identification code The unique code assigned to each generator, transporter, and treatment, storage, or disposal facility by regulating agencies to ease identification and tracking of chemicals or hazardous waste. Also called EPA I.D. Number.
idiopathic Denoting a disease of unknown cause.
igneous Produced under conditions involving intense heat, as rocks of volcanic origin.
ignitable Capable of burning or causing a fire.
illness A condition of pronounced deviation from the normal healthy state; sickness. Illness can be the result of disease or injury.
imhoff cone A clear, cone-shaped container marked with graduations. The cone is used to measure the volume of settleable solids in a specific volume (usually one liter) of water.
immediate biochemical oxygen demand
immediately dangerous to health and life (idhl) The maximum level to which a healthy individual can be exposed to a chemical for 30 minutes and escape without suffering irreversible health effects or impairing symptoms. Used as a level of concern.
immission level A descriptor for noise exposure, in decibels, representing the total sound energy incident on the ear over a specified period of time (e.g., months, years).
immune suppressants Agents that block or restrict the activity of one or more components of the immune system, usually leading to increased susceptibility to infectious disease.
immunity The resistance usually associated with possession of antibodies that have an inhibitory effect on a specific microorganism (or its toxin) that causes a particular infectious disease. See resistance.
immunity, active Resistance developed in response to stimulus by an antigen (infecting agent or vaccine) and usually characterized by the presence of antibody produced by the host.
immunoassay specificity A performance characteristic determined by conducting cross-reactivity studies with structually similar substances that may be present in the analyte matrix. Specificity studies are determined with each new lot of polyclonal antibodies used in the immunoassay. For monoclonal antibody, each subsequent new lot is usually characterized by biochemical and biophysical techniques in lieu of comprehensive specificity studies.
immunity, herd The resistance of a group to invasion and spread of an infectious agent, based on the resistance to infection of a high proportion of individual members of the group. The resistance is a product of the number susceptible and the probability that those who are susceptible will come into contact with an infected person.
immunity, passive Immunity conferred by an antibody produced in another host and acquired naturally by an infant from its mother or artificially by administration of anantibody-containing preparation (antiserum or immune globulin).
immunodeficient Lacking in the ability to produce antibodies in response to an antigen.
immunotoxins Monoclonal antibodies coupled with toxins that are capable of delivering the toxin moiety to a target cell.
impact noise A reverberant type of impulsive noise.
impeller A rotating set of vanes designed to impart energy to fluids and pump or lift water.
impermeable Not easily penetrated. The property of a material or soil that does not allow (or allows only with great difficulty) the movement or passage of water.
impermeable strata Layers of rock or sediment that do not allow the transmission of water.
impervious area A hard surface area (e.g., parking lot) that prevents or retards the entry of water into the soil, thus causing water to run off the surface in greater quantities and at an increased rate of flow.
impoundment A body of water or sludge confined by a dam, dike, floodgate, or other barrier.
impulse noise A nonreveberant type of impulsive noise.
impulsive noise Impulsive noise is characterized by a sharp rise and rapid decay in sound levels and is less than 1 second in duration. For the purpose of this document, it includes impact or impulse noise.
IMViC test A group of tests used to differentiate Escherichia and Enterobacter.
in-channel use See instream use.
inches of mercury The name comes from the use of mercurial barometers that equate the height of a column of mercury with air pressure. One inch of mercury is equivalent to 33.86 millibars or 25.40 millimeters.
incidence Number of new cases of a disease occurring within a particular population during a specified period of time.
incidence of tumors Percentage of animals with tumors.
incidence rate A measure of the frequency with which an event, such as a new case of illness, occurs in a population over a period of time. The denominator is the population at risk; the numerator is the number of new cases occurring during a given time period.
incident command post A facility located at a safe distance from an emergency site, where the incident commander, key staff, and technical representatives can make decisions and deploy emergency manpower and equipment.
incident command system (ICS) The organizational arrangement wherein one person, normally the Fire Chief of the impacted district, is in charge of an integrated, comprehensive emergency response organization and the emergency incident site, backed by an Emergency Operations Center (EOC) with staff, resources, information, and advice.
incineration Burning combustible organic materials to remove the water and reduce the remaining residues to a safe, non-burnable ash. The ash can then be disposed of safely.
incineration at sea Disposal of waste by burning at sea on specially-designed incinerator ships.
