133 research outputs found

    Líquenes de las rocas ultramáficas en la Sierra de A Capelada (A Coruña, NW de España)

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    SÁNCHEZ-BIEZMA SERRANO, M. J., ÁLVAREZ ANDRÉS, J. & LÓPEZ DE SILANES VÁZQUEZ, M. E. 2001. Líquenes de las rocas ultramáficas en la Sierra de A Capelada (A Coruña, NW España). Bot. Complutensis 25: 261-269. Se ha llevado a cabo un estudio ecológico y biogeográfico de la flora que se asienta sobre rocas ultramáficas en la Sierra de A Capelada (A Coruña, NW de España), a partir de un catálogo de 106 especies.SÁNCHEZ-BIEZMA SERRANO, M. J., ÁLVAREZ ANDRÉS, J. & LÓPEZ DE SILANES VÁZQUEZ, M. E. 2001. Líchens of ultramafic rocks in the Sierra de A Capelada (A Coruña, NW Spain). Bot. Complutensis 25: 261-269. An ecological and biogeographic study of the flore on ultramaphic rocks in the Sierra de A Capelada (A Coruña, NW Spain) was made from a catalogue of 106 species

    On the relation between Differential Privacy and Quantitative Information Flow

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    Differential privacy is a notion that has emerged in the community of statistical databases, as a response to the problem of protecting the privacy of the database's participants when performing statistical queries. The idea is that a randomized query satisfies differential privacy if the likelihood of obtaining a certain answer for a database xx is not too different from the likelihood of obtaining the same answer on adjacent databases, i.e. databases which differ from xx for only one individual. Information flow is an area of Security concerned with the problem of controlling the leakage of confidential information in programs and protocols. Nowadays, one of the most established approaches to quantify and to reason about leakage is based on the R\'enyi min entropy version of information theory. In this paper, we analyze critically the notion of differential privacy in light of the conceptual framework provided by the R\'enyi min information theory. We show that there is a close relation between differential privacy and leakage, due to the graph symmetries induced by the adjacency relation. Furthermore, we consider the utility of the randomized answer, which measures its expected degree of accuracy. We focus on certain kinds of utility functions called "binary", which have a close correspondence with the R\'enyi min mutual information. Again, it turns out that there can be a tight correspondence between differential privacy and utility, depending on the symmetries induced by the adjacency relation and by the query. Depending on these symmetries we can also build an optimal-utility randomization mechanism while preserving the required level of differential privacy. Our main contribution is a study of the kind of structures that can be induced by the adjacency relation and the query, and how to use them to derive bounds on the leakage and achieve the optimal utility

    A special perturbation method in orbital dynamics

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    The special perturbation method considered in this paper combines simplicity of computer implementation, speed and precision, and can propagate the orbit of any material particle. The paper describes the evolution of some orbital elements based in Euler parameters, which are constants in the unperturbed problem, but which evolve in the time scale imposed by the perturbation. The variation of parameters technique is used to develop expressions for the derivatives of seven elements for the general case, which includes any type of perturbation. These basic differential equations are slightly modified by introducing one additional equation for the time, reaching a total order of eight. The method was developed in the Grupo de Dinámica de Tethers (GDT) of the UPM, as a tool for dynamic simulations of tethers. However, it can be used in any other field and with any kind of orbit and perturbation. It is free of singularities related to small inclination and/or eccentricity. The use of Euler parameters makes it robust. The perturbation forces are handled in a very simple way: the method requires their components in the orbital frame or in an inertial frame. A comparison with other schemes is performed in the paper to show the good performance of the method

    Ultrasonically assisted low-temperature drying of desalted codfish

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    [EN] Low-temperature drying (LTD) constitutes an interesting means of dehydrating foodstuffs, thus preserving the quality of the product. Power ultrasound (US) generates several mechanical effects that could help to shorten the long drying times associated with LTD. In this work, the feasibility of using US in LTD of desalted cod was assessed. For this purpose, desalted cod slices (50 30 5 mm) were dried (2 m/s) at different temperatures (10, 0 and 10 C) without (AIR) and with (AIR þ US, 20.5 kW/m3) US application. Afterwards, the dried samples were rehydrated in distilled water (25 C). A diffusion model was used to describe both drying and rehydration kinetics. The color and hardness of both dried and rehydrated cod samples were also measured. The application of US increased the drying rate at every temperature tested, shortening the drying time by 16% at 0 C and up to 60% at 10 C. The ultrasonically assisted dried samples presented a rehydration rate which was slightly lower than that of those that had been conventionally dried, but they were harder and whiter, which is more suited to consumer preferences. Therefore, power ultrasound could be considered an affordable technology with which to accelerate LTD of desalted cod, providing high quality dried products.The authors acknowledge the financial support of the Spanish Ministerio de Economia y Competitividad (MINECO) - European Regional Development Fund (ERDF) from the project DPI2012-37466-CO3-03 and the FPI fellowship (BES-2010-033460) granted to J.V. Santacatalina. They also wish to acknowledge Carmen Cambra S.L. for their technical support with the selection of the raw material.Santacatalina Bonet, JV.; Guerrero, M.; García Pérez, JV.; Mulet Pons, A.; Cárcel Carrión, JA. (2016). Ultrasonically assisted low-temperature drying of desalted codfish. Food Science and Technology Research. 65:444-450. https://doi.org/10.1016/j.lwt.2015.08.023S4444506

    Influencia de los métodos de conservación en las actividades enzimáticas de suelos forestales mediterráneos

