Physics Institute

The topological band structures of InAs x Sb 1Àx (x = 0, 0.25, 0.5, 0.75, 1) alloys have been investigated using density functional theory by utilizing the Wien2k package. These alloys are in a topologically trivial phase in their unstrained states and exhibit a small band gap. Since in small band-gap cubic semiconductors the nontrivial topological phase can be achieved by lattice expansion, we investigate the effect of hydrostatic and biaxial lattice expansion on band inversion strength and band order of these alloys. It is found that under reasonable hydrostatic lattice expansion, InAs x Sb 1Àx (x = 0, 0.25, 0.75, 1) alloys with cubic symmetry and InAs 0.5 Sb 0.5 alloy with tetragonal symmetry, are converted to nontrivial topological semiconductors with zero band gap and non-zero band gap, respectively. In order to convert InAs x Sb 1Àx (x = 0, 0.25, 0.75, 1) alloys into topological semiconductors with non-zero band gap, we let the systems of InAs x Sb 1Àx (x = 0, 0.25, 0.75, 1) alloys undergo a biaxial lattice expansion. Thus by breaking the cubic symmetry in these alloys, not only they are converted to topologically nontrivial phase but also a small band gap is opened at C point.

The structural, electronic, and optical properties of InAs, InSb, and their ternary alloys InAs x Sb 1−x (x = 0.25, 0.5, 0.75) are investigated within density functional theory utilizing the WIEN2K package. We find that the lattice constants and bulk moduli as a function of x are in best agreement with Vegard's linear rule. When computing the electronic band structures with the modified Becke-Johnson exchange-correlation functional (mBJLDA), our results for the band gaps of InAs, InSb, and their ternary alloys are in good agreement with the available experimental results while the conventional Wu-Cohen generalized gradient approximation (GGA) functional leads to zero or close to zero band gaps. In particular, our mBJLDA results confirm experimental evidence that the minimum band gap occurs for As concentrations around x ≈ 0.3. Furthermore, we investigate the dielectric function of these compounds within the random phase approximation using both the Wu-Cohen GGA and the mBJLDA functionals. While the mBJLDA results of our fully first-principles calculations show good agreement of the peak positions in 2 (ω) with experiments, the peaks in the optical spectra based on the Wu-Cohen GGA band structure appear redshifted compared to experiment. We further identify the interband transitions responsible for the structures in the spectra. Looking at the optical matrix element, we note that the major peaks are dominated by transition from the Sb 5p (As 4p) states to In s states for InSb and InAs 0.25 Sb 0.75 (InAs, InAs 0.75 Sb 0.25 , and InAs 0.5 Sb 0.5).

The intense traffic on existing pavements not only induces increased deterioration but also decreases availability of pavements for monitoring and maintenance interventions. In Europe, in general, the existing pavement network requires maintenance in order to comply with traffic requirements. In an economic scenario of financial requirements, it is crucial to plan and justify maintenance measures needed for an efficient management. This paper presents future trends in pavement engineering focussing specifically on the non-destructive continuous monitoring, data processing, and possible applications of Building Information Modelling, as improved tools for pavement monitoring and rehabilitation management.

