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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.

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McClintock Arctic Expedition
The McClintock Arctic Expedition of 1857 was a British effort to locate the last remains of the lost Franklin Arctic Expedition. Led by captain Francis Leopold McClintock aboard the steam yacht Fox, the expedition spent two years in the region and ultimately returned with the only written message from the doomed expedition. McClintock and crew were awarded the Arctic medal in recognition of their achievements.
  • 848
  • 09 Nov 2022
Topic Review
Fault-tolerant Computer System
Fault-tolerant computer systems are systems designed around the concepts of fault tolerance. In essence, they must be able to continue working to a level of satisfaction in the presence of errors or breakdowns. Fault tolerance is not just a property of individual machines; it may also characterise the rules by which they interact. For example, the Transmission Control Protocol (TCP) is designed to allow reliable two-way communication in a packet-switched network, even in the presence of communications links which are imperfect or overloaded. It does this by requiring the endpoints of the communication to expect packet loss, duplication, reordering and corruption, so that these conditions do not damage data integrity, and only reduce throughput by a proportional amount. Recovery from errors in fault-tolerant systems can be characterised as either 'roll-forward' or 'roll-back'. When the system detects that it has made an error, roll-forward recovery takes the system state at that time and corrects it, to be able to move forward. Roll-back recovery reverts the system state back to some earlier, correct version, for example using checkpointing, and moves forward from there. Roll-back recovery requires that the operations between the checkpoint and the detected erroneous state can be made idempotent. Some systems make use of both roll-forward and roll-back recovery for different errors or different parts of one error.
  • 2.3K
  • 09 Nov 2022
Topic Review
Discovery and Development of Non-nucleoside Reverse-transcriptase Inhibitors
Non-nucleoside reverse-transcriptase inhibitors (NNRTIs) are antiretroviral drugs used in the treatment of human immunodeficiency virus (HIV). NNRTIs inhibit reverse transcriptase (RT), an enzyme that controls the replication of the genetic material of HIV. RT is one of the most popular targets in the field of antiretroviral drug development. Discovery and development of NNRTIs began in the late 1980s and in the end of 2009 four NNRTI had been approved by regulatory authorities and several others were undergoing clinical development. Drug resistance develops quickly if NNRTIs are administered as monotherapy and therefore NNRTIs are always given as part of combination therapy, the highly active antiretroviral therapy (HAART).
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  • 09 Nov 2022
Topic Review
Massetognathus
Massetognathus (/ˌmæsɪˈtɒɡnəθəs/ MASS-ə-TOG-nə-thəss; Greek for "chewing muscle jaw") is an extinct genus of plant-eating traversodontid cynodonts. They lived during the Triassic Period about 235 million years ago, and are known from the Chañares Formation in Argentina and the Santa Maria Formation in Brazil.
  • 655
  • 09 Nov 2022
Topic Review
Ethology
Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objective study of animal behaviour, usually referring to measured responses to stimuli or to trained behavioural responses in a laboratory context, without a particular emphasis on evolutionary adaptivity. Throughout history, different naturalists have studied aspects of animal behaviour. Ethology has its scientific roots in the work of Charles Darwin and of American and German ornithologists of the late 19th and early 20th century, including Charles O. Whitman, Oskar Heinroth, and Wallace Craig. The modern discipline of ethology is generally considered to have begun during the 1930s with the work of Dutch biologist Nikolaas Tinbergen and Austrian biologists Konrad Lorenz and Karl von Frisch, the three recipients of the 1973 Nobel Prize in Physiology or Medicine. Ethology combines laboratory and field science, with a strong relation to some other disciplines such as neuroanatomy, ecology, and evolutionary biology. Ethologists typically show interest in a behavioural process rather than in a particular animal group, and often study one type of behaviour, such as aggression, in a number of unrelated species. Ethology is a rapidly growing field. Since the dawn of the 21st century researchers have re-examined and reached new conclusions in many aspects of animal communication, emotions, culture, learning and sexuality that the scientific community long thought it understood. New fields, such as neuroethology, have developed. Understanding ethology or animal behaviour can be important in animal training. Considering the natural behaviours of different species or breeds enables trainers to select the individuals best suited to perform the required task. It also enables trainers to encourage the performance of naturally occurring behaviours and the discontinuance of undesirable behaviours.
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  • 09 Nov 2022
Topic Review
Histopathology of Colorectal Carcinoma
The histopathology of colorectal carcinoma involves analysis of tissue taken from a biopsy or surgery. A pathology report contains a description of the microscopical characteristics of the tumor tissue, including both tumor cells and how the tumor invades into healthy tissues and finally if the tumor appears to be completely removed. The most common form of colon cancer is adenocarcinoma, constituting between 95% to 98% of all cases of colorectal cancer. Other, rarer types include lymphoma, adenosquamous and squamous cell carcinoma. Some subtypes have been found to be more aggressive.
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  • 09 Nov 2022
Topic Review
Radeon HD 4000 Series
The Radeon R700 is the engineering codename for a graphics processing unit series developed by Advanced Micro Devices under the ATI brand name. The foundation chip, codenamed RV770, was announced and demonstrated on June 16, 2008 as part of the FireStream 9250 and Cinema 2.0 initiative launch media event, with official release of the Radeon HD 4800 series on June 25, 2008. Other variants include enthusiast-oriented RV790, mainstream product RV730, RV740 and entry-level RV710. Its direct competition was nVidia's GeForce 200 series, which launched in the same month.
  • 2.2K
  • 09 Nov 2022
Topic Review
Euro Health Consumer Index
Euro Health Consumer Index (EHCI) is a comparison of European health care systems based on waiting times, results, and generosity. The information is presented as a graphic index. EHCI was produced 2005–2009 and 2012–2016 by Health Consumer Powerhouse. The 2014 ranking included 37 countries measured by 48 indicators. It claims to measure the "consumer friendliness" of healthcare systems. It does not claim to measure which European state has the best healthcare system, but it does produce specialist Indexes on Diabetes, Cardiac Care, HIV, Headache and Hepatitis. In 2006 France was the champion with 768 points out of 1000. In the 2015 results the same performance would have given the 13th position among 35 countries because of the widespread improvements in standards. While no bias in favour of any health system was alleged, the index was criticised in the British Medical Journal by Martin McKee and others from the European Observatory on Health Systems and Policies in February 2016. Points they made included: A survey by the Centre for Population Change in 2019 produced results consistent with the index.
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  • 09 Nov 2022
Topic Review
Homogenization (Climate)
Homogenization in climate research means the removal of non-climatic changes. Next to changes in the climate itself, raw climate records also contain non-climatic jumps and changes, for example due to relocations or changes in instrumentation. The most used principle to remove these inhomogeneities is the relative homogenization approach in which a candidate station is compared to a reference time series based on one or more neighboring stations. The candidate and reference station(s) experience about the same climate, non-climatic changes that happen only in one station can thus be identified and removed.
  • 618
  • 09 Nov 2022
Topic Review
Crossword
A crossword is a word puzzle and word search game that usually takes the form of a square or a rectangular grid of white- and black-shaded squares. The game's goal is to fill the white squares with letters, forming words or phrases, by solving clues, which lead to the answers. In languages that are written left-to-right, the answer words and phrases are placed in the grid from left to right and from top to bottom. The shaded squares are used to separate the words or phrases.
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  • 10 Nov 2022
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