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Lester Germer
Lester Halbert Germer (October 10, 1896 – October 3, 1971) was an American physicist. With Clinton Davisson, he proved the wave-particle duality of matter in the Davisson–Germer experiment, which was important to the development of the electron microscope. These studies supported the theoretical work of De Broglie. He also studied thermionics, erosion of metals, and contact physics. He was awarded the Elliott Cresson Medal in 1931. A former fighter pilot in World War I, Germer subsequently worked at Bell Labs in New Jersey. In 1945 (at the age of 49), Germer launched a side career as a rock climber. He climbed widely around the Northeast United States, and especially at New York's Shawangunk Ridge. Although the Appalachian Mountain Club was dominant in the area at the time, and strictly regulated rock climbing, Lester was never associated with the club, and found himself in conflict with the leading climber in the area, Hans Kraus, who was head of the AMC's Safety Com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clinton Joseph Davisson
Clinton Joseph Davisson (October 22, 1881 – February 1, 1958) was an American physicist who won the 1937 Nobel Prize in Physics for his discovery of electron diffraction in the famous Davisson–Germer experiment. Davisson shared the Nobel Prize with George Paget Thomson, who independently discovered electron diffraction at about the same time as Davisson. Early life and education Davisson was born in Bloomington, Illinois. He graduated from Bloomington High School (Bloomington, Illinois), Bloomington High School in 1902, and entered the University of Chicago on scholarship. Upon the recommendation of Robert A. Millikan, in 1905 Davisson was hired by Princeton University as Instructor of Physics. He completed the requirements for his B.S. degree from Chicago in 1908, mainly by working in the summers. While teaching at Princeton, he did doctoral thesis research with Owen Richardson. He received his Ph.D. in physics from Princeton in 1911; in the same year he married Richardson's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermionics
Thermionic emission is the liberation of electrons from an electrode by virtue of its temperature (releasing of energy supplied by heat). This occurs because the thermal energy given to the charge carrier overcomes the work function of the material. The charge carriers can be electrons or ions, and in older literature are sometimes referred to as thermions. After emission, a charge that is equal in magnitude and opposite in sign to the total charge emitted is initially left behind in the emitting region. But if the emitter is connected to a battery, the charge left behind is neutralized by charge supplied by the battery as the emitted charge carriers move away from the emitter, and finally the emitter will be in the same state as it was before emission. The classical example of thermionic emission is that of electrons from a hot cathode into a vacuum (also known as thermal electron emission or the Edison effect) in a vacuum tube. The hot cathode can be a metal filament, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grade (climbing)
In rock climbing, mountaineering, and other climbing disciplines, climbers give a grade to a climbing route or boulder problem, intended to describe concisely the difficulty and danger of climbing it. Different types of climbing (such as sport climbing, bouldering or ice climbing) each have their own grading systems, and many nationalities developed their own, distinctive grading systems. There are a number of factors that contribute to the difficulty of a climb, including the technical difficulty of the moves, the strength, stamina and level of commitment required, and the difficulty of protecting the climber. Different grading systems consider these factors in different ways, so no two grading systems have an exact one-to-one correspondence. Climbing grades are inherently subjective.Reynolds Sagar, Heather, 2007, ''Climbing your best: training to maximize your performance'', Stackpole Books, UK, 9. They may be the opinion of one or a few climbers, often the first ascensioni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Climbing
Lead climbing is a climbing style, predominantly used in rock climbing. In a roped party one climber has to take the lead while the other climbers follow. The ''lead climber'' wears a harness attached to a climbing rope, which in turn is connected to the other climbers below the lead climber. While ascending the route, the lead climber periodically connects the rope to protection equipment for safety in the event of a fall. This protection can consist of permanent bolts, to which the climber clips quickdraws, or removable protection such as nuts and cams. One of the climbers below the lead climber acts as a belayer. The belayer gives out rope while the lead climber ascends and also stops the rope when the lead climber falls or wants to rest. A different style than lead climbing is top-roping. Here the rope is preattached to an anchor at the top of a climbing route before the climber starts their ascent. Lead climbing as a discipline of sport climbing debuted at the 2020 Summ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myocardial Infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck or jaw. Often it occurs in the center or left side of the chest and lasts for more than a few minutes. The discomfort may occasionally feel like heartburn. Other symptoms may include shortness of breath, nausea, feeling faint, a cold sweat or feeling tired. About 30% of people have atypical symptoms. Women more often present without chest pain and instead have neck pain, arm pain or feel tired. Among those over 75 years old, about 5% have had an MI with little or no history of symptoms. An MI may cause heart failure, an irregular heartbeat, cardiogenic shock or cardiac arrest. Most MIs occur due to coronary artery disease. Risk factors include high blood pressure, smoking, diabetes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Kraus
