Foreground removal from WMAP 7yr polarization maps using an MLP neural network

One of the fundamental problems in extracting the cosmic microwave background signal (CMB) from millimeter/submillimeter observations is the pollution by emission from the Milky Way: synchrotron, free-free, and thermal dust emission. To extract the fundamental cosmological parameters from CMB signal, it is mandatory to minimize this pollution since it will create systematic errors in the CMB power spectra. In previous investigations, it has been demonstrated that the neural network method provide high quality CMB maps from temperature data. Here the analysis is extended to polarization maps. As a concrete example, the WMAP 7-year polarization data, the most reliable determination of the polarization properties of the CMB, has been analysed. The analysis has adopted the frequency maps, noise models, window functions and the foreground models as provided by the WMAP Team, and no auxiliary data is included. Within this framework it is demonstrated that the network can extract the CMB polarization signal with no sign of pollution by the polarized foregrounds. The errors in the derived polarization power spectra are improved compared to the errors derived by the WMAP Team.Comment: Accepted for publication in Astrophysics & Space Scienc

Power filtration of CMB observational data

We propose a power filter Gp for linear reconstruction of the CMB signal from observational maps. This Gp filter preserves the power spectrum of the CMB signal in contrast to the Wiener filter which diminishes the power spectrum of the reconstructed CMB signal. We demonstrate how peak statistics and a cluster analysis can be used to estimate the probability of the presence of a CMB signal in observational records. The efficiency of the Gp filter is demonstrated on a toy model of an observational record consisting of a CMB signal and noise in the form of foreground point sources.Comment: 17 pages; 4 figures; submitted to International Journal of Modern Physic

Comparing different revisions of the Childhood Health Assessment Questionnaire to reduce the ceiling effect and improve score distribution: Data from a multi-center European cohort study of children with JIA

<p>Abstract</p> <p>Background</p> <p>The original version of the Childhood Health Assessment Questionnaire (CHAQ30orig) suffers from a ceiling effect and hence has reduced clinical validity. The purpose of this study was to evaluate the effect of adding eight more demanding items (CHAQ38) and a new categorical response option (CATII) on discriminant validity and score distribution in a European patient sample.</p> <p>Methods</p> <p>Eighty-nine children with Juvenile Idiopathic arthritis (JIA) and 22 healthy controls, aged 7-16 years, were recruited from eight centres across Europe. Eight new CHAQ items and scoring option were translated back and forth for the countries in which they were not already present. Demographic, clinical, and CHAQ data were collected on-site. Subsequently, five different scoring methods were applied, i.e. the original method (CHAQ30orig) and four alternatives. These alternatives consisted of the mean item scores for the 30 and 38-question versions with either the original (CATI), or the new categorical response option (CATII). The five versions were tested for their ability to distinguish between patients and controls. Furthermore score distributions were evaluated and visualized by box and whisker plots.</p> <p>Results</p> <p>Two CHAQ revisions with the new response option showed poor discriminative ability, whereas one revised version (CHAQ38CATI) had comparable discriminative ability comparable to the original CHAQ. A profound ceiling effect was observed in the original scoring method of the CHAQ (27%). The addition of eight more demanding items and application of a plain mean item score reduced this significantly to 14% (χ²= 4.21; p < 0.05).</p> <p>Conclusions</p> <p>Revising the CHAQ by adding eight more demanding items and applying a plain mean item scoring (CHAQ38CATI) maintained discriminant ability and reduced the ceiling effect in a European patient sample. The new categorical response option (CATII) seemed promising, but was less able to distinguish children with JIA from healthy controls and had less favourable distribution characteristics. The CHAQ38CATI is advocated for future use in mildly affected JIA patients.</p

Demonstration of astrocytes in cultured amniotic fluid cells of three cases with neural-tube defect

We have investigated the origin of rapidly adhering (RA) cells in three cases of neural tube defects (two anencephali, one encephalocele). We were able to demonstrate the presence of glial fibrillary acidic (GFA) protein in variable percentages (4–80%) of RA cells cultured for 4–6 days by use of indirect immunofluorescence with GFA antiserum. Cells cultured from amniotic fluids of normal pregnancies and fetal fibroblasts were completely GFA protein negative. GFA protein is well established as a highly specific marker for astrocytes. Demonstration of astrocytes may prove to be a criterion of high diagnostic value for neural tube defects. The percentage of astrocytes decreased with increasing culture time, while the percentage of fibronectin positive cells increased both in amniotic fluid cell cultures from neural tube defects and normal pregnancies