• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1090
  • 612
  • 303
  • 153
  • 115
  • 68
  • 52
  • 43
  • 36
  • 27
  • 23
  • 23
  • 22
  • 17
  • 9
  • Tagged with
  • 2962
  • 474
  • 338
  • 304
  • 230
  • 200
  • 199
  • 183
  • 177
  • 169
  • 139
  • 130
  • 116
  • 115
  • 113
  • 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.
311

Examples of Volume-Preserving Great Circle Flows of S3

Haskett, Ryan 01 May 2000 (has links)
This summer Herman Gluck and Weiqing Gu proved the last step in a process that took conformal maps between two complex spaces and related them to Volume Preserving Great Circle Fibrations of S3. These fibrations, which are non-intersecting flows, break down under certain conditions. We obtained the fibrations by applying the process to different conformal maps then calculated the angles where they intersect. This paper centers around the developments in the method for converting the conformal maps and finding the critical angles. Finally, the examples are included in their various stages of completeness.
312

EXAMINATION OF VOLUME AND INTENSITIES OF WEEKDAY PRACTICES AND COMPETITIVE GAMES IN COLLEGIATE FOOTBALL PLAYERS

Lindon, Tyler 01 January 2017 (has links)
The aims of the present study were to characterize the typical volume (total distance) and intensities (high-speed distance > 75% of maximum speed for weekday practices, Monday through Friday and competitive games on Saturday; compare the daily practice volume and intensities to competitive games to determine if the targeted volume and intensities are achieved as part of the periodized strategies using GPS software; and examine the relationship among total distance, high-speed distance in the prediction of player-load . Thirty NCAA Division I Football players (187.9 ± 5.5 cm; 107.4 ± 24.6 kg) were monitored using GPS receivers with integrated accelerometers during the 13-week regular season during the 2016 season. Separate one-way repeated measures ANOVAs demonstrated that competitive game loads and intensity were significantly different than weekday practices (p-value ≤ 0.05). There were significant differences among weekday practices in terms of overall volume and intensities, however the overall training goals were not met. Stepwise linear regression revealed that total distance is a significant predictor of player load. The results of the present study indicated that total distance, but not high-speed distance, could best be used to describe and track the development of a periodization model for training in Division I Collegiate Football using GPS technologies.
313

The contribution of the lymph hearts in compensation for acute hypovolemic stress in the toad Bufo marinus

Baustian, Mark 01 January 1986 (has links)
Currently published data on the role of the lymphatic system in amphibians are inadequate and contradictory. Estimates of the rate of formation of lymph and the role of the lymph hearts in returning this fluid to the circulation are not based on actual volume determinations but rather estimates derived from changes in hematocrit using published values of plasma and blood volume. The lymph hearts are known to be vital to the maintenance of normal fluid compartment physiology and to increase their rate of activity during episodes of hypovolemic stress. Yet, significant redistribution of body fluids following hemorrage appears to occur in animals without lymph hearts. In this study, plasma and blood volumes were determined by the dye dilution technique using injected Evan's blue dye to label the plasma. Eight intact and 6 animals with their lymph hearts destroyed were hemorrhaged to 78% and 75% of their initial blood volumes, respectively. Changes in blood volume were measured following the hemorrhage by analysis of Evan's blue washout and hemodilution.
314

