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Nordwall, Fredrik. "Stream fish population response to harvesting /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5867-6.pdf.
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Schroeder, Nathan. "Response to population in corn hybrids with specific characteristics." Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/35767.
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Master of AgribusinessDepartment of Agricultural Economics
Allen M. Featherstone
Examining the interaction between population and corn yield is important because the challenge of feeding the world is real. Projections show the world population is increasing and expected to reach over 9 billion people by around 2050. Expanding global urbanization drives the need to increase corn yield on current land and needs to occur to meet global population growth. Previous studies on corn yield increases conclude that ear size is limited and increasing corn plants per acre is important to increasing yield potential. This study used Answerplot data to analyze the effect of increasing plant population on corn yield in 2009. There are over 150 Answerplots across the cornbelt. The weather of 2009 proved to be a challenging year in certain regions of the cornbelt. Record rainfall, and below normal temperature had an influence on corn yield. A total of 4,180 observations from Answerplot were used from across the nation to analyze the relationship between corn yield and plant population. Multiple regression models were estimated and found that in 2009, an increase in plant population from 30,000 to 40,000 plants per acre resulted in an 8.5 bushel per acre increase. This result was robust for various econometric models. Economically, the cost per acre for current seed for this increase in population is about $38.87 per acre. At a corn price greater than $4.58 per bushel, increasing plant population would have made economic sense for 2009.
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Scott, Finlay. "Predicting the response of density dependent population models." Thesis, University of East Anglia, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426988.
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Dinsmore, Teresa J. "Response perseveration and personality features in the college population." Virtual Press, 1991. http://liblink.bsu.edu/uhtbin/catkey/834149.
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An association between antisocial and histrionic personality disorders has been examined in familial and intrapersonal research. This association was explored within the framework of Gorenstein and Newman's (1980) model of disinhibitory psychopathology. Two studies were proposed to examine the association of these personality disorder features, with the second study contingent on the results of the first experiment. The first study investigated whether the response perseveration phenomenon would generalize to college students identified with antisocial personality features using a card playing task developed by Newman, Patterson, and Kosson (1987). Results indicated that the response perseveration phenomenon did not generalize, however, college females identified with antisocial features performed in a similar fashion on the card playing task as Newman et al.'s psychopathic subjects. The evidence gathered from this study suggest that whether the response perseveration phenomenon generalizes to antisocial feature college women requires further investigation.Department of Psychological Science
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Keyes, Marilyn Theresa Carleton University Dissertation Psychology. "Predicators of response to dexfenfluramine in a bulimic population." Ottawa, 1995.
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Lstibůrek, Milan. "Population response to positive assortative mating in forest tree breeding." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-03142005-083542/.
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Positive assortative mating (PAM) may substantially enhance genetic variance in a breeding population (BP). This creates potential for additional genetic gains available through production populations (PP) to forest plantations. Open-nucleus strategies (NB) have been incorporated in forest tree breeding programs. In NB, the BP is subdivided into two hierarchical levels, a nucleus and a main population, and can be considered a less rigorous form of PAM. First, PAM was compared to NB by stochastic simulation considering jointly genetic gain and diversity within the framework of a long-term breeding program. Test effort was either assumed constant throughout the entire BP or was redirected according to the rank of each mate. The simulation revealed that PAM results in larger gains in the PP compared to NB under both situations and at any target PP diversity. Second, the test effort during PAM was redirected by varying family sizes as a linear function of mid-parent BLUP values. The actual distribution of mid-parent BLUP values was standardized by a constant value, which was varied in simulation scenarios to cover the entire range of the distribution of family sizes. When equal numbers of progenies were selected per family and the variation in family sizes was maximized, only a minimal reduction in BP diversity was observed, compared to cases with constant family sizes. Under such favorable conditions, the redistribution of resources increased genetic response and variance in the BP, causing substantially greater genetic response in the PP. These conclusions were verified under a mixed-inheritance model with a major-gene locus contributing to variation in a quantitative trait. Finally, the investigation of PAM was extended by considering correlated traits within the framework of a clonal forestry program. The success of somatic embryogenesis in families generated by crossing elite genotypes developed in the breeding program was either considered exponentially distributed or constant. The distribution of success caused non-significant differences in genetic gain of PP. These conclusions were verified over a range of correlation, heritabilities and economic weights of traits.
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Sri, Raja Lourdes Omesha. "The population response of hematopoietic stem cells differentiating into granulocytes." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10047267/.
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The stepwise transition of a myeloid progenitor cell to a functional neutrophil requires cytokines and their cognate receptors to provide signalling input during each stage of differentiation. The aim of this project was to experimentally characterize the changing signalling events that occur during this process over a period of 17 days by obtaining dynamic time course data on intracellular signalling protein activation states. The steady state expression of phosphorylated and total levels of Erk1/2, PKB/Akt, STAT3 and STAT5 was measured at various time points throughout the differentiation process. Each of these reporter proteins characterises the signalling status of four distinct collateral signalling pathways activated by the GCSF receptor, a major regulator of the differentiation process. Once a data set had been obtained varied statistical inference methods were used to derive causal inferences between the activation states of these "beacon protein" signalling markers in order to identify possible novel mechanisms of direct or indirect crosstalk, between the signalling pathways. Interestingly some of the newly identified crosstalk interactions validated observations made in other experimental systems, and also suggested potential future experiments to follow up and validate further the inferred network. Understanding how to manipulate these signalling networks could have therapeutic value and these newly identified cross talk events could contribute to a deeper understanding of the cytokine-driven differentiation of stem cells required to achieve successful and useful interventions. In conclusion, the application of mathematical models and statistical inference algorithms to existing and novel experimental data sets has enabled novel conclusions to be drawn about signalling and protein interaction dynamics in the regulation of protein cellular decisions in a heterogeneous population of cells.
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Podéus, Henrik. "Neural response of a Neuron population : A mathematical modelling approach." Thesis, Linköpings universitet, Avdelningen för medicinsk teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-177797.
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The brain – the organ that allows us to be aware of our surroundings – consists of a complex network of neurons, which seemingly allows the human brain to be able of abstract thinking, emotions, and cognitive function. To learn how the brain is capable of this, the two main branches of neuroscience study either neurons in detail, or how they communicate within neuronal networks. Both these branches often tackle the complexity using a combination of experiments and mathematical modelling. A third and less studied aspect of neuroscience concerns the neurovascular coupling (NVC), for which my research group has previously developed mathematical models. However, these NVC models have still not integrated valuable data from rodents and primates, and the NVC models are also not connected to existing neuronal network models. In this project, I address both of these two shortcomings. First, an existing model for the NVC was connected with a simple model for neuronal networks, establishing a connection between the NVC models and the software NEURON. Second, we established a way to preserved information from NVC data from rodents and mice into NVC models humans. This work thus connects the previously developed NVC model both with data from other species and with other types of models. This brings us one step closer to a more holistic and interconnected understanding of the brain and its many intriguing cognitive and physiological functions.
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Spencer, Stephen. "Pulse fishing of a walleye population, response, recovery and management implications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0013/MQ33452.pdf.
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Mathew, John. "Spectrum of autoantibody response to tumour associated antigens in normal population." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/56070/.
