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Do geese fully develop brood patches? A histological analysis of lesser snow geese (Chen caerulescens caerulescens) and Ross's geese (C. rossii).

Most birds develop brood patches before incubation; epidermis and dermis in the brood patch region thicken, and the dermal connective tissue becomes increasingly vascularized and infiltrated by leukocytes. However, current dogma states that waterfowl incubate without modifications of skin within the brood patch region. The incubation periods of lesser snow geese (Chen caerulescens caerulescens; hereafter called snow geese) and Ross's geese (C. rossii) are 2-6 days shorter than those of other goose species; only females incubate. Thus, we hypothesized that such short incubation periods would require fully developed brood patches for sufficient heat transfer from incubating parents to eggs. We tested this hypothesis by analyzing the skin histology of abdominal regions of snow and Ross's geese collected at Karrak Lake, Nunavut, Canada. For female snow geese, we found that epidermis and dermis had thickened and vascularization of dermis was 14 times greater, on average, than that observed in males (n=5 pairs). Our results for Ross's geese (n=5 pairs) were more variable, wherein only one of five female Ross's geese fully developed a brood patch. Our results are consistent with three hypotheses about brood patch development and its relationship with different energetic cost-benefit relationships, resulting from differences in embryonic development and body size.

Animals↗

Manganese and other trace elements in urban snow near an expressway.

The Mn contamination arising from the combustion of MMT (methylcyclopentadienyl manganese tricarbonyl) in unleaded gasoline was assessed using snow collected at different distances 15, 25, 125 and 150 m from an expressway (Montreal, Canada) in February 1993. The snow samples were analyzed by atomic absorption and by neutron activation for total Mn, Mg, Cu, V, Al, Zn, Fe, Na, and Ca concentrations in the soluble (<0.4 microm) and particulate fractions. ANOVA with ranked values was performed to compare element concentrations and soluble/particulate ratios among receptor sites and depths. Principal component analysis was used to describe the spatiotemporal variations of the deposition rates and the influence of meteorological factors. The average concentration of all trace elements, except Mg, Cu, and V, decreased significantly (p<0.05) from receptor sites near the road (15-25 m) to those farther away (125-150 m). The deposition rates of all metals and ions, except Cu, were highly positively correlated (tau = 0.5-0.9) with each other and inversely correlated with snowfalls. Wind frequency showed no correlation with deposition rate. The spatial trend was similar for all these elements making it difficult to distinguish Mn arising from the combustion of MMT from that due to other sources, such as road dust. Only the soluble/particulate ratio calculated for Mn seemed higher than that for the other metals, which might be explained by the particle size of Mn from MMT (0.2-0.4 microm). The present study only indicates a direct contamination of the snow by road activities and substantial deposition of trace elements near the roadway; no clear link can be established between motor vehicle emissions and the concentration of Mn in snow.

Journal Article↗

Chemical composition of arctic snow: concentration levels and regional distribution of major elements.

At the end of the northern winter 1996/1997, 21 snow samples were collected from 17 arctic localities in Norway, Sweden, Finland, Svalbard, Russia, Alaska, Canada, Greenland and Iceland. Major element concentrations of the filtered (0.45 mum) melted snow indicate that most samples are consistent with a diluted seawater composition. Deviations from this behaviour indicate additional SO(4)(2-) and Cl(-) relative to seawater, suggesting a minor contribution from (probably local) coal combustion emissions (Alaska, Finland, Sweden, Svalbard). The samples with the highest Na and Cl(-) content (Canada, Russia) also have higher Na/SO(4)(2-) and Cl(-)/SO(4)(2-) ratios than seawater, suggesting a slight contamination from (probably local) deicing activities. Local soil or rock dust inputs in the snow are indicated by 'excess' Ca contents (Alaska, Svalbard, Greenland, Sweden). No overall relationship was found between pH (range: 4.6-6.1) and total or non-seasalt SO(4)(2-) (NSS), suggesting that acidification due to long-range transport of SO(2) pollution is not operating on an arctic-wide scale. In a few samples (Alaska, Finland, Sweden, Svalbard), a significant proportion (>50%) of SO(4)(2-) is non-marine in origin. Sources for this non-marine SO(4)(2-) need not all be found in long-range atmospheric transport and more likely sources are local industry (Finland, Sweden), road traffic (Alaska) or minor snow-scooting traffic (one Svalbard locality). A few samples from northern Europe show a relatively weak trend of decreasing pH with increasing NO(3)(-).

