Monday, September 24, 2007

Society

A society is a grouping of individuals, which is characterized by common interests and may have characteristic culture and institutions. In a society, members can be from a different ethnic group. A "Society" may refer to a particular people, such as the Nuer, to a nation state, such as Switzerland, or to a broader cultural group, such as a Western society. Society can also refer to an prearranged group of people linked together for religious, benevolent, cultural, scientific, political, patriotic, or other purposes.

Monday, September 17, 2007

The structure of pollen

Each pollen grain contain vegetative cells only one in the greater part flowering plant but several in other seed plants and a generative cell contain a tube nucleus that produces the pollen tube and a generative nucleus that divide to form the two sperm cells. The group of cells is surrounded by a cellulose cell wall and a thick, rough outer wall made of sporopollenin.

Pollen is created in the microsporangium contained in the anther of an angiosperm flower, male cone of a coniferous plant, or male cone of other seed plants. Pollen grains come in a broad multiplicity of shapes, sizes, and surface markings characteristic of the species see photomicrograph at right. Most, but surely not all, are spherical, Pollen grains of pines, firs, and spruces are wing. The minimum pollen grain that of the Forget-me-not plant (Myosotis sp.), is approximately 6 µm (0.006 mm) in diameter.

Pollen grains may have furrows, the course of which classify the pollen as colpate or sulcate. The number of furrows or pores helps categorize the flowering plants, with eudicots having three colpi (tricolpate), and other groups having one sulcus.

Monday, September 10, 2007

Earth's atmosphere

Earth's atmosphere is a layer of gases surrounding the planet Earth and retain by the Earth's gravity. It contains roughly (by molar content/volume) 78% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide; trace amounts of other gases, and a changeable amount (average around 1%) of water vapor. This mixture of gases is usually known as air. The atmosphere protects life on Earth by captivating ultraviolet solar radiation and reducing temperature extremes between day and night.

There is no exact border between the atmosphere and outer space, it slowly becomes thinner and fades into liberty. Three quarters of the atmosphere's mass is within 11 km of the terrestrial surface. In the United States, people who travel above a height of 80.5 km (50 statute miles) are selected astronauts. An altitude of 120 km (400,000 ft) marks the boundary where atmospheric property becomes obvious during re-entry. The Kármán line, at 100 km (328,000 ft), is also often regarded as the boundary between atmosphere and outer space.

Tuesday, September 4, 2007

Dance

Dance means in Old French dancier, perhaps from Frankish generally refers to human movement also used as a form of expression or presented in a social, spiritual or performance setting.

Dance also is used to explain methods of non-verbal communication (see body language) between humans or animals (bee dance, mating dance), motion in inanimate objects (the leaves danced in the wind), and certain musical forms or genres.

Choreography is the art of making dances, and the human being who does this is called a choreographer.

Definitions of what constitutes dance are dependent on social, cultural, visual, artistic and moral constraints and variety from functional movement (such as folk dance) to codified, virtuoso techniques such as ballet. Dance disciplines live in sports such as gymnastics, figure skating, and synchronized swimming and martial arts kata are often compare to dance.