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2.
Wilderness Environ Med ; 33(4): 429-436, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36244889

RESUMO

INTRODUCTION: The coronavirus disease 2019 (COVID-19) pandemic impacted the ski industry worldwide by closing or limiting access to ski resorts. Subsequently, anecdotal reports of increased backcountry use emerged in the press, with concerns of inexperienced skiers causing or having problems in the backcountry. This study attempted to quantify this and identify motivations for new backcountry skiers. METHODS: Self-identified backcountry skiers and snowboarders (aged ≥18 y) in the United States and Canada completed an anonymous 29-question online survey distributed by regional avalanche centers, education providers, and skiing organizations (n=4792). Respondents were stratified by backcountry experience, defining "newcomers" who began backcountry skiing from 2019 to 2021, coincident with the COVID-19 pandemic. Percentages of ski days spent in the backcountry were compared before and during the COVID-19 pandemic using paired t-tests and across cohorts using repeated-measures analysis of variance. Avalanche education was compared using unpaired χ2 tests. RESULTS: Of established skiers, 81% noticed more people in the backcountry and 27% reported increasing their own use. Participants reported spending 17% (95% CI, 15.8-17.9) more of their days in the backcountry during the COVID-19 pandemic, with newcomers increasing their time spent by 36% and established skiers increasing their time spent by 13% (P<0.0001). Of newcomers, 27% cited the COVID-19 pandemic as motivation to enter the backcountry and 24% lacked formal avalanche education, which is significantly higher than the 14% of established skiers (P<0.0001). CONCLUSIONS: Influenced by factors related to COVID-19, reported backcountry use increased during the pandemic. Newcomers had a lower level of avalanche education and less confidence in evaluating terrain. Because 80% of participants were recruited from avalanche safety or education websites, this likely underestimates skiers lacking avalanche awareness or education and is further limited by the nature of online surveys.


Assuntos
Traumatismos em Atletas , Avalanche , COVID-19 , Esqui , Humanos , COVID-19/epidemiologia , Pandemias , Hábitos
3.
Wilderness Environ Med ; 33(4): 422-428, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36210278

RESUMO

INTRODUCTION: Rapid location of avalanche victims by companions using avalanche transceivers is of utmost importance to prevent asphyxiation. The objective was to determine whether electromagnetic interference from heating elements in gloves worn by rescuers or victims can impair the receiving or transmitting function of avalanche beacons. METHODS: Commercially available heated gloves from 3 different manufacturers were examined during a simulated search with 3 common brands of avalanche transceivers. Distance to target beacon at first signal detection and accuracy of direction to target, as indicated by the arrow from the direction indicator, were evaluated. RESULTS: Preliminary tests showed that transmitting and receiving signals are degraded by electromagnetic interference caused by rectangular pulses emitted by activated heating elements. Field tests revealed significantly reduced distances of first signal detection when heated gloves were turned on near receiving avalanche transceivers (P<0.001; Wilcoxon signed-rank test). Decreased distance to target beacon ranged between 1.9 m (5%) and 41.5 m (94%) at first detection, depending on the avalanche transceiver used. CONCLUSIONS: Avalanche transceivers are susceptible to electromagnetic interference from gloves with electric heating elements. We do not recommend using heated gloves when performing a transceiver search for avalanche victims because it can lead to a delay in rescue.


Assuntos
Avalanche , Humanos , Trabalho de Resgate , Asfixia , Fenômenos Eletromagnéticos
5.
Sci Total Environ ; 848: 157759, 2022 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-35931167

