Changes In Thermal Conditions Research Articles

MRI characterization of brown adipose tissue under thermal challenges in normal weight, overweight, and obese young men.

To implement quantitative Dixon magnetic resonance imaging (MRI) methods for brown adipose tissue (BAT) characterization at inactive and cold-activated states in normal weight, overweight, and obese subjects. The hypotheses are that MRI characteristics of BAT would differentiate between nonobese and obese subjects, and activation of BAT in response to thermal challenges that are detected by MRI would be correlated with BAT activity measured by positron emission tomography / computed tomography (PET/CT). Fifteen male subjects (20.7 ± 1.5 years old) including six normal weight, five overweight, and four obese subjects participated in the study. A multiecho Dixon MRI sequence was performed on a 1.5T scanner. MRI was acquired under thermoneutral, nonshivering thermogenesis, and subsequent warm-up conditions. Fat fraction (FF), R2*, and the number of double bonds (ndb) were measured by solving an optimization problem that fits in- and out-of-phase MR signal intensities to the fat-water interference models. Imaging acquisition and postprocessing were performed by two MRI physicists. In each subject, Dixon MRI measurements of FF, R2*, and ndb were calculated for each voxel within all BAT regions of interest (ROIs) under each thermal condition. Mean FF, R2*, and ndb were compared between nonobese (ie, normal-weight/overweight) and obese subjects using the two-sample t-test. Receiver operating characteristic (ROC) analyses were performed to differentiate nonobese vs. obese subjects. BAT MRI measurement changes in response to thermal condition changes were compared with hypermetabolic BAT volume/activity measured by PET/CT using the Pearson's correlation. In addition, BAT MRI measurements were compared with body adiposity using the Pearson's correlation. P < 0.05 was considered statistically significant. Obese subjects showed higher FF and lower R2* than nonobese subjects under all three thermal conditions (P < 0.01). ROC analyses demonstrated that FF and R2* were excellent predictors for the differentiation of nonobese from obese subjects (100% specificity and 100% sensitivity). FF changes under thermal challenges were correlated with hypermetabolic BAT volume (r = -0.55, P = 0.04 during activation, and r = 0.72, P = 0.003 during deactivation), and with BAT activity (r = 0.69, P = 0.006 during deactivation), as measured by PET/CT. FF and R2* under all three thermal conditions were highly correlated with body adiposity (P ≤ 0.002). MRI characteristics of BAT differentiated between nonobese and obese subjects in both inactivated and activated states. BAT activation detected by Dixon MRI in response to thermal challenges were correlated with glucose uptake of metabolically active BAT. 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:936-947.

The development of permafrost bacterial communities under submarine conditions

Submarine permafrost is more vulnerable to thawing than permafrost on land. Besides increased heat transfer from the ocean water, the penetration of salt lowers the freezing temperature and accelerates permafrost degradation. Microbial communities in thawing permafrost are expected to be stimulated by warming but how they develop under submarine conditions is completely unknown. We used the unique records of two submarine permafrost cores from the Laptev Sea on the East Siberian Arctic Shelf, inundated about 540 and 2500 years ago, to trace how bacterial communities develop depending on duration of the marine influence and pore water chemistry. Combined with geochemical analysis, we quantified total cell numbers and bacterial gene copies, and determined the community structure of bacteria using deep sequencing of the bacterial 16S rRNA gene. We show that submarine permafrost is an extreme habitat for microbial life deep below the seafloor with changing thermal and chemical conditions. Pore water chemistry revealed different pore water units reflecting the degree of marine influence and stages of permafrost thaw. Millennia after inundation by sea water, bacteria stratify into communities in permafrost, marine-affected permafrost, and seabed sediments. In contrast to pore water chemistry, the development of bacterial community structure, diversity and abundance in submarine permafrost appears site-specific, showing that both sedimentation and permafrost thaw histories strongly affect bacteria. Finally, highest microbial abundance was observed in the ice-bonded seawater unaffected but warmed permafrost of the longer inundated core, suggesting that permafrost bacterial communities exposed to submarine conditions start to proliferate millennia after warming.

