Wong Ka Wah = 奇異星的特性 / 黃嘉華. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 98-101). / Text in English; abstracts in English and Chinese. / Wong Ka Wah = Qi yi xing de te xing / Huang Jiahua. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- History of Compact Stars --- p.1 / Chapter 1.2 --- The Proposal of Strange Quark Stars --- p.2 / Chapter 1.3 --- Outline of the Thesis --- p.3 / Chapter 2 --- Cold Equation of State from Perturbative QCD --- p.6 / Chapter 2.1 --- Description of Strange Quark Matter --- p.7 / Chapter 2.2 --- MIT Bag Model --- p.8 / Chapter 2.3 --- Perturbative QCD --- p.10 / Chapter 2.4 --- Comparison with MIT Bag Model --- p.11 / Chapter 3 --- Static Structure of Strange Stars --- p.16 / Chapter 3.1 --- Static Equilibrium --- p.16 / Chapter 3.2 --- Models --- p.18 / Chapter 3.3 --- Results of Global Properties and Discussions --- p.18 / Chapter 4 --- Stability of Strange Quark Matter --- p.25 / Chapter 4.1 --- Absolute Stable Condition --- p.25 / Chapter 4.2 --- Weak Stable Condition --- p.26 / Chapter 4.3 --- Stability Condition Compared to Neutron Stars --- p.27 / Chapter 4.4 --- Conclusion --- p.28 / Chapter 5 --- Effect of Massive Strange Quarks --- p.31 / Chapter 5.1 --- Numerical Analysis of the Effect of Strange Quark Mass on the EOS --- p.33 / Chapter 5.2 --- Structure of Strange Stars with Strange Quark Mass --- p.37 / Chapter 5.3 --- Conclusion --- p.38 / Chapter 6 --- QCD Phase Transition in a Compact Star --- p.46 / Chapter 6.1 --- Cooling Properties --- p.47 / Chapter 6.1.1 --- Heat capacity of quark stars --- p.49 / Chapter 6.1.2 --- Luminosity of quark stars --- p.50 / Chapter 6.1.3 --- Microphysics of the neutron star cooling --- p.54 / Chapter 6.2 --- Handling of the Phase Transition --- p.56 / Chapter 6.3 --- The Models --- p.59 / Chapter 6.4 --- Results --- p.60 / Chapter 6.4.1 --- Method 1 --- p.61 / Chapter 6.4.2 --- Method 2 --- p.66 / Chapter 6.5 --- Discussion and Conclusion --- p.66 / Chapter 7 --- Formation of a Strange Star --- p.73 / Chapter 7.1 --- Formalism of the Problem --- p.73 / Chapter 7.2 --- Lagrangian Hydrodynamics --- p.74 / Chapter 7.3 --- Hot Equation of State --- p.75 / Chapter 7.3.1 --- Nuclear Matter EOS --- p.75 / Chapter 7.3.2 --- Quark Matter EOS --- p.77 / Chapter 7.3.3 --- Mixed Phase --- p.78 / Chapter 7.4 --- Initial Models --- p.78 / Chapter 7.5 --- Results --- p.80 / Chapter 7.6 --- Discussion and Conclusion --- p.81 / Chapter 8 --- Conclusion --- p.95 / Bibliography --- p.98 / Chapter A --- Solving the EOS --- p.102 / Chapter B --- Solving C from Eq. (7.10) --- p.105

Dark respiration rates of the aerial shoots of Arceuthobium tsugense, obtained by manometric and IRGA techniques, show production of C02to range between 155-300 µl CO2 g-1h-1 with evidence of seasonal variation. Experiments with 14C02 indicate that the aerial shoots are capable of some photosynthetic CO2 fixation, with 10-15% of the available 14C incorporated by the plant tissue in one hour.The portions of the o aerial shoots which are most active in C02 fixation are the young terminal regions. Biochemical characterization of the products of photosynthesis reveals that 80-90% of the incorporated 14C is ethanol soluble. Ten percent of the ethanol fraction is lipoidal in nature, the rest is H20 soluble. Ion exchange separation of the H20 soluble portion shows that 16-25% of the 14C activity is cationic, about 25% anionic, with the balance neutral. Aspartic acid, glutamic acid, and valine are present in the cationic fraction, with additional free amino acids indicated. IRGA experiments indicate an apparent photosynthetic CO2 fixation capacity of 80-90 percent of the ethanol fraction is lipoidal in nature, the rest is H20 soluble. Ion exchange separation of the H20 soluble portion shows that 16-25% of the 14C activity is cationic, about 25% anionic, with the balance neutral. Aspartic acid, glutamic acid, and valine are present in the cationic fraction, with additional free amino acids indicated. IRGA experiments indicate an apparent photosynthetic CO2 fixation capacity of 80-90 µl CO2 g-1 h-1, or 25-30% of the amount of C02 produced by respiration. The significance of these findings is discussed with respect to nutrition of the parasite.

