1,991 research outputs found
A pluripotential theoretic framework for polynomial interpolation of vector-valued functions and differential forms
No full textWe consider the problem of uniform interpolation of functions with values in a complex inner product space of finite dimension. This problem can be cast within a modified weighted pluripotential theoretic framework. Indeed, in the proposed modification a vector valued weight is considered, allowing to partially extend the main asymptotic results holding for interpolation of scalar valued functions to the case of vector valued ones. As motivating example and main application we specialize our results to interpolation of differential forms by differential forms with polynomial coefficients
The numerical linear algebra of weights. Part I : from the spectral analysis to conditioning and preconditioning in the one-dimensional Laplacian case
No full textWeights are geometrical degrees of freedom that allow to generalize Lagrangian finite elements. They are defined through integrals over specific supports, well understood in terms of differential forms and integration, and lie within the framework of finite element exterior calculus. We adopt this formalism with the target of identifying supports that are appealing for a finite element approximation, describing weights in terms of a single parameter in the third- and fourth-order methods. To do so, we study the related parametric matrix-sequences, with the matrix order tending to infinity as the mesh size tends to zero. Using the generalized locally Toeplitz theory, we analyze the performance of weights-based finite elements on an elliptic operator. In particular, for degrees 3 and 4, we identify an optimal value for the weights location, which sits in a rather large interval where weights give rise to better conditioned stiffness matrices. With this at hand, we propose and test ad hoc preconditioners, in dependence of the discretization parameters and in connection with conjugate gradient method. The model problem we consider is a one-dimensional Laplacian, both with constant and non-constant coefficients. Numerical visualizations and experimental tests are reported and critically discussed, showing a confidence interval for the choice of the parameter
Progresso tecnologico nella produzione industriale di proteine da idrocarburi e loro qualità con particolare riguardo alla situazione italiana.
No full textStructure and expression of the negative growth factor mouse beta-galactoside binding protein gene.
No full textFollowing the identification of murine β-galactoside binding protein (mGBP) as an autocrine negative growth factor we have now isolated and characterized the genomic region spanning the mGBP gene and have determined the 5′ end of the transcript by primer extension, S1 mapping and mRNA sequence. The gene is found to be contained within 4 kilobases and composed of four exons of 79, 80, 171 and 197 nucleotides separated by three introns of 1200, 1600 and 193 nucleotides. The DNA region upstream of the 5′ end of the transcript contains canonical sequences for eukaryotic promoter elements including CAT and TATA boxes and several DNA motifs for potential transcription regulation. The gene is differentially expressed in a variety of normal tissues
Computing weights for high order Whitney edge elements
No full textThe interpolation of differential forms is a challenging problem that is getting increasing attention. The issue of finding unisolvent degrees of freedom to describe a differential form in terms of high-order Whitney forms is an active area of research nowadays. In this paper we deal with a family of such degrees of freedom, called weights, that fits with the physical and geometrical nature of the field to interpolate. These weights play the role of interpolation coefficients when reconstructing scalar/vector fields in terms of a set of selected multivariate polynomial forms. Weights are a generalization of the evaluations of a scalar function at a set of nodes in view of its reconstruction on multivariate polynomial bases. As in the nodal case, different sets of such weights are compared in terms of a Lebesgue constant. In this contribution, we briefly recall their definition and provide examples of algorithms in low dimension to compute their associated Lebesgue constant value. Insights to greater dimensions are offered as well
Preliminary studies on anti-inflammatory and analgesic activities of Salpichroa rhomboidea Miers extract.
No full text
Activation of the galectin-1 (L-14-I) gene from nonexpressing differentiated cells by fusion with undifferentiated and tumorigenic cells.
No full textExpression of the galectin-1 (L-14-I) gene, elevated in most differentiated and transformed cell lines, has been studied in cell hybrid systems. Fusion of L-14-I nonproducing rat liver differentiated FAO cells with dedifferentiated rat liver BRL3A cells leads to extinction of liver-specific gene expression while L-14-I mRNA levels remain high. Interspecific hybrids produced by fusion of tumorigenic human osteosarcoma 143TK- with FAO cells show loss of both differentiated functions and tumorigenic phenotype and activation of the FAO L-14-I alleles. Increased expression of rat L-14-I alleles was also observed in human osteosarcoma x rat thyroid cells transient heterokaryons. The data presented here show that expression of the L-14-I gene is subject to dominant positive control and that it correlates with loss of differentiation-specific functions, but it is independent from tumorigenicity. L-14-I activation in FAO cells is achieved by treatment with 5-azacytidine. This result suggests that DNA demethylation is responsible or a prerequisite for L-14-I activation in hybrids
- …
