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991.
The risk of both severe and frequent injury associated with active pursuits in mountain areas is acknowledged. This phenomenon is all the most relevant to investigate in France that there is a growing enthusiasm for outdoor sports and recreation. This paper focuses on the social-demographic and sporting profiles of accident victims. Our intent is to better understand who is specifically at risk, while practicing mountain recreation, in the French mountains. Such identification doubtlessly constitutes an important asset in order to enhance prevention. Three critical activities are notably tackled, among some others: hiking, a widespread activity that exposes many practitioners to hazardous settings; mountaineering and ski touring, supposedly entailing the most severe injuries. In order to align the information collected, then provide estimations based on the reasoned crossing of these secondary data, we consulted and summarised all the databases that we knew of on the French territory: rescue team intervention reports, aggregated statistics from the sports ministry, sporting federation accident declarations, avalanche experts statistics, mountain guides union accident/incident reports, healthcare facilities admissions, etc. Only the sources considered to be the most reliable and representative were used, owing to the number of cases processed, the exhaustive nature of data collection, or the level of information detail available. Our method also included consultation of all the parties playing an active role in prevention, training and mountain rescue, thus ensuring a participative, co-constructive approach to the study with the people that have the best knowledge of victims’ profiles. Around fifty such parties were interviewed on the methods implemented, the benefits and limits of current data, and the main expectations in terms of accidentology progress, thus further enhancing the credibility of the study proposed in this paper. Our results show that the parent population profiles (in terms of age, gender, place of residence, etc.), weighted by the level of exposure (frequency of participation, level of engagement, etc.) appears to have an impact on the accident victim profiles. There is certainly a very marked gender bias and a serious age impact to be taken into account, as well as the influence of the level of experience, which counter certain preconceived ideas and which, at the very least, go against instinct. However, aside from a probable over-exposure of experienced or expert participants, much remains to be explained concerning the accident mechanisms and circumstances involved. At this stage, we regret the analytic deficiencies induced by a lack of knowledge concerning the parent populations in many cases, which makes interpretation difficult. 相似文献
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994.
Samanta Manon Lax Eric Wade Peterson Stephen J. Van der Hoven 《Environmental Earth Sciences》2017,76(20):708
The concentration of chloride (Cl?) in streams in northern regions has increased as a result of applications of deicers. This study focused on quantifying the relationship between land use and stream Cl? concentrations. The study area comprises two adjacent watersheds in central Illinois, with similar geology and climate but different land uses (agricultural and urban). GIS analysis delineated watershed land use and calculated road surface areas. Stream water samples were collected and analyzed for anionic composition. During the winter months, streams dominated with urban land use experienced a 20-fold increase in Cl? concentrations (range between 36 and 1350 mg L?1); Cl? concentrations in agricultural dominated streams also increased, but the increase was smaller (3X) and concentrations remained low (between 11 and 58 mg L?1). As road salts are not the sole source of Cl? in a stream, Cl? and bromide (Br?) mass ratios (Cl/Br) and Cl? and sodium (Na) molar ratios ([Cl]/[Na]) were used to identify potential sources of Cl?. The ratios indicate urbanized watersheds were impacted by road salts; agricultural watersheds ratios indicate other anthropogenic sources. A nonlinear relationship between urban land use and stream Cl? concentrations indicates urban land use as low as 23% results in elevated Cl? concentrations (greater than 150 mg L?1) in stream waters. 相似文献
995.
Eric N. Powell 《Estuaries and Coasts》2017,40(1):105-120
The National Oceanic and Atmospheric Administration (NOAA) Status and Trends Mussel Watch Program sampled the largest oysters in nearly every major US coastal lagoon and estuary in the Gulf of Mexico once during the winter from 1986 to 2010. This contribution examines trends in the principal oyster disease in the Gulf of Mexico, Dermo, caused by Perkinsus marinus, and some related population dynamic characteristics for its host, Crassostrea virginica. During the 1986–2000 period, P. marinus prevalence and infection intensity and oyster population dynamics followed the El Niño-Southern Oscillation (ENSO) cycle, responding to variations in salinity caused by variations in rainfall and freshwater inflow. The ENSO signal in the oyster population effectively ceased circa 2002. Beginning around this time, wintertime P. marinus prevalence and weighted prevalence began a decadal decline, as did the length of the largest oysters and the fraction of these largest animals that were female. The trends in Dermo disease, oyster length, and oyster sex ratio are all consistent with the following hypothesis: increasing temperature during the 2000s resulted in an increase in P. marinus infection intensity sufficient to increase the mortality rate in late summer and fall in the larger animals. This simultaneously reduced Dermo prevalence and infection intensity in the winter at the time of sampling and also resulted in the decline in the length of the largest animals targeted by Mussel Watch. Coincident with the decline in length is the expected decline in the fraction female, such that the percent female in the largest animals dropped to ≤50 % throughout much of the Gulf of Mexico. The decline in length leading to fewer large animals reproducing and the loss of females are predicted to have reduced oyster population reproductive capacity substantially during the 2000s. The early 60 % of the Mussel Watch time series took place during a period of negative Atlantic Multidecadal Oscillation (AMO) indices. The AMO moved into positive territory circa 2000. A positive AMO index is consistent with observed warmer water temperatures, and increased water temperature is consistent with an increase in Dermo-induced mortality. 相似文献
996.
