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PubMed2002

Mechanisms promoting higher growth rate in arctic than in temperate shorebirds.

We compared prefledging growth, energy expenditure, and time budgets in the arctic-breeding red knot (Calidris canutus) to those in temperate shorebirds, to investigate how arctic chicks achieve a high growth rate despite energetic difficulties associated with precocial development in a cold climate. Growth rate of knot chicks was very high compared to other, mainly temperate, shorebirds of their size, but strongly correlated with weather-induced and seasonal variation in availability of invertebrate prey. Red knot chicks sought less parental brooding and foraged more at the same mass and temperature than chicks of three temperate shorebird species studied in The Netherlands. Fast growth and high muscular activity in the cold tundra environment led to high energy expenditure, as measured using doubly labelled water: total metabolised energy over the 18-day prefledging period was 89% above an allometric prediction, and among the highest values reported for birds. A comparative simulation model based on our observations and data for temperate shorebird chicks showed that several factors combine to enable red knots to meet these high energy requirements: (1) the greater cold-hardiness of red knot chicks increases time available for foraging; (2) their fast growth further shortens the period in which chicks depend on brooding; and (3) the 24-h daylight increases potential foraging time, though knots apparently did not make full use of this. These mechanisms buffer the loss of foraging time due to increased need for brooding at arctic temperatures, but not enough to satisfy the high energy requirements without invoking (4) a higher foraging intake rate as an explanation. Since surface-active arthropods were not more abundant in our arctic study site than in a temperate grassland, this may be due to easier detection or capture of prey in the tundra. The model also suggested that the cold-hardiness of red knot chicks is critical in allowing them sufficient feeding time during the first week of life. Chicks hatched just after the peak of prey abundance in mid-July, but their food requirements were maximal at older ages, when arthropods were already declining. Snow cover early in the season prevented a better temporal match between chick energy requirements and food availability, and this may enforce selection for rapid growth.

Adaptation, Physiological↗
PubMed1986

Epidemiologic survey of vibration syndrome among riveters, chippers and grinders in the railroad system of the People's Republic of China.

Vibration syndrome caused by hand-held vibrating tools in 14 locomotive and rolling stock plants in four regions of the People's Republic of China (south, north, middlewest, and northeast) and the influence of climatic factors on its prevalence rate were studied. For 1,028 male workers (705 riveters, 284 chippers, and 39 grinders), the prevalence rate of the syndrome was 13.4% and for a reference group of 256 workers it was 1.6%. The prevalence rate of white finger in the four regions differed and was higher in northeast and north China than in south and middlewest China. This finding suggests that cold climate and humidity may be causative factors of the vibration syndrome.

Adolescent↗
PubMed1997

A case of Plesiomonas shigelloides cellulitis and bacteraemia from northern Europe.

Bacteremia caused by Plesiomonas shigelloides is a rare event, often associated with consumption of seafood and fresh or estuarine water in temperate or tropical climates. Most patients have showed underlying health disorders. Here we present a case of P. shigelloides septicaemia and cellulitis of the left hand associated with fish handling in Northern Sweden (65 degrees latitude north). The patient, who suffered from multiple myeloma, recovered uneventfully after initial treatment with intravenous cefuroxime followed by a course of oral ciprofloxacin. P. shigelloides seems to be ubiquitous in freshwater world-wide and may cause invasive infections also in cold climate areas.

Aged↗
PubMedDate not supplied

The Bourgeois-Pichat's biometric method and the influence of climate: new evidences from late 19th-century Italy.

This paper examines to which extent seasonal and climatic conditions might affect the reliability of the Bourgeois-Pichat's method. Other scholars have already argued on this issue, but although climate has often been claimed to explain part of the differentials in mortality figures among Italian regions, to date its impact has not actually been recognized and quantitatively evaluated. To test such hypothesis data at the regional level from late 19th-century Italy have been analyzed. Our analysis of the biometric components revealed a strong bias in the estimates of the endogenous and exogenous components in the first month of life. Variations in infant mortality among Italian regions correlated with variations in the endogenous levels rather than in the exogenous levels of infant (neonatal) mortality, as it was expected owing to the infective nature of the diseases climate might induce. Specifically, Northern and colder regions featured high figures for both neonatal mortality and the endogenous component, while the opposite scheme applied to the Southern, more temperate regions. Finally, the reasons for such misleading results were investigated. It emerged that the model's assumption of a constant and invariant proportion of neonatal exogenous deaths to the total amount of exogenous deaths was not matched by the Italian data. This situation caused the excess neonatal exogenous mortality, especially that induced by cold climate in Northern regions, to be wrongly counted in the endogenous component.

