Rozprawy doktorskie na temat „Acclimatisation”

World-wide, increasing numbers of individuals repeatedly alternate between low and high altitude for work and play. There is a general impression that acquired acclimatisation status persists for some time following return to sea level and that subsequent altitude tolerance is improved by previous hypoxic experience. However, it is unknown whether previous exposure to high altitude fundamentally alters the process of hypoxic re-acclimatisation (RA). My Doctoral research employed a number of approaches to investigate potential differences between the processes of initial acclimatisation (IA) and RA. The time course and mechanisms of hypoxic de-acclimatisation (DA) were explored to determine the time domains across which the retention of previous acclimatisation status might facilitate RA. Cross-sectional and longitudinal field studies were conducted to compare functional outcomes, cardiorespiratory function in rest and exercise and haematological responses throughout IA and RA in high-altitude trekkers. Results indicated that clinical outcomes and trekking performance were improved in RA but with limited physiological evidence of underlying improvements in hypoxic compensation. The haematological response to hypoxia was slightly greater in RA than IA, prompting further investigation of haematological RA in an animal model. Three paradigms of RA were used to examine the effect of IA and DA duration on the process of haematological RA in mice exposed to normobaric hypoxia. Despite altered erythropoietic control in RA treatments, the resulting haematological responses were generally consistent between IA and RA with no evidence of improved responses in RA. In fact, haematological acclimation was impaired in one RA treatment, possibly due to reduced availability of nutrients required for haemoglobin synthesis following an extended period of IA and upregulated erythropoiesis. Given the lack of physiological explanation for improved functional outcomes in RA, non-physiological mechanisms were pursued. Interviews with altitude-experienced individuals identified a perception that prior altitude experience leads to reduced altitude-induced anxiety and improved psychological tolerance of sensations associated with altitude exposure. Although physiological aspects of hypoxic re-acclimatisation merit further investigation, it is possible that improved psychological tolerance of high altitude contributes to the improved functional outcomes in RA that are reported here and elsewhere.

Results of the first investigation into possible acclimatisation to cold and thermal status of Antarctic divers are presented. Over a year, on average one subject dived on alternate days and the other four subjects once a week. Divers wore 7mm or 10mm wet suits in water ca-1^oC. Mean dive duration was 30min, and mean depth of immersion 9m. Surface mean wind speed was 10 knots and mean ambient temperature -2^oC. Over the year subjects rectal and skin temperatures, and thermal comfort were monitored before, during and after immersion on 26 dives. Severe body cooling (Hall 1972) occurred on 75%, rectal temperature decreased to below normal (although never to clinically hypothermic levels) and there was a marked, exponential drop in skin temperature. End-of-dive finger temperatures were always at a level at which impairment of function would be expected. Divers were usually uncomfortably cold at the end of dives. During the year repeated monthly measurements were made of: skinfold thickness, body weight, body fat weight and fat-free mass: basal metabolic rate: rectal and skin temperatures, metabolic rate, shivering, thermal comfort, adrenaline, noradrenaline and cortisol excretion during immersion to the neck in water at 20^oC for one hour: time of onset of cold-induced vasodilatation, temperature and pain responses of left index finger immersed at 0^oC for half an hour. Differences between the responses of divers at different months of the year and between divers and nondivers were tested by analysis of variance. It was found that divers shivered less and had less thermal discomfort (by verbal rating scales) than nondivers (as they had similar metabolic rates this suggests greater nonshivering thermogenesis). It was also found that divers extracted more oxygen from inspired air while immersed to the neck than nondivers. In both divers and nondivers there was a winter increase of skinfold thickness and body fat weight and a winter decrease of fat-free mass, and while these may be an adaptation to cold, it is possible that other stimuli were responsible. No significant differences were found between any of the other parameters tested. Monthly measurements of physical fitness, and time spent outside and in various activities indicated that these were not important complicating factors in the acclimatisation studies. A comparison of Antarctic dives and laboratory cold water immersions showed that while dives led to a greater fall of peripheral temperature and lower peripheral thermal comfort the laboratory immersions led to a greater fall in rectal temperature and trunk skin temperature. In this thesis, it is proposed that while Antarctic divers were subject to considerable thermal stress there was little evidence of cold acclimatisation.

