The Segway PT is a two-wheeled, self-balancing personal transporter by Segway Inc. It was invented by Dean Kamen and brought to market in 2001. HT is an initialism for'human transporter' and PT for'personal transporter'; the Segway PT was developed from the self-balancing iBOT wheelchair, developed at University of Plymouth, in conjunction with BAE Systems and Sumitomo Precision Products. Segway's first patent was filed in 1994 and granted in 1997 followed by others including one submitted in June 1999 and granted in October 2001; the invention and financing of the Segway was the subject of a book, a leak of information prior to publication of the book and the launch of the product led to excited speculation about the device and its importance. John Doerr speculated. South Park devoted an episode to making fun of the hype before the product was released. Steve Jobs was quoted as saying that it was "as big a deal as the PC", The device was unveiled on 3 December 2001, following months of public speculation, in Bryant Park, New York City, on the ABC News morning program Good Morning America with the first units delivered to customers in early 2002.
The original Segway models featured three speed settings: 6 miles per hour, 8 mph with faster turning, 10 mph. Steering of early versions was controlled using a twist grip that varied the speeds of the two motors; the range of the p-Series was 6–10 mi on a charged nickel metal hydride battery with a recharge time of 4–6 hours. In September 2003, the Segway PT was recalled, because if users ignored repeated low battery warnings on the PTs, it could lead them to fall. With a software patch to version 12.0, the PT would automatically slow down and stop in response to detecting low battery power. In August 2006 Segway discontinued all previous models and introduced the i2 and x2 products which were steered by leaning the handlebars to the right or left, had a maximum speed of 12.5 mph from a pair of 2 horsepower Brushless DC electric motor with regenerative braking and a range of up to 15–25 mi, depending on terrain, riding style and state of the batteries. Recharging took 8–10 hours; the i2 and x2 introduced the wireless InfoKey which could show mileage and a trip odometer, as well as put the Segway into Security mode, which locked the wheels and set off an alarm if it was moved, could be used to turn on the PT from up to 15 feet away.
Versions of the product prior to 2011 included: Segway i167 Segway e167: As i167, with addition of electric kickstand Segway p133: Smaller platform and wheels and less powerful motors than the i and e Series with top speed was 10 miles per hour in the p-Series Segway i180: With lithium-ion batteries Segway XT: The first Segway HT designed for recreation Segway i2: The first on-road Segway PT with LeanSteer Segway x2: The first off-road Segway PT with LeanSteerIn March 2014, Segway announced third generation designs, including the i2 SE and x2 SE sport, new LeanSteer frame and powerbase designs, with integrated lighting. Ninebot Inc. a Beijing-based transportation robotics startup and a Segway rival, acquired Segway in April 2015 having raised $80M from Xiaomi and Sequoia Capital. In June 2016 the company launched a smaller self-balancing scooter; as of July 2017 the following self-balancing scooters are available from Segway: ProfessionalSegway i2 SE Segway x2 SE Segway Robot ConsumerNinebot by Segway E+ Ninebot by Segway miniPro The dynamics of the Segway PT are similar to a classic control problem, the inverted pendulum.
It uses brushless DC electric motors in each wheel powered by lithium-ion batteries with balance achieved using tilt sensors, gyroscopic sensors developed by BAE Systems' Advanced Technology Centre. The wheels are driven forward or backward as needed to return its pitch to upright. See also: Personal transporter#International regulation In 2011 the Segway i2 was being marketed to the emergency medical services community; the special police forces trained to protect the public during the 2008 Summer Olympics used the Segway for mobility. The Segway miniPro is available to be used as the mobility section of a robot. Disability Rights Advocates for Technology promoted the use of the Segway PT on sidewalks as an Americans with Disabilities Act of 1990 issue. Segway Inc. cannot however market these devices in the US as medical devices and they have not been approved by the Food and Drug Administration as a medical device. The maximum speed of the Segway PT is 12.5 miles per hour. The product is capable of covering 24 mi on a charged lithium-ion battery, depending on terrain, riding style, the condition of the batteries.