Distinct responses of sympatric migrant and resident Atlantic cod phenotypes to substrate and temperature at a remote Gulf of Maine seamount

AbstractLife-history strategies often vary within motile marine species, affecting morphometry, growth, diet, and fecundity. Atlantic cod (Gadus morhua) in the Gulf of Maine display marked variation in a number of life-history traits, exemplified by differences in body colour. Migratory behaviours are suspected to differ among these colour types, but have yet to be shown definitively. Here, we used the combination of an acoustic telemetry system and fine-scale benthic habitat maps to reveal that the red phenotype cod adhered to an isolated kelp forest covering &amp;lt;2 km2 of a seamount in the central Gulf of Maine. Meanwhile, the olive phenotype cod adopted diel vertical migratory behaviour, possibly in response to a temperature gradient. Use of shallow, structured habitat was influenced by temperature and may be enabled by dynamic conditions related to internal waves that persist throughout the summer and early fall. Detections decreased in response to changing thermal conditions, although phenotypes reacted to these changes in distinct ways: the olive phenotype abandoned shallow habitat prior to peak summer temperatures, while the red phenotype remained until mid-fall when temperatures and temperature variability declined. Our findings support a link between morphometry, colour, behavioural strategies, and habitat preferences that may be widespread in Atlantic cod.

Annual Changes in Seasonal River Water Temperatures in the Eastern and Western United States

Changes in river water temperatures are anticipated to have direct effects on thermal habitat and fish population vital rates, and therefore, understanding temporal trends in water temperatures may be necessary for predicting changes in thermal habitat and how species might respond to such changes. However, many investigations into trends in water temperatures use regression methods that assume long-term monotonic changes in temperature, when in fact changes are likely to be nonmonotonic. Therefore, our objective was to highlight the need and provide an example of an analytical method to better quantify the short-term, nonmonotonic temporal changes in thermal habitat that are likely necessary to determine the effects of changing thermal conditions on fish populations and communities. To achieve this objective, this study uses Bayesian dynamic linear models (DLMs) to examine seasonal trends in river water temperatures from sites located in the eastern and western United States, regions that have dramatically different riverine habitats and fish communities. We estimated the annual rate of change in water temperature and found little evidence of seasonal changes in water temperatures in the eastern U.S. We found more evidence of warming for river sites located in the western U.S., particularly during the fall and winter seasons. Use of DLMs provided a more detailed view of temporal dynamics in river thermal habitat compared to more traditional methods by quantifying year-to-year changes and associated uncertainty, providing managers with the information needed to adapt decision making to short-term changes in habitat conditions that may be necessary for conserving aquatic resources in the face of a changing climate.

What Does a Magma Reservoir Look Like? The “Crystal's-Eye” View

Crystals within volcanic rocks contain records of the changing chemical and thermal conditions within the magma reservoirs in which they resided before eruption. Observations from these crystal records place fundamental constraints on the processes operating within the reservoirs. Data from volcanic crystals are in accord with recent conceptual models of magma reservoirs being composed dominantly of crystal mushes, with small volumes and/or small fractions of melt present. The implication is that magma reservoirs have differing modes of behavior: magmas are stored over the long term in largely crystalline, quiescent, conditions, punctuated by brief episodes of intense activity during the decades to centuries immediately prior to an eruption.

Thermal Control, Weather, and Aging.

The purpose of this review is to highlight the latest developments in the field of weather and health with a focus on the elderly. The current state of knowledge is summarized and open questions and emerging fields of research are discussed. It is expected that climate change will lead to higher global average surface temperatures and more extreme climatic conditions. Previous studies have shown that non-optimal temperatures are associated with increased morbidity and mortality, specifically in elderly people. Future research fields comprise e.g., synergistic effects between meteorological variables and air pollution; long-term impacts of temperature changes; novel unraveling the underlying pathways using blood biomarkers; the association between temperature and mental health; and urban planning and adaptation processes. Understanding the health impacts associated with changes in thermal conditions requires multidisciplinary approaches. Adaptation processes, as well as improvements in urban planning and warning systems, can help reduce the predicted burden of climate change, especially in the elderly.

