Thesis (M.S.)--University of Oregon, 2006. / Includes bibliographical references (leaves 20-23).

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Batrachochytrium dendrobatidis (Bd) is a fungal pathogen causing amphibian population declines. Bd has a narrow thermal tolerance and requires moisture to survive. Differences in frog biology, pathogen biology or temperature and moisture conditions may determine population response to disease. Population responses to Bd vary among sites, habitats, species and populations. In the tropics, stream-dwelling species decline to a greater degree than forest species, yet not all stream species decline to extirpation and not all forest species survive. I hypothesized that variation in operative temperature (Te) or body temperature (Tb) might explain differences in host population change documented among sites, seasons, habitats, and species. I sampled three moist-forest Panamanian sites (elevation 375 - 1300 m) during 2.5 months of the 2008 wet season and four different moist-forest sites (elevation 400 - 1300 m) during 3 weeks of the 2008 dry season. I measured Te and Tb of anurans along stream and forest transects. Additional environmental variables such as height, substrate, canopy cover and sunfleck presence were measured concomitantly. I used analysis of covariance to determine whether these factors influenced Te and Tb. I compared frequency distributions of Tb and Te to a Bd thermal growth curve to determine: 1) whether temperatures above Bd's critical thermal maximum were available to frogs, and 2) whether populations of species that have declined occupied habitats more frequently in Bd's optimal thermal range than species that have not. Te and Tb differed among sites, with cooler temperatures at higher elevation. Te was cooler during the dry season yet the presence of sunflecks and open canopy had greater effect on Te during the dry season. Within a site, Te and Tb were not different between habitats. Within a site, Tb did not vary among species. Average Te and Tb for all sites fell within Bd's thermal tolerance range, but the low elevation sites had Tb ranges extending above Bd's critical thermal maximum. Although temperature may explain greater losses at higher elevations, I found no significant difference in operative temperatures between stream and forest habitats at any site which indicates that temperature alone does not explain greater losses of stream anurans. Species that have declined to extirpation elsewhere did not consistently have cooler body temperatures compared to surviving species. Within the Neotropics, moisture, instead of temperature, may explain patterns of Bd prevalence among seasons, habitats, and species.

The effect of elevated temperatures on the phase transformation mechanisms in electrodes for lithium-ion batteries (LIBs) is an important but – to date – only less studied subject in battery research. In real-life applications, LIBs usually function at non-ambient conditions and especially increased temperatures give rise to safety concerns. This thesis focuses to gain deeper insights into the phase transformations at high temperatures (HTs) by tackling both the challenging hardware development of a HT in situ synchrotron X-ray diffraction (XRD) battery testing system as well as its application to study two important cathode materials: LiFePO4 and V6O13. This allows unprecedented insights into the structural changes and its influence on electrochemical performance at variable temperatures (VTs). LiFePO4 was investigated for various battery cycling rates and temperatures. Electrochemical cycling of LiFePO4 in the newly designed in situ XRD setup proved that the in situ XRD cells work from low to high cycling rates between 25 to 150oC. The current induced non-equilibrium solid solution metastable LiFePO4 phase, present at room temperature during high rate cycling, was found to be less pronounced at temperatures above 125oC. This is possibly due to faster Li-ion diffusion at HT, leading to faster phase separations in the solid solution phases. In a next step, V6O13, a promising cathode material for HT applications, especially for oil field applications, was tested using the in situ HT XRD setup. The material exhibits a very high capacity with a complex voltage profile. The underlying asymmetric discharge and charge phase transition mechanisms, which include a six-step discharge and five-step charge process, are unravelled by in situ XRD. The LixV6O13 unit cell expands sequentially in c, b, and a directions during discharge and reversibly contracts back during charge. The process is associated with a change of occupied lithium sites as well as charge ordering in LixV6O13. Density functional theory (DFT) calculations and nuclear magnetic resonance spectroscopy gave further insight into the electronic structures and preferred Li positions in the different structures formed upon cycling, particularly at high lithium contents. At HT, V6O13 exhibits an even greater capacity, as well as a more symmetric discharge and charge profile. Combining the results from the HT in situ XRD study and the DFT calculation, the most Li puckered phase was found to be able to open further along the b axis, with a new Li site getting (partially) occupied. The new Li site corresponds to more Li intercalation into the LixV6O13 structure and, therefore, more electrode charge storage capacity. The more symmetric discharge and charge process was attributed to the disappearance of phase 2 (present at room temperature for 1.7 < x ≤ 2.1 in LixV6O13) at HT.

