High Voltage Pulsed Power Converters for the ESS Linear Accelerator.

Material science has become an important research area in order to fulfill today’s requirements on lighter, cheaper and more sustainable materials. The European spallation source is a research center based on the world’s most powerful neutron source, which will enable new possibilities to evaluate material properties down to an atomic level. The linear accelerator (Linac), accelerates with help of electromagnetic fields, protons to a speed of 96.2 % of the light. Due to high power and the pulsing nature of the accelerator an extremely advanced electrical supply is required. This master´s thesis comprises a concept topology for solving the impact of such pulsed power supplies on the AC grid power quality. The electrical supply consists of two series connected stages, which will be stacked in modulators. The first stage is a low voltage grid connected capacitor bank charger, the second stage converts the power to a high voltage pulsing pattern. This project comprises the first stage (the capacitor charger) which consists of an Active Front End in series with a DC/DC-converter. The main objectives are to fulfil the international standards regarding power quality, where main focus will be on flicker, low frequency harmonics emission and unitary power factor. In order to fulfill these goals with pulsating loads connected, a completely new developed power control introduced. Mathematical models have been derived in order to verify the functionality and to tune all the developed controls. A complete final implementation is done with the help of Matlab Simulink to more in-depth verify the different control parameters. This implementation is also used to check that the international standards are met. Complete calculations of power losses are also presented with evaluation of results and possible improvements. Together with the limitations, goals of the degree project and basic equations are derived in this report. The topology is shown to be extremely effective with very good results in terms of output voltage quality (capacitor charging voltage) and on flicker and low frequency harmonics impact on the grid. Almost every effects due to the pulsing output nature are totally erased seen from the grid side

Vector sums of line segments

The author shows that a necessary and sufficient condition for a convex polyhedron to be representable as a finite vector sum of line segments is that each of its faces possesses central symmetry

The relationship between self-concept and school attendance

The purpose of this study was to seek evidence which might lead to the development of more effective ways of dealing with the problem of failure to attend school. Concept of self has long been considered worthy of consideration in evaluating behavior. It is known that significant experiences in life can modify self concept. This study selected 58 truant (T) students on the basis of 10 unexcused absences in a 4 week period from school during one academic year and 58 non truant (NT) students randomly selected from a total group of several hundred students electing to participate in a vocational skill training program, and tested the following hypotheses: I. There will not be a significant difference between the self concept scores of the student who poses an attendance problem and the student who does not pose an attendance problem as measured by the Tennessee Self Concept Scale. II. Self concept of attendance problem students will not change significantly after being in the George Emory School District Skill Center for one semester. III. After having been in the George Emory School District Skill Center for one semester there will be no significant differences between the gain scores of the attendance and nonattendance problem student. Hypothesis I was statistically tested to determine differences in self concept with two tailed unpaired t tests on the 4 mean score areas of the Tennessee Self Concept Scale (T) group vs. (NT) group. Null hypothesis II was statistically tested by comparison of the (T) group pretest vs. (T) group post test scores in the 4 mean score areas of the instrument after one semester of treatment with two tailed paired t tests. Null hypothesis III was tested by (a) repeating the procedure outlined in Null Hypothesis II for the (NT) group and (b) comparing after treatment the (T) mean gain scores vs. the (NT) group mean gain scores with two tailed unpaired t tests on the 4 score areas of the instrument. It was concluded that: 1. There is no difference at the .05 statistical significance level in self concept between the truant and non-truant populations studied as measured by the Tennessee Self Concept Scale score areas. The means of the four self concept score areas of the instrument seem to imply that the truant population had a lower self concept in two of the four score areas than the non-truant population. 2. Rescheduling into the elective vocational skill program used in this study did not improve self concept in any of the 4 score areas at the .05 statistical level of significance for the truant group. The means in three of the four score areas did reveal a trend toward improvement after treatment and there was a favorable change in standard deviation in two of the four score areas. 3. There was no increase at the .05 statistical level of significance in the positive gain scores for the truant population when compared to the non-truant population after treatment as measured by the four self concept score areas of the Tennessee Self Concept Scale. The non-truant group population means in the 4 score areas revealed a trend toward improvement in self concept in all 4 score areas of the instrument. One area (D), at the .05 statistical level of significance, there was a favorable change in the standard deviation for the non-truant group after treatment in one score area of the four. The truant population gain means in the 4 self concept score areas revealed a trend toward larger gain in 3 of the 4 score areas than the non-truant population

