Existentialism is a term applied to the work of a number of late 19th- and 20th-century philosophers who, despite profound doctrinal differences, shared the belief that their philosophical thinking begins with the human subject - not merely the thinking subject, but the acting, feeling, living human individual. In existentialism, the individual's starting point is characterized by what has been called the “existential attitude”, or a sense of disorientation and confusion in the face of an apparently meaningless or absurd world. Many existentialists have also regarded traditional systematic or academic philosophies, in both style and content, as too abstract and remote from concrete human experience.
Søren Kierkegaard and Friedrich Nietzsche were two of the first philosophers considered fundamental to the existentialist movement, though neither used the term “existentialism” and it is unclear whether they would have supported the existentialism of the 20th century. They focus on subjective human experience rather than the objective truths of mathematics and science, which they believed were too detached or observational to truly get at the human experience. Like Pascal, they were interested in people's quiet struggle with the apparent meaninglessness of life and the use of diversion to escape from boredom.
Concepts
Existence precedes essence
A central proposition of existentialism is that existence precedes essence, which means that the most important consideration for the individual is the fact that he or she is an individual - an independently acting and responsible conscious being (“existence”) - rather than what labels, roles, stereotypes, definitions, or other preconceived categories the individual fits (“essence”). The actual life of the individual is what constitutes what could be called his or her “true essence” instead of there being an arbitrarily attributed essence used by others to define him or her. Thus, human beings, through their own consciousness, create their own values and determine a meaning to their life.
The Absurd
The notion of the Absurd contains the idea that there is no meaning to be found in the world beyond what meaning we give it. This meaninglessness also encompasses the amorality or “unfairness” of the world. This contrasts with the notion that “bad things don't happen to good people”; to the world, metaphorically speaking, there is no such thing as a good or a bad person; what happens happens, and it may just as well happen to a “good” person as to a “bad” person.
Because of the world's absurdity, at any point in time, anything can happen to anyone, and a tragic event could plummet someone into direct confrontation with the Absurd.
Facticity
Facticity is a concept defined by Sartre in Being and Nothingness as the “in-itself”, of which humans are in the mode of not being. This can be more easily understood when considering it in relation to the temporal dimension of the past: one's past is what one is in the sense that it co-constitutes oneself. However, to stay that one is only one's past would be to ignore a significant part of reality (the present and the future), while saying that one's past is only what one was, would entirely detach it from them now. A denial of one's own concrete past constitutes an inauthentic lifestyle, and the same goes for all other kinds of facticity (having a body - e.g., one that does not allow a person to run faster than the speed of sound - identity, values, etc.)
Facticity is both a limitation and a condition of freedom. It is a limitation in that a large part of one's facticity consists of things one couldn't have chosen (birthplace, etc.), but a condition in the sense that one's values most likely will depend on it. However, even though one's facticity is “set in stone” (as being past, for instance), it cannot determine a person: The value ascribed to one's facticity is still ascribed to it freely by that person. As an example, consider two men, one of whom has no memory of his past and the other remembers everything. They both have committed many crimes, but the first man, knowing nothing about this, leads a rather normal life while the second man, feeling trapped by his own past, continues a life of crime, blaming his own past for “trapping” him in his life There is nothing essential about his committing crimes, but he ascribes this meaning to his past.
However, to disregard one's facticity when one, in the continual process of self-making, projects oneself into the future, would be to put oneself in denial of oneself, and would thus be inauthentic. In other words, the origin of one's projection will still have to be one's facticity, although in the mode of not being it (essentially). Another aspect of facticity is that it entails angst, both in the sense that freedom “produces” angst when limited by facticity, and in the sense that the lack of the possibility of having facticity to “step in” for one to take responsibility for something one has done also produces angst.
Authenticity
The theme of authentic existence is common to many existentialist thinkers. It is often taken to mean that one has to “create oneself” and then lie in accordance with this self. What is meant by authenticity is that in acting, one should act as oneself, not as “one” acts or as “one's genes” or any other essence requires. The authentic act is one that is in accordance with one's freedom. Of course, as a condition of freedom is facticity, but not to the degree that this facticity can in any way determine one's choices (in the sense that one could blame one's background for making the choice one made) . The role of facticity in relation to authenticity involves letting one's actual values come into play when one makes a choice (instead of, like Kierkegaard's Aesthete, “choosing” randomly), so that one also takes responsibility for the act instead of choosing either-or without allowing the options to have different values.
In contrast to this, the inauthentic is the denial to live in accordance with one's freedom. this can take many forms, from pretending choices are meaningless or random, through convincing oneself that some form of determinism is true, a sort of “mimicry” where one acts as “one should”. How “one” should act is often determined by an image one has of how one such of oneself (say, a bank manager, lion tamer, prostitute, etc.) acts. This image usually corresponds to some sort of social norm, but this does not mean that all acting in accordance with social norms is inauthentic: The main point is the attitude that one takes to one's own freedom and responsibility, and the extent to which one acts in accordance with this freedom.
Angst
“Existential angst”, sometimes called dread anxiety, or anguish, is a term that is common to many existentialist thinkers. It is generally held to be a negative feeling arising from the experience of human freedom and responsibility. this archetypal example is the experience one has when standing on a cliff where one not only fears falling of it, but also dreads the possibility of throwing oneself off. In this experience that “nothing is holding me back”, one senses that the lack of anything that predetermines one to either throw oneself or to a stand still, and one experiences one's own freedom.
It can also be seen in relation to the previous point how angst is before nothing, and this is what sets it apart from fear that has an object. While in the case of fear, one can take definite measures to remove the object of fear, in the case of angst, no such “constructive” measures are possible. the use of the word “nothing” in this context relates both to the inherent insecurity about the consequences of one's actions, and to the fault that, in experiencing one's freedom as angst, one also realizes that one will be fully responsible for these consequences, there is no thing in a person (his or genes, for instance) that acts in her or his stead, and that he or she can “blame” if something goes wrong. Therefore, not every choice is perceived as having dreadful consequences (and, it can be claimed, human lives would be unbearable if every choice facilitated dread). However, this doesn't change the fact that freedom remains a condition of every action. Angst is often described as a drama an adolescent troubles with their drawing developmental years.
Despair
Despair, in existentialism, is generally defined as a loss of hope. More specifically, it is a loss of hope in reaction to a breakdown in one or more of the defining qualities of one's self or identity. If a person is invested in being a particular thing, such as a bus driver or an upstanding citizen, and then finds his being-thing compromised, he would normally be found in a state of despair - a hopeless state. For example, a singer who loses her ability to sing may despair if she has nothing else to fall back on, nothing on which to rely for her identity. She finds herself unable to be what defined her being.
What sets the existentialist notion of despair apart from the conventional definition is that existentialist despair is a state one is in even when he isn't overtly in despair. So long as a person's identity depends on qualities that can crumble, he is considered to be in perpetual danger.
Opposition to positivism and rationalism
Existentialists oppose definitions of human beings as primarily rational, and, therefore, oppose positivism and rationalism. Existentialism asserts that people actually make decisions based on subjective meaning rather than purely rationally. The rejection of reason as the source of meaning is a common theme of existentialist thought, as is the focus on the feelings of anxiety and dread that we feel in the face of our own radical freedom and our awareness of death. Kierkegaard advocated rationality as a means to interact with the objective world (e.g., in the natural sciences), but when it comes to existential problems, reason is sufficient: “Human reason has boundaries.”
