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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

A critical evaluation of the causes of carcass condemnations in a South African cattle abattoir

Tlhapi, Petrus Thabo January 2013 (has links)
This study was conducted to investigate the causes and the effects of breed, gender and season on carcass condemnations post-mortem in a large South African abattoir. Condemnation of carcasses as a results of animal diseases and conditions has been identified as a problem in the South African beef industry, but the causes and extent of carcass condemnations have not been studied in detail. The importance of cattle management during transportation and pre-slaughter is generally appreciated, but a better understanding of the influence of breed, gender and season on the prevalence of carcass condemnations can help to improve slaughter management at large abattoirs. Diseases and conditions evaluated during this study were parafilaria, bruising, soiling, fever, peritonitis and pleuritis, abscesses, measles, oedema and intramuscular haemorrhage. Breeds of cattle slaughtered were Friesland, Bonsmara, Brahman, Angus, Afrikander, Hereford and Nguni cattle, grouped as males and females, and the seasonal effects investigated were confined to Autumn, Winter and Summer combined with Spring as it was not easy to distiquish between the two. Data was collected in a Grade A abattoir in South Africa in 2010. The experimental design involved 42 combinations based on their effects and interactions namely 7 breeds x 2 genders x 3 seasons. The model used in this procedure was based on the presence of conditions = (Intercept) x i x j x k where i~breed, j~gender and k~season. The binary response variable was the presence (value = 1) or absence (value = 2) of the respective condition. Overall, the significant order and extent of causes of bovine carcass condemnations evaluated in this particular abattoir during the period of study were peritonitis and pleuritis at 2.49%, soiling 2.33%, bruising 2.10%, parafilaria 0.54%, while other conditions had a negligible effect. Almost half of these carcass condemnations were due to soiling and bruising, which can be addressed by implementing better abattoir management and better management during transportation. Peritonitis and pleuritis were prevalent to a greater degree in Autumn, Soiling in Summer, bruising in winter and parafilaria more prevalent in Summer as well. Bonsmara bulls were more affected by peritonitis and pleuritis, soiling, bruising and parafilari compared to other breeds.. Overall breed, gender and season influenced carcass condemnations in large South African abattoir It is suggested that proper dehorning should be done at an early stage, especially in bulls of breeds like Bonsmara, Nguni, Friesland and Hereford, which predispose cattle to bruising which increases the number of carcass condemnations. Steps should be taken (i.e. proper handling techniques should be applied) to avoid injuries which may lead to internal bleeding, and eventually bruises (most probably due to fighting during transportation or in lairage), that can be avoided by using improved and upgraded facilities which include enough space per animal. In case of soiling, well-trained slaughter personnel, cattle handlers and cleaners should be hired to prevent bile and soil contamination during evisceration and to avoid mud or manure contamination durinmg lairage. It is recommended that employees be trained to help reduce the high rate of carcass condemnations. Breeds like Bonsmara and Brahman were more susceptible to peritonitis, pleuritis and parafilaria, so treatrment programmes are advisable for these breeds, especially those from regions where these conditions or diseases are more prevalent. / Dissertation (MSc Agric)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted
2

