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At least 325 records · Page 18Linked to original sources
PubMed2004

Fungal spore transport through a building structure.

The study carried out laboratory measurements with a full-scale timber frame structure to determine penetration of inert particles with size distribution from 0.6 to 4 microm and spores of Penicillium and Cladosporium through the structure. Pressure difference over and air leakage through the structure were varied. Measurements at moderate pressure differences resulted in the penetration factors within the range of 0.05-0.2 for inert particles, and indicated also the penetration of fungal spores through the structure. The measurements showed that the penetration was highly dependent on pressure difference over the structure but not on holes in surface boards of the structure. The results show that surface contacts between the frames and mineral wool may have a significant effect on penetration. The penetration was approximately constant within particle size rage of 0.6-2.5 microm, but particles with diameter of 4.0 microm did not penetrate through the structure at all even at a higher-pressure difference of 20 Pa, except in the case of direct flow-path through the structure. Results have important consequences for practical design showing that penetration of fungal spores through the building envelope is difficult to prevent by sealing. The only effective way to prevent penetration seems to be balancing or pressurizing the building. In cold climates, moisture condensation risk should be taken into account if pressure is higher indoors than outdoors. Determined penetration factors were highly dependent on the pressure difference. Mechanical exhaust ventilation needs a special consideration as de-pressurizing the building may cause health risk if there is hazardous contamination in the building envelope exists.

Air Movements↗
PubMed2003

Panniculitis, due to Mycobacterium smegmatis, in two Finnish cats.

Pyogranulomatous panniculitis due to infection by Mycobacterium smegmatis was diagnosed in two cats in Finland, a country with a rather cold climate. The diagnosis was confirmed by sequencing of the 16S rRNA gene, which gave a perfect match with the M smegmatis strain ATCC 19420. Gene sequencing makes it possible to distinguish M smegmatis from closely related mycobacteria such as M goodii sp.nov. Diagnosing this entity seems to be a question of having a high index of suspicion. The appearance of the disease as well as sampling is described in detail. In our first case an initial erroneous diagnosis of Nocardia species considerably delayed our arriving at the right diagnosis. The first patient has now been followed for more than 7 years. Her disease is chronic, but she is not systemically affected. Several antimicrobials were tried. Probable side effects of enrofloxacin medication are described.

Animals↗
PubMed1999

Diabetes and enterovirus autoimmunity in glacial Europe.

The incidence of insulin-dependent diabetes mellitus (IDDM), a chronic disease with a well-known genetic basis, is highest in Scandinavian and Sardinian populations. The high incidence of IDDM in Scandinavia and Sardinia, which were genetically isolated from the spread of agriculturists in Europe about 8000 years ago, suggests that an IDDM-susceptible genotype(s) may have been beneficial in Europe more than 8000 years ago. In glacial times, Europe had an extremely cold climate that was frequently interrupted by episodes of warming. When enteroviruses were locked in the ice and permafrost, glacial Europeans would have had little immunity to these viruses. Each time the climate warmed, enteroviruses would have spread through increased amounts of melt water. With a genetic ability to mount an autoimmune defense, the IDDM genotype(s) would have been beneficial in glacial Europe as a defense against all enteroviruses, including those that had co-evolved to mimic host tissue.

Diabetes Mellitus, Type 1↗
PubMed2002

The fireside hypothesis: was there differential selection to tolerate air pollution during human evolution?

It is believed that sometime around 1.9 million years ago early hominid ancestors began to migrate out of Africa. Migration north and away from the equator would have forced early humans to encounter seasonal fluctuations in temperature. As a means of adapting to cold climates, the use of fire undoubtedly played an important role. We hypothesize that progressive exposure to toxic airborne particles produced from combustion created selective pressure to develop an adaptation to the inhalation of smoke. In this paper we test this hypothesis using archival data on the incidence of different cancers among geographically distinct human populations. As predicted from evolutionary theory, the incidence of lung cancer is inversely proportional to the ostensible reliance on fire of geographically different groups during human evolutionary history.

