Articial spin ice structures are two-dimensional systems of lithographically fabricated lattices ofelongated ferromagnetic islands, which interact via dipolar interaction. These systems have beenshown to be a suitable playground to study the magnetic, monopole-like, excitations, similar tothose in three-dimensional rare-earth pyrochlores. Therefore, such articial structures can be potentialmaterials for investigations of magnetricity [1]. The investigations of these articial spin icestructures stretches from the direct imaging of the magnetic congurations among the islands to indirectinvestigation methods allowing to determine the phase transitions occurring in such systems. Inthis project, square articial spin ice arrays were investigated employing magneto-optical Kerr eectfor the measurement of the magnetic susceptibility. The susceptibility dependence on temperaturewas measured at dierent frequencies of the applied AC magnetic eld for arrays of the dierentisland spacing and at two dierent incident light directions with the respect to the direction of theislands. A peak shift of the real part of susceptibility, χ', with increasing frequency towards thehigher temperatures was observed. Furthermore, a rough estimation of the relaxation times of themagnetic moments in the islands is given by the analysis of the susceptibility data.

No description available.

While Rhodococcus equi (R. equi) remains the most common cause of subacute or chronic granulomatous bronchopneumonia in foals, development of a relevant model to study this bacterium has proven difficult. As a result, the reasons for the underlying foal’s susceptibility to this disease are not well understood. Furthermore, data regarding the immune response of foals to R. equi infection remains controversial. We hypothesized that foals are susceptible to R. equi early in life and that this susceptibility decreases with age. Also, we hypothesized that specific subclasses of IgG antibodies to the virulence-associated protein of R. equi, VapA, predict the outcome of exposure. The objectives of this study were: (1) to develop an R. equi challenge model that resulted in slow progressive disease in some foals as well as spontaneous regression of lesions in others, (2) using the developed model, to investigate the age-related susceptibility of young foals to R. equi, (3) to describe the humoral immune response of foals following experimental challenge and natural infection. The use of a low dose of R. equi to challenge neonatal foals resulted in slow, progressive disease characterized by pulmonary abscessation and spontaneous regression in approximately 50% of the foals. When this low dose was used in 1, 2 or 3-week-old foals, a marked decrease in disease susceptibility was observed as the foals aged. The immunological responses seen after experimental challenge reflect those observed after natural infection. While there was a significant increase of VapA-specific IgG and IgG subclasses over time in both pneumonic and healthy foals, use of VapA-specific IgG(T) showed good sensitivity and specificity when used as a diagnostic tool for R. equi pneumonia. In summary, this study shows that foal susceptibility to R. equi occurs early in life and decreases with age. Whereas all foals developed VapA-specific IgG antibodies post-exposure, IgG(T) appeared to be predictive of infection.

Carbonatites are carbonate-rich magmatic rocks that are rare and of great relevance for our understanding of crustal and mantle processes. Although found on all continents and in settings ranging from Archaean to present-day, their deeper plumbing system is still poorly understood. Therefore, the main goal of this thesis is to broaden the existing knowledge of carbonatite systems, often limited to surface geological observations, by providing depth constraints using a number of geophysical methods and petrophysical measurements. The Alnö alkaline and carbonatite complex in central Sweden was chosen for this purpose. Data from three reflection seismic lines, ground gravity and magnetic measurements are presented. These data are complemented by a series of petrophysical measurements, including ultrasonic velocities, density, magnetic bulk susceptibility, anisotropy of magnetic susceptibility (AMS), and magnetic remanence, to aid in the interpretation of the geophysical data. The reflection seismic data indicate a solidified saucer-shaped fossil magma chamber at about 3 km depth. Caldera-style volcanism, constrained by surface geological observations, provides a plausible scenario to explain the emplacement of the complex, suggesting that carbonatite magmas have been stored, transported and erupted in a similar manner to known emplacement mechanisms for silicic calderas, although these are compositionally different. The AMS data from most of the carbonatite sheets in Alnö show a strong degree of anisotropy and oblate-shaped susceptibility ellipsoids. A set of syn- and post-emplacement processes that may control the AMS signature is evaluated based on the dataset. Overprinting of the primary flow patterns by processes related to sheet closure at the terminal stage of magma transport may explain the AMS observations. A complementary study using 3D inversion of ground gravity and aeromagnetic data was then carried out to better delineate the 3D internal architecture of the complex. Resulting models indicate a depth extent of the complex to about 3-4 km, consistent with the interpretation of the reflection seismic data. The modelling results of a ring-shaped magnetic anomaly observed in the Klingefjärden bay adjacent to Alnö Island further suggest that the complex may extend laterally about 3 km towards the north.

