Glossary
Terms starting with H
271 definitions · page 2 of 5.
- HEAT CAPACITY
- The amount of heat necessary to raise the temperature of a given mass one degree. Heat capacity may be calculated by multiplying the mass by the specific heat.
- HEAT GAIN
- an increase in the amount of heat contained in a space, resulting from direct solar radiation, heat flow through walls, windows, and other building surfaces, and the heat given off by people, lights, equipment, and other sources.
- HEAT LOSS
- A decrease in the amount of heat contained in a space, resulting from heat flow through walls, windows, roof and other building surfaces and from exfiltration of warm air.
- Heat of Passion information
- A term common in criminal law, as a mitigating factor in murder charges, that to some extent excuses or condones, by reducing the grade of the charge, where the violence was the product of sudden and uncontrollable anger cause by reasonable provocation.
- HEAT PUMP
- An air-conditioning unit which is capable of heating by refrigeration, transferring heat from one (often cooler) medium to another (often warmer) medium, and which may or may not include a capability for cooling. This reverse-cycle air conditioner usually…
- HEAT RATE
- A number that tells how efficient a fuel-burning power plant is. The heat rate equals the Btu content of the fuel input divided by the kilowatt-hours of power output.
- HEAT STORM
- Heat storms occur when temperatures exceed 100 degrees Fahrenheit over a large area for three days in a row. Normal hot temperatures cause electricity demand to increase during the peak summertime hours of 4 to 7 p.m. when air conditioners are straining to…
- HEAT TRANSFER
- Flow of heat energy induced by a temperature difference. Heat flow through a building envelope typically flows from a heated, or hot area to a cooled, or cold area.
- heat-shock protein
- One of a number of proteins appearing in a cell after the cell has been subjected to elevated temperatures.
- HEATING DEGREE DAY
- A unit that measure the space heating needs during a given period of time.
- HEATING LOAD
- The rate at which heat must be added to a space in order to maintain the desired temperature within the space.
- HEATING SEASONAL PERFORMANCE FACTOR
- A representation of the total heating output of a central air-conditioning heat pump in Btus during its normal usage period for heating, divided by the total electrical energy input in watt-hours during the same period, as determined using the test procedure…
- HEATING VALUE
- The amount of heat produced by the complete combustion of a given amount of fuel.
- heavy metal
- A descriptive term for rock bands since the 1970s whose heavily amplified electric and percussion sounds have been associated with youthful rebellion and defiance.
- HEAVY WATER
- A type of hydrogen atom that may be used as fuel for fusion power plants. Also called DEUTERIUM, it is found in abundance in the seas.
- HEDGING CONTRACTS
- Contracts which establish future prices and quantities of electricity independent of the short-term market. Derivatives may be used for this purpose. (See Contracts for Differences, Forwards, Futures Market, and Options.)
- Heir Apparent information
- An heir whose interest in taking cannot be extinguished, so long as he or she outlives.
- Heirs information
- Those who inherit real property or personal property.
- heliacal rising
- the period of time when an object, such as a star, is briefly seen in the eastern sky before dawn and is no longer hidden from the glare of the sun
- helicase
- A protein that unwinds DNA at replication forks.
- HELIOCHEMICAL
- Using solar radiation to cause chemical reactions.
- heliosphere
- a vast region around the sun dominated by the solar wind
- HELIOTHERMAL
- A process that uses the sun's rays to produce heat.
- helium
- the second lightest element; consists of two protons, and usually two neutrons and two electrons; about 8 percent of the atoms in the universe are helium
- helix-turn-helix (HLH) protein
- A protein in which a domain which forms two helices separated by a loop that acts as a sequence-specific DNA binding domain. HLH proteins are thought to act as transcription factors.
- helix-turn-helix motif
- Configuration, found in some DNA-binding proteins, consisting of a recognition helix and a stabilizing helix separated by a short loop.
- Help Desk Software Information
- Help Desk software is the common name for several internet based computer programs designed to assist a company in the management of a wide and varied customer base or a large inventory. The help desk is essential in large concerns and is generally managed…
- hemizygous
- The condition of loci on the X chromosome of the heterogametic sex of a diploid species. Or more generally when one part of the genome, in a normally diploid species, is present in only one copy.
- hemizygous gene
- A gene present in only one copy in a diploid organism for example, X-linked genes in a male mammal.
