Summary

HandWiki is the world's largest wiki-style encyclopedia dedicated to science, technology and computing. It allows you to create and edit articles as long as you have external citations and login account. In addition, this is a content management environment that can be used for collaborative editing of original scholarly content, such as books, manuals, monographs and tutorials.

Expand All
Entries
Topic Review
List of Mathematicians (B)
This is a list of mathematicians in alphabetical order beginning with 'B'.
  • 1.9K
  • 31 Oct 2022
Topic Review
Sun-Ni Law
Sun-Ni's Law (or Sun and Ni's Law, also known as memory-bounded speedup), is a memory-bounded speedup model which states that as computing power increases the corresponding increase in problem size is constrained by the system’s memory capacity. In general, as a system grows in computational power, the problems run on the system increase in size. Analogous to Amdahl's law, which says that the problem size remains constant as system sizes grow, and Gustafson's law, which proposes that the problem size should scale but be bound by a fixed amount of time, Sun-Ni's Law states the problem size should scale but be bound by the memory capacity of the system. Sun-Ni's Law was initially proposed by Xian-He Sun and Lionel Ni at the Proceedings of IEEE Supercomputing Conference 1990. With the increasing disparity between CPU speed and memory data access latency, application execution time often depends on the memory speed of the system. As predicted by Sun and Ni, data access has become the premier performance bottleneck for high-end computing. From this fact one can see the intuition behind Sun-Ni's Law, as system resources increase, applications are often bottlenecked by memory speed and bandwidth, thus an application can achieve a larger speedup by utilizing all the memory capacity in the system. Sun-Ni's Law can be applied to different layers of a memory hierarchy system, from L1 cache to main memory. Through its memory-bounded function,W=G(M), it reveals the trade-off between computing and memory in algorithm and system architecture design. All three speedup models, Sun-Ni, Gustafson, and Amdahl, provide a metric to analyze speedup for Parallel computing. Amdahl’s law focuses on the time reduction for a given fixed-size problem. Amdahl’s law states that the sequential portion of the problem (algorithm) limits the total speedup that can be achieved as system resources increase. Gustafson’s law suggests that it is beneficial to build a large-scale parallel system as the speedup can grow linearly with the system size if the problem size is scaled up to maintain a fixed execution time. Yet as memory access latency often becomes the dominant factor in an application’s execution time, applications may not scale up to meet the time bound constraint. Sun-Ni's Law, instead of constraining the problem size by time, constrains the problem by the memory capacity of the system, or in other words bounds based on memory. Sun-Ni's Law is a generalization of Amdahl's Law and Gustafson's Law. When the memory-bounded function G(M)=1, it resolves to Amdahl's law, when the memory-bounded function G(M)=m,the number of processors, it resolves to Gustafson's Law.
  • 1.0K
  • 31 Oct 2022
Topic Review
Telepathology
Telepathology is the practice of pathology at a distance. It uses telecommunications technology to facilitate the transfer of image-rich pathology data between distant locations for the purposes of diagnosis, education, and research. Performance of telepathology requires that a pathologist selects the video images for analysis and the rendering of diagnoses. The use of "television microscopy", the forerunner of telepathology, did not require that a pathologist have physical or virtual "hands-on" involvement in the selection of microscopic fields-of-view for analysis and diagnosis. An academic pathologist, Ronald S. Weinstein, M.D., coined the term "telepathology" in 1986. In a medical journal editorial, Weinstein outlined the actions that would be needed to create remote pathology diagnostic services. He and his collaborators published the first scientific paper on robotic telepathology. Weinstein was also granted the first United States patents for robotic telepathology systems and telepathology diagnostic networks. Weinstein is known to many as the "father of telepathology". In Norway , Eide and Nordrum implemented the first sustainable clinical telepathology service in 1989; this is still in operation decades later. A number of clinical telepathology services have benefited many thousands of patients in North America, Europe, and Asia. Telepathology has been successfully used for many applications, including the rendering of histopathology tissue diagnoses at a distance. Although digital pathology imaging, including virtual microscopy, is the mode of choice for telepathology services in developed countries, analog telepathology imaging is still used for patient services in some developing countries.
  • 546
  • 31 Oct 2022
Topic Review
Targeted Immunization Strategies
Targeted immunization strategies are approaches designed to increase the immunization level of populations and decrease the chances of epidemic outbreaks. Though often in regards to use in healthcare practices and the administration of vaccines to prevent biological epidemic outbreaks, these strategies refer in general to immunization schemes in complex networks, biological, social or artificial in nature. Identification of at-risk groups and individuals with higher odds of spreading the disease often plays an important role in these strategies.
  • 813
  • 31 Oct 2022
Topic Review
Fire Knife
The fire knife is a traditional Samoan cultural implement that is used in ceremonial dances. It was originally composed of a machete wrapped in towels on both ends with a portion of the blade exposed in the middle. Tribal performers of fire knife dancing (or Siva Afi or even "Ailao Afi" as it is called in Samoa) dance while twirling the knife and doing other acrobatic stunts. The towels are set afire during the dances thus explaining the name.
  • 2.3K
  • 31 Oct 2022
Topic Review
Black Belt (U.S. Region)
