Dissertations / Theses on the topic 'Human Heat Balance Models'

This thesis presents a series of studies into the responses of people to outdoor thermal conditions experienced over all seasons in the United Kingdom. The aim was to investigate practical methods for predicting human responses to outside weather conditions, which would be useful in predicting effects on human comfort and health. The studies involved both laboratory experiments and field trials. One particular aspect of outside conditions, not usually investigated in laboratory studies, is the contribution of solar radiation. Single subject and thermal manikin studies were used to determine the contribution of solar radiation to human response. In addition to this, a total of 168 subjects responses were recorded during trials at the Loughborough University weather station compound. (latitude 52.47N and longitude 01.11W). The trials were distributed between July 2007 and October 2008. This provided a comprehensive data-base for the evaluation of thermal indices. The thesis is divided into four parts. Part one provides an introduction to the subject and a comprehensive literature review. It also describes equipment, calibration procedures and methods used. Part two quantified the contribution of solar radiation to the heat load on a person. A human subject and a heated thermal manikin were exposed to outdoor thermal conditions, while in light clothing and (for the person) conducting a step test. They were then exposed to identical conditions in a thermal chamber, but without the contribution of the sun. The conditions outside were 23˚C air temperature, 42˚C mean radiant temperature and 54% relative humidity with an average air velocity of 0.75 ms-1. The difference in sweat rate (person) and heat required (manikin) between outdoor and indoor conditions were used to estimate the contribution of the sun. Using three different analyses estimates were 14 Wm-2, 35 Wm-2 and 50 Wm-2 depending upon the assumptions made. Part three describes current thermal indices that can be used to assess the effects of weather conditions on people. It also presents the results of weather station measurements over the time period considered. In chapters 8 and 9 field trials are described which capture both the thermal conditions and human physiological and subjective responses to those conditions. Chapter 10 uses the data collected to provide an evaluation of current thermal indices for predicting human responses. The range of air temperature and relative humidity (at 2 pm) over a year was -2˚C to 29˚C and 34% to 95% respectively. Wind speed varied and was greater in winter and spring than in summer and autumn. Solar radiation was influenced by the altitude of the sun which depended upon season. Mean solar radiation increased from December to June and decreased from June to December. The subjective and physiological responses for 130 people (65 males and 65 females) over a range of outdoor weather conditions are presented. Physiological responses for females generally showed a stronger relationship with environmental variables and subjective responses than those for males. The subjective and physiological responses of four groups (one in each season of the year - involving a total of 38 people), are presented. It was found that there were significant individual differences in response. Part four provides a suggestion for an improved thermal index. The PMV (Predicted Mean Vote) out of four thermal indices (WBGT, PMV, WCI/tch and Twc) had the strongest relationship with environmental variables and physiological responses but had a weak relationship with subjective responses. A PMVoutdoors index was developed to improve the prediction of subjective responses for the outdoor conditions investigated. Conclusions and recommendations for future research are provided.

Purpose: In most thermoregulatory research, participants are asked to abstain from consuming caffeine prior to experimental trials due to an assumed confounding effect on core temperature, skin blood flow and/or sweating responses. Yet, evidence supporting this notion appears inconclusive. We aimed to rigorously assess the impact of acute caffeine ingestion on thermoregulatory responses to steady-state exercise in the moderate heat in both caffeine-habituated and non-habituated individuals. Methods: A total of 28 participants (Habituated (HAB), n=14, 4 women; Non-Habituated (NHAB), n=14, 6 women) cycled at a fixed metabolic heat production on two separate occasions: 60 minutes after ingesting i) 5 mg·kg-1 caffeine (CAF) or ii) 5 mg·kg-1 maltodextrin placebo (PLA), in a double-blinded randomised and counter-balanced order. Environmental conditions were 30.6±0.9°C, 31±1 % RH. Results: The rise in esophageal temperature from baseline (ΔTes) with CAF was greater in the HAB group (P<0.001), but not the NHAB group (P=0.34) (CAFHAB interaction: P=0.001). Skin blood flow responses on the arm and the back were attenuated with CAF in the HAB group (CAFHAB interaction: P<0.05) but not in the NHAB group (CAFHAB interaction: Arm: P>0.05). WBSL was not between CAF and PLA (P=0.18). Conclusion: A greater ΔTes with CAF was observed in the HAB group but not the NHAB group, possibly due to an attenuated skin blood flow on the forearm and back with CAF compared to PLA in the HAB group only. These findings support the practice of requesting habituated caffeine-users to abstain from all sources of caffeine prior to participating in thermoregulatory research studies. However, the restriction of caffeine intake for non-habituated individuals (from incidental sources, e.g. chocolate, tea etc) seems unnecessary.

