Quasinormal frequencies of a massless scalar in the hidden Kerr/CFT proposal

The hidden Kerr/CFT proposal implies that the massless scalar wave equation in the near-region and low-frequency limit respects a hidden SL(2,R)$\times$SL(2,R) invariance in the Kerr black hole spacetime. We may use this symmetry to determine quasinormal frequencies (QNFs) of the massless scalar wave propagating around the Kerr black hole algebraically. It is shown that QNFs obtained using the hidden conformal symmetry near the horizon correspond approximately to not only those of scalar perturbation around the near-horizon region of a nearly extremal Kerr (NEK) black hole, but also those of non-equatorial scalar modes around the NEK black hole. This indicates that the hidden Kerr/CFT proposal could determine quasinormal modes and frequencies of the massless scalar wave around the NEK (rapidly rotating) black hole approximately.Comment: 1+25 pages, 1 figure, revised version to appear in GER

Photocatalytic Reduction of Co2 Using Zns Pillaring on Kaolin Catalyst

Increasing of carbon dioxide (CO2) concentration in atmosphere has gain major attention by the researchers. This is due to CO2 ability to absorb heat from the UV light and emits the heat to atmosphere resulted in earth warming. In order to overcome this problem, the researchers come out with many solutions. Conventional method and also Advanced Oxidation Process (AOP) have been invented as a way to reduce the concentration of the predominant greenhouse gases especially CO2. However, AOP has come out as the emerging technologies due to its practicality in reduction process in industry. This study will be focusing on one of the AOP which is photocatalytic reduction process of CO2. In this process, a photocatalyst was needed. In this research, photocatalyst used was ZnS-Kaolin, a combination of semiconductor ZnS and phyllosilicate mineral, Kaolin. ZnS-Kaolin was prepared by using two methods which are hydrothermal method and simpler impregnation method. In this photocatalytic reduction process, the catalyst was dispersed in medium solution, NaOH aqueous and hence help to catalyze the process. The characteristics of the developed ZnS-Kaolin were observed by using Scanning Electron Microscope (SEM) and Thermal Gravimetric Analyzer (TGA). The effect of parameters such as irradiation time and dosage of ZnS-Kaolin used were observed and studied. This process was produced usable products such as methanol and was analyzed by using High Performance Liquid Chromatography (HPLC). Based on the results, from SEM analysis, it was found that raw Kaolin was constructed from hexagonal flakes structure. Meanwhile, both ZnS-Kaolin prepared from Hydrothermal and Impregnation methods are consists of leaf-like layers structure with ZnS nanoparticles deposited on Kaolin structure. From TGA analysis, it was found that ZnS-Kaolin prepared from Hydrothermal method has higher thermal resistance compared to ZnS-Kaolin prepared from Impregnation method. Meanwhile, for photoreduction process of CO2, methanol production was observed to be maximum by using ZnS-Kaolin prepared from Hydrothermal method at dosage of 0.75 g and at 2 hours irradiation time. In conclusion, ZnS-Kaolin prepared by using Hydrothermal method shows better performance in photoreduction process of CO2 compared to ZnS-Kaolin prepared from Impregnation method

Franciaországi romák beiskoláztatása

Franciaországban ma körülbelül 350 000 francia roma állampolgár él, Rhone megyében pedig – ahol én dolgoztam – körülbelül 5000. Franciául a romákat „Gens du Voyage”-nek hívják, mely magyarra lefordítva utazó embereket jelent

The bright optical flash from GRB 060117

We present a discovery and observation of an extraordinarily bright prompt optical emission of the GRB 060117 obtained by a wide-field camera atop the robotic telescope FRAM of the Pierre Auger Observatory from 2 to 10 minutes after the GRB. We found rapid average temporal flux decay of alpha = -1.7 +- 0.1 and a peak brightness R = 10.1 mag. Later observations by other instruments set a strong limit on the optical and radio transient fluxes, unveiling an unexpectedly rapid further decay. We present an interpretation featuring a relatively steep electron-distribution parameter p ~ 3.0 and providing a straightforward solution for the overall fast decay of this optical transient as a transition between reverse and forward shock.Comment: Accepted to A&A, 4 pages, corected few typos pointed out by X.F. W

