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Berlin Brandenburg

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  • 1
    In: Water Resources Research, October 2012, Vol.48(10), pp.n/a-n/a
    Description: In this study we present a formula for the hydraulic head describing the mean drawdown of a three dimensional steady state pumping test in heterogeneous anisotropic porous media effectively. By modeling the hydraulic conductivity as spatial random function and using the upscaling method Coarse Graining we succeed in deriving a closed form solution () which we understand as an extension of Thiem's formula to heterogeneous media. The solution () does not only depend on the radial distance r but accounts also for the statistics of , namely geometric mean , variance , horizontal correlation length and anisotropy ratio . We perform a sensitivity analysis on the parameters of () and implement an inverse estimation strategy. Using numerical pumping tests we show the applicability of () on the interpretation of drawdown data. This will be done for both, an ensemble of as well as for single pumping tests. Making use of the inverse estimation method we find excellent agreement of estimated parameters with initial values, in particular for the horizontal correlation length. Formula for effective description of hydraulic head of steady state pumping test Analysis of 3D numerical pumping tests in highly heterogeneous anisotropic media Direct estimation method to infer on statistics of log normal conductivity
    Keywords: Coarse Graining ; Geostatistics ; Heterogeneity ; Steady State Pumping Tests
    ISSN: 0043-1397
    E-ISSN: 1944-7973
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  • 2
    Language: English
    In: Vadose Zone Journal, 2011, Vol.10(3), p.988
    Description: Recent studies have shown that rhizosphere hydraulic properties may differ from those of the bulk soil. Specifically, mucilage at the root-soil interface may increase the rhizosphere water holding capacity and hydraulic conductivity during drying. The goal of this study was to point out the implications of such altered rhizosphere hydraulic properties for soil-plant water relations. We addressed this problem through modeling based on a steady-rate approach. We calculated the water flow toward a single root assuming that the rhizosphere and bulk soil were two concentric cylinders having different hydraulic properties. Based on our previous experimental results, we assumed that the rhizosphere had higher water holding capacity and unsaturated conductivity than the bulk soil. The results showed that the water potential gradients in the rhizosphere were much smaller than in the bulk soil. The consequence is that the rhizosphere attenuated and delayed the drop in water potential in the vicinity of the root surface when the soil dried. This led to increased water availability to plants, as well as to higher effective conductivity under unsaturated conditions. The reasons were two: (i) thanks to the high unsaturated conductivity of the rhizosphere, the radius of water uptake was extended from the root to the rhizosphere surface; and (ii) thanks to the high soil water capacity of the rhizosphere, the water depletion in the bulk soil was compensated by water depletion in the rhizosphere. We conclude that under the assumed conditions, the rhizosphere works as an optimal hydraulic conductor and as a reservoir of water that can be taken up when water in the bulk soil becomes limiting.
    Keywords: Agriculture;
    ISSN: Vadose Zone Journal
    E-ISSN: 1539-1663
    Source: CrossRef
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  • 3
    Language: English
    In: PLoS ONE, 2009, Vol.4(11), p.e7986
    Description: Prenatal exposure to allergens or antigens released by infections during pregnancy can stimulate an immune response or induce immunoregulatory networks in the fetus affecting susceptibility to infection and disease later in life. How antigen crosses from the maternal to fetal environment is poorly understood. One hypothesis is that transplacental antigen transfer occurs as immune complexes, via receptor-mediated transport across the syncytiotrophoblastic membrane and endothelium of vessels in fetal villi. This hypothesis has never been directly tested. Here we studied Plasmodium falciparum merozoite surface protein 1 (MSP1) that is released upon erythrocyte invasion. We found MSP1 in cord blood from a third of newborns of malaria-infected women and in 〉90% following treatment with acid dissociation demonstrating MSP1 immune complexes. Using an ex vivo human placental model that dually perfuses a placental cotyledon with independent maternal and fetal circuits, immune-complexed MSP1 transferred from maternal to fetal circulation. MSP1 alone or with non-immune plasma did not transfer; pre-incubation with human plasma containing anti-MSP1 was required. MSP1 bound to IgG was detected in the fetal perfusate. Laser scanning confocal microscopy demonstrated MSP1 in the fetal villous stroma, predominantly in fetal endothelial cells. MSP1 co-localized with IgG in endothelial cells, but not with placental macrophages. Thus we show, for the first time, antibody-dependent transplacental transfer of an antigen in the form of immune complexes. These studies imply frequent exposure of the fetus to certain antigens with implications for management of maternal infections during pregnancy and novel approaches to deliver vaccines or drugs to the fetus.
    Keywords: Research Article ; Infectious Diseases -- Protozoal Infections ; Pathology -- Immunology ; Pediatrics And Child Health -- Neonatology
    E-ISSN: 1932-6203
    Source: PLoS
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  • 4
    Language: English
    In: Bioorganic & Medicinal Chemistry Letters, 01 March 2013, Vol.23(5), pp.1168-1176
    Description: Systems biology aims to provide a holistic and in many cases dynamic picture of biological function and malfunction, in case of disease. Technology developments in the generation of genome-wide datasets and massive improvements in computer power now allow to obtain new insights into complex biological networks and to copy nature by computing these interactions and their kinetics and by generating in silico models of cells, tissues and organs. The expectations are high that systems biology will pave the way to the identification of novel disease genes, to the selection of successful drug candidates—that do not fail in clinical studies due to toxicity or lack of human efficacy—and finally to a more successful discovery of novel therapeutics. However, further research is necessary to fully unleash the potential of systems biology. Within this review we aim to highlight the most important and promising top-down and bottom-up systems biology applications in drug discovery.
