Type IV pili (T4P) are long, fibrous surface appendages involved in attachment, motility, biofilm formation and DNA uptake that are expressed by bacteria and archaea. They are an important virulence factor for a number of bacteria, including Pseudomonas aeruginosa, an opportunistic pathogen that is a common cause of nosocomial infections. T4P are composed mainly of monomers of the major pilin subunit, PilA, although several low abundance proteins called minor pilins are also present. These surface-exposed proteins are potential vaccine candidates, although a more complete understanding of their diversity and function is required for the rational development of a pilus-based vaccine. There are five distinct groups of P. aeruginosa major pilins, which vary based on their sequence and their associated accessory proteins, and two distinct sets of minor pilins, although the roles of the latter in pilus biology are poorly understood. This study focuses on the structural characterization of major and minor pilins and functional implications for pilus assembly and disassembly dynamics. The structural analysis of major pilins from groups III and V revealed specific differences in pilin structure that may affect subunit interactions within the pilus fibre and interactions with their specific accessory proteins and minor pilins. The minor pilins PilVWX were shown to form a putative subcomplex with the adhesin and anti-retraction protein PilY1, which is proposed to prime pilus assembly and thus traffic PilY1 to the bacterial surface. High resolution X-ray crystal structures of the minor pilins FimU and PilE were solved and functional characterization suggested that FimU and PilE are necessary for efficient pilus assembly to stably connect the priming subcomplex to the major pilin subunits. Together, this work has increased our understanding of pilin diversity and defined a concrete role for the minor pilins in pilus assembly. / Thesis / Doctor of Philosophy (PhD) / Pseudomonas aeruginosa is a bacterium that can take advantage of a weakened immune system to cause lethal infections. The first step of infection involves attachment to the host using long sticky fibres called type IV pili. Each fibre is composed primarily of a single protein, the major pilin, but also contains low abundance proteins called minor pilins. Without these proteins, the bacteria can’t attach and cause infections, making pilins excellent vaccine candidates. This study focused on the characterization of major and minor pilins to understand the diversity of these proteins and how these differences might affect pilus assembly. We show that the molecular structure of the major pilin differs between strains although the core architecture is the same, and that the minor pilins are required for initiation of pilus assembly. This work furthers our understanding of the structures and functions of pilin proteins, and provides information helpful for the development of vaccines.

No description available.

Clostridium perfringens is a Gram-positive anaerobe capable of causing disease in humans and many animals. C. perfringens is able to move across surfaces in a manner that is dependent on growth and type IV pili. Type IV pili are filaments that can be extended away from the cell by rapid polymerization, and retracted by depolymerization. Furthering the understanding of the initial and final energetic states of the pilins will reveal insights into possible mechanisms of type IV pilus assembly. Toward that end, a pilin was purified from the Gram-negative pathogen Pseudomonas aeruginosa and incorporated into an artificial membrane. The pilin was probed by a solid state nuclear magnetic resonance (ssNMR) technique that can determine the angle and depth of insertion of a helical peptide, as well as fluorescent and electron microscopy. All type IV pilus systems involve the action of an assembly ATPase to provide energy to polymerize the pilus. One proposed mechanism involves two primary proteins: an ATPase and an integral membrane core protein (IMCP). Other type IV pilus proteins are thought to play supportive roles in aiding the traversal of the cell envelope. In order to evaluate this model, the assembly ATPase PilB2 and IMCP PilC2 from C. perfringens were purified and examined for interactions. The evidence presented here suggest that PilB2 and PilC2 do not interact directly, and cannot function as a core assembly apparatus. The carbonic anhydrase (Cpb) from C. perfringens strain 13 was characterized both biochemically and physiologically. Cpb belongs to the type I subclass of the β class and is the first β class enzyme investigated from a strictly anaerobic bacteria. Kinetic analyses revealed a two-step, pingpong, zinc-hydroxide mechanism of catalysis. Analyses of a cpb deletion mutant of C. perfringens strain HN13 showed that Cpb is strictly required for growth when cultured in semi-defined medium and an atmosphere without CO₂. The grew well in nutrient-rich media with or without CO₂ in the atmosphere, although elimination of glucose resulted in decreased production of acetate, propionate, and butyrate. The results suggest a role for Cpb in anaplerotic CO₂ fixation reactions by supplying bicarbonate to carboxylases. / Ph. D.

