The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Shangping Xie - One of the best experts on this subject based on the ideXlab platform.
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recent global warming hiatus tied to equatorial pacific Surface Cooling
Nature, 2013Co-Authors: Yu Kosaka, Shangping XieAbstract:Global warming has stalled since the late 1990s, puzzling researchers; here a climate model that includes observed sea Surface temperatures in the eastern equatorial Pacific reproduces the hiatus as part of natural variation, suggesting that long-term global warming is likely to continue.
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recent global warming hiatus tied to equatorial pacific Surface Cooling
Nature, 2013Co-Authors: Yu Kosaka, Shangping XieAbstract:Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century, challenging the prevailing view that anthropogenic forcing causes climate warming. Various mechanisms have been proposed for this hiatus in global warming, but their relative importance has not been quantified, hampering observational estimates of climate sensitivity. Here we show that accounting for recent Cooling in the eastern equatorial Pacific reconciles climate simulations and observations. We present a novel method of uncovering mechanisms for global temperature change by prescribing, in addition to radiative forcing, the observed history of sea Surface temperature over the central to eastern tropical Pacific in a climate model. Although the Surface temperature prescription is limited to only 8.2% of the global Surface, our model reproduces the annual-mean global temperature remarkably well with correlation coefficient r = 0.97 for 1970-2012 (which includes the current hiatus and a period of accelerated global warming). Moreover, our simulation captures major seasonal and regional characteristics of the hiatus, including the intensified Walker circulation, the winter Cooling in northwestern North America and the prolonged drought in the southern USA. Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Nina-like decadal Cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas increase.
G Glover - One of the best experts on this subject based on the ideXlab platform.
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systematic review and meta analysis of intravascular temperature management vs Surface Cooling in comatose patients resuscitated from cardiac arrest
Resuscitation, 2020Co-Authors: Emily S Bartlett, Kjetil Sunde, G Glover, Fabio Silvio Taccone, Terence D Valenzuela, Ahamed H Idris, Nicolas Deye, Michael A Gillies, Alexander C Flint, Holger ThieleAbstract:Abstract Objective To systematically review the effectiveness and safety of intravascular temperature management (IVTM) versus Surface Cooling methods (SCM) for induced hypothermia (IH). Methods Systematic review and meta-analysis. English-language PubMed, Embase and the Cochrane Database of Systematic Reviews were searched on May 27, 2019. The quality of included observational studies was graded using the Newcastle-Ottawa Quality Assessment tool. The quality of included randomized trials was evaluated using the Cochrane Collaboration’s risk of bias tool. Random effects modeling was used to calculate risk differences for each outcome. Statistical heterogeneity and publication bias were assessed using standard methods. Eligibility Observational or randomized studies comparing survival and/or neurologic outcomes in adults aged 18 years or greater resuscitated from out-of-hospital cardiac arrest receiving IH via IVTM versus SCM were eligible for inclusion. Results In total, 12 studies met inclusion criteria. These enrolled 1,573 patients who received IVTM; and 4,008 who received SCM. Survival was 55.0% in the IVTM group and 51.2% in the SCM group [pooled risk difference 2% (95% CI -1%, 5%)]. Good neurological outcome was achieved in 40.9% in the IVTM and 29.5% in the Surface group [pooled risk difference 5% (95% CI 2%, 8%)]. There was a 6% (95% CI 11%, 2%) lower risk of arrhythmia with use of IVTM and 15% (95% CI 22%, 7%) decreased risk of overCooling with use of IVTM versus SCM. There was no significant difference in other evaluated adverse events between groups. Conclusions IVTM was associated with improved neurological outcomes vs. SCM among survivors resuscitated following cardiac arrest. These results may have implications for care of patients in the emergency department and intensive care settings after resuscitation from cardiac arrest.
