1,437 research outputs found

    Protection of Relational Databases by Means of Watermarking: Recent Advances and Challenges

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    Databases represent today great economical and strategic concerns for both enterprises and public institutions. In that context, where data leaks, robbery as well as innocent or even hostile data degradation represent a real danger, and watermarking appears as an interesting tool. Watermarking is based on the imperceptible embedding of a message or watermark into a database in order, for instance, to determine its origin as well as to detect if it has been modified. A major advantage of watermarking in relation to other digital content protection mechanisms is that it leaves access to the data while keeping them protected by means of a watermark, independent of the data format storage. Nevertheless, it is necessary to ensure that the introduced distortion does not perturb the exploitation of the database. In this chapter, we give a general overview of the latest database watermarking methods, focusing on those dealing with distortion control. In particular, we present a recent technique based on an ontological modeling of the database semantics that represent the relationships in between attributes—relationships that should be preserved in order to avoid the appearance of incoherent and unlikely records

    Estrategias Aplicadas por los Docentes como Gerentes de Aula para el Fortalecimiento de los Aprendizajes

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    The present research was executed within the quantitative paradigm, under the feasible project modality, with the objective of designing strategies aimed at teachers to strengthen learning in the students of the Arnoldo Gabaldon educational unit, located in Delicias, Rafael Urdaneta municipality State Táchira. The methodology used responds to the characteristics of field descriptive research, not experimental. The study population consisted of 72 teachers. To obtain the information, a 20-item contentive instrument was applied, which measured the factors that influence the application of managerial strategies to strengthen student learning. This instrument was validated and a reliability index of 0.81 was obtained. In the analysis of results, the single and absolute frequencies of each reagent were determined. This resulted in a series of constantly occurring situations that led to the following conclusions: managerial strategies are employed by teachers on average, as well as in organization and planning, there is no commitment in relation to it, although there It was possible to detect that teachers comply with the planned activities on a regular basis. In addition, in the case of management and control, it is denoted how forcefully both processes are fulfilled, even in the majority, and both are assumed as managerial strategies. Therefore, the implementation of strategies is recommended.La presente investigación se ejecutó dentro del paradigma cuantitativo, bajo la modalidad de proyecto factible, con el objetivo de diseñar estrategias dirigidas a docentes para el fortalecimiento de los aprendizajes en los estudiantes de la unidad educativa Arnoldo Gabaldon, ubicada en Delicias, municipio Rafael Urdaneta del estado Táchira. La metodología utilizada responde a las características de la investigación descriptiva de campo, no experimental. La población del estudio estuvo conformada por 72 docentes. Para obtener la información se aplicó, un instrumento contentivo de 20 ítems, los cuales midieron los factores que inciden la aplicación de estrategias gerenciales para el fortalecimiento de los aprendizajes en los estudiantes. Este instrumento fue validado y se obtuvo un índice de confiabilidad de 0,81. En el análisis de resultados se determinaron las frecuencias simples y absolutas de cada reactivo. Lo cual, dio como resultado una serie de situaciones acontecidas constantemente que permitió llegar a las siguientes conclusiones: las estrategias gerenciales son empleadas medianamente por los docentes, como también en la organización y la planificación, no existe un compromiso en relación a ello, aunque allí se logró detectar que los docentes cumplen medianamente con las actividades planificadas. Además de ello en el caso de la dirección y control se denota como de manera contundente se cumple con ambos procesos, incluso de manera mayoritaria, y ambos se asumen como estrategias gerenciales. Por lo tanto, se recomienda la aplicación de las estrategias

    Multistage reliability-based expansion planning of ac distribution networks using a mixed-integer linear programming model