The U. S. Consumer Product Safety Commission does not have Segway-specific recommendations but does say that bicycle helmets are adequate for "low-speed, motor-assisted" scooters. Segway polo Official website
The spinal cord is a long, tubular structure made up of nervous tissue, that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. It encloses the central canal of the spinal cord; the brain and spinal cord together make up the central nervous system. In humans, the spinal cord begins at the occipital bone where it passes through the foramen magnum, meets and enters the spinal canal at the beginning of the cervical vertebrae; the spinal cord extends down to between the second lumbar vertebrae where it ends. The enclosing bony vertebral column protects the shorter spinal cord, it is around 45 cm in men and around 43 cm long in women. The spinal cord has a varying width, ranging from 13 mm thick in the cervical and lumbar regions to 6.4 mm thick in the thoracic area. The spinal cord functions in the transmission of nerve signals from the motor cortex to the body, from the afferent fibers of the sensory neurons to the sensory cortex, it is a center for coordinating many reflexes and contains reflex arcs that can independently control reflexes.
It is the location of groups of spinal interneurons that make up the neural circuits known as central pattern generators. These circuits are responsible for controlling motor instructions for rhythmic movements such as walking; the spinal cord is the main pathway for information connecting the brain and peripheral nervous system. Much shorter than its protecting spinal column, the human spinal cord originates in the brainstem, passes through the foramen magnum, continues through to the conus medullaris near the second lumbar vertebra before terminating in a fibrous extension known as the filum terminale, it is about 45 cm long in men and around 43 cm in women, ovoid-shaped, is enlarged in the cervical and lumbar regions. The cervical enlargement, stretching from the C5 to T1 vertebrae, is where sensory input comes from and motor output goes to the arms and trunk; the lumbar enlargement, located between L1 and S3, handles sensory input and motor output coming from and going to the legs. The spinal cord is continuous with the caudal portion of the medulla, running from the base of the skull to the body of the first lumbar vertebra.
It does not run the full length of the vertebral column in adults. It is made of 31 segments from which branch one pair of sensory nerve roots and one pair of motor nerve roots; the nerve roots merge into bilaterally symmetrical pairs of spinal nerves. The peripheral nervous system is made up of these spinal roots and ganglia; the dorsal roots are afferent fascicles, receiving sensory information from the skin and visceral organs to be relayed to the brain. The roots terminate in dorsal root ganglia, which are composed of the cell bodies of the corresponding neurons. Ventral roots consist of efferent fibers that arise from motor neurons whose cell bodies are found in the ventral gray horns of the spinal cord; the spinal cord are protected by three layers of tissue or membranes called meninges, that surround the canal. The dura mater is the outermost layer, it forms a tough protective coating. Between the dura mater and the surrounding bone of the vertebrae is a space called the epidural space; the epidural space is filled with adipose tissue, it contains a network of blood vessels.
The arachnoid mater, the middle protective layer, is named for its spiderweb-like appearance. The space between the arachnoid and the underlying pia mater is called the subarachnoid space; the subarachnoid space contains cerebrospinal fluid, which can be sampled with a lumbar puncture, or "spinal tap" procedure. The delicate pia mater, the innermost protective layer, is associated with the surface of the spinal cord; the cord is stabilized within the dura mater by the connecting denticulate ligaments, which extend from the enveloping pia mater laterally between the dorsal and ventral roots. The dural sac ends at the vertebral level of the second sacral vertebra. In cross-section, the peripheral region of the cord contains neuronal white matter tracts containing sensory and motor axons. Internal to this peripheral region is the grey matter, which contains the nerve cell bodies arranged in the three grey columns that give the region its butterfly-shape; this central region surrounds the central canal, an extension of the fourth ventricle and contains cerebrospinal fluid.
