Chemodynamical history of the Galactic Bulge

The Galactic Bulge can uniquely be studied from large samples of individual stars, and is therefore of prime importance for understanding the stellar population structure of bulges in general. Here the observational evidence on the kinematics, chemical composition, and ages of Bulge stellar populations based on photometric and spectroscopic data is reviewed. The bulk of Bulge stars are old and span a metallicity range -1.5<~[Fe/H]<~+0.5. Stellar populations and chemical properties suggest a star formation timescale below ~2 Gyr. The overall Bulge is barred and follows cylindrical rotation, and the more metal-rich stars trace a Box/Peanut (B/P) structure. Dynamical models demonstrate the different spatial and orbital distributions of metal-rich and metal-poor stars. We discuss current Bulge formation scenarios based on dynamical, chemical, chemodynamical and cosmological models. Despite impressive progress we do not yet have a successful fully self-consistent chemodynamical Bulge model in the cosmological framework, and we will also need more extensive chrono-chemical-kinematic 3D map of stars to better constrain such models.Comment: 9 figures, 55 pages final version to appear in the Annual Reviews of Astronomy & Astrophysics, volume 5

Phase behaviour of a symmetrical binary fluid mixture in a field

Integral equation theory calculations within the mean spherical approximation (MSA) and grand canonical Monte Carlo (MC) simulations are employed to study the phase behaviour of a symmetrical binary fluid mixture in the presence of a field arising from unequal chemical potentials of the two particle species. Attention is focused on the case for which, in the absence of a field, the phase diagram exhibits a first order liquid-liquid transition in addition to the liquid-vapor transition. We find that in the presence of a field, two possible subtypes of phase behaviour can occur, these being distinguished by the relationship between the critical lines in the full phase diagram of temperature, density, and concentration. We present the detailed form of the respective phase diagrams as calculated from MSA and compare with results from the MC simulations, finding good overall agreement.Comment: 8 pages, 2 figure

Higher-order-in-spin interaction Hamiltonians for binary black holes from Poincar\'e invariance

The fulfillment of the space-asymptotic Poincar\'e algebra is used to derive new higher-order-in-spin interaction Hamiltonians for binary black holes in the Arnowitt-Deser-Misner canonical formalism almost completing the set of the formally $1/c^4$ spin-interaction Hamiltonians involving nonlinear spin terms. To linear order in $G$, the expressions for the $S^3p$- and the $S^2p^2$-Hamiltonians are completed. It is also shown that there are no quartic nonlinear $S^4$-Hamiltonians to linear order in $G$.Comment: REVTeX4, 14 pages; center-of-mass-vector corrected Eq. (2.25) and modified coefficients of the Hamiltonian Eq. (7.3) and corresponding source terms Eqs. (7.5) and (7.6) following hereof; version to appear in Phys Rev

Full 3D Quantum Transport Simulation of Atomistic Interface Roughness in Silicon Nanowire FETs

The influence of interface roughness scattering (IRS) on the performances of silicon nanowire field-effect transistors (NWFETs) is numerically investigated using a full 3D quantum transport simulator based on the atomistic sp3d5s* tight-binding model. The interface between the silicon and the silicon dioxide layers is generated in a real-space atomistic representation using an experimentally derived autocovariance function (ACVF). The oxide layer is modeled in the virtual crystal approximation (VCA) using fictitious SiO2 atoms. -oriented nanowires with different diameters and randomly generated surface configurations are studied. The experimentally observed ON-current and the threshold voltage is quantitatively captured by the simulation model. The mobility reduction due to IRS is studied through a qualitative comparison of the simulation results with the experimental results

Asymmetry in shape causing absolute negative mobility

We propose a simple classical concept of nanodevices working in an absolute negative mobility (ANM) regime: The minimal spatial asymmetry required for ANM to occur is embedded in the geometry of the transported particle, rather than in the channel design. This allows for a tremendous simplification of device engineering, thus paving the way towards practical implementations of ANM. Operating conditions and performance of our model device are investigated, both numerically and analytically.Comment: 6 pages; accepted for publication in PR

Why do education vouchers fail at the ballot box?

We compare a uniform voucher regime against the status quo mix of public and private education, focusing on the distribution of welfare gains and losses across house- holds by income. We argue that the topping-up option available under uniform vouchers is not sufficiently valuable for the poorer households, so the voucher regime is defeated at the polls. Our result depends critically on the opting-out feature in the current system.Education ; Households

Why do education vouchers fail at the ballot box?

We compare a uniform voucher regime against the status quo mix of public and private education, focusing on the distribtuion of welfare gains and losses across households by income. We argue that the topping-up option available under uniform vouchers is not su¢ ciently valuable for the poorer households, so the voucher regime is defeated at the polls. Our result depends critically on the opting-out feature in the current system.vouchers, political economy, opting out, education finance