Journal Article↗

Snow Mountain agent gastroenteritis from clams.

A 1983 investigation of two clambake-related gastroenteritis outbreaks in Rochester, New York, showed that 84 (43%) of 196 persons interviewed had an acute illness characterized by watery diarrhea, vomiting, and abdominal cramps. None of the ill persons were hospitalized or had complications. Illness was associated with eating raw (p = 0.002) or baked (p less than 0.01) hard-shell clams, with the risk of illness increasing with the total number of clams consumed (p less than 0.01). The median incubation period and duration of illness were 36 and 44 hours, respectively. Stool samples obtained 2-4 days after onset of illness were negative for commonly recognized bacterial and viral pathogens. However, of 31 persons whose stools were tested, the stool of only one ill person was positive by enzyme-linked immunosorbent assay for the Snow Mountain agent, one of the Norwalk-like viruses. Paired serum specimens from six (67%) of nine ill and two (29%) of seven well persons showed a fourfold or greater rise in antibody titer to Snow Mountain agent. Persons who ate clams were more likely to seroconvert to Snow Mountain agent (eight of 12) than were those who did not eat clams (zero of four) (p = 0.04). The clams were harvested off the coast of southern Massachusetts in late October, when harvest waters were documented to be contaminated by untreated municipal sewage. This report describes the first documented outbreak of shellfish-associated gastroenteritis attributed to Snow Mountain agent of which we are aware.

Acute Disease↗

Who made John Snow a hero?

This paper describes how and why John Snow's investigation of the transmission of cholera grew into an epidemiologic classic. The evolution of the interpretation of the work of John Snow was first studied in depth in the Dutch medical literature, and thereafter traced more superficially in the bacteriologic, hygienic, and epidemiologic literature of Germany, the United Kingdom, and the United States. From the oral tradition of teaching, as well as from the written sources, it is concluded that US epidemiologist W. H. Frost was responsible for the revival of the work of John Snow in the 1930s. Besides the obvious and enjoyable clarity of thinking and reasoning, epidemiologically and medically, of the writings of John Snow, his example well suited epidemiology of the 1930s since his convictions came very close to the bacteriologic paradigm of the day.

Cholera↗

Branch breakage under snow and ice loads.

Measurements were made on branches and trunks of Picea sitchensis (Bong.) Carr. to determine the relationship between (i) the bending moment at the bases of branches that cause breakage, and (ii) midpoint diameter cubed. The theory for cantilever beams was then used to calculate the basal bending moments and midpoint diameters of branches with different numbers of laterals and endpoint deflections, given previously measured values of Young's modulus, taper and weights of foliage and wood. Snow and ice loads (equal to 2 and 4 g cm(-1) of shoot, respectively) were then included in the calculation to determine whether the basal bending moments exceeded the breakage values. The likelihood of breakage increased with an increase in (i) number of laterals, and (ii) endpoint deflection under self weight (without snow or ice)-features that had previously been shown to lessen the amount of branch wood required to support a unit of foliage. However, branches which deflected moderately (> 10% of their length) under their own weight deflected greatly under snow or ice loads and might shed powdery snow before breakage occurs.

Journal Article↗

Fracture mechanics of snow avalanches.