Environmental stress in the northern Tethys during the Paleogene: a review of foraminiferal and geochemical records from the Polish Outer Carpathians

During the Paleogene, the area of the northern Tethys was controlled by a turbidity system stimulated by diastrophic and geodynamic processes. These factors contributed to the dispersion and rapid oxygenation of organic debris. Its accumulation was a consequence of stagnant bottom water conditions that periodically occurred in the basin. In these periods, intense decomposition intensified by hydrothermal and diagenetic processes was associated with oxygen consumption and the release of greenhouse gases, which led to hypoxia and acidification. These phenomena intensified by thermal and density stratification had a major impact on the structure, evolution and distribution of biota. Stress associated with rapidly changing conditions induced by sedimentary process and upwelling resulted in the dominance of forms that colonized most sediments ( Glomospira, Ammodiscus, Recurvoides, Rzehakina) and surface waters ( Guembelitria, Chiloguembelina, Globanomalina, Globigerina, Cassigerinella, Catapsydrax ). At the time, foraminifera were limited to low-diversified eutrophic assemblages or were mainly replaced by siliceous phytoplankton (radiolarians and diatoms). Geochemical data confirm that environmental crises in the Paleogene basin took place under changing thermal conditions that reflect global events (KTBE, PTME, EEOC and TTE). Thermal stress favouring the formation of certain minerals or rocks occasionally occurred during the Paleocene to Eocene (siderite, phosphates) and dominated in the Early Oligocene (silica).

学校建築におけるコミュニティスペースの環境条件と利用実態に関する研究

Not only spaces of study, such as, a classroom and a library, but also those for informal communication in lunch time and after school, such as, courtyard and entrance hall, are one of the most important factors for campus planning. To say about communication spaces, the environment and its influence on the state of mind and the behavior of the students must be different between the indoor communication space where the thermal condition is controlled by artificial devices, and that of outdoor where the thermal condition changes naturally. But, few studies are found from the viewpoint of thermal condition and usage of those spaces. The purpose of this study is to figure out the thermal and architectural influences of the indoor and outdoor community spaces of the junior and senior high school buildings on the state of mind and the behavior of the students through the year. The research of the thermal environment, the observational survey and the questionnaire survey have been done in June, September, October, November, and February, in the junior and senior high school. The results are shown as follows. 1. Both the result of the observational survey and the questionnaire survey shows that students stay hall and courtyard having a lunch and chattering in lunch time, then, after school, they were mainly studying in the hall, chattering and having rendezvous with friends in the courtyard. The staying time is longer in the hall than in the courtyard. So, it found that students chose which to stay depend on the staying time and purpose. 2. The research of the thermal environment and observational survey show that there was no correlation between the number of students in the hall or courtyard and the temperature, and also that students kept staying in the courtyard in high temperature as 28 degree centigrade in September. 3. There was a weak positive correlation between the temperature and the rate to choose staying in the courtyard. In September, in spite of the heat, the rate increased. In February, because of the cold, the rate decreased. 4. PMV of the hall and courtyard was almost within +1.0 to -1.0 through the year. In June and September, in the courtyard, PMV increased more than +1.0, but the number of the students staying there didn't decrease. 5. The thermal sense in February shows that the ratio of the sum of the cold and slightly cold in the hall was more than that in the courtyard. It can be inferred that the students' basic metabolic rate is higher than those of the grown-up, and also, that students have chosen to stay outside by themselves, knowing it's cold there. 6. In the courtyard, there was no correlation between the evaluation of thermal comfort and PPD. One of the reasons is assumed that there are a lot of stimulus in outdoor except for thermal stimuli, one more reason is also assumed that thermal condition such as heat and cold outdoor is tend to be widely accepted compared with indoor. 7. The students' evaluation shows that furniture and vending machines promote to stay in the courtyard. 8. The students' evaluation shows that they feel natural factors, such as, “wind” , ”shade of tree”, “sunshine”, and “sky”, more in the courtyard than in the hall. 9. The students' evaluation shows that there were about 30% replies of the long distance from the classroom to there, for the reason why students don't stay in the hall or the courtyard. But, another evaluation shows there is not obvious relation between the distance and the number of staying students. On the other hand, the reason to stay in the hall or courtyard has a difference by grade. Those results are expected to be the basic data necessary for planning informal communication spaces in schools, specially in the outdoor.

