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Cold Water (cold + water)
Selected AbstractsPenguins as oceanographers unravel hidden mechanisms of marine productivityECOLOGY LETTERS, Issue 3 2002Jean-Benoît Charrassin ABSTRACT A recent concept for investigating marine ecosystems is to employ diving predators as cost-effective, autonomous samplers of environmental parameters (such as sea-temperature). Using king penguins during their foraging trips at sea, we obtained an unprecedented high resolution temperature map at depth off the Kerguelen Islands, Southern Ocean, a poorly sampled but productive area. We found clear evidence of a previously unknown subsurface tongue of cold water, flowing along the eastern shelf break. These new results provide a better understanding of regional water circulation and help explain the high primary productivity above the Kerguelen Plateau. [source] Foraging energetics of arctic cormorants and the evolution of diving birdsECOLOGY LETTERS, Issue 3 2001David Grémillet Efficient body insulation is assumed to have enabled birds and mammals to colonize polar aquatic ecosystems. We challenge this concept by comparing the bioenergetics of cormorants (Phalacrocorax carbo) living in temperate and arctic conditions. We show that although these birds have limited insulation, they maintain high body temperature (42.3 °C) when diving in cold water (1,10 °C). Their energy demand at these times is extremely high (up to 60 W kg,1). Free-living cormorants wintering in Greenland (water temperature ,1 °C) profoundly alter their foraging activity, thus minimizing time spent in water and the associated high thermoregulatory costs. They then meet their daily food demand within a single intense dive bout (lasting 9 min on average). Their substantial energy requirements are balanced by the highest predatory efficiency so far recorded for aquatic predators. We postulate that similar behavioural patterns allowed early diving birds (Cretaceous) to colonize cold coastal areas before they evolved efficient insulation. [source] Developmental effects of bioaccumulated selenium in eggs and larvae of two salmonid speciesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2005Jodi Holm Abstract Elevated concentrations of Se have been detected in cold, flowing water habitats near uranium and coal mines in Canada. Fish from these systems have concentrations of Se in their tissues that exceed toxic effect thresholds that have been established for warm-water fishes. However, the applicability of toxic effect thresholds and guidelines to cold water, lotic habitats is a matter of contention in the literature since most cases of Se toxicosis have been documented in standing, warm-water systems. To examine the possibility of impaired reproduction in wild rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) near coal mining activity in the northeastern slopes region of Alberta, Canada, spawn from both species were collected from exposure and reference sites. Gametes were fertilized in the laboratory, reared to the swim-up stage, and examined for deformities. A significant relationship was observed for rainbow trout between the amount of Se in eggs and the incidence of developmental abnormalities, specifically craniofacial defects, skeletal deformities, and edema. These associations approximate exponential functions with probabilities that 15% of the population would be affected occurring between 8.8 and 10.5 ,g Se per gram of wet egg weight, based on probit analysis. These relationships are similar to those described for centrarchids inhabiting a seleniferous warm-water lake. No such relationships were established for brook trout. [source] The energetic equivalence of changing salinity and temperature to juvenile salmonFUNCTIONAL ECOLOGY, Issue 4 2006S. J. WEBSTER Summary 1The influence of salinity, temperature and physiological development on habitat choice by juvenile salmon is poorly understood. We measured differences in the net energetic cost of habitats that differed in salinity or temperature using behavioural titration of juvenile salmon and correlated these costs with body size and osmoregulatory enzyme activity to quantify how costs change with physiological development. 2Juvenile salmon showed a strong preference for saline water (27 or 15 vs 0) and for cold water (9 °C vs 14 °C). It was estimated to be 0·15 W and 0·11 W more costly for salmon to forage in fresh water than in 15 and 27 salt water, respectively, and 0·09 W more costly to forage in warm than in cold water. 3We expected fish to prefer 15 salt water to fresh water regardless of enzyme activity because they are iso-osmotic with this salt concentration. In contrast, preference for higher salt concentrations should increase with enzyme activity. Consistent with our expectations, enzyme activity was not correlated with preference for 15 salt water, but was positively correlated with preference for 27 salt water. 