Change in lung volume in asthma with particular reference to obesity

Schachter, L. M January 2005 (has links)
Doctor of Philosophy(PhD) / Over the last 20 years both asthma and obesity have increased in prevalence. What is the link? There are data to suggest that increasing obesity is a risk for the increase in prevalence of asthma. A number of mechanisms have been postulated including the effects of reduced lung volume on bronchial reactivity and mechanical changes with lower lung volumes. Other possibilities include other obesity-induced co-morbidities including gastro-oesophageal reflux. The aim of this thesis was to evaluate the link between asthma and obesity in both adult and childhood populations and to undertake experimental studies to examine the effects of changes in lung volume on bronchial reactivity. In chapter 1, the literature is reviewed. The current literature suggests that there is a link between diagnosis of asthma, new onset of asthma, symptoms of shortness of breath and wheeze. In chapter 2, data on 1997 adults in 3 population studies were analysed and the association between body mass index (BMI) and symptoms of shortness of breath and wheeze, diagnosis of asthma, medication usage for asthma, lung function and bronchial responsiveness were studied. This study showed that obesity was a risk for recent asthma (OR 2.04; 95%CI 1.02-3.76, p=0.048), symptoms of shortness of breath and wheeze (OR 2.6; 95%CI 1.46- 4.70, p=0.001), and medication usage for asthma (OR 2.53; 95%CI 1.36-4.70, p=0.003). There was a reduction in lung volume as measured by forced vital capacity (FVC), but there was no increase in bronchial hyperresponsiveness (BHR) (OR 0.87; 95% CI 0.35-2.21, p=0.78). Thus although the symptoms of asthma are increased there were no increases in BHR, despite significantly reduced lung volumes. The increase the medication usage is unlikely to have normalised the BHR, as there were ongoing symptoms suggestive of asthma. In chapter 3, data on 5993 children in 7 population studies were analysed and the association between BMI percentile and symptoms of cough, wheeze, ix diagnosis of asthma, medication usage for asthma, atopy, lung function and bronchial responsiveness was studied. After adjusting for atopy, sex, age, smoking and family history, BMI was a significant risk factor for wheeze ever (OR=1.06; 95%CI 1.01-1.10, p=0.008) and cough (OR=1.09; 95%CI 1.05-1.14, p=0.001) but not for recent asthma (OR=1.02; 95%CI 0.98-1.07 p=0.43), or bronchial hyperresponsiveness (OR=0.97; 95%CI 0.95-1.04 p=0.77). In girls, a higher BMI was significantly associated with higher prevalence of atopy (x2 trend 7.9, p=0.005), wheeze ever (x2 trend 10.4, p=0.001), and cough (x2 trend 12.3, p<0.001). These were not significant in boys. With increasing BMI in children, there was no reduction in lung volume, no increase in airway obstruction and no increase in bronchial responsiveness. In chapter 4, the hypothesis that obesity per se is associated with bronchial responsiveness was tested. Six obese women without asthma were compared to 6 non-obese women without asthma with high dose methacholine challenges to assess the bronchial responsiveness. There was no increase in bronchial responsiveness, and no difference in the position or shape of the high dose methacholine curve despite the fact that these women had reduced lung volumes associated with their obesity. In chapter 5, the hypothesis whether reduced lung volume per se would cause a change in greater mechanical effect, ie more marked airway narrowing in both non-asthmatic and asthmatic subjects was tested. Lung volumes and methacholine challenges were undertaken in the supine and erect position on different days. As expected in normal subjects there was a small reduction in lung volume on lying down, this was associated with an increase in the measure of bronchial reactivity DRR. In contrast, in asthmatics, there was no acute fall in lung volume and there were variable changes in the index of reactivity suggesting non-homogeneity in the lung function abnormality. This suggests changes in bronchial reactivity can occur without any relationship to lung volume change. These negative results suggest that lung volume changes that may occur in obesity are unlikely contributors to the apparent increase in asthma symptoms. In chapter 6, the hypothesis that the supposed increase in asthma symptoms in the obese were due to the effects of gastro-oesophageal reflux were assessed in 147 obese subjects graded for gastro-oesophageal reflux severity using manometry and gastroscopy. This study showed that subjects with increased gastro-oesophageal reflux did not have subjective increases in asthma prevalence, obstructive sleep apnoea, or snoring however they had a clear worsening of gas transfer as measured by carbon monoxide transfer suggesting a greater level of parenchymal disease. The overall results are that there is an increase of diagnosis of asthma, increase in symptoms of asthma and medication usage for the treatment of asthma in the obese. Objectively despite reductions in lung volume, there is no increase in bronchial responsiveness in this group suggesting that these symptoms are not related to true asthma, but to alternative co-morbidities associated with obesity such as gastro-oesophageal reflux. Notably gastrooesophageal reflux was not associated with increased asthma prevalence or airway obstruction. However it was associated with reduced gas transfer suggesting parenchymal disease. This suggests that the increase in symptoms of wheeze and shortness of breath in the obese should not be attributed to asthma in the absence of variable airflow limitation that is reversible spontaneously or with treatment, or with an increase in the existing bronchial hyperresponsiveness (BHR) to a variety of stimuli.
315

Real-time DVR Illumination Methods for Ultrasound Data

Sundén, Erik January 2010 (has links)
<p>Ultrasound (US) volume data is noisy, so traditional methods for direct volume rendering (DVR) are less appropriate. Improved methods or new techniques are required. There are furthermore a high performance requirement and limited pre-processing to be considered in order for it to be used interactively, since the volume data might be time-varying.</p><p>There exist numerous techniques for improving visual perception of volume rendering, and while some perform well and produce a visually enhanced result, many are designed and compared for use with medical data that has a high signal-to-noise ratio. This master thesis describe and compare recent methods for DVR illumination, in the form of ambient occlusion or direct/indirect lighting from an external light source. New designs and modifications are introduced for efficiently and effectively enhancing the visual quality of DVR with US data. Furthermore, this thesis addresses the issue of how clipping is performed during rendering and for the different illumination techniques, which is commonly used in ultrasound visualization.</p><p>This diploma work was conducted at Siemens Corporate Research in Princeton, NJ where the partially open source framework XIP is developed. The framework was extended further to include modern methods for DVR illumination that are described in detail within this thesis. Finally, presented results show that several methods can be used to visually enhance the visualization within highly interactive frame-rates.</p>
316

