• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1846
  • 1022
  • 325
  • 218
  • 178
  • 175
  • 55
  • 54
  • 43
  • 42
  • 39
  • 37
  • 37
  • 30
  • 18
  • Tagged with
  • 4875
  • 767
  • 442
  • 392
  • 378
  • 333
  • 302
  • 246
  • 237
  • 218
  • 217
  • 206
  • 205
  • 202
  • 200
  • 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.
361

Inhibition of phosphodiesterase type 5 and exercise in arterial hypertension

Attinà, Teresa M. January 2010 (has links)
Hypertensive patients exhibit impaired exercise capacity, a strong independent risk factor for cardiovascular disease, and the mechanisms responsible for this are not fully determined. Potential candidates may include endothelial vasomotor dysfunction and arterial stiffness, both of which are associated with hypertension. Impairment of the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway plays a major role in the development of these abnormalities, suggesting that enhancement of NO-cGMP signalling through phosphodiesterase type 5 (PDE5) inhibition may offer therapeutic potential in arterial hypertension. This thesis investigated the effects of the PDE5 inhibitor sildenafil citrate on exercise-induced vasodilatation, maximal exercise capacity and arterial stiffness in hypertensive patients, using different studies involving local limb and whole body exercise. Preliminary dose-ranging studies were initially performed to investigate the intraarterial (brachial) effects of sildenafil on forearm blood flow (FBF), and to select an appropriate, cGMP-independent, vasodilator to use as a control. On the basis on these studies, it was established that sildenafil, infused at 50μg/min, and verapamil, infused at 5μg/min, had similar vasodilator effect on FBF. Ten untreated hypertensive patients and ten matched normotensive subjects were then studied in a three-way, randomised, single-blind and placebo-controlled FBF study. The aim was to investigate the effects of sildenafil on handgrip exercise-induced vasodilatation, and to compare this response with verapamil and saline (placebo). Preinfusion exercise-induced vasodilatation was significantly reduced in hypertensive compared with normotensive subjects (P<0.001). However, after the infusions, while verapamil did not affect the vasodilator response to exercise in either group, sildenafil substantially enhanced this response in hypertensive patients, but not in normotensive subjects (P<0.05). These results suggested that sildenafil, through an increase in cGMP levels in the vasculature, substantially and selectively improves the vasodilator response to handgrip exercise in hypertensive patients.
362

Community capacity building, community development and health : a case study of 'health issues in the community'

Phillips, Richard January 2007 (has links)
This research project aimed to further knowledge regarding the relationship between community capacity building (CCB), community development and health within the context of the Health Issues in the Community (HIIC) programme. CCB refers to the development of capabilities to identify and address community issues and was conceptualised using four dimensions: participation, resource mobilisation, links with others and role of outside agents. HIIC is a learning resource supported by NHS Health Scotland, the national health promotion agency. The main objective of HIIC is to help students explore the processes involved in tackling health-related concerns in the community. The main concepts in this study were explored by referring to a range of academic literatures and five research questions were formulated. ‘How did HIIC tutors and students understand the concept of community and was this understanding influenced by completing HIIC?’, ‘How did stakeholders and tutors understand the notion of CCB?’, ‘Was CCB evident in the experiences of the students after their involvement with the course?’, ‘Did participating in the HIIC course contribute towards furthering students’ understanding about health?’ and ‘Did participating in HIIC have any other impact on participants?’ Face-to-face, semi-structured interviews were conducted across Scotland with three participant groups: stakeholders, tutors and students. This involved a total of thirtyfive interviews with students and tutors from eleven different courses. Interviews were transcribed and analysed using thematic analysis. Four key themes emerged: community, CCB, health, and impact of learning. Tutors and students suggested that people could be members of multiple communities. Community was understood as a geographical location, a common interest and as a sense of belonging. Tutors also considered the community as a site of professional practice. Some participants had an expectation that community members should act collectively to help one another. Completing HIIC appeared to influence students’ understanding about their own circumstances, issues within their community and how it functions, rather than informing how they defined the concept of community. CCB was seen by tutors as a process that develops competencies to address community issues. Stakeholders and tutors differed in their views about whether CCB was an individual level or a collective process. Participants likened CCB to community development, but stakeholders questioned if it shared the same value base or if it was an outcome of community development. Tutors expressed a range of opinions about their understanding of CCB. It was viewed as a potentially helpful idea in terms of understanding the work of community / health-based practitioners. However, others were unable to give a definition of CCB and some tutors considered CCB a concept with little meaning or an indicator to fulfil in the context of a funding application. The manifestation of individual aspects of CCB were identified in the accounts of some participants, but the data did not support the contention that HIIC promoted CCB, within the timescale of this study, although, it could be argued that latent CCB was developed. The data did indicate that participants’ understanding about the concept of health was reaffirmed, broadened or changed and that participating in HIIC could increase an individual’s awareness of social and health issues, develop interpersonal skills and widen social networks. This study indicated that by exploring the concepts of CCB, community and health, a contribution was made towards understanding the processes by which participating in a HIIC course influenced students to address health-related concerns.
363

