571 research outputs found

    Effect of the electronic pressure on the energy and magnetic moment of charged test particles in turbulent electromagnetic fields

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    In this work we perform direct numerical simulations of three-dimensional magnetohydrodynamics with a background magnetic field, representing solar wind plasma, and introduce test particles to explore how a turbulent electromagnetic environment affects them. Our focus is on the terms of the electric field present in the generalized Omh's Law that are usually dismissed as unimportant. These are the Hall and the electronic pressure (EP) terms, but we concentrate primarily on the latter. We discover that the EP term generates an acceleration of the particles, which represent protons, in the direction parallel to the background magnetic field, in contrast to the known preferential perpendicular energization. By studying the electric field itself, we are able to detect the type of structures of the EP field that produce such parallel acceleration. These are thin and elongated structures placed on top of a monotonic and near-zero background. A statistical study to understand the real significance of the electronic pressure term is also performed

    Estrategia informático-analítica para generar indicadores de eficiencia reproductiva en tambos

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    La obtención de indicadores reproductivos y productivos de establecimientos lecheros a escala regional puede realizarse a través de la combinación de la información que se releva automáticamente durante el monitoreo regular tanto de variables de la producción como del manejo reproductivo. El volumen de datos que se generan a partir de controles lecheros y de sistemas para la gestión de las preñeces y partos en un tambo es cuantiosa. Para combinar los dos tipos de información es necesario explicitar el objetivo de la concatenación de los distintos tipos de datos. En este trabajo ilustramos una estrategia de análisis de datos de controles lecheros (1.465.011) e historia reproductiva (1.112.319) provenientes del seguimiento (Año 2007-2008) de 291 tambos fundamentalmente de la Provincia de Córdoba y de la zona centro y sur de Santa Fe. Las herramientas estadísticas aplicadas luego de unir y depurar ambas bases fueron: curvas de sobrevida de Kaplan-Meier, regresión de riesgo proporcionales de Cox y regresión logística múltiple. Los resultados sugieren que, en relación al objetivo de preñar las vacas lo antes posibles, los indicadores días abiertos y la tasa de preñez acumulada a los 100 días son de relevante información para evaluar la eficiencia reproductiva de un tambo.To obtain regional productive and reproductive indicators from dairy herds we can use and combine the automatic generate information of the milk tests and the regular reproductive monitoring, and management information. Normally, the amount of data in a herd is very large and hard to handle because of milk test and the regular reproduction monitoring. So, before match the two kind of information we need think very well the objectives. In this paper we illustrate an analysis strategy of milk tests (1,465,011) and reproductive management data (1,112,319) from 291 dairy herds. These herds were followed for two years (2997-2008) and are mainly from Cordoba and from the central and south area of Santa Fe. After cleaning and joining the two data sets we performed three statistical analyses and these were: Kaplan-Meier survival curves, Cox proportional hazard ratio, and multiple logistic regression. Following the objective of gets pregnant as soon as possible the cows, the results suggest that days open and 100 days cumulative pregnancy rate are good indicators of reproductive efficiency of dairy herds.Sociedad Argentina de Informática e Investigación Operativ

    Simulations of organic aerosol with CAMx over the Po Valley during the summer season

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    A new sensitivity analysis with the Comprehensive Air Quality Model with Extensions (CAMx) using a traditional two-product scheme (SOAP) and the newer Volatility Basis Set (VBS) algorithm for organic aerosol (OA) calculations is presented. The sensitivity simulations include the default versions of the SOAP and VBS schemes, as well as new parametrizations for the VBS scheme to calculate emissions and volatility distributions of semi- and intermediate-volatile organic compounds. The focus of the simulations is the summer season (May to July 2013), in order to quantify the sensitivity of the model in a period with relatively large photochemical activity. In addition to the model sensitivity, we validate the results with ad hoc OA measurements obtained from aerosol mass spectrometers at two monitoring sites. Unlike winter cases previously published, the comparison with experimental data showed limited sensitivity to total OA amount, with an estimated increase in OA concentrations limited to a few tenths of µg m−3, for both the primary and secondary components. We show that the lack of pronounced sensitivity is related to the effect of the new parametrizations on different emissions sectors. Furthermore, the minor sensitivity to the new parametrizations could be related to the greater partitioning of OA towards the gaseous phase in the summer period, thus reducing the organic fraction in the aerosol phase

    Virtual Screening of acyclovir derivatives as potential antiviral agents: design, synthesis, and biological evaluation of new acyclic nucleoside ProTides

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    Following our findings on the anti-human immunodeficiency virus (HIV) activity of acyclovir (ACV) phosphate prodrugs, we herein report the ProTide approach applied to a series of acyclic nucleosides aimed at the identification of novel and selective antiviral, in particular anti-HIV agents. Acyclic nucleoside analogues used in this study were identified through a virtual screening using HIV-reverse transcriptase (RT), adenylate/guanylate kinase, and human DNA polymerase γ. A total of 39 new phosphate prodrugs were synthesized and evaluated against HIV-1 (in vitro and ex vivo human tonsillar tissue system) and human herpes viruses. Several ProTide compounds showed substantial potency against HIV-1 at low micromolar range while the parent nucleosides were not effective. Also, pronounced inhibition of herpesvirus replication was observed. A carboxypeptidase-mediated hydrolysis study was performed for a selection of compounds to assess the formation of putative metabolites and support the biological activity observed

