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  • *Lymphocyte Activation
  • Engineering
  • Nuclear reactions
  • 1995-1999  (7)
  • 1
    Digitale Medien
    Digitale Medien
    A SPACE-TIME FINITE ELEMENT METHOD FOR THE EXTERIOR STRUCTURAL ACOUSTICS PROBLEM: TIME-DEPENDENT RADIATION BOUNDARY CONDITIONS IN TWO SPACE DIMENSIONS (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 1635-1657 
    Details
    ISSN: 0029-5981
    Schlagwort(e): finite element method ; radiation boundary conditions ; absorbing boundary conditions ; discontinuous Galerkin method ; structural acoustics ; wave equation ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A time-discontinuous Galerkin space-time finite element method is formulated for the exterior structural acoustics problem in two space dimensions. The problem is posed over a bounded computational domain with local time-dependent radiation (absorbing) boundary conditions applied to the fluid truncation boundary. Absorbing boundary conditions are incorporated as ‘natural’ boundary conditions in the space-time variational equation, i.e. they are enforced weakly in both space and time. Following Bayliss and Turkel, time-dependent radiation boundary conditions for the two-dimensional wave equation are developed from an asymptotic approximation to the exact solution in the frequency domain expressed in negative powers of a non-dimensional wavenumber. In this paper, we undertake a brief development of the time-dependent radiation boundary conditions, establishing their relationship to the exact impedance (Dirichlet-to-Neumann map) for the acoustic fluid, and characterize their accuracy when implemented in our space-time finite element formulation for transient structural acoustics. Stability estimates are reported together with an analysis of the positive form of the matrix problem emanating from the space-time variational equations for the coupled fluid-structure system. Several numerical simulations of transient radiation and scattering in two space dimensions are presented to demonstrate the effectiveness of the space-time method.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
  • 2
    Digitale Medien
    Digitale Medien
    A Galerkin least-squares finite element method for the two-dimensional Helmholtz equation (1995)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 38 (1995), S. 371-397 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Helmholtz equation ; least squares ; Galerkin method ; Fourier analysis ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: In this paper a Galerkin least-squares (GLS) finite element method, in which residuals in least-squares form are added to the standard Galerkin variational equation, is developed to solve the Helmholtz equation in two dimensions. An important feature of GLS methods is the introduction of a local mesh parameter that may be designed to provide accurate solutions with relatively coarse meshes. Previous work has accomplished this for the one-dimensional Helmholtz equation using dispersion analysis. In this paper, the selection of the GLS mesh parameter for two dimensions is considered, and leads to elements that exhibit improved phase accuracy. For any given direction of wave propagation, an optimal GLS mesh parameter is determined using two-dimensional Fourier analysis. In general problems, the direction of wave propagation will not be known a priori. In this case, an optimal GLS parameter is found which reduces phase error for all possible wave vector orientations over elements. The optimal GLS parameters are derived for both consistent and lumped mass approximations. Several numerical examples are given and the results compared with those obtained from the Galerkin method. The extension of GLS to higher-order quadratic interpolations is also presented.
    Zusätzliches Material: 20 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620380303
    Standort Signatur Erwartet Verfügbarkeit
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    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Application of the full approximation storage method to the numerical simulation of two-dimensional steady incompressible viscous multiphase flows (1998)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 28 (1998), S. 1217-1239 
    Details
    ISSN: 0271-2091
    Schlagwort(e): multiphase ; multifluid ; multigrid ; FAS ; local coupled solver ; Engineering ; Numerical Methods and Modeling
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Notizen: In recent years multigrid algorithms have been applied to increasingly difficult systems of partial differential equations and major improvements in both speed of convergence and robustness have been achieved. Problems involving several interacting fluids are of great interest in many industrial applications, especially in the process and petro-chemical sectors. However, the multifluid version of the Navier-Stokes equations is extremely complex and represents a challenge to advanced numerical algorithms. In this paper, we describe an extension of the full approximation storage (FAS) multigrid algorithm to the multifluid equations. A number of special issues had to be addressed. The first was the development of a customised, non-linear, coupled relaxation scheme for the smoothing step. Automatic differentiation was used to facilitate the coding of a robust, globally convergent quasi-Newton method. It was also necessary to use special inter-grid transfer operators to maintain the realisability of the solution. Algorithmic details are given and solutions for a series of test problems are compared with those from a widely validated, commercial code. The new approach has proved to be robust; it achieves convergence without resorting to specialised initialisation methods. Moreover, even though the rate of convergence is complex, the method has achieved very good reduction factors: typically five orders of magnitude in 50 cycles. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    NUMERICAL UNCERTAINTIES IN TRANSONIC FLOW CALCULATIONS FOR AEROFOILS WITH BLUNT TRAILING EDGES (1997)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 24 (1997), S. 355-373 
    Details
    ISSN: 0271-2091
    Schlagwort(e): computational fluid dynamics ; transonic airfoils ; numerical uncertainty ; Engineering ; Numerical Methods and Modeling
