Transient Schr\"odinger-Poisson Simulations of a High-Frequency Resonant Tunneling Diode Oscillator

Transient simulations of a resonant tunneling diode oscillator are presented. The semiconductor model for the diode consists of a set of time-dependent Schr\"odinger equations coupled to the Poisson equation for the electric potential. The one-dimensional Schr\"odinger equations are discretized by the finite-difference Crank-Nicolson scheme using memory-type transparent boundary conditions which model the injection of electrons from the reservoirs. This scheme is unconditionally stable and reflection-free at the boundary. An efficient recursive algorithm due to Arnold, Ehrhardt, and Sofronov is used to implement the transparent boundary conditions, enabling simulations which involve a very large number of time steps. Special care has been taken to provide a discretization of the boundary data which is completely compatible with the underlying finite-difference scheme. The transient regime between two stationary states and the self-oscillatory behavior of an oscillator circuit, containing a resonant tunneling diode, is simulated for the first time

Heat risk assessment for the Brussels capital region under different urban planning and greenhouse gas emission scenarios

Urban residents are exposed to higher levels of heat stress in comparison to the rural population. As this phenomenon could be enhanced by both global greenhouse gas emissions (GHG) and urban expansion, urban planners and policymakers should integrate both in their assessment. One way to consider these two concepts is by using urban climate models at a high resolution. In this study, the influence of urban expansion and GHG emission scenarios is evaluated at 100 m spatial resolution for the city of Brussels (Belgium) in the near (2031-2050) and far (2081-2100) future. Two possible urban planning scenarios (translated into local climate zones, LCZs) in combination with two representative concentration pathways (RCPs 4.5 and 8.5) have been implemented in the urban climate model UrbClim. The projections show that the influence of GHG emissions trumps urban planning measures in each period. In the near future, no large differences are seen between the RCP scenarios; in the far future, both heat stress and risk values are twice as large for RCP 8.5 compared to RCP 4.5. Depending on the GHG scenario and the LCZ type, heat stress is projected to increase by a factor of 10 by 2090 compared to the present-day climate and urban planning conditions. The imprint of vulnerability and exposure is clearly visible in the heat risk assessment, leading to very high levels of heat risk, most notably for the North Western part of the Brussels Capital Region. The results demonstrate the need for mitigation and adaptation plans at different policy levels that strive for lower GHG emissions and the development of sustainable urban areas safeguarding livability in cities

Quality of life after liver transplantation : state of the art

Quality of life (QoL) after deceased donor liver transplantation is increasingly recognized as a major outcome parameter. We reviewed recent publications in this rapidly evolving field in order to summarize recent achievements in the field and to define opportunities and perspectives for research and improvement of patient care. QoL does improve after liver transplantation according to a typical pattern. During the first year, there is a significant improvement in QoL. After one year, the improvement does stabilise and tends to decline slightly. In addition to the physical condition, different psychological parameters (such as depression, anxiety, sexual function) and socio-demographic elements (professional state, sex, marital state) seem to impact QoL. Opportunities for further research are the use of dedicated questionnaires and identification of influencing factors for QoL

Liver transplantation for alcoholic liver disease: a retrospective analysis of recidivism, survival and risk factors predisposing to alcohol relapse

Background and study aims : Alcoholic liver disease (ALD) is the second most common indication for liver transplantation. The aim of this study was to evaluate the alcohol relapse rate and long-term survival after liver transplantation for ALD and to identify risk factors predisposing to alcohol relapse. Patients and methods : Between 2000 and 2007, 108 patients transplanted for ALD in the Ghent University Hospital were included in this retrospective analysis. Relapse was defined as any drinking after transplantation, problem drinking as more than 2 units/day for women and 3 units/day for men. A wide range of variables was obtained from a questionnaire and medical records. Results : The mean follow-up was 55 months. Relapse was observed in 29%, 16% in problem drinking. The one-and five-year survival was 87% and 74% respectively. No significant difference in survival was found between non-relapsers, occasional drinkers and problem drinkers. The following risk factors were found to be significantly associated with relapse into problem drinking in an univariate analysis : a shorter pre-transplant abstinence period, the presence of a first degree relative with alcohol abuse and a higher number of prior attempts to quit. In multivariable analysis, the presence of a first degree relative with alcohol abuse was found associated with relapse into problem drinking. Conclusions : The presence of a first degree relative with alcohol abuse is a valuable pre-transplant variable evaluating an ALD patient's eligibility for liver transplantation. Other variables are also helpful to outline the broader context of the drinking behavior of the patient

The Association Between Objectively Measured Physical Activity and Academic Achievement in Dutch Adolescents: Findings From the GOALS Study

The main goal of this study was to investigate the association between objectively measured physical activity and academic achievement in adolescents

Scheitern der Reform des Emissionshandels: Verliert Europa die Vorreiterrolle in der Klimapolitik?