Efeito da sazonalidade nos níveis de atividade física em adultos

Bressan, Ana Weigert 26 August 2008 (has links)
Made available in DSpace on 2015-03-05T20:05:13Z (GMT). No. of bitstreams: 0 Previous issue date: 26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Não há suficiente consistência na literatura sobre mudanças nos níveis de atividade física (NAF) de acordo com as variações climáticas. Nós realizamos um estudo para avaliar o efeito da sazonalidade nos NAFs em adultos de Porto Alegre e região metropolitana. Foi um estudo longitudinal com uma amostra de conveniência de 120 pessoas de 20 a 69 anos. As pessoas foram avaliadas em dois períodos do ano de 2007: no verão e no inverno. A atividade física foi avaliada usando a seção de atividade física no tempo de lazer e como forma de deslocamento do International Physical Activity Questionnaire (IPAQ). As variáveis socioeconômicas e demográficas foram avaliadas por meio de um questionário padronizado. As análises foram estratificadas por sexo, idade, escolaridade, nível socioeconômico e Índice de Massa Corporal (IMC). Das 120 pessoas, 71% eram mulheres, 59% tinham de 20-40 anos, a média de idade, 61% tinham 12 anos ou mais de escolaridade, 83% pertenciam à classe A e B e a razão de sobrepeso/ peso normal foi 1:2,5. / There are no consistent findings about the effect of weather and season changes on the physical activity levels. We conducted a study to evaluate seasonal effects on physical activity levels among adults living in Porto Alegre and metropolitan region, Southern Brazil. The study design was longitudinal with a convenience sample of 120 adults, aged 20 to 69. Visits were carried out in two periods of the year 2007: summer and winter. Physical activity was evaluated using the leisure-time and transport-related physical activity sections of the International Physical Activity Questionnaire (IPAQ). Socioeconomic and demographic characteristics were obtained by standardized questionnaires. Analyses were stratified by gender, age, education, socioeconomic and Body Mass Index (BMI). A total of 120 people were interviewed, 71% were women. Most people (59%) were in the 20-40 years age group, 61% had more than 12 years of education and belonged to A and B socioeconomic levels (83%). Overweight / normal weight ratio was 1
3

Numerical and experimental dynamic analyses of the Vega Pedestrian bridge including seasonal effects

Hallak Neilson, John Peter January 2019 (has links)
As timber structures become increasingly relevant and sought after – since they enable improvements in building time while reducing a structure’s life cycle impacts – streamlining their design can have meaningful economic and environmental implications. For timber footbridges, its design is frequently governed by serviceability criteria linked to excessive vibrations. To address this in design, it is necessary to correctly characterize the structure’s dynamic properties and understand what the leading parameters in its behaviour are. This thesis studied an existing timber arch footbridge, aiming to evaluate its dynamic behaviour both with experimental measurements and with theoretical models. The influence of temperature change over different seasons was considered, particularly around its effect on the asphalt layer – whose stiffness is highly correlated to temperature. The experimental results showed high correlation between temperature and natural frequencies: a variation of +21°C reduced the natural frequency for the 1st transverse mode of the deck by as much as 30.6% while the 1st vertical mode was reduced by 17.7% (variation of 0.029Hz/°C). The damping ratio was also measured, though a definitive correlation between its value and temperature was not identified. This change in behaviour cannot be explained by the influence of the asphalt layer alone however, as there is a high degree of uncertainty around many other components of the bridge and their interactions, such as the connections. Thus, to fully characterize the influence of each component with changing temperature, further experimental tests would have to be performed, or simpler structures with fewer connections should be considered. In designing a new structure, considering the asphalt layer as an added mass is a straightforward way to treat this material at the most critical condition (i.e. no contribution to stiffness). This strategy lead to sufficiently similar results between the computational model and the experimental results at warm temperatures. The asphalt stiffness could perhaps be considered for the 1st transverse mode of the deck, since it is in this mode that the asphalt layer plays its largest contribution.
4

Suivi temporel des propriétés mécaniques de la croûte sous le Japon à partir des données continues du réseau Hi-net / Monitoring of the mechanical properties of the crust beneath Japan from continuous data of the Hi-net network