incinerator A furnace for burning organic maeterial under controlled conditions, leaving only ash.
incompatible waste A waste unsuitable for mixing with another waste or material because it may react to form a hazard.
increased sampling Quarterly sampling that must be performed when a system exceeds the MCL for a given contaminant.
inclining-block rate See increasing-block rate.
increasing-block rate A pricing structure for which the dollar amount charged per unit of water (such as dollars per gallon) increases with the amount of water usage. Also inclining block rate.
incremental cost The additional cost associated with adding an increment of capacity.
incremental shaft encoder A component of a tide gauge for converting length to a shaft angle on a rotating disk. The position of the rotating disk is determined by single or dual optical or magnetic sensors to provide an electrical output. No electro-mechanical components or gears are used, so extremely low torque is required to move the float wheel, wire, and float mechanism.
incubation The process of holding microbial cultures under certain conditions, especially at a certain temperature, favorable to their growth.
incubation period A period of subclinical or inapparent pathologic changes following exposure, ending with the onset of symptoms of infectious disease.
independent variable An exposure, risk factor, or other characteristic being observed or measured that is hypothesized to influence an event or manifestation (the dependent variable).
index temperature A temperature which denotes the beginning of a specific event such as 28 degrees Fahrenheit. The 28 degree temperature denotes a freeze that can damage plants.
Indian spring low water A datum described by an elevation depressed below mean sea level by an amount equal to the sum of the amplitudes of the harmonic constituents M2, S2, K1, and O1.
Indian tide plane Same as Indian spring low water.
indicator 1) Chemical. A substance that gives a visible change, usually of color, at a desired point in a chemical reaction, generally at a specific end point. 2) Instrumentation. A device which indicates the result of a measurement. Most indicators in the water utility field use a fixed scale and movable indicator (pointer) such as a pressure gauge or a movable scale and movable indicator like those on a circular-flow recording chart. Also called a receiver. 3) Biological. An organism or collection of organisms having relatively narrow requirements and thus indicating the presence of certain environmental conditions.
indicator organism See indicator.
indictment The formal statement of the charges against an individual presented by a grand jury.
indigenous Of a native species; not introduced.
indirect discharge Introduction of pollutants from a non-domestic source into a publicly owned waste-treatment system. Indirect dischargers can be either commercial or industrial facilities.
indirect source Any facility or building, property, road or parking facility that attracts motor vehicle traffic and, indirectly, causes pollution.
indirect transmission The transmission of an agent carried from a reservoir to a susceptible host by suspended air particles or by animate (vector) or inanimate (vehicle) intermediaries.
indirect waste pipe A drain pipe used to convey liquid wastes that does not connect directly with the drainage system, but which discharges into the drainage system through an air break into a vented trap or a properly vented and trapped fixture, receptacle, or interceptor.
individual water system A small water system, not owned or operated by a water utility, that serves less than five residences or farms that do not have access to a public water system.
indoor air pollution Chemical, physical, or biological contaminants in the breathing air inside a habitable structure or conveyance.
indoor climate Temperature, humidity, lighting, and noise levels in a habitable structure or conveyance. Indoor climate can affect indoor air pollution.
inducer A chemical or conditional change that activates the expression leading to the production of a desired product. A small molecule which interacts with a regulator protein and triggers gene transcription.
industrial pollution prevention Combination of industrial source reduction and toxic chemical use substitution.
industrial source reduction Practices that reduce the amount of any hazardous substance, pollutant, or contaminant entering any waste stream or otherwise released into the environment. Term includes equipment or technology modifications, substitution of raw materials, and improvements in housekeeping, maintenance, training or inventory control.
industrial waste Unwanted materials from an industrial operation; may be liquid, sludge, solid, or hazardous waste.
industrial wastewater Wastewater in which wastes from industrial processes predominate.
inequality A systematic departure from the mean value of a tidal quantity. See diurnal inequality, parallax inequality, and phase inequality.
inertial flow A solution of the relative hydrodynamic equations of motion in which only the horizontal component of the Coriolis and centrifugal forces are balanced. This anticyclonic flow results from a sudden application and release of a driving force which then allows the system to continue on under its own momentum without further interference.
inertial separator A device that uses centrifugal force to separate waste particles.
inert material A material that is not very reactive, such as a noble metal, plastic, or cement.
infection The entry and multiplication of an infectious agent in body tissues of man or animal resulting in cellular injury. An infection may be either apparent (called manifest)—the infected person appears to be sick, or inapparent—there is no outward sign that an infectious agent has entered that person at all.
