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PRF , a tense
{{disambiguation ...
PRF may refer to: Science and technology * Physical register file, in CPU design * Platelet rich fibrin * Pontine reticular formation * Positive-real function in mathematics * Programmed ribosomal frameshifting during mRNA translation * Pseudorandom function family * Pulse repetition frequency Organizations * Polícia Rodoviária Federal, the Federal Highway Police of Brazil * Progeria Research Foundation Business * Pasture, rangeland, and forage insurance, a type of crop insurance for livestock growers Other uses * Perfect (grammar) The perfect tense or aspect (abbreviated or ) is a verb form that indicates that an action or circumstance occurred earlier than the time under consideration, often focusing attention on the resulting state rather than on the occurrence itself. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polícia Rodoviária Federal
The Brazilian Federal Highway Police (''Polícia Rodoviária Federal'' or ''PRF'') is a federal highway patrol, subordinate to the Ministry of Justice, whose main function is fighting crime on Brazilian federal roads and highways, as well as monitoring and supervising vehicular traffic, although it has also taken on duties that go beyond its original authority, such as action within Brazilian cities and forests in conjunction with other public safety agencies. It was subordinate to the old National Department of Roadways (''Departamento Nacional de Estradas de Rodagem'' or ''DNER''), now the National Department of Transport Infrastructure (''Departamento Nacional de Infra-Estrutura de Transportes'' or ''DNIT''), until the publication of Law 8,028 of 12 April 1990, which redefined the structure of the Brazilian executive branch. Its competences are defined by article 144 of the Federal Constitution and by Law 9,503 (Brazilian Traffic Code), by Decree 1655 of 3 October 1995 and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Register File
A register file is an array of processor registers in a central processing unit (CPU). Register banking is the method of using a single name to access multiple different physical registers depending on the operating mode. Modern integrated circuit-based register files are usually implemented by way of fast static RAMs with multiple ports. Such RAMs are distinguished by having dedicated read and write ports, whereas ordinary multiported SRAMs will usually read and write through the same ports. The instruction set architecture of a CPU will almost always define a set of registers which are used to stage data between memory and the functional units on the chip. In simpler CPUs, these ''architectural registers'' correspond one-for-one to the entries in a physical register file (PRF) within the CPU. More complicated CPUs use register renaming, so that the mapping of which physical entry stores a particular architectural register changes dynamically during execution. The register ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platelet-rich Plasma
Platelet-rich plasma (PRP), also known as autologous conditioned plasma, is a concentrate of platelet-rich plasma protein derived from whole blood, centrifuged to remove red blood cells. Though promoted to treat an array of medical problems, evidence for benefit is mixed as of 2020, with some evidence for use in certain conditions and against use in other conditions. As a concentrated source of blood plasma and autologous conditioned plasma, PRP contains several different growth factors and other cytokines that can stimulate healing of soft tissue and joints. There are some indications for use in sports medicine and orthopedics (acute muscle strains, tendinopathy and muscle-fascial injuries and osteoarthritis), or dermatology (androgenic alopecia, wound healing, and skin rejuvenation) or even in proctology (fistula-in-ano). For preparation of PRP, various protocols are used, with an underlying principle of concentrating platelets to 3–5 times physiological levels, then injectin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pontine Reticular Formation
The reticular formation is a set of interconnected nuclei that are located throughout the brainstem. It is not anatomically well defined, because it includes neurons located in different parts of the brain. The neurons of the reticular formation make up a complex set of networks in the core of the brainstem that extend from the upper part of the midbrain to the lower part of the medulla oblongata. The reticular formation includes ascending pathways to the cortex in the ascending reticular activating system (ARAS) and descending pathways to the spinal cord via the reticulospinal tracts. Neurons of the reticular formation, particularly those of the ascending reticular activating system, play a crucial role in maintaining behavioral arousal and consciousness. The overall functions of the reticular formation are modulatory and premotor, involving somatic motor control, cardiovascular control, pain modulation, sleep and consciousness, and habituation. The modulatory functions are prim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positive-real Function
Positive-real functions, often abbreviated to PR function or PRF, are a kind of mathematical function that first arose in electrical network synthesis. They are complex functions, ''Z''(''s''), of a complex variable, ''s''. A rational function is defined to have the PR property if it has a positive real part and is analytic in the right half of the complex plane and takes on real values on the real axis. In symbols the definition is, : \begin & \Re (s)0 \quad\text\quad \Re(s) > 0 \\ & \Im (s)0 \quad\text\quad \Im(s)=0 \end In electrical network analysis, ''Z''(''s'') represents an impedance expression and ''s'' is the complex frequency variable, often expressed as its real and imaginary parts; :s=\sigma+i\omega \,\! in which terms the PR condition can be stated; : \begin & \Re (s)0 \quad\text\quad \sigma > 0 \\ & \Im (s)0 \quad\text\quad \omega=0 \end The importance to network analysis of the PR condition lies in the realisability condition. ''Z''(''s'') is realisable as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosomal Frameshift
