Paleontology or palaeontology is the scientific study of life that existed prior to, sometimes including, the start of the Holocene Epoch. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments. Paleontological observations have been documented as far back as the 5th century BC; the science became established in the 18th century as a result of Georges Cuvier's work on comparative anatomy, developed in the 19th century. The term itself originates from Greek παλαιός, palaios, "old, ancient", ὄν, on, "being, creature" and λόγος, logos, "speech, study". Paleontology lies on the border between biology and geology, but differs from archaeology in that it excludes the study of anatomically modern humans, it now uses techniques drawn from a wide range of sciences, including biochemistry and engineering. Use of all these techniques has enabled paleontologists to discover much of the evolutionary history of life all the way back to when Earth became capable of supporting life, about 3.8 billion years ago.
As knowledge has increased, paleontology has developed specialised sub-divisions, some of which focus on different types of fossil organisms while others study ecology and environmental history, such as ancient climates. Body fossils and trace fossils are the principal types of evidence about ancient life, geochemical evidence has helped to decipher the evolution of life before there were organisms large enough to leave body fossils. Estimating the dates of these remains is essential but difficult: sometimes adjacent rock layers allow radiometric dating, which provides absolute dates that are accurate to within 0.5%, but more paleontologists have to rely on relative dating by solving the "jigsaw puzzles" of biostratigraphy. Classifying ancient organisms is difficult, as many do not fit well into the Linnaean taxonomy classifying living organisms, paleontologists more use cladistics to draw up evolutionary "family trees"; the final quarter of the 20th century saw the development of molecular phylogenetics, which investigates how organisms are related by measuring the similarity of the DNA in their genomes.
Molecular phylogenetics has been used to estimate the dates when species diverged, but there is controversy about the reliability of the molecular clock on which such estimates depend. The simplest definition of paleontology is "the study of ancient life"; the field seeks information about several aspects of past organisms: "their identity and origin, their environment and evolution, what they can tell us about the Earth's organic and inorganic past". Paleontology is one of the historical sciences, along with archaeology, astronomy, cosmology and history itself: it aims to describe phenomena of the past and reconstruct their causes. Hence it has three main elements: description of past phenomena; when trying to explain the past and other historical scientists construct a set of hypotheses about the causes and look for a smoking gun, a piece of evidence that accords with one hypothesis over the others. Sometimes the smoking gun is discovered by a fortunate accident during other research. For example, the discovery by Luis and Walter Alvarez of iridium, a extra-terrestrial metal, in the Cretaceous–Tertiary boundary layer made asteroid impact the most favored explanation for the Cretaceous–Paleogene extinction event, although the contribution of volcanism continues to be debated.
The other main type of science is experimental science, said to work by conducting experiments to disprove hypotheses about the workings and causes of natural phenomena. This approach cannot prove a hypothesis, since some experiment may disprove it, but the accumulation of failures to disprove is compelling evidence in favor. However, when confronted with unexpected phenomena, such as the first evidence for invisible radiation, experimental scientists use the same approach as historical scientists: construct a set of hypotheses about the causes and look for a "smoking gun". Paleontology lies between biology and geology since it focuses on the record of past life, but its main source of evidence is fossils in rocks. For historical reasons, paleontology is part of the geology department at many universities: in the 19th and early 20th centuries, geology departments found fossil evidence important for dating rocks, while biology departments showed little interest. Paleontology has some overlap with archaeology, which works with objects made by humans and with human remains, while paleontologists are interested in the characteristics and evolution of humans as a species.
