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Biography

Krist Novoselic

Krist Anthony Novoselic (Croatian: Krist Novoselić; born May 16, 1965) is an American musician and political activist, and was the bassist and founding member of the grunge band Nirvana alongside guitarist and lead singer Kurt Cobain.[1][2] Nirvana achieved massive success, earning multiple gold and platinum awards and touring around the world at sold-out shows.[3] After Nirvana disbanded foll

13.2K
22 Nov 2022

Topic Review

Essential Trace Elements

Trace elements produce double-edged effects on the lives of animals and particularly of humans. On one hand, these elements represent potentially toxic agents; on the other hand, they are essentially needed to support growth and development and confer protection against disease. The amount taken up and the accumulation in human tissues decisively control whether the exerted effects are toxic or beneficial. This entry provides a brief description of some toxic, likely essential and essential elements and their influence on human health.

13.1K
20 Aug 2020

Topic Review

Tetrapods (/ˈtɛtrəˌpɒdz/; from grc τετρα- (tetra-) 'four', and πούς (poús) 'foot') are four-limbed vertebrate animals constituting the superclass Tetrapoda (/tɛˈtrɒpədə/). It includes extant and extinct amphibians, reptiles (including dinosaurs and therefore birds), and synapsids (including mammals). Tetrapods evolved from a group of animals known as the Tetrapodomorpha which, in turn, evolved from ancient lobe-finned (sarcopterygian) fish around 390 million years ago in the middle Devonian period; their forms were transitional between lobe-finned fishes and the four-limbed tetrapods. Limbed vertebrates (tetrapods in the broad sense of the word) are first known from Middle Devonian trackways, and body fossils became common near the end of the Late Devonian but these were all aquatic. The first crown-tetrapods (last common ancestors of extant tetrapods capable of terrestrial locomotion) appeared by the very early Carboniferous, 350 million years ago. The specific aquatic ancestors of the tetrapods and the process by which they colonized Earth's land after emerging from water remains unclear. The change from a body plan for breathing and navigating in water to a body plan enabling the animal to move on land is one of the most profound evolutionary changes known. Tetrapods have numerous anatomical and physiological features that are distinct from their aquatic ancestors. These include the structure of the head for feeding and breathing, limb girdles and digits for locomotion, eyes for seeing, ears for hearing, and the heart and lungs for gas circulation and exchange outside water. The first tetrapods (stem) or "fishapods" were primarily aquatic. Modern amphibians, which evolved from earlier groups, are generally semiaquatic; the first stage of their lives is as fish-like tadpoles, and later stages are partly terrestrial and partly aquatic. However, most tetrapod species today are amniotes, most of which are terrestrial tetrapods whose branch evolved from earlier tetrapods early in the Late Carboniferous. The key innovation in amniotes over amphibians is the amnion, which enables the eggs to retain their aqueous contents on land, rather than needing to stay in water. (Some amniotes later evolved internal fertilization, although many aquatic species outside the tetrapod tree had evolved such before the tetrapods appeared, e.g. Materpiscis.) Some tetrapods, such as snakes and caecilians, have lost some or all of their limbs through further speciation and evolution; some have only concealed vestigial bones as a remnant of the limbs of their distant ancestors. Others returned to being amphibious or otherwise living partially or fully aquatic lives, the first during the Carboniferous period, others as recently as the Cenozoic. One group of amniotes diverged into the reptiles, which includes lepidosaurs, dinosaurs (which includes birds), crocodilians, turtles, and extinct relatives; while another group of amniotes diverged into the mammals and their extinct relatives. Amniotes include the tetrapods that further evolved for flight—such as birds from among the dinosaurs, pterosaurs from the archosaurs, and bats from among the mammals.

12.8K
04 Nov 2022

Topic Review

Responses to Sneezing

In English-speaking countries, the common verbal response to another person's sneeze is "bless you", or, less commonly in the United States and Canada , "Gesundheit", the German word for health (and the response to sneezing in German-speaking countries). There are several proposed bless-you origins for use in the context of sneezing. In non-English-speaking cultures, words referencing good health or a long life are often used instead of "bless you," though some also use references to God. In some Asian cultures such as Korean and Japanese cultures, the practice of responding to another person's sneeze does not exist. In the Assyrian language, “Shemad Alaha”, “in God’s name”, is the response to a sneeze.

