Analysis and Implementation of Multiphase-Multilevel Inverter for Open-Winding Loads

Research work carried out in focusing a novel multiphase-multilevel ac motor drive system much suitable for low-voltage high-current power applications. In specific, six-phase asymmetrical induction motor with open-end stator winding configuration, fed from four standard two-level three-phase voltage source inverters (VSIs). Proposed synchronous reference frame control algorithm shares the total dc source power among the 4 VSIs in each switching cycle with three degree of freedom. Precisely, first degree of freedom concerns with the current sharing between two three-phase stator windings. Based on modified multilevel space vector pulse width modulation shares the voltage between each single VSIs of two three-phase stator windings with second and third degree of freedom, having proper multilevel output waveforms. Complete model of whole ac motor drive based on three-phase space vector decomposition approach was developed in PLECS - numerical simulation software working in MATLAB environment. Proposed synchronous reference control algorithm was framed in MATLAB with modified multilevel space vector pulse width modulator. The effectiveness of the entire ac motor drives system was tested. Simulation results are given in detail to show symmetrical and asymmetrical, power sharing conditions. Furthermore, the three degree of freedom are exploited to investigate fault tolerant capabilities in post-fault conditions. Complete set of simulation results are provided when one, two and three VSIs are faulty. Hardware prototype model of quad-inverter was implemented with two passive three-phase open-winding loads using two TMS320F2812 DSP controllers. Developed McBSP (multi-channel buffered serial port) communication algorithm able to control the four VSIs for PWM communication and synchronization. Open-loop control scheme based on inverse three-phase decomposition approach was developed to control entire quad-inverter configuration and tested with balanced and unbalanced operating conditions with simplified PWM techniques. Both simulation and experimental results are always in good agreement with theoretical developments.

Essays in Household and Demographic Economics

This dissertation consists of three empirical studies that are believed to provide new contributions to the literature exploring the determinants of children/adolescents achievement test scores (Chapter 2), adolescent health risk behaviors (Chapter 3), and children time use patterns (Chapter 4). The second and third studies look at the separate roles of fathers and of mothers in influencing outcomes, wherein parental time is the resource input of interest quantitatively measured and directly derived from time diaries. The last chapter looks at the time allocation of children and how it varies according to child and household characteristics.

Eine ökologische Landeskunde der Rhön

Die Ökologische Landeskunde der Rhön – mit einem Schwerpunkt auf dem hessischen Teil – behandelt als moderne Landeskunde neben der Geostruktur und der humangeographischen Struktur im Besonderen die ökologische Struktur, denn nur durch diese Pointierung können Räume in ihrer Gesamtheit und Komplexität beschrieben werden. Das gilt im Besonderen für ökologisch bedeutsame Schutzräume wie die Rhön. Der Mittelgebirgsraum Rhön ist eine über Jahrhunderte gewachsene Kulturlandschaft mit einem weitgehend intakten, aber fragilen Ökosystem, das eine einzigartige und schützenswerte floristische und faunistische Ausstattung aufweist. Durch die weitreichenden mittelalterlichen Rodungen und die anschließende extensive Weidenutzung haben sich unter dem Eingriff des Menschen besonders auf den Höhenlagen im Laufe der Zeit artenreiche und ökologisch bedeutsame Ökosystemtypen, wie Borst- und Kalkmagerrasen, entwickelt. Um das naturräumliche und touristische Potential des Untersuchungsraums langfristig erhalten zu können, haben ökologische und nachhaltige Entwicklungen in den einzelnen Wirtschaftssektoren eine überragende Funktion. Im primären, sekundären und tertiären Sektor zeigen sich deutliche Entwicklungen hin zu ökologischen Erzeugnissen und Dienstleistungen. Der Ökolandbau gewinnt in der Rhön zunehmend an Bedeutung, Betriebe spezialisieren sich immer mehr auf Bio-zertifizierte und regionale Produkte und werben verstärkt mit ökologischen und rhöntypischen Begrifflichkeiten. Vor allem der für die Rhön wirtschaftlich bedeutende Tourismussektor, der im Spannungsfeld zwischen Ökonomie und Ökologie steht, entwickelt sich ebenfalls in Richtung nachhaltiger und umweltfreundlicher Formen. Am Beispiel des Milseburgradwegs konnte anhand einer Besucherbefragung auf Basis standardisierter Fragestellungen mit vornehmlich geschlossenen Fragen gezeigt werden, wie wichtig den Nutzern eine intakte Natur ist und wie Ökotourismus, Wirtschaftlichkeit und Naturschutz koexistieren können. Die Prämierung der Rhön zum Biosphärenreservat Rhön durch die UNESCO im Jahre 1991 erwies sich als Glücksfall und konnte dem strukturschwachen ländlichen Raum wichtige ökologische und wirtschaftliche Impulse geben, vor allem in Richtung ökologischer und nachhaltiger Erzeugnisse und Dienstleistungen. Die Auszeichnung kann dabei als Synthese zwischen Geostruktur und humangeographischer Struktur angesehen werden und ist Würdigung, Mahnung und Pflicht zugleich. Zusätzlich verdeutlicht sie auf eindringliche Weise die Fragilität und Schutzwürdigkeit des Ökosystems. Gegenwärtig zeichnen sich im Untersuchungsraum einige Entwicklungen ab, die die ökologische Raumstruktur gefährden und zusätzlich zur Aberkennung des Titels Biosphärenreservat führen könnten, weshalb sie kritisch gesehen werden müssen. Hier stechen der Bau der geplanten Bundesstraße B 87n von Fulda nach Meiningen oder das Kernzonendefizit hervor. Die Arbeit ist deshalb ein Plädoyer für den unbedingten Erhalt des identitätsstiftenden Titels Biosphärenreservat sowie für eine aktive Umweltbildung, denn eine erfolgreiche Zukunft und Identifikation der Bewohner mit ihrem Heimatraum ist unmittelbar an das Prädikat gekoppelt. Ökologische Landeskunden verstehen sich als aktive Elemente in der Umweltbildung und richten sich an die Menschen, die immer mehr zum prägenden Faktor von Räumen und ihren Ökosystemen werden. In der Rhön können sie sogar als Ausgangspunkt für die Herausbildung aufgefasst werden. Trotz der begrenzten Aussagekraft der Arbeit und der Komplexität des Untersuchungsraums zeigen sich vielfältige, ökologisch relevante Entwicklungen, die jedoch durch weitere sozialwissenschaftliche und wirtschaftswissenschaftliche Arbeiten erweitert, vertieft und stetig abgeglichen werden müssen.