Wang, Qing-Yu 19 December 2018 (has links)
Le Japon s’est doté du réseau sismologique à haute sensibilité (Hi-net) qui contient plus de 1000 stations permanentes, qui fournissent d’immenses ensembles des données continues au Japon. Dans le cadre d’un accord avec le NIED, nous bénéficions d’enregis- trements de fond de données à court et à long periodes pour analyser les variations de vitesse sismiques, afin de suivre l’évolution mécanique de la croûte temporelle avec une résolution temporelle mensuelle à quotidienne dans les différentes bandes de périodes. Les résultats de courte période nous aident à mieux comprendre la sismologie environnemen- tale sur les processus souterrains sous les impacts de certains forçages environnementaux environnants tels que l’hydrologie, la thermoelasticité et certains effets de charge directe. Les résultats de longues périodes montrent des réponses co- et post-sismiques différentes avec la profondeur. Il s’agit d’une méthode supplémentaire et directe pour révéler en profondeur le champ de contrainte/déformation, ce qui améliore la perception du mécanisme d’un tremblement de terre. Cette thèse comprend principalement les trois parties suivantes.La première partie est consacrée à la présentation de la relation entre la fonction de Green et les corrélations croisées. La simulation numérique à Hokkaido vérifie également l’établissement de la relation entre les deux.La seconde partie concerne l’analyse des variations transitoires de la vitesse des ondes sismiques dans la croûte provoquées par les perturbations environnementales. Les impacts des perturbations saisonnières environnementales sur la déformation de la croûte sont généralement suivis et discutés en fonction des observations géodésiques. Récemment, la surveillance du bruit sismique ambiant fournit de nouvelles informations sur la déformation continue de la croûte, révélée par les changements de vitesse sismiques temporels. Dans cette étude, nous identifions les différents facteurs environnementaux responsables des effets saisonniers locaux et montrons comment une meilleure compréhension de ces perturbations de la croûte causée par l’environnement améliore les observations des modifications des propriétés sismiques induites par la tectonique.La dernière partie consiste à étudier la réponse mécanique de la croûte aux grands séismes. La surveillance de la vitesse sismique basée sur le bruit peut directement son- der en permanence l’état mécanique de la croûte en profondeur. Dans ce travail, nous étudions la réponse de la croûte terrestre au séisme de Tohoku-oki Mw 9.0, 2011. Nous employons ici pour la première fois le réseau très dense de Hi-Net tiltmètre en tant que sismomètres de longue période (8 - 50 s) pour que la surveillance basée sur le bruit échantillonne la croûte à plus de 5 km en profondeur. L’évolution spatio-temporelle des changements de vitesse sismiques dans différentes bandes de périodes révèle une réponse sismique dépendant de la profondeur, qui est la limite pour les données des sismomètres courte période. Le résultat pourrait avoir des implications à la fois sur la réponse viscoélastique de la croûte aux grands déformations ou sur une réponse complexe des vitesses sismiques de la croûte à un ècoulement de fluide transitoire.Cette thèse s’inscrit dans le cadre d’une collaboration plus générale entre ISTerre- Universit Grenoble Aples et le Massachusetts Institute of Technology visant à développer des outils de surveillance dans des contextes naturels et industriels. / The Japanese High Sensitivity Seismograph Network (Hi-net) contains more than 1000 permanent stations, which provide large continuous data sets throughout Japan. In the framework of an agreement with NIED, we benefit from both short period and tilt meters data downhole recordings to analyze the seismic velocity variations, thus to follow the mechanical evolution of the crust in different time scales with a temporal re- solution from monthly to daily in different period ranges. The short period results help us better understanding the environmental seismology on the subsurface processes under the impacts of some surrounding environmental forcing such as hydrology, thermoelas- ticity, and some direct loading effects. The results from long periods show different co- and postseismic responses with depth. This is a supplementary and direct method to disclose the stress/strain field at depth improving the perception of the mechanism of an earthquake. This thesis mainly consists of the following three parts.The first part is devoted to the theoretical demonstration of the relationship between the Green’s function and cross-correlations. The numerical simulation in Hokkaido also verifies the establishment of the in-between connection.The second part is about the analysis of the transient changes of seismic wave velo- city in the crust caused by environmental perturbations. The impacts of environmental seasonal disturbances to crustal deformation are usually tracked and discussed based on geodetic observations. Recently, ambient seismic noise-based monitoring provides new insights into the continuous deformation in the crust as revealed by the temporal seismic velocity changes. In this study, we identify the different environmental factors in charge of the local seasonal effects and show how better understanding these environmentally induced crustal perturbations improves the observations of tectonic-induced seismic pro- perty changes.The last part is to study the mechanical response of the crust to large earthquakes.Noise-based seismic velocity monitoring can directly probe the mechanical state of the crust at depth continuously in time. In this work, we study the response of the crust to the Mw 9.0, 2011 Tohoku-oki earthquake. we employ here for the first time the very dense network of Hi-net tilt meters as long period (8 – 50 s) seismometers for the noise-based monitoring to sample the crust below 5 km depth. Spatio-temporal evolution of seismic velocity changes in different period bands reveals depth-dependent seismic response. The result could have implications of both nonelastic response of the crust to large strain changes or a complex response of crustal seismic velocities to transient fluid flow.This thesis is in the context of a more general collaboration between ISTerre- Universit Grenoble Aples, and the Massachusetts Institute of Technology aiming at developing tools for monitoring in natural and industrial contexts.
5

