a new building program to address obsolete office buildings in Washington, D. C. resulting in the construction of many of the offices that now line Independence Avenue. In 1970 the Nixon administration created the Consumer Product Information Coordinating Center, now part of USAGov. In 1974 the Federal Buildings Fund was initiated, allowing GSA to issue rent bills to federal agencies. In 1972 GSA established the Automated Data and Telecommunications Service, which became the Office of Information Resources Management. In 1973 GSA created the Office of Federal Management Policy. GSA's Office of Acquisition Policy centralized procurement policy in 1978. GSA was responsible for emergency preparedness and stockpiling strategic materials to be used in wartime until these functions were transferred to the newly-created Federal Emergency Management Agency in 1979.
In 1984 GSA introduced the federal government to the use of charge cards, known as the GMA SmartPay system. The National Archives and Records Administration was spun off into an independent agency in 1985; the same year, GSA began to provide governmentwide policy oversight and guidance for federal real property management as a result of an Executive Order signed by President Ronald Reagan. In 2003 the Federal Protective Service was moved to the Department of Homeland Security. In 2005 GSA reorganized to merge the Federal Supply Service and Federal Technology Service business lines into the Federal Acquisition Service. On April 3, 2009, President Barack Obama nominated Martha N. Johnson to serve as GSA Administrator. After a nine-month delay, the United States Senate confirmed her nomination on February 4, 2010. On April 2, 2012, Johnson resigned in the wake of a management-deficiency report that detailed improper payments for a 2010 "Western Regions" training conference put on by the Public Buildings Service in Las Vegas.
In July 1991 GSA contractors began the excavation of what is now the Ted Weiss Federal Building in New York City. The planning for that buildin
Network interface device
In telecommunications, a network interface device is a device that serves as the demarcation point between the carrier's local loop and the customer's premises wiring. Outdoor telephone NIDs provide the subscriber with access to the station wiring and serve as a convenient test point for verification of loop integrity and of the subscriber’s inside wiring. Generically, an NID may be called a network interface unit, telephone network interface, system network interface, or telephone network box. Australia's National Broadband Network uses the term network termination device or NTD. A smartjack is a type of NID with capabilities beyond simple electrical connection, such as diagnostics. An optical network terminal is a type of NID used with fiber-to-the-premises applications; the simplest NIDs are just a specialized set of wiring terminals. These will take the form of a small, weather-proof box, mounted on the outside of the building; the telephone line from the telephone company will be connected to one side.
The customer connects their wiring to the other side. A single NID enclosure may contain termination for multiple lines. In its role as the demarcation point, the NID separates the telephone company's equipment from the customer's wiring and equipment; the telephone company owns the NID itself, all wiring up to it. Anything past the NID is the customer's responsibility. To facilitate this, there is a test jack inside the NID. Accessing the test jack disconnects the customer premises wiring from the public switched telephone network and allows the customer to plug a "known good" telephone into the jack to isolate trouble. If the telephone works at the test jack, the problem is the customer's wiring, the customer is responsible for repair. If the telephone does not work, the line is faulty and the telephone company is responsible for repair. Most NIDs include "circuit protectors", which are surge protectors for a telephone line, they protect customer wiring and personnel from any transient energy on the line, such as from a lightning strike to a telephone pole.
Simple NIDs contain no digital logic. They have no capabilities beyond wiring termination, circuit protection, providing a place to connect test equipment. Several types of NIDs provide more than just a terminal for the connection of wiring; such NIDs are colloquially called smartjacks or Intelligent Network Interface Devices as an indication of their built-in "intelligence", as opposed to a simple NID, just a wiring device. Smartjacks are used for more complicated types of telecommunications service, such as T1 lines. Plain old telephone service lines cannot be equipped with smartjacks. Despite the name, most smartjacks are much more than a simple telephone jack. One common form for a smartjack is a printed circuit board with a face plate on one edge, mounted in an enclosure. A smartjack may provide signal conversion, converting codes and protocols to the type needed by the customer equipment, it may buffer and/or regenerate the signal, to compensate for signal degradation from line transmission, similar to what a repeater does.
Smartjacks typically provide diagnostic capabilities. A common capability provided by a smartjack is loopback, such that the signal from the telephone company is transmitted back to the telephone company; this allows the company to test the line from the central telephone exchange, without the need to have test equipment at the customer site. The telephone company has the ability to remotely activate loopback, without needing personnel at the customer site; when looped back, the customer equipment is disconnected from the line. Additional smartjack diagnostic capabilities include alarm indication signal, which reports trouble at one end of the line to the far end; this helps the telephone company know if trouble is present in the line, the smartjack, or customer equipment. Indicator lights to show configuration and alarms are common. Smartjacks derive their operating power from the telephone line, rather than relying on premises electrical power, although this is not a universal rule. In fiber-to-the-premises systems, the signal is transmitted to the customer premises using fiber optic technologies.
