Final exam

Scientists should be disinterested observers Collect observations without prejudice or preconception Multiple observations lead to emerging patterns that can provide “truths about nature”.

Hypothesis emerges from observation Logical predictions follow from the hypothesis Predictions can be tested in such a way as to allow for rejection of the hypothesis. Hypotheses can only be “rejected” or “fail to be rejected”, they can never be proven.

He suggested that there is a consensual world view that involves an agreed upon set of assumptions, methods, and language (a paradigm) in which science progresses incrementally. At a certain point there builds up difficulties and eventually a scientific revolution brings about a new paradigm.

where the falsification of hypotheses and construction of alternative hypotheses occurs. No feelings in science Differnces – timing, testing of hypothesis, language

Language: error and mistake. Used interchangeably in law. Error is intrinsic to any scientific measurement and is part of the data interpretation. Objective: Law – justice within a time limit. A decision has to be made. Science – truth with no time limit. A decision is not required.

assume indistinguishable marks produced by a single object and those produced by different people or objects are observably different. Advantage/appeal: enables forensic scientists to draw bold, definitive conclusions. PROBLEM: excuses forensic sciences from developing: measures of object attributes, collecting population data on the frequencies of variations in those attributes, testing attribute independence, and calculating and explaining probability that different objects share common observable attributes.

Stephen Cowan - Fingerprint Ray Crone - Bite mark J.R. Brouingaard - Head/Pubic hair Ronald Cotton - Eye witness

the general acceptance of the scientific technique or principle

new rules for admissibility of scientific expert testimony. Difficult for courts to sort good from bad science, whether the bad science is a matter of perjury, incompetence, or unclear language.

peer review, error rates, adequate testing, regular standards and techniques, general acceptance. Theoretical underpinnings of methods must yield testable predictions by means of which the theory could be falsified. Methods preferably published in peer-reviewed journal. Known rate of error that can be used to evaluate results. Methods generally accepted by relevant scientific community.

colour tests such as Kastle-Mayer/Hemastix luminescence tests: luminol/Bluestar antibody precipitin tests, specific for human blood: Hematrace test.

Direct microscopic observations acid phosphatase test (colour test) prostate specific antigen tests (P30 human specific)

Phadebas Test (for alpha-amylase)

Species identification is performed using DNA markers (mitochondrial DNA sequencing).

PCR amplification of X and Y chromosomespecific DNA allows sex determination. .

DNA analysis can identify evidence taken from an illegal kill site and “link” it to a sample from suspected poacher

Databases needed for population identification (e.g. reference samples).

Establish if animals in a captive breeding program are the offspring of registered breeding pairs or illegally obtained from wild stocks (again with STRs or microsatellite markers)

DNA analysis + chemical testing Serological testing + DNA analysis Trace evidence + DNA analysis Toxicology + DNA analysis

DNA Extraction –> DNA Quantitation –> PCR Amplification of Multiple STR markers

Separation and Detection of PCR Products (STR Alleles) –> Sample Genotype Determination

Comparison of Sample Genotype to Other Sample Results –> If match occurs, comparison of DNA profile to population databases –> Generation of Case Report with Probability of Random Match

used molecular biology technique that allows scientists to make millions or even billions of copies of a specific segment of DNA.

A genotype refers to the genetic makeup of an organism, which is the collection of genes inherited from its parent