The cardiovascular effects of whole body heat stress during exercise are well established. However the independent contribution of elevated skin temperature (Tsk) or core temperature (Tc) on these responses remains unclear. The purpose of this study was to determine how increases in Tsk and Tc alone and in combination, impact cardiovascular responses during moderate intensity exercise. To accomplish this goal, eight healthy, recreationally active males were immersed to the neck in a cold (14 - 17°C) or hot (40 - 42.5°C) water bath for 20 to 25 min to alter Tc immediately prior to exercise with either cool Tsk (i.e. fans) or warm Tsk (i.e. heaters). Conditions during exercise were cool skin and cool core (CC), warm skin and cool core (WC), cool skin and warm core (CW), and warm skin and warm core (WW), and were conducted in a randomized crossover design. When data was combined (n=16), warm core conditions (CW and WW) were associated with significantly higher average heart rate (HR) and lower stroke volume (SV) during exercise compared to cool core conditions (CC and WC); 168.1 ± 3.2 vs. 152.2 ± 4.0 beats/min and 139.2 ± 7.3 vs. 147.7 ± 9.4 mL/beat, respectively. The approximate 9 mL/beat decline in SV and 16 beat/min increase in HR in warm core conditions tended to increase cardiac output (Q), 23.2 ± 0.6 vs. 22.2 ± 0.7 L/min, P=0.078. Similarly, warm Tsk conditions (WC and WW) were associated with significantly higher average HR and lower SV during exercise compared to cool Tsk conditions (CC and CW); 165.2 ± 3.3 vs. 155.1 ± 3.4 beats/min and 140.8 ± 7.8 vs. 146.0 ± 8.7 mL/beat, respectively. Additionally, there was also a trend for Q to be elevated with warm skin (23.0 ± 0.6 vs. 22.4 ± 0.6, P=0.075). Although combined data indicated that warm Tsk conditions significantly lowered average SV by ~6 mL/beat, there was no reduction in SV during exercise by warm Tsk, when Tes was cool (i.e. <37.0°C), as evidenced by identical values for SV in CC and WC, 147.7 ± 9.8 vs. 147.7 ± 9.0 mL/beat, respectively. In contrast, SV was significantly lower in WW compared with CW, 133.9 ± 7.0 vs. 144.4 ± 7.8 mL/beat, respectively. Therefore, the major reduction in SV by warm Tsk occurred during WW, when Tes was elevated (i.e. >38.0°C). Analyzing data independently for precooling and preheating conditions revealed that warm Tsk was associated with greater HR drift from 5 to 20 min of exercise, compared to cool Tsk, when esophageal temperature (Tes) was both cool or warm (23.9 ± 2.2 vs. 17.5 ± 2.3 and 12.3 ± 1.3 vs. 4.6 ± 1.7 beats/min, respectively). These observations demonstrate that both Tes and Tsk can directly influence cardiovascular responses during exercise, as indicated by elevations in HR during exercise with warm Tsk, with both warm and cool Tes. However SV is not compromised by warm Tsk if Tes is below 37.5°C. Furthermore, when both Tes and Tsk are elevated simultaneously, cardiovascular strain (i.e. increased HR and reduced SV) is much greater than when either is elevated alone. This is demonstrated by the finding that average HR was 175.8 ± 3.2 beats/min in WW, compared to 149.8 ± 4.0, 154.7 ± 4.1, and 160.3 ± 3.5 beats/min, in CC, WC, and CW, respectively, and the fact that SV was lowest during exercise in WW. In conclusion, individuals exercising in the heat should take measures to keep skin cool, especially when Tes is 39°C or greater to attenuate the cardiovascular strain that occurs with warm Tsk, when Tes is elevated. / text

It‟s very interesting demonstrates the needs of organizations, whether they private or public, of mechanisms that ensure information quality and quick access. Such mechanisms, among other functions, shall ensure the security and availability of information to the user. This is the work of information systems (SI): collect (or recover), process, store and distribute information for decision-making, coordination and control of an organization. In the light of its importance to the success of organizations, the study of the use of information systems has been a lot of attention for at least three decades. Understand the factors that necessitate the use of information systems is to establish relationships between behavior and attitudes of individuals, for example, the effort noticed and performance against technology, adjust this with the task to be performed and the degree of satisfaction that user front SI available. As a result, this research has focused study of motivational factors that impact the technology. Therefore, the main object of this work is to investigate whether or not respect/connection among constructs "Perceived effort", "performance", "Adequacy between task and technology" and "User satisfaction" in an institution of higher education (IES). The character was a case study. Were applied 167 questionnaires with public IES servers that actually use SI to perform their tasks. The results cited for identification of the variables that influence in user satisfaction of SI through the process of quantitative analysis developed in this work. / É reveladora a necessidade proeminente das organizações, quer sejam elas privadas ou públicas, de mecanismos que garantam informações de qualidade e de acesso rápido. Tais mecanismos, entre outras funções, devem assegurar a segurança e a disponibilidade das informações para o usuário dessas organizações. Este é o trabalho dos sistemas de informação (SI): coletar (ou recuperar), processar, armazenar e distribuir informações destinadas a apoiar a tomada de decisões, a coordenação e o controle de uma organização. Em função de sua importância para o sucesso das organizações, o estudo da utilização dos sistemas de informação tem merecido muita atenção há pelo menos três décadas. Entender os fatores que verificam a utilização dos sistemas de informação é estabelecer relações entre comportamento e atitude dos indivíduos como, por exemplo, o esforço percebido e o desempenho frente a tecnologia, o ajuste desta com a tarefa a ser executada e o grau de satisfação desse usuário frente ao SI disponível. Em decorrência disso, esta pesquisa tem como foco principal o estudo dos fatores motivacionais que impactam a adoção de uma tecnologia. Portanto, o objeto principal deste trabalho é investigar a existência ou não de relação/conexão entre os construtos esforço percebido , desempenho , da Adequação entre Tarefa e Tecnologia e a Satisfação do Usuário numa Instituição de Ensino Superior (IES). O caráter da pesquisa desenvolvida foi um estudo de caso. Foram aplicados 167 questionários aos servidores públicos de uma IES que, efetivamente, utilizavam o SI para realizar suas tarefas. Os resultados apontaram para a identificação das variáveis que influenciam na satisfação do usuário do SI através do processo de análise quantitativa desenvolvido no presente trabalho.