An examination of UV radiation tolerance and photoenzymatic repair capabilities across temperature in the freshwater cladocerans Scapholeberis mucronata, Diaphanosoma birgei, and Moina spp

ABSTRACTUltraviolet (UV) radiation has multiple consequences to freshwater organisms. Some zooplanktons use photoenzymatic repair (PER), which is a process that utilizes ultraviolet-A and visible light (photorepair radiation, PRR) to repair ultraviolet-B-induced DNA damage. Some zooplanktons also repair damage via nucleotide excision repair (NER), which is a radiation-independent enzymatic process. Our objective was to determine the effects of UV radiation, including the use of PER and NER on the cladocerans Diaphanosoma birgei, Scapholeberis mucronata, and Moina spp. Based on studies with Daphnia, we hypothesized that the use of PER and NER varies with temperature and across species. The three taxa were exposed to UV-B radiation followed by photorepair radiation (+PRR) or no photorepair radiation (−PRR). The occurrences of PER and NER were determined indirectly by monitoring the survival and reproduction after exposure. Experiments were performed at 10, 15, 20, 25, and 30 °C. S. mucronata and Moina spp. use PER effectively at all temperatures, whereas D. birgei uses PER less effectively and only at warmer temperatures. S. mucronata and Moina spp. use NER more effectively at colder temperatures, while D. birgei uses little to no NER. These findings have implications on how these organisms may adapt to changing UV and thermal conditions.

Short-term changes in thermal conditions and active layer thickness in the tundra of the Kaffiøyra region, NW Spitsbergen

This article describes and discusses the results of observations concerning short-term changes in the thermal conditions and the thickness of the active layer in a test field located in the tundra of the Kaffioyra (NW Spitsbergen) during the summer season of 2015. One of the objectives was to find a correlation between the dynamic of the changes and the local topography. In recent years, thawing of the active layer in the Kaffioyra region has been considerably varied in individual summer seasons. The test field area was 100 square meters, comprised 36 measurement points and was situated at approximately 3 m a.s.l. in the tundra. The measurements of the thickness and temperature of the active layer were carried out in July, August and early September of 2015. The greatest thickness of the active layer in the tundra was found near the moraine, in the area with the sharpest slope (156 cm to 212 cm). Ground temperatures were observed to follow the prevailing weather conditions with a delay, which amounted to about 24 h at a depth of 25 cm, and as much as 48 h at a depth of 75 cm. A greater thickness of the active layer was found in the western part of the test field, in the vicinity of a tidal channel, and in the eastern part of the field, bordering on the foot of the Aavatsmarkbreen’s moraine. A considerable sloping of the land, combined with increased surface runoff and infiltration at the time of precipitation, makes the water penetrating into the active layer increase its temperature. This demonstrates that the local land forms (tidal channels and terminal moraines) have a substantial influence on the extent and rate of changes which occur in the active layer.

Short-term changes in thermal conditions and active layer thickness in the tundra of the Kaffiøyra region, NW Spitsbergen

