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Cooler
Terms modified by Cooler Selected AbstractsCooler for obtaining crystals in a crucible furnaceJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-2 2003B. Cabric An air cooler (`cold key') is presented with a movable branchy Tamman test tube (`test comb') installed in a laboratory crucible furnace for regulation and simultaneous crystallization tests at different temperature gradients and crystallization rate intervals, with the purpose of obtaining crystals. This method can also be applied in tube or chamber furnaces. [source] Residual Limbs of Amputees Are Significantly Cooler than Contralateral Intact LimbsPAIN PRACTICE, Issue 5 2008R. Norman Harden MD ,,Abstract: Objective: To test the hypothesis that distal residual limbs (DRLs) have significant vasomotor abnormalities. Design: Comparative surface temperature studies of DRLs using paired samples (DRL vs. similar site on intact contralateral limb). Subjects/Patients: Thirty-six volunteer subjects with unilateral, upper or lower limb amputations were recruited and evaluated at a pain research center in an urban academic rehabilitation facility. Methods: Our main outcomes were subjects' residual limb temperature as measured by quantitative infrared telethermography (qIRT), temperature strips, and examiner's palpation, compared with the contralateral limb. Results: The qIRT showed that the DRLs were significantly cooler than the corresponding area of the contralateral intact limbs (P < 0.01). The difference using temperature strips supported this finding (P < 0.05); while on physical examination, 39% of the residual limbs were perceived by the examiner as cooler than the corresponding unaffected limbs. Conclusions: DRLs as measured by qIRT were significantly cooler than the corresponding area of the contralateral intact limbs. A better understanding of these findings may be important in elucidating the pathophysiology of relevant clinical features such as a potential sympathetic component of postamputation pain.,, [source] A Calix[4]arene 3d/4f Magnetic Cooler,ANGEWANDTE CHEMIE, Issue 52 2009Georgios Karotsis Gut gekühlt: Der erste auf Calix[4]arenen basierende 3d/4f-Cluster (siehe Bild; violett,Mn, braun,Gd, rot,O, blau,N) hat eine hohe magnetische Isotropie und viele molekulare Spinzustände, die selbst bei niedriger Temperatur besetzt sind, während sein ferromagnetisches Limit erst bei hohem angelegtem Feld erreicht wird. Diese Eigenschaften machen ihn zu einem ausgezeichneten magnetischen Kühlmittel für Niedertemperaturanwendungen. [source] Effects of nest temperature and moisture on phenotypic traits of hatchling snakes (Tropidonophis mairii, Colubridae) from tropical AustraliaBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2006GREGORY P. BROWN Previous research on developmentally plastic responses by reptile embryos has paid relatively little attention to tropical species, or to possible interactions between the effects of thermal and hydric regimes. In the present study, eggs of keelback snakes (Tropidonophis mairii), from a tropical area with strong temporal and spatial variation in soil temperatures and moisture levels, were incubated. The phenotypic traits of hatchling snakes (body size, shape, muscular strength) were affected by moisture content of the incubation medium (vermiculite plus 100% vs. 50% water by mass), by mean incubation temperatures (25.7 vs. 27.9 °C) and by diel thermal variation (diel range 6.0 vs. 8.4 °C). Interactions between these factors were negligible. Cooler, more thermostable, moister conditions resulted in larger offspring, a trait under strong selection in this population. Thermal and hydric conditions covary in potential nest-sites (e.g. deeper nests are more thermostable as well as moister). This covariation may influence the evolution of reaction norms for embryogenesis. For example, if moister nests enhance offspring fitness and are cooler, then selection will favour the ability to develop in cool as well as moist conditions. Thus, the evolution of optimal incubation conditions with respect to one variable (e.g. temperature) may be driven by patterns of association with another variable (e.g. soil moisture) among natural nest-sites. Perhaps for this reason, the thermal optimum for incubation is surprisingly low in this tropical species. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 159,168. [source] The Late Prehistoric,Early Historic Game Sink in the Northwestern United StatesCONSERVATION BIOLOGY, Issue 1 2002R. Lee Lyman The number of big game killed by the Corps of Discovery in 1805,1806 and recorded by Lewis and Clark suggests that ungulates were abundant in central and eastern Montana and rare in western Montana, central Idaho, and southeastern Washington during the early nineteenth century. Paleoecologists Paul Martin and Chris Szuter conclude that this difference was a function of human predation. They support their conclusion that ungulates would have been abundant in southeastern Washington had humans not hunted them by arguing that the nineteenth-century livestock industry was successful without supplemental feeding. The livestock industry was, however, not consistently successful until artificial feeding was initiated. Archaeological data from eastern Washington indicate that ungulates have been taken by human hunters more frequently than small-mammal prey throughout the last 10,000 years and that ungulates decreased relative to small mammals coincident with changes in climate. Bison ( Bison bison) and elk (Cervus canadensis) were present in eastern Washington throughout the Holocene, but bison were abundant there only during a cooler and moister period; elk have been abundant only in the twentieth