Algorithms↗
PubMed2003

Atmospheric deposition of V, Cr, and Ni since the late glacial: effects of climatic cycles, human impacts, and comparison with crustal abundances.

Vanadium, Cr, and Ni accumulating in a Swiss peat bog since 12 370 14C yr B.P. have been measured using inductively coupled plasma-mass spectrometry (ICP-MS) after acid dissolution in a microwave autoclave. Strict quality control schemes were applied to guarantee the accuracy of the applied analytical methodology. The concentration gradients in the peat column and comparison with Pb indicate that V, Cr, and Ni are effectively immobile in the ombrotrophic section of the peat profile but that Ni is added to the minerotrophic peat layers by chemical weathering of the underlying sediments. The lowest metal concentrations were found during the Holocene climate optimum (5320-8230 14C yr B.P.) when "natural background" values averaged 0.55 +/- 0.13 microg g(-1) V, 0.76 +/- 0.17 microg g(-1) Cr, and 0.46 +/- 0.09 microg g(-1) Ni (n = 18); given the average bulk density (0.05 g/cm3) and accumulation rate (0.05 cm/ yr) of peat in this zone, the corresponding atmospheric fluxes are approximately 14, 19, and 12 microg m(-2) yr(-1) for V, Cr, and Ni, respectively. The highest concentrations of V, Cr, and Ni were found during the Younger Dryas cold climate event (centered at 10 590 14C yr B.P.) when background values were exceeded by about 40 times. Elevated concentrations and accumulation rates were also found at 8230 and 5320 14C yr B.P., which are consistent with the elevated dust fluxes recorded by Greenland ice cores. By far the greatest contribution of the three elements to the peat inventory is atmospheric soil dust, and the metal fluxes vary not only with climate change but also land-use history (especially the beginning of forest clearing for agriculture ca. 6 millennia ago). The V/Sc, Cr/Sc, and Ni/ Sc ratios were remarkably similar to their corresponding ratios in the earth's crust until the onset of the Industrial Revolution (240 14C yr B.P.), which largely validates the use of crustal concentrations for calculating enrichment factors (EF) for these elements. In modern samples, the EFs of V, Cr, and Ni reach maximum values between 2.4 and 4.1, relative to background; anthropogenic emissions are a more likely explanation of the elevated EFs than either plant uptake or chemical diagenesis. This study demonstrates the usefulness of peat bogs as archives of atmospheric metal deposition and underpins the potential of peat cores to help distinguish between lithogenic and anthropogenic metal sources.

Air Pollutants↗
PubMed2000

Geophysical, archaeological, and historical evidence support a solar-output model for climate change.

Although the processes of climate change are not completely understood, an important causal candidate is variation in total solar output. Reported cycles in various climate-proxy data show a tendency to emulate a fundamental harmonic sequence of a basic solar-cycle length (11 years) multiplied by 2(N) (where N equals a positive or negative integer). A simple additive model for total solar-output variations was developed by superimposing a progression of fundamental harmonic cycles with slightly increasing amplitudes. The timeline of the model was calibrated to the Pleistocene/Holocene boundary at 9,000 years before present. The calibrated model was compared with geophysical, archaeological, and historical evidence of warm or cold climates during the Holocene. The evidence of periods of several centuries of cooler climates worldwide called "little ice ages," similar to the period anno Domini (A.D.) 1280-1860 and reoccurring approximately every 1,300 years, corresponds well with fluctuations in modeled solar output. A more detailed examination of the climate sensitive history of the last 1, 000 years further supports the model. Extrapolation of the model into the future suggests a gradual cooling during the next few centuries with intermittent minor warmups and a return to near little-ice-age conditions within the next 500 years. This cool period then may be followed approximately 1,500 years from now by a return to altithermal conditions similar to the previous Holocene Maximum.

Journal Article↗
PubMedDate not supplied

Variation and causal factors of craniofacial robusticity in Patagonian hunter-gatherers from the late Holocene.

Fueguian-Patagonian skulls have been characterized as some of the most robust of any modern crania. However, the causal factors of such robusticity remain unsettled. We assess within- and among-sample cranial robusticity of seven samples from continental Patagonia and Tierra del Fuego, using geometric morphometric techniques. In addition, the biomechanical, phylogenetic, and climatic hypotheses proposed to account for robusticity in such samples are discussed. Two Amerindian samples of farmers and two early middle Holocene samples from South America were included. The results show: 1) large variation in craniofacial robusticity among Patagonian samples, with the highest robusticity in samples from south continental Patagonia and Isla Grande of Tierra del Fuego, whereas central and north Patagonian samples display the same degree of robusticity as farmer samples; 2) that early middle Holocene samples display lower levels of robusticity than South Patagonian samples; and 3) strong association between latitude and craniofacial robusticity, with the most robust craniofacial morphologies occurring at the highest latitudes. In consequence, neither masticatory stress nor retention of ancestral features is supported by the morphological evidence analyzed. Hence it is hypothesized that endocrine changes related to cold climate may be a plausible explanation for several craniofacial features found in Fueguian and south continental Patagonian samples, such as their large masticatory component, and pronounced supraorbital ridge and glabellar region.