Periciliary liquid (PCL) is a critical component of the respiratory system for maintaining mucus clearance. As PCL homeostasis is affected by evaporation and mechanical forces, which are in turn affected by various breathing conditions, lung morphology and ventilation distribution, the complex process of PCL depth regulation in vivo is not fully understood. We propose an integrative approach to couple a thermo-fluid computational fluid dynamics (CFD) model with an epithelial cell model to study the dynamics of PCL depth using subject-specific human airway models based on multi-detector row computed-tomography (MDCT) volumetric lung images. The thermo-fluid CFD model solves three-dimensional (3D) incompressible Navier-Stokes and transport equations for temperature and water vapor concentration with a realistic energy flux based boundary condition imposed at airway wall. A corresponding one-dimensional (1D) thermo-fluid CFD model is also developed to provide necessary information to the 3D model. Both 1D and 3D models are validated with experimental measurements, and the temperature and humidity distributions in the airways are investigated. Correlations for the dimensionless parameters of Nusselt number and Sherwood number are proposed for characterizing heat and mass transfer in the airways. As one of the key applications of the thermo-fluid CFD model, the water loss rates in the both 1D and 3D airway models are studied. It is found that the secondary flows formed at the bifurcations elevate the regional heat and mass transfer during inspiration and hence the water loss rate, which can only be observed in the 3D models. Among the three human airway models studied in both 1D and 3D, little inter-subject variability is observed for the distributions of temperature and humidity. However, the inter-subject variability could be dramatic for the distribution of water loss rate, as it is greatly affected by airway diameter and regional ventilation. A method is proposed to construct an ion-channel conductance model for both normal and cystic fibrosis (CF) epithelial cells, which couples an existing fluid secretion model with an existing nucleotide and nucleoside metabolism model (collectively named epithelial cell model). The epithelial cell models for both normal and CF are capable of predicting PCL depth based on mechanical stresses and evaporation, and are validated with a wide range of experimental data. With these two models separately validated and tested, the integrated model of the thermo-fluid CFD model and epithelial cell model is applied to MDCT-based human airway models of three CF subjects and three normal subjects to study and compare PCL depth regulation under regular breathing conditions. It is found that evaporative water loss is the dominant factor in PCL homeostasis. Between three types of mechanical forces, cyclic shear stress is the primary factor that triggers ATP release and increases PCL depth. In addition, it is found that that greater diameters of the airways in the 4th-7th generations in CF subjects decrease evaporative water loss, resulting in similar PCL depth as normal subjects. Under regular breathing conditions, the average PCL depths of normal and CF is around 6 to 7 µm, with mechanical forces play a greater role in regulating CF PCL depth. Comparing to 7.68 µm normal base level (considered as optimum PCL depth), this average PCL depth is about 8 to 21% lower. This might suggest that mechanical forces alone cannot entirely balance evaporative water loss, and other mechanisms might be involved.