Kremer-Grest models for commodity polymer melts: Linking theory, experiment and simulation at the Kuhn scale

The Kremer-Grest (KG) polymer model is a standard model for studying generic polymer properties in Molecular Dynamics simulations. It owes its popularity to its simplicity and computational efficiency, rather than its ability to represent specific polymers species and conditions. Here we show, that by tuning the chain stiffness it is possible to adapt the KG model to model melts of real polymers. In particular, we provide mapping relations from KG to SI units for a wide range of commodity polymers. The connection between the experimental and the KG melts is made at the Kuhn scale, i.e. at the crossover from chemistry-specific small scale to the universal large scale behavior. We expect Kuhn scale-mapped KG models to faithfully represent universal properties dominated by the large scale conformational statistics and dynamics of flexible polymers. In particular, we observe very good agreement between entanglement moduli of our KG models and the experimental moduli of the target polymers.Comment: Compared to previous versions. Final update and corrections to numbers in table

No. 21: Cross-Border Raiding and Community Conflict in the Lesotho-South African Border Zone

Movement backwards and forwards across borders for work is often considered to be the primary form of unauthorized movement in Southern Africa. In southern Lesotho, a new and particularly dangerous form of two-way cross-border movement has become entrenched. This situation warrants the label “crisis”; a crisis which is devastating parts of the countryside in both Lesotho and the northern Eastern Cape Province of South Africa. Media and official attention has focused on the extreme violence which accompanies cross-border stock raiding. This paper seeks to understand the social and economic roots and impacts of cross-border stock theft. Such an analysis is a vital first-step towards the resolution of the conflict since it shows not only why the violence occurs but who stands to benefit from its perpetuation. The analysis is also helpful to understanding the extent to which the existence of an international border is implicated in the cycle and counter-cycle of violence. This paper concludes with an assessment of official reaction, or inaction, on the crisis. The findings are based upon wide-ranging interviews with 147 respondents in 10 villages in southern Lesotho. A complementary study is now recommended on the South African side of the border. The stock theft epidemic is characterized by the following features: Although stock theft is not new to this border zone, it became more widespread, organized and violent in the 1990s. Some 71% of the Basotho stockowners reported having had stock stolen since 1990, many more than once. Over 40% of nonstockowners say they are without animals because of stock theft. Since 1990, 85% of stockowners in the border villages have lost animals to thieves as compared with 49% from non-border villages. Shepherds from border villages also report a higher rate of victimisation (83%) than those further removed from the border (50%). Most cattle and sheep are stolen from cattle posts where they are guarded only by shepherds. Stock is also taken from village kraals and, on occasion, whole villages have been attacked and all the stock driven off. Villagers in all ten villages rate stock theft as a serious problem. Stock thieves come from within Lesotho as well as across the border in South Africa. Basotho stock thieves also carry out raids in South Africa and vice-versa. Gun use is widespread, although South African raiders seem to have greater access to arms. Much of the theft appears to be coordinated by well-organised criminal gangs but reliable information on their composition and organization is difficult to access. Criminal networks in Lesotho and South Africa also cooperate to dispose of stolen animals in the lowlands of Lesotho and as far afield as Port Elizabeth, Durban and Welkom The upsurge in stock theft is clearly related to growing poverty in the region. On both sides of the border, mine retrenchments have hit hard, sending experienced miners home and denying young men access to wage employment. Not only has this exacerbated household and community poverty, but it has provided willing foot-soldiers for stock thieves. Stock raiding produces further impoverishment, insecurity and suspicion, fuelling the escalating cycle of theft and counter-theft. Though not itself in dispute or a source of conflict per se, the Lesotho-South African border plays an essential role in the organization and impact of stock theft. There are significant differences in vulnerability and impact between villages close to the border and those further inland. The international border leads to a distinctive pattern of stock theft. In the simplest scenario, raiders from one side steal from border villages on the other and vice-versa and drive the