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
Osmium-172
Osmium (76Os) has seven naturally occurring isotopes, five of which are stable: 187Os, 188Os, 189Os, 190Os, and (most abundant) 192Os. The other natural isotopes, 184Os, and 186Os, have extremely long half-life (1.12×1013 years and 2×1015 years, respectively) and for practical purposes can be considered to be stable as well. 187Os is the daughter of 187Re (half-life 4.56×1010 years) and is most often measured in an 187Os/188Os ratio. This ratio, as well as the 187Re/188Os ratio, have been used extensively in dating terrestrial as well as meteoric rocks. It has also been used to measure the intensity of continental weathering over geologic time and to fix minimum ages for stabilization of the mantle roots of continental cratons. However, the most notable application of Os in dating has been in conjunction with iridium, to analyze the layer of shocked quartz along the Cretaceous–Paleogene boundary that marks the extinction of the dinosaurs 66 million years ago. There are also 30 artificial radioisotopes, the longest-lived of which is 194Os with a half-life of six years; all others have half-lives under 94 days. There are also nine known nuclear isomers, the longest-lived of which is 191mOs with a half-life of 13.10 hours. All isotopes and nuclear isomers of osmium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.
  • 705
  • 19 Oct 2022
Topic Review
Ford Maverick (1970)
The Ford Maverick is a compact car manufactured and marketed by Ford for model years 1970–1977 in the United States, originally as a two-door sedan employing a rear-wheel drive platform original to the 1960 Falcon — and subsequently as a four-door sedan on the same platform. The Maverick was also manufactured in Venezuela, Canada, Mexico, and from 1970 to 1979, in Brazil. The name "maverick" was derived from the word for unbranded range animals, and the car's nameplate was stylized to resemble the head of Longhorn cattle.
  • 2.3K
  • 19 Oct 2022
Topic Review
WebSphere Commerce
IBM WebSphere Commerce also known as WCS (WebSphere Commerce Suite) is a software platform framework for e-commerce, including marketing, sales, customer and order processing functionality in a tailorable, integrated package. It is a single, unified platform which offers the ability to do business directly with consumers (B2C), with businesses (B2B), indirectly through channel partners (indirect business models), or all of these simultaneously. WebSphere Commerce is a customizable, scalable and high availability solution built on the Java - Java EE platform using open standards, such as XML, and Web services. IBM WebSphere Commerce is sometimes referred to as WCS, however this abbreviation was originally used as a reference to the platform when it was named WebSphere Commerce Suite. Use of the abbreviation continued with users and solution implementers after the platform was renamed to WebSphere Commerce with the announcement of WebSphere Commerce V5.4.
  • 2.2K
  • 19 Oct 2022
Topic Review
Merchants of Doubt
Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming is a 2010 non-fiction book by American historians of science Naomi Oreskes and Erik M. Conway. It identifies parallels between the global warming controversy and earlier controversies over tobacco smoking, acid rain, DDT, and the hole in the ozone layer. Oreskes and Conway write that in each case "keeping the controversy alive" by spreading doubt and confusion after a scientific consensus had been reached was the basic strategy of those opposing action. In particular, they show that Fred Seitz, Fred Singer, and a few other contrarian scientists joined forces with conservative think tanks and private corporations to challenge the scientific consensus on many contemporary issues. Some of the book's subjects have been critical of the book, but most reviewers received it favorably. One reviewer said that Merchants of Doubt is exhaustively researched and documented, and may be one of the most important books of 2010. Another reviewer saw the book as his choice for best science book of the year. It was made into a film, Merchants of Doubt, directed by Robert Kenner, released in 2014.
  • 1.7K
  • 19 Oct 2022
Topic Review
Mercedes-Benz W108
The Mercedes-Benz W108 and W109 are luxury cars produced by Mercedes-Benz from 1965 through to 1972 and 1973 in North America only. The line was an update of the predecessor W111 and W112 fintail sedans. The cars were successful in West Germany and in export markets including North America and Southeast Asia. During the seven-year run, a total of 383,361 units were manufactured.
