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  • 1
    Publication Date: 2012-07-10
    Description: The aim of this paper is to analyse a numerical method to solve transient eddy current problems with input current intensities as data, formulated in terms of the magnetic field in a bounded domain including conductors and dielectrics. To this end, we introduce a time-dependent weak formulation and prove its well-posedness. We propose a finite element method for space discretization based on the Nédélec edge elements on tetrahedral meshes, for which we obtain error estimates. Then we introduce a backward Euler scheme for time discretization and prove error estimates for the fully discrete problem, too. Furthermore, a magnetic scalar potential is introduced to deal with the curl-free condition in the dielectric domain, which leads to an important saving in computational effort. Finally, the method is applied to solve two problems: a test with a known analytical solution and an application to electromagnetic forming.
    Print ISSN: 0272-4979
    Electronic ISSN: 1464-3642
    Topics: Mathematics
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  • 2
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0163-7827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2019
    Description: Abstract Ni is an essential cofactor in NiFe‐uptake hydrogenase, an enzyme regulating H2 metabolism in diazotrophic cyanobacteria, the major H2 producers in the surface ocean globally. Here, we investigated the effect of Ni supply on H2 production and N2 fixation by using a model marine cyanobacterial diazotroph, Cyanothece. By mediating total dissolved Ni concentrations from 100 to 0.03 nmol L−1 in a trace metal‐defined culture medium, we demonstrated that Ni deficiency results in H2 accumulation, coupled with decreasing Ni quotas, growth rates, and occasionally relatively low N2 fixation rates. These results indicate that Ni deficiency limits the growth of the Cyanothece to some extent, considerably decreases H2 uptake by hydrogenase and leads to H2 accumulation and N2 fixation variation in the diazotroph. The findings show that Ni availability is a critical factor on controlling H2 production and N2 fixation in marine diazotrophic cyanobacteria. The information of Ni bioavailability for diazotrophic cyanobacteria is thus essential to evaluate the importance of Ni for H2 cycling and N2 fixation in oceanic surface waters.
    Print ISSN: 0024-3590
    Electronic ISSN: 1939-5590
    Topics: Biology , Geosciences , Physics
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  • 5
    Publication Date: 2019
    Description: Abstract Catchment travel times integrate the multitude of hydrological flow processes and provide insights into catchment functioning. StorAge Selection (SAS) functions describe how residence times of water in storage are related to travel times of water in catchment outflows. As such, SAS functions are useful to summarize transport processes in catchments and are ideal to simulate catchment outflows and the concentrations of various solutes and tracers. Recent studies suggested that using one probability distribution function (pdf) for SAS functions may not account for all transport processes in various hydrological systems. In this study we introduced a composite streamflow SAS function defined as a weighted sum of several pdfs (called components), using a uniform pdf for the youngest water and two gamma pdfs for the oldest water. The novel parameterization of this SAS function is nonlinear with respect to catchment storage and to a proxy of storage variations. This composite streamflow SAS function was needed to obtain realistic simulations of the complex high resolution (sub‐daily) stream deuterium (δ2H) dynamics measured for 2 years in the Weierbach, a forested headwater catchment in Luxembourg, whereas various SAS functions using only one component (i.e. pdf) failed. The three components of the composite streamflow SAS function confirmed the superposition of streamflow generation mechanisms with contrasting travel times suggested by previous experimental and modeling studies. Our work suggests that in some catchments, composite SAS functions may offer a more realistic perspective on transport processes derived from high resolution tracer data than simpler SAS functions.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
    Publication Date: 2014-06-21
    Description: ABSTRACT It is well known how mountains play a crucial role in the climate system and have very particular climate features compared to other regions. Sierra de Guadarrama is a part of the Iberian Peninsula Central System (Spain), a mountain range located in the center of an extensive plateau, dominated by a continental Mediterranean climate but under a strong Atlantic influence. This range provides fresh water to the different settlements in its vicinity, providing enough water resources to several millions of inhabitants, crop fields, industries and the city of Madrid, the capital of Spain. Nevertheless, there is no work studying the role of the synoptic scale in relation to the precipitation in this mountain range. To tackle this problem, this work calculates water vapour flux patterns (WVFPs) using total column water vapour flux as a predictor field due to the close relation between this parameter and the precipitation in mountainous areas. A clustering analysis on the first three principal components of the predictor field was performed and seven differentiated WVFPs were found using a cost function considering local precipitation data for optimum number of cluster determination. Then, an analysis is made for each component in terms of synoptic relation with other fields and well-known broader teleconnection patterns. Finally, an analysis in terms of their contribution to total precipitation, mean rain intensity and probability of precipitation is made. This work is expected to bring new light on the knowledge of precipitation climatology over this crucial and still not very well-known area, and it is a solid step for future precipitation modelling tools validation that combined with reliable measurements will allow to produce realistic precipitation assessments and forecasts in order to improve the hydrological management of this complex area.
