This project provided an exceptional opportunity to describe diving behaviour, movements and to characterise critical habitats of blue sharks in the North-eastern Atlantic using satellite and archival telemetry.  Tracked blue sharks displayed southward movements away from the tagging areas, exhibiting pronounced site fidelity to localised high-productivity frontal regions.  Blue sharks also displayed a high degree of variability in vertical movements. Shifts in diving behaviour were detected both within and between individuals, whereas behavioural phases were linked to the thermal structure of the water column in coastal areas, and to changes in prey distribution or type in offshore regions.  High resolution data showed that blue sharks shift between Brownian (in productive habitats) and Lévy (less productive waters) behaviours.  Vertical movements ranged from the surface to 1160 m, and water temperatures varied between 7.2-27.2°C.  Behavioural data was also crucial in determining the degree of spatial and temporal overlap, and thus vulnerability, between blue sharks and high-seas longliners.  Confirmed fishing mortality was ~11% with four tagged sharks caught by surface longliners.  Simulations showed that boats/sharks overlap was higher in winter and early spring, with the majority of simulated sharks (~88%) at risk at least one day year-1.  Our results indicate that, depending on which geographical regions are occupied at specific times, different segments of the blue shark population face differential risk from longlines.  Sequencing of mitochondrial DNA suggested an absence of spatial genetic differentiation throughout the North Atlantic, providing strong evidence that blue sharks comprise a single population in this region.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

In this thesis, we combined inductively coupled plasma reactive ion etching (ICP-RIE) and SiO2 sputtering to enhance quantum well intermixing (QWI). The samples used in this study were grown by molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) on InP substrates. MBE sample consists of three In0.53Ga0.47As quantum wells, and the other consists of three In0.77Ga0.23As0.79P0.21 quantum wells. Ar+ bombardment by ICP-RIE was the first process step, and then a 300 nm SiO2 capping layer was sputtered upon the samples. The processed samples were subject to rapid thermal annealing. The properties of quantum wells after annealing were determined by photoluminescence (PL) measurement. The In0.53Ga0.47As/In0.53Ga0.26Al0.21As structure was used to design a series of experiments. First, we observed that the amount of blueshift increased with ICP-RIE time increased. ICP-RIE for 8 minutes was the optimum resulting in a bandgap blueshift of 60 nm, leaving a distance of about 200 nm between QWs and the SiO2 interface. The PL blueshift was directly ascribed to QWI caused by compositional interdiffusion between QWs and barriers. To determine how ICP-RIE affects QWI, we used H3PO4 solution to etch samples to the depth that was around 200 nm away from the QWs, and then coated by a sputtered SiO2 layer. Under 700¢J annealing, it gave rise to a blueshift of only 18 nm. And we also proved that the sputtered SiO2 capping layer provided an extra amount of bandgap blueshift. After the mechanism of QWI combining ICP-RIE and SiO2 sputtering was established, we applied this QWI process in In0.77Ga0.23As0.79P0.21/In0.57Ga0.43As0.64P0.36 material system, and we obtained a maximum amount of blueshift of 90 nm in this study.

The purpose of this study was to implement a new, rapid field method to effectively and accurately detect harmful clay minerals in aggregate fines by using the modified methylene blue (MMB) test. The focus of this study was based on existing knowledge that expansive, or swelling, clays can cause performance problems in pavements whose coarse aggregate fraction contains an appreciable amount of clay. It has been shown through various research projects along with pavement sections in the field that have failed due to distresses caused by the presence of a considerable amount of deleterious clay minerals. As part of this study, nearly thirty aggregate sources, mainly throughout Texas, have been collected and tested using the MMB test. These samples also underwent chemical separation in order to determine the amount of clay contained within each sample. A strong correlation between the MMB test and the clay content detected by chemical separation results has been established. In other words, clay-rich samples have been reflected by the results of the MMB test, thus providing evidence of the test’s accuracy in detecting expansive clay minerals. In addition to the quantification of aggregate fines by mineralogy, performance testing using hot mix asphalt (HMA) and Portland cement concrete (PCC) mixes was also conducted. In one phase of the study, known amounts of standard clay minerals were introduced to the mixes, and performance testing was carried out. This was done in hopes of establishing a limit of tolerable amounts of clay in coarse aggregate fines that would not sacrifice concrete performance. In another phase of this study, natural stockpiled aggregates from select quarries throughout Texas known to contain clay minerals in the aggregate fines were used to make Portland cement concrete to see how they performed as the coarse aggregate fraction of the mixes. Through extensive methylene blue and concrete performance testing, the aim was to establish a threshold methylene blue value (MBV) that corresponds with the maximum permissible clay content within the aggregate fines.

The blue sheep (Pseudious nayaur) is the major large-size herbivores in Helanshan. During studying, the blue sheep mean group size were 4.2¡ã7.1, with smaller group size than in other ranges. Mixed groups were usually bigger than male and female groups. Sex ratio the most close was 1:1.08 (¡ð:¡ñ) in winter, and other samples still favored males except for fall. The highest ratio of adult female to young was 1:0.78 in summer. In daily activity cycle, blue sheep usually moved and fed in morning and evening, but rested during noon. In summer, animals started active earlier and ended latter than in winter, but had more short active time. From summer to fall, the blue sheep mostly used the edge of forest and used forest least in altitude 2200m. But in altitude 1700m, blue sheep used grassland more than frequently bush and fountain.

Abstract As blue/green laser has a short wavelength radiation, it can be applied to micro-machining, laser display, high-density optical data storage, underwater communications, and so on. Large efforts have been devoted to simplify the laser system and reduce the cost. Therefore, various types of blue/green lasers have been studied, especially intracavity frequency doubling of the diode-pumped solid-state laser, which can effectively generate high blue/green laser powers with long lifetime. Among all cavity designs, direct-coated composite crystal is the most compact structure. Compare with the green laser, which is a four-level laser, blue laser belongs to a quasi-three-level system. Thus, it is more important to control the temperature of gain medium. Before the experiment, making an estimation will greatly benefit the progress and efficiency. ZEMAX was utilized to simulate the focus system and GLAD was used to model our intracavity frequency-doubled blue laser. In the experiment, we used a LD array as a pumping source and arranged suitable lens to reduce the array¡¦s spot size. The laser crystal was mounted onto a copper mount which was cooled by the Vapochill cooling system. In addition, we also tried to rotate the crystal and obtained a peak power of 192 mW with only 4 mm cavity length. The result is the highest output power of microchip blue laser to our knowledge. Using lens duct as the pump transport optics can further miniaturize this composite-chip blue laser.

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