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At least 1,531 records · Page 85Linked to original sources
PubMed2006

Resting and exercise energy use in Antarctica: effect of 50% restriction in temperate climate energy requirements.

OBJECTIVE: To determine the impact of energy restriction (ER) upon the previously reported increased resting and exercise-related oxygen utilization, reduced body temperature, increased serum TSH, and reduced serum free T3 concentrations found during Antarctic residence (AR). DESIGN: Prospective, intervention with both paired controls and a similar reference control group (RG). PATIENTS AND MEASUREMENTS: Seven subjects were assessed before and after a 50% ER period of 60 h. This ER was carried out within 30 days of arriving in Antarctica in October (OCT) and again after 10 months AR in August (AUG). During the periods of ER, mean energy consumption was 5662 +/- 1344 kJ/day in OCT and 5529 +/- 967 kJ/day in AUG. Resting metabolic rate (RMR), a calculated resting metabolic rate (RMR(reg)) using a submaximal work regression, serum TSH, FT3 and tympanic temperature (Tty) were measured. These values were compared with a similar RG of 12 subjects reported previously who were studied in California, USA before and then again during AR. RESULTS: Weight declined by 1.1 +/- 0.1 kg/day (OCT) and 0.92 +/- 0.2 kg/day (AUG) with ER, resulting in a reduction of body weight by 3.1 +/- 0.4% in OCT (P = 0.0001) and 2.5 +/- 0.4% in AUG (P = 0.0015) during AR. The RMR before ER did not change with AR and it was not significantly different from the RG studied in California. With ER the RMR tended to decline in both OCT (132 +/- 5 to 122 +/- 4 mlO2/min/m2) and AUG (134 +/- 5 to 126 +/- 5 mlO2/min/m2), but these were not significant. By contrast, RMR(reg) obtained before ER was increased with AR by 22.5 +/- 7.8% (P = 0.01) in OCT and by 28.1 +/- 7.0% (P = 0.0008) in AUG over the RG values obtained in California. RMR(reg) did not decrease with ER in either OCT or AUG. The total energy expenditure derived from these measures of weight loss suggests that 24-h energy requirements are 74.4%[95% confidence interval (CI) 2.6-146.3; P < 0.05] more than those expected in temperate climates. Tty declined by 0.6 +/- 0.2 degrees C (P < 0.01) with AR compared with the RG measured in California, but was not affected by either period of ER. ER had no effect on FT3 but tended to decrease serum TSH in AUG (P = 0.06). CONCLUSIONS: Exercise-related energy requirements are increased with AR. Moderate ER may reduce resting but not exercise-related energy expenditure and it is associated with a weight loss exceeding expectations for 50% restriction of temperate climate energy predictions.

Acclimatization↗
PubMed1992

Sleep patterns of European expatriates in a dry tropical climate.

Night sleep in sedentary African subjects living in the sahelian zone lasts from 7 h to 8 h, with high amounts of slow-wave sleep (SWS) and paradoxical sleep (PS), SWS being present in each sleep cycle. We report here on sleep patterns in 6 healthy male European expatriates (aged 32-39 years) living in the same tropical climate. Polysomnography was taken for 3 consecutive nights in February (mean ambient temperature, Ta: 29.5 degrees C), March (Ta: 31.6 degrees C) and May (Ta: 33.3 degrees C). Comparisons between seasons were made with an analysis of variance, with P >/= 0.05. Because of a first night effect, the first nocturnal recording was discarded. Total sleep time (TST) increased in May vs February and March (P < 0.05). Stage 2 was shorter in March than in February (P < 0.001) and its proportion decreased from February to March (P < 0.02) and from March to May (P < 0.05). Conversely, SWS increased from February to March and March to May (duration, P < 0.001; proportion, P < 0.05), due to an augmentation in stage 4 with more numerous and longer stage 4 phases. Stage 3 was also increased in May vs March. The latency to SWS was shorter in March. SWS was present in each sleep cycle. PS was high, but did not vary. The sleep pattern changes were directly correlated with Ta. In conclusion, Caucasians living in the tropics slept similarly to Africans. The seasonal sleep variations favour the hypothesis that SWS is increased when thermoregulatory processes are triggered, either through passive climatic heating or exercise-induced hyperthermia.

Journal Article↗
PubMed2006

Natural selection and climate change: temperature-linked spatial and temporal trends in gene frequency in Fagus sylvatica.

