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RF (other)
RF is an abbreviation for radio frequency. Rf or RF may also mean: Arts and entertainment * '' Red Faction (series)'', a series of revolution video games * Rinforzando, , in music notation * ''RF Online'', an online RPG made by CCR * RFTV, a Brazilian television network Business * Aero K, IATA code (2020–present) * Florida West International Airways, IATA code (1984–2017) * Radio Nippon, (a.k.a. RF Radio Nippon, from its call sign JORF), a radio station in Yokohama, Japan * Regions Financial Corporation, NYSE stock symbol * Registered association (Finland) (''Registrerad förening''), Finnish legal status for a non-profit organization * Royalty-free, in business Government and politics * France (''République française'') * Russian Federation * Rhodesian Front, former political party in Rhodesia Biology and medicine * Rheumatic fever, an inflammatory disease * Release factors RF1, RF2, RF3, proteins * Reticular formation, in the brainstem * Rheumatoid factor, an antibody * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Frequency
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the upper limit of audio frequencies that humans can hear (though these are not electromagnetic) and the lower limit of infrared frequencies, and also encompasses the microwave range. These are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves, so they are used in radio technology, among other uses. Different sources specify different upper and lower bounds for the frequency range. Electric current Electric currents that oscillate at radio frequencies (RF currents) have special properties not shared by direct current or lower audio frequency alternating current, such as the 50 or 60 Hz current used in electrical power distribution. * Energy from RF currents in conduct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reticular Formation
The reticular formation is a set of interconnected nuclei in the brainstem that spans from the lower end of the medulla oblongata to the upper end of the midbrain. The neurons of the reticular formation make up a complex set of neural networks in the core of the brainstem. The reticular formation is made up of a diffuse net-like formation of reticular nuclei which is not well-defined. It may be seen as being made up of all the interspersed cells in the brainstem between the more compact and named structures. The reticular formation is functionally divided into the ascending reticular activating system (ARAS), ascending pathways to the cerebral cortex, and the descending reticular system, descending pathways ( reticulospinal tracts) to the spinal cord. Due to its extent along the brainstem it may be divided into different areas such as the midbrain reticular formation, the central mesencephalic reticular formation, the pontine reticular formation, the paramedian pontine reticul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Right Fielder
A right fielder, abbreviated RF, is the outfielder in baseball or softball who plays defense in right field. Right field is the area of the outfield to the right of a person standing at home plate and facing towards the pitcher's mound. In the numbering system used to record defensive plays, the right fielder is assigned the number 9. Position description Outfielders must cover large distances, so speed, instincts and quickness to react to the ball are key. They must be able to catch fly balls above their head and on the run, as well as prevent balls hit down the right field Baseball, foul line from getting past them. Being situated 250–300 feet from home plate, they must be able to throw the ball accurately over a long distance to be effective. Of all outfield positions, the right fielder often has the strongest arm, because they are the farthest from third base. As well as the requirements above, the right fielder backs up First baseman, first base on all throws from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Range Factor
Range Factor (commonly abbreviated RF) is a baseball statistic developed by Bill James. It is calculated by dividing putouts and assists by the number of innings or games played at a given defense position. The statistic is premised on the notion that the total number of outs in which a player participates is more relevant in evaluating that player's defensive play than the percentage of cleanly handled chances as calculated by the conventional statistic fielding percentage. However, some positions (especially first baseman) may have substantially more putouts because of a superior infield around them that commits fewer errors and turns many double plays, allowing them to receive credit for more putouts. Also, catchers who have many strikeout pitchers on their team will have a high range factor, because the catcher gets the putout on a strikeout if the batter does not reach base. All-time single-season leaders :Note: ''All-time single-season leaders are listed according to Range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canon RF Mount
The Canon RF lens mount is an interchangeable-lens mount developed by Canon for its full-frame mirrorless interchangeable-lens cameras, and featured first by the EOS R, followed by the EOS RP. The RF mount was announced in September 2018. In May 2022, Canon announced APS-C EOS R cameras (the EOS R10 and EOS R7) and RF-S lenses designed for these cameras. The RF mount allows for the use of Canon EF and EF-S mount lenses using one of three Canon-made lens adapters. When an RF-S or EF-S lens is attached, however, the camera will only function as an APS-C camera, not a full-frame camera. Details Canon full-frame cameras have used the EF lens mount since 1987. In comparison with that mount, the RF mount's inner diameter is the same at 54 mm. The RF mount's flange focal distance at 20 mm is much shorter than that of the Canon EF and EF-S mounts at 44 mm. The EF-M mount has a flange focal distance of 18 mm. An EF-EOS R lens adapter enables Canon EF, EF-S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rutherfordium
Rutherfordium is a synthetic element, synthetic chemical element; it has Chemical symbol, symbol Rf and atomic number 104. It is named after physicist Ernest Rutherford. As a synthetic element, it is not found in nature and can only be made in a particle accelerator. It is radioactive; the most stable known isotope, 267Rf, has a half-life of about 48 minutes. In the periodic table, it is a d-block element and the second of the fourth-row transition elements. It is in period 7 and is a group 4 element. Chemistry experiments have confirmed that rutherfordium behaves as the heavier Homologous series, homolog to hafnium in group 4. The chemical properties of rutherfordium are characterized only partly. They compare well with the other group 4 elements, even though some calculations had indicated that the element might show significantly different properties due to Relativistic quantum chemistry, relativistic effects. In the 1960s, small amounts of rutherfordium were produced at Joint ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Random Forest