Adaptation, Physiological↗
PubMed1997

The metabolic syndrome: from inherited survival trait to a health care problem.

A critical role is proposed for the quantity and quality of dietary carbohydrate in the pathogenesis of the insulin resistance and hyperinsulinaemia which characterise the Metabolic Syndrome. We propose that an insulin-resistant genotype evolved to provide survival and reproductive advantages for the cold-climate, large game hunters of the last Ice Age who consumed a low carbohydrate, high protein diet with periodic starvation. Insulin resistance would have minimised glucose utilisation by muscles thereby facilitating the preferential utilisation of glucose by the brain, foetus and mammary gland. But beginning about 10,000 years ago following the end of the last Ice Age and the development of agriculture, dietary carbohydrate increased and the selection pressure for insulin resistance decreased in some groups. Agriculture began in the Middle East and spread throughout Europe long before it was developed elsewhere. Hence the prevalence of the insulin-resistant genotype decreased in Europeans and other groups exposed to a high carbohydrate intake for sufficiently long. Some geographically isolated groups such as the Pima Indians and Nauruans experienced conditions which further diminished the gene pool diversity and resulted in particularly insulin resistant populations. Traditional carbohydrate foods have a low glycaemic index and produce only modest increases in plasma insulin. However, the constant supply of highly refined high glycaemic index carbohydrate in modern diets, results in postprandial hyperinsulinaemia. The insulin-resistant genotype is now disadvantageous and predisposes to the development of the Metabolic Syndrome.

Blood Glucose↗
PubMed1998

[Paranasal sinuses: only one of nature's games?].

BACKGROUND: Many theories exist concerning the function of paranasal sinuses, but it is rather difficult to definitively name the right one. Despite the fact that many of them have been proved to be wrong, they are still used. THEORIES: Galen postulated 2000 years ago that they were "porous bones", which helped with weight reduction. Like Galen's theory, most of the others have been refuted as well. A list of these refuted theories covers a range of postulated functions including a relative warming or moistening of the breath, protection against high pressure in the nasal region when sneezing, paranasal sinuses as a place of efficient mucus production, or an aid for smelling, similar to the ethmoidal cells of the porcupine. Others include an isolated function for protection against cold climates and an aid for formulating sound by acting as a resonance chambers. CONCLUSIONS: Two theories still remain. One says that the paranasal sinuses are only the result of the evolutionary processes that have taken place in the skull during human development. The other theory explain that the form of the paranasal sinuses exists through the influence of the forces created during the act of chewing. Small cavities appear as a result of the minimal energy created, and these cavities can be found in the form of paranasal sinuses.

Adaptation, Physiological↗
PubMed2006

Consistent simulations of multiple proxy responses to an abrupt climate change event.

Isotope, aerosol, and methane records document an abrupt cooling event across the Northern Hemisphere at 8.2 kiloyears before present (kyr), while separate geologic lines of evidence document the catastrophic drainage of the glacial Lakes Agassiz and Ojibway into the Hudson Bay at approximately the same time. This melt water pulse may have been the catalyst for a decrease in North Atlantic Deep Water formation and subsequent cooling around the Northern Hemisphere. However, lack of direct evidence for ocean cooling has lead to speculation that this abrupt event was purely local to Greenland and called into question this proposed mechanism. We simulate the response to this melt water pulse using a coupled general circulation model that explicitly tracks water isotopes and with atmosphere-only experiments that calculate changes in atmospheric aerosol deposition (specifically (10)Be and dust) and wetland methane emissions. The simulations produce a short period of significantly diminished North Atlantic Deep Water and are able to quantitatively match paleoclimate observations, including the lack of isotopic signal in the North Atlantic. This direct comparison with multiple proxy records provides compelling evidence that changes in ocean circulation played a major role in this abrupt climate change event.