Ribosomal frameshifting, also known as translational frameshifting or translational recoding, is a biological phenomenon that occurs during translation that results in the production of multiple, unique proteins from a single mRNA. The process can be programmed by the nucleotide sequence of the mRNA and is sometimes affected by the secondary, 3-dimensional mRNA structure. It has been described mainly in viruses (especially retroviruses), retrotransposons and bacterial insertion elements, and also in some cellular genes. Process overview Proteins are translated by reading tri-nucleotides on the mRNA strand, also known as codons, from one end of the mRNA to the other (from the 5' to the 3' end) starting with the amino acid methionine as the start (initiation) codon AUG. Each codon is translated into a single amino acid. The code itself is considered degenerate, meaning that a particular amino acid can be specified by more than one codons. However, a shift of any number of nucleoti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudorandom Function Family
In cryptography, a pseudorandom function family, abbreviated PRF, is a collection of efficiently-computable functions which emulate a random oracle in the following way: no efficient algorithm can distinguish (with significant advantage) between a function chosen randomly from the PRF family and a random oracle (a function whose outputs are fixed completely at random). Pseudorandom functions are vital tools in the construction of cryptographic primitives, especially secure encryption schemes. Pseudorandom functions are not to be confused with pseudorandom generators (PRGs). The guarantee of a PRG is that a ''single'' output appears random if the input was chosen at random. On the other hand, the guarantee of a PRF is that ''all its outputs'' appear random, regardless of how the corresponding inputs were chosen, as long as the ''function'' was drawn at random from the PRF family. A pseudorandom function family can be constructed from any pseudorandom generator, using, for exam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulse Repetition Frequency
The pulse repetition frequency (PRF) is the number of pulses of a repeating signal in a specific time unit. The term is used within a number of technical disciplines, notably radar. In radar, a radio signal of a particular carrier frequency is turned on and off; the term "frequency" refers to the carrier, while the PRF refers to the number of switches. Both are measured in terms of cycle per second, or hertz. The PRF is normally much lower than the frequency. For instance, a typical World War II radar like the Type 7 GCI radar had a basic carrier frequency of 209 MHz (209 million cycles per second) and a PRF of 300 or 500 pulses per second. A related measure is the pulse width, the amount of time the transmitter is turned on during each pulse. After producing a brief pulse of radio signal, the transmitter is turned off in order for the receiver units to hear the reflections of that signal off distant targets. Since the radio signal has to travel out to the target and back ag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Progeria Research Foundation
The Progeria Research Foundation (PRF) is a non-profit organization dedicated to developing treatments and, ultimately, a cure for progeria, a congenital disorder. The Foundation was established in 1999 by the family and friends of Sam Berns, a child with progeria, including Dr. Leslie Gordon and Dr. Scott Berns, his parents, and Audrey Gordon, his aunt.Moore, Keith. Old at Age 3: The Story of Zachary Moore' Old At Age 3, 2007 , pp. 11–13 From their website, the Foundation's mission statement is: "To discover treatments and the cure for Progeria and its aging related disorders." In 2003, The Progeria Research Foundation helped to discover the gene mutation that causes progeria and developed a diagnostic test for it. In 2020 the American Food and Drug Administration approved the use of lonafarnib Lonafarnib, sold under the brand name Zokinvy, is a medication used to reduce the risk of death due to Hutchinson-Gilford progeria syndrome and for the treatment of certain processing- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crop Insurance
Crop insurance is purchased by agricultural producers, and subsidized by the federal government, to protect against either the loss of their crops due to natural disasters, such as hail, drought, and floods, or the loss of revenue due to declines in the prices of agricultural commodities. The two general categories of crop insurance are called crop-yield insurance and crop-revenue insurance. On average, the federal government subsidizes 62 percent of the premium. In 2019, crop insurance policies covered almost 380 million acres. Major crops are insurable in most counties where they are grown, and approximately 90% of U.S. crop acreage is insured under the federal crop insurance program. Four crops—corn, cotton, soybeans, and wheat— typically account for more than 70% of total enrolled acres. For these major crops, a large share of plantings is covered by crop insurance. Specialty crops A farmer or grower may desire to grow a crop associated with a particular defined attribute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