When dealing with evidence about humans and paleontologists may work together – for example paleontologists might identify animal or plant fossils around an archaeological site, to discover what the people who lived there ate. In addition, paleontology borrows techniques from other sciences, including biology, ecology, chemistry and mathematics. For example, geochemical signatures from rocks may help to discover when life first arose on Earth, analyses of carbon isotope ratios may help to identify climate changes and to explain major transitions such as the Permian–Triassic extinction event. A recent discipline, molecular phylogenetics, compares the DNA and RNA of modern organisms to re-construct the "family trees" of their
United States National Library of Medicine
The United States National Library of Medicine, operated by the United States federal government, is the world's largest medical library. Located in Bethesda, the NLM is an institute within the National Institutes of Health, its collections include more than seven million books, technical reports, microfilms and images on medicine and related sciences, including some of the world's oldest and rarest works. The current director of the NLM is Patricia Flatley Brennan. Since 1879, the National Library of Medicine has published the Index Medicus, a monthly guide to articles, in nearly five thousand selected journals; the last issue of Index Medicus was printed in December 2004, but this information is offered in the accessible PubMed, among the more than fifteen million MEDLINE journal article references and abstracts going back to the 1960s and 1.5 million references going back to the 1950s. The National Library of Medicine runs the National Center for Biotechnology Information, which houses biological databases that are accessible on the Internet through the Entrez search engine and Lister Hill National Center For Biomedical Communications.
As the United States National Release Center for SNOMED CT, NLM provides SNOMED CT data and resources to licensees of the NLM UMLS Metathesaurus. NLM maintains ClinicalTrials.gov registry for human observational studies. The Toxicology and Environmental Health Program was established at the National Library of Medicine in 1967 and is charged with developing computer databases compiled from the medical literature and from the files of governmental and nongovernmental organizations; the program has implemented several information systems for chemical emergency response and public education, such as the Toxicology Data Network, TOXMAP, Tox Town, Wireless Information System for Emergency Responders and the Household Products Database. These resources are accessible without charge on the internet; the United States National Library of Medicine Radiation Emergency Management System provides: Guidance for health care providers physicians, about clinical diagnosis and treatment of radiation injury during radiological and nuclear emergencies Just-in-time, evidence-based, usable information with sufficient background and context to make complex issues understandable to those without formal radiation medicine expertise Web-based information that may be downloaded in advance, so that it would be available during an emergency if the Internet were not accessibleRadiation Emergency Management System is produced by the United States Department of Health and Human Services, Office of the Assistant Secretary for Preparedness and Response, Office of Planning and Emergency Operations, in cooperation with the National Library of Medicine, Division of Specialized Information Services, with subject matter experts from the National Cancer Institute, the Centers for Disease Control and Prevention, many U.
S. and international consultants. The Extramural Division provides grants to support research in medical information science and to support planning and development of computer and communications systems in medical institutions. Research and exhibitions on the history of medicine and the life sciences are supported by the History of Medicine Division. In April 2008 the current exhibition Against the Odds: Making a Difference in Global Health was launched. National Center for Biotechnology Information is an intramural division within National Library of Medicine that creates public databases in molecular biology, conducts research in computational biology, develops software tools for analyzing molecular and genomic data, disseminates biomedical information, all for the better understanding of processes affecting human health and disease. For details of the pre-1956 history of the Library, see Library of the Surgeon General's Office; the precursor of the National Library of Medicine, established in 1836, was the Library of the Surgeon General's Office, a part of the office of the Surgeon General of the United States Army.
The Armed Forces Institute of Pathology and its Medical Museum were founded in 1862 as the Army Medical Museum. Throughout their history the Library of the Surgeon General's Office and the Army Medical Museum shared quarters. From 1866 to 1887, they were housed in Ford's Theatre after production there was stopped, following the assassination of President Abraham Lincoln. In 1956, the library collection was transferred from the control of the U. S. Department of Defense to the Public Health Service of the Department of Health and Welfare and renamed the National Library of Medicine, through the instrumentality of Frank Bradway Rogers, the director from 1956 to 1963; the library moved to its current quarters in Bethesda, Maryland, on the campus of the National Institutes of Health, in 1962. JournalReview.org National Library of Medicine classification system PubMed Miles, Wyndham D.. A History of the National Library of Medicine: The Nation's Treasury of Medical Knowledge. U. S. Government Printing Office.