4The cost of changing salinity vs changing temperature were very similar, indicating that knowledge of both of these costs are necessary to understand juvenile salmon habitat choice. [source] Flashing characteristics in a pipe downstream from a depressurizing tank and temperature fluctuation characteristics at a mixing tee junction with cold water injectionHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2003Koji Shiina Abstract The flashing characteristics in a pipe downstream from a depressurizing tank were experimentally and analytically investigated on the basis of the transient test and two-phase flow analysis. The following conclusions were obtained. (1) When the pressure margin of the pump inlet side and the distance to obtain an isothermal condition were sufficient, flashing phenomena did not occur in spite of the decreasing pressure. (2) When the ratio of the cold water injection flow rate to the hot water flow rate Mc/Mh increased, the peak distance of the water temperature fluctuation moved from L/D = 1 to 0, and the maximum water temperature fluctuation ratio was about 40% of the temperature difference between hot and cold water near the mixing tee junction. Because no problem occurred regarding the pipe material thermal fatigue, reliability of the mixing tee junction was assured. (3) Due to suppression of flashing phenomena of the mixing pipe system, the decision diagram on the flashing occurrence was obtained from the test and the analytical results, taking into consideration three factors: the depressurizing ratio in the tank; the cold water injection flow rate due to remaining subcooling; and the delay time of thermal mixing. The simplified analytical equation was used to decrease the cold water injection flow rate by the optimized pipe length between the mixing tee junction and the drain pump. The cold water injection flow rate was minimized when the pipe length was about 15 to 20 times the pipe inner diameter. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 411,429, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10096 [source] Water temperature sampling by foraging Brünnich's Guillemots with bird-borne data loggersJOURNAL OF AVIAN BIOLOGY, Issue 2 2001Yutaka Watanuki (correspondence) We describe the features of waters where seabirds were feeding by sampling vertical water temperature profiles with data loggers mounted on five Brünnich's Guillemots in Svalbard, Norway. The guillemots foraged in a cold water (,0.5,0.5°C SST (sea surface temperature)) by making 1.8 dive bouts in short trips (32,257 min duration) as well as in moderate (0.5,2.0°C SST) and warm waters (2.5,4.0°C SST) by making 6.0 dive bouts during long trips (411,688 min duration). Judging from outbound flying time (15.7,24.4 min), time between dive bouts (23.9,43.3 min) and water types, the birds probably fed in fjord or coastal waters during short trips and in both coastal and offshore waters during long trips. Water temperature and diving behaviour can be simultaneously recorded by small data loggers, which therefore will provide useful information on marine features and foraging activity of top predators. [source] Persistence of coastal spruce refugia during the Holocene in northern New England, USA, detected by stand-scale pollen stratigraphiesJOURNAL OF ECOLOGY, Issue 2 2002Molly Schauffler Summary 1 Pollen data from wet, forested hollows in five spruce (Picea) stands on the eastern coast of Maine, USA, reveal that spruce has been well-established (spruce pollen > 6%) for at least 5000 years at four of the sites (Isle au Haut, Schoodic Peninsula, and Roque Island). Spruce became dominant in the fifth stand (Blackwoods, Mount Desert Island) only in the last 2000 years. This is in contrast to pollen stratigraphies from two inland forest hollows and from inland lakes that indicate a significant region-wide increase in the abundance of spruce only 1000 years ago. 2 All five coastal pollen stratigraphies suggest that conditions along the east coast of Maine became cooler and moister sometime between 6000 and 5000 years ago. Mid-Holocene changes in vegetation and sediment accumulation correspond with the timing of rapid increases in tidal amplitude and diurnal mixing of cold water in the Gulf of Maine, suggestive that these resulted in increased marine effects on the local climate at a time that was generally warmer than present. 3 Two inland forest-hollow stratigraphies do not show evidence of mid-Holocene cooling. Coastal effects therefore persisted for several thousand years despite regional climate changes. 