Glaciers are of key importance to freshwater supplies in the Himalayan region. Their growth or decline is among other factors determined by an interaction of 2-m air temperature (TAS) and precipitation rate (PR) and thereof derived positive degree days (PDD) and snow and ice accumulation (SAC). To investigate determining factors in climate projections, we use a model ensemble consisting of 36 CMIP5 general circulation models (GCMs) and 13 regional climate models (RCMs) of two Asian CORDEX domains for two different representative concentration pathways (RCP4.5 and RCP8.5). First, we downsize the ensemble in respect to the models' ability to correctly reproduce dominant circulation patterns (i.e., the Indian summer monsoon [ISM] and western disturbances [WDs]) as well as elevation-dependent trend signals in winter. Within this evaluation, a newly produced data set for the Indus, Ganges and Brahmaputra catchments is used as observational data. The reanalyses WFDEI, ERA-Interim, NCEP/NCAR and JRA-55 are used to further account for observational uncertainty. In a next step, remaining TAS and PR data are bias corrected applying a new bias adjustment method, scale distribution mapping, and subsequently PDD and SAC computed. Finally, we identify and quantify projected climate change effects. Until the end of the century, the ensemble indicates a rise of PDD, especially during summer and for lower altitudes. Also TAS is rising, though the highest increases are shown for higher altitudes and between December and April (DJFMA). PRs connected to the ISM are projected to robustly increase, while signals for PR changes during DJFMA show a higher level of uncertainty and spatial heterogeneity. However, a robust decline in solid precipitation is projected over our research domain, with the exception of a small area in the high mountain Indus catchment where no clear signal emerges. 1 | INTRODUCTION The Himalayan region, sometimes referred to as the water tower of Asia or High Mountain Asia (HMA), is home to the highest mountains on our planet. Located between 28 and 38 N latitude runoff from the Hindu Kush, Karakoram and southern Himalaya (HKKH) feed three major rivers, the Indus, Ganga and Brahmaputra, whose catchments are in the focus of this study. The water generated in the HKKH has varying importance for the downstream areas. In comparison

Glaciers are of key importance to the freshwater supply in the Himalayan region. Their growth or melting is influenced by an interaction of temperature near the surface (tas) and precipitation rate (pr). In a changing climate characterized by rising temperatures mountain glaciers are ought to decline. However, recent observations indicate a glacier growth over the Karakoram (western Himalaya) due to a rise in snow accumulation while positive degree days show no change.

The main goal of our study is to improve the efficiency of crop hail damage assessment practices. The preliminary study focuses on the combined analysis of hail signature information from radar and ground measurements for crop hail damage assessment. The days with the high crop hail damage claims were selected for the investigation. Total 16 hail days were assigned to examine the relation between radar-derived products and damages produced by hail in Styria, Austria during 2015. 3D single polarization C-band weather radar data and radiosonde freezing level data were used to derive hail kinetic energy flux as well as flux integrated over the whole event. The spatial distribution maps of total hail kinetic energy were developed to capture the swath and intensity of the hail storms to identify potential hail damage areas. Hail events from ESWD (European Severe Weather Database), crop damage reports from the Austrian Hail Insurance System were allotted for validation. The hail signature...

In this communication, we evaluate the role of maintenance costs of hydraulic infrastructures in the risk analysis of torrential channels under the impact of process and/or climate changes. We combine stochastic life-cycle analysis (LCA), debris-flow modelling and risk assessments to understand the cumulative effects of extreme debris-flow events and potential progressive degradation of infrastructure on mitigation structures. We compare two scenarios to assess the reliability of check dams in reducing debris flow risks, with a focus on their performance and maintainability. We detect that maintenance works will play an important role in the next decades to maintain the reliability of infrastructure at a high level of confidence, which will however result in high economic costs.

Glaciers are of key importance to the freshwater supply in the Himalayan region. Their growth or melting is influenced by an interaction of temperature near the surface (TAS) and precipitation rate (PR). In a changing climate characterized by rising temperatures mountain glaciers are ought to decline. However, recent observations indicate a glacier growth over the Karakoram (western Himalaya) due to a rise in snow accumulation while positive degree days show no change.

Two key factors can affect the functional ability of protection structures in mountains torrents, namely (i) infrastructure maintenance of existing infrastructures (as a majority of existing works is in the second half of their life cycle), and (ii) changes in debris-flow activity as a result of ongoing and expected future climatic changes. Here, we explore the applicability of a stochastic life-cycle performance to assess debris-flow risk in the heavily managed Wartschenbach torrent (Lienz region, Austria) and to quantify associated, expected economic losses. We do so by considering maintenance costs to restore infrastructure in the aftermath of debrisflow events as well as by assessing the probability of check dam failure (e.g., as a result of overload). Our analysis comprises two different management strategies as well as three scenarios defining future changes in debris-flow activity resulting from climatic changes. At the study site, an average debris-flow frequency of 21 events per decade was observed for the period 1950-2000; activity at the site is projected to change by + 38% to − 33%,

