Observation of the spin-orbit gap in bilayer graphene by one-dimensional ballistic transport

We report on measurements of quantized conductance in gate-defined quantum point contacts in bilayer graphene that allow the observation of subband splittings due to spin-orbit coupling. The size of this splitting can be tuned from 40 to 80 $\mu$eV by the displacement field. We assign this gate-tunable subband-splitting to a gap induced by spin-orbit coupling of Kane-Mele type, enhanced by proximity effects due to the substrate. We show that this spin-orbit coupling gives rise to a complex pattern in low perpendicular magnetic fields, increasing the Zeeman splitting in one valley and suppressing it in the other one. In addition, we observe the existence of a spin-polarized channel of 6 e$^2$/h at high in-plane magnetic field and of signatures of interaction effects at the crossings of spin-split subbands of opposite spins at finite magnetic field.Comment: 5 pages, 4 figures, Supplement 6 figure

Proving termination of programs automatically with AProVE

AProVE is a system for automatic termination and complexity proofs of Java, C, Haskell, Prolog, and term rewrite systems (TRSs). To analyze programs in high-level languages, AProVE automatically converts them to TRSs. Then, a wide range of techniques is employed to prove termination and to infer complexity bounds for the resulting TRSs. The generated proofs can be exported to check their correctness using automatic certifiers. For use in software construction, we present an AProVE plug-in for the popular Eclipse software development environment

Linear and nonlinear optical properties of some organoxenon derivatives

We employ a series of state-of-the-art computational techniques to study the effect of inserting one or more Xe atoms in HC2H and HC4H, on the linear and nonlinear optical (L&NLO) properties of the resulting compounds. It has been found that the inserted Xe has a great effect on the L&NLO properties of the organoxenon derivatives. We analyze the bonding in HXeC2H, and the change of the electronic structure, which is induced by inserting Xe, in order to rationalize the observed extraordinary L&NLO properties. The derivatives, which are of interest in this work, have been synthesized in a Xe matrix. Thus the effect of the local field (LF), due to the Xe environment, on the properties of HXeC2H, has also been computed. It has been found that the LF effect on some properties is significant. The calculations have been performed by employing a hierarchy of basis sets and the techniques MP2 and CCSD(T) for taking into account correlation. For the interpretation of the results we have employed the complete active space valence bond and CASSCF/CASPT2 [email protected]

Spatial and temporal variations in ammonia emissions – a freely accessible model code for Europe

Deriving a parameterisation of ammonia emissions for use in chemistry-transport models (CTMs) is a complex problem as the emission varies locally as a result of local climate and local agricultural management. In current CTMs such factors are generally not taken into account. This paper demonstrates how local climate and local management can be accounted for in CTMs by applying a modular approach for deriving data as input to a dynamic ammonia emission model for Europe. Default data are obtained from information in the RAINS system, and it is demonstrated how this dynamic emission model based on these input data improves the NH<sub>3</sub> calculations in a CTM model when the results are compared with calculations obtained by traditional methods in emission handling. It is also shown how input data can be modified over a specific target region resulting in even further improvement in performance over this domain. The model code and the obtained default values for the modelling experiments are available as supplementary information to this article for use by the modelling community on similar terms as the EMEP CTM model: the GPL licencse v3

Vicinal Surfaces and the Calogero-Sutherland Model

A miscut (vicinal) crystal surface can be regarded as an array of meandering but non-crossing steps. Interactions between the steps are shown to induce a faceting transition of the surface between a homogeneous Luttinger liquid state and a low-temperature regime consisting of local step clusters in coexistence with ideal facets. This morphological transition is governed by a hitherto neglected critical line of the well-known Calogero-Sutherland model. Its exact solution yields expressions for measurable quantities that compare favorably with recent experiments on Si surfaces.Comment: 4 pages, revtex, 2 figures (.eps

Improved modelling of atmospheric ammonia over Denmark using the coupled modelling system DAMOS

A local-scale Gaussian dispersion-deposition model (OML-DEP) has been coupled to a regional chemistry-transport model (DEHM with a resolution of approximately 6 km × 6 km over Denmark) in the Danish Ammonia Modelling System, DAMOS. Thereby, it has been possible to model the distribution of ammonia concentrations and depositions on a spatial resolution down to 400 m × 400 m for selected areas in Denmark. DAMOS has been validated against measured concentrations from the dense measuring network covering Denmark. Here measured data from 21 sites are included and the validation period covers 2–5 years within the period 2005–2009. A standard time series analysis (using statistic parameters like correlation and bias) shows that the coupled model system captures the measured time series better than the regional- scale model alone. However, our study also shows that about 50% of the modelled concentration level at a given location originates from non-local emission sources. The local-scale model covers a domain of 16 km × 16 km, and of the locally released ammonia (NH<sub>3</sub>) within this domain, our simulations at five sites show that 14–27% of the locally (within 16 km × 16 km) emitted NH<sub>3</sub> also deposits locally. These results underline the importance of including both high-resolution local-scale modelling of NH<sub>3</sub> as well as the regional-scale component described by the regional model. The DAMOS system can be used as a tool in environmental management in relation to assessments of total nitrogen load of sensitive nature areas in intense agricultural regions. However, high spatio-temporal resolution in input parameters like NH<sub>3</sub> emissions and land-use data is required