Like Kierkegaard, Sartre saw problems with rationality, calling it a form of “bad faith”, an attempt by the self to impose structure on a world of phenomena - “the Other” - that is fundamentally irrational and random. According to Sartre, rationality and other forms of bad faith hinder people from finding meaning in freedom. To try to suppress their feelings of anxiety and dread, people confine themselves within everyday experience, Sartre asserts, thereby relinquishing their freedom and acquiescing to being possessed in one form or another by “the Look” of “the Other” (i.e., possessed by another person - or at least one's idea of that person).
Sources:
http://en.wikipedia.org/wiki/Existentialism
Wednesday, June 19, 2013
Monday, May 20, 2013
greenhouse effect
The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases.
Solar radiation at the frequencies of visible light largely passes through the atmosphere to warm the planetary surface, which then emits this energy at the lower frequencies of infrared thermal radiation. Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate much of the energy to the surface and lower atmosphere. The mechanism is named after the effect of solar radiation passing through glass and warming a greenhouse, but the way it retains heat is fundamentally different as a greenhouse works by reducing air flow, isolating the warm air inside the structure so that heat is not lost by convection.
If an ideal thermally conductive blackbody was the same distance from the sun as the Earth is, it would have a temperature of about 5.3 °C. However, since the Earth reflects about 30% of the incoming sunlight, this idealized planet's effective temperature (the temperature of a black body that would emit the same amount of radiation) would be about -18 °C. the surface temperature of this hypothetical planet is 33 °C below the Earth's actual surface temperature of approximately 14 °C. The mechanism that produces this difference between the actual surface temperature and the effective temperature is due to the atmosphere and is known as the greenhouse effect.
Earth's natural greenhouse effect makes life as we know it possible. However, human activities, primarily the burning of fossil fuels and clearing of forests, have intensified the natural greenhouse effect, causing global warming.
By their percentage contribution to the greenhouse effect on Earth, the four major gases are:
Greenhouse gas
A greenhouse (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Greenhouse gases greatly affect the temperature of the Earth; without them, the Earth's surface would average about 33 °C colder than the present average of 14 °C (57 °F).
Since the beginning of the Industrial Revolution, the burning of fossil fuels has contributed to a 40% increase in the concentration of carbon dioxide in the atmosphere from 280ppm to 397ppm, despite the uptake of a large portion of the emissions by various natural "sinks" involved in the carbon cycle. Anthropogenic carbon dioxide (CO²) emissions (i.e., emissions produced by human activities) come from combustion of carbon-based fuels, principally wood, coal, oil, and natural gas.
Greenhouse
A greenhouse is a structural building with different types of covering materials that pass sunlight, usually glass, or plastic. It mainly heats up because the sun warms the ground inside, which then warms the air in the greenhouse. The air continues to heat because it is confined within the greenhouse, unlike the environment outside the greenhouse where warm air near the surface rises and mixes with cooler air aloft. In addition, the warmed structures and plants inside the greenhouse re-radiate some of their thermal energy in the infrared spectrum, to which glass is partly opaque, so some of this energy is also trapped inside the greenhouse. However, this latter process is a minor player compared with the former (convective) process. Thus, the primary heating mechanism of a greenhouse is convection. This can be demonstrated by opening a small window near the roof of a greenhouse; the temperature drops considerably. This principle is the basis of the autovent automatic cooling system. Thus, the glass used for a greenhouse works as a barrier to air flow, and its effect is to trap energy within the greenhouse. The air that is warmed near the ground is prevented from rising indefinitely and flowing away.
Although heat loss due to thermal conduction through the glass and other building materials occurs, net energy (and therefore temperature) increases inside the greenhouse.
Convection
Convection is the concerted, collective movement of ensembles of molecules within fluids (e.g., liquids, gases) and rheids. It is the circulatory motion that occurs in a fluid at a nonuniform temperature owing to the variation of its density and the action of gravity.
Blackbody
A blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence.
Real materials emit energy at a fraction ‒ called the emissivity ‒ blackbody energy levels. By definition, a blackbody in thermal equilibrium has an emissivity of ε = 1.0. A source with lower emissivity independent of frequency often is referred to as a gray body. Construction of blackbodies with emissivity as close to one as possible remains a topic of current interest. A white body is one with a "rough surface that reflects all incident rays completely and uniformly in all directions."
Effective temperature
The effective temperature of a body such as a star or planet is the temperature of a blackbody that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's temperature when the body's emissivity curve (as a function of wavelength) is not known.
When the star's or planet's net emissivity in the relevant wavelength band is less than unity (less than that of a blackbody), the actual temperature of the body will be higher than the effective temperature. The net emissivity may be low due to surface or atmospheric properties, including the greenhouse effect.
Emissivity
The emissivity of the material (usually written ε or e) is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a blackbody at the same temperature. A true blackbody would have an ε = 1 while any real object would have ε < 1. Emissivity is a dimensionless quantity.
In general, the duller and blacker a material is, the closer its emissivity is to 1. The more reflective a material is, the lower its emissivity. Highly polished silver has an emissivity of about 0.02.
Sources:
http://en.wikipedia.org/wiki/Greenhouse_effect
http://en.wikipedia.org/wiki/Greenhouse_gas
http://en.wikipedia.org/wiki/Greenhouse
http://en.wikipedia.org/wiki/Convection
http://en.wikipedia.org/wiki/Blackbody
http://en.wikipedia.org/wiki/Effective_temperature
http://en.wikipedia.org/wiki/Emissivity
Solar radiation at the frequencies of visible light largely passes through the atmosphere to warm the planetary surface, which then emits this energy at the lower frequencies of infrared thermal radiation. Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate much of the energy to the surface and lower atmosphere. The mechanism is named after the effect of solar radiation passing through glass and warming a greenhouse, but the way it retains heat is fundamentally different as a greenhouse works by reducing air flow, isolating the warm air inside the structure so that heat is not lost by convection.
If an ideal thermally conductive blackbody was the same distance from the sun as the Earth is, it would have a temperature of about 5.3 °C. However, since the Earth reflects about 30% of the incoming sunlight, this idealized planet's effective temperature (the temperature of a black body that would emit the same amount of radiation) would be about -18 °C. the surface temperature of this hypothetical planet is 33 °C below the Earth's actual surface temperature of approximately 14 °C. The mechanism that produces this difference between the actual surface temperature and the effective temperature is due to the atmosphere and is known as the greenhouse effect.
Earth's natural greenhouse effect makes life as we know it possible. However, human activities, primarily the burning of fossil fuels and clearing of forests, have intensified the natural greenhouse effect, causing global warming.
By their percentage contribution to the greenhouse effect on Earth, the four major gases are:
- water vapor, 36-70%
- carbon dioxide, 9-26%
- methane, 4-9%
- ozone, 3-7%
Greenhouse gas
A greenhouse (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Greenhouse gases greatly affect the temperature of the Earth; without them, the Earth's surface would average about 33 °C colder than the present average of 14 °C (57 °F).
Since the beginning of the Industrial Revolution, the burning of fossil fuels has contributed to a 40% increase in the concentration of carbon dioxide in the atmosphere from 280ppm to 397ppm, despite the uptake of a large portion of the emissions by various natural "sinks" involved in the carbon cycle. Anthropogenic carbon dioxide (CO²) emissions (i.e., emissions produced by human activities) come from combustion of carbon-based fuels, principally wood, coal, oil, and natural gas.