Atlantic Ocean↗
PubMed1995

Genetics and the origin of European languages.

A new set of European genetic data has been analyzed to dissect independent patterns of geographic variation. The most important cause of European genetic variation has been confirmed to correspond to the migration of Neolithic farmers from the area of origin of agriculture in the Middle East. The next most important component of genetic variation is apparently associated with a north-south gradient possibly due to adaptation to cold climates but also to the differentiation of the Uralic and the Indo-European language-speaking people; however, the relevant correlations are not significantly different from zero after elimination of the spatial autocorrelation. The third component is highly correlated with the infiltration of the Yamna ("Kurgan") people, nomadic pastoralists who domesticated the horse and who have been claimed to have spread Indo-European languages to Europe; this association, which is statistically significant even when taking spatial autocorrelations into account, does not completely exclude the hypothesis of Indo-European as the language of Neolithic farmers. It is possible that both expansions were responsible for the spread of different subfamilies of Indo-European languages, but our genetic data cannot resolve their relative importance.

Alleles↗
PubMed2002

An explanation for the seasonality of acute upper respiratory tract viral infections.

Despite a great increase in our understanding of the molecular biology of the viruses associated with acute upper respiratory tract viral infections (URTIs) there is a remarkable lack of knowledge and ideas about why URTI should exhibit a seasonal incidence. Most publications in this area either acknowledge a complete lack of any explanation for the seasonality of URTI or put forward an explanation relating to an increased "crowding" of susceptible persons in winter. This review will discuss some of the ideas concerning the seasonality of URTI and put forward a new hypothesis for discussion, namely that seasonal exposure to cold air causes an increase in the incidence of URTI due to cooling of the nasal airway. The hypothesis is supported by literature reports demonstrating that inhalation of cold air causes cooling of the nasal epithelium, and that this reduction in nasal temperature is sufficient to inhibit respiratory defences against infection such as mucociliary clearance and the phagocytic activity of leukocytes. A case is also made to suggest that warming of the nasal airway during fever and nasal congestion may help to resolve a current URTI.

Body Temperature↗
PubMed1981

Accidental hypothermia: a community hospital perspective.

Hypothermia, especially in an urban environment, is often an unsuspected and therefore underdiagnosed clinical entity. Of 60 cases recorded over a two-year period in a typical community hospital in Philadelphia, 26 (43%) involved patients under 60 years of age; ambient air temperatures at admission exceeded 50 F (10 C) in 28 (47%) of the 60 cases. Hypothermia thus cannot necessarily be attributed to advanced age or cold climates or seasons. The severity of hypothermia did not correlate with either the season of the year or the ambient air temperature. Diabetes and alcohol abuse appear to be risk factors for hypothermia, being present in 18 (30%) and 14 (23%) of our patients, respectively. Every emergency department should have a protocol for identification and management of the hypothermia victim to allow timely institution of appropriate rewarming techniques.

Accidents↗
PubMed1998

Thermoregulatory, metabolic and sympathoadrenal responses to repeated brief exposure to cold.

This study examined the metabolic, thermoregulatory and sympathoadrenal response pattern of eight male subjects to repeated bouts of brief cold stress. Water immersion (WI) was used to induce cold stress over a 60 min period on three separate occasions on three successive days. Rectal temperature (T(re)), mean skin temperature (T(sk)) and metabolic rate (VO2) were measured at 10 min intervals throughout WI and for 20 min post-immersion (PI). Blood was drawn and assayed for plasma adrenaline (ADR), noradrenaline (NDR) and cortisol at rest, at the end of immersion and PI. Acute cold stress was induced for each of the three exposures with a reduction in T(re) of approximately 0.63 degrees C (p<0.01) and approximately 1.2 degrees C (p<0.01) at the end of immersion and PI, respectively. T(sk) was reduced for all trials by approximately 6.0 degrees C (p<0.01) at the end of immersion and approximately 3.0 degrees C (p<0.01) at PI. VO2 peaked at 40-50 min of WI to 83%, 58% and 47% above rest for each consecutive trial. Plasma ADR did not show any change (p=0.34) as a consequence of cold stress between trials. Plasma NDR increased at the end of immersion (p<0.01) and remained elevated at PI (p<0.01). Plasma cortisol showed no change for any of the exposure periods. DeltaT(re) was more pronounced for the last exposure and was negatively correlated (r= -0.78, p<0.02) with plasma NDR. The results of this investigation complement previous findings of cold adaptation and suggest a possible adaptive response to repeated brief bouts of cold exposure evidenced by the changing trends in body temperature, metabolic rate and plasma NDR.