12.7K
01 Dec 2022

Topic Review

Intergeneric Hybrid

In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in blending inheritance), but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridisation, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo. Some act before fertilization and others after it. Similar barriers exist in plants, with differences in flowering times, pollen vectors, inhibition of pollen tube growth, somatoplastic sterility, cytoplasmic-genic male sterility and the structure of the chromosomes. A few animal species and many plant species, however, are the result of hybrid speciation, including important crop plants such as wheat, where the number of chromosomes has been doubled. Human impact on the environment has resulted in an increase in the interbreeding between regional species, and the proliferation of introduced species worldwide has also resulted in an increase in hybridisation. This genetic mixing may threaten many species with extinction, while genetic erosion from monoculture in crop plants may be damaging the gene pools of many species for future breeding. A form of often intentional human-mediated hybridisation is the crossing of wild and domesticated species. This is common in both traditional horticulture and modern agriculture; many commercially useful fruits, flowers, garden herbs, and trees have been produced by hybridisation. One such flower, Oenothera lamarckiana, was central to early genetics research into mutationism and polyploidy. It is also more occasionally done in the livestock and pet trades; some well-known wild × domestic hybrids are beefalo and wolfdogs. Human selective breeding of domesticated animals and plants has resulted in the development of distinct breeds (usually called cultivars in reference to plants); crossbreeds between them (without any wild stock) are sometimes also imprecisely referred to as "hybrids". Hybrid humans existed in prehistory. For example, Neanderthals and anatomically modern humans are thought to have interbred as recently as 40,000 years ago. Mythological hybrids appear in human culture in forms as diverse as the Minotaur, blends of animals, humans and mythical beasts such as centaurs and sphinxes, and the Nephilim of the Biblical apocrypha described as the wicked sons of fallen angels and attractive women.

12.3K
10 Oct 2022

Topic Review

The white tiger or bleached tiger is a pigmentation variant of the Bengal tiger, which is reported in the wild from time to time in the Indian states of Madhya Pradesh, Assam, West Bengal and Bihar in the Sunderbans region and especially in the former State of Rewa. Such a tiger has the black stripes typical of the Bengal tiger, but carries a white or near-white coat.

12.2K
19 Oct 2022

Biography

Masaru Emoto (江本勝, Emoto Masaru, July 22, 1943 – October 17, 2014)[1] was a Japanese businessman, author and pseudoscientist who claimed that human consciousness could affect the molecular structure of water. His 2004 book The Hidden Messages in Water was a New York Times best seller.[2] His conjecture evolved over the years, and his early work revolved around pseudoscientific hypothese

12.1K
30 Nov 2022

Biography

Katharine Burr Blodgett

Katharine Burr Blodgett (January 10, 1898 – October 12, 1979) was an American physicist and chemist known for her work on surface chemistry, in particular her invention of "invisible" or nonreflective glass while working at General Electric. She was the first woman to be awarded a Ph.D. in physics from the University of Cambridge, in 1926.[1] Blodgett was born on January 10, 1898 in Schenec

11.8K
18 Nov 2022

Biography

Eckhart Tolle (/ˈɛkɑːrt ˈtɒlə/ EK-art TOL-ə; German: [ˈɛkhaʁt ˈtɔlə]; born Ulrich Leonard Tölle, February 16, 1948) is a German spiritual teacher and self-help author best known as the author of The Power of Now and A New Earth: Awakening to Your Life's Purpose. After being recommended by Oprah Winfrey, his first book, The Power of Now,[1] reached The New York Times Best Seller l

