Thursday, December 25, 2008

Human languages

Human languages are usually referred to as natural languages, and the science of studying them falls under the purview of linguistics. A common progression for natural languages is that they are considered to be first spoken, then written, and then an understanding and explanation of their grammar is attempted.

Languages live, die, move from place to place, and change with time. Any language that ceases to change or develop is categorized as a dead language. Conversely, any language that is in a continuous state of change is known as a living language or modern language.

Making a principled distinction between one language and another is usually impossible. For instance, there are a few dialects of German similar to some dialects of Dutch. The transition between languages within the same language family is sometimes gradual (see dialect continuum).

Some like to make parallels with biology, where it is not possible to make a well-defined distinction between one species and the next. In either case, the ultimate difficulty may stem from the interactions between languages and populations. (See Dialect or August Schleicher for a longer discussion.)

The concepts of Ausbausprache, Abstandsprache and Dachsprache are used to make finer distinctions about the degrees of difference between languages or dialects.

Monday, December 15, 2008


Genetics (from Ancient Greek genetikos, “genitive” and that from genesis, “origin”), a discipline of biology, is the science of heredity and variation in living organisms.The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the process of inheritance, only began with the work of Gregor Mendel in the mid-nineteenth century. Although he did not know the physical basis for heredity, Mendel observed that organisms inherit traits in a discrete manner—these basic units of inheritance are now called genes.
DNA, the molecular basis for inheritance. Each strand of DNA is a chain of nucleotides, matching each other in the center to form what look like rungs on a twisted ladder.

Genes correspond to regions within DNA, a molecule composed of a chain of four different types of nucleotides—the sequence of these nucleotides is the genetic information organisms inherit. DNA naturally occurs in a double stranded form, with nucleotides on each strand complementary to each other. Each strand can act as a template for creating a new partner strand—this is the physical method for making copies of genes that can be inherited.

The sequence of nucleotides in a gene is translated by cells to produce a chain of amino acids, creating proteins—the order of amino acids in a protein corresponds to the order of nucleotides in the gene. This is known as the genetic code. The amino acids in a protein determine how it folds into a three-dimensional shape; this structure is, in turn, responsible for the protein's function. Proteins carry out almost all the functions needed for cells to live. A change to the DNA in a gene can change a protein's amino acids, changing its shape and function: this can have a dramatic effect in the cell and on the organism as a whole.

Wednesday, December 03, 2008

Grain milk

Grain milk is a milk substitute made from fermented grain or from flour. Grain milk can be made from oats, spelt, rice, rye, einkorn wheat or quinoa.

Grain milk looks very similar to cow's milk. It has a lower protein content and a higher carbohydrate content than cow's milk. Just as cow's milk is often fortified with Vitamin D, which it naturally lacks, grain milks may have calcium and some vitamins (especially B12) added to them.

Grain milk is low in saturated fat and contains no lactose, which is beneficial for those who are lactose intolerant. Grain milk also lacks milk protein, making it suitable for vegans and people with milk allergies.

Flavored grain milk can come in plain, vanilla, chocolate or a variety of other flavors. Like unflavored grain milk, it is often available with added nutrients. There are also grain milk cream and desserts available.

Friday, November 28, 2008


In the area of horticulture, Defra has policy responsibility for work on horticultural production and marketing, potatoes and hops. Along with other UK Agriculture Departments, Defra administers schemes for growers, including the Producer Organisation (Fresh Fruit and Vegetables) Aid Scheme.Growers may also be eligible for payments under the Single Payment Scheme.

Defra's horticultural policy responsibilities extend to the following EU regimes:
* fresh and processed fruit and vegetables and bananas
* flowers and plants
* hops

Part of this responsibility includes attending EU Management Committees. These are meetings attended by EU Member States whose responsibility it is to give an opinion on proposals made by the Commission for the management of the regimes. Further information on Management Committees can be found on the Europa website.Defra commissions a variety of research which has relevance to the industry. Defra also sponsors the National Fruit Collection at Brogdale in Kent.

Wednesday, November 19, 2008


Tonicity is a measure of blood capacity or effective osmolality in cell biology. Osmolality and osmolarity are properties of a particular solution, independent of any membrane. Tonicity is the base measurment for complex compounds with provides immunity to the body, and is equal to the sum of the concentrations of the solutes which have the capacity to exert an osmotic force across that membrane. Tonicity, also, depends on solute permemability (permeant solutes do not affect tonicity; impermeant solutes do affect tonicity). Tonicity is generally classified in three ranges; hypertonicity, hypotonicity and isotonicity. Hypertonic, isotonic and hypotonic solutions are defined in reference to a cell membrane by comparing the tonicity of the solution with the tonicity within the cell

Wednesday, November 12, 2008

Inner planet Venus

Venus (0.7 AU) is close in size to Earth, (0.815 Earth masses) and like Earth, has a thick silicate mantle around an iron core, a substantial atmosphere and evidence of internal geological activity. However, it is much drier than Earth and its atmosphere is ninety times as dense. Venus has no natural satellites. It is the hottest planet, with surface temperatures over 400 °C, most likely due to the amount of greenhouse gases in the atmosphere. No definitive evidence of current geological activity has been detected on Venus, but it has no magnetic field that would prevent depletion of its substantial atmosphere, which suggests that its atmosphere is regularly replenished by volcanic eruptions.

Monday, November 03, 2008

OpenGL 2.1

OpenGL 2.1 was released on August 2, 2006 and is backward compatible with all prior OpenGL versions. OpenGL 2.1 incorporates the following functionality:

  • Shading Language revision 1.20 (GLSL)
  • to specify and query non-square matrix uniforms for use with the OpenGL Shading Language
  • Pixel buffer objects for efficient image transfers to and from buffer objects for commands such as glTexImage2D and glReadPixels.

This functionality corresponds to the ARB_pixel_buffer_object extension.

  • sRGB texture formats.

This functionality corresponds to the EXT_texture_sRGB extension.

Thursday, October 30, 2008


Cognition is a concept used in different ways by different disciplines, but is generally accepted to mean the process of awareness or thought. For example, in psychology, it refers to an information processing view of an individual's psychological functions. Other interpretations of the meaning of cognition link it to the development of concepts; individual minds, groups, organizations, and even larger coalitions of entities, can be modelled as societies which cooperate to form concepts. The autonomous elements of each 'society' would have the opportunity to demonstrate emergent behavior in the face of some crisis or opportunity. Cognition can also be interpreted as "understanding and trying to make sense of the world".

