Biogeographic patterns of animals are shaped by biotic interactions, such as competition, and by abiotic factors, such as climate. Mountain Chickadees (Parus gambeli) and Juniper Titmice (Parus ridgway) are permanent residents of regions of western North America and are ecologically similar, but have different northern range limits. l measured several physiological variables, including basal metabolic rate (BMR), peak metabolic rate (PMR = maximal thermogenic capacity), metabolic response to varying environmental temperature (MRT), evaporative water loss (EWL), and daily energy expenditure (DEE) for summer-and winter-acclimatized Mountain Chickadees and Juniper Titmice to determine if seasonal and interspecific variation in cold tolerance and thermogenic ability shape the northern range distribution of these two species. In addition, I examined the ecological consequences of nocturnal hypothermia and cavity roosting in seasonally acclimatized Mountain Chickadees and Juniper Titmice. Winter birds tolerated colder test temperatures than summer birds for both species This improved cold tolerance was associated with a significant increase in PMR in winter chickadees (27.1 %) and titmice (114%) compared to summer. BMR was significantly higher in winter birds (16.0%) compared to summer birds for both species. BMR and PMR were significantly higher for chickadees compared to titmice in both summer and winter. Winter chickadees were able to withstand colder test temperatures than winter titmice. The Mountain Chickadee's lower critical temperature is lower than the Juniper Titmouse's in summer and in winter. The Mountain Chickadee's upper critical temperature is also lower than the Juniper Titmouse's and chickadees also had significantly higher evaporative water loss rates compared to titmice. Seasonal acclimatization in Mountain Chickadees involves insulatory as well as metabolic changes. For Juniper Titmice winter acclimatization appears to be primarily a metabolic process. The laboratory metabolism data for activity costs associated with DEE revealed that foraging energy requirements were not significantly higher than alert perching energy requirements. DEE was significantly higher (P<0.05) in winter-acclimatized chickadees and titmice compared to their summer counterparts. The marked increase in calculated DEE in winter birds compared to summer contrasts a pattern of increased DEE in the breeding season for several avian species. The data from this study indicate that the northern range limit of small birds can be limited by energetic and water balance demands.

Cultivated chickpea (Cicer arietinum) has a narrow genetic base making it difficult for breeders to produce new elite cultivars with durable resistance to major biotic and abiotic stresses. As an alternative to genome mapping, microarrays have recently been applied in crop species to identify and assess the function of putative genes thought to be involved in plant abiotic stress and defence responses. In the present study, a cDNA microarray approach was taken in order to determine if the transcription of genes, from a set of previously identified putative stress-responsive genes from chickpea and its close relative Lathyrus sativus, were altered in chickpea by the three abiotic stresses; drought, cold and high-salinity. For this, chickpea genotypes known to be tolerant and susceptible to each abiotic stress were challenged and gene expression in the leaf, root and/or flower tissues was studied. The transcripts that were differentially expressed among stressed an d unstressed plants in response to the particular stress were analysed in the context of tolerant/susceptible genotypes. The transcriptional change of more than two fold was observed for 109, 210 and 386 genes after drought, cold and high-salinity treatments, respectively. Among these, two, 15 and 30 genes were consensually differentially expressed (DE) between tolerant and susceptible genotypes studied for drought, cold and high-salinity, respectively. The genes that were DE in tolerant and susceptible genotypes under abiotic stresses code for various functional and regulatory proteins. Significant differences in stress responses were observed within and between tolerant and susceptible genotypes highlighting the multiple gene control and complexity of abiotic stress response mechanism in chickpea. The annotation of these genes suggests that they may have a role in abiotic stress response and are potential candidates for tolerance/susceptibility.

<p>A problem with cold pilgered tubes for OCTG applications is that they can get anisotropic properties with regard to yield strength. One source of anisotropy is texture that is developed during the cold deformation. EBSD measurements have been made on several austenitic stainless steels with different deformations to see what influence the composition has on the texture formation. The same measurements were used to study the influence of grain size on texture formation. The conclusion was that the composition can have an impact on the texture and hence has potential to also affect the anisotropy. The differences in texture cannot be associated with a specific alloying element, but is rather a synergetic effect. It was also concluded that grain structure has no strong influence on texture formation. An evaluation of three different tool designs used for cold pilgering was made. The designs evaluated are referred to as design A, B and C. EBSD measurements showed large deviations in texture in the middle of the wall compared to close to the surface of pilgered OCTG. However, the measurements showed no large differences between the three designs and the texture could not be coupled to the anisotropy.</p>

Thesis (M.S.)--Miami University, Dept. of Zoology, 2007. / Title from first page of PDF document. Includes bibliographical references (p. 17-20).

