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PubMed1980

A biomechanical model for actively controlled snow ski bindings.

Active control of snow ski bindings is a new design concept which potentially offers improved protection from lower extremity injury. Implementation of this concept entails measuring physical variables and calculating loading and/or deformation in injury prone musculoskeletal components. The subject of this paper is definition of a biomechanical model for calculating tibia torsion based on measurements of torsion loading between the boot and ski. Previous control schemes have used leg displacement only to indicate tibia torsion. The contributions of both inertial and velocity-dependent torques to tibia loading are explored and it is shown that both these moments must be included in addition to displacement-dependent moments. A new analog controller design which includes inertia, damping, and stiffness terms in the tibia load calculation is also presented.

Accidental Falls↗
PubMed2001

Seasonal variations of snow depth on Mars.

Using topography collected over one martian year from the Mars Orbiter Laser Altimeter on the Mars Global Surveyor (MGS) spacecraft, we have measured temporal changes in the elevation of the martian surface that correlate with the seasonal cycle of carbon dioxide exchange between the surface and atmosphere. The greatest elevation change (1.5 to 2 meters) occurs at high latitudes ( above 80 degrees ), whereas the bulk of the mass exchange occurs at lower latitudes (below 75 degrees N and below 73 degrees S). An unexpected period of sublimation was observed during northern hemisphere autumn, coincident with dust storms in the southern hemisphere. Analysis of MGS Doppler tracking residuals revealed temporal variations in the flattening of Mars that correlate with elevation changes. The combined changes in gravity and elevation constrain the average density of seasonally deposited carbon dioxide to be 910 +/- 230 kilograms per cubic meter, which is considerably denser than terrestrial snow.

Atmosphere↗
PubMed1986

Characterization of the Snow Mountain agent of viral gastroenteritis.

Snow Mountain agent (SMA) is a 27- to 32-nm virus which is the etiologic agent of outbreaks of acute gastroenteritis in Colorado and Vermont. SMA is morphologically similar to but antigenically distinct from the Norwalk and Hawaii agents of viral gastroenteritis but, like those agents, has not been cultivated in vitro. We purified and characterized SMA directly from human stool specimens containing the virus. The density of the SMA virion was 1.29 g/cm3 and 1.21 to 1.22 g/cm3 on potassium tartrate-glycerol gradients and 1.33 to 1.34 g/cm3 on cesium chloride gradients. SMA had an S value of 170 to 183S on a sucrose velocity gradient. The purified virion was iodinated, immunoprecipitated with acute and convalescent sera from volunteers challenged with SMA, and analyzed on polyacrylamide gels. The virion contains one major structural protein of 62,000 molecular weight, which is similar in size to the 59,000-molecular-weight protein found in the Norwalk virion. The biophysical properties and single structural protein of SMA most closely resemble those of the calicivirus group.

Caliciviridae↗
PubMed2005

Cellular and humoral immunity following Snow Mountain virus challenge.

Little is known about the immune response to noroviruses. To elucidate the immunobiology of norovirus infection in humans, 15 volunteers were challenged with Snow Mountain virus (SMV), a genogroup 2 norovirus. We assessed the cellular and humoral immune response and infection by analyzing stool, serum, saliva, and peripheral blood mononuclear cell (PBMC) responses pre- and postchallenge. In contrast to Norwalk virus (NV), SMV infection was not dependent upon blood group secretor status. Nine of 15 volunteers were infected and showed a >/=4-fold increase over the prechallenge anti-SMV serum immunoglobulin G (IgG) titer, mostly subclass IgG1. Although serum IgG elicited by SMV infection was cross-reactive with Hawaii virus (HV), another genogroup 2 norovirus, salivary IgA was less cross-reactive. Neither SMV-elicited serum IgG nor salivary IgA cross-reacted with NV, a genogroup 1 norovirus. Significant increases in serum gamma interferon (IFN-gamma) and IL-2, but not IL-6 or IL-10, were noted on day 2 postchallenge. For the majority of volunteers, both infected and uninfected, PBMCs stimulated with norovirus virus-like particles secreted IFN-gamma and other Th1 cytokines, suggesting previous norovirus exposure in most volunteers. Like the IgG antibodies, the SMV-activated T cells were cross-reactive with HV but not NV. IFN-gamma production was dependent upon CD4(+) cells, consistent with a predominant, but not exclusive, Th1 response. To our knowledge, this is the first report characterizing T-cell and cytokine responses following live norovirus challenge.

