666 research outputs found

    Highly-complex optical signal generation using electro-optical systems with non-linear, non-invertible transmission functions

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    We present a scheme whereby a static non-linear, non-invertible transmission function performed by the electro-optic Mach-Zehnder modulator produces highly complex optical chaos. The scheme allows the deterministic transformation of low-dimensional band-limited chaotic signals into much higher-dimensional structures with broadband spectra and without using any delay elements or feedback. Standard benchmark tests show that all the considered complexity indices are highly increased due to this transformation in a controlled fashion. This mechanism allows the design of simple optoelectronic delayed oscillators with extremely complex chaotic output.Comment: 4 pages, 5 figures. To appear in Applied Physics Letters (August 2012

    Diverse routes to oscillation death in a coupled-oscillator system.

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    We study oscillation death (OD) in a well-known coupled-oscillator system that has been used to model cardiovascular phenomena. We derive exact analytic conditions that allow the prediction of OD through the two known bifurcation routes, in the same model, and for different numbers of coupled oscillators. Our exact analytic results enable us to generalize OD as a multiparameter-sensitive phenomenon. It can be induced, not only by changes in couplings, but also by changes in the oscillator frequencies or amplitudes. We observe synchronization transitions as a function of coupling and confirm the robustness of the phenomena in the presence of noise. Numerical and analogue simulations are in good agreement with the theory

    Psychometric properties of the Valuing Questionnaire in a Spaniard sample and factorial equivalence with a Colombian sample

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    Background. The Valuing Questionnaire (VQ) is considered as one of the most psychometrically robust instruments to measure valued living according to the acceptance and commitment therapy model. It consists of 10 items that are responded to on a 7-point Likert-type scale and has two factors: Progression and Obstruction. The Spanish version of theVQshowed good psychometric properties in Colombian samples. However, there is no evidence of the psychometric properties of the VQ in Spaniard samples. This study aims to analyze the validity of the VQ in a large Spaniard sample and analyze the measurement invariance with a similar Colombian sample. Method. The VQ was administered to a Spaniard sample of 846 adult participants from general online population. Cronbach's alpha and McDonald's omega were computed to analyze the internal consistency of the VQ. The fit of the VQ's two-factor model was tested through a confirmatory factor analysis with a robust maximum likelihood (MLR) estimation method. Afterward, we analyzed the measurement invariance across countries and gender. Convergent construct validity was analyzed with a package of questionnaires that evaluated experiential avoidance (Acceptance and Action Questionnaire-II, AAQ-II), emotional symptoms (Depression Anxiety and Stress Scale-21, DASS-21), life satisfaction (Satisfaction with Life Scale, SWLS), and cognitive fusion (Cognitive Fusion Questionnaire, CFQ). Results. The internal consistency across samples was adequate (alphas and omegas were .85 for VQ-Progress and .84 for VQ-Obstruction). The two-factor model obtained a good fit to the data (RMSEA D 0.073, 90% CI [0.063, 0.083], CFI D 0.98, NNFI D 0.97, and SRMR D 0.053). The VQ showed strict invariance across countries and gender and showed theoretically coherent correlations with emotional symptoms, life satisfaction, experiential avoidance, and cognitive fusion. In conclusion, the Spanish version of the VQ demonstrated good psychometric properties in a large Spaniard sample

    An Open-Source Proactive Security Infrastructure for Business Process Management

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    Business Process Management Systems (BPMS) have emerged in the IT arena as cornerstone in the automation and orchestration of complex services for organizations. These systems manage critical information that is crucial for the organizations. The potential cost and consequences of security threats could produce information loss for the reputation of organizations. Therefore, the early response regarding to the non-compliance of security requirement is a real necessity overall during the business process execution. Currently, an active response requires a human intervention with high know-how and expertise in both business process management and security. In this paper, we propose an initial work which presents an open-source proactive infrastructure for the automatic continuous monitoring and checking compliance of security requirements at runtime of business processes

    Sex-specific behavioral and neurogenic responses to cocaine in mice lacking and blocking dopamine D1 or dopamine D2 receptors