RESUMO

The eastern Mediterranean is a hotspot in terms of geomorphic hazards, but the activity of gravitational processes in mountainous areas is largely unexplored. We carried out dendrogeomorphic research in the Helmos Mountains (Northern Peloponnese, Greece) to determine the timing, spatial extent, and hydrometeorological triggers of debris flows and snow avalanches. Specifically, we sampled increment cores from 123 injured Greek firs (Abies cephalonica L.) growing on a debris flow cone and growing along a snow avalanche track. Tree rings were counted and cross-dated with the reference chronology using CooRecorder and CDendro software and the event years were determined on the basis of the location of scars and traumatic resin ducts. We compiled an 118-year chronology (1904-2021) with seven debris flow event years and only one severe debris flow occurring in the 1970/1971 dormant period (WIt = 148.0), followed by spatially limited records for 1986/1987 (WIt = 3.8) and 1993/1994 (WIt = 2.5). Similarly, seven snow avalanche event years were identified in the period 1854-2021, with one major event in 1997/1998 (WIt = 304.5) followed by the 1998/1999 event (WIt = 6.3). Extremely wet conditions in February-March 1971 followed by rain-on-snow precipitation were considered as the most likely trigger of the analysed debris flow event using data from nearby meteorological stations and the ERA5 reanalysis. The snow avalanche event was deciphered in the spring of 1998, when heavy snowfall over three days (62 cm) was followed by rapid snowmelt due to high average temperatures (6-11 °C). We conclude that the abundance of snow is a crucial factor in the geomorphic activity in the study region and that the temperature fluctuations and rain-to-snow transitions are the leading factors for the debris flows or snow avalanches to occur. Furthermore, the dendrogeomorphic approach used can be useful to clearly identify large-scale geomorphic events and excludes potential geomorphic noise caused by other ecological stresses.


Assuntos
Avalanche , Neve , Grécia , Chuva , Estações do Ano
6.
Chaos ; 32(6): 063121, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35778115

RESUMO

We investigate how the interplay of the topology of the network of load transmitting connections and the amount of disorder of the strength of the connected elements determines the temporal evolution of failure cascades driven by the redistribution of load following local failure events. We use the fiber bundle model of materials' breakdown assigning fibers to the sites of a square lattice, which is then randomly rewired using the Watts-Strogatz technique. Gradually increasing the rewiring probability, we demonstrate that the bundle undergoes a transition from the localized to the mean field universality class of breakdown phenomena. Computer simulations revealed that both the size and the duration of failure cascades are power law distributed on all network topologies with a crossover between two regimes of different exponents. The temporal evolution of cascades is described by a parabolic profile with a right handed asymmetry, which implies that cascades start slowly, then accelerate, and eventually stop suddenly. The degree of asymmetry proved to be characteristic of the network topology gradually decreasing with increasing rewiring probability. Reducing the variance of fibers' strength, the exponents of the size and the duration distribution of cascades increase in the localized regime of the failure process, while the localized to mean field transition becomes more abrupt. The consistency of the results is supported by a scaling analysis relating the characteristic exponents of the statistics and dynamics of cascades.


Assuntos
Avalanche , Simulação por Computador , Probabilidade
7.
Artigo em Inglês | MEDLINE | ID: mdl-35627575

RESUMO

Snowmobilers make a grim and significant contribution to avalanche fatality statistics in Norway. However, there is limited knowledge on the behavior of this group in avalanche terrain and the factors influencing this behavior. Our study documents what snowmobilers do and not do in avalanche terrain, how their behavior relates to managing complex avalanche conditions and if there is a mismatch between avalanche competence, education and riding preferences. This ethnographic study observed snowmobiler tracks and thus avalanche terrain usage in Northern Norway during 2018 and 2019, supported by open-ended conversations with target group riders. Results show that high-marking lost popularity to technical riding, which seems to be perceived as safer despite increased exposure to complex avalanche terrain and conditions with persistent weak layers in the snowpack. The detected mismatch between preferences and avalanche knowledge/attitude will remain an obstacle to future accident prevention efforts unless behavioral changes are addressed. This study of a predominantly illegal activity sheds light on how to explore and observe hard-to-reach illegal activities and should be of interest to a wider audience from other research disciplines.