infectious agent An organism, usually a microorganism, but including helminths, that is capable of producing infection or infectious disease.
infectious disease A disease of man or animal resulting from an invasion of the body by pathogenic agents and the reaction of the tissues to these agents and/or the toxins they produce.
infectious waste Hazardous waste with infectious characteristics including: contaminated animal waste, human blood and blood products, isolation waste, pathological waste, and discarded sharps (needles, scapels, or broken medical instruments).
infectivity The proportion of persons exposed to a causative agent who become infected by an infectious disease.
inference, statistical In statistics, the development of generalizations from sample data, usually with calculated degrees of uncertainty.
infiltration 1) The gradual flow or movement of water into and through (to percolate or pass through) the pores of the soil. Also see percolation. 2) the penetration of water from the soil into sewer or other pipes through defective joints, connections, or manhole covers.
infiltration gallery A subsurface groundwater collection system, typically shallow in depth, constructed with open jointed or perforated pipes that discharge collected water into a water-tight chamber. From this chamber, the water is pumped to treatment facilities and into the distribution system. Infiltration galleries are usually located close to streams or ponds and may be under the direct influence of surface water.
infiltration rate Quantity of water (usually measured in inches) that will enter a particular type of soil per unit time (usually one hour).
infiltration test Field or lab tests used to measure the permeability or hydraulic conductivity of a porous media as a liquid passes through it. These tests are usually used to analyze a soil profile.
infiltrometer A device by which the rate and amount of water infiltration into the soil is determined.
inflow Entry of extraneous rainwater into a sewer system from sources other than infiltration, such as basement drains, manholes, storm drains, and street washing.
influent Water or other liquid (raw or partially treated) flowing into a reservoir, basin, treatment process, or treatment plant.
information The formal statement of the charges against an individual in a misdemeanor, issued by the US or Commonwealth’s Attorney and not by a grand jury. It may always be used in misdemeanor prosecutions, and may be used in felony prosecutions only if the defendant waives his right to be indicted.
information file In the Superfund program, a file that contains accurate, up-to-date documents on a Superfund site. The file is usually located in a public building convenient for local residents.
information system The organized collection, processing, transmission, and dissemination of information in accordance with defined procedures, whether automated or manual.
information technology (I/T) The computer hardware, software, and telecommunications operated by an organization to accomplish a function.
ingestion Type of exposure through the mouth.
ingestion exposure pathway A term referring to exposure primarily from ingestion of water or foods such as milk and fresh vegetables that have been contaminated with radiation. The duration of primary exposure could range in length from hours to months.
inhalation The term used when radioactive materials are taken into the lungs by breathing.
inhibitor 1) A substance that slows or prevents growth or reproduction of an organism. 2) A substance that sharply reduces corrosion, when added to water, acid, or other liquid in small amounts.
initial base sampling The initial round of sampling required for contaminants under Phase II and Phase V.
initial compliance period The first full three-year compliance period which begins at least 18 months after promulgation. For all regulated contaminants, the initial compliance period is the first full three year compliance period beginning at least 18 months after promulgation with the exception of waterworks with 150 or more service connections for contaminants listed at Table 2.3, VOC 19-21; Table 2.3, SOC 19-33; and antimony, beryllium, cyanide (as free cyanide), nickel, and thallium which shall begin January 1993.
initial detention
initial nuclear radiation Nuclear radiation emitted from the fireball and the cloud column during the first minute after a nuclear explosion.
injection well A well into which fluids are injected for purposes, such as waste disposal, improving the recovery of crude oil, or solution mining.
injection zone A geological formation receiving fluids through a well.
injunction An order issued by the court requiring a defendant to do or refrain from doing a specified act.
inland high wind warning for hurricane force winds Announcement issued for force winds 74 mph (64 knots) or greater within 12 hours.
inland high wind watch for hurricane force winds Announcement issued for hurricane force winds 74 mph (64 knots) or greater within 24 hours.
in-line filtration The addition of chemical coagulants directly to the filter inlet pipe. The chemicals are mixed by the flowing water. Flocculation and sedimentation facilities are eliminated. This pretreatment method is commonly used in pressure filter installations. Also see conventional filtration and direct filtration.
innovative technology A new or inventive method that effectively treats wastes and reduce risks to human health and the environment.