P. 531. ISBN 978-0-16-002644-7. NLM 8218545. Reznick, Jeffrey. US National Library of Medicine. Charleston, South Carolina: Arcadia Publishing. ISBN 978-1-4671-2608-3. LCCN 2017931439. NLM 101706419. Schullian, Dorothy. "The National Library of Medicine. I"; the Library Quarterly: Information, Policy. 28: 1–17. Doi:10.1086/618482. JSTOR 4304714. NLM 0135203. Schullian, Dorothy. "The National Library of Medicine. II"; the Library Quarterly: Information, Policy. 28: 95–121. Doi:10.1086/618521. JSTOR 4304753. NLM 0135203. Past and future of biomedical informat
Thomson Reuters Corporation is a Canadian multinational mass media and information firm. The firm was founded in Toronto, Canada, where it is headquartered at 333 Bay Street in Downtown Toronto. Thomson Reuters shares are cross listed on the Toronto Stock Exchange and the New York Stock Exchange. Thomson Reuters was created by the Thomson Corporation's purchase of the British company Reuters Group in April 2008, is majority owned by The Woodbridge Company, a holding company for the Thomson family. Thomson Reuters was ranked as Canada's "leading corporate brand" in the 2010 Interbrand Best Canadian Brands ranking. Thomson Reuters operates in more than 100 countries, has more than 45,000 employees; the company was founded by Roy Thomson in 1934 in Ontario as the publisher of The Timmins Daily Press. In 1953, Thomson moved to Scotland the following year, he consolidated his media position in Scotland in 1957 when he won the franchise for Scottish Television. In 1959, he bought the Kemsley Group, a purchase that gave him control of the Sunday Times.
He separately acquired the Times in 1967. He moved into the airline business in 1965, when he acquired Britannia Airways and into oil and gas exploration in 1971 when he participated in a consortium to exploit reserves in the North Sea. In the 1970s, following the death of Thomson, the company withdrew from national newspapers and broadcast media, selling the Times, the Sunday Times and Scottish Television and instead moved into publishing, buying Sweet & Maxwell in 1988; the company at this time was known as the International Thomson Organisation Ltd. In 1989, ITOL merged with Thomson Newspapers. In 1996, The Thomson Corporation acquired West Publishing, a purveyor of legal research and solutions including Westlaw; the Company was founded by Paul Julius Reuter in 1851 in London as a business transmitting stock market quotations. Reuter set up his "Submarine Telegraph" office in October 1851 and negotiated a contract with the London Stock Exchange to provide stock prices from the continental exchanges in return for access to London prices, which he supplied to stockbrokers in Paris, France.
In 1865, Reuters in London was the first organization to report the assassination of Abraham Lincoln. The company was involved in developing the use of radio in 1923, it was acquired by the British National & Provincial Press in 1941 and first listed on the London Stock Exchange in 1984. Reuters began to grow in the 1980s, widening the range of its business products and expanding its global reporting network for media and economic services: key product launches included Equities 2000, Dealing 2000-2, Business Briefing, Reuters Television for the financial markets, 3000 Series and the Reuters 3000 Xtra service; the Thomson Corporation acquired Reuters Group PLC to form Thomson Reuters on April 17, 2008. Thomson Reuters operated under a dual-listed company structure and had two parent companies, both of which were publicly listed — Thomson Reuters Corporation and Thomson Reuters PLC. In 2009, it unified its dual listed company structure and stopped its listing on the London Stock Exchange and NASDAQ.
It is now listed only as Thomson Reuters Corporation on the New York Stock Exchange and Toronto Stock Exchange. On February 13, 2013, Thomson Reuters announced it would cut 2,500 jobs to cut cost in its Legal and Risk division. On October 29, 2013, Thomson Reuters announced it would cut another 3,000 jobs in those same three divisions; the Thomson-Reuters merger transaction was reviewed by the U. S. Department of Justice and by the European Commission. On February 19, 2008, both the Department of Justice and the Commission cleared the transaction subject to minor divestments; the Department of Justice required the parties to sell copies of the data contained in the following products: Thomson's WorldScope, a global fundamentals product. The proposed settlement further requires the licensing of related intellectual property, access to personnel, transitional support to ensure that the buyer of each set of data can continue to update its database so as to continue to offer users a viable and competitive product.
