Neuroscience is the scientific study of the nervous system. It is a multidisciplinary branch of biology that combines physiology, molecular biology, developmental biology, mathematical modeling and psychology to understand the fundamental and emergent properties of neurons and neural circuits; the understanding of the biological basis of learning, behavior and consciousness has been described by Eric Kandel as the "ultimate challenge" of the biological sciences. The scope of neuroscience has broadened over time to include different approaches used to study the nervous system at different scales and the techniques used by neuroscientists have expanded enormously, from molecular and cellular studies of individual neurons to imaging of sensory and cognitive tasks in the brain; the earliest study of the nervous system dates to ancient Egypt. Trepanation, the surgical practice of either drilling or scraping a hole into the skull for the purpose of curing headaches or mental disorders, or relieving cranial pressure, was first recorded during the Neolithic period.
Manuscripts dating to 1700 BC indicate that the Egyptians had some knowledge about symptoms of brain damage. Early views on the function of the brain regarded it to be a "cranial stuffing" of sorts. In Egypt, from the late Middle Kingdom onwards, the brain was removed in preparation for mummification, it was believed at the time. According to Herodotus, the first step of mummification was to "take a crooked piece of iron, with it draw out the brain through the nostrils, thus getting rid of a portion, while the skull is cleared of the rest by rinsing with drugs."The view that the heart was the source of consciousness was not challenged until the time of the Greek physician Hippocrates. He believed that the brain was not only involved with sensation—since most specialized organs are located in the head near the brain—but was the seat of intelligence. Plato speculated that the brain was the seat of the rational part of the soul. Aristotle, believed the heart was the center of intelligence and that the brain regulated the amount of heat from the heart.
This view was accepted until the Roman physician Galen, a follower of Hippocrates and physician to Roman gladiators, observed that his patients lost their mental faculties when they had sustained damage to their brains. Abulcasis, Avicenna and Maimonides, active in the Medieval Muslim world, described a number of medical problems related to the brain. In Renaissance Europe, René Descartes, Thomas Willis and Jan Swammerdam made several contributions to neuroscience. Luigi Galvani's pioneering work in the late 1700s set the stage for studying the electrical excitability of muscles and neurons. In the first half of the 19th century, Jean Pierre Flourens pioneered the experimental method of carrying out localized lesions of the brain in living animals describing their effects on motricity and behavior. In 1843 Emil du Bois-Reymond demonstrated the electrical nature of the nerve signal, whose speed Hermann von Helmholtz proceeded to measure, in 1875 Richard Caton found electrical phenomena in the cerebral hemispheres of rabbits and monkeys.
Adolf Beck published in 1890 similar observations of spontaneous electrical activity of the brain of rabbits and dogs. Studies of the brain became more sophisticated after the invention of the microscope and the development of a staining procedure by Camillo Golgi during the late 1890s; the procedure used a silver chromate salt to reveal the intricate structures of individual neurons. His technique was used by Santiago Ramón y Cajal and led to the formation of the neuron doctrine, the hypothesis that the functional unit of the brain is the neuron. Golgi and Ramón y Cajal shared the Nobel Prize in Physiology or Medicine in 1906 for their extensive observations and categorizations of neurons throughout the brain. In parallel with this research, work with brain-damaged patients by Paul Broca suggested that certain regions of the brain were responsible for certain functions. At the time, Broca's findings were seen as a confirmation of Franz Joseph Gall's theory that language was localized and that certain psychological functions were localized in specific areas of the cerebral cortex.
The localization of function hypothesis was supported by observations of epileptic patients conducted by John Hughlings Jackson, who inferred the organization of the motor cortex by watching the progression of seizures through the body. Carl Wernicke further developed the theory of the specialization of specific brain structures in language comprehension and production. Modern research through neuroimaging techniques, still uses the Brodmann cerebral cytoarchitectonic map anatomical definitions from this era in continuing to show that distinct areas of the cortex are activated in the execution of specific tasks. During the 20th century, neuroscience began to be recognized as a distinct academic discipline in its own right, rather than as studies of the nervous system within other disciplines. Eric Kandel and collaborators have cited David Rioch, Francis O. Schmitt, Stephen Kuffler as having played critical roles in establishing the field. Rioch originated the integration of basic anatomical and physiological research with clinical psychiatry at the Walter Reed Army Institute of Research, starting in the 1950s.