Investigation of micro- and macro-phenomena in densely packed granular media using the discrete element method

Zhou, Chong January 2011 (has links)
Granular materials are in abundance in nature and are estimated to constitute over 75% of all raw materials passing through the industry. Granular or particulate solids are thus of considerable interest to many industrial sectors and research communities, where many unsolved challenges still remain. This thesis investigates the micro- and macro-phenomena in densely packed particulate systems by means of the Discrete Element Method (DEM), which is a numerical tool for analysing the internal complexities of granular material as the mechanical interactions are considered at the grain scale. It presents an alternative approach to phenomenological continuum approaches when studying localisation problems and finite deformation problems in granular materials. In order to develop a comprehensive theoretical understanding of particulate matter and to form a sound base to improve industrial processes, it is desirable to study the mechanical behaviour of granular solids subject to a variety of loading conditions. In this thesis, three loading actions were explored in detail, which are biaxial compression, rigid object penetration and progressive formation of granular piles. The roles of particle shape and contact friction in each of these loading scenarios were investigated. The resulting packing structures were compared and studied to provide a micromechanical insight into the development of contact force network which governs the collective response. The interparticle contact forces and displacements were then used to evaluate the equivalent continuum stress and strain components thus providing the link between micro- and macroscopic descriptions. The information collected from the evolution of strong contact network illustrates the underlying mechanism of force transmission and propagation. DEM simulations presented in this thesis demonstrate strong capability in predicting the bulk behaviour as well as capturing local phenomenon occurring in the system. The research first simulates a testing environment of biaxial compression in DEM, in which the phenomenon of strain localisation was investigated, with special attention given to the interpretation of underlying failure mechanism. Several key micromechanical quantities of interest were extracted to understand the bifurcation instability, such as force chains, contact orientation, particle rotation and void ratio. In the simulation of progressive formation of granular piles, a counterintuitive pressure profile with a significant pressure dip under the apex was predicted for three models under certain conditions. Both particle shape and preparation history were shown to be important in the resulting pressure distribution. During the rigid body penetration into a granular sample, the contact forces were used to evaluate the equivalent continuum stress components. Significant stress concentration was developed around the punch base which further led to successive collapse and reformation of force chains. Taking the advantage of micromechanical analysis at particle scale, two distinct bearing failure mechanisms were identified as the penetration proceeded. To further quantify the nature of strain mobilisation leading to failure, Particle Image Velocimetry (PIV) was employed to measure the deformation over small strain interval in association with shear band propagation in the biaxial test and deformation pattern in the footing test. The captured images from DEM simulation and laboratory experiments were evaluated through PIV correlation. This optical measuring technique is able to yield a significant improvement in the accuracy and spatial resolution of the displacement field over highly strained and localised regions. Finally, a series of equivalent DEM simulations were also conducted and compared with the physical footing experiments, with the objective of evaluating the capability of DEM in producing satisfactory predictions.
364

The study of muscle metabolism in young people using 31P-magnetic resonance spectroscopy

Barker, Alan Robert January 2008 (has links)
The purpose of this thesis is to extend understanding of the muscle metabolic responses of children and adolescents during exercise using the non-invasive technique of 31P-magnetic resonance spectroscopy (31P-MRS). The first experimental paper examined the reliability of measuring parameters of muscle metabolism in 11-12 year old children over three exhaustive incremental tests using a single-legged quadriceps ergometer. Exercise performance (peak power: ~ 10% coefficient of variation [CV]) and metabolic variables (muscle phosphate and pH intracellular thresholds [IT]: ~ 10% CV, and pH: ~ 1% CV at exhaustion) demonstrated good reliability, whereas the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) at exhaustion had poor reproducibility (~ 50% CV). The second paper examined the influence of age and sex on the muscle metabolic responses during incremental exercise in 9-12 year old children and young adults. The Pi/PCr and pH responses before and at the ITs were independent of age and sex, although during exercise above the ITs, the anaerobic energy contribution (increase in Pi/PCr, fall in pH) was higher in adults than children and in females compared with males, indicating an intensity dependence on age- and sex-related differences in muscle energetics. The third paper examined the relationship between the dynamics of muscle PCr, a putative controller of muscle respiration, and pulmonary oxygen uptake (pVO2) in 9-10 year old children during moderate intensity quadriceps and cycling exercise respectively. No differences were found between the PCr and phase II VO2 time constants at the onset (PCr 23 s [SD 5] vs. pVO2 23 s [SD 4]; P=1.000) or offset (PCr 28 s [SD 5] vs. pVO2 29 s [SD 5]; P=1.000) of exercise, suggesting an age-related slowing of the phosphate linked controller(s) of mitochondrial oxidative phosphorylation may underlie the faster pVO2 kinetics found in children compared to adults. The final experimental chapter tested this hypothesis, but no age or sex related differences were found in the PCr kinetic time constant at the onset (boys: 21 s [SD 4]; girls: 24 s [SD 5]; men: 26 s [SD 9]; women: 24 s [SD 7], P>0.200) or offset (boys: 26 s [SD 5]; girls: 29 s [SD 7]; men: 23 s [SD 9]; women: 29 s [SD 7], P>0.070) of exercise. In conclusion, this thesis has demonstrated that muscle metabolic parameters determined by 31P-MRS are suitable for the study of developmental exercise metabolism. During exercise below the metabolic ITs, the phosphate-linked regulation of muscle respiration is comparable between children and adults, although during exercise above the ITs children are characterised by a lower ‘anaerobic’ energy turnover than adults, indicating an age-related modulation of metabolic control during high intensity exercise.
365

