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At least 829 records · Page 46Linked to original sources
PubMed1977

Thermal data from helicopters operating in a sub-arctic environment.

Using automatic and observer-operated equipment for monitoring thermal data, observations have been made during Royal Navy Wessex 5 helicopter operations in a sub-Arctic climate. Measurements were taken in flight of front and rear cabin temperatures and aircrew deep body and skin temperatures. The results indicate that the "arcticised" aircraft used had more than enough cabin heating to alleviate cold stress on the aircrew.

Aerospace Medicine↗
PubMed2004

Ecosystem carbon storage in arctic tundra reduced by long-term nutrient fertilization.

Global warming is predicted to be most pronounced at high latitudes, and observational evidence over the past 25 years suggests that this warming is already under way. One-third of the global soil carbon pool is stored in northern latitudes, so there is considerable interest in understanding how the carbon balance of northern ecosystems will respond to climate warming. Observations of controls over plant productivity in tundra and boreal ecosystems have been used to build a conceptual model of response to warming, where warmer soils and increased decomposition of plant litter increase nutrient availability, which, in turn, stimulates plant production and increases ecosystem carbon storage. Here we present the results of a long-term fertilization experiment in Alaskan tundra, in which increased nutrient availability caused a net ecosystem loss of almost 2,000 grams of carbon per square meter over 20 years. We found that annual aboveground plant production doubled during the experiment. Losses of carbon and nitrogen from deep soil layers, however, were substantial and more than offset the increased carbon and nitrogen storage in plant biomass and litter. Our study suggests that projected release of soil nutrients associated with high-latitude warming may further amplify carbon release from soils, causing a net loss of ecosystem carbon and a positive feedback to climate warming.

Arctic Regions↗
PubMed1973

Problem of the old and the cold.

A pilot winter study of body temperatures using new measuring techniques was tested on 72 volunteers aged 65 or more living in Portsmouth. The body temperatures were related to their environmental temperature and living conditions. No case of serious hypothermia was found, but the study confirms that elderly people have lower body temperatures and suggests that the coldest individuals tended to be the least aware of discomfort from the cold; this may well place them "at risk" for developing hypothermia.

Aged↗
PubMed1986

[Chilblains].

Chilblain is a frostbite, it belongs to the vascular acrosyndromes by the mere fact of symmetrical lesions and to the dystrophic group by its organic obstructive and thrombotic microangiopathy, especially of venules. Chilblain is conditional on a dysesthesia for cold, diagnosis is easy if in the know, prognosis as usual good and treatment must be more preventive than curative.

Chilblains↗
PubMed2003

Isolation and characterization of new strains of methanogens from cold terrestrial habitats.

Five strains of methanogenic archaea (MT, MS, MM, MSP, ZB) were isolated from permanently and periodically cold terrestrial habitats. Physiological and morphological studies, as well as phylogenetic analyses of the new isolates were performed. Based on sequences of the 16S rRNA and methyl-coenzyme M reductase a-subunit (mcrA) genes all new isolates are closely related to known mesophilic and psychrotolerant methanogens. Both, phylogenetic analyses and phenotypic properties allow to classify strains MT, MS, and MM as members of the genus Methanosarcina. Strain MT is a new ecotype of Methanosarcina mazei, whereas strains MM and MS are very similar to each other and can be assigned to the recently described psychrotolerant species Methanosarcina lacustris. The hydrogenotrophic strain MSP is a new ecotype of the genus Methanocorpusculum. The obligately methylotrophic strain ZB is closely related to Methanomethylovorans hollandica and can be classified as new ecotype of this species. All new isolates, including the strains from permanently cold environments, are not true psychrophiles according to their growth temperature characteristics. In spite of the ability of all isolates to grow at temperatures as low as 1-5 degrees C, all of them have their growth optima in the range of moderate temperatures (25-35 degrees C). Thus, they can be regarded as psychrotolerant organisms. Psychrotolerant methanogens are thought to play an important role in methane production in both, habitats under seasonal temperature variations or from permanently cold areas.

Animals↗
PubMed2005

A report of decomposition rates of a special burial type in Edmonton, Alberta from an experimental field study.

