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At least 901 records · Page 50Linked to original sources
PubMed2005

Dynamics of the in-run in ski jumping: a simulation study.

A ski jumper tries to maintain an aerodynamic position in the in-run during changing environmental forces. The purpose of this study was to analyze the mechanical demands on a ski jumper taking the in-run in a static position. We simulated the in-run in ski jumping with a 4-segment forward dynamic model (foot, leg, thigh, and upper body). The curved path of the in-run was used as kinematic constraint, and drag, lift, and snow friction were incorporated. Drag and snow friction created a forward rotating moment that had to be counteracted by a plantar flexion moment and caused the line of action of the normal force to pass anteriorly to the center of mass continuously. The normal force increased from 0.88 G on the first straight to 1.65 G in the curve. The required knee joint moment increased more because of an altered center of pressure. During the transition from the straight to the curve there was a rapid forward shift of the center of pressure under the foot, reflecting a short but high angular acceleration. Because unrealistically high rates of change of moment are required, an athlete cannot do this without changing body configuration which reduces the required rate of moment changes.

Friction↗
PubMed1987

Radioactive cesium from the Chernobyl accident in the Greenland Ice Sheet.

Measurements of cesium-134 and cesium-137 in Greenland snow together with models of long-range transport have been used to assess radionuclide deposition in the Arctic after the Chernobyl accident. The results suggest that a well-defined layer of radioactive cesium is now present in polar glaciers, providing a new reference for estimating snow accumulation rates and dating ice core samples.

Accidents↗
PubMed1998

Lightning injuries during snowy conditions.

Skiers and other snow sports enthusiasts can become lightning casualties. Two such accidents are reported, one being fatal. There are fewer warning signals of impending lightning strikes in winter-like conditions. However, outdoor activists should be aware of at least two suspicious clues: the appearance of convective clouds, and the presence of graupel (snow pellets) during precipitation.

Adult↗
PubMed2006

Emergency department visits for sledding injuries in children in the United States in 2001/2002.

OBJECTIVES: To describe the characteristics of nonfatal sledding-related injuries in U.S. children resulting in emergency department (ED) visits in 2001/2002 and to explore the implications of these findings for injury prevention efforts. METHODS: A stratified probability sample of U.S. hospitals providing emergency services in the National Electronic Injury Surveillance System-All Injury Program was utilized for 2001/2002. ED visits resulting from injuries involving sleds, snow discs, snow tubes, and toboggans were analyzed for patients 19 years of age or younger. RESULTS: In 2001/2002, there were an estimated 57,866 ED visits for sledding-related injuries in the United States for all age groups. Of these, 41,272 (71%) occurred in patients 19 years of age or younger, 58% of whom were male. The highest number of injuries occurred in children between five and 14 years of age (74%), and the injuries were most often caused by falls or collisions (75%). The head or neck was the most frequently injured body region among those 0-9 years of age, while the extremities were injured most commonly among those 10-19 years of age. Head and neck injuries occurred in 56% (95% confidence interval [CI] = 32% to 81%) of children 0-4 years of age versus 19% (95% CI = 9% to 29%) of patients 15-19 years of age. Nine percent (95% CI = 6% to 12%) of patients sustained a traumatic brain injury. Three percent (95% CI = 1% to 5%) of patients required admission to the hospital. CONCLUSIONS: Sledding injuries resulting in ED visits predominantly affect children and are a source of measurable morbidity in this population. An increase in injury prevention efforts for this activity is warranted.

Adolescent↗
PubMed2006

Quantifying dispersal and establishment limitation in a population of an epiphytic lichen.