Greenhouse
A greenhouse is a structural building with different types of covering materials that pass sunlight, usually glass, or plastic. It mainly heats up because the sun warms the ground inside, which then warms the air in the greenhouse. The air continues to heat because it is confined within the greenhouse, unlike the environment outside the greenhouse where warm air near the surface rises and mixes with cooler air aloft. In addition, the warmed structures and plants inside the greenhouse re-radiate some of their thermal energy in the infrared spectrum, to which glass is partly opaque, so some of this energy is also trapped inside the greenhouse. However, this latter process is a minor player compared with the former (convective) process. Thus, the primary heating mechanism of a greenhouse is convection. This can be demonstrated by opening a small window near the roof of a greenhouse; the temperature drops considerably. This principle is the basis of the autovent automatic cooling system. Thus, the glass used for a greenhouse works as a barrier to air flow, and its effect is to trap energy within the greenhouse. The air that is warmed near the ground is prevented from rising indefinitely and flowing away.
Although heat loss due to thermal conduction through the glass and other building materials occurs, net energy (and therefore temperature) increases inside the greenhouse.
Convection
Convection is the concerted, collective movement of ensembles of molecules within fluids (e.g., liquids, gases) and rheids. It is the circulatory motion that occurs in a fluid at a nonuniform temperature owing to the variation of its density and the action of gravity.
Blackbody
A blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence.
Real materials emit energy at a fraction ‒ called the emissivity ‒ blackbody energy levels. By definition, a blackbody in thermal equilibrium has an emissivity of ε = 1.0. A source with lower emissivity independent of frequency often is referred to as a gray body. Construction of blackbodies with emissivity as close to one as possible remains a topic of current interest. A white body is one with a "rough surface that reflects all incident rays completely and uniformly in all directions."
Effective temperature
The effective temperature of a body such as a star or planet is the temperature of a blackbody that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's temperature when the body's emissivity curve (as a function of wavelength) is not known.
When the star's or planet's net emissivity in the relevant wavelength band is less than unity (less than that of a blackbody), the actual temperature of the body will be higher than the effective temperature. The net emissivity may be low due to surface or atmospheric properties, including the greenhouse effect.
Emissivity
The emissivity of the material (usually written ε or e) is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a blackbody at the same temperature. A true blackbody would have an ε = 1 while any real object would have ε < 1. Emissivity is a dimensionless quantity.
In general, the duller and blacker a material is, the closer its emissivity is to 1. The more reflective a material is, the lower its emissivity. Highly polished silver has an emissivity of about 0.02.
Sources:
http://en.wikipedia.org/wiki/Greenhouse_effect
http://en.wikipedia.org/wiki/Greenhouse_gas
http://en.wikipedia.org/wiki/Greenhouse
http://en.wikipedia.org/wiki/Convection
http://en.wikipedia.org/wiki/Blackbody
http://en.wikipedia.org/wiki/Effective_temperature
http://en.wikipedia.org/wiki/Emissivity
Sunday, May 12, 2013
antibiotic
An antibacterial is an agent that inhibits bacterial growth or kills bacteria. The term is often used synonymously with the term antibiotic(s). Today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic(s) has come to denote a broader range of antimicrobial compounds, including anti-fungal and other compounds.
The term antibiotic was first used in 1942 by Selman Waksman and his collaborators in journal articles to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution. This definition excluded substances that kill bacteria, but are not produced by microorganisms (such as gastric juices and hydrogen peroxide). It also excluded synthetic antibacterial compounds such as the sulfonamides. Many antibacterial compounds are relatively small molecules with a molecular weight of less than 2000 atomic units.
With advances in medicinal chemistry, most of today's antibacterials chemically are semisynthetic modifications of various natural compounds. Compounds that are still isolated from living organisms are the aminoglycosides, whereas other antibacterials -- for example, the sulfonamides, the quinolones, and the oxazolidinones -- are produced solely by chemical synthesis. In accordance with this, many antibacterial compounds are classified on the basis of chemical/biosynthetic origin into natural, semisynthetic, and synthetic. Another classification system is based on biological activity; in this classification, antibacterials are divided into two broad groups according to their biological effect on microorganisms: bactericidal agents kill bacteria, and bacteriostatic agents slow down or stall bacterial growth.
Antibiotic resistance is a form of drug resistance whereby some (or, less commonly, all) sub-populations of a microorganism, is usually a bacterial species, are able to survive after exposure to one or more antibiotics; pathogens resistant to multiple antibiotics are considered multidrug resistant (MDR) or, more colloquially, superbugs.
Antibiotic resistance is a serious and growing phenomenon in contemporary medicine and has emerged as one of the pre-eminent public health concerns of the 21st century, particularly as it pertains to pathogenic organisms (the term is especially relevant to organisms which cause disease in humans). In the simplest cases, drug-resistant organisms may have acquired resistance to first-line antibiotics, thereby necessitating the use of second-line agents. Typically, a first-line agent is selected on the basis of several factors including safety, availability and cost; a second-line agent is usually broader in spectrum, has a less favorable risk-benefit profile and is more expensive or, in dire circumstances, is locally unavailable.
It may take the form of a spontaneous or induced genetic mutation, or the acquisition of resistance genes from other bacterial species by horizontal gene transfer via conjugation, transduction, or transformation. Many antibiotic resistance genes reside on transmissible plasmids, facilitating their transfer. Exposure to an antibiotic naturally selects for the survival of the organisms with the genes for resistance. In this way, a gene for antibiotic resistance may readily spread through an ecosystem of bacteria. Antibiotic-resistance plasmids frequently contain genes conferring resistance to several different antibiotics.
Genes for resistance to antibiotics, like the antibiotics themselves, are ancient. However, the increasing prevalence of antibiotic-resistant bacterial infections seen in clinical practice stems from antibiotic use both within human medicine and veterinary medicine. Any use of antibiotics can increase selective pressure in a population of bacteria to allow the resistant bacteria to thrive and the susceptible bacteria to die off. As resistance towards antibiotics becomes more common, a greater need for alternative treatments arises. However, despite a push for new antibiotic therapies there has been a continued decline in the number of newly approved drugs. Antibiotic resistance therefore poses a significant problem.
Plasmid
A plasmid is a small DNA molecule that is physically separate from, and can replicate independently of, chromosomal DNA within a cell. Most commonly found as small circular, double stranded DNA molecules in bacteria, plasmids are sometimes present in archaea and eukaryotic organisms. In nature, plasmids carry genes that may benefit survival of the organism (e.g. antibiotic resistance), and can frequently be transmitted from one bacterium to another (even of another species) via horizontal gene transfer.
Plasmid sizes vary from 1 to 1000 kilo base pairs (kbp). The number of identical plasmids in a single cell can range anywhere from one to thousands under some circumstances. Plasmids can be considered part of the mobilome because they are often associated with conjugation, a mechanism of horizontal gene transfer.
Plasmid host-to-host transfer requires direct mechanical transfer by conjugation, or changes in incipient host gene expression allowing the intentional uptake of the genetic element by transformation. Plasmids provide a mechanism for horizontal gene transfer within a population of microbes and typically provide a selective advantage under a given environmental state. Plasmids may carry genes that provide resistance to naturally occurring antibiotics in a competitive environmental niche, or the proteins produced may act as toxins under similar circumstances.
Sources:
http://en.wikipedia.org/wiki/Antibacterial
http://en.wikipedia.org/wiki/Antibiotic_resistance
http://en.wikipedia.org/wiki/Plasmid
The term antibiotic was first used in 1942 by Selman Waksman and his collaborators in journal articles to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution. This definition excluded substances that kill bacteria, but are not produced by microorganisms (such as gastric juices and hydrogen peroxide). It also excluded synthetic antibacterial compounds such as the sulfonamides. Many antibacterial compounds are relatively small molecules with a molecular weight of less than 2000 atomic units.
