Separation of foregrounds from cosmic microwave background observations with the MAP satellite

Simulated observations of a 10\dg \times 10\dg field by the Microwave Anisotropy Probe (MAP) are analysed in order to separate cosmic microwave background (CMB) emission from foreground contaminants and instrumental noise and thereby determine how accurately the CMB emission can be recovered. The simulations include emission from the CMB, the kinetic and thermal Sunyaev-Zel'dovich (SZ) effects from galaxy clusters, as well as Galactic dust, free-free and synchrotron. We find that, even in the presence of these contaminating foregrounds, the CMB map is reconstructed with an rms accuracy of about 20 $\mu$K per 12.6 arcmin pixel, which represents a substantial improvement as compared to the individual temperature sensitivities of the raw data channels. We also find, for the single 10\dg \times 10\dg field, that the CMB power spectrum is accurately recovered for \ell \la 600.Comment: 7 pages, 7 figures, MNRAS submitte

Exploring the Gamma Ray Horizon with the next generation of Gamma Ray Telescopes. Part 1: Theoretical predictions

The physics potential of the next generation of Gamma Ray Telescopes in exploring the Gamma Ray Horizon is discussed. It is shown that the reduction in the Gamma Ray detection threshold might open the window to use precise determinations of the Gamma Ray Horizon as a function of the redshift to either put strong constraints on the Extragalactic Background Light modeling or to obtain relevant independent constraints in some fundamental cosmological parameters.Comment: Updated contents, 19 pages, 8 figure

L'ús del coneixement compartit per a ensenyar i aprendre

En aquest treball es descriuen i analitzen els usos del marc social de referència i del marc específic de referència com a mecanismes semiòtics que apareixen en el discurs dels participants en la interacció. Aquests mecanismes acompleixen funcions relacionades amb l’establiment inicial d’un corpus de significats compartits, la seva ampliació, i la resolució d’incomprensions i malentesos. En concret, l’estudi d’aquests mecanismes implica la comprensió de com l’ús d’experiències que suposadament són compartides entre els participants en la interacció intervé en el servei de la construcció d’esferes cada cop més amples d’intersubjectivitat. Els conceptes proposats per a referir-nos al corpus de coneixements suposadament compartits, recurs en el marc social de referència i recurs al marc específic de referència, provenen de diferents estudis (Pla, 1989; Coll et al. 1992, 1995, 1996) dirigits a la seva delimitació conceptual i empírica. En aquest treball s’il·lustren aquests mecanismes semiòtics mitjançant els resultats d’una investigació sobre influència educativa en la interacció entre mare i fill. Aquests resultats s’inscriuen en un projecte d’investigació més ampli dirigit a l’estudi dels mecanismes d’influència educativa en diferents situacions educatives (escolars i no escolars) que, prenent la concepció constructivista com a marc teòric de referència, ha permès l’elaboració d’un model d’anàlisi de la interactivitat (Coll et alt. 1992, 1995).This paper describes and analyzes the uses of the social reference framework and of the specific reference framework as semiotic mechanisms that appear in the interaction participants’ discourse. The mechanisms have different functions related to the initial establishment of a shared meaning corpus, its widening and the solving of misunderstandings. Especially, the study of these mechanisms implies understanding how the use of experiences that supposedly are shared by interaction participants takes part in the construction of ever wider spheres of intersubjectivity. The proposed concepts to refer to the supposedly shared knowledge corpus, resource in the social reference framework and resource in the specific reference framework are taken from different studies (Pla, 1989; Coll et al. 1992, 1995, 1996) targeted at its conceptual and empirical delimitation. This study shows these semiotic mechanisms by the use of the results of an investigation on the educational influence in the interaction between mother and son. These results are part of an wider investigation project aimed at the study of the educational influence mechanisms in different educational situations (in and out of the school) which, considering the constructivist conception as the theoretical reference framework, has enabled the creation of an interactivity analysis model (Coll et al. 1992, 1995).En este trabajo se describen y analizan los usos del marco social de referencia y del marco específico de referencia como mecanismos semióticos que aparecen en el discurso de los participantes en la interacción. Estos mecanismos cumplen funciones relacionadas con el establecimiento inicial de un corpus de significados compartidos, su ampliación, y la resolución de incomprensiones y malentendidos. En concreto, el estudio de estos mecanismos implica la comprensión de como el uso de experiencias que supuestamente son compartidas entre los participantes en la interacción interviene en el servicio de la construcción de esferas cada vez más amplias de intersubjetividad. Los conceptos propuestos para referirnos al corpus de conocimientos supuestamente compartidos, recurso en el marco social de referencia y recurso al marco específico de referencia, provienen de diferentes estudios (Pla, 1989; Coll et al. 1992, 1995, 1996) dirigidos a su delimitación conceptual y empírica. En este trabajo se ilustran estos mecanismos semióticos mediante los resultados de una investigación sobre influencia educativa en la interacción entre madre e hijo. Estos resultados se inscriben en un proyecto de investigación más amplio dirigido al estudio de los mecanismos de influencia educativa en diferentes situaciones educativas (escolares y no escolares) que, tomando la concepción constructivista como marco teórico de referencia, ha permitido la elaboración de un modelo de análisis de la interactividad (Coll et alt. 1992, 1995)