Groundwater chemistry along flow paths between a proposed repository site and the accessible environment

The Nevada Nuclear Waste Storage Investigations Program of the Department of Energy is investigating Yucca Mountain in the Nevada Test Site as a possible repository location. As part of this investigation, the groundwater from all pumped wells in and near the site has been sampled and analyzed; the results are reported in this document. The speciation and solubility of nuclear waste elements in these groundwaters have been calculated using the EQ3/6 computer code. Estimates have also been made of the pH and Eh buffering capacity of the water/rock system of Yucca Mountain

Chemical Composition of Ground Water and the Locations of Permeable Zones in the Yucca Mountain Area, Nevada

Ten wells in the Yucca Mountain area of southern Nevada have been sampled for chemical analysis. Samples were obtained during pumping of water from the entire well bore (composite sample) and in one instance by pumping water from a single isolated interval in well UE-25b#1. Sodium is the most abundant cation and bicarbonate the most abundant anion in all water samples. Although the general chemical compositions of individual samples are similar, there are significant differences in uncorrected carbon-14 age and in inorganic and stable-isotope composition. Flow surveys of seven wells performed using iodine-131 as a tracer indicate that ground-water production is usually from one or more discrete zones of permeability

Variation in plasma calcium analysis in primary care in Sweden - a multilevel analysis

<p>Abstract</p> <p>Background</p> <p>Primary hyperparathyroidism (pHPT) is a common disease that often remains undetected and causes severe disturbance especially in postmenopausal women. Therefore, national recommendations promoting early pHPT detection by plasma calcium (P-Ca) have been issued in Sweden. In this study we aimed to investigate variation of P-Ca analysis between physicians and health care centres (HCCs) in primary care in county of Skaraborg, Sweden.</p> <p>Methods</p> <p>In this cross sectional study of patients' records during 2005 we analysed records from 154 629 patients attending 457 physicians at 24 HCCs. We used multilevel logistic regression analysis (MLRA) and adjusted for patient, physician and HCC characteristics. Differences were expressed as median odds ratio (MOR).</p> <p>Results</p> <p>There was a substantial variation in number of P-Ca analyses between both HCCs (MOR_HCC1.65 [1.44-2.07]) and physicians (MOR_physician1.95 [1.85-2.08]). The odds for a P-Ca analysis were lower for male patients (OR 0.80 [0.77-0.83]) and increased with the number of diagnoses (OR 25.8 [23.5-28.5]). Sex of the physician had no influence on P-Ca test ordering (OR 0.93 [0.78-1.09]). Physicians under education ordered most P-Ca analyses (OR 1.69 [1.35-2.24]) and locum least (OR 0.73 [0.57-0.94]). More of the variance was attributed to the physician level than the HCC level. Different mix of patients did not explain this variance between physicians. Theoretically, if a patient were able to change both GP and HCC, the odds of a P-Ca analysis would in median increase by 2.45. Including characteristics of the patients, physicians and HCCs in the MLRA model did not explain the variance.</p> <p>Conclusions</p> <p>The physician level was more important than the HCC level for the variation in P-Ca analysis, but further exploration of unidentified contextual factors is crucial for future monitoring of practice variation.</p

Digital methods for ethnography: analytical concepts for ethnographers exploring social media environments