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Early detection and diagnosis of cancer has a significant impact on cancer specific mortality as shown in randomised screening trials for breast, colon and lung cancer. However, current screening tests have limitations as they reduce cancer specific mortality for breast, colon and lung cancer by only 24%, 16% and 20% respectively, and partly as a result cancer continues to be one of the common causes of death in the developed world(Aberle et al, 2011; Hardcastle et al, 1996; Larsson et al, 1996). One of the other problems associated with current screening tests is patient compliance (mammography, colonoscopy and CT) (Jonnalagadda et al, 2012; Maurer, 1995; Pooler et al, 2012). Diagnosing cancers with a blood test by identifying tumour associated antibodies in serum is a novel method which may allow the identification of early stage cancers and hopefully it would have greater patient acceptability. These tumour associated antibodies represent an indirect amplified signal generated as a response by the immune system to tumour associated antigens secreted early on in development of cancer. One of the common limitations of many autoantibody studies is the selection of appropriate controls - or the lack of such. One common problem is the use of limited number of normal individuals without cancer as controls, the data from which may not be representative of the normal population as a whole (Stockert et al, 1998). In addition not only the numbers of controls are often incorrect but also the age of the controls. Many studies report using 'blood donors' as controls(Guy et al, 1981) and clearly for most tumour types this involves both a younger population and also a relatively health population which may not always be reflective of the individuals to be screened (e.g. compare heavy smokers). We hypothesised that autoantibody response to cancer associated antigens may alter with demographics (age, sex, and smoking) and the aim of our study was to identify the spectrum of response of tumour associated antigens in a range of demographic groups within the normal population of the East Midlands. EarlyCDT-Lung™ is a simple commercial blood test which is reported to aid the early detection of lung cancer. The technology was initially developed in the laboratories of the Division of Breast Surgery and subsequently underwent further development by the university spinout company, Oncimmune. EarlyCDT-Lung initially measured autoantibodies (AAbs) to six cancer associated antigens (p53, NY-ESO-1, CAGE, GBU4-5, Annexinl, and SOX2) and was reported to identify up to 40% of lung cancers, at both at eariy- and late-stage disease(Boyle et al, 2011; Chapman et al, 2012; Chapman et al, 2011; Lam et al, 2011; Macdonald et al, 2012a; Macdonald et al, 2012b; Murray et al, 2010).The initial technical (Murray et al 2010) and clinical (Boyle et a;l 2011; Lam et al 2011) validation studies matched high risk individuals to every lung cancer patient. Controls were individually matched to a patient with lung cancer by age, gender and smoking history. As the 6 antigen panel had been developed and validated (Boyle et al, 2011; Murray et al, 2010) it was decided to proceed to assess the level of autoantibodies across the population and in particular to look at differences by gender and different decades of life. We used a semi-automated Enzyme linked immunosorbent assays (ELISA) to run the serum samples collected from individuals with no previous history of cancer. Informed consent was taken prior to a detailed health questionnaire and then a blood sample by standard venipunture. The information acquired in the questionnaire included age, gender, smoking history, any autoimmune disease and family history of cancer. Serum samples used in this thesis were collected from 2065 individuals. Male to female ratio was 1: 2.6(566:1487). Ratio of smoker versus ex-smokers versus non-smoker was 1: 2.4: 3.8 (285:672:1096). There was a fall in the number of smokers with increasing decade of life. The proportion of smokers and ex-smokers versus non-smokers remained approximately the same in both genders. Almost half the patients (964) had family history of some form of cancer. One hundred and eighty six subjects (9%) had personal history of autoimmune disease. Analysis of autoantibody levels revealed a small but steady increase with increasing age for 4 out of the 6 antigens (p53, NY-ESO-1, CAGE and GBU4- 5). Except for CAGE, there was no significant difference in mean optical densities between males and females. For CAGE, when analysis of variance was used to adjust for run differences, there was no significant difference in mean optical densities between males and females. Autoantibody response to all 6 cancer related antigens were consistently low in smokers. The rise in autoantibody response was more in the ex-smoker group compared to the other two groups suggesting the possibility of rebound effect when smoking is stopped. It reached statistical significance except in case of NY-ESO-1. Age matched analysis were done, and the differences were statistically significant for p53, GBU 4-5 and Annexinl. To explore further the "rebound" hypothesis further, the year of quitting for ex-smokers were extracted from the database. Any association between AAb levels and time lapse since quitting might provide support to this hypothesis. Very little difference was seen for most antigens back to 1970, but decades before that there was an observed increase in the mean AAb level for all antigens except SOX2. Further work would be required to establish such a rebound effect. Family history and history of autoimmune disease did not have a significant impact on autoantibody levels. Analysis of autoantibody levels in a large cohort of the normal population of the East Midlands revealed that age has a small but significant influence on the serum levels of certain autoantibodies to cancer related antigens. However, this could be confounded by the fact that incidence of cancer also increases with age, and would need further investigation and in particular longer followup of patients who have given blood in this research study to see which individuals have developed cancer.
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Comella, Natalia 1974. "Characterization of a transcriptional response to population density in Bacillus subtilis." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/30069.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 2004.Includes bibliographical references.
Bacteria keep track of their population density by using extracellular signaling molecules. In response to the accumulation of these signals, changes in gene expression coordinate the switch from unicellular activity to group behavior. In Bacillus subtilis, this shift towards social behavior occurs, in part, through a signaling pathway that monitors the concentration of the ComX pheromone. ComX stimulates the receptor ComP which activates the transcription factor and response regulator ComA, resulting in the regulation of competence development and other processes. I characterized the signaling pathway and the ComA-mediated cellular response by examining global changes in gene transcription. Under the conditions tested, the ComX-P-A pathway is linear; the ComX pheromone acts exclusively on the ComP membrane histidine kinase receptor, which in turn only activates the response regulator ComA. I found that the activation of the ComX-P-A pathway leads to changes in expression of at least 35 transcriptional units; nine of them appear to be directly regulated by ComA. Many of the operons encode genes that affect the membrane and extracellular environment. The signaling pathway positively regulates transcription of genes involved in fatty acid metabolism, antibiotic production, exopolysaccharide biosynthesis, and degradative enzymes. The presence of signal sequences suggests that more than half of the ComA-dependent gene products of unknown function are membrane or extracellular in nature. These physiological changes may allow B. subtilis to become more resistant to the accumulation of toxic products, scavenge alternative nutrient sources, and eliminate possible competitors for those new nutrients.
(cont.) I also analyzed the srfA antibiotic operon, which is directly regulated by ComA. The srfA operon affects transcription of several indirect-ComA targets, including the Fap (fatty acid production) regulon and the antibiotic (skf) operon which regulates timing of sporulation. A product of the 5' end of the srfA operon affects the activity, rather than the stability, of the FapR repressor. A product from the 3' end of the operon may also be involved. In contrast, a product of the 3' end of the srfA operon helps regulate transcription of the skf operon. Irrespective of direct or indirect regulation, these physiological changes allow B. subtilis to adapt to a crowded environment where it competes for limited resources. Changing the membrane and extracellular environment under conditions of high cell density appears to be a conserved response in both Gram-positive and Gram-negative bacteria.
by Natalia Comella.
Ph.D.
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Rostö, Evelina. "Changes in alpine plant population sizes in response to climate change." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-418248.
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Alpine plants are assumed to be in particular danger as the climate changes rapidly worldwide. Specialist alpine species in Norrbotten County, northern Sweden have been surveyed over the last 20 years, providing insight to population dynamics and how the plants might respond to the changing climate. The main current threat to the species is habitat destruction as the climate changes. Variation in the number of plants among populations and years, and correlations with environmental variables were examined. Some species had increased while others had decreased over the years. No uniform relationship for all species and populations were discovered, but some of the species exhibited relationships between population size changes and temperature and precipitation. However, if the future climate in Norrbotten County changes according to the predictions, the habitats of the specialist alpine plants may be severely altered, leaving the species with no alternative places to establish and grow.
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Matsumoto, Audrey. "The Effect of Immediacy and Salience Questionnaire Response Rates." DigitalCommons@USU, 1996. https://digitalcommons.usu.edu/etd/4670.
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In this study, a theory that identified salience and immediacy as two constructs that significantly determine questionnaire response rates was tested. This theory emphasized the importance of identifying and rating factors that impact the immediacy and salience of a questionnaire to a specific population. It was proposed that factors that make a questionnaire highly immediate and salient to a given population should be identified first, and then implemented into the construction and administration of the questionnaire. In this way, researchers can manipulate the variables, which will maximize the response rate for their specific population before distribution. A questionnaire that is highly immediate and salient to a given population was estimated to achieve a response rate of 80% or higher.
The immediacy and salience of several manipulable variables of a questionnaire were rated by a sample characteristically similar to the target population. Three treatments of the questionnaire were sent to three randomly assigned groups of the population. These treatments varied from low, moderate, to high immediacy and salience based on the ratings.
An analysis of the ratings revealed a very strong direct relationship between salience and immediacy. Variables of the questionnaire were rated very similarly between the two constructs. Contrary to Christensen's theory, different levels of immediacy and salience were not found to interact. However, a direct relationship was found between immediacy and salience levels, and final response rates, which was consistent with the theory. The order of response rate percentages for each treatment group reflected the degree of immediacy and salience as measured by the raters.
