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16,700 | Bupropion, when used for treating obesity over a period of 6 to 12 months, results in an average weight loss of 2.7 kg (5.9 lbs) over placebo. This is not much different from the weight loss produced by several other weight-loss medications such as sibutramine or orlistat. The combination drug naltrexone/bupropion has ... | https://en.wikipedia.org/wiki?curid=378579 |
16,701 | Bupropion is not effective in the treatment of cocaine dependence, but it is showing promise in reducing drug use in light methamphetamine users. Based on studies indicating that bupropion lowers the level of the inflammatory mediator TNF-alpha, there have been suggestions that it might be useful in treating inflammato... | https://en.wikipedia.org/wiki?curid=378579 |
16,702 | Bupropion is available as an oral tablet in a number of different formulations. It is formulated mostly as the hydrochloride salt but also to a lesser extent as the hydrobromide salt. The available forms of bupropion hydrochloride include IR (instant-release) tablets (50, 75, 100mg), SR (sustained-release) tablets (50,... | https://en.wikipedia.org/wiki?curid=378579 |
16,703 | The drug label advises that bupropion should not be prescribed to individuals with epilepsy or other conditions that lower the seizure threshold, such as anorexia nervosa, bulimia nervosa, benzodiazepine or alcohol withdrawal. It should be avoided in individuals who are taking monoamine oxidase inhibitors (MAOIs). When... | https://en.wikipedia.org/wiki?curid=378579 |
16,704 | The common adverse effects of bupropion with the greatest difference from placebo are dry mouth, nausea, constipation, insomnia, anxiety, tremor, and excessive sweating. Bupropion has the highest incidence of insomnia of all second-generation antidepressants, apart from desvenlafaxine. It is also associated with about ... | https://en.wikipedia.org/wiki?curid=378579 |
16,705 | Bupropion raises blood pressure in some people. One study showed an average rise of 6 mm Hg in sysolic blood pressure in 10% of patients. The prescribing information notes that hypertension, sometimes severe, is observed in some people taking bupropion, both with and without pre-existing hypertension. Safety of bupropi... | https://en.wikipedia.org/wiki?curid=378579 |
16,706 | Seizure is a rare but serious adverse effect of bupropion. It is strongly dose-dependent: for the immediate release preparation, the seizure incidence is 0.4% at the dose 300–450 mg per day; the incidence climbs almost ten-fold for the higher than recommended dose of 600 mg. For comparison, the incidence of unprovoked ... | https://en.wikipedia.org/wiki?curid=378579 |
16,707 | Cases of liver toxicity leading to death or liver transplantation have been reported for bupropion. It is considered to be one of several antidepressants with greater risk of hepatotoxicity. | https://en.wikipedia.org/wiki?curid=378579 |
16,708 | The prescribing information warns about bupropion triggering an angle-closure glaucoma attack. On the other hand, bupropion may decrease the risk of development of open angle glaucoma. | https://en.wikipedia.org/wiki?curid=378579 |
16,709 | Bupropion use by mothers in the first trimester of pregnancy is associated with 23% increase of the odds in congenital heart defects in their children. | https://en.wikipedia.org/wiki?curid=378579 |
16,710 | The FDA requires all antidepressants, including bupropion, to carry a boxed warning stating that antidepressants may increase the risk of suicide in people younger than 25. This warning is based on a statistical analysis conducted by the FDA which found a 2-fold increase in suicidal thought and behavior in children and... | https://en.wikipedia.org/wiki?curid=378579 |
16,711 | Bupropion prescribed for smoking cessation results in 25% increase of the risk of psychiatric side effects, in particular, anxiety (about 40% increase) and insomnia (about 80% increase). The evidence is insufficient to determine whether bupropion is associated with suicides or suicidal behavior. | https://en.wikipedia.org/wiki?curid=378579 |
16,712 | In rare cases, bupropion-induced psychosis may develop. It is associated with higher doses of bupropion; many cases described are at higher than recommended doses. Concurrent antipsychotic medication appears to be protective. In most cases the psychotic symptoms are eliminated by reducing the dose, ceasing treatment or... | https://en.wikipedia.org/wiki?curid=378579 |
16,713 | Although studies are lacking, a handful of case reports suggest that abrupt discontinuation of bupropion may cause antidepressant discontinuation syndrome. | https://en.wikipedia.org/wiki?curid=378579 |
