Global lopsided instability in a purely stellar galactic disc

It is shown that pure exponential discs in spiral galaxies are capable of supporting slowly varying discrete global lopsided modes, which can explain the observed features of lopsidedness in the stellar discs. Using linearized fluid dynamical equations with the softened self-gravity and pressure of the perturbation as the collective effect, we derive self-consistently a quadratic eigenvalue equation for the lopsided perturbation in the galactic disc. On solving this, we find that the ground-state mode shows the observed characteristics of the lopsidedness in a galactic disc, namely the fractional Fourier amplitude A$_1$ increases smoothly with the radius. These lopsided patterns precess in the disc with a very slow pattern speed with no preferred sense of precession. We show that the lopsided modes in the stellar disc are long-lived because of a substantial reduction ($\sim$ a factor of 10 compared to the local free precession rate) in the differential precession. The numerical solution of the equations shows that the ground-state lopsided modes are either very slowly precessing stationary normal mode oscillations of the disc or growing modes with a slow growth rate depending on the relative importance of the collective effect of the self-gravity. N-body simulations are performed to test the spontaneous growth of lopsidedness in a pure stellar disc. Both approaches are then compared and interpreted in terms of long-lived global $m=1$ instabilities, with almost zero pattern speed.Comment: 15 pages, 23 figures, accepted in MNRA

Spin polarized STM spectra of Dirac Fermions on the surface of a topological insulator

We provide a theory for the tunneling conductance $G(V)$ of Dirac Fermions on the surface of a topological insulator as measured by a spin-polarized scanning tunneling microscope tip for low bias voltages $V$. We show that $G(V)$ exhibits an unconventional dependence on the direction of magnetization of the tip and can be used to measure the magnitude of the local out-of-plane spin orientation of the Dirac Fermions on the surface. We also demonstrate that if the in-plane rotational symmetry on the surface of the topological insulator is broken by an external field, then $G(V)$ acquires a dependence on the azimuthal angle of the magnetization of the tip. We explain the role of the Dirac Fermions in this unconventional behavior and suggest experiments to test our theory.Comment: 7 pages, 5 Fig

Learning from Rohingya Refugee Repatriation to Myanmar

The author examines the role of the United Nations and the international community in establishing criteria for the return of Rohingya refugees to Myanmar from Bangladesh. This study highlights the importance of the international community in establishing standards and supporting the return, even in cases where the national governments involved (Myanmar and Bangladesh) have never signed the un Convention on the Status of Refugees. The author concludes that the repatriation of Rohingya refugees from Bangladesh has been relatively successful, and that the pattern seen in this return could be usefully replicated in order to bring about the voluntary repatriation of other refugee groups to Myanmar.L’auteur examine le rôle joué par les Nations Unies et la communauté internationale dans l’élaboration de critères pour le retour de réfugiés Rohingya du Bangladesh vers le Myanmar. L’étude souligne le poids considérable dont pèse la communauté internationale lorsqu’il est question d’établir des critères et de soutenir le processus de retour, et cela, même dans des cas où les gouvernements concernés (le Myanmar et le Bangladesh) n’ont jamais signé la Convention des Nations Unies sur le statut des réfugiés. L’auteur conclut que cette opération de rapatriement de réfugiés Rohingya du Bangladesh s’est relativement bien passée et que la tendance observée dans ce retour pourrait être utilement reproduite afin d’obtenir le rapatriement volontaire d’autres groupes de réfugiés vers le Myanmar

The Chittagong Hill Tracts Peace Accord: A Landmark Model for a Viable Solution to the Refugee Problem