11.7K
05 Dec 2022

Topic Review

Tyrannosaurus is a genus of large theropod dinosaur. The species Tyrannosaurus rex (rex meaning "king" in Latin), often called T. rex or colloquially T-Rex, is one of the best represented theropods. Tyrannosaurus lived throughout what is now western North America, on what was then an island continent known as Laramidia. Tyrannosaurus had a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the Upper Cretaceous period, 68 to 66 million years ago. It was the last known member of the tyrannosaurids and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event. Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to its large and powerful hind limbs, the forelimbs of Tyrannosaurus were short but unusually powerful for their size, and they had two clawed digits. The most complete specimen measures up to 12.3–12.4 m (40.4–40.7 ft) in length; however, according to most modern estimates, T. rex could grow to lengths of over 12.4 m (40.7 ft), up to 3.66–3.96 m (12–13 ft) tall at the hips, and 8.87 metric tons (9.78 short tons) in body mass. Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it is still among the largest known land predators and is estimated to have exerted the strongest bite force among all terrestrial animals. By far the largest carnivore in its environment, Tyrannosaurus rex was most likely an apex predator, preying upon hadrosaurs, juvenile armored herbivores like ceratopsians and ankylosaurs, and possibly sauropods. Some experts have suggested the dinosaur was primarily a scavenger. The question of whether Tyrannosaurus was an apex predator or a pure scavenger was among the longest debates in paleontology. Most paleontologists today accept that Tyrannosaurus was both an active predator and a scavenger. Specimens of Tyrannosaurus rex include some that are nearly complete skeletons. Soft tissue and proteins have been reported in at least one of these specimens. The abundance of fossil material has allowed significant research into many aspects of its biology, including its life history and biomechanics. The feeding habits, physiology, and potential speed of Tyrannosaurus rex are a few subjects of debate. Its taxonomy is also controversial, as some scientists consider Tarbosaurus bataar from Asia to be a second Tyrannosaurus species, while others maintain Tarbosaurus is a separate genus. Several other genera of North American tyrannosaurids have also been synonymized with Tyrannosaurus. As the archetypal theropod, Tyrannosaurus has been one of the best-known dinosaurs since the early 20th century and has been featured in film, advertising, postal stamps, and many other media.

11.7K
06 Dec 2022

Biography

Benjamin Aaron Shapiro (born January 15, 1984)[1] is an American conservative political commentator, public speaker, media executive, author, and attorney. At age 17, he became the youngest nationally syndicated columnist in the United States.[2][3][4] He writes columns for Creators Syndicate and Newsweek, serves as editor-in-chief for The Daily Wire, which he founded, and hosts The Ben Shapiro

11.5K
06 Dec 2022

Topic Review

An eyelash curler is a hand-operated mechanical device for curling eyelashes for cosmetic purposes. Usually only the upper eyelashes are curled.

11.5K
25 Nov 2022

Topic Review

A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally without tail in Ancient Greek). The oldest fossil "proto-frog" Triadobatrachus is known from the Early Triassic of Madagascar , but molecular clock dating suggests their split from other amphibians may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest. Frogs account for around 88% of extant amphibian species. They are also one of the five most diverse vertebrate orders. Warty frog species tend to be called toads, but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history. An adult frog has a stout body, protruding eyes, anteriorly-attached tongue, limbs folded underneath, and no tail (the tail of tailed frogs is an extension of the male cloaca). Frogs have glandular skin, with secretions ranging from distasteful to toxic. Their skin varies in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to show toxicity and ward off predators. Adult frogs live in fresh water and on dry land; some species are adapted for living underground or in trees. Frogs typically lay their eggs in water. The eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on plant matter. Frog skin has a rich microbiome which is important to their health. Frogs are extremely efficient at converting what they eat into body mass. They are an important food source for predators and part of the food web dynamics of many of the world's ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce a wide range of vocalizations, particularly in their breeding season, and exhibit many different kinds of complex behaviors to attract mates, to fend off predators and to generally survive. Frogs are valued as food by humans and also have many cultural roles in literature, symbolism and religion. They are also seen as environmental bellwethers, with declines in frog populations often viewed as early warning signs of environmental damage. Frog populations have declined significantly since the 1950s. More than one third of species are considered to be threatened with extinction and over 120 are believed to have become extinct since the 1980s. The number of malformations among frogs is on the rise and an emerging fungal disease, chytridiomycosis, has spread around the world. Conservation biologists are working to understand the causes of these problems and to resolve them.