Anisotropic susceptibility of ferromagnetic ultrathin Co films on vicinal Cu

We measure the magnetic susceptibility of ultrathin Co films with an in-plane uniaxial magnetic anisotropy grown on a vicinal Cu substrate. Above the Curie temperature the influence of the magnetic anisotropy can be investigated by means of the parallel and transverse susceptibilities along the easy and hard axes. By comparison with a theoretical analysis of the susceptibilities we determine the isotropic exchange interaction and the magnetic anisotropy. These calculations are performed in the framework of a Heisenberg model by means of a many-body Green's function method, since collective magnetic excitations are very important in two-dimensional magnets.Comment: 7 pages, 3 figure

Inhibitory Control Across the Preschool Years: Developmental Changes and Associations with Parenting

The normative developmental course of inhibitory control between 2.5 and 6.5 years, and associations with maternal and paternal sensitivity and intrusiveness were tested. The sample consisted of 383 children (52.5% boys). During four annual waves, mothers and fathers reported on their children’s inhibitory control using the Children\u27s Behavior Questionnaire. During the first wave, mothers’ and fathers’ sensitivity and intrusiveness were observed and coded with the Emotional Availability Scales. Inhibitory control exhibited partial scalar invariance over time, and increased in a decelerating rate. For both mothers and fathers, higher levels of sensitivity were associated with a higher initial level of children\u27s inhibitory control, whereas higher levels of intrusiveness predicted a slower increase in children\u27s inhibitory control

A combined first and second order variational approach for image reconstruction

In this paper we study a variational problem in the space of functions of bounded Hessian. Our model constitutes a straightforward higher-order extension of the well known ROF functional (total variation minimisation) to which we add a non-smooth second order regulariser. It combines convex functions of the total variation and the total variation of the first derivatives. In what follows, we prove existence and uniqueness of minimisers of the combined model and present the numerical solution of the corresponding discretised problem by employing the split Bregman method. The paper is furnished with applications of our model to image denoising, deblurring as well as image inpainting. The obtained numerical results are compared with results obtained from total generalised variation (TGV), infimal convolution and Euler's elastica, three other state of the art higher-order models. The numerical discussion confirms that the proposed higher-order model competes with models of its kind in avoiding the creation of undesirable artifacts and blocky-like structures in the reconstructed images -- a known disadvantage of the ROF model -- while being simple and efficiently numerically solvable.Comment: 34 pages, 89 figure

Konsekvenser for emissioner og luftkvalitet af tiltag på transportområdet i Regeringens klima- og luftudspil

Regeringens klima- og luftudspil (”Sammen om en grønnere fremtid”) indeholder en beskrivelse af 38 initiativer rettet mod at reducere udledningen af drivhusgasser og/eller luftforurening. DCE - Nationalt Center for Miljø og Energi under Aarhus Universitet har gennemgået de 38 initiativer med henblik på en vurdering af hvilke af disse initiativer, der har indflydelse på luftforureningen i 2030, samt den forventede størrelse af den reducerende effekt. DCE har kvantificeret effekten af følgende initiativer og benævnt det klimascenariet: (1) Stop for salg af nye benzin- og dieselbiler i 2030 og for nye plug-in hybridbiler fra 2035, (2) Slut med udledning af CO2 og luftforurening fra busser i byerne fra 2030, (3) Benzin og diesel skal ud af taxidriften inden 2030, (4) Gamle brændeovne skrottes ved ejerskifte, og (5) Skrotpræmie til gamle brændeovne. Artiklen fokuserer på de tre virkemidler rettet mod vejtransportsektoren og sammenligner med den eksisterende basisemissionsfremskrivning for vejtrafik i Danmark i 2030, og effektvurderer scenarierne mht. til emission og luftkvalitet.  Den største emissionsbesparelse opnås i Scenarie 1 (1 mio. elbiler), og emissions-reduktionerne for hele vejtrafikken i 2030 bliver på hhv. 13 %, 17 % og 2,1 % for NOx, PM2,5–udstødning og PM2,5–samlet (udstødning og ikke-udstødning). Hvis alle tre scenarier indføres bliver emissionsreduktionerne for NOx og PM2,5 –udstødning og PM2,5 –samlet (udstødning og ikke-udstødning) hhv. 15 %, 19 % og 2,3 %.  Effekten af klimascenariet er vurderet for luftkvaliteten på 98 gader i København i 2030 ved beregninger af ændringer i den regionale baggrund, bybaggrund og gadekoncentrationer. Basisudviklingen fra 2016 til 2030 viser et stort fald i koncentrationerne, og klimascenariet bidrager til et yderligere mindre fald. Effekten af klimascenariet for reduktion af NO2 gadekoncentrationerne er især bestemt af reduktionen i trafikkens emissioner, mens de mindre reduktioner af PM2,5 og PM10 i højere grad er bestemt af reduktioner i emissioner fra brændeovne end fra trafik.&nbsp