Mosses new to Hong Kong (1)

Ten moss species - Garkea flexuosa (Griffith) Marg. & Nork., Campylopus laxitextus Lac., Fissidens dubius P. Beauv., Fissidens ceylonensis Dozy & Molk, Fissidens maceratus Mitt., Philonotis thwaitesii Mitt., Isopterygium minutirameum (C. Muell.)Jaeg., Homalia trichomanoides (Hedw.) B.S.G., Pogonatum neesii (C. Muell.) Dozyand Polytrichum formosum Hedw. are reported new to Hong Kong. Among them, five are new to Guangdong Province of China

Testing for Mean-Coherent Regular Risk Spanning

Coherent risk measures have received considerable attention in the recent literature.Coherent regular risk measures form an important subclass: they are empirically identifiable, and, when combined with mean return, they are consistent with second order stochastic dominance.As a consequence, these risk measures are natural candidates in a mean-risk trade-off portfolio choice.In this paper we develop a mean-coherent regular risk spanning test and related performance measure.The test and the performance measure can be implemented by means of a simple semi-parametric instrumental variable regression, where instruments have a direct link with the stochastic discount factor.We illustrate applications of the spanning test and the performance measure for several coherent regular risk measures, including the well known expected shortfall.portfolio choice;coherent risk;spanning test

A mathematica‐based CAL matrix‐theory tutor for scientists and engineers

Under the TLTP initiative, the Mathematics Departments at Imperial College and Leeds University are jointly developing a CAL method directed at supplementing the level of mathematics of students entering science and engineering courses from diverse A‐level (or equivalent) backgrounds. The aim of the joint project is to maintain — even increase ‐ the number of students enrolling on such first‐year courses without lowering the courses’ existing mathematical standards

Socioeconomic characteristics of payang seine (lampara) and driftnet fisheries in West Sumatra, Indonesia

A proportionate random sample survey of 10 percent of the driftnet and Payang seine fishers in West Sumatra was carried out in 1998. A total of 45 driftnet and 66 lampara fishers were interviewed to obtain socioeconomic data on the fisheries. About 40 percent of the driftnet and 76 percent of the lampara fishers owned and operated their fishing vessels and gears indicating a high level of ownership of fishing assets by these small scale fishers. The lampara catches consisted mainly of eastern little tuna, skipjack tuna, yellow fin tuna and mackerel, while the driftnets caught mainly Spanish mackerel, Indian mackerel, eastern little tuna and scad

Spin Analysis of Supersymmetric Particles

The spin of supersymmetric particles can be determined at $e^+e^-$ colliders unambiguously. This is demonstrated for a characteristic set of non-colored supersymmetric particles -- smuons, selectrons, and charginos/neutralinos. The analysis is based on the threshold behavior of the excitation curves for pair production in $e^+e^-$ collisions, the angular distribution in the production process and decay angular distributions. In the first step we present the observables in the helicity formalism for the supersymmetric particles. Subsequently we confront the results with corresponding analyses of Kaluza-Klein particles in theories of universal extra space dimensions which behave distinctly different from supersymmetric theories. It is shown in the third step that a set of observables can be designed which signal the spin of supersymmetric particles unambiguously without any model assumptions. Finally in the fourth step it is demonstrated that the determination of the spin of supersymmetric particles can be performed experimentally in practice at an $e^+e^-$ collider.Comment: 39 pages, 14 figure

Motion studies of high current arcs using an optical fibre array imaging system

This paper presents an integrated portable measurement system for thestudy of high speed and high temperature unsteady plasma flows such as thosefound in the vicinity of high current switching arcs. The system permits direct andnon-intrusive measurement of arc light emission images with a capture rate of 1million images per second (1MHz), and 8 bit intensity resolution. Novel softwaretechniques are reported to measure arc trajectories. Results are presented on singlehigh current (2kA) discharge events where the electrode and arc runner surfaces areinvestigated using 3D laser scanning methods; such that the position of the arc rootson the runner can be correlated to the measured trajectories. The results showevidence of the cathode arc root stepping along the arc runners<br/

Motion studies of cathode roots in high current arcs using an optical fibre array based imaging system

This paper presents an integrated portable measurement system for the study of high speed and high temperature unsteady plasma flows such as those found in the vicinity of high current switching arcs. The system permits direct and non-intrusive measurement of arc light emission images with a capture rate of 1 million images per second (1MHz), and 8 bit intensity resolution. Novel software techniques are reported to measure arc trajectories. Results are presented on single high current (2kA) discharge events where the electrode and arc runner surfaces are investigated using 3D laser scanning methods; such that the position of the arc roots on the runner can be correlated to the measured trajectories. The results show evidence of the cathode arc root stepping along the arc runners, and regions of where the arc runner is eroded by a stationary arc

Motion studies of high current arcs using an optical fibre array imaging system

This paper presents an integrated portable measurement system for thestudy of high speed and high temperature unsteady plasma flows such as thosefound in the vicinity of high current switching arcs. The system permits direct andnon-intrusive measurement of arc light emission images with a capture rate of 1million images per second (1MHz), and 8 bit intensity resolution. Novel softwaretechniques are reported to measure arc trajectories. Results are presented on singlehigh current (2kA) discharge events where the electrode and arc runner surfaces areinvestigated using 3D laser scanning methods; such that the position of the arc rootson the runner can be correlated to the measured trajectories. The results showevidence of the cathode arc root stepping along the arc runners<br/

Assessing Credit with Equity: A CEV Model with Jump to Default

Unlike in structural and reduced-form models, we use equity as a liquid and observable primitive to analytically value corporate bonds and credit default swaps.Restrictive assumptions on the .rm.s capital structure are avoided.Default is parsimoniously represented by equity value hitting the zero barrier either diffusively or with a jump, which implies non-zero credit spreads for short maturities.Easy cross-asset hedging is enabled.By means of a tersely speci.ed pricing kernel, we also make analytic credit-risk management possible under systematic jump-to-default risk.Equity;Corporate Bonds;Credit Default Swaps;Constant-Elasticity-of-Variance (CEV) Diffusion;Jump to Default

Superconductivity near the vibrational mode instability in MgCNi3

To understand the role of electron-phonon interaction in superconducting MgCNi$_{3}$ we have performed density functional based linear response calculations of its lattice dynamical properties. A large coupling constant $\lambda$= 1.51 is predicted and contributing phonons are identified as displacements of Ni atoms towards octahedral interstitials of the perovskite lattice. Instabilities found for some vibrational modes emphasize the role of anharmonic effects in resolving experimental controversies.Comment: 4 pages, 4 eps figures, replaces the older versio