Effect Of Thermal Adaptation Research Articles

Stronger compensatory thermal adaptation of soil microbial respiration with higher substrate availability.

Ongoing global warming is expected to augment soil respiration by increasing the microbial activity, driving self-reinforcing feedback to climate change. However, the compensatory thermal adaptation of soil microorganisms and substrate depletion may weaken the effects of rising temperature on soil respiration. To test this hypothesis, we collected soils along a large-scale forest transect in eastern China spanning a natural temperature gradient, and we incubated the soils at different temperatures with or without substrate addition. We combined the exponential thermal response function and a data-driven model to study the interaction effect of thermal adaptation and substrate availability on microbial respiration and compared our results to those from two additional continental and global independent datasets. Modeled results suggested that the effect of thermal adaptation on microbial respiration was greater in areas with higher mean annual temperatures, which is consistent with the compensatory response to warming. In addition, the effect of thermal adaptation on microbial respiration was greater under substrate addition than under substrate depletion, which was also true for the independent datasets reanalyzed using our approach. Our results indicate that thermal adaptation in warmer regions could exert a more pronounced negative impact on microbial respiration when the substrate availability is abundant. These findings improve the body of knowledge on how substrate availability influences the soil microbial community-temperature interactions, which could improve estimates of projected soil carbon losses to the atmosphere through respiration.

Outdoor thermal perception and heatwave adaptation effects in summer – A case study of a humid subtropical city in China

Heatwaves occur more frequently during the summer owing to global warming, which causes excessive heat stress and thermal discomfort. Heat stress increases overheating risk and impacts people's health and outdoor activities. Assessing outdoor thermal risk and clarifying human thermal responses under outdoor high-temperature conditions are of particular importance. However, the effect of thermal adaptation on people's thermal perception during heatwave conditions requires exploration. This paper aims to provide a comprehensive analysis of human outdoor thermal perception under non-heatwave and heatwave conditions to obtain adaptation-based outdoor thermal benchmarks to estimate the threshold for thermal discomfort and heat stress. Longitudinal and cross-sectional questionnaire surveys are carried out during the summer in public squares in Chongqing. The results showed that thermal perceptions undergo a dynamic change process in summer, which is closely related to an individual's past thermal experience. In comparison with thermal benchmarks under non-heatwave conditions, the neutral, comfortable, and 80% acceptable range of UTCI under heatwave conditions shifted to a higher temperature. For the heatwave period, the neutral UTCI range was from 21.5 °C to 27.9 °C. The modified UTCI ranges for heat stress classifications were obtained, including the 80% acceptable temperature range from 21.4 °C to 30.1 °C. The contributions of this study are in the method of determining outdoor thermal benchmarks in heatwave conditions and clarifying local people's thermal demands. These findings can provide more refined guidance for heat stress assessment and enrich the possibilities for urban design and urban resilience responses to heatwave conditions.

Evaluation of the accuracy of PMV and its several revised models using the Chinese thermal comfort Database

The predicted mean vote (PMV) and its several revised models are widely used for the prediction of thermal comfort. This study aims to assess their performances using the Chinese Thermal Comfort Database (N = 41977). In air-conditioned buildings, the PMV prediction accuracy (P) and the mean absolute error (MAE) are 41.2 % and 0.86, respectively, which is better than the performance in free-running buildings (P = 31.9 %, MAE = 1.09). The performance of the PMV model is also tested under different HVAC modes, climate zones, and building types. The prediction accuracy varies but does not exceed 60 % for all subset cases. Three typical revised models (ePMV, nPMV and aPMV) considering thermal adaptation show better accuracy than the PMV, but the improvements are still limited and do not exceed 5 %. It appears that the PMV and revised models are reliable under thermal neutrality conditions, while their accuracy decreased towards the ends of the thermal sensation scale, especially on the cooler side. For further improvement of the prediction performance, it may be necessary to consider the effect of thermal adaptation in parallel with other approaches, such as revising the PMV core structure and considering individual differences.

