Top PDF The role of stochastic thermal environments in modulating the thermal physiology of an intertidal limpet, Lottia digitalis

The role of stochastic thermal environments in modulating the thermal physiology of an intertidal limpet, Lottia digitalis

The role of stochastic thermal environments in modulating the thermal physiology of an intertidal limpet, Lottia digitalis

in foot SOD levels. There was also no evidence of greater oxidative damage of proteins, in contrast to previous work that has shown that elevated temperatures increased levels of carbonlyated proteins in limpets (Han et al., 2013; Zhang et al., 2014). Intertidal animals tailor their cellular stress response mechanisms to be quickly initiated following the onset of high tide such that recovery is complete before the start of the next low tide period (Hofmann and Somero, 1996; Tomanek and Somero, 2000; Schill et al., 2002; Clark et al., 2008; Zhang et al., 2014). Transcriptomics of Mytilus californianus have also shown upregulated gene expression of recovery mechanisms, including antioxidants, to return to cellular homeostasis during the high tide period before the next low tide period (Gracey et al., 2008; Place et al., 2012). It may have been that the periods of immersion during high tide were sufficient to mitigate any acquired stress during the daytime low tide periods of the acclimation treatments by available antioxidants. We targeted four commonly examined biochemical indices of energy metabolism and oxidative stress; however, there are numerous other aspects of the cellular stress response to be explored (e.g. heat shock proteins) that may be primed to be constitutively expressed in response to acclimation to different heating patterns (Tomanek and Somero, 2002; Dong et al., 2008a,b). Furthermore, differences found in upper temperature tolerance may be due to differences in the capacity to induce cellular defense or protective mechanisms upon heating during low tide. Several studies have shown that intertidal organisms start producing cellular chaperones once heating begins (e.g. Tomanek and Somero, 2002; Huang et al., 2015). It has been previously shown that different limpet species all in the genus Lottia have unique strategies involving heat shock proteins (Dong et al., 2008b). For example, L. scabra maintains high levels of constitutive heat shock proteins whereas L. austrodigitalis, L. scutum and Journal
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Thermal physiology of the fingered limpet Lottia digitalis under emersion and immersion

Thermal physiology of the fingered limpet Lottia digitalis under emersion and immersion

enhanced stress tolerance on limpets. It has previously been shown that animals living higher in the intertidal zone and those living at lower latitudes have a higher thermal tolerance and breadth of performance over a wider temperature range than congeners living lower in the intertidal zone or at higher latitudes (Stillman and Somero, 1996; Chelazzi et al., 2001; Stillman, 2003; Stenseng et al., 2005; Braby and Somero, 2006; Dong and Williams, 2011; Logan et al., 2012). These findings provide support that an animal’s performance and tolerance limits typically reflect its natural habitat temperatures. It is perhaps not surprising that intertidal animals that are located high on the rocky shore and experience daily exposure to elevated temperatures during emersion have biochemical and physiological mechanisms in place that provide enhanced temperature tolerance under emersion compared with immersion. To date, there are limited studies that have investigated the thermal sensitivity of intertidal animals under conditions of emersion, the condition when they naturally experience the largest fluctuations in environmental temperature (but see Williams et al., 2005; Miller et al., 2009; Dong and Williams, 2011; Logan et al., 2012). In one study, the marbled rock crab, Pachygrapsus marmoratus, showed no difference in heart rate between emersion and immersion in response to increasing acute temperature exposures from 10 to 32.5°C (De Pirro et al., 1999). Unlike limpets that are sessile during a low tide period, crabs are mobile and can move to cooler, more shaded environments if environmental temperatures increase. Therefore, the need to have additional stress tolerance mechanisms during emersion may depend not only on location within the intertidal zone but also on the capacity to behaviorally thermoregulate.
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Biophysics, environmental stochasticity, and the evolution of thermal safety margins in intertidal limpets

Biophysics, environmental stochasticity, and the evolution of thermal safety margins in intertidal limpets