Acclimatization↗
PubMed2002

Prevalence of antibodies to Bartonella henselae, B. elizabethae and B. quintana in Swedish domestic cats.

Sera from 292 cats were analyzed by means of indirect immunofluorescence for antibodies to Bartonella henselae, B. quintana and B. elizabethae. The sera were sent to the Swedish National Institute of Veterinary Medicine for health monitoring and were tested retrospectively for antibodies to Bartonella. The most prevalent antibodies (25%) reacted with the B. elizabethae antigen. Cats with such antibodies were older than those without antibodies. The prevalence of antibodies to B. elizabethae was higher in the south of Sweden than in the north, with the highest prevalence (46%) being found in cats living in the Stockholm region. There was no difference in sex distribution. A low prevalence (1%) of antibodies to B. henselae was found and no sera reacted with B. quintana. The high prevalence of antibodies to B. elizabethae is consistent with previous findings in Swedish patients. The small number of cats with B. henselae antibodies observed in this study could be due to the cold climate and the low occurrence of cat fleas in Sweden.

Aging↗
PubMed1991

Heat--sweat--dehydration--rehydration: a praxis oriented approach.

In any situation where heat production as a result of physical exercise exceeds heat elimination from the body by radiation and convection, the body will depend on sweat secretion and evaporation for its thermoregulation. Sweat secretion will reach maximal levels at high energy expenditures in the heat but will be limited when exercising in the cold climate. Athletes and their coaches should understand some of the principles of thermoregulation in order to make an adequate decision about optimal fluid and carbohydrate replacement in a specific situation. In general it is advised that the carbohydrate content of rehydration drinks should be low (max 80 g l-1) when sweat loss is maximal, may be intermediate when both carbohydrate availability and moderate dehydration influence performance (up to 110 g l-1), and may be maximal (up to 160 g l-1) when the sweat loss is minimized and carbohydrate is the major determinant of the rate of fatigue development. Sodium should be added to rehydration drinks in order to maximize fluid and carbohydrate absorption. A range of electrolyte values for replacement of sweat induced losses, based on whole body wash down procedure is presented.

Body Temperature Regulation↗
PubMed2006

Performance of direct biofiltration of surface water for reduction of biodegradable organic matter and biofilm formation potential.

Direct biofiltration of surface water may be considered as pre-treatment for membrane filtration, in order to reduce fouling. The biofiltration process was investigated with regard to biodegradable organic matter and biofilm formation, covering the annual variations under moderately cold climate conditions. Granular activated carbon (GAC) and two types of crushed expanded clay (EC) were compared as filter media. To assess the biological properties of the biofilters, viable biomass and respiratory activity was examined. Biofiltration removed assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC) by about 30% and also reduced the bacterial concentration in the water phase. Also, biofilm formation in the treated water was reduced by 80-90% during summer and winter conditions. The reductions in the investigated parameters were similar in the biofilters with GAC and EC. Likewise, a similar amount and development of biomass was found in the GAC and EC biofilters of comparable grain size with a pronounced stratification from top to bottom of the filter bed. The specific respiratory activity of the biofilter biomass was dependent on raw water temperature. Even though slight correlations between BDOC removal and temperature or respiratory activity were observed, AOC and BDOC removals were mainly dependent on the feed water concentrations of these compounds. The results indicate that direct biofiltration of surface water, by reducing AOC, BDOC and biofilm formation in the water, may be an advantageous pre-treatment for membrane filtration processes.

