Abstract The high-latitude polar ionosphere is characterized by two regions, the polar cap and the auroral oval. In the polar cap, the geomagnetic field lines are open and connect to the solar wind, whereas the field lines in the auroral oval are closed and map to the plasma sheet and the plasma sheet boundary layer in the magnetosphere. The two substantially different magnetic and plasma domains are separated by a separatrix, the polar cap boundary (PCB), which is an ionospheric projection of the open-closed field line boundary (OCB) in the magnetosphere. In this thesis, a new method to determine the location of the PCB in the nightside ionosphere based on electron temperature measurements by EISCAT incoherent scatter radars is introduced. Comparisons with other PCB proxies like poleward boundary of the auroral emissions, poleward edge of the auroral electrojets and poleward boundary of energetic particle precipitation show general agreement. By applying the method to several events together with other supporting ground-based and space-borne observations, dynamic processes and phenomena in the vicinity of the PCB and inside the auroral oval are studied. The main results include the following. During substorm expansion, the PCB moves poleward in a burstlike manner with individual bursts separated by 2–10 min, indicating impulsive reconnection in the magnetotail. In one event, a possible signature of the high-altitude counterpart of the Earthward flowing field-aligned current of the Hall current system at the magnetotail reconnection site is observed. Investigation of the relation between the auroral activity and the local reconnection rate estimated from the EISCAT measurements reveals direct association between individual auroral poleward boundary intensifications (PBIs) and intensifications in the ionospheric reconnection electric field within the same MLT sector. The result confirms earlier suggestions of positive correlation between PBIs and enhanced flux closure in the magnetotail. In another event, quiet-time bursty bulk flows (BBFs) and their ionospheric signatures are studied. The BBFs are found to be consistent with the so called "bubble" model with Earthward fast flows inside the region of depleted plasma density (bubble). The tailward return flows show an interesting asymmetry in plasma density. Whereas the duskside return flows show signatures of a depleted wake, consistent with a recent suggestion, no similar feature is seen for the dawnside return flows, but rather increase in density. The BBFs are associated with auroral streamers in the conjugate ionosphere, consistently with previous findings. The related ionospheric plasma flow patterns are interpreted as ionospheric counterpart of the BBF flows, excluding the dawnside return flows which could not be identified in the ionosphere. The BBFs and streamers are found to appear during an enhanced reconnection electric field in the magnetotail.

Insight into the biochemical mechanisms utilized by retaining and inverting glycosyltransferase enzymes is an important stepping stone to the directed design of stereospecific inhibitor based drugs. The suitability of proposed mechanisms was probed using site directed mutagenesis of catalytically relevant residues as well as the use of catalytically inactive substrate analogs UMP-PO2-CH2-D-Gal and α-L-Fuc-(1→2)-β-D-(3-deoxy)-Gal-O(CH2)5CH3 with the retaining human enzyme a specific α-1,3-N-acetylglucosaminyltransferase (GTA) in conjunction with kinetic and structural approaches including two dozen high resolution X-ray structures and a 2.5 Å resolution neutron structure. The neutron structure depicts a remarkably non-polar active site which lacks suitably positioned hydrogen atoms to support a dissociative mechanism. Site directed mutagenesis of residues which should be essential to initiate and stabilize a dissociative oxocarbenium ion do not abolish enzyme activity. The catalytically inactive substrate analogs depict the acceptor nucleophile to lay very close to the anomeric carbon (2.5 Å), which is considerably closer than the closest observed enzymatic dipoles (4.8 Å). This is an indication that the active site architecture is more suited to facilitate a mechanism initiating with nucleophilic attack than dissociation. To ensure that these observations are applicable to other glycosyltransferases, in depth geometric analysis of all published liganded structures of GT-A fold glycosyltransferase enzymes are reported that display conserved architectures in which the acceptor nucleophile approach is closer than enzymatic dipoles required for dissociation for both inverting and retaining enzymes. Inverting and retaining enzymes present the donor sugar through different conserved geometries about the divalent cation cofactor: all inverting enzymes position the donor for inline nucleophilic attack by the acceptor, the retaining enzymes position the sugar to be attacked from an orthogonal angle. Such an orthogonal associative mechanism is the most direct proposed approach, and seems supported by all available evidence. / Graduate

No description available.