During the same period, Schmitt established a neuroscience research program within the Biology Department at the Massachusetts Institute of Technology, bringing together biology, chemistry and mathematics. The first freestandin
Time is the indefinite continued progress of existence and events that occur in irreversible succession through the past, in the present, the future. Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, to quantify rates of change of quantities in material reality or in the conscious experience. Time is referred to as a fourth dimension, along with three spatial dimensions. Time has long been an important subject of study in religion and science, but defining it in a manner applicable to all fields without circularity has eluded scholars. Diverse fields such as business, sports, the sciences, the performing arts all incorporate some notion of time into their respective measuring systems. Time in physics is unambiguously operationally defined as "what a clock reads". See Units of Time. Time is one of the seven fundamental physical quantities in both the International System of Units and International System of Quantities.
Time is used to define other quantities – such as velocity – so defining time in terms of such quantities would result in circularity of definition. An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event constitutes one standard unit such as the second, is useful in the conduct of both advanced experiments and everyday affairs of life; the operational definition leaves aside the question whether there is something called time, apart from the counting activity just mentioned, that flows and that can be measured. Investigations of a single continuum called spacetime bring questions about space into questions about time, questions that have their roots in the works of early students of natural philosophy. Temporal measurement has occupied scientists and technologists, was a prime motivation in navigation and astronomy. Periodic events and periodic motion have long served as standards for units of time. Examples include the apparent motion of the sun across the sky, the phases of the moon, the swing of a pendulum, the beat of a heart.
The international unit of time, the second, is defined by measuring the electronic transition frequency of caesium atoms. Time is of significant social importance, having economic value as well as personal value, due to an awareness of the limited time in each day and in human life spans. Speaking, methods of temporal measurement, or chronometry, take two distinct forms: the calendar, a mathematical tool for organising intervals of time, the clock, a physical mechanism that counts the passage of time. In day-to-day life, the clock is consulted for periods less than a day whereas the calendar is consulted for periods longer than a day. Personal electronic devices display both calendars and clocks simultaneously; the number that marks the occurrence of a specified event as to hour or date is obtained by counting from a fiducial epoch – a central reference point. Artifacts from the Paleolithic suggest that the moon was used to reckon time as early as 6,000 years ago. Lunar calendars were among the first to appear, with years of either 13 lunar months.
Without intercalation to add days or months to some years, seasons drift in a calendar based on twelve lunar months. Lunisolar calendars have a thirteenth month added to some years to make up for the difference between a full year and a year of just twelve lunar months; the numbers twelve and thirteen came to feature prominently in many cultures, at least due to this relationship of months to years. Other early forms of calendars originated in Mesoamerica in ancient Mayan civilization; these calendars were religiously and astronomically based, with 18 months in a year and 20 days in a month, plus five epagomenal days at the end of the year. The reforms of Julius Caesar in 45 BC put the Roman world on a solar calendar; this Julian calendar was faulty in that its intercalation still allowed the astronomical solstices and equinoxes to advance against it by about 11 minutes per year. Pope Gregory XIII introduced a correction in 1582. During the French Revolution, a new clock and calendar were invented in attempt to de-Christianize time and create a more rational system in order to replace the Gregorian calendar.
The French Republican Calendar's days consisted of ten hours of a hundred minutes of a hundred seconds, which marked a deviation from the 12-based duodecimal system used in many other devices by many cultures. The system was abolished in 1806. A large variety of devices have been invented to measure time; the study of these devices is called horology. An Egyptian device that dates to c. 1500 BC, similar in shape to a bent T-square, measured the passage of time from the shadow cast by its crossbar on a nonlinear rule. The T was oriented eastward in the mornings. At noon, the device was turned around so. A sundial uses a gnomon to cast a shadow on a set of markings calibrated to the hour; the position of the shadow marks the hour in local time. The idea to separate the day into smaller parts is credited to Egyptians because of their sundials, which operated on a duodecimal system; the importance of the number 12 is due to the number of lunar cycles in a year and the number of stars used to count the passage of night.
