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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.
1

Mechanistic and inhibitory studies of S-ribosylhomocysteinase (LuxS)

Zhu, Jinge 17 May 2005 (has links)
No description available.
2

Economic and Hydraulic Simulation Models for Evaluation of Sediment Management in a Reservoir

Anari, Razieh 08 August 2022 (has links)
Reservoir sedimentation is a serious problem that threatens the water storage capacities across the world. Extending a dam's life requires adopting a new design and operational paradigm that focuses on managing the reservoir and watershed system to bring sediment inflow and outflow into balance by including reservoir sediment management facilities in dam and reservoir. However, the cost of methods that remove the sediment from reservoirs is usually prohibitive and is a serious factor preventing sustainable sediment management. This thesis considered a case study, Paonia Reservoir in Colorado, to investigate two aspects of reservoir operation, sediment management and economic assessment. The purpose is to determine how sediment management (sluicing using a low-level gate) effectively reduces sedimentation and whether this management is economically viable. The SRH-1D will be implemented to model the reservoir sedimentation, and RSEM evaluate it economically. The result comparison of current Paonia operation with hypothetical Paonia (added low-level gate) proved sluicing incoming sediment-laden flow effectively reduces sedimentation without interruption in the reservoir targeted functions like irrigating downstream. The deposited sediment volume could decrease more by monitoring the possible peak flow time and keeping the low-level gate open to pass high incoming flow downstream. This thesis applied RSEM to evaluate and compare the benefits and costs of continued sedimentation and eventual dam decommissioning (the existing Reservoir condition) to sediment management costs and benefits (hypothetical Paonia Reservoir). The results illustrated that sediment removal is advantageous because it contributed to decrease rate of decline of reservoir capacity, which made this capacity, and the associated instantaneous net benefits exceed those in the without sediment management alternative. The preserved benefits from sustainable sediment management offset the additional costs of incorporating sediment management. One of the key messages of this thesis is that incorporating sediment management into the planning and design phases of dam projects is essential for ensuring that the benefits of reservoir storage are sustained over the long term. This means fairness between current and future generations to enjoy the benefits of the facility while spreading the cost of ownership, operations, and maintenance over generations.
3

The Study of Carrier Relaxation in InN Thin Films

Lin, Guan-Ting 14 February 2008 (has links)
This theses investigates the carrier dynamics in Indium Nitride thin films grown on Si(111) substrates by means of ultrafast time-resolved photoluminescence (TRPL) apparatus. The study of energy relaxation shows hot phonon effective is prominent at photogenerated carrier concentration above 4¡Ñ10^18cm^-3 and become insignificant at carrier concentration below 7¡Ñ10^17cm^-3. Effective phonon emission times in the range of 116 to 23 femtoseoncds are obtained from the time evolution of carrier temperature assuming that the carrier-LO-phonon interaction is the dominant energy relaxation process. In the study of carrier recombination, the TRPL¡¦s are studied at the peak energies of the time-integrated PL at various lattice temperatures and are converted to decay rates with a rate equation, which includes the nonradiative and radiative coefficients, and a nonlinear dependence of PL intensity on the photogenerated carrier concentration. The increase with temperatures of the Shockley-Read-Hall rates implies that, in addition to the mid-gap defect states, a thermally activated trapping may become prominent at high lattice temperatures due to the increased kinetic energy gained by the carriers. The radiative recombination is the dominated recombination mechanism at low temperature but become trivial at high temperature. The fitted radiative coefficient at a temperature of 35K is consistent to the theoretical prediction. The Auger recombination exhibits a quadratic dependence on carrier concentration and becomes effective at high carrier concentration and at high temperature. The fitted Auger recombination coefficients are comparable to those of InGaAs and InGaAsP materials with band gap energies in the range of 0.6-0.8eV.
4

Participação dos canais “Transient Receptor Potential - TRP” nos efeitos cardiovasculares induzidos por carvacrol em ratos com Hipertensão essencial

