Exposure to thermal stress can negatively impact an animals' overall welfare, resulting in decreased body condition, lower reproductive success, and in severe cases, mortality. The swine industry has prioritized efficient production and as a result has gained rapid improvements in lean growth and increase litter sizes. Unfortunately, modern swine are unable to cope with the negative effects of heat stress. Thus, it is crucial to understand the preferred temperature of swine to create recommendations on when to initiate mitigation strategies to combat the negative effects of thermal stress. However, several different factors contribute to an animals' thermal comfort and thermal preference will differ based on age, reproductive stage, social context, early life thermal stress, and behavior. Thus, making it exceptionally difficult to classify an animal's thermal comfort zone. These studies aim to highlight how those factors influence thermal comfort in pigs and help guide recommendation polices for housing pigs in their preferred temperatures.<br>

Temperature is a ubiquitous force influencing biological processes ranging from cellular responses to life span. The thermal environment for many organisms is predicted to change with globally increasing temperatures and studies conducted in natural systems incorporating various evolutionary forces, such as gene flow, is needed. In my thesis, I investigate how snails (Radix balthica) originating from distinct geothermal environments within Lake Mývatn in northern Iceland have adapted, both genetically and phenotypically, to the respective thermal regime. Locations were classified as either cold, warm or seasonal depending on the average and variance in temperature. A high resolution spatial distribution of genetic variation within Mývatn was obtained using both neutral and outlier AFLPs. In addition, the genetic profile enabled me identify warm origin snails irrespective of geographic location in Iceland. Warm environments were often more stressful than cold or seasonal environments but snails originating from a high temperature location benefited from increased performance elsewhere. Patterns of growth were identical in both common garden and reciprocal transplant experiment; warm origin snails grew faster than both cold and seasonal origin snails. This result is in concordance with quantitative genetics models of thermal adaptation but suggesting cogradient rather than countergradient variation. Although warm origin snails generally had superior performance, survival at cold temperatures (&lt; 12 °C) was reduced. All snails matured at similar size in the common garden experiment but cold origin snails were observed to mature later and lay fewer eggs. Also, snails had a common optimum for growth rate at 20 °C irrespective of thermal origin. This is arguably the reason why snails were observed to have a common thermal preference. Interestingly, warm origin snails had a reduced tolerance to high temperatures compared to cold and seasonal origin snails which did not differ in tolerance. Putatively, natural selection has reduced a putatively unnecessary trait (high temperature tolerance in a stable thermal environment) in favour of higher growth rate and performance in warm habitats. In conclusion, the price of high performance in a warm environment was paid in terms of reduced survival at low temperatures and a potential disadvantage of reduced genetic variability.

Made available in DSpace on 2016-06-02T20:09:07Z (GMT). No. of bitstreams: 1 1612.pdf: 2927282 bytes, checksum: 0156961dd061931755aa12339ca3139f (MD5) Previous issue date: 2007-03-09 / Financiadora de Estudos e Projetos / Thermal comfort is specifically related to thermal behavior in response to both indoor and outdoor air temperature. Human thermal acceptability to climate changes and its effects depend on several aspects. It relies not only on local climatic conditions, but also on personal traits which can interfere seriously with thermal preferences as well as with someone s mental and physical performance. The combination of these factors determines the human thermal acceptability and the satisfaction degree in relation to a specific environment. The more those conditions vary, the higher the percentage of dissatisfied people with an environment is, due to personal requirements of each person. Thus, meeting those expectations of thermal comfort, considering people s needs and limitations, has been an important subject of studies in this field highlighting its importance when planning, designing, and constructing a building. Therefore, human thermal preferences and thermal sensations to hot and cold environments are essential information to various activity sectors because comfort and human performances depend directly on environmental thermal conditions. Since