Charged Particles Circular Orbits around Weakly Charged and Magnetized Kerr Black Holes

We study the circular orbits of charged particles around a weakly charged Kerr black hole immersed in a weak, axisymmetric magnetic field. Firstly, we review the circular orbits of neutral particles. We then review the circular orbits of charged particles around a weakly charged Kerr black hole and weakly magnetized Kerr black hole. The case of a weakly magnetized and charged black hole is investigated thereafter. We investigate, in particular, the effect of the electromagnetic forces on the charged particles' innermost stable circular orbits. We examine the conditions for the existence of negative-energy stable circular orbits and the possibility of the emergence of a gap or double orbit in thin accretion disks. Some of the interesting astrophysical consequences of our findings are discussed as well.Comment: Accepted for publication in the Astrophysical Journal. arXiv admin note: substantial text overlap with arXiv:2208.1395

Particle Dynamics in Weakly Charged Extreme Kerr Throat

We study dynamics of a test charged particle moving in a weakly charged extreme Kerr throat. Dynamical equations of the particle motion are solved in quadratures. We show explicitly that the Killing tensor of the Kerr spacetime becomes reducible in the extreme Kerr throat geometry. Special types of motion of particles and light are discussed.Comment: The paper is prepared for the fest volume devoted to 75th Birthday of Mario Castagnin

Genetic local search for multicast routing with pre-processing by logarithmic simulated annealing

Over the past few years, several local search algorithms have been proposed for various problems related to multicast routing in the off-line mode. We describe a population-based search algorithm for cost minimisation of multicast routing. The algorithm utilises the partially mixed crossover operation (PMX) under the elitist model: for each element of the current population, the local search is based upon the results of a landscape analysis that is executed only once in a pre-processing step; the best solution found so far is always part of the population. The aim of the landscape analysis is to estimate the depth of the deepest local minima in the landscape generated by the routing tasks and the objective function. The analysis employs simulated annealing with a logarithmic cooling schedule (logarithmic simulated annealing—LSA). The local search then performs alternating sequences of descending and ascending steps for each individual of the population, where the length of a sequence with uniform direction is controlled by the estimated value of the maximum depth of local minima. We present results from computational experiments on three different routing tasks, and we provide experimental evidence that our genetic local search procedure that combines LSA and PMX performs better than algorithms using either LSA or PMX only

Faculty Members Practice of 21st Century Skills in Teaching: A Perspective from Bisha University

This study aims to identify the teaching practices of faculty staff members at the University of Bisha in light of twenty-first century skills. The descriptive method is used as it suits the research aims. The faculty staff members demonstrate a high level of teaching practices in light of twenty-first century skills, with life and occupation skills ranking first, learning and creativity skills ranking second, and digital culture skills ranking third. The results show statistically significant dissimilarities in learning and creativity skills and life and occupation skills between the teaching practices of faculty staff members in favor of the Faculty of Engineering, while the difference in digital culture skills favors the Faculty of Education. Additionally, there is a statistically significant difference in the teaching practices of faculty staff members in the light of twenty-first century skills attributable to the variable of teaching experience, favoring the category of (5-10 years)

Factors affecting mental fitness for work in a sample of mentally ill patients

<p>Abstract</p> <p>Background</p> <p>Mental fitness for work is the ability of workers to perform their work without risks for themselves or others. Mental fitness was a neglected area of practice and research. Mental ill health at work seems to be rising as a cause of disablement. Psychiatrists who may have had no experience in relating mental health to working conditions are increasingly being asked to undertake these examinations. This research was done to explore the relationship of mental ill health and fitness to work and to recognize the differences between fit and unfit mentally ill patients.</p> <p>Methods</p> <p>This study was cross sectional one. All cases referred to Al-Amal complex for assessment of mental fitness during a period of 12 months were included. Data collected included demographic and clinical characteristics, characteristics of the work environment and data about performance at work. All data was subjected to statistical analysis.</p> <p>Results</p> <p>Total number of cases was 116, the mean age was 34.5 ± 1.4. Females were 35.3% of cases. The highly educated patients constitute 50.8% of cases. The decision of the committee was fit for regular work for 52.5%, unfit for 19.8% and modified work for 27.7%. The decision was appreciated only by 29.3% of cases. There were significant differences between fit, unfit and modified work groups. The fit group had higher level of education, less duration of illness, and better performance at work. Patients of the modified work group had more physical hazards in work environment and had more work shift and more frequent diagnosis of substance abuse. The unfit group had more duration of illness, more frequent hospitalizations, less productivity, and more diagnosis of schizophrenia.</p> <p>Conclusion</p> <p>There are many factors affecting the mental fitness the most important are the characteristics of work environment and the most serious is the overall safety of patient to self and others. A lot of ethical and legal issues should be kept in mind during such assessment as patient's rights, society's rights, and the laws applied to unfit people.</p