4 The pollen data suggest that refugia along the coast (and probably in isolated sites inland), may have played a critical role in allowing the rapid regional expansion of spruce around 1000 years ago. The steep increases in the abundance of spruce pollen in all forest-hollow and lake pollen stratigraphies in northern New England at that time corroborate other evidence of a region-wide shift to cooler and moister conditions. 5 Pollen stratigraphies from small forested hollows provide a means to examine local vegetation dynamics and interpret those dynamics in the context of regional signals. [source] Effects of temperature on larval fish swimming performance: the importance of physics to physiologyJOURNAL OF FISH BIOLOGY, Issue 4 2002I. Hunt von Herbing Temperature influences both the physiology offish larvae and the physics of the flow conditions under which they swim. For small larvae in low Reynolds number (Re) hydrodynamic environments dominated by frictional drag, temperature-induced changes in the physics of water flow have the greatest effect on swimming performance. For larger larvae, in higher Re environments, temperature-induced changes in physiology become more important as larvae swim faster and changes in swimming patterns and mechanics occur. Physiological rates at different temperatures have been quantified using Q10s with the assumption that temperature only affected physiological variables. Consequently, Q10s that did not consider temperature-induced changes in viscosity overestimated the effect of temperature on physiology by 58% and 56% in cold-water herring and cod larvae respectively. In contrast, in warm-water Danube bleak larvae, Q10s overestimated temperature-induced effects on physiology by only 5,7%. This may be because in warm water, temperature-induced changes affect viscosity to a smaller degree than in cold water. Temperature also affects muscle contractility and efficiency and at high swimming velocities, efficiency decreases more rapidly in cold-exposed than in warm-exposed muscle fibres. Further experiments are needed to determine whether temperature acts differently on swimming metabolism in different thermal environments. While hydrodynamic factors appear to be very important to larval fish swimming performance in cold water, they appear to lose importance in warm water where temperature effects on physiology dominate. This may suggest that major differences exist among locomotory capacities of larval fish that inhabit cold, temperate waters compared to those that live in warm tropical waters. It is possible that fish larvae may have developed strategies that affect dispersal and recruitment in different aquatic habitats in order to cope not only with temperature-induced physiological challenges, but physical challenges as well. [source] ANTIOXIDANT PROPERTIES OF WATER EXTRACTS FROM PARCHING GREEN TEAJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2010SHENG-DUN LIN ABSTRACT Cold and hot water extracts (2, 6 and 10%) were prepared from parching green tea and its antioxidant properties studied and potential antioxidant components determined. Yields of hot water extracts (17.53,28.63%) were significantly higher than those of cold water extracts (13.34,16.14%). The half maximal effective concentration (EC50) values in antioxidant activity and reducing power were 2.17,2.75 and 0.22,0.30 mg/mL, respectively. Scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals were comparable. EC50 values in scavenging ability on hydroxyl radicals and chelating ability on ferrous ions were 3.31,4.54 and 1.63,3.09 mg/mL, respectively. Contents of total phenols were 220.52,339.83 mg/g whereas those of total catechins in cold and hot water extracts were 130.22,146.28 mg/g and 136.40,191.33 mg/g, respectively. Based on the results obtained, hot water extracts were more effective in antioxidant activity, reducing power and scavenging ability on hydroxyl radicals but less effective in chelating ability on ferrous ions. PRACTICAL APPLICATIONS Tea is one of popular drinks in the world. The consumption of green tea is especially popular in Asia, mainly for its health benefits. Parched tea is a Chinese style green tea, which is different from the Japanese style steamed tea. Recently, the tea prepared by brewing tea leaves in cold water has become a new choice in Taiwan in addition to traditionally hot water-brewed tea. Results from this research, the cold and hot water extracts of green tea are good antioxidant. Besides, green tea is also reported to reduce serum cholesterol levels and inhibit hypertension, mutagenesis, and tumourigenesis in several experiments in vitro and in vivo. Therefore, the extract of green tea has the potential to be developed into new health foods, and the cold brewing would be a new