543 resultados para Nehari Manifold


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Aortic aneurysms and aortic dissection represent a significant health risk due to the demographic developments and current life styles. The mortality of ruptured aortic aneurysms is up to 80 % and the prevalence of aneurysms varies depending on the localization (thoracic or abdominal). Most commonly affected is the infrarenal abdominal aorta; however, there is evidence that the prevalence is diminishing but in contrast the incidence of thoracic aortic aneurysms is increasing. Aortic dissection is often fatal and is the most common acute aortic disease but the incidence is presumed to be underestimated. The pathogenesis of aortic aneurysms is manifold and is based on an interplay between degenerative, proteolytic and inflammatory processes. An aortic dissection arises from a tear in the intima which results in a separation of the aortic wall layers with infiltration of bleeding and the danger of aortic rupture. Various genetic disorders of connective tissue promote degeneration of the aortic media, most notably Marfan syndrome. Risk factors for aortic aneurysms and aortic dissection are nicotine abuse, arterial hypertension, age and male gender. Aortic aneurysms initially have an uneventful course and as a consequence are mostly discovered incidentally. The clinical course and symptoms of aortic dissection are very much dependent on the section of the aorta affected and the manifestations are manifold. Acute aortic dissection is in 80 % of cases first manifested as sudden extremely severe pain. The diagnostics and subsequent course control can be achieved by a variety of imaging procedures but the modality of choice is computed tomography.

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Dimensional modeling, GT-Power in particular, has been used for two related purposes-to quantify and understand the inaccuracies of transient engine flow estimates that cause transient smoke spikes and to improve empirical models of opacity or particulate matter used for engine calibration. It has been proposed by dimensional modeling that exhaust gas recirculation flow rate was significantly underestimated and volumetric efficiency was overestimated by the electronic control module during the turbocharger lag period of an electronically controlled heavy duty diesel engine. Factoring in cylinder-to-cylinder variation, it has been shown that the electronic control module estimated fuel-Oxygen ratio was lower than actual by up to 35% during the turbocharger lag period but within 2% of actual elsewhere, thus hindering fuel-Oxygen ratio limit-based smoke control. The dimensional modeling of transient flow was enabled with a new method of simulating transient data in which the manifold pressures and exhaust gas recirculation system flow resistance, characterized as a function of exhaust gas recirculation valve position at each measured transient data point, were replicated by quasi-static or transient simulation to predict engine flows. Dimensional modeling was also used to transform the engine operating parameter model input space to a more fundamental lower dimensional space so that a nearest neighbor approach could be used to predict smoke emissions. This new approach, intended for engine calibration and control modeling, was termed the "nonparametric reduced dimensionality" approach. It was used to predict federal test procedure cumulative particulate matter within 7% of measured value, based solely on steady-state training data. Very little correlation between the model inputs in the transformed space was observed as compared to the engine operating parameter space. This more uniform, smaller, shrunken model input space might explain how the nonparametric reduced dimensionality approach model could successfully predict federal test procedure emissions when roughly 40% of all transient points were classified as outliers as per the steady-state training data.

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Healthy individuals live in peaceful co-existence with an immense load of intestinal bacteria. This symbiosis is advantageous for both the host and the bacteria. For the host it provides access to otherwise undigestible nutrients and colonization resistance against pathogens. In return the bacteria receive an excellent nutrient habitat. The mucosal immune adaptations to the presence of this commensal intestinal microflora are manifold. Although bacterial colonization has clear systemic consequences, such as maturation of the immune system, it is striking that the mutualistic adaptive (T and B cells) and innate immune responses are precisely compartmentalized to the mucosal immune system. Here we summarize the mechanisms of mucosal immune compartmentalization and its importance for a healthy host-microbiota mutualism.

