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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.
691

Escherichia coli produtora de toxina de Shiga em carne moída comercializada na cidade de São Paulo, SP / Shiga toxin-producing Escherichia coli in ground beef at retail level at Sao Paulo city, Brazil

Adriana Lucatelli 24 February 2012 (has links)
Apesar de Escherichia coli O157:H7 ainda ser considerado o principal sorotipo envolvido com surtos de enfermidades veiculadas por alimentos entre as E. coli produtoras de toxina de Shiga (STEC), outros sorogrupos estão ganhando importância, como O26, O45, O103, O111, O121 e O145, que estão sendo denominados de \"Top Six STEC non O157\". As STEC são responsáveis por sintomas que variam de uma simples diarreia até diarreia sanguinolenta, que pode evoluir ainda para síndrome hemolítica urêmica e púrpura trombótica trombocitopênica, podendo ocasionar danos crônicos como falência renal e levar a óbito. Para tanto, apresentam diversos fatores de virulência, entre eles, as toxinas de Shiga (Stx) ou verotoxinas (Vtx). Os veículos destes micro-organismos são diversos alimentos, sendo o principal deles, as carnes moídas. Apesar da importância da carne moída como veículo transmissor de STEC, pouco se conhece sobre a sua presença nesse alimento comercializado na cidade de São Paulo, SP. Sendo assim, o objetivo deste trabalho foi pesquisar a presença de STEC em carne moída comercializada no varejo da cidade de São Paulo e caracterizar tais isolados quanto à presença dos seguintes fatores de virulência: stx1, stx2, eae e ehx. Foram coletadas 248 amostras em diferentes bairros da cidade de São Paulo. Para a detecção de E. coli sorogrupo O157 foi utilizada a metodologia ISO 16654 e para a detecção dos sorogrupos O103, O111, O145 e O26 foi empregada a metodologia descrita pelo Surveillance Group for Diseases and Infections of Animals (NRM 006). Uma amostra de carne moída (0,4%) apresentou o micro-organismo pesquisado. A identificação genotípica e bioquímica caracterizou esse isolado como STEC O157:H7, portador de todos os fatores de virulência pesquisados: stx1, stx2, eae e ehx. Foi constatada, também, a expressão das proteínas stx em células Vero. Esse é o primeiro relato da presença de E. coli O157:H7 produtora de toxina de Shiga em carne moída no Brasil. / Although Escherichia coli O157:H7 is still considered the most important serotype involved in foodborne disease outbreaks among Shiga toxin-producing E. coli (STEC), other serogroups are receiving more attention such as O26, O45, O103, O111, O121 and O145, that are being called the \"Top Six STEC non O157\". STEC are responsible for symptoms ranging from simple diarrhea to bloody diarrhea, which can further evolve to hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, which may cause damage such as chronic renal failure and lead to death. To do so, they have several virulence factors, including the Shiga toxins (Stx) or verotoxins (Vtx). The vehicles of these microorganisms are many foods, most notably, the ground beef. Despite the importance of ground beef as a vehicle for transmitting STEC, little is known about their presence in this kind of food sold in São Paulo, SP. Therefore, the objective of this study was to investigate the presence of STEC in ground beef sold at retail level in Sao Paulo city and characterize the isolates for the presence of the following virulence factors: stx1, stx2, eae and ehx. 248 samples were collected in different districts of Sao Paulo city. For the detection of E. coli O157 serogroup the methodology ISO 16654 was used and for the detection of serogroups O103, O111, O145 and O26 the methodology described by the Surveillance Group for Diseases and Infections of Animals (NRM 006) was used. One sample of ground beef (0.4%) showed the presence of the microorganism studied. The biochemical and genotypical identification characterized this isolate as STEC O157:H7, carrying all of the investigated virulence factors: stx1, stx2, eae and ehx. The expression of stx proteins in Vero cells was also observed. This is the first report on the isolation of E. coli O157:H7 Shiga toxin-producing from ground beef in Brazil.
692