Traumatic Brain Injury (TBI) is a major concern for health professionals as it is a leading cause of death and disability in the United States. Patients can experience difficulties that include intellectual impairment, memory impairment, and executive functioning deficits. Psychometric tests have been used to assist in the diagnosis of head injuries. Specifically, the Wechsler scales are recognized in the scientific and medical communities as the most widely utilized measure of general intellectual function in older adolescents and adults. The recently published Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) is a revision of the WAIS-III. No studies have been published to date relevant to the effects of head trauma or other neurological disorders due to the recent introduction of the test. The purpose of the study was to understand the immediate intellectual consequences of head injury in adults along a continuum of severity, evaluate whether new additions to the WAIS-IV provide additional information about the effects of head trauma, and determine if the length of recovery affects the WAIS-IV indices differently. A total of 47 participants between the ages of 18-89 were selected from inpatient and outpatient admissions at a major trauma center. Participants who had sustained a closed-head injury were selected and tested between 1 month and 36 months post-injury (once any post traumatic amnesia had resolved). Patients were administered the Galveston Orientation Amnesia Test, Wechsler Test of Adult Reading, and WAIS-IV. The main question addressed by the current study was the extent to which brain injured adults display intellectual deficits and if these were consistent with those observed on prior versions of the Wechsler scales. An examination of the pattern of intellectual impairments and the effects of demographic corrections on the WAIS-IV was also conducted. Results indicated that the WAIS-IV IQ and indexes were reduced significantly by traumatic brain injury, and that more severe injuries were likely to show the most pronounced effect on the Processing Speed Index. Abnormalities visualized by brain CT or MRI scans were associated with lower IQ's and index scores than were shown by patients with traumatic head injury that had normal CT scans. There was no evidence that corrections for educational level, ethnicity, and gender improved the sensitivity of the WAIS-IV to injury severity beyond that obtained by corrections for age.

A series of oxovanadium(IV) complexes of Schiff bases derived from substituted salicylaldehyde and aminoalcohols has been prepared and characterized. The Schiff bases coordinate through 0, N, and 0 as tridentate bivalent ligands. The primary purpose of the investigation is to describe the structure and bonding in these complexes. The subnormal magnetic properties of the complexes provide much information about both the structure and the bonding in the complexes.

The different interpretations of the character of Sir John Falstaff have been so controversial that at no time since the presentation of the Henry IV plays have critics been able to agree as to his precise qualities. He has been called the greatest humorous character in all literature by even those critics who have spoken adversely of his other traits. George Bernard Shaw called him "a besotted and disgusting old wretch," an opinion added to those of others who have seen him as a coward, liar, cheat, thief, glutton, and rogue. There is no denying that he is one of the most captivating and controversial of all characters in English literature.

The question of magic in the later middle ages has a rather long tradition in the Bohemian historical milieu in the argument over the manuscripts of Kues. However, it is only one of the very aspects of the subject, and others were until now more or less neglected. Therefore I would like to bring a new fresh perspective and clearly define the field of research into its dynamic complexity. My argument is composed from three integrally interconnected parts. Firstly, I should bring forward the question: What is magic? The exact definition of this word is still not agreed upon despite the grand effort of scholars not only from the last decades. By examination of the word "magic" I have to have as a condition a very good referential background for it. With the second question, I concentrate on diachronic of the historical context and its dynamics of the transfer and contra-transfer of learned magic in Bohemia. At last, I am taking into account the close investigation of the written sources and the overall dynamics of the bigger European picture of the period. The main argument proposed by this thesis, is that the used sources are predating the Kues manuscript and that in the 14th century the unprecedented growth of the artistic faculty of the Prague university, as one of the first, brought into play the...

Chapter 1: We provide first evidence of a link from daily air pollution exposure to sleep loss in a panel of Chinese cities. We develop a social media-based, city-level metric for sleeplessness, and bolster causal claims by instrumenting for pollution with plausibly exogenous variations in wind patterns. Estimates of effect sizes are substantial and robust. In our preferred specification, a one standard deviation increase in AQI causes an 11.6% increase in sleeplessness. The results sustain qualitatively under OLS estimation but are attenuated. The analysis provides a previously unaccounted-for benefit of more stringent air quality regulation. It also offers a candidate mechanism in support of recent research that links daily air quality to diminished workplace productivity, cognitive performance, school absence, traffic accidents, and other detrimental outcomes. Chapter 2: We provide linear and non-parametric estimates of the causal impact of short-term exposure to polluted air on the prevalence of cough in a panel of a hundred Chinese cities. In our central estimate, which exploits plausibly-exogenous variations in the number of agricultural fires burning in the vicinity as an instrument, we find that a one standard deviation increase in airborne pollution causes a roughly 5% increase in the prevalence of cough in the affected city. Amongst pollutants the effect can be tied specifically to particulate matter (PM2.5). The results prove resilient in a series of robustness tests and falsification exercises. Chapter 3: We provide the first study of the relationship between air pollution and students' migration intentions for higher education. Young people's interest in local study is proxied by their Baidu search index for local universities. The IV method is supplemented to identify the causal link by instrumenting for particular matter with plausibly exogenous variations in temperature inversion strength. The estimates of effect sizes are substantial and robust. When air quality in Beijing moves from good-day level to moderately-polluted level, people's search for local education decreases by 3.8% under OLS and 11.8% under IV. The results release the signal that people lost their interest in local universities due to the elevated air pollution. There could be future out-migration to cleaner cities for higher education.

