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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Socio-ecological drivers of primate social network dynamics and implications for individual fitness

Murphy, Derek January 2015 (has links)
Social animals, such as primates, incur many fitness-related costs as a direct result of living in groups of conspecifics. However, group-living also comes with benefits. Sociality is thought to have evolved in response to the need for individuals to negotiate their social environment in order to maximise the benefits and minimise the costs associated with group-living. Recently, researchers interested in animal sociality have turned to a set of sophisticated statistical tools, collectively termed 'social network analysis' in order to better understand the structure of animal social systems and the role of individuals within their social groups. Using a social network analytic approach, I explore the relationship between the ecological and social environments, and the implications of an uncertain social landscape for individual fitness and fitness-relevant processes in two species of Old-World monkeys: chacma baboons (Papio hamadryas ursinus) and vervet monkeys (Chlorocebus aethiops pygerythrus). My results suggest that individuals respond to fluctuating local conditions in diverse ways depending on behavioural context and their current reproductive state, and that the social environment experienced by an individual, and their active pattern of social engagement has important implications for infant survival. Finally, I investigate how network structure influences two fitness-relevant processes of flow in a population of vervet monkeys: information transfer and disease transmission. I conclude that the complex social life of animal groups emerges from many individuals trying to achieve the same fitness goals. Successful individuals exploit the complexity in their social environment and respond adaptively to an uncertain and inconstant set of local conditions by actively adopting social strategies that serve to enhance their fitness.
72

Antibiotic Resistance and Resistance Mechanisms in Bacteria Isolated from the Deep Terrestrial Subsurface

