Term
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Definition
| Test that uses antibody and antigen complexes as a means of generating a measurable result |
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Term
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Definition
| Antibody: antigen complex |
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Term
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Definition
| Immune response that causes the body to generate antibodies |
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Term
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Definition
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Term
| An antigen can be used as a reagent to detect the presence of what? |
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Definition
| Antibodies in the patient's serum. |
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Term
| If the antibody is present what does it show? |
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Definition
| It shows that the person's body has responded to that specific antigen before |
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Term
| Response that antibodies are present in patient's serum comes from what? |
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Definition
| Previous exposure to an organism or drug or medication in the patient's serum. |
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Term
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Definition
| A protein that is produced by the body in response to an "invading foreign substance". |
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Term
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Definition
| Substance that the body is trying to "fight off" by mounting an immune response. |
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Term
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Definition
| Anything measured by a laboratory test. In immunoassay testing, the anayte may be either an antibody, or an antigen |
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Term
| Immunoassays use one or more select antibodies to detect what? |
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Definition
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Term
| Analytes that are being measured by immunoassays are usually what? |
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Definition
Substances that are naturally present in the body (thyroid hormone)
Substances that the body produces but are not typically present (cancer antigen)
Substances that do not naturally occur in the body (Abused drug) |
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Term
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Definition
| Each site on an antigen that can bind antibodies. Antigenic site to which an antigen can bind. |
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Term
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Definition
| Specificity and affinity for a specific antigen |
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Term
| Antibodies are what type of proteins? |
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Definition
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Term
| What two main structural and functional regions is IgG composed of? |
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Definition
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Term
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Definition
| Contains the antigen binding site |
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Term
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Definition
| Region of constant structure with an antibody class |
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Term
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Definition
| Monospecific antibodies that are the same because they are made by identical immune cells that are clones of a unique parent cell. They bind to the same epitope. |
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Term
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Definition
| Antibodies produced from different B-cell lineages within the body. A collection of immunoglobulin molecules that react against a specific antigen, each identifying a different epitope. |
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Term
| How are polyclonal antibodies produced? |
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Definition
| Polyclonal antibodies are produced when an antigen is injected into an animal such as a rabbit and the rabbit's B-lymphocytes produce IgG antibodies for the specific antigen. They polyclonal IgG is then taken from the rabbit's serum. |
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Term
| Which type of antibodies are more likely to produce false positive results? |
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Definition
| Polyclonal antibodies because they are less specific to antigen epitopes and have various binding affinities |
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Term
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Definition
| The likelihood of separation after the antibody/antigen complex is formed |
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Term
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Definition
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Term
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Definition
| An antibody is said to be specific for the antigen that stimulated it's production. (The homologous antigen) |
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Term
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Definition
| Antibody reacts to an antigen that is structurally similar to the antigen that stimulated its production and can bind to others. |
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Term
| Cross reactivity is closely related to what? |
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Definition
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Term
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Definition
| Binding of an antibody and antigen expressed mathematically |
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Term
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Definition
| Hapten, a low molecular weight antigen that is considered to have only 1 epitope. |
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Term
| The affinity for the Hp is related to what? |
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Definition
| The chance or likelihood to bind to the complementary nature of each antigen or antibody |
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Term
| What doe immunoassays require to measure the amount of antigen or antibody present? |
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Definition
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Term
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Definition
| A molecule that will react as part of the assay and in doing so will produce a signal that can be measured in the solution. ( Radioactive compound or enzyme that causes a change in color) |
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Term
| Radioactive (radionuclides) |
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Definition
| Atoms with unstable nuclei that spontaneously emit radiation |
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Term
| What are the two types of radioactive labels used in the clinical lab? |
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Definition
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Term
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Definition
| The emitted electrons of a radionuclide (radioactive substance) |
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Term
| What is the radio nuclide that is used commonly in cellular immunology assays? |
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Definition
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Term
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Definition
| Electromagnetic radiation from an unstable nuclei |
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Term
| Radionuclides releases more energy and become more stable when? |
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Definition
| When they disintegrate or decay |
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Term
| Half life of radionuclide |
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Definition
| Time needed for 50% of the nuclide to decay. |
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Term
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Definition
| Detects the energy released from a radionuclide |
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Term
| What does the energy released during decay of a radionuclide excite? |
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Definition
| A fluor which releases a photon of light |
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Term
| The photon of light released by a fluor can be amplified and detected by what? |
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Definition
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Term
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Definition
| Measures products formed by photometric, fluorometric or chemilum methods |
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Term
| Examples of enzymes labels are? |
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Definition
Horseradish peroxidase
Biologic catalysts (increase the rate of reaction but not consumed by the reaction) |
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Term
