Toeplitz operators on Hardy spaces

In the present thesis we establish Banach space counterparts for several results known for Toeplitz operators on Hardy-Hilbert spaces. We use methods of Didas, Eschmeier and Everard to construct Toeplitz projections for Toeplitz operators acting on a general class of Hardy-type spaces. These Toeplitz projections provide a general framework for Brown-Halmos type characterizations of Toeplitz operators and allow us to prove a Banach space version of a classical spectral inclusion theorem of Hartman and Wintner. Furthermore we show that a multivariable spectral mapping theorem of Eschmeier for Toeplitz tuples on Hardy-Hilbert spaces over strictly pseudoconvex domains with smooth boundary remains true in the corresponding Banach space setting. As an application we derive a spectral mapping theorem for truncated Toeplitz systems which generalizes a one dimensional result proved by Bessonov for the Hardy-Hilbert space on the unit disc

Modelling Catalytic Cracking In A Novel Riser Simulator (volumes I And Ii)

A 45 mL bench-scale internal recycle reactor, named a \u27Riser Simulator\u27 was used to study the kinetics of catalytic cracking. This reaction system is well suited for riser cracking reactions since it can be operated at reaction times as low as 3 seconds and can simulate the reaction regime of a riser. The reactor operates in a batch mode with a gas recirculation in the upward direction through the central catalyst zone to maintain a well fluidized bed.;Experimental runs performed in the unit included the cracking of two commercial feedstocks and three mixtures of pure light oil compounds with two commercial catalysts. The reactor conditions were varied with temperatures of 500, 525 and 550{dollar}\sp\circ{dollar}C; reaction times of 3 to 10 seconds and catalyst to oil ratios of 3 to 7. The products were analyzed using gas chromatography and mass spectrometry.;The kinetic parameters associated with the three lump model were evaluated based on a reactor model which intrinsically includes the effect of molar expansion during cracking. The kinetic values obtained fell in the range of values reported in other works using pilot scale riser units. Three different catalyst decay functions were used and it was found that first order decay was sufficient to describe the data for short contact times.;An eight lump model which takes into account feedstock composition (paraffins, naphthenes and aromatics) was also evaluated. The model predicted gasoline yields to within {dollar}\pm{dollar}2.3 wt% and light gases plus coke yields to within {dollar}\pm{dollar}3.9 wt%.;The information presented in this work should help furnish the existing gap of kinetic data for short contact time riser cracking. The Riser Simulator can be considered a valuable tool for determination of relevant kinetic data and could also be used for purposes of catalyst screening since it achieves a reaction regime which is more realistic for riser cracking than that achieved by the industry standard MAT unit

Integrating the Credit-Bearing Information Literacy Course into the Curriculum: Goals, Benefits and Challenges

This presentation provides a model for the design and implementation of a successful credit-bearing information literacy course that addresses the most common objections against stand-alone library instruction. It emphasizes two key principles, making it relevant to students and university administrators alike: integration into the university general education program, and the contextualization of information-seeking mechanics by introducing students to the economic, political and social context in which information is produced, managed and used. These principles lay the foundation for the development of critical information literacy skills that students can transfer to other courses and beyond. Offering stand-alone instruction while integrating it into the curriculum is an innovative strategy that opens the way for the creation of advanced, discipline-specific and program-embedded library instruction. The presenters will show the course syllabus and a sample online module, and will outline strategies to integrate information literacy into the general education program. They will invite participants to debate the potential benefits and pitfalls of stand-alone, credit-bearing library courses and to assess the effectiveness of the solutions offered in the presentation

Modeling and optimization of solar thermoelectric generators for terrestrial applications