Formal Organization in Ground-bass Compositions

Stevens, Bryan 08 1900 (has links)
This thesis examines formal organization in ground-bass works. While it is true that many or even most works of the ground-bass repertoire are variation sets over a ground, there also exist many ground-bass works that are not in variation form. The primary goal of this thesis is to elucidate the various ways in which such non-variation formal organizations may be achieved. The first chapter of this work discusses the general properties of ground basses and various ways that individual phrases may be placed in relation to the statements of the ground. The second chapter considers phrases groupings, phrase rhythm, and the larger formal organizations that result. The third chapter concludes this study with complete analyses of Purcell’s “When I am laid in earth” from Dido and Aeneas and Delanade’s “Jerusalem, convertere ad dominum Deum tuum” from his setting of the Leçons de ténèbres.
693

Development and Application of A SERS Needle for One-step Multi-phase Analysis

Chen, Haoxin 25 October 2018 (has links)
Surface-enhanced Raman spectroscopy (SERS) is an emerging and sensitive technique in food analysis providing advantages of rapid detection, simple sample preparation and on-site detection capability over GC and LC methods. Most SERS applications focus on detecting trace amount of analyte in liquid as an alternative approach to HPLC. Herein, we invented an innovative SERS-active needle which is composed with an injection needle and a gold-nanoparticles coated fiber inside the injection needle. The gold nanoparticles-coated fiber was fabricated by reducing gold (III) on a chemically etched stainless wire. The SERS needle can be used to insert into the headspace and liquid sample for simultaneous multiphase sample detection, or a soft tissue like a tomato fruit to detect the analyte inside of the tissue with minimum invasion. Using this needle, we can detect as low as 5 ppb of fonofos in the headspace of water and apple juice samples, compared with the dip method, which cannot detect lower than 10 ppb in water and 50 ppb in apple juice. The SERS needle was also applied in real time pesticide translocation study to monitor internalized thiabendazole in tomato fruit after root uptake. The SERS needle detected thiabendazole inside tomato fruits 30 days after the pesticide exposure in a hydroponic planting environment. Moreover, realizing the advantage of detecting volatile components in the headspace of food sample, we applied the SERS needle in a ground beef spoilage study to detect the spoilage biomarkers in the headspace of the raw beef. As a result, the SERS needle detected volatile spoilage compounds produced by bacteria Lactobacillus. Overall, this invention opens a new field of SERS strategy for broad analytical applications.
694

Geodetic constraints on the present-day motions of the Arabian plate and the southern Red Sea region

Viltres, Renier 11 1900 (has links)
The present-day kinematics and deformation of the Arabian plate and the southern Red Sea region involves interaction of tectonic and non-tectonic processes including plate subduction, continental collision, seafloor spreading, intraplate magmatism, continental transform faulting, microplate rotation, hydrological loading cycles, and anthropogenic activity. Therefore, good constraints on the rates and directions of relative plate motion, plate boundary locations, and rheological properties in the area are essential to assess seismic and volcanic hazards in the region. In this thesis, I combine Global Navigation Satellite System (GNSS) measurements from over 200 stations with kinematic block modeling to provide updated estimates of the present-day motions of the Arabian plate and the southern Red Sea region. Using the non-rigid residual motions and changes in GNSS station baselines, I provide quantitative constraints on the internal deformation for the Arabian plate at different spatial scales. In addition, I use the GNSS station response to seasonal water exchange in the Red Sea to make inferences of the lithospheric elastic properties beneath Arabia. The GNSS-derived velocity field indicates coherent motion of both the Danakil block in the southern Red Sea and the Arabian plate at present. Current motions in the southern Red Sea region, however, are inconsistent with previous interpretations and require an additional plate boundary in the area. My updated fault slip rates improved earlier estimates limited by the number and spatial distribution of GNSS stations, particularly for the Arabian-Indian plate pair, for which slower right-lateral strike-slip motions are predicted. Non-rigid residual velocities within the Arabian plate interior indicate that large-scale internal deformations are compensated internally. However, at a smaller scale, I identify several localities accommodating significant strain, mostly related to anthropogenic activity. Ground response to surface mass loading associated with water transport in the Red Sea suggests that the Earth’s elastic structure beneath the Arabian plate is 20% to 30% less stiff than global averaged (i.e., AK135-F planetary model). Still, the lithosphere beneath both the Danakil block and the Arabian plate remains strong despite being affected by significant faulting and magmatism associated with the Nubian-Arabian-Eurasian plate interaction.
695