Tuesday, October 21, 2008

Steel lattice

The steel lattice is the most widespread form of construction. It provides great strength, low wind resistance and economy in the use of materials. Such structures are usually triangular or square in cross-section.

When built as a stayed mast, usually the whole mast is parallel-sided. One exception is the Blaw-Knox type.

When built as a tower, the structure may be parallel-sided or taper over part or all of its height. When constructed of several sections which taper exponentially with height, in the manner of the Eiffel Tower, the tower is said to be an Eiffelized one. The Crystal Palace tower in London is an example.

Sunday, October 12, 2008

Single Message Authorisation/Clearing

Some financial networks operate a single message solution, in which a transaction is authorised and cleared via the same message.

A transaction will be authorised via a pre-authorisation step, where the merchant requests the issuer to reserve an amount on the cardholder's account for a specific time, followed by completion, where the merchant requests an amount blocked earlier with a pre-authorisation. This transaction flow in two steps is often used in businesses such as hotels and car rental where the final amount is not known, and the pre-authorisation is made based on an estimated amount. Completion may form part of a settlement process, typically performed at the end of the day when the day's completed transactions are submitted. All these messages will be sent "on-line" from the merchant acquirer to the issuing bank.

Monday, September 29, 2008

Bluetooth 1.2

  • Faster Connection and Discovery
  • Adaptive frequency-hopping spread spectrum (AFH), which improves resistance to radio frequency interference by avoiding the use of crowded frequencies in the hopping sequence.
  • Higher transmission speeds in practice, up to 721 kbit/s, as in 1.1.
  • Extended Synchronous Connections (eSCO), which improve voice quality of audio links by allowing retransmissions of corrupted packets, and may optionally increase audio latency to provide better support for concurrent data transfer.
  • Host Controller Interface (HCI) support for three-wire UART.
  • Ratified as IEEE Standard 802.15.1-2005.

Tuesday, September 23, 2008


The next major advance in "beam based" navigation system was the use of two signals that varied not in sound, but in phase. In these systems, known as VHF omnidirectional range, or VOR, a single master signal is sent out continually from the station, and a highly directional second signal is sent out that varies in phase 30 times a second compared to the master. This signal is timed so that the phase varies as the secondary antenna spins, such that when the antenna is 90 degrees from north, the signal is 90 degrees out of phase of the master. By comparing the phase of the secondary signal to the master, the angle can be determined without any physical motion in the receiver. This angle is then displayed in the cockpit of the aircraft, and can be used to take a fix just like the earlier RDF systems, although it is, in theory, easier to use and more accurate.

Tuesday, September 16, 2008


Sight or vision is the ability of the brain and eye to detect electromagnetic waves within the visible range (light) interpreting the image as "sight." There is disagreement as to whether this constitutes one, two or three senses. Neuroanatomists generally regard it as two senses, given that different receptors are responsible for the perception of colour (the frequency of photons of light) and brightness (amplitude/intensity - number of photons of light). Some argue[citation needed] that stereopsis, the perception of depth, also constitutes a sense, but it is generally regarded as a cognitive (that is, post-sensory) function of brain to interpret sensory input and to derive new information. The inability to see is called blindness.

Monday, September 08, 2008

Notable paleontologists

History includes a number of prominent paleontologists. Fossils were systematically studied in the 11th century by the Persian naturalist, Ibn Sina (known as Avicenna in Europe), in The Book of Healing (1027), and by the Chinese naturalist, Shen Kuo (1031-1095). In particular, Ibn Sina's theory on fossils was accepted by most naturalists in medieval Europe and the medieval Near East by the 16th century.

The modern discipline of paleontology begins in the 19th century, when Charles Darwin collected fossils of South American mammals during his trip on the Beagle and examined petrified forests in Patagonia. Mary Anning was a notable early paleontologist. She found several landmark fossils, in her home town of Lyme Regis. Although self-taught, she collected and described them in a very systematic way. William Buckland, Richard Owen, Gideon Mantell, Georges Cuvier and Thomas Huxley were important early pioneers, in the field of paleontology. Thomas Jefferson took a keen interest in mammoth bones. Edward Drinker Cope and Othniel Charles Marsh waged a famously fierce competition known as the Bone Wars in the late 19th century that involved some questionable practices, but which significantly advanced the understanding of the natural history of North America and vertebrate paleontology. Professor Earl Douglass of the Carnegie University in Pittsburgh, Pennsylvania, opened the fossil quarry protected today by Dinosaur National Monument in Utah. Douglass' fossils are in several Natural History Museums. Meanwhile, Baron Franz Nopcsa, a pioneer paleobiologist, argued that dinosaurs might have been both warm-blooded and ancestral to birds.

Besides looking at mammal teeth and unearthing penguin skeletons, George Gaylord Simpson played a crucial role in bringing together ideas from biology, paleontology and genetics, to help create the 'Modern Synthesis' of evolutionary biology. His book "Tempo and Mode" is a classic in the field. Prominent names in invertebrate paleontology include Steven M. Stanley, Stephen Jay Gould, David Raup, Rousseau H. Flower and Jack Sepkoski, who have done much to expand our understanding of long-term patterns in the evolution of life on earth. Large names in the field of paleoanthropology include Louis, Mary and Richard Leakey, Raymond Dart, Robert Broom, C.K. 'Bob' Brain, Kenneth Oakley, Robert Ardrey and Tim White. In recent times, Mongolian paleontologist Rinchen Barsbold has done much to expand our understanding of dinosaur and bird evolution. Paul Sereno of the University of Chicago has made several important dinosaur finds in areas such as the Sahara, where fossil hunting has been uncommon.

Tuesday, September 02, 2008

Panic disorder

In panic disorder, a person suffers from brief attacks of intense terror and apprehension that cause trembling and shaking, confusion, dizziness, nausea, difficulty breathing, and feelings of impending doom or a situation that would be embarrassing. One who is often plagued by sudden bouts of intense anxiety might be said to be afflicted by this disorder. The American Psychiatric Association (2000) defines a panic attack as fear or discomfort that arises abruptly and peaks in 10 minutes or less, and can occasionally last hours.

Although panic attacks sometimes seem to occur out of nowhere, they generally happen after frightening experiences, prolonged stress, or even exercise. Many people who have panic attacks (especially their first one) think they are having a heart attack and often end up at the doctor or emergency room. Even if the tests all come back normal the person will still worry, with the physical manifestations of anxiety only reinforcing their fear that something is wrong with their body. Heightened awareness (hypervigilance) of any change in the normal function of the human body will be noticed and interpreted as a possible life threatening illness by an individual suffering from panic attacks.