Hans Kraus (November 28, 1905 in Austria-Hungary – March 6, 1996, in New York City) was a physician, physical therapist, mountaineer and alpinist. A pioneer of modern rock climbing, he was also one of the fathers of sports medicine and physical medicine and rehabilitation and was elected to the U.S. National Ski Hall of Fame in 1974. Career Born in the Austro-Hungarian Empire, Kraus attended medical school in Vienna in the 1920s, against his father's wishes, becoming an orthopedic surgeon. Through his subsequent practice he developed a philosophy of treatment at odds with traditional medicine of the time. He would evolve this method, called "immediate mobilization", over his entire medical career. Passing his medical exams in New York, Kraus continued developing unique methods of fracture treatment, applying them to all kinds of athletes. He became especially well known in skiing circles. In the 1950s, Kraus was behind a push by the Appalachian Mountain Club to regula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Appalachian Mountain Club
Appalachian Mountain Club (AMC) is the oldest outdoor group in the United States. Created in 1876 to explore and preserve the White Mountains in New Hampshire, it has expanded throughout the northeastern U.S., with 12 chapters stretching from Maine to Washington, D.C. The AMC's 275,000 members, advocates, and supporters () mix outdoor recreation, particularly hiking and backpacking, with environmental activism. Additional activities include cross-country skiing, whitewater and flatwater canoeing and kayaking, sea kayaking, sailing, rock climbing and bicycle riding. The Club has about 2,700 volunteers, who lead roughly 7,000 trips and activities per year. The organization publishes a number of books, guides, and trail maps. History Appalachian Mountain Club was organized in 1876, incorporated in 1878, and authorized by legislative act of 1894 to hold mountain and forest lands as historic sites. The club was formed by the efforts of Massachusetts Institute of Technology Professor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northeast United States
The Northeastern United States, also referred to as the Northeast, the East Coast, or the American Northeast, is a geographic list of regions of the United States, region of the United States. It is located on the Atlantic Ocean, Atlantic coast of North America, with Canada to its north, the Southern United States to its south, and the Midwestern United States to its west. The Northeast is one of the four regions defined by the United States Census Bureau, U.S. Census Bureau for the collection and analysis of statistics. The region is usually defined as including nine U.S. states: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York (state), New York, Pennsylvania, Rhode Island, and Vermont. The United States Census Bureau, U.S. Census Bureau–defined region of the Northeastern United States has a total area of with of that being land mass, making it the smallest region of the United States by both land mass and total area. The Northeastern region is the nati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock Climbing
Rock climbing is a sport in which participants climb up, across, or down natural rock formations. The goal is to reach the summit of a formation or the endpoint of a usually pre-defined route without falling. Rock climbing is a physically and mentally demanding sport, one that often tests a climber's strength, endurance, agility and balance along with mental control. Knowledge of proper climbing techniques and the use of specialized climbing equipment is crucial for the safe completion of routes. Because of the wide range and variety of rock formations around the world, rock climbing has been separated into several different styles and sub-disciplines, such as scrambling, bouldering, sport climbing, and trad (traditional) climbing another activity involving the scaling of hills and similar formations, differentiated by the rock climber's sustained use of hands to support their body weight as well as to provide balance. Rock climbing competitions have the objectives of either ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Jersey
New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware River and Pennsylvania; and on the southwest by Delaware Bay and the state of Delaware. At , New Jersey is the fifth-smallest state in land area; but with close to 9.3 million residents, it ranks 11th in population and first in population density. The state capital is Trenton, and the most populous city is Newark. With the exception of Warren County, all of the state's 21 counties lie within the combined statistical areas of New York City or Philadelphia. New Jersey was first inhabited by Native Americans for at least 2,800 years, with the Lenape being the dominant group when Europeans arrived in the early 17th century. Dutch and Swedish colonists founded the first European settlements in the state. The British later seized control o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell Labs
Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by multinational company Nokia. With headquarters located in Murray Hill, New Jersey, the company operates several laboratories in the United States and around the world. Researchers working at Bell Laboratories are credited with the development of radio astronomy, the transistor, the laser, the photovoltaic cell, the charge-coupled device (CCD), information theory, the Unix operating system, and the programming languages B, C, C++, S, SNOBOL, AWK, AMPL, and others. Nine Nobel Prizes have been awarded for work completed at Bell Laboratories. Bell Labs had its origin in the complex corporate organization of the Bell System telephone conglomerate. In the late 19th century, the laboratory began as the Western Electric Engineering Department, l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fighting occurring throughout Europe, the Middle East, Africa, the Pacific, and parts of Asia. An estimated 9 million soldiers were killed in combat, plus another 23 million wounded, while 5 million civilians died as a result of military action, hunger, and disease. Millions more died in genocides within the Ottoman Empire and in the 1918 influenza pandemic, which was exacerbated by the movement of combatants during the war. Prior to 1914, the European great powers were divided between the Triple Entente (comprising France, Russia, and Britain) and the Triple Alliance (containing Germany, Austria-Hungary, and Italy). Tensions in the Balkans came to a head on 28 June 1914, following the assassination of Archduke Franz Ferdin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