Adaptation, Physiological↗
PubMed2004

Bioaugmentation for nitrification at cold temperatures.

Bioaugmentation of nitrifying bacteria for short solids retention time (short-SRT) nitrification is an attractive alternative for wastewater treatment plants in cold climates or for those in the process of upgrading to include nitrification. One possible source of ammonia for the production of nitrifying bacteria is the liquor generated during the dewatering of anaerobically digested sludges. The objectives of this study was to determine the impact of sudden decrease in temperature on nitrification rates and to determine if nitrification could be accomplished in sequencing batch reactors (SBRs) at 10 degrees C by seeding nitrifying bacteria acclimated to 20 degrees C. In this research, biomass produced during warm nitrification of dewatering liquor was seeded into cold SBRs at various hydraulic retention times from 43.3 to 96 h. The average decreases in nitrification rates were 58%, 71% and 82% for biomass cooled to 10 degrees C when the biomass was acclimated to 20 degrees C, 25 degrees C and 30 degrees C, respectively. The seeded SRTs of the cold SBRs were raised above the minimum solids retention time (SRT(min)) required for nitrification. Full ammonia nitrogen removal was achieved in cold SBRs that were operated at an apparent SRT less than SRT(min).

Bacteria, Anaerobic↗
PubMed1999

The impact of growing-season length variability on carbon assimilation and evapotranspiration over 88 years in the eastern US deciduous forest

Recent research suggests that increases in growing-season length (GSL) in mid-northern latitudes may be partially responsible for increased forest growth and carbon sequestration. We used the BIOME-BGC ecosystem model to investigate the impacts of including a dynamically regulated GSL on simulated carbon and water balance over a historical 88-year record (1900-1987) for 12 sites in the eastern USA deciduous broadleaf forest. For individual sites, the predicted GSL regularly varied by more than 15 days. When grouped into three climatic zones, GSL variability was still large and rapid. There is a recent trend in colder, northern sites toward a longer GSL, but not in moderate and warm climates. The results show that, for all sites, prediction of a long GSL versus using the mean GSL increased net ecosystem production (NEP), gross primary production (GPP), and evapotranspiration (ET); conversely a short GSL is predicted to decrease these parameters. On an absolute basis, differences in GPP between the dynamic and mean GSL simulations were larger than the differences in NEP. As a percentage difference, though, NEP was much more sensitive to changes in GSL than were either GPP or ET. On average, a 1-day change in GSL changed NEP by 1.6%, GPP by 0.5%, and ET by 0.2%. Predictions of NEP and GPP in cold climates were more sensitive to changes in GSL than were predictions in warm climates. ET was not similarly sensitive. First, our results strongly agree with field measurements showing a high correlation between NEP and dates of spring growth, and second they suggest that persistent increases in GSL may lead to long-term increases in carbon storage.

Journal Article↗
PubMed1996

Physiological and subjective responses to thermal transients of exercising subjects dressed in cold-protective clothing.

In cold conditions variations in the physical activity of clothed individuals and rest periods in a moderate temperature may result in a disturbance of heat balance and thermal comfort of the individual, in particular when sweating occurs. The purpose of the study was to examine thermal responses in persons dressed in winter clothing during changes of exercise intensity (high to low) and ambient temperature, and to investigate whether there were any effects on these responses due to fibre material (wool and synthetic). Two types of transient condition were studied, an exercise level transient (E) and a temperature transient (T). Ten healthy male subjects dressed in multi-layer winter clothing ensembles with different levels of total insulation walked on a treadmill at an ambient temperature of -10 degrees C. The garments were manufactured from wool, giving insulations of 2.6 clo, in T only and otherwise of 3.2 clo, or synthetic fibres, giving insulations of 2.4 clo in T only and otherwise of 3.1 clo. In E the subjects exercised at a high intensity for 50 min followed by 60 min walking at low intensity. In T they walked at a moderate speed for 90 min in ambient temperature of -10 degrees C, rested in temperatures of +22 degrees C for 30 min and walked in the cold climatic chamber for another 45 min. The skin temperature, sweating responses and thermal sensations were higher/warmer with increasing insulation during exercise. The wool fibre material resulted in a slightly higher mean skin temperature (about 0.3 degree C) during exercise, but no differences in subjective responses were found. The rest period had only a small influence on the subsequent thermal responses. The interindividual variations in thermal responses were large.