The most precise timekeeping device of the ancient
Leland Stanford Junior University is a private research university in Stanford, California. Stanford is known for its academic strength, proximity to Silicon Valley, ranking as one of the world's top universities; the university was founded in 1885 by Leland and Jane Stanford in memory of their only child, Leland Stanford Jr. who had died of typhoid fever at age 15 the previous year. Stanford was a U. S. Senator and former Governor of California who made his fortune as a railroad tycoon; the school admitted its first students on October 1, 1891, as a coeducational and non-denominational institution. Stanford University struggled financially after the death of Leland Stanford in 1893 and again after much of the campus was damaged by the 1906 San Francisco earthquake. Following World War II, Provost Frederick Terman supported faculty and graduates' entrepreneurialism to build self-sufficient local industry in what would be known as Silicon Valley; the university is one of the top fundraising institutions in the country, becoming the first school to raise more than a billion dollars in a year.
The university is organized around three traditional schools consisting of 40 academic departments at the undergraduate and graduate level and four professional schools that focus on graduate programs in Law, Medicine and Business. Stanford's undergraduate program is the most selective in the United States by acceptance rate. Students compete in 36 varsity sports, the university is one of two private institutions in the Division I FBS Pac-12 Conference, it has gained the most for a university. Stanford athletes have won 512 individual championships, Stanford has won the NACDA Directors' Cup for 24 consecutive years, beginning in 1994–1995. In addition, Stanford students and alumni have won 270 Olympic medals including 139 gold medals; as of October 2018, 83 Nobel laureates, 27 Turing Award laureates, 8 Fields Medalists have been affiliated with Stanford as students, faculty or staff. In addition, Stanford University is noted for its entrepreneurship and is one of the most successful universities in attracting funding for start-ups.
Stanford alumni have founded a large number of companies, which combined produce more than $2.7 trillion in annual revenue and have created 5.4 million jobs as of 2011 equivalent to the 10th largest economy in the world. Stanford is the alma mater of 30 living billionaires and 17 astronauts, is one of the leading producers of members of the United States Congress. Stanford University was founded in 1885 by Leland and Jane Stanford, dedicated to Leland Stanford Jr, their only child; the institution opened in 1891 on Stanford's previous Palo Alto farm. Despite being impacted by earthquakes in both 1906 and 1989, the campus was rebuilt each time. In 1919, The Hoover Institution on War and Peace was started by Herbert Hoover to preserve artifacts related to World War I; the Stanford Medical Center, completed in 1959, is a teaching hospital with over 800 beds. The SLAC National Accelerator Laboratory, established in 1962, performs research in particle physics. Jane and Leland Stanford modeled their university after the great eastern universities, most Cornell University and Harvard University.
Stanford opened being called the "Cornell of the West" in 1891 due to faculty being former Cornell affiliates including its first president, David Starr Jordan. Both Cornell and Stanford were among the first to have higher education be accessible and open to women as well as to men. Cornell is credited as one of the first American universities to adopt this radical departure from traditional education, Stanford became an early adopter as well. Most of Stanford University is on one of the largest in the United States, it is located on the San Francisco Peninsula, in the northwest part of the Santa Clara Valley 37 miles southeast of San Francisco and 20 miles northwest of San Jose. In 2008, 60% of this land remained undeveloped. Stanford's main campus includes a census-designated place within unincorporated Santa Clara County, although some of the university land is within the city limits of Palo Alto; the campus includes much land in unincorporated San Mateo County, as well as in the city limits of Menlo Park and Portola Valley.
