Speeding up the solution of the Bethe-Salpeter equation by a double-grid method and Wannier interpolation

The Bethe-Salpeter equation is a widely used approach to describe optical excitations in bulk semiconductors. It leads to spectra that are in very good agreement with experiment, but the price to pay for such accuracy is a very high computational burden. One of the main bottlenecks is the large number of k-points required to obtain converged spectra. In order to circumvent this problem we propose a strategy to solve the Bethe-Salpeter equation based on a double-grid technique coupled to a Wannier interpolation of the Kohn-Sham band structure. This strategy is then benchmarked for a particularly difficult case, the calculation of the absorption spectrum of GaAs, and for the well studied case of Si. The considerable gains observed in these cases fully validate our approach, and open the way for the application of the Bethe-Salpeter equation to large and complex systems.Comment: 5 pages, 3 figures. Accepted for Phys. Rev.

Team-Based Learning Impact on College Students Anxiety

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Knowledge Management and Business IntelligenceOver the years, the anxiety issue gained more prominence affecting multiple age groups. Young people, such as college students are no exception. They are faced many situations that affect their well-being causing them anxiety and putting at risk their academic performance. Those circumstances lead students to disengagement attitudes toward school and consequently poor evaluation performances. Having those issues in mind, several institutions are trying to adapt their way of teaching through the transition from traditional ways, where student’s knowledge is only supplied by lecturers, to student-centered approaches, namely, active learning where students can participate in their own learning process being that process a collaboration between the teacher and the learner. So far, active learning has proved that in some situations can be useful in anxiety reduction. Therefore, aiming to understand and explore in a broader way what is the impact of active learning practices, namely, team-based learning on NOVA IMS university students’ anxiety, from several study areas, this study focuses its research on the implementation of that approach during one semester. Intending to accomplish those objectives, qualitative and quantitative analyses were carried out through the use of surveys and individual interviews, allowing the further implementation of exploratory, statistical, and cluster analysis supported by Jupyter Notebook, SPSS Statistics, and Excel. Those analyses allowed not only the discovery of the student's opinions on the practice applied as well as the respective relationship between active learning and anxiety levels felt in those situations and the specific semester period being complemented by students’ demographic and non-demographic characteristics

The contribution of physical exercise to organisational performance

Maintaining high levels of employee’s performance at work is a major concern among managers. Employees’ characteristics and individual performance contribute to the competitiveness of organisations. The current work environment is highly sedentary, which influences employees’ performance. This quantitative study investigates the moderating effect of physical exercise on the relationships between job satisfaction, motivation, and organisational performance. Data was collected using an online questionnaire and it was analysed using structural equation modelling and moderation analysis. The results show the existing relationships between job satisfaction, intrinsic motivation and performance regarding both dimensions of organisational performance: creativity and dealing with emergencies. Such relationships are moderated by the level of exercise performed by the employees.info:eu-repo/semantics/publishedVersio

EXIGÊNCIAS DOS CONSUMIDORES EUROPEUS EM RELAÇÃO À MAÇÃ GAÚCHA, NA VISÃO DOS EXPORTADORES

Considering the European consumers’ concern regarding food quality and safety, three study cases were developed with companies aiming to know what the requirements about apple production are. The results showed that two companies are only producers, meaning they do not hold any contractual relation between a company and themselves, which characterizes the management structure as “own productionâ€. As for the third company, producers sell their fruit to the company after establishing a partnership (hybrid governance structure). The challenges for these companies are the increasing level of requirements concerning the apple quality, the relation between prices and costs and the food safety and traceability in the chain.food safety, certification, traceability, fruit chain.,

Personalizing medicine for metastatic colorectal cancer: Current developments

Metastatic colorectal cancer (mCRC) is still one of the tumor types with the highest incidence and mortality. In 2012, colorectal cancer was the second most prevalence cancer among males (9%) and the third among females (8%). In this disease, early diagnosis is important to improve treatment outcomes. However, at the time of diagnosis, about one quarter of patients already have metastases, and overall survival of these patients at 5-years survival is very low. Because of these poor statistics, the development of new drugs against specific targets, including the pathway of angiogenesis, has witnessed a remarkable increase. So, targets therapies through epidermal growth factor and its receptor and also KRAS pathways modulation acquired a main role whether in association with standard chemotherapy and radiotherapy. With the current knowledge in the field of molecular biology, including genetic mutations and polymorphisms, we know better why patients respond so differently to the same treatments. So, in the future we can develop increasingly personalized treatments to the patient and not the disease. This review aims to summarize some molecular pathways and their relation to tumor growth, as well as novel targeted developing drugs and recently approved for mCRC. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.info:eu-repo/semantics/publishedVersio

Job creation and destruction in the digital age: Assessing heterogeneous effects across European Union countries

Do investments in Information and Communication Technology (ICT) create jobs? The literature suggests that, even if innovations are labour saving, there may be compensating mechanisms that lead to a positive employment effect. We investigate this issue using country-level data for the European Union from 1995 to 2019. The results suggest an average positive net effect of ICT investment on total employment. An increase of €100,000 in the ICT investment stock is associated with an average increase of 3.3 jobs in the European Union. However, the magnitude of the impact is heterogeneous across countries. The differences are explained by the country-specific characteristics of ICT investment (non-machine versus machine-based) and the existing skill endowment of the labour force. Moreover, the rate of return on investment expressed in terms of net job creation tends to decline over time, as the share of high-skilled workers in the market increase

The effects of official and unofficial information on tax compliance

The administration of tax policy has shifted its focus from enforcement to complementary instruments aimed at creating a social norm of tax compliance. In this paper we provide an analysis of the effects of the dissemination of information regarding the past degree of tax evasion at the social level on the current individual tax compliance behavior. We build an experiment where, for given levels of audit probabilities, fines and tax rates, subjects have to declare their income after receiving either a communication of the offcial average tax evasion rate or a private message from a group of randomly matched peers about their tax behavior. We use the experimental data to estimate a dynamic econometric model of tax evasion. The econometric model extends the Allingham-Sandmo-Yitzhaki tax evasion model to include self-consistency and endogenous social interactions among taxpayers. We find four main results. First, tax compliance is very persistent. Second, the higher the offcial past tax evasion rate the higher the degree of persistence: evaders are more likely to evade again, and compliant individuals are more likely to comply again. Third, when all peers communicate to have evaded (complied) in the past, both evaders and compliant individuals are more likely to evade (comply). Fourth, while both treatments, and especially the unoffcial information treatment, are associated, in the context of our experiment, with a signicantly larger growth in evasion intensity, the aggregate effect depends on the characteristics of the population. In countries with inherently low levels of tax evasion, offcial information can have beneficial effects by consolidating the behavior of compliant individuals. However, in countries with inherently high levels of tax evasion, offcial information can have detrimental effects by intensifying the behavior of evaders. In both cases, the impact of offcial information is magnified in the presence of strong peer effects.info:eu-repo/semantics/publishedVersio