Utformning av ett nationellt kunskapsstöd för primärvården i Sverige : Ett kunskapsstöd för att möjliggöra mer jämlik vård / The layout of a national knowledgebase for the primary health care in Sweden : A knowledgebase for more equal health care

Blom Kall, Jennie January 2016 (has links)
Kunskapsbaserade stöd får en allt mer central roll inom vård och omsorg. De viktigaste rekommendationerna som idag finns är de nationella riktlinjerna som Socialstyrelsen har tagit fram. Som det ser ut idag används dessa i olika utsträckning inom primärvården runt om i Sverige och många landsting har sina egna varianter på kunskapsstöd. Därför ska ett nationellt kunskapsstöd utvecklas som alla kan ta del av för möjliggörande av att patienten får den bästa möjliga vården, vilket också ska leda till en mer jämlik vård i hela Sverige. I denna studie samlades information in om hur ett sådant stöd skulle kunna utformas via 8 intervjuer med läkare där resultatet sedan användes för att utforma en enkät som 16 personer inom primärvården från olika landsting besvarade. Enkäten behandlade frågor om hur de ville att informationen skulle presenteras och vilka huvudrubriker de ansåg vara viktigast i ett kunskapsstöd. Det visade sig att Behandling var den viktigaste huvudrubriken, att lättanvänt och pålitligt är viktiga egenskaper hos ett kunskapsstöd och att informationen ska presenteras kortfattat så att läkaren snabbt kan få en överblick av informationen då läkare ofta har tidsbrist.
696

An Evaluation of The Performance and Comparative Cost of Ground-mounted and Rooftop Mounted Solar Photovoltaic Systems

Leighton, Michael 04 February 2021 (has links)
In South Africa, there is an increasing interest in installing rooftop mounted solar photovoltaic systems. However, financing the photovoltaic systems causes most interest to be abandoned, largely due to the cost required to replace a building's asbestos roof. An alternative solution to replacing an asbestos roof is to install a ground-mounted photovoltaic system, which is more costly compared to a rooftop mounted system. This study aims to determine if a ground-mounted or a rooftop mounted solar photovoltaic system is the most financially feasible solar photovoltaic configuration. In this study three photovoltaic systems were analysed, all of which are installed in Atlantis, Western Cape (WC). Since all three systems are in the same area, they are all exposed to the same metrological conditions, allowing for identical energy generation potential. Two of the photovoltaic systems are ground-mounted systems located respectfully at the South African Renewable Energy Incubator (SAREBI) and at Stripform Packaging. The third system is a rooftop mounted system located at SA Tyre Recyclers. The photovoltaic system at SAREBI is a 9.75 kWp system consisting of 30 Canadian Solar CS6U-325P modules, one Schneider Electric 20 kW inverter, a tilt angle of 15° and an azimuth angle of -19°. The photovoltaic system at SA Tyre Recyclers is a 231 kWp system consisting of 700 JA Solar JAP72S-01-330-SC modules, 7 SolarEdge 27.6 kW inverters, a tilt angle of 13° and an azimuth angle of 22°. The photovoltaic system at Stripform Packaging is a 20.1 kWp system consisting of 60 Canadian Solar CS6U-335P modules, one SMA 20 kW inverter, a tilt angle of 15° and an azimuth angle of 46°. To achieve the aim of this study, the performance of each of the solar photovoltaic systems was examined, by comparing their annual specific yield. After which the technical aspects and differences of each of the photovoltaic systems were explored, to illustrate how each of the systems differ technically and how each system can be improved. Finally, the comparative cost of each of the solar photovoltaic systems was examined by analysing the levelized cost of energy (LCOE) and the payback period for each of the photovoltaic systems. The results demonstrated that from an annual specific yield perspective, the ground-mounted configuration was the best performing, whilst from a financial perspective, the rooftop mounted configuration had the lowest levelized cost of energy (LCOE) and payback period. However, installing a ground-mounted system is more financially feasible than replacing an asbestos roof and then installing a rooftop mounted system. In conclusion, by fully understanding the performance, payback period and levelized cost of energy, a clear understanding of potential risk can be determined, thus making the installation of photovoltaic systems more appealing for financiers. It is recommended that this study be repeated in a manner in which each of the photovoltaic system configurations are constructed consisting of all the same photovoltaic components, measuring equipment, tilt and azimuth angles. All of which would result in two identical photovoltaic systems where one is installed on a rooftop and the other installed on the ground. Once the two photovoltaic system configurations are equal in all aspects, an accurate comparison to determine which configuration is the most optimal performer and which is the most financially viable will be possible.
697

