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PubMed1995

Increased UV exposure in Finland in 1993.

Exceptionally low total ozone, up to 40% below the normal level, was measured over Northern Europe during winter and spring in 1992 and 1993. In 1993 the depletion persisted up to the end of May, resulting in a significant increase of biologically effective UV radiation. The increases were significantly smaller in 1992 and 1993 than in 1993. The UV exposure of the Finnish population was evaluated through measurements and theoretical calculations. The increase in measured erythemal (International Lighting Commission) UV falling onto horizontal surfaces on clear day was determined relative to model calculations for an average ozone amount. The increase was on average 10% from April to May 1993, and the maximal measured increase was 34%. Theoretical calculations for both erythemal and carcinogenic (Skin Cancer Utrecht--Philadelphia) UV indicated that in 1993 the theoretical annual increase to a vertical (cylinder) surface ranged from 8 to 13% in Finland. The reflection of UV from snow considerably increases facial UV doses in Northern Finland.

Animals↗

PubMed1984

Two cases of acutely developed cataract in diabetes mellitus.

A 14-year-old female with insulin dependent diabetes mellitus for 3 months, suddenly developed - in less than one day - a dense 'snow-flake cataract' with severe visual impairment in the left eye. In hospital, 5 days later one morning, the patient experienced additional loss of vision in the right eye due to further rapid cataract development, in close relation to hypoglycaemia in the early morning. In another case, a 22-year-old diabetic woman, treated with insulin for 1 year, developed an acute diabetic cataract in less than one day with pronounced visual reduction. Previously, only a few cases of acutely developed and irreversible diabetic cataract have been published. The prevalence of this rare type of diabetic cataract is estimated to be below 1% among diabetics.

Acute Disease↗

PubMed1976

Cryosurgery.

Cryosurgery offers a means of destroying tissue by subjecting it to extreme cold. The mechanisms by which cells die are as yet poorly understood, but reliable and predictable clinical results have been obtained in the treatment of a wide range of benign and premalignant oral lesions. Its effectiveness in the primary treatment of malignant oral lesion has not been adequately assessed but at least it offers palliation and relief of intractable pain where conventional cancer therapy has failed. The use of carbon dioxide 'snow' has been tested and found to be a simple and effective means of treating superficial benign lesions of the mouth.

Animals↗

PubMed2001

Antioxidant status and oxidative stress in elite alpine ski racers.

The goal of this study was to access antioxidant status and markers of oxidative damage in elite alpine ski racers during routine training. Subjects included 12 members of the U.S. Men's Alpine Ski Team attending a 10-day summer training camp. Blood draws were collected at rest and after exercise: (a) prior to training, (b) following 2 days of dry land training, and (c) after 4 days of on-snow skiing. Seven measures of antioxidant status were determined using colorimetric and HPLC methods (Trolox equivalent antioxidant capacity, uric oxidase, alpha-tocopherol, total glutathione, cytosolic glutathione peroxidase, and superoxide dismutase). Oxidative stress was assessed using 2 markers of lipid oxidation (malondialdehyde and lipid hydroperoxides) and 2 markers of protein oxidation (carbonylated total proteins and carbonylated hemoglobin). The results of this study suggest that antioxidant status of elite alpine skiers may decline over a period of intense training. However, elevations in markers of oxidative stress were not evident.

Adult↗

PubMed2003

Case study of training, fitness, and nourishment of a dog driver during the Iditarod 1049-mile dogsled race.

The purpose of the present case study was threefold: (a) to estimate intake and expenditure of a dog driver (musher) while participating in the Iditarod, (b) to determine the hydration status of the musher at the completion of the event, and (c) to evaluate training related changes in aerobic capacity and body composition of a long-distance dog sled driver in preparation for and following completion of a 1049-mile (1692-km) sled dog race. Actual energy intake during the Iditarod Sled Dog Race was estimated at 8,921 kilojoules (kJ) per day. Nutrient intake expressed as percentage kJ of total energy (14%, 44% and 42% for protein, carbohydrates, and fat, respectively). Weight loss of .72 kg of body weight indicated an energy deficit of 1819 kJ per day during the race. Total energy needs per day were calculated to be 10,740 kJ/day. An increase in hematocrit and hemoglobin during the race may indicate dehydration during the event. There was an improvement in aerobic fitness during on-snow training as determined by ventilatory threshold and VO2peak data. Fat-free mass was maintained during training (46.4 kg), with a concomitant decrease in fat (2.4 kg). Fat-free mass was also maintained during the 12-day race.

Alaska↗

PubMed2004

The effects of health and environment on exercise-class participation in older, urban women.