Les lésions cérébrales traumatiques (LCT) restent un défi de santé publique de nos jours car celles-ci touchent plus de cinquante millions de personnes dans le monde par an. Leur prise en charge nécessite généralement des soins de longue durée et ceci engendre malheureusement des dépenses financières importantes estimées à plus de 400 millions de dollars US par an. Les LCT font partie des plus complexes traumatismes affectant le cerveau humain. Dans les cas chroniques par exemple, l’une des complications des LCT est la persistance de la neuroinflammation qui conduit inévitablement à une dégénérescence neuronale et à un déficit cognitif. Malheureusement, les stratégies d'intervention se heurtent encore à plusieurs obstacles malgré les progrès technologiques actuels. Des efforts sont faits pour arrêter ce « tueur silencieux », mais jusqu'à nos jours, aucune stratégie ne s’est avérée efficace contre les perturbations physiologiques à long terme des LCT.De nos jours, il apparaît de plus en plus clairement que le lysat plaquettaire contient une pléthore de molécules actives pouvant exercer des activités neuroprotectrices. Ce produit neuroprotecteur naturel pourrait donc être bénéfique dans le traitement des maladies neurodégénératives comme l’ont montré des études antérieures avec des modèles expérimentaux d’accidents vasculaires cérébraux, de sclérose latérale amyotrophique et de la maladie de Parkinson.Nous avons émis l'hypothèse que l’injection de ce lysat plaquettaire dans une zone lésée du cerveau favoriserait la cicatrisation et réduirait la mort neuronale.Notre projet avait donc pour but de développer une approche innovante pour le traitement de la lésion traumatique cérébrale. Nous visions à donner la preuve du concept de l'intérêt d’utiliser le lysat chauffé de plaquettes humaines (HPPL) comme agent neuroprotecteur.Du HPPL a été préparé à partir de concentrés plaquettaires non viro-inactivés et viro-inactivés selon une procédure préalablement établie. L’impact sur la viabilité des cellules, l’absence d’activité pro-inflammatoire, le potentiel de stimuler la cicatrisation du HPPL ont été évalué à l'aide de modèles cellulaires pertinents. L’activité d’inhibition de la ferroptose par le HPPL a été aussi investiguée en utilisant des cellules de LUHMES et des cultures primaires de neurones. En fin, des modèles de LCT de souris ont été utilisés pour évaluer le potentiel « neuro-restaurateur » du HPPL. Nous avons ciblé ici son impact sur la fonction motrice, la neuroinflammation, le stress oxydatif et la perte synaptique. Des tests de comportement, d'expression de gènes, d’histologie, d'ELISA, de Western blot et d’analyse protéomique ont été utilisés au cours de cette étude.L'étude in vitro a révélé que les HPPL contiennent une pléthore de molécules bioactives qui sont non-toxiques pour les cellules, ni n’induisent de stress aux cellules traitées. Bien plus, les HPPL n'ont pas exercé d’impact négatif sur l'expression des protéines synaptiques et neuronales, et ont conservé leur potentiel « anti-ferroptose ». L'administration du HPPL à des souris ayant des LCT, a amélioré leur fonction motrice, atténué l'inflammation et le stress oxydatif et réduit la perte synaptique.En résume, le HPPL/I-HPPL possède une activité neuroprotectrice révélée à travers les essais in vitro. In vivo, il a réussi à inverser le déficit moteur, moduler l’activation des cellules gliales et le stress oxydatif provoqués par la LCT induite aux souris
Traumatic brain injury (TBI) remains a global health challenge nowadays, impacting over 50 million people per year globally. This situation is partly linked to the fact that TBI is among the central nervous system disorders whose management mostly requires long-term care. It incurs a substantial economic burden to health systems and costing the global economy more than $400 million. In either high, middle, or low-income countries, TBI is associated with significant economic and societal changes that deserve attention. The disease is described as one of the most complexes, inducing some disproportionate effects between the countries. Unfortunately, the intervention strategies are still facing several limitations at the global level despite all the health sciences’ progress. These obstacles are the surge of neuroinflammation, leading to progressive neuronal degeneration and cognitive deficit. Efforts are made to stop this “silent killer”, but there is a failure to manage the long-term burden of TBI efficiently until now.Nowadays, there is growing evidence that platelet lysates are full of bioactive compounds, and they could constitute a powerful natural neuroprotective agent. Few studies have already shown their therapeutic potential in stroke, amyotrophic lateral sclerosis, and Parkinson's disease. Thus, we hypothesized that the delivery of human platelet lysate at an injured area in the brain could provide a suitable environment for recovery.The current project is intending to develop an innovative approach for the treatment of TBI. We aim to give the proof-of-concept of the interest of using heat-treated human platelet pellet lysate (HPPL) as a neuroprotective agent in TBI using experimental models.We used cells and animal models of TBI to achieve our goal. We first prepared HPPL from non-pathogen-reduced platelet concentrates (PCs) and pathogen-inactivated PCs (I-HPPL) according to a previously established procedure. We evaluated their safety and functionality using cell models relevant to TBI, including viability assays, wound healing, anti-inflammatory activity, protein expressions, and anti-ferroptosis effect. The safety assessment of the platelet biomaterial was done using neuronal and endothelial cells and its neuroprotective potential with primary neurons, dopaminergic cells line and, a ferroptosis inducer.Mouse TBI models were used to assess the therapeutic potential of HPPL. We targeted it impact on motor function, neuroinflammation, oxidative stress, and synaptic loss. Behavior tests, gene expression, fluorescent staining, ELISA, Western blot, and proteomics have been used during the investigation. The in vitro experiment performed to investigate the platelet lysate’s safety demonstrated clearly that HPPL/I-HPPL contain bioactive molecules and did not affect cell’s viability or induced stress. Moreover, HPPL and I-HPPL did not affect synaptic and neuronal protein expression and revealed anti-ferroptosis potential. This finding leads to further investigation of HPPL's beneficial effect in vivo. HPPL administration to TBI mice improved their motor function, mitigated the inflammation and oxidative stress. HPPL also decreased the synaptic proteins lost.HPPL is safe and exerted neuroprotective activity in vitro. It successfully reversed the motor deficit, inflammation, and stress triggered by brain injury in mice

The energy exchange in the soil-snow-vegetation-atmospheresystem was studied to improve the quantitative knowledge of thegoverning processes. The lack of such knowledge contributes tothe uncertainty in the applicability of many existing modelsindependent of the temporal or spatial scale. The theoreticalbackground and available methods for measurements and numericalsimulations were reviewed. Numerical simulation models andavailable data sets representing open land and boreal forestwere evaluated in both diurnal and seasonal time-scales.Surface heat fluxes, snow depth, soil temperatures andmeteorological conditions were measured at an agriculturalfield in central Sweden over two winters, 1997-1999. Twoone-dimensional simulation models of different complexity wereused to simulate the heat and water transfer in thesoil-snow-atmosphere system and compared with the measurements.Comparison of simulated and observed heat fluxes showed thatparameter values governing the upper boundary condition weremore important than the formulation of the internal mass andheat balance of the snow cover. The models were useful toevaluate the lack of energy balance closure in the observedsurface heat fluxes, which underlined the importance ofimproved accuracy in eddy correlation measurements of latentflow during winter conditions.

