130,884 research outputs found
Automatic compensation system for impedance measurement
No full textThis paper deals with the realization of the four-pair terminal definition of impedance standards. A simple, though reliable, system is described that allows an automatic compensation of the voltage at the low potential port of impedance standards to be obtained. Such a system employs a commercial data acquisition board and a signal generator with adjustable-phase capability, which acts as the phase reference for the generator that feeds the impedance standard. A standard PC controls the whole system and implements the demodulation and the control algorithms. Preliminary tests have been performed in the frequency range of 50 Hz to 20 kHz with different kinds of impedance standards (resistive, inductive and capacitive), obtaining a residual voltage at the low potential port of less than 5 μV
Combinatorial generators for the cohomology of toric arrangements
No full textWe give a new combinatorial description of the cohomology ring structure of H & lowast; ( M (A); Z ) of the complement M (A) of a real complexified toric arrangement Ain (C & lowast;)d. C & lowast; ) d . In particular, we correct an error in the paper [4]. (c) 2024 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies
A locally adaptive statistical procedure (LAP) to identify differentially expressed chromosomal regions
No full textMotivation: The systematic integration of expression profiles and other types of gene information, such as chromosomal localization, ontological annotations and sequence characteristics, still represents a challenge in the gene expression arena. In particular, the analysis of transcriptional data in context of the physical location of genes in a genome appears promising in detecting chromosomal regions with transcriptional imbalances often characterizing cancer.Results: A computational tool named locally adaptive statistical procedure (LAP), which incorporates transcriptional data and structural information for the identification of differentially expressed chromosomal regions, is described. LAP accounts for variations in the distance between genes and in gene density by smoothing standard statistics on gene position before testing the significance of their differential levels of gene expression. The procedure smoothes parameters and computes p-values locally to account for the complex structure of the genome and to more precisely estimate the differential expression of chromosomal regions. The application of LAP to three independent sets of raw expression data allowed identifying differentially expressed regions that are directly involved in known chromosomal aberrations characteristic of tumors
Defining Which Patients Are at High Risk for Recurrence of Soft Tissue Sarcoma
No full textSeveral studies have investigated the prognosis of soft tissue sarcomas and the influence of a variety of factors, such as size, histology subtype, malignancy grade, site, margins, on overall survival, recurrence-free survival, incidence of local and distant spreading. The impact of genomic and expression profiling on long-term outcomes of patients with sarcomas has been also evaluated in order to fill the knowledge gap of this heterogeneous disease. Nomograms represent a prognostic tool that extends the standard staging systems on an individualized basis, taking into account tumor- and patient-related factors. They are used to assist the health provider and the patients in the decision-making process, for patient counseling, treatment decision-making, follow-up scheduling, and clinical trial eligibility determination. None of the available nomograms include molecular characterization of sarcomas. In the future, omics signatures might be incorporated into prognostic nomograms possibly improving their performance. In the present review, we focus on the complexity of prognostic and predictive factors for extremity and trunk wall as well as for retroperitoneal soft tissue sarcomas, while exploring the available prognostic models
Families of superelliptic curves, complex braid groups and generalized Dehn twists
No full textWe consider the universal family End of superelliptic curves: each curve Σnd in the family is a d-fold covering of the unit disk, totally ramified over aset P of n distinct points; Σnd↪End→Cn is a fiber bundle, where Cn is the configuration space of n distinct points. We find that End is the classifying space for the complex braid group of type B(d, d, n) and we compute a big part of the integral homology of End, including a complete calculation of the stable groups over finite fields by means of Poincaré series. The computation of the main part of the above homology reduces to the computation of the homology of the classical braid group with coefficients in the first homology group of Σnd, endowed with the monodromy action. While giving a geometric description of such monodromy of the above bundle, we introduce generalized 1d-twists, associated to each standard generator of the braid group, which reduce to standard Dehn twists for d = 2
The problem for the Artin group of type and its cohomology
No full textWe prove that the complement to the affine complex arrangement of type Bn is a K(π,1) space. We also compute the cohomology of the affine Artin group GBn (of type Bn) with coefficients in interesting local systems. In particular, we consider the module Q[q±1 , t±1], where the first n standard generators of GBn act by (−q)-multiplication while the last generator acts by (−t) multiplication. Such a representation generalizes the analogous 1-parameter representation related to the bundle structure over the complement to the discriminant hypersurface, endowed with the monodromy action of the associated Milnor fibre. The cohomology of GBn with trivial coefficients is derived from the previous one
Cohomology of Artin groups of type ~A_n, B_n and applications
No full textWe consider two natural embeddings between Artin groups: the group GÃn-1 of type Ãn-1 embeds into the group GBn of type Bn; GBn in turn embeds into the classical braid group Brn+1:=GAn of type An. The cohomologies of these groups are related, by standard results, in a precise way. By using techniques developed in previous papers, we give precise formulas (sketching the proofs) for the cohomology of GBn with coefficients over the module Q[q±1,t±1], where the action is (-q)–multiplication for the standard generators associated to the first n-1 nodes of the Dynkin diagram, while is (-t)–multiplication for the generator associated to the last node
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