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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Biochemical, biophysical and morphological studies of temperature acclimation in the intestine of the common carp (Cyprinus carpio, L.)

Lee, J. A. C. January 1987 (has links)
No description available.
2

Science and Colonial Culture: Scientific Interests and Institutions in Brisbane, 1859-1900

Clements, Helen Gail, n/a January 1999 (has links)
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.
3

The Role of GABAA Receptor-mediated Neurotransmission in Ventilatory Acclimatisation to Hypoxia

Phe, Balinda Siou Ing 26 February 2009 (has links)
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.
4

The Role of GABAA Receptor-mediated Neurotransmission in Ventilatory Acclimatisation to Hypoxia

Phe, Balinda Siou Ing 26 February 2009 (has links)
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.
5

Interactive Effects of Hypoxia and Cocaine Treatment on Ventilatory Chemoreflexes and Locomotor Sensitisation

Knight, Jeffrey 24 February 2009 (has links)
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.
6

Interactive Effects of Hypoxia and Cocaine Treatment on Ventilatory Chemoreflexes and Locomotor Sensitisation

Knight, Jeffrey 24 February 2009 (has links)
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.
7

Human cold exposure, adaptation and performance in a northern climate

Mäkinen, T. M. (Tiina M.) 23 May 2006 (has links)
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.
8

Knowledge and pleasure at Regent's Park : the gardens of the Zoological Society of London during the nineteenth century

Ņkerberg, Sofia January 2001 (has links)
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. / digitalisering@umu
9

Auswirkung von Lichtakklimatisation und Saccharosedüngung auf Kohlenhydratgehalt und Vitalität von Ficus benjamina und Chamaedorea elegans

Haas, Manuela 17 January 2017 (has links)
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.
10

Melatonin and thyroid hormones in the cold and in darkness:association with mood and cognition

Pääkkönen, T. (Tiina) 16 February 2010 (has links)
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.

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