Normal changes in heartbeat, such as when climbing a flight of stairs will be noticed by a panic sufferer and lead them to think something is wrong with their heart or they are about to have another panic attack. Some begin to worry excessively and even quit jobs or refuse to leave home to avoid future attacks. Panic disorder can be diagnosed when several apparently spontaneous attacks lead to a persistent concern about future attacks.

Monday, August 25, 2008

Protected mode and supervisor mode

Modern CPUs support something called dual mode operation. CPUs with this capability use two modes: protected mode and supervisor mode, which allow certain CPU functions to be controlled and affected only by the operating system kernel. Here, protected mode does not refer specifically to the 80286 (Intel's x86 16-bit microprocessor) CPU feature, although its protected mode is very similar to it. CPUs might have other modes similar to 80286 protected mode as well, such as the virtual 8086 mode of the 80386 (Intel's x86 32-bit microprocessor or i386).

However, the term is used here more generally in operating system theory to refer to all modes which limit the capabilities of programs running in that mode, providing things like virtual memory addressing and limiting access to hardware in a manner determined by a program running in supervisor mode. Similar modes have existed in supercomputers, minicomputers, and mainframes as they are essential to fully supporting UNIX-like multi-user operating systems.

When a computer first starts up, it is automatically running in supervisor mode. The first few programs to run on the computer, being the BIOS, bootloader and the operating system have unlimited access to hardware. However when the operating system passes control to another program, it can place the CPU into protected mode.

In protected mode, programs may have access to a more limited set of the CPU's instructions. A user program may leave protected mode only by triggering an interrupt, causing control to be passed back to the kernel. In this way the operating system can maintain exclusive control over things like access to hardware and memory.

The term "protected mode resource" generally refers to one or more CPU registers, which contain information that the running program isn't allowed to alter. Attempts to alter these resources generally causes a switch to supervisor mode.

Tuesday, August 19, 2008

Foraging Foraging

Foraging Foraging theory is a branch of behavioral ecology that studies the foraging behavior of animals in response to the environment in which the animal lives. Foraging theory considers the foraging behavior of animals in reference to the payoff that an animal obtains from different foraging options. Foraging theory predicts that the foraging options that deliver the highest payoff, should be favored by foraging animals because it will have the highest fitness payoff.

Robert MacArthur, J M Emlen, and Eric Pianka, first proposed an optimal foraging theory in an independent paper in 1966. This theory argued that because of the key importance of successful foraging to an individual's survival, it should be possible to predict foraging behavior by using decision theory to determine the behavior that would be shown by an "optimal forager" - one with perfect knowledge of what to do to maximize usable food intake. While the behavior of real animals inevitably departs from that of the optimal forager, optimal foraging theory has proved very useful in developing hypotheses for describing real foraging behavior. Departures from optimality often help to identify constraints either in the animal's behavioral or cognitive repertoire, or in the environment, that had not previously been suspected. With those constraints identified, foraging behavior often does approach the optimal pattern even if it is not identical to it.

Monday, August 11, 2008

Tagged Image File Format

Tagged Image File Format (abbreviated TIFF) is a file format for storing images, including photographs and line art. It is now under the control of Adobe Systems. Originally created by the company Aldus for use with what was then called "desktop publishing", the TIFF format is widely supported by image-manipulation applications, by publishing and page layout applications, by scanning, faxing, word processing, optical character recognition and other applications. Adobe Systems, which acquired Aldus, now holds the copyright to the TIFF specification. TIFF has not had a major update since 1992, though several Aldus/Adobe technical notes have been published with minor extensions to the format, and several specifications, including TIFF/EP, have been based on the TIFF 6.0 specification.

The TIFF is a flexible, adaptable file format for handling images and data within a single file, by including the header tags (size, definition, image-data arrangement, applied image compression) defining the image's geometry. For example, a TIFF can be a container file holding compressed JPEG and RLE (run-length encoding) images. A TIFF also can include a vector-based Clipping path (outlines, croppings, image frames). The ability to store image data in a lossless format makes the TIFF file a useful image archive, because, unlike standard JPEG files, the TIFF using lossless compression (or none) may be edited and re-saved without losing image compression; other TIFF options are layers and pages.

Although the currently accepted standard format, when the TIFF was introduced, its extensibility provoked compatibility problems. Programmers were free to specify new tags and options — but not every implemented program supported every tag created. Resultantly, the TIFF became the lowest common denominator image file. Today, the most TIFF images and readers remain based upon uncompressed 32-bit CMYK or 24-bit RGB images.

Monday, August 04, 2008

Eukaryotic cells

Eukaryotic cells consist of cell membrane, organelles which represent the functional components for storage, excretion, digestion and nucleus (centre of the cell), it contains all the vital information needed by the cell or the whole organism to function, grow and reproduce.
Eukaryotic cells are found in humans, plants and animals, also algae, and protozoa. Eukaryotic cells have both a cellular membrane and a nuclear membrane. Eukaryotic genome is more complex than that of prokaryotes and distributed among multiple chromosomes.

  • Mitosis: The division of the parent nucleus into two daughter nuclei, separating the duplicated genome into two sets, each identical to the parent cell's genome.
  • Cytokinesis: The pinching and division of the cell membrane and cytoplasm, separating the recently divided nuclei, the organelles, and other cellular components.
  • Meiosis: The division of the nucleus in sex cells that reduces the diploid number of chromosomes to a haploid number in order to facilitate sexual reproduction.
Examples of cell division in multicellular eukariotic organisms include repair, growth, and development. An injury or wound is healed when the cells exposed by the injury divide at an excellerated rate until they come into contact with other cells. After this the cells return to a more typical division rate. Cell division causes an organism to grow as long as the rate of cell division exceeds normal cell death. As cells divide and become more numerous they are located in more diverse physical and chemical environments. These variations in local conditions influence the cells to alter gene expression causing the cells to differentiate and become more specialized allowing an organism to develop

Monday, July 28, 2008


Many advocates of capitalism agreed with Marx's analysis of capitalism as a process of continual change, but, unlike Marx, believed and hoped that capitalism would essentially go on forever.

Thus, by the beginning of the 20th century, two opposing schools of thought - Marxism and liberalism - believed in the possibility and the desirability of continual change and improvement. Marxists strongly opposed capitalism and the liberals strongly supported it, but the one concept they could both agree on was modernism.

Modernism is a trend of thought which affirms the power of human beings to make, improve and reshape their society, with the aid of scientific knowledge, technology and practical experimentation. It reaches its extreme limits with the Russian Revolution and the third Chinese revolution, inspired by Marxist ideology. Here, people claimed such confidence in the ability to change their world for the better, which they thought that, in a relatively short time, largely illiterate peasants could begin to build a just, egalitarian and socialist order in a conscious way, armed with science and technology.