With advances in medicinal chemistry, most of today's antibacterials chemically are semisynthetic modifications of various natural compounds. Compounds that are still isolated from living organisms are the aminoglycosides, whereas other antibacterials -- for example, the sulfonamides, the quinolones, and the oxazolidinones -- are produced solely by chemical synthesis. In accordance with this, many antibacterial compounds are classified on the basis of chemical/biosynthetic origin into natural, semisynthetic, and synthetic. Another classification system is based on biological activity; in this classification, antibacterials are divided into two broad groups according to their biological effect on microorganisms: bactericidal agents kill bacteria, and bacteriostatic agents slow down or stall bacterial growth.
Antibiotic resistance is a form of drug resistance whereby some (or, less commonly, all) sub-populations of a microorganism, is usually a bacterial species, are able to survive after exposure to one or more antibiotics; pathogens resistant to multiple antibiotics are considered multidrug resistant (MDR) or, more colloquially, superbugs.
Antibiotic resistance is a serious and growing phenomenon in contemporary medicine and has emerged as one of the pre-eminent public health concerns of the 21st century, particularly as it pertains to pathogenic organisms (the term is especially relevant to organisms which cause disease in humans). In the simplest cases, drug-resistant organisms may have acquired resistance to first-line antibiotics, thereby necessitating the use of second-line agents. Typically, a first-line agent is selected on the basis of several factors including safety, availability and cost; a second-line agent is usually broader in spectrum, has a less favorable risk-benefit profile and is more expensive or, in dire circumstances, is locally unavailable.
It may take the form of a spontaneous or induced genetic mutation, or the acquisition of resistance genes from other bacterial species by horizontal gene transfer via conjugation, transduction, or transformation. Many antibiotic resistance genes reside on transmissible plasmids, facilitating their transfer. Exposure to an antibiotic naturally selects for the survival of the organisms with the genes for resistance. In this way, a gene for antibiotic resistance may readily spread through an ecosystem of bacteria. Antibiotic-resistance plasmids frequently contain genes conferring resistance to several different antibiotics.
Genes for resistance to antibiotics, like the antibiotics themselves, are ancient. However, the increasing prevalence of antibiotic-resistant bacterial infections seen in clinical practice stems from antibiotic use both within human medicine and veterinary medicine. Any use of antibiotics can increase selective pressure in a population of bacteria to allow the resistant bacteria to thrive and the susceptible bacteria to die off. As resistance towards antibiotics becomes more common, a greater need for alternative treatments arises. However, despite a push for new antibiotic therapies there has been a continued decline in the number of newly approved drugs. Antibiotic resistance therefore poses a significant problem.
Plasmid
A plasmid is a small DNA molecule that is physically separate from, and can replicate independently of, chromosomal DNA within a cell. Most commonly found as small circular, double stranded DNA molecules in bacteria, plasmids are sometimes present in archaea and eukaryotic organisms. In nature, plasmids carry genes that may benefit survival of the organism (e.g. antibiotic resistance), and can frequently be transmitted from one bacterium to another (even of another species) via horizontal gene transfer.
Plasmid sizes vary from 1 to 1000 kilo base pairs (kbp). The number of identical plasmids in a single cell can range anywhere from one to thousands under some circumstances. Plasmids can be considered part of the mobilome because they are often associated with conjugation, a mechanism of horizontal gene transfer.
Plasmid host-to-host transfer requires direct mechanical transfer by conjugation, or changes in incipient host gene expression allowing the intentional uptake of the genetic element by transformation. Plasmids provide a mechanism for horizontal gene transfer within a population of microbes and typically provide a selective advantage under a given environmental state. Plasmids may carry genes that provide resistance to naturally occurring antibiotics in a competitive environmental niche, or the proteins produced may act as toxins under similar circumstances.
Sources:
http://en.wikipedia.org/wiki/Antibacterial
http://en.wikipedia.org/wiki/Antibiotic_resistance
http://en.wikipedia.org/wiki/Plasmid
Wednesday, February 27, 2013
curator
A curator (from Latin: curare meaning "take care") is a manager or overseer. Traditionally, a curator or keeper of a cultural heritage institution (e.g., gallery, museum, library or archive) is a content specialist responsible for an institution's collections and involved with the interpretation of heritage material. The object of a traditional curator's concern necessarily involves tangible objects of some sort, whether it be artwork, collectibles, historic items or scientific collections.
In smaller organizations, a curator may have sole responsibility for the acquisition and care of objects. The curator will make decisions regarding what objects to take, oversee their potential and documentations, conduct research based on the collection and history that provides propered packaging of art for transportation, and share that research with the public and polymath community through exhibitions and publications. In very small volunteer-based museums, such as local historical societies, a curator may be the only paid staff member.
In larger institutions, the curator's primary function is as a subject specialist, with the expectation that he or she will conduct original research on objects and guide the organization in its collecting. Such institutions can have multiple curators, each assigned to a specific collecting area (e.g., Curator of Ancient Art, Curator of Prints and Drawings, etc.) and often operating under the direction of a head curator. In such organizations, the physical care of the collection may be overseen by museum collection managers or museum conservators, and documentation and administrative matters (such as insurance and loans) are handled by a museum registrar.
Curators generally hold a higher academic degree in their subject, typically a Doctor of Philosophy or a Master's degree in subjects such as history, history of art, archaeology, anthropology, or classics. Curators are also expected to have contributed to their academic field, for example, by delivering public talks, publishing articles or presenting at specialist academic conferences. It is important that curators have knowledge of the current collecting market for their area of expertise, and are aware of current ethical practices and laws that may impact their organization's collecting.
Recently, the increased complexity of many museums and cultural organizations has prompted the emergence of professional programs in fields such as public history, museum studies, arts management, and curating/curatorial practice.
Sources:
http://en.wikipedia.org/wiki/Curator
In smaller organizations, a curator may have sole responsibility for the acquisition and care of objects. The curator will make decisions regarding what objects to take, oversee their potential and documentations, conduct research based on the collection and history that provides propered packaging of art for transportation, and share that research with the public and polymath community through exhibitions and publications. In very small volunteer-based museums, such as local historical societies, a curator may be the only paid staff member.
In larger institutions, the curator's primary function is as a subject specialist, with the expectation that he or she will conduct original research on objects and guide the organization in its collecting. Such institutions can have multiple curators, each assigned to a specific collecting area (e.g., Curator of Ancient Art, Curator of Prints and Drawings, etc.) and often operating under the direction of a head curator. In such organizations, the physical care of the collection may be overseen by museum collection managers or museum conservators, and documentation and administrative matters (such as insurance and loans) are handled by a museum registrar.
Curators generally hold a higher academic degree in their subject, typically a Doctor of Philosophy or a Master's degree in subjects such as history, history of art, archaeology, anthropology, or classics. Curators are also expected to have contributed to their academic field, for example, by delivering public talks, publishing articles or presenting at specialist academic conferences. It is important that curators have knowledge of the current collecting market for their area of expertise, and are aware of current ethical practices and laws that may impact their organization's collecting.
Recently, the increased complexity of many museums and cultural organizations has prompted the emergence of professional programs in fields such as public history, museum studies, arts management, and curating/curatorial practice.