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Chu, Cindy. "Population dynamics of smallmouth bass (Micropterus dolomieu) in response to habitat supply." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58893.pdf.
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Deeny, Sarah Raphaelle. "Population genetics of Streptococcus pneumoniae : the response to antibiotic and vaccine pressure." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/6219.
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Streptococcus pneumoniae (pneumococcus) is a pathogen and a commensal of the upper respiratory tract, which is a leading cause of child mortality. The development of a successful vaccine against pneumococcal carriage and disease and the ongoing challenge of antimicrobial resistant strains mean that there is an imperative to understand how the pneumococcal population responds to vaccine and antibiotic pressure. Strains of pneumococci with reduced susceptibility to penicillin and other antibiotics have emerged and are a cause of concern, though their clinical impact is unclear. I perform a meta-analysis to examine the impact of antibiotic non-susceptibility on the risk of mortality and show that a meningitis infection with penicillin non-susceptible pneumococci increases the risk of mortality two fold. I then examine why some serotypes of pneumococcus are more likely to carry resistance than others. Using a mathematical model I generate the hypothesis that serotypes with a long duration of carriage are more likely to have a high prevalence of antibiotic resistance than those with a short duration of carriage. Using maximum likelihood estimation, I show that in children less than two years of age, penicillin resistance only occurs in those serotypes whose duration of carriage is nineteen days or more. Having considered the circumstances under which antibiotic resistance carries a selective advantage in a pneumococcal serotype, I then consider the effect that the spread of an advantageous gene has on the genetic diversity in a generalised bacterial population. Most simple models predict that when a novel allele arises in a bacterial population that is fitter than other alleles at that locus, it and its descendents will increase in frequency and sweep to fixation in the population. In the absence of recombination, all genetic diversity at all loci other than those within the sweeping genotype is lost. I consider whether asymmetric recombination can prevent the loss of diversity over the whole genome. I show that asymmetric recombination, when occurring at rates estimated to date from bacterial populations, is not frequent enough to prevent the extinction of alleles from the wild-type population. Finally, I analyse sequence data sampled from carried pneumococci to examine the impact of vaccination on genetic diversity in a pneumococcal population, an example of a selective event in a pneumococcal population.
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Sekhavati, Farzad Verfasser], and Joachim [Akademischer Betreuer] [Rädler. "Dynamic response of individual cells in heterogeneous population / Farzad Sekhavati. Betreuer: Joachim Rädler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2015. http://d-nb.info/1076980732/34.
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Whaley, Joanna. "The physiological response of winter wheat varieties to reductions in plant population density." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368249.
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Bird, David Jonathan. "The response of fish to electricity and its applications in fish population ecology." Thesis, University of Lincoln, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258772.
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Bansept, Florence. "Biophysical modeling of bacterial population dynamics and the immune response in the gut." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS397.
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La première partie de cette thèse porte sur les dynamiques de colonisation d'une population bactérienne au début d'une infection intestinale. Le but est de déduire des paramètres biologiquement pertinents de données indirectes. Un modèle simple est étudié, et l'on discute de l'observable optimale pour caractériser la variabilité d'une distribution d'étiquettes génétiques. Des arguments biologiques et des incohérences entre des observables expérimentales avec le premier modèle motivent l'étude d'un second, où deux sous-populations se répliquent à des taux différents, mais on ne peut pas conclure clairement sur le jeu de données utilisé. La seconde partie porte sur les mécanismes de la réponse immunitaire. Le principal effecteur du système immunitaire adaptatif dans l'intestin, l'IgA (un anticorps), enchaîne les bactéries-filles en agrégats clonaux lors de la réplication. Nous avons contribué à prouver ce phénomène par un modèle qui prédit la réduction de la diversité bactérienne qui en découle. Au sein de l'hôte, l'interaction entre la croissance et la fragmentation des agrégats a pour conséquence le piégeage préférentiel des bactéries à croissance rapide, ce qui pourrait permettre au système immunitaire de réguler la composition du microbiote. A l'échelle de la population-hôte, et dans le contexte de l'évolution d'une résistance aux antibiotiques, si les bactéries sont transmises sous forme d'amas clonaux, alors la probabilité de transmettre une bactérie résistante est réduite dans une population immunisée. Ainsi, des outils de physique statistique nous permettent d'identifier des mécanismes génériques en biologieThe first part of this thesis focuses on the colonization dynamics of a bacterial population in early infection of the gut. The aim is to infer biologically relevant parameters from indirect data. We discuss the optimal observable to characterize the variability in genetic tags distributions. In a first one-population model, biological arguments and inconsistencies between several experimental observables lead to the study of a second model with two-subpopulations replicating at different rates. As expected, this model allows for broader possibilities in observables combination, even though no clear conclusion can be drawn as to a data set on Salmonella in mice. The second part concerns the mechanisms that make the immune response effective. The main effector of the immune system in the gut, IgA (an antibody), enchains daughter bacteria in clonal clusters upon replication. Our model predicting the ensuing reduction of diversity in the bacterial population contributes to evidence this phenomenon, called “enchained growth”. Inside the host, the interplay of cluster growth and fragmentation results in preferentially trapping faster-growing and potentially noxious bacteria away from the epithelium, which could be a way for the immune system to regulate the microbiota composition. At the scale of the hosts population, in the context of evolution of antibiotic resistance, if bacteria are transmitted via clonal clusters, the probability to transmit a resistant bacteria is reduced in immune populations. Thus we use statistical physics tools to identify some generic mechanisms in biology
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Herman, Maria G. "The Population and Behavioral Response of Woodpeckers to the Emerald Ash Borer Invasion." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1279242304.
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Mittal, Sajjan K. "Local and systemic induction of an abundant CD4+CD25+ regulatory T cell population in non-Hodgkin's lymphoma." Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=26200.
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Mittal, Sajjan. "Local and systemic induction of an abundant CD4+CD25+ regulatory T cell population in non-Hodgkin's lymphoma." Thesis, University of Aberdeen, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=26200.
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To investigate their importance in non-Hodgkin’s lymphoma (NHL), I enumerated Treg cells in peripheral blood mononuclear cells (PBMC) and involved tissues from 30 newly diagnosed patients CD25+FoxP3+CD127lowCD4+ Treg cells were increased markedly in PBMC (median=20.4% CD4 T cells, n=20) versus healthy controls (median=3.2%, n=13: p<0.001, rank sum test) and correlated with serum lactate dehydrogenase (n=14; Rs=0.79, p<0.001) and disease stage. I documented poor proliferation of T cells with mitogen ConA and almost none with recall antigens PPD and DPT in both PBMC and involved tissue samples (n=9). T cell hyporesponsiveness was reversed by depleting CD25+ cells (n=4), or by adding anti-CDLA-4 (n=3), supporting the view that Treg cells explain the systemic immunosuppression seen in NHL. As a high percentage of Treg cells were also present in involved tissues (patients’ involved tissues median=38.8% of CD4 T cells (n=15) vs. reactive nodes median=11.6% of CD4 T cells (n=2); p=0.02, rank sum test), I determined if tumour cells could induce a T regulatory phenotype. I incubated CD25+ depleted PBMC with tumour cells in vitro for five days. A dose and time dependent T regulatory phenotype induction from CD25+ depleted PBMC fractions were seen (n=6, maximum induction of 86.7%). Partial induction was seen when these fractions were separated with transwells. These ‘induced Treg cells’ were FACS sorted and suppressed effector T cells proliferation. I conclude that NHL cells are powerful inducers of Treg cells. These cells circulate systemically and induce active immune tolerance both systematically and within tumour microenvironment, thus representing a new therapeutic target in NHL.
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Ali, Qasim. "Contribution to the mathematical modeling of immune response." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2013. http://tel.archives-ouvertes.fr/tel-00905603.