Rapid increases in global temperature are likely to impose strong directional selection on many plant populations, which must therefore adapt if they are to survive. Within populations, microgeographic genetic differentiation of individuals with respect to climate suggests that some populations may adapt to changing temperatures in the short-term through rapid changes in gene frequency. We used a genome scan to identify temperature-related adaptive differentiation of individuals of the tree species Fagus sylvatica. By combining molecular marker and dendrochronological data we assessed spatial and temporal variation in gene frequency at the locus identified as being under selection. We show that gene frequency at this locus varies predictably with temperature. The probability of the presence of the dominant marker allele shows a declining trend over the latter half of the 20th century, in parallel with rising temperatures in the region. Our results show that F. sylvatica populations may show some capacity for an in situ adaptive response to climate change. However as reported ongoing distributional changes demonstrate, this response is not enough to allow all populations of this species to persist in all of their current locations.

Alleles↗
PubMed1995

Quantitation of major allergens in dust samples from urban populations collected in different seasons in two climatic areas of the Basque region (Spain).

We present the results of allergen content evaluation in 80 dust samples from 31 homes of atopic patients from two climatic areas (humid and subhumid), collected in two seasons of the year (autumn and winter). Monoclonal antibody-based immunoassays were used to quantify Der p 1, Der f 1, Der 2, Lep d 1, and Fel d 1. The results were compared according to climate, season, and the type of sensitization (Pyroglyphidae mites, storage mites, or grass pollens). We underline the predominance of Dermatophagoides pteronyssinus (89% of samples) over D. farinae (16% of samples) in our environment. Der p 1 rates were higher in the humid area (Mann-Whitney P < 0.001), especially in the autumn (Wilcoxon P < 0.05). Lep d 1 was detected in 23% of samples and Lep d 1 levels were higher in the homes of patients sensitized to storage mites (Mann-Whitney P < 0.05), whereas this allergen was not detected in the homes of pollen-allergic patients. Fel d 1 was detected in nine of the 31 homes (16% of samples) although there was a cat in only one home.

Allergens↗
PubMed1995

School adjustment in sixth graders: parenting transitions, family climate, and peer norm effects.

This study examined whether sixth graders' (mean age = 11.86 years) adjustment to the school context (assessed by grades, achievement scores, and disruptive behavior) was affected by factors from both the family context (represented by students' reports of the number of parenting transitions experienced as well as current levels of supervision, acceptance, autonomy granting, and conflict in the family) and the peer context (represented by students' perceptions of peer norms supporting academic excellence). School adjustment was related to the number of parenting transitions experienced, family climate, and peer norms as well as to higher-order relations involving family climate and peer norms such that (a) high grade point averages occurred at only moderate levels of family supervision, (b) achievement scores were positively related to supervision at only low levels of family autonomy granting, and (c) grade point average was positively related to peer norms at only high levels of family acceptance.

Child↗
PubMed2006

Disaster risk, climate change and international development: scope for, and challenges to, integration.

Reducing losses to weather-related disasters, meeting the Millennium Development Goals and wider human development objectives, and implementing a successful response to climate change are aims that can only be accomplished if they are undertaken in an integrated manner. Currently, policy responses to address each of these independently may be redundant or, at worst, conflicting. We believe that this conflict can be attributed primarily to a lack of interaction and institutional overlap among the three communities of practice. Differences in language, method and political relevance may also contribute to the intellectual divide. Thus, this paper seeks to review the theoretical and policy linkages among disaster risk reduction, climate change and development. It finds that not only does action within one realm affect capacity for action in the others, but also that there is much that can be learnt and shared between realms in order to ensure a move towards a path of integrated and more sustainable development.

Disasters↗
PubMed2006

Reducing hazard vulnerability: towards a common approach between disaster risk reduction and climate adaptation.

Over the past few decades, four distinct and largely independent research and policy communities--disaster risk reduction, climate change adaptation, environmental management and poverty reduction--have been actively engaged in reducing socio-economic vulnerability to natural hazards. However, despite the significant efforts of these communities, the vulnerability of many individuals and communities to natural hazards continues to increase considerably. In particular, it is hydro-meteorological hazards that affect an increasing number of people and cause increasingly large economic losses. Arising from the realisation that these four communities have been largely working in isolation and enjoyed only limited success in reducing vulnerability, there is an emerging perceived need to strengthen significantly collaboration and to facilitate learning and information exchange between them. This article examines key communalities and differences between the climate change adaptation and disaster risk reduction communities, and proposes three exercises that would help to structure a multi-community dialogue and learning process.