The properties of sub-monolayer Helium-3 films adsorbed on two totally different but planar substrates, Mylar^&dagger; film and exfoliated graphite have been studied using NMR. The nuclear magnetic relaxation times T₁ and T₂ have been measured as functions of fractional monolayer completion, temperature, substrate plane orientation and Larmor frequency using a specially designed and constructed NMR spectrometer system. The results obtained with a Mylar film substrate are consistent3with the formation of patches of solid ³He at regions of preferential adsorption on the substrate. Measurements of T₂ m very low coverage ³He films on exfoliated graphite also indicate that the adsorbate forms areas of relatively high density solid, in agreement with the thermodynamic analysis of Elgin and Goodstein. Finally, detailed measurements of T₂ as a function of all of the above parameters at low areal densities will help us to characterise the relaxation processes for the fluid phase of ³³He on exfoliated graphite. ^&dagger;Mylar is the tradename of poly(ethelene-terephthalate) film, marketed by Du Pont.

Doctor of Philosophy / Department of Agronomy / P. V. Vara Prasad / Increased ambient temperature and soil salinity seriously affect the productivity of wheat (Triticum aestivum L.) which is an important cereal second to rice as the main human food crop. However, wheat plant is most susceptible to high temperatures and salinity at booting and flowering stages. Several studies have documented the effects of individual stress like salinity and high temperature stress on wheat, nonetheless little is known about effects of combined salinity and high temperature at critical growth stages. Therefore, the objectives of this research were (i) to screen winter wheat germplasm for salinity tolerance at the germination stages and to determine seedling growth traits associated with salinity tolerance, (ii) to evaluate the independent and combined effects of high temperature and salinity on winter wheat genotypes at the booting stages through growth, physiological, biochemical, and yield traits, and (iii) to evaluate the independent and combined effects of high temperature and salinity on winter wheat genotypes at the flowering stages through growth, physiological, biochemical, and yield traits. In the first experiment, 292 winter wheat genotypes (winter wheat germplasm) was screened for salinity stress at germination stage under controlled environments. The seeds were subjected to three levels of salinity, 0, 60, and 120 mM NaCl to quantify the effects of salinity on seed germination and seedling growth. In the second experiment, controlled environment study was conducted to quantity the independent and combined high temperature and salinity stress effects on growth, physiological, biochemical, and yield traits of twelve winter wheat genotypes during booting stage. Plants were grown at 20/15 °C (daytime maximum/nighttime minimum) temperature with 16 h photoperiod. At booting stages, the plants were exposed to optimum (20/15 °C) or high temperature (35/20 °C) and without (0 mM NaCl) and with (60, and 120 mM) NaCl. In the third experiment, plants were exposed to optimum or high temperature and with and without NaCl levels at flowering stages. The temperature regime and salinity levels were same as experiment II. The duration of stress was 10 d and after the stress period the plants were brought to optimum temperature and irrigated with normal water (0 mM NaCl). The results indicated that, at 120 mM NaCl, the final germination percentage was decreased and the mean daily germination was delayed. Irrespective of the genotype, salinity stress significantly decreased the shoot and root length; seedling dry matter production, and seedling vigor. Based on the seedling vigor index, the genotype GAGE, OK04507, MTS0531, TASCOSA, ENDURANCE and GUYMON, were found to be most tolerant and CO04W320, 2174-05, CARSON, OK1070275, TX02A0252 and TX04M410211 were the most susceptible to salinity at germination stage. Combined stresses of high temperature and salinity decreased photosynthetic rate and grain yields. Based on grain yield, the genotype TASCOSA was found to be most tolerant (64 % decrease) to combined stresses, and AVALANCHE was the most susceptible to combined stresses (75 % decrease) at booting stages. Similarly, at flowering stage, TX04M410211 had greater tolerance to combined stresses (65 % decline) as compared to GAGE (83 % decline). In both experiments, tolerance was associated with higher spikelet number and seed set. In conclusion, there is genetic variability among winter wheat genotypes that can be used in breeding programs to improve winter wheat yield under combined high temperature and salinity stress conditions.