The representation of boreal forest in the land surfacescheme used within a weather forecast model was tested with athree-year data set from the NOPEX forest site in centralSweden. The formulation with separate energy balances forvegetation and the soil/snow beneath tree cover improvedsimulation of the seasonal and diurnal variations of latent andsensible heat flux compared with an older model version.Further improvements of simulated surface heat fluxes could beexpected if the variation of vegetation properties within andbetween years and a new formulation of the boundary conditionsfor heat flux into the soil is included.

Keywords: Surface energy balance, Snow, Boreal forest,SVAT models, Eddy-correlation Measurements, Latent heat flux,Sensible heat flux, Net radiation, Soil temperature,Aerodynamic roughness, Surface resistance

QC 20100614

Epidermolysis bullosa simplex (EBS) and epidermolytic ichthyosis (EI) are rare skin fragility diseases characterized by intra-epidermal blistering due to autosomal dominant-negative mutations in basal (KRT5 or KRT14) and suprabasal (KRT1 or KRT10) keratin genes,  respectively. Despite vast knowledge in the disease pathogenesis, the pathomechanisms are not fully understood, and no effective remedies exist. The purpose of this work was to search for keratin gene mutations in EBS patients, to develop in vitro models for studying EBS and EI, and to investigate novel pharmacological approaches for both diseases. We identified both novel and recurrent KRT5 mutations in all studied EBS patients but one which did not show any pathogenic keratin mutations. Using cultured primary keratinocytes from EBS patients, we reproduced a correlation between clinical severity and cytoskeletal instability in vitro. Immortalized keratinocyte cell lines were established from three EBS and three EI patients with different phenotypes using HPV16-E6E7. Only cell lines derived from severely affected patients exhibited spontaneous keratin aggregates under normal culture conditions. However, heat stress significantly induced keratin aggregates in all patient cell lines. This effect was more dramatic in cells from patients with a severe phenotype. In organotypic cultures, the immortalized cells were able to differentiate and form a multilayered epidermis reminiscent of those observed in vivo. Addition of two molecular chaperones, trimethylamine N-oxide dihydrate (TMAO) and sodium 4-phenylbutyrate (4-PBA), reduced the keratin aggregates in both stressed and unstressed EBS and EI keratinocytes, respectively. The mechanism of action of TMAO and 4-PBA was shown to involve the endogenous chaperone system (Heat shock proteins e.g. Hsp70). Besides, MAPK signaling pathways also seemed to be incriminated in the pathogenesis of EBS. Furthermore, depending on which type of keratin is mutated, 4-PBA up-regulated Hsp70 and KRT4 (possibly compensating for mutated KRT1/5), and down-regulated KRT1 and KRT10, which could further assist in protecting EBS and EI cells against stress. In conclusion, novel and recurrent pathogenic keratin mutations have been identified in EBS. Immortalized EBS and EI cell lines that functionally reflect the disease phenotype were established. Two pharmacologic agents, TMAO and 4-PBA, were shown to be promising candidates as novel treatment of heritable keratinopathies in this in vitro model.