997.
Olivier Gourgue Richard ComblenJonathan Lambrechts Tuomas KärnäVincent Legat Eric Deleersnijder 《Advances in water resources》2009
We present a flux-limiting wetting–drying approach for finite-element discretizations of the shallow-water equations using discontinuous linear elements for the elevation. The key ingredient of the method is the use of limiters for generalized nodal fluxes. This method is implemented into the Second-generation Louvain-la-Neuve Ice-ocean Model (SLIM), and is verified against standard test cases. The method is further applied to the wetting and drying of sand banks in the Scheldt Estuary, which is located in northern Belgium and the southern Netherlands. The results obtained for both the benchmarks and the realistic problem illustrate the accuracy of the method in describing the hydrodynamics in the vicinity of dry areas. In particular, the method strictly conserves mass, and there is no transport through dry areas. 相似文献
998.
Eric Tabacchi Johannes Steiger Dov Corenblit Michael T. Monaghan Anne-Marie Planty-Tabacchi 《Aquatic Sciences - Research Across Boundaries》2009,71(3):279-289
The structure and function of alluvial Highly Dynamic River Systems (HDRS) are driven by highly variable hydrological disturbance
regimes, and alternate between resistant, metastable states and resilient, transitional states. These are in turn subject
to influences of feedback loops within hydrogeomorphic and biological processes. Here we consider how resistance and resilience
largely determine HDRS ecosystem trajectories and how these characteristics can be modified by natural and anthropogenic processes.
We review the mechanisms by which biodiversity can affect both resistance and resilience and introduce a conceptual framework
that incorporates some unique HDRS characteristics. We suggest that resilient and resistant patterns frequently coexist in
the active tract of these river systems, and that this coexistance promotes the return of metastable states after major disturbances.
In contrast, highly resistant and poorly resilient patterns dominate at their external boundaries. The loss of these natural
dynamics resulting from direct and indirect human impacts causes deviations to resistance and resilience patterns and therefore
to HDRS trajectory. We propose that understanding the role of interactions between biological and physical processes that
control resistance and resilience is crucial for system restoration and management. 相似文献
999.
Ozgur Bozkurt Kelly G. Pennell Eric M. Suuberg 《Ground Water Monitoring & Remediation》2009,29(1):92-104
This paper presents model simulation results of vapor intrusion into structures built atop sites contaminated with volatile or semivolatile chemicals of concern. A three-dimensional finite element model was used to investigate the importance of factors that could influence vapor intrusion when the site is characterized by nonhomogeneous soils. Model simulations were performed to examine how soil layers of differing properties alter soil-gas concentration profiles and vapor intrusion rates into structures. The results illustrate difference in soil-gas concentration profiles and vapor intrusion rates between homogeneous and layered soils. The findings support the need for site conceptual models to adequately represent a site's geology when conducting site characterizations, interpreting field data, and assessing the risk of vapor intrusion at a given site. For instance, in layered geologies, a lower permeability and diffusivity soil layer between the source and building often limits vapor intrusion rates, even if a higher permeability layer near the foundation permits increased soil-gas flow rates into the building. In addition, the presence of water-saturated clay layers can considerably influence soil-gas concentration profiles. Therefore, interpreting field data without accounting for clay layers in the site conceptual model could result in inaccurate risk calculations. Important considerations for developing more accurate conceptual site models are discussed in light of the findings. 相似文献
1000.
Computational fluid dynamics (CFD) techniques are widely adopted to simulate the behavior of fire. However, CFD suffers from
the shortcoming of requiring extensive computer storage and a lengthy computational time. In practical applications, although
comprehensive field information on velocities, temperatures, pressure, and the fractions of different constitutes can be obtained
from CFD simulations, the user may only be interested in few important parameters that index the performance of a compartment
design in the event of a fire. The height of the thermal interface (HTI) is one such key index, and refers to the average
height above floor level inside a fire compartment at which the temperature gradient is highest. In practice, a fire compartment
is considered untenable when the HTI drops below the respiratory level of the occupants, and in optimizing the design of a
fire system, another set of design parameters (e.g., the width of the door opening) must be examined if the HTI of a fire
compartment design is evaluated by CFD as being too low. This trial and error exercise then continues until a close to optimum
set of design parameters is achieved. This approach is theoretically feasible, but requires lengthy computational time. This
paper proposes the application of an Artificial Neural Network (ANN) approach as a fast alternative to CFD models to simulate
the behavior of a compartment fire. A novel ANN model named GRNNFA has been specially developed for fire studies. It is a
hybrid ANN model that combines the General Regression Neural Network (GRNN) and Fuzzy ART (FA). The GRNNFA model features
a network structure that grows incrementally, stable learning, and the absence of the noise embedded in experimental fire
data. It has been employed to establish a system response surface based on the training samples collected from a full-scale
experiment on compartment fire. However, as the available training samples may not be sufficient to describe the behavior
of all systems, and especially those involving fire data, this paper proposes that extra knowledge be acquired from human
experts. Human expert network training has thus been developed to remedy established system response surface problems. After
transforming the remedied system response surface to the problem domain, a Genetic Algorithm (GA) is applied to evaluate the
close to optimum set of design parameters. 相似文献