11.2K
19 Oct 2022

Topic Review

Evolution of Elephants

Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are an informal grouping within the proboscidean family Elephantidae. Elephantidae is the only surviving family of proboscideans; extinct members include the mastodons. Elephantidae also contains several extinct groups, including the mammoths and straight-tusked elephants. African elephants have larger ears and concave backs, whereas Asian elephants have smaller ears, and convex or level backs. The distinctive features of all elephants include a long proboscis called a trunk, tusks, large ear flaps, massive legs, and tough but sensitive skin. The trunk is used for breathing, bringing food and water to the mouth, and grasping objects. Tusks, which are derived from the incisor teeth, serve both as weapons and as tools for moving objects and digging. The large ear flaps assist in maintaining a constant body temperature as well as in communication. The pillar-like legs carry their great weight. Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia and are found in different habitats, including savannahs, forests, deserts, and marshes. They are herbivorous, and they stay near water when it is accessible. They are considered to be keystone species, due to their impact on their environments. Elephants have a fission–fusion society, in which multiple family groups come together to socialise. Females (cows) tend to live in family groups, which can consist of one female with her calves or several related females with offspring. The groups, which do not include bulls, are usually led by the oldest cow, known as the matriarch. Males (bulls) leave their family groups when they reach puberty and may live alone or with other males. Adult bulls mostly interact with family groups when looking for a mate. They enter a state of increased testosterone and aggression known as musth, which helps them gain dominance over other males as well as reproductive success. Calves are the centre of attention in their family groups and rely on their mothers for as long as three years. Elephants can live up to 70 years in the wild. They communicate by touch, sight, smell, and sound; elephants use infrasound, and seismic communication over long distances. Elephant intelligence has been compared with that of primates and cetaceans. They appear to have self-awareness, and appear to show empathy for dying and dead family members. African bush elephants and Asian elephants are listed as endangered and African forest elephants as critically endangered by the International Union for Conservation of Nature (IUCN). One of the biggest threats to elephant populations is the ivory trade, as the animals are poached for their ivory tusks. Other threats to wild elephants include habitat destruction and conflicts with local people. Elephants are used as working animals in Asia. In the past, they were used in war; today, they are often controversially put on display in zoos, or exploited for entertainment in circuses. Elephants are highly recognisable and have been featured in art, folklore, religion, literature, and popular culture.

11.0K
28 Nov 2022

Topic Review

Red algae, or Rhodophyta (/roʊˈdɒfɪtə/, /ˌroʊdəˈfaɪtə/; from grc ῥόδον (rhódon) 'rose', and φυτόν (phutón) 'plant'), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority of species (6,793) are found in the Florideophyceae (class), and mostly consist of multicellular, marine algae, including many notable seaweeds. Red algae are abundant in marine habitats but relatively rare in freshwaters. Approximately 5% of red algae species occur in freshwater, environments with greater concentrations found in warmer areas. Except for two coastal cave dwelling species in the asexual class Cyanidiophyceae, there are no terrestrial species, which may be due to an evolutionary bottleneck in which the last common ancestor lost about 25% of its core genes and much of its evolutionary plasticity. The red algae form a distinct group characterized by having eukaryotic cells without flagella and centrioles, chloroplasts that lack external endoplasmic reticulum and contain unstacked (stroma) thylakoids, and use phycobiliproteins as accessory pigments, which give them their red color. Red algae store sugars as floridean starch, which is a type of starch that consists of highly branched amylopectin without amylose, as food reserves outside their plastids. Most red algae are also multicellular, macroscopic, marine, and reproduce sexually. The red algal life history is typically an alternation of generations that may have three generations rather than two. The coralline algae, which secrete calcium carbonate and play a major role in building coral reefs, belong here. Red algae such as dulse (Palmaria palmata) and laver (nori/gim) are a traditional part of European and Asian cuisines and are used to make other products such as agar, carrageenans and other food additives.