The European Commission imposed similar divestments: according to the Commission's press release, "the parties committed to divest the databases containing the content sets of such financial information products, together with relevant assets and customer base as appropriate to allow purchasers of the databases and assets to establish themselves as a credible competitive force in the marketplace in competition with the merged entity, re-establishing the pre-merger rivalry in the respective fields."These remedies were viewed as minor given the scope of the transaction. According to the Financial Times, "the remedy proposed by the competition authorities will affect no more than $25m of the new Thomson Reuters group’s $13bn-plus combined revenues."The transaction was cleared by the Canadian Competition Bureau. In November 2009, The European Commission opened formal anti-trust proceedings against Thomson Reuters concerning a potential infringement of the EC Treaty's rules on abuse of a dominant market position.
The Commission investigated Thomson Reuters' practices in the area of real-time market datafeeds, in particular whether customers or competitors were prevented from translating Reuters Instrument Codes to alternative identification codes of other datafeed suppliers to the detriment of competition. In Dec
Natural History Museum, Berlin
The Natural History Museum is a natural history museum located in Berlin, Germany. It exhibits a vast range of specimens from various segments of natural history and in such domain it is one of three major museums in Germany alongside Naturmuseum Senckenberg in Frankfurt and Museum Koenig in Bonn. German speakers call this museum Museum für Naturkunde since this is the term that can be read in the façade's Museum, it is called Naturkundemuseum or Museum für Naturkunde in Berlin so that it can be distinguished from other museums in Germany named as Museum für Naturkunde. The museum's official name changed through time, it had been founded in 1810 as a part of the Berlin University, which changed its name to Humboldt University of Berlin in 1949. This is why the Natural History Museum in Berlin had been known for a long part of its history as the "Humboldt Museum", but in 2009 it left the university to join the Leibniz Association; the current official name is Museum für Naturkunde – Leibniz-Institut für Evolutions- und Biodiversitätsforschung and the "Humboldt" name is no longer related to this museum.
Furthermore: there is another Humboldt-Museum in Berlin in Tegel Palace dealing with brothers Wilhelm and Alexander von Humboldt. The museum houses more than 30 million zoological and mineralogical specimens, including more than ten thousand type specimens, it is famous for two exhibits: the largest mounted dinosaur in the world, a well-preserved specimen of the earliest known bird, Archaeopteryx. The museum's mineral collections date back to the Prussian Academy of Sciences of 1700. Important historic zoological specimens include those recovered by the German deep-sea Valdiva expedition, the German Southpolar Expedition, the German Sunda Expedition. Expeditions to fossil beds in Tendaguru in former Deutsch Ostafrika unearthed rich paleontological treasures; the collections are so extensive that less than 1 in 5000 specimens is exhibited, they attract researchers from around the world. Additional exhibits include a mineral collection representing 75% of the minerals in the world, a large meteor collection, the largest piece of amber in the world.
In November 2018 the German government and the city of Berlin decided to expand and improve the building for more than 600 million €. Since the museum renovation in 2007, a large hall explains biodiversity and the processes of evolution, while several rooms feature changing special exhibitions; the specimen of Giraffatitan brancai in the central exhibit hall is the largest mounted dinosaur skeleton in the world. It is composed of fossilized bones recovered by the German paleontologist Werner Janensch from the fossil-rich Tendaguru beds of Tanzania between 1909 and 1913; the remains are from one gigantic animal, except for a few tail bones, which belong to another animal of the same size and species. The historical mount was 12.72 m tall, 22.25 m long. In 2007 it was remounted according to new scientific evidence, reaching a height of 13.27 m. When living, the long-tailed, long-necked herbivore weighed 50 t. While the Diplodocus carnegiei mounted next to it exceeds it in length, the Berlin specimen is taller, far more massive.
The "Berlin Specimen" of Archaeopteryx lithographica, is displayed in the central exhibit hall. The dinosaur-like body with an attached tooth-filled head, claws, long lizard-like tail, the clear impression of feathers in the surrounding stone is strong evidence of the link between reptiles and birds; the Archaeopteryx is a transitional fossil. Recovered from the German Solnhofen limestone beds in 1871, it is only the third Archaeopteryx to be discovered and the most complete; the first specimen, a single 150-million-year-old feather found in 1860, is in the possession of the museum. The MFN's collection comprises 250,000 specimens of minerals, of which 4,500 are on exhibit in the Hall of Minerals. A large hall explains the principles of evolution, it was opened in 2007 after a major renovation of parts of the building. The Museum für Naturkunde now exhibits one of the best-preserved Tyrannosaurus skeletons worldwide. Of 300 bones, 170 have been preserved, which puts it in the third position among others.