Adult↗
PubMed1986

Subretinal neovascularisation and snow banking in a case of sarcoidosis: case report.

A 49-year-old Japanese man presented with chronic granulomatous uveitis in his left eye. Later he developed macular subretinal neovascularisation. The chest x-ray showed bilateral hilar lymphadenopathy. Bronchoscopy and gallium-67 scanning were positive, PPD skin test negative, and serum angiotensin converting enzyme (ACE) levels increased. Ophthalmoscopy and fluorescein angiography of the left eye showed perivasculitis, retinochoroidal exudates, snow banking, and vitreous opacity. On these findings, the diagnosis of sarcoidosis was made. Treatment was based on topical corticosteroids, mydriatics, beta blockers, and oral carbonic anhydrase inhibitors. After 15 months the visual acuity decreased in the left eye, and a neovascular membrane was observed in the macula. Fluorescein angiography confirmed subretinal neovascularisation. Almost two years later the patient still has the neovascular membrane in his left eye.

Eye Diseases↗
PubMedDate not supplied

A low molecular weight peptide from snow mold with epitopic homology to the winter flounder antifreeze protein.

Evidence for a small size protein (ca. 3500 kDa) exhibiting epitopic homology to the Atlantic winter flounder antifreeze protein (AFP) is found in the snow molds Coprinus psychromorbidus, Myriosclerotinia borealis, and Typhula incarnata. The protein shows strong cross-reactivity with antisera specific for the flounder AFP. Preliminary studies suggest that the protein is synthesized in response to lowering the culture temperature, and that it is membrane associated and, therefore, may function in an analogous capacity to the fish AFP. Also, the protein is shown to have antifreeze properties as determined by nuclear magnetic resonance microimaging experiments.

Agaricales↗
PubMed1986

Impending cardiac herniation: the snow cone sign.

Two cases of cardiac herniation and volvulus that occurred after right pneumonectomy are presented. Both asymptomatic patients demonstrated an unusual bulging contour to the right side of the heart on radiographs obtained in the recovery room, before complete herniation and volvulus occurred. In an autopsy preparation, a similar right contour was produced after partial cardiac herniation through a pericardial defect. The hemispheric contour from partial cardiac herniation resembles the shape of a snow cone. Clinical awareness of this sign of impending herniation is important, so risk factors known to produce herniation may be modified.

Adult↗
PubMed1977

G-band patterns of the Siberian snow sheep (Ovis nivicola) and their relationship to chromosomal evolution in sheep.

G-band patterns of the Siberian snow sheep, Ovis nivicola alleni, 2n=52, were compared with the patterns reported in 2n=54 wild Asiatic mouflon and 2n=54 North American sheep and those in domestic sheep with 2n=54, 53, and 52. The three largest pairs of biarmed autosomes displayed indistinguishable, presumably homologous, G-banding patterns in all types of sheep. The banding and morphology of the fourth pair of biarmed autosomes in O.nivicola differed from those of the three translocation variants described in domestic sheep. Wild sheep with 2n=54 may have evolved monophyletically from an ancestral 2n=58-56-54 population or polyphyletically by a series of independent, nonrandom fusions. In contrast, the fouth pair of biarmed autosomes in O.nivicola and in 2n=52 domestic sheep variants may have resulted from random fusions of different chromosomes.

Animals↗
PubMedDate not supplied

Upper extremity injuries in snow skiers.

All skiers with upper extremity injuries seen at the Henry Ford Hospital between 1983 and 1986 were evaluated in terms of age, sex, skill of the skier, type of snow conditions, pole type, grip type, direction of fall, and mechanism of injury. Our primary objective was to evaluate whether the type of pole used had an effect on the injury rate. We found that the strap handled pole without any platform had the lowest injury rate. The saber type pole handle had the highest injury rate. Other observations showed ulnar collateral ligament injury of the thumb to be the most common upper extremity injury to skiers. A proportionally high number of skiers with upper extremity injuries were advanced skiers.

