• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3556
  • 1657
  • 509
  • 451
  • 343
  • 267
  • 131
  • 82
  • 67
  • 53
  • 47
  • 47
  • 47
  • 47
  • 47
  • Tagged with
  • 8758
  • 1441
  • 1276
  • 1270
  • 857
  • 596
  • 565
  • 522
  • 476
  • 396
  • 392
  • 356
  • 340
  • 332
  • 308
  • 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.
61

A novel cuffless technique for non-invasive blood pressure measurement under post-exercise conditions. / CUHK electronic theses & dissertations collection

January 2008 (has links)
Cardiovascular diseases (CVD) are the leading cause of death. It is also one of the major factors resulting sudden deaths in exercises. Blood pressure (BP) is one of the vital diagnostic parameters to reflect the functionality of cardiovascular system and evaluate the conditions of CVD. However, current BP measuring devices usually require the occlusion of cuff that causes inconvenience to users during measurement. They are neither suitable nor practical for long-term monitoring. Pulse transit time (PTT), the duration for a pressure pulse wave to travel from one arterial site to another, has been proposed as a potential parameter for cuffless BP measurement in recent decades. Because of its cuffless and non-invasive measuring features, the aim of the present study is to develop a novel PTT-based BP estimation for cuffless and non-invasive monitoring of BP under resting and exercise conditions. / The accuracy of proposed method for continuous BP monitoring has been evaluated on seventeen subjects during cycling. Brachial BP was measured by FinapresRTM (Fin. BP) and a trained nurse (Nur. BP). In approximate 22000 beats, the differences between predictions and Fin. BP were 1.3+/-13.0 mmHg for SBP and -1.5+/-6.1 mmHg for DBP respectively. The intermittent BP measurements using the proposed method were compared to the readings from FinapresRTM and nurse separately. The differences between proposed method and Nur. BP were 0.9+/-9.9 mmHg for SBP and -1.2+/-5.2 mmHg for DBP respectively. The differences between proposed method and Fin. BP were -0.1+/-12.6 mmHg for SBP and -1.4+/-5.9 mmHg for DBP respectively. The predictions using the proposed method were more consistent with the nurse readings. Furthermore, thorax impedance signal was proposed for cuffless BP estimation and it was examined on twenty-two subjects. The results illustrated that proposed parameters, measured from Q wave of electrocardiogram to the peaks of thorax impedance signal and its derivative, were highly correlated with BP. They were potential parameters to provide non-invasive and cuffless BP estimation. / To conclude, the accuracy of proposed method was comparable to the cuff-based approaches under resting and exercise conditions. This work is potential to solve the problems due to prevalence of CVD and rising aging population. (Abstract shortened by UMI.) / Wong, Yee Man. / Adviser: Y. T. Zhang. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3650. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
62

Adaption of bacteria to hydrostatic and osmotic pressure : a tale of two sisters

Black, Stuart Lucas January 2011 (has links)
Adaption to environmental stresses is vital for the survival of all organisms living in any environment. Two of the major environmental factors in the deep sea environment are high hydrostatic pressure and high salt concentration. Hydrostatic pressure and osmotic pressure share similarities in their effects on organisms living in the deep sea but this overlap has been little explored. Major studies from Japan and California over the last 40 years have shown the effects of hydrostatic pressure on bacteria from the deep sea (see [1] for a review). These are complemented by work by Yancey et al. [2] showing that specific solutes accumulated in response to osmotic pressure in fish have the ability to enhance resistance to hydrostatic pressure. However, this work has been done in vitro or with larger organisms and not much is known about the overlap of osmotic and hydrostatic pressure in bacteria. In this study I investigated the effects of osmotic and hydrostatic pressure on two model organisms: Photobacterium profundum and Escherichia coli. In order to accomplish this task I developed novel imaging equipment which allows for high resolution imaging of bacteria at pressure. I also developed a new method of growing bacteria in 96-well plates at high pressure, which lead to the identification of a hierarchy of genes essential for the growth of E. coli at pressure. I used the same 96-well plate technique to monitor the growth of P. profundum at differing osmotic and hydrostatic pressures. Furthermore I also attempted to analyse the solutes accumulated by different strains of P. profundum in response to osmotic and hydrostatic pressures.
63

Flexible Sensor for Measurement of Skin Pressure and Temperature for the Prevention of Pressure Ulcers