The potential of quantile mapping (QM) as a tool for bias correction of precipitation extremes simulated by regional climate models (RCMs) is investigated in this study. We developed an extended version of QM to improve the quality of bias-corrected extreme precipitation events. The extended version aims to exploit the advantages of both non-parametric methods and extreme value theory. We evaluated QM by applying it to a small ensemble of hindcast simulations, performed with RCMs at six different locations in Europe. We examined the quality of both raw and bias-corrected simulations of precipitation extremes using the split sample and cross-validation approaches. The split-sample approach mimics the application to future climate scenarios, while the cross-validation framework is designed to analyse “new extremes”, that is, events beyond the range of calibration of QM. We demonstrate that QM generally improves the simulation of precipitation extremes, compared to raw RCM results, but...

The mass spectrum of heavy pseudoscalar mesons, described as quark-antiquark bound systems, is considered within the Bethe-Salpeter formalism with momentumdependent masses of the constituents. This dependence is found by solving the Schwinger-Dyson equation for quark propagators in rainbow-ladder approximation. Such an approximation is known to provide both a fast convergence of numerical methods and accurate results for lightest mesons. However, as the meson mass increases, the method becomes less stable and special attention must be devoted to details of numerical means of solving the corresponding equations. We focus on the pseudoscalar sector and show that our numerical scheme describes fairly accurately the π, K, D, D s and η c ground states. Excited states are considered as well. Our calculations are directly related to the future physics programme at FAIR.

In view of the mass spectrum of heavy mesons in vacuum the analytical properties of the solutions of the truncated Dyson-Schwinger equation for the quark propagator within the rainbow approximation are analysed in some detail. In Euclidean space, the quark propagator is not an analytical function possessing, in general, an infinite number of singularities (poles) which hamper to solve the Bethe-Salpeter equation. However, for light mesons (with masses M qq ≤ 1 GeV) all singularities are located outside the region within which the Bethe-Salpeter equation is defined. With an increase of the considered meson masses this region enlarges and already at masses ≥ 1 GeV, the poles of propagators of u, d and s quarks fall within the integration domain of the Bethe-Salpeter equation. Nevertheless, it is established that for meson masses up to M qq ≃ 3 GeV only the first, mutually complex conjugated, poles contribute to the solution. We argue that, by knowing the position of the poles and their residues, a reliable parametrisation of the quark propagators can be found and used in numerical procedures of solving the Bethe-Salpeter equation. Our analysis is directly related to the future physics programme at FAIR with respect to open charm degrees of freedom.

The mass spectrum of heavy pseudoscalar mesons, described as quark-antiquark bound systems, is considered within the Bethe-Salpeter formalism with momentum dependent masses of the constituents. This dependence is found by solving the Schwinger-Dyson equation for quark propagators in rainbow-ladder approximation. Such an approximation is known to provide both a fast convergence of numerical methods and accurate results for lightest mesons. However, as the meson mass increases, the method becomes less stable and special attention must be devoted to details of numerical means of solving the corresponding equations. We focus on the pseudoscalar sector and show that our numerical scheme describes fairly accurately the $\pi$, $K$, $D$, $D_s$ and $\eta_c$ ground states. Excited states are considered as well. Our calculations are directly related to the future physics programme at FAIR. Comment: 8 pages, 1 figure. Talk presented at the XX International Baldin Seminar "Relativistic Nuce...

The operator product expansion (OPE) for heavy-light-quark pseudoscalar mesons (Dmesons and B-mesons) in medium is determined, both for a moving meson with respect to the surrounding medium as well as for a meson at rest. First of all, the OPE is given in terms of normal-ordered operators up to mass dimension 5, and the mass of the heavyquark and the mass of the light-quark are kept finite. The Wilson coefficients of such an expansion are infrared (IR) divergent in the limit of a vanishing light-quark mass.