Im April lehnte das Europäische Parlament den Vorschlag der EU-Kommission ab, vorübergehend CO2-Emissionszertifikate vom Markt zu nehmen, um so den Preisverfall für Emissionsrechte zu stoppen und Anreize für die Industrie, in klimafreundliche Technologien zu investieren, zu setzen. Steht die Reform des europäischen Emissionshandels endgültig vor dem Scheitern? Nach Ansicht von Hans-Jürgen Nantke, Umweltbundesamt, ist der Emissionshandel ein sehr effizientes Klimaschutzinstrument. Wie effizient, hänge allerdings vom politischen Willen für ambitionierte Ziele zur Kohlendioxidminderung ab, und daran hapere es derzeit in der EU. In den bisherigen beiden Handelsperioden seien die emissionshandelspflichtigen Unternehmen zu großzügig mit weitestgehend kostenlosen Emissionsberechtigungen ausgestattet worden, so dass von diesem Preissignal kein spürbarer Anreiz für Investitionen in zusätzliche Klimaschutzmaßnahmen ausgehen konnte. Alfred Endres und Frederik Schaff, FernUniversität Hagen, sehen es aus umweltökonomischer Sicht als sinnvoll an, den durch Vergabe von Emissionszertifikaten gesteckten Rahmen der Klima belastenden Emissionen zu verengen. Durch das Backloading wäre aber nur eine Verschiebung des Problems zu erwarten. Die Chancen wären besser, wenn man sich entschlossen hätte, die Emissionsrechte unwiderruflich aus dem Markt zu nehmen. Aber dafür fehle den verantwortlichen Politiker(inne)n die Willenskraft. Auch für Till Requate, Universität Kiel, bedeutet das Backloading nur einen kurzatmigen ordnungspolitischen Eingriff, der das Problem des reformbedürftigen unkoordinierten Nebeneinanders europäischer, nationaler und regionaler Energiepolitik nicht löst. Dem Klimaziel helfen würde nur eine langfristige Verringerung der Menge an Emissionszertifikaten. Es wäre vernünftig, das EU ETS mit anderen Emissionshandelssystemen zu verknüpfen. Susanne Dröge, Stiftung Wissenschaft und Politik, Berlin, sieht die EU in der Reform-Falle und befürchtet, dass der europäische Emissi

Portal vein thrombosis in patients on the waiting list for liver transplantation : a single center cohort study

C

Active commuting to school, cognitive performance, and academic achievement: an observational study in Dutch adolescents using accelerometers

Background: The current study examined the associations between active commuting to school, cognitive performance, and academic achievement in Dutch adolescents. In addition, it was explored whether these associations were moderated by sex and mediated by depressive symptoms. Methods: Students in grades 7 and 9 (N = 270; mean age 13.4 years; 53% boys) were included. Active commuting to school was measured objectively by an ActivPAL3™ accelerometer. Cognitive performance was measured by the d2 Test of attention (key components of executive functioning) and the Symbol Digit Modalities Test (information-processing speed). Academic achievement was determined by the mean of the school grades obtained in Dutch, mathematics and English. Depressive symptoms were self-reported. Results: Active commuting to school constituted 28% of the total amount of time spent moving per week. Active commuting to school was not significantly associated with cognitive performance and academic achievement, overall. However, active commuting to school was positively associated with performance on the d2 Test of attention in girls (β = .17, p = .037), but not in boys (β = −.03, p =.660). The associations were not mediated by depressive symptoms. Conclusions: The associations between active commuting to school and cognitive performance and academic achievement are weak and might be moderated by sex, while the greatest benefits on cognition due to active commuting to school might be with regard to executive functioning. Future studies might make use of experimental designs, because causal relations between active commuting to school and cognitive performance or academic achievement would provide important implications for both education and public health.This research was supported by the NIHC (Nationaal Initiatief Hersenen & Cognitie [National Initiative Brain & Cognition]) funded by FES (Fonds Economische Structuurversterking [Fund Economic Structure Reinforcement])

Taxation of real estate: Russian reforms and foreign practice

In this report, a comparative analysis of Russian reforms in the field of real estate taxation is conducted and foreign practice investigated