Arceuthobium americanum is a flowering plant which parasitizes Pinus contorta (Lodgepole pine). This study examined branch performance of P. contorta infected to varying degrees with A. americanum.

Super-Dwarf wheat plants were grown in simulation growth chambers under 12 treatments with three photoperiods (18 h, 21 h, 24 h) and four carbon-dioxide levels (360, 1200, 3000, and 7000 11mol/mol). Carbon-dioxide concentrations affected flower initiation rates of Super-Dwarf wheat. The optimum C02level for flower initiation and development was 1200molμ•mol-1. Super-optimum C01 levels delayed flower initiation, but did not decrease final flower bud number per head. Longer photoperiods not only accelerated flower initiation rates, but also decreased deleterious effects of super-optimum C02. Flower bud size and head length at the same developmental stage were larger under longer photoperiods. But final flower bud number was not affected by photoperiod. Stomatal densities on the abaxial surface were more sensitive to the variation of photoperiod and C02 level than those on the adaxial surface for Super-Dwarf wheat. Stomatal density did not significantly change on the adaxial surface, but was significantly decreased on the abaxial surface under longer photoperiods and higher C02 levels at 27 day after planting (DAP). Cell-walls of both stem and leaf tissues did not significantly change with variation of photoperiod and carbon-dioxide levels at either seedling stage or mature stage. McDowell fixative was suitable for long-term storage of plant tissue for use in light microscopy. When stored up to 180 d, there was no significant change in leaf thickness, shape and size of mesophyll cells, and shape of chloroplasts for wheat leaves under the light microscope.

Includes bibliographical references (l5 leaves) The aim of the work presented in this thesis was to develop molecular genetic markers for YD2 (the gene in barley which provides protection against barley yellow dwarf luteovirus) which could be used for the marker assisted selection of the gene in breeding programs and enable the gene to be cloned via a map-based approach.

The family Callitrichidae encompasses the marmosets and tamarins, the smallest of the anthropoid primates and one of the most species-rich of platyrrhine families. Seven new species of Amazonian marmosets (Callithrix, Callitrichidae) have been discovered in recent years, as well as the exceptional dwarf marmoset Callibella humilis. Most of these species were described on the basis of their pelage and presumed separation by major rivers. I performed analyses of craniometric variables by taxa and by river basins, in order to determine if there are significant cranial distinctions between taxa separated by rivers. I analyzed quantitative cranial and mandibular characters of Callibella humilis to determine if it could be distinguished from other callitrichids. I found that Callibella is clearly distinct from all other genera of marmosets and tamarins, in particular in the morphology of the lower jaw. I also analyzed representative species of Amazonian Callithrix and found support for the theory of separation by river-barriers. In my analyses the Amazonian marmosets were divided into three separate species groups, with the easternmost species (Callithrix argentata and C. leucippe) strongly distinct and separated from the others by the broad Rio Tapajos. Two additional species, C. chrysoleuca and C. saterei, formed a discrete group in the central Amazon, and the westernmost species - C. melanura, C. nigriceps and the Rondonia marmoset - formed a third distinct group. These results from cranial morphology align with recent genetic studies indicating that the Amazonian marmosets are strongly divided by the Rio Tapajos, and offer additional support to the theory of river-barriers. Although these species are typically considered to be of low conservation priority, many of them are found in areas experiencing accelerated deforestation. An initial analysis of protected-area coverage for the Amazonian marmosets demonstrates that while some species may be found in a number of protected areas, others are virtually uncovered, and the lack of comprehensive information on their distributions may preclude an effective conservation strategy. The dwarf marmoset Callibella is known from an exceptionally restricted range, with almost no protected areas, and this unique species should be a conservation priority.

The absorption due to pairs of H₂ molecules is an important opacity source in the atmospheres of various types of planets and cool stars, such as late stars, low mass main sequence stars, brown dwarf stars, cool white dwarf stars, the ambers of the smaller, burnt out main sequence stars, exoplanets, etc., and therefore of special astronomical interest. Astronomers are interested in the outer planets as they still contain primordal matter. Furthermore, recent observations by the Hubble space telescope (in operation since 1990) have revealed several thousand cool white dwarf stars with temperatures of several thousand Kelvin. It is surprising that none of them has temperatures lower than roughly 4000 K. This means that the white dwarf stars have not had enough time to cool down to the temperature of the cosmic background radiation. Astrophysicists believe that this information can be used for an alternative and more accurate method of cosmochronology. However, the emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra of their cores, largely due to collision-induced absorption by collisional complexes of residual hydrogen and helium in the stellar atmospheres. In order to model the radiative processes in these atmospheres, which have temperatures of several thousand kelvin, one needs accurate knowledge of the induced dipole and potential energy surfaces of the absorbing collisional complexes, such as H₂--H₂, H₂--He, and H₂--H. These come from quantum-chemical calculations, which, for the high temperatures and high photon energies under consideration in this work, need to take into account that the H₂ bonds can be stretched or compressed far from equilibrium length. Since no laboratory measurements for these high temperatures and photon energies exist, one has to undertake \textit{ab initio} calculations which take into account the high vibrational and rotational excitation of the involved hydrogen molecules. However, before one attempts to proceed to higher temperatures and photon energies where no laboratory measurements exist it is good to check that the formalism is correct and reproduces the results at temperatures and photon energies where laboratory measurements exist, that is, at and below room temperature and for photon energies up to about 1.5 eV. In this work a formalism is developed to compute the binary collision-induced absorption of simple molecular complexes up to temperatures of thousands of kelvin and photon energies up to 2.5 eV, properly taking into account vibrational and rotational dependencies of the induced dipole and potential energy surfaces. In order to make the computational effort feasible, the isotropic potenial approximation is employed. The formalism is applied to collisional complexes of H₂--H₂, D₂--D₂, H₂--He, D₂--He, T₂--He, and H₂--H, and compared with existing laboratory measurements. / text

