10,628 research outputs found

    The Effects of Fire Fighting and On-Scene Rehabilitation on Hemostatis

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    Fire fighting is a dangerous occupation – in part because firefighters are called upon to perform strenuous physical activity in hot, hostile environments. Each year, approximately 100 firefighters lose their lives in the line of duty and tens of thousands are injured. Over the past 15 years, approximately 45% of line of duty deaths have been attributed to heart attacks and another 650-1,000 firefighters suffer non-fatal heart attacks in the line of duty each year. From 1990 to 2004, the total number of fireground injuries has declined, yet during this same period, the number of cases related to the leading cause of injury - overexertion/strain – remained relatively constant. It is well recognized that fire fighting leads to increased cardiovascular and thermal strain. However, the time course of recovery from fire fighting is not well documented, despite the fact that a large percentage of fire fighting fatalities occur after fire fighting activity. Furthermore, on scene rehabilitation (OSR) has been broadly recommended to mitigate the cardiovascular and thermal strain associated with performing strenuous fire fighting activity, yet the efficacy of different rehabilitation interventions has not been documented. Twenty-five firefighters were recruited to participate in a “within-subjects, repeated measures” study designed to describe the acute effects of fire fighting on a broad array of physiological and psychological measures and several key cardiovascular variables. This study provided the first detailed documentation of the time course of recovery during 2½ hours post-fire fighting. Additionally, we compared two OSR strategies (standard and enhanced) to determine their effectiveness.published or submitted for publicationnot peer reviewe

    Representation of Africa online: sourcing practice and frames of reference

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    The dominant perspective on the representation of Africa in the western media claims that western media coverage is bias and crisis orientated and the liberal perspective claims that the coverage of Africa is not as negative as is often assumed. However, there is a paucity of literature on the representation of Africa online. This research enquiry is relevant because literature claims that the Internet has the potential to resolve the journalistic predicament of representing other culture through political participation and deliberation. But this requires a re-orientation of the sourcing practice of news organization to embrace sensitivity to and knowledge of African cultures. Moreover, the journalistic predicament can be resolved or not depending on the news gathering approach adopted by the news organization. Literature has identified two approaches, that is, ‘gatekeeping’ used mainly by dominant traditional media and ‘gatewatching’ used by alternative media in their quest to counter mainstream ideology. This study examines the impacts of the ‘gatewatching’ approach adopted by Africa Have Your Say (AHYS) website on its representation and frames of reference of Africa. It uses on-site observation, in-depth interviews and textual analysis to gather data. The study found that although the sourcing practice at the AHYS is elaborate and complex, the ‘gatewatching’ approach makes its susceptible to second level agenda setting. Hence, its frame repeats the attributes and tone used by the mainstream traditional media. However, a minority of users did not use repeat this frame in their comments

    Morphology Effectively Controls Singlet-Triplet Exciton Relaxation and Charge Transport in Organic Semiconductors

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    We present a comparative study of ultrafast photo-conversion dynamics in tetracene (Tc) and pentacene (Pc) single crystals and Pc films using optical pump-probe spectroscopy. Photo-induced absorption in Tc and Pc crystals is activated and temperature-independent respectively, demonstrating dominant singlet-triplet exciton fission. In Pc films (as well as C60_{60}-doped films) this decay channel is suppressed by electron trapping. These results demonstrate the central role of crystallinity and purity in photogeneration processes and will constrain the design of future photovoltaic devices.Comment:

    Anomalous transverse acoustic phonon broadening in the relaxor ferroelectric Pb(Mg_1/3Nb_2/3)O_3

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    The intrinsic linewidth ΓTA\Gamma_{TA} of the transverse acoustic (TA) phonon observed in the relaxor ferroelectric compound Pb(Mg1/3_{1/3}Nb2/3)0.8_{2/3})_{0.8}Ti0.2_{0.2}O3_3 (PMN-20%PT) begins to broaden with decreasing temperature around 650 K, nearly 300 K above the ferroelectric transition temperature TcT_c (360\sim 360 K). We speculate that this anomalous behavior is directly related to the condensation of polarized, nanometer-sized, regions at the Burns temperature TdT_d. We also observe the ``waterfall'' anomaly previously seen in pure PMN, in which the transverse optic (TO) branch appears to drop precipitously into the TA branch at a finite momentum transfer qwf0.15q_{wf} \sim 0.15 \AA1^{-1}. The waterfall feature is seen even at temperatures above TdT_d. This latter result suggests that the PNR exist as dynamic entities above TdT_d.Comment: 6 pages, 4 figure

    Decay of escherichia coli in soil following the application of biosolids to agricultural land

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    The decay of Escherichia coli in a sandy loam soil, amended with enhanced and conventionally treated biosolids, was investigated in a field experiment following spring and autumn applications of sewage sludge. Control soils, without the application of biosolids, were also examined to determine the background indigenous populations of E. coli which are present in the environment. The survival of indigenous E. coli and populations of E. coli applied to soil in biosolids, is assessed in relation to environmental factors influencing pathogen-decay processes in soil

    Relationship between spatial proximity and travel-to-work distance : the effect of the compact city

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    In this paper, an assessment is made of the relationship between selected aspects of spatial proximity (density, diversity, minimum commuting distance, jobs-housing balance and job accessibility) and reported commuting distances in Flanders (Belgium). Results show that correlations may depend on the considered trip end. For example, a high residential density, a high degree of spatial diversity and a high level of job accessibility are all associated with a short commute by residents, while a high job density is associated with a long commute by employees. A jobs-housing balance close to one is associated with a short commute, both by residents and by employees. In general, it appears that the alleged sustainability benefits of the compact city model are still valid in a context of continuously expanding commuting trip lengths
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