alternative way to make a tea. [source] SENSORY QUALITY OF READY-TO-EAT LETTUCE WASHED IN WARM, CHLORINATED WATER,JOURNAL OF FOOD QUALITY, Issue 6 2000P.J. DELAQUIS ABSTRACT Three prepackaging treatments were evaluated for ready-to-eat (RTE) lettuce. Fresh iceberg lettuce pieces were dipped for 3 min in cold water (4C) with 100 ppm total chlorine, warm (47C) water with 100 ppm chlorine and tap water at room temperature. The lettuce was dewatered by centrifugation, packed in breathable film bags (OTR: 1600-2000 cc/m2/24 h) and stored for 11 days at 1C. Sensory evaluation revealed that the texture and visual appearance of stored RTE lettuce were improved by the warm water treatment. However, heat processing induced changes in the flavor of the lettuce, and a chlorinaceous off-odor was detected by some panelists. [source] Palliation in cancer of the oesophagus , what passes down an oesophageal stent?JOURNAL OF HUMAN NUTRITION & DIETETICS, Issue 5 2003A. Holdoway Introduction: Self-expanding metal stents are becoming an increasingly popular method of palliation of dysphagia in advanced oesophageal carcinoma. Approximately 10% require intervention post-placement because of blockage (Angorn, 1981). This could be prevented by effective dietary advice. We set out to write evidence-based dietary guidelines for patients undergoing oesophageal stent insertion. A comprehensive literature search failed to identify evidence to support the present guidelines used by manufacturers and dietitians on foods allowed or to avoid and the use of fizzy drinks to ,clean' the stent. Only reference on the ability to consume a semi-solid or solid diet was made (Nedin, 2002). We therefore tested the ability of 50 foods to pass through a stent and the efficacy of fizzy water in unblocking an occluded stent. Method: Normal mouthfuls of raw and cooked, peeled/unpeeled fruit and vegetables, casseroles, griddle or grilled plain meat, poultry or fish, eggs, nuts, dried fruit and bread in various forms were tested. An adult female chewed a ,normal' mouthful of each test food and at the point of swallowing the bolus of food was passed into an expanded Ultraflex metal covered stent (internal diameter 18 mm). If occlusion occurred, water was dribbled through the stent, simulating swallowing fluid, in an attempt to unblock the stent. If the occlusion remained, the stent was agitated to mimic advice given about moving around to unblock a stent in a patient. If it remained occluded, a smaller amount of food, approximately half a mouthful, was chewed for twice as long and re-tested. To test the efficacy of fizzy water to clear an occlusion, we compared the ability of water, warm water and fizzy water to unblock a stent artificially occluded with a bolus of bread. Results: Foods that occluded the stent but passed through if eaten in half mouthfuls and chewed for twice normal chewing time included sandwiches, dry toast, apple, tinned pineapple, fresh orange segments with pith removed, up to six sultanas, chopped dried apricot, boiled egg, muesli, meat and poultry. Dry meat, fruit with pith, skins of capsicum peppers and tomatoes, more than seven sultanas and dried apricots caused occlusion. Nuts and vegetables such as lettuce, which are cited in many diet sheets as items to avoid (Nedin, 2002), passed through the stent when chewed to a normal level. The volumes of fluid required to unblock a stent occluded with bread were 5 l of fizzy water, 3.5 l of cold water or 1 l of warm water. Conclusion: If a patient has good dentition and can chew well and take small mouthfuls and prepare and cook food appropriately, it is likely that they can enjoy a wide variety of solid foods. The use of fizzy drinks to maintain the patency of the stent in patients prone to reflux is questionable, warm fluids may be more efficacious. Based on these initial findings we are updating our dietary guidelines for patients undergoing oesophageal stent insertion and hope to audit stent occlusion following implementation. [source] Marine macroalgae analyzed by mass spectrometry are rich sources of polyunsaturated fatty acids,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 12 2005L. De Angelis Abstract Algae from cold water (Canada) and warm water (China) were analyzed for their total lipid content, and for their fatty acid (FA) composition and content. The major findings are that FA from Canadian algae are generally richer in polyunsaturated FA (PUFA), with a higher n-3/n-6 FA ratio, and a higher degree of total unsaturation. The 18 C, 4 double bonds FA (18 : 4 stearidonic acid, morotic acid as synonym) was detected in greater amounts in cold water samples. The high levels of total PUFA, and especially of n-3 FA in Canadian algae, suggests their possible utilizations for nutritional