Théorèmes limites pour des processus à longue mémoire saisonnière

Ould Mohamed Abdel Haye, Mohamedou 30 December 2001 (has links) (PDF)
Nous étudions le comportement asymptotique de statistiques ou fonctionnelles liées à des processus à longue mémoire saisonnière. Nous nous concentrons sur les lignes de Donsker et sur le processus empirique. Les suites considérées sont de la forme $G(X_n)$ où $(X_n)$ est un processus gaussien ou linéaire. Nous montrons que les résultats que Taqqu et Dobrushin ont obtenus pour des processus à longue mémoire dont la covariance est à variation régulière à l'infini peuvent être en défaut en présence d'effets saisonniers. Les différences portent aussi bien sur le coefficient de normalisation que sur la nature du processus limite. Notamment nous montrons que la limite du processus empirique bi-indexé, bien que restant dégénérée, n'est plus déterminée par le degré de Hermite de la fonction de répartition des données. En particulier, lorsque ce degré est égal à 1, la limite n'est plus nécessairement gaussienne. Par exemple on peut obtenir une combinaison de processus de Rosenblatt indépendants. Ces résultats sont appliqués à quelques problèmes statistiques comme le comportement asymptotique des U-statistiques, l'estimation de la densité et la détection de rupture.
6

Population delineation and wintering ground influence on vital rates of white-winged scoters

Swoboda, Cindy Jean 03 May 2007
North American populations of white-winged scoters (<i>Melanitta fusca deglandi</i>) have declined markedly over the past several decades. The causes for decline are uncertain, but likely involve a complexity of events occurring on wintering and breeding areas. To gain insight into potential cross-seasonal effects, I delineated Atlantic and Pacific wintering scoter populations and linked them to a shared breeding area using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) ratios in feathers. By applying this methodology to a marked breeding population at Redberry Lake, Saskatchewan, I assigned females to putative wintering areas and determined: (1) population structure; (2) the extent of winter site philopatry; and, (3) differences in vital rates and other variates in relation to winter origin. Discriminant function analysis of isotopic ratios in feather samples from known wintering locations resulted in classification probabilities of 96% (<i>n</i> = 149) for Pacific and 78% (<i>n</i> = 32) for Atlantic wintering scoters. Using this methodology, I determined that the Redberry Lake breeding population is comprised of approximately 75% Pacific and 25% Atlantic wintering birds, and its members exhibit high degrees of winter region philopatry based on the classification of successive recaptures over three field seasons. Annual variations in population structure, as well as differences in nest initiation dates and blood contaminant loads in relation to winter area suggest seasonal interactions may influence survival and reproductive success of this population. To gain insight into potential seasonal interactions, I examined nest success and female survival in relation to winter area. No significant differences in nest success in relation to winter area were found, but nests that failed before mid-incubation were not sampled. Adult female survival rate for 2000-2004 was estimated as 0.85, with no significant difference detected between wintering areas. This study demonstrated that it is important to link breeding and wintering areas to better understand the factors influencing population dynamics and to effectively address conservation issues.
7

Investment Companies’ Discount Fluctuation on the Swedish Market : A statistical analysis regarding different micro-   and macroeconomic factors influence on Swedish closed-end funds’ discount

