The focus of this report is to investigate whether a towboat would be able meet damaged stability requirements. In order to evaluate what type of damage stability requirements could be considered, two damage stability criteria were selected for this investigation: Offshore Supply Vessel and Passenger Vessel Damage Criteria. Two vessels are then evaluated using General Hydrostatic Software (GHS) to find the maximum allowable vertical center of gravity allowed by each set of criteria. These values are then compared to the vessels’ operating conditions to show if the vessels would currently be able to operate. Ultimately it is found that the extent of damage of the criteria is the greatest limiting factor for this vessel type. Suggestions are made regarding the necessary changes to the boats’ general arrangements and loading conditions in order to meet the damaged stability requirements.

Aging-related decline in immunity is believed to be the main driver behind decreased vaccine efficacy and reduced resistance to infections in older adults. Unrepaired DNA damage is known to precipitate cellular senescence, which was hypothesized to be the underlying cause of certain age-related phenotypes. Consistent with this, some hallmarks of immune aging were more prevalent in individuals exposed to whole-body irradiation (WBI), which leaves no anatomical repository of undamaged hematopoietic cells. To decisively test whether and to what extent WBI in youth will leave a mark on the immune system as it ages, we exposed young male C57BL/ 6 mice to sublethal WBI (0.5-4 Gy), mimicking human survivor exposure during nuclear catastrophe. We followed lymphocyte homeostasis thorough the lifespan, response to vaccination, and ability to resist lethal viral challenge in the old age. None of the irradiated groups showed significant differences compared with mock-irradiated (0 Gy) animals for the parameters measured. Even the mice that received the highest dose of sublethal WBI in youth (4 Gy) exhibited equilibrated lymphocyte homeostasis, robust T-and B-cell responses to live attenuated West Nile virus (WNV) vaccine and full survival following vaccination upon lethal WNV challenge. Therefore, a single dose of nonlethal WBI in youth, resulting in widespread DNA damage and repopulation stress in hematopoietic cells, leaves no significant trace of increased immune aging in a lethal vaccine challenge model.

A dissertation submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg, for the degree of Master of Science (Medicine). / Objective: To determine the relationship between asbestos exposure and chromosome damage, as depicted by sister chromatid exchange frequency. Design: Descriptive, cross-sectional study. Setting: Asbestos-products factory Subjects: 31 asbestos-exposed subjects and 21 unexposed subjects Main outcome measure: Mean sister chromatid exchange (SCE) frequency per metaphase cell. Results: The control group had a slightly higher mean SCE frequency per cell than the exposed group (3.4%) but this difference was not statistically significant (p = 0.5935). Smoking contributed significantly to SCE frequencies in both the exposed and unexposed groups. The mean SCE frequencies per cell in the exposed group were 10.49 for smokers and 8.59 for non-smokers (p = 0.0078). The frequencies for smokers and non-smokers in the unexposed group were 10.83 and 8.58, respectively (p = 0.0257). Conclusions: The failure to observe an increase in SCE frequency does not rule out asbestos exposure as a genotoxic agent. Rather, it may help to resolve the limitations of this method for detecting genetic damage. Alternatively, the fibre levels to which this group was exposed may have been too low to cause chromosome damage. / WHSLYP2016

Abstract Diamond is nowadays regarded as a potential semiconductor material of the future, due to its extreme and unique properties. Some of these properties, in- clude its high hardness, highest breakdown ¯eld, high Debye temperature, high thermal conductivity, high hole and electron mobilities, large bandgap and op- tical transparency, among others. These properties make diamond suitable for high-temperature, high-speed and high-power electronic applicatons, as well as in other applications. However, defects associated with ion implantation have been shown to make it rather di±cult to obtain n-type doping in diamond. As such, an understanding of the nature of defects produced during ion implanta- tion of diamond remains a subject of great importance, if not essential, for the optimization of high-temperature, high-power electronic applications in partic- ular. In this respect, this study investigates the nature of the radiation damage generated within the collision cascades of multi-implantations of carbon ions in high-pressure, high-temperature single-crystal synthetic type Ib diamond, spread over a range of energies (50-150keV) and doses. This is achieved by means of the cold-implantation-rapid-annealing (CIRA) routine, and the anal- ysis of damage caused was done by using cross sectional transmission electron microscopy techniques. More precisely, the modes used to achieve this are the bright ¯eld transmission electron microscopy (BFTEM) coupled with selected area di®raction or SAD. At low dose implantation or at sub-critical implantation doses (2.5x1015 ions/cm2), it was found that the ion-damaged diamond layer consists of some threading dislocations, not homogeneously distributed which propagate from the surface into the ion-damaged diamond. In contrast to the sub-critical implantation doses , it was found that at very high implantation doses (7.0x1015 ions/cm2), i.e., above the critical dose (where diamond transforms to graphite upon annealing), the damaged diamond layer had some unconventional defect features close to the implanted surface.