Upon encountering stress conditions, cells must rapidly alter their gene expression and re-model their RNA complement to deal with the changing environment. As a consequence, both new RNA transcription as well as RNA degradation must take place. Accordingly, the RNA degradative machinery may adjust to the changes in RNA metabolism. Thus, a study of the response of the three major degradative exoribonucleases in Escherichia coli, polynucleotide phosphorylase, RNase II, and RNase R, to stress is of significant importance. RNase R, a processive 3' to 5' exoribonuclease, is unique among the known E. coli exoribonucleases in its ability to digest through RNAs containing extensive secondary structure without the aid of a helicase. In vivo, RNase R plays important roles in quality control of stable RNA, decay of mRNA with extensive repetitive extragenic palindromic (REP) sequences, cell-cycle regulated degradation of tmRNA in Caulobacter crescentus, as well as processing of rRNA under low temperature in P. syringae. In this dissertation, RNase R was shown to be unusual among the E. coli exoribonucleases in its dramatic response to a variety of stress conditions. Elevation of RNase R activity by as much as 10-fold was observed in response to entry into stationary phase, starvation and cold shock, and an ~3-fold increase was seen during growth in minimal medium compared to rich medium. The elevation in RNase R activity was associated with an increase in RNase R protein. Phenotypes of rnr mutants were also investigated, and RNase R was found to contribute to cell growth and viability. Further investigation of the regulation of RNase R during stress, primarily in stationary phase, revealed a novel regulation mechanism. Despite the large increase in RNase R protein and activity in stationary phase, rnr message actually decreased to only ~14% of its level in exponential phase. Further study revealed that RNase R is highly unstable in exponential phase and becomes stabilized during stationary phase, cold shock, and in minimal medium. Investigation of proteolysis on the unusual instability of RNase R indicated that both Lon and ClpXP play a role. In the absence of Lon, RNase R stability is increased ~10-fold. Based on these results, I propose that the increase in RNase R during stress is due to its enhanced stability under those conditions.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Restricted until May 2006. Includes bibliographical references.

The first and main part of this thesis concerns the quantization of the transverse transport in diverse periodic quantum systems. From a theoretical point of view, the Hall conductivity's quantization may be understood at the single-particle level in terms of topological invariants. In periodic media such as crystals, the single-particle energy spectrum depicts a specific band structure. A modern approach, based on topology and differential geometry, consists in assigning an abstract mathematical object, a fibre bundle, to each energy band. The fibre bundle's topology is measured by a topological invariant, called the Chern number, which only takes integral values. Surprisingly, the transverse conductivity can be expressed as a sum of Chern numbers. In this work, one provides a rigorous derivation of this fact and one presents several methods which allow the numerical and analytical computation of the Chern numbers for diverse systems. The first original study concerns the physics of ultracold atoms trapped in optical lattices. These very popular experimental setups, which are currently designed in several laboratories worldwide, allow for the exploration of fundamental problems encountered in modern physics. In particular atoms trapped in optical lattices reproduce with a very high accuracy the physics of the Hubbard-type models which describe a huge variety of condensed matter phenomena, such as high-Tc superconductivity and the Mott quantum phase transition. Particularly interesting is the possibility to create artificial magnetic fields in optical lattices. Generated by complex laser configurations or by rotation of the trap, these artificial fields allow the simulation of electronic systems subjected to intense magnetic fields. In this thesis, one explores the possibility of a quantum Hall-like effect for neutral particles in such arrangements. In particular one focuses on the exotic situation in which non-Abelian gauge potentials are generated in the system. In these interesting arrangements, the atomic hoppings are assisted by external lasers and are described by non-commutating translation operators. The non-Abelian fields which are generated in these systems are well known in high-energy physics, where they play a key role in modern theories of fundamental interactions. Thereafter, our study of the IQHE in periodic systems concerns quantum graphs. These models which describe the propagation of a quantum wave within an arbitrary complex object are extremely versatile and hence allow the study of various interesting quantum phenomena. Quantum graphs appear in diverse fields such as solid state physics, quantum chemistry, quantum chaology and wave physics. On the other hand, in the context of quantum chaology, graphs have been the vehicle to confirm important conjectures about chaos signatures. In this thesis, one studies the spectral and chaological properties of infinite rectangular quantum graphs in the presence of a magnetic field. One then establishes the quantization of the Hall transverse conductivity for these systems. The second part of the thesis is devoted to the physics of interacting atoms trapped in optical lattices and subjected to artificial gauge potentials. One explores the Mott quantum phase transition in both bosonic and fermionic optical lattices subjected to such fields. The optical lattices are described through the Hubbard model in which the dynamics is ruled by two competing parameters: the interaction strength U and the tunneling amplitude t. The Mott phase is characterized by a commensurate filling of the lattice and is reached by increasing the ration U/t, which can be easily achieved experimentally by varying the depth of the optical potential. In this thesis one studies how this quantum phase transition is modified when the optical lattice is subjected to diverse artificial gauge potentials. Moreover, one shows that vortices are created in bosonic optical lattices in the vicinity of the Mott regime. The vortices are topological defects in the macroscopic wave function that describes the superfluid. One comments on the vortex patterns that are observed for several configurations of the gauge potential. %%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%% La physique statistique quantique prédit l’émergence de propriétés remarquables lorsque la matière est soumise à des conditions extrêmes de basses températures. Aujourd’hui ces nouvelles phases de la matière jouent un rôle fondamental pour les technologies actuelles et ainsi méritent d’être étudiées sur le plan théorique. Dans le cadre de ma thèse, j’ai étudié l’effet Hall quantique qui se manifeste dans des systèmes bidimensionnels ultra froids et soumis à des champs magnétiques intenses. Cet effet remarquable se manifeste par la quantification parfaite d’un coefficient de transport appelé conductivité de Hall. Cette grandeur physique évolue alors sur divers plateaux qui correspondent à des valeurs entières d’une constante fondamentale de la nature. D’un point de vue théorique, cette quantification peut être approchée par la théorie des espaces fibrés qui permet d’exprimer la conductivité de Hall en termes d’invariants topologiques. Nous explorons l'effet Hall quantique pour différents systèmes en nous appuyant sur l’interprétation topologique de la quantification de la conductivité de Hall. Nous démontrons ainsi que l’effet Hall quantique se manifeste aussi bien dans les métaux que dans les graphes quantiques et les réseaux optiques. Les graphes quantiques sont des modèles permettant l’étude du transport dans des circuits fins, alors que les réseaux optiques sont des dispositifs actuellement réalisés en laboratoire qui piègent des atomes froids de façon périodique. Considérant différents champs magnétiques externes et variant la géométrie des systèmes, nous montrons que cet effet subit des modifications remarquables. Notamment, l’effet Hall quantique est représenté par des diagrammes des phases impressionnants : les multiples phases correspondant à la valeur entière de la conductivité de Hall se répartissent alors dans des structures fractales. De plus, ces diagrammes des phases se révèlent caractéristiques des différents systèmes étudiés. D’autre part, nous étudions la transition quantique de Mott dans les réseaux optiques. En augmentant l’interaction entre les particules, le système devient isolant et se caractérise par le remplissage homogène du réseau. Nous étudions également l’apparition de tourbillons quantiques lorsque le système est soumis à un champ magnétique au voisinage de la phase isolante.

