A non-destructive technical and stylistic comparative analysis of selected metal artefacts from the Ditsong National Museum of Cultural History

The destructive nature of conventional analytical techniques, coupled with the finite nature of ancient/historical artefacts, has long restricted technical examinations of museum collections, mainly due to ethical constraints. However, over the past few decades, the application of Non-Destructive Evaluation (NDE) techniques has become increasingly popular within the fields of archaeology and cultural heritage diagnostics. The application of such techniques has facilitated the examination of objects that have long remained uninvestigated. However, this positive development also held a slight drawback, in that researchers tend to now focus on technical analyses alone, while excluding more traditional means of analyses, such as comparative stylistic analysis and surface investigation. By employing a combination of stylistic analysis, visual surface investigation (by means of SLR photography and digital microscopy) and nuclear imaging (by means of Microfocus X-Ray Computed Tomography), the thesis sets out to justify the application of mixed methodologies as part of a more holistic integrated authentication approach. Thus stated, the thesis presents a mixed-methodological approach towards the analysis of selected metal objects from the Ditsong National Museum of Cultural History in Pretoria, South Africa. The objects under investigation include a small collection of ancient Egyptian bronze statuettes, a Samurai helmet (kabuto) and mask (menpó), a European gauntlet, and an Arabian dagger (jambiya/khanjar). While all the objects are curated as part of the museum’s archaeology and military history collections, the exact production dates, manufacturing techniques and areas of origin remain a mystery. By using a combination of techniques, the thesis aims to identify diagnostic features that can be used to shed light on their relative age, culturo-chronological framework and, by extension, their authenticity.Old Testament and Ancient Near Eastern Studie

INDUSTRIAL RESTRUCTURING AND REVITALISATION IN THE UK COASTAL ZONE

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN003838 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Species interactions differ in their genetic robustness

Conflict and cooperation between bacterial species drive the composition and function of microbial communities. Stability of these emergent properties will be influenced by the degree to which species' interactions are robust to genetic perturbations. We use genome-scale metabolic modeling to computationally analyze the impact of genetic changes when Escherichia coli and Salmonella enterica compete, or cooperate. We systematically knocked out in silico each reaction in the metabolic network of E. coli to construct all 2583 mutant stoichiometric models. Then, using a recently developed multi-scale computational framework, we simulated the growth of each mutant E. coli in the presence of S. enterica. The type of interaction between species was set by modulating the initial metabolites present in the environment. We found that the community was most robust to genetic perturbations when the organisms were cooperating. Species ratios were more stable in the cooperative community, and community biomass had equal variance in the two contexts. Additionally, the number of mutations that have a substantial effect is lower when the species cooperate than when they are competing. In contrast, when mutations were added to the S. enterica network the system was more robust when the bacteria were competing. These results highlight the utility of connecting metabolic mechanisms and studies of ecological stability. Cooperation and conflict alter the connection between genetic changes and properties that emerge at higher levels of biological organization.The authors thank reviewers for comments that substantially improved this manuscript. BG and DS were partially supported by grants from the US Department of Energy (DE-SC0004962) and NIH (R01GM089978 and R01GM103502). (DE-SC0004962 - US Department of Energy; R01GM089978 - NIH; R01GM103502 - NIH)Published versio

Work Related Musculoskeletal Pain and It’s Management

This is an ongoing project, your comments are welcome! [email protected] chapter reviews current best evidence in the identification and management of work related factors causing musculoskeletal pain and discomfort

Antimicrobial Susceptibility Testing and Sub-Inhibitory Growth Effects of Seven African Medicinal Plant Extracts

Novel antibiotic therapies are urgently required in light of the antibiotic resistance crisis. Antimicrobial susceptibility testing of plants is under-researched, but early results indicate plants may constitute a reservoir of novel antimicrobial compounds. Empiric determination of unstudied traditional plant preparations is desired, because traditional plant medicine is relied upon in many areas of the developing world. Herein, we investigated the antimicrobial properties of seven plants from African traditional medicine, as well as the effects of sub-lethal concentrations on bacterial growth. We found that gram-positive organisms were susceptible to plant extract treatment between 0.5-10% (v/v) concentrations, while gram-negative organisms tested demonstrated resistance. Sub-lethal plant extract treatments indicated bioactivity other than antimicrobial activity. Observations included proliferation, adhesion, and possible biofilm formation promotion. Determination of bioactive compounds present in the tested plant extracts is desired for pursuing drug development. Likewise, confirmation of biofilm promotion at sub-lethal doses is desired for potential identification of potential targets for novel antibiotic drug development. Lastly, as the plant extracts we tested are used in traditional medicines our results may aid in improving the efficacy of their use by traditional practitioners. *Indicates faculty mentor