Minerals in the museum were part of the collection of instructors from the Berlin Mining Academy. The University of Berlin was founded in 1810, acquired the first of these collections in 1814, under the aegis of the new Museum of Mineralogy. In 1857, the paleontology department was founded, 1854 a department of petrography and general geology was added. By 1886 the university was overflowing with collections, so design began on a new building nearby at Invalidenstraße 43, which opened as the Museum für Naturkunde in 1889; the museum was built on the site of a former ironworks and this is reflected in two spectacular cast iron stairwells within the building. Of particular significance is the contribution of the first director after the move to the new building. In the past the museum consisted of the entire collections being open to the public, but Karl Möbius instigated a clear split between a public exhibition sp
OCLC Online Computer Library Center, Incorporated d/b/a OCLC is an American nonprofit cooperative organization "dedicated to the public purposes of furthering access to the world's information and reducing information costs". It was founded in 1967 as the Ohio College Library Center. OCLC and its member libraries cooperatively produce and maintain WorldCat, the largest online public access catalog in the world. OCLC is funded by the fees that libraries have to pay for its services. OCLC maintains the Dewey Decimal Classification system. OCLC began in 1967, as the Ohio College Library Center, through a collaboration of university presidents, vice presidents, library directors who wanted to create a cooperative computerized network for libraries in the state of Ohio; the group first met on July 5, 1967 on the campus of the Ohio State University to sign the articles of incorporation for the nonprofit organization, hired Frederick G. Kilgour, a former Yale University medical school librarian, to design the shared cataloging system.
Kilgour wished to merge the latest information storage and retrieval system of the time, the computer, with the oldest, the library. The plan was to merge the catalogs of Ohio libraries electronically through a computer network and database to streamline operations, control costs, increase efficiency in library management, bringing libraries together to cooperatively keep track of the world's information in order to best serve researchers and scholars; the first library to do online cataloging through OCLC was the Alden Library at Ohio University on August 26, 1971. This was the first online cataloging by any library worldwide. Membership in OCLC is based on use of services and contribution of data. Between 1967 and 1977, OCLC membership was limited to institutions in Ohio, but in 1978, a new governance structure was established that allowed institutions from other states to join. In 2002, the governance structure was again modified to accommodate participation from outside the United States.
As OCLC expanded services in the United States outside Ohio, it relied on establishing strategic partnerships with "networks", organizations that provided training and marketing services. By 2008, there were 15 independent United States regional service providers. OCLC networks played a key role in OCLC governance, with networks electing delegates to serve on the OCLC Members Council. During 2008, OCLC commissioned two studies to look at distribution channels. In early 2009, OCLC negotiated new contracts with the former networks and opened a centralized support center. OCLC provides bibliographic and full-text information to anyone. OCLC and its member libraries cooperatively produce and maintain WorldCat—the OCLC Online Union Catalog, the largest online public access catalog in the world. WorldCat has holding records from private libraries worldwide; the Open WorldCat program, launched in late 2003, exposed a subset of WorldCat records to Web users via popular Internet search and bookselling sites.
In October 2005, the OCLC technical staff began a wiki project, WikiD, allowing readers to add commentary and structured-field information associated with any WorldCat record. WikiD was phased out; the Online Computer Library Center acquired the trademark and copyrights associated with the Dewey Decimal Classification System when it bought Forest Press in 1988. A browser for books with their Dewey Decimal Classifications was available until July 2013; until August 2009, when it was sold to Backstage Library Works, OCLC owned a preservation microfilm and digitization operation called the OCLC Preservation Service Center, with its principal office in Bethlehem, Pennsylvania. The reference management service QuestionPoint provides libraries with tools to communicate with users; this around-the-clock reference service is provided by a cooperative of participating global libraries. Starting in 1971, OCLC produced catalog cards for members alongside its shared online catalog. OCLC commercially sells software, such as CONTENTdm for managing digital collections.