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Notizen: Numerical uncertainties are quantified for calculations of transonic flow around a divergent trailing edge (DTE) supercritical aerofoil. The Reynolds-averaged Navier-Stokes equations are solved using a linearized block implicit solution procedure and mixing-length turbulence model. This procedure has reproduced measurements around supercritical aerofoils with blunt trailing edges that have shock, boundary layer and separated regions. The present effort quantifies numerical uncertainty in these calculations using grid convergence indices which are calculated from aerodynamic coefficients, shock location, dimensions of the recirculating region in the wake of the blunt trailing edge and distributions of surface pressure coefficients. The grid convergence index is almost uniform around the aerofoil, except in the shock region and at the point where turbulence transition was fixed. The grid convergence index indicates good convergence for lift but only fair convergence for moment and drag and also confirms that drag calculations are more sensitive to numerical error. © 1997 by John Wiley and Sons, Ltd.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
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    Unbekannt
    Molecular basis of T cell inactivation by CTLA-4 (1998)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1998-12-18
    Beschreibung: CTLA-4, a negative regulator of T cell function, was found to associate with the T cell receptor (TCR) complex zeta chain in primary T cells. The association of TCRzeta with CTLA-4, reconstituted in 293 transfectants, was enhanced by p56(lck)-induced tyrosine phosphorylation. Coexpression of the CTLA-4-associated tyrosine phosphatase, SHP-2, resulted in dephosphorylation of TCRzeta bound to CTLA-4 and abolished the p56(lck)-inducible TCRzeta-CTLA-4 interaction. Thus, CTLA-4 inhibits TCR signal transduction by binding to TCRzeta and inhibiting tyrosine phosphorylation after T cell activation. These findings have broad implications for the negative regulation of T cell function and T cell tolerance.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lee, K M -- Chuang, E -- Griffin, M -- Khattri, R -- Hong, D K -- Zhang, W -- Straus, D -- Samelson, L E -- Thompson, C B -- Bluestone, J A -- P01 AI35294-6/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1998 Dec 18;282(5397):2263-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ben May Institute for Cancer Research, and Committee on Immunology, University of Chicago, Chicago, IL 60637, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9856951" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Abatacept ; Animals ; Antigens, CD ; Antigens, Differentiation/*metabolism ; CTLA-4 Antigen ; Cell Line ; Cells, Cultured ; Humans ; *Immunoconjugates ; Intracellular Signaling Peptides and Proteins ; *Lymphocyte Activation ; Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/genetics/metabolism ; Membrane Proteins/*metabolism ; Mice ; Mice, Inbred BALB C ; Models, Immunological ; Phosphorylation ; Phosphotyrosine/metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 11 ; Protein Tyrosine Phosphatase, Non-Receptor Type 6 ; Protein Tyrosine Phosphatases/genetics/metabolism ; Receptors, Antigen, T-Cell/*metabolism ; Recombinant Fusion Proteins/metabolism ; SH2 Domain-Containing Protein Tyrosine Phosphatases ; *Signal Transduction ; T-Lymphocytes/*immunology ; Transfection ; src Homology Domains
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
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    Unbekannt
    Lymphoproliferative disorders with early lethality in mice deficient in Ctla-4 (1995)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1995-11-10
    Beschreibung: The role of the cell-surface molecule CTLA-4 in the regulation of T cell activation has been controversial. Here, lymph nodes and spleens of CTLA-4-deficient mice accumulated T cell blasts with up-regulated activation markers. These blast cells also infiltrated liver, heart, lung, and pancreas tissue, and amounts of serum immunoglobulin were elevated. The mice invariably became moribund by 3 to 4 weeks of age. Although CTLA-4-deficient T cells proliferated spontaneously and strongly when stimulated through the T cell receptor, they were sensitive to cell death induced by cross-linking of the Fas receptor and by gamma irradiation. Thus, CTLA-4 acts as a negative regulator of T cell activation and is vital for the control of lymphocyte homeostasis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Waterhouse, P -- Penninger, J M -- Timms, E -- Wakeham, A -- Shahinian, A -- Lee, K P -- Thompson, C B -- Griesser, H -- Mak, T W -- New York, N.Y. -- Science. 1995 Nov 10;270(5238):985-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Immunology, University of Toronto, Ontario, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7481803" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Abatacept ; Animals ; Antigens, CD/analysis ; Antigens, CD95/metabolism ; Antigens, Differentiation/genetics/*physiology ; Apoptosis ; B-Lymphocytes/immunology ; CTLA-4 Antigen ; Cells, Cultured ; Concanavalin A/pharmacology ; Female ; Gamma Rays ; Gene Targeting ; Homeostasis ; *Immunoconjugates ; Immunoglobulins/blood ; Immunophenotyping ; Lymph Nodes/immunology/pathology ; *Lymphocyte Activation ; Lymphoproliferative Disorders/*immunology/pathology ; Male ; Mice ; Mice, Inbred C57BL ; Spleen/immunology/pathology ; T-Lymphocytes/*immunology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    facet.materialart.
    Unbekannt
    Hierarchical control of lymphocyte survival (1996)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1996-10-04
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Boise, L H -- Thompson, C B -- New York, N.Y. -- Science. 1996 Oct 4;274(5284):67-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Gwen Knapp Center for Lupus and Immunology Research, Howard Hughes Medical Institute, University of Chicago, Illinois 60637-5420, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8848725" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Antigens/immunology ; Antigens, CD95/physiology ; *Apoptosis ; *Cell Survival ; Cytokines/physiology ; *Lymphocyte Activation ; Lymphocytes/*cytology/*immunology ; Proto-Oncogene Proteins/physiology ; Proto-Oncogene Proteins c-bcl-2 ; Receptors, Antigen/physiology ; Receptors, Cell Surface/physiology ; Signal Transduction
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
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