Crivello, Matthew DeMorais 01 March 2017 (has links)
With the prolonged lifespan of the average person, the number of hospital stays have increased. Currently, pressure ulcers are one of the most severe complications associated with prolonged hospital stay. The protocol in today€™s hospital is to rotate bedridden patients once every two hours to prevent pressure ulcers. This puts a strain on attending nurses as the risk of a pressure ulcer for a patient is not universal and therefore, a universal preventative protocol is not the most effective solution. This thesis describes the circuit design and physical implementation of a device to address the issue of pressure ulcers. The device has the form factor of a patch to be placed on specific, at risk areas of the human body. The device was designed and prototyped first on a rigid structure and then on a flexible printed circuit board substrate. A calibration procedure was developed to reduce part to part variability inherent to the pressure sensor. The resistance measurement was achieved through a novel approach including the use of a timer removing the need for an analog-to-digital converter. A seven hour experiment was conducted with live, animal subjects to measure the pressure and temperature of at risk areas of the body. The results of the experiment successfully prove the fundamental approach outlined in this thesis and justify continued research and refinement into the product design.
64

Determinants of blood pressure in pregnancy.

January 1997 (has links)
by Cathy Yui Hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 129-152). / Abstract --- p.i / List of A bbreviations --- p.iv / Table of Contents --- p.vii / Chapter CHAPTER 1 --- INTRODUCTION / Chapter 1. --- Definitions & Morbid implication of PIH / Chapter 1.1. --- Definition of PIH --- p.1 / Chapter 1.2. --- Classification --- p.2 / Chapter 1.3. --- Background --- p.3 / Chapter 2. --- Aetiology PIH --- p.4 / Chapter 2.1. --- Anatomy of placenta --- p.4 / Chapter 2.2. --- Physiology of placenta --- p.4 / Chapter 2.3. --- The placenta as the cause of PIH --- p.6 / Chapter 2.4. --- Pathology of the placental bed --- p.7 / Chapter 3. --- Epidemiology of PIH --- p.9 / Chapter 3.1. --- Maternal risk factors --- p.9 / Chapter 3.2. --- Fetal risk factors --- p.10 / Chapter 3.3. --- Genetics of PIH --- p.10 / Chapter 3.4. --- Maternal outcome --- p.12 / Chapter 3.5. --- Fetal outcome --- p.13 / Chapter 4. --- Pathophysiologic changes in PIH --- p.14 / Chapter 4.1. --- Important Pathophysiologic changes in PIH --- p.14 / Chapter 4.1.1. --- Hyperdynamic circulation --- p.14 / Chapter 4.1.2. --- Changes in Intravascular volume --- p.15 / Chapter 4.1.3. --- Loss of resistance to Angiotensin II and catecholamines --- p.16 / Chapter 4.1.4. --- Coagulation abnormalities --- p.16 / Chapter 4.1.5. --- Platelets --- p.17 / Chapter 4.2. --- Multisystem disorder in PIH --- p.18 / Chapter 4.2.1. --- The kidney --- p.18 / Chapter 4.2.2. --- The liver --- p.19 / Chapter 4.2.3. --- The brain and nervous system --- p.19 / Chapter 4.2.4. --- Cardiovascular and renin-angiotensin systems --- p.20 / Chapter 4.2.5. --- Placenta --- p.21 / Chapter 5. --- Prediction of PIH --- p.22 / Chapter 5.1. --- Standard methods of antental care --- p.22 / Chapter 5.1.1. --- Blood