In this paper we introduce a model and an optimization methodology for terrestrial solar thermoelectric generators (STEGs). We describe, discuss, and justify the necessary constraints on the STEG geometry that make the STEG optimization independent of individual dimensions. A simplified model shows that the thermoelectric elements in STEGs can be scaled in size without affecting the overall performance of the device, even when the properties of the thermoelectric material and the solar absorber are temperature-dependent. Consequently, the amount of thermoelectric material can be minimized to be only a negligible fraction of the total system cost. As an example, a Bi[subscript 2]Te[subscript 3]-based STEG is optimized for rooftop power generation. Peak efficiency is predicted to be 5% at the standard spectrum AM1.5G, with the thermoelectric material cost below 0.05 $/W[subscript p]. Integrating STEGs into solar hot water systems for cogeneration adds electricity at minimal extra cost. In such cogeneration systems the electric current can be adjusted throughout the day to favor either electricity or hot water production

Optical cavity for improved performance of solar receivers in solar-thermal systems

A principal loss mechanism for solar receivers in solar-thermal systems is radiation from the absorbing surface. This loss can be reduced by using the concept of directional selectivity in which radiation is suppressed at angles larger than the incident angle of the sunlight striking the absorber. Directional selectivity can achieve efficiencies similar to high solar concentration, without the drawbacks associated with large heat fluxes. A specularly reflective hemispherical cavity placed over the absorber can reflect emitted radiation back to the absorber, effectively suppressing emission losses. An aperture in the cavity will still allow sunlight to reach the absorber surface when used with point focus concentrating systems. In this paper the reduction in radiative losses through the use of a hemispherical cavity is predicted using ray tracing simulations, and the effects of cavity size and absorber alignment are investigated. Simulated results are validated with proof of concept experiments that show reductions in radiative losses of more than 75% from a near blackbody absorber surface. The demonstrated cavity system is shown to be capable of achieving receiver efficiencies comparable to idealized spectrally selective absorbers across a wide range of operating temperatures.United States. Dept. of Energy (“Concentrated Solar Thermoelectric Power”, a DOE SunShot CSP Grant, under award number DE-EE0005806

Quality Control in the Production Process of SMC Lightweight Material

The use of sheet molding compounds (SMC) in diverse applications requires different specific material properties for each type of finished parts. These material properties have to be assured by a reliable quality control, which does not only have to be performed for the prefabricated SMC itself but also during the production process of the semi-finished material. This is of high importance because quality fluctuations and defects can already occur during the production of the semi-finished SMC. This results in high scrap rates as well as machine failure and can additionally cause further problems in the following process steps. Hence, an inline quality control can help to establish objective quality criteria for semi-finished SMC and can enable controlled and stable production processes. Therefore, this paper deals with quality assurance in the production process of semi-finished sheet molding compounds. Air entrapping and fiber distribution are identified as two parameters that influence the quality of the semi-finished product significantly. In addition, the early detection of a pending carrier foil failure can help to establish a stable process. The focus of this paper lies on how various, individually adapted metrology systems can be used for the detection of the respective characteristics and integrated into the production process of the semi-finished SMC. In particular, optical systems, such as area scan cameras and laser stripe sensors as well as thermographic sensors are discussed and possibilities for application-related sensor data evaluation are shown. This helps to reduce the scrap rates of parts and to establish a further automated production process

Prevalence of metabolic syndrome in patients with schizophrenia, and metabolic changes after 3 months of treatment with antipsychotics - results from a German observational study

<p>Abstract</p> <p>Background</p> <p>This observational study explored the prevalence of metabolic syndrome (MetS) in adult in- and outpatients with untreated or treated schizophrenia at baseline, and month-3 after initiation or switch of antipsychotic treatment.</p> <p>Methods</p> <p>MetS-prevalence (AHA/NHLB-definition) was assessed and Clopper-Pearson 95% confidence intervals (CIs) were calculated. Factors associated with MetS were explored through univariate and multivariate logistic regressions (both visits).</p> <p>Results</p> <p>MetS-prevalence was 44.3% (CI 39.8;48.9) at baseline and 49.6% (CI 45.0;54.2) at month-3. Previously unmedicated patients showed the lowest baseline MetS-prevalence (24.7%, CI 18.3;32.1). MetS-prevalence was not significantly different, regardless if patients previously received typical or atypical antipsychotics. Increased MetS-risk was associated with somatic comorbidity and non-smoking at both visits, and with non-psychiatric co-medication, male sex, and increased C-reactive protein at month-3.</p> <p>Conclusions</p> <p>At baseline, MetS was most prevalent in patients with previous antipsychotic medication. Limited metabolic changes were observed 3 months after switch/initiation of antipsychotic therapy.</p> <p>Trial Registration Number</p> <p>ClinicalTrials.gov Identifier: n.a.</p