purposes. Copyright © 2005 John Wiley & Sons, Ltd. [source] VARIABILITY IN THE ECOPHYSIOLOGY OF HALIMEDA SPP. (CHLOROPHYTA, BRYOPSIDALES) ON CONCH REEF, FLORIDA KEYS, USA,JOURNAL OF PHYCOLOGY, Issue 4 2003Kevin Beach The photosynthetic performance, pigmentation, and growth of a Halimeda community were studied over a depth gradient on Conch Reef, Florida Keys, USA during summer,fall periods of 5 consecutive years. The physiology and growth of H. tuna (Ellis & Solander) Lamouroux and H. opuntia (L.) Lamouroux on this algal dominated reef were highly variable. Maximum rate of net photosynthesis (Pmax), respiration rate, and quantum efficiency (,) did not differ between populations of either species at 7 versus 21 m, even though the 21-m site received a 66% lower photon flux density (PFD). Physiological parameters, as well as levels of photosynthetic pigments, varied temporally. Pmax, saturation irradiance, compensation irradiance, and growth were greatest in summer months, whereas ,, chl a, chl b, and carotenoid concentrations were elevated each fall. Halimeda tuna growth rates were higher at 7 m compared with 21 m for only two of five growth trials. This may have arisen from variability in light and nutrient availability. Individuals growing at 7 m received a 29% greater PFD in August 2001 than in 1999. In August 1999 and 2001 seawater temperatures were uniform over the 14-m gradient, whereas in August 2000 cold water regularly intruded upon the 21-m but not the 7-m site. These results illustrate the potentially dynamic relationship between nutrients, irradiance, and algal productivity. This suggests the necessity of long-term monitoring over spatial and temporal gradients to accurately characterize factors that impact productivity. [source] Polymers derived from N -isopropylacrylamide and azobenzene-containing acrylamides: Photoresponsive affinity to waterJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2004Haruhisa Akiyama N -Isopropylacryamide was copolymerized by free-radical polymerization with N -[2-(4-phenylazophenoxy)ethyl]acrylamide derivatives that were substituted at their 4,-position with ethoxy, methoxyethoxy, or isopropyl units, or with N -{2-[4-(pyridin-2-ylazo)phenoxy]ethyl}acrylamide. The polymers were soluble in cold water and possessed lower critical solution temperatures (LCSTs). The value of the LCST rose a few degrees after UV irradiation and dropped after irradiation with visible light, reversibly, in processes that corresponded to the isomerization of the azobenzene units. The polymers became increasingly hydrophobic after increasing their azobenzene content. The difference of hydrophobicity correlates with the absorption band height at about 400 nm. The structure of the substituent on the azobenzene unit affected both the transition temperature and the hydrophobicity. A change in photoinduced wettability for water was observed to occur on a prepared film at a temperature different from the LCST determined in water. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5200,5214, 2004 [source] Water-related occupations and diet in two Roman coastal communities (Italy, first to third century AD): Correlation between stable carbon and nitrogen isotope values and auricular exostosis prevalence,AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010Fiona Crowe Abstract The reconstruction of dietary patterns in the two Roman imperial age coastal communities of Portus and Velia (I,III AD) by means of stable isotope analysis of bone remains has exposed a certain degree of heterogeneity between and within the two samples. Results do not correlate with any discernible mortuary practices at either site, which might have pointed to differential social status. The present study tests the hypothesis of a possible connection between dietary habits and occupational activities in the two communities. Among skeletal markers of occupation, external auricular exostosis (EAE) has proved to be very informative. Clinical and retrospective epidemiological surveys have revealed a strong positive correlation between EAE development and habitual exposure to cold water. In this study, we show that there is a high rate of occurrence of EAE among adult males in both skeletal samples (21.1% in Portus and 35.3% in Velia). Further, there is a statistically significant higher prevalence of EAE among those individuals at Velia with very high nitrogen isotopic values. This points to fishing (coastal, low-water fishing) as the sea-related occupation most responsible for the onset of the ear pathology. For Portus, where the consumption of foods from sea and river seems to be more widespread through the population, and where the scenario of seaport and fluvial activities was much more complex than in Velia, a close