Unknown Date (has links)
Various natural environments have been examined for the presence of antibiotic-resistant bacteria and/or novel resistance mechanisms, but little is known about resistance in the terrestrial deep subsurface. This study examined two deep environments that differ in their known period of isolation from surface environments and the bacteria therein. One hundred and fifty-four strains of bacteria were isolated from sediments located 170-259 m below land surface at the U.S. Department of Energy Savannah River Site (SRS) in South Carolina and Hanford Site (HS) in Washington. Analyses of 16S rRNA gene sequences showed that both sets of strains were phylogenetically diverse and could be assigned to several genera in 3-4 phyla. All of the strains were screened for resistance to 13 antibiotics by plating on selective media and 90% were resistant to at least one antibiotic. 86% of the SRS and 62% of the HS strains were resistant to more than one antibiotic. Resistance to naladixic acid, mupirocin, or ampicillin was noted most frequently. The results indicate that antibiotic resistance is common among subsurface bacteria. The somewhat higher frequencies of resistance and multiple resistance at the SRS may, in part, be due to recent surface influence, such as exposure to antibiotics used in agriculture. However, the HS strains have never been exposed to anthropogenic antibiotics but still had a reasonably high frequency of resistance. Given their long period of isolation from surface influences, it is possible that they possess some novel antibiotic resistance genes and/or resistance mechanisms. Seven of the strains from the HS that are resistant to tetracycline were examined for the presence of a novel antibiotic resistance gene. From these seven strains, a novel tetracycline resistance determinant was characterized. The predicted amino acid sequence shares only a 30% sequence similarity with TetA(Z), the most closely related previously described determinant. The new protein is a putative efflux pump with several characteristics in common with previously characterized efflux pumps including: a divergently transcribed TetR repressor, conserved GxxSDRxGRR motif, and transmembrane domains. The determinant has been assigned the name Tet 42. Functional genes from another subset of 11 HS strains that are resistant to ciprofloxacin were sequenced for resistance-conferring mutations. The most common mechanism of resistance to this antibiotic is based on mutations in the functional genes for DNA gyrase (gyrA, gyrB) and topoisomerase II (parC, parE). Sequences for the genes gyrA, gyrB, and parC in resistant strains were compared to the same sequences from ciprofloxacin-sensitive strains from the HS and Escherichia coli. The strains grouped into three genera: Arthrobacter, Sphingomonas, and Pseudomonas. All of the resistant strains possessed some mutations in their gyrase and/or topoisomerase genes that result in the substitution of amino acids not seen in the gene products of E. coli and the sensitive strains. These mutations, some of which have not been reported previously, can be considered putative resistance-conferring mutations. The resistant subsurface strains were also grown in the presence of an efflux pump inhibitor, and a majority of the cultures did not grow when the inhibitor was added. Lack of growth in the presence of the inhibitor may indicate that ciprofloxacin resistance is due entirely or in part to an efflux pump. The presence of an efflux pump might also explain why some of the strains with a higher minimum inhibitory concentration (MIC) have fewer mutations in their gyrase and/or topoisomerase genes than do strains with a lower MIC. It is possible that, along with novel mutations that may play a role in resistance, these strains also posses an uncharacterized efflux pump. A third approach used in this study to examine novel antibiotic resistance mechanisms was to look at differences in the entire proteome under normal and stressed conditions. The strain G887 is resistant to tetracycline and possesses the tetracycline resistance determinant Tet 42. Cultures of this strain were grown with tetracycline and without tetracycline. Protein extractions were performed from each culture and separated in the 1st dimension according to pI, on 4-7 Isoelectric Focusing Strips (IEF) strips and 6-11 IEF strips. After the 1st dimension separation, the proteins were separated by molecular weight on 12% acrylamide gels. The gels were stained with a fluorescent stain, imaged, and analyzed with spot analysis software. The gels run with the proteins from the tetracycline-treated culture indicated that several proteins visualized on both the 4-7 and 6-11 gels were upregulated in the presence of tetracycline. Some of these spots correspond to the molecular weight and pI for Tet A(42) or to those of several previously described general stress proteins. This work demonstrates that there is a high frequency of antibiotic resistance in the deep terrestrial subsurface and that bacteria in this environment possess uncharacterized antibiotic resistance genes and mutations that confer resistance. Given the constant emergence of antibiotic-resistant pathogenic strains in clinical settings and the problems this creates with respect to the treatment of bacterial diseases, it becomes increasingly important to characterize antibiotic resistance genes that may exist in the environment but have not yet been transferred to clinically important species. Our ability to alter existing antibiotics or develop new drugs to counter novel resistance mechanisms will be dependent on such characterizations. It might also be worthwhile to investigate subsurface bacteria for the ability to produce antibiotics themselves. There is a real potential for novel antibiotic discovery, given the length of time these bacteria have been isolated from antibiotic-producing bacteria in surface environments. / A Dissertation submitted to the Department of Biomedical Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2008. / October 3, 2008. / Antibiotic Resistance, Bacteria, Subsurface / Includes bibliographical references. / David L. Balkwill, Professor Directing Dissertation; Hank W. Bass, Outside Committee Member; Graham A. Patrick, Committee Member; Branko Stefanovic, Committee Member.
73

The relationship between food environment, obesity and NCD status among adults aged 30-70 years in Langa and Mount Frere, South Africa.

Manuga, Tshilidzi January 2019 (has links)
Master of Public Health - MPH / Non-Communicable Diseases (NCDs) are some of the leading causes of death worldwide. Obesity results from the interactions between biology, behaviour, and environment. The current obesity epidemic is largely driven by environmental rather than biological factors, through its influence on social norms regarding food choices and lifestyle behaviours. The number of people dying from diabetes and hypertension keeps increasing because of the current obesity trend.
74