This Portfolio aims to examine the problems of acclimatisation and coping strategies of such foreign students. A sample of tweleve students was chosen from Chinese students studying at one private educational institution in Singapore. Drawing on the findings of Furnham (1997) and Murphy-Lejenne (2002), among others, the present study looks at the reasons why the participants decided to travel overseas, why they chose Singapore as their destination, what problems they encountered while here, and how they coped with the problems. They were also asked what specific problems they encountered with the schools they enrolled in. It is the contention of the present study that school has a major influenceon their overall acclimatisation. Suggestions were sought from the participants on ways they thought the school could help make their stay here more successful The in-depth interviews found that the main problem encountered by the Chinese students were with accommodation, student agents, school, language, and the :attitude of the local populance towards them. To cope with their problem;, they relied on friends, and family for support and information, and used modern technology for communication. They expected the school to help them find suitable accommodation and practise higher standards of service. The present study concludes with recommendations for further actions needed by schools and government and areas for future research.

Historians have investigated for some time the nature and practice of colonial science. Some have seen it in terms of the spread of European influence and knowledge in an age of imperialism, others have studied it in particular local contexts. These studies identi& an emphasis on practical science and natural history, and a degree of dependence on experts resident at the European centre. More recent work thaws attention to the exchange of information that occurred between various sites on the periphery. In this thesis I investigate the nature and practice of science in Brisbane in the latter half of the nineteenth century. Brisbane was a small, isolated town, an administrative centre in a colony dominated by its pastoral industry. The govermnent, partly because of regular budgetary crises and partly because it could not perceive any public benefit, was not interested in funding science. The two scientific institutions - the Philosophical Society, which became the Royal Society in 1883, and the Acclimatisation Society - are studied in order to demonstrate the ways in which men with scientific interests organised themselves and attempted to influence the scientific agenda. I go on to trace the relationships and communication networks of the two men who are arguably the pre-eminent figures in nineteenth-century Queensland science, F. M. Bailey and Joseph Bancroft, in an attempt to determine what effect geographic and intellectual isolation, and lack of funding, had on their activities. Several themes emerge. First, although there was an emphasis as elsewhere on practical science and natural history, for some middle class men science was a social and cultural pursuit. These men, in seeking to re-create the institutions that they had left behind them in Britain, established social and political networks that helped to establish them in a new society. The continual inflow of new immigrants guaranteed an inflow of scientific culture and new technology. Second, acclimatisation and economic botany provided a focus for practical scientific activities. Through the leadership of Lewis Bernays, a public servant with no scientific background or training, acclimatisation became a respectable activity in which people from all over the colony participated. Acclimatisation represented the interface between science, technology and economic progress. Third, other men such as F. M. Bailey, the colonial botanist, and Dr Joseph Bancroft, who had many scientific interests, were intent on both expanding the body of knowledge and making use of what they considered useful knowledge for the benefit of the colony. A simple diffusion model does not explain adequately the complex conditions under which western science was pursued and established in a remote settler society such as Queensland.

Historians have investigated for some time the nature and practice of colonial science. Some have seen it in terms of the spread of European influence and knowledge in an age of imperialism, others have studied it in particular local contexts. These studies identi& an emphasis on practical science and natural history, and a degree of dependence on experts resident at the European centre. More recent work thaws attention to the exchange of information that occurred between various sites on the periphery. In this thesis I investigate the nature and practice of science in Brisbane in the latter half of the nineteenth century. Brisbane was a small, isolated town, an administrative centre in a colony dominated by its pastoral industry. The govermnent, partly because of regular budgetary crises and partly because it could not perceive any public benefit, was not interested in funding science. The two scientific institutions - the Philosophical Society, which became the Royal Society in 1883, and the Acclimatisation Society - are studied in order to demonstrate the ways in which men with scientific interests organised themselves and attempted to influence the scientific agenda. I go on to trace the relationships and communication networks of the two men who are arguably the pre-eminent figures in nineteenth-century Queensland science, F. M. Bailey and Joseph Bancroft, in an attempt to determine what effect geographic and intellectual isolation, and lack of funding, had on their activities. Several themes emerge. First, although there was an emphasis as elsewhere on practical science and natural history, for some middle class men science was a social and cultural pursuit. These men, in seeking to re-create the institutions that they had left behind them in Britain, established social and political networks that helped to establish them in a new society. The continual inflow of new immigrants guaranteed an inflow of scientific culture and new technology. Second, acclimatisation and economic botany provided a focus for practical scientific activities. Through the leadership of Lewis Bernays, a public servant with no scientific background or training, acclimatisation became a respectable activity in which people from all over the colony participated. Acclimatisation represented the interface between science, technology and economic progress. Third, other men such as F. M. Bailey, the colonial botanist, and Dr Joseph Bancroft, who had many scientific interests, were intent on both expanding the body of knowledge and making use of what they considered useful knowledge for the benefit of the colony. A simple diffusion model does not explain adequately the complex conditions under which western science was pursued and established in a remote settler society such as Queensland.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Humanities
Arts, Education and Law
Full Text