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    A new mathematical model for the multistage distribution network expansion planning problem considering reliability is proposed in this paper. Decisions related to substation and branch expansion are driven by the minimization of the total cost, which comprises investment and operating costs including the impact of reliability. The proposed model features two main novelties. First, a set of novel algebraic expressions is devised for a standard reliability index, namely the expected energy not supplied. As a result, the dependence of reliability on network topology is explicitly and effectively cast in the mathematical formulation of the planning problem at hand. In addition, the effect of the network is characterized by a computationally efficient piecewise linear representation of the ac power flow model that takes into account both real and reactive power. The resulting optimization problem is formulated as an instance of mixed-integer linear programming, which provides a suitable framework for the attainment of high-quality solutions with acceptable computational effort using efficient off-the-shelf software with well-known convergence properties. The effectiveness of the proposed planning methodology is empirically demonstrated by providing cheaper expansion plans that enhance system reliability and by achieving better computational results as compared with state-of-the-art models.En este artículo se propone un nuevo modelo matemático para el problema de planificación de la expansión de la red de distribución multietapa considerando la confiabilidad. Las decisiones relacionadas con la expansión de subestaciones y sucursales están impulsadas por la minimización del costo total, que comprende los costos de inversión y operación, incluido el impacto de la confiabilidad. El modelo propuesto presenta dos novedades principales. En primer lugar, se diseña un conjunto de expresiones algebraicas novedosas para un índice de fiabilidad estándar, a saber, la energía esperada no suministrada. Como resultado, la dependencia de la confiabilidad enla topología de la redse incluye explícita y efectivamente en la formulación matemática del problema de planificación en cuestión. Además, el efecto de la red se caracteriza por una representación lineal por partes computacionalmente eficiente del modelo de flujo de potencia de CA que tiene en cuenta tanto la potencia real como la reactiva. El problema de optimización resultante se formula como una instancia de programación lineal de enteros mixtos, que proporciona un marco adecuado para el logro de soluciones de alta calidad con un esfuerzo computacional aceptable utilizando software comercial eficiente con propiedades de convergencia bien conocidas.. La eficacia de la metodología de planificación propuesta se demuestra empíricamente al proporcionar planes de expansión más económicos que mejoran la confiabilidad del sistema y al lograr mejores resultados computacionales en comparación con los modelos más avanzados

    The Heteromeric Complex Formed by Dopamine Receptor D 5 and CCR9 Leads the Gut Homing of CD4 + T Cells Upon Inflammation.

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    Background and aims: CD4+ T cells constitute central players in inflammatory bowel diseases (IBDs), driving inflammation in the gut mucosa. Current evidence indicates that CCR9 and the integrin α4β7 are necessary and sufficient to imprint colonic homing on CD4+ T cells upon inflammation. Interestingly, dopaminergic signaling has been previously involved in leukocyte homing. Despite dopamine levels are strongly reduced in the inflamed gut mucosa, the role of dopamine in the gut homing of T cells remains unknown. Here, we study how dopaminergic signaling affects T cells upon gut inflammation. Methods: Gut inflammation was induced by transfer of naïve T cells into Rag1-/- mice or by administration of dextran sodium sulfate. T cell migration and differentiation were evaluated by adoptive transfer of congenic lymphocytes followed by flow cytometry analysis. Protein interaction was studied by bioluminescence resonance energy transfer analysis, bimolecular fluorescence complementation, and in situ proximity ligation assays. Results: We show the surface receptor providing colonic tropism to effector CD4+ T cells upon inflammation is not CCR9 but the complex formed by CCR9 and the dopamine receptor D5 (DRD5). Assembly of the heteromeric complex was demonstrated in vitro and in vivo using samples from mouse and human origin. The CCR9:DRD5 heteroreceptor was upregulated in the intestinal mucosa of IBD patients. Signaling assays confirmed that complexes behave differently than individual receptors. Remarkably, the disruption of CCR9:DRD5 assembly attenuated the recruitment of CD4+ T cells into the colonic mucosa. Conclusions: Our findings describe a key homing receptor involved in gut inflammation and introduce a new cell surface module in immune cells: macromolecular complexes formed by G protein-coupled receptors integrating the sensing of multiple molecular cues. Keywords: Chemokine Receptors; Dopaminergic Regulation; G Protein-Coupled Receptors Heteromers; Gut Tropism; Inflammatory Bowel Diseases; Inflammatory Colitis; T Cell Migration

