Components of the molecular pathway underlying gonadogenesis in organisms with temperature-dependent sex determination (TSD) have been retained from genetic sex determination. Furthermore, although much of this network has been conserved, new functions for these genes have evolved in this different mode of sex determination. We find that the transcription factors Sox9 and Dmrt1 and the hormone Mis are involved in the formation of a testis and/or the repression of an ovary at a male-producing temperature. While Mis expression may be maintained by Sox9, the initial upregulation of Mis in the developing testis is most likely modulated by some other upstream factor. Dmrt1 appears to play an upstream role in testis sex determination. We provide evidence that the transcription factor Dax1 and the signaling molecule Wnt4, cloned for the first time in an organism with TSD, play roles in gonadogenesis in both sexes. Finally, we show that the transcription factor FoxL2 and the signaling molecule Rspo1 are involved in the formation of an ovary and/or the repression of a testis at a female-producing temperature. In the first investigation of Rspo1 in any organism exhibiting TSD, we demonstrate it is involved upstream in ovarian sex determination. Complementary to descriptive studies, we optimize a whole organ culture system in which gonad explants develop in vitro for up to three weeks. We show that expression of the sex-determining network in isolated gonads mimics in ovo patterns, revealing an endogenous temperature-sensing mechanism that does not require other embryonic tissues. Ectopic expression of Sox9 reveals a possible positive feedback regulation of Dmrt1. The use of this culture system opens the door to functional manipulation of the gonad at the molecular level and is suitable for a myriad of future studies. This work makes strides in elucidating the molecular network underlying gonadogenesis in an organism exhibiting TSD, and invites investigation of the evolution of gene function. The data lend insight into the changing roles of molecules in sex determination across diverse taxa, and into the evolution of developmental pathways in general. / text

A close relation between structural and optical properties of any semiconductor material does exist. An adequate knowledge and understanding of this relationship is necessary for fabrication of devices with desired optical properties. The structural quality and hence the optical properties can be influenced by the growth method and the substrate used. The aim of this work was to investigate the change in optical properties caused by growth techniques and substrate modification. To study the influence of growth technique on optical properties, ZnO nanostructures were grown using atmospheric pressure metal organic chemical vapor deposition (APMOCVD) and chemical bath deposition (CBD) technique. The structural and optical investigations were performed using scanning electron microscopy (SEM) and micro photoluminescence (μ-PL), respectively. The results revealed that the grown structures were in the shape of nano-rods with slightly different shapes. Optical investigation revealed that low temperature PL spectrum for both the samples was dominated by neutral donor bound excitons emission and it tends to be replaced by free exciton (FX) emission in the temperature range of 60-140K. Both excitonic emissions show a typical red-shift with increase in temperature but with a different temperature dynamics for both the sample and this is due to difference in exciton-phonon interaction because of the different sizes of nano-rods. Defect level emission (DLE) is negligible in both the sample at low temperature but it increased linearly in intensity after 130 K up to the room temperature.Modification in substrate can also play a significant role on structural and optical properties of the material. Specially variation in the miscut angle of substrate can help to control the lateral sizes of the Nanostructures and thus can help to obtain better structural andoptical quality. Also optical quality is a key requirement for making blue and ultraviolet LEDs. Therefore, ZnO Nanostructures were grown on SiC on-axis and off-axis substrates having different off-cut angles. Morphological investigation revealed thatgrown structures are epitaxial for the case when substrate off-cut angle is higher and deposition rate is low. Low temperature PL spectrum of all the samples was dominated by neutral donor bound excitons and free exciton emission become dominant at 100 K for all the samples which completely eliminate the neutral donor bound excitonic emission at 160K. Two electron satellite of the neutral donor bound excitons and LO phonons of excitonic features are also present. A typical red-shift in excitonic features was evident in temperature dependence measurement. Red-shift behavior of free exciton for all the samples was treated by applying Varshni empirical expression and several important parameter, such as, the Debye temperature and the band gap energy value was extracted. Thermal quenching behavior was also observed and treated by thermal quenching expression and value of the activation energy for non-radiative channel was extracted. The results that are obtained demonstrate a significant contribution in the fields of ZnO based nano-optoelectronics and nano-electronics.