Abstract This article describes and discusses the results of observations concerning short-term changes in the thermal conditions and the thickness of the active layer in a test field located in the tundra of the Kaffiøyra (NW Spitsbergen) during the summer season of 2015. One of the objectives was to find a correlation between the dynamic of the changes and the local topography. In recent years, thawing of the active layer in the Kaffiøyra region has been considerably varied in individual summer seasons. The test field area was 100 square meters, comprised 36 measurement points and was situated at approximately 3 m a.s.l. in the tundra. The measurements of the thickness and temperature of the active layer were carried out in July, August and early September of 2015. The greatest thickness of the active layer in the tundra was found near the moraine, in the area with the sharpest slope (156 cm to 212 cm). Ground temperatures were observed to follow the prevailing weather conditions with a delay, which amounted to about 24 h at a depth of 25 cm, and as much as 48 h at a depth of 75 cm. A greater thickness of the active layer was found in the western part of the test field, in the vicinity of a tidal channel, and in the eastern part of the field, bordering on the foot of the Aavatsmarkbreen’s moraine. A considerable sloping of the land, combined with increased surface runoff and infiltration at the time of precipitation, makes the water penetrating into the active layer increase its temperature. This demonstrates that the local land forms (tidal channels and terminal moraines) have a substantial influence on the extent and rate of changes which occur in the active layer.

Topographic Influence on the Motion of Tropical Cyclones Landfalling on the Coast of China

Abstract A few recent numerical studies investigated the influence of a continent, which is much larger in size than islands, on the track of a landfalling tropical cyclone. It has been found that land surface roughness and temperature tend to make a tropical cyclone move toward the continent. In this study, the effect of the elevated terrain on the western part of mainland China on landfall tracks is examined through idealized numerical experiments, in which an initially axisymmetric vortex is embedded into a monsoon trough and takes a landfall track across China’s mainland. It is found that the effect of the elevated terrain on the western part of mainland China can enhance the southerly environmental flows in the low and midtroposphere, leading to an additional landward component of tropical cyclone motion, suggesting that forecasts for tropical cyclone tracks over land should take into consideration the change in thermal condition over the continent. The study suggests that the increased duration of tropical cyclone overland tracks observed in China may be associated with the reduction of the thermal forcing over the Tibetan Plateau.

Pervasive forwarding mechanism for mobile social networks

In recent years, we have witnessed an increase in the popularity of mobile wireless devices and networks, with greater attention devoted to feasibility of opportunistic computing, sensing, and communication. In Mobile Social Networks (MSNs), communication is provided by spatial proximity and social links between peers, where personal devices carried by users communicate directly in a device-to-device mode. On one hand, human mobility provides encounters between peers and opportunities for communication without additional infrastructure; on the other hand, it introduces intermittent connections, network partitions, and long delay, requiring sophisticated message-forwarding mechanisms to improve network performance. Therefore, socially-inspired approaches which consider network structure and personal user features have been proposed to cope with these challenges. However, many studies disregard adaptive policies of message forwarding capable of dealing with variations of these features. In this paper, we investigated message dissemination in MSNs considering external factors such as temperature and seasonal calendar as environmental features capable of model users’preferences and encounters. We evaluated the time of day, the day of the week, and environmental variables such as weather and geographic position as important factors to the collective behavior and spatiotemporal characteristics of urban scenarios. This paper presents an analysis of real data from weather and human mobility, which depict distinct social interactions and spatial features characterized by changes in thermal conditions. Thus, we propose a socially-aware forwarding mechanism that is adaptable to the seasonality of personal preferences. Our experiments indicated that pervasive data can provide useful information towards the design of the next generation of human-centered Opportunistic Networks.

Electrical conductivity and porosity in stainless steel 316L scaffolds for electrochemical devices fabricated using selective laser sintering

Battery electrode microstructures must be porous, to provide a large active surface area to facilitate fast charge transfer kinetics. In this work, we describe how a novel porous electrode scaffold, made from stainless steel 316L powder can be fabricated using selective laser sintering by proper selection of process parameters. Porosity, electrical conductivity and optical microscopy measurements were used to investigate the properties of fabricated samples. Our results show that a laser energy density between 1.50–2.00J/mm2 leads to a partial laser sintering mechanism where the powder particles are partially fused together, resulting in the fabrication of electrode scaffolds with 10% or higher porosity. The sample fabricated using 2.00J/mm2 energy density (60W–1200mm/s) exhibited a good electrical conductivity of 1.80×106S/m with 15.61% of porosity. Moreover, we have observed the porosity changes across height for the sample fabricated at 60W and 600mm/s, 5.70% from base and increasing to 7.12% and 9.89% for each 2.5mm height towards the top surface offering graded properties ideal for electrochemical devices, due to the changing thermal boundary conditions. These highly porous electrode scaffolds can be used as an electrode in electrochemical devices, potentially improving energy density and life cycle.