Sinkhole formation due to subsurface erosion above undermined ground

Breyl, Jacobus January 2019 (has links)
In November 2016, 38 sinkholes formed due to subsurface erosion above undermined ground on Donkerhoek farm near Sasolburg. The fact that the sinkholes formed more than 24 years after mining in the area ceased, emphasised the need for a method to predict the likelihood of sinkhole formation due to subsurface erosion. This is especially relevant for mining houses required to quantify their mine closure risks. The purpose of this study was to investigate the mechanisms and soil properties involved in the formation of the 38 sinkholes on Donkerhoek farm through a fieldwork and laboratory testing programme and develop a method to predict the likelihood of sinkhole formation. Three areas were selected for test pit excavation: an area with large sinkholes, one with small sinkholes and a third with no sinkholes but with a history of subsidence crack formation. The same mechanism of sinkhole formation was observed in both the large and small sinkhole areas: at the soil-rock interface, soil was being eroded into a subsidence crack in the rock, resulting in an upwards migrating cavity and the eventual formation of a sinkhole on surface when the cover over the cavity collapsed. This was the first time that this mechanism was observed in the Sasolburg area, having previously only been identified in the Secunda area. The laboratory tests, carried out on samples obtained during the fieldwork, included foundation indicator, dispersivity, XRF and XRD, soil water retention curves, consolidated undrained triaxial and permeability tests. By comparison of the results from the different study areas, it was concluded that the larger sinkholes form in areas with highly dispersive soils, higher clay content, higher swell potential and a higher capacity to retain suctions when wetted. The following soil properties and factors were identified as the main contributors to sinkhole formation: • The strength of the lid, which is highly influenced by the unsaturated behaviour of the lid material. The lid strength determines the sinkhole diameter; • The erodibility of the material which is influenced by dispersivity and the material obtaining a crumb structure due to desiccation; • The activity of the soil, which influences the volume changes during drying and thereby the width and depth of desiccation cracks; and • The thickness of the soil layer overlying the rockhead. With the critical factors identified, the Van der Merwe method to predict sinkhole size was used as basis to develop an index method to predict the likelihood of sinkhole formation due to subsurface erosion above undermined ground. The method considers combinations of the following factor groups to express a high or low likelihood of the formation of large or small sinkholes in a particular area: • The strength of the lid material, mainly influenced by the unsaturated behaviour of the soil; • The capacity for cavity formation (CCF), which combines the dispersivity, erodibility and activity of the soil; and • The influence of the thickness of the soil layer overlying the rock, evaluated by calculating the ratio between crack width in the rock and the soil layer thickness. / Dissertation (MEng)--University of Pretoria, 2019. / Civil Engineering / MEng (Geotechnical Engineering) / Unrestricted
698