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The early steps of activation are crucial in deciding the fate of T-cells leading to the proliferation. These steps strongly depend on the initial conditions, especially the avidity of the T-cell receptor for the specific ligand and the concentration of this ligand. The recognition induces a rapid decrease of membrane TCR-CD3 complexes inside the T-cell, then the up-regulation of CD25 and then CD25-IL2 binding which down-regulates into the T-cell. This process can be monitored by flow cytometry technique. We propose several models based on the level of complexity by using population balance modeling technique to study the dynamics of T-cells population density during the activation process. These models provide us a relation between the population of T-cells with their intracellular and extracellular components. Moreover, the hypotheses are proposed for the activation process of daughter T-cells after proliferation. The corresponding population balance equations (PBEs) include reaction term (i.e. assimilated as growth term) and activation term (i.e. assimilated as nucleation term). Further the PBEs are solved by newly developed method that is validated against analytical method wherever possible and various approximate techniques available in the literature.
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Jones, Tunisa La'Sure. "Factors that influence individual differences in female sexual response in a college-aged population." Click here to access thesis, 2008. http://www.georgiasouthern.edu/etd/archive/spring2008/tynisa_l_jones/jones_tynisa_l_200801_ms.pdf.
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Thesis (Ed.D.)--Georgia Southern University, 2008."A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Under the direction of William D. McIntosh. ETD. Electronic version approved: May 2008. Includes bibliographical references (p. 64-71) and appendix.
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Lalagüe, Hadrien. "Genetic response of tree population to spatial climatic variation : an experimental genomic and simulation approach in Fagus sylvatica populations along altitudinal gradients." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20042/document.
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Un enjeu majeur de la génétique évolutive est de comprendre comment l'adaptation locale se développe en population naturelle, et comment les différentes forces évolutives y contribuent. Les études expérimentales d'adaptation locale utilisent couramment les gradients altitudinaux présentant une variation spatiale marquée des conditions environnementales. Dans ces conditions, on s'attend à ce que la différentiation génétique pour les caractères (traditionnellement mesurée par QST) et pour les gènes déterminant ces caractères (traditionnellement mesurée par FSTq) le long du gradient soit gouvernée de façon prédominante par la sélection et les flux de gènes, et peu influencée en revanche par la dérive génétique et la mutation. En particulier, des études théoriques ont montré un découplage entre QST et FST lorsque que les flux de gènes sont forts et/ou que la sélection est récente. Dans cette étude, nous avons testé cette hypothèse en combinant une approche de génomique expérimentale et des simulations dans des populations naturelles de hêtre commun (F. sylvatica) séparées de ~trois kilomètres et soumis à des environnements contrastés.Pour l'approche expérimentale, nous avons échantillonné 4 populations sur deux gradients altitudinaux sur le Mont Ventoux (avec une population à haute altitude et une à basse altitude sur chaque gradient). Cinquante huit gènes potentiellement impliqué dans la réponse aux stress abiotiques et dans le débourrement ont été séquencés sur un total de quatre-vingt seize individus, révélant 581 SNPs (Single Nucleotide Polymorphisms). Différentes approches ont été utilisées pour identifier les SNP outlier, présentant une différentiation plus forte qu'attendu sous un modèle neutre sans sélection. Le nombre de SNPs outlier identifié comme étant sous sélection s'est révélé être grandement dépendant de la méthode utilisé. La méthode fréquentiste a détecté de nombreux outliers alors que l'approche bayésienne n'a pu permettre de détecter des SNPs sous sélection. Par ailleurs, nous avons utilisé un modèle mécaniste individu-centré pour simuler les patrons de diversité phénotypique et génétique attendus le long du gradient pour la phénologie du débourrement végétatif, un caractère généralement adaptatif dans la réponse aux variations de température. Les résultats des simulations confirment que la différentiation génétique observée pour le caractère (QST) est généralement plus forte que celle observée au gène (FSTq), et que cette différentiation génétique au trait intervient dès la première génération. Toutefois, les tests d'outlier conduits sur le le modèle simulé ont révélé que plus de 95% des SNPs outlier sont des faux positifs. Comme dans l'approche expérimentale, l'approche Bayésienne ne s'est pas révélé suffisamment fiable pour détecter des QTLs dans des populations spatialement proche et génétiquement faiblement différentiée. Néanmoins une approche multi-locus basée sur un estimateur peu utilisé en génétique (le Zg) a révélé la forte corrélation inter-populations inter-gènes des QTLs confirmant les attendus théoriques. Toutefois, cette approche ne permet pas de détecter précisément les QTLs sans connaissance a priori sur les QTLs. En conclusion, les travaux de cette thèse mettent en évidence la rapidité des changements génétique qui interviennent en moins de 5 générations pendant la modification du climat, et la difficulté de détecter les gènes codant pour des traits complexesA major challenge in population genetics is to understand the local adaptation process in natural population and so to disentangle the various evolution forces contributing to local adaptation. The experimental studies on local adaption generally resort to altitudinal gradients that are characterized by strong environmental changes across short spatial scales. Under such condition, the genetic differentiation of the functional trait (measured by the Qst) as well as the genes coding for trait (measured by Fstq) are expected to be mainly driven by selection and gene flow. Genetic drift and mutation are expected to have minor effect. Theoretic studies showed a decoupling between Qst and Fst under strong gene flow and / or recent selection. In this study, I tested this hypothesis by combining experimental and modelling genomic approach in natural population of Fagus sylvatica separated by ~3 kilometres and under contrasted environments.Sampling was conducted in south-eastern France, a region known to have been recently colonised by F.sylvatica. Four naturally-originated populations were sampled at both high and low elevations along two altitudinal gradients. Populations along the altitudinal gradients are expected to be subjected to contrasting climatic conditions. Fifty eight candidate genes were chosen from a databank of 35,000 ESTs according to their putative functional roles in response to drought, cold stress and leaf phenology and sequenced for 96 individuals from four populations that revealed 581 SNPs. Classical tests of departure of site frequency spectra from expectation and outlier detection tests that accounted for the complex demographic history of the populations were used. In contrast with the mono-locus tests, an approach for detecting selection at the multi-locus scale have been tested.The results from experimental approaches were highly contrasted according the method highlighting the limits of those method for population loosely differentiated and spatially close. The modelling approach confirmed the results from the experimental data but revealed that up to 95% of the SNPs detected as outliers were false positive. The multi-locus approach revealed that the markers coding for the trait are differentially correlated compared to the neutral SNPs. But this approach failed to detect accurately the markers coding for the trait if no a priori knowledge is known about them. The modelling approach revealed that genetic changes may occur across very few generation. But while this genetic adaptation is measurable at the trait level, the available method for detecting genetic adaptation at the molecular level appeared to be greatly inaccurate. However, the multi-locus approach provided much more promise for understanding the genetic basis of local adaptation from standing genetic variation of forest trees in response to climate change
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Baker, William John Jr. "The effects of population doubling on the shear stress response of bovin aortic endothelial cells." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/19600.
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Holloran, Matthew J. "Greater sage-grouse (Centrocercus urophasianus) population response to natural gas field development in western Wyoming." Laramie, Wyo. : University of Wyoming, 2005. http://www.voiceforthewild.org/SageGrouseStudies/Matt%5FHolloran%5FVersion4.pdf.
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O'Connor, Emily Amelia. "Population differences in response to hypoxia : behaviour and physiology of three-spined stickleback (Gasterosteus aculeatus)." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441929.
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van, den Blink Emily. "A Test for Heritable Variation in A Wild Population in Response to Endocrine Disrupting Events." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1499449837.
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Endocrine disrupting chemicals (EDCs) are a pervasive threat to the health of both human and wildlife populations. EDCs bind to hormone receptors and mimic or block their action, causing disrupted growth, metabolism and reproduction. Fertility affected by EDCs might be compensated if some individuals are genetically resistant. Genetic resistance in a variable population might cause hormonal feedback pathways to be more resilient to disruption. The effects of EDCs on fertility will be studied using a naturally variable population. A wild population of neonatal male mice, Peromyscus leucopus, was treated with testosterone propionate during a critical developmental period. Genetic variation was measured by collecting testis and seminal vesicle mass. These results were used to determine the potential change in fertility of the mice. Preliminary results indicate that there is no genetic difference in individuals in their response to EDCs, suggesting that there is no inherited resilience to these chemicals. Ongoing studies on the impact of endocrine disruptors on reproduction will continue to be of increasing importance for determining prevention and treatment methods.
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Saraux, Claire. "Response of penguins to environmental changes across the Southern ocean : from individuals to population trends." Strasbourg, 2011. http://www.theses.fr/2011STRA6192.
