Tunable circular dipolelike system in graphene: Mixed electron-hole states

Coupled electron-hole states are realized in a system consisting of a combination of an electrostatic potential barrier and ring-shaped potential well, which resembles a circular dipole. A perpendicular magnetic field induces confined states inside the Landau gaps which are mainly located at the barrier or ring. Hybridizations between the barrier and ring states are seen as anticrossings in the energy spectrum. As a consequence, the energy levels show an oscillating dependence on the electrostatic potential strength in combination with an oscillating migration of the wave functions between the barrier and ring. At the anticrossing points the quantum state consists of a mixture of electron and hole. The present system mimics closely the behavior of a relativistic dipole on gapped graphene.Comment: 9 pages and 9 figure

The Role of Dendritic Cells in the Pathogenesis of COPD: Liaison Officers in the Front Line

Dendritic cells are professional antigen presenting cells linking innate and adaptive immune responses. Different dendritic cell subsets were identified in human lung, each with their own functional characteristics. As innate and adaptive immune responses are activated in Chronic Obstructive Pulmonary Disease (COPD), dendritic cells could play a role in the pathogenesis of this disease. Indeed, cigarette smoke appears to modulate dendritic cell function in vitro and alters dendritic cell numbers and function in cigarette smoke exposed mice. The number of pulmonary dendritic cells differs between COPD patients, smokers and non-smokers. Moreover, the number of Langerhans-type dendritic cells increases with the severity of the disease. In this review we will discuss the scientific evidence regarding the role of dendritic cells in COPD and we will put forward the concept of modulation of dendritic cell differentiation and function as a crucial step in the pathogenesis of COPD

Confinement and edge effects on atomic collapse in graphene nanoribbons

Atomic collapse in graphene nanoribbons behaves in a fundamentally different way as compared to monolayer graphene, due to the presence of multiple energy bands and the effect of edges. For armchair nanoribbons we find that bound states gradually transform into atomic collapse states with increasing impurity charge. This is very different in zig-zag nanoribbons where multiple quasi-one-dimensional \emph{bound states} are found that originates from the zero energy zig-zag edge states. They are a consequence of the flat band and the electron distribution of these bound states exhibits two peaks. The lowest energy edge state transforms from a bound state into an atomic collapse resonance and shows a distinct relocalization from the edge to the impurity position with increasing impurity charge

Partner Choices in Long Established Migrant Communities in Belgium

This paper aims to shed light on the partner choices of Moroccan, Turkish, Congolese, and Algerian migrants in Belgium. Three partner choices are distinguished: marrying a partner from the country of origin (partner migration), marrying a local co-ethnic partner, and establishing a mixed marriage. We focused on the role of migration history and transnational links, culture (religion, language), skin colour and structural characteristics of the district migrants live in (mainly community size) to gain further insight into the partner choices of migrants in Belgium. Our data comprise an extraction of the Belgian national register (2001-2008) and focus on first marriages among first, 1.5, and second generation migrants of Moroccan, Turkish, Algerian, and Congolese origin (N=52,142). We apply a multinomial logistic multilevel design to simultaneously incorporate individual and contextual effects at the district level. The main conclusion from this paper is that the partner selection pattern in early 21st century Belgian society still bears the traces of the starting conditions that migrant groups experienced when they first entered the country. While this continuity is important to understand the situation citizens with a migrant origin have to deal with today, it does not make change impossible. In fact, for the Turkish and Moroccan group, research recently showed a quite strong decline in transnational marriages and a modest increase in mixed marriages. These are indications that after 50 years of migration a transition towards full inclusion in Belgian society is not beyond reach. The conditions analysed in this paper, namely the strength of transnational networks, the cultural boundaries and the ethnic community size, may help to understand why this inclusion takes such a long period of time

Statistiek

B

Stock market’s reactions to revelation of tax evasion: an empirical assessment

Additionally to the financial crisis causing a world recession, Liechtenstein’s financial sector has been challenged by the so-called “Zumwinkel-Affair”, when a whistle-blower sold data of hundreds of tax evaders to international tax authorities. This paper investigates the impact of this affair, separated from the financial crisis, on the daily stock prices of banks from Liechtenstein. An “unconventional” augmented GARCH-model (labelled as “augmented amalGARCH”), which outperforms conventional models, is introduced and analyses the dynamical pattern and other influences on risk and average performance. Besides other findings, it can be concluded that the Zumwinkel-Affair had an (accumulating) effect on risk of stocks, but surprisingly no impact on average stock returns could be detected