    Prospects for Cherenkov Telescope Array observations of the young supernova remnant RX J1713.7-3946

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    We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7−3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti)correlations of gamma rays with emission at other wavelengths, in particular X-rays and CO/H I emission. We present a series of simulated images of RX J1713.7−3946 for CTA based on a set of observationally motivated models for the gamma-ray emission. In these models, VHE gamma rays produced by high-energy electrons are assumed to trace the nonthermal X-ray emission observed by XMM-Newton, whereas those originating from relativistic protons delineate the local gas distributions. The local atomic and molecular gas distributions are deduced by the NANTEN team from CO and H I observations. Our primary goal is to show how one can distinguish the emission mechanism(s) of the gamma rays (i.e., hadronic versus leptonic, or a mixture of the two) through information provided by their spatial distribution, spectra, and time variation. This work is the first attempt to quantitatively evaluate the capabilities of CTA to achieve various proposed scientific goals by observing this important cosmic particle accelerator

    Evaluation of aquaporins in the cerebrospinal fluid in patients with idiopathic normal pressure hydrocephalus

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    Brain aquaporin 1 (AQP1) and AQP4 are involved in cerebrospinal fluid (CSF) homeostasis and might participate in the origin of hydrocephalus. Studies have shown alterations of perivascular AQP4 expression in idiopathic normal pressure hydrocephalus (iNPH) and Alzheimer’s disease (AD). Due to the overlapping of clinical signs between iNPH and certain neurological conditions, mainly AD, specific biomarkers might improve the diagnostic accuracy for iNPH. The goal of the present study was to analyze and quantify the presence of AQP1 and AQP4 in the CSF of patients with iNPH and AD to determine whether these proteins can be used as biomarkers of iNPH. We examined AQP1 and AQP4 protein levels in the CSF of 179 participants (88 women) classified into 5 groups: possible iNPH (81 participants), hydrocephalus associated with other neurological disorders (13 participants), AD (41 participants), non-AD dementia (32 participants) and healthy controls (12 participants). We recorded each participant’s demographic and clinical variables and indicated, when available in the clinical history, the record of cardiovascular and respiratory complications. An ELISA showed virtually no AQP content in the CSF. Information on the vascular risk factors (available for 61 patients) confirmed some type of vascular risk factor in 86% of the patients with possible iNPH and 58% of the patients with AD. In conclusion, the ELISA analysis showed insufficient sensitivity to detect the presence of AQP1 and AQP4 in CSF, ruling out the possible use of these proteins as biomarkers for diagnosing iNPH.This research was funded by grants PI16/00493 and PI19/01096 to M.E. from the Spanish Ministry of Economy and Competitiveness, co-financed by the Carlos III Health Institute (ISCIII) and European Regional Development Fund (FEDER). J.L.T-C. was partially supported by the Regional Government of Andalusia and FEDER funds through a program for recruitment of young researchers

