487 research outputs found
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
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What do coronary artery disease patients think about their treatments? An assessment of patients' treatment representations
This article investigates patients' beliefs about the intervention offered to manage their illness. Coronary artery disease (CAD) patients, 70 of whom were undergoing medication, 71 to undergo angioplasty and 73 to undergo surgery, completed a 58-item questionnaire regarding their treatment beliefs. Responses were subject to principal components analysis, which indicated four factors accounting for 36.7 per cent of the variance. After excluding extraneous items, the final questionnaire consisted of 27 items, clustered around four components: treatment-value, treatment-concerns, decision-satisfaction and cure. A coherent set of subscale inter-correlations and ANCOVAs examining treatment group differences on these sub-scales showed a logical, explicable pattern of group differences reflecting the distinctive natures of each treatment and demonstrated discriminant validity. Correlations with other scales provided evidence of construct validity
Prevalencia y factores de riesgo de úlceras por presión
ObjetivoConocer la prevalencia de úlceras por presión (UPP) en pacientes incapacitados de una Zona Básica de Salud (ZBS) y caracterizar los factores de riesgo asociados a su aparición.DiseñoEstudio transversal observacional.EmplazamientoZBS Rincón de la Victoria (Málaga).ParticipantesPacientes incluidos en el Programa de Incapacitados (n = 178), de la ZBS, residentes en su domicilio o en una residencia geriátrica.MedicionesCuestionario específico con variables sociodemográficas y de salud. Para la valoración de factores de riesgo asociados con la formación de UPP, se utilizó la Escala de Norton Modificada (ENM). La variable resultado de interés fue la presencia o ausencia de UPP, localización y grado. El denominador para el cálculo de la prevalencia ha sido el total de pacientes valorados.ResultadosLa prevalencia fue del 12,9%. La característica sociodemográfica más significativa asociada con la presencia de úlceras en estos pacientes fue el nivel de instrucción del cuidador. Se constata asociación de determinadas variables del estado de salud del paciente con aparición de UPP.ConclusionesLos resultados alertan a la necesidad de la realización de protocolos diagnósticos y de intervención comunitaria para reducir la presentación de UPP en pacientes incapacitados que viven en la comunidad.ObjectivesTo study prevalence of pressure ulcers among functionally impaired patients in the community and evaluate risk factors associated with the development of pressure ulcers in these patients.DesignCross-sectional, observational study.SettingCommunity dwellers served by the Primary Health Care Area of Rincón de la Victoria in Málaga.ParticipantsAll patients included in the «Impaired Patient Programme» (n=178).MethodsA questionnaire was developed to ascertain demographic and health characteristics. Risk factors were evaluated with the Modified Norton Scale. The outcome variable of interest was presence or absence of pressure ulcers, their location and grade. The denominator used for the calculation of the prevalence was the total of evaluated patients.ResultsPrevalence of pressure ulcers in our Basic Health Area was 12.9%. The most important sociodemographic characteristic associated with the presence of pressure ulcers in these patients was the educational attainment of the caregiver. Health varaibles of the patient were also associated with the risk of developing ulcers.ConclusionsResults indicate the need of diagnostic protocols with standardised instruments and prevention plans to reduce pressure ulcers in the community. Longitudinal studies are needed to evaluate interventions in this area
Cold Nuclear Matter In Holographic QCD
We study the Sakai-Sugimoto model of holographic QCD at zero temperature and
finite chemical potential. We find that as the baryon chemical potential is
increased above a critical value, there is a phase transition to a nuclear
matter phase characterized by a condensate of instantons on the probe D-branes
in the string theory dual. As a result of electrostatic interactions between
the instantons, this condensate expands towards the UV when the chemical
potential is increased, giving a holographic version of the expansion of the
Fermi surface. We argue based on properties of instantons that the nuclear
matter phase is necessarily inhomogeneous to arbitrarily high density. This
suggests an explanation of the "chiral density wave" instability of the quark
Fermi surface in large N_c QCD at asymptotically large chemical potential. We
study properties of the nuclear matter phase as a function of chemical
potential beyond the transition and argue in particular that the model can be
used to make a semi-quantitative prediction of the binding energy per nucleon
for nuclear matter in ordinary QCD.Comment: 31 pages, LaTeX, 1 figure, v2: some formulae corrected, qualitative
results unchange
Review of AdS/CFT Integrability, Chapter II.2: Quantum Strings in AdS5xS5
We review the semiclassical analysis of strings in AdS5xS5 with a focus on
the relationship to the underlying integrable structures. We discuss the
perturbative calculation of energies for strings with large charges, using the
folded string spinning in an AdS3 subset of AdS5 as our main example.
Furthermore, we review the perturbative light-cone quantization of the string
theory and the calculation of the worldsheet S-matrix.Comment: 20 pages, see also overview article arXiv:1012.3982, v2: references
to other chapters update
Distribution-free multiple imputation in an interaction matrix through singular value decomposition
Missing values: sparse inverse covariance estimation and an extension to sparse regression
We propose an l1-regularized likelihood method for estimating the inverse
covariance matrix in the high-dimensional multivariate normal model in presence
of missing data. Our method is based on the assumption that the data are
missing at random (MAR) which entails also the completely missing at random
case. The implementation of the method is non-trivial as the observed negative
log-likelihood generally is a complicated and non-convex function. We propose
an efficient EM algorithm for optimization with provable numerical convergence
properties. Furthermore, we extend the methodology to handle missing values in
a sparse regression context. We demonstrate both methods on simulated and real
data.Comment: The final publication is available at http://www.springerlink.co
Increased numbers of oligodendrocyte lineage cells in the optic nerves of cerebroside sulfotransferase knockout mice
Sulfatide is a myelin glycolipid that functions in the formation of paranodal axo-glial junctions in vivo and in the regulation of oligodendrocyte differentiation in vitro. Cerebroside sulfotransferase (CST) catalyzes the production of two sulfated glycolipids, sulfatide and proligodendroblast antigen, in oligodendrocyte lineage cells. Recent studies have demonstrated significant increases in oligodendrocytes from the myelination stage through adulthood in brain and spinal cord under CST-deficient conditions. However, whether these result from excess migration or in situ proliferation during development is undetermined. In the present study, CST-deficient optic nerves were used to examine migration and proliferation of oligodendrocyte precursor cells (OPCs) under sulfated glycolipid-deficient conditions. In adults, more NG2-positive OPCs and fully differentiated cells were observed. In developing optic nerves, the number of cells at the leading edge of migration was similar in CST-deficient and wild-type mice. However, BrdU+ proliferating OPCs were more abundant in CST-deficient mice. These results suggest that sulfated glycolipids may be involved in proliferation of OPCs in vivo
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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