Dispersal is a process critical for the dynamics and persistence of metapopulations, but it is difficult to quantify. It has been suggested that the old-forest lichen Lobaria pulmonaria is limited by insufficient dispersal ability. We analyzed 240 DNA extracts derived from snow samples by a L. pulmonaria-specific real-time PCR (polymerase chain reaction) assay of the ITS (internal transcribed spacer) region allowing for the discrimination among propagules originating from a single, isolated source tree or propagules originating from other locations. Samples that were detected as positives by real-time PCR were additionally genotyped for five L. pulmonaria microsatellite loci. Both molecular approaches demonstrated substantial dispersal from other than local sources. In a landscape approach, we additionally analyzed 240 snow samples with real-time PCR of ITS and detected propagules not only in forests where L. pulmonaria was present, but also in large unforested pasture areas and in forest patches where L. pulmonaria was not found. Monitoring of soredia of L. pulmonaria transplanted to maple bark after two vegetation periods showed high variance in growth among forest stands, but no significant differences among different transplantation treatments. Hence, it is probably not dispersal limitation that hinders colonization in the old-forest lichen L. pulmonaria, but ecological constraints at the stand level that can result in establishment limitation. Our study exemplifies that care has to be taken to adequately separate the effects of dispersal limitation from a limitation of establishment.

DNA, Fungal↗
PubMedDate not supplied

Climatic and agricultural contributions to changing loads in two watersheds in Ohio.

Trends in climatic variables, streamflow, agricultural practices, and loads of nutrients and suspended solids were estimated for 1976-1995 in the Maumee and Sandusky watersheds, two large agricultural basins draining to Lake Erie. To understand the contributions that various factors may have made to the trends in loads, earlier results of models linking loads to explanatory variables were combined with estimated trends in those variables. The study period was characterized by increases in temperature, wintertime precipitation and streamflow, conservation farming, and loads of nitrate and total suspended solids; decreases in snowfall and snow cover, fertilizer, manure from livestock, and loads of soluble reactive phosphorus; and relatively steady exports of total phosphorus. After removing the effects of trends in streamflow, nitrate loads increased much less while total suspended solids and total phosphorus loads declined. The analysis suggests that the nitrate increases were due largely to climatic factors, particularly increases in winter streamflow, decreases in snowfall and snow cover, and declining annual precipitation. Decreases in soluble reactive phosphorus were associated with changes in agricultural practices, particularly declines in fertilizer deliveries and head of livestock.

Agriculture↗
PubMed2002

[2001 survey of pollen in Wakayama City with a real-time pollen counter].

Self-care is gradually being recognized as important in the treatment of pollinosis, based up to now on data on airborne pollen. To determine the real-time numbers of airborne pollen would be more useful in self-care, however, so we studied the usefulness of the real-time pollen counter. Between Feb. 2, 2001, and Apr. 26, 2001, 4 types of airborne pollen i.e., Japanese cedar, Japanese cypress, black alder, and beech observed in Wakayama City were counted with a Durham pollen counter and a real-time pollen counter (Yamato Manufacturing Co. Ltd.). Correlation between the 2 pollen counters was r = 0.69 for Japanese cedar in March and r = 0.89 for Japanese cypress in April. A high correlation was observed between outcomes of the 2 pollen counters. The amount of pollen from black alder and beech was less than that from Japanese cedar and cypress. Unexpected peaks were observed not related to the pollen number is apparently due to snow. We have taken measure against snow, so we concluded that the real-time pollen counter was useful in counting the amount of airborne pollen over time.

Air Pollutants↗
PubMed1997

Impact of light regimes on productivity patterns of benthic microbial mats in an antarctic lake: a modeling study.

Filamentous cyanobacteria often dominate benthic microbial communities of antarctic lakes and usually exhibit saturation of photosynthesis at light intensities approximately 100 microEinst m-2 s-1. Incident light regimes are controlled by ice and snow accumulations overlaying water columns during much of the year. Thus, light availability to microbial mats is often below saturation intensity and is strongly influenced by modest changes in climatic factors. A model of net primary production for benthic mat communities of the subantarctic Sombre Lake, Signy Island, was developed (1) to evaluate depth-specific productivities of mat communities, (2) to test the relative importances of model parameters to mat production, and (3) to explore the potential impacts of climate change on mat production as manifested through changes in light regime. Simulated rates of net primary production corresponded to observations on a daily basis (approximately 1-4 micrograms C fixed mg-1 ash-free DW of mat d-1) but were an order of magnitude lower than estimates of net annual production based on field measurements (< or = 3 vs. 11-45 g C m-2 yr-1, respectively). Close examination suggested that the simulated values were more plausible. A detailed sensitivity analysis of model behavior revealed that variations in the time of ice and snow melt in spring accounted for 40-60% of the total variation in model behavior, emphasizing the importance of climatic factors to net primary production of mat communities and the sensitivity of mat production to climate change.