Community Networks↗
PubMed2005

Mad tales from Bollywood: the impact of social, political, and economic climate on the portrayal of mental illness in Hindi films.

OBJECTIVE: To study the portrayal of mental illness (especially psychosis) in Hindi films since 1950 and to study the influence of prevalent social, political and economic factors on each portrayal. METHOD: Using two encyclopedias and one source book, films that had mental illness affecting one of the protagonists were identified. The social, economic and political factors were identified using history texts. RESULTS: In the 1960s after India became a Republic, the political climate was one of idealism and as a result the portrayal of mental illness was gentle, more international in its outlook, and used psychoanalytic techniques. In the 1970s and 1980s, as a result of increased political and bureaucratic corruption and an unstable political climate, the portrayals became harder and psychopaths were portrayed more often. In the 1980s, the trend continued with female psychopaths, and avenging women emerged as a major force because the political and judicial systems were seen as impotent in delivering justice. In the 1990s, following economic liberalization, the women were seen and used as possessions in society and the cinema, and portrayals of stalking and morbid jealousy increased. CONCLUSION: Hindi films since the 1950s appear to have been influenced by changing cultural norms which in turn affected the way mental illness is portrayed.

Adult↗
PubMed2001

Solar forcing of regional climate change during the Maunder Minimum.

We examine the climate response to solar irradiance changes between the late 17th-century Maunder Minimum and the late 18th century. Global average temperature changes are small (about 0.3 degrees to 0.4 degrees C) in both a climate model and empirical reconstructions. However, regional temperature changes are quite large. In the model, these occur primarily through a forced shift toward the low index state of the Arctic Oscillation/North Atlantic Oscillation as solar irradiance decreases. This leads to colder temperatures over the Northern Hemisphere continents, especially in winter (1 degrees to 2 degrees C), in agreement with historical records and proxy data for surface temperatures.

Journal Article↗
PubMed2002

Kilimanjaro ice core records: evidence of holocene climate change in tropical Africa.

Six ice cores from Kilimanjaro provide an approximately 11.7-thousand-year record of Holocene climate and environmental variability for eastern equatorial Africa, including three periods of abrupt climate change: approximately 8.3, approximately 5.2, and approximately 4 thousand years ago (ka). The latter is coincident with the "First Dark Age," the period of the greatest historically recorded drought in tropical Africa. Variable deposition of F- and Na+ during the African Humid Period suggests rapidly fluctuating lake levels between approximately 11.7 and 4 ka. Over the 20th century, the areal extent of Kilimanjaro's ice fields has decreased approximately 80%, and if current climatological conditions persist, the remaining ice fields are likely to disappear between 2015 and 2020.

Journal Article↗
PubMed2002

Climate effects of black carbon aerosols in China and India.

In recent decades, there has been a tendency toward increased summer floods in south China, increased drought in north China, and moderate cooling in China and India while most of the world has been warming. We used a global climate model to investigate possible aerosol contributions to these trends. We found precipitation and temperature changes in the model that were comparable to those observed if the aerosols included a large proportion of absorbing black carbon ("soot"), similar to observed amounts. Absorbing aerosols heat the air, alter regional atmospheric stability and vertical motions, and affect the large-scale circulation and hydrologic cycle with significant regional climate effects.

Journal Article↗
PubMed2002

Cosmic rays, clouds, and climate.

It has been proposed that Earth's climate could be affected by changes in cloudiness caused by variations in the intensity of galactic cosmic rays in the atmosphere. This proposal stems from an observed correlation between cosmic ray intensity and Earth's average cloud cover over the course of one solar cycle. Some scientists question the reliability of the observations, whereas others, who accept them as reliable, suggest that the correlation may be caused by other physical phenomena with decadal periods or by a response to volcanic activity or El Niño. Nevertheless, the observation has raised the intriguing possibility that a cosmic ray-cloud interaction may help explain how a relatively small change in solar output can produce much larger changes in Earth's climate. Physical mechanisms have been proposed to explain how cosmic rays could affect clouds, but they need to be investigated further if the observation is to become more than just another correlation among geophysical variables.