    Vertidos tóxicos al río Guadiamar: propuestas técnicas para su corrección

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    Inmediatamente de producirse el vertido tóxico al río Guadiamar, el Grupo T.A.R. se lanzó sin pensarlo dos veces a la búsqueda de soluciones técnicas a un panorama desolador y de efectos desconocidos, todos ellos amenazantes. El ácido “se comía el suelo inundado” por la riada, el agua retenida en Entremuros a pH 3, y con un enorme contenido de metales pesados, ocupaba una extensión de kilómetros. Nos hundimos en el agua hasta el cuello, y cuando nos cubría cogimos la barca, metimos el río a pedazos en nuestro laboratorio, para trabajar todas las hipótesis, ensayar todas las posibilidades. Peleando con la realidad le sacamos datos al Guadiamar, diseñamos actuaciones, poniéndole ingeniería a cuantas hipótesis nos planteaba la situación. En primera fila observamos las mejores actuaciones que nadie diseñó. El propio río, activando sus defensas naturales, mejoró la calidad del agua retenida en el dique de Entremuros subiendo el pH y precipitando los metales pesados. Los mecanismos de entrada de los metales pesados en la cadena trófica parecían ser lentos, dando tiempo a que la retirada de los lodos tóxicos llevada a cabo por la Administración fuera eficaz y diera tiempo a realizar tanto esfuerzo. Aunque el Guadiamar ha trabajado muy duro en su propia recuperación, con su ayuda hemos elaborado una gran cantidad de propuestas técnicas; unas para actuaciones de emergencia, otras a corto, medio y largo plazo. También hemos dado forma a un Plan frente a las previsibles avenidas de este primer otoño después del vertido. Nuestro objetivo ha sido poner a disposición soluciones preparadas para todo tipo de problemas, en primera o en segunda instancia. Prevenir no solo una o dos contingencias, se ha tratado de estar preparado para la mayor cantidad de eventualidades posibles. Por ello algunas serán utilizables, otras estarán en reserva, y muchas irían al cajón de los papeles. Pero ahí están por si acaso. Este libro recoge los trabajos de campo, los ensayos de laboratorio y la ingeniería desarrollada en los primeros cuatro meses. Durante el siguiente preparamos la edición del mismo, mientras, en paralelo, continuábamos en el trabajo experimental y el diseño. Cuando se cumpla el quinto mes, el 25 de Septiembre de 1998, lo presentaremos, ciento cincuenta días después... Con la financiación de la Diputación de Sevilla hemos preparado la primera edición en formato CD Rom e Internet, con muy poco coste para acceder a su contenido. En poco tiempo saldrá la edición en papel, con la misma financiación que la primera. Nos gustaría que este documento fuera entendido como lo que es, en nuestra opinión, una llamada urgente al debate de las ideas. Tratamos de ofrecer la información necesaria y el foro donde recoger las propuestas que seguramente muchos pueden aportar sin saber como transmitir sus experiencias. El Grupo de Tratamiento de Aguas Residuales (T.A.R.) abre con este libro la MESA DE DISCUSIÓN, para buscar un poco de luz, avanzar en las soluciones técnicas a la inmensa tarea de recuperar el río Guadiamar. El libro presenta lagunas, unas por la enorme prisa, otra por falta de datos, muchas por nuestra escasez de conocimientos. Dicen en España que “lo mejor es enemigo de lo bueno”...,y nos gustaría recoger ideas hoy mejor que mañana, que podría ser tarde. Nos comprometemos a seguir trabajando en soluciones técnicas, innovaciones tecnológicas e investigación aplicada a la recuperación del Guadiamar, a conocer lo ocurrido y su remedio. Nos comprometemos a publicar de la misma forma los resultados obtenidos, de manera que la discusión y el debate sigan siempre abiertos. El grupo T.A.R. podría ser un punto de intercambio de conocimientos universal, abierto, respetuoso y tolerante, universitario en definitiva, y por tanto útil en el cumplimiento de sus obligaciones. La primera necesidad de responder urgentemente, está dando paso a unas actuaciones programadas, a medida de los efectos de las correcciones introducidas. Deben instaurarse políticas de prevención y nuevas actuaciones para recuperar el Guadiamar, mejorar urgentemente las condiciones del entorno. Aprender de las soluciones adoptadas y generar mejores prácticas, puede ser una buena conclusión del trabajo realizado por tanta gente. Lo que empezó siendo una carrera de velocidad se nos convierte en un maratón, ya no hay que correr explosivamente, hay que mantener un ritmo en la carrera; hay que persistir en el esfuerzo todos los días durante mucho tiempo. Este nuevo desafío sigue siendo duro y difícil. Podéis contar con el Grupo T.A.R. para recorrer el duro camino de la Recuperación

    Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

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    BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
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