Sources:
http://en.wikipedia.org/wiki/Curator
Sunday, December 30, 2012
church architecture
In architecture, the apse (Greek ἀψίς (apsis), then Latin absis: "arch, vault"; sometimes written apsis; plural apses) is a semicircular recess covered with a hemispherical vault or semi-dome. In Romanesque, Byzantine and Gothic Christian abbey, cathedral and church architecture, the term is applied to a semi-circular or polygonal termination of the main building at the liturgical east end (where the altar is), regardless of the shape of the roof, which may be flat, sloping, domed or hemispherical.
The apse is the semicircular or polygonal termination to the choir or aisles of a church. In relation to church architecture it is generally the name given to where the altar is placed or where the clergy are seated.
Nave
In Romanesque and Gothic Christian abbey, cathedral basilica and church architecture, the nave is the central approach to the high altar, the main body of the church. "Nave" (Medieval Latin navis, "ship") was probably suggested by the keel shape of its vaulting. The nave of a church, whether Romanesque, Gothic or Classical, extends from the entry -- which may have a separate vestibule, the narthex -- to the chancel and is flanked by lower aisles separated from the nave by an arcade. If the aisles are high and of a width comparable to the central nave, the structure is sometimes said to have three naves.
Transept
A transept (with two semitransepts) is a transverse section, of any building, which lies across the main body of the building. In Christian churches, a transept is an area set crosswise to the nave in a cruciform ("cross-shaped") building in a Romanesque and Gothic Christian church architecture. Each half of a transept is known as a semitransept.
The transept of a church separates the nave from the sanctuary, whether apse, choir, chevet, presbytery, or chancel. The transepts cross the nave at the crossing, which belongs equally to the main nave axis and to the transept. Upon its four piers, the crossing may support a spire (e.g., Salisbury Cathedral), a central tower (e.g., Gloucester Cathedral) or a crossing dome (e.g., Saint Paul's Cathedral).
Narthex
The narthex of a church is the entrance or lobby area, located at the end of the nave, at the far end from the church's main altar. Traditionally the narthex was part of the church building, but it was not considered part of the church proper. It is either an indoor area separated from the nave by a screen or rail, or an external structure such as a porch.
Chancel
The chancel (or presbytery) is the space around the altar in the sanctuary at the liturgical east end of a traditional Christian church building, possibly including the choir. It may terminate in an apse.
As well as the altar, the chancel usually houses the credence table and seats for officiating and assisting ministers. In Anglican and Methodist churches it will usually include the choir. In some traditions, the pulpit and lectern may be in the chancel, but in others these functions are considered proper to the nave.
The chancel is typically raised somewhat above the level of the nave, where the congregation gathers. It may be separated from the nave by a rood screen, a rail, or an open space. In some churches, the congregation may gather on three sides or in a semicircle around the chancel.
Sources:
http://en.wikipedia.org/wiki/Apse
http://en.wikipedia.org/wiki/Nave
http://en.wikipedia.org/wiki/Transept
http://en.wikipedia.org/wiki/Narthex
http://en.wikipedia.org/wiki/Chancel
crypt
In architecture, a crypt (from the Latin crypta and the Greek κρύπτη, kryptē; meaning concealed, private) is a stone chamber or vault beneath the floor of burial vault possibly containing sarcophagi, coffins or relics.
In more modern terms, a crypt is most often a stone chambered vault used to store the deceased. Crypts are usually found in cemeteries and under public religious buildings, such as churches and cathedrals, but are also occasionally found beneath mausolea or chapels on personal estates. Wealthy or prestigious families will often have a 'family crypt' or 'vault' in which all members of the family are interred. Many royal families, for example, have vast crypts containing bodies of dozens of former royals. In some localities an above ground crypt is more commonly called a mausoleum, which also refers to any elaborate building intended as a burial place, for one or any number of people.
Originally crypts were typically found below the apse of a church, such as the Abbey of Saint-Germain in Auxerre, but were later located beneath naves and transepts as well. Occasionally churches were raised high to accommodate a crypt at the ground level, such as Saint Michael's church in Hildesheim, Germany.
Burial Vault
A burial vault is a structural underground tomb.
It is a stone or brick-lined underground space or 'burial' chamber for the interment of a dead body or bodies. They were originally and are still often vaulted and usually have stone slab entrances. They are often privately owned and used for specific family or other groups, but usually stand beneath a public religious building, such as a church, or in a churchyard or cemetery. A crypt may be used as a burial vault.
Sarcophagus
A sarcophagus is a box-like funeral receptacle for a corpse, most commonly carved in stone, and displayed above ground through they may also be buried.
Sarcophagi were most often designed to remain above ground, hence were often ornately carved or elaborately constructed. Some were built to be freestanding, as part of an elaborate sealed tomb or series of tombs, while others were intended for placement in crypts and remain accessible to view.
Relic
In religion, a relic is a part of the body of a saint or a venerated person, or else another type of ancient religious object, carefully preserved for purposes of veneration or as a touchable or tangible memorial. Relics are an important aspect of some forms of Buddhism, Christianity, Hinduism, Shamanism, and many other religions. The word relic comes from the Latin reliquiae, meaning "remains" or "something left behind" (the same root as relinquish).
Mausoleum
A mausoleum is an external free-standing building constructed as a monument enclosing the interment space or burial chamber of a deceased person or persons. A monument without the interment is a cenotaph. A mausoleum may be considered a type of tomb or the tomb may be considered to be within the mausoleum. A Christian mausoleum sometimes include a chapel.
Sources:
http://en.wikipedia.org/wiki/Crypt
http://en.wikipedia.org/wiki/Vault_%28tomb%29
http://en.wikipedia.org/wiki/Sarcophagus
http://en.wikipedia.org/wiki/Relic
http://en.wikipedia.org/wiki/Mausoleum
In more modern terms, a crypt is most often a stone chambered vault used to store the deceased. Crypts are usually found in cemeteries and under public religious buildings, such as churches and cathedrals, but are also occasionally found beneath mausolea or chapels on personal estates. Wealthy or prestigious families will often have a 'family crypt' or 'vault' in which all members of the family are interred. Many royal families, for example, have vast crypts containing bodies of dozens of former royals. In some localities an above ground crypt is more commonly called a mausoleum, which also refers to any elaborate building intended as a burial place, for one or any number of people.
Originally crypts were typically found below the apse of a church, such as the Abbey of Saint-Germain in Auxerre, but were later located beneath naves and transepts as well. Occasionally churches were raised high to accommodate a crypt at the ground level, such as Saint Michael's church in Hildesheim, Germany.
Burial Vault
A burial vault is a structural underground tomb.
It is a stone or brick-lined underground space or 'burial' chamber for the interment of a dead body or bodies. They were originally and are still often vaulted and usually have stone slab entrances. They are often privately owned and used for specific family or other groups, but usually stand beneath a public religious building, such as a church, or in a churchyard or cemetery. A crypt may be used as a burial vault.
Sarcophagus
A sarcophagus is a box-like funeral receptacle for a corpse, most commonly carved in stone, and displayed above ground through they may also be buried.
Sarcophagi were most often designed to remain above ground, hence were often ornately carved or elaborately constructed. Some were built to be freestanding, as part of an elaborate sealed tomb or series of tombs, while others were intended for placement in crypts and remain accessible to view.
Relic
In religion, a relic is a part of the body of a saint or a venerated person, or else another type of ancient religious object, carefully preserved for purposes of veneration or as a touchable or tangible memorial. Relics are an important aspect of some forms of Buddhism, Christianity, Hinduism, Shamanism, and many other religions. The word relic comes from the Latin reliquiae, meaning "remains" or "something left behind" (the same root as relinquish).
