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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.

Late season physiological adaptations of two syntopic araneid spiders

Markezich, Allan Louis. Riddle, Wayne A. January 1987 (has links)
Thesis (Ph. D.)--Illinois State University, 1987. / Title from title page screen, viewed August 16, 2005. Dissertation Committee: Wayne A. Riddle (chair), D. Reed Jensen, Steven A. Juliano, Charles F. Thompson, James N. Tone. Includes bibliographical references (leaves 103-118) and abstract. Also available in print.

Theoretical equations for describing steady state biological rates and their application in analysing physiological differences among animals

Borgmann, Uwe January 1973 (has links)
The rates of complex multi-enzyme systems, which may contain diffusion processes, can be written in a standard polynomial form. Approximation of this formula leads to the derivation of equations which provide a theoretical basis for the use of log-log plots (for rate-size and rate-substrate relationships), and Arrhenius plots (for rate-temperature relationships) in biology. Sharp discontinuities or "breaks" on such plots can be explained by summations of simple functions and the power to which these must be raised prior to summation. It has been found unnecessary to have large enthalpies (or activation energies) to produce sharp breaks on Arrhenius plots of the rates of complicated biological systems. / Science, Faculty of / Zoology, Department of / Graduate

Dark Adaptation of Second and Third Grade Children

Rohrer, Lois Young January 1940 (has links)
The purpose of the study is to determine the dark adaptation of second grade children in Denton, Texas.

Behavioural adaptive variation in the striped mouse Rhabdomys

Mackay, Megan Kirsten January 2017 (has links)
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy, 2017 / Under current and previous global climate change, environments are changing and have changed at a rapid rate. Species with the potential to undergo adaptive radiation are likely to survive environmental change. The genus Rhabdomys is widespread in southern Africa, occurring along the east-west rainfall gradient in South Africa. Rhabdomys may have undergone adaptive radiations in the past, which may have resulted in the current suite of species in various habitats of different aridity. Some Rhabdomys species also occur in sympatry in some locations in South Africa. The aim of my study was to investigate adaptive variation in Rhabdomys by studying the behaviour of 5 populations, representing 3 Rhabdomys species, across South Africa. Using selected taxa, my approach was, firstly, to describe variation in two traits, personality and spatial cogntion, well known for showing environmentally-linked (i.e. adaptive) variation. Secondly, I manipulated the development of exploratory and anxiety behaviour to assess the limits of the adaptive variation (i.e. test the nature of the reaction norm of the characters measured). I first established the taxon-level personality of 4 taxa (2 sympatric) in 5 standard behavioural tests. Generally, the semi-desert living R. pumilio was the boldest together, surprisingly, with R. d. dilectus occurring in grasslands of central South Africa, contradicting previously published results. Comparatively, R. bechuanae from central South Africa and R. dilectus from far north-eastern South Africa, also occurring in grasslands were less bold, even though R. bechuanae is sympatric with R. dilectus in central South Africa. My data indicate adaptive variation at the extreme populations and possibly character displacement in the sympatric populations. In the next chapter, I investigated whether early rearing environment shapes exploratory behaviour and anxiety responses of R. pumilio and R. bechuanae. I predicted that using an interspecies cross-fostering protocol would reveal a gene x environment interaction on behaviour, so that fostered offspring would display an intermediate behaviour phenotype compared to their non-fostered siblings. I showed that a novel rearing environment mostly did not influence the adult behaviour of cross-fostered inidividuals. This indicates genetic constraints on exploratory behaviour and anxiety responses. Next, I tested whether physical rearing environment shapes exploratory behaviour and anxiety responses. I reared semidesert R. pumilio, sympatric R. bechuanae and R. dilectus and allopatric R. bechuanae under either no cover or high cover for 2 generations. The taxa were mostly similar and altering the phyical housing condition did not alter behaviour, but there were small differences between the taxa in exploratory behaviour. In the final experimental chapter, I established whether the environment predicts the spatial cognition in semi-desert R. pumilio, sympatric R. bechuanae and R. dilectus and an allopatric population of R. dilectus from far north-eastern South Africa. The populations showed very similar performance in a modified Barnes maze, indicating a possible phylogenetic constraint on spatial cognition. Overall, my study suggests that there is adaptive variation in personality but not spatial cognition. In contrast to previous studies in the genus, alterations to the social and physical environments failed to separate out genetic and environmental effects (i.e. reaction norm) that would potentially provide the mechanisms for adaptive variation within and between species. The similarity in spatial cognition between taxa and similar responses to environmental modification indicate phylogenetic constraints on traits that were predicted to vary geographically. / XL2018