This study considers how environmental concerns helped shape Melbourne's public parkland in the period 1850-1920, when Melbourne's first parks were developed and during which ecology began to replace natural history as the determinant of environmental thought. Theories propounded by such figures as Alexander von Humboldt and George Perkins Marsh profoundly influenced land management around the world during this period, and by relating specific parkland developments to professional and popular ideas about the environment the study aims to place the parkland in an international context. Previous research has given little thought to the effect of environmental thought on Melbourne's parks, except for Ferdinand von Mueller's development of the Melbourne Botanic Garden where the influence is evident. Such influence has not been considered in Clement Hodgkinson's contemporaneous development of the city's other parks and gardens even though, like Mueller, Hodgkinson was closely involved with environmental issues of the day. The Field Naturalists Club of Victoria, of which Mueller was a member, has long been credited with influencing Wattle Park's development early in the 20th century, although there is little critical analysis of the extent to which it was able to bring popular concerns about the environment to bear on park design. The relationship between Mueller's environmental views and actions and his development of the Botanic Garden is discussed first. Connections are then made between Hodgkinson's early experiences as a surveyor, his later work as Victoria's foremost land manager, his association with Mueller, and his design of Melbourne's first parks and gardens. Finally, the FNCV's involvement in park development is examined while exploring the changing nature of environmental thought. Clearly, environmental thought did influence the development of some parkland, but only those reserves administered by Mueller and Hodgkinson and only while the two men remained in control. The success of the FNCV in influencing the future direction of any Melbourne park or garden is not so easily discernible, with little evidence that the Club played an important role in Wattle Park's development.

Introduction: Personality Trait theories uncritically accept the lay perspective of personality as an internal phenomenon linked to individuality and agency. This view flies in the face of empirical evidence demonstrating environmental influences on behaviour (Bargh & Ferguson, 2000). The idea that agency resides within individuals, and that a separation exists between individuals and their environment, has long been contested by theorists and clinicians arguing for acknowledgement of contextual factors (Skinner, 1971; Smail, 1999). Scores on personality measures based on the Five-Factor Approach (FFA; Costa & McCrae, 1985) have shown instability across the lifespan in relation to factors such as relationships (Neyer & Lehnart, 2007), and short-term changes in response to major adverse events (Lockenhoff, Terracciano, Patriciu, Eaton & Costa, 2009). That “personality” scores change in response to the environment highlights the weakness of the trait concept as a way of understanding behaviour. The move to university represents a major change of social environment that is sudden but predictable, and persists for a long time. It is therefore a time at which we can expect to observe changes in behaviour. Previous research into university acclimatisation and “homesickness” has assumed personality scores to be a static variable (e.g. Fisher & Hood, 1987) that impacts upon the relocation without being affected by it. This study sought to investigate the hypothesis that novel identity narratives would be evoked by a new environment and that this would impact upon acclimatisation. The study aimed to test this hypothesis by examining participant accounts. Method: First-year students (N = 7) completed two questionnaires designed to assess personality and homesickness. These measures were re-administered after six and fourteen weeks. Participants were interviewed at all three time-points, describing their experiences of adjusting to life at university. Interviews with participants were used as a basis for comparison with scores on psychometrics designed to measure personality and homesickness. These were analysed using a method that aimed at exploring narratives likely to impact on participants’ acclimatisation and presentation of themselves. The extended paper details a quantitative analysis of psychometric scores amongst a larger sample of 1st year students (N = 58). Results and Discussion: Participant accounts were analysed in terms of identity narratives to allow formulation of their experiences in relation to their psychometric scores. Participants described behaving differently at university and taking on new roles that impacted upon their acclimatisation. Despite reporting changes, participants expressed essentialist views about the self. Results from the quantitative study were not supportive of the hypothesis that homesickness would be associated with change on FFA measures.