Mausoleum
A mausoleum is an external free-standing building constructed as a monument enclosing the interment space or burial chamber of a deceased person or persons. A monument without the interment is a cenotaph. A mausoleum may be considered a type of tomb or the tomb may be considered to be within the mausoleum. A Christian mausoleum sometimes include a chapel.
Sources:
http://en.wikipedia.org/wiki/Crypt
http://en.wikipedia.org/wiki/Vault_%28tomb%29
http://en.wikipedia.org/wiki/Sarcophagus
http://en.wikipedia.org/wiki/Relic
http://en.wikipedia.org/wiki/Mausoleum
Sunday, December 2, 2012
rhetoric
Rhetoric is the art of speaking or writing effectively. It may entail the study of principles and rules of composition formulated by critics of ancient times and can involve the study of writing or speaking as a means of communication or persuasion.
As an art, rhetoric aims to improve the facility of speakers or writers who attempt to inform, persuade, or motivate particular audiences in specific situations. As a subject of formal study and a productive civic practice, rhetoric has played a central role in the Western tradition. Its best known definition comes from Aristotle, who considers it a counterpart of both logic and politics, and calls it "the faculty of observing in any given case the available means of persuasion." Rhetorics typically provide heuristics for understanding, discovering, and developing arguments for particular situations, such as Aristotle's three persuasive audience appeals, logos, pathos, and ethos. The five canons of rhetoric, which trace the traditional tasks in designing a persuasive speech, were first codified in classical Rome, invention (inventio), arrangement (dispositio), style (elocutio), memory (memoria), and delivery (pronuntiatio). Along with grammar and logic (or dialectic), rhetoric is one of the three ancient arts of discourse.
From ancient Greece to the late 19th century, rhetoric was a central part of Western education, filling the need to train public speakers and writers to move audiences to action with arguments. The word is derived from the Greek ῥητορικός (rhētorikós), "oratorical", from ῥήτωρ (rhḗtōr), "public speaker", related to ῥῆμα (rhêma), "that which is said or spoken, word, saying", and ultimately derived from the verb λέγω (loqui), "to speak, say."
Sources:
http://www.merriam-webster.com/dictionary/rhetoric
http://en.wikipedia.org/wiki/Rhetoric
As an art, rhetoric aims to improve the facility of speakers or writers who attempt to inform, persuade, or motivate particular audiences in specific situations. As a subject of formal study and a productive civic practice, rhetoric has played a central role in the Western tradition. Its best known definition comes from Aristotle, who considers it a counterpart of both logic and politics, and calls it "the faculty of observing in any given case the available means of persuasion." Rhetorics typically provide heuristics for understanding, discovering, and developing arguments for particular situations, such as Aristotle's three persuasive audience appeals, logos, pathos, and ethos. The five canons of rhetoric, which trace the traditional tasks in designing a persuasive speech, were first codified in classical Rome, invention (inventio), arrangement (dispositio), style (elocutio), memory (memoria), and delivery (pronuntiatio). Along with grammar and logic (or dialectic), rhetoric is one of the three ancient arts of discourse.
From ancient Greece to the late 19th century, rhetoric was a central part of Western education, filling the need to train public speakers and writers to move audiences to action with arguments. The word is derived from the Greek ῥητορικός (rhētorikós), "oratorical", from ῥήτωρ (rhḗtōr), "public speaker", related to ῥῆμα (rhêma), "that which is said or spoken, word, saying", and ultimately derived from the verb λέγω (loqui), "to speak, say."
Sources:
http://www.merriam-webster.com/dictionary/rhetoric
http://en.wikipedia.org/wiki/Rhetoric
Friday, November 23, 2012
global warming
Global warming is the rise in the average temperature of Earth's atmosphere and oceans since the late 19th century and its projected continuation. Since the early 20th century, Earth's mean surface temperature has increased by about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980. Warming of the climate system is unequivocal, and scientists are more than 90% certain that it is primarily used by increasing concentration of greenhouse gases produced by human activities such as the burning of fossil fuels and deforestation. These findings are recognized by the national science academies of all major industrialized nations.
Climate model projections were summarized in the 2007 Fourth Amendment Report (AR4) by the Intergovernmental Panel of Climate Change (IPCC). They indicated that during the 21st century, the goal surface temperature is likely to rise a further 1.1 to 2.9 °C (2 to 5.2 °F) for their lowest emissions scenario and 2.4 to 6.4 °C (4.3 to 11.5 °F) for their highest. The ranges of these estimates arise from the use of models with differing sensitivity to greenhouse gas concentrations.
According to AR4, warming and related changes will vary from region to region around the globe. The effects of an increase in global temperature include a rise in sea levels and a change in the amount and pattern of precipitation, as well a probable expansion of subtropical deserts. Warming is expected to be strongest in the Arctic and would be associated with the continuing retreat of glaciers, permafrost, and sea ice. Other likely effects of the warming include a more frequent occurrence of extreme-weather events including heat waves, droughts and heavy rainfall, ocean acidification and species extinctions due to shifting temperature regimes. Effects significant to humans include the threat to food security from decreasing crop yields and loss of habitat from inundation.
Proposed policy responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future geoengineering. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC), whose ultimate objective is to prevent dangerous antropogenic (i.e., human-induced) climate change. Parties to the UNFCCC have agreed that deep cuts in emissions are required, and that future global warming should be limited to below 2.0 °C (3.6 °F) relative to the pre-industrial level. Reports published in 2011 by the United Nations Environment Programme and the International Energy Agency suggest that efforts as of the early 21st century to reduce emissions may be inadequate to meet UNFCCC's 2 °C target.
Greenhouse gas
A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. In the solar system, the atmospheres of Venus, Mars, and Titan also contain gases that cause greenhouse effects. Greenhouse gases greatly affect the temperature of the Earth; without them, Earth's surface would average about 33 °C (59 °F) colder than the present average of 14 °C (57 °F).
However, since the beginning of the Industrial Revolution, the burning of fossil fuels has contributed to the increase in carbon dioxide in the atmosphere from 280ppm to 397ppm, despite the uptake of a large portion of the emissions through various natural "sinks" involved in the carbon cycle. Anthropogenic carbon dioxide (CO2) emissions (i.e., emissions produced by human activities) come from combustion of carbon based fuels, principally wood, coal, oil, and natural gas.
Fossil fuels
Fossil fuels are oil, coal, and natural gas that originate from decayed plants and animals found in the Earth's crust. Because they take millions of years to form and are being used at such a rapid rate, fossil fuels are essentially a non-renewable source of energy. Even so, in 2005, more than three-quarters of the world's energy consumption was through the use of fossil fuels. They work to generate steam, electricity and power transportation systems. They make the manufacturing of tens of thousands of commercial goods possible. And although fossil fuels have become synonymous with modern industrial society, their potential to solve some of the challenges of everyday existence has been understood throughout history.
Use of fossil fuels produces around 21.3 billion metric tons of carbon dioxide per year. Carbon dioxide is, of course, one of the notorious greenhouse gases - the stuff directly responsible for global warming.
There are many potential alternatives to the use of fossil fuels (some of them can be rather fruity). These include biofuel, ethanol, and vegetable oil. Most scientists believe it's time for humans to address their addiction to fuels derived from decayed plants and animals and help fossil fuels go the way of the dinosaur.