Unlike many conventional telephone technologies, this does not provide power for premises equipment, nor is it suitable for direct connection to customer equipment. An optical network terminal is used to terminate the fiber optic line, demultiplex the signal into its component parts, provide power to customer telephones; as the ONT must derive its power from the customer premises electrical supply, many ONTs have the option for a battery backup, to maintain service in the event of a power outage. According to Telcordia GR-49, requirements for telecommunications NIDs vary based on three categories of environmental conditions: Normal conditions: This refers to a normal environment, expected in most areas of any service provider. Temperatures are expected to be in the range of −20–32 °C, humidity is expected to be less than 90% RH. No unusual contamination is expected. Severe climatic conditions: These cover environments more severe than those of a normal environment. Temperatures are expected to be in the range of −40–43 °C, humidity may exceed 90% RH.
Jacks installed in NIDs in such environments are known to become contaminated and develop low insulation resistances and low dielectric brea
Information is the resolution of uncertainty. Information is associated with data and knowledge, as data is meaningful information and represents the values attributed to parameters, knowledge signifies understanding of an abstract or concrete concept; the existence of information can be uncoupled from an observer, which refers to that which accesses information to discern that which it specifies. In the case of knowledge, the information itself requires a cognitive observer to be accessed. In terms of communication, information is expressed either as the content of a message or through direct or indirect observation. That, perceived can be construed as a message in its own right, in that sense, information is always conveyed as the content of a message. Information can be encoded into various forms for interpretation, it can be encrypted for safe storage and communication. Information reduces uncertainty; the uncertainty of an event is measured by its probability of occurrence and is inversely proportional to that.
The more uncertain an event, the more information is required to resolve uncertainty of that event. The bit is a typical unit of information. For example, the information encoded in one "fair" coin flip is log2 = 1 bit, in two fair coin flips is log2 = 2 bits; the concept of information has different meanings in different contexts. Thus the concept becomes related to notions of constraint, control, form, knowledge, understanding, mental stimuli, perception and entropy; the English word derives from the Latin stem of the nominative: this noun derives from the verb informare in the sense of "to give form to the mind", "to discipline", "instruct", "teach". Inform itself comes from the Latin verb informare, which means to form an idea of. Furthermore, Latin itself contained the word informatio meaning concept or idea, but the extent to which this may have influenced the development of the word information in English is not clear; the ancient Greek word for form was μορφή and εἶδος "kind, shape, set", the latter word was famously used in a technical philosophical sense by Plato to denote the ideal identity or essence of something.'Eidos' can be associated with thought, proposition, or concept.
The ancient Greek word for information is πληροφορία, which transliterates from πλήρης "fully" and φέρω frequentative of to carry through. It means "bears fully" or "conveys fully". In modern Greek the word Πληροφορία is still in daily use and has the same meaning as the word information in English. In addition to its primary meaning, the word Πληροφορία as a symbol has deep roots in Aristotle's semiotic triangle. In this regard it can be interpreted to communicate information to the one decoding that specific type of sign; this is something that occurs with the etymology of many words in ancient and modern Greek where there is a strong denotative relationship between the signifier, e.g. the word symbol that conveys a specific encoded interpretation, the signified, e.g. a concept whose meaning the interpreter attempts to decode. In English, “information” is an uncountable mass noun. In information theory, information is taken as an ordered sequence of symbols from an alphabet, say an input alphabet χ, an output alphabet ϒ.
Information processing consists of an input-output function that maps any input sequence from χ into an output sequence from ϒ. The mapping may be deterministic, it may be memoryless. Information can be viewed as a type of input to an organism or system. Inputs are of two kinds. In his book Sensory Ecology Dusenbery called these causal inputs. Other inputs are important only because they are associated with causal inputs and can be used to predict the occurrence of a causal input at a time; some information is important because of association with other information but there must be a connection to a causal input. In practice, information is carried by weak stimuli that must be detected by specialized sensory systems and amplified by energy inputs before they can be functional to the organism or system. For example, light is a causal input to plants but for animals it only provides information; the colored light reflected from a flower is too weak to do much photosynthetic work but the visual system of the bee detects it and the bee's nervous system uses the information to guide the bee to the flower, where the bee finds nectar or pollen, which are causal inputs, serving a nutritional function.