This study presents a combined viscoelastic (VE)-viscoplastic (VP) analysis for Fiber Reinforced Polymer (FRP) composites subject to simultaneous mechanical load and conduction of heat. The studied FRP composites consist of unidirectional fibers, which are considered as linearly elastic with regards to their mechanical response, and isotropic polymeric matrix, which shows viscoelastic-viscoplastic response under various stresses and temperatures. Due to the viscoelastic and viscoplastic behavior of the polymeric matrix, the overall FRP composites exhibit a combined time-dependent and inelastic behavior. A simplified micromechanical model, consisting of a unit-cell with four fiber and matrix subcells, is formulated to homogenize the overall heat conduction and viscoelastic-viscoplastic responses of the FRP composites. The micromechanical model is compatible with a displacement based finite element (FE) and is implemented at the Gaussian integration points within the continuum finite elements, which is useful for analyzing the overall time-dependent response of FRP composite structures under various boundary conditions. The Schapery nonlinear integral model combined with the Perzyna viscoplastic model is used to describe the viscoelastic-viscoplastic response of the polymer constituents. An integrated time integration algorithm is formulated at the micromechanics level in order to solve the nonlinear viscoelastic-viscoplastic constitutive model at the matrix subcells and obtain the overall nonlinear response of the FRP. The viscoelastic-viscoplastic micromechanical model is validated usingexperimental data on off-axis glass/epoxy FRP composites available in literature. The overall response of the FRP composites determined from the simplified micromechanical model is also compared with the ones generated from microstructures of FRP with various fiber arrangements dispersed in homogeneous polymer matrix. The microstructural models of the FRP with detailed fiber arrangements are generated using FE. The effects of thermal stresses, due to the mismatches in the coefficient of thermal expansions of the fibers and polymeric matrix, and stress concentrations/discontinuities near the fiber and matrix interfaces on the overall thermo-mechanical deformation of FRP composites are studied using the two micromechanical models discussed above. Finally, an example of structural analysis is performed on a polymeric smart sandwich composite beam, having FRP skins and polymeric foam core with piezoelectric sensors integrated to the FRP skins, undergoing three point bending at an elevated temperature. The creep displacement is compared to experimental data available in literature.

Climate change poses a serious threat to species that demonstrate temperature dependent sex determination (TDS), including marine turtles. Increased temperatures can result in highly female skewed sex ratios and decreased hatchling success. In situ sand temperature data was collected from the nesting depth of hawksbill and green turtles at five study sites along the coast of the Red Sea. The sand temperature profile at four of the sites exceeded the pivotal temperature of 29.2°C (commonly cited in literature) throughout the study duration, which suggests feminization of turtles could be occurring, but further studies need to identify the pivotal temperature in this region. The percentage of days exceeding the commonly cited maximum thermal threshold (33 and 35°C) was calculated for each site at 30 and 50 cm. Sand temperature recordings were as high as 36.0°C at 30 cm depth, and 35.3°C at 50 cm. This suggests that the turtle hatchlings in some areas of the Red Sea could already have high mortality rates due to high temperatures, unless they are locally adapted to these high temperatures. The Red Sea is home to five out of the seven extant species of marine turtles in the world, but not much is known about these populations. The Red Sea is an understudied region of the world, but it has the potential to provide insight on how species might adapt to future climate change due to its high and variable water temperatures (range of 20°C to 35°C) and high salinity (40 PSU). Sites with lower sand temperatures (and lower risk of feminization) may represent priority areas for conservation efforts, particularly in regions facing imminent coastal development.

In the presented thesis work, meshfree method with distance fields was extended to obtain solution of nonlinear transient heat transfer problems. The thesis work involved development and implementation of numerical algorithms, data structure, and software. Numerical and computational properties of the meshfree method with distance fields were investigated. Convergence and accuracy of the methodology was validated by analytical solutions, and solutions produced by commercial FEM software (ANSYS 12.1). The research was focused on nonlinearities caused by temperature-dependent thermal conductivity. The behavior of the developed numerical algorithms was observed for both weak and strong temperature-dependency of thermal conductivity. Oseen and Newton-Kantorovich linearization techniques were applied to linearized the governing equation and boundary conditions. Results of the numerical experiments showed that the meshfree method with distance fields has the potential to produced fast accurate solutions. The method enables all prescribed boundary conditions to be satisfied exactly.