As the air temperature of the Earth rises, ecological relationships within a community might shift, in part due to differences in the thermal physiology of species. Prediction of these shifts – an urgent task for ecologists – will be complicated if thermal tolerance itself can rapidly evolve. Here, we employ a mechanistic approach to predict the potential for rapid evolution of thermal tolerance in the intertidal limpet Lottia gigantea. Using biophysical principles to predict body temperature as a function of the state of the environment, and an environmental bootstrap procedure to predict how the environment fluctuates through time, we create hypothetical time-series of limpet body temperatures, which are in turn used as a test platform for a mechanistic evolutionary model of thermal tolerance. Our simulations suggest that environmentally driven stochastic variation of L.  gigantea body temperature results in rapid evolution of a substantial ʻsafety marginʼ: the average lethal limit is 5–7°C above the average annual maximum temperature. This predicted safety margin approximately matches that found in nature, and once established is sufficient, in our simulations, to allow some limpet populations to survive a drastic, century-long increase in air temperature. By contrast, in the absence of environmental stochasticity, the safety margin is dramatically reduced. We suggest that the risk of exceeding the safety margin, rather than the absolute value of the safety margin, plays an underappreciated role in the evolution of thermal tolerance. Our predictions are based on a simple, hypothetical, allelic model that connects genetics to thermal physiology. To move beyond this simple model – and thereby potentially to predict differential evolution among populations and among species – will require significant advances in our ability to translate the details of thermal histories into physiological and population-genetic consequences.
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Footwear for cold environments Thermal properties, performance and testing

Footwear for cold environments Thermal properties, performance and testing

In mobile jobs in cold environments one has to deal with intensive sweating in feet due to work, as well as rapid cooling in times of inactivity resulting in dis- comfort feeling due to high humidity concentration in footwear. Standing jobs, e.g. meat cutting, involve cooling of the feet through intensive heat loss by con- duction and lower heat input from blood flow, especially if there is not much possibilities for feet motion and warming them up with exercise. With exercise it is possible to warm up the extremities or at least reduce the cooling, but none of those exercises used in the study by Rintamäki et al (Rintamäki et al., 1992) was able to warm up the toes. The exercise length should probably be longer than 10 minutes to affect the toe skin temperatures. An 8-hour long study (Rissanen et al., 1998) at -10 °C showed that the foot and toe temperatures increased during exercise (240 W/m 2
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Thermal sensation and comfort model for inhomogeneous indoor environments

Thermal sensation and comfort model for inhomogeneous indoor environments

3 Thermal sensation and comfort 3.1 Thermal sensation Gagge et al. [1967] point out the work of Roman philosopher Galen, who suggested adding a sense of heat and cold to the five traditional human senses, as the beginning of systematic research on thermal sensation. Defining sensation is far from being an easy task, however. Auliciems [1981] cites several researchers who pointed out that it is very difficult to define the meaning of sensa- tion without creating confusion. Bevan [1958], for example, claimed that the very word sensation should be eliminated from scientific usage altogether. Thermal sensation, he argued, was related to how people ’feel’ and would typically classify their thermal states using words such as warm, neutral, and cold. It is not possible, however, to define sensation in physical or physiological terms. As a consequence, many studies have tried to at least correlate physical conditions and physiolog- ical responses with thermal sensation. Parsons [2003] distinguishes between three different types of studies. Physiologists study thermoreceptor behaviour and attempt to relate this to thermal sen- sation. Studies in classical psychophysics investigate the relationship between physical intensity and psychological sensation, attempting to determine psychophysical laws. Designers and engi- neers consider whole-body thermal sensation as related to the thermal state of the body or parts of it. The latter approach has also been adopted in the present study. Thermoreceptors, already described in 2.3.1, serve as the combining element in this case.
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Thermal comfort in non-uniform environments: real-time coupled CFD and human thermal regulation modelling

Thermal comfort in non-uniform environments: real-time coupled CFD and human thermal regulation modelling

2.3.5 Dynamic thermal modelling Dynamic Thermal Modelling (DTM) is a technique often used to study the perfor- mance of buildings and that can be combined with CFD, as they provide complemen- tary information (Chen, 2009). A large variety of simulation software is available and used (Gandhi et al., 2014). As shown by Lomas et al. (2007), DTM can be used to predict the performance of a building over a period of time such as one year by comparing ventilation strategies or the impact of variable heat gains, and estimating likely energy consumption. However, DTM predicts overall space temperature, being not able to cope with spatially varying temperatures. This limitation may be partially overcome using some virtual partitions to split a space such a room into smaller por- tions. However, even with this method, DTM cannot reach the same level of spatial resolution of a CFD model. For instance, this approach can be useful to simply sep- arate the south- and north-facing parts of a large room. Similarly, also Zhang et al. (2013) coupled DTM and CFD to predict the performance of natural ventilation. However, air flow network models, which are used in DTM, underestimated air flow rates.
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Thermal comfort in urban green spaces in arid environments.

Thermal comfort in urban green spaces in arid environments.