stock back over the border. The situation becomes more problematic when Basotho stock thieves use the border as a refuge, stealing from Basotho and driving the animals across the border into South Africa to sell or exchange with South African thieves. Cross-border counter-raids to retrieve lost stock and revenge attacks are also common on both sides of the border. South African victims then target Basotho border villages for revenge raids, resulting in great tension and friction between ordinary Basotho and South Africans. The only Lesotho village reporting harmonious cross-border relations borders a white South African farming area. However, white border farmers are not aloof from the conflict. Lesotho police and villagers are adamant that some white South African farmers are implicated in cross-border theft. Stock raiding has major negative impacts on households, communities and cross-border interaction. The impacts also extend to the national economy. In Qacha’s Nek and Quthing districts, production of wool and mohair has fallen significantly in the last 5 years. Livestock holdings have dropped and the numbers of stockless households has increased. Farmers are reluctant to invest in breeding cattle as households debate the merits of getting rid of their cattle. One prominent stock-owner recently lost M200,000 of stock. Stock theft has also had a deleterious effect on agriculture, reducing the availability of oxen for ploughing fields. No one is immune from small-scale and organized raiding. Stock theft, coupled with decreasing agricultural production and increasing unemployment, deepens poverty and desperation. At the household and community level, the research found the following: Nearly 90% of respondents state their household economies have been negatively affected by stock theft. A household’s entire wealth and livelihood can be wiped out in one attack. Escalating stock theft and related violence have profound social consequences, bringing fear and insecurity to ordinary people. People are abandoning their villages and migrating to town and to South Africa to look for work. Community relations have become fraught with tension and suspicion. Nearly half of all stockowners interviewed suspect specific individuals within their own village are involved in the theft of animals – acting either as informants or actual thieves. Invariably it is the poor who are fingered and stigmatised. Communal cooperation such as livestock loaning for ploughing and mafisa (sharing of products) is in steep decline, as are cultural activities and celebrations which involve the slaughter of animals. Cross-border cooperation, activities and initiatives have collapsed and there is considerable animosity and hatred between the communities on either side of the border. Even casual visiting and shopping have all but ceased. Prevention efforts have involved some cross-border cooperation between villages to apprehend thieves and return cattle but these efforts are sporadic and make little dent on the problem. They often also lead to vicious reprisals from stock-theft syndicates. Vigilantism is on the rise in the face of widespread perceptions that the police and the courts on both sides of the border are either ineffectual or corrupt. This paper examines the inadequacies of the policing of the crisis, highlighting the low rates of arrest and prosecution. The difficulties of geography and inadequate resources which hamper effective policing are highlighted. Only in areas where the army is stationed or soldiers patrol the border has there been any marked decrease in theft. The situation is bound to deteriorate further unless there is effective national-level attention and intervention. The low-level civil war in the nearby Tsolo district of South Africa in 1997 was fuelled by a potent mix of poverty, mine retrenchments and stock theft. This conflict could well pale in comparison with the volatile situation building in the southern Lesotho border zone. Here, the same combination of factors are compounded by ethnic and national difference, and the strategic manipulation of borders by stock thieves on both sides. Both governments need to recognize that this local crisis could escalate into a major conflagration and intervene to defuse the situation, calm tensions and work towards effective policing and a political solution. Within Lesotho, the passage of a new Stock Theft Act promises heavy penalties for the shadowy figures involved in organized raiding, provided they can be caught. The institution of a national stock register also seems a step in the right direction though its likely effectiveness is debated. Both the Lesotho and South African governments should acknowledge that a crisis situation exists and that this is a regional problem. Only when national governments, working together with local stakeholders, take the problem seriously and begin cooperating can workable initiatives to halt this devastating social and economic plague be implemented