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Le changement climatique, dorénavant sans équivoque, devrait se poursuivre voire s’amplifier dans les siècles à venir, affectant profondément la composante biologique de notre planète. Il est donc nécessaire et urgent de mieux comprendre les écosystèmes et leurs réponses face au changement climatique. Au cours de cette thèse, j’ai étudié l’effet du climat dans l’Océan Austral au travers des manchots. Ceux-ci sont souvent considérés comme de bons indicateurs de leurs écosystèmes de part leur position au sommet de la chaîne trophique. Ce travail repose sur des données pluriannuelles collectées sur 3 espèces de manchots à l’aide de systèmes de suivi automatique, visant à minimiser la perturbation par rapport à la méthode habituelle des bagues alaires. Ainsi, nous montrons des effets contrastés du climat sur les différents traits d’histoire de vie chez les manchots royaux, dont la survie juvénile augmentait les années où la température de surface de la mer était élevée, au contraire de la survie adulte et du succès reproducteur. De plus, nous soulignons l’importance de l’échelle temporelle à laquelle on étudie cet effet du climat et la nécessité de l’adapter à la biologie de l’espèce. La mortalité des poussins de manchots pygmées est par exemple concentrée sur quelques semaines, indiquant que le succès reproducteur dépend chez cette espèce de conditions ponctuelles et non des moyennes saisonnières généralement utilisées. Enfin, les capacités différentes des individus à faire face à des conditions de glace variables, observées chez le manchot Adélie, montrent la nécessité de prendre en compte les différences interindividuelles en vue d’une potentielle adaptation des manchotsClimate change is now unequivocal and foreseen to continue within the next centuries, profoundly affecting the biological component of our planet. Thus, it is becoming urgently necessary to increase our understanding of ecosystems and their responses to climate change. In this thesis, we investigated the effects of climate on Southern Ocean ecosystems through the monitoring of penguins. As top-predators, penguins are often considered good indicators of their environment by integrating the effects of climate which occur lower in the food chain. Data were collected over several years on 3 penguin species (little, king and Adélie penguins) using automatic monitoring systems, that we proved to be relatively harm-free compared to the usual but deleterious flipper-banding method. We found king penguin juvenile survival to increase in years of high sea surface temperature by opposition to previous results on adult survival and breeding success, indicating contrasted effects of climate depending on life-history traits. Also, we highlighted the importance of the time-scale at which the effect of climate is investigated and the necessity of adapting it to the species biology. In little penguins, chick mortality was concentrated on some weeks, underlining the dependence of breeding success on punctual conditions instead of the mostly used mean seasonal conditions. Finally, we showed the importance of individual heterogeneity, leading for instance to differences in the ability to face various sea-ice conditions in Adélie penguins. Such inter-individual differences along with behavioural flexibility may play a role in a potential penguin adaption through phenotypic plasticity
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Anders, Judith E. "Senior Graduating Nursing Students: Career Choices in Gerontological Nursing in Response to Expanding Geriatric Population." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc103285/.
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Access to healthcare is needed and wanted by people of all ages and especially by those of the older population. The number of people in the 65 years of age and older population is rapidly growing with their needs expected to have a significant impact on the existing healthcare system and healthcare providers. The impact will be critical given the severe shortage of healthcare providers, especially of nurses and the rate of services being more often provided in non-hospital settings. The objectives of the study were to discover the plans of graduating nursing students as they choose their first place of employment, if they have future plans to pursue a nursing advance practice degree, and if they are very happy with their decision to become a nurse. Data for the study were obtained from a questionnaire presented to senior graduating nursing students. The findings were: (a) Most students prefer a hospital setting. (b) Younger students are three times as likely to seek out the hospital, and 1/3 of the students seek out the hospital setting because they were encouraged to become a nurse. (c) About 70% of the students want to work with their friends while 1/3 will seek the hospital worksite, as it is perceived as being the strongest resource in paying back loans. (d) Nearly 87% are considering the nursing advance practice role, and 52% have interest in the nurse practitioner role. The majority of students identified as very happy with their decision to become a nurse. This study provided insight for schools of nursing as they make curriculum decisions and to businesses as they learn of the preferences and plans of the new emerging nurses.
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Lind, Emma. "Genetic response to pollution in sticklebacks; natural selection in the wild." Doctoral thesis, Stockholms universitet, Zoologiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-89486.
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The last century, humans have been altering almost all natural environments at an accelerating rate, including the Baltic Sea that has highly eutrophicated areas and many coastal industries such as Pulp-mills. For animals living in a habitat that changes there are basically two alternatives, either to cope with the change or become locally extinct. This thesis aims to investigate if recent anthropogenic disturbance in the Baltic Sea can affect natural populations on a genetic level through natural selection. First, we found a fine-scale genetic structure in three-spine sticklebacks (Gasterosteus aculeatus) populations along the Swedish coast (paper I), indicating limited gene-flow between populations in geographic proximity. Different genetic markers, specifically Amplified Fragment Lenght Polymorpism (AFLP, and microsatellites, gave different results, highlighting the heterogeneous character of genomes which demonstrates that it is important to choose a genetic marker that is relevant for the question at hand. With a population genomic approach, and a multilocus genetic marker (AFLP), we detected convergent evolution in genotype composition in stickleback populations living in environments affected by pulp-mill effluent (paper II) and in highly eutrophicated environments (paper III), compared to adjacent reference populations. We found loci, in both studies (paper II, III), that were different from a neutral distribution and thus probably under divergent selection for the habitat differences investigated. The selective effect from pulp-mill effluents were more pronounced, but the two different habitats had mutual characters (AFLP loci). In paper IV, we converted five anonymous AFLP loci to sequenced markers and aligned them to the stickleback genome. Four out of five loci aligned within, or close to, coding regions on chromosome I, chromosome VIII, chromosome XIX and chromosome XX. One of the loci, located on chromosome VIII and identified as under divergent selection in both paper II and III, has been identified in other studies as to be under selection for fresh water adaptation, including Baltic Sea stickleback populations. In conclusion, anthropogenic alterations of natural environments can have evolutionary consequences, probably adaptive, for the animals living there and the evolutionary response exhibited by natural populations can be very fast.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.
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Baxter, Rebecca Jayne. "Role of the major histocompatibility complex in immune responsiveness in a Holstein Charolais cattle cross population." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5267.
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Infectious disease is a major issue facing the livestock industry. Further understanding of the role of genetic factors in the observed phenotypic variability of the immune response to pathogens and vaccination could assist in designing improved preventative measures such as more efficacious vaccines and targeted breeding strategies to select for disease resistance. Major candidate genes for controlling immune responsiveness are located within the major histocompatibility complex (MHC). The highly polymorphic classical MHC genes are key determinants in the strength and type of immune response. However, it has proved difficult to establish genotyping approaches to define functionally relevant allelic variations for outbred species such as cattle, not least because the peptide binding clefts (PBC) of classical MHC molecules are highly polymorphic, and the genes within the MHC complex are closely linked. The overall aim of this project was to investigate the role of MHC genes in immune responsiveness in approximately 200 F2 and backcross Holstein-Charolais cattle. These animals were generated as part of the Roslin Bovine Genome (RoBoGen) herd, established through a quantitative trait loci (QTL) project, in which a number of phenotypic traits including immune traits were measured. The immune traits included responses to a Foot-and-mouth disease virus (FMDV) peptide, and vaccines against bovine respiratory syncytial virus (BRSV), para-influenza virus 3 (PIV-3) and bovine herpes virus-1 (BHV-1), as well as T cell response to Staphylococcus aureus. The immune phenotypes measured included IgG and interferon- (IFN- ) levels and T cell proliferation. The cattle MHC region, known as bovine leukocyte antigens (BoLA), resides on bovine chromosome 23. The BoLA region contains approximately 200 genes most of which are immune-related. Class II gene polymorphisms were considered to be the most likely to influence the immune traits measured, and the project primarily focused on the best defined gene, BoLA-DRB3. A sequence-based typing technique was successfully improved to facilitate genotyping of the PBC of BoLA-DRB3 in all generations of the RoBoGen herd (approximately 400 animals) and identified 24 distinct alleles. The sequence information obtained also enabled further analysis of the role of defined ‘pockets’ within the PBC, which directly determine peptide binding affinity. All datasets were statistically analysed using a residual maximum likelihood (REML) model and it was shown that several of the DRB3 alleles within the RoBoGen herd had highly significant (p<0.05) associations with the immune response to the FMDV peptide. In addition DRB3 alleles were identified which had significant associations with the response to the respiratory pathogen vaccinations and exposure to S. aureus. The pocket analysis also enabled the identification of several amino acid positions within the PBC which were significantly associated with the immune response traits. In order to explore whether DQ Class II gene polymorphisms also played a role in the variability of responses and whether BoLA Class I-Class II haplotypes could be discerned, microarrays which utilized allele specific oligonucleotides for BoLA Class I and Class II DQ genes were employed. In addition, to investigate whether the number of DQ gene pairs per chromosome influenced the responses, a quantitative polymerase chain reaction (qPCR) assay to determine DQA gene dosage was developed. However, due to the extremely complex nature of the BoLA region both, techniques would require improving to be used for large-scale studies. Nonetheless, information about haplotypes was determined from the microarray results and the qPCR technique lays the foundations for future development to investigate DQ gene dosage. The MHC region in cattle is very complex due the high level of polymorphisms and gene duplications. It is likely that many genes play a role in the immune response to both pathogens and vaccines. However, from the evidence presented here, polymorphisms in the PBC of BoLA-DRB3, particularly within the pockets, are significantly associated with variation in immune response to many different antigens and this information could be exploited in the design of vaccines or breeding cattle for improved disease resistance.