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    Adult neurogenesis in rodents is modulated by dopaminergic signaling and inhibited by cocaine. However, the sex-specific role of dopamine D1 and D2 receptors (D1R, D2R) in the deleterious effect of cocaine on adult neurogenesis has not been described yet. Here, we explored sex differences in (a) cell proliferation (5′-bromo-2′-deoxyuridine [BrdU]), (b) neural precursor (nestin), (c) neuronal phenotype (BrdU/β3-tubulin), and (d) neuronal maturity (NeuN) in the subventricular zone (SVZ) of the lateral ventricles and striatum of mice with genetic deletion (D1, D2) or pharmacological blockage (SCH23390: 0.1 mg/kg/day/5 days; Raclopride: 0.3 mg/kg/day/5 days) of D1R and D2R, and treated (10 mg/kg/day/5 days) and then challenged (5 mg/kg, 48 hr later) with cocaine. Results indicated that hyperactivity responses to cocaine were absent in D1 mice and reduced in SCH23390-treated mice. Activity responses to cocaine were reduced in D2 males, but absent in D2 females and increased in Raclopride-treated females. D1R deletion blocked the deleterious effect of cocaine on SVZ cell proliferation in males. Cocaine-exposed D1 males also had reduced neuronal phenotype of SVZ newborn cells and increased striatal neuronal maturity. D2 mice had lower proliferative and neural precursor responses. Cocaine in D2 females or coadministered with Raclopride in wild-type females improved SVZ cell proliferation, an effect that positively correlated with plasma brain-derived neurotrophic factor (BDNF) concentrations. In conclusion, the sex-specific D1R and D2R signaling on SVZ cell proliferation, neural progenitor and neuronal maturity is differentially perturbed by cocaine, and BDNF may be required to link D2R to neuroplasticity in cocaine addiction in females.Consejería de Salud, Junta de Andalucía, Grant/Award Number: C1-0049-2019; Instituto de Salud Carlos III, Grant/Award Numbers: CP19/00068, CPII17/00024, CPII19/00022, CPII19/00031, PI19/01577, PI19/00886, PI17/02026, RD16/0017/0001; Ministerio de Sanidad, Servicios Sociales e Igualdad, Grant/Award Numbers: PND2017/043, PND2018/033, PND2018/044, PND2019/04

    Precarious employment and health: A qualitative study in Venezuelan immigrant population in Colombia

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    Background: Employment and working conditions are considered as an element that impacts on health inequalities, especially among vulnerable groups such as the immigrant population. This study aims to describe the characteristics of precarious employment in the Venezuelan immigrant population in Medellín (Colombia) according to its theoretical model and its relationship with the perception of their physical, mental, and psychosocial health. Methods: A qualitative study was conducted with a focused ethnography perspective. 31 people with Venezuelan origin and work experience were interviewed in the city of Medellin and its metropolitan area and 12 key informants from different formal and informal social organizations that work with the immigrant population. A narrative content analysis was carried manually and by using the Atlas.Ti 8.0 software. The principles of analytical induction were applied to carry out a thematic analysis of the main categories defined in the precarious employment framework. Results: The following characteristics of precarious employment were found: instability in employment conditions, work in the informal or submerged economy, limited empowerment, absence of social benefits, high vulnerability, low income, and a limited capacity for exercising labor rights. This situation affects mental health conditions, access to health services, and the presence of risks due to the work they perform. Conclusions: The Venezuelan working population in Medellín is found in a precarious employment situation. Inclusive social strategies and policies that take into account the reality of this population are required

    Hallazgo de nuevos mosaicos en Écija (Sevilla)

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    La excavación arqueológica llevada a cabo en un solar situado entre las Calles Fernández Pintado y Elvira de Écija, han puesto al descubierto unos restos romanos de gran interés, entre los que destacan los dos mosaicos descubiertos, el de la venera y el del circo, que en el trascurso del presente trabajo procederemos a analizar y estudiar de manera exhaustiva y pormenorizada. Se trata pues de dos nuevos e interesantes pavimentos que se suman al rico patrimonio musivo de Écija y que por sus propias características y configuración suponen una absoluta novedad dentro del conjunto musivo de dicha ciudad. ---------------------------------------------------------------------The archaeological excavation recently carried out in Écija (Sevilla), in a site between Fernández and Elvira streets, brought out some roman remains, among them two outstanding mosaics. Both of them are interesting and original pavements which came to complete the rich musive heritage of the roman city. In the present work we analyze and study them in detail

    Phenotypic plasticity of growth ring traits in Pinus hartwegii at the ends of its elevational gradient

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    IntroductionPhenotypic plasticity (PP) could be an important short-term mechanism to modify physiological and morphological traits in response to climate change and global warming, particularly for high-mountain tree species. The objective was to evaluate PP response of growth ring traits to temperature and precipitation in Pinus hartwegii Lindl. populations located at the ends of its elevational gradient on two volcanic mountains in central Mexico (La Malinche and Nevado de Toluca).MethodsIncrement cores collected from 274 P. hartwegii trees were used to estimate their PP through reaction norms (RN), which relate the ring width and density traits with climate variables (temperature and precipitation). We estimated the trees’ sensitivity (significant RN) to climatic variables, as well as the relative proportion of RN with positive and negative slope. We also estimated the relationship between the PP of ring width and density traits using correlation and Principal Component (PC) analyses.ResultsOver 70% of all trees showed significant RN to growing season and winter temperatures for at least one growth ring trait, with a similar proportion of significant RN at both ends of the gradient on both mountains. Ring width traits had mostly negative RN, while ring density traits tended to have positive RN. Frequency of negative RN decreased from lower to higher elevation for most traits. Average PP was higher at the lower end of the gradient, especially on LM, both for ring width and ring density traits, although high intrapopulation variation in PP was found on both mountains.DiscussionResults indicate that P. hartwegii presents spatially differentiated plastic responses in width and density components of radial growth. PP was particularly strong at the lower elevation, which has higher temperature and water stress conditions, putting these populations at risk from the continuing global warming driven by climate change
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