In the residential and commercial buildings, most of the energy is used to provide the thermal comfort environment to the occupants. The recent research towards Green Buildings is focusing on reduction of energy consumption by air-conditioners and fans used for producing the thermal comfort environment. The thermal comfort is defined as the condition of mind which expresses human satisfaction with the thermal environment. The human body is continuously producing metabolic heat and it should be maintained within the narrow range of core temperature. The heat generated inside the body should be lost to the environment to maintain the thermal equilibrium with each other. The heat loss from the body is taking place in different modes such as conduction, convection, radiation and evaporation through the skin and respiration. These heat losses are influenced by the environmental factors (air temperature, air velocity, relative humidity and mean radiant temperature), physiological factors (activity level, posture and sweat rate) and clothing factors (thermal insulation value, evaporative resistance and microenvironment volume). When the body is in thermally equilibrium with its surrounding environment, the heat production should be equal to heat loss to maintain the thermal comfort. The level of thermal comfort can be measured by the different indices which combine many parameters. Of these, the Fanger’s PMV (Predicted Mean Vote) – PPD (Percentage of People Dissatisfied) index was universally suggested by ASHRAE and ISO. The PMV – PPD index was derived based on the experiment conducted on acclimated European and American subjects. Many researchers have criticized that the PMV – PPD index is not valid for tropical regions and some researchers have well agreed with this index for the same region. The validation of PMV – PPD index for thermal comfort Indians has not yet been examined. The validation of PMV – PPD index can be done by the human heat balance experiment and the individual heat losses have to be calculated from the measured parameters. In the human heat balance, the convective heat transfer plays the major role when the air movement exists around the human body. The convective heat loss is dependent on the convective heat transfer coefficient which is the function of the driving force of the convection. Using Computational Fluid Dynamics techniques, an attempt has been made in this work to determine the convective heat transfer coefficient of the human body at standing posture in natural convection. The CFD technique has been used to analyze the heat and fluid flow around the human body as follows: The anthropometric digital human manikin was modeled in GAMBIT with a test room. This model was meshed by tetrahedral elements and exported to FLUENT software to perform the analysis. The simulation was done at different ambient temperatures (16 oC to 32 oC with increment of 2 oC). The Boussinesq approximation was used to simulate the natural convection and the Surface to Surface model was used to simulate the radiation. The surrounding wall temperature was assigned equal to the ambient temperature. The sum of convective and radiative heat losses calculated based on the ASHRAE model was set as heat flux from the manikin’s surface. From the simulation, the local skin temperatures have been taken, and the temperature and velocity distributions analyzed. The result shows that the skin temperature is increasing with an increase in ambient temperature and the thickness of the hydrodynamic and thermodynamic boundary layers is increasing with height of the manikin. From the Nusselt number analogy, the convective heat transfer coefficients of the individual manikin’s segments have been calculated and the relation with respect to the temperature differences has been derived by the regression analysis. The relation obtained for the convective heat transfer coefficient has been validated with previous experimental results cited in literature for the same conditions. The result shows that the present relation agrees well with the previous experimental relations. The characteristics of the human thermal plume have been studied and the velocity of this plume is found to increase with the ambient temperature. Using the Grashof number, the flow around the human manikin has been examined and it is observed to be laminar up to abdomen level and turbulent from shoulder level. In between these two levels, the flow is found to be in transition. The validation of PMV model for tropical countries, especially for Indians, was done by heat balance experiment on Indian subjects. The experiment was conducted on forty male subjects at different ambient temperatures in a closed room in which low air movement exists. The local skin temperature, relative humidity, air velocity and globe temperature were measured. The sensation vote was received from all the subjects at all the conditions. The convective heat loss was calculated from its coefficient obtained from the present computational simulation. The radiation heat loss was calculated for two cases: In case one, the mean radiant temperature was taken equal to the ambient temperature and in case two, the mean radiant temperature was calculated from the globe temperature. The other heat losses were calculated from the basic formulae and the relations given by ASHRAE based on Fanger’s assumption. From these calculations, the validity of the Fanger’s assumption was examined. The collected sensation votes and the calculated PMV were compared to validate the PMV – PPD index for Indians. The experimental results show that there was much variation in the calculated comfort level using the measured parameters and the Fanger’s assumption. For the case of mean radiant temperature equal to the ambient temperature for indoor condition, the comfort level was varying more than the actual. In addition, the calculated comfort level from the globe temperature agreed well with the comfort level from the collected sensation votes. So it was concluded that the ASHRAE model is valid for Indians if the radiation was measured exactly. Using the ASHRAE model, the required wall emissivity of the surrounding wall at different ambient temperatures was determined from the CFD simulation. In the ASHRAE model, the surrounding wall emissivity plays the major role in the radiative heat loss from the human body. Hence in recent years, research on low emissive wall paints is focused. The computational study was done to determine the required wall emissivity to obtain the thermal comfort of the occupant at low energy consumption. The simulation was done with the different ambient temperatures (16 oC to 40 oC with increment of 4 oC) with the different surrounding wall emissivity (0.0 to 1.0 with increment of 0.2). From this simulation, the change in mean skin temperature with respect to wall emissivity was obtained for all ambient temperature conditions. The required mean skin temperature for a particular activity level was compared with the simulation results and from that, the required wall emissivity at the different ambient conditions was determined. If the surrounding walls are having the required emissivity, it leads to decrease in heat/cold strain on the human body, and the thermal comfort can be obtained with low energy consumption.(please note that title in the CD is given as COMPUTATION OF REQUIRED WALL EMISSIVITY FOR LOW ENERGY CONSUMPTION IN BUILDINGS USING ASHRAE MODEL VALIDATED FOR INDIAN THERMAL COMFORT)

