2,601 research outputs found

    Interacting dark sector with variable vacuum energy

    Get PDF
    We examine a cosmological scenario where dark matter is coupled to a variable vacuum energy while baryons and photons are two decoupled components for a spatially flat Friedmann-Robertson-Walker spacetime. We apply the χ2\chi^{2} method to the updated observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era. We show that our model fulfills the severe bound of Ωx(z1100)<0.009\Omega_{x}(z\simeq 1100)<0.009 at the 2σ2\sigma level, so it is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from the Planck survey, the Atacama Cosmology Telescope, and the South Pole Telescope along with the future constraints achievable by the Euclid and CMBPol experiments, and fulfills the stringent bound Ωx(z1010)<0.04\Omega_{x}(z\simeq 10^{10})<0.04 at the 2σ2\sigma level in the big-bang nucleosynthesis epoch.Comment: 5 pages,3 figures, 2 tables. (http://prd.aps.org/abstract/PRD/v88/i8/e087301

    Estimation of PCBs content in agricultural soils associated with long-term fertilization with organic waste

    Get PDF
    Polychlorinated biphenyl (PCB) pollution related to the use of organic waste as fertilizers in agricultural soils is a cause of major concern. In the study presented herein, PCB concentration was studied through a field trial conducted in two agricultural soils in the province of Palencia (Spain) over a 4-year period, assessing the impact of irrigation and of different types of organic waste materials. The amounts of organic waste added to the soil were calculated according to the nitrogen needs of the crop, and the concentration of PCBs was determined before and after the application of the organic waste. The resulting persistence of the total PCB content in the agricultural soils, compared with the PCB concentration in the original soils, ranged from 27% to 90%, with the lowest value corresponding to irrigated soils treated with municipal solid waste compost (MSWC) and the highest value to non-irrigated soils treated with composted sewage sludge (CSS). An estimate of the PCB content in agricultural soils after the application of organic waste materials until year 2050 was obtained, resulting in a value below 5 ng·g-1, considered a background value for soils in sites far away from potential pollution sources

    Cyttaria hariotii E.Fisch. as a promising source of pullulan and Mn(II)-pullulan complexes for Mn-deficiency remediation in winter cereals

    Get PDF
    Pullulan, a water-soluble polysaccharide consisting of maltotriose units used in the preparation of edible films and drug delivery, is generally produced from starch by Aureobasidium pullulans (de Bary & Löwenthal) G.Arnaud fungus. In this article, the characterisation of an alternative pullulan source - the stromata of Cyttaria hariotii E.Fisch. fungus - by elemental analysis, infrared spectroscopy and thermal analysis techniques is reported. With a view to a possible valorisation of this pullulan and its derivatives as bioactive formulations in agriculture, low-molecular-weight pullulan (<7 kDa) complexes with Mn(II), suitable for the remediation of Mn-deficiencies in winter cereal by foliar application, were synthesised and characterised by mass spectrometry

    Research on nonlinear and quantum optics at the photonics and quantum information group of the University of Valladolid

    Get PDF
    We outline the main research lines in Nonlinear and Quantum Optics of the Group of Photonics and Quantum Information at the University of Valladolid. These works focus on Optical Solitons, Quantum Information using Photonic Technologies and the development of new materials for Nonlinar Optics. The investigations on optical solitons cover both temporal solitons in dispersion managed fiber links and nonparaxial spatial solitons as described by the Nonlinear Helmholtz Equation. Within the Quantum Information research lines of the group, the studies address new photonic schemes for quantum computation and the multiplexing of quantum data. The investigations of the group are, to a large extent, based on intensive and parallel computations. Some associated numerical techniques for the development of the activities described are briefly sketched

    Universal Conductance Distributions in the Crossover between Diffusive and Localization Regimes

