Sunday, June 29, 2008

Body plan

A body plan, or bauplan, is essentially the blueprint for the way the body of an organism is laid out. An organism's symmetry, its number of body segments and number of limbs are all aspects of its body plan. One of the key issues of developmental biology is the evolution of body plans as different as those of a starfish, a fern, or a mammal, from a common biological heritage, and in particular how radical changes in body plans have occurred over geological time. The body plan is a key feature of an organism's morphology, and since the discovery of DNA developmental biologists have been able to learn a lot about how genes control the development of structural features through a cascade of processes in which key genes produce morphogens, chemicals that diffuse through the body to produce a gradient that acts as a position indicator for cells, turning on other genes, some of which in turn produce other morphogens. A key discovery was the existence of groups of homeobox genes which are responsible for laying down the basic body plan in organisms. The homeobox genes are remarkably conserved between species as diverse as the fruitfly and man, the basic segmented pattern of the worm or fruitfly being the origin of the segmented spine in man. The field of evolutionary developmental biology, which studies the genetics of morphology in detail is now a rapidly expanding one [1], with many of the developmental genetic cascades, particularly in the fruitfly drosophila, now catalogued in considerable detail .Body plan is the basis for phylum, and there are 35 different basic animal body plans, corresponding to different phyla.

Sunday, June 22, 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

Sunday, June 15, 2008

Agere Systems

Agere Systems Inc. was an integrated circuit components company based in Allentown, Pennsylvania, in the Lehigh Valley region of Pennsylvania, in the United States. Effective April 2, 2007, it was merged into LSI Corporation.

Agere was incorporated on August 1, 2000 as a subsidiary of Lucent Technologies and then spun-off on June 1, 2002. The name Agere was that of a Texas-based electronics company that Lucent had acquired in 2000, although the pronunciations of the company names are different. The Texas company was pronounced with three syllables and a hard "g": A-gear-uh. The company name was pronounced with two syllables and a hard "g": A-gear.

The company also maintained an India office in Whitefield, India, located in the city of Bangalore, which is involved in ASIC design and software development.
The company also maintained an Israel office located in Raanana. This office was based on Modem-Art a developer of advanced processor technology for 3G/UMTS mobile devices which Agere has acquired in 2005.

The China offices of Agere were located at Shanghai and Shenzhen

Sunday, June 08, 2008

Trance genres

Trance music is broken into a large number of genres. Chronologically, the major genres are Classic trance, Acid trance, Progressive trance, and Uplifting Trance.Uplifting Trance is also known as "Anthem trance", "Epic trance", "Stadium trance" or "Euphoric trance".Closely related to Uplifting Trance is Euro-trance, which has become a general term for a wide variety of highly commercialized European dance music. Several subgenres are crossovers with other major genres of electronic music. For instance, tech trance is a mixture of trance and techno, and Ambient trance is a mixture of ambient and trance. Balearic beat, which is associated with the laid back vacation lifestyle of Ibiza, Spain, is often called "Ibiza trance". Similarly, Dream trance is sometimes called "Dream House", and is a subgenre of relaxing trance pioneered by Robert Miles in the mid 90s.

Another important distinction is between European trance and Goa trance which originated in Goa, India around the same time trance was evolving in Europe. Goa trance was influential in the formation of Psychedelic Trance, which features spazzy, spontaneous samples and other psychedelic elements. Trance is also very popular in Israel, with psychedelic trance producers such as Infected Mushroom and Yahel Sherman achieving world wide fame. The Israeli subgenre called Nitzhonot is a mixture of psychedelic and uplifting trance.

Sunday, June 01, 2008

Phase (matter)

In addition to the specific chemical properties that distinguish different chemical classifications chemicals can exist in several phases. For the most part, thechemical classifications are independent of these bulk phase classifications;however, some more exotic phases are incompatible with certain chemical properties.A phase is a set of states of a chemical system that have similar bulk structuralproperties, over a range of conditions, such as pressure or temperature. Physicalproperties, such as density and refractive index tend to fall within values characteristic of the phase. The phase of matter is defined by the phase transition,which is when energy put into or taken out of the system goes into rearranging the structure of the system, instead of changing the bulk conditions.

Sometimes the distinction between phases can be continuous instead of having a discrete boundary, in this case the matter is considered to be in a supercritical state. When three states meet based on the conditions, it is known as a triple point and since this is invariant, it is a convenient way to define a set of conditions.

The most familiar examples of phases are solids, liquids, and gases. Many substances exhibit multiple solid phases. For example, there are three phases of solid iron (alpha, gamma, and delta) that vary based on temperature and pressure. A principal difference between solid phases is the crystal structure, or arrangement, of the atoms. Less familiar phases include plasmas, Bose-Einstein condensates and fermionic condensates and the paramagnetic and ferromagnetic phases of magnetic materials. While most familiar phases deal with three-dimensional systems, it is also possible to define analogs in two-dimensional systems, which has received attention for its relevance to systems in biology.