Reis, Milena Ramos January 2015 (has links)
Submitted by ROBERTO PAULO CORREIA DE ARAÚJO (ppgorgsistem@ufba.br) on 2016-10-18T14:55:15Z No. of bitstreams: 1 Milena Ramos Reis.pdf: 2152638 bytes, checksum: 876fac844a4f4a8b22cb82e9cdeb5f3b (MD5) / Made available in DSpace on 2016-10-18T14:55:15Z (GMT). No. of bitstreams: 1 Milena Ramos Reis.pdf: 2152638 bytes, checksum: 876fac844a4f4a8b22cb82e9cdeb5f3b (MD5) / O carvacrol, um monoterpeno fenólico encontrado nos óleos essenciais de diversas plantas do gênero Origanum, já demonstrou causar hipotensão e vasodilatação em diferentes leitos vasculares de ratos normotensos, porém, seu efeito em ratos hipertensos ainda não foi elucidado. O objetivo deste estudo foi investigar os efeitos cardiovasculares do carvacrol em ratos espontaneamente hipertensos (SHR) e comparar com normotensos Wistar, utilizando ensaios farmacológicos in vitro (estudos funcionais e celulares) e in vivo. Nos ensaios funcionais in vitro, anéis de artéria mesentérica superior isolada de animais hipertensos e normotensos foram précontraídos com FEN (1μM) e o efeito de carvacrol (10-8-10-3M) foi observado. Em SHR, este monoterpeno induziu vasodilatação dependente de concentração (pD2=5,13 ± 0,05; Emáx=115,14 ± 5,46%; N=8) e, após a remoção do endotélio funcional, a potência da droga foi alterada significantemente (pD2=4,91 ± 0,05 N=9; p<0,01), sugerindo que a resposta vasodilatadora induzida por carvacrol, provavelmente, envolve uma via dependente e outra independente do endotélio vascular, porém, esta última parece ser a majoritária e, por isso, os ensaios seguintes foram realizados na ausência do endotélio vascular. Interessantemente, quando comparada com animais normotensos, a potência farmacológica de carvacrol foi reduzida significantemente (pD2=4,91 ± 0,05; N=9; p<0,05). Em anéis de ratos hipertensos, carvacrol reduziu o influxo de Ca2+ por canais Cav tipo-L, SOC e ROC, estes resultados foram semelhantes aos obtidos em ratos normotensos. Em ratos hipertensos, mas não em normotensos, a potência farmacológica do carvacrol em anéis pré-contraídos com FEN e na presença de diferentes inibidores de canais TRP (íon Gd3+, 10-5M; 2-APB, 10-6M ou 10-5M; BCTC, 2μM; 9-fenantrol, 10-5M; ou HC03003-1, 10-5M), foi reduzida em relação ao controle na ausência destes bloqueadores, sugerindo que os canais sensíveis à estes bloqueadores (TRPC1-7, TRPM2, M4 e TRPM8, TRPV1 e TRPA1), provavelmente, estão participando dos efeitos vasculares mediados por carvacrol e podem estar envolvidos no processo hipertensivo. Em estudos de patch-clamp em células de artéria mesentérica dispersas de ratos hipertensos, carvacrol (300μM) reduziu as correntes de entrada de Ba2+ por Cav tipo-L e este efeito foi semelhante em ratos normotensos. Além disso, em células de ratos hipertensos, o Mg2+ (2,5mM), bloqueador do TRPM6 e TRPM7, reduziu as densidades de ITRPM de entrada e saída, assim como carvacrol (100μM e 300μM), na ausência ou presença do 2-APB (100μM), bloqueador de TRPM7. A presença do 2-APB provocou inibição adicional nas densidades de ITRPM pelo carvacrol (100μM, mas não 300μM). Altas concentrações intracelulares de Mg2+ reduziram the magnitude of ITRPM7. Foi evidenciado que a ITRPM no controle é menor em ratos hipertensos que em normotensos. Estes dados obtidos e os relatados na literatura são sugestivos para provável inibição de ITRPM7 por carvacrol em células mesentéricas nativas. O efeito anti-hipertensivo do carvacrol foi avaliado por administração via orogástrica (50mg/kg/dia) durante 20 dias foi capaz de reduzir a pressão arterial média dos animais SHR tratados, no 20º dia do tratamento. O tratamento subcrônico com carvacrol não alterou os pesos cardíaco e corpóreo, nem a reatividade vascular. Em conclusão, esses dados sugerem que carvacrol possui atividade anti-hipertensiva em animais SHR, que pode ser devido ao seu efeito vasodilatador em anéis de artéria mesentérica superior isolada, provavelmente, por inibição do influxo de Ca2+ por Cav tipo-L, ROC, SOC e/ou canais TRPC1, 3 ou 6, além da inibição de correntes tipo-TRPM7 em miócitos mesentéricos.
5

Forecasting Inundation Extents in the Amazon Basin Using SRH-2D and HAND Based on the GEOGloWS ECMWF Streamflow Services