innovative technology evaluation A program to promote development and use of innovative treatment technologies.
inoculate To introduce a seed culture into a system.
inoculation The artificial introduction of microorganisms into a culture medium or into the human body.
inoculum The material containing microorganisms which is used for inoculation.
inorganic Of mineral origin. Material such as sand, salt, iron, calcium salts and other mineral materials. Inorganic substances are of mineral origin, whereas organic substances are usually of animal or plant origin. Also see organic.
inorganic chemicals Chemical substances of mineral origin, not of basically carbon structure.
inorganic matter
inorganic waste Waste material such as sand, salt, iron, calcium, and other mineral materials that are not converted in large quantities by organism action.
in personam Against the person.
input horsepower The total power used in operating a pump and motor.
input HP = (brake HP)(100%)/motor efficiency,%
in rem Against the thing.
insecticide Any substance or chemical formulated to kill or control insects.
in situ In place, the original location, in the natural environment.
in situ hybridization Hybridization with an appropriate probe carried out directly on a chromosome preparation or histological section.
in-situ stripping Treatment system that remove or strips volatile organic compounds from contaminated ground or surface water by forcing an airstream through the water and causing the compounds to evaporate.
inspection and maintenance (I/m) Activities that assure a wastewater treatment plant (and other anti-pollution facilities and processes) controls work properly.
instability Occurs when a rising air parcel becomes less dense than the surrounding air. Since its temperature will not cool as rapidly as the surrounding environment, it will continue to rise on its own. Contrasts with stable air.
institutional wastewater
instream flow River and stream waters that maintain stream quality, aquatic life, and recreational opportunities.
instream uses Water uses that can be carried out without removing the water from its source, as in navigation and recreation.
instructional multimedia A form of computer-based training that incorporates a mix of media as the stimulus to the student. Possible media elements include sound, animation, graphics, video, text; whatever it takes to get the instructional message across to the target audience. (See Multimedia)
instructional television fixed services (ITFS) A band of low-power microwave frequencies set aside by the Federal Communications Commission (FCC) exclusively for the transmission of educational programming, and licensed to public institutions. ITFS is typically used in urban areas and requires a specialized antenna. Receiving sites require a converter capable of changing signals to those used by a standard television set.
intangible losses Items of loss or damage for which a market price is not available or does not define magnitude. These include loss of life, creation of public health hazards, inconvenience to transportation, etc.
integrated exposure assessment A summation over time, in all media, of the magnitude of exposure to a toxic chemical.
integrated information system The coordination, blending, or uniting of data and information into a unified whole. Integration does not require a singular system, but it does require compatibility and/or interoperation of systems through data and communication standards.
integrated pest management (IPM) A mixture of chemical and other, non-pesticide, methods to control pests.
integrated resource planning An open and participatory planning process emphasizing least-cost principles and a balanced consideration of supply and demand management options for meeting water needs.
integrated services digital network (ISDN) Digital network with higher speed than found on the traditional telephone network. Even though ISDN uses existing phone lines, it does require specialized equipment. Because the network is all digital it can easily send voice, data, and video over the same line simultaneously.
integrated waste management Using a variety of practices to handle municipal solid waste; can include source reduction, recycling, incineration, and landfilling.
integrator A device or meter that continuously measures and calculates (adds) total flows in gallons, or million cubic feet or some other unit of volume measurement. Also called a totalizer.
intended use plan A document prepared each year by the state that identifies the intended uses of funds in the State Revolving Fund and describes how those uses support SRF goals.
interaction A relationship in which each component influences the other.
interactive video Combination of a videodisc (usually laserdisc) or videotape and computer system that permits user response and participation, allowing for direct exchanges between user and software or among people. This instructional medium has limited use today.
interceptors Larger sewer lines that, in a combined system, control the flow of the wastewater to the treatment plant. In a storm, they allow some of the wastewater to flow directly into a receiving stream. This protects the treatment plant from being overloaded in case of a sudden surge of water into the sewers. Interceptors are also used in separate sanitation systems to collect the flows from main and trunk sewers and carry them to the points of treatment. Also interceptor sewers.
interceptor sewers See interceptors.
interchangeable connection An arrangement or device that will allow alternate but not simultaneous use of two sources of water.
interface The common boundary layer between two substances, such as water and a solid (metal); or between two fluids, such as water and a gas (air); or between a liquid (water) and another liquid (oil).