"Perceived neighborhood walkability" and physical activity in four urban settings in South Africa

Isiagi, Moses 24 February 2020 (has links)
Introduction. In Africa, studies on the associations between the perceived neighbourhood walkability and physical activity, particularly, by socio-economic status (SES) remain scarce. This study explores these associations by validating the Neighbourhood Environmental Walkability Scale (NEWS-Africa) in an urban setting of South Africa to gain a better understanding of the construct of neighbourhood “walkability”. Methods. A convient sample of residents from four suburbs in urban metropole (n=52, 18-65yr, 81% women) in the Western Cape Province, South Africa (viz. Langa, Khayelitsha, Pinelands and Table View) were recruited through invitations following community gatherings and church services. Measures were obtained on perceived neighbourhood walkability, self-reported and measured physical activity and socio-economic status. Langa and Khayelitsha represented two primarily low-SES townships, whereas Pinelands and Table View represented suburbs of a higher-SES. Participants completed the 76-item (13 subscales) NEWS-Africa survey by structured interviews and reported weekly minutes of walking for transport and recreation using items from the International Physical Activity Questionnaire. Objective data on physical activity was collected using accelerometers, and ground-truthing was used to assess the neighbourhood environment using global information systems (GIS) in a 1000m buffer around each geocoded household. The research was carried out in three parts: 1) Evaluating the reliability and construct validity of the NEWS-Africa instrument between the two-SES groups. 2) Examining some of the walkability constructs and subscales of the NEWS-Africa instrument using GIS and ground-truthing, and the extent to which the SES of communities influenced these associations. 3) Examining the differences in self-reported physical activity (domains), measured physical activity (MVPA) when groups are divided according to SES, GIS walkability (1000m buffers) and if the data support the notion of utilitarian walking in low SES groups, irrespective of the built environment attributes. Results. For the combined-SES groups, the test-retest reliability indicated a good reliability with 10 out of the 13 scales of the NEWS-Africa being significantly and positively correlated. The Spearman’s correlations ranged from (rs = -0.43, p=0.00 to rs = 0.79, p=0.00). For construct validity of the NEWS -Africa instrument against self-reported physical activity, only three scales were related to walking for transport: Neighbourhood surroundings scale (rs= -0.34, p=0.01), Safety from Traffic scale (rs =0.34, p< 0.05) and people in the low-SES and combined SES perceived public bus/ train stops to be nearer than they actually were (rs =-0.50, P< 0.05). Of the 13 scales of the NEWS-Africa questionnaire, 6 were significantly correlated to GIS-measured walkability index parameters. The Roads and walking paths scale was positively associated with GIS-measured walkability (rs = 0.3), and the Stranger danger scale was negatively associated with GIS-measured walkability (rs = -0.4). When we considered GIS-measured Land use mix, 3 of the NEWS- Africa scales were correlated (For the entire sample, the scales including Places for walking, cycling and playing overall scale (rs = 0.3), and Neighbourhood surroundings scale (rs = 0.3), were positively associated respectively). Conversely, Stranger danger scale was inversely correlated (rs = -0.6). Intersection density measured with GIS was significantly and positively associated with the Roads and walking paths scale for all groups combined (rs = 0.3). For GIS-measured walkability, self-report physical and measured physical activity, there were no associations in any of the domains for self-reported physical activity within the 1000m buffer for all groups. However, for the objectively measured physical activity in the 1000m buffer, vigorous physical activity (rs = -0.39) was inversely associated with intersection density in the low-SES and moderate (rs = -0.29) and total MVPA (rs = -0.31) were inversely associated with Intersection density in the high SES. Conclusions: The overall results of the current study across all chapters generally show a mismatch between the perceived and objectively-assessed built environment, particularly in low-income communities. Furthermore, in low-SES communities, we failed to show the expected relationships between attributes of the built environment and physical activity, suggesting that physical activity in these communities is more utilitarian in nature, and as such, may not be as influenced by aspect of the built environment. In summary, the data suggest that the environment (including crime rates, poor access to physical activity facilities and public transportation predominantly made by buses) has less of an association with physical activity in LMICs and more disadvantaged communities, where physical activity is used for utilitarian, rather than recreational purposes. This study stemmed from the need to broaden research on the relationship between the built environment and physical activity, considering walkability constructs. These findings also suggest that the definition of the construct of walkability be re-examined, in relation to low SES settings.
699