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Reif, V. (Vitali). "Birds of prey and grouse in Finland:do avian predators limit or regulate their prey numbers?" Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514288050.
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Abstract
Relationships between predators and prey may affect population dynamics of both parties. Predators may also serve as a link between populations of different prey, e.g., small game and small mammals. I used available data on the diet and reproduction of birds of prey (mainly common buzzards Buteo buteo and goshawks Accipiter gentilis) and video surveillance of their nests, as well as multiannual data on numbers of grouse and small mammals for studying food habits and population dynamics of raptors and their links with population fluctuations of voles and grouse (capercaillie Tetrao urogallus, black grouse Tetrao tetrix and hazel grouse Bonasa bonasia) in western Finland during 1980–1990s when grouse and vole numbers fluctuated in regular cycles.
Microtus voles were the main prey of the buzzards which partly switched their diet to small game (juvenile grouse and hares) in years when vole numbers declined. The nesting rate of buzzards also correlated with vole abundance, but the productivity rate and brood size tended to lag behind the vole cycle. This mismatch between the buzzards' functional and numerical responses resulted in a fairly small impact of buzzards on juvenile grouse, which did not correlate with vole density. The productivity of goshawks followed the fluctuations of grouse density closely whereas the occupancy rate of goshawk territories did so with a two-year lag. The annual numerical ratio of goshawk to grouse was inversely related to grouse density, suggesting that this predator may be a destabilising factor for grouse population dynamics. However, the goshawks' kill rate of grouse showed no clear relations to grouse density. In June–July, these birds of prey (including hen harriers Circus cyaneus) usually killed a relatively small number of grouse chicks. Losses to raptors constituted up to one quarter of grouse juvenile mortality during the two months. We did not find a strong effect of avian predators on grouse juvenile mortality. In boreal forests, predators and other factors of grouse mortality do not operate as one, and there is probably no single factor responsible for the reproductive success of grouse.
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Cristofari, Robin. "Structure and dynamics of the penguin synnomes : understanding seabird life history and response to climate change through population genomics." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAJ005/document.
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L’Océan austral est l’un des pivot des écosystèmes et du climat de notre planète, qui concentre plus de 20% de la productivité primaire marine mondiale. La complexité de ses réseaux trophiques et son inaccessibilité rendent plus encore qu’ailleurs nécessaire l’utilisation d’espèces bio-indicatrices. Plusieurs espèces de manchots (comme le Manchot Royal et le Manchot Empereur) sont ainsi l’objet de programmes de suivi à long terme. Dans cette étude, nous utilisons les données offertes par la génomique des populations (« RAD-sequencing » couvrant le génome de centaines d'individus issus couvrant la distribution de ces deux espèces) et les représentations numériques du climat de l’IPCC-CMIP5 pour calibrer dans le temps long les analyses démographique plus précises réalisées à l'échelle de quelques générations dans le cadre de suivis démographiques, et mieux comprendre la réponse des manchots au changement climatique. Au-delà de ses conséquences immédiates pour l’étude des Manchots en tant que sentinelles de l’Océan Austral, cette étude montre l’intérêt d’une plus forte intégration de la génomique des populations dans les études démographiques et comportementalesThe Southern Ocean plays a central role in the regulation of the Earth’s climate and ecosystems, and accounts for more than 20% of the world’s marine productivity. The complexity of its trohpic networks and its sheer inaccessibility make the use of bioindicator species more necessary there than anywhere else. Several penguin species (such as the King and the Emperor penguin) are therefore the focus of long-term monitoring programs.In this study, we use the information from population genomics (« RAD-sequencing » data covering the genome of hundreds of individuals from the two species’ full distribution) and from IPCC-CMIP5 numerical climate models to calibrate in the long time the more precise demographic analyses realised in the framework of field surveys, and understand penguin responses to cliamte change. Beyond its implications for the study of penguins as sentinels of the Southern Ocean, our work demonstrates the interest of a stronger integration of population genomics in demographic and behavioural investigation
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Pettey, Dix H. "Stimulus Phoria versus Response Phoria in a Prepresbyopic Population at COSI (Center of Science and Industry)." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429719827.
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Janmaat, Jan Germen. "Nation-building in post-Soviet Ukraine educational policy and the response of the Russian-speaking population /." Utrecht : Amsterdam : KNAG ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/83402.
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Farooq, Shegufta Jabeen. "Torsional optokinetic nystagmus : response characteristics measured in the normal population and patients with ocular motor disorders." Thesis, University of Leicester, 2009. http://hdl.handle.net/2381/7364.
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This thesis presents the first detailed study of the torsional optokinetic nystagmus (tOKN) response in the normal population and in patients with oculomotor disorders. The effects on the tOKN response of: (i) stimulus velocity, (ii) stimulus area, and (iii) aging, were investigated in the normal population. The tOKN response was also evaluated in patients with long standing oculomotor disorders, namely strabismus and infantile nystagmus. Torsional OKN responses were recorded using infrared video-oculography and were elicited with volunteers fixating the centre of a large-field rotating sinusoidal grating pattern. Torsional OKN responses were present in all normal young volunteers (n=20) to stimuli rotated in clockwise and anticlockwise directions, and a linear relationship was observed between log stimulus velocity and tOKN slow phase velocity. Torsional OKN also showed brisk responses to peripheral field stimulation in the same subjects. The first report of a significant increase with age in the proportion of absent tOKN responses is also described in normal subjects aged between 19-72 years (n=30). The tOKN response was investigated for the first time in strabismic patients (n=16), comparing horizontal and vertical OKN responses, and also in patients with infantile nystagmus (n=16). OKN responses from strabismus patients demonstrated consistent asymmetry in horizontal and vertical directions. However, a significantly higher incidence of absent tOKN responses in both intorsion and extorsion directions were observed in comparison to controls. Torsional OKN was present in 3 of 16 patients with infantile nystagmus. Torsional OKN is a well developed reflex in the normal population with the capacity to respond in proportion to stimulus velocity and area of stimulation. However, the tOKN response is dramatically affected by (i) the effects of aging, (ii) by the interruption of binocular visual development in patients with strabismus, and (iii) by the presence of infantile nystagmus.
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Becker, Sarah Nthabiseng. "Hanging out with the cool frogs : do operative and body temperatures explain population response to disease? /." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1885431351&sid=4&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Sarkar, Rajesh. "The innate immune response to Mycobacterium tuberculosis is dependent on strain lineage and on host population." Doctoral thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/2719.
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Includes abstract.Includes bibliographical references.
The genome structure of Mycobacterium tuberculosis is strongly clonal, in the absence of horizontal gene transfer. Thus it is feasible that clonal lineages may exhibit particular phenotypic characteristics, which may, in turn, result in differences in virulence or influence their association with particular host populations. Indeed, the global distribution of M. tuberculosis strains is not uniform and certain strain lineages predominate in particular geographical areas. Further, there is evidence that some strain lineages are emerging, suggesting differences in virulence. Firstly, we investigated the association between strain genotype of M. tuberculosis and in vitro correlates of virulence such as growth phenotype and cytokine induction in the monocyte-derived macrophage (MDM) model.
