Tolerance to anesthetic drugs is mediated partially by homeostatic mechanisms that attempt to restore normal neural excitability. The BK-type Ca2+-activated K+ channel, encoded by the slo gene, plays an important role in this neural adaptation. In Drosophila, a single sedative dose of the organic solvent anesthetic benzyl alcohol induces dynamic spatiotemporal changes in histone H4 acetylation across the slo regulatory region and leads to slo induction and tolerance. Mutations ablating the expression of slo also block the acquisition of tolerance, whereas activating the expression of a slo transgene results in resistance to drug sedation. Moreover, artificially inducing histone acetylation with the histone deacetylase inhibitor causes similar acetylation changes, slo induction, and functional tolerance to the drug. Histone acetylation changes occur over two highly conserved non-coding DNA elements, 6b and 55b, of the slo control region. To investigate the function of these two elements, I generated individual knockout mutants by gene targeting. Both knockout alleles are backcrossed into the CS wild type background. The 6b element seems to repress slo induction after drug sedation, because the 6b knockout allele overreacts to the drug. Compared to the wild type, 6b knockout allele shows a much greater slo message induction after drug sedation, it also displays stronger enhancements in seizure susceptibility and following frequency. In addition, the 6b deletion causes a persistent tolerance for at least a month, while tolerance only lasts about 10 days in wild type flies. My investigation also indicates that the 55b element limits basal slo expression in muscle. Finally, to investigate if the particular histone acetylation spikes are required for drug-induced slo induction and tolerance, I tether the histone-modifying enzymes, HDAC or HAT, to the 6b and 55b DNA elements, respectively. I observe that the positioning of an HDAC on these two elements blocks drug-induced slo induction and the development of tolerance. Therefore, histone acetylation across slo control region is required for the activation of slo and the acquisition of tolerance. / text

The variogram plays a central role in the analysis of geostatistical data. A valid variogram model is selected and the parameters of that model are estimated before kriging (spatial prediction) is performed. These inference procedures are generally based upon examination of the empirical variogram, which consists of average squared differences of data taken at sites lagged the same distance apart in the same direction. The ability of the analyst to estimate variogram parameters efficiently is affected significantly by the sampling design, i.e., the spatial configuration of sites where measurements are taken. In this paper, we propose design criteria that, in contrast to some previously proposed criteria oriented towards kriging with a known variogram, emphasize the accurate estimation of the variogram. These criteria are modifications of design criteria that are popular in the context of (nonlinear) regression models. The two main distinguishing features of the present context are that the addition of a single site to the design produces as many new lags as there are existing sites and hence also produces that many new squared differences from which the variograrn is estimated. Secondly, those squared differences are generally correlated, which inhibits the use of many standard design methods that rest upon the assumption of uncorrelated errors. Several approaches to design construction which account for these features are described and illustrated with two examples. We compare their efficiency to simple random sampling and regular and space-filling designs and find considerable improvements. (author's abstract) / Series: Forschungsberichte / Institut für Statistik

published_or_final_version / Psychology / Master / Master of Philosophy

It has been proposed to use heavy ion beams with energies around 10 MeV/amu, masses around 200, and average charges of 1+ as a driver for inertial fusion reactor. Current designs require the beams to travel through a region where the background gas pressure is several milli-torr. Thus, it is important to assess the rate at which the charge state of an incident beam evolves while passing through the background gas. The first objective of this project is to study the dependence of cross sections for multi-electron loss on target atomic number by using 6 MeV/amu Xe18+ ions and to compare the results with the n-body Classical Trajectory Monte Carlo calculations. A secondary objective of this project is to determine the extent to which the cross sections for molecular targets can be represented as sum of the cross sections for their atomic constituents. Cross sections for loss of one through eight electrons from 6 MeV/amu Xe18+ in single collisions have been measured with noble gas targets. The target Z-dependence of the total loss cross section was found to be well represented by two straight line segments. The cross section for He and Ne define one straight line segment and those for Ar, Kr and Xe define the other, where exhibits a smaller slope. The predictions of n-CTMC calculations are in good agreement with the measured total electron loss cross sections. A semiempirical fitting procedure based on the independent electron approximation provided a reasonably good representation of the individual cross sections for all of the noble gas targets. Additional measurements performed with a variety of molecular targets provided a rigorous test of cross section additivity and showed that the additivity rule works well for electron loss from heavy ions in the present energy and charge regime. A semiempirical calculation based the IEA shows that the average most probable impact parameter for electron loss is much smaller than the target molecular bond length. This result is believed to account for the finding of the insensitivity of the electron loss cross section to molecular structure.

No description available.

