OSAC Lexicon
The OSAC Lexicon is a compendium of forensic science terms and definitions. This terminology tool was created to help bring consistency and understanding to the way terms are used by the various forensic science. Use of the OSAC Lexicon does not replace the need to reference the original published source.
The terms and definitions in the OSAC Lexicon come from the published literature, including documentary standards and technical reports. It is continually updated with the latest work from OSAC units, as well as terms from newly published documentary standards and standards elevated to the OSAC Registry.
Gradually terms are evaluated and harmonized by the OSAC to a single term. This process results in an OSAC Preferred Term. An OSAC Preferred Term is a term, along with its definition, that has undergone review and evaluation by the FSSB Terminology Task Group and has been approved by the FSSB. The FSSB recommends that subcommittees use OSAC Preferred Terms when drafting standards.
The OSAC Lexicon should be the primary resource for terminology and used when drafting and editing forensic science standards and other OSAC work products.
Observable response(s) indicating desire to avoid a stimulus (may be motivated by fear but can occur without fear; e.g., learned or inherent dislike of a noxious or irritating stimulus)
Training procedure relying on the use of unpleasant stimuli. For example, when a canine receives a correction on the leash as it is lunging for food on the floor in the work environment. Canine learns that lunging for food is an unpleasant experience.
A stimulus that an animal will work to terminate or avoid.
The process in which an animal responds to a signal to avoid unpleasant consequences. (See aversive stimulus.) Example: A canine sits on command to avoid a correction
Observable response(s) that is indicative of a desire to refrain from contact or engagement with a stimulus.
Intentionally pairing a behavior with displeasure to develop a desired outcome. (See avoidance learning.)
The process in which an animal responds to a signal to avoid unpleasant consequences (aversive stimulus). (See avoidance conditioning.)
The pairing of displeasure with a negative behavior in order to extinct the behavior. (See 3.31 avoidance learning.)
A conflict resulting from being repelled by two undesirable goals or stimuli when there are strong pressures to choose one or the other. Often when the conflict is intense the canine will refuse to choose between the alternatives.
A deflagration resulting from the sudden introduction of air into a confined space containing oxygen-deficient products of incomplete combustion.
apparent absorption caused by anything other than the substance for which the analysis is being made.
the signal produced by the entire analytical system apart from the material of interest.
X-rays resulting from scattered Bremsstrahlung and coherently and incoherently scattered tube target peaks.
a recovered sample from a source believed not to have been exposed to pGSR.
Discussion—Background samples can be used to establish a threshold value.
a thin flexible material to which adhesive is applied.
in facial identification, a light source placed behind a subject in a controlled capture that reduces background shadows.
a characteristic of a subject or an object that is illuminated from behind.
a technique that uses high energy electrons that originate from the primary electron beam of the SEM and are elastically reflected by the specimen to create an image of the sample. The probability of backscattering is proportional to atomic number.
a layer applied to the top side of the backing. Its purpose is to coat and fill a porous surfaced backing with a material that is inert to the adhesive formulation to be used.
A canine that is trained, certified, and/or works with more than one certified canine handler.
a class of smokeless powders produced by a process where the final grain morphologies are spherical, flattened-ball, or flake.
one or more colored areas (circular to elongated shape) on a TLC plate produced by the separation of the dye components for a particular combination of solvent and stationary phase. Bands are created as the solvent (mobile phase) moves past and reacts with the solute, migrating from the origin.
Discussion—“Spot” may also be used to describe this area.
Nucleotide sequence database devoted to taxonomic studies and online platform for DNA sequence analysis of cytochrome oxidase I data.
Items used to conceal a target source in order to test the canine to perform the bark indication.
a filter used in fluorescence microscopy that absorbs excitation energy that has been reflected by the sample, selectively transmitting only wavelengths of light greater than the cut-off wavelength, or within a specific wavelength range.
the main high explosive charge.
The normal frequency of occurrence of a specified response per unit of time for that individual canine or group of canines.
The a) BLAST algorithm, and b) a suite of database search programs that implement variations of this algorithm to generate alignments between a nucleotide or protein sequence in a query, and nucleotide or protein sequences within a database.
Refers to a) the BLAST algorithm, and b) a suite of database search programs that implement variations of this algorithm to generate alignments between a nucleotide or protein sequence in a query, and nucleotide or protein sequences within a database.
A set of standards, controls, and/or case samples that are contemporaneously prepared, extracted, and analyzed in a particular sequence
in facial identification, a mode of searching records in an automated system in which a group of probes are simultaneously or sequentially launched.
See batch mode search
The FBI's Biometric Center of Excellence.
Biometric Data Block used in CBEFF.
A rounded mass of resolidified metal on the end of the remains of an electrical conductor or conductors that was caused by arcing and is characterized by a sharp line of demarcation between the melted and unmelted conductor surfaces.
current that impinges on the specimen.
Note—Also referred to as probe current.
a halo observed near the boundary of a transparent particle that is mounted in a medium that differs from the particle’s refractive index.
method for determining the refractive index of a transparent particle relative to its mountant by noting the direction in which the Becke line moves when the focus is changed.
DISCUSSION—The Becke line always moves toward the higher refractive index medium (particle or mountant) when the focus is raised, and towards the lower refractive index medium when the focus is lowered. At the point where the index of the particle matches the index of the mounting medium, the Becke line is no longer visible. The Becke line is generally viewed at a wavelength of 589 nm (the D line of sodium [nD]).
Any measurable, physical response of a canine. Can be voluntary (goal directed) or involuntary (reflexive).
The application of a behavioral technique (e.g., positive reinforcement) to change a behavior.
A series of independent behaviors that are linked together.
A trial where the judge sits as the trier of fact.
primer/case system, designed by Col. Hiram Berdan, having two or more flash holes consisting of a cup, explosive mixture, and covering foil or paper; the anvil is an integral part of the cartridge case head in the bottom of the primer pocket.
A system of processes, checks and testing that may deliver an outcome that has fewer problems and fewer unforeseen complications, and that may combine the attributes of the most efficient and most effective ways of accomplishing a task based on proven and provable methods, while maintaining overall operational integrity and remaining within the bounds of legally accepted practices.
symbol representing the intermediate principal re- fractive index of a biaxial crystal.
Preconception; prejudice; taint; partiality. Since most persons have biases, the issue is whether the bias is such that impartiality cannot be achieved and a fair outcome cannot occur. Any predisposition that a judge or arbitrator may have may be grounds for recusal. Any predisposition that a witness may have may be grounds for impeachment by cross-examination. Any predisposition that a juror may have may be grounds for excusal determined by through a process known as voir dire. This use of the term 'bias' is not that as used in statistical evaluations. (See cognitive bias, contextual bias, and experimental bias.)
An estimate of systematic measurement error, calculated as the difference between the mean of several measurements under identical conditions, to a known true value. It is often reported as a percent difference