SUMMARY / RELATED TOPICS

Vitamin

A vitamin is an organic molecule, an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, therefore must be obtained through the diet. Vitamin C can be synthesized by some species but not by others; the term vitamin does not include the three other groups of essential nutrients: minerals, essential fatty acids, essential amino acids. Most vitamins are not single molecules. For example, vitamin E consists of four tocotrienols; the thirteen vitamins required by human metabolism are vitamin A, vitamin B1, vitamin B2, vitamin B3, vitamin B5, vitamin B6, vitamin B7, vitamin B9, vitamin B12, vitamin C, vitamin D, vitamin E, vitamin K. Vitamins have diverse biochemical functions. Vitamin A acts as a regulator of tissue growth and differentiation. Vitamin D provides a hormone-like function, regulating mineral metabolism for bones and other organs.

The B complex vitamins the precursors for them. Vitamins C and E function as antioxidants. Both deficient and excess intake of a vitamin can cause clinically significant illness, although excess intake of water-soluble vitamins is less to do so. Before 1935, the only source of vitamins was from food. If intake of vitamins was lacking, the result was vitamin deficiency and consequent deficiency diseases. Commercially produced tablets of yeast-extract vitamin B complex and semi-synthetic vitamin C became available; this was followed in the 1950s by the mass production and marketing of vitamin supplements, including multivitamins, to prevent vitamin deficiencies in the general population. Governments mandated addition of vitamins to staple foods such as flour or milk, referred to as food fortification, to prevent deficiencies. Recommendations for folic acid supplementation during pregnancy reduced risk of infant neural tube defects. Although reducing incidence of vitamin deficiencies has benefits, supplementation is thought to be of little value for healthy people who are consuming a vitamin-adequate diet.

The term vitamin is derived from the word vitamine, coined in 1912 by Polish biochemist Casimir Funk, who isolated a complex of micronutrients essential to life, all of which he presumed to be amines. When this presumption was determined not to be true, the "e" was dropped from the name. All vitamins were discovered between 1913 and 1948. Vitamins are classified as either fat-soluble. In humans there are 13 vitamins: 9 water-soluble. Water-soluble vitamins dissolve in water and, in general, are excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption; because they are not as stored, more consistent intake is important. Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids. Vitamins A and D can accumulate in the body. Fat-soluble vitamin deficiency due to malabsorption is of particular significance in cystic fibrosis. Anti-vitamins are chemical compounds. For example, avidin is a protein in raw egg whites. Pyrithiamine, a synthetic compound, has a molecular structure similar to thiamine, vitamin B1, inhibits the enzymes that use thiamine.

Each vitamin is used in multiple reactions, therefore most have multiple functions. Vitamins are essential for the normal development of a multicellular organism. Using the genetic blueprint inherited from its parents, a fetus develops from the nutrients it absorbs, it requires certain minerals to be present at certain times. These nutrients facilitate the chemical reactions that produce among other things, skin and muscle. If there is serious deficiency in one or more of these nutrients, a child may develop a deficiency disease. Minor deficiencies may cause permanent damage. Once growth and development are completed, vitamins remain essential nutrients for the healthy maintenance of the cells and organs that make up a multicellular organism. For the most part, vitamins are obtained from the diet, but some are acquired by other means: for example, microorganisms in the gut flora produce vitamin K and biotin. Humans can produce some vitamins from precursors they consume: for example, vitamin A is synthesized from beta carotene.

The Food Fortification Initiative lists countries which have mandatory fortification programs for vitamins folic acid, vitamin A and vitamins B1, B2 and B12. The body's stores for different vitamins vary widely.

Piano Concerto No. 2 (MacDowell)

The Piano Concerto No. 2 in D minor, Op. 23 by Edward MacDowell was completed in late 1885. Although some obvious similarities with Edvard Grieg's, Camille Saint-Saëns's and Franz Liszt's concertos have been stated, MacDowell’s composition proves to be quite original, at least compared to his First Concerto, it was the first major piano concerto written by an American. It was the only large-scale composition by MacDowell to remain in standard repertoire. Macdowell's First Concerto was written and performed in 1882, when he was only 22, it was published in 1884. The composer soon began working on his Second. Finished in Wiesbaden in late 1885, for some years it remained unperformed. In 1888 MacDowell returned to America. On March 5, 1889 he performed the new concerto in Chickering Hall with New York Philharmonic under Theodore Thomas; the program of this concert included the American premiere of Tchaikovsky's Symphony No. 5. Next year Härtel published the orchestral score and an arrangement for 2 pianos.