Regional studies that examine decomposition rates of certain faunal remains can help to determine time since death. Forensic anthropologists have long used qualitative decomposition data, but linking these to more quantitative data could improve time since death estimations. Experiments were developed in which domestic pigs (Sus scrofa) were buried with varying characteristics then excavated and observed over a period of 15 months in Edmonton, Alberta. Data recorded after two weeks, five weeks, three months, one year, and 15 months were correlated with stages of decomposition as well as time since death, climate data, grave type, clothing, burial depth, and other factors. Results from these experiments provide useful regional information about stages of decomposition in a burial context. Pigs buried in June were skeletonized by approximately three to five weeks, while those buried in May were skeletonized between five weeks and three months. Climate data, insects, and grave type contributed the most to advanced decomposition, mainly in the form of mummification, and skeletonization.

Alberta↗
PubMed2006

Expected coalescence times and segregating sites in a model of glacial cycles.

The climatic fluctuations of the Quaternary have influenced the distribution of numerous plant and animal species. Several species suffer population reduction and fragmentation, becoming restricted to refugia during glacial periods and expanding again during interglacials. The reduction in population size may reduce the effective population size, mean coalescence time and genetic variation, whereas an increased subdivision may have the opposite effect. To investigate these two opposing forces, we proposed a model in which a panmictic and a structured phase alternate, corresponding to interglacial and glacial periods. From this model, we derived an expression for the expected coalescence time and number of segregating sites for a pair of genes. We observed that increasing the number of demes or the duration of the structured phases causes an increase in coalescence time and expected levels of genetic variation. We compared numerical results with the ones expected for a panmictic population of constant size, and showed that the mean number of segregating sites can be greater in our model even when population size is much smaller in the structured phases. This points to the importance of population structure in the history of species subject to climatic fluctuations, and helps explain the long gene genealogies observed in several organisms.

Animals↗
PubMed2001

Indication of global deforestation at the Cretaceous-Tertiary boundary by New Zealand fern spike.

The devastating effect on terrestrial plant communities of a bolide impact at the Cretaceous-Tertiary boundary is shown in fossil pollen and spore assemblages by a diverse flora being abruptly replaced by one dominated by a few species of fern. Well documented in North America, this fern spike signals widespread deforestation due to an impact winter or massive wildfires. A Southern Hemisphere record of a fern spike, together with a large iridium anomaly, indicates that the devastation was truly global. Recovery of New Zealand plant communities followed a pattern consistent with major climatic perturbations occurring after an impact winter that was possibly preceded by global wildfires.

Animals↗
PubMed2003

Evidence for survival of Pleistocene climatic changes in Northern refugia by the land snail Trochoidea geyeri (Soós 1926) (Helicellinae, Stylommatophora).

BACKGROUND: The study of organisms with restricted dispersal abilities and presence in the fossil record is particularly adequate to understand the impact of climate changes on the distribution and genetic structure of species. Trochoidea geyeri (Soós 1926) is a land snail restricted to a patchy, insular distribution in Germany and France. Fossil evidence suggests that current populations of T. geyeri are relicts of a much more widespread distribution during more favourable climatic periods in the Pleistocene. RESULTS: Phylogeographic analysis of the mitochondrial 16S rDNA and nuclear ITS-1 sequence variation was used to infer the history of the remnant populations of T. geyeri. Nested clade analysis for both loci suggested that the origin of the species is in the Provence from where it expanded its range first to Southwest France and subsequently from there to Germany. Estimated divergence times predating the last glacial maximum between 25-17 ka implied that the colonization of the northern part of the current species range occurred during the Pleistocene. CONCLUSION: We conclude that T. geyeri could quite successfully persist in cryptic refugia during major climatic changes in the past, despite of a restricted capacity of individuals to actively avoid unfavourable conditions.

Animals↗
PubMed1966

The possibility of life in outer space.

Experiments were carried out dealing with the effect of extreme factors on microorganisms. Methods for microbiological analysis of meteorites were developed. The effect of temperature, from -20 degrees C to +15 degrees C, on trypsine activity was studied. It was shown that at about -3 degrees C a definite intramolecular reorganization occurs in the enzyme, leading to decreased activation energy. Previously reported resistance of microorganisms to high vacuum was confirmed. New species were tested at l0(-8)-10(-9) mm Hg. It was shown that very thin metal and metal oxide films, as well as films from other substances, may fully protect microorganisms from the hazardous effect of UV rays. By using an artificial climate, camera forms of microorganisms were selected which have the highest resistance to the whole complex of Martian climatic factors. Pigmented and spore-forming microorganisms resist UV up to a dose of 4.04 x 10(8) erg/cm2. There are microorganisms on Earth which show some activity in soil at a relative humidity of 0.096-0.196%. Preliminary data permit one to assume the possibility of existence of Earth-like forms on Mars. The majority of meteorites are accessible to Earth microorganisms. While choosing a meteorite for microbiological analysis it is necessary to consider the soil and climatic factors of the country where the latter has been found.

