Glacier Bay National Park and Preserve is an American national park located in Southeast Alaska west of Juneau. President Calvin Coolidge proclaimed the area around Glacier Bay a national monument under the Antiquities Act on February 26, 1925. Subsequent to an expansion of the monument by President Jimmy Carter in 1978, the Alaska National Interest Lands Conservation Act (ANILCA) enlarged the national monument by 523,000 acres (817.2 sq mi; 2,116.5 km2) on December 2, 1980, and created Glacier Bay National Park and Preserve. The national preserve encompasses 58,406 acres (91.3 sq mi; 236.4 km2) of public land to the immediate northwest of the park, protecting a portion of the Alsek River with its fish and wildlife habitats, while allowing sport hunting. Glacier Bay became part of a binational UNESCO World Heritage Site in 1979, and was inscribed as a Biosphere Reserve in 1986. The National Park Service undertook an obligation to work with Hoonah and Yakutat Tlingit Native American organizations in the management of the protected area in 1994. The park and preserve cover a total of 3,223,384 acres (5,037 sq mi; 13,045 km2), with 2,770...

In astronomy, extinction is the absorption and scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observer. Interstellar extinction was first documented as such in 1930 by Robert Julius Trumpler. However, its effects had been noted in 1847 by Friedrich Georg Wilhelm von Struve, and its effect on the colors of stars had been observed by a number of individuals who did not connect it with the general presence of galactic dust. For stars that lie near the plane of the Milky Way and are within a few thousand parsecs of the Earth, extinction in the visual band of frequencies (photometric system) is roughly 1.8 magnitudes per kiloparsec.For Earth-bound observers, extinction arises both from the interstellar medium (ISM) and the Earth's atmosphere; it may also arise from circumstellar dust around an observed object. Strong extinction in earth's atmosphere of some wavelength regions (such as X-ray, ultraviolet, and infrared) is overcome by the use of space-based observatories. Since blue light is much more strongly attenuated than red light, extinction causes objects to appear redder than expected, a phenomenon referred to...

A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture medium under controlled laboratory conditions. Microbial cultures are foundational and basic diagnostic methods used as a research tools in molecular biology. The term culture can also refer to the microorganisms being grown. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested, or both. It is one of the primary diagnostic methods of microbiology and used as a tool to determine the cause of infectious disease by letting the agent multiply in a predetermined medium. For example, a throat culture is taken by scraping the lining of tissue in the back of the throat and blotting the sample into a medium to be able to screen for harmful microorganisms, such as Streptococcus pyogenes, the causative agent of strep throat. Furthermore, the term culture is more generally used informally to refer to "selectively growing" a specific kind of microorganism in the lab. It is often essential to isolate a pure culture of microorganisms. A pure (or axenic...