Random forests or random decision forests is an ensemble learning method for statistical classification, classification, regression analysis, regression and other tasks that works by creating a multitude of decision tree learning, decision trees during training. For classification tasks, the output of the random forest is the class selected by most trees. For regression tasks, the output is the average of the predictions of the trees. Random forests correct for decision trees' habit of overfitting to their Test set, training set. The first algorithm for random decision forests was created in 1995 by Tin Kam Ho using the random subspace method, which, in Ho's formulation, is a way to implement the "stochastic discrimination" approach to classification proposed by Eugene Kleinberg. An extension of the algorithm was developed by Leo Breiman and Adele Cutler, who registered "Random Forests" as a trademark in 2006 (, owned by Minitab, Minitab, Inc.). The extension combines Breiman's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiative Forcing
Radiative forcing (or climate forcing) is a concept used to quantify a change to the balance of energy flowing through a planetary atmosphere. Various factors contribute to this change in energy balance, such as concentrations of greenhouse gases and aerosols, and changes in surface albedo and solar irradiance. In more technical terms, it is defined as "the change in the net, downward minus upward, radiative flux (expressed in W/m2) due to a change in an external driver of climate change." These external drivers are distinguished from feedbacks and variability that are internal to the climate system, and that further influence the direction and magnitude of imbalance. Radiative forcing on Earth is meaningfully evaluated at the tropopause and at the top of the stratosphere. It is quantified in units of watts per square meter, and often summarized as an average over the total surface area of the globe. A planet in radiative equilibrium with its parent star and the rest of sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retardation Factor
In chromatography, the retardation factor (''R'') is the fraction of an analyte in the mobile phase of a chromatographic system. In planar chromatography in particular, the retardation factor ''R''F is defined as the ratio of the distance traveled by the center of a spot to the distance traveled by the solvent front. Ideally, the values for ''RF'' are equivalent to the R values used in column chromatography. Although the term retention factor is sometimes used synonymously with retardation factor in regard to planar chromatography the term is not defined in this context. However, in column chromatography, the retention factor or capacity factor (''k'') is defined as the ratio of time an analyte is retained in the stationary phase to the time it is retained in the mobile phase, which is inversely proportional to the retardation factor. General definition In chromatography, the retardation factor, ''R'', is the fraction of the sample in the mobile phase at equilibrium, defined a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rest Frame
In special relativity, the rest frame of a particle is the frame of reference (a coordinate system attached to physical markers) in which the particle is at rest. The rest frame of compound objects (such as a fluid, or a solid made of many vibrating atoms) is taken to be the frame of reference in which the average momentum of the particles which make up the substance is zero (the particles may individually have momentum, but collectively have no net momentum). The rest frame of a container of gas, for example, would be the rest frame of the container itself, in which the gas molecules are not at rest, but are no more likely to be traveling in one direction than another. The rest frame of a river would be the frame of an unpowered boat, in which the mean velocity of the water is zero. This frame is also called the center-of-mass frame, or center-of-momentum frame. The center-of-momentum frame is notable for being the reference frame in which the total energy (total relativistic ene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Representative Fraction
The scale of a map is the ratio of a distance on the map to the corresponding distance on the ground. This simple concept is complicated by the curvature of the Earth's surface, which forces scale to vary across a map. Because of this variation, the concept of scale becomes meaningful in two distinct ways. The first way is the ratio of the size of the generating globe to the size of the Earth. The generating globe is a conceptual model to which the Earth is shrunk and from which the map is Map projection, projected. The ratio of the Earth's size to the generating globe's size is called the nominal scale (also called principal scale or representative fraction). Many maps state the nominal scale and may even display a bar scale (sometimes merely called a "scale") to represent it. The second distinct concept of scale applies to the variation in scale across a map. It is the ratio of the mapped point's scale to the nominal scale. In this case 'scale' means the scale factor (also ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Risk Factor
In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often used as a synonym. The main difference lies in the realm of practice: medicine (clinical practice) versus public health. As an example from clinical practice, low ingestion of dietary sources of vitamin C is a known risk factor for developing scurvy. Specific to public health policy, a determinant is a health risk that is general, abstract, related to inequalities, and difficult for an individual to control. For example, poverty is known to be a determinant of an individual's standard of health. Risk factors may be used to identify high-risk people. Correlation vs causation Risk factors or determinants are correlational and not necessarily causal, because correlation does not prove causation. For example, being young cannot be said to caus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