Falcarinol is a covalent cannabinoid CB1 receptor antagonist and induces pro-allergic effects in skin

The skin irritant polyyne falcarinol (panaxynol, carotatoxin) is found in carrots, parsley, celery, and in the medicinal plant Panax ginseng. In our ongoing search for new cannabinoid (CB) receptor ligands we have isolated falcarinol from the endemic Sardinian plant Seseli praecox. We show that falcarinol exhibits binding affinity to both human CB receptors but selectively alkylates the anandamide binding site in the CB(1) receptor (K(i)=594nM), acting as covalent inverse agonist in CB(1) receptor-transfected CHO cells. Given the inherent instability of purified falcarinol we repeatedly isolated this compound for biological characterization and one new polyyne was characterized. In human HaCaT keratinocytes falcarinol increased the expression of the pro-allergic chemokines IL-8 and CCL2/MCP-1 in a CB(1) receptor-dependent manner. Moreover, falcarinol inhibited the effects of anandamide on TNF-alpha stimulated keratinocytes. In vivo, falcarinol strongly aggravated histamine-induced oedema reactions in skin prick tests. Both effects were also obtained with the CB(1) receptor inverse agonist rimonabant, thus indicating the potential role of the CB(1) receptor in skin immunopharmacology. Our data suggest anti-allergic effects of anandamide and that falcarinol-associated dermatitis is due to antagonism of the CB(1) receptor in keratinocytes, leading to increased chemokine expression and aggravation of histamine action.

Causes and mechanisms of intrauterine hypoxia and its impact on the fetal cardiovascular system: a review

Until today the role of oxygen in the development of the fetus remains controversially discussed. It is still believed that lack of oxygen in utero might be responsible for some of the known congenital cardiovascular malformations. Over the last two decades detailed research has given us new insights and a better understanding of embryogenesis and fetal growth. But most importantly it has repeatedly demonstrated that oxygen only plays a minor role in the early intrauterine development. After organogenesis has taken place hypoxia becomes more important during the second and third trimester of pregnancy when fetal growth occurs. This review will briefly adress causes and mechanisms leading to intrauterine hypoxia and their impact on the fetal cardiovascular system.

Dual-energy CT-cholangiography in potential donors for living-related liver transplantation: Improved biliary visualization by intravenous morphine co-medication

PURPOSE: To prospectively evaluate whether intravenous morphine co-medication improves bile duct visualization of dual-energy CT-cholangiography. MATERIALS AND METHODS: Forty potential donors for living-related liver transplantation underwent CT-cholangiography with infusion of a hepatobiliary contrast agent over 40min. Twenty minutes after the beginning of the contrast agent infusion, either normal saline (n=20 patients; control group [CG]) or morphine sulfate (n=20 patients; morphine group [MG]) was injected. Forty-five minutes after initiation of the contrast agent, a dual-energy CT acquisition of the liver was performed. Applying dual-energy post-processing, pure iodine images were generated. Primary study goals were determination of bile duct diameters and visualization scores (on a scale of 0 to 3: 0-not visualized; 3-excellent visualization). RESULTS: Bile duct visualization scores for second-order and third-order branch ducts were significantly higher in the MG compared to the CG (2.9±0.1 versus 2.6±0.2 [P<0.001] and 2.7±0.3 versus 2.1±0.6 [P<0.01], respectively). Bile duct diameters for the common duct and main ducts were significantly higher in the MG compared to the CG (5.9±1.3mm versus 4.9±1.3mm [P<0.05] and 3.7±1.3mm versus 2.6±0.5mm [P<0.01], respectively). CONCLUSION: Intravenous morphine co-medication significantly improved biliary visualization on dual-energy CT-cholangiography in potential donors for living-related liver transplantation.

