Address:   Home Page

Portal:Science

From Wikipedia, the free encyclopedia

Jump to: navigation, search
For a topic outline on this subject, see List of basic topics in science
Main page   Categories & Main topics   Portals & WikiProjects   Things you can do
edit
The Science Portal

Icon

Science, in the broadest sense of the term, refers to any system of knowledge attained by verifiable means. In a more restricted sense, science refers to a system of acquiring knowledge based on empiricism, experimentation, and methodological naturalism, as well as to the organized body of knowledge humans have gained by such research.

Scientists maintain that scientific investigation must adhere to the scientific method, a process for properly developing and evaluating natural explanations for observable phenomena based on empirical study and independent verification. Science, therefore, avoids supernatural explanations until all other natural possibilities have been considered, and rejects arguments from authority.

Fields of science are commonly classified along two major lines: Natural sciences, which study natural phenomena; and Social sciences, which study human behavior and societies. Whether mathematics is a science is a matter of perspective.

Fields of science can be further distinguished as pure science or applied science. Pure science is principally involved with the discovery of new truths with less (or no) regard to their applications. Applied science is principally involved with the application of existing knowledge in new ways.

edit  watch  

Selected article

DNA damage resulting in multiple broken chromosomes
DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light can cause DNA damage, resulting in as many as 1 million individual molecular lesions per cell per day. Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells after it undergoes mitosis. Consequently, the DNA repair process must be constantly active so it can respond rapidly to any damage in the DNA structure.

The rate of DNA repair is dependent on many factors, including the cell type, the age of the cell, and the extracellular environment. A cell that has accumulated a large amount of DNA damage, or one that no longer effectively repairs damage incurred by its DNA, can enter one of three possible states: an irreversible state of dormancy, known as senescence; cell suicide, also known as apoptosis or programmed cell death; or unregulated cell division, which can lead to the formation of a tumor that is cancerous.

edit  watch  

Selected picture

Sonoluminescence is the emission of light by bubbles in a liquid excited by sound.
Credit: Dake

Sonoluminescence is the emission of short bursts of light from imploding bubbles in a liquid when excited by sound. The effect was first discovered at the University of Cologne in 1934 as a result of work on sonar. H. Frenzel and H. Schultes put an ultrasound transducer in a tank of photographic developer fluid. They hoped to speed up the development process. Instead, they noticed tiny dots on the film after developing, and realized that the bubbles in the fluid were emitting light with the ultrasound turned on. It was too difficult to analyze the effect in early experiments because of the complex environment of a large number of short-lived bubbles. (This experiment is also ascribed to N. Marinesco and J.J. Trillat in 1933).

Sonoluminescence may or may not occur whenever a sound wave of sufficient intensity induces a gaseous cavity within a liquid to quickly collapse. This cavity may take the form of a pre-existing bubble, or may be generated through a process known as cavitation. Sonoluminescence in the laboratory can be made to be stable, so that a single bubble will expand and collapse over and over again in a periodic fashion, emitting a burst of light each time it collapses.

edit  watch  

Selected biography

Leonhard Euler
Leonhard Euler (April 15, 1707 Basel, Switzerland - September 18, 1783 St Petersburg, Russia) was a Swiss mathematician and physicist. He is considered to be the dominant mathematician of the 18th century and one of the greatest mathematicians of all time; he is certainly among the most prolific, with collected works filling over 70 volumes. Euler developed many important concepts and proved numerous lasting theorems in diverse areas of mathematics, from calculus to number theory to topology. In the course of this work, he introduced much of modern mathematical terminology, defining the concept of a function, and its notation, such as sin, cos, and tan for the trigonometric functions.
edit  watch  

Did you know...

Ring-tailed lemur

edit  watch  

Science News

Science news on Wikipedia
  • February 11: A rat study found that rats given artificial sweetener gained more weight than those on a sugar diet. Scientists speculate the body increases the metabolism anticipating calories that never come, then requires more food to make up the shortfall. (SciAm)
  • February 8: The first commercial vessel to use a kite to help save fuel created by SkySails finished its maiden voyage. Estimates are that the ship saved 10-15% fuel while the kite was in use, which translates into $1,000 to $1,500 in fuel costs per day.(Nature)
  • February 7: A new knee device is demonstrated that can generate electricity efficiently from walking with minimal effort. The system acquires energy from deceleration similar to how hybrid-electric cars regain energy from regenerative braking. (CBC)
Science news on Wikinews
edit  watch  

Associated Wikimedia

Purge server cache

Retrieved from "http://en.wikipedia.org/wiki/Portal:Science"
Your Ad Here