Abstract The purpose of the study was to examine the amount of cold exposure and factors affecting it at the population level in Finland, to determine what type of cold acclimatisation, if any, develops in urban residents in winter, and to find out whether cold acclimatisation or acclimation has a functional significance on psychological or physical performance. Tasks of low physical activity requiring attention and concentration (cognition, postural control) were assessed in cold. In a cross-sectional population study Finns aged from 25 to 74 years (n=6,951) were queried of their wintertime outdoor exposure duration and factors affecting it. In experimental studies seasonal cold acclimatisation (thermal responses) and its effect on cognition were assessed in the laboratory, where 15 young urban subjects were exposed to cold in winter and summer in bright or dim light. A controlled cold acclimation trial (n=10) was performed to study the effects of repeated exposures to cold on cognitive performance and postural control in young urban subjects. In the Finnish population the average amount of cold exposure in winter represents 4% of the total time. Most of the cold exposure occurs during leisure time and in outdoor occupations (agriculture, forestry, mining, industry, construction). Factors explaining increased occupational cold exposure were: occupation, age and a lesser amount of education. Factors associated with more leisure-time cold exposure were: being employed in outdoor occupations, being a pensioner, housewife, unemployed, practising physical exercise, and reporting at least average health. The experimental studies showed seasonal differences and aggravated thermal responses in urban residents in winter, but did not detect habituation responses typical of cold acclimatisation. In both seasons, acute moderate cold exposure resulted in positive, negative or mixed effects on cognition, reflected as changes in response times and accuracy. Simple cognitive tasks were impaired in cold, and in complex tasks both negative, positive and mixed effects were observed. It is suggested that cold exposure affects cognition through different mechanisms related to either distraction or arousal. Cold exposure increased postural sway by 70-90%, suggesting impaired postural control. Repeated exposures to moderate cold, reducing stress and discomfort and dampening physiological responses, did not markedly affect cognitive performance or postural control.

