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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

A compactness result for the div-curl system with inhomogeneous mixed boundary conditions for bounded Lipschitz domains and some applications

Pauly, Dirk, Skrepek, Nathanael 04 June 2024 (has links)
For a bounded Lipschitz domain with Lipschitz interface we show the following compactness theorem: Any L2-bounded sequence of vector fields with L2-bounded rotations and L2-bounded divergences as well as L2-bounded tangential traces on one part of the boundary and L2-bounded normal traces on the other part of the boundary, contains a strongly L2-convergent subsequence. This generalises recent results for homogeneous mixed boundary conditions in Bauer et al. (SIAM J Math Anal 48(4):2912-2943, 2016) Bauer et al. (in: Maxwell’s Equations: Analysis and Numerics (Radon Series on Computational and Applied Mathematics 24), De Gruyter, pp. 77-104, 2019). As applications we present a related Friedrichs/Poincaré type estimate, a div-curl lemma, and show that the Maxwell operator with mixed tangential and impedance boundary conditions (Robin type boundary conditions) has compact resolvents.
162

Berardinelli-Seip Congenital Lipodystrophy 2/Seipin Is Not Required for Brown Adipogenesis but Regulates Brown Adipose Tissue Development and Function

Zhou, Hongyi, Black, Stephen M., Benson, Tyler W., Weintraub, Neal L., Chen, Weiqin 01 August 2016 (has links)
Brown adipose tissue (BAT) plays a unique role in regulating whole-body energy homeostasis by dissipating energy through thermogenic uncoupling. Berardinelli-Seip congenital lipodystrophy (BSCL) type 2 (BSCL2; also known as seipin) is a lipodystrophy-associated endoplasmic reticulum membrane protein essential for white adipocyte differentiation. Whether BSCL2 directly participates in brown adipocyte differentiation, development, and function, however, is unknown. We show that BSCL2 expression is increased during brown adipocyte differentiation. Its deletion does not impair the classic brown adipogenic program but rather induces premature activation of differentiating brown adipocytes through cyclic AMP (cAMP)/protein kinase A (PKA)-mediated lipolysis and fatty acid and glucose oxidation, as well as uncoupling. cAMP/PKA signaling is physiologically activated during neonatal BAT development in wild-type mice and greatly potentiated in mice with genetic deletion of Bscl2 in brown progenitor cells, leading to reduced BAT mass and lipid content during neonatal brown fat formation. However, prolonged overactivation of cAMP/PKA signaling during BAT development ultimately causes apoptosis of brown adipocytes through inflammation, resulting in BAT atrophy and increased overall adiposity in adult mice. These findings reveal a key cell-autonomous role for BSCL2 in controlling BAT mass/activity and provide novel insights into therapeutic strategies targeting cAMP/PKA signaling to regulate brown adipocyte function, viability, and metabolic homeostasis.
163

VelociRapture

Warzak, Katheryn 18 December 2015 (has links)
N/A
164

n/a

Chen, Ying-kai 18 June 2004 (has links)
n/a
165

Race and BMI modify associations of calcium and vitamin D intake with prostate cancer

Batai, Ken, Murphy, Adam B., Ruden, Maria, Newsome, Jennifer, Shah, Ebony, Dixon, Michael A., Jacobs, Elizabeth T., Hollowell, Courtney M. P., Ahaghotu, Chiledum, Kittles, Rick A. 19 January 2017 (has links)
Background: African Americans have disproportionately higher burden of prostate cancer compared to European Americans. However, the cause of prostate cancer disparities is still unclear. Several roles have been proposed for calcium and vitamin D in prostate cancer pathogenesis and progression, but epidemiologic studies have been conducted mainly in European descent populations. Here we investigated the association of calcium and vitamin D intake with prostate cancer in multiethnic samples. Methods: A total of 1,657 prostate cancer patients who underwent screening and healthy controls (888 African Americans, 620 European Americans, 111 Hispanic Americans, and 38 others) from Chicago, IL and Washington, D.C. were included in this study. Calcium and vitamin D intake were evaluated using food frequency questionnaire. We performed unconditional logistic regression analyses adjusting for relevant variables. Results: In the pooled data set, high calcium intake was significantly associated with higher odds for aggressive prostate cancer (ORQuartile (1 vs. Quartile) (4) = 1.98, 95% C.I.: 1.01-3.91), while high vitamin D intake was associated with lower odds of aggressive prostate cancer (ORQuartile 1 vs. Quartile (4) = 0.38, 95% C.I.: 0.18-0.79). In African Americans, the association between high calcium intake and aggressive prostate cancer was statistically significant (ORQuartile 1 vs. Quartile 4 = 4.28, 95% C.I.: 1.70-10.80). We also observed a strong inverse association between total vitamin D intake and prostate cancer in African Americans (ORQuartile 1 vs. Quartile 4 = 0.06, 95% C.I.: 0.02-0.54). In European Americas, we did not observe any significant associations between either calcium or vitamin D intake and prostate cancer. In analyses stratifying participants based on Body Mass Index (BMI), we observed a strong positive association between calcium and aggressive prostate cancer and a strong inverse association between vitamin D intake and aggressive prostate cancer among men with low BMI (<27.8 kg/m(2)), but not among men with high BMI (>= 27.8 kg/m(2)). Interactions of race and BMI with vitamin D intake were significant (P-Interaction < 0.05). Conclusion: Calcium intake was positively associated with aggressive prostate cancer, while vitamin D intake exhibited an inverse relationship. However, these associations varied by race/ethnicity and BMI. The findings from this study may help develop better prostate cancer prevention and management strategies.
166

