Controlled application of biological or chemical substances to the skin to test for allergy. Small amounts of diluted test substances applied under a patch of cloth or soft paper and an impermeable membrane are left in place for 48 hours, and the skin reaction is then examined and scored from 0 (none) to 4+ (severe blistering and redness).
Learn more about patch test with a free trial on Britannica.com.
Laboratory examination of the physical and chemical properties and components of a sample of blood. Analysis includes number of red and white blood cells (erythrocytes and leukocytes); red cell volume, sedimentation (settling) rate, and hemoglobin concentration; blood typing; cell shape and structure; hemoglobin and other protein structure; enzyme activity; and chemistry. Special tests detect substances characteristic of specific infections.
Learn more about blood analysis with a free trial on Britannica.com.
Test proposed by Alan M. Turing to determine whether a computer can be said to “think.” Turing suggested the “imitation game,” wherein a remote human interrogator, within a fixed time frame, must distinguish between a computer and a human subject based on their replies to questions posed by the interrogator. A series of such tests would measure the computer's success at “thinking” by the probability of its being misidentified as the human subject. The test is performed today in competitions that test the success of artificial intelligence.
Learn more about Turing test with a free trial on Britannica.com.
(1673) Act passed by the British Parliament that required holders of civil and military offices to profess the established religion and to receive Holy Communion according to the rites of the Church of England. Though directed primarily against Roman Catholics, it extended in principle to all non-Anglicans; it was modified in 1689 to enable most non-Catholics to qualify. An act adopted in 1828 removed the test. In the U.S. Constitution, Article VI prescribes that “no religious test” shall be required for any officeholder. Seealso Catholic Emancipation.
Learn more about Test Act with a free trial on Britannica.com.
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans all nuclear explosions in all environments, for military or civilian purposes.
Arms control advocates had campaigned for the adoption of a treaty banning all nuclear explosions since the early 1950s, when public concern was aroused as a result of radioactive fall-out from atmospheric nuclear tests and the escalating arms race. Over 50 nuclear explosions were registered between 16 July 1945, when the first nuclear explosive test was conducted by the United States at Alamogordo, New Mexico, and 31 December 1953. Prime Minister Nehru of India voiced the heightened international concern in 1954, when he proposed the elimination of all nuclear test explosions worldwide. However, within the context of the Cold War, skepticism in the capability to verify compliance with a comprehensive nuclear test ban treaty posed a major obstacle to any agreement. On 13 October 1999 the United States Senate rejected ratification of the CTBT.
Limited success was achieved with the signing of the Partial Test Ban Treaty in 1963, which banned nuclear tests in the atmosphere, underwater and in space. However, neither France nor China, signed the PTBT.
A major step towards non-proliferation of nuclear weapons came with the signing of the Nuclear Non-proliferation Treaty (NPT) in 1968. Under the NPT, non-nuclear weapon states were prohibited from, inter alia, possessing, manufacturing or acquiring nuclear weapons or other nuclear explosive devices. All signatories, including nuclear weapon states, were committed to the goal of total nuclear disarmament.
One of the largest issues was the priorities of the different countries. The Non-aligned movement countries were highly concerned with vertical proliferation (more and more bombs, new bomb technology) while the Nuclear Powers were focusing on horizontal proliferation (nuclear bombs being produced by states other than themselves).
The US has signed the CTBT, but not ratified it. There is ongoing debate whether or not the US should ratify the CTBT. Proponents of ratification claim that it would:
The Preparatory Commission for the Comprehensive Test Ban Treaty Organization (CTBTO), an international organization headquartered in Vienna, Austria, was created to build the verification regime, including establishment and provisional operation of the network of monitoring stations, the creation of an international data centre, and development of the On Site Inspection capability.
The monitoring network consists of 337 facilities located all over the globe. As of January 2008, nearly 70 percent of monitoring stations are operational. The monitoring stations register data that is transmitted to the international data centre in Vienna for processing and analysis. The data is sent to states that have signed the Treaty.