Compensatory evolution for a gene deletion is not limited to its immediate functional network

<p>Abstract</p> <p>Background</p> <p>Genetic disruption of an important phenotype should favor compensatory mutations that restore the phenotype. If the genetic basis of the phenotype is modular, with a network of interacting genes whose functions are specific to that phenotype, compensatory mutations are expected among the genes of the affected network. This perspective was tested in the bacteriophage T3 using a genome deleted of its DNA ligase gene, disrupting DNA metabolism.</p> <p>Results</p> <p>In two replicate, long-term adaptations, phage compensatory evolution accommodated the low ligase level provided by the host without reinventing its own ligase. In both lines, fitness increased substantially but remained well below that of the intact genome. Each line accumulated over a dozen compensating mutations during long-term adaptation, and as expected, many of the compensatory changes were within the DNA metabolism network. However, several compensatory changes were outside the network and defy any role in DNA metabolism or biochemical connection to the disruption. In one line, these extra-network changes were essential to the recovery. The genes experiencing compensatory changes were moderately conserved between T3 and its relative T7 (25% diverged), but the involvement of extra-network changes was greater in T3.</p> <p>Conclusion</p> <p>Compensatory evolution was only partly limited to the known functionally interacting partners of the deleted gene. Thus gene interactions contributing to fitness were more extensive than suggested by the functional properties currently ascribed to the genes. Compensatory evolution offers an easy method of discovering genome interactions among specific elements that does not rest on an a priori knowledge of those elements or their interactions.</p

Examining the Antimicrobial Activity of Plant Extracts used in Traditional Medicine

With the increasing prevalence of antibiotic resistance, the need for novel antimicrobials is high. In Africa, local populations use native plant extracts to treat infection; however, whether or not they are antimicrobial remains largely unknown. If these plant extracts demonstrate antimicrobial activity they may prove useful in the fight against antibiotic resistance. The purpose of this project was to develop a standard method to evaluate the antimicrobial activity of extracts from eleven plant species used in traditional medicine, and to examine if these extracts inhibit growth of four different bacterial species representing various pathogen groups. Using a modified disk diffusion assay, increasing volumes of plant extracts, antibiotic solutions, or control solutions were added to filter paper disks. These disks were then placed onto agar plates inoculated with test bacteria. The zones of inhibition were measured and additional visual growth effects were recorded. Seven of the eleven extracts produced zones of inhibition against at least one bacterial species. This effect was dose-dependent. Of the four bacterial species tested, E. coli, B. subtilis and S. epidermidis had their growth inhibited by at least one extract. Interestingly, ten of the extracts had additional bio-activity that resulted in visible morphological changes in the bacteria, indicating these extracts affect growth and gene expression. This effect was produced in all four bacterial species by at least one extract. This investigation was essential in characterizing the extracts’ biological properties so they may be studied further and potentially used in industrial or medical applications. *Indicates faculty mento

Multiple long-term, experimentally-evolved populations of Escherichia coli acquire dependence upon citrate as an iron chelator for optimal growth on glucose

Background: Specialization for ecological niches is a balance of evolutionary adaptation and its accompanying tradeoffs. Here we focus on the Lenski Long-Term Evolution Experiment, which has maintained cultures of Escherichia coli in the same defined seasonal environment for 50,000 generations. Over this time, much adaptation and specialization to the environment has occurred. The presence of citrate in the growth media selected one lineage to gain the novel ability to utilize citrate as a carbon source after 31,000 generations. Here we test whether other strains have specialized to rely on citrate after 50,000 generations. Results: We show that in addition to the citrate-catabolizing strain, three other lineages evolving in parallel have acquired a dependence on citrate for optimal growth on glucose. None of these strains were stimulated indirectly by the sodium present in disodium citrate, nor exhibited even partial utilization of citrate as a carbon source. Instead, all three of these citrate-stimulated populations appear to rely on it as a chelator of iron. Conclusions: The strains we examine here have evolved specialization to their environment through apparent loss of function. Our results are most consistent with the accumulation of mutations in iron transport genes that were obviated by abundant citrate. The results present another example where a subtle decision in the design of an evolution experiment led to unexpected evolutionary outcomes.Organismic and Evolutionary Biolog