The subject of this dissertation is the Zoological Gardens of the Zoological Society of London (f. 1826) in the nineteenth century. Located in Regent s Park, it was the express purpose of the Gardens (f. 1828) to function as a testing-ground for acclimatisation and to demonstrate the scientific impor­tance of various animal species. The aim is to analyse what the Gardens signified as a recreational, educational and scientific institution in nineteenth-century London by considering them from four different perspectives: as a pan of a newly-founded society, as a part of the leisure culture of mid-Victorian London, as a medi­ator of popular zoology and as a constituent of the Zoological Society's scientific ambitions. After an introduction which describes the devlopment of European zoos, Chapter two recapitu­lates the early years of the Society and the Gardens. The original aims of the Society—science and acclimatisation located in a museum and zoological garden—as stated in various prospectuses, are examined. The implications of acclimatisation, it being a problematic practice, are outlined and the connections between acclimatisation, the Society, the Gardens and the British Empire are also briefly considered. The founding of the Gardens is extensively described as well as how the animals were obtained and how exhibits were arranged. Chapter three is based primarily on the popular response to the Gardens in the 1850s when, after a period of decline, the institution once again became a common London visiting-place. The most important questions of this chapter concern the public and how it reacted to the Gardens of this period. The financial problems preceding the five years between 1850 and 1855 ^ described as well as how the Society managed to regain its popularity. This process was closely linked to the decision in 1847to let non-members of the Society enter the Gardens, and the implications of this resolution are discussed. As a background to the Gardens' popularity, two other London recreations are also described: the Colosseum Panorama and the Surrey Zoological Garden. The Surrey Zoological Gar­den especially is interesting, as it was a rival of the Society's Gardens, and the different attractions of these establishments are considered. Chapter four focuses on the official and non-official guidebooks to the Gardens and the implica­tions of these as mediators of popular zoology. The historical and cultural connection between the guidebooks and travel handbooks is oudined and also how the genre as a whole is constructed. The progress and development of the Society's guidebooks during the nineteenth century is described and the differences between these guidebooks and the non-official ones are examined. Finally, with the aid of Victorian children's books, I argue that the guidebooks can literally be considered as travel handbooks since a visit to the Gardens may be regarded as a journey of knowledge. Chapter five is an in-depth study of the zoological science of the Gardens. The scientific work of the Society is briefly described, starting with the Committee of Science and Correspondence, and the Proceedings of the Zoological Society of London. The Proceedings reports that base their findings on animals in the Gardens are then described together with minor detours into the history of taxonomy and morphology.
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Die Pflanzenqualität lässt sich durch Akklimatisationsmethoden gezielt beeinflussen. In der vorliegenden Arbeit wurden, speziell von Ficus benjamina und Chamaedorea elegans, die innere (Kohlenhydrate, Chlorophyll und Flavonole) und äußere Qualität (Morphologie, Habitus und Vitalität) im Kontext erfasst und interpretiert. Dazu wurde zunächst für beide Pflanzenarten eine neue Methode zur Bestimmung der Zuckergehalte (Glucose, Fructose, Saccharose) erarbeitet. Die Kultivierung der Pflanzen erfolgte in fünf aufeinanderfolgenden praxisüblichen Phasen der Wertschöpfungskette: Produktion, Lichtakklimatisation, Dunkeltransport, Regeneration und Innenraum. Diese simulierten Phasen zogen verschiedene Wachstumsbedingungen nach sich, die insbesondere den Wachstumsfaktor Licht betrafen und sich variantenbezogen unterschieden. Die Kohlenhydratgehalte sanken im Laufe der Wertschöpfungskette bei F. benjamina um 15 bis 30 % und bei Ch. elegans um 50 %. Es zeigte sich, dass Lichtintensitäten unter 350 µmol m-2 s-1 den Kohlenhydratgehalt negativ beeinflussten, dabei waren Unterschiede bei den Pflanzenarten zu beobachten. Darauf aufbauend wurden weitere Versuche durchgeführt, die eine exogene Zuckerapplikation (Konzentration 7,5 g l-1, 10 g l-1, 20 g l-1 Saccharose) über die Flüssigdüngung hinsichtlich der Wirkung auf den Kohlenhydratgehalt und die Vitalität der Pflanzen testeten. Auch hier unterschieden sich die geprüften Pflanzenarten in ihrer Reaktion. Vor allem für Chamaedorea elegans erwies sich eine Zuckerdüngung als vorteilhaft. Die vorliegende Arbeit liefert für Wissenschaft und Praxis eine umfassende und aktuelle Übersicht über die Möglichkeiten und Grenzen zur Beeinflussung der Pflanzenqualität und -vitalität mittels Lichtakklimatisation und Zuckerdüngung. Erstmalig wurde die Entwicklung der Kohlenhydratgehalte über einen längeren Untersuchungszeitraum, mit Blick auf die zentralen Kultivierungsphasen, für beide Innenraumbegrünungspflanzen aufgezeigt.
Plant quality can be influenced by acclimatisation. Most of the previous studies on plants for interior landscaping focused mainly on external quality. Therefore, this thesis presents the results of a study on Ficus benjamina and Chamaedorea elegans, investigating and analysing primarily inner quality characteristics (carbohydrates, chlorophyll, and flavonols). However, external quality characteristics (morphology, habitus, and vitality) were considered as well. In a first step, a new method was developed to determine the sugar content (fructose, glucose, sucrose) for both species. Cultivation of F. benjamina and Ch. elegans plants was carried out in five consecutive steps following standard practice of the value chain: production, light acclimatisation, transport in darkness, regeneration and interior spaces. These phases simulated different cultivation conditions, particularly varying light treatments. During the value chain the carbohydrate content (sugar and starch) in F. benjamina decreased 15 to 30 % and in Ch. elegans about 50 %. Light intensities below 350 µmol m 2 s-1 diminished carbohydrate concentrations depending on the plant species investigated. Based on these findings additional experiments were undertaken testing sugar supplied via the nutrient solution (7.5 g l-1, 10 g l-1 and 20 g l-1 sucrose). Both species investigated responded with different carbohydrate concentration and vitality. Sugar nutrition was particularly beneficial for Ch. elegans. This work provides a comprehensive and current overview of the capabilities and limitations to influence plant quality and vitality by light acclimatisation and sugar nutrition. For the first time, carbohydrate dynamics in interior plants has been studied in long term experiments in relation to their key cultivation stages for two important model species.

