Comunidade de pesquisa global: ¿o que os padrões internacionais de coautoria dizem sobre sua estrutura?

Global research community represents a noteworthy object for sociological studies. In this paper we regards it as an entity with network structure and try to analyze the current state of this structure and its recent dynamics. Among the many various approaches to studying the network links that bring together the researchers all over the world, we choose to look at the structure of international co-authorship of research papers published in journals indexed by Scopus Elsevier database. We try to provide a general outline of the network structure, to reveal distinct regional clusters existing at the various levels of this structure, and to discover whatever significant changes took place in the network structure over the last 25 years.La comunidad de investigación global representa un objeto notable para los estudios sociológicos. En este documento, lo consideramos como una entidad con estructura de red e intentamos analizar el estado actual de esta estructura y su dinámica reciente. Entre los diversos enfoques para estudiar los enlaces de red que reúnen a los investigadores de todo el mundo, elegimos observar la estructura de la coautoría internacional de los trabajos de investigación publicados en revistas indexadas por la base de datos Scopus Elsevier. Intentamos proporcionar una descripción general de la estructura de la red, revelar los distintos grupos regionales que existen en los distintos niveles de esta estructura y descubrir los cambios significativos que tuvieron lugar en la estructura de la red durante los últimos 25 años.A comunidade global de pesquisa representa um objeto notável para os estudos sociológicos. Neste trabalho nós o consideramos como uma entidade com estrutura de rede e tentamos analisar o estado atual dessa estrutura e sua dinâmica recente. Entre as várias abordagens para o estudo dos links de rede que reúnem pesquisadores de todo o mundo, optamos por analisar a estrutura de coautoria internacional de trabalhos de pesquisa publicados em periódicos indexados pela base de dados Scopus Elsevier. Tentamos fornecer um esboço geral da estrutura da rede, revelar clusters regionais distintos existentes nos vários níveis dessa estrutura e descobrir as mudanças significativas ocorridas na estrutura da rede nos últimos 25 anos

Stochastic synchronization in globally coupled phase oscillators

Cooperative effects of periodic force and noise in globally Cooperative effects of periodic force and noise in globally coupled systems are studied using a nonlinear diffusion equation for the number density. The amplitude of the order parameter oscillation is enhanced in an intermediate range of noise strength for a globally coupled bistable system, and the order parameter oscillation is entrained to the external periodic force in an intermediate range of noise strength. These enhancement phenomena of the response of the order parameter in the deterministic equations are interpreted as stochastic resonance and stochastic synchronization in globally coupled systems.Comment: 5 figure

Coherence Resonance and Noise-Induced Synchronization in Globally Coupled Hodgkin-Huxley Neurons

The coherence resonance (CR) of globally coupled Hodgkin-Huxley neurons is studied. When the neurons are set in the subthreshold regime near the firing threshold, the additive noise induces limit cycles. The coherence of the system is optimized by the noise. A bell-shaped curve is found for the peak height of power spectra of the spike train, being significantly different from a monotonic behavior for the single neuron. The coupling of the network can enhance CR in two different ways. In particular, when the coupling is strong enough, the synchronization of the system is induced and optimized by the noise. This synchronization leads to a high and wide plateau in the local measure of coherence curve. The local-noise-induced limit cycle can evolve to a refined spatiotemporal order through the dynamical optimization among the autonomous oscillation of an individual neuron, the coupling of the network, and the local noise.Comment: five pages, five figure

Сomparison of biomechanical properties of non-absorbable and partially absorbable mesh implants used in surgery for urinary incontinence and genital prolapse: experimental study

Introduction. The amount of non-absorbable synthetic material used in the surgical treatment of pelvic organ prolapse and stress urinary incontinence has been shown to directly correlate with the risks of mesh-associated complications. Previously, we developed a partially absorbable implant. Currently, there are insufficient data on the use of partially absorbable implants in female pelvic floor reconstruction, which requires comparative biomechanical and pathomorphological studies.Objective. To compare the biomechanical properties of a new generation partially absorbable implants and nonabsorbable polypropylene mesh implants during animal model.Materials & methods. Thirty-nine rabbits weighing 3200 ± 250 g were randomised into three groups depending on the implanted endoprosthesis: group 1 (n = 15) — “Axilen” implant (polydioxanone 98%, polypropylene 2%), group 2 (n = 15) — “Axilen Rapid” implant (polyglycapron 98%, polypropylene 2%), group 3 (n = 9) — “Urosling 1” implant. After implantation, rabbits of all 3 groups were divided into 3 subgroups according to the withdrawal period from the experiment: 14 days, 60 days, and 180 days. The biomaterial obtained was subjected to two studies: evaluation of the macroscopic view of the explanted mesh endoprosthesis with the formed capsule and the surrounding tissues, study of the biomechanical properties of the formed connective tissue capsule with the implant.Results. According to macroscopic evaluation, there was a less significant tissue reaction to partially absorbed implants. A comparative analysis of biomechanical indices revealed no statistically significant difference in rupture elongation at all follow-up periods among the presented groups. Tensile strength, at 60 and 180 days, was not statistically different between the groups described. At 14 days, there was a statistically significant difference in tensile strength between groups 1 and 3 (p = 0.003).Conclusion. During biomechanical animal experiments, the connective tissue capsule formed on the partially absorbable implant was not inferior to the similar parameter of the non-absorbable sample in its tensile strength, which explains a great potential for the use of partially absorbable implants in reconstructive surgery of pelvic organ prolapse and stress urinary incontinence