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Endocrine resistance in breast cancer remains a major clinical problem and is caused by crosstalk mechanisms of growth factor receptor cascades, such as the erbB and PI3K/AKT pathways. The possibilities a single breast cancer cell has to achieve resistance are manifold. We developed a model of 4-hydroxy-tamoxifen (OHT)‑resistant human breast cancer cell lines and compared their different expression patterns, activation of growth factor receptor pathways and compared cells by genomic hybridization (CGH). We also tested a panel of selective inhibitors of the erbB and AKT/mTOR pathways to overcome OHT resistance. OHT‑resistant MCF-7-TR and T47D-TR cells showed increased expression of HER2 and activation of AKT. T47D-TR cells showed EGFR expression and activated MAPK (ERK-1/2), whereas in resistant MCF-7-TR cells activated AKT was due to loss of CTMP expression. CGH analyses revealed remarkable aberrations in resistant sublines, which were predominantly depletions. Gefitinib inhibited erbB signalling and restored OHT sensitivity in T47D-TR cells. The AKT inhibitor perifosine restored OHT sensitivity in MCF-7-TR cells. All cell lines showed expression of receptors for gonadotropin-releasing hormone (GnRH) I and II, and analogs of GnRH-I/II restored OHT sensitivity in both resistant cell lines by inhibition of erbB and AKT signalling. In conclusion, mechanisms to escape endocrine treatment in breast cancer share similarities in expression profiling but are based on substantially different genetic aberrations. Evaluation of activated mediators of growth factor receptor cascades is helpful to predict response to specific inhibitors. Expression of GnRH-I/II receptors provides multi-targeting treatment strategies.

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Experimental work and analysis was done to investigate engine startup robustness and emissions of a flex-fuel spark ignition (SI) direct injection (DI) engine. The vaporization and other characteristics of ethanol fuel blends present a challenge at engine startup. Strategies to reduce the enrichment requirements for the first engine startup cycle and emissions for the second and third fired cycle at 25°C ± 1°C engine and intake air temperature were investigated. Research work was conducted on a single cylinder SIDI engine with gasoline and E85 fuels, to study the effect on first fired cycle of engine startup. Piston configurations that included a compression ratio change (11 vs 15.5) and piston geometry change (flattop vs bowl) were tested, along with changes in intake cam timing (95,110,125) and fuel pressure (0.4 MPa vs 3 MPa). The goal was to replicate the engine speed, manifold pressure, fuel pressure and testing temperature from an engine startup trace for investigating the first fired cycle for the engine. Results showed bowl piston was able to enable lower equivalence ratio engine starts with gasoline fuel, while also showing lower IMEP at the same equivalence ratio compared to flat top piston. With E85, bowl piston showed reduced IMEP as compression ratio increased at the same equivalence ratio. A preference for constant intake valve timing across fuels seemed to indicate that flattop piston might be a good flex-fuel piston. Significant improvements were seen with higher CR bowl piston with high fuel pressure starts, but showed no improvement with low fuel pressures. Simulation work was conducted to analyze initial three cycles of engine startup in GT-POWER for the same set of hardware used in the experimentations. A steady state validated model was modified for startup conditions. The results of which allowed an understanding of the relative residual levels and IMEP at the test points in the cam phasing space. This allowed selecting additional test points that enable use of higher residual levels, eliminating those with smaller trapped mass incapable of producing required IMEP for proper engine turnover. The second phase of experimental testing results for 2nd and 3rd startup cycle revealed both E10 and E85 prefer the same SOI of 240°bTDC at second and third startup cycle for the flat top piston and high injection pressures. E85 fuel optimal cam timing for startup showed that it tolerates more residuals compared to E10 fuel. Higher internal residuals drives down the Ø requirement for both fuels up to their combustion stability limit, this is thought to be direct benefit to vaporization due to increased cycle start temperature. Benefits are shown for an advance IMOP and retarded EMOP strategy at engine startup. Overall the amount of residuals preferred by an engine for E10 fuel at startup is thought to be constant across engine speed, thus could enable easier selection of optimized cam positions across the startup speeds.

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In power electronic basedmicrogrids, the computational requirements needed to implement an optimized online control strategy can be prohibitive. The work presented in this dissertation proposes a generalized method of derivation of geometric manifolds in a dc microgrid that is based on the a-priori computation of the optimal reactions and trajectories for classes of events in a dc microgrid. The proposed states are the stored energies in all the energy storage elements of the dc microgrid and power flowing into them. It is anticipated that calculating a large enough set of dissimilar transient scenarios will also span many scenarios not specifically used to develop the surface. These geometric manifolds will then be used as reference surfaces in any type of controller, such as a sliding mode hysteretic controller. The presence of switched power converters in microgrids involve different control actions for different system events. The control of the switch states of the converters is essential for steady state and transient operations. A digital memory look-up based controller that uses a hysteretic sliding mode control strategy is an effective technique to generate the proper switch states for the converters. An example dcmicrogrid with three dc-dc boost converters and resistive loads is considered for this work. The geometric manifolds are successfully generated for transient events, such as step changes in the loads and the sources. The surfaces corresponding to a specific case of step change in the loads are then used as reference surfaces in an EEPROM for experimentally validating the control strategy. The required switch states corresponding to this specific transient scenario are programmed in the EEPROM as a memory table. This controls the switching of the dc-dc boost converters and drives the system states to the reference manifold. In this work, it is shown that this strategy effectively controls the system for a transient condition such as step changes in the loads for the example case.