In this master thesis, electrical characterization of thin film CuInxGa(1−x)Se2 solar cells produced by Midsummer AB were performed with the aim of determining the dominant recombination path of these cells. Current-Voltage (IV), Quantum Effinciency (QE), temperature dependent IV (IVT) and Drive-Level Capacitance Profiling (DLCP) was used with the objective to investigate the dominant recombination path as well as provide some insight of the solar cells in order to create a baseline model using the modelling software SCAPS (Solar cell CAPacitance Simulator). The IV produced mostly consistent results with slight variation, most likely due to non uniformity of equipment. The QE showed consistent results between all cells indicating a stable process for the sample preparation. Using IVT measurements were taken from a temperature of 115K −300K in order to obtain the activation energy for the dominant recombination path. By comparing it with the band gap energy from the QE measurement, it was found that the dominant recombination path is in either the space charge region or in the bulk of the CIGS and not at the hetero interface. DLCP measurement were made at both low temperature and at room temperature and revealed that the cells had a similar doping as other comparable cells at 7×1016cm−3 . The initial baseline model created in SCAPS show a good agreement with the measured IV and currently indicates a spike in the band alignment, supporting the results for the IVT measurement.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23509号 / 工博第4921号 / 新制||工||1769(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 田中 功, 教授 中村 裕之, 教授 安田 秀幸 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Yes / In this study, the thermal performance analysis of porous fin with temperature-dependent thermal conductivity and internal heat generation is carried out using Haar wavelet collocation method. The effects of various parameters on the thermal characteristics of the porous fin are investigated. It is found that as the porosity increases, the rate of heat transfer from the fin increases and the thermal performance of the porous fin increases. The numerical solutions by the Haar wavelet collocation method are in good agreement with the standard numerical solutions.

Yes / In this paper, the Chebychev spectral collocation method is applied for the thermal analysis of convective-radiative straight fins with the temperature-dependent thermal conductivity. The developed heat transfer model was used to analyse the thermal performance, establish the optimum thermal design parameters, and also, investigate the effects of thermo-geometric parameters and thermal conductivity (nonlinear) parameters on the thermal performance of the fin. The results of this study reveal that the rate of heat transfer from the fin increases as the convective, radioactive, and magnetic parameters increase. This study establishes good agreement between the obtained results using Chebychev spectral collocation method and the results obtained using Runge-Kutta method along with shooting, homotopy perturbation, and adomian decomposition methods.

In aquatic turtles, females select nest sites that have a high degree of solar exposure, and exploit recently tilled agricultural fields for nesting, presumably because of increased solar exposure and/or easier nest excavation, and the importance of incubation temperature on survival and offspring phenotype. These same disturbed sites are often contaminated by pollutants and turtles can incorporate high levels of pollutants into their eggs which negatively impact hatch success. For my M.S. research, I investigated turtle nest site selection in a system dominated by agricultural and industrial land use, the impact of crop growth on the thermal and hydric dynamics of turtle nests, and I used paired field and laboratory experiments to examine the individual and interactive impacts of agricultural land use and Hg contamination on hatch success and offspring phenotype in Chelydra serpentina. Of the 150 turtle nests found during this research, 84% were located in human-disturbed soils. Nest site characteristics were similar among nests found in Hg contaminated and reference areas. Agriculture and control nests did not differ in temperature at the time of nesting, but temperatures diverged as crops grew, with temperatures in nests in agricultural fields averaging 2.5 °C lower than control nests over the course of incubation. Similarly, despite no initial difference, nest moisture levels diverged throughout incubation and moisture averaged 107 kPa lower in agricultural than control soils throughout incubation. In my field and laboratory experiments, I found that in comparison to turtles from control incubation conditions (i.e., warmer), turtles incubated under agricultural thermal regimens (i.e., colder) took longer to hatch, hatched at smaller structural body sizes, lost more mass after hatching, had lower post-hatching structural growth rates, and were more likely to be male. Additionally, thermal conditions associated with agricultural land use interacted with high levels of mercury to impact hatching success and offspring sex ratios. My thesis research provides one of the first documentations of negative interactive effects of mercury pollution and habitat quality on early vertebrate development and highlights the importance of examining the combined influence of multiple global changes on biological systems. / Master of Science