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Haapea, M. (Marianne). "Non-response and information bias in population-based psychiatric research:the Northern Finland 1966 Birth Cohort study." Doctoral thesis, University of Oulu, 2010. http://urn.fi/urn:isbn:9789514261572.
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Abstract Study samples in medical research are selected according to the objectives of the studies. Researchers seek to collect data as extensively and reliably as possible. In practice, however, data are often missing or may be incorrect. This thesis covers some of the problems concerning missing data and data collection in psychiatric research. Methods for adjusting for missing data and for evaluating the reliability of data are presented. The data originate from the Northern Finland 1966 Birth Cohort (N = 12058). This study explored how participation in an epidemiologic study that includes questionnaires and a clinical examination is affected by mental health (N = 11540), and whether non-participants experience more severe clinical symptoms than participants in a psychiatric field study (N = 145) among subjects with a psychosis. Inverse probability weighting (IPW) was used to adjust for non-participation in comparisons of brain volumes between schizophrenia and control groups. The precision of self-reported medication use was also explored (N = 7625). In an epidemiologic study of all cohort members, subjects with a psychiatric disorder participated less actively than those without one. In the psychiatric field study, non participants were more often patients with schizophrenia than other psychoses. The psychiatric symptoms of non-participants were more severe and they needed more hospital care than participants. The use of IPW led to higher estimates of cerebrospinal fluid volume and lower estimates of grey and white matter volumes in schizophrenia patients, and increased the statistical significance of the differences in brain volume estimates between the schizophrenia and control groups. The precision of self-reported data on psychoactive medication use was substantial. Due to non-participation, the true prevalence of psychiatric disorders is probably higher than the prevalence estimates from field studies that are based on data provided by participants only. In order to reflect the true differences in the target population, weighting methods can be used to improve estimates affected by non-participation. Regarding psychoactive medication use, data collected by postal questionnaire can be assumed accurate enough for study purposes. However, it may underestimate the prevalence of medication use due to non-participationAbstract Tutkimusaineisto valitaan tutkimuksen tavoitteiden perusteella. Tavoitteena on kerätä kattava ja virheetön aineisto. Käytännössä kuitenkin osa tiedoista voi puuttua tai olla virheellistä. Tässä väitöskirjassa esitellään yleisesti menetelmiä huomioida puuttuva tieto analyyseissä ja arvioida aineistojen luotettavuutta psykiatrisessa tutkimuksessa. Aineisto perustuu Pohjois-Suomen vuoden 1966 syntymäkohorttiin (N = 12058). Väitöskirjassa tutkittiin, miten psykiatrinen sairastavuus vaikuttaa osallistumiseen epidemiologisessa tutkimuksessa, joka sisälsi kyselyitä ja terveystutkimuksen (N = 11540), sekä erosiko psykiatriseen kenttätutkimukseen osallistuneiden ja osallistumattomien psykoosipotilaiden kliininen taudinkuva toisistaan (N = 145). Käänteisen todennäköisyyden painotusmenetelmää käytettiin korjaamaan puuttuvan tiedon aiheuttamaa virhettä aivovolyymien estimaateissa skitsofreniapotilailla. Lisäksi arvioitiin itse ilmoitetun lääkekäyttötiedon luotettavuutta (N = 7625). Epidemiologisessa tutkimuksessa ne kohortin jäsenet, joilla oli jokin psykiatrinen sairaus, osallistuivat passiivisemmin kuin ne, joilla ei ollut psykiatrista sairautta. Psykoosipotilaat, jotka eivät osallistuneet psykiatriseen kenttätutkimukseen, sairastivat tutkimukseen osallistuneita useammin skitsofreniaa kuin muita psykooseja ja heidän taudinkuvansa oli vakavampi. Painottaminen kasvatti aivonesteen ja alensi harmaan ja valkean aineen tilavuuksien estimaatteja skitsofreniapotilailla, ja lisäsi aivovolyymien erojen tilastollista merkitsevyyttä skitsofreniapotilaiden ja vertailuhenkilöiden välillä. Itse ilmoitetun psykoaktiivisten lääkkeiden käyttötiedon luotettavuus oli merkittävä. Kadosta johtuen psykiatristen sairauksien todellinen vallitsevuus on todennäköisesti korkeampi kuin vallitsevuuden estimaatit, jotka on laskettu tutkimukseen osallistuneiden tiedoista. Painotusmenetelmiä voidaan käyttää parantamaan puuttuvan tiedon vääristämiä estimaatteja, koska painottamalla huomioidaan todellisia eroja kohdeväestössä. Tutkittaessa lääkekäyttötietoa postikyselyillä kerätyn aineiston voidaan olettaa olevan laadultaan riittävä tutkimustarpeisiin
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Baniszewski, Julie. "IRRIGATED ZEA MAYS RESPONSE TO NITROGEN AND HIGH PLANT POPULATION DENSITY IN NARROW ROWS." UKnowledge, 2016. http://uknowledge.uky.edu/pss_etds/73.
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Modern genetics have improved maize hybrids to better tolerate stress, use nutrients more efficiently and potentially yield higher. Management practices, such as narrow row technology and high plant population density (PPD) may further improve yields in modern maize under irrigated, non-limiting conditions. High PPD (74, 99, 124, 148 K seeds ha-1) were tested in narrow rows with up to four nitrogen (N) rates in three locations over two years in Kentucky with a modern maize hybrid in irrigated, non-limiting conditions. Results indicate that optimal seeding rates were 99,000 to 124,000 seeds ha-1, providing maximum yield and highest partial return, likely due to increasing seed number ha-1 and greater canopy closure, although seed size declined and pollination was more asynchronous as PPD increased. Excess N did not overcome silking delay or the decline in kernel mass associated with higher PPD, indicating 252 kg N ha-1 was adequate for high yields at any population, although data indicates better utilization of supplied N at higher populations. Implications can be used to implement better management techniques in high-yielding maize to supplement use of improved genetics.
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Hoffman, Eric Robert. "Biochemical, Fitness, and Genetic Effects of DDT and Malathion Selection on Two Populations of Chironomus riparius : Population and Insecticide Specific Response to Selection for Resistance /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487861796821005.
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Kelfve, Susanne. "Gotta survey somebody : Methodological challenges in population studies of older people." Doctoral thesis, Stockholms universitet, Sociologiska institutionen, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-121167.
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Conducting representative surveys of older people is challenging. This thesis aims to analyze a) the characteristics of individuals at risk of being underrepresented in surveys of older people, b) the systematic errors likely to occur as a result of these selections, and c) whether these systematic errors can be minimized by weighting adjustments. In Study I, we investigated a) who would be missing from a survey that excluded those living in institutions and that did not use indirect interviews, b) how prevalence rates would be affected by these exclusions, and c) whether post-stratifying the data by sex and age (weighting adjustment) would correct for any systematic measurement error. In Study II, we compared mortality and hospitalization rates in those who responded to a postal questionnaire with rates in the target population. In addition, we tested whether a weighting variable created with a number of auxiliary variables could correct for the differences. In Study III, we followed a longitudinal cohort sample for 43 years. By recalculating baseline characteristics at each follow-up, we investigated how the sample changed after a) selective mortality and b) survey non-participation. In Study IV, we investigated whether the systematic non-participation that is likely to occur in surveys of older people affects the association between education and health. In sum, the results of these four studies show that people in the oldest age groups, women, those of low socioeconomic position, and those with the poorest health tend to be underrepresented in surveys of older people. This systematic underrepresentation might lead to an underestimation of poor health and function, a bias that is unlikely to be corrected by weighting adjustments, and to an underestimation of health inequality between educational groups. The results also show that the selective mortality that occurs in longitudinal samples might be compounded by selective non-participation among the most disadvantaged groups.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript.
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Dalin, Peter. "Food-web interactions and population variability of leaf beetles in managed and natural willow stands /." Uppsala : Dept. of Entomology, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s303.pdf.