interflow The lateral movement of water in the unsaturated zone during and immediately after a precipitation event. The water, moving as interflow, discharges directly into a stream or lake.
interim (permit) status Period during which treatment, storage and disposal facilities coming under RCRA are temporarily permitted to operate while awaiting a permanent permit.
interlock An electrical switch, usually magnetically operated. Used to interrupt all (local) power to a panel or device when the door is opened or the circuit exposed to service.intermediate groundwater
intermediate regional flood The intermediate regional flood is sometimes referred to as the 100-year flood. This does not mean that a flood of this magnitude will occur every 100 years, but over a long period of time, for example, such as 500 years, it would be equaled or exceeded an average of five times. It is conceivable that floods of this magnitude could occur during two consecutive years. Another way to view a 100-year flood would be to say that it has a one percent chance of occurring during any year.
intermittent filter A water treatment filter or a wastewater treatment contactor that is dosed intermittently rather than continuously.
intermittent noise Noise levels that are interrupted by intervals of relatively low sound levels.
internal corrosion Corrosion that occurs inside a pipe because of the physical, chemical, or biological interactions between the pipe and water as opposed to forces acting outside the pipe, such as soil, weather, or stress conditions.
internal friction Friction within a fluid (water) due to cohesive forces.
internal tide A tidal wave propagating along a sharp density discontinuity, such as a thermocline, or in an area of gradually changing (vertically) density.
international low water A hydrographic datum, proposed in 1919 and not yet been generally adopted, was to be "a plane so low that the tide will but seldom fall below it."
Internet A worldwide network of computer networks. It is an interconnection of large and small networks around the globe. The Internet began in 1962 as a resilient computer network for the U.S. military and over time has grown into a global communication tool of more than 12,000 computer networks that share a common addressing scheme.
Internet courses Students participate in the class by using the Internet for all or part of the coursework. The instructor posts a Web page which contains all relevant course information and assignments. Communication between students and instructors occurs by e-mail.
interquartile range The central portion of a distribution, calculated as the difference between the third quartile and the first quartile; this range includes about one-half of the observations in the set, leaving one-quarter of the observations on each side.
interrogatories Written questions propounded by one party and served on the other party in a suit, who must serve written answers thereto under oath within a given period of time.
interspecies extrapolation model Model used to extrapolate from results observed in laboratory animals to humans.
interstate Between one state and anyplace outside of that state, or within the District of Columbia or any other territory.
interstate carrier water supply A source of water for drinking and sanitary use on planes, buses, trains, and ships operating in more than one state. These sources are federally regulated.
Interstate Commerce Clause A clause of the U.S. Constitution which reserves to the federal government the right to regulate the conduct of business across state lines.
interstate water Waters that flow across or form part of state or international boundaries, e.g., the Potomac River or coastal waters.
interstice A very small open space in a rock or granular material. Also called a void or void space. See pore.
interstitial monitoring The continuous surveillance of the space between the walls of an underground storage tank.
intertidal Of or related to the region of marine shoreline between the high-tide mark and low-tide mark; where neap, spring, and storm tides are important.
intertidal zone The zone between the mean higher high water and mean lower low water lines.
intertropical convergence zone (ITCZ) The axis dividing the southeast trades from the northeast trades, toward which the surface winds tend to converge The easterly trade winds of both hemispheres converge at an area near the equator called the "Intertropical Convergence Zone (ICTZ)", producing a narrow band of clouds and thunderstorms that encircle portions of the globe.
interval See lunitidal interval and lunicurrent interval.
Intranet Inter-connected network within one organization that uses Web technologies for the sharing of information internally, not world wide. Such information might include organization policies and procedures, announcements, or information about new products.
intrastate Within a state.
intrusive borehole test Technique that measures resistivity, conductivity, radioactive properties, velocity, density, and other physical properties, depending on the tool used. The specific borehole tools are lowered down hole and the data are recorded continuously either digitally and/or by hard copy.
