All articles starting with U
6,146 articles
Upper confidence bound
The upper confidence bound (UCB) is a decision rule for multi-armed bandits and reinforcement learning that selects the action with the largest estimated reward plus an uncertainty bonus.
Upper Congo
Upper Congo, FEOW freshwater ecoregion 540, the Lualaba reach of the Congo River in the DRC from the Shaba Plateau to the Upper Congo Rapids, with endemic molluscs and a poorly surveyed endemic fish fauna.
Upper Congo Rapids
Upper Congo Rapids, freshwater ecoregion 539 (FEOW), a stretch of the Lualaba/Congo River between Ubundu and Kisangani, DR Congo, where the river drops 60 m over 100 km through rapids including Boyoma Falls, forming a fish dispersal barrier with a rapids-adapted fauna.
Upper critical solution temperature
The upper critical solution temperature (UCST) is the critical temperature above which a mixture is fully miscible, applied to partially miscible liquids like phenol and water and to polymer solutions.
Upper Danube
Upper Danube: upper course of the Danube River from the Black Forest through Austria to the Drava confluence; also WWF freshwater ecoregion 417, 248,000 km², temperate upland rivers with endemic lake whitefish and heavily altered hydrology.
Upper Deck Company
Upper Deck Company (The Upper Deck Company, LLC), founded 1988, American trading card and collectibles maker; 1989 premium baseball set, exclusive NHL license, UDA authentication, e-Pack digital platform, Carlsbad, California.
Upper Dir District
Upper Dir District (بر دير ولسوالۍ, ضلع دیر بالا), Khyber Pakhtunkhwa, Pakistan: mountainous Panjkora valley district created 1996 from Dir District; 1,083,566 people (2023), 3,699 sq km, 4.4% urban, Kumrat Valley tourism.
Upper East Region
Upper East Region: one of Ghana's 16 regions, capital Bolgatanga, created 1983 from the Upper Region split. Area 8,842 km², 2021 population 1,301,226, borders Burkina Faso and Togo, agricultural economy, PEARL development framework.
Upper East Side
Upper East Side: Manhattan neighborhood from East 59th to East 96th Street, Fifth Avenue to the East River, with Lenox Hill, Carnegie Hill, and Yorkville; known for Museum Mile, Central Park frontage, and the Second Avenue Subway.
Upper Egypt (صعيد مصر)
Upper Egypt (صعيد مصر) is southern Egypt, the Nile Valley between Nubia and Lower Egypt, named for the river's northward flow. Centered on Hierakonpolis, Nagada, and Abydos, its proto-states unified Egypt under Narmer around 3100 BC; today it holds about 38 percent of Egypt's population.
Upper Franconia
Upper Franconia (Oberfranken), a Bavarian Regierungsbezirk in northeastern Bavaria on the Thuringian, Saxon, and Czech borders; seat Bayreuth; nine districts plus Bamberg, Bayreuth, Coburg, Hof; about 1.06 million residents.
Upper Ganga River
Upper Ganga River (Ramsar site 1574) is an 85 km, 26,590 ha Ganges stretch from Brijghat to Narora, Uttar Pradesh, designated 8 November 2005; India's only riverine Ramsar site, habitat of the endangered Ganges river dolphin, gharial, and 82 fish species.
Upper Garonne
Upper Garonne (Haute-Garonne), French department 31 in Occitanie with prefecture Toulouse; 586 communes, 1,471,468 inhabitants in 2023, fastest-growing in Occitanie, dominated by the aerospace industry.
Upper gastrointestinal bleeding
Upper gastrointestinal bleeding (UGIB, hematemesis, melena): bleeding from the esophagus, stomach, or duodenum above the ligament of Treitz. Incidence 80-150/100,000 yearly, mortality 7-11%; peptic ulcers cause ~44%; managed with resuscitation, endoscopy within 24 hours, and post-endoscopy proton pump inhibitors.