Measuring and Predicting Transient Diesel Engine Emissions

Westlund, Anders January 2009 (has links)
<p> </p><p>Due to its impact on human health and the nature surrounding us, diesel engine emissions have been significantly reduced over the last two decades. This reduction has been enforced by the legislating organs around the world that gradually have made the manufacturers transform their engines to today’s complex high-tech products. One of the most challenging areas to meet the legislations is transient operation where the inertia in gas-exchange system makes transition from one load to another problematic.</p><p> </p><p>Modern engines have great potential to minimize the problems associated with transient operation. However, their complexity also imposes a great challenge regarding optimization and systematical testing of transient control strategies in an engine test bed could be both expensive and time consuming.</p><p> </p><p>The objective of this project is to facilitate optimization of transient control strategies. This should be done by identifying appropriate measurement methods for evaluation of transients and by providing models that can be used to optimize strategies off-line.</p><p> </p><p>Measurement methods for evaluation of transients have been tested in several experiments, mainly focusing on emission but also regarding e.g. EGR flow. Applicable instruments for transient emission measurements have been identified and used. However, no method to measure soot emissions cycle resolved has yet been found. Other measurements such as EGR flow and temperatures are believed to have significantly decreased accuracy during transients.</p><p> </p><p>A model for prediction of NOx emissions have been used and complemented with a new approach for soot emission predictions that has been developed in this project. The emission models have been shown to be applicable over a wide range of operating conditions with exception for highly premixed combustion. It has also been shown that models developed for steady state conditions can be used for transients operation.</p>
167

Product orientation of environmental work - barriers & incentives

Zackrisson, Mats January 2009 (has links)
<p><em>Abstract</em></p><p>The research behind this licentiate is spread out over a decade of intensive development of environmental work in industry. A 1998 survey of Swedish companies with newly installed environmental management systems (EMS) concluded that such systems need more product-orientation. Data collected by companies as part of the process of creating their EMS between 1996-2001 offered further evidence that it is environmentally justified to seek improvements in the materials selection, use and disposal phases of products, i.e., to make the environmental improvement work more product-orientated. In a EU-funded project carried out between 2004-2006 it was demonstrated that developing an environmental product declaration could be a cost-effective product-oriented environmental action even for smaller companies.</p><p>This licentiate thesis relates to methods for companies to orientate their environmental work on their products. In particular, it examines experience and provides insights on the possibilities for companies, including small ones, to use life cycle assessment in product development in order to design products with an environmental performance well above legal compliance.</p><p>It is difficult to give general recommendations to companies about their environmental work because each company has its own unique business idea, customers, work culture, stakeholders etc. Nevertheless, the main findings of the licentiate thesis can be summed up in the following recommendations for, say, a small company in Europe without much previous experience of environmental work:</p><p>§  Focus your environmental work on your products because you will accomplish more environmentally and the chance of profiting economically will motivate your personnel;</p><p>§  Consider doing a life cycle assessment, LCA, on a strategically chosen product in order to learn more about your products and how to improve their environmental performance;</p><p>§  Do not expect to find a general market demand for green products; start a dialogue with your best customers in order to create the demand;</p><p>§  Engage an LCA specialist to do the LCA and work together with your personnel to interpret the results and generate improvement ideas;</p><p>§  If your customers demand that you install an environmental management system, ask them if they would not prefer to receive an environmental product declaration on the particular product they are interested in, and a chance to discuss how its environmental performance can be improved.</p>
168