The aim of this article is to introduce some analytical concepts suitable for ethnographers dealing with social media environments. As a result of the growth of social media, the Internet structure has become a very complex, fluid, and fragmented space. Within this space, it is not always possible to consider the 'classical' online community as the privileged field site for the ethnographer, in which s/he immerses him/herself. Differently, taking inspiration from some methodological principles of the Digital Methods paradigm, I suggest that the main task for the ethnographer moving across social media environments should not be exclusively that of identifying an online community to delve into but of mapping the practices through which Internet users and digital devices structure social formations around a focal object (e.g., a brand). In order to support the ethnographer in the mapping of social formations within social media environments, I propose five analytical concepts: community, public, crowd, self-presentation as a tool, and user as a device

Primary Hyperparathyroidism Influences the Expression of Inflammatory and Metabolic Genes in Adipose Tissue

Background: Primary hyperparathyroidism (PHPT) is characterised by increased production of parathyroid hormone (PTH) resulting in elevated serum calcium levels. The influence on bone metabolism with altered bone resorption is the most studied clinical condition in PHPT. In addition to this, patients with PHPT are at increased risk of non-skeletal diseases, such as impaired insulin sensitivity, arterial hypertension and increased risk of death by cardiovascular diseases (CVD), possibly mediated by a chronic low-grade inflammation. The aim of this study was to investigate whether adipose tissue reflects the low-grade inflammation observed in PHPT patients. Methodology/Principal Findings: Subcutaneous fat tissue from the neck was sampled from 16 non-obese patients with PHPT and from 16 patients operated for benign thyroid diseases, serving as weight-matched controls. RNA was extracted and global gene expression was analysed with Illumina BeadArray Technology. We found 608 differentially expressed genes (q-value,0.05), of which 347 were up-regulated and 261 were down-regulated. Gene ontology analysis showed that PHPT patients expressed increased levels of genes involved in immunity and defense (e.g. matrix metallopeptidase 9, S100 calcium binding protein A8 and A9, CD14, folate receptor 2), and reduced levels of genes involved in metabolic processes. Analysis of transcription factor binding sites present in the differentially expressed genes corroborated the up-regulation of inflammatory processes. Conclusions/Significance: Our findings demonstrate that PHPT strongly influences gene regulation in fat tissue, which may result in altered adipose tissue function and release of pathogenic factors that increase the risk of CVD

Effect of eplerenone on parathyroid hormone levels in patients with primary hyperparathyroidism: a randomized, double-blind, placebo-controlled trial

<p>Abstract</p> <p>Background</p> <p>Increasing evidence suggests the bidirectional interplay between parathyroid hormone and aldosterone as an important mechanism behind the increased risk of cardiovascular damage and bone disease observed in primary hyperparathyroidism. Our primary object is to assess the efficacy of the mineralocorticoid receptor-blocker eplerenone to reduce parathyroid hormone secretion in patients with parathyroid hormone excess.</p> <p>Methods/design</p> <p>Overall, 110 adult male and female patients with primary hyperparathyroidism will be randomly assigned to eplerenone (25 mg once daily for 4 weeks and 4 weeks with 50 mg once daily after dose titration] or placebo, over eight weeks. Each participant will undergo detailed clinical assessment, including anthropometric evaluation, 24-h ambulatory arterial blood pressure monitoring, echocardiography, kidney function and detailed laboratory determination of biomarkers of bone metabolism and cardiovascular disease.</p> <p>The study comprises the following exploratory endpoints: mean change from baseline to week eight in (1) parathyroid hormone(1–84) as the primary endpoint and (2) 24-h systolic and diastolic ambulatory blood pressure levels, NT-pro-BNP, biomarkers of bone metabolism, 24-h urinary protein/albumin excretion and echocardiographic parameters reflecting systolic and diastolic function as well as cardiac dimensions, as secondary endpoints.</p> <p>Discussion</p> <p>In view of the reciprocal interaction between aldosterone and parathyroid hormone and the potentially ensuing target organ damage, the EPATH trial is designed to determine whether eplerenone, compared to placebo, will effectively impact on parathyroid hormone secretion and improve cardiovascular, renal and bone health in patients with primary hyperparathyroidism.</p> <p>Trial registration</p> <p>ISRCTN33941607</p