The Chittagong Hill Tracts (CHT) area of Bangladesh, home to the Chakma and eleven other major tribes, has experienced civil strife since the early 1970s. The demand for autonomy by the local tribal leaders and the settlement of Bengalees into the CHT sparked armed insurgency. The fighting between the tribal hill people and Bangladlesh army continued for almost two decades, resulting in a large flight of predominantly Chakma refugees into India. Talks between India and Bangladesh officials regarding these refugees resulted in the creation of tribally-Ied local governments in the CHT, and a rehlilbilitation package for Chakma and other refugees. This process laid the groundwork for the Chittagong Hill Tracts Peace Accord signed on December 2,1997 between the Bangladesh government and the Hill Tracts People's Solidarity Association (PCJSS). Shortly after, about 60,000 refugees returned to the CHT from India, and guerillas surrendered their arms. The objective of this background paper is to examine the Chittagong Hill Tracts Peace Accord and its role in providing a framework for a viable solution to the refugee problem in the CHT. It also highlights those aspects of the Accord which serve as a model for preventing refugee flight and displacement of people in any conflict situation.La zone des Traités de la Colline de Chittagong (Chittagong Hill Tracts: CHT) au Bangladesh, patrie des Chakma et de onze autres importantes tribus, fait l'objet d'enjeux sécessionnistes depuis le début des années 1970. Les aspirations autonomistes des chef tribaux locaux et l'installation de bengalis sur la CHT a fait éclater l'insurrection armée. Les affrontements entre les populations tribales de la colline et l'armée du Bangladesh se sont poursuivis pendant presque deux décennies, entraînant un flot massif de réfugiés à prédominance Chakma vers l'Inde. Des pourparlers entre l'Inde et les officiels du Bangladesh au sujet de ces réfugiés ont mené à la création de gouvernements locaux sous contrôle tribal dans la CHT, ainsi qu'à une ententede réhabilitation pour les Chakmaet autres réfugiés. Ce processus a pavé la voie à l'Accords de Paix de la zone des Traités de la Colline de Chittagong, signé le 2 décembre 1997 entre le gouvernement du Bangladesh et l'Association de Solidarité des Peuples de la Colline (PCJSS). Peu après, environ 60,000 réfugiés sont retournés dans la CHT depuis l'Inde, et la guérilla a déposé les armes. Le but de cet article de fond est de procéder à un examen de l'Accord de Paix de la zone des Traités de la Colline de Chittagong, et le rôle qu'il joue dans la mise en place d'un cadre susceptible de mener à une solution viable du problème des réfugiés dans la CHT. L'article attire aussi l'attention sur les aspects de l'accord pouvant servir de modèle pour une prévention des flots de réfugiés dans toutes situations de conflit

Energy Constrained Generation Dispatch Based on Price Forecasts Including Expected Values and Risk

A number of price forecasting methods are used to forecast wholesale (spot) electricity prices. The forecasts are evaluated for both accuracy and variation in accuracy (risk). These forecasts are used to balance revenue against forecasting error risk in dispatching constrained generation. The best dispatch method found was based on the half-hours with the maximum demand

Aerosol Characteristics at a high-altitude station Nainital during the ISRO-GBP Land Campaign-II

During the second land campaign (LC-II) organised by ISRO-GBP, extensive ground-based measurements of aerosol characteristics were carried out over Manora Peak (29.4oN; 79.5oE; 1951 metres above mean sea level), Nainital (a high altitude station located in the Shivalik ranges of Central Himalayas) during the dry, winter season (December) of 2004. These measurements included the spectral aerosol optical depths (AOD), columnar water vapour content (W), Total Columnar Ozone (TCO), total number concentration (NT) of near surface aerosols, mass concentration of black carbon (MB), aerosol mass loading (MT), and Global Solar Radiation. Based on these measured parameters, we present the results on the near-surface and columnar properties of atmospheric aerosols at Nainital.Comment: Published in the Proceedings of the ISRO-GBP Land-Campaign-II meeting, Physical Research Laboratory, Ahmadabad (Inida), March 200

Differential Biofeedback Intervention In Moderating Inhibited Performance In Soccer

Performance excellence in soccer crucially depends on mental toughness or more specifically the aspect of emotional flexibility and hardiness of the player. Since indices of projective evaluations can reveal hidden emotional crises and internal conflicts, psychobiological evaluations could substantiate with the inner emotionality revealed to provide etiological information related to performance hindrances in soccer. Present study was carried out to identify the efficacy of skin conductance (Sc) biofeedback in regulation of sudomotor nerve activity (SNA) and of electromyography (EMG) biofeedback in regulation of peak torque and maximal voluntary contraction (MVC) in modification of performance catastrophe in soccer. All of them were assessed with autonomic measures (SNA and Sc amplitude); electromyography evaluation of emotionality and MVC revealed through EMG. Forty National-selection group soccer players of Malaysia were randomly categorized into four groups (Gr. A, N = 10, no-intervention control group); Gr. B (who received Sc biofeedback training); Gr. C (received EMG biofeedback intervention) and Gr. D (players who received combined training of Sc and EMG biofeedback intervention). Players of intervention groups received their respective trainings for 12 weeks (15 min.s /day for 3 days/ week). Postintervention analyses revealed marked improvement in the soccer players who received Sc and EMG biofeedback intervention, and the combined biofeedback training was evident as most efficient intervention technique in modulating emotionality as well as muscle potentiality. Analysis of variance and repeated measure of ANOVA were done to observe shared aetiology in the form of direct, inverse and supportive relationships between psychobiological and emotional indices related to performance crises in soccer. Comprehensive understanding of the confounding relationships between subjective feelings emotionality and corroborative psychobiological indices as predictor of high performance was achieved