16,714 | Bupropion is considered moderately dangerous in overdose. According to an analysis of US National Poison Data System, adjusted for the number of prescriptions, bupropion and venlafaxine are the two new generation antidepressants (that is excluding tricyclic antidepressants) that result in the highest mortality and morb... | https://en.wikipedia.org/wiki?curid=378579 |
16,715 | Since bupropion is metabolized to hydroxybupropion by the enzyme CYP2B6, drug interactions with CYP2B6 inhibitors are possible: this includes such medications as paroxetine, sertraline, norfluoxetine (active metabolite of fluoxetine), diazepam, clopidogrel, and orphenadrine. The expected result is the increase of bupro... | https://en.wikipedia.org/wiki?curid=378579 |
16,716 | Bupropion and its metabolites are inhibitors of CYP2D6, with hydroxybupropion responsible for most of the inhibition. Additionally, bupropion and its metabolites may decrease expression of CYP2D6 in the liver. The end effect is a significant slowing of the clearance of other drugs metabolized by this enzyme. For instan... | https://en.wikipedia.org/wiki?curid=378579 |
16,717 | Bupropion lowers the seizure threshold, and therefore can potentially interact with other medications that also lower it, such as antipsychotics, tricyclic antidepressants, theophylline, and systemic corticosteroids. The prescribing information recommends minimizing the use of alcohol, since in rare cases bupropion red... | https://en.wikipedia.org/wiki?curid=378579 |
16,718 | Caution should be observed when combining bupropion with a monoamine oxidase inhibitor (MAOI), as it may result in hypertensive crisis. | https://en.wikipedia.org/wiki?curid=378579 |
16,719 | The mechanism of action of bupropion in the treatment of depression and for other indications is unclear. However, it is thought to be related to the fact that bupropion is a norepinephrine–dopamine reuptake inhibitor (NDRI) and antagonist of several nicotinic acetylcholine receptors. It is uncertain whether bupropion ... | https://en.wikipedia.org/wiki?curid=378579 |
16,720 | The occupancy of dopamine transporter (DAT) by bupropion (300mg/day) and its metabolites in the human brain as measured by several positron emission tomography (PET) studies is approximately 20%, with a mean occupancy range of about 14 to 26%. For comparison, the NDRI methylphenidate at therapeutic doses is thought to ... | https://en.wikipedia.org/wiki?curid=378579 |
16,721 | After oral administration, bupropion is rapidly and completely absorbed reaching the peak blood plasma concentration after 1.5 hours (t). Sustained release (SR) and extended release (XL) formulations have been designed to slow down absorption resulting in t of 3 hours and 5 hours, respectively. Absolute bioavailability... | https://en.wikipedia.org/wiki?curid=378579 |
16,722 | Bupropion is metabolized in the body by a variety of pathways. The oxidative pathways are by cytochrome P450 isoenzymes CYP2B6 leading to "R,R"- and "S,S"-hydroxybupropion and, to a lesser degree, CYP2C19 leading to 4'-hydroxybupropion. The reductive pathways are by 11β-hydroxysteroid dehydrogenase type 1 in the liver ... | https://en.wikipedia.org/wiki?curid=378579 |
16,723 | The metabolism of bupropion is highly variable: the effective doses of bupropion received by persons who ingest the same amount of the drug may differ by as much as 5.5 times (with a half-life of 12–30 hours), while the effective doses of hydroxybupropion may differ by as much as 7.5 times (with a half-life of 15–25 ho... | https://en.wikipedia.org/wiki?curid=378579 |
16,724 | Bupropion is an aminoketone that belongs to the class of substituted cathinones and the more general class of substituted phenethylamines. The clinically used bupropion is racemic, that is a mixture of two enantiomers: "S"-bupropion and "R"-bupropion. Although the optical isomers on bupropion can be separated, they rap... | https://en.wikipedia.org/wiki?curid=378579 |
16,725 | There have been reported cases of false-positive urine amphetamine tests in persons taking bupropion. | https://en.wikipedia.org/wiki?curid=378579 |
16,726 | It is synthesized in two chemical steps starting from 3'-chloro-propiophenone. The alpha position adjacent to the ketone is first brominated followed by nucleophilic displacement of the resulting alpha-bromoketone with "t"-butylamine and treated with hydrochloric acid to give bupropion as the hydrochloride salt in 75–8... | https://en.wikipedia.org/wiki?curid=378579 |
16,727 | Bupropion was invented by Nariman Mehta of Burroughs Wellcome (now GlaxoSmithKline) in 1969, and the US patent for it was granted in 1974. It was approved by the U.S. Food and Drug Administration (FDA) as an antidepressant on 30 December 1985, and marketed under the name Wellbutrin. However, a significant incidence of ... | https://en.wikipedia.org/wiki?curid=378579 |
