October 20, 2012
Food microbiology is the study of the microorganisms that inhabit, create, or contaminate food. Including the study of microorganisms causing food spoilage. ‘Good’ bacteria, however, such as probiotics, are becoming increasingly important in food science. In addition, microorganisms are essential for the production of foods such as cheese, yogurt, other fermented foods, bread, beer and wine. Food safety is a major focus of food microbiology. Pathogenic bacteria, viruses, and toxins produced by microorganisms are all possible contaminants of food.
However, microorganisms and their products can also be used to combat these pathogenic microbes. Probiotic bacteria, including those that produce bacteriocins (toxins created by bacteria to kill rival bacteria), can inhibit pathogens. Alternatively, purified bacteriocins such as nisin can be added directly to food products. Finally, bacteriophages, viruses that only infect bacteria, can be used to kill bacterial pathogens. Thorough preparation of food, including proper cooking, eliminates most bacteria and viruses. However, toxins produced by contaminants may not be heat-labile, and some are not eliminated by cooking
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October 19, 2012
Century egg (‘pidan,’ also known as preserved egg and millennium egg) is a Chinese cuisine ingredient made by preserving fowl eggs in a mixture of clay, ash, salt, quicklime (calcium oxide), and rice hulls for several weeks to several months, depending on the method of processing. Through the process, the yolk becomes a dark green to gray color with a creamy consistency and an odor of sulfur and ammonia, while the white becomes a dark brown, translucent jelly with little flavor.
The transforming agent in the century egg is its alkaline material, which gradually raises the pH of the egg to around 9, 12, or more during the curing process. This chemical process breaks down some of the complex, flavorless proteins and fats, which produces a variety of smaller flavorful compounds. Some eggs have fungal patterns near the surface of the egg white that are likened to pine branches, and that gives rise to one of its Chinese names, the ‘pine-patterned egg.’
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October 19, 2012
Pickling, also known as ‘brining’ or ‘corning,’ is the process of preserving food with acid. Pickling began 4000 years ago using cucumbers native to India. It is called ‘achar’ in northern India. This was used as a way to preserve food for out-of-season use and for long journeys, especially by sea. Salt pork and salt beef were common staples for sailors before the days of steam engines. Although the process was invented to preserve foods, pickles are also made and eaten because people enjoy the resulting flavors.
Pickling may also improve the nutritional value of food by introducing B vitamins produced by bacteria (when pickled in a process utilizing fermentation). The term ‘pickle’ is derived from the Dutch word ‘pekel,’ meaning ‘brine’ (salt water). In the U.S. Canada, and Australia the word ‘pickle’ alone almost always refers to a pickled cucumber (other types of pickles will be described as ‘pickled onion,’ ‘pickled cauliflower,’ etc.), except when it is used figuratively. In the UK, ‘pickle’ refers to Ploughman’s pickle, a kind of chutney; a pickled cucumber is referred to as a ‘gherkin.’
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October 19, 2012
Fermentation [fur-men-tey-shuhn] is when a living cell uses sugar for energy without requiring oxygen. Yeast is an organism that ferments. When yeast ferments sugar, the yeast eats sugar and makes alcohol. Other organisms (such as bacteria) make vinegar (acetic acid) or lactic acid when they ferment sugar. Fermentation is used to make beer, some types of fuel, and to make bread rise. When yeast ferments, it breaks down the glucose into ethanol and carbon dioxide.
Ethanol fermentation always produces ethanol and carbon dioxide. It is important in bread-making, brewing, and winemaking. Lactic acid fermentation produces lactic acid. It happens in muscles of animals when they need lots of energy fast, and is also used to preserve foods in pickling. The word ‘fermentation’ is derived from the Latin verb ‘fervere,’ which means ‘to boil’ (same root as ‘effervescence’). It is thought to have been first used in the late fourteenth century in alchemy, but only in a broad sense. It was not used in the modern scientific sense until around 1600.
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October 18, 2012
The theory of recapitulation [ree-kuh-pich-uh-ley-shuhn] is often known as ‘ontogeny recapitulates phylogeny.’ It was an idea of French physician Étienne Serres in 1824. In 1886 German biologist Ernst Haekel proposed that the embryonic development of an individual organism (its ontogeny) followed the same path as the evolutionary history of its species (its phylogeny). It is also called the ‘biogenetic law’ or ’embryological parallelism.’
It was a theory that tied evolution (change in organisms over time) with embryology (the way organisms develop before they are born). The theory basically stated that before they are born, organisms pass through developmental stages that look like adult animals of other species, in roughly the same order that these other species split off during evolution. Although there is something to this idea, it is no longer thought to be such a useful way to look at development.
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October 18, 2012
In biology, phylogeny [fahy-loj-uh-nee] refers to the evolutionary relationships among groups of organisms (e.g. species, populations). The term ‘phylogenetics’ derives from the Greek terms ‘phyle’ and ‘phylon,’ denoting ‘tribe’ and ‘race’; and the term ‘genetikos,’ denoting ‘relative to birth,’ from ‘genesis’ (‘origin’). The result of phylogenetic studies is a hypothesis about the evolutionary history of taxonomic groups. Phylogenetic analyses have become essential in researching the evolutionary tree of life. The overall goal of National Science Foundation’s Assembling the Tree of Life activity (AToL) is to resolve evolutionary relationships for large groups of organisms throughout the history of life, with the research often involving large teams working across institutions and disciplines.