Variability of growing degree days in Poland in response to ongoing climate changes in Europe

An observed increase in air temperature can lead to significant changes in the phenology of plants and, consequently, changes in agricultural production. The aim of the study was to evaluate the spatial differentiation of thermal resources in Poland and their variability during a period of changing thermal conditions in Europe. Since the variability of thermal conditions is of paramount importance for perennial crops, the study focused on apple, plum, and cherry orchard regions in Poland. The analysis was conducted for the period of 1951–2010 using air temperature daily data. Thermal resources have been defined using the growing degree days (GDD) index calculated independently for the whole year and during in frost-free season for three air temperature thresholds: 0, 5, and 10 °C, which determine the non-winter period, growing season, and the period of full plant growth, respectively. In addition, due to the high significance for perennials in particular, the incidence and intensity of frost during flowering were calculated. In this study, a detailed analysis of the spatial differentiation of thermal resources was first performed, followed by an evaluation of long-term variability and associated change patterns. The obtained results confirmed an increase in thermal resources in Poland as a consequence of the lengthening of the growing season. However, the frequency and intensity of spring frost, especially during flowering or even during ripening of plants, remain a threat to harvests in both the eastern and western parts of the country.

Combined Effects of Temperature and Seston Concentration on the Physiological Energetics of the Manila Clam Ruditapes philippinarum.

The suspension-feeding Manila clam Ruditapes philippinarum is a native species of the western Pacific that is now widely distributed around the globe because of its commercial importance. To determine the adaptive physiological responses to changing thermal and nutritional conditions, clearance, filtration, feces production, ammonium excretion, respiration rates, and scope for growth (SFG) were measured in adult clams. The clams were exposed to 24 treatments involving the combination of four water temperatures (8, 13, 18, and 23°C) and six concentrations of suspended particulate matter (SPM: 9.5 to 350.5 mg L–1). Physiological rates were standardized by using the mean (480 mg) of tissue dry weights of experimental clams using allometric equations between physiological variables and tissue dry weight. Higher clearance rates were recorded at higher temperatures and lower SPM concentrations, and these rates decreased with increasing SPM concentration at individual temperatures. Consumed energy increased with increasing temperature and SPM concentration, peaking at around 100–200 mg L–1 at 18–23°C. Whereas fecal energy was largely determined by SPM concentration, ammonia excretion was mainly governed by temperature. Respiration rate studies revealed a predominant quadratic effect of temperature on the metabolism, indicating a lack of acclimatory adjustment of metabolic rate to rising temperature. SFG values were positive under almost all the treatment conditions and were much higher at higher SPM concentrations (> 45 mg L–1), with the highest level being recorded at 18°C and 100–200 mg L–1 SPM. Increased filtration rate offset the increased metabolic cost at warm temperatures. Our holistic findings suggest that a high degree of physiological plasticity allows R. philippinarum to tolerate the wide range of temperatures and SPM concentrations that are found in tidal flats, accounting in part for the successful distribution of this species over a wide variety of geographical areas.

Forest health in a changing world: effects of globalization and climate change on forest insect and pathogen impacts

Forests and trees throughout the world are increasingly affected by factors related to global change. Expanding international trade has facilitated invasions of numerous insects and pathogens into new regions. Many of these invasions have caused substantial forest damage, economic impacts and losses of ecosystem goods and services provided by trees. Climate change is already affecting the geographic distribution of host trees and their associated insects and pathogens, with anticipated increases in pest impacts by both native and invasive pests. Although climate change will benefit many forest insects, changes in thermal conditions may disrupt evolved life history traits and cause phenological mismatches. Individually, the threats posed to forest ecosystems by invasive pests and climate change are serious. Although interactions between these two drivers and their outcomes are poorly understood and hence difficult to predict, it is clear that the cumulative impacts on forest ecosystems will be exacerbated. Herewe introduce and synthesize the information in this special issue of Forestry with articles that illustrate the impacts of invasions of insects and pathogens, climate change, forest management and their interactions, as well as methods to predict, assess and mitigate these impacts. Most of these contributions were presented at the XXIV IUFROWorld Congress in 2014.