Master of Science / Department of Human Nutrition / Edgar Chambers IV / The sensory properties of coffee are impacted by various factors such as coffee origin, degree of roasting and ways of consumption. This study analyzed impact of ways of consumption (1. consumption temperatures and 2. milk and/or sugar additions) on 38 flavor attributes of hot brewed coffee by descriptive sensory analysis. Different type of coffee samples (2 Arabica, 1 Robusta, and 1 Blended) were consumed at 50ºC, 60ºC and 70ºC. Results showed significant interactions of temperature and coffee samples for coffee like attributes such as coffee identity, fidelity, and blended. The consumption temperature played a major impact on perceived flavor attributes of coffee and influenced Arabica, Blended and Robusta coffee differently and we have to consider that when blending coffees. Coffee identity and fidelity significantly increased with an increase in all temperatures, but most attributes showed significantly higher intensity only for samples served at 70ºC regardless of insignificant differences at 60ºC and 50ºC. Three coffee samples (light, medium, and dark roasted) were tasted with and without milk or sugar. The data were submitted to principal component analysis and cluster analysis. The first 2 PC’s allowed to separate coffee into three categories and CA revealed similar distribution of coffee into three clusters. Coffee like attributes were seemed to play a more important role in the determination of clusters as the addition of milk and sugar decreased the intensity of key flavor attributes such as coffee identity, bitterness, fidelity, roasted, blended, and longevity. The flavor attributes of dark roasted coffee was more impacted by the addition of milk and sugar. Results suggested that the effect of addition (milk and/or sugar) is correlated to the degree of roasting and we have to consider the milk and sugar additions according to degree of roasting.

Espalhamentos Raman e Brillouin foram usados no estudo de vários sistemas que apresentam questões em aberto no comportamento de suas propriedades físicas com a temperatura. Estudamos materiais de interesse geofísico, como o rutilo Ti02 e o espinélio MgAl204. Os resultados de espalhamento Raman no rutilo Ti02, a temperaturas de 1000 K, mostraram que as frequências dos fônons ópticos diminuem pouco com a temperatura. A ausência de um modo soft a estas altas temperaturas, confirma a estabilidade da stishovite, material de estrutura análoga ao rutilo TiO2, e que existe no manto terrestre. As constantes elásticas do espinélio MgAl204 foram medidas em função da temperatura, por meio de espalhamento Brillouin até 2100 K: estas foram as temperaturas mais altas já obtidas em experimentos de espalhamento Brillouin. A partir das constantes elásticas, calculamos parâmetros de importância geofísica, pois este material é estruturalmente análogo ao espinélio y-Mg2Si04, considerado o maior constituinte do manto inferior terrestre. O estudo de espalhamento Raman no material sintético c-BN, a temperaturas de 1600 K, mostrou que este material retém suas propriedades mecânicas a estas altas temperaturas, sendo indicado para aplicações onde estas condições são requeridas. Realizamos espalhamento Raman nos compostos GaI3, GaBr3,AlBr3 e AlCI3, com a finalidade de determinar suas estruturas perto de seus pontos de fusão. A estrutura dos líquidos foi determinada como sendo composta por moléculas diméricas, presentes também nos sólidos, com a excessão do composto AICI3. Neste composto, a mudança de estado sólido-líquido ocorre com uma brusca mudança estrutural, onde o sólido iônico transforma-se em um líquido de moléculas diméricas. As propriedades elásticas da água sob pressões negativas foram investigadas por meio de espalhamento Brillouin em microinclusões, naturais e sintéticas, de água e vapor de água em cristais de quartzo. Através do aquecimento, estas inclusões homogenizam a uma temperatura Th: no resfriamento a partir de Th, o sistema atinge um estado metaestável, interrompido pela nucleação da fase gasosa. Nossos experimentos geraram tensões da ordem de 100 MPa. O enxofre líquido foi estudado por espalhamento Brillouin, a temperaturas em torno da transição À. A interpretação dos espectros polarizados foi feita de acordo com o formalismo de Mori-Zwanzig, e não mostraram evidência da transição À. Os espectros despolarizados, por outro lado, mostraram uma pronunciada anomalia em torno da temperatura da transição . / Raman and Brillouin scattering were used in the study of several systems which present open questions in their physical properties. under the effect of the temperature. Materials of geophysical interest were studied as rutile Ti02 and the spinel MgAh04. Results of Raman scattering from Rutile (Ti02) up to 1000 K show that the frequencies of the optical phonons decrease slowly with temperature, and do not show anomalies reported in previous work at lower. temperatures The absence of a soft mode at these high temperatures confirms the stability of stishovitte, a structural analog of Rutile (Ti02), wich exists in the Earth\'s mantle. The elastic constants of Spinel MgAh04 were measured using Brillouin scattering up to 2100 K: this is the highest temperature ever reported for a Brillouin scattering experiment. Parameters of geophysical importance were calculated, in an analog to y-Mg2Si04, believed to be the major constituent of the Earth\'s lower mantle. Raman scattering measurements on cubic boron nitride up to 1600 K, indicate that at high temperature this material retains its mechanical strength, and it is therefore suitable in applications where very high temperatures are involved. The vibrational properties of molten GaI3, GaBr3, AlBr3 and AlCI3. were determined by Raman scattering. The structure of these compounds in the molten state is a dimer represented by M2X6 consisting of two tetrahedra sharing a halide edge. In AlC13, the melting process leads to a drastic change in the structure. Using Brillouin scattering we have investigated the elastic properties of water under negative pressures. The samples were H20 liquid-vapor inclusions in -quartz which could be heated to their homogenization temperature; on cooling, negative pressures as high as 100 MPa were reached before a vapor bubble nucleated. The velocity of sound results obtained indicate that nucleation occurs long before reaching the mechanical instability region, where the bulk modulus is zero. Liquid Sulphur was studied by Brillouin scattering as a function of temperature trough the lambda transition. Mori-Zwanzig formalism was applied to fit the polarized spectra and they showed no evidence of a lambda transition. On the other hand the depolarized spectra exhibited marked changes near the lambda transition temperature.

