On the nonlinear stability of mKdV breathers

A mathematical proof for the stability of mKdV breathers is announced. This proof involves the existence of a nonlinear equation satisfied by all breather profiles, and a new Lyapunov functional which controls the dynamics of small perturbations and instability modes. In order to construct such a functional, we work in a subspace of the energy one. However, our proof introduces new ideas in order to attack the corresponding stability problem in the energy space. Some remarks about the sine-Gordon case are also considered.Comment: 7 p

The multidimensionality of poverty: Time poverty in Spain

In the last few years the concept of poverty has evolved from simply being a measure of income poverty to a multidimensional measure that takes into consideration essential aspects for the attainment of certain levels of wellbeing. This paper assesses how the incorporation of time can contribute to the measurement of poverty. To this end, we reviewed the time poverty literature and focused on the Spanish case. We use the Spanish Time-Use Survey 2009-2010 to analyse time poverty in Spain, and estimate a probit model to assess the probability of being time poor in Spain and identify key factors associated with time poverty in Spain

Spontaneous Symmetry Breakdown in non-relativistic Quantum Mechanics

The advantages and disadvantages of some pedagogical non-relativistic quantum-mechanical models, used to illustrate spontaneous symmetry breakdown, are discussed. A simple quantum-mechanical toy model (a spinor on the line, subject to a magnetostatic interaction) is presented, that exhibits the spontaneous breakdown of an internal symmetry.Comment: 19 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1111.1213. Equations (30) and (31) have been corrected. Other minor correction

Mathematical Thinking and the VESS Model: A Descriptive Study

Critical, creative, and flexible thinking is one of the educational priorities in the 21st Century, at a time in which the world is showing its most ephemeral and uncertain side. In this sense, visible thinking is a fundamental tool for achieving more significant and meaningful learning. The VESS (Meaningful Life with Balance and Wisdom) model, considering how we learn, provides different tools, such as the aforementioned, which facilitate learning. Thus, thinking, and, more specifically, the development of mathematical thinking through the VESS model, provides an open door towards the development of basic cognitive skills, such as attention, metacognition, and memory, and has a direct effect on the three areas of the early childhood education curriculum. The aim of the present work is to discover, in a descriptive manner, how the learning of the VESS model influences future teachers. In the present article, a series of descriptive, correlational, and survey-based models conducted at the University of Cordoba (Córdoba, Spain) are described. Beforehand, a validation of the instrument was performed, which obtained high goodness-of-fit indices, with an adequate validity and reliability

Calibration of semi-analytic models of galaxy formation using Particle Swarm Optimization

We present a fast and accurate method to select an optimal set of parameters in semi-analytic models of galaxy formation and evolution (SAMs). Our approach compares the results of a model against a set of observables applying a stochastic technique called Particle Swarm Optimization (PSO), a self-learning algorithm for localizing regions of maximum likelihood in multidimensional spaces that outperforms traditional sampling methods in terms of computational cost. We apply the PSO technique to the SAG semi-analytic model combined with merger trees extracted from a standard $\Lambda$CDM N-body simulation. The calibration is performed using a combination of observed galaxy properties as constraints, including the local stellar mass function and the black hole to bulge mass relation. We test the ability of the PSO algorithm to find the best set of free parameters of the model by comparing the results with those obtained using a MCMC exploration. Both methods find the same maximum likelihood region, however the PSO method requires one order of magnitude less evaluations. This new approach allows a fast estimation of the best-fitting parameter set in multidimensional spaces, providing a practical tool to test the consequences of including other astrophysical processes in SAMs.Comment: 11 pages, 4 figures, 1 table. Accepted for publication in ApJ. Comments are welcom

Validation of an instrument on tactical-offensive knowledge for players with intellectual disability

El objetivo de este trabajo se centra en construir y validar una herramienta que permita, de forma fiable, evaluar el conocimiento de base de jugadores con discapacidad intelectual leve en aspectos de táctica ofensiva en FS, permitiendo usarlo como evaluación inicial complementaria que guíe el proceso de entrenamiento. El tamaño muestral fue de 68 jugadores (Medad=27; SDedad=9.06 y Mexperiencia=11.78; SDexperiencia=1,29). Los resultados muestran valores adecuados de consistencia interna y de fiabilidad (α=0.64, ω=0.74, ICC=0.64 y test-retest). De manera complementaria, se realizó un análisis cualitativo, mediante una entrevista colectiva a un grupo de expertos, sobre la utilidad del instrumento en esta población de deportistas. Los resultados permiten establecer una sólida base para el empleo de este instrumento en futuros estudiosThe objective of this work is to build and validate a tool that allows, reliably, evaluate the base knowledge of players with mild intellectual impairment in aspects of offensive tactical in FS, so that it can be used as an additional initial evaluation to guide the training process of coaches. The sample size is constituted by 68 subjects (Mage=27; SDage=9.06 y Mexperience=11.78; SDexperience=1,29). The results show satisfactory internal consistency and reliability values (α=0.64, ω=0.74, ICC=0.64 and test-retest). In a complementary manner, a qualitative analysis was carried out, through a collective interview with a group of experts, about the utility of the instrument in this population of athletes. The results allow to establish a solid base for the use of this instrument in future studie

The role of afforestation species as a driver of Hg accumulation in organic horizons of forest soils from a Mediterranean mountain area in SW Europe