Arm Injuries↗
PubMed1994

Bottom temperatures of skating skis on snow.

Thermocouples provide information about ski and skier performances and snow conditions. V1 skating superimposed a strong, cyclic signal on the general heating due to friction. The power spectra of these cycles gave information about the skier's technique. The greatest temperature response at the base of a skating ski was just behind the foot, where the ski is heavily loaded. The longitudinal profiles showed generally increasing temperatures along the length of the ski. Harder, more durable waxes are needed behind the foot, where most of the weight is carried, but the gliding temperatures are highest there. Heating increased with both speed and solar input. Solar radiation absorption heats the ski base directly and raises its temperature considerably. The color of the ski base and the amount of sunshine should be considered when choosing a wax.

Humans↗
PubMed1989

The aetiology of multiple loose bodies. Snow storm knee.

We report four patients who showed hundreds of brilliant white loose bodies at arthroscopy of the knee after a short history of pain and crepitus. Histological, historical and clinical evidence is presented which indicates that the aetiology of this condition is the culture of chondrocytes in synovial fluid. It is suggested that reversal of the usually accepted order of events in synovial osteochondromatosis could provide a better and unified explanation for both that condition and multiple loose bodies. The term 'snow storm knee' is proposed to describe the dramatic picture seen at arthroscopy.

Adolescent↗
PubMed2001

A psychoanalytic reading of Peter Høeg's novel Miss Smilla's Feeling for Snow.

The author presents a psychoanalytic reading of the Danish author Peter Høeg's masterpiece 'Miss Smilla's Feeling for Snow', focusing on the special linguistic style of the novel. Further, the author puts forward an interpretation of the heroine, seeing her as a literary example of female bisexuality. Investigating the heroine's fate, the author discusses Miss Smilla's phallic defence and identity. The narrative technique in Høeg's novel is analysed through Lacan's concepts of the Real, the Imaginary and the Symbolic. The main figure is interpreted as an imaginary example of female bisexuality. Miss Smilla has neither an unambiguous gender identity nor ethnicity. The heroine is pictured in a conflict between two cultures: the Greenlandish and the western European, and her bisexuality both reflects this and is part of it. The author proposes to interpret a significant memory from Smilla's early childhood as an example of a castration phantasy, which retroactively gives new significance to the little girl's pre-oedipal frustration.

Bisexuality↗
PubMed1994

Seasonal effects on seminal and endocrine traits in the captive snow leopard (Panthera uncia).

The annual reproductive cycle of the male snow leopard (Panthera uncia) was characterized by evaluating seminal and endocrine traits monthly. Testicular volume was greatest (P < 0.05) during the winter months when the quality of ejaculate was optimal. Ejaculate volume, total sperm concentration ml-1, motile sperm concentration per ejaculate, sperm morphology and sperm motility index were lowest during the summer and autumn months compared with the winter and spring. Peripheral LH, FSH and testosterone concentrations were also lowest during the summer months, increasing during the autumn just before the increase in semen quality, and were maximal during the winter months. There was a direct relationship (P < 0.01) between: (1) testosterone and testicular volume, total sperm concentration ml-1, motile sperm concentration per ejaculate and ejaculate volume, and (2) LH and testicular volume and motile sperm concentration per ejaculate. In summary, although spermatozoa were recovered throughout the year, optimal gamete quality was observed during the winter and spring. Although previous studies in felids have demonstrated seasonal effects on either seminal or endocrine traits, this is the first study to demonstrate a distinct effect of season on both pituitary and testicular function.

Animals↗
PubMed1997

Public health on the railroad: William Freeman Snow and the California Sanitation Exhibit.

This paper describes the California Sanitation Exhibit, a railroad car outfitted for instruction in public health that toured California in 1909 and 1910. The sanitation exhibit used display models, photographs, and lectures to educate the public about tuberculosis and other infectious diseases, waste contamination, and the dangers of bad milk. The success of the exhibit, which reached 5% of the state's population, resulted in the appointment of its creator, William Freeman Snow, as secretary of the California State Board of Health.

California↗
PubMed2004

Large-volume injection electrothermal AAS combined with tungsten-treated pyrolytic graphite furnace: determination of cadmium in tap, snow and river water samples with phosphate modifier.