Inventory, TSCA Inventory of chemicals produced pursuant to Section 8 (b) of the Toxic Substances Control Act (TSCA).
inverse barometer effect The inverse response of sea level to changes in atmospheric pressure. A static reduction of 1.005 mb in atmospheric pressure will cause a stationary rise of 1 cm in sea level.
inversion In meteorology, a condition in which cooler surface air is trapped under an upper layer of warmer air preventing vertical circulation.
invertebrate Any animal lacking a backbone, e.g., insects, spiders, crustaceans, segmented worms, round and flatworms, molluscs, etc.
investment The commitment of funds for purposes of obtaining an economic return over a period of time, usually in the form of periodic cash flows and/or terminal value. The first cost plus interest during construction.
investor-owned utility A private utility owned by investors and typically regulated by a state public utility commission.
in vitro In glass; a laboratory experiment performed in a test tube or other vessel.
in vitro studies Studies of chemical effects conducted in tissues, cells, or subcellular extracts from an organism (i.e., not in the living organism).
in vivo Within a living organism; a laboratory experiment performed in which the substance under study is inserted into a living organism.
in vivo studies Studies of chemical effects conducted in intact, living organisms.
invoice A document that accompanies merchandise and contains at least the following information: (a) origination and destination of merchandise; (b) local consignee; (c) description of merchandise including any marks, etc.; (d) quantity, (e) purchase price.
IOC Inorganic compound or chemical.
ion An electrically charged atom, radical (such as SO42-) or molecule formed by the loss or gain of one or more electrons.
ionic concentration The concentration of any ion in solution, usually expressed in moles per liter.
ion exchange treatment A common water-softening method found on a large scale at water purification plants that remove some organics and radium by adding calcium oxide or calcium hydroxide to increase the pH to a level where the metals will precipitate out.
ionization The splitting or dissociation (separation) of molecules into negatively and positively charged ions.
ionization chamber A device that measures the intensity of ionizing radiation.
ionizing radiation Radiation that can strip electrons from atoms, i.e., alpha, beta, and gamma radiation.
ion-specific/selective electrode
ipso facto By the act itself.
irradiated food Food subject to brief radioactivity, usually gamma rays, to kill insects, bacteria, and mold, and to permit storage without refrigeration.
Irminger Current A North Atlantic Ocean current setting westward off the south-west coast of Iceland.
irradiation Exposure to radiation of wavelengths shorter than those of visible light (gamma, X-ray, or ultraviolet) for medical purposes, to sterilize water, milk or other foodstuffs, or disinfect wastewater, or to induce polymerization of monomers or vulcanization of rubber.
irreversible effect Effect characterized by the inability of the body to partially or fully repair injury caused by a toxic agent.
irrigation To supply agricultural land with water by artificial means.
irrigation district A cooperative, self-governing public corporation set up as a subdivision of the State government, with definite geographic boundaries, organized and having taxing power to obtain and distribute water for irrigation of lands within the district; created under the authority of a State legislature with the consent of a designated fraction of the landowners or citizens.
irrigation efficiency The amount of water stored in the root zone compared to the amount of irrigation water applied.
irrigation return flow Surface and subsurface water that leaves the field following application of irrigation water.
irrigation scheduling An automated method for optimizing outdoor water use by matching the watering schedule to plant needs.
irrigation water use Artificial application of water on lands to assist in the growing of crops and pastures or to maintain vegetative growth in recreational lands such as parks and golf courses.
irritant A substance that can cause irritation of the skin, eyes, or respiratory system. Effects may be acute from a single high level exposure, or chronic from repeated low-level exposures to such compounds as chlorine, nitrogen dioxide, and nitric acid.
isanostere An isopleth of either specific volume anomaly or thermosteric anomaly.
isobar An isopleth of pressure or line drawn on a weather map connecting points of equal barometric pressure.
isobaric surface A surface of constant or uniform pressure.
isohaline 1) An isopleth of salinity. Constant or uniform in salinity. 2) In an organism, the property of being in balance with the salt concentration of its surroundings.
isopach map A map showing areas of an aquifer or geologic formation of the same thickness.
isopleth A line of constant or uniform value of a given quantity. See isanostere, isobar, isohaline, isopycnic, and isotherm.
isopycnic An isopleth of density. Constant or uniform in density.
isotherm A line of a map connecting points having the same temperature at the same time.
isotope A variation of an element that has the same atomic number of protons, but has a different weight because of the number of neutrone. Various isotopes of the same element may have different radioactive behaviors, some are highly unstable.
isotropy The condition in which the property or properties of interest are the same when measured along axes in any direction.
I/T investment An expenditure of money and/or resources for I/T or I/T-related products, services, and support involving managerial, technical, and organizational risk for which there are expected benefits to the organization's performance. These benefits are defined as improvements either in efficiency of operations or effectiveness in services.