Frying in vegetable oil is a popular cooking and food processing method worldwide; as a result, the oils used for frying are widely consumed by the general public and it is of practical importance to better understand their health impacts. To date, the effects of frying oil consumption on human health are inconclusive, making it difficult to establish dietary recommendations or guidelines. Here we show that dietary administration of frying oil, which was prepared under the conditions of good commercial practice, exaggerated dextran sodium sulfate (DSS)-induced colitis in mice. In addition, to explore the potential compounds involved in the actions of the frying oil, we isolated polar compounds from the frying oil and found that administration of the polar compounds also exacerbated DSS-induced colitis in mice. Together, our results showed that dietary administration of frying oil exaggerated development of inflammatory bowel disease (IBD) in mice, and this effect could be mediated by the polar compounds in the frying oil.

TESIS PARA OPTAR AL GRADO DE MAGÍSTER EN FINANZAS / En el presente trabajo se desarrolló una valoración económica y financiera de Empresas La Polar, utilizando como método Flujos de Caja Descontados, esta valoración fue realizada utilizando la información financiera publicada por la empresa hasta el 30 de Septiembre de 2013 en sus memorias y en la Superintendencia de Valores y Seguros. Se realizó un análisis global de la empresa, tanto de su historia, como ha sido su desarrollo, a que segmento está enfocado, como financia sus proyectos, todos estos factores que nos permitieron realizar proyecciones financieras las cuales utilizando como metodología Flujo de Caja Descontados obtuvimos como resultado el precio de la acción. Para realizar las proyecciones financieras necesarias, es importante recaudar información financiera de Empresa La Polar y de la industria en la cual está inserta, para poder determinar cómo es el funcionamiento de esta, como le afectan la variables económicas y así poder construir supuestos consecuentes y conservadores, de modo de que nuestros cálculos sean lo más cercanos a la realidad. El objetivo de este trabajo es mostrar de una manera sencilla cómo se realiza en la práctica un análisis financiero de una empresa, que variables son necesarias tener en consideración, de donde puedes obtener la infurción necesaria para realizar los diferentes cálculos y posteriormente las proyecciones. La Valoración de Empresas, es considerada una buena herramienta en la toma de decisiones de inversión, ya que a través de esto puedes determinar si está en un precio de la acción es mayor o menor a su precio histórico, si es conveniente realizar compras o ventas de dicha acción, nos permite tener una visión basada en fundamentos financieros.

A brief review of the subject of palaeomagnetism as it affects the study of the behaviour of the earth's magnetic field and the problems of Continental Drift and Polar wander is presented, giving the reasons why a systematic palaeomagnetic study of the Cape and Karroo Systems of South Africa would be of outstanding significance. This task was vigorously tackled by sampling the Karroo System at vertical intervals of approximately 50 ft. in two separate areas, using the techniques that were then available. The results, although negative, provide material for a discussion of the possible reasons for the scattered directions of magnetization of the samples. A palaeomagnetic study of the Karroo dolerites was undertaken in an attempt to (i) determine 1 the position of the geomagnetic pole at the time of the intrusions, and (ii) possibly assess the importance of the remagnetization of Karroo sediments by the thermal effects of the younger intrusions. Samples from surface exposures in the eastern half of South Africa, from the shafts of a gold mine and from a railway tunnel were collected and studied, giving a reliable mean direction of magnetization of the Karroo dolerites of Declination= 341°, Inclination= -60°. At the commencement of the Jurassic period the geomagnetic pole relative to Southern Africa had the present day co-ordinates of Longitude 74½ 0 E, Latitude 70° S. Both normally and reversely magnetized dolerites were found and evidence in favour of a true reversal of the earthts magnetic field is advanced. It is also suggested that in the area studied, the dolerite was intruded in two distinct phases. Because the direction of magnetization of the Karroo dolerites is very close to that of the present magnetic field, it is difficult to separate samples remagnetized at the time of the intrusions from those remagnetized in the present field. However, some light is thrown on the problem of the scattered directions of magnetization of the Karroo sediments by the fact that dolerite samples collected from surface exposures are much less consistently magnetized than those from underground workings.