- Herbes de Provence
- A mixture of heady herbs from the south of France made up of any combination of basil, thyme, oregano, marjoram, bay, sage, rosemary and summer savory (some recipes also call for lavender and dried orange peel, among other flavourings). The Mediterranean…
- heredity
- The biological similarity of offspring and parents.
- heritability
- A measure of the degree to which the variance in the distribution of a phenotype is due to genetic causes. In the broad sense it is measured by the total genetic variance divided by the total phenotypic variance. In the narrow sense it is measured by the…
- heritability in the narrow sense
- The proportion of phenotypic variance that can be attributed to additive genetic variance.
- hermaphrodite
- An individual with both male and female genitalia. (1) A plant species in which male and female organs occur in the same flower of a single individual (compare monoecious plant). (2) An animal with both male and female sex organs.
- Herring
- A North Atlantic fish that's rich oils. Herring stocks are suffering from the effects of overfishing and ecological changes, so herring is less widely available than it once was. Usually sold whole, herrings can be poached, fried or grilled as well as…
- Hertz
- a unit of frequency equal to one cycle per second
- HERTZ
- A unit of electromagnetic wave frequency that is equal to one cycle per second. - It is named after Henrich R. Hertz.
- heterochromatin
- Densely staining condensed chromosomal regions, believed to be for the most part genetically inert. chromatin that remains tightly coiled (and darkly staining) throughout the cell cycle. See euchromatin
- heteroduplex
- A DNA double helix formed by annealing single strands from different sources; if there is a sequence difference between the strands, the heteroduplex may show single strand loops or bubbles (unpaired regions).
- heteroduplex analysis
- Duplex DNA formed by strands from different sources, referred to as a heteroduplex, will have loops and bubbles in regions where the two DNAs differ. Electron microscopic observation (analysis) of this DNA has been a useful tool in recombinant DNA work.
- heteroduplex DNA model
- A model that explains both crossing over and gene conversion by assuming the production of a short stretch of heteroduplex DNA (formed from both parental DNAs) in the vicinity of a chiasma.
- heteroduplex mapping
- The use of heteroduplex analysis to determine the location of various insertions; deletions; or heterogeneities between two DNA molecules.
- heterogametic sex
- The sex with (usually) two heteromorphic (differently shaped) sex chromosomes (for example, X and Y). During meiosis it produces two kinds of gametes in regard to these sex chromosomes.
- heterogeneous nuclear mRNA (hnRNA)
- The original RNA transcripts found in eukaryotic nuclei before post-transcriptional modifications. A diverse assortment of RNA types found in the nucleus, including mRNA precursors (pre-mRNA) and other types of RNA.
- heterokaryon
- A cell that contains two or more nuclei from different origins. A cell composed of two different nuclear types in a common cytoplasm.
- heterokaryon test
- A test for cytoplasmic organelle mutations (eg. mitochondrial or chloroplast mutations), based on new associations (recombination) of phenotypes in cells derived from genetically marked haploid heterokaryons. Since the heterokaryons are haploid and produce…
- heteromorphic chromosomes
- A chromosome pair with some homology but differing in size, shape, or staining properties. Homologous chromosome pair which are not morphologically identical (eg the sex chromosomes).
- heterophony
- (heter-off-ony) A texture in which two or more variations of the same melody are performed simultaneously, common in folk music.
- heteroplasmon
- A cell containing a mixture of genetically different cytoplasms, generally different mitochondria or different chloroplasts.
- heteroplasmy
- The existence within an organism of genetic heterogeneity within the populations of mitochondria or chloroplasts.
- heterothallic
- A botanical term used for organisms in which the two sexes reside in different individuals.
- heterothallic fungus
- A fungus species in which two different mating types must unite to complete the sexual cycle.
- heterotroph
- Organism requiring an organic form of carbon as a carbon source.
- heterozygosity
- A measure of the genetic variation in a population; with respect to one locus, stated as the frequency of heterozygotes for that locus.
- heterozygote
- An individual having a heterozygous gene pair. A diploid or polyploid with different alleles at a particular locus.
- heterozygote advantage
- A selection model in which heterozygotes have the highest fitness.
- heterozygous gene pair
- A gene pair having different alleles in the two chromosome sets of the diploid individual for example, Aa or, A1A2.
- hexachord
- the six usable degrees of the modal scale, often used to organize Renaissance music.
- Hexadecimal color-notation system
- A way of defining colors. Uses RGB scheme and associates a two digit hexadecimal number with each base color (red, green and blue).
- hexaploid
- A cell having six chromosome sets, or an organism composed of such cells.