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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.

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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.

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A Persian astrolabe, used for determining the time at both day and night.
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An 18th Century Persian astrolabe used for determining the time at both day and night. The points of the curved spikes on the front rete plate, mark the positions of the brightest stars. The name of each star being labeled at the base of each spike. The back plate, or mater is engraved with projected coordinate lines. From the Whipple M

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Santiago Ramón y Cajal
Santiago Ramón y Cajal (May 1, 1852 – October 17, 1934) was a famous Spanish histologist, physician, and Nobel laureate. He is considered to be one of the founders of modern neuroscience. His most famous studies were on the fine structure of the central nervous system. Cajal used a histological staining technique developed by his contemporary [[]] tissue continuous reticulum (or web) of in the circulatory system. Using Golgi's method, Ramón y Cajal reached a very different conclusion. He postulated that the nervous system is made up of billions of separate neurons and that these cells are polarized. Rather than forming a continuous web, Cajal suggested that neurons communicate with each other via specialized junctions called "synapses". This hypothesis became the basis of the neuron doctrine, which states that the individual unit of the nervous system is a single neuron. Electron microscopy later showed that a plasma membrane completely enclosed each neuron, supporting Cajal's theory, and weakening Golgi's reticular theory.
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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)
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