Efficient and Portable Middleware for Application-level Adaptation

Rao, Deepak 23 May 2001 (has links)
Software-intensive systems operating in a shared environment must utilize a "request, acquire and release" protocol. In the popular client-server architecture resource-poor clients rely on servers for the needed capabilities. With mobile clients using wireless connectivity, the disparity in resource needs can force the consideration of adaptation by clients, leading to a strategy of self-reliance. Achieving self-reliance through adaptation becomes even more attractive in environments, which are dynamic and continually changing. A more comprehensive strategy is for the mobile client to recognize the changing resource levels and plan for any such degradation; that is, the applications in the mobile client need to adapt to the changing environment and availability of resources. Portable adaptation middleware that is sensitive to architecture and context changes in network operations is designed and implemented. The Adaptation Middleware not only provides the flexibility for the client applications to adapt to changing resources around them, but also to changing resource levels within the client applications. Further, the Adaptation Middleware imposes few changes on the structure of the client application. The Adaptation Middleware creates the adaptations; the client remains unaware and unconcerned with these adaptations. The Adaptation Middleware in this study also enables a more informative cost estimation with regard to applications such as mobile agents. A sample application developed using the Adaptation Middleware shows performance improvements in the range of 31% to 54%. A limited set of experiments show an average response time of 68 milliseconds, which seems acceptable for most applications. Further, the Adaptation Middleware permits increased stability for applications demonstrating demand levels subject to high uncertainty. / Master of Science

Political culture, governance and climate change adaptation : case study of South Korea

Park, Keumjoo January 2013 (has links)
Many scholars highlight the essence of a participatory governance approach to climate change adaptation and the positive impact of allowing multiple actors participation in the process of decision making as a determinant for successful adaptation to climate change. However, political culture in some societies does not support participation, and people are neither interested nor even aware of political actions. There are very few studies carried out that examine cultural, especially political cultural, influences over governing climate change adaptation. In response to this academic gap, this research aims to investigate how political culture influences a governance approach to climate change adaptation. Using an empirical case study of the process of formulating national climate change adaptation policies in South Korea, this study examines the way decisions are made about climate change policies under ‘dominant bureaucratic’, ‘authoritarian’ and ‘weak participant’ political cultures and investigates how such political cultures will hamper or encourage a governance approach to effective climate change adaptation. This study therefore advances knowledge about how political culture influences climate change adaptation. It provides a basis for comparative analyses of other political cultures in different regions and will enable scholars to understand the challenges that particular forms of governance hold for promoting climate change adaptation.

Robust decentralized adaptive control in the manipulator control problem

Bundell, G. A. January 1985 (has links)
No description available.

The relationship between climate and leaf shape in the Agave cerulata complex.

Burgess, Tony Lambard. January 1988 (has links)
Agave adaptation to aridity is examined, comparing trends among phylads, clines in Deserticolae taxa of Baja California, and variation in A. deserti along an elevational gradient. Agave physiology is reviewed and recent evolutionary scenarios are discussed. Tentative hypotheses predict characteristics of Agave leaves and rosettes in arid climates. A study of bioclimatology in the Vizcaino Region of Baja California follows, aimed at defining aspects of a subtropical arid climate that are relevant to a plant. The Vizcaino Region is described in terms of its physiography, vegetation physiognomy and floristics. Ombrothermic diagrams and juxtaposed graphs relate temperature and rainfall at stations throughout the region. Temperature regimes are compared using the 5th, 25th, 75th, and 95th percentiles of their respective distributions of monthly means, and subregional groups with similar regimes are defined. Conditions when soil moisture is available are examined by segregating 'wet' months with rainfall totals of 5 mm or more. Thermal distributions of wet months are compared with respect to their shapes and to temperatures delimiting the central two-thirds of wet months. Patterns in mean annual precipitation are presented. Variables are derived to estimate stress imposed on plants by drought. Median annual precipitation deficit, defined as the difference between total annual potential evapotranspiration and total annual rainfall, expresses the stress typically experienced by plants. The 90th percentile of potential evapotranspiration of dry intervals estimates the severity of droughts that longer-lived perennials survive. Each derived climate variable shows a different geographic pattern. Variance in leaf measurements from collection sites throughout the range of Agave cerulata is studied with a principal components analysis. Leaf characters associated with the major components of variance together with leaf volume/surface ratios are used as dependent variables in multiple regression equations with climate variables, which are estimated for each collection site. As the precipitation deficit increases, leaf size generally decreases, but where the longest droughts are most stressful, leaves tend to be larger. Leaf volume/surface is coupled with leaf size. When size variables are included in regressions, higher volume/surface is associated with more extreme cold, cooler summers, and warmer winters. Warmer summers, higher precipitation deficits, and more warm-season storms are correlated with higher length/width ratios. Larger basal surfaces occur in conjunction with higher precipitation deficits, warmer temperatures, and less warm-season rainfall.

The effects of retirement upon identity development

Doyle, Joanne Louise January 1999 (has links)
No description available.

Regulation of immune receptor functional responses by G protein-coupled receptor kinases (GRKs) and arrestins

Mariggio, Stefania Pasqua January 2001 (has links)
No description available.

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