The Friendship Experiences of Academic High Achievers in Hong Kong Secondary Schools

This research thesis explores the complex, unique and contextual friendship experiences of ten exceptionally high academic achievers in mainstream Hong Kong secondary schools. The research was conducted through semi-structured interviews and the data was thematically analysed. Three broad themes were found and presented in the thesis. They include friendship needs, friendship processes and contextual factors of high academic achievers in school friendship development. The findings show the complex and unique experiences of these individual students who shared similar academic qualities. The thesis also includes suggestions for professional practice and further directions for inquiry on gifted education and students' school friendship development in Hong Kong

Dynamics of the formation of a hydrogel by a pathogenic amyloid peptide: islet amyloid polypeptide

Many chronic degenerative diseases result from aggregation of misfolded polypeptides to form amyloids. Many amyloidogenic polypeptides are surfactants and their assembly can be catalysed by hydrophobic-hydrophilic interfaces (an air-water interface in-vitro or membranes in-vivo). We recently demonstrated the specificity of surface-induced amyloidogenesis but the mechanisms of amyloidogenesis and more specifically of adsorption at hydrophobic-hydrophilic interfaces remain poorly understood. Thus, it is critical to determine how amyloidogenic polypeptides behave at interfaces. Here we used surface tensiometry, rheology and electron microscopy to demonstrate the complex dynamics of gelation by full-length human islet amyloid polypeptide (involved in type II diabetes) both in the bulk solution and at hydrophobic-hydrophilic interfaces (air-water interface and phospholipids). We show that the hydrogel consists of a 3D supramolecular network of fibrils. We also assessed the role of solvation and dissected the evolution over time of the assembly processes. Amyloid gelation could have important pathological consequences for membrane integrity and cellular functions

A plane slide that occurred during construction of a national expressway in Chongqing, SW China

This paper presents a case study of a major landslide that occurred during the construction of a national expressway in Chongqing, southwestern China. The landslide was a typical plane failure associated with steep cutting in weathered mudstone and sandstone. The weathered mudstone block slipped down along the bedding interface of the mudstone and sandstone and formed an open gap that measured some 6 to 8 m high, by 2 to 7 m wide and 53 m long in the hillside slope. This study referred that the landslide was caused by the combined effect of the following factors: (a) an unsupported high and steep cutting in weathered mudstone; (b) an exposed bedding interface between the incompetent weathered mudstone and the competent sandstone that daylights within the cut slope; (c) the mudstone and sandstone bedding interface as a pre-existing folding tectonic shear plane of low shear strength; and (d) the possible presence of a ground water table in the weathered mudstone perched on the relative impervious sandstone bedding surface. The case study highlights the importance of engineering geological mapping during and immediately after the formation of a new cut slope. It also emphasises the importance of identification of the pre-existing tectonic shear planes along the mudstone and sandstone bedding interface in similar geological terrain.published_or_final_versio

Critical motility-induced phase separation belongs to the Ising universality class

A collection of self-propelled particles with volume exclusion interactions can exhibit the phenomenology of a gas-liquid phase separation, known as motility-induced phase separation (MIPS). The nonequilibrium nature of the system is fundamental to the phase transition; however, it is unclear whether MIPS at criticality contributes a novel universality class to nonequilibrium physics. We demonstrate here that this is not the case by showing that a generic critical MIPS belongs to the Ising universality class with conservative dynamics

Scaling behaviour of non-equilibrium planar N-atic spin systems under weak fluctuations

Starting from symmetry considerations, we derive the generic hydrodynamic equation of nonequilibrium XY spin systems with N-atic symmetry under weak fluctuations. Through a systematic treatment we demonstrate that, in two dimensions, these systems exhibit two types of scaling behaviours. For N = 1, they have long-range order and are described by the flocking phase of dry polar active fluids. For all other values of N, the systems exhibit quasi long-range order, as in the equilibrium XY model at low temperature

Diversity of phase transitions and phase separations in active fluids

Active matter is not only indispensable to our understanding of diverse biological processes, but also provides a fertile ground for discovering novel physics. Many emergent properties impossible for equilibrium systems have been demonstrated in active systems. These emergent features include motility-induced phase separation, a long-ranged ordered (collective motion) phase in two dimensions, and order-disorder phase coexistences (banding and reverse-banding regimes). Here, we unify these diverse phase transitions and phase coexistences into a single formulation based on generic hydrodynamic equations for active fluids. We also reveal a novel comoving coexistence phase and a multicritical point

Prediction of 3-d surface topography in ultra-precision machining

2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Erosional effects on runout of fast landslides, debris flows and avalanches: A numerical investigation

The mechanism of mass changes in debris transportation process is an important topic in the study of fast landslides, debris flows and avalanches. Basal erosion is recognised as a dynamic interaction between the original moving material and the entrained basal topsoil shearing along their non-slip contact surface. In this paper we propose a new concept of yield rate and establish the erosional relationship to bridge these two systems. A pertinent mathematical model and numerical implementation are formulated. Parametric numerical experiments are conducted to compare the erosional effects. The simulated results are consistent with available experimental and field observations. The influence of the involvement of the erosive material on runout behaviour and the global mobility of the moving material are elucidated. The proposed method is then employed to analyse a recent debris flow event in northern Italy. The excellent match to the field data gives it a plausible potential application to the analysis of this type of gravity-driven flow with significant erosion. Defined in a dimensionless form, the proposed yield rate can be estimated conveniently in general geotechnical practices.published_or_final_versio

Generalised framework of limit equilibrium methods for slope stability analysis

A generalised framework is proposed in this paper incorporating almost all of the existing limit equilibrium methods of slices for slope stability analysis with general slip surfaces. The force and moment equilibrium equations are derived in terms of the factor of safety and the initially assumed normal stress distribution over the slip surface, multiplied by a modification function involving two auxiliary unknowns. These equations are then analytically solved to yield explicit expressions for the factor of safety. Various assumptions regarding the interslice forces can be transformed into a unified form of expression for the normal stress distribution along the slip surface. An iterative procedure is developed to expedite the convergence of the solution for the factor of safety. Experience to date indicates that the process generally converges within a few iterations. Computation schemes are suggested to avoid numerical difficulty, especially in computing the factor of safety associated with the rigorous Janbu method. The present framework can be readily implemented in a computer program, giving solutions of slope stability associated with a number of conventional methods of slices.published_or_final_versio

Critical phenomenon of the order-disorder transition in incompressible active fluids

We study incompressible systems of motile particles with alignment interactions. Unlike their compressible counterparts, in which the order-disorder (i.e., moving to static) transition, tuned by either noise or number density, is discontinuous, in incompressible systems this transition can be continuous, and belongs to a new universality class. We calculate the critical exponents to $\mathcal{O}(\epsilon )$ in an $\epsilon =4-d$ expansion, and derive two exact scaling relations. This is the first analytic treatment of a phase transition in a new universality class in an active system