| HF | Hageman factor; haplotype frequency; hard filled [capsule]; hay fever; head of fetus; head forward; ... |
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| LFT | latex fixation test; latex flocculation test; left fronto-transverse [fetal position]; liver functio... |
| MF | magnetic field; meat free; medium frequency; megafarad; membrane filler; merthiolate-formaldehyde [s... |
| ERA | electrical response activity; electroencephalic response audiometry; Electroshock Research Associati... |
| RR | radiation reaction; radiation response; rate ratio; rational recovery [group]; recovery room; relati... |
| cyclotron frequency | <radiobiology> Number of times per second that a particle orbits a magnetic field line. The frequency is completely determined by the strength of the field and the particle's charge-to-mass ratio. (Often, and incorrectly, called the Larmor frequency. The cyclotron or gyrofrequency is twice the Larmor frequency of precession.) (09 Oct 1997) |
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| hearing loss, high-frequency | Hearing loss in frequencies above 1000 hertz. (12 Dec 1998) |
| high frequency current | An alternating electric current having a frequency of 10,000 or more per second; it produces no muscular contractions and does not affect the sensory nerves. Synonym: d'Arsonval current, Tesla current. (05 Mar 2000) |
| high frequency deafness | Selective loss of hearing acuity for high frequencies, usually associated with neurosensory damage; common in acoustic trauma. (05 Mar 2000) |
| high-frequency jet ventilation | Respiratory support system used primarily with rates of about 100 to 200/min with volumes of from about one to three times predicted anatomic dead space. Used to treat respiratory failure and maintain ventilation under severe circumstances. (12 Dec 1998) |
| high frequency recombination strain | A type of bacterial strain which is able to pass on genetic information to neighboring bacteria at a high rate. The high-frequency recombination strain (Hfr) is able to do this because it possesses the f plasmid and can therefore initiate bacterial conjugation. (09 Oct 1997) |
| high frequency transduction | Specialised transduction in which the donor bacterium contains not only the transducing, defective probacteriophage but also nondefective prophage that serves as "helper" virus, enabling most of the defective prophage particles to develop sufficiently to function as transducing agents. (05 Mar 2000) |
| high-frequency ventilation | Ventilatory support system using frequencies from 60-900 cycles/min or more. Three types of systems have been distinguished on the basis of rates, volumes, and the system used. They are high frequency positive-pressure ventilation (hfppv), high-frequency jet ventilation (hfjv), and high-frequency oscillation (hfo). (12 Dec 1998) |
| nearest neighbor frequency | The frequency by which certain types of entities or structures are immediately adjacent to a given structure. (05 Mar 2000) |
| dominant frequency | The frequency occurring most often in an electroencephalogram. (05 Mar 2000) |
| flicker fusion frequency technique | A technique of perimetry using the criterion of critical fusion frequency. Synonym: flicker fusion frequency technique. (05 Mar 2000) |
| Larmor frequency | In magnetic resonance, the precessional frequency, n0, of magnetic nuclei in a plane perpendicular to the direction of the external magnetic field; v0 = gB0/2π, where B0 is the magnetic field strength and g is the magnetogyric ratio. (05 Mar 2000) |
| frequency | 1. <physics> The number of occurrences of a periodic or recurrent process per unit time, for example the number of vibrations of a particle per second or the number of repetitions of a complete wave form (cycles) per second. 2. <statistics> The number of members of a population or statistical sample falling in a particular class. 3. Relative frequency, the average number of occurrences of a particular event in a large number of repeated trials. (07 Apr 1998) |
| frequency analysis | <ecology, statistics> A method of evaluating vegetation in an area by establishing a transect and counting the occurrences of plant species at various sampling points along the transect. (07 Apr 1998) |
| frequency distribution | A statistical description of raw data in terms of the number or frequency of items characterised by each of a series or range of values of a continuous variable. (05 Mar 2000) |