Abstract The purpose of the study was to examine the cold-induced effects on pineal and thyroid hormones, as well as the associations of these hormones with psychological performance and to determine how psychological performance could be affected by demographic, anthropometric, physiological or biochemical measures during cold acclimatisation. The feasibility of urinary melatonin (MT), rather than 6-sulphatoxymelatonin (aMT6s), as an indicator of MT secretion was also examined. In the laboratory study, seasonal cold acclimatisation, its effects on hormones and their associations with mood and cognition were assessed in 15 young urban subjects exposed to cold in winter or summer in bright or dim light. In the field study, the associations of mood and cognition with demographic, anthropometric, physiological and biochemical measures were determined in healthy, euthyroid subjects (n = 133) in Antarctica in the beginning and at the end of summer and winter seasons. In both seasons, simple task performance was consistently impaired in the cold in experimental and field conditions. In complex tasks, negative, positive and mixed effects were observed. In the experimental study, serum MT and thyroid hormone levels were positively associated with mood. MT was negatively associated with simple task performance. Free triiodothyronine (T3) and thyrotropin (TSH) had mixed effects on simple task performance. TSH was positively associated with complex task performance. In the field study, higher age was associated with impaired cognition, especially in complex task performance. Total T3 was positively associated with mood and total thyroxine (T4) with complex task accuracy. Both urinary MT and aMT6s were good indicators of MT secretion, but the variation was smaller for MT. In conclusion, the associations of serum MT, TSH and thyroid hormone levels with mood and cognition found in experimental and field conditions are consistent with the psychological changes associated with the onset and consequent stages of the previously established polar T3 syndrome. In the field study, cognition and mood were associated with subject’s age and gender, which seemed to affect the physiological changes during acclimatisation to cold and darkness in Antarctica
Tiivistelmä Tutkimuksen tarkoituksena oli selvittää kylmäaltistuksen aiheuttamia muutoksia käpy- ja kilpirauhasen hormonien tasoissa, hormonien yhteyttä psyykkiseen toimintakykyyn sekä demografisten, antropometristen, fysiologisten ja biokemiallisten tekijöiden yhteyttä psyykkiseen toimintakykyyn kylmäakklimatisaation aikana. Lisäksi verrattiin virtsan melatoniinin (MT) ja 6-sulfatoksimelatoniinin (aMT6s) soveltuvuutta MT-erityksen kuvaajina. Laboratoriotutkimuksessa selvitettiin talveen liittyvää kylmäsopeutumista, sen vaikutusta hormonitasoihin ja näiden yhteyttä mielialaan ja älylliseen toimintakykyyn 15 nuorella miehellä, jotka altistettiin kylmälle talvella ja kesällä sekä kirkkaassa että hämärässä valossa. Kenttäkokeessa Antarktiksella selvitettiin mielialan ja älyllisen toimintakyvyn sekä demografisten, antropometristen, fysiologisten ja biokemiallisten tekijöiden välistä yhteyttä terveillä henkilöillä (n = 133) kesä- ja talvikauden alussa ja lopussa. Suoriutuminen yksinkertaisista tehtävistä huononi kylmässä kesällä ja talvella sekä laboratorio- että kenttäoloissa. Kylmä vaikutti monimutkaisista tehtävistä suoriutumiseen vaihtelevasti. Laboratoriotutkimuksessa seerumin MT- ja kilpirauhashormonitasot korreloivat positiivisesti mielialan kanssa. MT korreloi negatiivisesti yksinkertaisista tehtävistä suoriutumisen kanssa. Vapaa trijodotyroniini (T3) ja tyrotropiini (TSH) korreloivat vaihtelevasti yksinkertaisista tehtävistä suoriutumisen kanssa. TSH korreloi positiivisesti monimutkaisista tehtävistä suoriutumisen kanssa. Kenttätutkimuksessa korkeampi ikä oli yhteydessä huonontuneeseeen älylliseen toimintakykyyn erityisesti monimutkaisissa tehtävissä. T3:n kokonaismäärä korreloi positiivisesti mielialan ja tyroksiinin (T4) kokonaismäärä monimutkaisista tehtävistä suoriutumisen kanssa. Sekä virtsan MT että aMT6s olivat hyviä MT-erityksen mittareita, mutta MT:ssa vaihtelu oli pienempää. Laboratorio- ja kenttäolosuhteissa havaitut MT:n, TSH:n ja kilpirauhashormonien yhteydet mielialaan ja älylliseen toimintakykyyn vahvistavat aiemmin havaittuja tuloksia polaarisen T3 -oireyhtymän synnystä ja oireyhtymän eri vaiheisiin liittyvistä psyykkisistä muutoksista. Kenttätutkimuksessa mieliala ja älyllinen toimintakyky olivat yhteydessä koehenkilön ikään ja sukupuoleen, jotka puolestaan voivat vaikuttaa fysiologisiin muutoksiin kylmään ilmastoon ja pimeyteen sopeutumisen aikana

Hårdgörning av trä syftar till att göra materialet hårdare. Detta går att åstadkomma genom komprimering, det komprimerade materialet tenderar dock att återgå mot sin ursprungsform då materialet utsätts för fukt om ingen låsning sker. Låsningen kan ske mekaniskt i en treskiktskonstruktion som motverkar träets fuktrörelser. Dessa skivor har dock visat sig vara instabila och tidigare försök har uppvisat deformationer i form av kupning. Denna undersökning syftar till att utreda förutsättningarna för att använda komprimerad asp samt att ta fram underlag för framtagning av en kommersiell produkt.