Dense snow avalanches are analyzed by modeling the snow slab as an elastic and brittle plate, attached by static friction to the underlying ground. The grade of heterogeneity in the local fracture (slip) thresholds, and the ratio of the average substrate slip threshold to the average slab fracture threshold, are the decisive parameters for avalanche dynamics. For a strong pack of snow there appears a stable precursor of local slips when the frictional contacts are weakened (equivalent to rising temperature), which eventually trigger a catastrophic crack growth that suddenly releases the entire slab. In the opposite limit of very high slip thresholds, the slab simply melts when the temperature is increased. In the intermediate regime, and for a homogeneous slab, the model display features typical of real snow avalanches. The model also suggests an explanation to why avalanches are impossible to forecast reliably based on precursor observations. This explanation may as well be applicable to other catastrophic rupture phenomena such as earthquakes.

Journal Article↗

Fracture toughness of snow in shear under friction.

The fracture toughness of snow in shear is one of the most relevant parameters when studying the mechanics of snow slab avalanche release. Double-cantilever snow beams were loaded asymmetrically to determine K(IIc). If crack surfaces touch under applied pressure, the fracture toughness in shear of snow (rho=247 kg m(-3)) is K(IIc)=680+/-60 Pa m(1/2). Screening of the stress intensity at the crack tip occurs by Newtonian friction with k=1.3+/-0.47 along the crack faces.

Journal Article↗

Two-threshold model for scaling laws of noninteracting snow avalanches.

The sizes of snow slab failure that trigger snow avalanches are power-law distributed. Such a power-law probability distribution function has also been proposed to characterize different landslide types. In order to understand this scaling for gravity-driven systems, we introduce a two-threshold 2D cellular automaton, in which failure occurs irreversibly. Taking snow slab avalanches as a model system, we find that the sizes of the largest avalanches just preceding the lattice system breakdown are power-law distributed. By tuning the maximum value of the ratio of the two failure thresholds our model reproduces the range of power-law exponents observed for land, rock, or snow avalanches. We suggest this control parameter represents the material cohesion anisotropy.

Journal Article↗

Seasonal modulation of interseismic strain buildup in northeastern Japan driven by snow loads.

Distinct periodic variations with annual frequencies are often found in the time series of continuous Global Positioning System (GPS) site coordinates in northeastern Japan. They show maximum arc-normal contraction of a few millimeters as well as maximum subsidence of 1 to 2 centimeters, both in March. In northeastern Japan, it snows heavily on the western flank of the backbone range, attaining a maximum depth of several meters in March. When observed snow depths were compared with the load distribution estimated from the GPS data, the surface loads caused by the snow were found to be largely responsible for the annual displacement of GPS sites. The snow load modulates secular strain buildup in northeastern Japan due to the Pacific Plate subduction, but its relevance to the seasonal change of earthquake occurrences remains uncertain.

Journal Article↗

Characteristics and Diversity of beta-d-Glucosidase (EC 3.2.1.21) Activity in Marine Snow.

Large amorphous aggregates commonly described as marine snow were sampled in the water column of the northern Adriatic Sea in August 1991. beta-d-Glucosidase activity associated with these aggregates was characterized. Enzymatic activity was measured with the fluorogenic substrate analog 4-methylumbelliferyl-beta-d-glucoside and found to be mainly associated with particles; on average, only 24% of the whole beta-d-glucosidase activity remained in the supernatant after centrifugation. Although the temperature optimum for beta-d-glucosidase activity was approximately 40 degrees C, incubation of the previously liberated particle-attached enzyme at 50 degrees C for 20 min caused a >90% reduction of enzymatic activity relative to the activity at 40 degrees C. The level of inactivation of beta-d-glucosidase was much lower, however, when whole marine snow was incubated, indicating qualitative modifications of beta-d-glucosidase in marine snow. Separation of beta-d-glucosidase by different approaches indicated that the diversity of isoenzymes is restricted. In samples taken from the pycnocline, only one major isoenzyme was present in noticeable amounts. This isoenzyme contributed up to 70% of the whole beta-d-glucosidase activity detectable by two different chromatographic separations (anion-exchange chromatography and size exclusion chromatography). Although the same isoenzyme was dominant in marine snow taken from surface waters (0.5-m depth), we found a second peak of activity which eluted at lower NaCl concentrations from the anion-exchange column. Generally, the diversity of isoenzymes exhibiting beta-d-glucosidase activity seems to be surprisingly small in amorphous pelagic aggregates.

