University of Maribor

About: University of Maribor is a education organization based out in Maribor, Slovenia. It is known for research contribution in the topics: Population & KEKB. The organization has 3987 authors who have published 13077 publications receiving 258339 citations. The organization is also known as: Univerza v Mariboru.

Reasons for Plagiarism in Higher Education

Abstract: Background and Purpose: The survey was performed to determine the reasons that lead students to possibly com­mit plagiarism during their studies. By doing so, we wanted to determine the main reason for the appearance of pla­giarism and how, within this main reasons, various indicators of plagiarism are judged and, finally, how demographic data and student motivation for study are associated with the reasons for plagiarism. Design/Methodology/Approach: A paper-and-pencil survey was carried out among 17 faculties of the University of Maribor in Slovenia. A sample of 139 students 85 males and 54 females participated in this study, ages ranged from 19 to 36 years. The questionnaire contained 95 closed questions referring to: (i) general data, (ii) education, (iii) social status, (iv) awareness of plagiarism, and (v) reasons for plagiarism. Parametric and nonparametric statistical tests were performed depending on distributions of the answers. Results: The results reveal that information and communication technology is largely responsible for the plagiarism with two reasons highlighted: ease of copying and ease of access to materials and new technologies. We also found some differences between low and high motivated students. Different average values of the answers considering motivation for study were confirmed for academic skills, teaching factors and other reasons for plagiarism, where the average for lower motivated students is significantly different (higher) than the average for higher motivated students. At the end we could find no direct relationship between the average time spent on the Internet and plagiarism. Conclusion: The transmission of knowledge is the basic mission of faculties. This mission is based on moral beliefs about the harmfulness of its abuse, and plagiarism is exactly such abuse. Regardless of the students past at this point professors are those who could greatly contribute to the right set of skills to keep students off plagiarising.

Photon Spheres and Sonic Horizons in Black Holes from Supergravity and Other Theories

Abstract: We study closed photon orbits in spherically symmetric static solutions of supergravity theories, a Horndeski theory, and a theory of quintessence. These orbits lie in what we shall call a photon sphere (antiphoton sphere) if the orbit is unstable (stable). We show that in all the asymptotically flat solutions we examine that admit a regular event horizon, and whose energy-momentum tensor satisfies the strong energy condition, there is one and only one photon sphere outside the event horizon. We give an example of a Horndeski theory black hole (whose energy-momentum tensor violates the strong energy condition) whose metric admits both a photon sphere and an antiphoton sphere. The uniqueness and nonexistence also holds for asymptotically anti--de Sitter solutions in gauged supergravity. The latter also exhibits the projective symmetry that was first discovered for the Schwarzschild--de Sitter metrics: the unparametrized null geodesics are the same as when the cosmological or gauge coupling constant vanishes. We also study the closely related problem of accretion flows by perfect fluids in these metrics. For a radiation fluid, Bondi's sonic horizon coincides with the photon sphere. For a general polytropic equation of state this is not the case. Finally we exhibit counterexamples to a conjecture of Hod's.

The influence of time delay in a chaotic cancer model.

Abstract: The tumor-immune interactive dynamics is an evergreen subject that continues to draw attention from applied mathematicians and oncologists, especially so due to the unpredictable growth of tumor cells. In this respect, mathematical modeling promises insights that might help us to better understand this harmful aspect of our biology. With this goal, we here present and study a mathematical model that describes how tumor cells evolve and survive the brief encounter with the immune system, mediated by effector cells and host cells. We focus on the distribution of eigenvalues of the resulting ordinary differential equations, the local stability of the biologically feasible singular points, and the existence of Hopf bifurcations, whereby the time lag is used as the bifurcation parameter. We estimate analytically the length of the time delay to preserve the stability of the period-1 limit cycle, which arises at the Hopf bifurcation point. We also perform numerical simulations, which reveal the rich dynamics of the studied system. We show that the delayed model exhibits periodic oscillations as well as chaotic behavior, which are often indicators of long-term tumor relapse.

Differential Evolution with Self-adaptation and Local Search for Constrained Multiobjective Optimization

Abstract: This paper presents Differential Evolution with Self-adaptation and Local Search for Constrained Multiobjective Optimization algorithm (DECMOSA-SQP), which uses the self-adaptation mechanism from DEMOwSA algorithm presented at CEC 2007 and a SQP local search. The constrained handling mechanism is also incorporated in the new algorithm. Assessment of the algorithm using CEC 2009 special session and competition on constrained multiobjective optimization test functions is presented. The functions are composed of unconstrained and constrained problems. Their results are assessed using the IGD metric. Based on this metric, algorithm strengths and weaknesses are discussed.