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intravascular versus Surface Cooling for targeted temperature management after out of hospital cardiac arrest an analysis of the ttm trial data
Critical Care, 2016Co-Authors: G Glover, Richard M Thomas, George Vamvakas, Nawaf Alsubaie, Jules Cranshaw, Andrew Walden, Matt P Wise, Marlies Ostermann, Emma ThomasjonesAbstract:Targeted temperature management is recommended after out-of-hospital cardiac arrest and may be achieved using a variety of Cooling devices. This study was conducted to explore the performance and outcomes for intravascular versus Surface devices for targeted temperature management after out-of-hospital cardiac arrest. A retrospective analysis of data from the Targeted Temperature Management trial. N = 934. A total of 240 patients (26%) managed with intravascular versus 694 (74%) with Surface devices. Devices were assessed for speed and precision during the induction, maintenance and rewarming phases in addition to adverse events. All-cause mortality, as well as a composite of poor neurological function or death, as evaluated by the Cerebral Performance Category and modified Rankin scale were analysed. For patients managed at 33 °C there was no difference between intravascular and Surface groups in the median time taken to achieve target temperature (210 [interquartile range (IQR) 180] minutes vs. 240 [IQR 180] minutes, p = 0.58), maximum rate of Cooling (1.0 [0.7] vs. 1.0 [0.9] °C/hr, p = 0.44), the number of patients who reached target temperature (within 4 hours (65% vs. 60%, p = 0.30); or ever (100% vs. 97%, p = 0.47), or episodes of overCooling (8% vs. 34%, p = 0.15). In the maintenance phase, cumulative temperature deviation (median 3.2 [IQR 5.0] °C hr vs. 9.3 [IQR 8.0] °C hr, p = <0.001), number of patients ever out of range (57.0% vs. 91.5%, p = 0.006) and median time out of range (1 [IQR 4.0] hours vs. 8.0 [IQR 9.0] hours, p = <0.001) were all significantly greater in the Surface group although there was no difference in the occurrence of pyrexia. Adverse events were not different between intravascular and Surface groups. There was no statistically significant difference in mortality (intravascular 46.3% vs. Surface 50.0%; p = 0.32), Cerebral Performance Category scale 3–5 (49.0% vs. 54.3%; p = 0.18) or modified Rankin scale 4–6 (49.0% vs. 53.0%; p = 0.48). Intravascular and Surface Cooling was equally effective during induction of mild hypothermia. However, Surface Cooling was associated with less precision during the maintenance phase. There was no difference in adverse events, mortality or poor neurological outcomes between patients treated with intravascular and Surface Cooling devices. TTM trial ClinicalTrials.gov number https://clinicaltrials.gov/ct2/show/NCT01020916 NCT01020916; 25 November 2009
Craig G Crandall - One of the best experts on this subject based on the ideXlab platform.
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effect of thermal stress on frank starling relations in humans
The Journal of Physiology, 2009Co-Authors: Thad E Wilson, Craig G Crandall, Carsten Tollund, Ellen A Dawson, Peter Nissen, Chie C Yoshiga, Christian Jons, Niels H SecherAbstract:The Frank–Starling ‘law of the heart’ is implicated in certain types of orthostatic intolerance in humans. Environmental conditions have the capacity to modulate orthostatic tolerance, where heat stress decreases and Cooling increases orthostatic tolerance. The objective of this project was to test the hypothesis that heat stress augments and Cooling attenuates orthostatic-induced decreases in stroke volume (SV) via altering the operating position on a Frank–Starling curve. Pulmonary artery catheters were placed in 11 subjects for measures of pulmonary capillary wedge pressure (PCWP) and SV (thermodilution derived cardiac output/heart rate). Subjects experienced lower-body negative-pressure (LBNP) of 0, 15 and 30 mmHg during normothermia, skin-Surface Cooling (decrease in mean skin temperature of 4.3 ± 0.4°C (mean ±s.e.m.) via perfusing 16°C water through a tubed-lined suit), and whole-body heating (increase in blood temperature of 1.0 ± 0.1°C via perfusing 46°C water through the suit). SV was 123 ± 8, 121 ± 10, 131 ± 7 ml prior to LBNP, during normothermia, skin-Surface Cooling, and whole-body heating, respectfully (P= 0.20). LBNP of 30 mmHg induced greater decreases in SV during heating (−48.7 ± 6.7 ml) compared to normothermia (−33.2 ± 7.4 ml) and to Cooling (−10.3 ± 2.9 ml; all P < 0.05). Relating PCWP to SV indicated that Cooling values were located on the flatter portion of a Frank–Starling curve because of attenuated decreases in SV per decrease in PCWP. In contrast, heating values were located on the steeper portion of a Frank–Starling curve because of augmented decreases in SV per decrease in PCWP. These data suggest that a Frank–Starling mechanism may contribute to improvements in orthostatic tolerance during cold stress and orthostatic intolerance during heat stress.