    Broad Antiviral Activity of Carbohydrate-Binding Agents against the Four Serotypes of Dengue Virus in Monocyte-Derived Dendritic Cells

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    BACKGROUND: Dendritic cells (DC), present in the skin, are the first target cells of dengue virus (DENV). Dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) is present on DC and recognizes N-glycosylation sites on the E-glycoprotein of DENV. Thus, the DC-SIGN/E-glycoprotein interaction can be considered as an important target for inhibitors of viral replication. We evaluated various carbohydrate-binding agents (CBAs) against all four described serotypes of DENV replication in Raji/DC-SIGN(+) cells and in monocyte-derived DC (MDDC). METHODOLOGY/PRINCIPAL FINDINGS: A dose-dependent anti-DENV activity of the CBAs Hippeastrum hybrid (HHA), Galanthus nivalis (GNA) and Urtica dioica (UDA), but not actinohivin (AH) was observed against all four DENV serotypes as analyzed by flow cytometry making use of anti-DENV antibodies. Remarkably, the potency of the CBAs against DENV in MDDC cultures was significantly higher (up to 100-fold) than in Raji/DC-SIGN(+) cells. Pradimicin-S (PRM-S), a small-size non-peptidic CBA, exerted antiviral activity in MDDC but not in Raji/DC-SIGN(+) cells. The CBAs act at an early step of DENV infection as they bind to the viral envelope of DENV and subsequently prevent virus attachment. Only weak antiviral activity of the CBAs was detected when administered after the virus attachment step. The CBAs were also able to completely prevent the cellular activation and differentiation process of MDDC induced upon DENV infection. CONCLUSIONS/SIGNIFICANCE: The CBAs exerted broad spectrum antiviral activity against the four DENV serotypes, laboratory-adapted viruses and low passage clinical isolates, evaluated in Raji/DC-SIGN(+) cells and in primary MDDC

    INTERNAL FRICTION AND YOUNG'S MODULUS MEASUREMENTS ON SiO2 AND Ta2O5 FILMS DONE WITH AN ULTRA-HIGH Q SILICON-WAFER SUSPENSION

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    International audienceIn order to study the internal friction of thin films a nodal suspension system called GeNS (Gentle Nodal Suspension) has been developed. The key features of this system are: i) the possibility to use substrates easily available like silicon wafers; ii) extremely low excess losses coming from the suspension system which allows to measure Q factors in excess of 2×10^8 on 3 " diameter wafers; iii) reproducibility of measurements within few percent on mechanical losses and 0.01% on resonant frequencies; iv) absence of clamping; v) the capability to operate at cryogenic temperatures. Measurements at cryogenic temperatures on SiO 2 and at room temperature only on Ta2O5 films deposited on silicon are presented

    1,3,5-Triazines with aromatic amino acids: Exploring their potential as lectin mimetics

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    VII Escuela de verano de la SEQT, Sociedad Española de Química Terapeútica, Barcelona, 19-21 Julio, 202

    Surfactant protein D inhibits HIV-1 infection of target cells via interference with gp120-CD4 interaction and modulates pro-inflammatory cytokine production

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    © 2014 Pandit et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Surfactant Protein SP-D, a member of the collectin family, is a pattern recognition protein, secreted by mucosal epithelial cells and has an important role in innate immunity against various pathogens. In this study, we confirm that native human SP-D and a recombinant fragment of human SP-D (rhSP-D) bind to gp120 of HIV-1 and significantly inhibit viral replication in vitro in a calcium and dose-dependent manner. We show, for the first time, that SP-D and rhSP-D act as potent inhibitors of HIV-1 entry in to target cells and block the interaction between CD4 and gp120 in a dose-dependent manner. The rhSP-D-mediated inhibition of viral replication was examined using three clinical isolates of HIV-1 and three target cells: Jurkat T cells, U937 monocytic cells and PBMCs. HIV-1 induced cytokine storm in the three target cells was significantly suppressed by rhSP-D. Phosphorylation of key kinases p38, Erk1/2 and AKT, which contribute to HIV-1 induced immune activation, was significantly reduced in vitro in the presence of rhSP-D. Notably, anti-HIV-1 activity of rhSP-D was retained in the presence of biological fluids such as cervico-vaginal lavage and seminal plasma. Our study illustrates the multi-faceted role of human SPD against HIV-1 and potential of rhSP-D for immunotherapy to inhibit viral entry and immune activation in acute HIV infection. © 2014 Pandit et al.The work (Project no. 2011-16850) was supported by Medical Innovation Fund of Indian Council of Medical Research, New Delhi, India (www.icmr.nic.in/)
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