People with substance dependence show maladaptive approach responses toward stimuli related to their drug of addiction. Reducing the motivational salience of these appealing but maladaptive stimuli could decrease these inappropriate approach responses. Tasks that involve response inhibition influence the affective valence of stimuli, such that previously inhibited items are disliked compared to never-inhibited items. It is not clear, however, whether this effect can be harnessed to develop interventions to decrease the maladaptive motivational salience of addiction-related stimuli. To lay the groundwork for such an intervention, I first determined that people in treatment for substance dependence showed affective devaluation of previously-inhibited stimuli (Experiment 1). Because adolescence is associated with high risk of illegal substance use, I then examined the magnitude of the inhibitory devaluation effect in a group of adolescents from an adverse background (Experiment 2). Devaluation of inhibited stimuli increased significantly with age, suggesting that the effect occurs more strongly as the brain matures. Drug-related stimuli are extremely motivationally salient to people with substance dependence. Experiments 3-6 examined the affective consequences of inhibition for different types of motivationally salient stimuli: geometric images associated with monetary gains or losses, or sexually-appealing images. Finally, I determined that inhibition affects not only a stimulus’ affective valence, but also its motivational value. Heterosexual male participants who inhibited images of attractive females were later less likely to press a key in order to see more images of that type than participants who did not inhibit these images (Experiment 7). Taken together, this evidence suggests that computer-based tasks involving inhibition may be useful for decreasing the affective and motivational salience of drug-related stimuli in substance-dependent individuals.

Migratory birds face the distinct challenge of travelling between widely separated and environmentally distinct areas for their breeding and non-breeding periods. They may be faced with different pressures at different points in their life cycle, and a solid understanding of the drivers of individual fitness and population demography is crucial to understanding the ecological and evolutionary trajectories of their populations. In this thesis, I combine long-term data and experimental manipulations to study migratory patterns and arrival dynamics, density dependence, and reproductive behaviour in a long-distance migratory bird, the American redstart. First, I show that non-breeding season weather is associated with redstart phenology on the breeding grounds. Greater winter rainfall corresponds to earlier arrival and egg-laying dates at both the population and individual level, indicating that individual birds may be able to adjust their phenology in response to conditions in winter. Furthermore, I demonstrate these associations independently at two breeding populations at opposite sides of the redstart breeding range and their corresponding putative non-breeding areas: greater rainfall in Jamaica and Mexico was associated with advanced redstart phenology in Ontario and Alberta, respectively. Second, I performed a manipulation experiment to delay the arrival of male redstarts to the breeding grounds. I show that delayed males suffer reduced fledging success in comparison to early-arriving males that bred early or late, but equivalent success in comparison to males that arrived and bred late. These results provide evidence against the importance of either timing or individual quality, but instead suggest that other aspects of quality, namely mate and territory quality, may be important factors driving the success of early-arriving males. Third, I examine the consequences of density dependence for reproductive success and mating behaviour in a population of redstarts for which I showed density-dependent population growth over a period of 11 years. Greater breeding density, both at an annual scale and at a local scale, was associated with reduced success and greater paternity loss. Overall, my findings contribute to a broader understanding of the selective pressures and regulatory mechanisms acting on migratory birds, from the individual up to the population level. / Thesis (Ph.D, Biology) -- Queen's University, 2012-09-25 13:17:33.172

No description available.

This study explored the effects of cognitive style and expected evaluation on creativity. Past research has shown that an expectation of evaluation can have a negative impact on creativity, and those individuals classified as field-independent rather than field-dependent are more likely to have higher creativity scores. An interaction between expected evaluation and cognitive style was hypothesized. Participants created a collage to measure creativity, either with or without an expectation of evaluation, and then cognitive style was measured. The hypothesis was partially supported. The more field-independent an individual, the higher the creativity score. Those in the evaluation condition scored higher in creativity than those in the non-evaluation condition, but this effect disappeared when controlling for time and previous art experience. The effect of expected evaluation is discussed in terms of the experimental situation and the conceptualization of motivation. Further investigations of cognitive style and motivational conditions are suggested. / Department of Educational Psychology

While the phenotypic effects of sexual selection have been well studied, the consequences for population mean fitness remain unclear. Additionally, there is a need to more fully characterize how various forms of inter- and intrasexual selection combine to affect the evolution of traits under sexual selection. Here, I address these issues as they relate to male territoriality in Drosophila serrata, a model system for the study of female preference for male pheromones. First, I demonstrate that territoriality occurs and is a likely component of male sexual fitness. Results from a phenotypic manipulation indicate that territorial success was also condition-dependent, and that sexual selection against low condition males tended to be stronger given a high opportunity for territory defense. Territorial success depended on body size but not on pheromones. How this and other components of male mating success interact to affect trait evolution and population mean fitness remains an important area for future study.