century, subsequent to transplants and the extermination of predators. Geographic variation in the abundance of bison across Montana, Idaho, and eastern Washington has been influenced by human predation but has also been influenced by biogeographic history, habitat differences, and climatic change. Resumen: Los datos históricos proveen información valiosa sobre las estructuras de los ecosistemas, sus funciones y procesos. El número de animales de caza grandes que fueron sacrificados por las tropas de descubrimiento en 1805-1806 y registradas por Lewis y Clark sugieren que los ungulados eran abundantes en Montana central y oriental y raros en Montana occidental, Idaho central y el sudeste de Washington durante los inicios del siglo diecinueve. Los paleontólogos Paul Martin y Chris Szuter concluyen que esta diferencia fue causada por la depredación humana. Ellos apoyan su conclusión de que los ungulados podrían haber sido abundantes en el sudeste de Washington si los humanos no los hubieran cazado argumentando que la industria de la ganadería del siglo diecinueve exitosa sin alimento suplementario. Sin embargo, la industria de la ganadería no fue consistentemente exitosa hasta que se inició la alimentación artificial. Los datos arqueológicos de Washington oriental indican que los ungulados fueron eliminados por los cazadores humanos mas frecuentemente que las presas pequeñas de mamíferos a lo largo de los últimos 10,000 años y que la disminución de ungulados, relativa a la de mamíferos pequeños coincidió con cambios en el clima. El bisonte (Bison bison) y el alce (Cervus canadiensis) estuvieron presentes en Washington oriental a lo largo del Holoceno, pero los bisontes fueron abundantes solo durante un periodo mas frío y húmedo; los alces habían sido abundantes solo en el siglo veinte subsecuente a los transplantes y a la exterminación de los depredadores. La variación en la abundancia de alces a lo largo de Montana, Idaho y el oriente de Washington estuvo influenciada por la depredación humana, pero también por la historia biogeográfica, las diferencias en hábitat y el cambio climático. [source] Olfactory preference for own mother and litter in 1-day-old rabbits and its impairment by thermotaxisDEVELOPMENTAL PSYCHOBIOLOGY, Issue 6 2008Jessica Serra Abstract We investigated the ability of rabbit pups to display preferences towards various elements of their postnatal environment during the stage of confinement in the nest. Subjects were submitted to a two-choice test during the first week after birth to assess if they could detect and discriminate between does, litters of pups, or nesting materials of the same developmental stage. On D1 and D7, pups were attracted to any lactating doe, litter, or nest when compared to an empty compartment. When two stimuli were opposed, pups preferred their own nest to an alien one on D1 and D7 but not their mother nor their siblings when opposed to alien does or pups. However, additional tests indicated that this lack of preference for kin conspecifics resulted from a predominant attraction to thermal cues over individual odors. Indeed, pups were strongly attracted to a warm compartment (37°C) than to a cooler one (20°C) and once thermal cues were controlled for in the testing situation, the pups were specifically attracted to odors of their own mother's hair and of their siblings. No preference was observed towards the mother's uterine secretions. In conclusion, pups can recognize olfactory cues emanating from their mother and their siblings the day after birth. The preference for nesting materials would reflect in major part the combined attraction to maternal and sibling odors present in the nest. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 542,553, 2008. [source] Modeling past and future alpine permafrost distribution in the Colorado Front RangeEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2005Jason R. Janke Abstract Rock glaciers, a feature associated with at least discontinuous permafrost, provide important topoclimatic information. Active and inactive rock glaciers can be used to model current permafrost distribution. Relict rock glacier locations provide paleoclimatic information to infer past conditions. Future warmer climates could cause permafrost zones to shrink and initiate slope instability hazards such as debris flows or rockslides, thus modeling change remains imperative. This research examines potential past and future permafrost distribution in the Colorado Front Range by calibrating an existing permafrost model using a standard adiabatic rate for mountains (0·5 °C per 100 m) for a 4 °C range of cooler and warmer temperatures. According to the model, permafrost currently covers about 12 per cent (326·1 km2) of the entire study area (2721·5 km2). In a 4 °C cooler climate 73·7 per cent (2004·4 km2) of the study area could be covered by permafrost, whereas in a 4°C warmer climate almost no permafrost would be found. Permafrost would be reduced severely by 93·9 per cent (a loss of 306·2 km2) in a 2·0 °C warmer climate; however, permafrost will likely respond slowly to change. Relict rock glacier distribution indicates that mean annual air temperature (MAAT) was once at least some 3·0 to 4·0 °C cooler during the Pleistocene, with permafrost extending some 600,700 m lower than today. The model is effective at identifying temperature sensitive areas for future monitoring; however, other feedback mechanisms such as precipitation are neglected. Copyright © 2005 John Wiley & Sons, Ltd. [source] Rock albedo and monitoring of thermal conditions in respect of weathering: some expected and some unexpected resultsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2005Kevin Hall Abstract Broadly speaking, there is, at least within