<p>Nitride semiconductors are promising for applications in opto-electronic devices due to their wide band gap that is adjustable by appropriate choice of alloy composition. To date, many III-nitride devices have been demonstrated, such as light-emitting diodes, lasers, etc. Most opto-electronic devices make use of the optical transition from conduction band to valence band. Moreover, the large conduction band offset achieved by III-nitrides makes it possible to take advantage of transitions inside the conduction band or valence band, which provide much more freedom for band engineering. Although many III-nitrides based opto-electronic devices have been invented and implemented in commercial use, there is still a need for more compact, rugged, higher efficiency devices with lower cost. Many challenges of III-nitride semiconductors are related to material defects, lattice mismatch and internal polarization fields. Photoluminescence is a convenient technique to characterize sample quality and optical properties. It does not destroy the samples or need any electrical contacts. Therefore, it is commonly used in qualitative analysis of III-nitrides. This thesis focuses on non-polar m-plane III-nitrides structures, because this crystal orientation eliminates internal polarization fields in heterostructures. We first performed a photoluminescence study of a series of m-plane InGaN thin films with In compositions up to 24.5%. Evidence of large In composition fluctuations was observed. This inhomogeneity of In composition contributes to the non-monotonic temperature dependence of photoluminescence peak energy and linewidth. A large drop of internal quantum efficiency when temperature increases to room temperature was observed, which indicates the presence of a large number of non-radiative recombination centers. This is due to low temperature growth of InGaN by plasma assisted molecular beam epitaxy. The InGaN film with 11% has a linewidth close to theoretical calculations for InGaN with random In distribution, and much smaller than many reported polar c-plane InGaN films with comparable In compositions, which suggests improved material quality. This In composition was selected for the design of InGaN/AlGaN superlattices.</p> <p>In order to avoid the disadvantage of strain buildup, we designed nearly strain-balanced non-polar m-plane InGaN/AlGaN structures with In composition of about 9%. Steady-state photoluminescence and time-resolved photoluminescence were performed on these structures. A significant discrepancy between measured and calculated PL peak positions was observed. This is likely due to the In composition fluctuations and quantum confinement in quantum wells. The broadening mechanism of the PL in the superlattices was investigated. The low-temperature linewidth of undoped superlattices is comparable to many previously reported values for m-plane InGaN/GaN quantum wells. Similar to InGaN films, the internal quantum efficiency drops dramatically when temperature reaches room temperature. Regions with high In compositions act as localization centers for excitons. An average localization potential depth of 21 meV was estimated for undoped superlattices. This small potential depth does not reduce the degree of polarization of emitted light, and contributes to the narrow linewidth. A fast decay time of 0.3 ns at 2 K was observed for both doped and undoped superlattices. This value is much smaller than that for polar c-plane InGaN/GaN superlattices. The localization of excitons was found to be strong and not affected by magnetic field at low temperatures. Compared with undoped superlattices, the doping sheets reduce decay pathways of excitons in doped superlattices.</p> <p> </p>