  • 8.4K
  • 19 Oct 2022
Topic Review
Sea Urchin
Sea urchins (/ˈɜːrtʃɪnz/) are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone — from the intertidal seashore down to 5,000 metres (16,000 ft; 2,700 fathoms). The spherical, hard shells (tests) of sea urchins are round and spiny, ranging in diameter from 3 to 10 cm (1 to 4 in). Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines. Although algae are the primary diet, sea urchins also eat slow-moving (sessile) animals. In the food chain, the predators who eat sea urchins are the sea otter and the starfish, the wolf eel, the triggerfish, and human beings. Adult sea urchins have fivefold symmetry, but their pluteus larvae feature bilateral (mirror) symmetry, indicating that the sea urchin belongs to the Bilateria group of animal phyla, which also comprises the chordates and the arthropods, the annelids and the molluscs, and are found in every ocean and in every climate, from the tropics to the polar regions, and inhabit marine benthic (sea bed) habitats, from rocky shores to hadal zone depths. The fossil record of the Echinoids dates from the Ordovician period, some 450 million years ago; the closest echinoderm relatives of the sea urchin are the sea cucumbers (Holothuroidea); both are deuterostomes, a clade that includes the chordates. The animals have been studied since the 19th century as model organisms in developmental biology, as their embryos were easy to observe; this has continued with studies of their genomes because of their unusual fivefold symmetry and relationship to chordates. Species such as the slate pencil urchin are popular in aquariums, where they are useful for controlling algae. Fossil urchins have been used as protective amulets.
  • 6.7K
  • 19 Oct 2022
Topic Review
Mushroom Poisoning
Mushroom poisoning is poisoning resulting from the ingestion of mushrooms that contain toxic substances. Its symptoms can vary from slight gastrointestinal discomfort to death in about 10 days. Mushroom toxins are secondary metabolites produced by the fungus. Mushroom poisoning is usually the result of ingestion of wild mushrooms after misidentification of a toxic mushroom as an edible species. The most common reason for this misidentification is a close resemblance in terms of color and general morphology of the toxic mushrooms species with edible species. To prevent mushroom poisoning, mushroom gatherers familiarize themselves with the mushrooms they intend to collect, as well as with any similar-looking toxic species. The safety of eating wild mushrooms may depend on methods of preparation for cooking.
  • 3.0K
  • 19 Oct 2022
Topic Review
Non-Helical Models of DNA Structure
In the history of molecular biology, non-helical or "side-by-side" models of DNA were proposed in the 1970s as a challenge to the standard double-helical model. The non-helical models attempted to solve problems relating to the topology of circular DNA chromosomes during replication. These theories were briefly considered seriously as a minority viewpoint, but they were later largely rejected due to X-ray crystallography of DNA duplexes and later the nucleosome core particle, as well as the discovery of topoisomerases, and these non-double-helical models are not currently accepted by the mainstream scientific community.
  • 1.8K
  • 12 May 2023
Topic Review
Sex Ratio
The sex ratio is the ratio of males to females in a population. In most sexually reproducing species, the ratio tends to be 1:1. This tendency is explained by Fisher's principle. For various reasons, however, many species deviate from anything like an even sex ratio, either periodically or permanently. Examples include parthenogenic species, periodically mating organisms such as aphids, some eusocial wasps such as Polistes fuscatus and Polistes exclamans, bees, ants, and termites. The human sex ratio is of particular interest to anthropologists and demographers. In human societies, however, sex ratios at birth may be considerably skewed by factors such as the age of mother at birth, and by sex-selective abortion and infanticide. Exposure to pesticides and other environmental contaminants may be a significant contributing factor as well. As of 2014, the global sex ratio at birth is estimated at 107 boys to 100 girls (1,000 boys per 934 girls).
  • 6.4K
  • 19 Oct 2022
Topic Review
Forscene
Forscene is an integrated internet video platform, video editing software, covering non linear editing and publishing for broadcast, web and mobile. Designed by Forbidden Technologies plc to allow collaborative editing of video, it is capable of video logging, reviewing, publishing and hosting to HD quality. The system is implemented as a mobile app for Android and IOS devices and as a web application with a Java applet as part of its user interface. The latter runs on platforms without application installation, codec installation, or machine configuration and has Web 2.0 features. Forscene won the Royal Television Society's award for Technology in the post-production process in December 2005, and is now used internationally. The underlying compression technology and the user interface are covered by separate patents.
  • 2.5K
  • 19 Oct 2022
  • Page
  • of
  • 863

Other Entry Collections

>>