Counterfeit Integrated Circuits (ICs) are previously used ICs that are resold as new. They have become a serious problem in modern electronic devices. They cause lower performance, reduced life span and even catastrophic failure of systems and platforms. To prevent counterfeiting and the associated revenue loss, there is need for non-invasive and inexpensive techniques to establish the authenticity of devices. We describe a technique to detect a counterfeit IC that does not have any special anti-counterfeiting mechanisms built-in prior to deployment. Our detection criterion is based on measuring path delays. The experiments show that a single path delay cannot directly reveal the age, as it is also greatly influenced by process variation and this could result in large error in classifying ICs as authentic or counterfeit. �Instead, we establish that the relationship between the delays of two or more paths is a great indicator for the age of device. The idea is to project ICs from different age groups onto the space of the path delays and train a trusted reference hyper-surface for each age group. Ideally, the hyper-surfaces do not overlap. In this way, an IC under test can be assigned to one hyper-surface based on the distance of its footprint with respect to these hyper-surfaces, thus predicting its age. In our simulations, we observe over 97% correct prediction of identifying an aged IC from a new IC. / Master of Science

Environmental variation of Thamnocortus insignis Mast. (Restionaceae) is presented, by using average dry weight measurements of six populations of this species found along the coast of the Cape Province. The dry weight measurements were used to detect variation in the growth rates of the six populations, which in tum indicates the environmental variation among the populations. The results were showed no significant difference between all six populations and this was due to the relatively very small sizes of the seedlings when the measurements were taken. Genetic variation was investigated by using isozyme electrophoresis of the EST locus. One population (Puntjie) showed significant deviation from the Hardy-Weinberg equilibrium, whilst all the others agreed with the assumptions of the model except for the Superthatch-extra tall population, which was homologous. Estimation of allelic diversity among the populations produced a Fst of 0.098 that implies that there is a high level of gene flow among the six populations of the species. The allelic diversity estimate within populations was also very low (Fis = 0.079) implying that the genetic neighbourhoods are relatively large and there is a high incidence of gene flow within the populations. Both estimation results support the predicted results for dioecious wind-pollinated species such as T. insignis.

Student Number : 0318625T - MSc dissertation - School of Molecular and Cell Biology - Faculty of Science / Genetic variation in haptoglobin, a plasma protein, has been reported to be associated with susceptibility to and the rate of HIV/AIDS progression. The purpose of this study was to investigate the influence of haptoglobin polymorphism on HIV/AIDS in black South Africans. Polymorphism in the coding region of the haptoglobin gene was detected by direct DNA and allele-specific amplification. Polymorphism in the coding region of the gene was detected by amplification of DNA and by polyacrylamide gel electrophoresis of plasma protein. A statistically significant association was observed between allele -61C and resistance to HIV infection. The Hp0 phenotype, in which no haptoglobin protein is detected, was associated with HIV status and some promoter genotypes. Since in our study population there were a few samples with usable clinical data , further investigations need to be done to confirm the association of the -61C allele and the Hp0 phenotype with the risk of HIV infection.

No description available.

No description available.

No description available.

No description available.

The investigation of the waters of Lake Bridgeport is to obtain data essential for a satisfactory understanding of the physical and chemical factors on the aquatic life. These factors detremine the kinds of food available for life there.

No description available.

No description available.