geomorphic circles, a general acceptance that rocks with low albedos will warm both faster and to higher temperatures than rocks with high albedos, reflectivity influencing radiative warming. Upon this foundation are built notions of weathering in respect of the resulting thermal differences, both at the grain scale and at the scale of rock masses. Here, a series of paving bricks painted in 20 per cent reflectivity intervals from black through to white were used to monitor albedo-influenced temperatures at a site in northern Canada in an attempt to test this premise. Temperatures were collected, for five months, for the rock surface and the base of the rock, the blocks being set within a mass of local sediment. Resulting thermal data did indeed show that the dark bricks were warmer than the white but only when their temperatures were equal to or cooler than the air temperature. As brick temperature exceeded that of the air, so the dark and light bricks moved to parity; indeed, the white bricks frequently became warmer than the dark. It is argued that this ,negating' of the albedo influence on heating is a result of the necessity of the bricks, both white and black, to convect heat away to the surrounding cooler air; the darker brick, being hotter, initially convects faster than the white as a product of the temperature difference between the two media. Thus, where the bricks become significantly hotter than the air, they lose energy to that air and so their respective temperatures become closer, the albedo influence being superceded by the requirement to equilibrate with the surrounding air. It is argued that this finding will have importance to our understanding of weathering in general and to our perceptions of weathering differences between different lithologies. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effects of the North Atlantic Oscillation on growth and phenology of stream insectsECOGRAPHY, Issue 6 2004Robert A. Briers Climatic variation associated with the North Atlantic Oscillation (NAO) influences terrestrial and marine ecosystems, but its effects on river and stream ecosystems are less well known. The influence of the NAO on the growth of stream insects was examined using long-term empirical data on the sizes of mayfly and stonefly nymphs and on water temperature data. Models of egg development and nymphal growth in relation to temperature were used to predict the effect of the NAO on phenology. The study was based in two upland streams in mid-Wales UK that varied in the extent of plantation forestry in their catchments. Winter stream temperatures at both sites were positively related to the winter NAO index, being warmer in positive phases and colder in negative phases. The observed mean size and the simulated developmental period of mayfly nymphs were significantly related to the winter NAO index, with nymphs growing faster in positive phases of the NAO, but the growth of stonefly nymphs was not related to the NAO. This may have been due to the semivoltine stonefly lifecycle, but stonefly nymph growth is also generally less dependent on temperature. There were significant differences in growth rates of both species between streams, with nymphs growing more slowly in the forested stream that was consistently cooler than the open stream. Predicted emergence dates for adult mayflies varied by nearly two months between years, depending on the phase of the NAO. Variation in growth and phenology of stream insects associated with the NAO may influence temporal fluctuations in the composition and dynamics of stream communities. [source] Effects of temperature and elevation on habitat use by a rare mountain butterfly: implications for species responses to climate changeECOLOGICAL ENTOMOLOGY, Issue 4 2009SARAH ASHTON Abstract 1.,The present study used the mountain specialist butterfly Parnassius apollo as a model system to investigate how climate change may alter habitat requirements for species at their warm range margins. 2.,Larval habitat use was recorded in six P. apollo populations over a 700 m elevation gradient in the Sierra de Guadarrama (central Spain). Larvae used four potential host species (Sedum spp.) growing in open areas amongst shrubs. 3.,Parnassius apollo host-plant and habitat use changed as elevation increased: the primary host shifted from Sedum amplexicaule to Sedum brevifolium, and larvae selected more open microhabitats (increased bare ground and dead vegetation, reduced vegetation height and shrub cover), suggesting that hotter microhabitats are used in cooler environments. 4.,Larval microhabitat selection was significantly related to ambient temperature. At temperatures lower than 27 °C, larvae occupied open microhabitats that were warmer than ambient temperature, versus more shaded microhabitats that were cooler than ambient conditions when temperature was higher than 27 °C. 5.,Elevational changes in phenology influenced the temperatures experienced by larvae, and could affect local host-plant favourability. 