Impact of actual interference on capacity and call admission control in a CDMA network.

Parvez, Asad 05 1900 (has links)
An overwhelming number of models in the literature use average inter-cell interference for the calculation of capacity of a Code Division Multiple Access (CDMA) network. The advantage gained in terms of simplicity by using such models comes at the cost of rendering the exact location of a user within a cell irrelevant. We calculate the actual per-user interference and analyze the effect of user-distribution within a cell on the capacity of a CDMA network. We show that even though the capacity obtained using average interference is a good approximation to the capacity calculated using actual interference for a uniform user distribution, the deviation can be tremendously large for non-uniform user distributions. Call admission control (CAC) algorithms are responsible for efficient management of a network's resources while guaranteeing the quality of service and grade of service, i.e., accepting the maximum number of calls without affecting the quality of service of calls already present in the network. We design and implement global and local CAC algorithms, and through simulations compare their network throughput and blocking probabilities for varying mobility scenarios. We show that even though our global CAC is better at resource management, the lack of substantial gain in network throughput and exponential increase in complexity makes our optimized local CAC algorithm a much better choice for a given traffic distribution profile.
366

Building Design Capability in the Public Sector : Expanding the Horizons of Development

Malmberg, Lisa January 2017 (has links)
Public sector organizations are in need of new approaches to development and innovation. There is a need to develop a capability to better understand priorities, needs and wishes of public sector service users and become more proactive, in order to meet the demands on keeping costs down and quality high. Design is increasingly put forward as a potential answer to this need and there are many initiatives taken across the world to encourage the use of a design approach to development and innovation within public sector. In relation to this trend there is a need to improve the understanding of how public sector organizations develop ability to exploit design; how they develop design capability. This is the focus of this thesis, which through an exploratory study has observed the two initiatives aiming to introduce design and develop design capability within healthcare and social service organizations. One main contribution of this work is an understanding of the design capability concept based on a structured review of the use of the design capability concept in the literature. The concept has previously been used in relation to different aspects of designs in organizations. Another important contribution is the development of an understanding for how design capability is developed based on interpretations founded in the organizational learning perspective of absorptive capacity. The study has identified how different antecedents to development of design capability have influenced this development in the two cases. The findings have identified aspects that both support and impede the development of design capability which are important to acknowledge and address when aiming to develop design capability within a public sector organization. In both cases, the set up of the knowledge transferring efforts focus mainly on developing awareness of design. Similar patterns are seen in other prior and parallel initiatives. The findings however suggest that it is also important to ensure that the organization have access to design competence and that structures like routines, processes and culture support and enable the use of design practice, in order to make design a natural part of the continuous development work.
367

Intraspecific Variation of Aboveground Woody Biomass Increment in Hybrid Poplar at High Temperature

