Spin-spin interaction in the bulk of topological insulators

We apply mean-field theory and Hirsch-Fye quantum Monte Carlo method to study the spin-spin interaction in the bulk of three-dimensional topological insulators. We find that the spin-spin interaction has three different components: the longitudinal, the transverse and the transverse Dzyaloshinskii-Moriya-like terms. When the Fermi energy is located in the bulk gap of topological insulators, the spin-spin interaction decays exponentially due to Bloembergen-Rowland interaction. The longitudinal correlation is antiferromagnetic and the transverse correlations are ferromagnetic. When the chemical potential is in the conduction or valence band, the spin-spin interaction follows power law decay, and isotropic ferromagnetic interaction dominates in short separation limit.Comment: 9 pages, 10 figure

DRGs payment reform and cost management: A case study in a public hospital in China

This dissertation bases on evidence collected from a Chinese public hospital to analyse the process followed of Diagnosis-Related Groups (DRGs) implementation and the link between DRGs and hospital cost management. Methodologically, this study employs case study approach, aiming to develop an in-depth and rich understandings of DRGs practices and cost management in a specific setting. Multiple sources of evidence were collected by the researcher, allowing him to analyze the process of DRGs case grouping, cost collection and analysis, and of cost control. The case study suggests that implementing DRGs in public hospitals represents an important issue to their sustainable development and that the development of appropriate management and cost accounting systems is key to the DRGs reform that is taking place in China.Esta dissertação baseia-se em evidência recolhida num hospital público na China para analisar a implementação de Grupos de Diagnóstico Homogeneos (GDH) e a sua ligação com a gestão de custos no hospital. Em termos metodológicos, o estudo adota o método de estudo de caso, com o objetivo de produzir um conhecimento profundo e rico relativo à prática de GDHs e gestão de custos numa organização específica. O pesquisador coletou evidência de fontes múltiplas, permitindo-lhe apresentar e analisar o processo de implementação dos GDHs no hospital, e analisar como a gestão de custos através dos GDHs suporta estratégias de desenvolvimento do hospital. O estudo de caso conduzido sugere que a implementação de GDHs em hospitais públicos é uma questão importante para seu desenvolvimento sustentável, e que a gestão financeira e de custos são a chave para a reforma do sector da saúde em andamento na China

Early-stage star forming cloud cores in GLIMPSE Extended Green Objects (EGOs) as traced by organic species

In order to investigate the physical and chemical properties of massive star forming cores in early stages, we analyse the excitation and abundance of four organic species, CH3OH, CH3OCH3, HCOOCH3 and CH3CH2CN, toward 29 Extended Green Object (EGO) cloud cores that were observed by our previous single dish spectral line survey. The EGO cloud cores are found to have similar methanol J_3-J_2 rotation temperatures of ~44 K, a typical linear size of ~0.036 pc, and a typical beam averaged methanol abundance of several 10^(-9) (the beam corrected value could reach several 10^(-7)). The abundances of the latter three species, normalized by that of methanol, are found to be correlated also across a large variety of clouds such as EGO cloud cores, hot corinos, massive hot cores and Galactic Center clouds. The chemical properties of the EGO cloud cores lie between that of hot cores and hot corinos. However, the abundances and abundance ratios of the four species can not be satisfactorily explained by recent chemical models either among the EGO cloud cores or among the various types of cloud cores from literature

Bidding to drive: Car license auction policy in Shanghai and its public acceptance

Increased automobile ownership and use in China over the last two decades has increased energy consumption, worsened air pollution, and exacerbated congestion. However, the countrywide growth in car ownership conceals great variation among cities. For example, Shanghai and Beijing each had about 2 million motor vehicles in 2004, but by 2010, Beijing had 4.8 million motor vehicles whereas Shanghai had only 3.1 million. Among the factors contributing to this divergence is Shanghai’s vehicle control policy, which uses monthly license auctions to limit the number of new cars. The policy appears to be effective: in addition to dampening growth in car ownership, it generates annual revenues up to 5 billion CNY (800 million USD). But, despite these apparent successes, the degree to which the public accepts this policy is unknown. This study surveys 524 employees at nine Shanghai companies to investigate the policy acceptance of Shanghai’s license auction by the working population, and the factors that contribute to that acceptance: Perceived policy effectiveness, affordability, equity concerns, and implementation. Respondents perceive the policy to be effective, but are moderately negative towards the policy nonetheless. However, they expect that others accept the policy more than they do. Respondents also hold consistently negative perceptions about the affordability of the license, the effects on equity, and the implementation process. Revenue usage is not seen as transparent, which is exacerbated by a perception that government vehicles enjoy advantages in obtaining a license, issues with the bidding process and technology, and difficulties in obtaining information about the auction policy. Nevertheless, respondents believe that license auctions and congestion charges are more effective and acceptable than parking charges and fuel taxes. To improve public acceptability of the policy, we make five recommendations: Transparency in revenue usage; transparency in government vehicle licensing and use, categorizing licenses by vehicle type, implementation and technology improvements to increase bidding convenience, and policies that restrict vehicle usage in congested locations

In-plane noncollinear exchange coupling mediated by helical edge states in Quantum Spin Hall system

We study the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction mediated by helical edge states in quantum spin hall system. The helical edge states induce an in-plane noncollinear exchange coupling between two local spins, in contrast to the isotropic coupling induced in normal metal. The angle between the two local spins in the ground state depends on the Fermi level. This property may be used to control the angle of spins by tuning the electric gate.Comment: 4 pages, 1 figur