The spinal cord is elliptical in cross section, being compressed dorsolaterally. Two prominent grooves, or sulci, run along its length; the posterior median sulcus is the groove in the dorsal side, the anterior median fissure is the groove in the ventral side. The human spinal cord is divided into segments. Six to eight motor nerve rootlets branch out of right and left ventro lateral sulci in a orderly manner. Nerve rootlets combine to form nerve roots. Sensory nerve rootlets form off right and left dorsal lateral sulci and form sensory nerve roots; the ventral and dorsal roots combine to form one on each side of the spinal cord. Spinal nerves, with the exception of C1 and C2, form inside the intervertebral foramen; these rootlets form the demarcation between the peripheral nervous systems. The grey column, in the center of the cord, is shaped like a butterfly and consists of cell bodies of interneurons, motor neurons, neuroglia cells and unmyelinated axons; the anterior and posterior grey column present as projections of the grey matter and are known as the horns of the spinal cord.
Together, the gr
A biological membrane or biomembrane is an enclosing or separating membrane that acts as a selectively permeable barrier within living things. Biological membranes, in the form of eukaryotic cell membranes, consist of a phospholipid bilayer with embedded and peripheral proteins used in communication and transportation of chemicals and ions; the bulk of lipid in a cell membrane provides a fluid matrix for proteins to rotate and laterally diffuse for physiological functioning. Proteins are adapted to high membrane fluidity environment of lipid bilayer with the presence of an annular lipid shell, consisting of lipid molecules bound to surface of integral membrane proteins; the cell membranes are different from the isolating tissues formed by layers of cells, such as mucous membranes, basement membranes, serous membranes. The lipid bilayer consists of two layers - an inner leaflet; the components of bilayers are distributed unequally between the two surfaces to create asymmetry between the outer and inner surfaces.
This asymmetric organization is important for cell functions such as cell signaling. The asymmetry of the biological membrane reflects the different functions of the two leaflets of the membrane; as seen in the fluid membrane model of the phospholipid bilayer, the outer leaflet and inner leaflet of the membrane are asymmetrical in their composition. Certain proteins and lipids rest only on one surface of not the other. • Both the plasma membrane and internal membranes have cytosolic and exoplasmic faces • This orientation is maintained during membrane trafficking – proteins, glycoconjugates facing the lumen of the ER and Golgi get expressed on the extracellular side of the plasma membrane. In eucaryotic cells, new phospholipids are manufactured by enzymes bound to the part of the endoplasmic reticulum membrane that faces the cytosol; these enzymes, which use free fatty acids as substrates, deposit all newly made phospholipids into the cytosolic half of the bilayer. To enable the membrane as a whole to grow evenly, half of the new phospholipid molecules have to be transferred to the opposite monolayer.
This transfer is catalyzed by enzymes called flippases. In the plasma membrane, flippases transfer specific phospholipids selectively, so that different types become concentrated in each monolayer. Using selective flippases is not the only way to produce asymmetry in lipid bilayers, however. In particular, a different mechanism operates for glycolipids—the lipids that show the most striking and consistent asymmetric distribution in animal cells; the biological membrane is made up of lipids with hydrophilic heads. The hydrophobic tails are hydrocarbon tails whose length and saturation is important in characterizing the cell. Lipid rafts occur when lipid proteins aggregate in domains in the membrane; these help organize membrane components into localized areas that are involved in specific processes, such as signal transduction. Red blood cells, or erythrocytes, have a unique lipid composition; the bilayer of red blood cells is composed of cholesterol and phospholipids in equal proportions by weight.
Erythrocyte membrane plays a crucial role in blood clotting. In the bilayer of red blood cells is phosphatidylserine; this is in the cytoplasmic side of the membrane. However, it is flipped to the outer membrane to be used during blood clotting. Phospholipid bilayers contain different proteins; these membrane proteins have various functions and characteristics and catalyze different chemical reactions. Integral proteins span the membranes with different domains on either side. Integral proteins hold strong association with the lipid bilayer and cannot become detached, they will dissociate only with chemical treatment. Peripheral proteins are unlike integral proteins in that they hold weak interactions with the surface of the bilayer and can become dissociated from the membrane. Peripheral proteins create membrane asymmetry. Oligosaccharides are sugar containing polymers. In the membrane, they can be covalently bound to lipids to form glycolipids or covalently bound to proteins to form glycoproteins.