The cognitive scientist and applied mathematician Ronaldo Vigo argues that information is a concept that requires at least two related entities to make quantitative sense. These are, any dimensionally defined category of objects S, any of its subsets R. R, in essence, is a representation of S, or, in other words, conveys representational information about S. Vigo defines the amount of information that R conveys a
Integrated Services Digital Network
Integrated Services Digital Network is a set of communication standards for simultaneous digital transmission of voice, video and other network services over the traditional circuits of the public switched telephone network. It was first defined in 1988 in the CCITT red book. Prior to ISDN, the telephone system was viewed as a way to transport voice, with some special services available for data; the key feature of ISDN is that it integrates speech and data on the same lines, adding features that were not available in the classic telephone system. The ISDN standards define several kinds of access interfaces, such as Basic Rate Interface, Primary Rate Interface, Narrowband ISDN, Broadband ISDN. ISDN is a circuit-switched telephone network system, which provides access to packet switched networks, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better voice quality than an analog phone can provide, it offers circuit-switched connections, packet-switched connections, in increments of 64 kilobit/s.
In some countries, ISDN found major market application for Internet access, in which ISDN provides a maximum of 128 kbit/s bandwidth in both upstream and downstream directions. Channel bonding can achieve a greater data rate. ISDN is employed as data-link and physical layers in the context of the OSI model. In common use, ISDN is limited to usage to Q.931 and related protocols, which are a set of signaling protocols establishing and breaking circuit-switched connections, for advanced calling features for the user. They were introduced in 1986. In a videoconference, ISDN provides simultaneous voice and text transmission between individual desktop videoconferencing systems and group videoconferencing systems. Integrated services refers to ISDN's ability to deliver at minimum two simultaneous connections, in any combination of data, voice and fax, over a single line. Multiple devices can be attached to the line, used as needed; that means an ISDN line can take care of what were expected to be most people's complete communications needs at a much higher transmission rate, without forcing the purchase of multiple analog phone lines.
It refers to integrated switching and transmission in that telephone switching and carrier wave transmission are integrated rather than separate as in earlier technology. The entry level interface to ISDN is the Basic Rate Interface, a 128 kbit/s service delivered over a pair of standard telephone copper wires; the 144 kbit/s overall payload rate is divided into two 64 kbit/s bearer channels and one 16 kbit/s signaling channel. This is sometimes referred to as 2B+D; the interface specifies the following network interfaces: The U interface is a two-wire interface between the exchange and a network terminating unit, the demarcation point in non-North American networks. The T interface is a serial interface between a computing device and a terminal adapter, the digital equivalent of a modem; the S interface is a four-wire bus. The R interface defines the point between a non-ISDN device and a terminal adapter which provides translation to and from such a device. BRI-ISDN is popular in Europe but is much less common in North America.
It is common in Japan — where it is known as INS64. The other ISDN access available is the Primary Rate Interface, carried over T-carrier with 24 time slots in North America, over E-carrier with 32 channels in most other countries; each channel provides transmission at a 64 kbit/s data rate. With the E1 carrier, the available channels are divided into 30 bearer channels, one data channel, one timing and alarm channel; this scheme is referred to as 30B+2D. In North America, PRI service is delivered via T1 carriers with only one data channel referred to as 23B+D, a total data rate of 1544 kbit/s. Non-Facility Associated Signalling allows two or more PRI circuits to be controlled by a single D channel, sometimes called 23B+D + n*24B. D-channel backup allows for a second D channel in case the primary fails. NFAS is used on a Digital Signal 3. PRI-ISDN is popular throughout the world for connecting private branch exchanges to the public switched telephone network. Though many network professionals use the term ISDN to refer to the lower-bandwidth BRI circuit, in North America BRI is uncommon whilst PRI circuits serving PBXs are commonplace.
The bearer channel is a standard 64 kbit/s voice channel of 8 bits sampled at 8 kHz with G.711 encoding. B-channels can be used to carry data, since they are nothing more than digital channels; each one of these channels is known as a DS0. Most B channels can carry a 64 kbit/s signal, but some were limited to 56K because they traveled over RBS lines; this has since become less so. X.25 can be carried over the B or D channels of a BRI line, over the B channels of a PRI line. X.25 over the D channel is used at many point-of-sale terminals because it eliminates the modem setup, because it connects to the central system over a B channel, thereby eliminating the need for modems and making much better use of the central system's telephone lines. X.25 was part of an ISDN protocol
In telecommunications, transmission is the process of sending and propagating an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless. One example of transmission is the sending of a signal with limited duration, for example a block or packet of data, a phone call, or an email. Transmission technologies and schemes refer to physical layer protocol duties such as modulation, line coding, error control, bit synchronization and multiplexing, but the term may involve higher-layer protocol duties, for example, digitizing an analog message signal, data compression. Transmission of a digital message, or of a digitized analog signal, is known as digital communication