842 research outputs found

    Effect of metal clusters on the swelling of gold-fluorocarbon-polymer composite films

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    We have investigated the phenomenon of swelling due to acetone diffusion in fluorocarbon polymer films doped with different gold concentrations below the percolation threshold. The presence of the gold clusters in the polymer is shown to improve the mixing between the fluorocarbon polymer and the acetone, which is not a good solvent for this kind of polymers. In order to explain the experimental results the stoichiometry and the morphology of the polymer--metal system have been studied and a modified version of the Flory--Huggins model has been developed

    End-user oriented strategies to facilitate multi-organizational adoption of emergency management information systems

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    11 pages, 4 figures.Response to large-scale emergencies is a cooperative process that requires the active and coordinated participation of a variety of functionally independent agencies operating in adjacent regions. In practice, this essential cooperation is sometimes not attained or is reduced due to poor information sharing, non-fluent communication flows, and lack of coordination. We report an empirical study of IT-mediated cooperation among Spanish response agencies and we describe the challenges of adoption, information sharing, communication flows, and coordination among agencies that do not share a unity of command. We analyze three strategies aimed at supporting acceptance and surmounting political, organizational and personal distrust or skepticism: participatory design, advanced collaborative tools inducing cognitive absorption, and end-user communities of practice.This work has been funded by the Grant (PR2007-0271) and the Research Project (TSI2007-60388) of Spanish Ministry of Education and Science. SIGAME is a project funded by Dirección General de Protección Civil y Emergencias of Spanish Ministry of Interior.Publicad

    Hemodynamic and ADH responses to central blood volume shifts in cardiac-denervated humans

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    Hemodynamic responses and antidiuretic hormone (ADH) were measured during body position changes designed to induce blood volume shifts in ten cardiac transplant recipients to assess the contribution of cardiac and vascular volume receptors in the control of ADH secretion. Each subject underwent 15 min of a control period in the seated posture, then assumed a lying posture for 30 min at 6 deg head down tilt (HDT) followed by 20 min of seated recovery. Venous blood samples and cardiac dimensions (echocardiography) were taken at 0 and 15 min before HDT, 5, 15, and 30 min of HDT, and 5, 15, and 30 min of seated recovery. Blood samples were analyzed for hematocrit, plasma osmolality, plasma renin activity (PRA), and ADH. Resting plasma volume (PV) was measured by Evans blue dye and percent changes in PV during posture changes were calculated from changes in hematocrit. Heart rate (HR) and blood pressure (BP) were recorded every 2 min. Results indicate that cardiac volume receptors are not the only mechanism for the control of ADH release during acute blood volume shifts in man

    The effects of single versus twice daily short term heat acclimation on heat strain and 3000 m running performance in hot, humid conditions

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    Endurance performances are impaired under conditions of elevated heat stress. Short term heat acclimation (STHA) over 4-6 days can evoke rapid adaptation, which mitigate decrements in performance and alleviate heat strain. This study investigated the efficacy of twice daily heat acclimation (TDHA) compared to single session per day heat acclimation (SDHA) and normothermic training, at inducing heat acclimation phenotype and its impact upon running performance in hot, humid conditions.Twenty one, moderately trained males were matched and assigned to three groups; SDHA (mean±SD) (peak oxygen consumption [V˙O2peak] 45.8±6.1 mL kg-1 min-1, body mass 81.3±16.0 kg, stature 182±3 cm), TDHA (46.1±7.0 mL kg-1 min-1, 80.1±11.9 kg, 178±4 cm) or control (CON) (47.1±3.5 mL kg-1 min-1, 78.6±16.7 kg, 178±4 cm). Interventions consisted of 45 min cycling at 50% V˙O2peak, once daily for 4d (SDHA) and twice daily for 2d (TDHA), in 35 °C, 60% relative humidity (RH), and once daily for 4 days (CON) in 21 °C, 40% RH. Participants completed a pre- and post-intervention 5 km treadmill run trial in 30 °C, 60% RH, where the first 2 km were fixed at 40% V˙O2peak and the final 3 km was self-paced.No statistically significant interaction effects occurred within- or between-groups over the 2-4 days intervention. While within-group differences were found in physiological and perceptual measures during the fixed intensity trial post-intervention, they did not statistically differ between-groups. Similarly, TDHA (-36±34 s [+3.5%]) and SDHA (-26±28 s [+2.8%]) groups improved 3 km performances (p=0.35), but did not differ from CON (-6±44 s [+0.6%]).This is the first study to investigate the effects of HA twice daily and compare it with traditional single session per day STHA. These STHA protocols may have the ability to induce partial adaptive responses to heat stress and possibly enhance performance in environmentally challenging conditions, however, future development is warranted to optimise the administration to provide a potent stimuli for heat adaptation in athletic and military personnel within a rapid regime

    Human Versus Machine: A Comparative Analysis in Detecting Artificial Intelligence-Generated Images

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    This article delves into the intricate process of artificial intelligence-generated content detection, shedding light on automated detectors' challenges and revealing human detection biases, strengths, and weaknesses

    Common ground in collaborative intelligence analysis: an empirical study

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    This paper reports an empirical exploration of how different configurations of collaboration technology affect peoples’ ability to construct and maintain common ground while conducting collaborative intelligence analysis work. Prior studies of collaboration technology have typically focused on simpler conversational tasks, or ones that involve physical manipulation, rather than the complex sensemaking and inference involved in intelligence work. The study explores the effects of video communication and shared visual workspace (SVW) on the negotiation of common ground by distributed teams collaborating in real time on intelligence analysis tasks. The experimental study uses a 2x2 factorial, between-subjects design involving two independent variables: presence or absence of Video and SVW. Two-member teams were randomly assigned to one of the four experimental media conditions and worked to complete several intelligence analysis tasks involving multiple, complex intelligence artefacts. Teams with access to the shared visual workspace could view their teammates’ eWhiteboards. Our results demonstrate a significant effect for the shared visual workspace: the effort of conversational grounding is reduced in the cases where SVW is available. However, there were no main effects for video and no interaction between the two variables. Also, we found that the “conversational grounding effort” required tended to decrease over the course of the tas

    Half-Time Strategies to Enhance Second-Half Performance in Team-Sports Players: A Review and Recommendations

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    The competitive demands of numerous intermittent team sports require that two consecutive periods of play are separated by a half-time break. Typically, half-time allows players to: return to the changing rooms, temporarily relax from the cognitive demands of the first half of match-play, rehydrate, re-fuel, attend to injury or equipment concerns, and to receive tactical instruction and coach feedback in preparation for the second half. These passive practices have been associated with physiological changes which impair physical and cognitive performance in the initial stages of the second half. An increased risk of injury has also been observed following half-time. On the day of competition, modification of half-time practices may therefore provide Sports Scientists and Strength and Conditioning Coaches with an opportunity to optimise second half performance. An overview of strategies that may benefit team sports athletes is presented; specifically, the efficacy of: heat maintenance strategies (including passive and active methods), hormonal priming (through video feedback), post-activation potentiation, and modified hydro-nutritional practices are discussed. A theoretical model of applying these strategies in a manner that compliments current practice is also presented
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