correlation between EAE and fish consumption by fishermen is less easy to establish. Am J Phys Anthropol 2010. © 2009 Wiley-Liss, Inc. [source] Variability in the summertime coastal marine atmospheric boundary-layer off California, USATHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 597 2004Linda Ström Abstract An analysis of boundary-layer structure and surface-layer turbulence from measurements off the California coast is presented from data collected by research aircraft during two field experiments: the Coastal Waves 1996 (CW96) and the Monterey Area Ship Track (MAST) experiments. CW96 covers the near-coast region, in particular in the vicinity of major headlands, whereas MAST extends offshore. Along the US west coast, coastal modification of the along-coast flow occurs on two main horizontal scales. Firstly, a large-scale variability is due to the interplay between the shallow near-coast marine atmospheric boundary-layer (MABL) and the coastal terrain, typically higher than the MABL depth. The MABL depth decreases smoothly towards the coast while the wind speed increases to a coastal jet in response to the sloping MABL inversion. Secondly, the flow is affected by supercritical flow dynamics. As the wind speed increases and the MABL depth decreases towards the coast, the MABL flow becomes supercritical in a shallow-water sense. As supercritical shallow-water flow interacts with major headlands, expansion fans form, affecting both the wind speed and the MABL depth. The combination of CW96 and MAST data reveals significant differences between the flow along the coast and that far offshore. MABL winds are stronger near the coast whereas aloft the winds are weaker than offshore. The near-coast MABL is also better mixed. Turbulence increases towards the coast while the sensible-heat flux decreases and often changes sign, leading to stable stratification near the coast. A length-scale determining the across-coast influence of the expansion fans is defined from simple inviscid and irrotational shallow-water theory. Data from four days of the CW96 experiment show that this simple theory describes the low-level wind speed adequately. Surface-layer turbulence also scales with this simple length-scale, but the results are complicated by upwelling of cold water, giving rise to strong internal boundary-layers. From terms in the turbulent-energy budgets it appears that dissipation of turbulence exceeds local production. Copyright © 2004 Royal Meteorological Society [source] Effect of oral vitamin E supplementation on oxidative stress in guinea-pigs with short-term hypothermiaCELL BIOCHEMISTRY AND FUNCTION, Issue 6 2007Leyla Aslan Abstract Effects of oral vitamin E supplementation on blood malondialdehyde (MDA), glutathione (GSH) and vitamin E levels and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) enzyme activities in acute hypothermia of guinea-pigs were investigated. Thirty male guinea pigs, weighing 500,800,g were randomly divided into one of three experimental groups: A (control, without cooling), B (hypothermic) and C (hypothermic with vitamin E supplementation). The guinea-pigs of group C received daily oral supplementation of 460,mg,kg,1 bw vitamin E for 4 days before inducing hypothermia. Twenty-four hours after the last vitamin E supplementation, the guinea-pigs of the B and C groups were cooled by immersion into cold water (10,12°C), and the control guinea-pigs were immersed into water of body temperature (37°C) up to the neck for 5,min without using any anaesthetic or tranquilizer. Rectal body temperatures of groups were measured and blood samples for biochemical analysis were collected immediately after the cooling. The body temperature, GSH and vitamin E levels and GSH-Px enzyme activity of hypothermic guinea-pigs were lower (p,<,0.05), but SOD enzyme activity was not different (p,>,0.05) from those of control animals. Although, the body temperature of hypothermic with vitamin E supplementation group was lower (p,<,0.05), all other parameters of this group were not different (p,>,0.05) from the controls. It was concluded that oral supplementation of vitamin E can alleviate the lipid peroxidation-induced disturbances associated with hypothermia by increasing the serum vitamin E level to normal. However, more studies are needed to prove whether this vitamin can improve quality of life during the cold seasons. Copyright © 2007 John Wiley & Sons, Ltd. [source] Second-Law Based Thermodynamic Analysis of a Novel Heat ExchangerCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2009Y.