Matej Bel University

About: Matej Bel University is a education organization based out in Banská Bystrica, Slovakia. It is known for research contribution in the topics: Tourism & Fuzzy set. The organization has 721 authors who have published 1497 publications receiving 11573 citations. The organization is also known as: Matej Bel & Univerzita Mateja Bela.

On the existence of tori in Asada’s two-regional model

Abstract: A two-regional five-dimensional model describing the development of income, capital stock and money stock, which was introduced by Asada in (2004) [2] is analysed. Sufficient conditions for the existence of two pairs of purely imaginary eigenvalues and the last one being negative in the linear approximation matrix of the model are found. Formulae for the calculation of the coefficients in the bifurcation equation of the model are derived. The theorem on the existence of invariant tori is presented. A numerical example illustrating the gained results is given.

Particle-size distribution of dust created during sanding the modified ash wood

Abstract: Particle-size distribution of dust created during sanding the modified ash wood. The paper presents the results of the particle size distribution of dust from sanding thermally modified wood ash at three temperature levels and comparatively unmodified wood. It has been found and described the effect of temperature in the process of modification of wood on the content of particles belonging to the smallest fraction of dust dreated during sanding.

Double machine learning for sample selection models

Abstract: This paper considers the evaluation of discretely distributed treatments when outcomes are only observed for a subpopulation due to sample selection or outcome attrition. For identification, we combine a selection-on-observables assumption for treatment assignment with either selection-on-observables or instrumental variable assumptions concerning the outcome attrition/sample selection process. We also consider dynamic confounding, meaning that covariates that jointly affect sample selection and the outcome may (at least partly) be influenced by the treatment. To control in a data-driven way for a potentially high dimensional set of pre- and/or post-treatment covariates, we adapt the double machine learning framework for treatment evaluation to sample selection problems. We make use of (a) Neyman-orthogonal, doubly robust, and efficient score functions, which imply the robustness of treatment effect estimation to moderate regularization biases in the machine learning-based estimation of the outcome, treatment, or sample selection models and (b) sample splitting (or cross-fitting) to prevent overfitting bias. We demonstrate that the proposed estimators are asymptotically normal and root-n consistent under specific regularity conditions concerning the machine learners and investigate their finite sample properties in a simulation study. We also apply our proposed methodology to the Job Corps data for evaluating the effect of training on hourly wages which are only observed conditional on employment. The estimator is available in the causalweight package for the statistical software R.

Design of High-Performance Pyridine/Quinoline Hydrazone Photoswitches.

Abstract: The design of P-type photoswitches with thermal stability of the metastable form of hundreds of years that would efficiently transform using excitation wavelengths above 350 nm remains a challenge in the field of photochromism. In this regard, we designed and synthesized an extended set of 13 pyridine/quinoline hydrazones and systematically investigated the structure-property relationships, defining their kinetic and photoswitching parameters. We show that the operational wavelengths of the pyridine hydrazone structural motif can be effectively shifted toward the visible region without simultaneous loss of their high thermal stability. Furthermore, we characterized the ground-state and excited-state potential energy surfaces with quantum-chemical calculations and ultrafast transient absorption spectroscopy, which allowed us to rationalize both the thermal and photochemical reaction mechanisms of the designed hydrazones. Whereas introducing an electron-withdrawing pyridyl moiety in benzoylpyridine hydrazones leads to thermal stabilities exceeding 200 years, extended π-conjugation in naphthoylquinoline hydrazones pushes the absorption maxima toward the visible spectral region. In either case, the compounds retain highly efficient photoswitching characteristics. Our findings open a route to the rational design of a new family of hydrazone-based P-type photoswitches with high application potential in photonics or photopharmacology.

Identification of prospective industrial clusters in Slovakia

Abstract: Abstract Clusters became an integral part of regional policies intended to build and strengthen competitive advantages within specifically identified geographical areas. They are still considered crucial for economic development and employment, although their orientation has slightly changed as the distance and geographical boundaries lost their importance. This article analyses crucial regional data that indicates potentially beneficial economic concentrations as an assumption for the preparation of prospective clusters in Slovakia. Potential clusters were identified based on significant employment concentrations of particular regional industries that appear extraordinary when compared with national employment and the dynamic development within the selected time frame. Prospective clusters were identified, and opportunities of their development were described, including the harmonisation with the current regional and urban strategy. Analysing absolute and relative quantities in employment, sections and divisions of SK NACE were used for the proper identification of industries. The location quotient served as a tool for the spatial concentration of employment in the Banská Bystrica region, the threshold value for the selection of cluster candidates was set to 2. The shift–share analysis was used for the identification of long-term changes in employment, and 10% of the most dynamic industries were presented at the level of divisions once and then, at the level of sections of SK NACE. Forestry and logging, the manufacture of wood products and the manufacture of basic metals were confirmed by both methods as significant concentrations. The result partially corresponded with the previously active and currently inactive cluster in Banská Bystrica, which was focused on mechanical engineering, still significant when considering numbers of companies and employees as well as sales. Forestry was the most concentrated industry, while the wholesale and retail trades were the most dynamic. Forestry, logging and manufacture of wood products might be strongly interlinked with the current entrepreneurial and social strategy of self-governing regions that is still at the stage of potential cluster identification and fitting to its priorities. The article assumed basic quantitative methods utilised for the identification of prospective clusters. It confirmed the practicality of their application, the gravity of data processing and also certain possible limitations due to the extraordinary focus on the employment concentration. According to the analysis and gained results, the former cluster in the Banská Bystrica region was confirmed as the potentially significant actor in the regional policy (although, currently, having no industrial or public interest) and the new cluster candidates were identified. Outcomes indicated the need to continue the research with a more detailed examination of qualitative aspects that could complete the effort by focusing on clusters not only having higher employment statistics but also the support from regional institutions, also reflecting the preferences of businesses.