Biodegradation, Environmental↗
PubMed2005

Salinity effect on the characteristics of saturated horizontal flow in small boxes containing Filtralite-P.

Constructed wetlands are ecological systems that have proven their efficiency in treating wastewater and reducing pollutants of concern in both warm and cold climate. Oversizing these systems is common in the design process due to the inadequate knowledge about water movement in the porous media used. This study investigates the saturated horizontal flow pattern in a lightweight aggregates especially made for use in constructed wetlands termed Filtralite P using computer tomography and a chloride tracer under different hydraulic loading rates and inlet concentrations in a laboratory box experiment. The salt concentrations showed a major effect on the retention time and the flow by enhancing short-circuiting, preferential flow pattern. A hydraulic loading rate of 25 cm day(-1) is suggested as the safest loading rate with Filtralite P under different ranges of wastewater concentrations with a possibility to use a loading rate of 50 cm day(-1) only with municipal wastewater and not the industrial wastewater. The computer tomography images indicated that flow was going first to the bottom and then fluidise upward with a sharp boundary between the incoming and ambient water.

Ecosystem↗
PubMed2005

The effects of aeration and the application of the k-C* model in a subsurface flow constructed wetland.

Since the horizontal subsurface flow constructed wetland in Kodijärve, Estonia had problems with aeration, a vertical subsurface flow (VSSF) constructed wetland (CW) was built for the purpose of enhancing aeration. This article gives an overview of how the vertical subsurface flow constructed wetland has affected the aeration capacity and purification efficiency of the constructed wetland system in a one-year period of operation. The aeration capacity of the VSSF CW averaged 63.6 g O2 m(-2) d(-1) during this one-year operational period, and aerobic processes occur more effectively in the system. An area of 0.5 m2 pe(-1) is most likely too small for sufficient aeration in cold climates, and the short water residence time in the VSSF CW also can hinder nitrification. Also, an analysis of the application of the k-C* model in the horizontal subsurface flow part of the Kodijärve hybrid constructed wetland is presented for BOD, total nitrogen, ammonium and total phosphorus. The k-C* model describes processes in the HSSF CW quite well. The k values are found to be smaller than reported in the literature, mainly because of the low hydraulic loading rates. Low k values in more oxygen dependent processes, such as BOD, N(tot), and NH4-N removal, also indicate insufficient oxygen supply in the system.

Air↗
PubMedDate not supplied

Conflicts between courtship and thermoregulation: the thermal ecology of amorous male garter snakes (Thamnophis sirtalis parietalis, colubridae).

Thermoregulatory behavior is an important component of daily activities for many reptiles, especially for small heliothermic (sun-basking) species that inhabit cold climates. However, the relative costs and benefits of thermoregulation depend on numerous factors, such that reptiles may sometimes accord a low priority to precise control of body temperatures. We observed and radio tracked garter snakes (Thamnophis sirtalis parietalis) in central Manitoba during the mating season (spring). Previous studies on this species have documented precise behavioral regulation of body temperatures during summer. In contrast, the courting snakes that we studied in springtime spent little time in overt thermoregulatory behavior. Body temperatures were extremely variable (both in outdoor enclosures and in the field) despite abundant opportunities for more precise thermal control. These small elongate reptiles cool so quickly (relative to the time periods needed for effective courtship) that any benefit to higher body temperatures would be transitory at best. Experiments show that hotter males are no better at obtaining matings or at detecting predators. Thus, male garter snakes concentrate on courtship rather than on basking. In the face of conflicting priorities, reptiles may often forgo precise thermoregulation because its benefits are too low, and its costs too high, compared with alternative behaviors.

Animals↗