Thesis (Ph.D.)--University of Western Sydney, 2009. / A thesis presented to the University of Western Sydney, College of Arts, Centre for Cultural Research, in fulfilment of the requirements for the degree of Doctor of Philosophy. Includes bibliographies.

This series of experiments developed novel paradigms involving the integration of conventional and ethologically relevant forms of reinforcement in the study of fear conditioning in rats. Experiment 1 compared the effects of foot shock, immobilization and predator exposure, alone and in combination, on the expression of conditioned fear memory and extinction. The combination of all 3 reinforcers produced a significantly stronger fear memory and greater resistance to extinction, compared to when each reinforcer was administered alone. Furthermore, whereas conditioning with foot shock, alone, resulted in rapid extinction of the fear memory, the combination of immobilization and cat exposure, or all 3 reinforcers together, produced a robust extinction resistant fear memory. Experiment 2 explored the effects of giving extinction trials every two versus every seven days. This experiment demonstrated extinction when the trials were given every 2 days, with no evidence of extinction when trials were given every 7 days. Experiment 3 focused on extending predator-based conditioning to enhance the development of cue-based fear conditioning. Rats were administered multiple predator-based conditioning trials in one session to enhance the formation of both contextual and cue-based fear memories. Experiment 4 tested the hypothesis that hippocampal involvement during learning is necessary for predator-based contextual, but not cued, fear memory. This work provided support for this hypothesis with the finding of impaired contextual memory, with no effect on cued memory, in rats that had a pharmacological suppression of hippocampal activity during fear conditioning. Experiment 5 developed an entirely novel form of inhibitory avoidance conditioning. This work demonstrated that rats learned to avoid entering a place which was paired with immobilization and predator exposure. Experiment 6 investigated the effects of sleep deprivation occurring prior to fear conditioning on the expression of fear memory. This experiment showed that pre-training sleep deprivation blocked the development of contextual (hippocampal-dependent), but not cue (hippocampal-independent), fear memory. Overall, this series of experiments established the groundwork to use ethologically relevant stimuli, including predator exposure, in conjunction with conventional reinforcers, such as foot shock and immobilization, to advance our understanding of the neurobiology of emotional memory.

The ecological impact of past extinction events is one of the central issues in paleobiology. In face of present environmental changes, a better understanding of past extinctions will enable us to identify the magnitude of biodiversity crises and their underlying processes. The Late Neogene was a time of extraordinary climatic reorganization, including Northern Hemisphere glaciation, the rise of the Central American Isthmus, and associated changes in environmental conditions. Therefore, the Late Neogene extinctions of marine molluscs of South Florida present an ideal platform to examine the interaction between environmental changes and biotic response. In the present study, three different aspects of the Late Neogene extinctions are examined: temporal diversity patterns, selectivity patterns, and the impacts of these extinction events on ecological interactions. In the first part of this study, the diversity pattern of marine bivalves of Florida during the Late Neogene. Using bulk samples enables to take account of varying sampling intensity and underlying relative abundance distributions in diversity estimation. Comparison of sample-standardized diversity analyses shows that both richness and evenness of marine bivalve community declined at the Tamiami - Caloosahatchee transition, which coincides with the proposed first phase of the Late Neogene extinctions at the end of the Pliocene. Although magnitude of biodiversity loss was severe during these late Neogene extinction events, extinction risk was non-randomly distributed across taxa. Selectivity analyses, a combination of both commonly used non-parametric tests and logistic regressions, suggest that abundance or local population size was positively related with survivorship during the late Neogene. As other biological or ecological traits can influence this observed relation between abundance and extinction vulnerability, multivariate approach is used to control for these traits. Even after effects of geographic range and feeding mode is considered, the positive relation between abundance and survivorship, which supports predictions from biological studies, is evident in case of these Late Neogene extinction events. While present analyses show that the increase in relative abundance of Chione is a major factor in driving changes in community compositions, interactions between Chione and its' drilling predators also varied during the Late Neogene. This study suggests that identification of predators is a critical part of evaluation of prey-predator interactions. When drill hole traces of two predatory gastropod groups, muricids and naticids, are differentiated based on a revised site selectivity criteria, temporal trend of prey size selectivity differs from previous reports. Both groups exhibit some changes in predatory behavior during phases of the Late Neogene extinctions, suggesting that previous hypothesis of prey turnover at the Caloosahatchee - Bermont transition cannot explain the observed temporal trends of prey size selectivity in the present study.