Antarctic Regions↗
PubMed2001

Non-point pollution of Ishikari river, Hokkaido, Japan.

We researched the Ishikari river, Japan's second-longest river, to clarify the characteristics of non-point pollution by comparing flux characteristics of chemical components in three periods of one year: the snow melting period, the typhoon flooding period and the stable period. We found non-point pollutants present in great amounts because a large amount of suspended matter, which is contained in soil, flows into the river and concentrations of nutrients and organic matters do not decrease in a short time in the flooding period by rain and in the snow melting period.

Disasters↗
PubMedDate not supplied

[The sanitary status of natural waters on the territory of Moscow (according to the results of the examination of chemical and radionuclide composition)].

The paper presents the results of examination of the chemical and radionuclide composition of natural waters and snow cover in Moscow. Areas with abnormal contents of tritium are found in the underground and surface waters and snow cover. The high concentrations of strontium, boron, fluorine, and barium are ascertained to be associated with natural factors. Areas of technogenically polluted underground waters are identified. Recommendations are given for further studies. Particular emphasis is laid on that the artesian wells that are a reservoir source of water supply under emergency are to be revised.

Barium↗
PubMed1990

Immunolocalization of heparan sulfate proteoglycans to the prion protein amyloid plaques of Gerstmann-Straussler syndrome, Creutzfeldt-Jakob disease and scrapie.

Previous histochemical studies have demonstrated highly sulfated glycosaminoglycans (GAGs) localized to the amyloid plaques in the brains of humans and animals with prion diseases (Snow et al., Acta Neuropathol 77:337, 1989). However, the identity of the specific class of proteoglycan/GAG present was not known. The current investigation used immunocytochemical techniques to identify and localize heparan sulfate proteoglycans (HSPGs) in human cases of Gerstmann-Straussler syndrome and Creutzfeldt-Jakob disease, as well as in experimental scrapie of hamsters. Polyclonal and monoclonal antibodies to either the protein core or GAG moiety of the basement membrane-derived HSPG were utilized. The results demonstrate that both the protein core and the GAG chains of HSPGs are immunolocalized to the prion protein amyloid plaques in each of these diseases. HSPG immunostaining was also evident in these tissues in blood vessels, choroid plexus, myelinated axons, and in the cytoplasm of certain neuronal and astrocytic populations, particularly those in close proximity to the amyloid plaques. Additionally, in Creutzfeldt-Jakob disease and Gerstmann-Straussler syndrome cerebellum, positive immunostaining for heparan sulfate GAGs was observed within the cell bodies of Purkinje cells. The specific accumulation of HSPGs in the amyloid deposits of both the prion diseases and Alzheimer's disease (Snow et al., Am J Pathol 133:456, 1988), suggests that a common mechanism involving HSPGs may occur in the pathogenesis of amyloidosis in each of these diseases.

Amyloid↗
PubMedDate not supplied

Surveillance for injuries: cluster of finger amputations from snowblowers.

In an investigation of the health effects of a Christmas eve snowstorm in 1982, a review of emergency room records in the Denver area identified a cluster of 17 cases of finger amputations. Fifteen (88) percent of these amputations were associated with snowblower use. An additional 12 persons with hand or finger injuries without amputations from snowblowers were identified. A case-control study was performed comparing these patients with a control group who had used snowblowers. Patients were more likely than controls to have had their machines become clogged with snow (odds ratio [OR], 3.4, 95 percent confidence limits [CL], 0.74-15.4). Using a hand to dislodge trapped snow was the only risk factor identified for the patients (OR, 116; 95 percent CL, 16-820). No differences were found for other variables such as type of snowblower, instruction for use, or previous experience using a snowblower. The findings suggest that the most feasible measure to prevent such injuries is a change in snowblower design to preclude entry of a hand while the machine is running. This investigation illustrates the importance of surveillance in detecting and controlling injuries. Without such surveillance, the similarity among injuries reported on this paper would not have been recognized. Ongoing surveillance for injuries might identify other clusters of injuries.

