3,944 research outputs found

    Fire effects on aquatic ecosystems: an assessment of the current state of science

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    Fire is a prevalent feature of many landscapes and has numerous and complex effects on geological, hydrological, ecological, and economic systems. In some regions, the frequency and intensity of wildfire have increased in recent years and are projected to escalate with predicted climatic and landuse changes. In addition, prescribed burns continue to be used in many parts of the world to clear vegetation for development projects, encourage desired vegetation, and reduce fuel loads. Given the prevalence of fire on the landscape, authors of papers in this special series examine the complexities of fire as a disturbance shaping freshwater ecosystems and highlight the state of the science. These papers cover key aspects of fire effects that range from vegetation loss and recovery in watersheds to effects on hydrology and water quality with consequences for communities (from algae to fish), food webs, and ecosystem processes (e.g., organic matter subsidies, nutrient cycling) across a range of scales. The results presented in this special series of articles expand our knowledge of fire effects in different biomes, water bodies, and geographic regions, encompassing aquatic population, community, and ecosystem responses. In this overview, we summarize each paper and emphasize its contributions to knowledge on fire ecology and freshwater ecosystems. This overview concludes with a list of 7 research foci that are needed to further our knowledge of fire effects on aquatic ecosystems, including research on: 1) additional biomes and geographic regions; 2) additional habitats, including wetlands and lacustrine ecosystems; 3) different fire severities, sizes, and spatial configurations; and 4) additional response variables (e.g., ecosystem processes) 5) over long (>5 y) time scales 6) with more rigorous study designs and data analyses, and 7) consideration of the effects of fire management practices and policies on aquatic ecosystems

    Development of a Breadboard Instrument for the Ultrasonic Measurement of Stress

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    The measurement of stress is a generic problem which constantly occurs in nondestructive evaluation applications. X-ray diffraction provides the most successful approach, but suffers from the limitation that only a very near surface layer is sensed. Ultrasonic measurements, based on the stress dependence of the wave speed, have the capability of sampling bulk material. However, they suffer from some practical problems, including degradations in accuracy due to competing sources of wave speed shifts and difficulties of making measurements in complex geometries. The former problem has, in principle, been overcome by an approach recently developed as discussed below

    Electronic Prescribing Usability: Reduction of Mental Workload and Prescribing Errors Among Community Physicians

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    Background: Medical errors are common in hospitals, and research is always needed to find ways of reducing these. This study attempts to address three gaps in this field. First, the factors leading to the reduction of mental workload and its relationship with the reduction of prescribing errors by improving electronic prescribing (e-prescribing) usability have not been empirically examined before. Second, the past research in the field of e-prescribing usability lacks robust theoretical models. Third, there are no existing studies to examine the direct influences of user interface consistency and error prevention with the reduction of mental workload and prescribing errors. Materials and Methods: A quantitative survey method was used to collect data from 188 community physicians. The partial least squares path modeling technique was applied to analyze the data. Results: Prescribing errors were reduced by improving the information quality, user interface consistency, system ease of use, and mental workload reduction. Mental workload is reduced by ease of use, error prevention, and consistency. No significant relationships between prescribing error reduction with error prevention and also between information quality with mental workload reduction were found. Conclusions: The designers of e-prescribing should improve the error prevention and consistency of the system and make it easy to use if they wish for the system to reduce users’ mental workload. They should also improve the system information quality, ease of use, and consistency if they claim that their system reduces physicians’ prescribing errors. The system should also reduce users’ mental workload to meet this objective

    From Rotating Atomic Rings to Quantum Hall States

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    Considerable efforts are currently devoted to the preparation of ultracold neutral atoms in the emblematic strongly correlated quantum Hall regime. The routes followed so far essentially rely on thermodynamics, i.e. imposing the proper Hamiltonian and cooling the system towards its ground state. In rapidly rotating 2D harmonic traps the role of the transverse magnetic field is played by the angular velocity. For particle numbers significantly larger than unity, the required angular momentum is very large and it can be obtained only for spinning frequencies extremely near to the deconfinement limit; consequently, the required control on experimental parameters turns out to be far too stringent. Here we propose to follow instead a dynamic path starting from the gas confined in a rotating ring. The large moment of inertia of the fluid facilitates the access to states with a large angular momentum, corresponding to a giant vortex. The initial ring-shaped trapping potential is then adiabatically transformed into a harmonic confinement, which brings the interacting atomic gas in the desired quantum Hall regime. We provide clear numerical evidence that for a relatively broad range of initial angular frequencies, the giant vortex state is adiabatically connected to the bosonic ν=1/2\nu=1/2 Laughlin state, and we discuss the scaling to many particles.Comment: 9 pages, 5 figure

    Resource Pooling and Cost Allocation Among Independent Service Providers

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    Constrictive pericarditis is an easily overlooked cause of right heart failure: a case report

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    We describe a patient who suffered progressive right heart failure of unknown aetiology, despite a lengthy series of hospital investigations. Constrictive pericarditis had not been suspected during life, and was ultimately diagnosed as an autopsy finding. The salient clinical features and confirmatory investigations for this unusual disorder are reviewed. The case reminds us to consider the possibility of constrictive pericarditis in patients with unexplained chronic right heart failure, so that prompt investigation and treatment can be instigated

    Paired and clustered quantum Hall states

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    We briefly summarize properties of quantum Hall states with a pairing or clustering property. Their study employs a fundamental connection with parafermionic Conformal Field Theories. We report on closed form expressions for the many-body wave functions and on multiplicities of the fundamental quasi-hole excitations.Comment: 13 pages, Contribution to the proceedings of the NATO Advanced Research Workshop "Statistical Field Theories" Como (Italy), June 18-23 200

    The pseudogap: friend or foe of high Tc?

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    Although nineteen years have passed since the discovery of high temperature superconductivity, there is still no consensus on its physical origin. This is in large part because of a lack of understanding of the state of matter out of which the superconductivity arises. In optimally and underdoped materials, this state exhibits a pseudogap at temperatures large compared to the superconducting transition temperature. Although discovered only three years after the pioneering work of Bednorz and Muller, the physical origin of this pseudogap behavior and whether it constitutes a distinct phase of matter is still shrouded in mystery. In the summer of 2004, a band of physicists gathered for five weeks at the Aspen Center for Physics to discuss the pseudogap. In this perspective, we would like to summarize some of the results presented there and discuss its importance in the context of strongly correlated electron systems.Comment: expanded version, 20 pages, 11 figures, to be published, Advances in Physic

    Job Stressors, Strain, and Psychological Wellbeing Among Women Sports Coaches

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    Despite a globally recognised need for inclusive diversity among sport workforces, women are underrepresented in the inherently stressful profession of sports coaching. This study aimed to work with women sports coaches to answer the following research questions: 1) What demographic and contract-related factors are associated with job stressors? 2) What associations exist between job stressors, strain, and psychological wellbeing (PWB) at work? Women coaches (n = 217) volunteered to complete the revised version of An Organizational Stress Screening Tool (ASSET). Path analyses identified several groups of coaches (head coaches, “other” coaches, disabled coaches) who experienced more job stressors related to their coaching work. They also highlighted the importance of workload stressors and their detrimental relationship with psychological and physical strain but positive relationship with sense of purpose (i.e., eudaimonic wellbeing). Collectively, these findings offer the first assessment of women coaches’ job stressors, strain, and PWB, and offer insight to factors that may influence coaches’ engagement with the profession. They also highlight intervention foci for national governing bodies that are seeking to protect the health and wellbeing of the women coaches within their workforce
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