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The world in which social work operates today is a very different world from that in which most of us took their social work training, and the changes we are facing are profound. This paper argues that these changes are not merely a regime change in social policy but that they are essentially about a re-ordering of social relationships and attempt to model them on neo-liberal ideas. In view of these pressures it is understandable that social workers often try to ignore those changes and withdraw into a private world of therapeutic relationships in which the methods they trained in are made to be still valid, or they simply go along with new service delivery designs without asking too many questions. Both reactions fail to question what the "social" can still mean in the light of these changes and how social workers can fulfil their mandate to be responsible for the social dimension of public life. Nothing less than a head-on challenge of the basic presuppositions of neo-liberalism (Willke 2003) and their manifold applications to social service delivery systems will thereby suffice.

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Herman Stein, President of the International Association of Schools of Social Work from 1968 - 1976, has for more than sixty years excelled as an educator, scholar, internationalist, university administrator, and leader in a variety of professional associations. From almost the beginning of his career, the world has been the stage on which he has played those many roles, all of them with an abundance of talent. In fact, while he was in the graduate program of what is now the Columbia University School of Social Work, he had to decide whether to become a social worker or an actor. As an undergraduate he became involved in student theatrical productions, where he teamed up with the famous comedian, Danny Kaye, who became a life-long companion and friend. At the end of Steins first year in the social work program, he was invited to join an off-Broadway variety show that helped to launch Kaye on his meteoric rise on both stage and screen. "If I´d joined," Stein has said, "the theater probably was going to be where I would make my career as a character actor." Fortunately for social work and social work education, he chose instead to continue his studies at the School of Social Work, from which he received his master's degree in 1941 and the doctoral degree in 1958. While the world has been his stage, education has been at the heart of his manifold activities. Following a period of direct service practice as a caseworker in a well-known private agency in New York City, he was recruited by the Columbia School of Social Work in 1945 as a faculty member. With an interruption for a significant overseas assignment from 1947 to 1950, he continued at Columbia for another fourteen years, rising through all professorial ranks to Professor and Director of the School's Research Center.

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The possibility of violence is ubiquitous in human social relations, its forms are manifold and its causes complex. Different types of violence are interrelated but in complex ways, and they are studied within a wide range of disciplines, so that a general theory, while possible, is difficult to achieve. This paper acknowledges that violence can negate power and that all forms of social power can entail violence, proceeds on the assumption that the organisation of violence is a particular source of social power. It therefore explores the general relationships of violence to power, the significance of war as the archetype of organised violence, the relationships of other types (revolution, terrorism, genocide) to war, and the significance of civilian-combatant stratification for the understanding of all types of organised violence. It then discusses the problems of applying conceptual types in analysis, and the necessity of a historical framework for theorising violence. The paper concludes by offering such a framework in the transition from industrialised total war to global surveillance war.

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Nicht nur die vielfältigen funktionsbezogenen Anforderungen von Produkten und Bauteilen, sondern vor allem die heutigen Marktbedürfnisse stellen große Herausforderungen für aktuelle Fertigungstechnologien dar. Hierbei bildet die kontinuierlich steigende Variantenvielfalt bei gleichzeitiger Senkung der Stückzahlen je Variante die differenzierten Kundenwünsche ab. Diese Entwicklungen begünstigen die Perspektiven des Laserstrahlschmelzens im Allgemeinen sowie seiner speziellen Anwendungsgebiete Rapid Prototyping, Rapid Tooling und Rapid Manufac-turing. In den Branchen der Medizintechnik und der Gummi- und Kunststoffverarbeitung ist bereits seit einiger Zeit eine dynamische Entwicklung erkennbar. Besonders in der Medizintechnik wird der immer breitere Einsatz des Laserstrahlschmelzens durch die hohe Innovationsfähigkeit des Verfahrens und ein verbesserstes Qualitäts-management vorangetrieben. Aufgrund der zunehmenden Forderungen nach individualisierten und individuellen Produkten werden bereits heute patientenangepasste Implantate mit dem Laserstrahlschmelzverfahren gefertigt. Erwarten die Marktteilnehmer eine weiterhin steigende Nachfrage nach solchen Produkten? Wie muss das Verfah-ren verbessert werden, um seine Prozessstabilität zu erhöhen? Wo liegen die zukünftigen Herausforderungen in der Strahlschmelztechnologie? Um diese und weitere Fragen zu klären hat das Fraunhofer Institut für Produkti-onsanlagen und Konstruktionstechnik (IPK) eine Markt- und Trendanalyse für das Laserstrahlschmelzen durchge-führt.

