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Biography

Walter Heinrich Heitler (German: [ˈhaɪtlɐ]; 2 January 1904 – 15 November 1981) was a German physicist who made contributions to quantum electrodynamics and quantum field theory. He brought chemistry under quantum mechanics through his theory of valence bonding. In 1922, Heitler began his study of physics at the Karlsruhe Technische Hochschule, in 1923 at the Humboldt University of Berlin

2.8K
07 Dec 2022

Topic Review

Bradykinin (BK) (Greek brady-, slow; -kinin, kīn(eîn) to move) is a peptide that promotes inflammation. It causes arterioles to dilate (enlarge) via the release of prostacyclin, nitric oxide, and endothelium-derived hyperpolarizing factor and makes veins constrict, via prostaglandin F2, thereby leading to leakage into capillary beds, due to the increased pressure in the capillaries. Bradykinin is a physiologically and pharmacologically active peptide of the kinin group of proteins, consisting of nine amino acids. A class of drugs called angiotensin converting enzyme inhibitors (ACE inhibitors) increase bradykinin levels by inhibiting its degradation, thereby increasing its blood pressure lowering effect. ACE inhibitors are FDA approved for the treatment of hypertension and heart failure.

2.7K
04 Nov 2022

Biography

Gennady Zyuganov

Gennady Andreyevich Zyuganov (Russian: Генна́дий Андре́евич Зюга́нов; born 26 June 1944) is a Russia n communist politician who has been the leader of the Communist Party of the Russian Federation since 1993. He has been Chairman of the Union of Communist Parties - Communist Party of the Soviet Union (UCP-CPSU) since 2001, a deputy in the State Duma since 1993, and a m

2.7K
28 Nov 2022

Topic Review

Hoverflies, also called flower flies or syrphid flies, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae (maggots) eat a wide range of foods. In some species, the larvae are saprotrophs, eating decaying plant and animal matter in the soil or in ponds and streams. In other species, the larvae are insectivores and prey on aphids, thrips, and other plant-sucking insects. Insects such as aphids are considered a crop pest, and therefore the aphid-eating larvae of some hover flies serve as an economically (as well as ecologically) important predator and even potential agents for use in biological control, while the adults may be pollinators. About 6,000 species in 200 genera have been described. Hoverflies are common throughout the world and can be found on all continents except Antarctica. Hoverflies are harmless to most mammals, though many species are mimics of stinging wasps and bees, a mimicry which may serve to ward off predators.

2.7K
16 Nov 2022

Topic Review

Captive White Tigers

Captive white tigers are of little known lineage. They are held captive around the world, usually for financial purposes. The Tiger Species Survival Plan devised by the Association of Zoos and Aquariums has condemned the breeding of white tigers. The genes responsible for white colour are represented by 0.001% of the tiger population. However, in 2008–2009, a closing stock of 264 Bengal tigers and 100 white Bengal tigers were accounted for in Indian zoos. The disproportionate growth in numbers of the latter points to the relentless inbreeding resorted to among homozygous recessive individuals for selectively multiplying the white animals. This progressively increasing process will eventually lead to inbreeding depression and loss of genetic variability.

2.7K
01 Nov 2022

Topic Review

A peach is a soft, juicy and fleshy stone fruit produced by a peach tree.

2.7K
27 Oct 2022

Biography

August Beer (German: [beːɐ̯]; 31 July 1825 – 18 November 1863) was a Germany physicist, chemist, and mathematician of Jewish descent.[1] Beer was born in Trier, where he studied mathematics and natural sciences. Beer was educated at the technical school and gymnasium of his native town until 1845, when he went to Bonn to study mathematics and the sciences under the mathematician and phys

2.7K
15 Dec 2022

Topic Review

UK Biobank is a large long-term biobank study in the United Kingdom (UK) which is investigating the respective contributions of genetic predisposition and environmental exposure (including nutrition, lifestyle, medications etc.) to the development of disease. It began in 2006. Based in Stockport, Greater Manchester, it is incorporated as a limited company and registered charity in England and Wales, and registered as a charity in Scotland.