16,728 | In 1996, the FDA approved a sustained-release formulation of alcohol-resistant bupropion called Wellbutrin SR, intended to be taken twice a day (as compared with three times a day for immediate-release Wellbutrin). In 2003, the FDA approved another sustained-release formulation called Wellbutrin XL, intended for once-d... | https://en.wikipedia.org/wiki?curid=378579 |
16,729 | In France, marketing authorization was granted for Zyban on 3 August 2001, with a maximum daily dose of 300 mg; only sustained-release bupropion is available, and only as a smoking cessation aid. | https://en.wikipedia.org/wiki?curid=378579 |
16,730 | On 11 October 2007, two providers of consumer information on nutritional products and supplements, ConsumerLab.com and The People's Pharmacy, released the results of comparative tests of different brands of bupropion. The People's Pharmacy received multiple reports of increased side effects and decreased efficacy of ge... | https://en.wikipedia.org/wiki?curid=378579 |
16,731 | In April 2008, the FDA approved a formulation of bupropion as a hydrobromide salt instead of a hydrochloride salt, to be sold under the name Aplenzin by Sanofi-Aventis. | https://en.wikipedia.org/wiki?curid=378579 |
16,732 | In 2009, the FDA issued a health advisory warning that the prescription of bupropion for smoking cessation has been associated with reports about unusual behavior changes, agitation and hostility. Some people, according to the advisory, have become depressed or have had their depression worsen, have had thoughts about ... | https://en.wikipedia.org/wiki?curid=378579 |
16,733 | In 2012, the U.S. Justice Department announced that GlaxoSmithKline had agreed to plead guilty and pay a $3 billion fine, in part for promoting the unapproved use of Wellbutrin for weight loss and sexual dysfunction. | https://en.wikipedia.org/wiki?curid=378579 |
16,734 | In 2017, the European Medicines Agency recommended suspending a number of nationally approved medicines due to misrepresentation of bioequivalence study data by Micro Therapeutic Research Labs in India. The products recommended for suspension included several 300 mg modified-release bupropion tablets. | https://en.wikipedia.org/wiki?curid=378579 |
16,735 | While bupropion demonstrates some potential for misuse, this potential is less than of other commonly used stimulants, being limited by features of its pharmacology. Case reports describe misuse of bupropion as producing a "high" similar to cocaine or amphetamine usage but with less intensity. Bupropion misuse is uncom... | https://en.wikipedia.org/wiki?curid=378579 |
16,736 | In Russia bupropion is banned as a narcotic drug, yet not per se but rather as a derivative of methcathinone. | https://en.wikipedia.org/wiki?curid=378579 |
16,737 | The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of [ISO] standards development for the purpose of systems interconnection'. In the OSI reference model, the communications between a computing system are split into seven different abstraction lay... | https://en.wikipedia.org/wiki?curid=22747 |
16,738 | The model partitions the flow of data in a communication system into seven abstraction layers to describe networked communication from the physical implementation of transmitting bits across a communications medium to the highest-level representation of data of a distributed application. Each intermediate layer serves ... | https://en.wikipedia.org/wiki?curid=22747 |
16,739 | Each layer in the OSI model has its own well-defined functions, and the functions of each layer communicate and interact with the layers immediately above and below it, unless the layer does not have layers below or above. | https://en.wikipedia.org/wiki?curid=22747 |
16,740 | The Internet protocol suite has a separate model, the layers of which are mentioned in and . That model combines the physical and data link layers of the OSI model into a single link layer, and has a single application layer for all protocols above the transport layer, as opposed to the separate application, presentati... | https://en.wikipedia.org/wiki?curid=22747 |
16,741 | In comparison, several networking models have sought to create an intellectual framework for clarifying networking concepts and activities, but none have been as successful as the OSI reference model in becoming the standard model for discussing, teaching, and learning for the networking procedures in the field of Info... | https://en.wikipedia.org/wiki?curid=22747 |