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Definition
| Fluorochromes or fluorphores which absorb radiant energy of 1 wavelength and emit energy at a longer wavelength in less than 10-1 seconds. |
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Term
| Fluorescent labels can be detected using what? |
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Definition
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Term
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Definition
| Emit a photon of light as the result of a chemical or biochemical reaction |
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Term
| What is a common example of a luminescent label? |
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Definition
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Term
| Labeled ligand assays include |
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Definition
Isotopic-RIA (Beta and Gamma)
EIA
FIA/FPIA
Luminescence
Chemi
Bio |
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Term
| Unlabeled immunoassays include |
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Definition
Direct (RID)
Nephelometry
Turbidometry |
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Term
| Immunoassay methodologies are |
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Definition
Noncompetitive and competitive immunoassays
Homogenous and Heterogeneous immunoassays |
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Term
| The measurement of an analyte in an immunoassay is achieved by using either |
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Definition
| A competitive or a noncompetitive format |
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Term
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Definition
| Unlabeled analyte (usually antigen) in the test sample is measured by its ability to competed with the labeled antigen in the immunoassay |
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Term
| Why does the unlabeled antigen block the ability of the labeled antigen to bind? |
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Definition
| Because that binding site on the antibody is already occupied. |
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Term
| In competitive immunoassay less label measured in the assay means what? |
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Definition
| More of the unlabeled (test sample) antigen is present |
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Term
| The amount of antigen in the test sample is what? |
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Definition
| Inversely related to the amount of label measured in the competitive format |
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Term
| One step competitive format |
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Definition
| Both the labeled antigen reagent and the unlabeled specimen (or test sample analyte) compete for a limited amount of antibody |
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Term
| Two-step competitive format |
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Definition
| Antibody concentration of the reaction solution larger than the concentration of the antigen. Antibody is incubated with specimen containing antigens of interests and then in the second step, labeled antigen is added |
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Term
| Noncompetitive Method is also known as the what? |
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Definition
| Sandwich method and it is a direct relationship |
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Term
| Noncompetitive assay provides the highest level of what? |
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Definition
| Assay sensitivity and specificity a |
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Term
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Definition
| Assay in which analytes are bound (sandwiched) between two highly specific antibody reagents |
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Term
| Examples of noncompetitive assays include |
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Definition
| Critical analytes such as cardiac and hepatic markers. |
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Term
| Two step noncompetitive assay |
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Definition
| Includes wash steps in which the sandwich binding compelex is isolated and washed to remove excess unbound label reagent and any other interfering stubstances. |
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Term
| Which assay offers the highest specificity and sensitivity of all the assays? |
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Definition
| Two-step noncompetitive assay |
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Term
| In noncompetitive assays, the measurement of labeled analyte, usually antibody is what? |
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Definition
| Dierctly proportional to the amount of antigen present in the sample. |
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Term
| The directly proportional relationship of noncompetitive assays can be measured by using what? |
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Definition
| Dose response curve. The more antigen that is present, the more labeled antibody that will bind. |
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Term
| Heterogeneous Immunoassay Methods |
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Definition
| Immunoassay methods that require separation of bound antibody/antigen complex |
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Term
| Homogeneous Immunoassay Methods |
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Definition
| Immunoassay methods that do not require separation of the antibody/antigen complex |
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Term
| Homogenous methods have been generally applied to the measurement of what? |
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Definition
| Abused and therapeutic drugs. They are much easier and faster to perform because they do not require separation of the bound antibody/antigen complex. |
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Term
| Heterogeneous immunoassays require the separation of what? |
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Definition
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Term
| Heterogeneous immunoassays have what compared to homogenous immunoassays? |
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Definition
| A better sensitivity and specificity |
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Term
| Heterogeneous competitive immunoassays involve |
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Definition
| Antigen excess and labeled competing antigen. RIA is the prototype |
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Term
| Heterogeneous noncompetitive immunoassays involve |
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Definition
| Antibody excess and secondary labeled antibody. ELISA is the prototype (Enzyme linked, immunoabsorbant assay) |
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Term
| Which heterogeneous immunoassay can be automated? |
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Definition
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Term
| The separation step is a key in the design of automated heterogeneous immunoassays. What are some common approaches to automated separation? |
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Definition
Immobilized antibodies
Capture/filtration
Magnetic separation |
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Term
| Immobilized antibody methods include |
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Definition
Coated tube
Coated bead
Solid phase antibody methods |
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Term
| Homogeneous immunoassays do not require separation of |
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Definition
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Term
| Homogenous immunoassays have what compared to heterogeneous immunoassays |
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Definition
| A better speed and adaptability |
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Term
| Virtually all homogeneous immunoassays are |
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Definition
One-site (Monoclonal)
Competitive
Designed for small antigens such as therapeutic/abused drugs and steroid/peptide hormones |
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Term
| Enzyme-multiplied immunoassay technique (EMIT) |
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Definition
| Developed by Syva Corporation in the 1970's and is now owned by Behrin Diagnostics. It offered an alternative to RIA or HPLC for measuring therapeutic drugs |
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Term
| What did EMIT spark the widespread use of? |
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Definition
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Term
| EMIT is used for what two types of applications |
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Definition
| Quantitative (TDM) and qualitative (DAV) |
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Term
| What is the most common use of EMIT methods? |
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Definition
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Term
| Depending on the type of application EMIT can be either |
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Definition
| Homogeneous or heterogeneous |
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