This dissertation is an observational exploration of the exciting physics that can be enabled by high-speed photometric monitoring of extremely low-mass (< 0.25 M[subscript sun symbol]) white dwarf stars, which are found in some of the most compact binaries known. It includes the cleanest indirect detection of gravitational waves at visible wavelengths, the discovery of pulsations in He-core WDs, the strongest evidence for excited p-mode pulsations in a WD, the discovery of the first tidally distorted WDs and their use to constrain the low-end of the WD mass-radius relationship, and the strongest cases of Doppler beaming observed in a binary system. It is the result of the more than 220 nights spent at McDonald Observatory doing high-speed photometry with the Argos instrument on the 2.1 m Otto Struve telescope, which has led to a number of additional exciting results, including the discovery of an intermediate timescale in the evolution of cooling DA WDs and the discovery of the most massive pulsating WD, which should have an ONe-core and should be highly crystallized. / text

Although exotic objects like supermassive black holes (SMBHs) and dark matter halos do not emit or interact with light, we can still detect them across the vastness of space. By observing the gravitational dance of objects we can see, astronomers are able to infer the mass of the invisible objects they orbit. This has led to the discovery that nearly every massive galaxy hosts a SMBH at its center, and has confirmed that every galaxy is embedded in an extended halo of dark matter. However, the practice of inferring mass from the motions of bright kinematics tracers has many complications, not the least of which is that we seldom observe more than the line-of-sight component of the instantaneous velocity of a star. Consequently, astronomers must build dynamical models of the galaxies they wish to study. These models often rely on overly restrictive assumptions, or are crippled by degeneracies amongst their parameters and lack predictive power. In this thesis, I introduce a significant advancement into the field of dynamical modeling. My modeling technique is based on the powerful principle of orbit superposition, also known as Schwarzschild Modeling. This technique is robust to many of the degeneracies associated with dynamical modeling, and has enjoyed much success in measuring the SMBHs and dark matter halos of large elliptical or bulge-dominated galaxies. I use it in Chapter 2 to accurately measure the SMBH in the Sombrero Galaxy (NGC 4594) and to constrain its dark matter halo. Unfortunately, when measuring dark matter halos with Schwarzschild Modeling, the modeler is required to adopt a parameterization for the dark matter density profile. Often this is precisely the quantity one wishes to measure. To avoid this reliance on a priori parameterizations, I introduce a technique that calculates the profile non-parametrically. Armed with this powerful new technique, I set out to measure the distribution of dark matter in the halos of some of the smallest galaxies in the Universe. These dwarf spheroidal galaxies (dSphs) orbit the Milky Way as satellites, and their dark matter content has been studied extensively. However, the models used to probe their halos have been simplistic and required overly restrictive assumptions. As a result, robust conclusions about their dark matter content have remained elusive. Into this controversial and active area of study, I bring Non-Parametric Schwarzschild Modeling. The results I find offer the most robust and detailed measurements of the dark matter profiles in the dSphs to date. I begin my study with the first application of standard Schwarzschild Modeling to any dSph galaxy by using it in Chapter 3 on Fornax. This chapter details the process of re-tooling Schwarzschild Modeling for the purpose of measuring these small galaxies. In Chapter 4, I introduce the fully non-parametric technique, and apply it to Draco as proof of concept. Chapter 5 presents the main results of this thesis. Here I apply Non-Parametric Schwarzschild Modeling to Draco, Carina, Fornax, Sculptor, and Sextans. By relaxing the assumption of a parameterization for the dark matter profile, I find a variety of profile types in these five galaxies---some of which are consistent with past observations, others consistent with predictions from simulations, and still others were completely unanticipated. Finally, in Chapter 6 I describe the modeling of these galaxies in more detail. I demonstrate the accuracy of Non-Parametric Schwarzschild Modeling by recovering a known dark matter profile from artificial simulated data. I also expound upon the modeling results by presenting the detailed orbit structure of the five dSphs. Lastly, I compare my results to hydrodynamical simulations to explore the link between dark matter profile type and the baryon content of the dSphs. / text

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