Upper gastrointestinal series
Upper gastrointestinal series, also called barium swallow or UGI, is a fluoroscopic x-ray exam of the esophagus, stomach, and duodenum using drunk barium contrast, with single- and double-contrast forms, used to find ulcers, reflux, hernias, strictures, and tumors.
Upper Hand
Upper Hand (aka Pyramids, Use Your Marbles) is Margalith Akavya's two-player abstract marble-stacking game on a 5x5 grid, dated 1992 or 1985, with bonus placements completing 2x2 squares; distinct from 2016 Button Shy and pagat card games of the same name.
Upper house
Upper house: the second chamber of a bicameral legislature, also called a senate or House of Lords. Exists in 79 countries; filled by direct, indirect, or appointed designation; typically holds weaker veto and budget powers than the lower house.
Upper Huang He
The Upper Huang He (upper Yellow River) is the headwater reach of China's Yellow River on the Tibetan Plateau, freshwater ecoregion 634 supplying over 35% of the basin's water.
Upper Huang He Corridor
Upper Huang He Corridor (FEOW ecoregion 634): a Palearctic montane-freshwater ecoregion in China covering the Yellow River from the Himalayan exit to about Guide, Qinghai, plus Gansu's endorheic basins, with 1 endemic fish species.
Upper hybrid oscillation
An upper hybrid oscillation is an electrostatic electron oscillation in a magnetized plasma, whose frequency is the quadrature of electron plasma and cyclotron frequencies, used to measure electron density.
Upper Indus
The Upper Indus, also called the Upper Indus Basin (UIB), is the mountainous headwater of the Indus River above Tarbela Dam, spanning the Hindu Kush, Karakoram, and Himalaya.
Upper Iowa University
Upper Iowa University (UIU), founded 1857 in Fayette, Iowa, as Fayette Seminary, is a private nonprofit university with residential, regional, military, online, and self-paced programs; accredited by the Higher Learning Commission; Peacocks athletics in NCAA Division II.
Upper Irtysh
Upper Irtysh (Black Irtysh, Ertix He): headwater reach of the Irtysh River from the Altai glaciers in Xinjiang through Lake Zaysan to Ust-Kamenogorsk; also FEOW freshwater ecoregion 603 with 43 fish species, two endemics, and a large Soviet dam cascade.
Upper Klamath Lake
Upper Klamath Lake: Oregon's largest lake (305 km2, shallow), headwaters of the Klamath River; hypereutrophic with Aphanizomenon flos-aquae blooms, endangered Lost River and shortnose suckers, Link River Dam regulation since 1917, and Klamath Tribes' adjudicated instream water claim.
Upper Krishna Project
The Upper Krishna Project is a multi-stage irrigation and power project on the Krishna River in northern Karnataka, India, built around the Almatti and Narayanpur dams.
Upper Lancang (Mekong)
Upper Lancang (Mekong), ecoregion 724, the Chinese upper Mekong basin (Lancang Jiang, turbulent river). Tibetan Plateau headwaters, 11-dam cascade impounding 45.6 km3, 86.5% sediment trapping, endemic Schizothoracinae and Glyptosterninae fishes.
Upper limb
Upper limb (upper extremity): the shoulder-to-fingers region of the human body, divided into arm, forearm, and hand, with 30 bones per limb, brachial plexus innervation, and manipulation-focused anatomy.
Upper limb deep vein thrombosis
Upper limb deep vein thrombosis (UEDVT, upper extremity DVT): thrombosis of deep arm veins (subclavian, axillary, jugular), 5–10% of all DVT; primary Paget-Schroetter/effort thrombosis versus catheter- or cancer-associated secondary forms.
Upper limb hypertrophy
Upper limb hypertrophy (ORPHA:295049, HPO HP:0010484) is abnormal enlargement of the arm, forearm, or hand from increased cell size, occurring isolated or in overgrowth syndromes such as Klippel-Trenaunay, Servelle-Martorell, and PIK3CA-related overgrowth spectrum.
Upper Lualaba
Upper Lualaba is a freshwater ecoregion in the southeastern Democratic Republic of Congo, centered on the Kamolondo Depression, its lakes and swamps, and Upemba National Park.