pressure increase in antenatal period --- p.22 / Chapter 5.1.2. --- Second Trimester Mean Arterial Pressure --- p.23 / Chapter 5.1.3. --- Proteinuria --- p.25 / Chapter 5.1.4. --- Excessive weight gain and edema --- p.26 / Chapter 5.1.5. --- Platelet count --- p.27 / Chapter 5.2. --- Vasoconstriction tests --- p.27 / Chapter 5.2.1. --- The Isometric Handgrip Exercise Test --- p.27 / Chapter 5.2.2. --- Roll-Over Test --- p.28 / Chapter 5.2.3. --- Infusion of Angiotensin II --- p.31 / Chapter 5.3. --- Biochemical tests --- p.33 / Chapter 5.3.1. --- Urinary Calcium excretion --- p.33 / Chapter 5.3.2. --- Prostacyclin & throboxane A2 --- p.33 / Chapter 5.3.3. --- Platelet Angiotensin II receptors --- p.34 / Chapter 5.4. --- Ultrasougographic evaluation --- p.36 / Chapter 5.4.1. --- Doppler waveforms of uteroplacental circulation --- p.36 / Chapter 6. --- Prevention & treatment of PIH --- p.38 / Chapter 6.1. --- Antihypertensive drugs --- p.40 / Chapter 6.2. --- Antithrombotic agents --- p.40 / Chapter 6.2.1. --- Low-dose aspirin --- p.40 / Chapter 6.3. --- Calcium supplementation --- p.44 / Chapter CHAPTER 2 --- General Methodology / Chapter 1.1 --- Introduction --- p.48 / Chapter 1.2. --- Materials --- p.48 / Chapter 2. --- Studies --- p.51 / Chapter 2.1. --- Validation of Cor-7000 Sphygmomanometer --- p.51 / Chapter 2.1.1. --- Patients --- p.51 / Chapter 2.1.2. --- Methods --- p.51 / Chapter 2.1.3. --- Statistics --- p.52 / Chapter 2.1.4. --- Results --- p.53 / Chapter 2.2. --- Platelet ANG II receptor status and systemic vascular resistance --- p.58 / Chapter 2.2.1. --- Control subjects --- p.58 / Chapter 2.2.2. --- Patient subjects --- p.58 / Chapter 2.2.3. --- Platelet preparation and platelet angiotensin II binding site assay --- p.60 / Chapter 2.2.3.1. --- Statistical analysis --- p.62 / Chapter 2.2.3.2. --- Results --- p.63 / Chapter 2.2.4. --- Using impedance techniques to measurement of systemic vascular resistance --- p.74 / Chapter 2.2.4.1. --- Measurement of Cardiac Output by impedance cardiography --- p.74 / Chapter 2.2.4.2. --- Validity of transthoracic electrical bioimpedance technique --- p.81 / Chapter 2.2.4.3. --- Measurement of mean arterial pressure --- p.87 / Chapter 2.2.4.3.1. --- Experimental technique --- p.87 / Chapter 2.2.4.3.2. --- Statistical analysis --- p.92 / Chapter 2.2.4.4. --- Results --- p.92 / Chapter 2.2.4.5. --- Data analysis --- p.93 / Chapter 2.2.4.6. --- Relationship between platelet ANG II binding and haemodynamic indices --- p.110 / Chapter 2.2.4.7. --- pregnancy outcome --- p.115 / Chapter CHAPTER 3. --- RESULTS / Chapter 1. --- Study 1 Validation of Cor 7000 sphygmomanometer --- p.116 / Chapter 2. --- Study 2 Platelet ANG II receptor status and systemic vascular resistance --- p.118 / Chapter 2.1. --- Platelet Angiotensin II binding Assay --- p.118 / Chapter 2.2. --- Limitation of the TEB technique --- p.121 / Chapter 2.3. --- Changes in blood pressure and other cardiovascular indices --- p.122 / Chapter 2.4. --- Relationship between Platelet ANG II binding and Haemodynamic indices --- p.124 / Chapter CHAPTER 4 --- CONCLUSION / Chapter 4.1. --- Conclusion --- p.126 / References --- p.129 / Acknowledgments
65

The organisation and behaviour of interest groups: a theoretical review and application to South Africa