Adult↗
PubMed1993

Five year digital replantation series from the frigid zone of China.

A series of 208 digital replantations from the frigid zone within the People's Republic of China is presented. The extremely cold climate (often -20 degrees C to -30 degrees C) presents the problem of warming exposed amputated digits prior to replantation without causing further damage. An overall replantation survival rate of 94% is reported, and this includes 45 cases of multiple digit amputation. Longer periods of ischemia seem to be tolerated under these unusually frigid conditions. Problems encountered within the series and suggestions for successful outcomes are discussed.

Adolescent↗
PubMed1998

[Definition and epidemiology of vascular acrosyndromes].

Vascular acrosyndromes group several disorders around Raynaud's phenomenon, characterized by a distal involvement and a vasomotor pathogenesis. Their exact mechanisms remain unknown, but epidemiological data favour disturbances of thermoregulation: cold climate, outdoor occupation and low body mass index are significant risk factors for most of them. Acrosyndromes with vasoconstriction are highly prevalent in France: 10 to 15% for Raynaud's phenomenon and acrocyanosis; 2 to 6% for chilblains. Acrosyndromes with vasodilatation (acrocholose, erythermalgia) are much rare. There is no link between Raynaud's phenomenon and tobacco use, alcohol consumption, oestrogen treatment, carpal tunnel syndrome or thoracic outlet syndrome. By contrast, the role of connective tissue diseases and occupational disorders (vibration exposure and hand-hammer syndrome) are established.

Age Factors↗
PubMed2001

Confounding and effect modification in the short-term effects of ambient particles on total mortality: results from 29 European cities within the APHEA2 project.

We present the results of the Air Pollution and Health: A European Approach 2 (APHEA2) project on short-term effects of ambient particles on mortality with emphasis on effect modification. We used daily measurements for particulate matter less than 10 microm in aerodynamic diameter (PM10) and/or black smoke from 29 European cities. We considered confounding from other pollutants as well as meteorologic and chronologic variables. We investigated several variables describing the cities' pollution, climate, population, and geography as potential effect modifiers. For the individual city analysis, generalized additive models extending Poisson regression, using a smoother to control for seasonal patterns, were applied. To provide quantitative summaries of the results and explain remaining heterogeneity, we applied second-stage regression models. The estimated increase in the daily number of deaths for all ages for a 10 microg/m3 increase in daily PM10 or black smoke concentrations was 0.6% [95% confidence interval (CI) = 0.4-0.8%], whereas for the elderly it was slightly higher. We found important effect modification for several of the variables studied. Thus, in a city with low average NO2, the estimated increase in daily mortality for an increase of 10 microg/m3 in PM10 was 0.19 (95% CI = 0.00-0.41), whereas in a city with high average NO2 it was 0.80% (95% CI = 0.67-0.93%); in a relatively cold climate the corresponding effect was 0.29% (95% CI = 0.16-0.42), whereas in a warm climate it was 0.82% (95% CI = 0.69-0.96); in a city with low standardized mortality rate it was 0.80% (95% CI = 0.65-0.95%), and in one with a high rate it was 0.43% (95% CI = 0.24-0.62). Our results confirm those previously reported on the effects of ambient particles on mortality. Furthermore, they show that the heterogeneity found in the effect parameters among cities reflects real effect modification, which is explained by specific city characteristics.

Aged↗
PubMedDate not supplied

Social status does not affect resting metabolic rate in wintering dark-eyed junco (Junco hyemalis).

Studies of wintering birds have demonstrated a correlation between social rank and energy expenditures. It is assumed that dominance is energetically costly because of increased activity, possibly caused by elevated androgen levels. As winter acclimatization leads to an increase in metabolic rate, maintaining dominance status in a cold climate can be a substantial challenge. We measured resting metabolic rates in dominant and subordinate dark-eyed juncos (Junco hyemalis) living in small groups in a controlled winter environment. We found no significant effect of social rank when controlling for body size. It has been shown previously that high testosterone levels during the nonbreeding season can lead to higher body conductance, fat loss, and higher nocturnal body temperature. A hypothesis explaining our result is that for juncos it is preferable to maintain low androgen levels during winter and to maintain social rank using a mechanism other than higher agonistic activity.

Agonistic Behavior↗
PubMed2005

History and geography of suicide: could genetic risk factors account for the variation in suicide rates?