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effect of skin Surface Cooling on central venous pressure during orthostatic challenge
American Journal of Physiology-heart and Circulatory Physiology, 2005Co-Authors: Jian Cui, Sylvain Durand, Benjamin D Levine, Craig G CrandallAbstract:Orthostatic stress leads to a reduction in central venous pressure (CVP), which is an index of cardiac preload. Skin Surface Cooling has been shown to improve orthostatic tolerance, although the me...
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skin Cooling maintains cerebral blood flow velocity and orthostatic tolerance during tilting in heated humans
Journal of Applied Physiology, 2002Co-Authors: Thad E Wilson, Rong Zhang, Sarah Witkowski, Craig G CrandallAbstract:Orthostatic tolerance is reduced in the heat-stressed human. The purpose of this project was to identify whether skin-Surface Cooling improves orthostatic tolerance. Nine subjects were exposed to 1...
Gregory J Offer - One of the best experts on this subject based on the ideXlab platform.
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the Surface cell Cooling coefficient a standard to define heat rejection from lithium ion battery pouch cells
Journal of The Electrochemical Society, 2020Co-Authors: Alastair Hales, Yatish Patel, Mohamed Waseem Marzook, Laura Bravo Diaz, Gregory J OfferAbstract:There is no universal and quantifiable standard to compare a given cell model's capability to reject heat. The consequence of this is suboptimal cell designs because cell manufacturers do not have a metric to optimise. The Cell Cooling Coefficient for pouch cell tab Cooling (CCC tabs ) defines a cell's capability to reject heat from its tabs. However, Surface Cooling remains the thermal management approach of choice for automotive and other high-power applications. This study introduces a Surface Cell Cooling Coefficient, CCC surf which is shown to be a fundamental property of a lithium-ion cell. CCC surf is found to be considerably larger than CCC tabs , and this is a trend anticipated for every pouch cell currently commercially available. However, Surface Cooling induces layer-to-layer nonuniformity which is strongly linked to reduced cell performance and reduced cell lifetime. Thus, the Cell Cooling Coefficient enables quantitative comparison of each Cooling method. Further, a method is presented for using the Cell Cooling Coefficients to inform the optimal design of a battery pack thermal management system. In this manner, implementation of the Cell Cooling Coefficient can transform the industry, by minimising the requirement for computationally expensive modelling or time consuming experiments in the early stages of battery-pack design.
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Surface Cooling causes accelerated degradation compared to tab Cooling for lithium ion pouch cells
Journal of The Electrochemical Society, 2016Co-Authors: Ian Hunt, Yan Zhao, Yatish Patel, Gregory J OfferAbstract:One of the biggest causes of degradation in lithium-ion batteries is elevated temperature. In this study we explored the effects of cell Surface Cooling and cell tab Cooling, reproducing two typical Cooling systems that are used in real-world battery packs. For new cells using slow-rate standardized testing, very little difference in capacity was seen. However, at higher rates, discharging the cell in just 10 minutes, Surface Cooling led to a loss of useable capacity of 9.2% compared to 1.2% for cell tab Cooling. After cycling the cells for 1,000 times, Surface Cooling resulted in a rate of loss of useable capacity under load three times higher than cell tab Cooling. We show that this is due to thermal gradients being perpendicular to the layers for Surface Cooling leading to higher local currents and faster degradation, but in-plane with the layers for tab Cooling leading to more homogenous behavior. Understanding how thermal management systems interact with the operation of batteries is therefore critical in extending their performance. For automotive applications where 80% capacity is considered end-of-life, using tab Cooling rather than Surface Cooling would therefore be equivalent to extending the lifetime of a pack by 3 times, or reducing the lifetime cost by 66%.