6.,Habitat heterogeneity appears to play an important role in P. apollo larval thermoregulation, and may become increasingly important in buffering populations of this and other insect species against climatic variation. [source] Effects of handling on heat shock protein expression in rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2002Barbara Shayne Washburn Abstract As part of an effort to validate the use of heat shock proteins (HSPs) as biomarkers of exposure to and effects of contaminants, we evaluated the effect of two handling regimens on the induction of HSP 60 and 70 in rainbow trout (Oncorhynchus mykiss). Fish were acclimated to laboratory conditions for several weeks before the beginning of the experiment. Fish were then captured by net, placed in a cooler for 1 h while being transported in a truck, returned to their original tanks, then sacrificed 6 to 8 h later. Tricaine methane sulfonate (MS-222) was used during different phases of handling to reduce handling stress. Heat-stressed fish were included in the experiment as a positive control. Muscle, liver, gills, and heart were analyzed for HSP 60 and 70 by immunoblotting. We found no effect of any handling regimen on the induction of HSPs. These findings suggest that the capture and transport of fish for environmental monitoring purposes should not interfere with the use of stress proteins as biomarkers. [source] Species richness and spatial distribution of blackflies (Diptera: Simuliidae) in streams of Central Amazonia, BrazilFRESHWATER BIOLOGY, Issue 1 2002Neusa Hamada 1.,The spatial distribution and species richness of blackflies were evaluated at 58 stream sites in Central Amazonia, Brazil. Samples were taken along a north,south axis of approximately 130 km and a east,west axis of approximately 220 km. 2.,Based on stream-site characteristics, the occurrence of larvae of the six most frequently collected species was highly predictable (79.3,91.5% accuracy in prediction of occurrence). The predictive value of stream size and the presence of impoundments agrees with results of similar work in the Holarctic Region, suggesting a general responses of blackflies to environmental parameters. 3.,Although only 19.0% of interstream variation in species richness was explained by a regression model, results suggested that species richness was greater in larger, cooler, faster, covered streams with rocky beds than in smaller, warmer, slower, open streams with sandy bottoms. Overall, the species richness of blackflies (11 species in total) was lower than in the temperate zone suggesting, for some taxa at least, that aquatic communities do not follow the terrestrial pattern of greater species richness in the tropics. [source] Growth and physiological acclimation to temperature and inorganic carbon availability by two submerged aquatic macrophyte species, Callitriche cophocarpa and Elodea canadensisFUNCTIONAL ECOLOGY, Issue 2 2000B. Olesen Abstract 1.,Interactive effects of temperature and inorganic carbon availability on photosynthetic acclimation and growth of two submerged macrophyte species, Elodea canadensis and Callitriche cophocarpa, were examined to test the hypotheses that: (1) effects of temperature on growth rate and photosynthetic acclimation are suppressed under low inorganic carbon availability; (2) the plants compensate for the reduction in activity of individual enzymes at lower temperatures by increasing the activity per unit plant mass, here exemplified by Rubisco. The experiments were performed in the laboratory where plants were grown in a factorial combination of three temperatures (7,25 °C) and three inorganic carbon regimes. 2.,The relative growth rate of both species was strongly affected by growth conditions and increased by up to 4·5 times with increased temperature and inorganic carbon availability. The sensitivity to inorganic carbon was greatest at high temperature and the sensitivity to temperature greatest at high carbon concentrations. 3.,Photosynthetic acclimation occurred in response to growth conditions for both species. The affinity for inorganic carbon and the photosynthetic capacity, both measured at 15 °C, increased with reduced inorganic carbon availability during growth and were greater at warmer than at cooler growth temperature. The acclimative change in photosynthesis was related to the extent of temperature and inorganic carbon stress. Using data for Elodea, a negative relationship between degree of temperature stress and photosynthetic performance was found. In relation to inorganic carbon, a linear increase in CO2 affinity and photosynthetic capacity was found with increased inorganic carbon stress during growth. 4.,The total Rubisco activity declined with increased inorganic carbon availability during growth and with enhanced growth temperature. In addition, the activation state of Rubisco was higher at cooler than at warmer temperatures for Callitriche. This suggests that low-temperature grown plants compensate for the temperature-dependent reduction in activity of the individual Rubisco molecules by enhancing resource allocations towards Rubisco. [source] Gardening at the edge: Documenting the limits of tropical Polynesian kumara horticulture in southern New ZealandGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 3 2004Kari N. Bassett An Erratum has been published for this article in Geoarchaeology 19(6) 2004, 613. Kumara (Ipomoea batatus), a major food source for Maori, was brought to New Zealand from tropical Eastern Polynesia ,700 years ago. Maori successfully adapted their cultivation techniques to grow kumara in New Zealand's cooler, seasonal climate, although most kumara cultivation was limited to the warmer North Island, with cultivation becoming more marginal southward. Banks Peninsula area is considered to be the southernmost limit for kumara gardening. The Okuora Farm archeological site on the southern side of Banks Peninsula has five pits that appear to be of the raised-rim type used for over winter storage of kumara tubers. We conducted a preliminary investigation into the nature of the pits and surrounding 1 km2 area using nondestructive techniques in accordance with Maori designation of food storage sites as tapu. Ground penetrating radar (GPR) investigation of two of the pits revealed subsurface disturbances consistent with postholes and drains, typical of raised rim kumara storage pits. Soil modification typical of kumara gardening was identified on a 1 ha area on a warm north-northwest