Cau Nicklasson, Ronnie, Hansson, Simon January 2013 (has links)
Closed-end funds’ (CEF) discount and discount fluctuations have been puzzling researchers for decades. Up to date, there are no multidimensional or cross-sectional variables that have been proved to influence CEFs simultaneously. Fact is that, earlier research and theories on the subject are contradictious and several suggestions on the origin of the CEF’s discount and its fluctuations have been proposed. To mention a few, investor sentiments, taxation issues, dividend policies, agency costs and agency problems are considered to influence these discounts. The purpose of this report is to examine the relationship between micro- and macroeconomic variables fluctuations, and how these can explain the discount fluctuation of the Swedish CEFs. This report focuses upon the CEFs traded at NASDAQ OMX Stockholm, which have been selected through a comprehensive multistage selection process. 10 CEFs were selected. Monthly data for calculating micro- and macroeconomic variables was collected for the period March 2003 – February 2013, which resulted in approximately 1 200 observations. OLS regression analysis, Fixed- and Random Effect Models and Hausman tests were conducted. The findings conclude that some of this report’s chosen micro- and macro variables influence on the Swedish CEFs’ discount fluctuation, although these findings are conditioned. The CEFs’ individual characteristics or traits result in a significant impact on the fluctuation of CEFs’ discount. Hence, only by controlling these characteristics, multidimensional or cross-sectional micro- and macroeconomic variables can be proved to affect the CEFs’ discount fluctuation.
8

Investor distraction during the Swedish summer and stock market under-reaction to companies’ earnings releases

Guscott, Alyssa, Bach, My January 2011 (has links)
This paper investigates whether greater investor distraction on the Swedish stock market during the summer months of June, July and August leads to a more pronounced post earnings announcement drift (PEAD) effect, during the ten year period between 2000 and 2009. PEAD is an anomaly whereby the information contained in earnings announcements is not immediately or completely incorporated into stock prices, in the cases where the announcement contains an ‘earnings surprise’. The methodology involves using the standardised unexpected earnings (SUE) metric to measure the level of ‘earnings surprise’ and a buy and hold abnormal returns (BHAR) trading strategy to measure return. The study tests and confirms the existence of greater investor distraction during summer months on the Swedish market. For a holding period of 12 months, a BHAR trading strategy generates a greater abnormal return for summer months (11.3%) compared with the abnormal return for non-summer months (10.5%). These results are also interesting in a broader context, as they confirm the existence of the PEAD effect, one of the strongest counter-arguments to the efficient markets hypothesis (EMH); the foundation of many financial models used for stock market valuation. This is because, according to the EMH, in an efficient market it should not be possible to generate abnormal returns based on available information. However, it may be noted that these results do not take into account transaction costs. This means that while it can be demonstrated that there is greater investor distraction during the Swedish summer, in order to implement a successful trading strategy based on this finding, further testing would be required. Therefore, based on the findings of this paper, a number of areas for future research have been identified.
9

Population delineation and wintering ground influence on vital rates of white-winged scoters

Swoboda, Cindy Jean 03 May 2007 (has links)
North American populations of white-winged scoters (<i>Melanitta fusca deglandi</i>) have declined markedly over the past several decades. The causes for decline are uncertain, but likely involve a complexity of events occurring on wintering and breeding areas. To gain insight into potential cross-seasonal effects, I delineated Atlantic and Pacific wintering scoter populations and linked them to a shared breeding area using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) ratios in feathers. By applying this methodology to a marked breeding population at Redberry Lake, Saskatchewan, I assigned females to putative wintering areas and determined: (1) population structure; (2) the extent of winter site philopatry; and, (3) differences in vital rates and other variates in relation to winter origin. Discriminant function analysis of isotopic ratios in feather samples from known wintering locations resulted in classification probabilities of 96% (<i>n</i> = 149) for Pacific and 78% (<i>n</i> = 32) for Atlantic wintering scoters. Using this methodology, I determined that the Redberry Lake breeding population is comprised of approximately 75% Pacific and 25% Atlantic wintering birds, and its members exhibit high degrees of winter region philopatry based on the classification of successive recaptures over three field seasons. Annual variations in population structure, as well as differences in nest initiation dates and blood contaminant loads in relation to winter area suggest seasonal interactions may influence survival and reproductive success of this population. To gain insight into potential seasonal interactions, I examined nest success and female survival in relation to winter area. No significant differences in nest success in relation to winter area were found, but nests that failed before mid-incubation were not sampled. Adult female survival rate for 2000-2004 was estimated as 0.85, with no significant difference detected between wintering areas. This study demonstrated that it is important to link breeding and wintering areas to better understand the factors influencing population dynamics and to effectively address conservation issues.
10