The Black Belt is a region of the Southern United States. The term originally described the prairies and dark fertile soil of central Alabama and northeast Mississippi. Because this area in the 19th century was historically developed for cotton plantations based on enslaved African American labor, the term became associated with these conditions. It was generally applied to a much larger agricultural region in the Southern United States, which was characterized by a history of cotton plantation agriculture in the 19th century and a high percentage of African Americans outside metropolitan areas. The enslaved peoples were freed after the American Civil War, and many continued to work in agriculture afterward. Their descendants make up much of the African-American population of the United States. During the first half of the 19th Century, as many as one million enslaved Africans were transported through sales in the domestic slave trade to the Deep South in a forced migration to work as laborers for the region's cotton plantations. After having lived enslaved for several generations in the area, many remained as rural workers, tenant farmers and sharecroppers after the Civil War and emancipation. Beginning in the early 20th century and up to 1970, a total of six million black people left the South in the Great Migration to find work and other opportunities in the industrial cities of the Northeast, Midwest, and West. Because of relative isolation and lack of economic development, the rural communities in the Black Belt have historically faced acute poverty, rural exodus, inadequate education programs, low educational attainment, poor health care, urban decay, substandard housing, and high levels of crime and unemployment. In December 2017, the Special Rapporteur of the Office of the United Nations High Commissioner for Human Rights declared that Alabama was the most impoverished area in the developed world. Given the history of decades of racial segregation into the late 20th century, African-American residents have been the most disproportionately affected, although these problems apply broadly to all ethnic groups in the rural Black Belt. The region and its boundaries have varying definitions, but it is generally considered a band through the center of the Deep South, although stretching from as far north as Delaware to as far west as East Texas.
  • 7.0K
  • 31 Oct 2022
Topic Review
Hypoactive Sexual Desire Disorder
Hypoactive sexual desire disorder (HSDD), hyposexuality or inhibited sexual desire (ISD) is considered a sexual dysfunction in some jurisdictions and is characterized as a lack or absence of sexual fantasies and desire for sexual activity, as judged by a clinician. For this to be regarded as a disorder, it must cause marked distress or interpersonal difficulties and not be better accounted for by another mental disorder, a drug (legal or illegal), or some other medical condition. A person with ISD will not start, or respond to their partner's desire for, sexual activity. HSDD affects approximately 10% of all pre-menopausal women in the United States, or about 6 million women. There are various subtypes. HSDD can be general (general lack of sexual desire) or situational (still has sexual desire, but lacks sexual desire for current partner), and it can be acquired (HSDD started after a period of normal sexual functioning) or lifelong (the person has always had no/low sexual desire.) In the DSM-5, HSDD was split into male hypoactive sexual desire disorder and female sexual interest/arousal disorder. It was first included in the DSM-III under the name inhibited sexual desire disorder, but the name was changed in the DSM-III-R. Other terms used to describe the phenomenon include sexual aversion and sexual apathy. More informal or colloquial terms are frigidity and frigidness.
  • 2.2K
  • 31 Oct 2022
Topic Review
Miscanthus Giganteus
Miscanthus × giganteus, the giant miscanthus, is a sterile hybrid of Miscanthus sinensis and Miscanthus sacchariflorus. It is a perennial grass with bamboo-like stems that can grow to heights of more than 4 metres (13 ft) in one season (from the third season onwards). Just like Pennisetum purpureum, Arundo donax and Saccharum ravennae, it is also called elephant grass. Miscanthus × giganteus' perennial nature, its ability to grow on marginal land, its water efficiency, non-invasiveness, low fertilizer needs, significant carbon sequestration and high yield have sparked a lot of interest among researchers, with some arguing that it has "ideal" energy crop properties. Some argue that it can provide negative emissions, while others highlight its water cleaning and soil enhancing qualities. There are practical and economic challenges related to its use in the existing, fossil based combustion infrastructure, however. Torrefaction and other fuel upgrading techniques are being explored as countermeasures to this problem.
  • 2.6K
  • 03 Nov 2022
Topic Review
Raft (Computer Science)
Raft is a consensus algorithm designed as an alternative to the Paxos family of algorithms. It was meant to be more understandable than Paxos by means of separation of logic, but it is also formally proven safe and offers some additional features. Raft offers a generic way to distribute a state machine across a cluster of computing systems, ensuring that each node in the cluster agrees upon the same series of state transitions. It has a number of open-source reference implementations, with full-specification implementations in Go, C++, Java, and Scala. It is named after Reliable, Replicated, Redundant, And Fault-Tolerant. Raft is not a Byzantine fault tolerant algorithm: the nodes trust the elected leader.
  • 794
  • 31 Oct 2022
Topic Review
International Roughness Index
The International Roughness Index (IRI) is the roughness index most commonly obtained from measured longitudinal road profiles. It is calculated using a quarter-car vehicle math model, whose response is accumulated to yield a roughness index with units of slope (in/mi, m/km, etc.). This performance measure has less stochasticity and subjectivity in comparison to other pavement performance indicators, but it is not completely devoid of randomness. The sources of variability in IRI data include the difference among the readings of different runs of the test vehicle and the difference between the readings of the right and left wheel paths. Despite these facts, since its introduction in 1986, the IRI has become the road roughness index most commonly used worldwide for evaluating and managing road systems. The measurement of IRI is required for data provided to the United States Federal Highway Administration, and is covered in several standards from ASTM International: ASTM E1926 - 08, ASTM E1364 - 95(2005), and others. IRI is also used to evaluate new pavement construction, to determine penalties or bonus payments based on smoothness.
  • 4.3K
  • 31 Oct 2022
  • Page
  • of
  • 863

Other Entry Collections

>>