M.Sc. / Please refer to full text to view abstract

Chapter 1.This chapter investigates the direct behavioral impact of information-based regulations by examining the effect of ozone alerts on cycling trips in Sydney. Moreover, the dynamics of individuals' response is studied by examining the behavioral impact of two successive day ozone alerts on cycling demand. A common problem in estimating direct avoidance behavior is that an increase in the pollution level could be an endogenous response to alerts. While controlling for the endogenous effect of alerts and air quality, results show that cycling trips decrease by 35 percent in response to a smog alert. When alerts are issued for two successive days, however, individuals appear to neglect the second day alerts. Our findings also indicate that ozone alerts induce one and half times larger impacts on weekends compared to weekdays. These patterns suggest that the cost of cycling substitution for commuter goals is higher than leisure goals. Furthermore, the cost of intertemporally avoiding cycling is increasing over time. Chapter 2. If decisions with lasting consequences are influenced by extraneous or transient factors then welfare can be damaged. This chapter investigates the impact of outdoor temperature on high-stakes decisions (immigration adjudications) made by professional decision-makers (US immigration judges). In our preferred specification, which includes spatial, temporal and judge fixed effects, and controls for various potential confounders, a 10 F degree increase in case-day temperature reduces positive decisions by 6.55%. This is despite judgements being made indoors, `protected' by climate-control. Results are consistent with established links from temperature to mood and risk appetite and have important implications for evaluating the welfare-burden of climate change. Chapter 3. The carbon tax in the Canadian province of British Columbia is widely-regarded as a `poster child' application of market-based methods to address greenhouse gas emissions. However the implications for local air quality have been ignored. Using synthetic control and difference-in-difference methods, in this chapter we evidence a causal link from carbon tax implementation and level to increased nitrogen oxides NOx and ultra-fine particulates PM_2.5 pollution problems in Vancouver, the province's largest city. We provide evidence consistent with the mechanism working through induced switching from gasoline to diesel vehicles. The results prove highly robust to inclusion of a wide set of controls in various combinations, alternative specifications, and satisfy a set of falsification checks. The analysis points to the possibility of negative secondary effects of climate policies, contrary to the usual presumption that secondary benefits are inevitably positive.