New-generation synthetic implants for the surgical correction of pelvic organ prolapse and stress urinary incontinence: design and testing

Introduction. Up to 50.0% of postpartum women experience stress urinary incontinence (SUI) and pelvic organ prolapse (POP). One of the most common and pathogenetically substantiated methods for surgical correction of severe SIU and POP is prosthetic reconstruction of the pelvic floor, involves the use of monofilament polypropylene surgical meshes through vaginal or laparoscopic access.. However, this way is associated with specific problems, i.e., primarily mucosal erosions, and pelvic pain. This has served as a trigger for the development of new materials that reduce the likelihood of such side effects.Objective. To develop the new-generation synthetic implants for surgical correction of stress urinary incontinence and pelvic organ prolapse.Materials and methods. The main development stages: 1. design of an experimental sample of a synthetic implant (evaluation of basic, physical and mechanical properties). 2. test of an experimental sample obtained in vitro.Results. A bioresorbable polypropylene ligature delivery system was developed and manufactured in two variants: for the POP correction (mesh tape with a width of 13 – 15 mm) and for the SUI correction (mesh tape with a width of 10 – 11 mm).Conclusion. Based on the results of the in vitro tests, we can conclude that the synthetic implants developed are able to provide physiological longitudinal (axial) support of the necessary pelvic floor sections and reduce the risk of postoperative complications. Further in vivo studies are required to assess the response of living tissue to the implantation of this type of synthetic implants

Multifractal characterization of stochastic resonance

We use a multifractal formalism to study the effect of stochastic resonance in a noisy bistable system driven by various input signals. To characterize the response of a stochastic bistable system we introduce a new measure based on the calculation of a singularity spectrum for a return time sequence. We use wavelet transform modulus maxima method for the singularity spectrum computations. It is shown that the degree of multifractality defined as a width of singularity spectrum can be successfully used as a measure of complexity both in the case of periodic and aperiodic (stochastic or chaotic) input signals. We show that in the case of periodic driving force singularity spectrum can change its structure qualitatively becoming monofractal in the regime of stochastic synchronization. This fact allows us to consider the degree of multifractality as a new measure of stochastic synchronization also. Moreover, our calculations have shown that the effect of stochastic resonance can be catched by this measure even from a very short return time sequence. We use also the proposed approach to characterize the noise-enhanced dynamics of a coupled stochastic neurons model.Comment: 10 pages, 21 EPS-figures, RevTe

Ce-doped Li6Ln(BO3)3 (Ln = Y, Gd) Single crystals fibers grown by micro-pulling down method and luminescence properties

Ce3+-doped borate crystal fibers of Li6Gd(BO 3)3 (LGBO) and Li6Y(BO3)3 (LYBO) compositions are grown by the micro-pulling down (μ-PD) method for potential application in developing new neutron detectors. The ternary equilibrium diagram of Li2O-Gd2O3-B 2O3 is drawn and the preparations of homogeneous mixed LGBO and LYBO powders and growth conditions for single crystal fibers are discussed. Absorption, excitation and X-ray luminescence spectra are investigated. Absolute light yield derived from energy spectra and kinetic decay curves measured under α- and γ-scintillations of Ce 3+-doped LGBO and LYBO single crystal fibers is provided. © 2012 Elsevier B.V. All rights reserved

Phase synchronization and noise-induced resonance in systems of coupled oscillators

We study synchronization and noise-induced resonance phenomena in systems of globally coupled oscillators, each possessing finite inertia. The behavior of the order parameter, which measures collective synchronization of the system, is investigated as the noise level and the coupling strength are varied, and hysteretic behavior is manifested. The power spectrum of the phase velocity is also examined and the quality factor as well as the response function is obtained to reveal noise-induced resonance behavior.Comment: to be published in Phys. Rev.

Not particularly special: critiquing ‘NPS’ as a category of drugs

Novel Psychoactive Substances (NPS) have been a dominant feature of drug discourse for many years now and, in academic, policy and public discourse, have become established as a new – and by implication, distinct – category of drugs. We argue that this understanding of NPS is fundamentally problematic. Differences within the category are obscured, as are similarities between NPS and more established categories of drugs. Focusing on NPS as something new, different or particularly special is misleading and counterproductive and can have serious consequences in terms of understanding the bigger picture in relation to illegal drugs more generally. This has led to overestimations of the size of the NPS problem, obfuscation of the common underlying causes of dependent drug use, and the implementation of significant and problematic policy changes. Further, a failure to see the rise in NPS as just one of a number of emerging trends in contemporary drug scenes, alongside the development of online markets or the rise in domestic drug production operations, for example, impairs our ability to understand the wider societal, cultural and theoretical underpinnings of drug use. NPS are not particularly special: treating them as such can have dangerous and far-reaching consequences

Synchronization and resonance in a driven system of coupled oscillators

We study the noise effects in a driven system of globally coupled oscillators, with particular attention to the interplay between driving and noise. The self-consistency equation for the order parameter, which measures the collective synchronization of the system, is derived; it is found that the total order parameter decreases monotonically with noise, indicating overall suppression of synchronization. Still, for large coupling strengths, there exists an optimal noise level at which the periodic (ac) component of the order parameter reaches its maximum. The response of the phase velocity is also examined and found to display resonance behavior.Comment: 17 pages, 3 figure