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Ident > Fluorescence > Flashcards

Fluorescence Flashcards

1
Q

What is fluorescence?

A

The emission of light by a substance which has absorbed light or other electromagnetic radiation.
Emitted light has longer wave length, lower energy than the absorbed light

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2
Q

What does fluorescence allow us to do?

A

Render latent impressions visible
Enhance friction ridge details
Eliminate backgrounds
Increase contrast between impression and background

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3
Q

What are the two filters?

A

Exciter filter - built into the light source machine - blocks all unwanted wavelengths resulting in a color beam.

Barrier filter - placed on front of camera lens AND In front of your eyes - lens and glasses same color

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4
Q

Most useful light and wavelength at crime scene to trigger fluorescence is?

A

Blue at approx 450 NM. (Hair fibers teeth bones untreated fingerprints etc)

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5
Q

What is ultraviolet UV light?

A

Electromagnetic radiation with a wave length shorter than that of visible light but longer than x rays

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6
Q

What is visible light?

A

Electromagnetic radiation that is visible to the human eye and is responsible for the sense of sight
Wavelength in 400-700 nm range

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7
Q

3 main chemical dyes used during forensic examination

A

Ardrox, brilliant yellow, rhodamine6g

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8
Q

Barrier filter is…

A

Placed in front of camera lens to block unwanted light emitted by light source

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9
Q

Fingerprint technique where metals are evaporated in a vacuum

A

VMD. Vacuum metal deposition

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10
Q

When warmed, produces fumes that react with invisible fingerprint residues to form white polymer?

A

CA. Cyanoacrylate

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11
Q

Process to remove tape to examine adhesive side of tape

A

Un-du or compressed air. (You undue the tape)

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12
Q

Fingerprint technique most commonly used on dry porous

A

Indanedione zinc chloride or DFO. - dfo double dip and oven

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13
Q

3 factors to consider when deciding to use a chemical technique.

A

Substrate
Value of item
Matrix
History of exhibit
Seriousness of offense
Practicality
Damage to item surroundings
Time elapsed between deposition and development of print.

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14
Q

An impression of friction ridges of all or any part of a finger

A

Finger print or fingermark

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15
Q

What does LASER stand for

A

Light amplification by stimulated emission of radiation

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16
Q

Reference material that can be used for chemical development methods

A

Fingermark visualization manual

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17
Q

When flashlight is low as possible swept across floor looking for impression in dust

A

Grazed lighting

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18
Q

The three heights of light to photograph a 3d footwear impression

A

Ankle, knee, hip. Think of the 3 3 and 3 from the tripod hangar session

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19
Q

3 pieces of ppe to be worn in lab

A

Lab coat. Eye protection. Gloves

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20
Q

What sheets are to be reviewed prior to using any chemical

A

Safety data sheets SDS

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21
Q

A label that the employer produces for use In the workplace that contains a chemical process info on safe handling precautions and reference to SDS

A

WHMIS workplace label

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22
Q

When using LASER. The goggles must have a minimum of this optical density factor.

A

OD4. O.01% of light transmitted

23
Q

Name 5 things the SDS provides

A

Hazard identification
Handling and storage
Info on ingredients
Identification of product
First aid measures
Fire- fighting measures
transport information
Stability and reactivity

24
Q

What decade was cyanoacrylate first used?

A

1970’s

25
Q

4 premises of fingerprint identification ?

A

Friction ridges develop on the fetus in their definitive form before birth
Friction ridges are persistent throughout life except for permanent scarring
The specific friction ridge patterns and details in small areas of fingerprints are unique and never repeated
Overall friction ridge patterns vary within limits which allow for clsssification

26
Q

Why is friction skin unique?

A

Random timing - time if differentiation 15-17 weeks.
Random growth- ridge thickness and thinness is random path a ridges take is random, ridge alignment is random, pore locations and size are random
Random pressures. - pressures from size and shape if volar pads , pressure from neigbouring ridges in womb, numerous genetic and physical pressure

27
Q

Dry origin footwear - you can only lift can’t enhance with powders. Electrostatic dust lifter or gel lift . When I’m doubt- assume it is of dry origin.