facing hillside. Several large borrow pits were identified as the likely source of the gravel added to the modified soil, possibly to retain heat and moisture. A plant phytolith study of soil samples identified several that appear to be from kumara. The combination of results strongly suggests this site was one of the southernmost Maori kumara gardening sites yet identified in New Zealand. © 2004 Wiley Periodicals, Inc. [source] RESPONSE OF A MONTENEGRO GLACIER TO EXTREME SUMMER HEATWAVES IN 2003 AND 2007GEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 4 2008PHILIP. ABSTRACT. The Debeli Namet glacier in the Durmitor massif, Montenegro, is one of the lowest altitude glaciers (2050,2300 m) at this latitude (42,44°N) in the northern hemisphere. The glacier survives well below the climatological equilibrium line altitude because of substantial inputs from avalanching and windblown snow. The glacier survived two of the hottest summers on record in 2003 and 2007, although it experienced significant retreat. However, during the intervening years (2004,2006) the glacier increased in size and advanced, forming a new frontal moraine. This rapid advance was primarily in response to much cooler summer temperatures, close to or cooler than average, and a marked increase in winter precipitation. The rapid growth and decay of the Debeli Namet glacier in response to inter-annual climate variability highlights the sensitivity of small cirque glaciers to short-term climate change. [source] Effects of wildfire and permafrost on soil organic matter and soil climate in interior AlaskaGLOBAL CHANGE BIOLOGY, Issue 12 2006JENNIFER W. HARDEN Abstract The influence of discontinuous permafrost on ground-fuel storage, combustion losses, and postfire soil climates was examined after a wildfire near Delta Junction, AK in July 1999. At this site, we sampled soils from a four-way site comparison of burning (burned and unburned) and permafrost (permafrost and nonpermafrost). Soil organic layers (which comprise ground-fuel storage) were thicker in permafrost than nonpermafrost soils both in burned and unburned sites. While we expected fire severity to be greater in the drier site (without permafrost), combustion losses were not significantly different between the two burned sites. Overall, permafrost and burning had significant effects on physical soil variables. Most notably, unburned permafrost sites with the thickest organic mats consistently had the coldest temperatures and wettest mineral soil, while soils in the burned nonpermafrost sites were warmer and drier than the other soils. For every centimeter of organic mat thickness, temperature at 5 cm depth was about 0.5°C cooler during summer months. We propose that organic soil layers determine to a large extent the physical and thermal setting for variations in vegetation, decomposition, and carbon balance across these landscapes. In particular, the deep organic layers maintain the legacies of thermal and nutrient cycling governed by fire and revegetation. We further propose that the thermal influence of deep organic soil layers may be an underlying mechanism responsible for large regional patterns of burning and regrowth, detected in fractal analyses of burn frequency and area. Thus, fractal geometry can potentially be used to analyze changes in state of these fire prone systems. [source] Boiling refrigerant-type panel cooler (refrigerant circulation and cooling performance)HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 2 2004Yoshiyuki Okamoto Abstract We have developed a new compact boiling refrigerant type panel cooler. It is a closed two-phase loop thermosiphon constructed with heat exchanger cores for an automobile air conditioning system. We confirmed higher performance of the natural refrigerant circulation type and tried to optimize the size of the refrigerant path in the boiling core by observing the internal refrigerant flow and successfully achieved much higher cooling performance. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(2): 94,105, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20003 [source] A comparison of forest and moorland stream microclimate, heat exchanges and thermal dynamicsHYDROLOGICAL PROCESSES, Issue 7 2008David M. Hannah Abstract Although the importance of riparian forest in moderating stream temperature variability is recognized, most previous research focuses on conifer harvesting effects and summer maximum temperature with highly variable findings. This article compares stream temperature, microclimate and heat exchange dynamics between semi-natural forest and moorland (no trees) reaches in the Scottish Cairngorms over two calendar years to provide a longer-term perspective. Mean daily water column temperature is warmer for moorland than forest in late winter,early spring, but cooler in summer. Daily water column temperature range is greater for moorland than forest. Streambed temperature dynamics are markedly different between reaches, reflecting contrasting groundwater,surface water (GW,SW) interactions. Mean, minimum and maximum daily air temperature is cooler, humidity is lower, and wind speed is much higher for moorland than forest on average. Net radiation is the dominant heat sink in autumn,winter and major heat source in spring,summer for moorland and summer for forest. Net radiation is greater in summer and lower in winter for moorland than forest. Sensible heat is an energy source in autumn,winter and sink in spring,summer, with loss (gain) greater in summer (winter) for moorland than forest. Latent heat is predominantly a sink for both reaches, with magnitude and variability higher for moorland than forest. Streambed heat flux is much smaller than fluxes at the air,water interface, with