El “confort térmico” es concebido como la ausencia de malestar con el ambiente térmico (ASHRAE, 2014). Para el estudio del confort en los EVU de la ciudad de San Juan, se aplica el índice racional UTCI (Universal Thermal Climatic Index) (Jendritzky, de Dear y Havenith, 2012) para espacios abiertos, basado en la valoración de la respuesta fisiológica de la persona. El UTCI define 10 escalas de estrés térmico, que abarcan desde el estrés por calor extremo al causado por mucho frío. La escala de valoración se presenta en la Tabla 1.

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Upper thermal limits of growth in brook trout and their relationship to stress physiology

Upper thermal limits of growth in brook trout and their relationship to stress physiology

of 6.5 – 20°C when compared with more moderate daily oscillations and constant temperature controls. However, redband trout subjected to 8°C oscillations of 8 – 16°C or 18 – 26°C did not exhibit elevated plasma cortisol levels (Cassinelli and Moffitt, 2010). It is also possible that there was an endocrine stress response induced during our growth study and that we missed the signal due to the timing of our sampling. In Atlantic salmon, plasma cortisol and glucose have been shown to return to baseline levels within hours following an acute crowding stressor (Carey and McCormick, 1998). In our growth study, we sampled fish in the morning when water temperatures had been below 21°C for at least 9 h, potentially giving them time to recover from any thermal stress experienced during the previous day. However, in our acute exposures we sampled after 1 h at peak temperatures and still did not observe elevated plasma cortisol or glucose, suggesting that these oscillating temperature treatments were not severe or long enough to induce an endocrine stress response. It is possible that plasma cortisol will only be elevated (or detectably different) when temperatures are high enough to induce severe and long-term reductions in food consumption and growth. It should also be noted that there are diurnal (circadian) rhythms in plasma cortisol in fish that are independent of temperature (Audet and Claireaux, 1992) that may have affected our ability to detect temperature impacts on cortisol. In addition to thermal impacts on brook trout growth and stress physiology we also explored the influence of elevated temperature on osmoregulation. Gill NKA activity (50%) and abundance (80%) decreased with temperature and were lowest at 24°C. The greater impact on abundance than activity suggests that the activity per unit molecule NKA is greater at elevated temperatures. Despite this, there were no differences in plasma Cl – levels in our temperature treatments, and no effect of oscillating temperature on gill NKA activity. Elevated temperature has been shown to reduce the length of the smolt window, as characterized by decreased gill NKA activity and seawater tolerance, in anadromous salmonids (McCormick et al., 1996, 1999), although this may be more related to temperature impacts on development than it is to temperature effects on osmoregulation per se. Similarly, elevated temperature also reduces survival and gill NKA activity in sockeye salmon during their spawning migration (Crossin et al., 2008). An inverse relationship between temperature and gill NKA activity has been observed in cod (Staurnes et al., 1994), halibut (Jonassen et al., 1999) and pupfish (Stuenkel and Hillyard, 1980), but not in turbot (Burel et al., 1996). It is plausible that changes in enzyme kinetics or alterations in behavior at elevated temperatures lessen the demand for both gill NKA activity and abundance, although more exploration in these areas is clearly needed.
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Predicting the physiological performance of ectotherms in fluctuating thermal environments

Predicting the physiological performance of ectotherms in fluctuating thermal environments

Physiological ecologists have long sought to understand the plasticity of organisms in environments that vary widely among years, seasons and even hours. This is now even more important because human-induced climate change is predicted to affect both the mean and variability of the thermal environment. Although environmental change occurs ubiquitously, relatively few researchers have studied the effects of fluctuating environments on the performance of developing organisms. Even fewer have tried to validate a framework for predicting performance in fluctuating environments. Here, we determined whether reaction norms based on performance at constant temperatures (18, 22, 26, 30 and 34°C) could be used to predict embryonic and larval performance of anurans at fluctuating temperatures (18–28°C and 18–34°C). Based on existing theory, we generated hypotheses about the effects of stress and acclimation on the predictability of performance in variable environments. Our empirical models poorly predicted the performance of striped marsh frogs (Limnodynastes peronii) at fluctuating temperatures, suggesting that extrapolation from studies conducted under artificial thermal conditions would lead to erroneous conclusions. During the majority of ontogenetic stages, growth and development in variable environments proceeded more rapidly than expected, suggesting that acute exposures to extreme temperatures enable greater performance than do chronic exposures. Consistent with theory, we predicted performance more accurately for the less variable thermal environment. Our results underscore the need to measure physiological performance under naturalistic thermal conditions when testing hypotheses about thermal plasticity or when parameterizing models of life-history evolution.
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Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