Edwards, Christopher Hyde 02 August 2021 (has links)
Floods are the most impactful natural disasters on earth, and reliable flood warning systems are critical for disaster preparation, mitigation, and response. The GEOGloWS ECMWF Streamflow Services (GESS) provide forecasted streamflow throughout the world. While forecasted discharge is essential to flood warning, forecasted inundation extents are required to understand and predict flood impact. In this research, I sought to expand GESS flood warning potential by generating inundation extents from streamflow forecasts. I compared Height Above Nearest Drainage (HAND), a method beneficial for flood mapping on a watershed scale, to a 2D hydrodynamic model, specifically Sedimentation and River Hydraulics – Two Dimension (SRH-2D), a method localized to specific areas of high importance. In three study areas in the Amazon basin, I validated HAND and SRH-2D flood maps against water maps derived from satellite SAR imagery. Specifically, I analyzed what features of an SRH-2D model were required to generate more accurate flood extents than HAND. I also analyzed the practicality of using SRH-2D for forecasting by comparing flood extents generated from simulating a complete forecast hydrograph to flood extents precomputed at predetermined, incremental flowrates. The SRH-2D models outperformed HAND, but their accuracy decreased at flowrates different than those used for calibration, limiting their reliability for forecasting and impact analysis. Based on this study, the key features necessary for a reliable SRH-2D model for forecasting include (1) a high-resolution DEM for an accurate representation of the floodplain, (2) correct representation of channel flow control, and (3) a channel bathymetry approximation and exit boundary rating curve that correctly predict water levels at a range of input flowrates. For forecasting practicality, the precomputed flood extents had accuracies comparable to the complete hydrograph simulations, showing their potential for estimating forecasted inundation extents. Future research should include (1) a more comprehensive analysis using existing SRH-2D models in areas with more bathymetry information and calibration data, (2) further assessment of the reliability of precomputed flood maps for forecasting applications, and (3) quantifying the effect of error in the streamflow forecasts on the accuracy of the resulting flood extents.
6

The intersectionality of women’s access to sexual and reproductive health services and information in Ismailia, Egypt

Elsayed, Reem January 2020 (has links)
Magister Artium (Development Studies) - MA(DVS) / Background: Sexual and reproductive health (SRH) is a right that should be guaranteed to every woman worldwide in order to have a healthy and safe sex life. In most Arab countries, including Egypt, there are different cultural, political, and religious factors that have contributed significantly to the manner that the society views and treats women’s bodies and sexuality. As a result, it is difficult to provide solid data and information to guide policymakers, policies, and to implement awareness and preventive programs. This thesis sought to address this gap by conducting a study looking at the intersectionality of women’s access to sexual and reproductive health services and information in Ismailia, Egypt. Methods: The relevant information was collected using qualitative methods. Semi-structured interviews were conducted with twelve married women and two key informant interviews with health professionals in the study area. Results: Intersectional theory was used to critically examine the various interacting factors such as gender, patriarchy, economic disadvantages, and other discriminatory systems that that can undermine women’s access to SRH information and services. The study revealed that married women suffer from the lack of access to proper SRH services and information. Conclusion: Married women’s experiences of accessing SRH services and information were affected by different intersecting factors. These factors are socio-economic, policy, cultural norms, power structure contexts, and privilege structures, and religious institutions. Recommendations were drafted to add more information and evidence related to Egyptian women and their SRH rights.
7

The effects of incorporating 0-500 m SRH into the Violent Tornado Parameter

Roberts, Jay Palmer 09 August 2022 (has links)
Between 2011-2021, violent tornadoes accounted for an average of 65% of all tornado-related fatalities. The Violent Tornado Parameter (VTP), created in 2018, attempts to address this forecast problem but has issues with false alarms. Storm Relative Helicity has historically been used in tornado forecasting. Recent studies have shown the 0-500 m effective layer SRH (ESRH) has skill in discerning significantly tornadic events from those that are not. This study explored the effects of incorporating 0-500 m ESRH into the VTP and issues relating to the parameter’s false alarm rate by examining RUC/RAP forecast soundings for 302 U.S. tornadic events (83 violent, 122 strong, 97 weak) from 2011 to 2020, along with test data from 2021. Overall, the study found that 0-500 m ESRH has skill in forecasting violent tornadoes, and that both the 0-3 km MLCAPE and 0-3 km Lapse Rate terms raised the parameter’s false alarm rate.
8

Flood Warning: A Generalized Approach to Forecast the Impacts of Flooding Events Using ArcGIS Pro, QGIS, and Python