Monday, July 21, 2008


An alphabet is a small set of symbols, each of which roughly represents or historically represented a phoneme of the language. In a perfectly phonological alphabet, the phonemes and letters would correspond perfectly in two directions: a writer could predict the spelling of a word given its pronunciation, and a speaker could predict the pronunciation of a word given its spelling. As languages often evolve independently of their writing systems, and writing systems have been borrowed for languages they were not designed for, the degree to which letters of an alphabet correspond to phonemes of a language varies greatly from one language to another and even within a single language.

In most of the alphabets of the Mid-East, only consonants are indicated, or vowels may be indicated with optional diacritics. Such systems are called abjads. In most of the alphabets of India and Southeast Asia, vowels are indicated through diacritics or modification of the shape of the consonant. These are called abugidas. Some abugidas, such as Ethiopic and Cree, are learned by children as syllabaries, and so are often called "syllabics". However, unlike true syllabaries, there is not an independent glyph for each syllable.

Sometimes the term "alphabet" is restricted to systems with separate letters for consonants and vowels, such as the Latin alphabet. Because of this use, Greek is often considered to be the first alphabet.

Tuesday, July 15, 2008

Breeding stock

"Breeding stock" is a term used to describe a group of animals used for purpose of planned breeding. When individuals are looking to breed animals, they look for certain valuable traits in purebred stock for a certain purpose, or may intend to use some type of crossbreeding to produce a new type of stock with different, and presumably superior abilities in a given area of endeavor.

For example, to breed chickens, a typical breeder intends to receive eggs, meat, and new, young birds for further reproduction. Thus the breeder has to study different breeds and types of chickens and analyze what can be expected from a certain set of characteristics before he or she starts breeding them. Accordingly, when purchasing initial breeding stock, the breeder seeks a group of birds that will most closely fit the purpose intended.

Breeding stock

"Breeding stock" is a term used to describe a group of animals used for purpose of planned breeding. When individuals are looking to breed animals, they look for certain valuable traits in purebred stock for a certain purpose, or may intend to use some type of crossbreeding to produce a new type of stock with different, and presumably superior abilities in a given area of endeavor.

For example, to breed chickens, a typical breeder intends to receive eggs, meat, and new, young birds for further reproduction. Thus the breeder has to study different breeds and types of chickens and analyze what can be expected from a certain set of characteristics before he or she starts breeding them. Accordingly, when purchasing initial breeding stock, the breeder seeks a group of birds that will most closely fit the purpose intended.

Sunday, July 06, 2008


The sword is an evolution of the knife. Its name literally means “hurting tool” from the Old German “Swert”. It is one of the most universally recognised ancient weapons and has taken many forms across many different countries. It is used to both slash and stab in much the same way a knife does.

During the Middle Ages, most European swords had double edged straight blades made for both slashing and stabbing. Examples of these swords include the one handed arming sword and the two handed longsword. Curved swords such as the falchion existed in Europe during the Middle Ages but were not as prominent as the straight ones.

The primary sword used in Japan is the Katana, which has a curved blade that is short in comparison to the Rapiers or Longswords of Europe. It is known for its sharpness and formed an integral component of the culture of the Samurai. The weapon remained in use even as other weapons of the time were neglected. It eventually disappeared after The Satsuma Rebellion. The weapon had a renaissance during World War II where it was used by Japanese soldiers in the Pacific theatre. Although the katana is seen as the primary sword of the Samurai, many other types of swords were used by the Samurai. These include the uchigatana, the odachi, the nodachi and the tachi

In its use by Roman forces the sword was relatively short, but effective in combination with a shield, since the soldier could block a downward slash with his shield and then thrust from below and upward into the midsection of an opponent. This technique was extremely effective when in a closed formation. Examples of the successful use of this technique include the defeat of the outnumbering forces of Queen Boudica in the Battle of Watling Street in the year 60 CE.

The sword was used differently in more modern Europe. It was a very long, cylindrical, and narrow blade with no edge and was used to stab rather than slash. It is the source of fencing as we know it today. Most middle and upper class men would be trained in fencing with the smallsword as it was the primary duelling weapon.

The Scimitar was a curved but short blade used in the Middle East. Its name is derived from the Persian shashimir. The weapon is vaguely similar to the European Sabre in that it is a curved slashing weapon.

The sword fell into disuse after Europe discovered gunpowder and related projectile weapons. Duelling and fencing for social purposes continued well after the invention of the handgun. Duelling fell into disuse even before the end of the 20th century and with it the sword ceased to be used in any practical sense.

Sunday, June 29, 2008


Morphogenesis (from the Greek morphê shape and genesis creation),( literally, "beginning of the shape"), is one of three fundamental aspects of developmental biology along with the control of cell growth and cellular differentiation. Morphogenesis is concerned with the shapes of tissues, organs and entire organisms and the positions of the various specialized cell types. Cell growth and differentiation can take place in cell culture or inside of tumor cell masses without the normal morphogenesis that is seen in an intact organism. The study of morphogenesis involves an attempt to understand the processes that control the organized spatial distribution of cells that arises during the embryonic development of an organism and that give rise to the characteristic forms of tissues, organs, and overall body anatomy. In the human embryo, the change from a cluster of nearly identical cells at the blastula stage to a post-gastrulation embryo with structured tissues and organs is controlled by the genetic "program" and can be modified by environmental factors. The term morphogenesis can also be used to describe the development of unicellular life forms that do not have an embryonic stage in their life cycle, or to refer to the evolution of a body structure within a taxonomic group. Morphogenetic responses may be induced in organisms by hormones, by environmental chemicals ranging from substances produced by other organisms to toxic chemicals or radionuclides released as pollutants, and other plants, or by mechanical stresses induced by spatial patterning of the cells.

Sunday, June 22, 2008


Mitosis is the process by which a cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two daughter cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of the cell cycle - the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell.

Mitosis occurs exclusively in eukaryotic cells, but occurs in different ways in different species. For example, animals undergo an "open" mitosis, where the nuclear envelope breaks down before the chromosomes separate, while fungi such as Aspergillus nidulans and Saccharomyces cerevisiae (yeast) undergo a "closed" mitosis, where chromosomes divide within an intact cell nucleus. Prokaryotic cells, which lack a nucleus, divide by a process called binary fission.
The process of mitosis is complex and highly regulated. The sequence of events is divided into phases, corresponding to the completion of one set of activities and the start of the next. These stages are prophase, prometaphase, metaphase, anaphase and telophase. During the process of mitosis the pairs of chromosomes condense and attach to fibers that pull the sister chromatids to opposite sides of the cell. The cell then divides in cytokinesis, to produce two identical daughter cells.