Thermal adaptation in occupant-driven HVAC control

Personal Comfort Models (PCM) build on state-of-the-art methods to predict individuals’ thermal comfort responses based on occupant input and indoor environment measurements. Such models use machine learning and internet of things (IoT) to learn personal comfort requirements and integrate them into control systems for indoor environments. However, it is a challenging task to have consistent feedback from individuals, which is normally obtained from thermal comfort surveys. In this study, a PCM approach was tested, where the effects of thermal adaptation on occupants’ thermal responses were analysed. Nine occupants participated during a three-week field study. Thermal preferences were learned by a framework grounded on fuzzy logic used to calculate a set point implemented in the HVAC control system of an open-plan office. The results show that only 29% of the occupants’ thermal comfort improved and decreased on 71% of them, when implementing the user-driven control strategy. The performance of the demand-driven control strategy was mainly influenced by insufficient and poorly distributed data, as well as the effect of thermal expectations on occupants’ thermal responses. These were affected by the better opportunities of behavioural adjustment offered by the participatory sensing approach as well as of their experience with the prevailing outdoor environment. The findings indicate that implementing demand-driven control grounded on user feedback should consider constant data renovation, accurate measurements of local indoor climate and occupants’ thermal expectation.

Effect of building envelope on thermal environmental conditions of a naturally ventilated building block in tropical climate

This article presents the effect of envelope measures on thermal environmental conditions of a naturally ventilated building block in composite climate of India. Envelope measures such as roof U-value, wall U-value, glass U-value and glass solar heat gain coefficient, roof reflectance and two combinations of these measures (total seven cases) are analysed as recommended by National Energy Conservation Building Code-India (ECBC) through prescriptive route. Subject building is modelled and simulated using dynamic thermal simulation tool. Two approaches of thermal comfort have been used in this study such as heat balance model based on laboratory study and adaptive model of thermal comfort based on field findings. Thermal environmental conditions are evaluated based on operative temperature with and without considering the effect of thermal adaptation. This study found that comfortable temperature varies from 20.3℃ to 31.5℃ based on calculation of comfortable temperature through comfort temperature equation during winter to summer season in warm climatic conditions. This study concludes that envelope with ECBC specifications offer 60% hours under comfort state which were not comfortable with conventional practiced envelope specifications of India. The same methodology is also used to investigate the effect of ECBC envelope specifications in other climatic conditions such as hot and dry, and warm and humid climate of India. Practical applications: The thermal performance of building envelope varies from climate to climate therefore care should be taken to choose particular envelope measure. This study aims to improve comfort conditions in naturally ventilated building block considering building code with/without thermal adaptation. This research would be helpful to architects, engineers and building constructors to choose the most effective or climate responsive envelope option for better thermal environment quality of the proposed building design. Use of thermal simulation tool is also recommended to examine the effect of envelope options on thermal comfort.

A note on the special fillet fatty acid composition of the dwarf carp(cyprinus carpio carpio)living in thermal Lake Hévíz, Hungary

Fatty acid (FA) composition of the fillet and the intestinal content of dwarf common carp (Cyprinus carpio carpio) living in Lake Hévíz was determined in wintertime collected samples and results were compared to widespread literature data on carp. Fillet FA profile of the thermally adapted (28 °C) Hévíz dwarf carps differed from profiles originated from divergent culture and feeding conditions in the overall level of saturation. Fillet myristic acid proportions largely exceeded all literature data in spite of poor dietary supply. Fillet fatty acid results indicate the effects of thermal adaptation (high saturation level) and the correlative effects of feed components rich in omega-3 fatty acids, with special respect to docosahexaenoic acid. With the application of discriminant factor analysis the Hévíz sample was accurately differentiated from the literature data on carp fillet fatty acid profile, mostly based on C14:0, C18:1 n9, C18:2 n6, C20:1 n9 and C20:4 n6 FAs. In summary, fillet FA profile suggested thermal adaptation, location specificity and the ingestion of algal and bacterial material.