In the residential and commercial buildings, most of the energy is used to provide the thermal comfort environment to the occupants. The recent research towards Green Buildings is focusing on reduction of energy consumption by air-conditioners and fans used for producing the thermal comfort environment. The thermal comfort is defined as the condition of mind which expresses human satisfaction with the thermal environment. The human body is continuously producing metabolic heat and it should be maintained within the narrow range of core temperature. The heat generated inside the body should be lost to the environment to maintain the thermal equilibrium with each other. The heat loss from the body is taking place in different modes such as conduction, convection, radiation and evaporation through the skin and respiration. These heat losses are influenced by the environmental factors (air temperature, air velocity, relative humidity and mean radiant temperature), physiological factors (activity level, posture and sweat rate) and clothing factors (thermal insulation value, evaporative resistance and microenvironment volume). When the body is in thermally equilibrium with its surrounding environment, the heat production should be equal to heat loss to maintain the thermal comfort. The level of thermal comfort can be measured by the different indices which combine many parameters. Of these, the Fanger’s PMV (Predicted Mean Vote) – PPD (Percentage of People Dissatisfied) index was universally suggested by ASHRAE and ISO. The PMV – PPD index was derived based on the experiment conducted on acclimated European and American subjects. Many researchers have criticized that the PMV – PPD index is not valid for tropical regions and some researchers have well agreed with this index for the same region. The validation of PMV – PPD index for thermal comfort Indians has not yet been examined. The validation of PMV – PPD index can be done by the human heat balance experiment and the individual heat losses have to be calculated from the measured parameters. In the human heat balance, the convective heat transfer plays the major role when the air movement exists around the human body. The convective heat loss is dependent on the convective heat transfer coefficient which is the function of the driving force of the convection. Using Computational Fluid Dynamics techniques, an attempt has been made in this work to determine the convective heat transfer coefficient of the human body at standing posture in natural convection. The CFD technique has been used to analyze the heat and fluid flow around the human body as follows: The anthropometric digital human manikin was modeled in GAMBIT with a test room. This model was meshed by tetrahedral elements and exported to FLUENT software to perform the analysis. The simulation was done at different ambient temperatures (16 oC to 32 oC with increment of 2 oC). The Boussinesq approximation was used to simulate the natural convection and the Surface to Surface model was used to simulate the radiation. The surrounding wall temperature was assigned equal to the ambient temperature. The sum of convective and radiative heat losses calculated based on the ASHRAE model was set as heat flux from the manikin’s surface. From the simulation, the local skin temperatures have been taken, and the temperature and velocity distributions analyzed. The result shows that the skin temperature is increasing with an increase in ambient temperature and the thickness of the hydrodynamic and thermodynamic boundary layers is increasing with height of the manikin. From the Nusselt number analogy, the convective heat transfer coefficients of the individual manikin’s segments have been calculated and the relation with respect to the temperature differences has been derived by the regression analysis. The relation obtained for the convective heat transfer coefficient has been validated with previous experimental results cited in literature for the same conditions. The result shows that the present relation agrees well with the previous experimental relations. The characteristics of the human thermal plume have been studied and the velocity of this plume is found to increase with the ambient temperature. Using the Grashof number, the flow around the human manikin has been examined and it is observed to be laminar up to abdomen level and turbulent from shoulder level. In between these two levels, the flow is found to be in transition. The validation of PMV model for tropical countries, especially for Indians, was done by heat balance experiment on Indian subjects. The experiment was conducted on forty male subjects at different ambient temperatures in a closed room in which low air movement exists. The local skin temperature, relative humidity, air velocity and globe temperature were measured. The sensation vote was received from all the subjects at all the conditions. The convective heat loss was calculated from its coefficient obtained from the present computational simulation. The radiation heat loss was calculated for two cases: In case one, the mean radiant temperature was taken equal to the ambient temperature and in case two, the mean radiant temperature was calculated from the globe temperature. The other heat losses were calculated from the basic formulae and the relations given by ASHRAE based on Fanger’s assumption. From these calculations, the validity of the Fanger’s assumption was examined. The collected sensation votes and the calculated PMV were compared to validate the PMV – PPD index for Indians. The experimental results show that there was much variation in the calculated comfort level using the measured parameters and the Fanger’s assumption. For the case of mean radiant temperature equal to the ambient temperature for indoor condition, the comfort level was varying more than the actual. In addition, the calculated comfort level from the globe temperature agreed well with the comfort level from the collected sensation votes. So it was concluded that the ASHRAE model is valid for Indians if the radiation was measured exactly. Using the ASHRAE model, the required wall emissivity of the surrounding wall at different ambient temperatures was determined from the CFD simulation. In the ASHRAE model, the surrounding wall emissivity plays the major role in the radiative heat loss from the human body. Hence in recent years, research on low emissive wall paints is focused. The computational study was done to determine the required wall emissivity to obtain the thermal comfort of the occupant at low energy consumption. The simulation was done with the different ambient temperatures (16 oC to 40 oC with increment of 4 oC) with the different surrounding wall emissivity (0.0 to 1.0 with increment of 0.2). From this simulation, the change in mean skin temperature with respect to wall emissivity was obtained for all ambient temperature conditions. The required mean skin temperature for a particular activity level was compared with the simulation results and from that, the required wall emissivity at the different ambient conditions was determined. If the surrounding walls are having the required emissivity, it leads to decrease in heat/cold strain on the human body, and the thermal comfort can be obtained with low energy consumption.(please note that title in the CD is given as COMPUTATION OF REQUIRED WALL EMISSIVITY FOR LOW ENERGY CONSUMPTION IN BUILDINGS USING ASHRAE MODEL VALIDATED FOR INDIAN THERMAL COMFORT)