Teachers` Perception of Outdoor Learning : Benefits and Challenges of Outdoor Learning

Ayeme, Bukola January 2020 (has links)
Outdoor learning has become very visible in recent times ,it is seen in different public medias such as magazines, on television, on various websites on internet, in the press and on public notice boards in different countries, accompanying different advertisements displaying a healthy lifestyle especially in early years of studies ( preschool ).The author seeks to address the perception of  Erasmus project “Dehors ” teachers`  experience outdoor, focusing majorly on the benefits and difficulties that these preschool teachers face while teaching outdoors. Furthermore, teachers are known to be role-models for their students and their opinion about their jobs matters a lot in displaying their duties as educators. Preschool children aged 0-6 years spend more time in school more than home, at least a minimum of five days in a week so ultimately attitudes of teachers largely have a positive or negative effect on  school children.  The aim of the present dissertation project is to explore how the teachers perceive outdoor learning based on their experiences outdoors. This study explored the components that characterize teachers` perception of outdoor learning. This research includes two set of interviews which were used to investigate both teachers` outdoor activities performed in Latvia and Swedish preschools. Outdoor learning has made a distinctive difference between the traditional learning approach of “stand and deliver” model which has systematically been changed to “guide on the side” model which educationalist view as a good method of impacting knowledge to learners, instead of giving knowledge as it was practiced before but in recent times, outdoor leaning processes helps to create an atmosphere for co-learning and not an isolated endeavours which is gradually  been replaced by outdoor learning approach of  “tell me and I will forget with “show me and I will remember”. These results provided a great insight on teachers` experiences of outdoor learning in the nature and on asphalt. It can be concluded that outdoor learning approach can be adaptable in the Latvian and Swedish contexts in promoting the development of preschool teachers therefore, there is a need for further research to promote effectiveness of outdoor teaching in Latvia and  Swedish preschools.
700

Optimization of Ground Source Cooling Combined with Free Cooling for Protected Sites

Johansson, Eric January 2012 (has links)
Ground source cooling is commonly used for cooling of electronics in protected sites. Sometimes the boreholes are combined with free cooling from the air using a dry cooler to reduce the amount and length of the boreholes, which is the biggest part of the costs. The dry cooler can have two different running modes. In unloading mode the dry cooler is started at a certain temperature and the fans are slowed down at low temperatures so that the cooling power never exceeds the cooling demand. The extracted cooling is used to unload the boreholes. In recharging mode the dry cooler is started at a certain temperature and is operating at full capacity below this temperature. The excess cooling that is extracted in this mode is used to recharge the boreholes. The numerical simulation tool COMSOL Multiphysics was used to evaluate the borehole performance. The software can simulate tilted boreholes with good accuracy and makes it possible to adjust the geometry in any desired way. In this thesis, the performance of a 100 kW ground source cooling system is evaluated for a number of cases both with and without dry coolers in different running modes and sizes. The best solution in respect to life cycle cost, technical feasibility and environmental impact is chosen to be an unloading case with a dry cooler with 100 kW capacity at 8 °C. Using only boreholes gives less carbon dioxide emissions but much higher costs.

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