It has been demonstrated that EGCG and caffeine, naturally present in green tea, have thermogenic properties in thermoneutral conditions. The purpose of this study was to quantify the effect of the combined ingestion of EGCG/caffeine on thermogenic responses during a 3h mild cold exposure. Eight healthy males (22± 1 y) were exposed in a randomized, cross over, single blinded fashion to the cold (liquid conditioned suit perfused with 15°C water), after ingesting either a placebo (CON) or an extract of 1600mg of EGCG and 600mg of caffeine (EXP). Thermic, metabolic and electromyographic measurements were monitored at baseline and during cold exposure. After 180min of cold exposure, shivering intensity was significantly reduced by ~32% in EXP condition compared to CON. Area under the curve calculations for total shivering intensity was also reduced by ~21% in EXP (457±99 %MVC.min) compared to CON (361±81 %MVC.min; p=0.007). In contrast, the total area under curve of VO2 was ~25% higher in EXP (33.3±5.5 L O2) compared to CON (25.3±5.1 L O2; p=0.03). Total Heat production (Hprod) also increased by about 11% in the EXP condition (1535±112 kJ) compared to control (1372 ±106 kJ; p=0.002). The decrease in shivering activity combined with an increase in VO2 and Hprod, following the ingestion of EGCG and caffeine in the cold, indicates that nonshivering thermogenesis pathways can be significantly stimulated in adult humans.

Graduation date: 1992

The cost of new cultivar development is high due to long juvenile periods and large tree size in tree fruit breeding programs. For apples, sour cherries, and saskatoon berries, grafting seedling scions onto the tips of branches of mature plants was hypothesized to shorten the juvenile period and reduce land use under the Canadian prairie conditions. For apples, a tip grafting system (tip grafting onto mature crabapple rootstocks) was compared with the traditional grafting system (grafting onto young Ottawa 3 rootstocks). Apple scions of Golden Delicious, McIntosh, and SK Prairie Sun which exhibit a range of inherent cold hardiness, were grafted in the spring of 2001. Over a two year period, winter survival of the scions was improved by 37% by the tip grafting system as compared to the traditional grafting system making it not feasible for evaluation of cold hardiness of scions. Vegetative growth of scions approximated the rootstocks on which the scions were grafted. Winter survival was highly correlated with shoot growth cessation (r = +0.83) and terminal bud stage (r = +0.85) observed around the time of first frost. Juvenile seedlings of saskatoon berry and sour cherry hybrids were tip grafted onto mature plants of their own species in the spring of 2000. After two growing seasons, the tip grafting system in sour cherries had reduced flowering by 69.7%, shoot length by 84%, and shoot diameter by 76% compared with the juvenile seedlings on their own roots (scion donors). Tip grafting saskatoon berry seedlings increased flowering by 68%, shoot length by 257%, and shoot diameter by 42% compared with scion donors. For sour cherries, the tip grafting system reduced winter dieback by 99.6%, hastened terminal bud development and leaf drop compared with the scion donors. Tip grafting of saskatoon berry seedlings had little effect on terminal bud development and cold hardiness of scions perhaps due to the cold hardy character of this species. For apples and sour cherries, the tip grafting system tested in this study enhanced cold hardiness of scions when combined with the appropriated rootstocks and may be useful for maintaining germplasm that otherwise would not be hardy in northern locations.