278 research outputs found
Improving alpha_QED(M_Z^2) and the charm mass by analytic continuation
The standard determination of the QED coupling on the Z pole is performed
using the latest available data for R. The direct application of analytic
continuation techniques is found not to improve the accuracy of the value of
\alpha(M_Z^2). However they help to resolve an ambiguity in the values of R in
the energy region \sqrt{s} < 2 GeV, which, in turn, reduces the uncertainty in
\alpha(M_Z^2). Moreover, they provide a sensitive determination of the mass of
the charm quark. The favoured solution, which uses the inclusive data for R for
\sqrt{s} < 2 GeV, has a pole mass m_c = 1.33-1.40 GeV and \alpha^{-1}(M_Z^2) =
128.972 +/- 0.026; whereas if the sum of the exclusive channels is used to
determine R in this region, we find \alpha^{-1}(M_Z^2) = 128.941 +/- 0.029.Comment: LaTeX, 23 pages, 7 eps figures, typos removed, accepted by Eur. Phys.
J.
Electrostatic Field Classifier for Deficient Data
This paper investigates the suitability of recently developed models based on the physical
field phenomena for classification problems with incomplete datasets. An original approach
to exploiting incomplete training data with missing features and labels, involving extensive use
of electrostatic charge analogy, has been proposed. Classification of incomplete patterns has been
investigated using a local dimensionality reduction technique, which aims at exploiting all available
information rather than trying to estimate the missing values. The performance of all proposed
methods has been tested on a number of benchmark datasets for a wide range of missing data scenarios
and compared to the performance of some standard techniques. Several modifications of the
original electrostatic field classifier aiming at improving speed and robustness in higher dimensional
spaces are also discussed
Expression of aldehyde dehydrogenase family 1, member A3 in glycogen trophoblast cells of the murine placenta
Introduction: Retinoic acid (RA) signaling is a well known regulator of trophoblast differentiation and placental development, and maternal decidual cells are recognized as the source of much of this RA. We explored possible trophoblast-derived sources of RA by examining the expression of RA synthesis enzymes in the developing mouse placenta, as well as addressed potential sites of RA action by examining the ontogeny of gene expression for other RA metabolizing and receptor genes. Furthermore, we investigated the effects of endogenous RA production on trophoblast differentiation
Charge Oscillations in Debye-Hueckel Theory
The recent generalized Debye-Hueckel (GDH) theory is applied to the
calculation of the charge-charge correlation function G_{ZZ}(r). The resulting
expression satisfies both (i) the charge neutrality condition and (ii) the
Stillinger-Lovett second-moment condition for all T and rho_N, the overall ion
density, and (iii) exhibits charge oscillations for densities above a "Kirkwood
line" in the (rho_N,T) plane. This corrects the normally assumed DH
correlations, and, when combined with the GDH analysis of the density
correlations, leaves the GDH theory as the only complete description of ionic
correlation functions, as judged by (i)-(iii), (iv) exact low-density (rho_N,T)
variation, and (v) reasonable behavior near criticality.Comment: 6 pages, EuroPhys.sty (now available on archive), 1 eps figur
Prior specification in Bayesian occupancy modelling improves analysis of species occurrence data
Multi-species biodiversity indicators are increasingly used to assess progress towards the 2020 ‘Aichi’ targets of the Convention on Biological Diversity. However, most multi-species indicators are biased towards a few well-studied taxa for which suitable abundance data are available. Consequently, many taxonomic groups are poorly represented in current measures of biodiversity change, particularly invertebrates. Alternative data sources, including opportunistic occurrence data, when analysed appropriately, can provide robust estimates of occurrence over time and increase the taxonomic coverage of such measures of population change. Occupancy modelling has been shown to produce robust estimates of species occurrence and trends through time. So far, this approach has concentrated on well-recorded taxa and performs poorly where recording intensity is low. Here, we show that the use of weakly informative priors in a Bayesian occupancy model framework greatly improves the precision of occurrence estimates associated with current model formulations when analysing low-intensity occurrence data, although estimated trends can be sensitive to the choice of prior when data are extremely sparse at either end of the recording period. Specifically, three variations of a Bayesian occupancy model, each with a different focus on information sharing among years, were compared using British ant data from the Bees, Wasps and Ants Recording Society and tested in a simulation experiment. Overall, the random walk model, which allows the sharing of information between the current and previous year, showed improved precision and low bias when estimating species occurrence and trends. The use of the model formulation described here will enable a greater range of datasets to be analysed, covering more taxa, which will significantly increase taxonomic representation of measures of biodiversity change
Alcohol exposure impairs trophoblast survival and alters subtype-specific gene expression in vitro
Maternal alcohol consumption is common prior to pregnancy recognition and in the rat results in altered placental development and fetal growth restriction. To assess the effect of ethanol (EtOH) exposure on the differentiation of trophoblast stem (TS) cells, mouse TS lines were differentiated in vitro for 6 days in 0%, 0.2% or 1% EtOH. This reduced both trophoblast survival and expression of labyrinth and junctional zone trophoblast subtype-specific genes. This suggests that fetal growth restriction and altered placental development associated with maternal alcohol consumption in the periconceptional period could be mediated in part by direct effects on trophoblast development. (C) 2016 Elsevier Ltd. All rights reserved
Critical Realism and Statistical Methods: A Response to Nash
This article offers a defence of critical realism in the face of objections Nash (2005) makes to it in a recent edition of this journal. It is argued that critical and scientific realisms are closely related and that both are opposed to statistical positivism. However, the suggestion is made that scientific realism retains (from statistical positivism) a number of elements that result in misleading accounts of social processes and events: indicators are used which do not reflect the close relationship between structure and agency; indicators refer to reified and not real properties of both structures and agents; and indicators do not refer to causal properties of objects and entities. In order to develop a narrative of causal processes, as Nash argues researchers should, then some adjustments need to be made to the principles that underpin scientific realism
Correlation functions in ionic liquid at coexistence with ionic crystal. Results of the Brazovskii-type field theory
Correlation functions in the restricted primitive model are calculated within
a field-theoretic approach in the one-loop self-consistent Hartree
approximation. The correlation functions exhibit damped oscillatory behavior as
found before in the Gaussian approximation [Ciach at. al., J. Chem. Phys. {\bf
118}, 3702 (2003)]. The fluctuation contribution leads to a renormalization of
both the amplitude and the decay length of the correlation functions. The
renormalized quantities show qualitatively different behavior than their
mean-field (MF) counterparts. While the amplitude and the decay length both
diverge in MF when the -line is approached, the renormalized
quantities remain of order of unity in the same dimensionless units down to the
coexistence with the ionic crystal. Along the line of the phase transition the
decay length and the period of oscillations are independent of density, and
their values in units of the diameter of the ions are
and respectively.Comment: 21 pages including 9 figure
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