architecture, mainly buildings, is intended for humans, it can be said that it should satisfy its occupants, regarding local climate conditions. In order to have this, it s necessary to determine the comfort temperatures in which people develop better their work activities, optimizing their mental, physical, and intellectual well being. This research consists of a theoretical analytical study of the international large database, compiled by ASHRAE (1997), combining climate conditions with human thermal preferences and sensations. The methodology used by Richard De Dear (1997) in the RP-884 ASHRAE s project was the probit procedure using SAS software, release 8 (SAS Institute, Cary, NC, USA, 1999) to the optimum temperatures obtained, and linear regression to the acceptable comfort limits of the population studied. The comfort limits obtained demonstrate the ratio between occupants comfort temperature and the outdoor temperature, featuring fluctuations of 80% to 90% of thermal acceptability in well-ventilated buildings. The aim of this study is to interpret the method adopted by Richard De Dear (1997) and apply it to the data resulting from the large ASHRAE (2004) Database to understand how the comfort temperatures (optimum temperatures) and the thermal acceptability were obtained for a group of people under predetermined indoor thermal conditions in well- ventilated buildings. The Probit analysis indicates the optimum temperature is 25ºC approximated, exactly 0,5 probability responses, that is, 50% interviewees. In the face the obtained results, it s succeeded the Probit analysis applicability has a great efficacy method to binary variable probability study and determination, which points out two interesting situations to research / O termo conforto térmico abrange muitos fatores do comportamento térmico subjetivo na relação com o clima interno e externo. A aceitabilidade térmica do homem aos efeitos do clima depende de vários aspectos, não só das condições climáticas do local, mas também de fatores pessoais que podem interferir significativamente nas suas preferências térmicas, bem como no rendimento físico e mental do seu organismo. A interação destes dois grupos de fatores determina o grau de satisfação e aceitabilidade térmica do homem em relação a um determinado ambiente. Quanto maior a variação destas condições, maior será a porcentagem de insatisfeitos em um ambiente, devido às exigências pessoais de cada indivíduo. Assim, atender as expectativas do homem em relação ao conforto térmico, considerando suas necessidades e limitações, tem sido um dos focos de estudos nesta área, que destaca a importância do tema no planejamento, projeto e execução de edificações. As sensações e preferências térmicas humanas em relação ao calor e ao frio, portanto, constituem informação indispensável para inúmeros setores de atividades, pois o conforto e o desempenho humano dependem diretamente das condições térmicas dos ambientes. Sendo a arquitetura, em particular o edifício, feito para o homem, conclui-se que este deve atender satisfatoriamente ao usuário, dentro das condições climáticas locais. Para isto, é necessário conhecer as temperaturas de conforto sob as quais o homem melhor desenvolve suas atividades de trabalho, otimizando seu bem-estar físico, intelectual e mental. Esta pesquisa consiste em um estudo teórico analítico da ampla base internacional de dados, compilada pela ASHRAE (1997), relacionando condições climáticas do ar e sensações e preferências térmicas humanas. A metodologia utilizada por Richard De Dear (1997) no projeto ASHRAE RP-884 foi o procedimento probit no software SAS, versão 8 (SAS Institute, Cary, NC, USA, 1999) para as temperaturas preferidas obtidas, e de regressão linear para os limites de conforto aceitáveis pela população avaliada. Estes limites de conforto resultantes expressam a relação entre temperatura de conforto do usuário e temperatura externa do ar, apresentando variações de 80% e 90% de aceitabilidade térmica, em edifícios naturalmente ventilados. O objetivo geral desta pesquisa é interpretar o método adotado por De Dear (1997) e aplicá-lo nos dados obtidos da ampla Base de Dados da ASHRAE (2004), como fim de entender como foram obtidas as temperaturas de conforto (temperaturas preferidas) e a aceitabilidade térmica de pessoas submetidas a determinadas condições térmicas internas, em ambientes naturalmente ventilados. Os resultados da análise Probit mostram que a temperatura preferida é aproximadamente 25ºC, a exatamente 0,5 de probabilidade de respostas, ou seja, 50% dos entrevistados. Diante dos resultados obtidos, verificou-se a aplicabilidade da análise Probit, como um método de grande eficácia para o estudo e a determinação de probabilidades de variáveis binárias, as quais apontam duas situações de interesse para a pesquisa