16,742 | The development of the OSI model started in the late 1970s to support the emergence of the diverse computer networking methods that were competing for application in the large national networking efforts in the world (see Protocol Wars). In the 1980s, the model became a working product of the Open Systems Interconnecti... | https://en.wikipedia.org/wiki?curid=22747 |
16,743 | In the early- and mid-1970s, networking was largely either government-sponsored (NPL network in the UK, ARPANET in the US, CYCLADES in France) or vendor-developed with proprietary standards, such as IBM's Systems Network Architecture and Digital Equipment Corporation's DECnet. Public data networks were only just beginn... | https://en.wikipedia.org/wiki?curid=22747 |
16,744 | The Experimental Packet Switched System in the UK circa 1973–1975 identified the need for defining higher level protocols. The UK National Computing Centre publication 'Why Distributed Computing' which came from considerable research into future configurations for computer systems, resulted in the UK presenting the cas... | https://en.wikipedia.org/wiki?curid=22747 |
16,745 | Beginning in 1977, the ISO initiated a program to develop general standards and methods of networking. A similar process evolved at the International Telegraph and Telephone Consultative Committee (CCITT, from French: Comité Consultatif International Téléphonique et Télégraphique). Both bodies developed documents that ... | https://en.wikipedia.org/wiki?curid=22747 |
16,746 | The drafters of the reference model had to contend with many competing priorities and interests. The rate of technological change made it necessary to define standards that new systems could converge to rather than standardizing procedures after the fact; the reverse of the traditional approach to developing standards.... | https://en.wikipedia.org/wiki?curid=22747 |
16,747 | In 1983, the CCITT and ISO documents were merged to form "The Basic Reference Model for Open Systems Interconnection," usually referred to as the "Open Systems Interconnection Reference Model", "OSI Reference Model", or simply "OSI model". It was published in 1984 by both the ISO, as standard ISO 7498, and the renamed ... | https://en.wikipedia.org/wiki?curid=22747 |
16,748 | OSI had two major components, an abstract model of networking, called the Basic Reference Model or seven-layer model, and a set of specific protocols. The OSI reference model was a major advance in the standardisation of network concepts. It promoted the idea of a consistent model of protocol layers, defining interoper... | https://en.wikipedia.org/wiki?curid=22747 |
16,749 | The concept of a seven-layer model was provided by the work of Charles Bachman at Honeywell Information Systems. Various aspects of OSI design evolved from experiences with the NPL network, ARPANET, CYCLADES, EIN, and the International Networking Working Group (IFIP WG6.1). In this model, a networking system was divide... | https://en.wikipedia.org/wiki?curid=22747 |
16,750 | The OSI standards documents are available from the ITU-T as the X.200-series of recommendations. Some of the protocol specifications were also available as part of the ITU-T X series. The equivalent ISO/IEC standards for the OSI model were available from ISO. Not all are free of charge. | https://en.wikipedia.org/wiki?curid=22747 |
16,751 | OSI was an industry effort, attempting to get industry participants to agree on common network standards to provide multi-vendor interoperability. It was common for large networks to support multiple network protocol suites, with many devices unable to interoperate with other devices because of a lack of common protoco... | https://en.wikipedia.org/wiki?curid=22747 |
16,752 | The OSI model is still used as a reference for teaching and documentation; however, the OSI protocols originally conceived for the model did not gain popularity. Some engineers argue the OSI reference model is still relevant to cloud computing. Others say the original OSI model doesn't fit today's networking protocols ... | https://en.wikipedia.org/wiki?curid=22747 |
16,753 | Communication protocols enable an entity in one host to interact with a corresponding entity at the same layer in another host. Service definitions, like the OSI Model, abstractly describe the functionality provided to an (N)-layer by an (N-1) layer, where N is one of the seven layers of protocols operating in the loca... | https://en.wikipedia.org/wiki?curid=22747 |
16,754 | At each level "N", two entities at the communicating devices (layer N "peers") exchange protocol data units (PDUs) by means of a layer N "protocol". Each PDU contains a payload, called the service data unit (SDU), along with protocol-related headers or footers. | https://en.wikipedia.org/wiki?curid=22747 |
16,755 | The recommendation X.200 describes seven layers, labelled 1 to 7. Layer 1 is the lowest layer in this model. | https://en.wikipedia.org/wiki?curid=22747 |