Classification systems in psychiatry are a work in progress. Therefore, continued efforts to improve their validity are necessary. Epidemiology provides a scientific method to assess the extent of psychiatric morbidity in community populations. However, data from epidemiological surveys have also contributed, either directly or indirectly, to many changes in the classification systems. Recent reviews of the current state of psychiatric classification indicate four unresolved issues: 1) the presence of two differing classification systems, 2) the role of the clinical significance criterion in differentiating psychopathology from normality, 3) the relationship of the exclusion criteria to the co-occurrence of psychiatric disorder pairs, and 4) the relative validity of categorical versus dimensional conceptualizations of psychiatric disorders. The current thesis examines these four unresolved issues, using data from a large-scale epidemiological survey of psychiatric disorders. With regard to GAD, differences in diagnostic criteria between DSM-IV and ICD-10 resulted in different types of cases identified, despite similarities in prevalence. The DSM-IV diagnostic criterion for clinical significance impacted, albeit to different degrees, on the prevalence, health service use and impairment of five disorders. The exclusion criteria in both DSM-IV and ICD-10 were significantly related to the patterns of co-occurrence found in the data. Using the example of depression, symptoms were more consistent with a dimensional rather than a categorical structure. A specific research agenda is proposed, the aim of which is to provide possible avenues of research that may benefit revisions to classification systems and the conduct of epidemiological surveys. This research agenda contains a number of suggestions. Future revisions will benefit from an explicit understanding of the differences between the classification systems. Better definitions of the concepts of clinical significance and psychiatric disorder are required. The co-occurrence of disorder pairs in epidemiological data informs understanding of the exclusion criteria, but the validity of these criteria relies on different data. Dimensional models of classification may yield more information than categorical models, and methods for incorporating them in large-scale surveys are proposed. It is concluded that epidemiological data should continue to play a significant part in the refinement of psychiatric classification.

<p>Generation IV (Gen IV) is a developing new generation of nuclear power reactors which is foreseen to bring about a safer and more sustainable production of nuclear power. A Swedish research program called GENIUS aims at developing the Gen IV technology, with emphasis on lead-cooled fast reactors. The present work is part of the GENIUS project, and deals with safeguards aspects for an envisioned future 100 MW Gen IV demonstration facility including storage and reprocessing plant. Also, the safeguards licensing aspects for the facilities have been investigated and results thereof are presented.</p><p>As a basis for the study, the changed usage and handling of nuclear fuel, as compared to that of today, have been examined in order to determine how today's safeguards measures can be modified and extended to meet the needs of the demonstration facility. Safeguards approaches have been considered for within and between each unit at the demonstration facility, with the main focus on system aspects rather than proposing safeguards instrumentation on a detailed level.</p><p>The proposed safeguards approach include the implementation of well-tried measures that are used at currently existing nuclear facilities as well as suggestions for new procedures. The former include, among others, regular inventory verifications, containment and surveillance measures as well as non-destructive and destructive measurements of nuclear materials. The traditional approaches may be improved and supplemented by modern techniques and approaches such as nuclear forensics, safeguards-by-design and improved on-line monitoring of streams of nuclear material. The safeguards approach for the demonstration facility should be outlined early in the licensing process, such that the facility units can be designed in a way that allows for implementation of adequate safeguards measures with minimal intrusion on the regular activities.</p><p>For operating a nuclear facility in Sweden, two separate permits are required. A license application for a new facility shall be handed both to the Swedish Radiation Safety Authority and to the environmental court, which in parallel prepare for decisions according to the Nuclear Activities Act and the Environmental Code, respectively. In terms of the Swedish legislation, there are no fundamental differences between Gen IV facilities and currently existing plants. However, comprehensive investigations and evaluations would be required in order to license new Gen IV facilities.</p>