    Keywords: Systems Biology ; Molecular Mechanistic Models ; Physiological Models ; Top-Down Systems Biology ; Bottom-Up Systems Biology ; Medicine ; Chemistry ; Anatomy & Physiology
    ISSN: 0960-894X
    E-ISSN: 1464-3405
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  • 5
    In: Chemical Communications, 2015, Vol.51(79), pp.14797-14800
    Description: We disclose herein a highly enantioselective de novo -synthesis of chiral 1-cyclopentenyl--keto esters starting from a simple bis-silyl-1,3-dienediolate and ,-unsaturated aldehydes via a domino vinylogous Michael-intramolecular Knoevenagel-type condensation. The cyclopentenes proved to be highly versatile and were readily converted into various structural motifs.
    Keywords: Chemistry;
    ISSN: 1359-7345
    E-ISSN: 1364-548X
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  • 6
    Language: English
    In: The Journal of organic chemistry, 02 June 2017, Vol.82(11), pp.5986-5992
    Description: We report herein the first Lewis acid-catalyzed generation of 2-amidoallyl cations through ring-opening of 4-benzylidene-2-oxazolines with Sc(OTf). Upon nucleophilic addition of indoles, indolylenamides were obtained with yields of 60-99% and excellent (Z)-selectivity. In addition, the novel strategy was also successfully applied to pyrroles and naphthols as π-nucleophiles. A Brønsted acid-catalyzed process using TfOH formed in situ was ruled out by control experiments.
    Keywords: Lewis Structures – Research ; Catalysis – Usage ; Azo Compounds – Chemical Properties ; Nucleophiles – Research ; Indoles – Chemical Properties;
    ISSN: 00223263
    E-ISSN: 1520-6904
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  • 7
    Language: English
    In: Journal of Applied Physics, 28 June 2015, Vol.117(24)
    Description: A model for explosive crystallization in a thin amorphous layer on a heat conducting substrate is presented. For the thin layer, the energy equation is used in a one-dimensional approximation. Heat conduction into the substrate and thermal contact resistance at the interface between layer and substrate are taken into account. Four rate equations are used to describe the kinetics of the homogeneous amorphous-crystalline transition. The whole process is examined as a plane wave of invariant shape in a moving frame of reference. Heat conduction in the substrate is described by introducing a continuous distribution of moving heat sources at the interface. This gives an integral representation for the temperature in the substrate in terms of the unknown source distribution. The integral term implies that there is a non-local influence of the temperature distribution in the layer on the heat loss. A coupled system of an integro-differential equation and four ordinary differential equations is obtained and solved numerically. The propagation velocity of the wave is obtained as an eigenvalue of the system of equations. Varying a non-dimensional heat loss parameter, a critical value is found beyond which no crystallization wave of invariant shape is possible. This can also be interpreted as a certain minimum layer thickness. Temperature and crystallinity distributions are shown for some interesting configurations. Predictions of crystallization-wave velocities and minimum layer thicknesses are compared with experimental values for explosive crystallization in germanium.
    Keywords: Articles
    ISSN: 0021-8979
    E-ISSN: 1089-7550
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  • 8
    Language: English
    In: Journal of Adolescence, December 2013, Vol.36(6), pp.1165-1175
    Description: Fostering social and academic self-concepts are central educational goals. During mid-adolescence academic engagement and success seem to be devalued by peers and to be negatively associated with students' social standing. For this age group, is the development of a positive academic self-concept compatible with the development of a positive social self-concept? We investigated relations among academic self-concept, social self-concept, and academic achievement. 1282 students (47.60% female) participated in three-waves of measurement in Grade 5, 6, and 8. Earlier social self-concept of acceptance negatively predicted changes in academic self-concept over time while earlier social self-concept of assertion positively predicted changes in academic self-concept. There were no significant relations between social self-concepts and achievement but positive reciprocal relations between academic self-concept and achievement. Results indicate that fostering adolescents self-concept in social and academic domains are compatible goals. However, some students need support in managing the challenge to coordinate social and academic goals.
    Keywords: Academic Self-Concept ; Social Self-Concept ; Social Acceptance ; Social Assertion ; Adolescence ; Longitudinal Data ; Medicine ; Social Welfare & Social Work ; Psychology
    ISSN: 0140-1971
    E-ISSN: 1095-9254
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  • 9
    Language: English
    In: Organic letters, 18 May 2018, Vol.20(10), pp.3119-3123
    Description: The first Sc(OTf)-catalyzed dehydration of 2-hydroxy oxime ethers to generate benzylic stabilized 1-azaallyl cations, which are captured by 1,3-carbonyls, is described. A subsequent addition of primary amines in a sequential three-component reaction affords highly substituted and densely functionalized tetrahydroindeno[2,1- b]pyrroles as single diastereomers with up to quantitative yield. Thus, three new σ-bonds and two vicinal quaternary stereogenic centers are generated in a one-pot operation.
    ISSN: 15237060
    E-ISSN: 1523-7052
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  • 10
    Language: English
    In: Organic letters, 07 December 2018, Vol.20(23), pp.7576-7580
    Description: A highly straightforward route to enantiomerically highly enriched cis-2,3-dihydrobenzofurans has been achieved via addition of α-diazocarbonyl compounds to in situ generated o-QMs catalyzed by a chiral Brønsted acid. This catalytic strategy provides a direct access to 2,3-dihydrobenzofurans in high yields and with up to 91:9 dr and 99:1 er at ambient temperature. Moreover, a unique phenonium-type rearrangement accounts for product formation with an inverted 2,3-substitution pattern.
    ISSN: 15237060
    E-ISSN: 1523-7052
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