Graded-channel and multiple-gate devices in SOI technology for analog and RF applications

Chung, Tsung Ming 26 April 2007 (has links)
The motivation to study this non-classical CMOS device is necessary to face with the ITRS constraints. In the ITRS roadmap, the gate length of devices are being scaled down rapidly but this rapid scaling is not in pace with the relatively slow scaling of the gate equivalent oxide thickness which leads to a degradation in the performance of the transistor. One of the solutions to this problem is the use of non-classical devices, such as the Gate-All-Around (GAA) MOSFET. Owing to the flexibility of SOI technology, these novel devices can be adapted to this technology bringing along with it the benefit of SOI technology. One of the main advantage of building this GAA device on SOI technology is that it offers the possibility whereby the second gate is easily built into the back of the device. GAA devices are also interesting because they do not need to scale down the thickness of the gate oxide rapidly but still able to maintain a suitable thickness to avoid problems such as current leakage through the thin gate oxide by tunnelling. The objective of this research can be divided into three parts; the first is to study the feasibility of the various fabrication process for this GAA device, the second to analyse the electrical characteristics of these fabricated GAA devices from DC characteristics up to 110 GHz and the third one is the use of commercial numerical simulation softwares (IE3D, Silvaco) in order to describe the physics of these novel devices. In this study, these different structures shows advantages and disadvantages when used in either analog or RF applications. The graded-channel structure has shown that it is advantageous when used in high performance analog circuits. The advantages of this structure is further enhanced when it is combined with the double-gate structure, forming a double-gate graded channel SOI MOSFET. Optimizing in terms of doping level along the channel of the graded-channel is important to yield good electrical results. In order for these devices to be successful commercially, it is important that they are compatible with the fabrication technology and trends available today and in the near future. To confirm that these devices can be adapted into today's and tomorrow's technology, we have shown that these they are easily adaptable in the current technology. Multiple-gate devices are a new group of devices which have been identified by ITRS as potential devices to meet the demands in the future. In this study, we have shown that these multiple-gate devices do indeed show improved short-channel effects and improved analog and RF characteristics when compared to the single-gate devices in existence. One of the main contributors to these improvements is due to what is known as the “volume inversion”.
317

Relationship of human tongue volume with inter-dental maxillary and mandibular arch width, palatal axial cross-sectional perimeter, palatal index and root axial inclination

Mandich, Marie-Alice 11 1900 (has links)
Objective : To determine the relationship of tongue volume as determined from Cone Beam Computed Tomography (CBCT) scan reconstructions with maxillary and mandibular arch width, axial cross-sectional palatal perimeter, palatal index and axial inclination of upper and lower first premolars and molars. Method: Thirty subjects without prior orthodontic treatment swished barium sulfate to coat the tongue prior to CBCT imaging. The scan reconstructions were analyzed with three after-market softwares and intra-examiner reliability was assessed. Results: Absolute agreement intra-class correlation coefficients were used to determine reliability of the measurements. Pearson correlation coefficients and regression analysis were used to determine relationships. Conclusions: Tongue volume was strongly correlated with upper inter-molar width and palatal perimeter at the molar level, and least correlated with lower inter-molar width and axial inclination of the upper and lower first premolars and molars. The differences in measurements obtained from the three softwares were not statistically significant.
318

A system for real-time rendering of compressed time-varying volume data

She, Biao 06 1900 (has links)
Real-time rendering of static volumetric data is generally known to be a memory and computationally intensive process. With the advance of graphic hardware, especially GPU, it is now possible to do this using desktop computers. However, with the evolution of real-time CT and MRI technologies, volumetric rendering is an even bigger challenge. The first one is how to reduce the data transmission between the main memory and the graphic memory. The second one is how to efficiently take advantage of the time redundancy which exists in the time-varying volumetric data. Most previous researches either focus on one problem or the other. In this thesis, we implemented a system which efficiently deals with both of the challenges. We proposed an optimized compression scheme that explores the time redundancy as well as space redundancy of time-varying volumetric data. The compressed data is then transmitted to graphic memory and directly rendered by GPU, so the data transfer between main memory and graphic memory is significantly reduced. With our implemented system, we successfully reduce more than half of the time of transferring the whole data directly. We also compare our proposed compression scheme with the one without exploiting time redundancy. The optimized compression scheme shows a reduce compression distortion over time. With usability, portability and extensibility in mind, the implemented system is also quite flexible.
319

Development and applications of a full-stress flowband model for ice using the finite volume method /

Price, Stephen F., January 2006 (has links)
Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 149-159).
320

Volume and Time Doubling of Graphs and Random Walks, the Strongly

Andras Telcs, h197tel@ella.hu 30 March 2001 (has links)
No description available.

Page generated in 0.0933 seconds