2.7K
10 Oct 2022

Topic Review

Tarantulas comprise a group of large and often hairy spiders of the family Theraphosidae. Currently, 1,010 species have been identified. The term "tarantula" is usually used to describe members of the family Theraphosidae, although many other members of the same infraorder (Mygalomorphae) are commonly referred to as "tarantulas" or "false tarantulas". Some of the more common species have become popular in the exotic pet trade. Many New World species kept as pets have setae known as urticating hairs that can cause irritation to the skin, and in extreme cases, cause damage to the eyes.

2.7K
28 Oct 2022

Biography

Jakob von Uexküll

Jakob Johann Baron von Uexküll (German: [ˈʏkskʏl]; 8 September 1864 – 25 July 1944) was a Baltic German biologist who worked in the fields of muscular physiology, animal behaviour studies, and the cybernetics of life. However, his most notable contribution is the notion of Umwelt, used by semiotician Thomas Sebeok and philosopher Martin Heidegger. His works established biosemiotics [1] as

2.7K
08 Dec 2022

Topic Review

Solidago, commonly called goldenrods, is a genus of about 100 to 120 species of flowering plants in the aster family, Asteraceae. Most are herbaceous perennial species found in open areas such as meadows, prairies, and savannas. They are mostly native to North America, including Mexico; a few species are native to South America and Eurasia. Some American species have also been introduced into Europe and other parts of the world.

2.7K
06 Nov 2022

Topic Review

Swine Influenza

Swine influenza is an infection caused by any of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) refers to any strain of the influenza family of viruses that is endemic in pigs. As of 2009, identified SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H2N1, H3N1, H3N2, and H2N3. Swine influenza virus is common throughout pig populations worldwide. Transmission of the virus from pigs to humans is rare, and does not always lead to human flu, often resulting only in the production of antibodies in the blood. If transmission causes human flu, it is called zoonotic swine flu. People with regular exposure to pigs are at increased risk of swine flu infections. Around the mid-20th century, identification of influenza subtypes was made possible, allowing accurate diagnosis of transmission to humans. Since then, only 50 such transmissions have been confirmed. These strains of swine flu rarely pass from human to human. Symptoms of zoonotic swine flu in humans are similar to those of influenza and of influenza-like illness in general, namely chills, fever, sore throat, muscle pains, severe headache, coughing, weakness, shortness of breath, and general discomfort. It is estimated that, in the 2009 flu pandemic, 11–21% of the then global population (of about 6.8 billion), equivalent to around 700 million to 1.4 billion people, contracted the illness—more, in absolute terms, than the Spanish flu pandemic. There were 18,449 confirmed fatalities. However, in a 2012 study, the CDC estimated more than 284,000 possible fatalities worldwide, with numbers ranging from 150,000 to 575,000. In August 2010, the World Health Organization declared the swine flu pandemic officially over. Subsequent cases of swine flu were reported in India in 2015, with over 31,156 positive test cases and 1,841 deaths.

2.7K
21 Nov 2022

Biography

Nicolas-Théodore de Saussure

Nicolas-Théodore de Saussure (14 October 1767, in Geneva – 18 April 1845, in Geneva [1]) was a Switzerland chemist and student of plant physiology who made seminal advances in phytochemistry. He is one of the major pioneers in the study of photosynthesis.[2] Nicolas-Théodore de Saussure was born into a wealthy, aristocratic, Genevan family, many of whose members were accomplished in the n

2.7K
15 Nov 2022

Biography

Ralph Waldo Trine

Ralph Waldo Trine (October 26, 1866 – November 8, 1958) was an American philosopher, author, and teacher. He wrote many books on the New Thought movement. Trine was a close friend of Henry Ford and had several conversations with him about success in life. Born September 9, 1866,[1] in Mount Morris, Illinois,[2] Trine was the son of Samuel G. Trine and Ellen E. Newcomer.[3] He attended publi

2.7K
30 Nov 2022

Topic Review

The queen snake (Regina septemvittata) is a species of nonvenomous semiaquatic snake, a member of the subfamily Natricinae of the family Colubridae. The species is endemic to North America.

