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Forensic Micrscopy

Exactly what it says on the tin

ISO International Organization for Standarization
ASTM American Society for Testing and Materials, International
ASCLD-LAB American Society of Crime Lab Directors- Lab Accreditation Board
Chain of custody documentation of location of evidence from the time it is obtained to the time it is presented in court
AFTE Association of Firearms and Toolmarks Examiners
Toxicology chemical analysis of bodily fluid and tissues to determine if a drug or poison is present.
Datum A fixed point of reference for all three-dimensional measurements
Artifact Human-made or modified portable object
Feature Non-portable artifact
Matrix Surrounding material (soil, water, or a living room)
Provenance Origin and deviation of an item in a three-dimensional space, in relation to the datum ad other items
Context The relationship between items and the surroundings where they are found
1. duty of the FO Detain any potential suspects
2. duty of the FO Render medical assistance to those who need it
3. duty of the FO Do not destroy, alter, or add evidence at the scene
4. duty of the FO Prevent others, even superiors, from mucking with the evidence
MSDS Material Safety Data Sheet
Universal Precautions Require employees to treat all human blood, body fluids, and other materials as if they are infected
Evidence Information that is given in a legal investigation to make a fact or proposition seem more or less likely
Trier-of-fact Whoever determines the guilt of innocence
Proxy data Remnants of events left behind
Demonstrative evidence Prepared later to help the trier-of-fact understand complex testimony
Conclusive evidence Evidence so strong as to overbear any other evidence to the contrary
Cirscumtantial evidence Evidence based on inference and not personal knowledge or observation
Conflicting evidence Irreconcilable evidence that comes from different sources
Corroborating evidence Evidence that differs from but strengthens or confirms other evidence
Derivative evidence Evidence that is discovered as a result of of illegally obtained evidence and is therefore inadmissible because of the primary taint
Exculpatory evidence Evidence tending to establish a criminal defendant's innocence
Foundational evidence Evidence that determines the admissibility of other evidence
Hearsay Testimony that is given by a witness who relates what others have said
Incriminating evidence Evidence tending to establish guilt or from which a fact-trier can establish guilt
Presumptive evidence Evidence deemed true and sufficient unless discredited by other evidence
Prima facie evidence Evidence that will establish a fact or sustain a judgement unless contradictory evidence is produced
Probative evidence Evidence that tend to prove or disprove a point in issue
Rebuttal evidence Evidence offered to disprove or contradict the evidence presented by the opposing party
Tainted evidence Evidence that is inadmissible because it was directly or indirectly obtained by illegal means
Direct transfer Transferred from object A to object B
Indirect transfer Involves one or more intermediate objects
Contamination Any transfers that take place after the action surrounding the crime has stopped
Class Group of objects with similar characteristics
Questioned evidence Evidence for which the original source is unknown
Known evidence Evidence for which the original source is known
Coincidental Associations Two things which have previously never been in contact with each other have items on them which any anatomically indistinguishable at a certain class level
Type I error False positive, saying something is blood when it is not
Type II error False negative, saying something is not blood when it is
Simple magnification system A single lens used to form an enlarged image of an object
Compound magnification system Magnification occurs in two stages
Lens Material that bends light in a known and predictable manner
Focal length Distance between two points of focus on either side of the lens
Resolution Minimum distance two things can be separated and still be distinguished as two objects (d=λ/2NA)
Numerical aperture Angular measure of the lens' light-gathering ability (NA=nsinμ) μ being half the angle of aperture of the objective
Eyepiece/ocular Lens that an observer looks into
Field of view The area seen through the eyepieces
10x/0.25na/170mm/0.17Plan Apo 10 times magnification, 0.25 numerical aperture, 170mm tube length, 0.17mm recommended coverslip thickness, plan apochromat corrected
Condenser Used to obtain a bright, even field of view and improve image resolution
Kohler illumination Sets light rays parallel throughout the lens system
Refractive index N = c/v, where c is the speed of light in a vacuum (186000 miles per second) and v is the speed of light in the material
Snell's Law n1sinθ1=n2sinθ2
Isotropic Optically the same throughout, only one refractive index
Anisotropic Optical properties that vary with orientation of incoming light, has an ordinary and extraordinary ray
Birefringence Division of light into the ordinary and extraordinary ray when it passes through certain types of material (n=ne-no)
Fluoresence The luminescence of a substance excited by radiation, emission stops when the excitation stops
Phosphorescence Characterized by long-lived emission
TEM Transmission electron microscope
SEM Scanning electron microscope
Electromagnetic radiation Various types of energy in the form of waves
Wavelength Distance between corresponding points on two adjacent waves (c=λ/v) where c is the speed of light, λ is the wavelength, and v is the frequency
Frequency The number of waves that pass a given point in one second
Photon Tiny packets of energy (E=hv or hc/λ)
Electromagnetic spectrum High energy. Gamma, X-rays, Ultraviolet, Visible, Infared, Microwave, Radio. Low energy
Microspectrophotometry Used for comparing colors, measures UV and visible light spectra
Beer's Law Relates the amount of absorbing substance present to the quantity of absorbance of light
Analyte Substance or substances being identified
Solvent Liquid or liquid solution that is used to dissolve an analyte
Solute Substance that is dissolved in a solvent
Partitioning Competition of two solvents for an analyte
Adsorption Process whereby a solid, liquid or gaseous analyte is attracted to the surface of a dissolving molecule