Assuntos
Avalanche , Esportes na Neve , Prevenção de Acidentes , Comunicação , Noruega
8.
Artigo em Inglês | MEDLINE | ID: mdl-35564653

RESUMO

Snow sports in the backcountry have seen a steep increase in popularity, and therefore preparedness for efficient companion and organized rescue is important. While technical rescue skills are widely taught, there is a lack of knowledge regarding first aid for avalanche patients. The stressful and time-critical situation for first responders requires a rule-based decision support tool. AvaLife has been designed from scratch, applying mathematical and statistical approaches including Monte Carlo simulations. New analysis of retrospective data and large prospective field test datasets were used to develop evidence-based algorithms exclusively for the avalanche rescue environment. AvaLife differs from other algorithms as it is not just a general-purpose CPR algorithm which has been slightly adapted for the avalanche patient. The sequence of actions, inclusion of the ≥150 cm burial depth triage criterion, advice to limit CPR duration for normothermic patients to 6 min in case of multiple burials and shortage of resources, criteria for using recovered subjects as a resource in the ongoing rescue, the adapted definition of "injuries incompatible with life", reasoning behind the utmost importance of rescue breaths, as well as the updated BLS-iCPR algorithm make AvaLife useful in single and multiple burial rescue. AvaLife is available as a companion rescue basic life support (BLS) version for the recreational user and an advanced companion and organized rescue BLS version for guides, ski patrols and mountain rescuers. AvaLife allows seamless interoperability with advanced life support (ALS) qualified medical personnel arriving on site.


Assuntos
Avalanche , Acidentes , Asfixia , Primeiros Socorros , Humanos , Estudos Prospectivos , Estudos Retrospectivos
9.
Wilderness Environ Med ; 33(2): 197-203, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35491311

RESUMO

INTRODUCTION: While avalanche fatalities have remained relatively steady per year, data suggest a possible increase in sidecountry use and snowmobile fatalities. Limited information is known regarding the accident details and preparedness among different groups of backcountry users including snowmobiles, sidecountry, and backcountry skiers, and what specific factors could contribute to their fatalities. METHODS: Avalanche fatality reports covering all US states posted by the Colorado Avalanche Information Center available online for 10 seasons (2009-2010 through 2018-2019 seasons) were analyzed for group size, specific equipment carried, burial depth, burial time, and other details. Only reports in the 3 following categories were included in the analysis: backcountry ski/snowboard, sidecountry ski/snowboard, and snowmobile/snowbike. These aspects were compared among the 3 tourer types using statistical analyses (ANOVA). RESULTS: Two hundred and five fatalities were analyzed (n=32 sidecountry, n=91 skier/snowboard, n=82 snowmobile/snowbike). Using 2 preparedness scores, the ski/snowboard group had the greatest distribution of high scores when evaluated by equipment carried and group size, with significant differences per group (P<0.01). Of the fatalities that were buried, burial time was related to the tourer group (P=0.04), with the ski/snowboard group having the highest proportion of burials <15 min. Burial depth was significantly different among the 3 tourer groups, with snowmobiles buried the deepest on average (P<0.01). CONCLUSIONS: Despite limited data available on fatalities, an analysis of preparedness suggests that backcountry skiers and snowboarders are more prepared for avalanche accidents compared to snowmobiles and sidecountry users when evaluated by equipment carried and group size.


Assuntos
Avalanche , Veículos Off-Road , Esqui , Acidentes , Colorado/epidemiologia , Estações do Ano , Estados Unidos/epidemiologia
10.
Sci Total Environ ; 836: 155380, 2022 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-35489509

RESUMO

Upsurge of glacier-related hazards in High Mountain Asia (HMA) has been evident in recent years due to global warming. While many glacial-related hazards are instantaneous, some large landslides were preceded by slow gravitational deformation, which can be predicted to evade catastrophes. Here, we present robust evidence of historical deformation in 2021 Chamoli rock-ice avalanche of Himalaya using space imaging techniques. Multi-temporal satellite data provide evidence of a precursor event in 2016 and expansion of a linear fracture along joint planes, indicating 2021 rock-ice avalanche is a retrogressive wedge failure. The deformation history shows that the fracture propagated at a velocity of ~0.07 m day-1 until September 2020, and with an accelerated velocity (~0.14 m day-1 on average) lately. Analysis of recent similar cases in HMA supported our inference on global warming-induced glacier retreat and thermomechanical effects in enhancing the weakening of fractured rock masses in tectonically active mountain belts. Recent advances in Earth observation and seismic monitoring system can offer clues to the location and timing of impending catastrophic failures in high mountain regions.