On the topic of Aerosol Generation and Propagation

Unknown Date (has links)
In this research, three methods of aerosol generation, and their subsequent propagation, are investigated experimentally. These experiments provided insight into the potential risk aerosol can have pertaining to the spread of infectious disease such as COVID – 19. The first of which investigated an alternative generation route that may exist given the discovery of small numbers of viable viruses in urine and stool samples. Flushing biomatter can lead to the aerosolization of micro-organisms; thus, there is a likelihood that bioaerosols generated in public restrooms may pose a concern for the transmission of COVID-19, especially since these areas are relatively confined, experience heavy foot traffic, and may suffer from inadequate ventilation. The results indicate that the particular designs tested in the study generate a large number of droplets in the size range 0.3 𝜇𝑚 – 3 𝜇𝑚, which can reach heights of at least 1.52 m. This highlights the need for incorporating adequate ventilation in the design and operation of public spaces, which can help prevent aerosol accumulation in high occupancy areas and mitigate the risk of airborne disease transmission. Secondly, experiments were conducted to evaluate the effectiveness of facial coverings at various distances around a simulated cough. These concluded that due to the gaps along the seal of a face mask, aerosols can escape 360° around a coughing individual. In the final portion of the thesis study, an experimental method was developed and conducted to break up a droplet via mechanical excitation. The results of these experiments showed that when a droplet is placed on a vibrating string, the droplet can be broken into many secondary droplets which is analogous to one speaking or singing thus providing insight as to how vocal cords can generate respiratory aerosols. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection
75

Cytokine-Associated Neutrophil Extracellular Traps and Antinuclear Antibodies in Plasmodium Falciparum Infected Children under the Age of Six.

Unknown Date (has links)
In Plasmodium falciparum-infected children, the relationships between blood cell histopathology, blood plasma components, development of immunocompetence, and disease severity remain poorly understood. This investigation relates levels of the pro-inflammatory cytokines IFN-g, IL-2, TNF-a, CRP, and IL-6, and select anti-inflammatory cytokines TGF-b and IL-10 to the formation of neutrophil extracellular nets (NETs), IgG antinuclear antibodies (ANA), and IgG antineutrophil cytoplasmic antibodies (ANCA) in blood collected before and seven days after initiation of Sulfadoxine-Pyrimethamine treatment from 21 Nigerian children under six years old presenting with uncomplicated malaria. The children exhibited a Th2 dominated cytokine profile and left-shifted leukocyte differential. Elevated TNF-a levels correlated with significant NET formation evident in the peripheral blood smears. ANA levels (inclusive of all subsets of ANA) were significant in 86% of the children pretreatment and in 100% of the children seven days after SP treatment but in only 33% of age-matched control samples collected during the season of low parasite transmission. IgG ANA subset levels to dsDNA were significant in 81% of both the pre- and post treatment samples, whereas ANCA levels were positive in only 14% of both the pre-and post-treatment samples. Our results suggest that an inverse relationship between TGF-b and CRP levels may contribute to homeostasis and that TNF-a-associated NET formation and ANA may induce pathology in falciparum-infected children or activate a protective mechanism against falciparum malaria in adults. The significance of in vivo circulating chromatin in NETs and ANA to dsDNA as a causative factor in the hyporesponsiveness of CpG olignucleotide-based malaria vaccines is discussed. / A Dissertation submitted to the Department of Biological Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Degree Awarded: Spring Semester, 2007. / Date of Defense: April 5, 2007. / Anti-Neutrophil Cytoplasmic Antibodies, Innate Immune Protection, ANA, ANCA, Neutrophil Extracellular Traps, Falciparum Malaria, Vaccine Hyporesponsiveness, Nets, Anti-Nuclear Antibodies, Autoimmunity, Cytokines / Includes bibliographical references. / Thomas Keller, III, Professor Directing Dissertation; Qing-Xiang Sang, Outside Committee Member; Robert H. Reeves, Committee Member; Kenneth H. Roux, Committee Member; Wu-Min Deng, Committee Member.
76

A Survey of Control Measures Employed for Specific Communicable Diseases in Defiance County Public Schools

Gecowets, Max E. January 1949 (has links)
No description available.
77

A Survey of Control Measures Employed for Specific Communicable Diseases in Defiance County Public Schools

Gecowets, Max E. January 1949 (has links)
No description available.
78

Selected risk factors associated with failure to receive immunizations in an age-appropriate manner /

Young, Seth Allen January 1985 (has links)
No description available.
79

Prevention of epidemics /

Chen, Jiunn-charn January 1986 (has links)
No description available.
80

Availability of essential medicines for chronic disease vs. communicable disease in Kenya as an indicator of age-related inequities in access