Smith, Robert Evan 18 January 2022 (has links)
Floods are the most common global natural disaster, and 1 billion people live in floodplains worldwide adding to the impactful damage that inundation causes. Disaster managers strive to mitigate damages to their communities but need to know what the impact of a potential flood may be. GEOGloWS ECMWF Streamflow Services estimates forecasted streamflow around the world. These forecasted streamflow's can be used to create predicted flood extent maps using Height Above Nearest Drainage (HAND) or Sedimentation and River Hydraulics - Two Dimension (SRH-2D). Another method to obtain a flood map is using Setinel-1 satellite Synthetic Aperture Radar (SAR) imagery. Flood maps alone will not demonstrate the impact of the flood, but some exposure data will provide needed impact metrics. In this research, I wanted to produce a general geoprocessing method for stakeholders to compute flood impact metrics over any flood extent map using any exposure dataset. Additionally, I sought to create similar geoprocessing workflows in ArcGIS Pro, QGIS, and stand-alone Python script so that the stakeholders can choose the best suited method that correlates with their access and familiarity. The general geoprocessing workflow was tested using three different global exposure datasets (Agriculture, Infrastructure, and Population). The three different geoprocessing implementations were tested in three areas that are of concern in the greater NASA SERVIR organization using the same flood map and exposure datasets for each area. This research produced a feasible, sustainable, successful, generalized geoprocessing workflow that computes flood impact metrics from a flood map and global exposure datasets. The global datasets can be interchanged with higher resolution exposure datasets specific to an area of interest generating more accurate results. The three geoprocessing methods performed similarly. The results were slightly different when the exposure dataset was a raster file as the conversion from raster to vector format produced differences in rounding values and programming implementation. However, this research's findings are such that the three geoprocessing methods are comparable and that any of the three geoprocessing implementations will produce reasonably similar flood impact results. Ongoing work by the Brigham Young University (BYU) Hydroinformatics lab is to create a Tethys web application that will allow stakeholders to view the flood map and flood impact of areas of interest. Future work may include investigating the workflow workability on a global scale, discovering and implementing global exposure data sources of better resolution, researching more data metrics that can contribute to a more robust flood impact results, and increasing the accuracy of flood impact results when compared among ArcGIS Pro, QGIS, and Python.
9

Subjektive Gesundheitseinschätzung gesunder Frauen nach der Geburt eines Kindes / Self-rated health (SRH) and health-related quality of life (HRQoL) in women after childbirth