It offers the bibliographic discovery system WorldCat Discovery, which allows for library patrons to use a single search interface to access an institution's catalog, database subscriptions and more. OCLC has been conducting research for the library community for more than 30 years. In accordance with its mission, OCLC makes its research outcomes known through various publications; these publications, including journal articles, reports and presentations, are available through the organization's website. OCLC Publications – Research articles from various journals including Code4Lib Journal, OCLC Research, Reference & User Services Quarterly, College & Research Libraries News, Art Libraries Journal, National Education Association Newsletter; the most recent publications are displayed first, all archived resources, starting in 1970, are available. Membership Reports – A number of significant reports on topics ranging from virtual reference in libraries to perceptions about library funding. Newsletters – Current and archived newsletters for the library and archive community.
Presentations – Presentations from both guest speakers and OCLC research from conferences and other events. The presentations are organized into five categories: Conference presentations, Dewey presentations, Distinguished Seminar Series, Guest presentations, Research staff
Peer review is the evaluation of work by one or more people with similar competences as the producers of the work. It functions as a form of self-regulation by qualified members of a profession within the relevant field. Peer review methods are used to maintain quality standards, improve performance, provide credibility. In academia, scholarly peer review is used to determine an academic paper's suitability for publication. Peer review can be categorized by the type of activity and by the field or profession in which the activity occurs, e.g. medical peer review. Professional peer review focuses on the performance of professionals, with a view to improving quality, upholding standards, or providing certification. In academia, peer review is used to inform in decisions related to faculty tenure. Henry Oldenburg was a British philosopher, seen as the'father' of modern scientific peer review. WA prototype is a professional peer-review process recommended in the Ethics of the Physician written by Ishāq ibn ʻAlī al-Ruhāwī.
He stated that a visiting physician had to make duplicate notes of a patient's condition on every visit. When the patient was cured or had died, the notes of the physician were examined by a local medical council of other physicians, who would decide whether the treatment had met the required standards of medical care. Professional peer review is common in the field of health care, where it is called clinical peer review. Further, since peer review activity is segmented by clinical discipline, there is physician peer review, nursing peer review, dentistry peer review, etc. Many other professional fields have some level of peer review process: accounting, engineering and forest fire management. Peer review is used in education to achieve certain learning objectives as a tool to reach higher order processes in the affective and cognitive domains as defined by Bloom's taxonomy; this may take a variety of forms, including mimicking the scholarly peer review processes used in science and medicine.
Scholarly peer review is the process of subjecting an author's scholarly work, research, or ideas to the scrutiny of others who are experts in the same field, before a paper describing this work is published in a journal, conference proceedings or as a book. The peer review helps the publisher decide whether the work should be accepted, considered acceptable with revisions, or rejected. Peer review requires a community of experts in a given field, who are qualified and able to perform reasonably impartial review. Impartial review of work in less narrowly defined or inter-disciplinary fields, may be difficult to accomplish, the significance of an idea may never be appreciated among its contemporaries. Peer review is considered necessary to academic quality and is used in most major scholarly journals, but it by no means prevents publication of invalid research. Traditionally, peer reviewers have been anonymous, but there is a significant amount of open peer review, where the comments are visible to readers with the identities of the peer reviewers disclosed as well.
The European Union has been using peer review in the "Open Method of Co-ordination" of policies in the fields of active labour market policy since 1999. In 2004, a program of peer reviews started in social inclusion; each program sponsors about eight peer review meetings in each year, in which a "host country" lays a given policy or initiative open to examination by half a dozen other countries and the relevant European-level NGOs. These meet over two days and include visits to local sites where the policy can be seen in operation; the meeting is preceded by the compilation of an expert report on which participating "peer countries" submit comments. The results are published on the web; the United Nations Economic Commission for Europe, through UNECE Environmental Performance Reviews, uses peer review, referred to as "peer learning", to evaluate progress made by its member countries in improving their environmental policies. The State of California is the only U. S. state to mandate scientific peer review.
