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Canon EF Lens Mount
The EF lens mount is the standard lens mount on the Canon EOS family of SLR film and digital cameras. EF stands for "Electro-Focus": automatic focusing on EF lenses is handled by a dedicated electric motor built into the lens. Mechanically, it is a bayonet-style mount, and all communication between camera and lens takes place through electrical contacts; there are no mechanical levers or plungers. The mount was first introduced in 1987. Canon claims to have produced its 100-millionth EF-series interchangeable lens on 22 April 2014. History The EF mount replaces its predecessor, the FD mount. The standard autofocus lens mounting technology of the time used a motor in the camera body to drive the mechanics of the focus helicoid in the lens by using a transfer lever. The key innovation of the EF series was to use a motor inside the lens itself for focusing. This allowed for autofocusing lenses which did not require mechanical levers in the mount mechanism, only electrical con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enhanced Fujita Scale
The Enhanced Fujita scale (abbreviated as EF-Scale) rates tornado intensity based on the severity of the damage they cause. It is used in some countries, including the United States, Canada, China, and Mongolia. The Enhanced Fujita scale replaced the decommissioned Fujita scale that was introduced in 1971 by Ted Fujita. Operational use began in the United States on February 1, 2007, followed by Canada on April 1, 2013. It has also been proposed for use in France. The scale has the same basic design as the original Fujita scale—six intensity categories from zero to five, representing increasing degrees of damage. It was revised to reflect better examinations of tornado damage surveys, in order to align wind speeds more closely with associated storm damage. Better standardizing and elucidating what was previously subjective and ambiguous, it also adds more types of structures and vegetation, expands degrees of damage, and better accounts for variables such as differences in con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Executive Functions
In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and successfully monitoring behaviors that facilitate the attainment of chosen goals. Executive functions include basic cognitive processes such as attentional control, cognitive inhibition, inhibitory control, working memory, and cognitive flexibility. Higher-order executive functions require the simultaneous use of multiple basic executive functions and include planning and fluid intelligence (e.g., reasoning and problem-solving). Executive functions gradually develop and change across the lifespan of an individual and can be improved at any time over the course of a person's life. Similarly, these cognitive processes can be adversely affected by a variety of events which affect an individual. Both neuropsychological tests (e.g., the Stroop test ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EF Education First
EF Education First (abbreviated as EF) is an international education company that specializes in language training, educational travel, academic degree programs, and cultural exchange. The company was founded in 1965 by Bertil Hult in the Swedish university town of Lund. The company is privately held by the Hult family. As of 2017, EF had approximately 52,000 employees in 116 countries. The company has particular focus in China and other Asian markets under the brand name "English First". History Bertil Hult dropped out of college to launch EF in 1969. He had earlier dropped out of junior high and gone to work for a ship broker in London, where he learned English by immersion; he had been unable to learn it in school due to dyslexia. The company started selling a French language course to Swedish students seeking to study in France, but he thought English was a bigger market and started offering services throughout Europe. In 1972 a friend convinced him to open a school ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elongation Factor
Elongation factors are a set of proteins that function at the ribosome, during protein synthesis, to facilitate translational elongation from the formation of the first to the last peptide bond of a growing polypeptide. Most common elongation factors in prokaryotes are EF-Tu, EF-Ts, EF-G. Bacteria and eukaryotes use elongation factors that are largely homologous to each other, but with distinct structures and different research nomenclatures. Elongation is the most rapid step in translation. In bacteria, it proceeds at a rate of 15 to 20 amino acids added per second (about 45-60 nucleotides per second). In eukaryotes the rate is about two amino acids per second (about 6 nucleotides read per second). Elongation factors play a role in orchestrating the events of this process, and in ensuring the high accuracy translation at these speeds. Nomenclature of homologous EFs In addition to their cytoplasmic machinery, eukaryotic mitochondria and plastids have their own translation ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canon EF Camera
The Canon EF is a manual focus 35mm 35 mm may refer to: * 135 film, a type of still photography format commonly referred to as 35 mm film * 35 mm movie film, a type of motion picture film stock * 35MM 35 mm may refer to: * 135 film, a type of still photography format ... single-lens reflex camera produced by Canon Inc., Canon between 1973 and 1978. It was compatible with Canon's Canon FD, FD-mount lenses. The EF was built as an electro-mechanical version of Canon's top-of-the line wholly mechanical Canon F-1. The shutter is mechanical at all speeds starting at 1/2 second and faster, but from 1 second and beyond the shutter is all electric, allowing for AE shutter speeds as long as 30 seconds. The EF shares the F-1's rugged construction and tough metal body. Unlike the F-1, the EF does not support any motor drive for film transport. Neither does it provide any interchangeable viewfinder. The Canon EF contained a silicon photocell light meter with a range of Exposu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ejection Fraction
An ejection fraction (EF) is the volumetric fraction (or portion of the total) of fluid (usually blood) ejected from a chamber (usually the heart) with each contraction (or heartbeat). It can refer to the cardiac atrium, ventricle, gall bladder, or leg veins, although if unspecified it usually refers to the left ventricle of the heart. EF is widely used as a measure of the pumping efficiency of the heart and is used to classify heart failure types. It is also used as an indicator of the severity of heart failure, although it has recognized limitations. The EF of the left heart, known as the left ventricular ejection fraction (LVEF), is calculated by dividing the volume of blood pumped from the left ventricle per beat (stroke volume) by the volume of blood collected in the left ventricle at the end of diastolic filling (end-diastolic volume). LVEF is an indicator of the effectiveness of pumping into the systemic circulation. The EF of the right heart, or right ventricular ejection ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth First!