16,756 | The Physical Layer is responsible for the transmission and reception of unstructured raw data between a device, such as a network interface controller, Ethernet hub, or network switch, and a physical transmission medium. It converts the digital bits into electrical, radio, or optical signals. Layer specifications defin... | https://en.wikipedia.org/wiki?curid=22747 |
16,757 | The Physical Layer also specifies how encoding occurs over a physical signal, such as electrical voltage or a light pulse. For example, a 1 bit might be represented on a copper wire by the transition from a 0-volt to a 5-volt signal, whereas a 0 bit might be represented by the transition from a 5-volt signal to 0-volt ... | https://en.wikipedia.org/wiki?curid=22747 |
16,758 | The data link layer provides node-to-node data transfer—a link between two directly connected nodes. It detects and possibly corrects errors that may occur in the physical layer. | https://en.wikipedia.org/wiki?curid=22747 |
16,759 | It defines the protocol to establish and terminate a connection between two physically connected devices. It also defines the protocol for flow control between them. | https://en.wikipedia.org/wiki?curid=22747 |
16,760 | The MAC and LLC layers of IEEE 802 networks such as 802.3 Ethernet, 802.11 Wi-Fi, and 802.15.4 ZigBee operate at the data link layer. | https://en.wikipedia.org/wiki?curid=22747 |
16,761 | The Point-to-Point Protocol (PPP) is a data link layer protocol that can operate over several different physical layers, such as synchronous and asynchronous serial lines. | https://en.wikipedia.org/wiki?curid=22747 |
16,762 | The ITU-T G.hn standard, which provides high-speed local area networking over existing wires (power lines, phone lines and coaxial cables), includes a complete data link layer that provides both error correction and flow control by means of a selective-repeat sliding-window protocol. | https://en.wikipedia.org/wiki?curid=22747 |
16,763 | The network layer provides the functional and procedural means of transferring packets from one node to another connected in "different networks". A network is a medium to which many nodes can be connected, on which every node has an "address" and which permits nodes connected to it to transfer messages to other nodes ... | https://en.wikipedia.org/wiki?curid=22747 |
16,764 | Message delivery at the network layer is not necessarily guaranteed to be reliable; a network layer protocol may provide reliable message delivery, but it need not do so. | https://en.wikipedia.org/wiki?curid=22747 |
16,765 | A number of layer-management protocols, a function defined in the "management annex", ISO 7498/4, belong to the network layer. These include routing protocols, multicast group management, network-layer information and error, and network-layer address assignment. It is the function of the payload that makes these belong... | https://en.wikipedia.org/wiki?curid=22747 |
16,766 | The transport layer provides the functional and procedural means of transferring variable-length data sequences from a source host to a destination host from one application to another across a network, while maintaining the quality-of-service functions. Transport protocols may be connection-oriented or connectionless. | https://en.wikipedia.org/wiki?curid=22747 |
16,767 | This may require breaking large protocol data units or long data streams into smaller chunks called "segments", since the network layer imposes a maximum packet size called the maximum transmission unit (MTU), which depends on the maximum packet size imposed by all data link layers on the network path between the two h... | https://en.wikipedia.org/wiki?curid=22747 |
16,768 | The transport layer also controls the reliability of a given link between a source and destination host through flow control, error control, and acknowledgments of sequence and existence. Some protocols are state- and connection-oriented. This means that the transport layer can keep track of the segments and retransmit... | https://en.wikipedia.org/wiki?curid=22747 |
16,769 | Reliability, however, is not a strict requirement within the transport layer. Protocols like UDP, for example, are used in applications that are willing to accept some packet loss, reordering, errors or duplication. Streaming media, real-time multiplayer games and voice over IP (VoIP) are examples of applications in wh... | https://en.wikipedia.org/wiki?curid=22747 |
16,770 | The OSI connection-oriented transport protocol defines five classes of connection-mode transport protocols ranging from class 0 (which is also known as TP0 and provides the fewest features) to class 4 (TP4, designed for less reliable networks, similar to the Internet). Class 0 contains no error recovery and was designe... | https://en.wikipedia.org/wiki?curid=22747 |