Sleep-disordered breathing in acute ischemic stroke and transient ischemic attack: effects on short- and long-term outcome and efficacy of treatment with continuous positive airways pressure - rationale and design of the SAS CARE study

Sleep-disordered breathing represents a risk factor for cardiovascular morbidity and mortality and negatively affects short-term and long-term outcome after an ischemic stroke or transient ischemic attack. The effect of continuous positive airways pressure in patients with sleep-disordered breathing and acute cerebrovascular event is poorly known. The SAS CARE 1 study assesses the effects of sleep-disordered breathing on clinical evolution, vascular functions, and markers within the first three-months after an acute cerebrovascular event. The SAS CARE 2 assesses the effect of continuous positive airways pressure on clinical evolution, cardiovascular events, and mortality as well as vascular functions and markers at 12 and 24 months after acute cerebrovascular event.

Phosphocreatine interacts with phospholipids, affects membrane properties and exerts membrane-protective effects

A broad spectrum of beneficial effects has been ascribed to creatine (Cr), phosphocreatine (PCr) and their cyclic analogues cyclo-(cCr) and phospho-cyclocreatine (PcCr). Cr is widely used as nutritional supplement in sports and increasingly also as adjuvant treatment for pathologies such as myopathies and a plethora of neurodegenerative diseases. Additionally, Cr and its cyclic analogues have been proposed for anti-cancer treatment. The mechanisms involved in these pleiotropic effects are still controversial and far from being understood. The reversible conversion of Cr and ATP into PCr and ADP by creatine kinase, generating highly diffusible PCr energy reserves, is certainly an important element. However, some protective effects of Cr and analogues cannot be satisfactorily explained solely by effects on the cellular energy state. Here we used mainly liposome model systems to provide evidence for interaction of PCr and PcCr with different zwitterionic phospholipids by applying four independent, complementary biochemical and biophysical assays: (i) chemical binding assay, (ii) surface plasmon resonance spectroscopy (SPR), (iii) solid-state (31)P-NMR, and (iv) differential scanning calorimetry (DSC). SPR revealed low affinity PCr/phospholipid interaction that additionally induced changes in liposome shape as indicated by NMR and SPR. Additionally, DSC revealed evidence for membrane packing effects by PCr, as seen by altered lipid phase transition. Finally, PCr efficiently protected against membrane permeabilization in two different model systems: liposome-permeabilization by the membrane-active peptide melittin, and erythrocyte hemolysis by the oxidative drug doxorubicin, hypoosmotic stress or the mild detergent saponin. These findings suggest a new molecular basis for non-energy related functions of PCr and its cyclic analogue. PCr/phospholipid interaction and alteration of membrane structure may not only protect cellular membranes against various insults, but could have more general implications for many physiological membrane-related functions that are relevant for health and disease.

P-Technique Factor Analyses of the Multiple Affect Adjective Checklist (MAACL)

The Multiple Affect Adjective Check List (MAACL) has been found to have five first-order factors representing Anxiety, Depression, Hostility, Positive Affect, and Sensation Seeking and two second-order factors representing Positive Affect and Sensation Seeking (PASS) and Dysphoria. The present study examines whether these first- and second-order conceptions of affect (based on R-technique factor analysis) can also account for patterns of intraindividual variability in affect (based on P-technique factor analysis) in eight elderly women. Although the hypothesized five-factor model of affect was not testable in all of the present P-technique datasets, the results were consistent with this interindividual model of affect. Moreover, evidence of second-order (PASS and Dysphoria) and third-order (generalized distress) factors was found in one data set. Sufficient convergence in findings between the present P-technique research and prior R-technique research suggests that the MAACL is robust in describing both inter- and intraindividual components of affect in elderly women.

Bacchus and Civic Order: The Culture of Drink in Early Modern Germany / Bacchus und die bürgerliche Ordnung. Die Kultur des Trinkens im frühneuzeitlichen Augsburg

Lining the streets inside the city's gates, clustered in its center, and thinly scattered among its back quarters were Augsburg's taverns and drinking rooms. These institutions ranged from the poorly lit rooms of backstreet wine sellers to the elaborate marble halls frequented by society's most privileged members. Urban drinking rooms provided more than food, drink, and lodging for their guests. They also conferred upon their visitors a sense of social identity commensurate with their status. Like all German cities, Augsburg during the sixteenth and seventeenth centuries had a history shaped by the political events attending the Reformation, the post-Reformation, and the Thirty Years' War; its social and political character was also reflected and supported by its public and private drinking rooms. In Bacchus and Civic Order: The Culture of Drink in Early Modern Germany, Ann Tlusty examines the social and cultural functions served by drinking and tavern life in Germany between 1500 and 1700, and challenges existing theories about urban identity, sociability, and power. Through her reconstruction of the social history of Augsburg, from beggars to council members, Tlusty also sheds light on such diverse topics as social ritual, gender and household relations, medical practice, and the concerns of civic leaders with public health and poverty. Drunkenness, dueling, and other forms of tavern comportment that may appear "disorderly" to us today turn out to be the inevitable, even desirable result of a society functioning according to its own rules.