Assuntos
Avalanche , Deslizamentos de Terra , Ásia , Aquecimento Global , Camada de Gelo
11.
Resuscitation ; 174: 47-52, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35341911

RESUMO

INTRODUCTION: We aimed to investigate the relationship between the time of the day and the probability of survival of completely buried avalanche victims. We explored the frequency of avalanche burials occurring after sunset, and described victims' characteristics, duration of burial and rescue circumstances compared to daytime avalanches. METHODS: In this retrospective, observational study, we analysed avalanche data from the registry of the Swiss Institute for Snow and Avalanche Research, from 1998 to 2020. RESULTS: A total of 3892 avalanche victims were included in the analysis, with 72 of the accidents (1.85%) occurring in the nighttime. Nearly 50% of the victims involved in nighttime avalanche accidents were completely buried, compared to about 25% of victims in daytime avalanches. Completely buried victims were rescued by a companion less often at night than in the daytime (15% vs. 51%, p <.001). The search and rescue of completely buried avalanche victims took longer during the nighttime compared to the daytime (median 89 min vs 20 min, p =.002). The probability of survival decreased as the day progressed; it was highest at around midday (63.0%), but decreased at sunset (40.4%) and was the lowest at midnight (28.7%). CONCLUSIONS: Avalanche accidents at night are a rare event, and probability of survival after complete burial is lower during the nighttime compared to the daytime. The most relevant reason for this is the longer duration of burial, which is explained in part by the lower rate of companion rescue and the lower rate of victim localisation with an avalanche transceiver.


Assuntos
Avalanche , Acidentes , Humanos , Estudos Retrospectivos , Fatores de Tempo
12.
High Alt Med Biol ; 23(2): 114-118, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35263173

RESUMO

DeLoughery, Emma P. and Thomas G. DeLoughery. Review and Analysis of Mountaineering Accidents in the United States from 1947-2018. High Alt Med Biol. 23:114-118, 2022. Introduction: Given the popularity of mountaineering, it is important to better understand accidents related to this sport. We undertook this review of accidents to better understand the demographics and locations involved in mountaineering accidents over 71 years. Methods: Data collected from "Accidents in North American Mountaineering" booklets from 1947 to 2018 included the date, state and location of the accident, sex and age of the victim, type of accident, injuries sustained, and distance fallen if a fall occurred. If at least 10 accidents occurred in an individual state and/or location, these sites were separately analyzed. Results: From 1947 to 2018, 2,799 people were reported to be involved in mountaineering accidents, and 43% of these accidents resulted in death. Women were involved in 12% of cases. Falls were the most common accident (68% incidence, 45% fatal), followed by falling rock (7%, 26% fatal), avalanche (6%, 75% fatal), and falling into a crevasse (2%, 52% fatal). The average age of victims was 30 years. California had the most accidents (18%), followed by Washington (16%) and Alaska (15%). Denali had the greatest frequency of both accidents and deaths (11%, 8% of deaths), followed by Mount Rainier (6%, 7% of deaths) and Mount Hood (2%, 3% of deaths). Conclusions: Accident victims tend to be young and predominantly male, and the accidents themselves are most often falls. Avalanches were identified as an accident cause with a high fatality rate.


Assuntos
Avalanche , Montanhismo , Acidentes por Quedas , Acidentes , Adulto , Feminino , Humanos , Incidência , Masculino , Montanhismo/lesões , Estados Unidos/epidemiologia
13.
PLoS Comput Biol ; 18(3): e1009952, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35303738