moorland and forest illustrating seasonal and between-reach differences attributable to different GW,SW interactions. Seasonal patterns in stream energy budget partitioning are illustrated schematically. To our knowledge, this is the first such study of mixed woodland, which generates notably different results to work on coniferous forest. This research provides a process basis to model stream thermal impact of changes in forest practice, and so inform decision making by land and water resource managers. Copyright © 2008 John Wiley & Sons, Ltd. [source] An inverse radiation problem of simultaneous estimation of heat transfer coefficient and absorption coefficient in participating mediaINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2003H. M. Park Abstract An inverse radiation problem is investigated where the spatially varying heat transfer coefficient h(z) and the absorption coefficient , in the radiant cooler are estimated simultaneously from temperature measurements. The inverse radiation problem is solved through the minimization of a performance function, which is expressed by the sum of square residuals between calculated and observed temperature, using the conjugate gradient method. The gradient of the performance function is evaluated by means of the improved adjoint variable method that can take care of both the function estimation and the parameter estimation efficiently. The present method is found to estimate h(z) and , with reasonable accuracy even with noisy temperature measurements. Copyright © 2002 John Wiley & Sons, Ltd. [source] Alumina Optical Surface Heat Shield for Use in Near-Solar EnvironmentINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 3 2009Don E. King Experiments indicate that coating a heat shield with alumina can significantly reduce spacecraft temperature during operation near the sun. A thin alumina (Al2O3) coating applied to carbon,carbon (C,C) reflects the majority of the visible solar irradiance while reemitting absorbed energy in the infrared. Testing on Al2O3 -coated C,C coupons using visible and NIR lasers (from ambient to 1773 K) show that the solar-absorptance-to-IR emittance ratio (,S/,IR) of the Al2O3 -coated heat shield was 0.6 or less. Compared with an uncoated carbon,carbon heat shield, the coated version is at least 12% cooler, enabling thermal insulation mass reductions, improved scientific measurements, and the use of less exotic thermal protection materials. [source] Fabrication of Precise Fluidic Structures in LTCCINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2009Fred Barlow A number of emerging applications of low-temperature co-fired ceramic (LTCC) require embedded fluidic structure within the co-fired ceramic and or precise external dimensional tolerances. These structures enable the control of fluids for cooling, sensing, and biomedical applications, and variations in their geometry from the design can have a significant impact on the overall performance of the devices. One example of this type of application is a multilayer cooler developed recently by the authors for cooling laser diode bars. In many laser systems, laser diodes are the primary emitters, or assemblies of these diode bars are used to pump traditional laser crystals such as Nd:YLF. Assemblies of these diodes require large amounts of electrical current for proper operation, and the device operating temperature must be carefully controlled in order to avoid a shift in the output wavelength. These diodes are packaged into water-cooled assemblies and by their nature dissipate enormous amounts of heat, with waste heat fluxes on the order of 2000 W/cm2. The traditional solution to this problem has been the development of copper multilayer coolers. Assemblies of laser diodes are then formed by stacking these diode bars and coolers. Several problems exist with this approach including the erosion of the copper coolers by the coolant, a requirement for the use of deionized water within the system, and a significant CTE mismatch between the diode bar and the metal cooler. Diodes are bonded to these metal structures and liquid coolant is circulated through the metal layers in order to cool the diode bar. In contrast, the coolers developed by the authors utilize fluid channels and jets formed within LTCC as well as embedded cavity structures to control the flow of a high-velocity liquid and actively cool the laser diode bars mounted on the surface of the LTCC., The dimensional tolerances of these cooler assemblies and complex shapes that are used to control the fluid can have a significant impact on the overall performance of the laser system. This paper describes the fabrication process used to create the precise channel and jet structures used in these LTCC-based coolers, as well as some of the challenges associated with these processes. [source] Thermographic assessment of tumor growth in mouse xenograftsINTERNATIONAL JOURNAL OF CANCER, Issue 5 2007Chengli Song Abstract In human breast tumors, a 1,2°C increase in skin surface temperature is usually observed at the periphery; it has been proposed that this change is due to the hypervascularity and increased blood flow resulting from tumor-associated angiogenesis. Here we tested the hypothesis that thermal imaging might represent a useful adjunctive technique in monitoring the growth dynamics of human tumor xenografts. Xenografts were established in immunocomprised nude mice using MDA-MB-231 or MCF7 breast cancer cells. We exploited the inherent noncontact and noninvasive advantages of infrared thermography to detect skin surface temperature changes. Continuous thermographic investigation was performed to detect and monitor tumor growth in vivo and high resolution digital images were analyzed to measure