Synchronization in the presence of memory

We study the effect of memory on synchronization of identical chaotic systems driven by common external noises. Our examples show that while in general synchronization transition becomes more difficult to meet when memory range increases, for intermediate ranges the synchronization tendency of systems can be enhanced. Generally the synchronization transition is found to depend on the memory range and the ratio of noise strength to memory amplitude, which indicates on a possibility of optimizing synchronization by memory. We also point out on a close link between dynamics with memory and noise, and recently discovered synchronizing properties of networks with delayed interactions

Exploiting Resolution-based Representations for MaxSAT Solving

Most recent MaxSAT algorithms rely on a succession of calls to a SAT solver in order to find an optimal solution. In particular, several algorithms take advantage of the ability of SAT solvers to identify unsatisfiable subformulas. Usually, these MaxSAT algorithms perform better when small unsatisfiable subformulas are found early. However, this is not the case in many problem instances, since the whole formula is given to the SAT solver in each call. In this paper, we propose to partition the MaxSAT formula using a resolution-based graph representation. Partitions are then iteratively joined by using a proximity measure extracted from the graph representation of the formula. The algorithm ends when only one partition remains and the optimal solution is found. Experimental results show that this new approach further enhances a state of the art MaxSAT solver to optimally solve a larger set of industrial problem instances

Generalized problematic internet use, emotional regulation and self-esteem in adults

Introduction: Many internationally studies, in the last two decades, found problematic internet use associated with a variety of psychosocial problems, but in Portugal this is a recent research question specially in adults. Objectives: To explore the relationship between problematic Internet use, emotional regulation and self-esteem. Methods: 138 Portuguese subjects (77.5% females), with a mean age of 27.76 years old (SD = 8.98, range: 18-58) filled in the Portuguese versions of the Generalized Problematic Internet Use Scale-2, the Difficulties in Emotion Regulation Scale and the Rosenberg Self-Esteem Scale. Results: Negative consequences subscale of generalized problematic internet use was positively correlated with all the emotional regulation difficulties subscales and negatively with Self-Esteem, and positively with daily hours of internet usage. A similar result was found for Self-Deficient Regulation subscale, except for Clarity subscale. Mood Regulation was correlated with Strategies, Goals and Self-Esteem. Males showed higher levels of Negative Consequences. Age and age onset of Internet use were negatively correlated with Mood Regulation, Self-Deficient Regulation and Negative Consequences. A statistically significant difference in Mood Regulation, Self-Deficient Regulation and Negative Consequences in marital status levels, and in professional situation, with higher median scores in divorced and single without a relationship and in student subjects; no significant differences were found in educational level. Conclusions: Generalized problematic Internet use, especially their Negative Consequences, is associated with higher emotional dysregulation, low self-esteem, lower age and lower age of Internet onset, being divorced or single without a relationship and being student, and it is more prevalent in males.info:eu-repo/semantics/publishedVersio

Astrometry of mutual approximations between natural satellites. Application to the Galilean moons

Typically we can deliver astrometric positions of natural satellites with errors in the 50-150 mas range. Apparent distances from mutual phenomena, have much smaller errors, less than 10 mas. However, this method can only be applied during the equinox of the planets. We developed a method that can provide accurate astrometric data for natural satellites -- the mutual approximations. The method can be applied when any two satellites pass close by each other in the apparent sky plane. The fundamental parameter is the central instant $t_0$ of the passage when the distances reach a minimum. We applied the method for the Galilean moons. All observations were made with a 0.6 m telescope with a narrow-band filter centred at 889 nm with width of 15 nm which attenuated Jupiter's scattered light. We obtained central instants for 14 mutual approximations observed in 2014-2015. We determined $t_0$ with an average precision of 3.42 mas (10.43 km). For comparison, we also applied the method for 5 occultations in the 2009 mutual phenomena campaign and for 22 occultations in the 2014-2015 campaign. The comparisons of $t_0$ determined by our method with the results from mutual phenomena show an agreement by less than 1-sigma error in $t_0$, typically less than 10 mas. This new method is particularly suitable for observations by small telescopes.Comment: 13 pages, 11 figures and 8 tables. Based on observations made at the Laborat\'orio Nacional de Astrof\'isica (LNA), Itajub\'a-MG, Brazi