In 1997, the Governor of California signed into law Senate Bill 1320, Chapter 295, statutes of 1997, which mandates that, before any CalEPA Board, Department, or Office adopts a final version of a rule-making, the scientific findings and assumptions on which the proposed rule are based must be submitted for independent external scientific peer review. This requirement is incorporated into the California Health and Safety Code Section 57004. Medical peer review may be distinguished in 4 classifications: 1) clinical peer review. Additionally, "medical peer review" has been used by the American Medical Association to refer not only to the process of improving quality and safety in health care organizations, but to the process of rating clinical behavior or compliance with professional society membership standards. Thus, the terminology has poor standardization and specificity as a database search term. To an outsider, the anonymous, pre-publication peer review process is opaque. Certain journals are accused of not carrying out stringent peer review in order to more expand their customer base in journals where authors pay a fee before public
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science by reporting new research. Articles in scientific journals are written by active scientists such as students and professors instead of professional journalists. There are thousands of scientific journals in publication, many more have been published at various points in the past. Most journals are specialized, although some of the oldest journals such as Nature publish articles and scientific papers across a wide range of scientific fields. Scientific journals contain articles that have been peer reviewed, in an attempt to ensure that articles meet the journal's standards of quality, scientific validity. Although scientific journals are superficially similar to professional magazines, they are quite different. Issues of a scientific journal are read casually, as one would read a magazine; the publication of the results of research is an essential part of the scientific method. If they are describing experiments or calculations, they must supply enough details that an independent researcher could repeat the experiment or calculation to verify the results.
Each such journal article becomes part of the permanent scientific record. Articles in scientific journals can be used in higher education. Scientific articles allow researchers to keep up to date with the developments of their field and direct their own research. An essential part of a scientific article is citation of earlier work; the impact of articles and journals is assessed by counting citations. Some classes are devoted to the explication of classic articles, seminar classes can consist of the presentation by each student of a classic or current paper. Schoolbooks and textbooks have been written only on established topics, while the latest research and more obscure topics are only accessible through scientific articles. In a scientific research group or academic department it is usual for the content of current scientific journals to be discussed in journal clubs. Public funding bodies require the results to be published in scientific journals. Academic credentials for promotion into academic ranks are established in large part by the number and impact of scientific articles published.
Many doctoral programs allow for thesis by publication, where the candidate is required to publish a certain number of scientific articles. Articles tend to be technical, representing the latest theoretical research and experimental results in the field of science covered by the journal, they are incomprehensible to anyone except for researchers in the field and advanced students. In some subjects this is inevitable given the nature of the content. Rigorous rules of scientific writing are enforced by the editors. Articles are either original articles reporting new results or reviews of current literature. There are scientific publications that bridge the gap between articles and books by publishing thematic volumes of chapters from different authors. Many journals have a regional focus, specializing in publishing papers from a particular geographic region, like African Invertebrates; the history of scientific journals dates from 1665, when the French Journal des sçavans and the English Philosophical Transactions of the Royal Society first began systematically publishing research results.
Over a thousand ephemeral, were founded in the 18th century, the number has increased after that. Prior to mid-20th century, peer review was not always necessary, but it became compulsory; the authors of scientific articles are active researchers instead of journalists. As such, the authors receive no compensation from the journal. However, their funding bodies may require them to publish in scientific journals; the paper is submitted to the journal office, where the editor considers the paper for appropriateness, potential scientific impact and novelty. If the journal's editor considers the paper appropriate, the paper is submitted to scholarly peer review. Depending on the field and paper, the paper is sent to 1–3 reviewers for evaluation before they can be granted permission to publish. Reviewers are expected to check the paper for soundness of its scientific argument, i.e. if the data collected or considered in the paper support the conclusion offered. Novelty is key: existing work must be appropriately considered and referenced, new results improving on the state of the art presented.
Reviewers are unpaid and not a part of the journal staff—instead, they should be "peers", i.e. researchers in the same field as the paper in question. The standards that a journal uses to determine publication can vary widely; some journals, such as Nature, Science, PNAS, Physical Review Letters, have a reputation of publishing articles that mark a fundamental breakthrough in their respective fields. In many fields, a formal or informal hierarchy of scientific journals exists. In some countries, journal rankings can be utilized for funding decisions and evaluation of individual researchers, although they are poorly suited for that purpose. For scientific journals Reproducibility and Replicability are core concepts that allow other scientists to check and reproduce the results under the same conditions described