16,771 | An easy way to visualize the transport layer is to compare it with a post office, which deals with the dispatch and classification of mail and parcels sent. A post office inspects only the outer envelope of mail to determine its delivery. Higher layers may have the equivalent of double envelopes, such as cryptographic ... | https://en.wikipedia.org/wiki?curid=22747 |
16,772 | Although not developed under the OSI Reference Model and not strictly conforming to the OSI definition of the transport layer, the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol Suite are commonly categorized as layer-4 protocols within OSI. | https://en.wikipedia.org/wiki?curid=22747 |
16,773 | Transport Layer Security (TLS) does not strictly fit inside the model either. It contains characteristics of the transport and presentation layers. | https://en.wikipedia.org/wiki?curid=22747 |
16,774 | The Session Layer creates the setup, controls the connections, and ends the teardown, between two or more computers, which is called a "session". Since DNS and other Name Resolution Protocols operate in this part of the layer, common functions of the Session Layer include user logon (establishment), name lookup (manage... | https://en.wikipedia.org/wiki?curid=22747 |
16,775 | The Presentation Layer establishes data formatting and data translation into a format specified by the application layer during the encapsulation of outgoing messages while being passed down the protocol stack, and possibly reversed during the deencapsulation of incoming messages when being passed up the protocol stack... | https://en.wikipedia.org/wiki?curid=22747 |
16,776 | The Presentation Layer handles protocol conversion, data encryption, data decryption, data compression, data decompression, incompatibility of data representation between OSs, and graphic commands. The presentation layer transforms data into the form that the application layer accepts, to be sent across a network. Sinc... | https://en.wikipedia.org/wiki?curid=22747 |
16,777 | The application layer is the layer of the OSI model that is closest to the end user, which means both the OSI Application Layer and the user interact directly with software application that implements a component of communication between the client and server, such as File Explorer and Microsoft Word. Such application ... | https://en.wikipedia.org/wiki?curid=22747 |
16,778 | Application-layer functions typically include file sharing, message handling, and database access, through the most common protocols at the application layer, known as HTTP, FTP, SMB/CIFS, TFTP, and SMTP. When identifying communication partners, the application layer determines the identity and availability of communic... | https://en.wikipedia.org/wiki?curid=22747 |
16,779 | Cross-layer functions are services that are not tied to a given layer, but may affect more than one layer. Some orthogonal aspects, such as management and security, involve all of the layers (See ITU-T X.800 Recommendation). These services are aimed at improving the CIA triad—confidentiality, integrity, and availabilit... | https://en.wikipedia.org/wiki?curid=22747 |
16,780 | Cross-layer functions are the norm, in practice, because the availability of a communication service is determined by the interaction between network design and network management protocols. | https://en.wikipedia.org/wiki?curid=22747 |
16,781 | Neither the OSI Reference Model, nor any OSI protocol specifications, outline any programming interfaces, other than deliberately abstract service descriptions. Protocol specifications define a methodology for communication between peers, but the software interfaces are implementation-specific. | https://en.wikipedia.org/wiki?curid=22747 |
16,782 | For example, the Network Driver Interface Specification (NDIS) and Open Data-Link Interface (ODI) are interfaces between the media (layer 2) and the network protocol (layer 3). | https://en.wikipedia.org/wiki?curid=22747 |
16,783 | The table below presents a list of OSI layers, the original OSI protocols, and some "approximate" modern matches. It is very important to note that this correspondence is rough: the OSI model contains idiosyncrasies not found in later systems such as the IP stack in modern Internet. | https://en.wikipedia.org/wiki?curid=22747 |
16,784 | The design of protocols in the TCP/IP model of the Internet does not concern itself with strict hierarchical encapsulation and layering. contains a section entitled "Layering considered harmful". TCP/IP does recognize four broad layers of functionality which are derived from the operating scope of their contained proto... | https://en.wikipedia.org/wiki?curid=22747 |
