Birth control

Birth control, also known as contraception and fertility control, are methods or devices used to prevent pregnancy. Planning, provision and use of birth control is called family planning. Birth control methods have been used since ancient times, but effective and safe methods only became available in the 20th century. Some cultures limit or discourage access to birth control because they consider it to be morally, religiously, or politically undesirable.

The most effective methods of birth control are sterilization by means of vasectomy in males and tubal ligation in females, intrauterine devices (IUDs), and implantable contraceptives. This is followed by a number of hormonal contraceptives including oral pills, patches, vaginal rings, and injections. Less effective methods include barriers such as condoms, diaphragms and contraceptive sponge and fertility awareness methods. The least effective methods are spermicides and withdrawal by the male before ejaculation. Sterilization, while highly effective, is not usually reversible; all other methods are reversible, most immediately upon stopping them.Safe sex, such as the use of male or female condoms, can also help prevent sexually transmitted infections.Emergency contraceptives can prevent pregnancy in the few days after unprotected sex. Some regard sexual abstinence as birth control, but abstinence-only sex education may increase teen pregnancies when offered without contraceptive education, due to non-compliance.

Getty Images

Getty Images, Inc. is an American stock photo agency, based in Seattle, Washington, United States. It is a supplier of stock images for business and consumers with an archive of 80 million still images and illustrations and more than 50,000 hours of stock film footage. It targets three markets—creative professionals (advertising and graphic design), the media (print and online publishing), and corporate (in-house design, marketing and communication departments).

Getty has distribution offices around the world and capitalizes on the Internet and CD-ROM collections for distribution. As Getty has acquired other older photo agencies and archives, it has digitized their collections, enabling online distribution. Getty Images now operates a large commercial website which allows clients to search and browse for images, purchase usage rights and download images. Costs of images vary according to the chosen resolution and type of rights associated with each image. The company also offers custom photo services for corporate clients.

Gamma ray

Gamma radiation (sometimes called gamma ray), denoted by the lower-case Greek letter gamma (γ), is extremely high-frequency electromagnetic radiation and therefore consists of high-energy photons. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays. Rutherford had previously discovered two other types of radioactive decay, which he named alpha and beta rays.

Gamma rays are ionizing radiation, and are thus biologically hazardous. Decay of an atomic nucleus from a high energy state to a lower energy state, a process called gamma decay, produces gamma radiation. This is what Villard had observed.

Natural sources of gamma rays on Earth include gamma decay of radionuclides and secondary radiation from atmospheric interactions with cosmic ray particles. Rare terrestrial natural sources produce gamma rays that are not of a nuclear origin, such as lightning strikes and terrestrial gamma-ray flashes. Additionally, gamma rays are produced by a number of astronomical processes in which very high-energy electrons are produced, that in turn cause secondary gamma rays via bremsstrahlung, inverse Compton scattering, and synchrotron radiation. However, a large fraction of such astronomical gamma rays are screened by Earth's atmosphere and can only be detected by spacecraft. Gamma rays are produced by nuclear fusion in stars including the Sun (such as the CNO cycle), but are absorbed or inelastically scattered by the stellar material before escaping and are not observable from Earth.

Birth

Birth, also known as parturition, is the act or process of bearing or bringing forth offspring. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the fetus at a developmental stage when it is ready to feed and breathe. In some species the offspring is precocial and can move around almost immediately after birth but in others it is altricial and completely dependent on parenting. In marsupials, the fetus is born at a very immature stage after a short gestational period and develops further in its mother's pouch.

It is not only mammals that give birth. Some reptiles, amphibians, fish and invertebrates carry their developing young inside them. Some of these are ovoviviparous, with the eggs being hatched inside the mother's body, and others are viviparous, with the embryo developing inside her body, as in mammals.

Birth in mammals

Large mammals, such as primates, cattle, horses, some antelopes, giraffes, hippopotamuses, rhinoceroses, elephants, seals, whales, dolphins, and porpoises, generally are pregnant with one offspring at a time; although, they may have twin or multiple births on occasion. In these large animals, the birth process is similar to that of a human though in most, the offspring is precocial. This means that it is born in a more advanced state than a human baby and is able to stand, walk and run (or swim in the case of an aquatic mammal) shortly after birth. In the case of whales, dolphins and porpoises, the single calf is normally born tail first which minimises the risk of drowning. The mother encourages the newborn calf to rise to the surface of the water to breathe.

Rock It (album)

Rock It is a Chuck Berry album released in 1979 by Atco Records; Atco was only the third label for which Berry recorded studio material after two tenures with Chess Records and a brief 1960s stint at Mercury Records. It is, to date, his most recent studio album (although he has released some live recordings since). It is his only release on Atco.

Track listing

All tracks composed by Chuck Berry

Personnel

References