Sources:
http://en.wikipedia.org/wiki/Global_warming
http://en.wikipedia.org/wiki/Greenhouse_gas
http://tlc.howstuffworks.com/family/fossil-fuel.htm
http://www.instituteforenergyresearch.org/energy-overview/fossil-fuels/
Climate model projections were summarized in the 2007 Fourth Amendment Report (AR4) by the Intergovernmental Panel of Climate Change (IPCC). They indicated that during the 21st century, the goal surface temperature is likely to rise a further 1.1 to 2.9 °C (2 to 5.2 °F) for their lowest emissions scenario and 2.4 to 6.4 °C (4.3 to 11.5 °F) for their highest. The ranges of these estimates arise from the use of models with differing sensitivity to greenhouse gas concentrations.
According to AR4, warming and related changes will vary from region to region around the globe. The effects of an increase in global temperature include a rise in sea levels and a change in the amount and pattern of precipitation, as well a probable expansion of subtropical deserts. Warming is expected to be strongest in the Arctic and would be associated with the continuing retreat of glaciers, permafrost, and sea ice. Other likely effects of the warming include a more frequent occurrence of extreme-weather events including heat waves, droughts and heavy rainfall, ocean acidification and species extinctions due to shifting temperature regimes. Effects significant to humans include the threat to food security from decreasing crop yields and loss of habitat from inundation.
Proposed policy responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future geoengineering. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC), whose ultimate objective is to prevent dangerous antropogenic (i.e., human-induced) climate change. Parties to the UNFCCC have agreed that deep cuts in emissions are required, and that future global warming should be limited to below 2.0 °C (3.6 °F) relative to the pre-industrial level. Reports published in 2011 by the United Nations Environment Programme and the International Energy Agency suggest that efforts as of the early 21st century to reduce emissions may be inadequate to meet UNFCCC's 2 °C target.
Greenhouse gas
A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. In the solar system, the atmospheres of Venus, Mars, and Titan also contain gases that cause greenhouse effects. Greenhouse gases greatly affect the temperature of the Earth; without them, Earth's surface would average about 33 °C (59 °F) colder than the present average of 14 °C (57 °F).
However, since the beginning of the Industrial Revolution, the burning of fossil fuels has contributed to the increase in carbon dioxide in the atmosphere from 280ppm to 397ppm, despite the uptake of a large portion of the emissions through various natural "sinks" involved in the carbon cycle. Anthropogenic carbon dioxide (CO2) emissions (i.e., emissions produced by human activities) come from combustion of carbon based fuels, principally wood, coal, oil, and natural gas.
Fossil fuels
Fossil fuels are oil, coal, and natural gas that originate from decayed plants and animals found in the Earth's crust. Because they take millions of years to form and are being used at such a rapid rate, fossil fuels are essentially a non-renewable source of energy. Even so, in 2005, more than three-quarters of the world's energy consumption was through the use of fossil fuels. They work to generate steam, electricity and power transportation systems. They make the manufacturing of tens of thousands of commercial goods possible. And although fossil fuels have become synonymous with modern industrial society, their potential to solve some of the challenges of everyday existence has been understood throughout history.
Use of fossil fuels produces around 21.3 billion metric tons of carbon dioxide per year. Carbon dioxide is, of course, one of the notorious greenhouse gases - the stuff directly responsible for global warming.
There are many potential alternatives to the use of fossil fuels (some of them can be rather fruity). These include biofuel, ethanol, and vegetable oil. Most scientists believe it's time for humans to address their addiction to fuels derived from decayed plants and animals and help fossil fuels go the way of the dinosaur.
Sources:
http://en.wikipedia.org/wiki/Global_warming
http://en.wikipedia.org/wiki/Greenhouse_gas
http://tlc.howstuffworks.com/family/fossil-fuel.htm
http://www.instituteforenergyresearch.org/energy-overview/fossil-fuels/
Sunday, November 18, 2012
infusion and tea
Infusion
Infusion is the process of extracting chemical compounds or flavors from plant material in a solvent such as water, oil or alcohol, by allowing the material to remain suspended in the solvent over time (a process often called steeping). An infusion is also the name for the resultant liquid.
A common example of an infusion is tea, and many tisanes are prepared in the same way. Lemon, chamomile, senna, apple, ginger, rooibos, and a great many other plants are used individually or in combination. Herbal infusions in water and oil are both commonly used as herbal remedies. Coffee can also be made through infusion (as in a French press), but it is more often made through percolation.
Tisane
Tisane or "herbal tea" is a catch-all term for any non-caffeinated beverage made from the infusion or decoction of herbs, spices, or other plant material. These drinks are distinguished from caffeinated beverages like coffee, maté, and the true teas (black, green, white, yellow, oolong, etc.), or from a decaffeinated tea, in which the caffeine has been removed. In addition to serving as a beverage, many tisanes are also consumed due to a perceived medicinal benefit.
Like brews made from the tea bush (Camellia sinensis), such infusions are prepared by combining hot water and fruits, leaves, roots or grains.
Tisanes can be made with fresh or dried flowers, leaves, seeds or roots, generally by pouring boiling water over the plant parts and letting them steep for a few minutes. Seeds and roots can also be boiled on a stove. The tisane is then strained, sweetened if so desired, and served. Many companies produce herbal tea bags for such infusions.
Flavored teas are prepared by adding other plants to an actual tea (black, oolong, green, yellow or white tea); for example, the popular Earl Grey tea is black tea with bergamot (the orange oil, not the herb of the same name), jasmine tea is Chinese tea with jasmine flowers, and genmaicha is a Japanese green tea with toasted rice.
Tea
Tea is an aromatic beverage commonly prepared by pouring hot or boiling water over cured leaves of the tea plant, Camellia sinensis. After water, tea is the most widely consumed beverage in the world. It has a cooling, slightly bitter, astringent flavor, which many people enjoy.
The phrase "herbal tea" usually refers to infusions of fruit or herbs made without the tea plant, such as rosehip tea or chamomile tea. Alternative phrases for this are tisane or herbal infusion, both bearing an implied contrast with "tea" as it is construed here.
Although single estate teas are available, almost all teas in bags and most other teas sold in the West are blends. Blending may occur in the tea-planting area (as in the case of Assam), or teas from many areas may be blended. The aim of blending is to obtain better taste, higher price, or both, as a more expensive, better-tasting tea may cover the inferior taste of cheaper varieties.
Some teas are not pure varieties, but have been enhanced through additives or special processing. Tea is highly receptive to inclusion of various aromas; this may cause problems in processing, transportation, and storage, but also allows for the design of an almost endless range of scented and flavored variants, such as bergamot (Earl Grey), vanilla, and caramel.
FURTHER READING
Caffeine
Caffeine is a bitter, white crystalline xantine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants. It is most commonly consumed by humans in infusions extracted from the seed of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. Other sources include yerba maté, guarana berries, guayusa, and the yaupon holly.
In humans, caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness.
Percolation Percolation concerns the movement and filtering of fluids through porous materials.
In coffee percolation, soluble compounds leave the coffee grounds and join the water to form coffee. These soluble compounds are the chemical compounds that give coffee its color, taste, and aroma. Insoluble compounds remain within the coffee filter.
Decoction
Decoction is a method of extraction by boiling, of dissolved chemicals, from herbal or plant material, which may include stems, roots, bark and rhizomes. Decoction involves first mashing, and then boiling in water to extract oils, volatile organic compounds, and other chemical substances. Decoction can be used to make tisanes, teas, coffees, tinctures and similar solutions. Decoctions and infusions may produce liquids with differing chemical properties, as the temperature/preparation difference may result in more oil-soluble chemicals in decoctions vs infusions. The process can also be applied to meats and vegetables to prepare bouillon or stock.