16,785 | Despite using a different concept for layering than the OSI model, these layers are often compared with the OSI layering scheme in the following manner: | https://en.wikipedia.org/wiki?curid=22747 |
16,786 | These comparisons are based on the original seven-layer protocol model as defined in ISO 7498, rather than refinements in the internal organization of the network layer. | https://en.wikipedia.org/wiki?curid=22747 |
16,787 | The OSI protocol suite that was specified as part of the OSI project was considered by many as too complicated and inefficient, and to a large extent unimplementable. Taking the "forklift upgrade" approach to networking, it specified eliminating all existing networking protocols and replacing them at all layers of the ... | https://en.wikipedia.org/wiki?curid=22747 |
16,788 | Although the OSI model is often still referenced, the Internet protocol suite has become the standard for networking. TCP/IP's pragmatic approach to computer networking and to independent implementations of simplified protocols made it a practical methodology. Some protocols and specifications in the OSI stack remain i... | https://en.wikipedia.org/wiki?curid=22747 |
16,789 | The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high a priori likelihood of its existence, and by extension of obtaining such evidence. As a 2015 article put it, "If life is so easy, someone from somewhere must have come calling by now." | https://en.wikipedia.org/wiki?curid=11579 |
16,790 | Italian-American physicist Enrico Fermi's name is associated with the paradox because of a casual conversation in the summer of 1950 with fellow physicists Edward Teller, Herbert York, and Emil Konopinski. While walking to lunch, the men discussed recent UFO reports and the possibility of faster-than-light travel. The ... | https://en.wikipedia.org/wiki?curid=11579 |
16,791 | There have been many attempts to resolve the Fermi paradox, such as suggesting that intelligent extraterrestrial beings are extremely rare, that the lifetime of such civilizations is short, or that they exist but (for various reasons) humans see no evidence. | https://en.wikipedia.org/wiki?curid=11579 |
16,792 | The following are some of the facts and hypotheses that together serve to highlight the apparent contradiction: | https://en.wikipedia.org/wiki?curid=11579 |
16,793 | Fermi was not the first to ask the question. An earlier implicit mention was by Konstantin Tsiolkovsky in an unpublished manuscript from 1933. He noted "people deny the presence of intelligent beings on the planets of the universe" because "(i) if such beings exist they would have visited Earth, and (ii) if such civili... | https://en.wikipedia.org/wiki?curid=11579 |
16,794 | In 1975, Michael H. Hart published a detailed examination of the paradox, one of the first to do so. He argued that if intelligent extraterrestrials exist, and are capable of space travel, then the galaxy could have been colonized in a time much less than that of the age of the Earth. However, there is no observable ev... | https://en.wikipedia.org/wiki?curid=11579 |
16,795 | Other names closely related to Fermi's question ("Where are they?") include the Great Silence, and "silentium universi" (Latin for "silence of the universe"), though these only refer to one portion of the Fermi Paradox, that humans see no evidence of other civilizations. | https://en.wikipedia.org/wiki?curid=11579 |
16,796 | In the summer of 1950 at Los Alamos National Laboratory in New Mexico, Enrico Fermi and co-workers Emil Konopinski, Edward Teller, and Herbert York had one or several lunchtime conversations. | https://en.wikipedia.org/wiki?curid=11579 |
16,797 | As three of the men walked to lunch, Teller writes that he has a "vague recollection" to the effect that "we talked about flying saucers and the obvious statement that the flying saucers are not real." Konopinski joined the others while the conversation was in progress. He remembered a magazine cartoon which showed ali... | https://en.wikipedia.org/wiki?curid=11579 |
16,798 | Teller writes that he thinks Fermi directed the question to him: "How probable is it that within the next ten years we shall have clear evidence of a material object moving faster than light?" Teller answered one in a million. Fermi said, "This is much too low. The probability is more like ten percent." Teller also wri... | https://en.wikipedia.org/wiki?curid=11579 |
16,799 | Herb York does not remember a previous conversation, although he says it makes sense given how all three later reacted to Fermi's outburst. | https://en.wikipedia.org/wiki?curid=11579 |
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