It was dedicated to Teresa Carreño, a famous pianist, who used to be one of MacDowell's earliest piano teachers. The first recording of this concerto was made by Jesús Maria Sanromá in 1934 with Boston Pops Orchestra under Arthur Fiedler. Van Cliburn chose this concerto for his professional debut; the work is scored for solo piano, 2 flutes, 2 oboes, 2 clarinets, 2 bassoons, 4 horns, 2 trumpets, 3 trombones and strings. The concerto consists of all in sonata form; however the first movement is slow and the second is a lively scherzo. Principal theme of the first movement reappears in the third. A typical performance lasts 25 -- 28 minutes; the first movement opens with a lilting Wagnerian, introduction played by orchestra. A stentorian cadenza follows, after a short reprise of the introduction the proper sonata form begins; the theme of the cadenza is incorporated in the first subject, while the introductory one is transformed into the second. The development section is interrupted by the reappearing of the initial cadenza, much more elaborated.

After this music proceeds to the recapitulation. Soon states orchestral tutti the main theme, after which the cadenza is heard for the last time, it ends in a gloomy mood. The orchestra repeats sounding like a funeral march; the soloist soon changes the key to D major, which becomes the key of the second subject. The movement ends peacefully with a brief coda; the tone of the scherzo has much in common with the final of MacDowell's First Concerto. According to the composer, it was inspired by Ellen Terry's portrayal of Beatrice in Much Ado About Nothing. There first subject here is a perpetual motion theme, it sounds somewhat folk-like when played for the second time. Comes a more lyrical second theme in E-flat minor, which after a shortened version of the first subject is repeated in B-flat minor. A new, full reprise of the scherzo theme leads to a coda; the finale is the most complicated movement. It begins again with a dark introduction recalling the main theme of the first movement; the piano cadenza manage to reappear.

This section is in D minor. Its main theme gives place soon to a second idea, rhythmically skittish. Nor statement of this requires long time, a new valse-like theme is presented in the brass, derived from the principle theme of the first movement. After some 30 bars it ends abruptly with piano stating the cadenza theme; the recapitulation of the first theme entrancingly imitates musical snuff-box. Different reminiscences upon the valse theme follow before the skittish melody returns, it is followed by the final section of the first theme and the coda providing a most brilliant conclusion. Jesús Maria Sanromá with Boston Pops Orchestra, Arthur Fiedler Alexander Jenner with Vienna State Opera Orchestra, Henry Swoboda - Jesús Maria Sanromá with Eastman-Rochester Symphony Orchestra, Howard Hanson - - a digitized version available from Naxos Records 9.80570 Vivian Rivkin with Vienna State Opera Orchestra, Dean Dixon - - reissued on MCA Records MCAD2-9842, disc 1 Van Cliburn with Chicago Symphony Orchestra, Walter Hendl - reissued on RCA GD60420 Eugene List with Vienna State Opera Orchestra, Carlos Chávez - His Master's Voice CLP 1710 - reissued on Millennium Classics MCD80086 Earl Wild with RCA Victor Symphony Orchestra, Massimo Freccia - - reissued on Chesky CD76A Marjorie Mitchell with American Arts Orchestra, William Strickland - Vanguard Records - reissued on Vanguard Roberto Szidon with London Philharmonic Orchestra, Edward Downes - Deutsche Grammophon 2530 055 Eugene List with Westphalian Symphony Orchestra Siegfried Landau - Donna Amato with London Philharmonic Orchestra, Paul Freeman - Archduke Records, reissued on Olympia Records OCD 353, reissued on ALTO ALC1012 Claudette Sorel with New York Philharmonic, Franco Autori - - reissued on Emsco Productions 8156 Thomas Tirino with Bulgarian Radio Symphony O

Scinax squalirostris

Scinax squalirostris is a species of frog in the family Hylidae. It is found in southeastern and central Brazil, northeastern Argentina, southern Paraguay, Bolivia; the nominal species might represent more than one species. Common names striped long-snouted treefrog have been coined for it. Scinax squalirostris is a small species measuring 24–29 mm in snout–vent length; the overall appearance is slender. The head is long and wider than the body; the snout is elongated. The tympanum is distinct; the dorsal ground color is brownish. There is black canthal lines bordered with white. Two black stripes enclose a white or flesh-colored area; the belly is greenish yellow. The vocal sac is lemon-colored. Scinax squalirostris occurs in open areas of grasslands and Eryngium spp. but in forests, at elevations below 1,500 m. Breeding takes place in small permanent and temporary waterbodies, including cattle ponds. Scinax squalirostris is a common species. Pollution might be a localized threat, it is known from several protected areas in Brazil and Argentina