Accidents, Home↗
PubMed1987

Snowblower injuries to the hand.

A single heavy snowstorm in Saskatoon in late 1984 resulted in nine patients sustaining snowblower injuries to 19 digits. Factors leading to injury included rapid onset of colder temperatures, sudden reuse of snowblowers after storage for the summer, a heavy mid-week storm that created a sense of urgency to clear snow in dusky light conditions after a day at work, frustration as exit chutes became repeatedly clogged with heavy wet snow and limited operator education. The injuries themselves resembled low-velocity "missile" injuries. A practical preventive measure would be to encourage manufacturers to equip machines with remotely located spring-opening clutches.

Accidents, Home↗
PubMed2026

Fine-Scale Population Genomics Reveals Genetic Differentiation in the Brooding Amphipod Cheirimedon femoratus Across the South Shetland Islands, Antarctica.

Antarctic marine ecosystems are sensitive to environmental change, and impacts on processes such as population connectivity will play a fundamental role in future population dynamics and persistence, affecting short-term demography and long-term evolution. We investigated the population genomics of the common benthic brooding Antarctic amphipod Cheirimedon femoratus (Pfeffer, 1888), using 8837 high-quality single-nucleotide polymorphisms (SNPs) from 87 individuals collected at 4 sites in the South Shetland Islands, separated by up to 200&#x2009;km: Deception Island, King George Island, Livingston Island, and Snow Island. While Admixture, F ST, principal component analysis (PCA), and demographic (Ne) analyses revealed a generally weak population genetic structure, Livingston Island emerged as a distinct population, especially compared to King George Island. All populations showed a heterozygote deficit with positive inbreeding coefficients (F IS), particularly high in the Snow Island population (~0.55). Tajima's D test suggested overall neutral evolution, although slight variation was observed among sites. Despite the limited dispersal potential of this brooding species, the observed connectivity may be maintained through passive dispersal, likely via floating macroalgae or ice-rafted debris, facilitated by prevailing regional ocean currents. This may enhance the population resilience of Antarctic benthic communities under environmental change, including regional warming and shifts in ocean circulation, compared to more isolated populations. Our findings underscore the complex interplay between passive connectivity and fine-scale differentiation in shaping Antarctic benthic invertebrate diversity.

Amphipoda↗
PubMed1994

Genomic diversity of small round structured viruses in the United Kingdom.

Fifty-two faecal specimens collected in the United Kingdom between 1986 and 1992, which contained small round structured virus (SRSV) particles, were tested by reverse transcriptase polymerase chain reaction assays using two primer pairs derived from sequences of Snow Mountain Agent and Norwalk virus. There was poor correlation between results obtained with each primer pair. Twenty specimens (38%) gave positive bands with SM51/31 primers and 18 (34%) were positive with SM52/32 primers, with a total of 30 specimens (57.7%) giving amplification products of the expected size with one or both primer pairs. Genomic variation was investigated by sequencing a 266 bp region of the RNA polymerase gene from nine strains which had been antigenically typed by solid phase immune electron microscopy (SPIEM). RNA sequence identities ranged from 53 to 99%. Three genomic groups were suggested by phylogenic analysis, the first of which contained Norwalk virus, Southampton virus, and strains typed by SPIEM as SRSV UK2. The second contained Snow Mountain agent and strains typed as either SRSV UK3 or UK4. The third contained strains typed as SRSV UK1 and strains untypeable by SPIEM. Some correlation was demonstrated when antigen typing by SPIEM and phylogenic grouping based on sequence data were compared.

Adult↗
PubMed1995

Molecular characterisation of small round structured viruses associated with gastroenteritis in South Africa.

