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forensics s2 > Unit 9- Hair and Fibers > Flashcards

Unit 9- Hair and Fibers Flashcards

1
Q

Fibers are considered to be ________ because they are generally _______

A

class evidence, mass produce

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2
Q

Fibers are used to

A

create a link between crime scenes and subjects.

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3
Q

Fibers can originate from many different sources:

A

carpeting, clothing, linens, furniture, insulation, rope/ligature, tape, paper

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4
Q

Two General Types of Fibers:

A

1) Natural
derived from animal hairs or plants
2) Synthetic
man-made

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5
Q

Natural Fibers: Animal Hairs

A

Sheep (wool); most common
Goat (mohair and cashmere)
Camel (wool)
Llama
Alpaca (wool)
Fur βibers from mink, rabbit, beaver, etc.
Silk (βiber from the cocoon of the silkworm)

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6
Q

Natural Fibers: Plant Fibers

A

cotton most common; ribbon-like shape with irregular twists
βlax (linen)
ramie
sisal often used in linen rugs
jute often used in ropes
hemp common name for cannabis for industrial/non-drug use;
typically used for rope or sack
kapok fiber from kapok tree seed pods; used in pillows and
mattress stuffing
coir coconut husks; used in carpet and rugs

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7
Q

Acrylics

A

> wool-like; soft and warm
quick drying and resistant to moth

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8
Q

Rayon

A

> cellulose-derived regenerated thin βiber

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9
Q

Acetates

A

> cellulose-based wrinkle resistant βiber

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10
Q

Nylon

A

> also common; elastic and strong
lustrous and silk-like when stretched
βirst created by DuPont in 1935

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11
Q

Kevlar

A

> light, but strong synthetic βiber developed by DuPont in 1965
heat resistant
typically used for bullet-proof vests, military applications, racing
tires, etc.

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12
Q

Nomex

A

> a variation of Kevlar
βire resistant
used by firemen and disaster response teams

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13
Q

Fiber

A

> a fine, slender piece of thread or filament

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14
Q

Yarn

A

> a twisted aggregate of fibers

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15
Q

Textile

A

> woven fibers; fabric

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16
Q

Weaving

A

Lengthwise threads (warps) are woven by crosswise threads (wefts) in a repeated pattern.

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17
Q

Plain

A

> firm; tends to wrinkle

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18
Q

Basket

A

> not very durable
shrinks when washed

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19
Q

Satin

A

> not durable
shiny surface

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20
Q

Twill

A

very strong, dense and compact, but soft

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21
Q

Leno

A

> open weave
easily distorted

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22
Q

Microscopic Comparisons

A

> color
diameter
surface markings
delustering agent (TiO2 added to reduce shine)

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23
Q

Polarized Light Microscopy

A

determines birefringence using polarized light
(difference between two refractive indices)

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24
Q

Fourier Transform Infrared Spectroscopy (FTIR)

A

analysis of chemical composition based on their ability to absorb light at different wavelengths

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25
Q

UV/Visible Microspectrophotometry

A

distinguishes slight/subtle color differences based on absorption of light at different wavelengths in the ultraviolet and visible range

26
Q

Significance of Fiber Evidence

A

The Questioned fiber could have originated from the known sample.
The Questioned fiber did not originate from the source represented by
the known sample.

27
Q

The number of fibers is _______ to the likelihood of actual contact (i.e., the greater the number of fibers, the more likely that contact actually occurred).

A

directly proportional

28
Q

Hair ƒ‹”

A

a slender threadlike outgrowth from the follicles of the skin of mammals

29
Q

Keratin ‹•ˆ‘—†ƒŽŽ‘˜‡”‘—”„‘†›

A

a protein that makes up most of the hair shaft

30
Q

Pigment (gives hair its color)

A
  • melanin
  • pheomelanin (redheads only)
31
Q

Cortex ‘”–‡š

A

the main body of a hair (wooden portion of a pencil)

32
Q

Medulla

A

the central cells of the cortex (the lead of a pencil); not always present

33
Q

cuticle

A

a layer of scales covering the hair shaft (a layer of yellow paint on a pencil)

34
Q

proximal end

A

root

35
Q

distal end

A

tip

36
Q

ovoid bodies

A
  • spheric to oval structure
  • mostly found in cattle and dog hairs, but also in some human hairs Ž•‘‹•‘‡
    Š—ƒŠƒ‹”•
37
Q

cortical fusi

A

elongated spindle-shaped air spaces in the cortex

38
Q

anagen phase

A
  • active growth stage
    -ribbon like tip
  • found with follicular tag
39
Q

catagen phase

A

intermediate stage of growth

40
Q

telogen phase

A
  • resting stage
  • has a bulb like shape
  • often found with very little pigment
  • often found with abundance of cortical fusi
41
Q

hairs that are forcibly removed often end up with a ____ attached to the proximal end

A

follicular tag

42
Q

Postmortem root band (dead man’s. root)

A

a dark band that may appear near the root of the hair originating from a decomposing body

43
Q

pigments

A

human: constant color and pigmentation throughout the hair shaft
animal: often seen with radical color changes

44
Q

medulla

A

Human: thin and amorphous
Animal: wide, regular, well-defined, repeated patterns

45
Q

scale structures

A

Human:
- overlapping imbricate scales
- flattened with narrow margins
Animal:
- imbricate scales
- crown-shaped coronal scales
- petal-shaped spinous scales

46
Q

caucasian

A
  • moderate shaft diameter with very little variation
  • light to moderate pigment density with fairly even distribution
  • oval- shaped cross section
47
Q

mongoloid

A
  • coarse shaft diameter
  • streaky pigments with heavy density
  • thick cuticle
  • round cross-section
48
Q

negroid

A
  • fine to moderate shaft diameter
  • considerable variation throughout the hair shaft with prominent twists curls
  • heavy pigment density with aggregate pigment clumpings
  • flat cross-section
49
Q

head hairs

A

-much longer than other hair types
-soft
- have artificial treatment

50
Q

pubic hairs

A
  • often coarse in diameter with wide variations
  • prominent “buckling”
51
Q

limb hairs (arm or leg)

A
  • fine diameter with little variation
  • arc-like gross appearance
  • usually tapered or abraded
52
Q

facial hairs (beard/mustache)

A

-very course diameter with irregular or triangular cross-section
- very broad and continuous medulla
- often with double medulla
- stiff texture

53
Q

chest hairs

A
  • moderate and variable shaft diameter
  • tip often dark in color
  • long and fine
  • arc-like gross appearance
  • granular medulla
  • stiff
54
Q

axillary hairs

A
  • less buckling.
  • medulla similar to limb hairs
  • fine tip
55
Q

eyebrow and eyelash

A

stubby and sabber like appearance

56
Q

fur hair vs guard hair in animals

A

fur: fine diameter, designed for insulation
guard: coarse diameter, designed for protection

57
Q

pili annulati

A

ringed or banded hairs

58
Q

trichorrhexis nodosa

A

conspicuous nodes due to immuneodefiency or small bowel disorder

59
Q

information provided by hair examination

A
  • human or animal
  • race
  • where in the body
60
Q

information not provided by hair examanation

A

age and gender

61
Q

hair may be used to distinguish identical twins who

A

cannot be distinguised based on their DNA because of environmental effects

62
Q

polyester

A
  • wrinkle resistance.
  • cotton

forensics s2 (8 decks)

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