This research investigated the effects of health and environmental factors on the dropout and intermittent nonattendance of an exercise program designed specifically for older, female, primary-care patients living in the inner city. Class-attendance records (n = 21,538) from a cohort 110 women were analyzed. Women who dropped out early had poorer perceived health and were more likely to report pain as an exercise barrier at baseline. Those who lived in a census tract where a larger percentage of workers walk to work were less likely to drop out early. Intermittent nonattendance was associated with adverse weather conditions including heat index above 90 degrees F, wind-chill index below 20 degrees F, overcast sky, and snow. Better attendance was associated with greater atmospheric pressure, as well as lower number of sunlight hours per day. This research highlights the need to better understand environmental barriers when promoting physical activities in older women.

Aged↗

PubMed2002

Antarctic Sea ice--a habitat for extremophiles.

The pack ice of Earth's polar oceans appears to be frozen white desert, devoid of life. However, beneath the snow lies a unique habitat for a group of bacteria and microscopic plants and animals that are encased in an ice matrix at low temperatures and light levels, with the only liquid being pockets of concentrated brines. Survival in these conditions requires a complex suite of physiological and metabolic adaptations, but sea-ice organisms thrive in the ice, and their prolific growth ensures they play a fundamental role in polar ecosystems. Apart from their ecological importance, the bacterial and algae species found in sea ice have become the focus for novel biotechnology, as well as being considered proxies for possible life forms on ice-covered extraterrestrial bodies.

Animals↗

PubMed2001

A new global mode of Earth deformation: seasonal cycle detected.

We have detected a global mode of Earth deformation that is predicted by theory. Precise positioning of Global Positioning System sites distributed worldwide reveals that during February to March, the Northern Hemisphere compresses (and the Southern Hemisphere expands), such that sites near the North Pole move downward by 3.0 millimeters, and sites near the equator are pulled northward by 1.5 millimeters. The opposite pattern of deformation occurs during August to September. We identify this pattern as the degree-one spherical harmonic response of an elastic Earth to increased winter loading of soil moisture, snow cover, and atmosphere. Data inversion shows the load moment's trajectory as a great circle traversing the continents, peaking at 6.9 x 10(22) kilogram meters near the North Pole in winter, indicating interhemispheric mass exchange of 1.0 x 10(16) +/- 0.2 x 10(16) kilograms.

Journal Article↗

PubMed2002

Ecological effects of climate fluctuations.

Climate influences a variety of ecological processes. These effects operate through local weather parameters such as temperature, wind, rain, snow, and ocean currents, as well as interactions among these. In the temperate zone, local variations in weather are often coupled over large geographic areas through the transient behavior of atmospheric planetary-scale waves. These variations drive temporally and spatially averaged exchanges of heat, momentum, and water vapor that ultimately determine growth, recruitment, and migration patterns. Recently, there have been several studies of the impact of large-scale climatic forcing on ecological systems. We review how two of the best-known climate phenomena-the North Atlantic Oscillation and the El Niño-Southern Oscillation-affect ecological patterns and processes in both marine and terrestrial systems.

Animals↗

PubMed2002

Environmental change and Antarctic seabird populations.

Recent changes in Antarctic seabird populations may reflect direct and indirect responses to regional climate change. The best long-term data for high-latitude Antarctic seabirds (Adélie and Emperor penguins and snow petrels) indicate that winter sea-ice has a profound influence. However, some effects are inconsistent between species and areas, some in opposite directions at different stages of breeding and life cycles, and others remain paradoxical. The combination of recent harvest driven changes and those caused by global warming may produce rapid shifts rather than gradual changes.

Animals↗

PubMed2002

Increase in the Asian southwest monsoon during the past four centuries.

Climate reconstructions reveal unprecedented warming in the past century; however, little is known about trends in aspects such as the monsoon. We reconstructed the monsoon winds for the past 1000 years using fossil Globigerina bulloides abundance in box cores from the Arabian Sea and found that monsoon wind strength increased during the past four centuries as the Northern Hemisphere warmed. We infer that the observed link between Eurasian snow cover and the southwest monsoon persists on a centennial scale. Alternatively, the forcing implicated in the warming trend (volcanic aerosols, solar output, and greenhouse gases) may directly affect the monsoon. Either interpretation is consistent with the hypothesis that the southwest monsoon strength will increase during the coming century as greenhouse gas concentrations continue to rise and northern latitudes continue to warm.

Journal Article↗

PubMed2003

Modern global climate change.