Sellars, Christian 02 1900 (has links)
In recent years. South Africa’s business and union leaders have often been called on to replicate the country’s substantial political achievements, in the economic sphere. Two important documents released in mid 1996 discuss the establishment of structures to facilitate dialogue between government, labour and business. The purpose of this would be to try to find ways of generating the growth and employment sorely needed in the country if democracy is to lead to any improvement in the living conditions of the majority. The government’s macroeconomic strategy paper - ‘Growth, Employment and Redistribution,’ commonly referred to as GEAR, was released first, followed by the report of the Labour Market Commission (LMC) convened by the President to investigate labour policy. The GEAR document proposes ‘a broad national agreement to create an environment for rapid growth, brisk investment and accelerated delivery of public services’ (1996: 26). The agreement would be needed to prevent the recent depreciation of the Rand from triggering a vicious cycle of wage and price increases which would destabilise financial markets and undermine the competitiveness of local industry. This could be achieved, GEAR argues, if labour and business were willing to consider the restraint of wages and prices. The idea of a national agreement is further elaborated in the LMC report, which proposes a ‘National Accord’ (1996). This proposal follows from the LMC’s belief that the negotiation of economic issues through institutional structures, as opposed to direct regulation by government statute, is both socially desirable and economically efficient (ibid, 219). Price restraint, wage restraint and investment decisions, together with tangible commitments from government on training, social welfare provision and industrial promotion would be the main issues covered by the accord. South Africa’s economic policy framework has been subject to heated debate since the release of GEAR. The union movement has expressed serious reservations about the market orientation of the government’s macroeconomic strategy. Given this position, together with the complex and fragmented structure of interest organisation in South Africa, the prospects for an accord or national agreement are not promising. Yet, the government has expressed the desire to set one up. This paper provides a review of political theory on interest groups. The purpose of this is to draw concepts and ideas from contributions in this area to see if they can shed any light on the nature of interest group interaction in South Africa, particularly with respect to the possibility of establishing a social accord. The review draws from two bodies of thought. The first is the theory of corporatism and the second that of public choice (often referred to as rational choice). Corporatist theory has enjoyed a fair degree of popularity amongst South African social scientists. However, the debate between them has not progressed very far, mainly due to confusion over terminology. Further, as argued Section 1, some local contributions have misread the international literature, ignoring aspects which might be of relevance to South Africa. These omissions are re-examined, but the section concludes that there are limitations in the extent to which corporatist theory is able to explain the dynamics of interest group formation and behaviour. Section 2 tries to find alternative explanations in the theory of public choice. The methodological integrity and general value of public choice theory has been strongly questioned (Green & Shapiro, 1994). While the paper provides a synopsis of public choice literature and a review of its critics, the focus is on the analysis of collective action. Despite the shortcomings which it shares with general public choice, this analysis provides useful theoretical pointers which can assist in developing an understanding of interest group dynamics which goes beyond corporatist theory. In the third section, the paper comes back to South Africa and looks at the recent history of interest organisation to establish whether any of the theoretical tools picked up in previous sections are helpful in understanding the local experience. After a general background, the section goes into the discussion of three particular issues, being: community participation in policy formation, trade policy and the labour market. Section 4 acknowledges that there is potential to build the capacity of interest organisations in South Africa and to restructure their interaction in socially beneficial ways. However, a number of issues are identified which mitigate against the conclusion of an effective social accord. These include the weaknesses evident in interest group organisation, the alliance between the African National Congress and the union federation Cosatu,1 and the absence of competition in South Africa at party political level. It is concluded that electoral reform might be a better means of democratising the country’s political environment than attempts at managing interest groups. / Working paper (South African Network for Economic Research) ; v. 1
66

A model-based calibration method for the design of wearable and cuffless devices measuring arterial blood pressure.

