A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes which alter membrane fluidity; and as signaling molecules. Hundreds of steroids are found in plants, animals and fungi. All steroids are manufactured in cells from the sterols lanosterol (opisthokonts) or cycloartenol (plants). Lanosterol and cycloartenol are derived from the cyclization of the triterpene squalene.The steroid core structure is typically composed of seventeen carbon atoms, bonded in four "fused" rings: three six-member cyclohexane rings (rings A, B and C in the first illustration) and one five-member cyclopentane ring (the D ring). Steroids vary by the functional groups attached to this four-ring core and by the oxidation state of the rings. Sterols are forms of steroids with a hydroxy group at position three and a skeleton derived from cholestane.: 1785f Steroids can also be more radically modified, such as by changes to the ring structure, for example, cutting one of the rings. Cutting Ring B produces secosteroids one of which is vitamin D3.
Examples include the lipid cholesterol, the sex hormones estradiol and testosterone,: 10–19 and the anti-inflammatory drug dexamethasone.Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior". The field of ethics, along with aesthetics, concerns matters of value; these fields comprise the branch of philosophy called axiology.Ethics seeks to resolve questions of human morality by defining concepts such as good and evil, right and wrong, virtue and vice, justice and crime. As a field of intellectual inquiry, moral philosophy is related to the fields of moral psychology, descriptive ethics, and value theory.
Three major areas of study within ethics recognized today are:
Meta-ethics, concerning the theoretical meaning and reference of moral propositions, and how their truth values (if any) can be determined;
Normative ethics, concerning the practical means of determining a moral course of action;
Applied ethics, concerning what a person is obligated (or permitted) to do in a specific situation or a particular domain of action.Alcatraz Island (, Latin-American Spanish pronunciation: [alkaˈtɾas], European Spanish pronunciation: [alkaˈtɾaθ] from Arabic: الْغَطَّاس, romanized: al-ḡaṭṭās, lit. 'gannet ("the diver")') is located in San Francisco Bay, 1.25 miles (2.01 km) offshore from San Francisco, California, United States. The small island was developed with facilities for a lighthouse, a military fortification, a military prison, and a federal prison, the latter operated from August 11, 1934 until March 21, 1963. The strong currents around the island and cold water temperatures made escape all but impossible. Since the late 20th century, it has become a major tourist attraction.
Beginning in November 1969, the island was occupied for more than 19 months by a group of Native Americans, initially primarily from San Francisco, who were later joined by AIM and other urban Indians from other parts of the country, who were part of a wave of Native American activists organizing public protests across the US through the 1970s. In 1972, Alcatraz was transferred to the Department of Interior to become part of Golden Gate National Recreation Area. It was designated as a National Historic Landmark in 1986.
Today, the island's facilities are managed by the National Park Service as part of Golden Gate National Recreation Area. Visitors can reach the island in fewer than 15 minutes by ferry ride from Pier 33, located between the San Francisco Ferry Building and Fisherman's Wharf, San Francisco. Hornblower Cruises, operating under the name Alcatraz Cruises, is the official ferry provider to and from the island.
Alcatraz Island is the site of the abandoned federal prison, the oldest operating lighthouse on the West Coast of the United States, early military fortifications, and natural features such as rock pools and a seabird colony (mostly western gulls, cormorants, and egrets). According to a 1971 documentary on the history of Alcatraz, the island measures 1,675 feet (511 m) by 590 feet (180 m) and is 135 feet (41 m) at highest point during mean tide. The total area of the island is reported to be 22 acres (8.9 ha).Landmarks on the island include the Main Cellhouse, Dining Hall, Lighthouse, the ruins of the Warden's House and Social Hall, Parade Grounds, Building 64, Water Tower, New Industries Building, Model Industries Building, and the Recreation Yard.