Because cytokinesis usually occurs in conjunction with mitosis, "mitosis" is often used interchangeably with "mitotic phase". However, there are many cells where mitosis and cytokinesis occur separately, forming single cells with multiple nuclei. This occurs most notably among the fungi and slime moulds, but is found in various different groups. Even in animals, cytokinesis and mitosis may occur independently, for instance during certain stages of fruit fly embryonic development. Errors in mitosis can either kill a cell through apoptosis or cause mutations that may lead to cancer.

Sunday, June 15, 2008


The first integrated circuits contained only a few transistors. Called "Small-Scale Integration" (SSI), they used circuits containing transistors numbering in the tens.

SSI circuits were crucial to early aerospace projects, and vice-versa. Both the Minuteman missile and Apollo program needed lightweight digital computers for their inertial guidance systems; the Apollo guidance computer led and motivated the integrated-circuit technology, while the Minuteman missile forced it into mass-production.

These programs purchased almost all of the available integrated circuits from 1960 through 1963, and almost alone provided the demand that funded the production improvements to get the production costs from $1000/circuit (in 1960 dollars) to merely $25/circuit (in 1963 dollars).[citation needed] They began to appear in consumer products at the turn of the decade, a typical application being FM inter-carrier sound processing in television receivers.
The next step in the development of integrated circuits, taken in the late 1960s, introduced devices which contained hundreds of transistors on each chip, called "Medium-Scale Integration" (MSI).

They were attractive economically because while they cost little more to produce than SSI devices, they allowed more complex systems to be produced using smaller circuit boards, less assembly work (because of fewer separate components), and a number of other advantages.

Further development, driven by the same economic factors, led to "Large-Scale Integration" (LSI) in the mid 1970s, with tens of thousands of transistors per chip.
Integrated circuits such as 1K-bit RAMs, calculator chips, and the first microprocessors, that began to be manufactured in moderate quantities in the early 1970s, had under 4000 transistors. True LSI circuits, approaching 10000 transistors, began to be produced around 1974, for computer main memories and second-generation microprocessors.

Sunday, June 08, 2008

Trance production

Trance employs a 4/4 time signature, a tempo of 130 to 160 BPM, and 32 beat phrases, somewhat faster than house music but usually not as fast as rave music. Psychedelic Trance is sometimes faster and earlier tracks were sometimes slower. A kick drum is placed on every downbeat and a regular open hi-hat is often placed on the upbeat. Some simple extra percussive elements are usually added, and major transitions, builds or climaxes are often foreshadowed by lengthy 'snare rolls' - a quick succession of equally spaced snare drum hits that builds in volume towards the end of a measure or phrase.

Synthesizers form the central elements of most trance tracks, with simple sawtooth-based sounds used both for short pizzicato elements and for long, sweeping string sounds. As with other genres of electronic music, important synthesizers are the Roland TR-808, TR-909, and TB-303, which is the source of the "acid" sound. There are also several synthesizer sounds that are almost completely unique to its genre. One of these sounds is the "supersaw", a waveform was made famous by such classic trance synthesizers as the Roland JP-8000, the Novation Supernova, and the Korg MS2000. A technique called "gating" is often employed in creating lead sounds (turning the volume up and down rapidly in rhythm with the piece to create a stuttered, chopped sound). Rapid arpeggios and minor scales are common features. Trance tracks often use one central "hook" melody which runs through almost the entire song, repeating at intervals anywhere between 2 beats and several bars.

While many trance tracks contain no vocals at all, other tracks rely heavily on vocals, and thus a sub-genre has developed. The sound and quality of the production relies to a large degree upon the technology available. Vintage analog equipment still holds a place in the hearts of many producers and enthusiasts, with names such as Moog, Roland and Oberheim staples in the trance sound palette. However, the mainstream availability of digital technology has allowed a whole new group of producers to emerge because while top shelf digital (or analog modeling) synthesizers cost thousands of US dollars, high demand and a small supply of clean vintage analog synthesizers causes them to be extremely expensive.

Trance records are often heavily loaded with reverb and delay effects on the synthesizer sounds, vocals and often parts of the percussion section. This provides the tracks with the sense of vast space that trance producers tend to look for in order to achieve the genre's epic quality. Flangers, phasers and other effects are also commonly used at extreme settings - in trance there is no need for sounds to resemble any real-world instrument, and so producers have free rein.

Monday, June 02, 2008

Psychoactive mushrooms

Psilocybin mushrooms possess psychedelic properties. They are commonly known as "magic mushrooms" "mush" or "shrooms" and are available in smart shops in many parts of the world, though some countries have outlawed their sale. A number of other mushrooms are eaten for their psychoactive effects, such as fly agaric, which is used for shamanic purposes by tribes in northeast Siberia, Russia. They have also been used in the West to potentiate, or increase, religious experiences. Because of their psychoactive properties, some mushrooms have played a role in native medicine, where they have been used in an attempt to effect mental and physical healing, and to facilitate visionary states. One such ritual is the Velada ceremony. A practitioner of traditional mushroom use is the shaman and curandera (priest-healer) María Sabina.

Tuesday, May 27, 2008


A nomogram, nomograph, or abac is a graphical calculating device, a two-dimensional diagram designed to allow the approximate graphical computation of a function. Like a slide rule, it is a graphical analog computation device; and, like the slide rule, its accuracy is limited by the precision with which physical markings can be drawn, reproduced, viewed, and aligned. Most nomograms are used in applications where an approximate answer is appropriate and useful. Otherwise, the nomogram may be used to check an answer obtained from an exact calculation method.

The slide rule is intended to be a general-purpose device. Nomograms are usually designed to perform a specific calculation, with tables of values effectively built in to the construction of the scales.

Understanding the Context

Many different methods of communication are possible on the Internet; some use specific software and all involve text and/or graphics.

* Some activities take place in real-time while others allow for a delayed reply.

* Discussion areas may be public or exist for a particular group of people.

* Information can either be broadcast or targeted at a particular user.

As the technology develops, and users and providers become more proficient, the boundaries between the different Internet services are blurred. For example, email is used in chat rooms, web pages include discussion areas and newsgroups can have files attached.

Each Internet service has its own educational value, risks, and recommended ways of dealing with problems, and these are detailed in the following pages. They are not exhaustive and many apply across Internet services. Schools should consider the sum of the advice in these guidelines across all areas.