The development and persistence of cocaine dependence are greatly influenced by emotional affect and cocaine associative learning. Cocaine is known to enhance nucleus accumbens (NAcc) dopamine, serve as a positive reinforcer and produce negative effects, such as anxiety that may influence cocaine intake behavior. In the first study, I investigated the effects of the anxiolytic, diazepam on NAcc dopamine levels and cocaine self-administration behavior. These are two factors associated with cocaine rewarding effects. Diazepam has no effect on NAcc dopamine, but affects cocaine self-administration. This supports the notion that decreasing the anxiogenic effects of cocaine increases the rewarding value in a dopamine independent manner. Therefore, increasing the aversive effects of cocaine might be a novel approach to fight cocaine dependence. In the second study, I studied cocaine-induced associative learning and changes in affect during cocaine conditioning and extinction. 50-kHz ultrasonic vocalizations (USVs) in rats are thought to reflect positive affect and occur upon appetitive stimuli and with cocaine delivery. First, I explored whether USVs might be elicited in anticipation of impending drug delivery. Shortly into conditioning, rats elicited USVs when placed in the cocaine-associated environment. USVs progressively increased, indicating a growing learned association between cocaine intake and cocaine-associated cues. This suggests that USVs may be a useful model for investigating cocaine craving and serve as a pharmacological target for interventions aimed to reduce cocaine craving and relapse. I then examined the effects of short-term deprivation of cocaine and cocaine cues on cocaine-conditioned USVs, which were both exaggerated after abstinence. The results may have clinical implications, in that intermittently avoiding cues or context may enhance drug cue salience and increase the probability of relapse. Motivational aspects of cocaine were assessed comparing commonly measured lever response rate and locomotion with cocaine-induced USVs during cocaine administration and extinction. In agreement with prevailing findings, lever responding for cocaine and cocaine-induced locomotor activity increased across conditioning sessions. However, the number of USVs evoked in response to cocaine infusion decreased with cocaine experience. These findings suggest growing tolerance to the rewarding properties of cocaine. These studies underscore the value of USV assessment during drug dependence studies. / text

This dissertation focuses on a variety of vadose zone processes that impact water table fluctuations. The development of vadose zone process conceptualization has been limited due to both the lack of recognition of the importance of the vadose zone and the absence of suitable field data. Recent studies have, however, shown that vadose zone soil moisture dynamics, especially in shallow water table environments, can have a significant effect on processes such as infiltration, recharge to the water table, and evapotranspiration. This dissertation, hence, attempts to elucidate approaches for modeling vadose zone soil moisture dynamics. The ultimate objective is to predict different vertical and horizontal hydrological fluxes. The first part of the dissertation demonstrates a new methodology using soil moisture and water table data collected along a flow transect. The methodology was found to be successful in the estimation of hydrological fluxes such as evapotranspiration, infiltration, runoff, etc. The observed dataset was also used to verify an exponential model developed to quantify the ground water component of total evapotranspiration. This analysis was followed by a study which analyzed the impact of soil moisture variability in the vadose zone on water table fluctuations. It was found that antecedent soil moisture conditions in the vadose zone greatly affected the specific yield values, causing a broad range of water table fluctuations for similar boundary fluxes. Hence, use of a constant specific yield value can produce inaccurate results. Having gained insight into the process of evapotranspiration and specific yield, a threshold based model to determine evapotranspiration and subsequent water table fluctuation was conceptualized and validated. A discussion of plant root water uptake and its impact on vadose zone soil moisture dynamics is presented in the latter half of this dissertation. A methodology utilizing soil moisture and water table data to determine the root water uptake from different sections of roots is also described. It was found that, unlike traditional empirical root water uptake models, the uptake was not only proportional to the root fraction, but was also dependent on the ambient soil moisture conditions. A modeling framework based on root hydraulic characteristics is provided as well. Lastly, a preliminary analysis of observed data indicated that, under certain field conditions, air entrapment and air pressurization can significantly affect the observed water table values. A modeling technique must be developed to correct such observations.

We have used a combination of hydrodynamical simulations, dust radiative transfer, and an empirically based analytical model for galaxy number densities and merger rates in order to physically model the bright high-redshift submillimeter-selected galaxy (SMG) population. We report the results of three projects: In the first we study the dependence of a galaxy’s observed-frame submillimeter (submm) flux on its physical properties. One of our principal conclusions is that the submm flux scales significantly more weakly with star formation rate for starbursts than for quiescently star-forming galaxies. Consequently, we argue that the SMG population is not exclusively merger-induced starbursts but rather a mix of merger-induced starbursts, early-stage mergers where two quiescently star-forming disk galaxies are blended into one submm source ("galaxy-pair SMGs"), and isolated disk galaxies. In the second work we present testable predictions of this model by demonstrating how quiescently star-forming and starburst SMGs can be distinguished from integrated data alone. Starbursts tend to have higher luminosity, effective dust temperature, global star formation efficiency \((L_{IR}/M_{gas})\), and infrared excess \((L_{IR}/L_{FUV})\) and tend to lie significantly above the star formation rate-stellar mass relation defined by quiescently star-forming galaxies. These diagnostics can be used to observationally determine the relative contribution of quiescently star-forming and starburst galaxies to the SMG population. In the final work we present the SMG number density, cumulative number counts, and redshift distribution predicted by our model. We show that, contrary to previous claims, the observed SMG number counts do not provide evidence for a top-heavy initial mass function. We also show that starbursts and galaxy-pair SMGs both contribute significantly to the bright SMG counts, whereas isolated disks contribute significantly only at the faint end. / Astronomy