Membranes contain sugar-containing lipid molecules known as glycolipids. In the bilayer, the sugar groups of glycolipids are exposed at the cell surface, where they can form hydrogen bonds. Glycolipids provide the most extreme example of asymmetry in the lipid bilayer. Glycolipids perform a vast number of functions in the biological membrane that are communicative, including cell recognition and cell-cell adhesion. Glycoproteins are integral proteins, they play an important role in the immune protection. The phospholipid bilayer is formed due to the aggregation of membrane lipids in aqueous solutions. Aggregation is caused by the hydrophobic effect, where hydrophobic ends come into contact with each other and are sequestered away from water; this arrangement maximises hydrogen bonding between hydrophilic heads and water while minimising unfavorable contact between hydrophobic tails and water. The increase in available hydrogen bonding increases the entropy of the system, creating a spontaneous process.
Biological molecules are amphiphilic or amphipathic, i.e. are hydrophobic and hydrophilic. The phospholipid bilayer contains charged hydrophilic headgroups; the lipids contain hydrophobic tails, which meet with the hydrophobic tails of the complementary layer. The hydrophobic tails are fatty acids that differ in lengths; the interactions of lipids the hydrophobic tails, determine the lipid bilayer physical properties such as fluidity. Membranes in cells define enclosed spaces or compartments in which
National Institutes of Health
The National Institutes of Health is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late 1870s and is now part of the United States Department of Health and Human Services; the majority of NIH facilities are located in Maryland. The NIH conducts its own scientific research through its Intramural Research Program and provides major biomedical research funding to non-NIH research facilities through its Extramural Research Program; as of 2013, the IRP had 1,200 principal investigators and more than 4,000 postdoctoral fellows in basic and clinical research, being the largest biomedical research institution in the world, while, as of 2003, the extramural arm provided 28% of biomedical research funding spent annually in the U. S. or about US$26.4 billion. The NIH comprises 27 separate institutes and centers of different biomedical disciplines and is responsible for many scientific accomplishments, including the discovery of fluoride to prevent tooth decay, the use of lithium to manage bipolar disorder, the creation of vaccines against hepatitis, Haemophilus influenzae, human papillomavirus.
NIH's roots extend back to the Marine Hospital Service in the late 1790s that provided medical relief to sick and disabled men in the U. S. Navy. By 1870, a network of marine hospitals had developed and was placed under the charge of a medical officer within the Bureau of the Treasury Department. In the late 1870s, Congress allocated funds to investigate the causes of epidemics like cholera and yellow fever, it created the National Board of Health, making medical research an official government initiative. In 1887, a laboratory for the study of bacteria, the Hygienic Laboratory, was established at the Marine Hospital in New York. In the early 1900s, Congress began appropriating funds for the Marine Hospital Service. By 1922, this organization changed its name to Public Health Services and established a Special Cancer Investigations laboratory at Harvard Medical School; this marked the beginning of a partnership with universities. In 1930, the Hygienic Laboratory was re-designated as the National Institute of Health by the Ransdell Act, was given $750,000 to construct two NIH buildings.
Over the next few decades, Congress would increase funding tremendously to the NIH, various institutes and centers within the NIH were created for specific research programs. In 1944, the Public Health Service Act was approved, the National Cancer Institute became a division of NIH. In 1948, the name changed from National Institute of Health to National Institutes of Health. In the 1960s, virologist and cancer researcher Chester M. Southam injected HeLa cancer cells into patients at the Jewish Chronic Disease Hospital; when three doctors resigned after refusing to inject patients without their consent, the experiment gained considerable media attention. The NIH was a major source of funding for Southam's research and had required all research involving human subjects to obtain their consent prior to any experimentation. Upon investigating all of their grantee institutions, the NIH discovered that the majority of them did not protect the rights of human subjects. From on, the NIH has required all grantee institutions to approve any research proposals involving human experimentation with review boards.