RESUMO

Epithelial tissues constitute an exotic type of active matter with non-linear properties reminiscent of amorphous materials. In the context of a proliferating epithelium, modeled by the quasistatic vertex model, we identify novel discrete tissue scale rearrangements, i.e. cellular rearrangement avalanches, which are a form of collective cell movement. During the avalanches, the vast majority of cells retain their neighbors, and the resulting cellular trajectories are radial in the periphery, a vortex in the core. After the onset of these avalanches, the epithelial area grows discontinuously. The avalanches are found to be stochastic, and their strength is correlated with the density of cells in the tissue. Overall, avalanches redistribute accumulated local spatial pressure along the tissue. Furthermore, the distribution of avalanche magnitudes is found to obey a power law, with an exponent consistent with sheer induced avalanches in amorphous materials. To understand the role of avalanches in organ development, we simulate epithelial growth of the Drosophila eye disc during the third instar using a computational model, which includes both chemical and mechanistic signaling. During the third instar, the morphogenetic furrow (MF), a ~10 cell wide wave of apical area constriction propagates through the epithelium. These simulations are used to understand the details of the growth process, the effect of the MF on the growth dynamics on the tissue scale, and to make predictions for experimental observations. The avalanches are found to depend on the strength of the apical constriction of cells in the MF, with a stronger apical constriction leading to less frequent and more pronounced avalanches. The results herein highlight the dependence of simulated tissue growth dynamics on relaxation timescales, and serve as a guide for in vitro experiments.


Assuntos
Avalanche , Drosophila , Animais , Epitélio , Morfogênese , Transdução de Sinais
14.
Hum Brain Mapp ; 43(8): 2534-2553, 2022 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-35146831

RESUMO

The critical brain hypothesis suggests that efficient neural computation can be achieved through critical brain dynamics. However, the relationship between human cognitive performance and scale-free brain dynamics remains unclear. In this study, we investigated the whole-brain avalanche activity and its individual variability in the human resting-state functional magnetic resonance imaging (fMRI) data. We showed that though the group-level analysis was inaccurate because of individual variability, the subject wise scale-free avalanche activity was significantly associated with maximal synchronization entropy of their brain activity. Meanwhile, the complexity of functional connectivity, as well as structure-function coupling, is maximized in subjects with maximal synchronization entropy. We also observed order-disorder phase transitions in resting-state brain dynamics and found that there were longer times spent in the subcritical regime. These results imply that large-scale brain dynamics favor the slightly subcritical regime of phase transition. Finally, we showed evidence that the neural dynamics of human participants with higher fluid intelligence and working memory scores are closer to criticality. We identified brain regions whose critical dynamics showed significant positive correlations with fluid intelligence performance and found that these regions were located in the prefrontal cortex and inferior parietal cortex, which were believed to be important nodes of brain networks underlying human intelligence. Our results reveal the possible role that avalanche criticality plays in cognitive performance and provide a simple method to identify the critical point and map cortical states on a spectrum of neural dynamics, ranging from subcriticality to supercriticality.


Assuntos
Avalanche , Memória de Curto Prazo , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Humanos , Inteligência , Imageamento por Ressonância Magnética
15.
Artigo em Inglês | MEDLINE | ID: mdl-35162119

RESUMO

Throughout history, accidental hypothermia has accompanied natural disasters in cold, temperate, and even subtropical regions. We conducted a non-systematic review of the causes and means of preventing accidental hypothermia after natural disasters caused by avalanches, earthquakes, tsunamis, and floods. Before a disaster occurs, preventive measures are required, such as accurate disaster risk analysis for given areas, hazard mapping and warning, protecting existing structures within hazard zones to the greatest extent possible, building structures outside hazard zones, and organising rapid and effective rescue. After the event, post hoc analyses of failures, and implementation of corrective actions will reduce the risk of accidental hypothermia in future disasters.


Assuntos
Avalanche , Terremotos , Hipotermia , Inundações , Humanos , Hipotermia/prevenção & controle , Japão , Tsunamis
16.
Phys Med Biol ; 67(4)2022 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-35171115