Thursday, May 22, 2008

Overview of the Click Thinking Pack

Schools and government initiatives are encouraging the educational use of the Internet right across the curriculum and young people are taking readily to this way of learning and communicating.

At the same time, the media tends to focus on the rare occasions when use of the Internet causes distress. The Scottish Executive believes that young people need to be protected and informed; and that those responsible for them, whether teachers, parents or other careers, should be aware of the issues involved.

Previous Scottish Executive Education Department (SEED) publications in this area have dealt with the need to protect pupils from misuse of computers (Information Ethics) and to understand copyright implications (Copyright and Ethics in a Digital Age).

This booklet focuses on personal safety and wellbeing. It attempts to clarify potential risks and to empower Internet users in schools so that they can keep themselves safe. Those who manage Scottish schools, and all teachers, whether responsible for a primary class or for teaching a subject, will find policy guidelines and background information which will prepare our pupils to take their safe and well-earned place in the Digital Age.

Much of the advice in these guidelines will be relevant to other Local Authority staff responsible for overseeing young people's use of the Internet (e.g. managers and staff in community education centers, residential homes for young people, libraries and other settings). These groups should take account of the messages about personal safety, and put into place the recommendations suitable for their setting.

Wednesday, May 07, 2008


CPSC Urges Bicyclists to Wear Helmets

CPSC Document #5002

Each year about 800 bicyclists are killed and more than half a million are treated in hospital emergency rooms. In recent years, almost two-thirds of the deaths and one-third of the injuries involved head and face injury. About one-half the injuries to children under the age of 10 involved the head or face. Helmets may reduce the risk of head injury to bicyclists by as much as 85 percent. Yet, only about 50 percent of bicyclists wear helmets.

The purpose of a helmet is to absorb the energy of an impact to minimize or prevent a head injury. Crushable, expanded polystyrene foam generally is used for this purpose.

A bicycle helmet should have a snug but comfortable fit on the rider's head. Some helmets are available with several different thicknesses of internal padding to custom fit the helmet to the user. If a parent is buying a helmet for a child, the CPSC recommends that the child accompany the parent so that the helmet can be tested for a good fit.

For a helmet to provide protection during impact, it must have a chin strap and buckle that will stay securely fastened. No combination of twisting or pulling should remove the helmet from the head or loosen the buckle on the strap. Children should be instructed to always wear the helmet level on the forehead, not tilted back. The chin strap should be adjusted correctly and firmly buckled.

Helmets manufactured after March 1999, are required by federal law to meet the CPSC standard. When purchasing a helmet, consumers are urged to examine the helmet and accompanying instructions and safety literature carefully. Consumers should also look for a label stating conformance with the CPSC standard.

Bicyclists should avoid riding at night. If you must ride at night, install and use front and rear lights on the bicycle and wear clothing with reflective tape or markings. These precautions are in addition to the reflectors that the CPSC requires to be on the front, rear, pedals, and wheels of bicycles.

Many bicycle-car crashes can be avoided by applying the rules of the road and by increasing attentiveness of cyclists and motorists. Bicyclists have a legal right to share the road, but they are often not noticed in traffic. Drivers should always keep an eye out for bicyclists, especially when turning, merging, changing lanes, or entering intersections.

Monday, April 28, 2008

All-Terrain Vehicle Safety

Too many ATV riders -- young and old -- are dying or experiencing life altering injuries from incidents involving ATVs. The U.S. Consumer Product Safety Commission (CPSC) recommends that all ATV riders follow the seven safety tips below every time they ride.

An estimated 740 people died in 2003* in incidents associated with ATVs. In addition, in 2004* there were an estimated 136,100 emergency room treated injuries associated with ATVs. About a third of all deaths and injuries involved victims under 16 years old. CPSC also reported that ridership has continued to grow, with 6.2 million 4-wheeled ATVs in use in 2003*.

The major ATV manufacturers agreed in Consent Decrees in 1988 and in subsequent voluntary action plans that they would not manufacture three-wheel ATVs; they would place engine size restrictions on ATVs sold for use by children under 16; and they would offer driver-training programs.

Children and young people under the age of 16 should not ride adult ATVs.

All ATV users should take a hands-on safety training course.

Always wear a helmet and safety gear such as boots and gloves while on an ATV.

Never drive an ATV on paved roads.

Never drive while under the influence of drugs or alcohol.

Never drive a youth or single-rider adult ATV with a passenger, and never ride these vehicles as a passenger.

There are some ATVs that are designed for two riders. Passengers on tandem ATVs should be at least 12 years old.

Monday, April 21, 2008

J-Hook Shaped Stake style (Anchor Types)

This style is used when holes are not pre-drilled into the ground shoes (bars) or rear ground shoe (bar) of the goal. Similar to the peg or stake style, this anchor is hammered, at an angle if possible, directly into the earth. The curved (top) portion of this anchor fits over the goal member to secure it to the ground (Figure 3.4). Typically, two to four stakes of this type are recommended (per goal), depending on stake structure, manufacturers specifications, weight of goal, and soil conditions. Stakes with larger diameters or textured surfaces have greater holding capacity.

Monday, April 14, 2008

Anchoring/Securing/Counterweighing Guidelines

A properly anchored/counterweighted movable soccer goal is much less likely to tip over. Remember to secure the goal to the ground (preferably at the rear of the goal), making sure the anchors are flush with the ground and clearly visible. It is IMPERATIVE that ALL movable soccer goals are always anchored properly (see Figure 2). There are several different ways to secure your soccer goal. The number and type of anchors to be used will depend on a number of factors, such as soil type, soil moisture content, and total goal weight.

