Marble run activity

We did a marble run activity (quite long ago). Group mates: Crisann, Wanying, Jesslyn, Jolene (memememe), Qingxun

The video of our marble run (: it didn't manage to last for very long but I think it was quite good

and here is a picture of our marble run :)

CSI practical last week; 17.08

My predictions:

Sample	My predictions
Sample 1	It may be blood as it has the shade of red blood has
Sample 2	It is not blood as it looks orange, not even the colour of diluted blood
Sample 3	It probably is not blood as it looks pink
Sample 4	It is probably blood. It looks like blood, but more diluted
Sample 5	It looks too brown to blood. It could, however, be blood mixed with soil.

After test 1, samples proving positive: 3,4,5




After test 2, samples proving positive: 4,5




After test 3, the sample proving to be positive is 4.

Also we did more about DNA. Here's my DNA:

DNA II

Egg has 23 pairs of chromosomes, sperm 23 pairs chromosomes -> meiosis (reduction) = 23 pairs

A female has only X chromosomes, however a male has both X and Y chromosomes (thus it is more likely to have a girl?)

If there is an extra chromosome, it means that the person has down syndrome.

Turner's syndrome = XO (O has 22 pairs of chromosomes but not X chromosome)
Klinelfer's syndrome = XXY (this is a male that has both sexual organs, e.g. have male genitalia but have breast development.)
Super Male = XYY (with this extra Y chromosome, more male hormones produced. The person may be more aggressive)
Super Female = XXX
-> may suffer from other things, like intelligence is lower, THESE PEOPLE ARE MOSTLY STERILE
when you have 2, one is suppressed and one is expressed
when you have 3, the other 2 is suppressed and one is expressed

All homosapiens need at least 1 X chromosome. A Y chromosome by itself will be aborted.

Sometimes, due to the body rejecting the genetic defects of the child, the child may be aborted (e.g. after 2 weeks of pregnancy sudden miscarriage)

DNA cannot be in a chromosome all the time (chromosomes are genes wrapped around a protein)
2 repressive genes will be expressed

O- OO
A- AA/AO
B- BB/BO
AB
think my parents are AO and OO since I have a brother who is A too.

Homework: read up on DNA (:

DNA notes

To get DNA
- blood (white blood cell! rbc has no nucleus, so no DNA)
- hair
- skin under nail
- saliva (like envelop licked area, cigarette butt)
- if it's rape, vagina swipe to find sperm
- sweat
- skin cells

Evidence	Possible location of DNA	Source
baseball bat	handle, end	sweat, skin, blood tissue
eyeglasses	nose or ear pieces	lens, sweat, skin
facial tissue, cotton swab	surface area	mucus, blood, sweat, ear wax
used cigarette	cigarette butt	saliva
stamp or envelop	licked area	saliva
blanket, pillow, sheet	surface area	swear, hair, urine, saliva
fingernail, partial fingernail	scarping	blood sweat, tissue

drugs can be found in your urine

DNA: look at 5 base pairs, THEY STILL MAY BE THE SAME EVEN THOUGH HIGHLY LIKELY.

Blood splatter analysis

Analysis:
- This was done on the floor before being lifted up. There are circular droplets of blood that show that the angle of impact is 90°, meaning it is done on the floor.
- It can also show the handedness of the person through the way the person drew the circle. The direction of the circle was probably clockwise (since the start is usually more concentrated), which means the person is right-handed.

Blood splatter activity: part 2!

Analysis of blood splatters
From the previous experiment, I gathered that all my hypotheses, namely:
- The higher the angle of elevation, the longer the blood splatter
- The higher the angle of elevation, the narrower the blood splatter
- The further the origin of the blood splatter, the wider the diameter of the blood splatter
were true.

Explanations
Height:
The height would affect the velocity of the blood, since higher height means the blood has more gravitational potential energy (which could then convert to more kinetic energy). Higher velocity will affect the diameter of the blood.

Angle of impact:

Since the blood splatter is elongated, the width becomes narrower. The angle of impact will increase when the difference between the length and width is greater (since sin is a ratio of opposite/hypotenuse)

Another factor that affects the blood splatter is the texture. Taken from rambio: Rough surfaces have protuberances that rupture the surface tension of the blood drop and produce spatter and irregularly shaped parent strains with spiny or serrated edges. Also, the volume of blood would naturally cause a bigger blood splatter.

According to this, I know that analysing the blood splatters can probably tell us the origin of the attack (the point where the assailant stabbed the victim). Looking at the slide on rambio, it can also tell:

• Type and velocity of weapon
• Number of blows
• Handedness of assailant (assailants tend to strike with their dominant hand on the opposite side of the victim's body)
• Position and movements of the victim and assailant during and after the attack
• Which wounds were inflicted first
• Type of injuries
• How long ago the crime was committed
• Whether death was immediate or delayed
• Blood spatters can lead to the recreation of a crime because of how blood behaves (which would be based on knowing the origin of attack :D)

Blood splatter activity (:

Blood splatter 1

Blood splatter 2

Blood splatter 3

Blood splatter 4

Blood Splatter Pattern from a Laboratory Experiment by Mr Leong TK & Chua HL

1. What is shape of blood splatter?
The blood splatter is round.

2. Describe any other characteristic of the splatter.
The blood splatter is concentrated at one point (making the spot darker when dried) and at the sides there may be little blots (as seen distinctly in blood splatter 1). It does not have a smooth edge, but rather it is jagged at the sides.

3. What are the factors that affect the shape of the blood splatter? Name as many as possible.
- Angle of elevation
- Force
- Distance between the spot it lands on and the origin
- ???

4. Generate some hypotheses from the blood splatter patterns observed above.
- The higher the angle of elevation, the longer the blood splatter
- The higher the angle of elevation, the narrower the blood splatter
- The further the origin of the blood splatter, the wider the diameter of the blood splatter

Results from the activity Jesslyn and I did (:

*Instead of doing labeling the blood splatters as "A10" etc, we labelled the actual height, like the lab experiment in the above picture. Also, I did the tables in a way that I found more comprehensive, but I also did the one according to the requirements at the top.



Also, here are the graphs:





Update 06.08.11, Saturday:

Jesslyn, Jolene, Jubily and Natalie K.'s blood splatter :D (from