<p> Cyclic voltammetric oxidation of 1,2,3,4,5-pentaphenylcyclopentadiene has been studied in non-polar chloroalkane solvents (CH2Cl2 and CH2ClCH2Cl). The oxidation is reversible if tetra-n-butylammonium hexafluorophosphate (TBA^+PF6^-) is used as supporting electrolyte, but irreversible when tetra-n-butylammonium perchlorate (TBA^+ClO4^-) or tetra-n-butylammonium trifluoromethane sulfonate (TBA^+OTf^-) are used, and partially reversible when tetra-n-butylammonium tetrafluoroborate (TBA^+BF4^-) is used. Oxidation of 1,2,3,4,5-pentaphenyl-1-methylcyclopentadiene, which has no relatively acidic protons, was reversible with all four supporting electrolytes.</p> <p> The criteria for reversibility were observation of cathodic wave on scan reversal, equal anodic and cathodic peak currents, minor dependence of peak potentials on scan rate, v, and linearity of anodic peak current, ipa with the square root of scan rate, v^1/2 , corresponding to Randles-Sevcik equation for reversible processes.</p> <p> It is proposed that perchlorate (ClO4^-) and triflate (OTf^-) anions are sufficiently basic to accept a proton from 1,2,3,4,5-pentaphenylcyclopentadiene cation-radical intermediate, while tetrafluoroborate (BF4^-) and particularly hexafluorophosphate (PF6^-) are less basic, and therefore less reactive.</p> <p> Controlled potential electrolysis of 1,2,3,4,5-pentaphenylcyclopentadiene with tetra-n-butylammonium perchlorate as supporting electrolyte affords the cation, which is consistent with an ECE mechanism in which the chemical step is proton loss.</p> / Thesis / Master of Science (MSc)

Heart rate variability (HRV) and music have been demonstrated to have a relationship in previous literature. The primary objective of this study is to further investigate that relationship by observing HRV during periods of listening to relaxing and exciting music and comparing the results to a baseline as well as the other condition. The secondary objective of this study is to investigate the efficacy and potential usage of the Polar H10 chest strap monitor in measuring HRV parameters. The results of the Polar H10 will be compared to the iWorx TA-220 and iWorx-ECG12, the existing gold standard in HRV and ECG recording. The data will be exported to Matlab and Excel and analyzed to see if particular types of music display any trends for these HRV parameters, as well as heart rate (HR). Polar data will be gathered and analyzed using the EliteHRV app. Analysis included Fast Fourier Transform (FFT), Low Frequency/High Frequency Ratio (LF/HF), standard deviation of NN intervals (SDNN). Data was gathered in 10 minute intervals of No Music, Relaxing Music, Exciting Music. Results showed notable changes in LF/HF ratio in both directions. SDNN and Mean RR interval had moderate decreases in both relaxing and exciting music, with Total Power having a significant decrease in both. Comparison of Polar H10 and iWorx-ECG data showed strong agreement in heart rate and RR interval data, but significant differences in other data. This suggests differences in calculation by the software used.

The Arctic has long held power over the American imagination as a place of otherworldly beauty, life-threatening elements, and dangerous wildlife. Nearing the end of the nineteenth century, in a time of great anxiety about the direction of American society, the region took on new significance. As a new frontier, the Arctic was a place where explorers could establish a vigorous and aggressive type of American manhood through their exploits. Publications, lectures, newspaper accounts, and other media brought the stories of these explorers to those at home. Through such accounts, the stories of brave explorers counteracted the perceived softening of men and American society in general. Women played a crucial role in this process. They challenged the perceived male-only nature of the Arctic while their depiction in publications and the press contradictorily claimed that they retained their femininity. American perceptions of the Arctic were inextricably intertwined with their perceptions of the Inuit, the indigenous peoples that called the region home. In the late-nineteenth-century, Americans generally admired the Inuit as an exceptional race that embodied characteristics that were accepted in American Society as representing ideal manhood. Over time the image of the Arctic in American society shifted from a terrifying yet conquerable place to an accessible and open place by the 1920s. This "friendly Arctic" - a term coined by anthropologist Vilhjalmur Stefansson - appeared to be a less threatening and intimidating place. Due to new technologies and geographical accomplishments, the Arctic appeared to become more accessible and useable. As the Arctic's depiction in American society gradually shifted towards a more "friendly Arctic," the role of women in the Arctic shifted as well. Women increasingly participated in this new friendly Arctic. While still claiming that their femininity remained, both fictional and non-fictional female explorers participated in a wide array of Arctic activities. The image of the Inuit, too, underwent a transformation. Americans viewed the Inuit with less respect than in prior decades. Open Arctic theories and rising technological advancements contributed to this change. The decline in respect also stemmed from beliefs that the indigenous northerners were set on a course of extinction or assimilation. Ultimately, the late-nineteenth- and early-twentieth-century relationship between Americans and the Arctic laid the foundation for present-day views of the region and the Inuit. / History