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    Soil storage method may alter enzymatic activity being storage conditions of the soil samples prior to analysis decisive for the results. Studies made on freshly collected soils are generally preferred. However it is always not possible due to practical reasons since for example sampling is often restricted to short period of the year or because a great quantity of microbiological analyses must be made on time and by few people. On this context, soil storage methods are needed, being cold at 4°C the most widely used although sometimes alternative storage methods are also utilized. The aim of this study is to evaluate the effect of two alternative storage methods of soil samples (freezing at –20°C and air drying conservation methods) in comparison to cold at 4°C on the enzymatic activities (dehydrogenase, phosphatase, β-glucosidase and urease soil enzymes). Samples of two forest ecosystems (pine and holm oak forest stand) were taken in two different season of the year (winter and spring 2009). Results showed that enzymatic activities differed when freezing or air drying conservation methods were used in comparison with cold soil samples. Generally, alternative soil storage methods presented lower enzymatic activity than cold at 4°C. However, these changes depend on season and sampling location.El método de conservación del suelo utilizado puede alterar la actividad enzimática, siendo decisivas para los resultados, las condiciones de conservación previas a los análisis. Para los estudios es preferible realizar los análisis en muestras frescas y recién cogidas. Sin embargo, esto no es siempre posible por razones prácticas ya que las muestras se tienen que recoger en un corto periodo del año o porque los análisis los debe hacer poca gente y siempre en un determinado tiempo. En este contexto, se necesita un método de conservación, siendo el mantenimiento en el frigorífico a 4°C el método más usado, aunque existen otros métodos alternativos. El objetivo de este trabajo es el de evaluar el efecto de dos métodos alternativos de conservación (congelado a –20°C y secado a temperatura ambiente) sobre las actividades enzimáticas (deshidrogenasa, fosfatasa, β-glucosidasa y ureasa), en comparación con el mantenido en el frigorífico a 4°C. Las muestras se obtuvieron de dos zonas forestales diferentes (pinar y encinar) y en dos épocas distintas (primavera y verano de 2009). Los resultados mostraron diferencias en las actividades enzimáticas cuando se usó el congelado o secado al aire de las muestras de suelo en comparación con el mantenimiento en el frigorífico. De forma general, los métodos de conservación alternativos mostraron una menor actividad enzimática en las muestras de suelo analizadas. Sin embargo, estos cambios dependen de la época del año y la zona de muestreo

    Compositionality Results for Quantitative Information Flow

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    International audienceIn the min-entropy approach to quantitative information flow, the leakage is defined in terms of a minimization problem, which, in case of large systems, can be computationally rather heavy. The same happens for the recently proposed generalization called g-vulnerability. In this paper we study the case in which the channel associated to the system can be decomposed into simpler channels, which typically happens when the observables consist of several components. Our main contribution is the derivation of bounds on the g-leakage of the whole system in terms of the g-leakage of its components

    Solamen Vaillanti Mollusk powder as an efficient biosorbent for removing cobalt ions from aqueous solution: Kinetic and equilibrium studies

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    In this research, Solamen Vaillanti mollusk (SVM) skin biosorbent was synthesized and used as a low-cost and environmentally friendly adsorbent to eliminate cobalt (Co2+) heavy metal ion from aqueous solution. The surface morphology and specific surface area of SVM were analyzed by SEM and BET analyses. Also, the impact of various effective factors like pH, temperature, contact time, biosorbent dose, and cobalt ion concentration was studied on the uptake process. According to our study, the highest biosorption efficiency of Co2+ (97.31%) was attained at pH 5, a mixing speed of 200 rpm, Co2+ ion concentration of 5 mg l-1, and biosorbent dosage of 2 g l-1 after 50 min. Also, the maximum biosorption capacity of SVM biosorbent was 16.23 mg l-1, which was achieved at pH 5 and temperature of 25 °C. Moreover, kinetic and equilibrium studies demonstrated that the quasi-second-order kinetic model and the Langmuir isotherm model are better compatible with the experimental data. Furthermore, the reusability of the bioadsorbent showed that it can be reused in 4 cycles in the bioadsorption process.Campus Lima Centr

    Metrics for Differential Privacy in Concurrent Systems

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    Part 3: Security AnalysisInternational audienceOriginally proposed for privacy protection in the context of statistical databases, differential privacy is now widely adopted in various models of computation. In this paper we investigate techniques for proving differential privacy in the context of concurrent systems. Our motivation stems from the work of Tschantz et al., who proposed a verification method based on proving the existence of a stratified family between states, that can track the privacy leakage, ensuring that it does not exceed a given leakage budget. We improve this technique by investigating a state property which is more permissive and still implies differential privacy. We consider two pseudometrics on probabilistic automata: The first one is essentially a reformulation of the notion proposed by Tschantz et al. The second one is a more liberal variant, relaxing the relation between them by integrating the notion of amortisation, which results into a more parsimonious use of the privacy budget. We show that the metrical closeness of automata guarantees the preservation of differential privacy, which makes the two metrics suitable for verification. Moreover we show that process combinators are non-expansive in this pseudometric framework. We apply the pseudometric framework to reason about the degree of differential privacy of protocols by the example of the Dining Cryptographers Protocol with biased coins

    Observational diagnostics of gas in protoplanetary disks

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    Protoplanetary disks are composed primarily of gas (99% of the mass). Nevertheless, relatively few observational constraints exist for the gas in disks. In this review, I discuss several observational diagnostics in the UV, optical, near-IR, mid-IR, and (sub)-mm wavelengths that have been employed to study the gas in the disks of young stellar objects. I concentrate in diagnostics that probe the inner 20 AU of the disk, the region where planets are expected to form. I discuss the potential and limitations of each gas tracer and present prospects for future research.Comment: Review written for the proceedings of the conference "Origin and Evolution of Planets 2008", Ascona, Switzerland, June 29 - July 4, 2008. Date manuscript: October 2008. 17 Pages, 6 graphics, 134 reference
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