The academic central campus is adjacent to Palo Alto, bounded by El Camino Real, Stanford Avenue, Junipero Serra Boulevard, Sand Hill Road. The United States Postal Service has assigned it two ZIP Codes: 94305 for campus mail and 94309 for P. O. box mail. It lies within area code 650. Stanford operates or intends to operate in various locations outside of its central campus. On the founding grant: Jasper Ridge Biological Preserve is a 1,200-acre natural reserve south of the central campus owned by the university and used by wildlife biologists for research. SLAC National Accelerator Laboratory is a facility west of the central campus operated by the university for the Department of Energy, it contains the longest linear particle accelerator in the world, 2 miles on 426 acres of land. Golf course and a seasonal lake: The university has its own golf course and a seasonal lake, both home to the vulnerable California tiger salamander; as of 2012 Lake Laguni
The hypothesis of linguistic relativity holds that the structure of a language affects its speakers' world view or cognition. Known as the Sapir–Whorf hypothesis, or Whorfianism, the principle is defined to include two versions: the strong hypothesis and the weak hypothesis: The strong version says that language determines thought and that linguistic categories limit and determine cognitive categories; the weak version says that usage only influence thought and decisions. The term "Sapir–Whorf hypothesis" is considered a misnomer by linguists for several reasons: Edward Sapir and Benjamin Lee Whorf never co-authored any works, never stated their ideas in terms of a hypothesis; the distinction between a weak and a strong version of this hypothesis is a invention. The idea was first expressed by 19th-century thinkers, such as Wilhelm von Humboldt, who saw language as the expression of the spirit of a nation. Members of the early 20th-century school of American anthropology headed by Franz Boas and Edward Sapir embraced forms of the idea to one degree or another, including in a 1928 meeting of the Linguistic Society of America, but Sapir in particular wrote more against than in favor of anything like linguistic determinism.
Sapir's student, Benjamin Lee Whorf, came to be seen as the primary proponent as a result of his published observations of how he perceived linguistic differences to have consequences in human cognition and behavior. Harry Hoijer, another of Sapir's students, introduced the term "Sapir–Whorf hypothesis" though the two scholars never formally advanced any such hypothesis. A strong version of relativist theory was developed from the late 1920s by the German linguist Leo Weisgerber. Whorf's principle of linguistic relativity was reformulated as a testable hypothesis by Roger Brown and Eric Lenneberg who conducted experiments designed to find out whether color perception varies between speakers of languages that classified colors differently; as the study of the universal nature of human language and cognition came into focus in the 1960s the idea of linguistic relativity fell out of favor among linguists. A 1969 study by Brent Berlin and Paul Kay demonstrated the existence of universal semantic constraints in the field of colour terminology which were seen to discredit the existence of linguistic relativity in this domain, although this conclusion has been disputed by relativist researchers.
From the late 1980s, a new school of linguistic relativity scholars has examined the effects of differences in linguistic categorization on cognition, finding broad support for non-deterministic versions of the hypothesis in experimental contexts. Some effects of linguistic relativity have been shown in several semantic domains, although they are weak. A balanced view of linguistic relativity is espoused by most linguists holding that language influences certain kinds of cognitive processes in non-trivial ways, but that other processes are better seen as arising from connectionist factors. Research is focused on exploring the ways and extent; the principle of linguistic relativity and the relation between language and thought has received attention in varying academic fields from philosophy to psychology and anthropology, it has inspired and coloured works of fiction and the invention of constructed languages. The strongest form of the theory is linguistic determinism, which holds that language determines the range of cognitive processes.
The hypothesis of linguistic determinism is now agreed to be false. This is the weaker form, proposing that language provides constraints in some areas of cognition, but that it is by no means determinative. Research on weaker forms has produced positive empirical evidence for a relationship; the idea that language and thought are intertwined is ancient. Plato argued against sophist thinkers such as Gorgias of Leontini, who held that the physical world cannot be experienced except through language. Plato held instead that the world consisted of eternal ideas and that language should reflect these ideas as as possible. Following Plato, St. Augustine, for example, held the view that language was labels applied to existing concepts; this view remained prevalent throughout the Middle Ages. Roger Bacon held the opinion that language was but a veil covering up eternal truths, hiding them from human experience. For Immanuel Kant, language was but one of several tools used by humans to experience the world.