Monday, April 07, 2008

Soccer Goal Injuries and Deaths

According to the 1994 National Soccer Participation Survey (Soccer Industry Council of America), over 16 million persons in the United States play soccer at least once a year. Seventy-four percent (over 12 million) of these persons are under the age of 18. Soccer ranks fourth in participation for those under 18, following basketball, volleyball, and softball and well ahead of baseball, which has an annual participation of 9.7 million.
There are approximately 225,000 to 500,000 soccer goals in the United States. Many of these soccer goals are unsafe because they are unstable and are either unanchored or not properly anchored or counter-balanced. These movable soccer goals pose an unnecessary risk of tip over to children who climb on goals (or nets) or hang from the crossbar.
The CPSC knows of four deaths in 1990 alone and at least 21 deaths during the past 16 years (1979-1994) associated with movable soccer goals. In addition, an estimated 120 injuries involving falling goals were treated each year in U.S. hospital emergency rooms during the period 1989 through 1993. Many of the serious incidents occurred when the soccer goals tipped over onto the victim. Almost all of the goals involved in these tip over appeared to be home-made by high school shop classes, custodial members, or local welders, not professionally manufactured. These home-made goals are often very heavy and unstable.
The majority of movable soccer goals are constructed of metal, typically weighing 150-500 pounds. The serious injuries and deaths are a result of blunt force trauma to the head, neck, chest, and limbs of the victims. In most cases this occurred when the goal tipped or was accidentally tipped onto the victim. In one case an 8-year-old child was fatally injured when the movable soccer goal he was climbing tipped over and struck him on the head. In another case, a 20-year-old male died from a massive head trauma when he pulled a goal down on himself while attempting to do chin-ups. In a third case, while attempting to tighten a net to its goal post, the victim’s father lifted the back base of the goal causing it to tip over striking his 3-year-old child on the head, causing a fatal injury.
High winds can also cause movable soccer goals to fall over. For example, a 9-year-old was fatally injured when a goal was tipped over by a gust of wind. In another incident, a 19-year-old goalie suffered stress fractures to both legs when the soccer goal was blown on top of her.

Sunday, March 30, 2008

B.C.-Canada Place officially closes doors

Monday, March 20, 2006 marks the official close of British Columbia-Canada Place, one of the most successful attractions of the 2006 Torino Olympic and Paralympic Winter Games.

Over the course of the 2006 Olympic and Paralympic Winter Games, British Columbia-Canada Place drew more than 100,000 visitors and journalists. These visitors were able to experience first hand the province’s culture, heritage, natural beauty and bustling cities. Also, more than 80 British Columbia businesses were able to connect with an international audience and showcase some of B.C.’s best products and services.

B.C.-Canada Place will be a legacy to the people of Torino. The official transfer took place in a ceremony yesterday, with Torino Mayor Sergio Chiamparino accepting a ceremonial key to the building.

“This generous gift from British Columbia will be a constant reminder of our friends in Canada and the celebrations that took place in our city during the 2006 Winter Games,” says Mayor Chiamparino. “We are honored to have this permanent B.C. presence in our city.”

Monday, March 24, 2008

Kent Kickin' Mini-Scooters

Kent is recalling about 90,000 scooters. The scooter handles can unexpectedly come out of the steering column if the clamp holding them in is not tight, causing the rider to lose control, fall and possibly suffer injuries.
Kent has received four reports of the handles coming out, resulting in four children suffering injuries, including broken arms, a broken wrist, bruises, abrasions and a cracked tooth.
These are Kickin' Mini-Scooters made of chrome-plated steel. A vertical decal on the steering column reads "KICKIN' MINI SCOOTER." The scooter's black plastic platform measures about 15 inches long, and it has 4-inch translucent in-line style wheels. "KENT" and "MADE IN CHINA" are written on the lower part of the steering column. The scooters were sold with black backpacks embroidered in white with the word "Kickin."
Toys R us stores nationwide sold the Kent scooters from May 2000 through September 2000 for about $60.
Consumers should stop riding these Kent scooters immediately, and call Kent International to receive a free replacement handlebar with pins to secure the handlebars. For more information, call Kent International at (800) 451-KENT (5368) between 8 a.m. and 5 p.m. ET Monday through Friday.
Kent has sold other models to Toys R Us such as the Street Craze, the Street Racer and Scoot that are NOT part of this recall. Scooters that Kent sold to Wal Mart, Meijer's, Target and AAFES are also NOT part of this recall.

Monday, March 17, 2008

Trampoline Safety Alert

The U. S. Consumer Product Safety Commission (CPSC) wants you and your family to be safe when using trampolines. The CPSC estimates that in 2001 there were 91,870 hospital emergency room-treated injuries associated with trampolines. About 93 percent of the victims were under 15 years of age, and 11 percent were under 5 years of age. Since 1990, CPSC has received reports of 6 deaths of children under age 15 involving trampolines. Injuries and deaths were caused by:

* Colliding with another person on the trampoline.
* Landing improperly while jumping or doing stunts on the trampoline.
* Falling or jumping off the trampoline.
* Falling on the trampoline springs or frame.
Most of the trampolines associated with injuries were at private homes.
Here are the steps you can take to help prevent serious trampoline injuries, especially paralysis, fractures, sprains, and bruises:

* Allow only one person on the trampoline at a time.
* Do not attempt or allow somersaults because landing on the head or neck can cause paralysis.
* Do not use the trampoline without shock-absorbing pads that completely cover its springs, hooks, and frame.
* Place the trampoline away from structures, trees, and other play areas.
* No child under 6 years of age should use a full-size trampoline. Do not use a ladder with the trampoline because it provides unsupervised access by small children.
* Always supervise children who use a trampoline.
* Trampoline enclosures can help prevent injuries from falls off trampolines.

Monday, March 10, 2008


In a computer CPU, an accumulator is a register in which intermediary arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to main memory, possibly only to be read right back again for use in the next operation. Access to main memory is slower than access to a register like the accumulator because the technology used for the huge main memory is slower (but cheaper) than that used for a register.

The canonical example for accumulator use is adding a list of numbers. The accumulator is initially set to zero, then each number in spin is added to the value in the accumulator. Only when all numbers have been added is the result seized in the accumulator written to main memory or to another, non-accumulator, CPU register.

Monday, February 25, 2008


Mercury (pronounced /'m?kj??ri/) is the deepest and smallest planet in the solar system, orbiting the Sun once every 88 days. Mercury is bright when viewed from Earth, range from -2.0 to 5.5 in apparent magnitude, but is not easily seen as its greatest angular separation from the Sun (greatest elongation) is only 28.3°: It can only be seen in morning and evening twilight. Comparatively little is known about it; the first of two spacecraft to move toward Mercury was Mariner 10 from 1974 to 1975, which mapped only about 45% of the planet’s surface. The second was the MESSENGER spacecraft, which mapped another 30% of the planet throughout its flyby of January 14, 2008. MESSENGER will make two more passes by Mercury, follow by orbital insertion in 2011, and will survey and map the whole planet.

Tuesday, February 19, 2008


The grapefruit is a subtropical citrus tree grown for its fruit which was initially named the "forbidden fruit" of Barbados.
These evergreen trees are frequently found at around 5-6 m tall, even though they can reach 13-15 m. The leaves are shady green, long up to 150 mm and thin. It produces 5 cm fair four-petalled flowers. The fruit is yellow-skinned, mainly oblate and ranges in diameter from 10-15 cm. The flesh is segmented and acidic, unreliable in color depending on the cultivars, which include white, pink and red pulps of varying sweetness. The 1929 US Ruby Red (of the Red blush variety) has the first grapefruit patent.
The fruit has only become popular from the late 19th century; before that it was only grown as a decorative plant. The US quickly became a major creation of fruit, with orchards in Florida, Texas, Arizona, and California. In Spanish, the crop is known as toronja or pomelo.