Empirically-based models of landslide distribution and susceptibility are currently the most commonly used approach for mapping probabilities of landslide initiation and analyzing their association with natural and anthropogenic environmental factors. In general, these models statistically estimate susceptibility based on the predisposition of an area to experience a landslide given a range of environmental factors, which may include land use, topography, hydrology and other spatial attributes. Novel statistical approaches include the generalized additive model (GAM), a non-parametric regression technique, which is used in this study to explore the relationship of landslide initiation to topography, rainfall and forest land cover and logging roads on Vancouver Island, British Columbia. The analysis is centered on an inventory of 639 landslides of winter 2006/07. Data sources representing potentially relevant environmental conditions of landslide initiation are based on: terrain analysis derived from a 20-m CDED digital elevation model; forest land cover classified from Landsat TM scenes for the summer before the 2006 rainy season; geostatistically interpolated antecedent rainfall patterns representing different temporal scales of rainfall (a major storm, winter and annual rainfall); and the main lithological units of surface geology. In order to assess the incremental effect of these data sources to predict landslide susceptibility, predictive performances of models based on GAMs are compared using spatial cross-validation estimates of the area under the ROC curve (AUROC), and variable selection frequencies are used to determine the prevalence of non-parametric associations to landslides. In addition to topographic variables, forest land cover (e.g., deforestation), and logging roads showed a strong association with landslide initiation, followed by rainfall patterns and the very general lithological classification as less important controls of landscape-scale landslide activity in this area. Annual rainfall patterns are found not to contribute significantly to model prediction improvement and may lead to model overfitting. Comparisons to generalized linear models (i.e., logistic regression) indicate that GAMs are significantly better for modeling landslide susceptibility. Overall, based on the model predictions, the most susceptible 4% of the study area had 29 times higher density of landslide initiation points than the least susceptible 73% of the study area (0.156 versus 0.005 landslides/km2).

Dietary habits which seriously erode health and quality of life are widespread. Effective clinical strategies for overweight, obese and eating disordered individuals are needed. Such treatment options are usually based on constructs generated by theoretical models of causation and maintenance. Underpinning the current enquiry, the Hypno-socio-cultural model hypothesises links between the aetiology of dysfunctional eating behaviours and higher levels of hypnotic susceptibility, fantasy ability and dissociative capacity, as well as acknowledging the social genesis of the self-defeating approach to diet. Empirical evidence has supported the socio-cognitive theory of causation and remediation, on which this research is based. The literature has suggested that hypnotic, imaginative and dissociative strategies have contributed to clinical efficacy, and that aetiology and maintenance of such self-defeating eating might be linked to higher than average hypnotic susceptibility, imaginative ability and dissociative capacity. Generalization of research findings across studies is limited by the uncertainty introduced by the variety of measuring instruments utilized, and gender and age differences which have emerged. As well, possible individual preferences for specificity of hypnotic suggestions, which may affect responsivity levels, could dictate a need for reinterpretation of the results of relevant research. As an initial step in exploration of these issues, a group of University students responded to a number of assessment instruments, designed to tap self-perceptions in relation to weight, shape and size concerns, eating behaviours, and use of imaginative, dissociative and hypnotic capacities, as well as responding to hypnotic suggestions embedded in a formal assessment thereof. In this current research, expected relationships between elements of the Hypno-socio-cultural model were probably affected by a complex array of factors, which are difficult to measure using current instruments. Case studies drawn from the participants in this study have further elucidated the possible connections underlying the proposed Hypno-Socio-Cultural model, as well as highlighting the complexity of the relationships of all the factors involved. The Phenomenology of Consciousness Inventory, which was used to access the subjective experience of the individual’s responsivity to hypnotic suggestion, and which also tapped imaginative and dissociative experiences in relation to same, appears to have unique potential for further exploration of issues related to the connections highlighted in this study Findings in the current study suggested that some widely used assessments were not measuring the same constructs. Because of such factors, results which suggested links between weight, shape and eating measures, and those assessing hypnotic susceptibility, fantasy-proneness and dissociative capacity, although in the expected direction, were not as strong as was expected. In light of the anecdotal evidence of effective clinical use of imaginative, dissociative and hypnotic techniques with self-defeating eaters, the results were reassessed. It seemed feasible to interpret these results as suggesting that higher reliance on self-protective and defensive modes of using imaginative and dissociative capacities may mark the self-defeating eater. A modified Hypno-Socio-Cultural model, incorporating such a possibility, has been proposed as the basis for further study. It is recommended that such research be undertaken, employing a variety of relevant measures, with a larger group of participants of both genders with DSM-IV criterion diagnosed self-defeating eating. The importance to clincial work of investigating the proposed model as a basis for treatment remains paramount in this field of self-defeating eating.

Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection, predominantly experienced by children in sub-Saharan Africa. Patients with CM are comatose and often convulse, develop retinal haemorrhages and motor abnormalities. Recent histological studies on brain tissue obtained from patients who have died from CM have identified heterogeneity in brain pathology. As a result, CM is considered to be a complex disease that may be comprised of a number of syndromes. Patients admitted to hospital with CM are treated with anti-malaria drugs; however, even in the best equipped hospitals, a large number of CM patients die within the first 24-hours following hospital admission before the anti-malarial treatment can have an effect. For this reason, it is critical that the mechanisms leading to CM are elucidated in order to develop effective adjunct therapies. Experimental cerebral malaria (ECM) caused by P. berghei ANKA (PbA) infection of susceptible mice displays many features of human CM. A key feature of this model is the pivotal role of the host immune response in pathogenesis, particularly the involvement of T cells. Evidence, predominantly from ECM studies, suggests that tumour necrosis factor (TNF) superfamily (TNFSF) members play critical roles in the immunopathology associated with CM. The first hypothesis investigated in this thesis was that key immune response pathways contribute to the development of CM and, despite the heterogeneity observed between CM patients, common pathways exist that may be targeted to prevent CM. The second hypothesis tested was that members of the TNF superfamily modulate the immune response to infection and are involved in the development of pathology observed in severe malaria (SM). In order to investigate the above hypotheses, three projects were carried out. First, we examined the great heterogeneity in brain expression profiles between ECM-susceptible CBA/CaH (CBA) and C57BL/6 (B6) mice at the peak of disease, as well as the significant differences in circulating cytokine expression and expansion of microglia in brain tissue. We found that, despite these differences, common therapeutic and preventative strategies existed to disrupt the development of ECM in the two ECM-susceptible mouse strains. Second, studies in ECM mice have identified T cells and TNFSF members, TNF and lymphotoxin (LT)-a, as critical mediators of ECM pathology. We extend these studies to examine the role of the TNFSF member LIGHT in ECM. Specific blockade of LIGHT signalling through its receptor, LTβR, in PbA-infected B6 mice abrogated the hallmark features of ECM brain pathology and improved the control of parasite growth. Importantly, specific blockade of LIGHT-LTβR signalling caused the expansion of splenic monocytes and an overall enhanced capacity to remove and process antigen during infection. Together, this study discovered a novel pathogenic role for LIGHT and LTβR in ECM and identified this TNF family receptor-ligand interaction as a potential target for therapeutic intervention in SM. Finally, we investigated the role of LTa in human SM and, more specifically, CM. We tested whether the polymorphisms within the gene encoding LTa (LTA) were associated with susceptibility to SM in Papuan Highland children and adults who had migrated from an area without malaria pressure to a region where malaria is endemic. Despite a lack of association between single nucleotide polymorphisms (SNPs) in the LTA/TNF locus and susceptibility to SM in Papuan Highland children and adults, we found a significant association between a SNP in the LTa-related gene encoding galactin-2 (LGALS2) and susceptibility to CM in children, but not adults in this study population. Interestingly, no association was found between this SNP and susceptibility to CM in Tanzanian children originating from and living in a malaria endemic region. These results suggest that there may be differences in the mechanisms leading to CM in adults and children, as well as between individuals from malaria endemic and non-endemic areas. Together, the findings outlined in this thesis are important to both the understanding of the underlying mechanisms leading to CM and to the development of improved interventions and adjunct therapies.

Thesis (Ph. D. in Human Genetics)--Vanderbilt University, May 2009. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Florida State University, 2004. / Advisors: Dr. Naresh Dalal, Dr. Johan van Tol, Florida State University, Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed Jan. 18, 2005). Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1948.