    Full text link
    The full distribution of the conductance P(G)P(G) in quasi-one-dimensional wires with rough surfaces is analyzed from the diffusive to the localization regime. In the crossover region, where the statistics is dominated by only one or two eigenchannels, the numerically obtained P(G) is found to be independent of the details of the system with the average conductance as the only scaling parameter. For < e^2/h, P(G) is given by an essentially ``one-sided'' log-normal distribution. In contrast, for e^2/h <= 2e^2/h, the shape of P(G) remarkable agrees with those predicted by random matrix theory for two fluctuating transmission eigenchannels.Comment: Accepted for publication in Phys. Rev. Let

    Magnetic Field Effects on the Transport Properties of One-sided Rough Wires

    Full text link
    We present a detailed numerical analysis of the effect of a magnetic field on the transport properties of a `small-NN' one-sided surface disordered wire. When time reversal symmetry is broken due to a magnetic field BB, we find a strong increase with BB not only of the localization length ξ\xi but also of the mean free path \ell caused by boundary states. Despite this, the universal relationship between \ell and ξ\xi does hold. We also analyze the conductance distribution at the metal-insulator crossover, finding a very good agreement with Random Matrix Theory with two fluctuating channels within the Circular Orthogonal(Unitary) Ensemble in absence(presence) of BBComment: 5 pages, 4 figures, to appear in Phys. Rev.

    Diseño y construcción de un sistema de archivo personal computadorizado para clínicas odontológicas

    Full text link
    El objetivo del sistema es gestionar de manera automática y flexible el archivo profesional de los odontólogos. Los requisitos que debía cumplir el sistema fueron obtenidos mediante consultas a distintos especialistas odontólogos, fruto de las cuales fue la especificación de los tipos de información y los procesos de la misma que - tienen lugar en la consulta del odontólogo

    ARPECOD Un sistema microinformativo para la gestión de clínica odontológica

    Full text link
    ARPECOD, cuyas siglas significan Archivo Personal, Computadorizado para Odontólogos, es un prototipo de instrumento especializado de ayuda a la creación, recuperación rápida y gestión dinámica y automática de historiales de clientes de profesionales odontólogos. Se ha concebido,diseñado, construido y probado en su totalidad en el Laboratorio de Ordenadores, Cibernética y Teoría de Sistemas (LOCTS) de la Escuela Técnica Superior de Ingenieros de Telecomunicación de Madrid por un grupo de profesores y alumnos

    Physicochemical characterization and antimicrobial activity against Erwinia amylovora, Erwinia vitivora, and Diplodia seriata of a light purple Hibiscus syriacus L. Cultivar

    Get PDF
    Phytochemicals are essential raw materials for the production of formulations that can be helpful in crop protection. In particular, Hibiscus spp., which are often used in traditional medicine, are rich in potential bioactive molecules. This study presents an analysis of the thermal, vibrational, and phytochemical characteristics of a light purple variety of Hibiscus syriacus, using thermal gravimetric and differential scanning calorimetry, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectroscopy techniques. Further, with a view to its valorization, the antimicrobial activity of its extracts has been investigated in vitro against Erwinia amylovora (the phytopathogen responsible for fire blight in apples, pears, and some other members of the family Rosaceae), Erwinia vitivora (the causal agent of the “maladie d’Oléron” in grapevines), and Diplodia seriata (responsible for “Bot canker”). Higher heating values and thermal features showed similarities with kenaf biomass. The main compounds identified in the hydro-methanolic extracts were: in flowers, 1-heptacosanol, heptacosane, 1-tetracosanol, hexadecenoic acid, 9,12,15-octadecatrienoic acid, and 9,12-octadecadienoic acid; and in leaves, the coumarin derivative 4,4,6,8-tetramethyl-2-chromanone, vitamin E, phytol, and sitosterol. MIC values of 500 and 375 μg·mL−1 were obtained against E. amylovora for flower and leaf extracts, respectively, upon conjugation with chitosan oligomers (to improve solubility and bioavailability). In the case of E. vitivora, MIC values of 250 and 500 μg·mL−1, respectively, were registered. Regarding the antifungal activity, EC90 values of 975.8 and 603.5 μg·mL−1, respectively, were found. These findings suggest that H. syriacus (cv. ‘Mathilde’) may be a promising source of antimicrobials for agriculture
    corecore