Search results for "variable"
showing 10 items of 1674 documents
QCD effects andb-tagging at LEP I
1995
We analyze the impact of usingb-tagged samples in studying non-Abelian effects due to QCD ine + e − → 4jet events at √s=M z 0, using angular variable analyses and comparisons withe + e − → 3jetγ events. We find that QCD effects are largely enhanced inb-quark samples with respect to ‘unflavoured’ ones, where energy-ordering is used to distinguish between gluon and quark jets. We show that theb-quark mass influences the angular distributions significantly and should not be neglected.
Planar Mappings of Finite Distortion
2010
We review recent results on planar mappings of finite distortion. This class of mappings contains all analytic functions and quasiconformal mappings.
Distortion of quasiconformal maps in terms of the quasihyperbolic metric
2013
Abstract We extend a theorem of Gehring and Osgood from 1979–relating to the distortion of the quasihyperbolic metric by a quasiconformal mapping between Euclidean domains–to the setting of metric measure spaces of Q -bounded geometry. When the underlying target space is bounded, we require that the boundary of the image has at least two points. We show that even in the manifold setting, this additional assumption is necessary.
Quasihyperbolic boundary conditions and capacity: Hölder continuity of quasiconformal mappings
2001
We prove that quasiconformal maps onto domains which satisfy a suitable growth condition on the quasihyperbolic metric are uniformly continuous when the source domain is equipped with the internal metric. The obtained modulus of continuity and the growth assumption on the quasihyperbolic metric are shown to be essentially sharp. As a tool, we prove a new capacity estimate.
Evaluation of approaches for measuring taxonomic completeness of lake profundal macroinvertebrate assemblages
2011
Summary 1. Benthic macroinvertebrates (MI) are commonly used to assess freshwater ecosystems with the reference condition approach. Such assessments necessitate control for natural community variation, either by categorical typologies or by predictive models that have been widely and successfully developed for running water biota but not previously for lake profundal invertebrates. 2. We evaluated four modelling techniques [multivariate regression tree (MRT), limiting environmental differences, nonparametric multiplicative regression (NPMR) and River Invertebrate Prediction And Classification System (RIVPACS) and the operative Finnish lake typology for assessing taxonomic completeness (obse…
Unequal distribution of RT-PCR artifacts along the E1-E2 region of Hepatitis C virus.
2009
Although viral variability studies have focused traditionally on consensus sequences, the relevance of molecular clone sequences for studying viral evolution at the intra-host level is being increasingly recognized. However, for this approach to be reliable, RT-PCR artifacts do not have to contribute excessively to the observed variability. Molecular clone sequences were obtained from an in vitro transcript to estimate the maximum error rate associated to RT-PCR for the Hepatitis C virus (HCV) E1-E2 region. On average, the frequency of RT-PCR errors was one order of magnitude lower than the level of intra-host genetic variability observed in samples from an HCV outbreak. However, RT-PCR err…
Relationship between erythemal UV and broadband solar irradiation at high altitude in Northwestern Argentina
2018
An analysis of the broadband solar irradiation, IT, and the erythemal UV irradiation, IUVER, has been performed using the measurements made from 2013 to 2015 at three sites located at altitudes over 1000 m a.s.l. In Northwestern Argentina (Salta, El Rosal, and Tolar Grande). The main objective of this paper is to determine a relationship between IT and IUVER, which would allow to estimate IUVER from IT in places with few IUVER measurements available, and especially in those where is important to establish adequate photoprotection measures given their dense population and location at high altitude. The relationship between the daily values of IUVER and IT has been fitted to a linear regressi…
Backward solution of PV nodes in radial distribution networks
2009
In this paper an iterative backward methodology to solve radial distribution networks with fixed voltage (PV) nodes and with constant power loads or mixed loads (with at least one component with constant power) is proposed. The method developed, although deriving conceptually from the backward/forward (b/f) methodology, presents only the backward phase in which all the network variables are evaluated. In themethods developed up until nowfor the solution of such systems, PV nodes are taken into account at the end of each iteration by evaluating, based on the known quantities of the network, the unknowns associated with PV nodes. In the methodology developed here the unknowns relevant to PV n…
A Multiresolution Approach Based on MRF and Bak–Sneppen Models for Image Segmentation
2006
The two major Markov Random Fields (MRF) based algorithms for image segmentation are the Simulated Annealing (SA) and Iterated Conditional Modes (ICM). In practice, compared to the SA, the ICM provides reasonable segmentation and shows robust behavior in most of the cases. However, the ICM strongly depends on the initialization phase. In this paper, we combine Bak-Sneppen model and Markov Random Fields to define a new image segmentation approach. We introduce a multiresolution technique in order to speed up the segmentation process and to improve the restoration process. Image pixels are viewed as lattice species of Bak-Sneppen model. The a-posteriori probability corresponds to a local fitn…
Inferring networks from high-dimensional data with mixed variables
2014
We present two methodologies to deal with high-dimensional data with mixed variables, the strongly decomposable graphical model and the regression-type graphical model. The first model is used to infer conditional independence graphs. The latter model is applied to compute the relative importance or contribution of each predictor to the response variables. Recently, penalized likelihood approaches have also been proposed to estimate graph structures. In a simulation study, we compare the performance of the strongly decomposable graphical model and the graphical lasso in terms of graph recovering. Five different graph structures are used to simulate the data: the banded graph, the cluster gr…