Decision-making, accepted to be an important part of executive function, is inherent in all complex human experiences requiring intact brain functioning. Three different types of decision making have been identified: actor-centred, emotion-based and veridical decisionmaking. All require goal-setting, planning and execution, which are often impaired after sustaining an acquired brain injury (ABI). The Cognitive Reserve Hypothesis (CRH) holds that a larger brain belonging to an individual with a higher IQ and better education will be more resilient to injury. The principal aim of this study was to investigate performance differences in neuropsychological tests of decision-making between individuals with ABI from different socioeconomic status (SES). It was hypothesised that ABI would exacerbate differences in decisionmaking performance between individuals from a higher SES and those from low SES in terms of the CRH. Participants (n=25) had all sustained an ABI. Actor-centred, emotion-based and veridical decision-making were investigated using the Tinker Toy Test (TTT), the Iowa Gambling Task (IGT) and the Berg Card Sorting Task (BCST) respectively. Participants were asked to complete an SES Questionnaire. The independent variables were markers of SES: Race, Level of Education, Quality of Education, and Quality of Medical Care at time of injury. Differences in quality of education were significant for the BCST, suggesting that a poor quality of education has a negative impact on veridical decision-making after ABI. Poor education (a marker of low SES) does not provide the same buffering effect for insults to the brain in the event of an ABI as does superior education (a marker of high SES).

The effects of simulated battle damage on the aerodynamic performance of a wing is well documented; it is known that battle damage reduces lift, increases drag and changes pitching moment. However, there is a fundamental lack of understanding when it comes to the three-dimensional flow features that create such effects. The current knowledge of the flow field is predominantly based upon interpretation of surface flow visualisation techniques coupled with force balance measurements. In this work, a more modern technique in the form of Particle Image Velocimetry (PIV) has been used to map the three-dimensional flow field away from the wing surface. A PIV system was designed for the Loughborough University Low Turbulence Wind Tunnel in order to gain a deeper understanding of the flow mechanisms that are produced by simulated battle damage. The system was tested for suitability and the data quality assessed. The system was found to produce high quality vector output with low levels of uncertainty, it could also be used in multiple planes and orientations to provide the flow field data required. The technique was first applied to a single battle damage hole with a diameter of 20% chord, located at the wing s mid-chord. The wing model was of realistic construction and had a cavity. This damage case had previously been shown to produce different flow features across the incidence range and was typically a survivable damage case. The hole was seen to produce a jet at incidence angles above 2°, however the characteristics of the jet were different to those predicted in previous battle damage work and in jets in cross-flow research. The velocity ratio was very low peaking at around 0.25 at 8° incidence, much lower than the surface flow features and jet in cross-flow literature would suggest. No characteristic counter-rotating vortex pair was found in the jet due to the presence of a wing cavity and low velocity ratio. It is suggested that the wing's adverse pressure gradient has a magnified effect on the wake and is responsible for the increase in wake size at higher incidence angles, something previously thought to be due to increasing velocity ratio. A larger hole of 40% chord located at mid-chord, along with a straight through damage hole with no cavity, have been tested to isolate and highlight flow features to further explain the flow mechanics. Then, PIV was applied to several multiple hole damage cases to study the interaction caused by such damage. Side-by-side holes with different proximities, where the two damage holes had the same chordwise location, were studied to isolate interaction effects. It was found that at low incidence angles the force increments were double that of a single damage hole at the same chordwise location. However, as incidence angle increased above 2° the increments were less than double. This was because the wakes of the two damage holes were smaller than the wake of a single damage hole. From a purely aerodynamic point of view, it was seen that having two holes close together interacting was favorable compared with having two holes far apart with no interaction. Two in-line damage holes were also tested. Once again the two holes together produced smaller increments than predicted by the summation method, i.e. summing the increments created by each single hole tested individually. The presence of two holes in-line limited the effectiveness of the forward hole and hence limited the performance losses, whereas individually the hole at the forward chord location will produce much larger effects than an equivalent hole further aft.

by Shi Yuling. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 159-184). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Barely Visible Impact Damage (BVID) can occur when laminated composite material is subject to impact, i.e. from runway debris or dropped tools, and may result in a significant reduction in the compressive strength of composite structures. A component containing BVID subjected to compression may fail via a number of mechanisms. However, it is assumed that the impact damage problems to be modelled will fail by delamination buckling leading to propagation of damage away from the original site. This precludes problems where the initial mechanism of failure is via kink banding or buckling of the full laminate. An analytical model is presented, for application to various composite structures, which predicts the level of compressive strain below which growth of BVID following local buckling of a delaminated sublaminate will not occur. The model is capable of predicting the critical through-thickness level for delamination, the stability of delamination growth, the sensitivity to experimental error in geometric measurements of the damage area and additionally establishes properties desirable for laminates optimised for damage tolerance. Problems treated with the model are split into two impact categories; ‘face’ (i.e. an out-of-plane skin impact) and ‘free edge’ (i.e. an in-plane stiffener edge impact) and two compressive loading regimes; ‘static’ and ‘fatigue’. Analytical results for static and fatigue compression of face impacted plates show an agreement of threshold strain to within 4% and 17% of experimental values respectively. In particular, for impacts to the skin under a stiffener subject to static loading the model is accurate to within 5%. An optimised laminate stacking sequence has shown an experimental increase of up to 29% in static strength can be achieved in comparison to a baseline configuration. Finally, compression testing has been undertaken on three coupons in order to validate an analysis of static free edge problems. Analytical results are, on average, within 10% of experimental results. An optimised laminate is theoretically predicted to increase static compression after free edge impact strength by at least 35%.