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Science is responding in manifold ways to current climate change. What are the perquisites for response, and how can we structure the response? By studying the historical climatic event “Year without a Summer” of 1816 and by relating to Fleck’s theory of genesis and development of a scientific fact, we posit that responding refers to making interlinkages between different notions of climatic change.

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Aerial photography and satellite imagery reveal manifold geomorphological evidence of a dynamic evolution of past and present rivers in the Bolivian Amazon. Comparison of oxbow lake and meander scar dimensions along an inactive meander belt of the Río Mamoré (Llanos de Moxos, north-eastern Bolivia) and its modern counterpart suggests significant regional paleohydrological variability. We used these features as geomorphological and sedimentary archives to enhance our understanding of longer-term variations of the fluvial system. Late Pleistocene to Holocene hydrological changes of the Río Mamoré are inferred from: (i) the analysis of satellite imagery, (ii) discharge estimates from meander morphology, (iii) stratigraphic, and (iv) chronological information based on luminescence and radiocarbon dating. The combined data from three oxbows indicate that the now abandoned meander belt – the paleo-Mamoré – continued to be active at least until ∼5 ka, and likely even postdating 3 ka. An up to threefold increase in discharge is estimated for the modern Río Mamoré versus the paleo-Mamoré. The altered runoff regime may have triggered an avulsive shift towards the currently active Río Mamoré. The preceding increase in discharge in turn, was possibly related to a shift in climatic conditions, which changed markedly between the mid- and late Holocene in tropical South America. In addition, it may have been the indirect result of capturing the avulsive Río Grande system to the east of the Río Mamoré. Alternative explanations for the differences in dimensions of the paleo versus the modern Río Mamoré, i.e. contemporaneous activity of both rivers or alteration of site factors such as the channel/floodplain relationship, are considered to be unlikely.

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PRINCIPALS Over the last two decades, the total annual number of applications for asylum in the countries of the European Union has increased from 15,000 to more than 300,000 people. The aim of this study was to give a first overview on multimorbidity of adult asylum seekers. METHODS Our retrospective Swiss single center data analysis examined multimorbidity of adult asylums seekers admitted to our ED between 1 January 2000 and 31 December 2012. RESULTS A total of 3170 patients were eligible for the study; they were predominantly male (2392 male, 75.5% versus 778 female, 24.5). The median age of the patients was 28 years (range 28-82). The most common region of origin was Africa (1544, 48.7%), followed by the Middle East (736, 23.6%). 2144 (67.6%) of all patients were not multimorbid. A total of 1183 (37.7%) of our patients were multimorbid. The mean Charlson comorbidity index was 0.25 (SD 1.1, range 0-12). 634 (20%) of all patients sufferem from psychiatric diseases, followed by chronic medical conditions (12.6%, 399) and infectious diseases (4.7%, 150). Overall, 11% (349) of our patients presented as a direct consequence of prior violence. Patients from Sri Lanka/India most often suffered from addictions problems (50/240, 20.8%, p<0.0001). Infectious diseases were most frequent in patients from Africa (6.6%), followed by the Balkans and Eastern Europe/Russia (each 3.8%). CONCLUSION The health care problems of asylum seekers are manifold. More than 60% of the study population assessed in our study did not suffer from more than one disease. Nevertheless a significant percentage of asylum seekers is multimorbid and exhibits underlying psychiatric, infectious or chronic medical conditions despite their young age.

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A carpet is a metric space homeomorphic to the Sierpiński carpet. We characterize, within a certain class of examples, non-self-similar carpets supporting curve families of nontrivial modulus and supporting Poincaré inequalities. Our results yield new examples of compact doubling metric measure spaces supporting Poincaré inequalities: these examples have no manifold points, yet embed isometrically as subsets of Euclidean space.