Concept decisions in product development process

Kihlander, Ingrid January 2009 (has links)
<p>Successful concept decisions are crucial for product development organisations. Failure in theconcept decision-making process means costly rework, requiring resources that could havebeen spent on innovative work with new products instead. This licentiate thesis tackles theconcept decision-making process and how to improve it. The research presented here is thefirst part of a research project, with an action research approach, that will develop newsupporting working procedures for concept decision making and thereby contribute to moresuccessful products.Empirical studies were conducted in Swedish industrial practice, particularly focusing oneorganisation, and it was found that concept decisions are not made at a certain point in time.Instead, many decisions and activities, on several organisational levels, were adding up to theconcept decisions in the investigated organisations. The concept decision-making process wasfound to be a web of interconnected activities, with many decisions integrated and embedded in the process. Itwas also found that both formal and informal factors influence the concept decision-makingprocess and main factors were identified as: Project and product request, Supporting structures androutines, Individual competence and driving forces, Teamwork and company culture and Contextualcircumstances. These factors represent different perspectives, meaning on what level theyinfluence concept decision making: individual, team, project, organisation, and context, and in orderto create improvements in the concept decision-making process all levels have to beconsidered. The knowledge of the different perspectives has implications for howimprovements should be designed.Larger product developing companies do often have internally defined formal workingprocedures that prescribe how to develop products within the company. The thesis discusseshow the internal working procedures relate to academic theory and to practice. It wasconcluded that internal formal working procedures has not been discussed in a sufficient wayin earlier engineering design research. Furthermore, means for improving the concept decisionmakingprocess are discussed, and it was concluded, based on interviews with practitioners,that the strongest pragmatic means for improvement were developing mindset and applyingmethods. Mindset addresses the awareness, attitude and approach needed for management (andco-workers) working in early product development phases. Methods mainly addresses the needfor having relevant supporting working procedures in general and templates for evaluationalternative solutions in particular. Finally, recommendations for future design of a template forevaluation alternative solutions are presented.</p>
169

Influence of surface topography and lubricant design in gear contacts

Bergseth, Ellen Unknown Date (has links)
<p>The purpose of this thesis was to study the influence of manufacturing variations on gear performance. The manufacturing variations inherent in different manufacturing methods were studied to include the effect of real surfaces. Real surfaces have surface irregularities at least on some scale, which can significantly influence how loads are transmitted at the gear contact. To some extent, the lubricant design can help to prevent contact that could lead to tooth failures by forming a protective surface boundary layer. An experimental study was used to consider the compositions of these layers with a surface analysis method.</p><p>In Paper <strong>A</strong> a robust design approach was used to find out to what extent the current standard for calculation of surface durability treats manufacturing variations and the choice of lubricant. The results show that the simplest calculation method used is not enough to predict the effect of these on surface durability. Additionally, the standard quality levels are poorly incorporated in the standard calculating procedures for surface durability, and the quality of the gear tooth is restricted to include only a few parameters.</p><p>In Paper <strong>B</strong> a pin-on-disc machine was used to evaluate the tribofilm formation by the additives and the corresponding wear occurring in the boundary lubrication regime in environmentally adapted lubricants. Studies of the additive and base fluid interaction were carried out using glow discharge-optical emission spectroscopy. It was found that the chemically reacted surface boundary layers played an important role in terms of wear. More specifically, the oxide layer thickness had significant influence on wear. The findings also demonstrate the complexity of lubrication design formulations coupled to these layers. For example, it was found that the pre-existing surface boundary layer (before any lubricant had been added) played an important role in allowing the lubricant to react properly with the surfaces.</p><p>The aim of Paper <strong>C</strong> was to contribute to the knowledge of how different surface topographies, tied to manufacturing methods, influence the early life contact conditions in gears. Topographical measurements of differently manufactured tooth flanks were used as data input to a contact analysis program. The variation in surface topography inherent in the manufacturing method was found to have a strong influence on the contact area ratio.</p>
170

Smooth Muscle Modeling : Activation and contraction of contractile units in smooth muscle

Murtada, Sae-Il January 2009 (has links)
No description available.

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