2.7K
24 Oct 2022

Biography

Paul Winchell (né Wilchinsky; December 21, 1922 – June 24, 2005) was an American ventriloquist, comedian, actor, voice artist, humanitarian, and inventor whose career flourished in the 1950s and 1960s. From 1950 to 1954, he hosted The Paul Winchell Show, which also used two other titles during its prime time run on NBC: The Speidel Show, and What's My Name?. From 1965–1968, Winchell hosted

2.7K
23 Nov 2022

Topic Review

Melanin (/ˈmɛlənɪn/ (listen); from Greek: μέλας, romanized: melas, lit. 'black, dark') is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization. The melanin pigments are produced in a specialized group of cells known as melanocytes. Functionally, eumelanin serves as protection against UV radiation. Melanin (neuromelanin) functions as the catalyst of all cellular functions within an organism. There are five basic types of melanin: eumelanin, pheomelanin, neuromelanin, allomelanin and pyomelanin. The most common type is eumelanin, of which there are two types— brown eumelanin and black eumelanin. Pheomelanin, which is produced when melanocytes are malfunctioning due to derivation of the gene to its recessive format is a cysteine-derivative that contains polybenzothiazine portions that are largely responsible for the of red yellow tint given to some skin or hair colors. Neuromelanin is found in the brain. Research has been undertaken to investigate its efficacy in treating neurodegenerative disorders such as Parkinson's. Allomelanin and pyomelanin are two types of nitrogen-free melanin. In the human skin, melanogenesis is initiated by exposure to UV radiation, causing the skin to darken. Eumelanin is an effective absorbent of light; the pigment is able to dissipate over 99.9% of absorbed UV radiation. Because of this property, eumelanin is thought to protect skin cells from UVA and UVB radiation damage, reducing the risk of folate depletion and dermal degradation. It is considered that exposure to UV radiation is associated with increased risk of malignant melanoma, a cancer of melanocytes (melanin cells). Studies have shown a lower incidence for skin cancer in individuals with more concentrated melanin, i.e. darker skin tone.

2.7K
28 Sep 2022

Topic Review

The feline tribe Acinonychini contains three genera, each with one extant species: the cougar in Puma, the jaguarundi in Herpailurus, and the cheetah in Acinonyx. In addition, a handful of extinct fossil species have been found in Eurasia and the Americas. The evolutionary relationships of these cats still needs to be worked out, with the main focus being the placement of the extinct species in relation to the extant species, and where cheetahs evolved. While cheetahs and cougars are sometimes considered big cats, as felines, they are more closely related to domestic cats than they are to pantherines such as lions and leopards.

2.6K
10 Nov 2022

Topic Review

The ferret (Mustela furo) is a domestic species of small mustelid. The only domesticated species in Mustelidae, it is thought to be a descendant of the European polecat, a mammal belonging to the same genus as the weasel, Mustela. Their fur is typically brown, black, white, or mixed. They have an average length of 51 cm (20 in), including a 13 cm (5.1 in) tail, weigh about between 0.7 and 2.0 kg (1.5 and 4.4 lb), and have a natural lifespan of 7 to 10 years. Ferrets are sexually dimorphic predators, with males being substantially larger than females. The history of the ferret's domestication is uncertain, like that of most other domestic animals, but it is likely that they have been domesticated for at least 2,500 years. They are still used for hunting rabbits in some parts of the world, but increasingly they are kept only as pets. Being so closely related to polecats, ferrets easily hybridize with them, and this has occasionally resulted in feral colonies of polecat–ferret hybrids that have caused damage to native fauna, especially in New Zealand. As a result, New Zealand and some other parts of the world have imposed restrictions on the keeping of ferrets. Several other mustelids are also known as ferrets, such as the black-footed ferret, an endangered species native to North America.

2.6K
21 Oct 2022

Topic Review

Lists of Elm Trees

Many elm (Ulmus) trees of various kinds have attained great size or otherwise become particularly noteworthy; among these are the following.

2.6K
30 Nov 2022

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