    Print ISSN: 0899-8418
    Electronic ISSN: 1097-0088
    Topics: Geosciences , Physics
    Published by Wiley
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  • 7
    Publication Date: 2015-02-10
    Description: The crystallization of hexagonal NdCO 3 OH through hydrothermal synthesis carried out at slow (reaching the desired temperature within 100 min) and quick (50 min) rates of heating but at variable temperatures (165–220°C) are reported here. The formation of NdCO 3 OH occurs via the crystallization of an amorphous precursor. Both the precursor and the crystalline NdCO 3 OH were characterized by X-ray diffraction, infrared spectroscopy and high-resolution electron microscopy. The mechanism of crystallization is very dependent on the experimental conditions (rate of heating and temperature treatment). With increasing temperature, the habit of NdCO 3 OH crystals changes progressively to more complex spherulitic or dendritic morphologies. The development of these crystal morphologies is suggested here to be controlled by the level at which supersaturation was reached in the aqueous solution during the breakdown of the amorphous precursor. At the highest temperature (220°C) and during rapid heating (50 min) the amorphous precursor breaks down rapidly and the fast supersaturation promotes spherulitic growth. At the lowest temperature (165°C) and slow heating (100 min), however, the supersaturation levels are approached more slowly than required for spherulitic growth, and thus more regular, previously unseen, triangular pyramidal shapes form.
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
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  • 8
    Publication Date: 2015-01-16
    Description: BioModels ( http://www.ebi.ac.uk/biomodels/ ) is a repository of mathematical models of biological processes. A large set of models is curated to verify both correspondence to the biological process that the model seeks to represent, and reproducibility of the simulation results as described in the corresponding peer-reviewed publication. Many models submitted to the database are annotated, cross-referencing its components to external resources such as database records, and terms from controlled vocabularies and ontologies. BioModels comprises two main branches: one is composed of models derived from literature, while the second is generated through automated processes. BioModels currently hosts over 1200 models derived directly from the literature, as well as in excess of 140 000 models automatically generated from pathway resources. This represents an approximate 60-fold growth for literature-based model numbers alone, since BioModels’ first release a decade ago. This article describes updates to the resource over this period, which include changes to the user interface, the annotation profiles of models in the curation pipeline, major infrastructure changes, ability to perform online simulations and the availability of model content in Linked Data form. We also outline planned improvements to cope with a diverse array of new challenges.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 9
    Publication Date: 2015-03-11
    Description: We have investigated in detail the material, optical, and lasing properties of innovative GaInSb/AlInSb composite quantum wells (CQWs). The CQWs are confined by AlGaAsSb barrier layers, and a monolayer-thin AlInSb barrier layer has been inserted within the GaInSb QWs in order to achieve lasing emission within the telecom window. High-resolution X-ray diffraction, transmission electron microscopy, and photoluminescence spectroscopies reveal high structural quality of the samples. Inserting AlInSb layers allows wider QWs, and thus higher gain-material volume and CQW/optical mode overlap. This translates into better laser performances. Near room temperature, a threshold current of 85 mA and an output power of ∼30 mW/uncoated-facet under continuous wave operation are demonstrated at 1.55  μ m with 10  μ m × 1 mm laser diodes.
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 10
    Publication Date: 2004-10-16
    Description: Topical agents, such as microbicides, that can protect against human immunodeficiency virus (HIV) transmission are urgently needed. Using a chimeric simian/human immunodeficiency virus (SHIV SF162), which is tropic for the chemokine receptor CCR5, we report that topical application of high doses of PSC-RANTES, an amino terminus-modified analog of the chemokine RANTES, provided potent protection against vaginal challenge in rhesus macaques. These experimental findings have potentially important implications for understanding vaginal transmission of HIV and the design of strategies for its prevention.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lederman, Michael M -- Veazey, Ronald S -- Offord, Robin -- Mosier, Donald E -- Dufour, Jason -- Mefford, Megan -- Piatak, Michael Jr -- Lifson, Jeffrey D -- Salkowitz, Janelle R -- Rodriguez, Benigno -- Blauvelt, Andrew -- Hartley, Oliver -- AI 36219/AI/NIAID NIH HHS/ -- AI 51649/AI/NIAID NIH HHS/ -- N01-CO-124000/CO/NCI NIH HHS/ -- New York, N.Y. -- Science. 2004 Oct 15;306(5695):485-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, Case Western Reserve University, University Hospitals, 2061 Cornell Road, Cleveland, OH 44106, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15486300" target="_blank"〉PubMed〈/a〉
    Keywords: Administration, Intravaginal ; Animals ; Anti-HIV Agents/administration & dosage/*therapeutic use ; Anti-Infective Agents, Local/administration & dosage/*therapeutic use ; Antibodies, Viral/blood ; *CCR5 Receptor Antagonists ; Chemokine CCL5/administration & dosage/*analogs & derivatives/*therapeutic use ; Dose-Response Relationship, Drug ; Drug Evaluation, Preclinical ; Female ; HIV Infections/*prevention & control/transmission ; HIV-1/drug effects ; Macaca mulatta ; Receptors, CCR5/metabolism ; Simian Acquired Immunodeficiency Syndrome/*prevention & control/transmission ; Simian Immunodeficiency Virus/drug effects/immunology ; Vagina/*virology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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