In the late 18th and early 19th centuries, the idea of the existence of different national characters, or "Volksgeister", of different ethnic groups was the moving force behind the German romantics school and the beginning ideologies of ethnic nationalism. Although himself a Swede, Emanuel Swedenborg inspired several of the German Romantics; as early as 1749, he alludes to something along the lines of linguistic relativity in commenting on a passage in the table of nations in the book of Genesis: "Everyone according to his language, according to their families, as to their nations." This signifies. "Language," in its inner meaning, signifies opinion, thus persuasions. This is because there is a correspondence of the language with the intellectual part of man, or with his thought, like that of an effect with its cause. In 1771 he spelled this out more explicitl
Virtual International Authority File
The Virtual International Authority File is an international authority file. It is a joint project of several national libraries and operated by the Online Computer Library Center. Discussion about having a common international authority started in the late 1990s. After a series of failed attempts to come up with a unique common authority file, the new idea was to link existing national authorities; this would present all the benefits of a common file without requiring a large investment of time and expense in the process. The project was initiated by the US Library of Congress, the German National Library and the OCLC on August 6, 2003; the Bibliothèque nationale de France joined the project on October 5, 2007. The project transitioned to being a service of the OCLC on April 4, 2012; the aim is to link the national authority files to a single virtual authority file. In this file, identical records from the different data sets are linked together. A VIAF record receives a standard data number, contains the primary "see" and "see also" records from the original records, refers to the original authority records.
The data are available for research and data exchange and sharing. Reciprocal updating uses the Open Archives Initiative Protocol for Metadata Harvesting protocol; the file numbers are being added to Wikipedia biographical articles and are incorporated into Wikidata. VIAF's clustering algorithm is run every month; as more data are added from participating libraries, clusters of authority records may coalesce or split, leading to some fluctuation in the VIAF identifier of certain authority records. Authority control Faceted Application of Subject Terminology Integrated Authority File International Standard Authority Data Number International Standard Name Identifier Wikipedia's authority control template for articles Official website VIAF at OCLC
International Standard Serial Number
An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is helpful in distinguishing between serials with the same title. ISSN are used in ordering, interlibrary loans, other practices in connection with serial literature; the ISSN system was first drafted as an International Organization for Standardization international standard in 1971 and published as ISO 3297 in 1975. ISO subcommittee TC 46/SC 9 is responsible for maintaining the standard; when a serial with the same content is published in more than one media type, a different ISSN is assigned to each media type. For example, many serials are published both in electronic media; the ISSN system refers to these types as electronic ISSN, respectively. Conversely, as defined in ISO 3297:2007, every serial in the ISSN system is assigned a linking ISSN the same as the ISSN assigned to the serial in its first published medium, which links together all ISSNs assigned to the serial in every medium.
The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers. As an integer number, it can be represented by the first seven digits; the last code digit, which may be 0-9 or an X, is a check digit. Formally, the general form of the ISSN code can be expressed as follows: NNNN-NNNC where N is in the set, a digit character, C is in; the ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, C=5. To calculate the check digit, the following algorithm may be used: Calculate the sum of the first seven digits of the ISSN multiplied by its position in the number, counting from the right—that is, 8, 7, 6, 5, 4, 3, 2, respectively: 0 ⋅ 8 + 3 ⋅ 7 + 7 ⋅ 6 + 8 ⋅ 5 + 5 ⋅ 4 + 9 ⋅ 3 + 5 ⋅ 2 = 0 + 21 + 42 + 40 + 20 + 27 + 10 = 160 The modulus 11 of this sum is calculated. For calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, counting from the right.
The modulus 11 of the sum must be 0. There is an online ISSN checker. ISSN codes are assigned by a network of ISSN National Centres located at national libraries and coordinated by the ISSN International Centre based in Paris; the International Centre is an intergovernmental organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, the ISDS Register otherwise known as the ISSN Register. At the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept. An ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an anonymous identifier associated with a serial title, containing no information as to the publisher or its location. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change. Since the ISSN applies to an entire serial a new identifier, the Serial Item and Contribution Identifier, was built on top of it to allow references to specific volumes, articles, or other identifiable components.
Separate ISSNs are needed for serials in different media. Thus, the print and electronic media versions of a serial need separate ISSNs. A CD-ROM version and a web version of a serial require different ISSNs since two different media are involved. However, the same ISSN can be used for different file formats of the same online serial; this "media-oriented identification" of serials made sense in the 1970s. In the 1990s and onward, with personal computers, better screens, the Web, it makes sense to consider only content, independent of media; this "content-oriented identification" of serials was a repressed demand during a decade, but no ISSN update or initiative occurred. A natural extension for ISSN, the unique-identification of the articles in the serials, was the main demand application. An alternative serials' contents model arrived with the indecs Content Model and its application, the digital object identifier, as ISSN-independent initiative, consolidated in the 2000s. Only in 2007, ISSN-L was defined in the