La problématique de la performance des marins en navigation extrême, n’a été que très peu étudiée avec des méthodes scientifiques rigoureuses de façon systématique et sous un angle de vue global en conditions écologiques. Nos travaux se sont attachés à évaluer le comportement humain en conditions écologiques avec une approche environnementaliste et transactionnelle. L’objectif principal de cette thèse a été de comprendre quel est l’impact des facteurs environnementaux tels que la force du vent et la quantité de sommeil ainsi que d’une stimulation cognitive à l’aide d’un vidéo self-modeling sur la perception de l’anxiété, de la fatigue et la tolérance à l’effort à vitesse maximale aérobie. Les résultats de la première étude, en condition écologique, où l’influence du vent et de la privation du sommeil ont été modélisées grâce à l’outil des fonctions transferts, a permis de comprendre que le marin opère une régulation liée temporellement à son engagement et aux efforts ou privations comme par exemple celle du sommeil. Cette régulation est liée à la perception de l’anxiété et l’intensité de l’effort perçu et est influencée par les facteurs environnementaux comme le vent ou la privation de sommeil. Cette étude a aussi montré qu’il existe une relation entre la durée de l’engagement, mesurée par le nombre de jours passés en mer, et la quantité de sommeil nécessaire, permettant ainsi de résister aux conditions environnementales. Une seconde étude en milieu extrême, cette fois en équipage de deux personnes, en utilisant le même protocole a confirmé que la quantité de sommeil était le meilleur activateur pouvant agir sur l’anxiété et permettre au mieux sa régulation. Une troisième étude nous a permis de montrer que la tolérance à un effort, mesuré par la perception de l’effort, n’était pas couplée exclusivement à une réponse physiologique mais aussi à des facteurs cognitifs. Le résultat principal de cette étude pilote a été de montrer que l’utilisation du feedback vidéo comme stimulation cognitive diminue significativement la perception de l’effort à partir 50% de la durée de l’épreuve. Contrairement à ce qui aurait pu être attendu, aucun effet n’a été observé sur la fréquence cardiaque. L’ensemble de ces résultats tend à montrer l’importance de l’interaction environnement – individu en milieu extrême, ainsi que lors d’une épreuve menée jusqu’aux limites de l’épuisement. Ces résultats ouvrent des perspectives intéressantes dans les domaines de l’entraînement sportif et de la rééducation. / The problem of performance in extreme sailing navigation has been very little studied using rigorous scientific methods consistently and at an angle of view in global environmental conditions. Our work sought to evaluate human behavior in ecological conditions with environmentalist and transactional approach. The main objective of this thesis was to understand what the impact of environmental factors such as wind strength and the amount of sleep as well as cognitive stimulation using a video self-modeling on perception of anxiety, fatigue and exercise tolerance in maximal aerobic speed. The results of the first study, ecological condition, where the influence of wind and sleep deprivation were modeled using the tool transfers functions, has to understand that the sailor makes a time- dependent regulation of its commitment and efforts and hardships such as that of sleep. This regulation is related to the perception of anxiety and intensity of perceived fatigue and is influenced by environmental factors such as wind or sleep deprivation. This study also showed that there is a relationship between the duration of the engagement, as measured by the number of days at sea, and the amount of sleep needed, allowing withstand environmental conditions. A second study in extreme conditions, this time with a crew of two people using the same protocol confirmed that the amount of sleep was the best activator can act on anxiety and allow its better regulation. A third study, we showed that the tolerance to stress, as measured by perceived exertion, was not exclusively coupled to a physiological response but also cognitive factors. The main result of this pilot study was to show that the use of video feedback as cognitive stimulation significantly reduces the perception of effort from 50 % of the duration of the event. Contrary to what might be expected, no effect was observed on heart rate. All of these results suggest the importance of the interaction environment - individual in extreme environments, and in a test conducted to the limits of exhaustion. These results open interesting perspectives in the fields of sports training and rehabilitation.