Journal Article↗

[Was Snow White a transsexual?].

The Rorschach Ink Blot test is considered to be an essential analytical instrument when studying the personalities of individuals presenting identity disorders, in particular, in the context of a sex change request. Nevertheless, there exist less than 20 studies of transsexualism utilising the Rorschach since the creation of this diagnostic category in 1953. This research has mostly concerned itself with relations between psychopathology and transsexualism. Practically non-existent are studies investigating the psychological conditions that permit, shape or induce sex change requests in individuals. Transsexuals request the removal of their genitals through mutilation surgery, which can be seen as subjects literally crying out to be castrated. This request is all the more surprising given that castration, in psychoanalytic terms, is considered to be the most severe punishment that an individual (woman or man) can be threatened with. Therefore, we asked ourselves which psychic conditions could motivate such as request. Based on any earlier study where answers (some explicit, others symbolic) given by sex-change applicants tested on the Rorschach were analysed, results seemed to suggest a counter-phobic attitude underlying sex-reassignment requests (28). According to these hypotheses, the fear of castration (banal as such) can only be overcome through the active search for castration itself. In opting for castration, the transsexual puts an end to the states of anxious waiting that are dominated by feelings of the incertitude and unpredictability of an eventual castration. Once obtained, the threat it constituted disappears, and with it so does the fear. Thus, by taking this active and voluntary step, the subject is no longer exposed to an imminent danger in a passive manner. This in itself creates a great feeling of relief, if not of actual pleasure in the subject (28). In this article, we postulated in a purely speculative manner, the existence of one or several modalities in the transsexual dynamics. Nevertheless, one can ask oneself about the possibility of a request based on a desire rather than on a defense, or even on the existence of a defensive process diametrically opposed to the counter-phobic attitude and which, instead of actively provoking the dreaded reality, would privilege its avoidance and the search of passivity. This latter hypothesis has the advantage of being rather easy to explore with the Rorschach because, according to Exner, the predominance of passive compared to active human movement responses (which he terms the Snow White Syndrome) indicates the propensity to escape into passive fantasies and the tendency to avoid the initiative for behaviour or decision-making, if other people can do it in the subject's place (12). Our results largely confirmed the hypothesis of the existence of an opposite mechanism, as a third of subjects (n = 26) presented Snow White Syndrome. According to Exner, these transsexuals are typically characterized by hiding into a world of make believe, avoiding all responsibility, as well as any decision-making. This passivity in our Snow White Syndrome group was all the more remarkable in that, on the whole, it infiltrated into all the movement responses and seemed to define a rigid style of thinking and mental elaboration, in addition to a suggestive content of passivity. However, this condition cannot be associated with a general lack of dynamism or energy. In fact, the treatment of information, which provides data concerning the motivation to treat a stimulus field of the stimulus--whether this concerns the capture (L) of the stimulus or the elaboration (DQ+) of the response--displayed a sufficient amount of motivation. Furthermore, internal resources (EA) were considerable and were brought into play whenever it was necessary to adopt a behaviour or make a decision. Furthermore, based on these Rorschach findings, we note that in transsexuals with Snow White Syndrome, there is a stereotyped tendency to shy away from difficulties by seeking refuge in realistic representations (but that lack in variety), which could be materialized by actions, but where the initiative is delegated to others. These transsexuals appear to shy away from the difficulties of life by seeking refuge into a world of fantasy, which they fill with the representations borrowed from reality (rather than fantasy) and consequently that are liable to be transposed, if necessary, back into reality. Therefore, one can better understand why they shun away from the deceiving reality that their physical sex represents, into the satisfying dream where they possess the genitals of the opposite sex, that is, a perfectly real organ, no longer the result of the subject's fantasy world.