Monday, February 11, 2008

What is Spamdexing?

Spamdexing has frequent methods, such as repeating unrelated phrases, to control the relevancy or prominence of resources indexed by a search engine, in a manner inconsistent with the idea of the indexing system. Some consider it to be a part of search engine optimization; though there are numerous search engine optimization methods that get better the quality and exterior of the content of web sites and serve content useful to many users. Search engines use a variety of algorithms to end relevancy ranking. Some of these contain determining whether the search term appears in the META keywords tag, others whether the search term appear in the body text or URL of a web page. Many search engines test out for instances of spamdexing and will remove believe pages from their indexes. In addition people working for a search-engine organization can quickly block the results-listing from entire websites that use spamdexing, perhaps alert by user objects of false matches. The rise of spamdexing in the mid-1990s made the majority important search engines of the time less useful.

Monday, February 04, 2008


Soil, comprising the pedosphere, is located at the border of the lithosphere with the biosphere, atmosphere, and hydrosphere. It consists of mineral, organic matter, as well as living organisms. Soil formation, or pedogenesis, is the combined effect of physical, chemical, biological, and anthropogenic process on soil parent material ensuing in the configuration of soil horizons.
Soil is our most important natural resources because of its position in the landscape and its dynamic, physical, chemical, and biologic functions. While the general concept of soil is well recognized, the definition of soil varies, according to the viewpoint of the discipline or occupation by means of soil as a resource.

Monday, January 28, 2008


Rotogravure (roto or gravure for short) is a type of intaglio printing process, in that it involves etching the image onto an image carrier. In gravure printing, the image is stamped onto a copper cylinder because, like offset and flexography, it uses a rotary printing press. The vast mass of gravure presses print on reels of paper, quite than sheets of paper. Sheetfed gravure is a modest, specialty market. Rotary gravure presses are the best and widest presses in operation, printing everything from narrow labels to 12-feet-wide rolls of vinyl flooring. Additional operations may be in-line with a gravure press, such as saddle stitching services for magazine/brochure work.

Monday, January 21, 2008

Multiple fruit

A multiple fruit is one fashioned from a cluster of flowers called an inflorescence. Each flower produces a fruit, but these grown-up into a single mass Examples are the pineapple, edible fig, mulberry, osage-orange, and breadfruit.

In the photograph on the right, stages of flowering and fruit development in the noni or Indian mulberry (Morinda citrifolia) can be experiential on a single branch. First an inflorescence of white flowers called a cranium is produced. After fertilization, each flower develops into a drupe, and as the drupes make bigger, they become connate (merge) into a multiple fleshy fruit called a syncarpet.

There are also many dry multiple fruits, e.g.

Tuliptree, multiple of samaras.
Sweet gum, multiple of capsules.
Sycamore and teasel, multiple of achenes.
Magnolia, multiple of follicles.

Wednesday, January 16, 2008


A batsman in the sport of cricket is, depending on context: Any players will perform for batting. A player whose expert in the game is batting. During the play of a cricket match, two members of the batting team are on the field, although their team-mates wait off the field. Those two players are the existing batsmen. Each batsman stands near one of the two wickets also end of the cricket pitch near the centre of the ground.

The two batsmen have different roles:

The striker stands in front of the wicket nearest him and attempts to protect it from balls bowled by the opposing bowler from the other wicket. The non-striker stands stopped near the bowler's wicket. While protecting his wicket, the striker may also hit the ball into the field and attempt to run to the opposite wicket, exchanging places with the non-striker. This score a run, the two batsmen may continue to exchange places, scoring additional runs, until members of the fielding team gather and return the ball to either wicket.

Monday, January 07, 2008


Pawpaw (Asimina) also known as a prairie banana or Ozark banana, is a genus of eight or nine species of small trees with large leaves and fruit, native to southeastern North America. The genus includes the largest edible fruit native to North America. They are understorey trees of deep fertile bottomland soils. The name, also spelled paw paw, paw-paw, and papaw, probably derives from the Spanish papaya, perhaps due to the superficial similarity of their fruit. Pawpaw is in the same family Annonaceae as the custard-apple, cherimoya, sweetsop, and soursop, and it is the only member of that family not confined to the tropics.

The pawpaws are shrubs or small trees, reaching heights of 2 to 12 m tall. The leaves are alternate, simple ovate, entire, 20 to 35 cm long and 10 to 15 cm broad. The northern, cold-tolerant common pawpaw is deciduous, while the southern species are often evergreen. The fetid flowers are produced singly or in clusters of up to eight together; they are large, 4 to 6 cm across, perfect, with six sepals and petals (three large outer petals, three smaller inner petals). The petal color varies from white to purple or red-brown. Pollinated by scavenging carrion flies and beetles, the flowers emit a weak scent which attracts few pollinators, thus limiting fruit production. Larger growers sometimes locate rotting meat near the trees at bloom time to increase the number of blowflies. Asimina triloba is the only larval host of the Zebra Swallowtail Butterfly.

The fruit is a large edible berry, 5 to 16 cm long and 3 to 7 cm broad, weighing from 20 to 500 g, with numerous seeds; it is green when unripe, maturing to yellow or brown. It has a flavor somewhat similar to both banana and mango, varying significantly by cultivar, and has more protein than most fruits.


The earliest documentation of pawpaws is in the 1541 report of the de Soto expedition, who found Native Americans cultivating it east of the Mississippi River. The Lewis and Clark Expedition depended and sometimes subsisted on pawpaws during their travels. Chilled pawpaw fruit was a favorite dessert of George Washington, and Thomas Jefferson was certainly familiar with it as he planted it at Monticello.

Thursday, January 03, 2008


Polymer is a substance collected of molecules with large molecular mass collected of repeating structural units, or monomers, connected by covalent chemical bonds. The word is resulting from the Greek, πολυ, polu, "many"; and μέρος, meros, "part". Well known examples of polymers contain plastics, DNA and proteins.

While the term polymer in popular usage suggests "plastic", polymers consist of a large class of natural and synthetic materials with a variety of properties and purposes. Natural polymer materials such as shellac and amber have been in utilize for centuries. Biopolymers such as proteins (for example hair, skin and division of the bone structure) and nucleic acids take part in crucial roles in biological processes. A variety of other natural polymers survive, such as cellulose, which is the major constituent of wood and paper.