Kjetil Sunde - One of the best experts on this subject based on the ideXlab platform.
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systematic review and meta analysis of intravascular temperature management vs Surface Cooling in comatose patients resuscitated from cardiac arrest
Resuscitation, 2020Co-Authors: Emily S Bartlett, Kjetil Sunde, G Glover, Fabio Silvio Taccone, Terence D Valenzuela, Ahamed H Idris, Nicolas Deye, Michael A Gillies, Alexander C Flint, Holger ThieleAbstract:Abstract Objective To systematically review the effectiveness and safety of intravascular temperature management (IVTM) versus Surface Cooling methods (SCM) for induced hypothermia (IH). Methods Systematic review and meta-analysis. English-language PubMed, Embase and the Cochrane Database of Systematic Reviews were searched on May 27, 2019. The quality of included observational studies was graded using the Newcastle-Ottawa Quality Assessment tool. The quality of included randomized trials was evaluated using the Cochrane Collaboration’s risk of bias tool. Random effects modeling was used to calculate risk differences for each outcome. Statistical heterogeneity and publication bias were assessed using standard methods. Eligibility Observational or randomized studies comparing survival and/or neurologic outcomes in adults aged 18 years or greater resuscitated from out-of-hospital cardiac arrest receiving IH via IVTM versus SCM were eligible for inclusion. Results In total, 12 studies met inclusion criteria. These enrolled 1,573 patients who received IVTM; and 4,008 who received SCM. Survival was 55.0% in the IVTM group and 51.2% in the SCM group [pooled risk difference 2% (95% CI -1%, 5%)]. Good neurological outcome was achieved in 40.9% in the IVTM and 29.5% in the Surface group [pooled risk difference 5% (95% CI 2%, 8%)]. There was a 6% (95% CI 11%, 2%) lower risk of arrhythmia with use of IVTM and 15% (95% CI 22%, 7%) decreased risk of overCooling with use of IVTM versus SCM. There was no significant difference in other evaluated adverse events between groups. Conclusions IVTM was associated with improved neurological outcomes vs. SCM among survivors resuscitated following cardiac arrest. These results may have implications for care of patients in the emergency department and intensive care settings after resuscitation from cardiac arrest.
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a comparison of intravascular and Surface Cooling techniques in comatose cardiac arrest survivors
Critical Care Medicine, 2011Co-Authors: Oystein Tomte, Tomas Draegni, Arild Mangschau, Dag Jacobsen, Bjorn Auestad, Kjetil SundeAbstract:nduction of mild therapeutic hy-pothermia (MTH) to reduce sec-ondary reperfusion brain injury incomatose patients is one of fewproven in-hospital treatment strategiesfor out-of-hospital cardiac arrest (OHCA)(1, 2). Although MTH can be induced andmaintained with basic means such as icepacks, cold air blankets, or infusion ofcold fluids (2, 3), numerous advancedsystems have been developed with theintention of achieving faster inductionand more reliable temperature mainte-nance (4, 5). These systems rely on twodistinct approaches to whole-body cool-ing, either Surface Cooling of the patients’skin or core Cooling with an endovascularcatheter. The clinical effect of choosingeither Surface Cooling or core Cooling isuncertain, because most studies havecompared modern Cooling devices to noor only basic Cooling, such as cold airblankets or ice packs (4).Our hospital uses either an advancedendovascular core Cooling device (Cool-gard; ZOLL Medical Corporation,Chelmsford, MA ) or an advanced SurfaceCooling device (Arctic Sun; Medivance,Louisville, CO) as part of a previouslydescribed standard operating procedurefor all OHCA patients (6). These devicesare fairly comparable in terms of Coolingeffectiveness and automatic temperaturefeedback control (4). Based on prospec-tively collected data from all comatoseOHCA patients treated and nonrandom-izedatourinstitutionwitheitherofthesetwo devices, we compared core and sur-face Cooling with a zero-effect hypothesisof equal Cooling effectiveness and patientoutcomes. To our knowledge, this is thefirst study comparing these two fre-quently used devices related to outcome,complications, and other physiologic andmetabolic effects.