Schäfers, Rainhild 27 September 2011 (has links)
In Deutschland ist eine zunehmende Kinderlosigkeit zu beklagen (Statistisches Bundesamt 2009). Die Ursachen hierfür werden primär vor dem Hintergrund der Unvereinbarkeit von Berufstätigkeit und Mutterschaft diskutiert (Schrupp 2008). Aus lerntheoretischer Perspektive wären subjektiv empfundene gesundheitliche Ein-schränkungen von Frauen nach der Geburt eines Kindes als weitere Ursache denkbar. Über die subjektiven Gesundheitseinschätzungen von Frauen im geburtshilflichen Kontext ist jedoch nur wenig bekannt. Vereinzelt finden sich Hinweise, dass Frauen ihre subjektive Gesundheit (SGH) nach der Geburt ihres Kindes trotz bestehender Morbidität sehr positiv bewerten (Bauer 2011, Schytt et al. 2005, Borrmann 2005). Ziel der Studie ist es die subjektive Morbidität, die SGH sowie die gesundheitsbezogenen Lebensqualität (GHLQ) gesunder Frauen acht Wochen und sechs Monate nach der Geburt eines Kindes zu erfassen und die Faktoren zu ermitteln, die sich beeinflussend auf SGH und GHLQ auswirken. Methode: Retrospektive, longitudinale Kohortenstudie. Basis der Sekundäranalyse bilden Daten von 1029 Erst- und Mehrgebärenden, die im Rahmen einer multizentrisch angelegten, prospektiven Interventionsstudie zum Versorgungskonzept Hebammenkreißsaal an der Hochschule Osnabrück unter Förderung des Bundesministeri-ums für Bildung und Forschung (FKZ 01 GT 0616) zum Zeitpunkt der Geburt (t0) sowie acht Wochen (t1) und sechs Monate (t2) nach der Geburt erhoben wurden. Zur Ermittlung der SGH wurde der SF-1 angewendet. Die Operationalisierung der GHLQ erfolgte über die standardisierte körperliche und die standardisierte psychische Summenskala des SF-36. Ergebnisse: Gut die Hälfte der Studienteilnehmerinnen bewertete ihre SGH zu t1 und t2 besser als gut, wobei Erstgebärende gegenüber Mehrgebärenden signifikant häufiger diese positive Einschätzung vornahmen (p<.007). Neben einer Reihe von Faktoren, die in keinem unmittelbaren Zusammenhang mit der Geburt stehen, zeigten sich geburtsspezifische Aspekte als signifikante Einflussgrößen. In der Gruppe der Erstgebärenden er-höhte sich bei Vorliegen geburtsverletzungsbedingter Beschwerden die Chance auf eine beeinträchtigte SGH zu t1 signifikant (OR 1.68, [95% KI 1.04-2.71]; p=.035). In der Gruppe der Mehrgebärenden erwies sich ein nega-tives Geburtserleben zu t2 als signifikante Einflussgröße für eine beeinträchtigte SGH (OR 7.66, [95% KI 2.17-26.99]; p=.002). Hinsichtlich der GHLQ konnten ebenfalls geburtsspezifische Aspekte als Einflussgrößen ermit-telt werden. Zu t1 erhöhten in der Gruppe der Erstgebärenden geburtsverletzungsbedingte Beschwerden die Chance auf eine verminderte GHLQ um fast das Dreifache (OR 2.83, [95% KI 1.63-4.93]; p<.001). Ein negati-ves Geburtserleben verdoppelte die Chance auf eine verminderte GHLQ in dieser Gruppe (OR 2.09, [95% KI 1.19-3.65]; p=.010). In der Gruppe der Mehrgebärenden zeigte sich das negative Geburtserleben ebenfalls als signifikante Einflussgröße (OR 3.93, [95% KI 1.14-13.53]; p=.030). Dies allerdings erst zu t2. Insgesamt konn-ten in einzelnen Subskalen des SF-36 signifikante Abweichungen zwischen der landes-, alters- und geschlechts-spezifischen Normstichprobe und dem Studiensample festgestellt werden. Schlussfolgerung: Geburtsverletzungsbedingte Beschwerden und ein negatives Geburtserleben beeinflussen die SGH und GHLQ nachhaltig. Mit dem Anspruch einer qualitativ hochwertigen geburtshilflichen Versorgung gilt es die subjektiven Gesundheitseinschätzungen von Frauen nach der Geburt eines Kindes standardisiert zu evalu-ieren. Um Ceiling-effekte zu vermeiden müssen die in anderen Bereichen bisher üblichen Erhebungsverfahren für den geburtshilflichen Kontext modifiziert werden
10

Towards an Understanding of Heterosexual Risk-Taking Behaviour Among Adolescents in Lusaka Zambia

Masheke Kaimba, Christine Kufanga January 2014 (has links)
This thesis investigates the underlying factors behind sexual risk-taking and non-risk-taking behavior with regard to Sexual Reproductive Health (SRH) among adolescents in Lusaka, Zambia. The Qualitative Approach was used for data collection and analysis and using the theory of Social Construction, the author explains how different contexts and aspects in the Zambian Society, that is Traditional, Socio-economic, Political, etc., influence the sexuality or sexual behavior of young people in Zambia. Hermeneutics was used to interpret the meanings in the texts/transcripts acquired through data collection and from the author’s knowledge and understanding of the Zambian historical and cultural contexts within which the participants of the research were constructed. Max Weber’s Ideal Type concept was also used to explain that each young individual’s sexual behavior is uniquely constructed by societal aspects. It explains how that the discourses of these different aspects of society impact on young people individually causing them to be either Sexually Risk-taking or Non Sexually Risk-taking. Either tendency depends on whether the societal aspect that has most the dominating influence on a given individual's life is a Power factor (causing them to rationally think their way into Non Sexually Risk-taking behavior) or a Risk factor(causing them to rationally think their way into Sexually Risk-taking behavior). The author of this thesis introduces a new Model for Social Construction of Adolescent Sexuality with regard to Risk-taking. She uses it to explain how it is either power factors or risk factors that can have a greater impact on an individual's thinking, causing them to have either sexual risk-taking or non-sexual risk-taking behavior. The author concludes that the extent to which unsafe sex among the Zambian adolescents constitutes a product of interacting and/or main discourses in relation to mainly Traditional aspect risk factors, varies from person to person depending on the strength of given risk factors over any power factors that may be at play in an individual's life.

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