The literature pertaining to models of human thermoregulation is critically reviewed. It is concluded that none of the models investigated can be used to predict the physiological response of acclimatized men required to work in the heat for extended periods of time, the reasons being: (i) physiological conductance (the lumped parameter describing internal heat transfer) has not been completely described in terms of all the variables effecting it (ii) the dynamic nature of the sweat rate response has never been mathematically described. A composite block diagram model for human thermoregulation, based on a single cylinder core and shell model of the controlled system, is postulated as a feasible solution to the problem of predicting physiological responses to work in the heat. The controlling system, consisting of physiological conductance and sweat rate, is singled out for thorough investigation. Detailed experimentation was carried out on a single nude acclimatized man over a wide range of environments (13,6°C dry-bulb, 9,2°C wet-bulb to 38,5°C dry-bulb, 36,5°C wet-bulb) and work rates (resting, 60 W/m2 to exercising, 240 W/m2 ). Each experiment lasted four hours. Physiological conductance (K) is expressed as a sigmoidal function of a weighted body temperature driving signal (Tmb ) and metabolic rate (M), such that for the same Tmb, K increases with increasing M. The saturation level of K at low Tm b is expressed as a linear function of M, the saturation level of K at high Tmb, is expressed as an exponential function of M. Because of the dynamic nature of the sweat rate response to a step change in environmental conditions and/or work rate, basic engineering control theory is used tc formulate a block diagram model for thermoregulatory sweating. The model introduces a rational approach to combining Tmb, local effect of skin temperature, sweat gland fatigue, skin wettedness and their time histories.

There is no overlapping criterion providing a basis for attaining balance between individual and population oriented ethical concerns generated in the pandemic and the epidemic interventions. The shortfall leads to competing individual and population interests that hamper the effective management of pandemics and epidemics. The libertarian model focuses on advancing individual rights. The epidemiological model focuses upon population health. The social justice model focuses on a broader perspective than individual rights and population health to include universal human rights. <br>This dissertation suggests a Mixed Interests Ethics Model (MIEM) to ethically negotiate a balance between the individual and population interests in pandemics and epidemics. MIEM involves a combination of models (libertarian, epidemiological, and social justice) that shed light on substantive ethical principles of each model (e.g. autonomy, solidarity, and common good); which in turn require procedural standards (i.e. necessity, reasonableness, proportionality, and harm avoidance) to negotiate between the principles when they conflict. <br>The UNESCO Universal Declaration on Bioethics and Human Rights provides a hermeneutical context for applying MIEM in so far as it places MIEM within the context of promoting rights (individual and human) by considering the general ethical tension between individual and universal rights as explained by the UNESCO Declaration.
McAnulty College and Graduate School of Liberal Arts;
Health Care Ethics
PhD;
Dissertation;

Background and objectives: There is compelling scientific evidence that climate change will increase the frequency of heat waves which have an impact on population health. In Adelaide, unprecedented heat waves have been experienced in recent years which had significant impact on human health. The objectives of this research project were to: (1) explore public opinion (views and attitudes) about heat waves in relation to climate change, (2) explore public understanding of the consequences and the emotional and psychological responses associated with heat waves, (3) identify the predictors of risk perception using a heat wave scenario and adaptive behaviours during heat waves; and (4) explore the concept of multi-stakeholder processes during the development of an adaptation strategy for heat waves. Methods: In the first study, interviews were conducted among fourteen residents to explore their views about heat waves, their understanding of its consequences and the emotional and psychological responses associated with heat waves. The second study was a cross-sectional study that examined the attitudes towards heat waves, risk perception and adaptive behaviours during heat waves among 267 participants with the health belief model used as the theoretical framework. The third study explored the concept of multi-stakeholder processes during the development of an adaptation strategy for heat waves. Data were gathered through a review of policy documents and interviews with eighteen stakeholders involved in the strategy development process. Qualitative data were analysed according to themes while descriptive and inferential statistical techniques were used to analyse quantitative data. Results: In the first study, most participants didn’t associate recent heat waves in Adelaide with climate change, although they acknowledged a considerable change in weather patterns over recent years. Although there were differences in the level of understanding among the participants, they modified their behaviours during a heat wave. Fear, worry, anxiety and concern were the main emotional responses associated with heat waves. Participants were concerned about low agricultural productivity, the costs of running an air-conditioner, sleeping well, and the threat of bush fires during a heat wave. In the second study, there was a significant association between gender, annual household income and concern for the societal effects of heat waves. About 43.2% of the participants believed that heat waves will extremely or very likely increase in Adelaide according to climate projections; 49.3% believed that the effects of heat waves were already being felt. The significant predictors of risk perception included age, marital status, annual household income, fan ownership and living arrangements. Participants’ perceived benefit, cues to action, educational level, and annual household income were associated with adaptive behaviours during a heat wave. In the third study, there was high level governance, leadership, collaboration, coordination and good institutional arrangements during the adaptation strategy development process in South Australia. The process benefited from the Emergency Management Act 2004, which facilitated an enabling environment. Although the process was not entirely inclusive and the fact that it experienced a few challenges, the strategy development process was overall successful. Conclusions: These findings suggest that there are variations in public opinion about heat waves in the context of climate change. Heat waves affect the emotional and psychological wellbeing of certain individuals. Using the health belief model as the theoretical framework, perceived benefit and cues to action predicted good adaptive behaviours. There were some demographic factors that were associated with risk perception in relation to heat waves. These factors would inform risk communication and behaviour change strategies for heat waves. An adaptation policy process for heat waves indicates that the process can be successful through a participatory process characterised by good leadership, excellent coordination, governance and institutional framework.
Thesis (Ph.D.) -- University of Adelaide, School of Population Health, 2014.