In order to make thermal solar power compete with the traditional sources of energy, the efficiency must increase and one way of doing it is by changing the operating fluid. Among the alternate fluids is the use of molten salts as a part of the process; either for thermal storage and later utilization for electrical production during the hours without sun or as a substitute of the operating fluid to provide higher temperatures resulting in better efficiency. The difficulty of using molten salts is the lack of physical properties in literature; such as viscosity, boiling point, vapor pressure and volumetric absorption of solar radiation, thus making the selection of a suitable salt a very difficult endeavor. As a part of the Multidisciplinary Research Initiative (MURI) of the Department of Energy in the project of High Operating Fluids, this work will focus on the optical properties of the molten salts (volumetric absorption). The objective of this Thesis is to design, build and test a device capable of measuring the light attenuation coefficient; which is directly related to volumetric absorption of solar radiation, as well as determine the attenuation coefficient of various eutectic systems for the ternary salt mixture of ZnCl2, NaCl and KCl. Based on the little existent literature, a device capable of measuring the attenuation coefficient was designed, built, validated and tested. This was done by projecting a stable beam of light simulating sun radiation through the molten salt sample and to a spectrometer with a wavelength range going from 400 nm to 1000 nm with operating temperatures going from 350oC to 600oC. This device is capable of controlling the thickness, from 1 to 60 mm, of the molten salt sample by a computer controlled linear stage with an accuracy of 0.1mm. Quartz was used as a container for the molten salts because of its high melting point and transparency. A ceramic heater was used as a heat source, which can heat up the sample to temperatures up to 1200 oC if necessary. Two validation tests for the device were done by measuring the light attenuation coefficient of clear water and extra virgin olive oil and then they were compared to the ones in literature. The eutectic systems were tested next; the results characterized the attenuation coefficient as a function of wavelength and temperature, something that no other experimental work has done before for this specific fluid. These values will help to determine an optimal operating fluid for high temperature thermal applications.

Previous research has shown that cognitive reappraisal, an emotion regulation strategy, has beneficial effects on emotion experience during strategy engagement. The present study extends this work by investigating whether cognitive reappraisal impacts the anticipation of an aversive event during, and five days following, strategy engagement. Emotion profiles, including psychophysiological and self-report indices, were also examined to assess whether reappraisal inhibits affective responses. Participants underwent habituation and simple discriminatory fear conditioning. Stimuli were pictures of a snake and a spider. Two days later participants returned to the laboratory and were either i) cued to engage in cognitive reappraisal while imagining the stimuli ii) exposed to the stimuli with no reappraisal instructions iii) exposed to the stimuli while engaging in cognitive reappraisal or iv) had an experience unrelated to the stimuli (control condition). Participants returned to the lab five days later and were exposed to both pictures paralleling initial habituation and conditioning protocols. It was found that cognitive reappraisal during exposure reduced expectancy of the UCS faster than exposure alone and resulted in lower mean skin conductance response (SCR) for those low, but not high, in fear of snakes. Five days later participants in the intervention conditions, compared to the control condition, demonstrated less anticipation of the UCS and smaller emotion-modulated startle magnitudes to the UCS. These findings suggest that cognitive reappraisal may be an effective tool for reducing anticipation of an aversive event and can result in enduring fear inhibition. This may have important implications for the treatment of individuals with anxiety disorders. The present study also examined the relationship between cardiac vagal control, indexed by respiratory sinus arrhythmia (RSA), and subsequent sympathetic arousal during fear conditioning, indexed by SCR. Results demonstrate that participants with low, compared to high, resting RSA had larger SCRs during habituation and conditioning trials. In addition, participants with lower RSA showed greater SCR reactivity following UCS presentation to both conditioned stimuli, suggesting that those with the lower RSA initially differentiated less between the UCS paired and unpaired images. These findings are consistent with theories that associate faster recovery from emotionally demanding situations with greater cardiac vagal control.

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Paukščių Tako Galaktikos sritį esančią Cefėjaus žvaigždyne sudaro keletas žvaigždėdaros regionų. Šiame darbe tirta sritis kurios centro koordinatės l=102.4 , b=+15.5 ir stebimo lauko dydis 1.2*1.2 laipsnio. Tyrimui naudota Vilniaus fotometrinė sistema su CCD kamera. / The Milky Way region in the direction of the Cepheus contains several star forming regions. The area of 1.2*1.2 deg size at l=102.4 , b=+15.5 are investigated using CCD photometry in the Vilnius system and described in this work.