Shiach, Ian M., Shiach, Ian M. January 2017 (has links)
In the continental United States, mean surface air temperature is expected to increase by up to 5°C within 100 years. With hotter temperatures, leaf budbreak is expected to occur earlier in forests, and leaf area is expected to increase in locations where temperature is limiting. The response of plant photosynthesis to hotter temperatures is less certain; plant productivity could increase or decrease. Past studies have found intraspecific variation in the responses of forest tree productivity, phenology, canopy leaf area, and leaf isoprene emission to warming, which all influence carbon uptake and yield for agricultural tree species; it is therefore important to understand not only how hot climates affect carbon uptake and biomass production between different tree species, but also in different genotypes of the same species. We conducted a common garden study at the Biosphere 2 research center near Oracle, AZ, USA. We created a hybrid poplar plantation of 168 trees, which were planted as cuttings in January 2013. The trees used in this study are comprised of 5 distinct genotypes of Populus deltoides × trichocarpa from a range of average annual air temperatures. We measured photosynthetic capacity, leaf phenological timing, canopy leaf area and aboveground woody biomass in 2014 growing season, and leaf isoprene emission in the 2015 growing season. We observed a strong effect of genotype on aboveground woody biomass increment, implying strong local adaptation to the home range and limited phenotypic plasticity in terms of physiological and biometric responses to high temperature environments. Our study suggests that genotypes from hotter home ranges are able to maintain photosynthetic capacity and canopy leaf area late into the growing season, despite high temperatures, and thus produce more aboveground woody biomass. This study may have implications for agricultural management—as temperatures warm where managers currently grow hybrid poplar for agricultural or other purposes, the genotypes from those home ranges would likely have reduced yield; managers could investigate the use of genotypes from home ranges with higher average temperatures to replace the vulnerable local varieties.
368

Exploring Holacracy’s Influence on Social Sustainability Through the Lens of Adaptive Capacity

Archer, Isaiah, Muirhead, Lewis, Forrester-Wilson, Sarah January 2016 (has links)
The organizational structure of Holacracy has been gaining popularity in recent years, but a lack of academic research on Holacracy called for a systematic approach to assessing its merits and shortcomings. The need Holacracy fills, is that of organizations dealing with a complex world and rapidly evolving technology. While Holacracy is not tailored to address sustainability issues, there are many components that made it a candidate for the researchers to examine it through a social sustainability lens. This study examines the effect of specific components of Holacracy with elements of adaptive capacity – a theory from which the research definition of social sustainability was built. With the goal of determining the effect of Holacracy on social sustainability, a questionnaire directed at employees and practitioners of holacratic organizations was utilized. The findings implied that Holacracy does positively influence the experience of the elements of adaptive capacity; with the relationship to the adaptive capacity element of self-organization being a standout. The importance of trust is also identified. The link to the Framework for Strategic Sustainable Development can be elucidated through adaptive capacity’s influence to the social sustainability principles. Because of the importance of social sustainability and social capital to organizational performance and longevity, this research is of value to any business using, or considering using Holacracy.
369

Elite Politics and Inequality: The Development of Fiscal Capacity in Authoritarian Regimes

Hollenbach, Florian Max Benjamin January 2015 (has links)
<p>The ability to raise revenue is one of the most fundamental requirements for state- hood. Without revenues, states are unable to perform even the most basic tasks. In this dissertation I aim to answer the question: When do authoritarian elites in- vest in fiscal capacity? First, I develop a theoretical argument using computational modeling techniques. I contend that inequality increases the costs associated with higher fiscal capacity due to a possible regime change in the future. On the other hand, elite demand for government spending can raise the incentives for autocrats to increase the tax capacity of the state. Complimentarity between elite-owned capital and government investment can lead to a demand for higher taxation. Based on their personal utility associated with government spending, elites weigh the current benefit of higher tax capacity with possible future costs.</p><p>I then test the overarching theoretical argument across two different datasets. First, I empirically investigate the question on a sample of over 90 authoritarian regimes from 1980 to 2006. Estimating a number of different models and including a variety of controls, I find that inequality has a strong negative long term effect on fiscal capacity. On the other hand, more industrial countries have higher levels of capacity. In the second empirical chapter, I investigate the theoretical argument on newly collected data on tax revenue and administrative spending in local Prussian counties in the 19th century. Again, I find that local inequality has strong negative effects, while more industrial areas are associated with higher levels of fiscal capacity.</p> / Dissertation
370

Public Participation in Water Planning in the Ebro River Basin (Spain) and Tucson Basin (U.S., Arizona): Impact on Water Policy and Adaptive Capacity Building

Ballester, Alba, Mott Lacroix, Kelly 29 June 2016 (has links)
The benefits of public participation in water management are recognized by governments, scholars, and stakeholders. These benefits, however, do not result from all engagement endeavors. This leads to the question: What are the determinants for effective public participation? Given a list of criteria for achieving the transformational capacity of participation, we analyze the benefits (including the influence on public policies) gained through public participation and the determinant factors for obtaining these benefits in the Ebro River Basin in Spain and in the Tucson Basin in Arizona (U.S.). Furthermore, and considering that droughts and floods are major water management challenges in both case studies, we focus on the potential of participation to build adaptive capacity. Our analysis of these case studies concludes that influence on public policies is determined more by the context of the participatory process, i.e., legal framework, political leadership, and social awareness, whereas influence on adaptive capacity building depends more on the characteristics of the participatory process, particularly the existence of active on-site consultation and deliberation.

Page generated in 0.0721 seconds