Praktiska tester har genomförts för att studera hårdhet, återfjädring och densitet hos det komprimerade virket. Vidare har treskiktsskivor tagits fram för att testa om det går att få en stabil konstruktion genom att variera tjockleken på spärrskiktet. Även skillnader i acklimatiseringstid och fuktkvotens inverkan för virkets återfjädring har studerats.

Resultaten visar på att aspens hårdhet efter komprimering blir i samma nivå som bok och ask, en låg fuktkkvot vid komprimering av materialet ger en låg återfjädring, komprimerat material har en längre acklimatiseringstid till jämviktsfuktkvot och materialet går att låsa tvärs fiberriktningen i en treskiktskonstruktion.

To make wood harder it can be densified. This can be achieved by compression, the compressed material tends to return to the original shape when it is exposed to moisture fluxations and if no form of fixation occurs. The fixation can be done mechanically in a three-layer panel construction which reduce movements in the timber. These panels have been found to be unstable and previous attempts have shown deformations in form of cupping. This study aims to evaluate the conditions for using compressed aspen wood, and to provide a basis for development of a commercial product.

Practical tests have been conducted to study hardness, springback and density of the compressed wood. In addition, three-layer panels have been developed to test whether it is possible to have a stable construction by varying the thickness of the buttom layer. Differences in acclimatisation time and the moisture contents effect on the springback has aslo been studied.

The results show that the hardness of aspen wood after compression is in equal levels with beech and ashes, a low moisture contet provides a low springback, compressed timber have a longer time for acclimatisation and it is possible to fixate the material in the direction across the grain in a three-layer panel construction.

Exposure to chronic hypoxia (CH) leads to ventilatory acclimatisation to hypoxia (VAH) which is a time-dependent increase in breathing. This study examined the role of the GABAA receptor in establishing VAH. Rats were exposed to CH or control (normoxic) conditions for 10 days during which the GABAA receptor antagonist, bicuculline, was infused systemically or directly into the nucleus of the solitary tract (NTS). Acute breathing trials were then performed to measure resting ventilation and ventilatory chemoreflexes. Systemic administration of bicuculline caused reductions in breathing during acute hypoxia and acute hypercapnia in the control but not the CH animals. Continuous infusion of bicuculline in to the NTS caused a reduction in the acute hypoxic ventilatory response in animals exposed to CH but not in the control animals. The results indicate that exposure to CH alters the GABAA-mediated regulation of acute ventilatory chemoreflexes both in the NTS and elsewhere in the brain.