Forest areas are a primary sink of atmospheric mercury (Hg) within terrestrial ecosystems, whereas forest vegetation plays a key role in atmospheric Hg transfer to soil horizons. This study assessed variations in total Hg contents (HgT) and accumulation (HgRes) in the soil organic horizons of a forest area in NE Portugal, where post-wildfire afforestation led to the substitution of the native deciduous species (Quercus pyrenaica) by fast-growing coniferous species (Pseudotsuga menziesii and Pinus nigra). The study also evaluated, for each species, the links between Hg contents and other biophilic elements of soil organic matter (C, N, S) present in organic subhorizons (OL, OF, OH). Mean HgT in the organic horizons of the different tree species follow the sequence: P. nigra (88 μg kg−1) < Q. pyrenaica (101 μg kg−1) < P. menziesii (141 μg kg−1). The highest HgRes for the entire organic horizon was found under P. menziesii (471 μg m−2), followed by P. nigra (253 μg m−2) and Q. pyrenaica (189 μg m−2). Among the organic subhorizons, values of HgT and HgRes follow the sequence OL < OF < OH, which is consistent with the degree of organic matter humification. Indeed, HgT and HgRes correlated significantly with the C/N and C/S ratios for all species and organic subhorizons, suggesting that the quality of organic matter may influence strongly the Hg fate in these forest soils. Soils from P. menziesii plots have shown an HgRes 2.5 times higher than in plots dominated by the native Q. pyrenaica. Hg accumulation in the organic horizons, promoted in the coniferous species, may increase the risk of Hg mobilization due to wildfires and forest management practices. Therefore, forest management plans should select cautiously the tree species for afforestation in order to minimize adverse environmental effects caused by changes in the biogeochemical cycle of contaminants such as Hg.M. Méndez-López acknowledges the predoctoral grant FPU of Ministerio de Educación y Formación Profesional (FPU17/05484). It is also recognized the financial support of the Consellería de Cultura, Educación e Universidade (Xunta de Galicia) through the contract ED431C 2021/46-GRC granted to the research group BV1 of the University of Vigo and the research project ED431F2018/06-EXCELENCIA.info:eu-repo/semantics/publishedVersio

Incidence of suspected serious adverse drug reactions in corona virus Ddsease-19 patients detected by a pharmacovigilance program by laboratory signals in a tertiary hospital in Spain: Cautionary data

BACKGROUND: From March to April 2020, Spain was the center of the SARS-CoV-2 pandemic, particularly Madrid with approximately 30% of the cases in Spain. The aim of this study is to report the suspected serious adverse drug reactions (SADRs) in COVID-19 patients vs. non-COVID-19 patients detected by the prospective pharmacovigilance program based on automatic laboratory signals (ALSs) in the hospital (PPLSH) during that period. We also compared the results with the suspected SADRs detected during the same period for 2019. METHODS: All ALSs that reflected potential SADRs including neutropenia, pancytopenia, thrombocytopenia, anemia, eosinophilia, leukocytes in cerebrospinal fluid, hepatitis, pancreatitis, acute kidney injury, rhabdomyolysis, and hyponatremia were prospectively monitored in hospitalized patients during the study periods. We analyzed the incidence and the distribution of causative drugs for the COVID-19 patients. RESULTS: The incidence rate of SADRs detected in the COVID-19 patients was 760.63 (95% CI 707.89–816.01) per 10,000 patients, 4.75-fold higher than the SADR rate for non-COVID-19 patients (160.15 per 10,000 patients, 95% CI 137.09–186.80), and 5.84-fold higher than the SADR rate detected for the same period in 2019 (130.19 per 10,000 patients, 95% CI 109.53–154.36). The most frequently related drugs were tocilizumab (59.84%), dexketoprofen (13.93%), azithromycin (8.43%), lopinavir-ritonavir (7.35%), dexamethasone (7.62%), and chloroquine/hydroxychloroquine (6.91%). CONCLUSIONS: The incidence rate of SADRs detected by the PPSLH in patients with COVID-19 was 4.75-fold higher than that of the non-COVID-19 patients. Caution is recommended when using medications for COVID-19 patients, especially drugs that are hepatotoxic, myotoxic, and those that induce thromboembolic events

Minerales de Mn-Co-Ni en las lateritas De Cuba oriental: resultados preliminares

En los yacimientos de lateritas niquelíferas, el Ni y Co pueden ser incorporados en óxidos e hidróxido s de Mn, donde han precipitados mediante reacciones redox (Elias et al., 1981). Además de asbolanas (ricas en Ni y ricas en Co), otros minerales que contienen Co son heterogenita y litioforita (Chukhrov et al., 1 983; Manceau et al., 1987; Llorca y Monchoux, 1991)

Size matters: how periodicity and depth of LIPSS influences E. coli adhesion on ferritic stainless steel

Bacterial adhesion is a serious problem in the healthcare and food industries, causing health problems and economic losses. This study evaluates the generation of Laser-Induced Periodic Surface Structures (LIPSS) with different periodicities to reduce bacterial adhesion on ferritic stainless steels. LIPSS nanostructuring evolves from hydrophilic to hydrophobic with air exposure. Fresh samples with 870 nm LIPSS show nearly 50 % reduced E. coli adhesion, but this effect diminishes in stabilized samples. This effect on bacterial adhesion can be attributed to LIPSS periodicity being like bacterial size, which would allow bacteria to accommodate and provide a suitable environment for their adhesion. Our results show that, in stable samples when the LIPSS periodicity is around 400 nm, reductions by almost 30 % are achieved and this reduction reaches 35 % when periodicity is close to 270 nm. These results indicate that smaller spatial periods prevent bacteria from fitting into valleys, so they remain on the peaks, hindering bacterial adhesion. Additionally, deeper LIPSS produced by a higher Surface Density of Applied Energy (SDAE), enhance bacteria-material interaction and, thus, increases adhesion