Bacillus↗
PubMed1977

Thermoregulation of the Japanese macaque living in a snowy mountain area.

A field investigation was conducted to study the thermoregulatory responses in nine Japanese macaques (Macaca fuscata) living in a snowy mountain area, Jigoku-Dani (Hell Valley, about 1,000 m above sea level) in Shiga Heights in central Japan in late January 1975. At about the same time, a laboratory study was made on four Japanese macaques reared in mild climate in an outdoor cage in Inuyama City. In the Hell Valley (HV) monkeys, no significant change in metabolic rate was observed at Ta between -1.4 and 28.3 degrees C, while the rectal temperature was maintained at normal level. In the cold environment, the skin temperatures of HV monkeys were significantly higher than those of the monkeys living indoors previously studied. Similar patterns of metabolic and thermal responses were observed in Inuyama monkeys living outdoors, but to a lesser degree. The hair on the back and abdomen in the HV monkeys was significantly longer than that of Iuyama monkeys living indoors. It is suggested that the thick fur of HV monkeys may account for, if not all, the thermoregulatory responses of the Japanese macaque in snowy mountain areas.

Animals↗
PubMedDate not supplied

[Hormonal metabolic status of the human body under the conditions of the Far North].

The concentrations of hormones (ACTH, cortisol, aldosterone, thyrotrophin, thyroxine, triiodothyronine, growth hormone, insulin, prolactin and testosterone), electrolytes (Na and K) as well as glucose and triglycerides were measured in 10 athletes who made a 380 km ski expedition in the Far North at ambient temperatures of -32 to -34 degrees C. Human adaptation to the geographic and climatic conditions of high latitudes was accompanied by noticeable changes in the incretory function of the adenopituitary, thyroid gland, adrenals and gonads. The data obtained indicate that a ski trip in the Far North produces a distinct stress with physical and cold components being predominant.

Adult↗
PubMed2001

The effect of season, occupation and repeated winterings on anthropologic and physiological characteristics in Russian antarctic staff.

UNLABELLED: Thirty anthropometric and ten physiological parameters were examined over a 10-month-period in 1985-86, in 66 male polar explorers, aged 25-61 years, at an Antarctic station (Mirny observatory). For 30 of these persons this was their first wintering in Antarctic while the remaining 36 had wintered there at least once before. The mentioned measurements were taken on 3 different occasions in April, September and January corresponding in the Antarctic to the beginning of the polar night and interim season period and the beginning of the polar day. Subjects of the investigation belonged to 3 occupational groups: administrative personnel, scientific staff, and manual laborers. Extended statistical analysis of the data was carried out in an attempt to distinguish the dynamics of the studied parameters in relation to the season of wintering (Climate), the number of previous winterings (Frequency), the type of occupation (Work), and their interactions. Multifactorial statistical analyses were also performed, so as to adjust for age of subjects, which is a requisite for evaluating the factor of repeating winterings, obviously age-related. Changes in a number of characteristics were clearly recognized as connected with the factor of repeating winterings, to wit: 1) Anthropometric parameters such as or subcutaneous fat and relative muscle mass; 2) Parameters pertaining to speed of neuromuscular response such as wrist muscle effort, or time of simple motor response; and 3) Physiological parameters encompassing vascular--blood pressure and respiratory--spirometric measurements. CONCLUSION: Our findings suggest that frequency of repeated winterings is not a leading factor influencing physical status of examinees. Occupational status of examinees alone or in interaction with repeated winterings and seasonal climatic factors have more prominent impact on the well-being of polar explorers.

Acclimatization↗
PubMed2003

[Results of studying of the pathomorphism of pulmonary tuberculosis in Iakutiia].

The paper summarizes the results of studies into the pathological anatomy and pathomorphism of pulmonary tuberculosis in Yakutia, which have been conducted by the Department of Anatomy, Yakutsk State University Medical Institute, over 36 years. A morphological comparative analysis of autopsies of individuals who died from different forms in the pre-antibacterial and antibacterial periods and surgical materials were used as a major source of data. More than 1,000 autopsies made it possible to define a wide range of behavioral patterns and the morphological features of pulmonary tuberculosis under the extreme climatic conditions of the Far North. These findings have made a significant contribution to the development of the new scientific school Northern Phthisiology.

Arctic Regions↗