Ma, Kwok Wai = 相互作用的超冷原子於一維系統之有關課題 / 馬國威. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 69-74). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Ma, Kwok Wai = Xiang hu zuo yong de chao leng yuan zi yu yi wei xi tong zhi you guan ke ti / Ma Guowei.

It is a well-known phenomenon that during Marangoni condensation of binary mixtures, a small concentration of more volatile constituent with smaller surface tension gives significant heat transfer enhancements. This is due to surface tension gradients causing instability in condensate film, resulting in a pseudo-dropwise mode of condensation which resembles closely to dropwise condensation of pure fluid on the hydrophobic surface, consequently, the film gets thinner with lower thermal resistance across the condensate film and thus higher heat transfer coefficient is achieved. Marangoni condensation of steam-ethanol mixtures has been widely investigated in the past. However, Marangoni condensation of self-rewetting fluids e.g. steam-butanol is yet to be investigated where the constituent in a small concentration is a less volatile component. Marangoni condensation of steam-ethanol, steam-butanol and steam-propanol mixtures has been investigated on a horizontal smooth tube at an atmospheric pressure. For all experiments, concentrations by mass in the boiler feed when cold prior to start of the experiment were 0.001%, 0.005%, 0.01%, 0.025%, 0.05%, 0.1%, 0.5% and 1.0%. The coolant temperature rise was measured accurately with a ten-junction thermopile. Tube wall temperature was measured using four thermocouples embedded in the test tube wall. Effects of pressure and vapour velocity over a wide range of vapour-to-surface temperature difference have been investigated. Care was taken to avoid error due to the presence of air in the vapour. Marangoni condensation of steam-butanol and steam propanol mixtures show significant heat transfer enhancements compared with that of steam-ethanol mixtures. Higher Heat flux and heat-transfer coefficients were observed. For the steam-ethanol mixtures, enhancement ratio (heat flux or heat-transfer coefficient divided by the corresponding value for pure steam condensation on a horizontal smooth tube for the same vapour-to-surface temperature difference and vapour velocity) of 5.5 was found at an ethanol concentration of 0.01%. For steam-butanol mixtures, the maximum enhancement ratio was found to be 11 at a concentration of 0.005% and 0.01%. For steam-propanol mixtures, the maximum enhancement ratio of 8.5 was found at the same mass concentrations as steam-butanol mixtures. Enhancement ratio was generally higher at lower ethanol concentrations, increases at first with increasing vapour-to-surface temperature difference and subsequently decreases at high vapour-to-surface temperature difference. Finally, a semi-empirical model was proposed to predict the Marangoni condensation of steam-ethanol mixtures based on the vapour phase diffusion theory of Sparrow and Marchall (1969) and pure steam dropwise theory of Rose (2002).

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No description available.

Errors in chromosome segregation during the first division of female meiosis are very common in humans and result in aneuploidy leading to reproduction problems. Chromosome segregation depends on the formation and function of the meiotic spindle as well as the structure of chromosomes, which need to condense to be able to orient and segregate properly. It is important to understand the mechanisms underlying the female meiotic spindle function and chromosome condensation to gain insight into female fertility problems. The female meiotic spindle assembles without centrosomes, so the mechanisms ensuring microtubule nucleation, spindle assembly and establishment of bipolarity act differently from those of mitosis or male meiosis. I identified a set of genes that are required for microtubule nucleation, spindle maintenance and centromere orientation in Drosophila female meiosis. This was accomplished by mapping previously uncharacterized Drosophila mutants and depleting already known genes by RNAi. I discovered that several proteins have a different role in female meiosis as compared to mitosis, which provides insight into the major differences between these systems. Little is known about the molecular mechanisms of chromosome condensation. The roles of only a few factors, such as condensin complexes, have been studied previously, and the evidence suggests that there are more molecular players required for chromosome condensation. To discover molecular mechanisms critical to this process, I depleted various chromosomal proteins by RNAi and screened for abnormalities of metaphase chromosome morphology in Drosophila oocytes by immunostaining and live imaging. I found that the conserved kinase NHK-1 plays a role in chromosome condensation in female meiosis. BAF is a critical NHK-1 substrate in this process and its phosphorylation is required for detachment of the chromosomes from the nuclear envelope to allow proper condensation. Also, I discovered that the nucleosome remodelling complex NuRD is crucial for chromosome condensation, especially for the chromosome arms. As a result of my PhD project I identified multiple factors required for meiotic spindle function. I also discovered two novel pathways of chromosome condensation that require the NuRD complex and NHK-1 activity.