the tumor temperature dynamics. In contrast to the skin temperature increases associated with human breast cancer, a consistent temperature decrease was found in the xenograft mice. In one case, a smaller secondary tumor, otherwise undetectable, was clearly evident by thermal imaging. The tumors were cooler than the surrounding tissue with a maximum temperature reduction of 1.5°C for MDA-MB-231 tumor and 3°C for MCF7 tumors observed on day 14. In addition, the temperature of the xenograft tumors decreased progressively as they grew throughout the observation period. It was demonstrated that thermographic imaging could detect temperature changes as small as 0.1°C on the skin surface at an early stage of tumor development. The findings of the study indicate that thermographic imaging might have considerable potential in monitoring human tumor xenografts and their response to anticancer drugs. © 2007 Wiley-Liss, Inc. [source] Milk yields, physico-chemical properties and composition of milk from indigenous Malawi goats and their Saanen half-bredsINTERNATIONAL JOURNAL OF CONSUMER STUDIES, Issue 3 2003P.P. Mumba Abstract A study to compare milk yield, some physico-chemical properties and the chemical composition of milk from 23 indigenous Malawi goats and 10 Malawi local × Saanen crosses was carried out from January to March 2000. The results showed that the average milk yield from the crosses (102.0 ± 11.21 kg) was higher (P < 0.01) than that from the indigenous goats (37.1 ± 4.79 kg). However, the pH and specific gravity of both milk samples did not differ significantly from each other. The latter was attributed to the fat and total solids contents, which did not differ significantly in the two milk samples. Although the crude protein content was not significantly different, lactose and minerals, namely calcium, sodium, magnesium, potassium and chloride, were higher (P < 0.01) in milk from the crosses than in milk from the indigenous goat. The results have shown that the levels of nutrients in goat milk are high, and this is indicative of its potential to improve the diets of rural Malawians. Also, as smallholder farmers sell raw unheated milk to the processing plants, such milk should not be kept for> 33 h in the cool dry season and for not> 20 h in the hot dry season. Farmers can also adopt a charcoal cooler to save the milk for an even longer time than they can at room temperature. In this case, the raw milk can only be stored for not> 20 h in the cool dry season and not> 16 h in the hot dry season. [source] An investigation of thermoelectric cooling devices for small-scale space conditioning applications in buildingsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2010Mark Gillott Abstract This paper presents the study of a thermoelectric cooler (TEC) designed for small-scale space conditioning applications in buildings. A theoretical study was undertaken to find the optimum operating conditions, which were then applied in the laboratory testing work. A TEC unit was assembled and tested under laboratory conditions. Eight pieces of UltraTEC were shown to generate up to 220,W of cooling with a COP of 0.46 under the input current of 4.8,A for each module. Thermo-economical analysis was carried out and results showed that a system with PV panel can compete with an equivalent system without a PV panel when PV costs fall down to or lower than £1.25 per Watt. For the cases without a PV panel, the system with a high level of TEC power input delivered a better performance in terms of the average cooling energy price than that system with a low level of TEC power input after critical interest rate (currently 4%). Copyright © 2009 John Wiley & Sons, Ltd. [source] The performance analysis of a two-stage transcritical CO2 cooling cycle with various gas cooler pressuresINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2008Arif Emre Özgür Abstract A theoretical analysis of a two-stage transcritical CO2 cooling cycle is presented. The effect of a two-stage cycle with intercooling process on the system coefficient of cooling performance is presented for various gas cooler pressures. However, the performance comparison between one-stage and two-stage cycles is presented for same operating conditions. Gas cooler pressure, compressor isentropic efficiency, gas cooler efficiency, intercooling quantity and refrigerant outlet temperature from the gas cooler are used as variable parameters in the analysis. It is concluded that the performance of the two-stage transcritical CO2 cycle is approximately 30% higher than that of the one-stage transcritical CO2 cycle. Hence, the two-stage compression and intercooling processes can be assumed as valuable applications to improve the transcritical CO2 cycle performance. Copyright © 2008 John Wiley & Sons, Ltd. [source] Performance enhancement of gas turbines by inlet air-cooling in hot and humid climatesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2006Majed M. Alhazmy Abstract In this paper, a model to study the effect of inlet air-cooling on gas turbines power and efficiency is developed for two different cooling techniques, direct mechanical refrigeration and an evaporative water spray cooler. Energy analysis is used to present the performance improvement in terms of power gain ratio and thermal efficiency change factors. Relationships are derived for an open gas turbine cycle with irreversible compression and expansion processes coupled to air-cooling systems. The obtained results show that the power and efficiency improvements are functions of the ambient conditions and the gas turbine pressure ratio. The performance improvement is calculated for, ambient temperatures from 30 to 50°C, the whole range of humidity ratio (10,100%) and pressure