-L. He Abstract In the present investigation, second-law based thermodynamics analysis was applied to a new heat exchanger with helical baffles. The helical baffles are designed as quadrant ellipses and each baffle occupies one quadrant of the cross-section of the shell side. Experimental tests were carried out with cold water in the tube side with a constant flow rate, and hot oil on the shell side with flow rate range from 4,24,m3/h. The temperatures and pressures for the inlet and outlet of both sides were measured. The heat transfer, pressure drop, entropy generation, and exergy loss of the new heat exchanger were investigated and compared with the results for a conventional shell-and-tube heat exchanger with segmental baffles. The computed results indicated that both the entropy generation number and exergy losses of the new heat exchanger design are lower than those of the heat exchanger with segmental baffles, which means that the novel heat exchanger has a higher efficiency than the heat exchanger with segmental baffles, from the second-law based thermodynamics viewpoint. [source] Cardiovascular changes induced by cold water immersion during hyperbaric hyperoxic exposureCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 5 2007Alain Boussuges Summary The present study was designed to assess the cardiac changes induced by cold water immersion compared with dry conditions during a prolonged hyperbaric and hyperoxic exposure (ambient pressure between 1·6 and 3 ATA and PiO2 between 1·2 and 2·8 ATA). Ten healthy volunteers were studied during a 6 h compression in a hyperbaric chamber with immersion up to the neck in cold water while wearing wet suits. Results were compared with measurements obtained in dry conditions. Echocardiography and Doppler examinations were performed after 15 min and 5 h. Stroke volume, left atrial and left ventricular (LV) diameters remained unchanged during immersion, whereas they significantly fell during the dry session. As an index of LV contractility, percentage fractional shortening remained unchanged, in contrast to a decrease during dry experiment. Heart rate (HR) significantly decreased after 5 h, although it had not changed during the dry session. The changes in the total arterial compliance were similar during the immersed and dry sessions, with a significant decrease after 5 h. In immersed and dry conditions, cardiac output was unchanged after 15 min but decreased by almost 20% after 5 h. This decrease was related to a decrease in HR during immersion and to a decrease in stroke volume in dry conditions. The hydrostatic pressure exerted by water immersion on the systemic vessels could explain these differences. Indeed, the redistribution of blood volume towards the compliant thoracic bed may conceal a part of hypovolaemia that developed in the course of the session. [source] Phylogeny of the sea spiders (Arthropoda, Pycnogonida) based on direct optimization of six loci and morphologyCLADISTICS, Issue 3 2007Claudia P. Arango Higher-level phylogenetics of Pycnogonida has been discussed for many decades but scarcely studied from a cladistic perspective. Traditional taxonomic classifications are yet to be tested and affinities among families and genera are not well understood. Pycnogonida includes more than 1300 species described, but no systematic revisions at any level are available. Previous attempts to propose a phylogeny of the sea spiders were limited in characters and taxon sampling, therefore not allowing a robust test of relationships among lineages. Herein, we present the first comprehensive phylogenetic analysis of the Pycnogonida based on a total evidence approach and Direct Optimization. Sixty-three pycnogonid species representing all families including fossil taxa were included. For most of the extant taxa more than 6 kb of nuclear and mitochondrial DNA and 78 morphological characters were scored. The most parsimonious hypotheses obtained in equally weighted total evidence analyses show the two most diverse families Ammotheidae and Callipallenidae to be non-monophyletic. Austrodecidae + Colossendeidae + Pycnogonidae are in the basal most clade, these are morphologically diverse groups of species mostly found in cold waters. The raising of the family Pallenopsidae is supported, while Eurycyde and Ascorhynchus are definitely separated from Ammotheidae. The four fossil taxa are grouped within living Pycnogonida, instead of being an early derived clade. This phylogeny represents a solid framework to work towards the understanding of pycnogonid systematics, providing a data set and a testable hypothesis that indicate those clades that need severe testing, especially some of the deep nodes of the pycnogonid tree and the relationships of ammotheid and callipallenid forms. The inclusion of more rare taxa and additional sources of evidence are necessary for a phylogenetic classification of the Pycnogonida. © The Willi Hennig Society 2006. [source] | ||||||||||||||||||||||