This study was conducted at the University of Massachusetts Medical Center in the Volkert laboratory. Human alkyl adenine DNA glycosylase (hAAG) is a DNA repair enzyme that repairs alkylated DNA bases. hAAG was cloned in 1991 and a second isoform was classified in 1994. The difference between the two isoforms of hAAG is an alternate spliced first exon. Both isoforms of the hAAG gene were present in the Volkert laboratory collection, however the second isoform (hAAG-2) was phenotypically different than the first and became the first focus of this study. Using the improperly functioning isoform as a template, and constructing a 5' primer with the identical upstream sequence as the functioning isoform (hAAG-1), a phenotypically similar gene was constructed by PCR. The new isoform (hAAG-2) was cloned into an expression vector and its activity as a DNA repair agent was studied. A second version of hAAG-2 was also constructed, incorporating a histidine tag for protein purification and identification purposes. Efforts included using the ability of hAAG to complement glycosylase deficient alkA tagA E. coli double mutant strains to assess and to compare the ability of the two isoforms of hAAG and to determine if the histidine tag affected function. The ability of hAAG to rescue cells from exposure to a variety of DNA damaging agents was studied by inducing each isoform and analyzing the sensitivity of the cells to increased doses of DNA damaging agents. Both hAAG-1 and hAAG-2 were able to restore the wild type resistance of the alkA and tag genes when exposed to the alkylating agents MNNG and MMS. In order to study the ability of hAAG to repair alkyl lesions larger than methyl groups, it was necessary to inactivate the uvrA dependent nucleotide excision repair gene. In E. coli, methyl lesions are repaired primarily by glycosylases, while nucleotide excision repairs bulky lesions. Thus, in order to detect hAAG activity on these types of damage, it was necessary to inactivate the bacterial uvrA gene. Each isoform of hAAG was transformed into a triple mutant strain deficient in alkA tagA and uvrA, then exposed to CNU, BCNU, and Mitomycin C. Each of these DNA damaging agent caused increased toxicity in the presence of hAAG. hAAG-1 expressed in the alkA tag double mutant strain was exposed to Mitomycin C and showed greater resistance than hAAG-1 expressed in the alkA tag uvrA triple mutant. In fact, in the nucleotide excision proficient strain, expression increased Mitomycin C resistance above that seen in the control, suggesting that glycosylase activity may function in a partnership with nucleotide excision repair and that the two isoforms of hAAG have subtle differences. An ompT protease knockout host strain was constructed using P1-transduction and used to examine protein products. hAAG-2 was inserted into the pBlueScript plasmid so that the gene could be regulated by the T7 promoter for use beyond the scope of this thesis. A protein synthesis time course assay was conducted to determine the expression levels of hAAG-1 and hAAG-2 when induced by IPTG. Immunoblot detection of the histidine tag was used to measure expression levels of each isoform.

CRISPR/Cas9 is the gene editing tool of choice in basic research and poised to become one in clinical context. However, current studies on the topic suffer from a number of shortcomings. Mutagenesis is often assessed using bulk methods, which means rare events go undetected, unresolved or are discarded as potential sequencing errors. Many of the genotyping methods rely on short-range PCR, which excludes larger structural variants. Other methods, such as FISH, do not provide basepair resolution, making the genotype assessment imprecise. Furthermore, it is not well understood how Cas9 delivery format influences the dynamics of indel introduction. Finally, many studies of on-target activity were conducted in cancerous cell lines, which do not accurately model the mutagenesis of normal cells in the therapeutic context. In my thesis, I have investigated on-target lesions induced by Cas9 complexed with single gRNAs and no exogenous template. I have followed the time dynamics of Cas9-induced small indels as a function of reagent delivery methods, established an assay for quantification of Cas9-induced genomic lesions that are not small indels ("complex lesions") and used this assay to isolate and genotype complex lesions, many of which would be missed by standard methods. I found that DNA breaks introduced by single guide RNAs frequently resolved into deletions extending over many kilobases. Furthermore, lesions distal to the cut site and cross-over events were identified. Frequent and extensive DNA damage in mitotically active cells caused by CRISPR/Cas9 editing may have pathogenic consequences.