January 2008 (has links)
Liu, Yinbo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 74-79). / Abstracts in English and Chinese. / Abstract --- p.i / List of Figures --- p.iv / List of Tables --- p.viii / Introduction --- p.1 / Chapter 1.1 --- Current status of Blood Pressure Management --- p.1 / Chapter 1.2 --- Current Status of Noninvasive Blood Pressure Measurement Techniques --- p.4 / Chapter 1.3 --- Motivations and Objectives of This Thesis --- p.9 / Chapter 1.4 --- Organization of This Thesis --- p.9 / Backgrounds --- p.11 / Chapter 2.1 --- Principle of the Pulse Transit Time-based Approach for BP Measurement --- p.11 / Chapter 2.1.1 --- General Descriptions --- p.11 / Chapter 2.1.2 --- Pressure Wave Propagation in Cylindrical Arteries --- p.13 / Chapter 2.1.3 --- Determining the PTT for BP Measurement --- p.14 / Chapter 2.2 --- Backgrounds for Pressure Related Elastic Properties of Artery --- p.17 / Chapter 2.2.1 --- Transmural Pressure and Its Components --- p.17 / Chapter 2.2.2 --- Volume-pressure Models --- p.19 / Chapter 2.2.3 --- Types and Structure of the Artery and Its Properties --- p.20 / Chapter 2.3 --- Literature Review on the Calibration Methods for Cuffless Blood Pressure Measurements --- p.22 / Chapter 2.4 --- Section Summary --- p.25 / Investigations on Factors Affecting PTT or BP --- p.26 / Chapter 3.1 --- The Effects of External Pressure --- p.26 / Chapter 3.1.1 --- Background --- p.26 / Chapter 3.1.2 --- Experimental protocol --- p.28 / Chapter 3.1.3 --- Analysis for the Effects of External Pressure on PTT --- p.30 / Chapter 3.1.4 --- Section Discussions --- p.31 / Chapter 3.2 --- The Effects of Hydrostatic Pressure --- p.32 / Chapter 3.2.1 --- Experimental protocol --- p.33 / Chapter 3.2.2 --- Analysis for the Effects of Hydrostatic Pressure on PTT --- p.34 / Chapter 3.2.3 --- Section Discussions --- p.37 / Chapter 3.2.4 --- Section Summary --- p.38 / Modeling the Effect of Hydrostatic Pressure on PTT for A Calibration Method --- p.39 / Chapter 4.1 --- Current Status of Hydrostatic Calibration Approaches --- p.39 / Chapter 4.2. --- Modeling Pulse Transit Time under the Effects of Hydrostatic Pressure for A Hydrostatic Calibration Method: --- p.40 / Chapter 4.2.1 --- Basic BP-PTT model --- p.40 / Chapter 4.2.2 --- V-P relationship Represented by a Sigmoid Curve --- p.40 / Chapter 4.2.3 --- Relating PTT with Hydrostatic Pressure --- p.41 / Chapter 4.2.4 --- Implementing the Hydrostatic Calibration Method for BP Estimation --- p.43 / Chapter 4.3. --- Preliminary Experiment --- p.44 / Chapter 4.3.1. --- Experimental Protocol and Methodology --- p.44 / Chapter 4.3.2. --- Experimental Analysis --- p.46 / Chapter 4.4. --- Section Discussions --- p.48 / Chapter 4.5. --- A Novel Implementation Algorithm of Hydrostatic Calibration Method for Cuffless BP Estimation --- p.49 / Chapter 4.6. --- Section Summary --- p.50 / Experimental Studies for the Hydrostatic Calibration Approach --- p.51 / Chapter 5.1 --- Experimental Analysis --- p.51 / Chapter 5.1.1 --- Experimental Protocol --- p.51 / Chapter 5.1.2 --- Methodology --- p.53 / Chapter 5.1.3 --- Preparations --- p.54 / Chapter 5.1.4 --- Experimental Results --- p.56 / Chapter 5.2 --- Section Discussions --- p.63 / Chapter 5.3 --- Section Summary --- p.70 / Conclusions and Suggestions for Future Works --- p.71 / Chapter 6.1 --- Conclusions --- p.71 / Chapter 6.2 --- Suggestions for Future Works --- p.72 / Reference --- p.71
67

Principal stress pore pressure prediction: utilizing drilling measurements to predict pore pressure

Richardson, Kyle Wade 15 May 2009 (has links)
A novel method of predicting pore pressure has been invented. The method utilizes currently recorded drilling measurements to predict the pore pressure of the formation through which the bit is drilling. The method applies Mohr’s Theory to describe the stresses at the bottom of the borehole. From the stress state and knowledge of Mohr’s Envelope, the pore pressure is predicted. To verify the method, a test procedure was developed. The test procedure enabled systematic collection and processing of the drilling data to calculate the pore pressure prediction. The test procedure was then applied to industry data that was recorded at the surface. The industry data were composed of wells from different geographical regions. Two conclusions were deduced from the research. First, Mohr’s Theory indicates that the model is valid. Second, because of too much variation in the torque measurements the model cannot be proved and requires further investigation.
68

Two phase releases following rapid vessel failure

Bettis, R. J. January 1987 (has links)
No description available.
69

Hydrostatic pressure retainment /

Setlock, Robert J. January 2004 (has links)
Thesis (M.S.)--Ohio University, June, 2004. / Includes bibliographical references (p. 105-107).
70

Comparisons of sidelying and supine hemodynamic measurements in patients following coronary artery bypass surgery a research report submitted in partial fulfillment ... /

Cosgray, Yvonne. Graham, Robin. January 1986 (has links)
Thesis (M.S.)--University of Michigan, 1986.

Page generated in 0.0438 seconds