Cepuch, Christina January 2012 (has links)
Magister Public Health - MPH / Background: A growing concern about possible age-related inequities in health care access has emerged in the increasing debate on the challenges of population ageing and health in sub-Saharan Africa. Older persons may experience systematic exclusion from health services. Viewed as one of the poorest, most marginalized groups in SSA societies, older people are deemed to lack access to even basic, adequate health care. There is an assumption, furthermore, that older persons have less access to required health services than do younger age-groups. This suggests an element of age-related inequity. One possible indicator of age-related inequity may be found through measuring the relative availability of essential medicines for chronic non-communicable diseases (NCD), relative to the availability of medicines for communicable diseases (CD). Aim and objectives: The aim of the study was to compare the availability of essential medicines for NCD and CD in Kenya, as an indicator of age-related inequities in access to health care in Kenya. The three study objectives were as follows, in public and mission facilities in Kenya: 1. To assess the availability of medicines for the following CD: diarrhoea, HIV, malaria, pneumonia and other infections 2. To assess the availability of medicines for the following NCD common in older populations: arthritis, diabetes, glaucoma, gout, heart disease, hypertension and Parkinson’s disease 3. To compare the availability of medicines for CD and NCD and draw conclusions on possible age-related inequities in access. Study design: Using an adapted version of the HAI / WHO methodology, a cross sectional descriptive survey of medicines availability was conducted. HAI and WHO collaboratively developed a standardized and validated methodology for comprehensively measuring medicines availability, as well as prices, affordability and price components. The survey manual, launched in 2003 and revised in 2008, is available to the public. The methodology involves collecting data on the availability and price of medicines found in a sample of health facilities across sectors of interest within national health systems. If the specific medicine, dose and form being surveyed is available on the day of the survey, then the medicine is documented as being available. Methods: Random sampling was carried out in six of Kenya’s eight provinces, targetting ten facilities per province. Data on availability of the targeted medicines was collected by trained data collectors on pilot-tested data collection forms adapted from the standardized WHO / HAI methodology. The list of medicines included sixteen for communicable diseases to treat infections such as diarrhoea, HIV, malaria, and pneumonia and twelve medicines used to treat non-communicable diseases such as diabetes, arthritis, hypertension, gout, glaucoma, stroke and Parkinson’s disease. Availability of medicines was noted by physical observation by a data collector, and calculated as the percentage of facilities where a medicine was found on the day of data collection. The availability of brands and generics was not distinguished and were combined to establish availability of each medicine. Overall availability of all CD and NCD medicines was compared, and within each category between rural and urban areas and between mission and public facilities. The Ministry of Health was informed of the survey and provided the data collectors with an MOH endorsement letter. The names of facilities participating in the study were recorded on the data collection forms, but not reported. No data on individual patients was collected, and no patients were interviewed for this survey. Data were entered into an Excel file and exported to and analyzed with SPSS. Results: A total of 56 facilities were surveyed: 49 in the public sector and 7 in the mission sector, giving a facility response rate of 93%. Thirty facilities were located in rural settings and 26 were in urban settings. More CD medicines were available than medicines for NCD. Of a total of 896 individual observations of CD medicines, 632 (70.5%) were recorded as available on the day of visit, compared to 306 (45.5%) of 672 possible individual observations of NCD medicines. These differences were highly significant statistically (chi-square=98.8, p<0.001). Furthermore, comparison of availability between urban and rural areas showed statistically significant differences for NCD medicines (40.6% vs. 51.3%, p=0.007), but not CD medicines (72.5% vs. 68.3%, p=0.190). There were no significant differences in availability of medicines in mission compared to public facilities. Conclusions: This study reveals the low relative availability of medicines for NCDs in Kenya’s public and mission sector. Medicines for NCDs were less available in rural vs. urban facilities, but there was no rural vs. urban difference in medicines for CDs. While more research should be carried out to understand the reasons behind these findings, immediate attention to the supply and financing of medicines for NCDs is urgently needed. The relatively lower availability of medicines for NCDs than for CDs may be an indicator of age-related inequities in access to health care in Kenya and calls for more investigations on equity and access to health for older people in Kenya.

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