Adult↗

Snow leopard (Panthera uncia) spermatozoa are sensitive to alkaline pH, but motility in vitro is not influenced by protein or energy supplements.

To better understand the biology of snow leopard spermatozoa and to facilitate developing assisted reproduction, a series of studies was conducted to: 1) identify the component(s) of complex culture media responsible for the detrimental effect on sperm survival in vitro, 2) optimize medium for supporting sperm viability, and 3) evaluate sperm capacitation in vitro. Constituents of complex media were added systematically to phosphate-buffered saline (PBS) to isolate the factor(s) influencing snow leopard sperm motility in vitro. Sperm capacitation was also assessed following incubation in PBS with bovine serum albumin (BSA), fetal calf serum (FCS), or heparin. For maintaining sperm motility, there was no benefit (P > or = 0.05) to supplementing PBS with low (5%) or high (20%) concentrations of snow leopard serum (SLS) versus FCS or BSA. Likewise, adding supplemental energy substrates (pyruvate, glucose, lactate, or glutamine) did not enhance or hinder (P > or = 0.05) sperm motility. However, motility rapidly decreased (P < 0.05) with the addition of NaHCO3 to PBS or Ham's F10 nutrient mixture. Surprisingly, Ham's F10 with no buffering component or with both NaHCO3 and N-Z-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) maintained sperm motility at levels similar (P > or = 0.05) to PBS. Although sperm motility in all treatments decreased with time, there was a strong inverse relationship (P < 0.01; r = 0.90) between motility and sample pH at 6 hours. Spermatozoa incubated in PBS containing FCS, BSA, or heparin did not undergo the acrosome reaction when exposed to calcium ionophore. In summary, alkaline pH has a profound detrimental effect on snow leopard sperm motility, and capacitation does not occur under conditions that normally promote this event in other felid species. These results clearly demonstrate a high degree of interspecific variation among felids in fundamental sperm function, and they provide evidence for the necessity of basic research when developing assisted reproduction in little-studied nondomestic species.

Acrosome↗

Dispersal behavior of adult snow melt mosquitoes in the Upper Rhine Valley, Germany.

The dispersal behavior of female snow melt mosquitoes was studied in two forests in Rhineland-Palatinate, Germany, from April to August 1993. Both CDC-light-traps and human bait collections were used to collect mosquitoes. Sampling sites were chosen along a west-east and a north-south transect in treated and untreated parts of a forest with a village in its center. Around this settlement, breeding sites within a radius of 1.5 to 2.5 km were treated. It could be shown that this buffer zone is sufficient to prevent a nuisance caused by snow melt mosquitoes in the village. The results lead to the conclusion that snow melt mosquitoes do not regularly migrate over large distances but stay near their breeding sites. In a detailed study of the behavior of Aedes rusticus, it could be observed that these mosquitoes were resting in the interior of the forest during daytime and leaving it with increasing dusk up to 50 m from the forest edge. A comparison of landing rate counts near a row of trees and in the open field showed higher activity near the row of trees indicating visual orientation of the mosquitoes. Although the Ae. rusticus females left the forest regularly, no nuisance occurred in nearby villages. The treatment of breeding sites near settlements appeared to be sufficient to prevent a nuisance caused by the snow melt mosquitoes.

Aedes↗

Injuries from single-vehicle crashes and snow depth.