In 1967, the Division of Regional Medical Programs was created to administer grants for research for heart disease and strokes. That same year, the NIH director lobbied the White House for increased federal funding in order to increase research and the speed with which health benefits could be brought to the people. An advisory committee was formed to oversee further development of the NIH and its research programs. By 1971 cancer research was in full force and President Nixon signed the National Cancer Act, initiating a National Cancer Program, President's Cancer Panel, National Cancer Advisory Board, 15 new research and demonstration centers. Funding for the NIH has been a source of contention in Congress, serving as a proxy for the political currents of the time. In 1992, the NIH encompassed nearly 1 percent of the federal government's operating budget and controlled more than 50 percent of all funding for health research, 85 percent of all funding for health studies in universities. While government funding for research in other disciplines has been increasing at a rate similar to inflation since the 1970s, research funding for the NIH nearly tripled through the 1990s and early 2000s, but has remained stagnant since then.
By the 1990s, the NIH committee focus had shifted to DNA research, launched the Human Genome Project. The NIH Office of the Director is the central office responsible for setting policy for NIH, for planning and coordinating the programs and activities of all NIH components; the NIH Director plays an active role in shaping outlook. The Director is responsible for providing leadership to the Institutes and Centers by identifying needs and opportunities in efforts involving multiple Institutes. Within this Office is the Division of Program Coordination and Strategic Initiatives with 12 divisions including: Office of AIDS Research Office of Research on Women's Health Office of Disease Prevention Sexual and Gender Minority Research Office Tribal Heath Research Office Office of Program Evaluation and PerformancePrevious directors: Joseph J. Kinyoun, served August 1887 – April 30, 1899 Milton J. Rosenau, served May 1, 1899 – September 30, 1909 John F. Anderson, served October 1, 1909 – November 19, 1915 George W. McCoy, served November 20, 1915 – January 31, 1937 Lewis R. Thompson, served February 1, 1937 – January 31, 1942 R
National Institute of Neurological Disorders and Stroke
The National Institute of Neurological Disorders and Stroke is a part of the U. S. National Institutes of Health, it conducts and funds research on brain and nervous system disorders and has a budget of just over US$1.5 billion. The mission of NINDS is "to reduce the burden of neurological disease—a burden borne by every age group, every segment of society, people all over the world". NINDS has established two major branches for research: an extramural branch that funds studies outside the NIH, an intramural branch that funds research inside the NIH. Most of NINDS' budget goes to fund extramural research. NINDS' basic science research focuses on studies of the fundamental biology of the brain and nervous system, neurodegeneration and memory, motor control, brain repair, synapses. NINDS funds clinical research related to diseases and disorders of the brain and nervous system, e.g. AIDS, Alzheimer disease, muscular dystrophy, multiple sclerosis, Parkinson disease, spinal cord injury and traumatic brain injury.
Established in 1950 by the U. S. Congress as the National Institute of Neurological Diseases and Blindness to help handle the casualties of World War II, NINDS grew along with the NIH. During the 1950s and 1960s, NINDS and the NIH had strong Congressional support and received significant appropriations. However, this funding declined in 1968; the NINDS was created in 1950 to study and treat the neurological and psychiatric casualties of World War II. Many service people had returned with serious brain injuries, nerve damage, psychic trauma. According to one estimate, "neurologically disabled veterans in the postwar years accounted for about 25 percent of the patients in general hospitals and 10 percent of those in psychiatric hospitals". In addition, 1.7 million American men had been rejected for military service due to a neuropsychiatric condition or learning disorder. NINDS was created as part of an effort to "revive the extinct neurological field". At the time and its focus on "emotional tensions due to interpersonal and cultural maladjustments" held sway in US medicine, while neurology, with its focus on the inner workings of the brain, had fallen out of favor.