The current state of knowledge of genetic predisposition towards the suicidal behavior allows for a question whether genetic risk factors account for the variation in suicide rates through time and space. Accordingly, the presented paper will attempt to tackle the genetics behind suicidal behavior from the perspective of the populational genetics. First, the variability of suicide rates across Europe is discussed. This is followed by a brief discussion of the J curve (on a map of Europe, the countries with a higher suicide rate form a so-called J curve, which starts in Finland and extends down to Slovenia), which maps on to the second principal component identified for European gene distribution, representing the ancestral adaptation to cold climates and the Uralic language dispersion. Furthermore, we will discuss whether the group of people living within the J-curve could share genes, which may not tolerate excessive amounts alcohol, the combination of which is more likely to end in suicidal behavior. Further along we list possible ways in which suicidal behaviour could have been selected for genetically in populations and identify those specific populations in which it may have appeared. Finally, we point at other locations in the world where a similar interplay of genes and environment has probably occurred, Greenland being the best example of the malignant interaction of alcohol consumption and the trait-like characteristics, which might constitute the vulnerability to suicidal behaviour.

Adaptation, Physiological↗
PubMed2004

Summary of human responses to ventilation.

UNLABELLED: It is known that ventilation is necessary to remove indoor-generated pollutants from indoor air or dilute their concentration to acceptable levels. But as the limit values of all pollutants are not known the exact determination of required ventilation rates based on pollutant concentrations is seldom possible. The selection of ventilation rates has to be based also on epidemiological research, laboratory and field experiments and experience. The existing literature indicates that ventilation has a significant impact on several important human outcomes including: (1) communicable respiratory illnesses; (2) sick building syndrome symptoms; (3) task performance and productivity, and (4) perceived air quality (PAQ) among occupants or sensory panels (5) respiratory allergies and asthma. In many studies, prevalence of sick building syndrome symptoms has also been associated with characteristics of HVAC-systems. Often the prevalence of SBS symptoms is higher in air-conditioned buildings than in naturally ventilated buildings. The evidence suggests that better hygiene, commissioning, operation and maintenance of air handling systems may be particularly important for reducing the negative effects of HVAC systems. Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated. Ventilation may bring indoors harmful substances or deteriorate indoor environment. Ventilation interacts also with the building envelope and may deteriorate the structures of the building. Ventilation changes the pressure differences across the structures of building and may cause or prevent infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. The paper summarises the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus is on office-type working environment and residential buildings. PRACTICAL IMPLICATIONS: The review shows that ventilation has various positive impacts on health and productivity of building occupants. Ventilation reduces the prevalence of airborne infectious diseases and thus the number of sick leave days. In office environment a ventilation rate up to 20-25 L/s per person seem to decrease the prevalence of SBS-symptoms. Air conditioning systems may increase the prevalence of SBS-symptoms relative to natural ventilation if not clean. In residential buildings the air change rate in cold climates should not be below app. 0.5 ach. Ventilation systems may cause pressure differences over the building envelope and bring harmful pollutants indoors.

Air Conditioning↗
PubMed2006

Wind-chill-equivalent temperatures: regarding the impact due to the variability of the environmental convective heat transfer coefficient.

The wind-chill index (WCI), developed in Antarctica in the 1940s and recently updated by the weather services in the USA and Canada, expresses the enhancement of heat loss in cold climates from exposed body parts, e.g., face, due to wind. The index provides a simple and practical means for assessing the thermal effects of wind on humans outdoors. It is also used for indicating weather conditions that may pose adverse risks of freezing at subfreezing environmental temperatures. Values of the WCI depend on a number of parameters, i.e, temperatures, physical properties of the air, wind speed, etc., and on insolation and evaporation. This paper focuses on the effects of various empirical correlations used in the literature for calculating the convective heat transfer coefficients between humans and their environment. Insolation and evaporation are not included in the presentation. Large differences in calculated values among these correlations are demonstrated and quantified. Steady-state wind-chill-equivalent temperatures (WCETs) are estimated by a simple, one-dimensional heat-conducting hollow-cylindrical model using these empirical correlations. Partial comparison of these values with the published "new" WCETs is presented. The variability of the estimated WCETs, due to different correlations employed to calculate them, is clearly demonstrated. The results of this study clearly suggest the need for establishing a "gold standard" for estimating convective heat exchange between exposed body elements and the cold and windy environment. This should be done prior to the introduction and adoption of further modifications to WCETs and indices. Correlations to estimate the convective heat transfer coefficients between exposed body parts of humans in windy and cold environments influence the WCETs and need to be standardized.

Body Temperature Regulation↗