Earth First! is a radical environmental advocacy group that originated in the Southwestern United States. It was founded in 1980 by Dave Foreman, Mike Roselle, Howie Wolke, Bart Koehler, and Ron Kezar. Today there are Earth First! groups around the world including ones in Australia, Belgium, Canada, the Czech Republic, France, Germany, India, Ireland, Italy, Mexico, the Netherlands, Nigeria, New Zealand, the Philippines, Poland, Slovakia, Spain, the United Kingdom, and the United States. Inspired by several environmental writings, including Rachel Carson's ''Silent Spring'', Aldo Leopold's land ethic, and Edward Abbey's ''The Monkey Wrench Gang'', a small group of environmental activists composed of Dave Foreman, ex-Yippie Mike Roselle, Wyoming Wilderness Society representatives Bart Koehler and Howie Wolke, and Bureau of Land Management employee Ron Kezar, united to form Earth First!. While traveling in Foreman's VW bus from the El Pinacate y Gran Desierto de Altar Biosphe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eastern Fare
The Eastern Fare Music Foundation is a music school, as well as a production and publishing house in Guwahati, Assam, India. The institute provides training for instrumental music in Western Classical music, Carnatic music and contemporary style. It was first founded in Bangalore in 2007. In 2016, the institute started its branches in Guwahati and Shillong. The branches in North East India provide classes in dance and Indian classical music. History It started early in 2007 with Assamese musician Jim Ankan Deka. In today's date the institute has six branches in the states of Karnataka, Assam and Meghalaya and provides training to over a thousand students. In 2009, Eastern Fare Music Foundation opened a club for the music enthusiasts known as Eastern Fare Music Club, which includes a library, a jamming room, two semi acoustic music studios and a discussion room. Faculty Jim Ankan Deka, founder and director of Eastern Fare Music Foundation, is a music composer, singer, songw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coin Grading
Coin grading is the process of determining the grade or condition of a coin, one of the key factors in determining its value. A coin's grade is generally determined by six criteria: strike, preservation, luster, color, attractiveness, and occasionally the country/state in which they’re minted. Several grading systems have been developed. Certification services professionally grade coins for tiered fees. Overview A "grade" measures a coin's appearance. There are generally five main components which determine a coin's grade: strike, surface preservation, luster, coloration and eye appeal. Grading is subjective and even experts can disagree about the grade of a given coin. History U.S. coin grading has evolved over the years to a system of finer and finer grade distinctions. Originally, there were only two grades, new and used. This changed to the letter grading system beginning with the lowest grade – ''Basal State'' (also ''Poor'' (PO)), then continuing ''Fair'' (Fr), ''Abou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Elias Fund
The Elias Fund is a nonprofit organization funding community development and education for Zimbabwean youth. Overview The Elias Fund began with a simple purpose - help one man raise his children. Today EF empowers Zimbabwean communities to build a promising future for their children through poverty alleviation. As a grassroots organization, the Elias Fund focuses on indigenous empowerment to alleviate poverty from the bottom-up. Mission statement The Elias Fund's mission statement is: "Spreading hope and opportunity in Zimbabwe through indigenous empowerment, and engaging the current youth culture of the United States by encouraging a positive identity centered on social justice." History In 1994, Elias Sithole, a gardener in Zimbabwe, met American songwriter Chad Urmston. Elias shared his dream of one day helping his three sons with a university education. This dream was put to song and became a popular piece with Urmston's band Dispatch. After the band broke up in 2004, bro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Footprint
The ecological footprint is a method promoted by the Global Footprint Network to measure human demand on natural capital, i.e. the quantity of nature it takes to support people or an economy. It tracks this demand through an ecological accounting system. The accounts contrast the biologically productive area people use for their consumption to the biologically productive area available within a region or the world (biocapacity, the productive area that can regenerate what people demand from nature). In short, it is a measure of human impact on the environment. Footprint and biocapacity can be compared at the individual, regional, national or global scale. Both footprint and biocapacity change every year with number of people, per person consumption, efficiency of production, and productivity of ecosystems. At a global scale, footprint assessments show how big humanity's demand is compared to what Earth can renew. Global Footprint Network estimates that, as of 2014, humanity has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