Wet origin- involve moisture goes on wet and eventually dries. Wet origins you can always enhance with powders etc.

A

Same as above

28
Q

What is grazed lighting?

A

Right along the surface parallel to surface. Dust particles reflect the light dust impressions best viewed and photographed with grazed lighting.

29
Q

What is oblique lighting?

A

Up from surface. But not 90 degrees

30
Q

What is the best way to preserve an impression?

A

Good photography is the best way to preserve

31
Q

Gel lifter begins to break down at what temperatures?

A

40c and -15 degrees

32
Q

Dental stone mixture ratio

A

5 parts dental stone. 2 parts water

33
Q

Three measurements of tires

A

Wheelbase
Front track width
Rear track width

34
Q

What is luminescence ?

A

Spontaneous emission of light by a substance not resulting from heat
Ex: fireflies bioluminescence

35
Q

What is fluorescence ?

A

The emission of light from a substance which has absorbed light or other electromagnetic radiation Emitted light has a longer wave length and therefore lower energy than absorbed light

36
Q

Physical object comparison: what is similar to:

A

Pieces could have a common origin there are corresponding class characteristics but insufficient RAC’s are present.

37
Q

Where is the noise treatment pattern applied?

A

In the curing mould. The ribs carry the noise treatment pattern.

38
Q

What is the 225/17/65 on tires

A

225- section width- measured at tire widest point in mm Includes side wall.
17- Rim diameter measured in inches
65- aspect ratio - % of height and width (height divided by width) bottom of side wall to top of tire. Not entire height of tire

39
Q

What is noise treatment?

A

The varied arrangement of the different pitch length of the tread elements around the circumference of a tire.

40
Q

What are sipes?

A

The thin strips cut cut across the surface to increase traction in wet or icy conditions. Winter tires have more sipes

41
Q

What are the three areas we need for wheel measurements?

A

Wheelbase
Front track width
Rear track width

Where the measurement stops is referred to as the leading edge.

42
Q

Two ways to search for tires

A

Tire book (tire design guide)
Send Jpg images to search in CPSIC

43
Q

What do we need to have in order to process a suspect vehicle for tires?

A

We need legal authority- who has the right to privacy on the vehicle We need consent from owner, need consent to process.

44
Q

Tire DOT number

A

Has 12 numbers. Sometimes 8 on one side. 4 on the other. The last 4 numbers are the week and year tires were made. 3909. 39th week of 09. Write this on test impression.

45
Q

What are the range of opinions for footwear?

A

Inconclusive
Exclusion
identification
Association of class characteristics
Higher degree of association

46
Q

What are the two principles of physical evidence comparison?

A

1) principle of uniqueness
2) principle of identification

47
Q

4 reasons we use fluorescence?

A

Enhance friction ridge details
Eliminate backgrounds
Render latent impressions visible
Increase contrast between impressions and background

48
Q

What is bloodstain pattern analysis?

A

The examination of size, shape, location and distribution pattern of bloodstains, in order to provide an interpretation of the physical events that gave rise to their origin.

49
Q

Things to include in a rough sketch

A

Compass north direction
Date and time sketch was made
Address/location
Reference points used
Who drew rough sketch
Who took measurements
Other pertinent info

50
Q

What type of pattern does hand milling produce?

A

Pantograph. (S type shape in example. There will always be slight differences

51
Q

Name types of outsole manufacturing?

A

Injection molding
Compression molding (waffle iron)
Open pour molding

52
Q

What samples would we collect at autopsy scene?

A

Toxicology Burt Fraser
DNA
Biology

53
Q

True or false… in an autopsy it is our responsibility to make note of injuries and testify to their nature

A

False

54
Q

What is the premises of bloodstain patterns?

A

(Predictable and reproducible )

Basic pattern types that are reproducible and distinguished from one another in most cases.

Ident (17 decks)

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