A decoction is also the name for the resulting liquid. Although this method of extraction differs from infusion and percolation, the resultant liquids are often functionally similar.
Alkaloids
Alkaloids are a group of naturally occurring chemical compounds, that contain mostly basic nitrogen atoms. They are produced by a large variety of organisms, including bacteria, fungi, plants, and animals, and are part of the group of natural products.
Sources:
http://en.wikipedia.org/wiki/Infusion
http://en.wikipedia.org/wiki/Tisane
http://en.wikipedia.org/wiki/Tea
http://en.wikipedia.org/wiki/Caffeine
http://en.wikipedia.org/wiki/Percolation
http://en.wikipedia.org/wiki/Decoction
http://en.wikipedia.org/wiki/Alkaloid
Infusion is the process of extracting chemical compounds or flavors from plant material in a solvent such as water, oil or alcohol, by allowing the material to remain suspended in the solvent over time (a process often called steeping). An infusion is also the name for the resultant liquid.
A common example of an infusion is tea, and many tisanes are prepared in the same way. Lemon, chamomile, senna, apple, ginger, rooibos, and a great many other plants are used individually or in combination. Herbal infusions in water and oil are both commonly used as herbal remedies. Coffee can also be made through infusion (as in a French press), but it is more often made through percolation.
Tisane
Tisane or "herbal tea" is a catch-all term for any non-caffeinated beverage made from the infusion or decoction of herbs, spices, or other plant material. These drinks are distinguished from caffeinated beverages like coffee, maté, and the true teas (black, green, white, yellow, oolong, etc.), or from a decaffeinated tea, in which the caffeine has been removed. In addition to serving as a beverage, many tisanes are also consumed due to a perceived medicinal benefit.
Like brews made from the tea bush (Camellia sinensis), such infusions are prepared by combining hot water and fruits, leaves, roots or grains.
Tisanes can be made with fresh or dried flowers, leaves, seeds or roots, generally by pouring boiling water over the plant parts and letting them steep for a few minutes. Seeds and roots can also be boiled on a stove. The tisane is then strained, sweetened if so desired, and served. Many companies produce herbal tea bags for such infusions.
Flavored teas are prepared by adding other plants to an actual tea (black, oolong, green, yellow or white tea); for example, the popular Earl Grey tea is black tea with bergamot (the orange oil, not the herb of the same name), jasmine tea is Chinese tea with jasmine flowers, and genmaicha is a Japanese green tea with toasted rice.
Tea
Tea is an aromatic beverage commonly prepared by pouring hot or boiling water over cured leaves of the tea plant, Camellia sinensis. After water, tea is the most widely consumed beverage in the world. It has a cooling, slightly bitter, astringent flavor, which many people enjoy.
The phrase "herbal tea" usually refers to infusions of fruit or herbs made without the tea plant, such as rosehip tea or chamomile tea. Alternative phrases for this are tisane or herbal infusion, both bearing an implied contrast with "tea" as it is construed here.
Although single estate teas are available, almost all teas in bags and most other teas sold in the West are blends. Blending may occur in the tea-planting area (as in the case of Assam), or teas from many areas may be blended. The aim of blending is to obtain better taste, higher price, or both, as a more expensive, better-tasting tea may cover the inferior taste of cheaper varieties.
Some teas are not pure varieties, but have been enhanced through additives or special processing. Tea is highly receptive to inclusion of various aromas; this may cause problems in processing, transportation, and storage, but also allows for the design of an almost endless range of scented and flavored variants, such as bergamot (Earl Grey), vanilla, and caramel.
FURTHER READING
Caffeine
Caffeine is a bitter, white crystalline xantine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants. It is most commonly consumed by humans in infusions extracted from the seed of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. Other sources include yerba maté, guarana berries, guayusa, and the yaupon holly.
In humans, caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness.
Percolation Percolation concerns the movement and filtering of fluids through porous materials.
In coffee percolation, soluble compounds leave the coffee grounds and join the water to form coffee. These soluble compounds are the chemical compounds that give coffee its color, taste, and aroma. Insoluble compounds remain within the coffee filter.
Decoction
Decoction is a method of extraction by boiling, of dissolved chemicals, from herbal or plant material, which may include stems, roots, bark and rhizomes. Decoction involves first mashing, and then boiling in water to extract oils, volatile organic compounds, and other chemical substances. Decoction can be used to make tisanes, teas, coffees, tinctures and similar solutions. Decoctions and infusions may produce liquids with differing chemical properties, as the temperature/preparation difference may result in more oil-soluble chemicals in decoctions vs infusions. The process can also be applied to meats and vegetables to prepare bouillon or stock.
A decoction is also the name for the resulting liquid. Although this method of extraction differs from infusion and percolation, the resultant liquids are often functionally similar.
Alkaloids
Alkaloids are a group of naturally occurring chemical compounds, that contain mostly basic nitrogen atoms. They are produced by a large variety of organisms, including bacteria, fungi, plants, and animals, and are part of the group of natural products.
Sources:
http://en.wikipedia.org/wiki/Infusion
http://en.wikipedia.org/wiki/Tisane
http://en.wikipedia.org/wiki/Tea
http://en.wikipedia.org/wiki/Caffeine
http://en.wikipedia.org/wiki/Percolation
http://en.wikipedia.org/wiki/Decoction
http://en.wikipedia.org/wiki/Alkaloid
Thursday, November 15, 2012
duty-free shop
Duty-free shops (or stores) are retail outlets that are exempt from the payment of certain local or national taxes and duties, on the requirement that the goods sold will be sold to travelers who will take them out of the country. Which products can be sold duty-free vary by jurisdiction, as well as how they can be sold, and the process of calculating the duty or refunding the duty component.
However, some countries impose duty on goods brought into the country, though they had been bought duty-free in another country, or when the value or quantity of such goods exceed an allowed limit. Duty-free shops are often found in the international zone of international airports and sea ports, but goods can be also bought duty-free aboard airplanes and passenger ships. They are not as commonly available for road or train travelers, although several border crossings between the United States and Canada have duty-free shops for car travelers.
Duty-free outlets were abolished for intra-EU travelers in 1999, but are retained for travelers whose final destination is outside the EU. They also sell to intra-EU travelers but with appropriate taxes. Some special member state territories such as Åland, Livigno, and the Canary Islands, are within the EU but outside the EU tax union, and thus still continue duty-free sales for all travelers.
Sources:
http://en.wikipedia.org/wiki/Duty-free_shop
However, some countries impose duty on goods brought into the country, though they had been bought duty-free in another country, or when the value or quantity of such goods exceed an allowed limit. Duty-free shops are often found in the international zone of international airports and sea ports, but goods can be also bought duty-free aboard airplanes and passenger ships. They are not as commonly available for road or train travelers, although several border crossings between the United States and Canada have duty-free shops for car travelers.
Duty-free outlets were abolished for intra-EU travelers in 1999, but are retained for travelers whose final destination is outside the EU. They also sell to intra-EU travelers but with appropriate taxes. Some special member state territories such as Åland, Livigno, and the Canary Islands, are within the EU but outside the EU tax union, and thus still continue duty-free sales for all travelers.
Sources:
http://en.wikipedia.org/wiki/Duty-free_shop
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