Combined effect of energy efficiency measures and thermal adaptation on air conditioned building in warm climatic conditions of India

This study evaluates improvement in energy efficiency of an air conditioned building block employing energy conservation measures (ECMs) recommended by Indian Energy Conservation Building Code 2007 (ECBC) through a prescriptive route. First part evaluates energy savings by implementing five ECMs of envelope independently and two combinations of ECMs keeping constant thermostat setting throughout the year. In the second part of the study same ECMs are considered to the subject building model allowing thermostat settings as per thermal adaptation resulting from change in outdoor temperature. Actual measurements were taken and simulation model was fine-tuned. Annual energy consumption of building is used to evaluate the effect of individual ECMs and their combinations on both part of the study, i.e. fixed thermostat and adaptive thermostat settings. The simulation result shows that together with combination of all ECMs recommended by ECBC, small buildings can save up to 40% energy consumption as compared to buildings built with conventionally practised specifications of India. Effect of thermal adaptation itself offers up to 16% energy saving opportunity in small buildings considering adaptive thermostat settings. The potential of energy conservation through ECMs suggested by ECBC and adaptive set point gets significantly reduced for large size buildings having high internal heat gains.

Thermal adaptation activates HSP70 synthesis, inhibits overproduction of nitric oxide, and protects the body from acute hypotension during heat shock

The role of HSP70 and nitric oxide in antihypotensive effects of thermal adaptation was studied. Western blot analysis and electron paramagnetic resonance were used to determine the contents of HSP70 and nitric oxide. Protective effect of adaptation was evaluated by the limitation of blood pressure drop after heat shock. The formation of protective effects, accumulation of HSP70, and development of the ability to decrease nitric oxide overproduction had similar dynamic patterns and appeared at the same period. Quercetin, an inhibitor of HSP70 synthesis, prevented the development of protective effects. The data suggest that HSP70 accumulated during adaptation prevents heat shock-induced hypotension by restricting NO over-production and interfering with its cytotoxic effects.

The effect of thermal adaptation on the level of nitrogenous excretion of Channa punctatus (bloch)

The rates of ammonia-N and urea-N excretion have been measured in summer- winter-adapted Channa punctatus, a representative of an Indian freshwater air-breathing teleost. The season-specific difference in these rates have been analyzed with respect to thermal adaptation during the variation of seasonal temperature of summer and winter months. Due to cold adaptation (either in nature's laboratory or a man made laboratory) the rates of ammonia-N and urea-N excretion are decreased, suggesting a lesser mobilization-N excretion during warm adaptation (either summer acclimation or 32°C acclimation) are noticed, suggesting a greater mobilization of protein and ureogenesis.

Relation between membrane phospholipid composition, fluidity and function in mitochondria of rat brown adipose tissue. Effect of thermal adaptation and essential fatty acid deficiency

Male weanling rats were maintained either at 28° C (thermoneutrality) or at 5° C (cold adaptation). During 9 weeks they were fed either a 2% hydrogenated coconut oil diet deficient in essential fatty acids or a diet containing 2% sunflower oil. The respective incidences of cold adaptation and of EFA deficiency on lipid composition of mitochondrial membranes from brown adipose tissue (BAT) were investigated. Using 1,6 diphenylhexatriene (DPH) as a probe, the parameters of membrane fluidity were estimated by steady-state fluorescence polarization measurements ( r s ) and by time-resolved fluorescence anisotropy decay (order parameter S). Cold acclimation induced a decrease of phosphatidylcholine to phosphatidylethanolamine (PC/PE ratio), an increase of the total fatty acid unsaturation index (T.U.). EFA deficiency had the same effect as cold on the PC/PE ratio, but decreased T.U. Cold adaptation induced a larger decrease of S than of r s , whereas EFA deficiency only increased r s and did not modify S. In liposomes prepared from mitochondrial lipids, r s values were smaller than in whole mitochondria. Both in cold-adapted and in EFA-deficient rats the variations of r s were correlated with lipid unsaturation. Comparison between BAT thermogenic activity, assessed by GDP binding and proportions of PE and PC showed a high correlation suggesting a change in the membrane occurring with the increase of mitochondrial activity that could be related to phospholipid composition rather than to membrane fluidity.

The effect of thermal adaptation on the phase-properties of the membrane lipids of Anacystis nidulans

The effect of thermal adaptation on the phase-properties of the membrane lipids of <i>Anacystis nidulans</i>