The application of the reverse transcriptase polymerase chain reaction (RT-PCR) has enabled several morphologically and physically similar small round structured viruses (SRSVs), including the prototype Norwalk virus (NV), to be classified within the Caliciviridae. This technique, using primers directed to the RNA-dependent RNA polymerase region within the ORF1 of NV, was used to characterise SRSVs associated with epidemic gastroenteritis in adults and sporadic paediatric gastroenteritis in South Africa. Genomic variation was investigated by sequence analysis of the amplified 209bp cDNA region from six isolates and comparison with other characterised SRSVs including NV. Antigenic variation was investigated by the use of the recombinant enzyme immunoassay described recently for the detection of Snow Mountain agent-like antigen in stool specimens. Two distinct antigenic groups were evident with NV-like viruses associated with adult gastroenteritis, and Mexico viruslike viruses associated with paediatric gastroenteritis. Viral isolates from two of the outbreaks of adult gastroenteritis showed a high degree of nucleotide sequence identity with NV, i.e., 84% and 98%, respectively, whereas the paediatric isolates showed 92-95% sequence similarity with the Snow Mountain-like virus, MxV. These data show concordance between antigenic and genomic analyses.

Adult↗
PubMed2005

Sorption, degradation and leaching of the fungicide iprodione in a golf green under Scandinavian conditions: measurements, modelling and risk assessment.

In cold climates, fungicides are used on golf greens to prevent snow mould causing serious damage to the turf. However, fungicide residues have been detected in runoff from golf courses, which may lead to restrictions on use. There is therefore an urgent need to improve understanding of the processes affecting leaching of fungicides from turfgrass systems to allow identification of green construction and management practices that minimize environmental impacts. In this study we monitored the leaching of the fungicide iprodione in a putting green. Sorption and degradation of iprodione was measured in batch and incubation experiments, and the simulation model MACRO was used as a risk assessment tool. Degradation of iprodione was bi-phasic, with a rapid initial phase (half-life 17 h) caused by enhanced biodegradation. Degradation rates slowed considerably after 5 days, with half-lives of up to 38 days. Sorption of iprodione was linear, with a K(oc) value of ca 400 cm(3) g(-1). MACRO reasonably accurately matched measured drainflows and concentrations of iprodione in soil and drainflow. However, peak concentrations in drainage were underestimated, which was attributed to preferential finger flow due to water repellency. The results also showed the importance of the organic matter content in the green root zone in reducing leaching. It was concluded that, with 'reasonable worst-case' use, losses of iprodione from greens can occur at concentrations exceeding water quality limits for aquatic ecosystems. Snow mould problems should be tackled by adopting green root zone mixes that minimize leaching and 'best management practices' that would avoid the need for intensive prophylactic use of fungicides.

Adsorption↗
PubMed2004

Effect of deicing salts on urban soils and health status of roadside trees in the Opole region.

This article reports on a study whose aim was to evaluate the impact of snow removal salts on urban soil properties and the health of roadside trees. The evaluation was done by chemical analyses of soil samples and plant matter combined with toxicity testing, performed with a Protoxkit F, a protozoan microbiotest. Samples were collected at 45 locations on three main roads in the town of Opole (Poland). The roads differed in the snow removal technology and amount of chemical substances (mostly NaCl) used on them during the winter. The study showed that when soil was exposed to a high level of NaCl, it tended to be more alkaline and also exhibited increased content of Na(+) and Cl(-). The toxic effects of the soil extract on protozoa appeared at 26.0 mg Na(+)/100 g soil dry mass (s.d.m.) and 12.0 mg Cl(-)/100 g s.d.m., whereas salt injury symptoms (chlorosis and necrosis of the edge of leaf blades) appeared at 13.2 mg Na(+)/100 g s.d.m. and 3.9 mg Cl(-)/100 g s.d.m., becoming more severe at 26.0 mg Na(+)/100 g s.d.m. and 12.0 mg Cl(-)/100 g s.d.m. because of extensive necrosis and defoliation. The lysimetric experiment, which was used to test soil samples collected from the city park area, indicated that salt plays a significant role in the pollution of soil in urban areas, with the least toxic salt being CaCl(2).

Animals↗