RESUMO

An avalanche photodiode (APD)-based small animal positron emission tomography (PET)-insert was fully evaluated for its PET performance, as well as potential influences on magnetic resonance imaging (MRI) performance. This PET-insert has an extended axial field of view (FOV) compared with the previous design to increase system sensitivity, as well as an updated cooling and temperature regulation to enable stable and reproducible PET acquisitions. The PET performance was evaluated according to the National Electrical Manufacturers Association NU4-2008 protocol. The energy and timing resolution's full width at half maximum were 16.1% and 4.7 ns, respectively. The reconstructed radial spatial resolution of the PET-insert was 1.8 mm full width at half maximum at the center FOV using filtered back projection for reconstruction and sensitivity was 3.68%. The peak noise equivalent count rates were 70 kcps for a rat-like and 350 kcps for a mouse-like phantom, respectively. Image quality phantom values and contrast recovery were comparable to state-of-the art PET-inserts and standalone systems. Regarding MR compatibility, changes in the mean signal-to-noise ratio for turbo spin echo and echo-planar imaging sequences were below 8.6%, for gradient echo sequences below 1%. Degradation of the mean homogeneity was below 2.3% for all tested sequences. The influence of the PET-insert on theB0maps was negligible and no influence on functional MRI sequences was detected. A mouse and rat imaging study demonstrated the feasibility ofin vivosimultaneous PET/MRI.


Assuntos
Avalanche , Animais , Imageamento por Ressonância Magnética/veterinária , Camundongos , Imagens de Fantasmas , Tomografia por Emissão de Pósitrons/veterinária , Ratos , Tomografia Computadorizada por Raios X
17.
Sci Rep ; 12(1): 2070, 2022 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-35136116

RESUMO

Outdoor breathing trials with simulated avalanche snow are fundamental for the research of the gas exchange under avalanche snow, which supports the development of the international resuscitation guidelines. However, these studies have to face numerous problems, including unstable weather and variable snow properties. This pilot study examines a mineral material perlite as a potential snow model for studies of ventilation and gas exchange parameters. Thirteen male subjects underwent three breathing phases-into snow, wet perlite and dry perlite. The resulting trends of gas exchange parameters in all tested materials were similar and when there was a significant difference observed, the trends in the parameters for high density snow used in the study lay in between the trends in dry and wet perlite. These findings, together with its stability and accessibility year-round, make perlite a potential avalanche snow model material. Perlite seems suitable especially for simulation and preparation of breathing trials assessing gas exchange under avalanche snow, and potentially for testing of new avalanche safety equipment before their validation in real snow.The study was registered in ClinicalTrials.gov on January 22, 2018; the registration number is NCT03413878.


Assuntos
Óxido de Alumínio , Avalanche , Troca Gasosa Pulmonar/fisiologia , Respiração , Dióxido de Silício , Neve , Adulto , Reanimação Cardiopulmonar/métodos , Estudos Cross-Over , República Tcheca , Método Duplo-Cego , Humanos , Masculino , Modelos Teóricos , Projetos Piloto , Estudos Prospectivos , Treinamento por Simulação , Adulto Jovem
20.
PLoS One ; 17(2): e0264033, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35167595

RESUMO

With ongoing global warming, snow avalanche dynamics may change as snow cohesion and friction strongly depend on temperature. In the field, a diversity of avalanche flow regimes has been reported including fast, sheared flows and slow plugs. While the significant role of cohesion and friction has been recognized, it is unclear how these mechanical properties affect avalanche flow regimes. Here, we model granular avalanches on a periodic inclined plane, using the distinct element method to better understand and quantify how inter-particle cohesion and ground friction influences avalanche velocity profiles. The cohesion between particles is modeled through bonds that can subsequently break and form, thus representing fragmentation and aggregation potentials, respectively. The implemented model shows a good ability to reproduce the various flow regimes and transitions as observed in nature: for low cohesion, highly sheared and fast flows are obtained while slow plugs form above a critical cohesion value and for lower ground frictions. Simulated velocity profiles are successfully compared to experimental measurements from the real-scale test site of Vallée de la Sionne in Switzerland. Even though the model represents a strong simplification of the reality, it offers a solid basis for further investigation of relevant processes happening in snow avalanches, such as segregation, erosion and entrainment, with strong impacts on avalanche dynamics research, especially in a climate change context.


Assuntos
Avalanche , Simulação por Computador , Fricção , Aquecimento Global , Fenômenos Mecânicos , Modelos Teóricos , Suíça
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