As mentioned before the hostile underground and underwater environments prevents the direct use of most, if not all, existing wireless communication and networking solutions, due to the extremely high path loss, small communication range, and high dynamics of EM waves when penetrating the different medium in the underground and underwater environment. This study aims at providing a detailed theoretical investigation and analytical model for wireless sensor networks used in the case of different media. This paper compared the channel characteristics of the EM waves in solid medium: soil in paper [2], coal in paper [3], oil sand in paper [4] and in liquid medium: water in paper [5], salty water in paper [5] and crude oil in paper [4] which are investigated specifically in the 315/433 MHz band.315/433 MHz band has been analyzed because of wireless nodes with the RF Transceiver TR1000 and CC1000 like MICA, MICA2, MICA2DOT, Cricket, MANTIS nymph motes can operate in the 315/433 MHz which can increase the efficient communication between sensor nodes comparing with 2.45 GHz. For this reason 315/433 MHz have been used in the analyses.
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Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

Our analysis is based on results obtained from building energy model simulations. Building energy modeling is the process of virtually recreating the physical building replicating all of its characteristics and by taking the climate into consideration. They provide valuable insights to designers and engineers on the behavior of the thermal loads in the buildings based on their architecture, operation type, internal activities and loads, and construction materials, and are often used to evaluate alternatives in building design. This study employs building energy simulations to study the impact of different building shapes, orientations and heights on the thermal loads in Office buildings.
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Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

This paper presents a method for approaching three dimensional models for n dimensional hypercubes through polar zonohedra, which – under certain conditions – constitute orthographic isometric projections of such hypercubes. The paper then goes on to present certain sections of the solids in question and the creation of tessellations on the plane. In order to design the zonohedra, use was made of the Rhino program, which combined with the Grasshopper routine allows for the parametric control of the geometric structure of the solid. In other words, it shows – through the proper manipulation of the design algorithm – how zonohedra are produced, constituting projections of higher dimensional hypercube spaces in three dimensional space. Subsequently, the sections of the zonohedra create planar tessellations on the planes, which change depending on how the n degree of the zonohedron changes. This results in a table that juxtaposes projections of hypercubes in three dimensional space and tessellations of a plane, some of which are already known, thus suggesting some sort of correlation between them. This study serves as a formulation of the architectural question surrounding the concept of the projection of polyhedra in general dimension on a plane and suggests an approach involving the parametric control of structures, thus bypassing – to a certain degree – the need for supervision. It also provides an answer to the general question regarding the contemporary role of geometry in the education of architects, which focuses mainly on the gradual detachment of the architect from the need to constantly monitor the produced form. The study presented in this paper is based on the post-doc research made by Nikos Kourniatis under the research funding program Thalis. Ioannis Emiris was the supervisor professor.
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Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

That is the reason for which a model was created (Fig. 7) which allows, firstly, the manual selection of 15 center-points (by typing the value range) from the attribute [r]

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Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

The proposal that has been developed for the adaptive reuse of Tenten factory is an answer to the question of ‘transforming a modern period industrial building to a sustainable and inno[r]

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Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

The World Health Organization (WHO) has no standard limit value for total dissolved solids however, the Nigerian Standard of Drinking Water (NSDW) permits a maximum of 500m[r]

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Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

Investigation of Thermal Environments in Humid Tropical Classroom in Indonesia

The second expert’s focus on language studies bridges the gap from where the first expert concludes(15th century ACE) to the present. Language studies use script in aspects such [r]

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Stochastic Analysis and Performance Evaluation of a Complex Thermal Power Plant

Stochastic Analysis and Performance Evaluation of a Complex Thermal Power Plant

Based on different assumptions, availability measures for a two-unit system with repair facility were obtained by several researchers. Rajamanickam et al. (1997) have assumed that the failure times and repair times for the components are independently distributed. Corder (1976) states that the raw material is processed through various equipment to get the final product in a process plant. The poor design, poor maintenance, lack of communication and coordination, defective planning, lack of skills and scarcity of inventories are main causes of failure. Thus highly skilled maintenance personnel are required to run a process plant. A thermal power plant is a complex engineering system comprising of various systems: Coal handling, Steam generators, Flue gas and air, Cooling water, Ash handling, Power Generation, Feed water and Condensate system connected either in series or in parallel or in combination of both (Arora and Kumar (1993) and Arora et al. (1995)). It is required to run the various subsystems of plant failure free for, a long period for maximum availability power generation. These subsystems are subjected to random failure and after repairs/replacement can be taken back into use. The operating conditions and repair policies used are the key factors for sub-systems and their components. The performance analysis can be used as tool to ensure the maximize level of system availability.
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Economic thermoregulatory response explains mismatch between thermal physiology and behaviour in newts