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Lee, David Jackson. "Population Dynamics of Rhizoctonia Species in Tall Fescue and Creeping Bentgrass in Response to Disease Management Programs." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-07122004-140248/.
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Rhizoctonia species are important pathogens of all turfgrasses, yet little is known about the structure of populations of these pathogens or the effect of disease control programs on population dynamics. Isolates of Rhizoctonia were obtained from a single creeping bentgrass putting green in 2002 and 2003 and from multiple tall fescue landscapes in 2003. Creeping bentgrass isolates were obtained by placing 5 mm soil cores on alkaline water agar, incubated at ~24 C for 1 to 2 days and the actively growing hyphae were transferred to potato dextrose agar (PDA). Tall fescue isolates were obtained from foliar lesions using the same procedures. Isolates were characterized using morphological characteristics, anastomosis reactions, nuclear staining, and ribosomal DNA (rDNA) sequences. From creeping bentgrass, 21 distinct clones of R. solani AG 2-2 IIIB were present in the sample population in 2002. Seven of these clones were also recovered on multiple sampling dates. Fifteen of the 21 clones from 2002 were recovered in 2003. All seven clones that were isolated in multiple sampling dates in 2002 were also recovered in 2003. There were 29 and 21 isolates of R. zeae collected from the sample population in 2002 and 2003, respectively. All 21 clones exhibited similar EC50 values to mancozeb, chlorothanlonil and azoxystrobin. Of 224 isolates collected from tall fescue during 2003, 88 were R. solani AG 1, 105 were binucleate Rhizoctonia CAG 1, 14 were R. zeae, two were R. cerealis, and 15 were not identified to species or AG. One hundred and seventy four of the isolates were assayed for sensitivity to the fungicides flutalonil, iprodione, tebuconazole, and trifloxystrobin. Mean EC50 values varied across fungicides and species, but generally were below 3.3 mg L-1. The diversity of Rhizoctonia populations associated with tall fescue, and the range in fungicide sensitivities among species indicates that response to management programs may vary with location and environment. The effects of phosphorous acid on fungal growth, disease incidence and turfgrass quality was evaluated in vitro and in vivo. Mean EC50 values of azoxystrobin (+SHAM) for R. solani 2-2 IIIB, and AG 1, P. aphanidermatum, and R. zeae were 1.27, 0.04, 0.012, and 0.145 mg L-1, respectively. Applications of phosphorous acid to creeping bentgrass and tall fescue did not significantly reduce brown patch incidence or increase turfgrass quality in field or greenhouse experiments. The benefit of phosphorous acid as a fungicide or plant nutrient is questionable.
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Honarnejad, Saman [Verfasser], and Mathias [Akademischer Betreuer] Hafner. "Dissecting population and single-cell heterogeneity in response to anti-cancer drugs / Saman Honarnejad ; Betreuer: Mathias Hafner." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://d-nb.info/1178009173/34.
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Latimer, Chris E. "Avian population and community dynamics in response to vegetation restoration on reclaimed mine lands in southwest Virginia." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/32773.
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Coal surface-mining is often implicated for its negative impacts on native flora and fauna. However, some studies suggest that, in reclaiming land after mining, there may be potential to create early successional habitat needed by many avian species currently in decline throughout eastern North America. I evaluated nest-site selection and nest success for on reclaimed mine lands in southwest Virginia during the summers of 2010 and 2011. For this nest-site analysis, I focused on 2 bird species common to reclaimed mine lands in southwest Virginia: field sparrows (Spizella pusillia) and indigo buntings (Passerina cyanea). In addition, I assessed bird community attributes in relation to various surface-mine reclamation regimens over a 5-year period from 2007-2011.
For both species, I found estimates of daily nest success to be higher than other estimates reported in the literature; however, empirical estimates of adult and juvenile survival are needed to provide better estimates of population status. For field sparrows, models of avian nest success support the hypothesis that a tradeoff exists between nest concealment and a view of the surroundings for field sparrows. For indigo buntings, year explained the most variation in nest success, with much lower estimates of daily nest survival in 2010, possibly as a result of increased precipitation.
I also assessed avian community dynamics in relation to vegetation changes on reclaimed mine sites and observed a total of 96 species throughout the 4 years of sampling. Local species persistence and species turnover were comparable to another continental scale study conducted using breeding bird survey (BBS) data. Observed changes in community vital rates were likely a result of changes in certain habitat attributes over the 5-year period. Lastly, seven species were unique to certain cover types, suggesting the need to consider landscape level processes when developing restoration guidelines for reclaimed coal surface-mines.Master of Science
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Latimer, Christopher Edward. "Avian population and community dynamics in response to vegetation restoration on reclaimed mine lands in southwest Virginia." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/32773.
Full textAbstract:
Coal surface-mining is often implicated for its negative impacts on native flora and fauna. However, some studies suggest that, in reclaiming land after mining, there may be potential to create early successional habitat needed by many avian species currently in decline throughout eastern North America. I evaluated nest-site selection and nest success for on reclaimed mine lands in southwest Virginia during the summers of 2010 and 2011. For this nest-site analysis, I focused on 2 bird species common to reclaimed mine lands in southwest Virginia: field sparrows (Spizella pusillia) and indigo buntings (Passerina cyanea). In addition, I assessed bird community attributes in relation to various surface-mine reclamation regimens over a 5-year period from 2007-2011.
For both species, I found estimates of daily nest success to be higher than other estimates reported in the literature; however, empirical estimates of adult and juvenile survival are needed to provide better estimates of population status. For field sparrows, models of avian nest success support the hypothesis that a tradeoff exists between nest concealment and a view of the surroundings for field sparrows. For indigo buntings, year explained the most variation in nest success, with much lower estimates of daily nest survival in 2010, possibly as a result of increased precipitation.
I also assessed avian community dynamics in relation to vegetation changes on reclaimed mine sites and observed a total of 96 species throughout the 4 years of sampling. Local species persistence and species turnover were comparable to another
continental scale study conducted using breeding bird survey (BBS) data. Observed changes in community vital rates were likely a result of changes in certain habitat attributes over the 5-year period. Lastly, seven species were unique to certain cover types, suggesting the need to consider landscape level processes when developing restoration guidelines for reclaimed coal surface-mines.Master of Science
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Cindi, Zinhle. "The role of genetic variation in VKORC1 and GGCX on warfarin response in a South African population." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29461.
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Background: Warfarin is the most commonly used drug in the management of thromboembolic disease. However, there is a huge variability in the management of warfarin affecting the international normalized ratio (INR). Many genetic-association studies have reported on European and Asian populations which has led to the designing of specific algorithms that are now being used to assist in warfarin dosing. However, very few or no studies have looked at the pharmacogenetics of warfarin in African populations, yet, huge differences in dosage requirements to reach the same INR have been observed. We set out to investigate genetic factors affecting warfarin therapy in South African black (SAB) and Mixed Ancestry (MA) participants. Methods: We recruited consenting participants from Groote Schuur Hospital and Gugulethu Community Health Centre comprising 263 of Mixed Ancestry (MA) descent and 109 of South African black (SAB) descent. Demographic data, clinical information and 5 ml of blood for genetic characterization was obtained from participants. DNA was extracted from the blood and genotyped using PCR/RFLP and Sanger sequencing for 5 single nucleotide polymorphisms (SNPs), VKORC1 c.-1639G>A, VKORC1 c.1173C>T, VKORC1 c.3730G>A, GGCX c.1218C>T and GGCX c.1242C>T. Results: We report an association of age with warfarin dose, where, older patients had lower dose requirements (p>0.001 in MA; p>0.042 in SAB). Higher BMI was associated with increased stabilizing dose in the MA group (p=0.003). The SNP VKORC1 c.-1639G>A was associated with stabilizing dose only in MA (p>0.003), with carriers of the A/A genotype requiring lower dosages (18 ± 14 mg/week) compared to G/G (38 ± 14 mg/week). Conclusion: We conclude that environmental and genetic factors may play a role in the way South African patients respond to warfarin. Particularly, it appears as if MA and SAB population group have different underlying genetic markers for warfarin response. This knowledge in warfarin pharmacogenomics could help in the judicious use of warfarin in South African patients. However, more genetic markers need to be characterized to understand the profiles of genetic determinants affecting responses to warfarin therapy in world populations.