Endosymbiotic photosymbionts, belonging to the dinoflagellate genus Symbiodinium, enable corals to succeed as dominant reef builders under ambient conditions, yet are also sensitive to anomalous changes in their thermal environment. Stressful temperatures cause photosynthetic damage to Symbiodinium, which can initiate lethal or sub-lethal coral bleaching. The capacity of Symbiodinium to resist and respond to stress (i.e. resilience) is crucial for the future persistence of corals. The aim of research presented in this thesis was to evaluate the influence of Symbiodinium population traits on the resilience of corals to warming seas. For within-type populations of Symbiodinium, spatial and temporal patterns of genetic diversity were investigated along with the potential for genetic adaptation and physiological acclimatisation to different thermal environments. Populations of the generalist Symbiodinium types C1, C2 and D (ITS1 rDNA) were used as a model system in the bleaching sensitive coral, Acropora millepora, on inshore reefs of the Great Barrier Reef (GBR). Genetic diversity and connectivity were estimated for Symbiodinium C2 populations using eight polymorphic microsatellite DNA markers. At the central GBR, Symbiodinium C2 assemblages were genotyped in more than 400 colonies of A. millepora sampled at 7 sites (0.4 to 13 km apart) across a 12 year period. Within-host and within-reef assemblages were genetically diverse (up to 7 alleles per microsatellite locus per coral colony), with significant structure observed at all spatial and temporal scales investigated. Differentiation among sites accounted for 19-27% of the total genetic variation and was consistent with restricted hydrodynamic dispersal of Symbiodinium and the nature of local disturbance regimes. Differentiation among sampling years accounted for a lesser 7% of the total genetic variation and was associated with significant coral mortality during bleaching and cyclone events. Bleached corals hosted less diverse Symbiodinium C2 assemblages than healthy corals, indicating that genotypes may be lost during bleaching-induced reductions in Symbiodinium densities. Such population bottlenecks were investigated in more detail by following changes in Symbiodinium C2 assemblages before and after a severe bleaching episode at sites in the southern GBR. A 10 % decline in reef-wide genetic diversity of Symbiodinium C2, including the loss of 16 alleles, was observed after the bleaching episode. The appearance of a few novel alleles after bleaching, combined with the high density of Symbiodinium on coral reefs, suggests that recovery of genetic diversity lost through bleaching is possible. However, if bleaching events become more frequent and severe, the genetic diversity of Symbiodinium populations could become eroded, especially as lost diversity is unlikely to be readily replenished by re-seeding from adjacent reefs. Conversely, limited genetic connectivity between reefs may have positive implications for populations by promoting adaptation to local environmental conditions. Adaptation of Symbiodinium populations was examined by comparing the thermal tolerance of Symbiodinium type C1 from two central GBR reefs that differ in summer maximum temperatures by ~2°C. Following acclimation to a common thermal environment, Symbiodinium C1 populations displayed heat stress responses that correlated with their native thermal environment, both in symbiosis with a cohort of A. millepora juveniles and in cell cultures. In symbiosis, Symbiodinium C1 from the cooler reef underwent chronic photoinhibition at an elevated temperature of 32°C, causing severe bleaching and partial mortality of juvenile coral hosts. In contrast, Symbiodinium C1 from the warmer reef thrived at 32°C, with high rates of photochemical efficiency and rapid growth of juvenile coral hosts. A second heat stress experiment demonstrated that adaptive variation in the thermal tolerance of Symbiodinium C1 populations was maintained after more than 30 asexual generations in culture. Pigment profiles of Symbiodinium C1 showed that levels of photoprotective pigment (β-carotene relative to chlorophyll a) were more than twofold greater in the population native to the warmer reef indicating a functional basis for variation in thermal tolerance. These results demonstrate that Symbiodinium types can adapt to local thermal environments and that this adaptation shapes the fitness of coral hosts. The contribution of physiological acclimatisation to adaptive variation in thermal tolerance was investigated during reciprocal transplantation of adult coral symbioses between the warm central and cool southern regions of the GBR. Throughout a year of transplantation, A. millepora-Symbiodinium D associations from the central GBR were exposed to gradually cooling temperatures and A. millepora-Symbiodinium C2 associations from the southern GBR were exposed to gradually warming temperatures. In both locations, native corals remained healthy and transplanted corals were healthy over initial months when temperatures remained within native thermal regimes. However, during winter, A. millepora-Symbiodinium D associations transplanted to the southern GBR bleached and the majority suffered whole or partial mortality at temperatures <1°C below their native minimum. Similarly, during summer, A. millepora-Symbiodinium C2 associations transplanted to the central GBR bleached and suffered whole or partial mortality at temperatures 1-2°C above their native maximum. At the central GBR during summer bleaching, mortality was preceded by a change in the dominant Symbiodinium type from C2 to D within transplanted corals. The strong interaction between genotype and environment observed for bleaching and mortality (as well as for parameters of growth and reproduction) re-affirm the importance of genetic adaptation in defining the thermal limits of A. millepora- Symbiodinium partnerships. These results likely reflect differences in the thermal tolerance among Symbiodinium types and populations, however variation between coral host populations may also exist. Findings presented in this thesis demonstrate that coral symbioses are adapted to their current thermal environments. Increases in thermal tolerance required for A. millepora symbioses to persist under warmer seas are dependent on continued genetic adaptation, as there is little potential for acclimatisation beyond current thermal regimes. Critical next steps to determine whether adaptation keeps pace with future warming include the application of functional genetic approaches to population genotyping and quantifying rates of adaptation for both Symbiodinium and coral hosts.

This study investigated two hypotheses. First, that chronic cocaine treatment would mimic the changes in breathing that are associated with ventilatory acclimatisation to chronic hypoxia (VAH). Second, that pre-treatment with a hypoxic stressor would bring about cross-sensitisation to cocaine. To address the first hypothesis, rats were exposed to either chronically hypoxic or chronically normoxic conditions and treated with either cocaine or saline for a 14 day period. Following this period, acute breathing trials were performed to measure resting ventilation and ventilatory chemoreflexes. The results demonstrated that chronic cocaine treatment did not induce the changes in breathing associated with VAH. To address the second hypothesis rats were exposed to a hypoxic stressor for 10 days (either intermittent hypoxia or chronic hypoxia) after which cocaine sensitisation was measured via locomotor sensitisation trials. The results demonstrated that cross-sensitisation between a hypoxic stress and cocaine was observed for intermittent but not chronic hypoxia.