During WWII, all of the administrative positions of the American Board of Psychiatry and Neurology held by the US armed services were filled by psychiatrists. After the war, a survey by the Veteran's Administration of the members of the American Board of Psychiatry and Neurology found that 48 were neurologists and 456 were psychiatrists. In 1948, Abe B. Baker, chair of neurology and psychiatry at the University of Minnesota, formed the American Academy of Neurology to give young neurologists a national organization to join. However, sustained research in neurology was not possible without a national institute. In the late 1940s and early 1950s, vocal American Neurological Association members testified before Congress, arguing that there needed to be such an institute, they articulated the arguments, made on a smaller scale by citizens' groups for diseases such as multiple sclerosis, cerebral palsy, muscular dystrophy and blindness. Members of the research grants committee of the National Institute of Mental Health, founded in 1949, contend that they helped provide an impetus for the new institute, as when reviewing grant applications they saw a significant number of neurological projects and proposed a separate institute for them.
The National Institute of Neurological Disorders and Blindness, the original name for the NINDS, was established on November 22, 1950, three months after President Harry Truman signed the Omnibus Medical Research Act on August 15, 1950. The legislation had been passed with the efforts of Senator Claude Pepper, responsible for helping the majority of the NIH institutes get their start, wealthy New York entrepreneur Mary Lasker, Fight for Sight founder Mildred Weisenfeld, who had retinitis pigmentosa. NINDB was not conceived of coherently at the beginning. For example, blindness was added because some concerned citizens raised the issue with Lasker who, in turn asked Congressman Andrew Biemiller to do so in Congress, he added it to the bill, being sympathetic with the cause since his mother was blind. NINDB was "responsible for conducting and supporting research and training in the 200 neurological and sensory disorders that affected 20 million individuals in the United States and were'the first cause of permanent crippling and the third cause of death.'"
Because the etiology of the most common neurological diseases was poorly understood, NINDB undertook both clinical and basic research on the disorders themselves and on treatments. In the beginning, the NINDB had an Advisory Council made of six medical professional and lay people, all appointed by the U. S. Surgeon General, they granted its funds. The NINDB's first annual budget was US$1.23 million. This came from the existing NIH budget, as Congress had not appropriated any new funds for the institute when it was created. Although the NINDB's budget was increased to $1.99 million in 1952, there was still no money for new research programs. Moreover, the institute had a lab; as Ingrid Farreras writes in her history, "The research conducted by the institute was still supported by the NIMH and the institute's survival was unclear."The NINDB's first director, Pearce Bailey, was appointed on October 3, 1951, came with experience from the Neuropsyc
Hemosiderin or haemosiderin is an iron-storage complex. It is only found within cells and appears to be a complex of ferritin, denatured ferritin and other material; the iron within deposits of hemosiderin is poorly available to supply iron when needed. Hemosiderin can be identified histologically with Perls' Prussian-blue stain. In normal animals, hemosiderin deposits are small and inapparent without special stains. Excessive accumulation of hemosiderin is detected within cells of the mononuclear phagocyte system or within epithelial cells of liver and kidney. Several disease processes result in deposition of larger amounts of hemosiderin in tissues. Hemosiderin is most found in macrophages and is abundant in situations following hemorrhage, suggesting that its formation may be related to phagocytosis of red blood cells and hemoglobin. Hemosiderin can accumulate in different organs in various diseases. Iron is required by many of the chemical reactions in the body but is toxic when not properly contained.
Thus, many methods of iron storage have developed. Hemosiderin forms after bleeding; when blood leaves a ruptured blood vessel, the red blood cell dies, the hemoglobin of the cell is released into the extracellular space. Phagocytic cells called macrophages engulf the hemoglobin to degrade it, producing hemosiderin and biliverdin. Excessive systemic accumulations of hemosiderin may occur in macrophages in the liver, spleen, lymph nodes, bone marrow; these accumulations may be caused by excessive red blood cell destruction, excessive iron uptake/hyperferraemia, or decreased iron utilization /uptake hypoferraemia. Hemosiderin may deposit in diseases associated with iron overload; these diseases are diseases in which chronic blood loss requires frequent blood transfusions, such as sickle cell anemia and thalassemia
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