Economic thermoregulatory response explains mismatch between thermal physiology and behaviour in newts

with the optimal temperature for factorial AS in newts. Although the relationship between AS and fitness is considered problematic, it must be noted that previous estimates were largely based on measurements of maximum sustainable oxygen consumption during locomotion. The adaptive significance of AS for locomotion is disputable in taxa with low aerobic support for this activity, such as ambush predators (Fu et al., 2009; Clark et al., 2013). In this study, we estimated AS from specific dynamic action, which is a highly integrative measure of energetic demands for food processing and digestion (McCue, 2006; Secor, 2009). Because these processes are tightly linked to energy acquisition, the link of AS for digestion with individual fitness seems more straightforward than in previous cases. Because AS for digestion may not represent the maximum aerobic capacity, it may be argued that our results are confounded by ‘ saved ’ extra capacity for locomotion. Locomotion in digesting individuals increases AS in some species but not in others (Alsop and Wood, 1997; Bennett and Hicks, 2001; Thorarensen and Farrell, 2006). The priority of aerobic capacity for digestion over locomotion is especially evident in ambush foragers (Fu et al., 2009). Newts are known for their very low aerobic capacity for locomotion (Bennett and Licht, 1973; Harlow, 1978), which suggests that the contribution of aerobic locomotion to their AS will be minor. In addition, because aerobic demands for digestion and locomotion are covered by the same cardio-respiratory capacity, thermal dependence of AS should be identical for both activities. Hence, unmeasured AS for locomotion appears to have a negligible influence on the results of this study.
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The effects of different thermal environments on performance of manual handling tasks

The effects of different thermal environments on performance of manual handling tasks

The review of literature highlighted the fact that hydration status is rarely, if ever, assessed prior to manual handling studies in different thermal environments. It was important to ensure that the participants were euhydrated prior to testing as the exercise protocol and the hot environment would pose a twin challenge to thermoregulation. Hydration can be assessed by a number of methods, some more invasive than others (blood analysis for instance). A simple and acceptable method is the measurement of urine osmolality which is defined as the number of osmoles (Osm) of solute particles per kilogram of pure solvent (Chadha et al, 2001). The kidneys can dilute or concentrate urine depending on the body’s need to excrete or retain water (Shirreffs, 2000) so urine concentration can give an indication of hydration status. In a dehydrated person for example the kidneys will reduce urine production so the solute concentration will be higher. Most adult humans are capable of concentrating urine from 50 - 1400 mOsm.kg'1 and much debate exists as to the optimum range for euhydration. Shirreffs & Maughan (1998) have suggested that urine osmolality greater than 900 mOsm.kg*1 can be used as an indication of hypohydration. They have also recommended that a sample of the first urination of the day provides the best estimate. Obviously this would present a problem especially when test sessions were conducted later in the day. The 900 mOsm.kg'1 concentration was nevertheless adopted as an indicator of hypohydration and anyone presenting with a urine osmolality at this level or higher was asked to drink copiously for the 20-30 minutes prior to commencement of lifting.
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Understanding And Modelling Thermal Energy Demand And Emissions In Urban Environments

Understanding And Modelling Thermal Energy Demand And Emissions In Urban Environments

electricity and fossil fuel energy use, normalised to a unit floor area (kWh/m 2 per year). Sub- metering is not widely employed, so cooling energy benchmarks are very generally not identified separately. One of the most comprehensive sources of energy benchmarks is CIBSE Guide F (CIBSE, 2004). Chapter 20 of this guide details all of the known energy and component benchmarks (from all sources) at the time of publication. It includes both ‘typical’ and ‘good practice’ figures for fossil fuel and electricity consumption, for multiple building types, split by major categories such as: Catering; Entertainment; Education (‘higher’ and ‘schools’); Hospitals; Hotels; Industrial; Local Authority; Ministry of Defence; Offices; Primary Health Care; Public Buildings; Residential and Nursing Homes; Retail; Sports and Recreation. These are further split by specific building function (e.g. for Public Buildings: Churches; Courts; Libraries; Museums; Prisons etc.). Additional tables provide more detailed system and component benchmarks for specific building types, although many are based on data from a relatively small sample (<50). Table 5-14. shows the breakdown for a ‘standard’ air conditioned office (Type 3), which is typical of many offices built in the past 20-30 years. Both ‘Good Practice’ and ‘Typical’ data are given, indicating that the energy demand in ‘Good Practice’ buildings is around 50% of that for ‘Typical’ buildings. It should be noted that the cooling energy is reported in terms of the electrical energy required to drive the cooling system (primary energy input), so to estimate the thermal cooling energy delivered the electrical energy should be multiplied by the COP of the cooling system.
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