South African forestry workers are predisposed to dehydration due to the heavy physical activity they perform in impermeable regulation safety clothing in hot and often humid environments where the availability of a variety of suitable fluids at reasonable temperatures is limited. As dehydration reduces both physical and mental capacity the potential consequences include decreased productivity and an increased risk for injury. The aim of this cross sectional observational study was to determine the prevalence and severity of dehydration in rural forestry workers in both winter (minimum and maximum daily temperatures 3-22°C) and autumn (minimum and maximum daily temperatures 14-27°C). The convenience sample included 103 workers in autumn (Nelspruit, n=64 males, n=39 females, mean age 37.32 years, mean BMI 22.3 kg/m2) and 79 in winter (Richmond, n=68 males, n=11 females, mean age 25.85 years, mean BMI 22.2 kg/m2). The sample included chainsaw operators, chainsaw operator assistants, debarkers and stackers. The risk of heat illness was moderate in Nelspruit (average daily temperature 21.1°C 67% rh) and low in Richmond (average daily temperature 17.0°C 39% rh). The prevalence of dehydration was determined by urine specific gravity (USG) measurements. Percent loss of body weight in the course of the shift was used to determine the severity of dehydration. In Nelspruit 43% (n=43) and in Richmond 47% (n=37) of the forestry workers arrived at work dehydrated (USG>1.020 g/ml). Pre break this had increased to 49% (n=49) in Nelspruit and 55% (n=33) in Richmond. By the end of shift the number of dehydrated forestry workers had significantly increased to 64% (n=64, p≤0.001) in Nelspruit and 63% (n=42, p=0.043) in Richmond. A minimum of 21% (n=2) in Nelspruit and 23% (n=15) in Richmond of the forestry workers had lost more than 2% of their body weight which could significantly decrease work capacity and work output as well as mental and cognitive ability. Dehydration was not related to season (winter/autumn), gender or job category. In Nelspruit 23% (n=23) and in Richmond 13% (n=10) arrived at work overhydrated (USG<1.013 g/ml). Pre break this had decreased to 14% (n=14) in Nelspruit and 10% (n=6) in Richmond. By the end of shift 4% (n=4) in Nelspruit and 2% (n=1) in Richmond had remained overhydrated and without correcting for fluid and food intake, 5% (n=5) had gained over 2% of their body weight in Nelspruit while none had gained weight in Richmond. Overhydration was not related to season (winter/autumn), gender or job category. Physical symptoms at the end of shift included tiredness (24%), toothache (13%) and headaches (10%) although these did not correlate to end of shift USG readings (p=0.221). The fluid requirements for male workers (n=8) who did not eat or drink across the shift was 439 ml per hour. The contractors were unaware of how much fluid should be supplied to workers and how much fluid they actually supplied. The only fluid provided by the contractors was water at the ambient air temperature which was the main source of fluid for the majority. Some forestry workers brought a limited variety of other fluids including amahewu, tea and cold drinks to work. At least 40% of the work force investigated, started their shift already compromised to work to capacity (USG>1.020 g/ml). The prevalence of dehydration had increased by the break emphasizing the need to begin drinking early on in the shift. The majority of forestry workers were dehydrated at the end of the shift. A significant proportion was dehydrated to the extent (>2%) that both work capacity and mental ability would be significantly compromised. A select group of forestry workers were drinking excessive amounts of fluid and were therefore susceptible to potentially fatal dilutional hyponatremia especially as water was the primary source of fluid. Dehydration in both autumn and winter was identified as being a significant but preventable risk. As a consequence of overhydration, a small group of forestry workers may be susceptible to dilutional hyponatremia. Fluid intake guidelines for males of 450 ml per hour appeared to be safe and were within the recommendations of the American College of Sports Medicine. Fluid guidelines for females need investigation.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.