Liu, Xiaopi = 光格子势中玻色爱因斯坦凝聚体的压缩,纠缠与激发谱 / 刘小披. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 97-100). / Abstracts in English and Chinese. / Liu, Xiaopi = Guang ge zi shi zhong bo se ai yin si tan ning ju ti de ya suo, jiu chan yu ji fa pu / Liu Xiaopi. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Review of Superfluidity and B.E. Condensation --- p.1 / Chapter 1.2 --- Our Understanding of superfluidity --- p.4 / Chapter 1.3 --- Non-classicality in Quantum Mechanics --- p.8 / Chapter 2 --- One-Component BECs in optical lattices --- p.16 / Chapter 2.1 --- Introduction: The Hamiltonian --- p.16 / Chapter 2.2 --- The Hamiltonian in Quasi-momentum space --- p.19 / Chapter 2.3 --- Bogoliubov Method and Equation of Motion --- p.21 / Chapter 2.3.1 --- Squeezing and Condensation --- p.27 / Chapter 2.3.2 --- Two-mode Entanglement and Squeezing --- p.31 / Chapter 3 --- Matrix method approach to ground state BECs --- p.39 / Chapter 3.1 --- Matrix method --- p.39 / Chapter 3.2 --- Ground state and Particle Distribution --- p.42 / Chapter 3.3 --- Correlation in Pair Ground State --- p.46 / Chapter 4 --- Attractive BECs in optical lattices --- p.50 / Chapter 5 --- 2-component BECs in optical lattice --- p.56 / Chapter 5.1 --- Model Hamiltonian --- p.56 / Chapter 5.2 --- Excitation Spectrum and Critical super-fluid velocity --- p.59 / Chapter 5.3 --- Excitation spectrum and Phase Separation Dynamics --- p.63 / Chapter 5.4 --- Excitation Spectrum for Asymmetric 2-component BECs --- p.67 / Chapter 6 --- Multi-Mode Squeezing of 2-component BECs in optical lattices --- p.69 / Chapter 6.1 --- Simultaneous Diagonalization --- p.69 / Chapter 6.2 --- Equation of Motion and Variance Matrix --- p.70 / Chapter 6.3 --- U(n) Squeezing of Variance Matrix --- p.75 / Chapter 6.4 --- Squeezing in the case qA≠ qB and nA≠ nB --- p.82 / Chapter 7 --- Entanglement between 2-component BECs in optical lattices --- p.83 / Chapter 7.1 --- Variance matrix in block diagonal --- p.83 / Chapter 7.2 --- 2-component entangled variance matrix --- p.86 / Chapter 7.3 --- Logarithmic negativity --- p.89 / Chapter 7.4 --- Beat oscillation mode of logarithmic negativity --- p.91 / Chapter 8 --- Conclusion and Outlook --- p.95 / Bibliography --- p.97

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The experimental realisation of Bose-Einstein condensation in 1995 opened up a wealth of opportunities for probing quantum states of matter. The development of many tools used to manipulate such ultracold samples and the rapid progress on understanding these systems will ultimately lead to great technological advances. The work described in this thesis contributes to this worldwide effort and here we present experiments which investigate the properties and behaviour of ultracold atoms. In the first experiments presented here, we have studied features of Bose-Einstein condensates loaded into an optical lattice formed by the interference of two laser beams. By altering the phase of the lattice at the Bragg condition, we investigate the effect of the phase shift on the dressed-atom states. We find that by applying a +(-)[pi]/2 phase shift after a [pi]/2 (3[pi]/2) lattice pulse, we are able to quickly and precisely load the ground and first excited eigenstates of the lattice. In another experiment, we use a periodically pulsed stationary optical lattice and a tightly-confined Bose-Einstein condensate to investigate the nonlinear kicked harmonic oscillator at quantum anti-resonance. We observe periodic behaviour in the energy of the condensate, however we show that the nonlinearity is not strong enough to enter the predicted chaotic regime. In addition, the amplitude of the energy oscillations damps to an average value and we relate this to dephasing of the coupling across the finite momentum width of the condensate. In the second series of experiments, we use a double-well magnetic collider to investigate cold collisions between ultracold atoms. By creating two ultracold clouds in a double-well magnetic trap and then transforming the trap to a single well, we accelerate the clouds together to initiate a collision between them. We describe in detail the analysis method that we use to extract the partial-wave phase shifts from the matter-wave interference patterns associated with the scattered atoms. We then implement a two-photon pulse, which is applied prior to the collision to convert one of the clouds to a different spin state. This enables the study of scattering between distinguishable states which exhibited anti-symmetric p-wave scattering via the interference with the s- and d-waves previously observed for indistinguishable states. We find the position of the d-wave shape resonance and compare our data to a coupled-channels model.

Occult deposition is the direct uptake of cloudwater by vegetation that comes into physical contact with wind-driven cloud droplets. This can be a significant pathway for hydrological and chemical fluxes from the atmosphere to some forests. Methods for estimating cloudwater fluxes to forests are reviewed. Previous studies have neglected the fact that cloudwater is not a conservative atmospheric quantity. This invalidates traditional micrometeorological approaches for estimation of cloudwater fluxes to forests. A theory is developed to predict the change in the cloudwater flux with height due to condensation in the updrafts of orographic cloud, allowing estimation of surface uptake via eddy correlation measurements while accounting for condensation. The performances of three microphysical instruments are examined. From collocated measurements, errors in cloud liquid water content are determined for a Particulate Volume Monitor (PVM) and a Forward Scattering Spectrometer Probe (FSSP) to be less than 0.01 g m⁻³ and 0.035 g m⁻³ respectively. Similarly, the error bounds for surface-normal cloud liquid water fluxes are found to be 2 mg m⁻² s⁻¹ for the PVM and 3.5 mg m⁻² s⁻¹ for the FSSP. Smaller errors are found to be associated with the uncertainty in the direction of the flux relevant to surface uptake. The FSSP is seen to have larger errors when droplet concentrations exceed 600 cm⁻³. A vertical divergence is detected in the cloudwater flux; the downward flux decreases with increasing distance from the surface, usually changing sign by 15 m above ground. Five candidate processes are identified as possible explanations for this measured flux divergence. A scale analysis shows that the liquid water source (condensation due to pseudoadiabatic ascent) is largely responsible for the change in flux with height. Accounting for the change in flux with height results in a near doubling of the estimated surface flux relative to the flux measured at a height of 10 m in the surface layer for this silver fir forest. This factor applies to chemical as well as liquid water fluxes. This source of liquid water also is seen to be important in developing a simple model for cloudwater deposition. / Graduation date: 1997

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