Em obesos, a disfunção endotelial correlaciona melhor com a relação cintura-quadril do que com a medida da cintura ou índice de massa corpórea

PURPOSE: Obesity is associated with cardiovascular disease, affecting large arteries and the microcirculation. Waist circumference and body mass index are routinely employed as measures for assessing obesity-related health risk, whereas waist-to-hip ratio is not. We aimed to investigate the association between brachial vascular reactivity and body mass index, waist circumference, and waist-to-hip ratio. METHODS: Eighty-five volunteers (21 men/66 women), aged between 20 and 55 years, underwent determination of waist circumference, body mass index, waist-to-hip ratio, and endothelial function by venous occlusion plethysmography. Forearm blood flow was measured in response to intrabrachial artery infusions of 3 different concentrations of endothelium-dependent (acetylcholine 7.5, 15, and 30 mg/min) and endothelium-independent (sodium nitroprusside 2, 4, and 8 mg/min) vasodilators. RESULTS: There was an inverse correlation of body mass index and waist circumference with forearm blood flow increments after acetylcholine and sodium nitroprusside infusions, while waist-to-hip ratio showed an inverse correlation with forearm blood flow increments only after acetylcholine. When subjects older than 40 years (n = 25) were excluded from the analysis, the inverse correlation of body mass index with forearm blood flow increments after acetylcholine infusion no longer existed, while waist circumference and waist-to-hip ratio showed the same results observed before. CONCLUSION: The waist-to-hip ratio is probably a better estimator of endothelial dysfunction and possibly of cardiovascular risk than body mass index. These findings underscore the importance of routinely collecting hip circumference as an obesity index and risk estimator.OBJETIVO: A obesidade é associada a doenças cardiovasculares e compromete tanto a macro como a microcirculação. As medidas da cintura e do índice de massa corpórea são rotineiramente empregadas para avaliação do risco cardiovascular em obesos, enquanto a relação cintura-quadril é pouco utilizada. O objetivo do trabalho foi determinar que medida antroprométrica, entre as rotineiramente usadas, avalia melhor o risco cardiovascular em obesos. MATERIAL E MÉTODO: Oitenta e quatro voluntários (21 homens/ 66 mulheres), idade entre 20 e 55 anos foram avaliados quanto ao diâmetro da cintura, ao índice de massa corpórea, à relação cintura-quadril e à função endotelial pela técnica de pletismografia com oclusão venosa para medida do fluxo sanguíneo braquial, em resposta a injeção intrabraquial de três doses de acetilcolina (7,5; 15 e 30 mg/min) ou de nitroprussiato de sódio (2; 4 e 8 mg/min), para avaliação da vasodilatação endotélio-dependente e -independente. RESULTADO: Houve correlação inversa entre o índice de massa corpórea, diâmetro da cintura e aumento do fluxo sanguíneo após injeção de acetilcolina e nitroprussiato de sódio, enquanto que a relação cintura-quadril mostrou uma correlação negativa apenas com o aumento no fluxo de sangue no antebraço, após as infusões de acetilcolina. Quando os indivíduos com mais de 40 anos foram retirados da análise, não observamos mais a relação inversa entre índice de massa corpórea e aumento do fluxo sanguíneo após injeção de acetilcolina, enquanto que a cintura e a relação cintura-quadril mantiveram os resultados observados anteriormente. CONCLUSÃO: A relação cintura-quadril é provavelmente um melhor índice para estimar a disfunção endotelial, e consequentemente o risco cardiovascular, que o índice de massa corpórea e esses achados reforçam a importância da aferição da circunferência do quadril como um índice de obesidade e para estimativa do risco cardiovascular