A large-volume (100 microl) injection-ETAAS with W-treated PG furnace combined with a phosphate modifier was applied to the determination of unpolluted levels of Cd in tap, snow and river-water samples. The limit of detection of 1.1 ng l(-1) was observed for a 4 w/v% NH4H2PO4 modifer. Matrix interference studies were tested for major ion species well found in fresh water. The direct determination of Cd in certified river water (12 +/- 2 ng l(-1)) was carried out and the observed value was in agreement with the certified one. The good recoveries of Cd added to real environmental water samples were also observed. This method was applied to the determination of Cd in unpolluted environmental water samples.

Journal Article↗
PubMed2004

Spring snow lowers human melatonin.

OBJECTIVES: We set out to find out in which way seasonal changes of environmental luminosity could affect melatonin secretion in humans. STUDY DESIGN: For an entire year we collected every two months nocturnal urine samples from 20 male outdoor workers who lived and worked in an area of the circumpolar region from which exact data solar irradiance and temperature were available. METHODS: Melatonin secretion rates were assessed with our melatonin-specific radioimmunoassay. RESULTS: Melatonin secretion was twice as high in December as in April, 0.88 +/- 16 nmol/12 h (mean +/- SE) vs. 0.43 +/- 9 nmol/12 h, p < 0.05. Regression analyses showed that melatonin values best correlated inversely with weeks before the urine samplings were collected was associated with a ca. 50% reduction in melatonin secretion. The association with global irradiance was weaker and none existed with temperature or other environmental variables. DISCUSSION: Light reaching the eyes via the snow or other reflecting involved in certain biological phenomena that exhibit seasonal variations such as reproductive and self-destructive behaviours.

Arctic Regions↗
PubMed1996

Renal coccidiosis and other parasitologic conditions in lesser snow goose goslings at Tha-anne River, west coast Hudson Bay.

Lesser snow goose (Chen caerulescens caerulescens) goslings, approximately 5 weeks of age, were collected near the mouth of Tha-anne River, Northwest Territories, Canada, during mid-August 1991. Many dead goslings had been observed in the area from 1988 to 1990. Goslings from near the coast, where habitat degradation by grazing geese was severe, were smaller, weighed less, and had a greater prevalence of renal coccidiosis (Eimeria truncata) and cecal nematode (Trichostrongylus spp.) infection than did goslings from inland areas, where habitat destruction was not evident. Prevalence of infection with intestinal cestodes was greater at inland than at coastal sites. Prevalences of gizzard nematodes (Epomidiostomum spp.) and Leucocytozoon spp. were not significantly different at the two sites. Histological examination of kidneys and examination of kidney homogenates for oocysts were more sensitive methods than gross examination of the kidneys for detecting renal coccidial infection. The number of oocysts present in droppings was not a good indicator of the severity of renal coccidial infection in individual birds; however, the average number of oocysts in droppings was indicative of the average severity of infection among groups of goslings.

Animals↗
PubMed2005

Avian cholera in waterfowl: the role of lesser snow and ross's geese as disease carriers in the Playa Lakes Region.

We collected samples from apparently healthy geese in the Playa Lakes Region (USA) during the winters of 2000-01 and 2001-02 to determine whether carriers of Pasteurella multocida, the bacterium that causes avian cholera, were present in wild populations. With the use of methods developed in laboratory challenge trials (Samuel et al., 2003a) and a serotype-specific polymerase chain reaction method for identification of P. multocida serotype 1, we found that a small proportion of 322 wild birds (<5%) were carriers of pathogenic P. multocida. On the basis of serology, an additional group of these birds (<10%) were survivors of recent avian cholera infection. Our results confirm the hypothesis that wild waterfowl are carriers of avian cholera and add support for the hypothesis that wild birds are a reservoir for this disease. In concert with other research, this work indicates that enzootic infection with avian cholera occurs in lesser snow goose (Chen caerulescens caerulescens) populations throughout their annual cycle. Although fewer Ross's geese (Chen rossii) were sampled, we also found these birds were carriers of P. multocida. Even in the absence of disease outbreaks, serologic evidence indicates that chronic disease transmission and recent infection are apparently occurring year-round in these highly gregarious birds and that a small portion of these populations are potential carriers with active infection.

Animals↗