Shutter-less calibration of uncooled infrared cameras

Abstract. Infrared (IR) cameras based on microbolometer focal plane arrays (FPAs) are the most widely used cameras in thermography. New fields of applications like handheld devices and small distributed sensors benefit from the latest sensor improvements in terms of cost and size reduction. In order to compensate for disturbing influences derived from changing ambient conditions, radiometric cameras use an optical shutter for online recalibration purposes, partially also together with sensor temperature stabilization. For these new applications, IR cameras should consist only of infrared optics, a sensor array, and digital signal processing (DSP). For acceptable measurement uncertainty values without using an optical shutter (shutter-less), the disturbing influences of changing thermal conditions have to be treated based on temperature measurements of the camera interior. We propose a compensation approach based on calibration measurements under controlled ambient conditions. All correction parameters are determined during the calibration process. Without sensor temperature stabilization (TEC-less), the pixel responsivity is also affected by the camera temperature changes and has to be considered separately. This paper presents the details of the compensation procedure and discusses relevant aspects to gain low temperature measurement uncertainty. The residual measurement uncertainty values are compared to the shutter-based compensation approach.

Differential larval responses of two ecologically similar insects (Odonata) to temperature and resource variation.

How species respond to shifting environmental conditions is a central question in ecology, especially because ecosystems are experiencing rapidly changing climatic conditions. However, predicting the responses of species interactions and community composition to changing conditions is often difficult. We examined the effects of rearing temperature and resource level on larval survival of two ecologically similar dragonflies, Erythemis collocata and Pachydiplax longipennis. Within high and low (26 and 21°C) temperatures, we crossed species and resource level and reared larvae individually. We predicted that warmer temperatures would reduce survival and increase growth rate, that higher resource availability would increase survival and growth rate, and that the two species would respond similarly. We found that increased temperature reduced survival for both species. There was also an interaction between temperature and species: E. collocata had higher survival at the lower temperature, but lower survival at the higher temperature when compared to P. longipennis. Resource level did not affect survival. In general, P. longipennis grew more than E. collocata, with no effects of temperature or resource level. These results suggest that these species respond dissimilarly to changing thermal conditions, that increased food availability cannot always compensate for the negative effects of higher temperatures, and that climate change may affect interactions between these two sympatric, ecologically similar species, with potential consequences for community composition.

Spatial and temporal variability of depth and density of the snow cover in Russia

Measurements of snow cover depth and density made in 2001–2010 in the snow survey routes made it possible to study spatial and temporal variability of these characteristics on the territory of Russia. Maps of distribution of the snow cover depth and density in November, January and March for this period were constructed. Comparison of these maps with similar ones for the period from 1966 to 2000 did show that in November of the last years, significant (up to 40%) reduction in snow cover depth took place on the north-east of the European part in the river Pechora basin, in central regions of the West Siberia, and in north-east Siberia. As compared to the data of 1966–2000 the maximal snow depth for the period of 2001–2010 increased by 40% on the north of the Tyumen oblast, and in some regions on the south of West Siberia as well as of the European territory. In these areas, thickness of the seasonally melted layer of soil may increase for two reasons, i.e. due to the climate warming or as a result of worse conditions for the soil freezing when snow cover depth increases. In other regions, namely, the Northern Yakutia and areas on the east of the Lena River, as well as in central regions of the West Siberia maximal snow cover depth decreased by almost 15%. Growth of maximal density of the snow cover in the years of 2001–2010 relative to that in 1966–2000 does not exceed 6%. But in the Lena river basin decrease of the snow cover maximal density was noted more significant, namely by 20%. Inhomogeneous spatial variations of the snow cover during the period 2001–2010 relative to those of 1966–2000 could result in different spatial changes in thermal conditions for the existence of permafrost and seasonally frozen ground in Russia.