Journal Article↗
PubMed2003

Asynchronous climate changes in the North Atlantic and Japan during the last termination.

Pollen records from the annually laminated sediment sequence in Lake Suigetsu, Japan, suggest a sequence of climate changes during the Last Termination that resembles that of the North Atlantic region but with noticeable differences in timing. An interstadial interval commenced a few centuries earlier [approximately 15,000 years before the present (yr B.P.)] than the North Atlantic GI-1 (Bölling) event. Conversely, the onset of a Younger Dryas (YD)-like cold reversal (12,300 to 11,250 yr B.P.) postdated the North Atlantic GS-1 (YD) event by a few centuries. Climate in the Far East during the Last Termination reflected solar insolation changes as much as Atlantic influences.

Journal Article↗
PubMed2003

Indian Ocean climate and an absolute chronology over Dansgaard/Oeschger events 9 to 13.

Oxygen-isotope ratios of a stalagmite from Socotra Island in the Indian Ocean provide a record of changes in monsoon precipitation and climate for the time period from 42 to 55 thousand years before the present. The pattern of precipitation bears a striking resemblance to the oxygen-isotope record from Greenland ice cores, with increased tropical precipitation associated with warm periods in the high northern latitudes. The largest change, at the onset of interstadial 12, occurred very rapidly, in about 25 years. The chronology of the events found in our record requires a reevaluation of previously published time scales for climate events during this period.

Journal Article↗
PubMed2003

Carbonate deposition, climate stability, and Neoproterozoic ice ages.

The evolutionary success of planktic calcifiers during the Phanerozoic stabilized the climate system by introducing a new mechanism that acts to buffer ocean carbonate-ion concentration: the saturation-dependent preservation of carbonate in sea-floor sediments. Before this, buffering was primarily accomplished by adjustment of shallow-water carbonate deposition to balance oceanic inputs from weathering on land. Neoproterozoic ice ages of near-global extent and multimillion-year duration and the formation of distinctive sedimentary (cap) carbonates can thus be understood in terms of the greater sensitivity of the Precambrian carbon cycle to the loss of shallow-water environments and CO2-climate feedback on ice-sheet growth.

Journal Article↗
PubMed2003

Air pollution and climate-forcing impacts of a global hydrogen economy.

If today's surface traffic fleet were powered entirely by hydrogen fuel cell technology, anthropogenic emissions of the ozone precursors nitrogen oxide (NOx) and carbon monoxide could be reduced by up to 50%, leading to significant improvements in air quality throughout the Northern Hemisphere. Model simulations of such a scenario predict a decrease in global OH and an increased lifetime of methane, caused primarily by the reduction of the NOx emissions. The sign of the change in climate forcing caused by carbon dioxide and methane depends on the technology used to generate the molecular hydrogen. A possible rise in atmospheric hydrogen concentrations is unlikely to cause significant perturbations of the climate system.

Journal Article↗
PubMed2003

Atmospheric science. Ozone and climate change.

Over the past 40 years, Southern Hemisphere circumpolar westerly winds have strengthened. In his Perspective, Karoly highlights the modeling study by Gillett and Thompson, who show that these observed Southern Hemisphere climate changes in spring and summer can be explained as a response to stratospheric ozone depletion over Antarctica. The observed strengthening of the circumpolar westerlies in winter is less likely to be the response to springtime Antarctic ozone depletion, but may be due in part to increasing atmospheric greenhouse gases. Understanding the different causes and practical impacts of these trends in Southern Hemisphere circulation is an important next step for climate researchers.

Comment↗
PubMed2004

New Zealand maritime glaciation: millennial-scale southern climate change since 3.9 Ma.

Ocean Drilling Program Site 1119 is ideally located to intercept discharges of sediment from the mid-latitude glaciers of the New Zealand Southern Alps. The natural gamma ray signal from the site's sediment core contains a history of the South Island mountain ice cap since 3.9 million years ago (Ma). The younger record, to 0.37 Ma, resembles the climatic history of Antarctica as manifested by the Vostok ice core. Beyond, and back to the late Pliocene, the record may serve as a proxy for both mid-latitude and Antarctic polar plateau air temperature. The gamma ray signal, which is atmospheric, also resembles the ocean climate history represented by oxygen isotope time series.

Journal Article↗