ratio from 8 to 12. For direct mechanical refrigeration air-cooling, the power improvement is associated with appreciable drop in the thermal efficiency. The maximum power gain can be obtained if the air temperature is reduced to its lowest limit that is the refrigerant evaporation temperature plus the evaporator design temperature difference. Water spray cooling process is sensitive to the ambient relative humidity and is suitable for dry air conditions. The power gain and efficiency enhancement are limited by the wet bulb temperature. The performance of spray evaporative cooler is presented in a dimensionless working graph. The daily performance of the cooling methods is examined for an ABB-11D5 gas turbine operating under the hot humid conditions of Jeddah, Saudi Arabia. The results indicate that the direct mechanical refrigeration increased the daily power output by 6.77% versus 2.57% for the spray air-cooling. Copyright © 2005 John Wiley & Sons, Ltd. [source] The impact of fouling on performance evaluation of evaporative coolers and condensersINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2005Bilal A. Qureshi Abstract Fouling of evaporative cooler and condenser tubes is one of the most important factors affecting their thermal performance, which reduces effectiveness and heat transfer capability with time. In this paper, the experimental data on fouling reported in the literature are used to develop a fouling model for this class of heat exchangers. The model predicts the decrease in heat transfer rate with the growth of fouling. A detailed model of evaporative coolers and condensers, in conjunction with the fouling model, is used to study the effect of fouling on the thermal performance of these heat exchangers at different air inlet wet bulb temperatures. The results demonstrate that fouling of tubes reduces gains in performance resulting from decreasing values of air inlet wet bulb temperature. It is found that the maximum decrease in effectiveness due to fouling is about 55 and 78% for the evaporative coolers and condensers, respectively, investigated in this study. For the evaporative cooler, the value of process fluid outlet temperature Tp,out varies by 0.66% only at the clean condition for the ambient wet bulb temperatures considered. Copyright © 2005 John Wiley & Sons, Ltd. [source] Study on carbon dioxide gas cooler heat transfer process under supercritical pressuresINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2002Jianfeng Wang Abstract In carbon dioxide transcritical air-conditioning and heat pump systems, the high-pressure-side heat exchanger operating at supercritical pressures is usually called as gas cooler. The carbon dioxide gas cooler displays much difference from the traditional heat exchangers employing constant property fluids. The commonly used logarithmic mean temperature difference (LMTD) and effectiveness,heat transfer unit (,-NTU) fail for the gas cooler design calculation as the carbon dioxide properties change sharply near the critical or pseudo-critical point in the heat transfer processes. The new effective heat transfer temperature difference expression for variable fluid property derived by the authors is verified by numeric simulation of the carbon dioxide gas cooler. Moreover, the available correlated models for the cooled carbon dioxide supercritical heat transfer are used to simulate the gas cooler. Detail analysis is made for the deviations among the different models, and for the distributions of local convective coefficient, heat flux, and local temperature of carbon dioxide along the flow path in the gas cooler. Copyright © 2002 John Wiley & Sons, Ltd. [source] Performance characteristics of a magnetic Stirling cooler,INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2002Feng Wu Abstract The quantum mechanics model of a magnetic Stirling cooler is established. The optimal relation between the cooling load and the coefficient of performance (COP) is obtained. The maximum cooling load and corresponding COP as well as the maximum COP and the corresponding cooling load are derived. The optimization criteria for a magnetic Stirling cooler are determined. The results obtained here will be useful for the further understanding and the selection of the optimal operating conditions for a magnetic Stirling cooler. Published in 2002 by John Wiley & Sons, Ltd. [source] Fishing in Peru between 10,000 and 3750 BPINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 1-2 2001Elizabeth J. ReitzArticle first published online: 28 FEB 200 Abstract Archaeozoological data for the period of 10,000,5000 bp were rare for the southeastern Pacific coast, until recent work provided data from eight sites in Peru and Ecuador. These sites span the early to mid-Holocene period, during which time modern climatic conditions became established. Vertebrate faunal data from these sites provide an opportunity to explore the influence of mid-Holocene environmental changes on fishing in Peru during this time. With two exceptions, most faunal collections are dominated by marine animals, with virtually no terrestrial vertebrates. Many of the marine organisms are catholic species, tolerant of a wide variety of water conditions, rather than ones which clearly prefer warm,tropical or warm,temperate ones. Warm,tropical species are more common in the northern assemblages, as would be expected. There is a temporal pattern as well. Within three subdivisions of this area, warm,tropical animals diminish in abundance, and warm,temperate animals increase. These differences probably reflect cultural responses to mid-Holocene environmental change, in which coastal waters from southern Peru into Ecuador became cooler. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||