Modern climate change is dominated by human influences, which are now large enough to exceed the bounds of natural variability. The main source of global climate change is human-induced changes in atmospheric composition. These perturbations primarily result from emissions associated with energy use, but on local and regional scales, urbanization and land use changes are also important. Although there has been progress in monitoring and understanding climate change, there remain many scientific, technical, and institutional impediments to precisely planning for, adapting to, and mitigating the effects of climate change. There is still considerable uncertainty about the rates of change that can be expected, but it is clear that these changes will be increasingly manifested in important and tangible ways, such as changes in extremes of temperature and precipitation, decreases in seasonal and perennial snow and ice extent, and sea level rise. Anthropogenic climate change is now likely to continue for many centuries. We are venturing into the unknown with climate, and its associated impacts could be quite disruptive.

Journal Article↗

PubMed2004

Conserved genetic basis of a quantitative plumage trait involved in mate choice.

A key question in evolutionary genetics is whether shared genetic mechanisms underlie the independent evolution of similar phenotypes across phylogenetically divergent lineages. Here we show that in two classic examples of melanic plumage polymorphisms in birds, lesser snow geese (Anser c. caerulescens) and arctic skuas (Stercorarius parasiticus), melanism is perfectly associated with variation in the melanocortin-1 receptor (MC1R) gene. In both species, the degree of melanism correlates with the number of copies of variant MC1R alleles. Phylogenetic reconstructions of variant MC1R alleles in geese and skuas show that melanism is a derived trait that evolved in the Pleistocene.

Animals↗

PubMed2005

Role of land-surface changes in arctic summer warming.

A major challenge in predicting Earth's future climate state is to understand feedbacks that alter greenhouse-gas forcing. Here we synthesize field data from arctic Alaska, showing that terrestrial changes in summer albedo contribute substantially to recent high-latitude warming trends. Pronounced terrestrial summer warming in arctic Alaska correlates with a lengthening of the snow-free season that has increased atmospheric heating locally by about 3 watts per square meter per decade (similar in magnitude to the regional heating expected over multiple decades from a doubling of atmospheric CO2). The continuation of current trends in shrub and tree expansion could further amplify this atmospheric heating by two to seven times.

Alaska↗

PubMed2007

Mass-independent sulfur isotopic compositions in stratospheric volcanic eruptions.

The observed mass-independent sulfur isotopic composition (Delta33S) of volcanic sulfate from the Agung (March 1963) and Pinatubo (June 1991) eruptions recorded in the Antarctic snow provides a mechanism for documenting stratospheric events. The sign of Delta33S changes over time from an initial positive component to a negative value. Delta33S is created during photochemical oxidation of sulfur dioxide to sulfuric acid on a monthly time scale, which indicates a fast process. The reproducibility of the results reveals that Delta33S is a reliable tracer to chemically identify atmospheric processes involved during stratospheric volcanism.

Journal Article↗

PubMed2006

The impact of boreal forest fire on climate warming.

We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 +/- 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (-2.3 +/- 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming.

Ecosystem↗

PubMed1972

Lead-212 in the urban boundary layer of New York City.

The radioactive emanation product lead-212 is useful in estimating rates of air exchange within the urban boundary layer. The concentration of lead-212 is negligible in air of oceanic origin as well as in air above continental areas under snow cover. On several days when conditions were such that one of these types of air mass approached New York City, measurements were made which show that the source strength of lead-212 within the city is relatively constant. On two such days vertical profiles of the concentration of lead-212 were measured from the Empire State Building, which served as a sampling tower. From the data of these profiles and a two-layer model of the urban boundary layer, we estimate the vertical eddy diffusivity to be of the order of tens of square meters per second and the residence time of air within the street layer to be of the order of S minutes. These results are consistent with the observed distribution of stable lead and with an independent estimate of the eddy viscosity from a wind profile. Under moderate wind conditions and with a mixing depth of hundreds of meters, virtually all the horizontal transport of lead-212 and other tracers with street-level sources takes place in the advective layer.

Air Movements↗

PubMed1972

Peripheral thermoregulation: foot temperature in two Arctic canines.

Arctic foxes and gray wolves maintain their foot temperature just above the tissue freezing point (about -1 degrees C)when standing on extremely cold snow, or when the foot is immersed in a -35 degrees C bath in the laboratory. Proportional thermoregulation stabilized the subcutaneous temperature of the foot pad to a precision of +/- 0.7 degrees C (largest deviations). Selective shunting of blood-borne body heat through a cutaneous vascular plexus in the foot pad accounted for more than 99 percent of measured heat loss from the pad surface. Maximum energetic efficiency is achieved because the unit of heat exchange is located in the pad surface which contacts the cold substrate rather than throughout the pad.

Animals↗