11.0K
11 Nov 2022

Topic Review

Context-Dependent Memory

In psychology, context-dependent memory is the improved recall of specific episodes or information when the context present at encoding and retrieval are the same. In a simpler manner, "when events are represented in memory, contextual information is stored along with memory targets; the context can therefore cue memories containing that contextual information". One particularly common example of context-dependence at work occurs when an individual has lost an item (e.g. lost car keys) in an unknown location. Typically, people try to systematically "retrace their steps" to determine all of the possible places where the item might be located. Based on the role that context plays in determining recall, it is not at all surprising that individuals often quite easily discover the lost item upon returning to the correct context. This concept is heavily related to the encoding specificity principle. This example best describes the concept of context-dependent forgetting. However, the research literature on context-dependent memory describes a number of different types of contextual information that may affect recall such as environmental context-dependent memory, state-dependent learning, cognitive context-dependent memory and mood-congruent memory. Research has also shown that context-dependence may play an important role in numerous situations, such as memory for studied material, or events that have occurred following the consumption of alcohol or other drugs.

10.6K
03 Nov 2022

Biography

Theodor Schwann

Theodor Schwann ([1][2] 7 December 1810 – 11 January 1882) was a Germany physician and physiologist.[3] His most significant contribution to biology is considered to be the extension of cell theory to animals. Other contributions include the discovery of Schwann cells in the peripheral nervous system, the discovery and study of pepsin, the discovery of the organic nature of yeast,[4] and the i

10.6K
18 Nov 2022

Topic Review

The Pinophyta, also known as Coniferophyta or Coniferae, or commonly as conifers, are a division of vascular land plants containing a single extant class, Pinopsida. They are gymnosperms, cone-bearing seed plants. All extant conifers are perennial woody plants with secondary growth. The great majority are trees, though a few are shrubs. Examples include cedars, Douglas firs, cypresses, firs, junipers, kauri, larches, pines, hemlocks, redwoods, spruces, and yews. As of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, and 629 living species. Although the total number of species is relatively small, conifers are ecologically important. They are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, but also in similar cool climates in mountains further south. Boreal conifers have many wintertime adaptations. The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow. Many of them seasonally alter their biochemistry to make them more resistant to freezing. While tropical rainforests have more biodiversity and turnover, the immense conifer forests of the world represent the largest terrestrial carbon sink. Conifers are of great economic value for softwood lumber and paper production.

10.5K
21 Oct 2022

Topic Review

Travis (Chimpanzee)

Travis (October 21, 1995 – February 16, 2009) was a male common chimpanzee (Pan troglodytes) who, in February 2009, mauled his owner's friend in Stamford, Connecticut. He blinded her, severed several body parts and lacerated her face. He was shot dead by a police officer. As an animal actor, Travis had appeared in several television shows and commercials, including spots for Pepsi and Old Navy. He had also appeared on The Maury Povich Show, The Man Show, and a television pilot that featured Sheryl Crow and Michael Moore.

10.3K
07 Nov 2022

Topic Review

Dunkleosteus is an extinct genus of large armored, jawed fishes that existed during the Late Devonian period, about 382–358 million years ago. It consists of ten species, some of which are among the largest placoderms to have ever lived: D. terrelli, D. belgicus, D. denisoni, D. marsaisi, D. magnificus, D. missouriensis, D. newberryi, D. amblyodoratus, and D. raveri. The largest and most well known species is D. terrelli, which grew up to 8.79 m (28.8 ft) long and 4 t (4.4 short tons) in weight. Dunkleosteus could quickly open and close its jaw, like modern-day suction feeders, and had a bite force of 6,000 N (612 kgf; 1,349 lbf) at the tip and 7,400 N (755 kgf; 1,664 lbf) at the blade edge. Numerous fossils of the various species have been found in North America, Poland , Belgium, and Morocco.

10.1K
16 Nov 2022

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