Taxonomy, the classification, identification, and naming of organisms, is usually richly informed by phylogenetics, but remains methodologically and logically distinct. The degree to which taxonomy depends on phylogenies differs between schools of taxonomy: ‘numerical taxonomy’ ignored phylogeny altogether, trying to represent the similarity between organisms instead; ‘phylogenetic systematics’ tries to reproduce phylogeny in its classification without loss of information; ‘evolutionary taxonomy’ tries to find a compromise between them in order to represent stages of evolution.
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October 16, 2012
Opinions differ on whether viruses are a form of life, or organic structures that interact with living organisms. They have been described as ‘organisms at the edge of life,’ since they resemble organisms in that they possess genes and evolve by natural selection, and reproduce by creating multiple copies of themselves through self-assembly. Although they have genes, they do not have a cellular structure, which is often seen as the basic unit of life.
Viruses do not have their own metabolism, and require a host cell to make new products. They therefore cannot naturally reproduce outside a host cell (although bacterial species such as chlamydia are considered living organisms despite the same limitation). Accepted forms of life use cell division to reproduce, whereas viruses spontaneously assemble within cells. They differ from autonomous growth of crystals as they inherit genetic mutations while being subject to natural selection. Virus self-assembly within host cells has implications for the study of the origin of life, as it lends further credence to the hypothesis that life could have started as self-assembling organic molecules.
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October 16, 2012
Deutsche Physik (literally: ‘German Physics’) or ‘Aryan Physics’ was a nationalist movement in the German physics community in the early 1930s against the work of Albert Einstein and other modern theoretically based physics, labeled ‘Jewish Physics’ (German: ‘Jüdische Physik’). The term was taken from the title of a 4-volume physics textbook by Philipp Lenard in the 1930s.
This movement began as an extension of a German nationalistic movement in the physics community which went back as far as World War I. In 1915, during fighting between the German army and Belgian resistance fighters after the German invasion in Belgium, the library of the Katholieke Universiteit in Leuven caught fire when German troops looted and set fire to the town. The loss of the library led to a protest note by British scientists, which was signed also by eight distinguished British scientists, namely William Bragg, William Crookes, Alexander Fleming, Horace Lamb, Oliver Lodge, William Ramsay, Baron Rayleigh, and J.J. Thomson, and in which it was assumed that the war propaganda mentioned corresponded to real behavior of German soldiers.
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October 13, 2012
Fallibilism [fal-uh-buhl-iz-uhm] (‘liable to err’) is the philosophical principle that human beings could be wrong about their beliefs, expectations, or their understanding of the world. In the most commonly used sense of the term, this consists in being open to new evidence that would disprove some previously held position or belief, and in the recognition that ‘any claim justified today may need to be revised or withdrawn in light of new evidence, new arguments, and new experiences.’
This position is taken for granted in the natural sciences. In another sense, it refers to the consciousness of ‘the degree to which our interpretations, valuations, our practices, and traditions are temporally indexed’ and subject to (possibly arbitrary) historical flux and change. Such ‘time-responsive’ fallibilism consists in an openness to the confirmation of a possibility that one anticipates or expects in the future.
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October 11, 2012
In sociology, articulation labels the process by which particular classes appropriate cultural forms and practices for their own use. The term appears to have originated from the work of Italian political theorist Antonio Gramsci, specifically from his conception of ‘superstructure’ (culture, institutions, political power structures, roles, rituals, and state, which are supported by the ‘base,’ the forces and relations of production). In this theory, cultural forms and practices have relative autonomy; socio-economic structures of power do not determine them, but rather they relate to them.
‘The theory of articulation recognizes the complexity of cultural fields. It preserves a relative autonomy for cultural and ideological elements (…) but also insists that those combinatory patterns that are actually constructed do mediate deep, objective patterns in the socio-economic formation, and that the mediation takes place in struggle: the classes fight to articulate together constituents of the cultural repe[r]toire in particular ways so that they are organized in terms of principles or sets of values determined by the position and interests of the class in the prevailing mode of production.’
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October 7, 2012
Project A119, also known as ‘A Study of Lunar Research Flights,’ was a top-secret plan developed in the late 1950s by the United States Air Force. The aim of the project was to detonate a nuclear bomb on the Moon to boost public morale in the United States after the Soviet Union took an early lead in the Space Race. The existence of the project was revealed in 2000 by a former NASA executive, Leonard Reiffel, who led the project in 1958.
A young Carl Sagan was part of the team responsible for predicting the effects of a nuclear explosion in low gravity. Project A119 was never carried out, primarily because a moon landing would be a much more acceptable achievement in the eyes of the American public. The project documents remained secret for nearly 45 years, and despite Reiffel’s revelations, the US government has never officially recognized its involvement in the study.
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October 7, 2012
Positive atheism (also called ‘strong atheism’ and ‘hard atheism’) is the form of atheism that asserts that no deities exist. Negative atheism (also called ‘weak atheism’ and ‘soft atheism’) is any other type of atheism, wherein a person does not believe in the existence of any deities, but does not explicitly assert there to be none.
The terms negative atheism and positive atheism were used by British philosopher Antony Flew in 1976,[1] and appeared again in Boston University philosopher Michael Martin’s writings in 1990. Because of flexibility in the term ‘god,’ it is possible that a person could be a positive/strong atheist in terms of certain conceptions of God, while remaining a negative/weak atheist in terms of others.
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