Swedish official statistics on road traffic accidents shows a remarkable variability among different winter seasons in single-vehicle crashes resulting in personal injuries--one of the major causes of personal injury in road traffic. This study presents results from analyses investigating the role played by snow as an injury-reducing factor. The regression model specified implies, when applied to Swedish data, that an increase in snow depth by 1 cm--for snow depths less than 40 centimetres--reduces the number of crashes with occupant injury by 3%. This finding has implications for assessing trends in traffic safety through the use of routine statistics on motor vehicle occupant injuries and also shows that roadside design is a decisive factor in the generation of injury to the individual in single-vehicle crashes.

Accidents, Traffic↗

Snow-related recreational injuries in children: assessment of morbidity and management strategies.

PURPOSE: The aim of this study was to investigate the causes, clinical course, and financial impact of snow-related sport injuries in children. METHODS: Reports of snow-related injuries (skiing, toboganning, snowboarding) occurring in 147 consecutive children (< or =16 years of age) admitted from 1991 through 1997 were collected prospectively and assessed retrospectively. During the last year of the study, outpatients treated and released from the emergency department (1996 through 1997) were examined in parallel (n = 101). Total financial impact was determined from the aggregate hospital, rehabilitation, and societal costs. RESULTS: One hundred thirty-seven patients (M:F, 2:1; mean age, 13 yrs) were admitted (toboggan [n = 74], ski [n = 59], snowboard [n = 16]), of which 66% occurred at licensed resorts, and 33% at parks or private property. There was one death. Although the pattern of injury was similar in all groups (head greater than long bone greater than intraabdominal injuries), mean injury severity scores (ISS) were significantly higher for snowboard injuries. Seventy-five percent of patients required at least one operation. Postdischarge, 15% of patients required institutional care. Of the 101 ambulatory patients (ski [n = 48], toboggan [n = 35], snowboard [n = 18]), 65% were injured at licensed resorts, and 56% required outpatient rehabilitation or home care. The per-patient costs were: hospital treatment, $27,936; outpatient services, $15,243; lost parental income, $1,500. CONCLUSIONS: Snow sport injuries, particularly snowboarding, cause severe childhood morbidity. Helmet usage, training requirements, and regulation of licensed resorts may reduce the morbidity and staggering costs.

Adolescent↗

Pinonaldehyde and some other organics in rain and snow in central Japan.

Solvent-extractable organic compounds in the rain and snow collected at local cities in the mountainous region in central Japan, were analyzed by GC/MS and GC. Pinonaldehyde (2,2-dimethyl-3-acetyl-cyclobutyl-ethanal), an atmospheric reaction product of alpha-pinene, was detected in the rain and snow for the first time, and n-alkanes (C17-C33), fatty acids (C8-C23), and benzoic acid were also detected as major organic components. Concentrations of pinonaldehyde, C17-C33 n-alkanes, C8-C11 fatty acids, C12-C23 fatty acids and benzoic acid ranged between <0.02-13, 0.10-35, 0.55-5.7, 4.2-19 and <0.02-6.0 microg/l, respectively. Their composition showed some difference in summer and winter. In summer, fatty acids and benzoic acid were more abundant, while pinonaldehyde and n-alkanes were much less. Higher photochemical reactivity and higher bioactivity in summer could explain these seasonal changes except for pinonaldehyde, which would suffer from further oxidation in the atmosphere after its photochemical production from alpha-pinene. Predominance of pinonaldehyde and C12-C23 fatty acids in the rain and snow showed a remarkable contrast to n-alkanes in aerosol phase, which were the most abundant components. It indicated that oxygenated products from biogenic compounds might be important as cloud condensation nuclei in forest areas.

Aerosols↗

Epidemic of accidental carbon monoxide poisonings caused by snow-obstructed exhaust systems.

We report a case series of accidental carbon monoxide poisonings caused by snow-obstructed automobile exhaust systems. Accumulation of more than 24 inches of snow contributed to the poisoning of 25 patients who were subsequently treated with hyperbaric oxygen therapy. Two illustrative cases are presented in greater detail, illustrating a life-threatening hazard associated with heavy snow accumulations.

Aged↗