Análise de séries temporais de coordenadas estimadas com GPS: uma proposta metodológica para eliminação de efeitos sazonais

Rosa, Guilherme Poleszuk dos Santos [UNESP] 31 October 2008 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-10-31Bitstream added on 2014-06-13T19:48:44Z : No. of bitstreams: 1 rosa_gps_me_prud.pdf: 9069576 bytes, checksum: d425dc3fdddbb18d5468027b620176e1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As redes ativas GPS tem se tornando cada vez mais utilizadas nos levantamentos geodésicos. As estações que fazem parte dessas redes têm suas coordenadas determinadas com alta precisão que, devido à estabilidade na sua construção e disponibilidade de dados, são chamadas estações de referência. Os dados podem ser empregados numa diversidade de pesquisas e projetos, sendo um dos mais comuns atualmente os de levantamentos geodésicos. O estudo e monitoramento do vapor d’água na atmosfera e movimento de placas litosféricas são exemplos de aplicações. Dentre os métodos de posicionamento GPS, o Posicionamento por Ponto Preciso (PPP) vem apresentando resultados muito promissores. Uma característica do PPP está relacionada com a modelagem e/ou estimação de todos os erros envolvidos nesse método. A acurácia obtida para as coordenadas pode ser da ordem de poucos milímetros, tal como no método de posicionamento relativo. Efeitos sazonais podem afetar esta acurácia caso não sejam considerados. Desta forma, é desejável dispor do conhecimento de todos os fatores sazonais (movimento do pólo, marés terrestres e cargas oceânicas) que interferem na posição da estação, visando minimizá-los ou modelá-los. Contudo, há evidências da existência de outros efeitos dessa natureza ainda não levados em consideração no PPP. Nesta pesquisa, foram realizados alguns experimentos com a finalidade de investigar os efeitos sazonais presentes nas séries temporais das coordenadas das estações Brasília (BRAZ), Euzébio (BRFT) e Manaus (NAUS) pertencentes à Rede Brasileira de Monitoramento Contínuo (RBMC)... / The active GPS networks have being more and more used in the geodetic surveying. The stations that belong to these networks have the coordinates determined with high precision, due to the construction stability and data availability, so they are called reference stations. The reference station data can be employed in a diversity of researches, where the geodetic positioning is one of the most common. The study and monitoring of the water vapor in the atmosphere and the lithosphere plates movement are examples of applications. Among the existent methods of GPS positioning, the Precise Point Positioning (PPP) has been presented great results. The accuracy obtained for the coordinates can reaches few millimeters, such as in the relative positioning. An important aspect concerning PPP is related to the modeling and / or estimation of all errors that affect this method. Among the errors, the seasonal effects can affect PPP accuracy if they are not considered. In this way, it is desirable to take care of all the seasonal factors (polar motion, solid tides and ocean loading) that interfere in the station position, aiming to minimize or to model them. Besides, there are evidences of other seasonal effects that still remain in PPP. In this research, some experiments were carried out with the finality of investigating the seasonal effects in the coordinate time series of the stations Brasília (BRAZ), Euzébio (BRFT) and Manaus (NAUS), that belong to the Rede Brasileira de Monitoramento Contínuo (RBMC). The coordinates of these stations were estimated daily using... (Complete abstract click electronic access below)

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