Gas chromatography The most versatile form of chromatography
Electrophoresis Type of chromatography that relies on the role of an electric field
Hairs Fibrous growths that originate from the skin of mammals
Epidermis Outer layer of the skin
Follicle Structure within which hairs grow
Keratin Tough, protein-based material from which hairs, nails, and horns are made
Keratinization Hardening process of hair growth
Sebaceous glands In the follicle, produces oils that coat hairs helping to keep them soft and pliable
Pili arrector Tiny muscles that raise hairs
Anagen First stage of hair growth, follicle produces new cells
Catagen Second stage of hair growth, follicle begins to shut down production of cells
Melanin/Pigment Small coloured granules that give hairs their particular color
Melanocytes Specialized cells that produce melanin/pigment
Eumelanin Dark brown pigment
Pheomelanin Lighter pigment
Root bulb/club root Root condenses into this during the catagen phase of hair growth
Telogen Resting phase for hair growth, root is held in place only by a mechanical connection
Root Portion that was formerly in the follicle
Tip Distal-most portion of the hair
Shaft Main portion of the hair
Cuticle Series of overlapping series of scales that forma protective covering
Imbricate Human scale pattern
Cortex Structure that makes up the bulk of the hair
Cortical fusi Small bubbles that may appear in the cortex
Ovoid bodies Odd structures that look like large pigment granules and may appear irregularly in the cortex
Guard hairs Large stiff hairs that make up the outer part of an animal's coat
Shield Widening in guard hairs in the upper half of the shaft
Buckling Abrupt change in direction of the hair shaft with or without a slight twist
Shouldering Asymmetrical cross-section of hairs
Pili annulati Hairs with colored rings
Monilethrix Makes hairs look like strings of beads
Pili torti Twisting of the hair along its length, creating a spiral morphology
Natural fiber Any fiber that exists as a fiber in its natural state
Manufactured fiber Any fiber derived by a process of manufacturing from any substance that, at any point, is not a fiber
Filaments Type of fiber having indefinite or extreme length
Staple fibers Natural fibers or cut lengths of filament 7/8 in - 8 in
Denier Weight in grams of 9000 m of the material fibrous
Yarn Term for continuous strands of textile fibers, filaments, or material in a form suitable for entangling to form a textile fabric
Plied yarn Yarn composed of several smaller strands of yarn twisted together
Fabric Textile structure produced by interlacing yarns, fibers, or filaments with substantial surface area relative to its thickness
Synthetic fibers Manufactured fibers that are synthesized from a chemical compound
Soil Contains both organic (humus) and inorganic (crushed rock and clay) material
Glass Amorphous solid, usually transparent
Coatings Any surface coating designed to protect, aesthetically improve, or provide some special quality, coloquially: paint
Paint Suspension of pigments and additives designed to color of protect a surface
Binder That portion of the coating that allows the pigment to be distributed across the surface
Vehicle Solvents, resins, and other additives that form a continuous film, binding the pigment to the surface
Microtome A device that holds a sample in place while a heavy and very sharp knife slices off sections a few tens of microns thick
Bertillonage First system of identification, used anthropometric measurements
Friction ridges Leave fingerprints, found on the palms, soles, and ends of fingers and toes
Patent print Fingerprint in some medium, blood, clay, fresh paint
Latent print Composed of the sweat and oils of the body that are transferred from the ridge pattern to some substrate
Minutiae Ridge characteristics
Loop One or more ridges entering from one side, curving back on themselves, and exiting the fingertip on the same side
Arch Ridges enter the print, gradually rise, and exit the opposite side
Tented Arch Arches with a pronounced sharp peak
Whorl Have type lines and at least two deltas, can be plain, central pocket, double loop, and accidental
AFIS Automated Fingerprint Identification System
Exemplar Known, authentic writing sample
Requested writing Writing samples taken from someone for the purpose of comparison with a questioned document
Non-requested writing Examples of subject's writing taken in the normal course of personal or business transactions
Formal signature Written carefully on an official document, name is not in doubt
Informal signature Used in routine correspondence where you want the person to recognize the name but the spelling isn't important
Stylistic signature Used in signing checks, credit card receipts, looks like a scribble
Document alterations Obliterations, erasures, additional markings, indented writings, and charred documents
Obliteration Overwriting of a sample of writing or printing with another writing instrument
Abrasive erasure Removing writing with an abrasive eraser material
Chemical erasure Dissolving or bleaching ink so it is no longer visible
Indented writing An image of the writing on one or more pages below
ESDA Electrostatic Detection Apparatus
Rifling Series of lands and grooves down the inside of a gun barrel
Striations Impressions of the interior barrel surface made on a bullet as it passes through the gun
Bore Diameter of a circle that touches the tops of the lands
Caliber Refers to the size of a particular ammunition cartride
Gauge Diameter of the shotgun barrel
Firing pin impression Mark made by the firing pin as it strikes the primer cap
Extraction/Ejection marks Marks indicative of the method of cartridge extraction or ejection
Trigger pull The force required to pull the trigger to the firing position
Gunshot residue Cloud of molten metals, partially burned gunpowder flakes, smoke, and other microscopic debris expelled when the gun fires
Footwear impression When a piece of footwear comes into contact with a recipient material or object
Imprint Made when there is enough residue to leave an impression on the recipient surface
Frye General acceptance within the particular scientific field to which it belongs
Daubert Falsifiability, knowledge of error rates, peer review, general acceptance, general acceptance
Created by: Dragoness