Structure of (8-amino-5,7-dichloroquinoline)dinitratocopper(II), [Cu(NO3)2(C9H6Cl2N2)]

Mr=400.62, monoclinic, C2/c, a=20.901 (5), b=7.439(2), c=18.708(4)A, β=114.59(3)º, V = 2645 (2)A3, Z = 8, Dx = 2.01Mg m-3, F(000) = 1592, (Mo Ka)= 0.71069 A, µ(Mo Ka)= 2.152 mm-1, room temperature, R=0.016, Rw=0.021 for 1132 observed reflections. The Cu atom displays a distorted octahedral coordination, being linked to four O atoms of two NO3 groups and two N atoms of the aminoquinoline. The different hybridization states of the N atoms produce variations in equatorial Cu-O bond distances, while the apical Cu-O lengths are larger than the equatorial lengths: Cu-Oeq 1.990(2), 2.039(3)A; Cu-Oax 2.488 (3), 2.473 (3) A

Wavelet-based methodology for [15O]-H20 PET brain activation assessment

[Abstract] AMI International Conference 2003, September 21-27, Madrid, Spain: "High Resolution Molecular Imaging: from Basic Science to Clinical Applications"Statistical parametric mapping (SPM) is a voxel-byvoxel analysis method commonly used for the detection of brain activation patterns. An alternative approach is the use of multiscale information by means of wavelet analysis. In this study, we have compared the detection of brain activations using conventional SPM and a statistical wavelet analysis in a set of realistic simulated [15O]-H20 positron emission tomography (PET) phantomsPublicad

The Diffuse Supernova Neutrino Background is detectable in Super-Kamiokande

The Diffuse Supernova Neutrino Background (DSNB) provides an immediate opportunity to study the emission of MeV thermal neutrinos from core-collapse supernovae. The DSNB is a powerful probe of stellar and neutrino physics, provided that the core-collapse rate is large enough and that its uncertainty is small enough. To assess the important physics enabled by the DSNB, we start with the cosmic star formation history of Hopkins & Beacom (2006) and confirm its normalization and evolution by cross-checks with the supernova rate, extragalactic background light, and stellar mass density. We find a sufficient core-collapse rate with small uncertainties that translate into a variation of +/- 40% in the DSNB event spectrum. Considering thermal neutrino spectra with effective temperatures between 4-6 MeV, the predicted DSNB is within a factor 4-2 below the upper limit obtained by Super-Kamiokande in 2003. Furthermore, detection prospects would be dramatically improved with a gadolinium-enhanced Super-Kamiokande: the backgrounds would be significantly reduced, the fluxes and uncertainties converge at the lower threshold energy, and the predicted event rate is 1.2-5.6 events /yr in the energy range 10-26 MeV. These results demonstrate the imminent detection of the DSNB by Super-Kamiokande and its exciting prospects for studying stellar and neutrino physics.Comment: 14 pages, 5 figures, 4 tables, some added discussions, accepted for publication in Physical Review

Differential associations of APOE-epsilon 2 and APOE-epsilon 4 alleles with PET-measured amyloid-beta and tau deposition in older individuals without dementia

Purpose: To examine associations between the APOE-ε2 and APOE-ε4 alleles and core Alzheimer’s disease (AD) pathological hallmarks as measured by amyloid-β (Aβ) and tau PET in older individuals without dementia. Methods: We analyzed data from 462 ADNI participants without dementia who underwent Aβ ([18F]florbetapir or [18F]florbetaben) and tau ([18F]flortaucipir) PET, structural MRI, and cognitive testing. Employing APOE-ε3 homozygotes as the reference group, associations between APOE-ε2 and APOE-ε4 carriership with global Aβ PET and regional tau PET measures (entorhinal cortex (ERC), inferior temporal cortex, and Braak-V/VI neocortical composite regions) were investigated using linear regression models. In a subset of 156 participants, we also investigated associations between APOE genotype and regional tau accumulation over time using linear mixed models. Finally, we assessed whether Aβ mediated the cross-sectional and longitudinal associations between APOE genotype and tau. Results: Compared to APOE-ε3 homozygotes, APOE-ε2 carriers had lower global Aβ burden (βstd [95% confidence interval (CI)]: − 0.31 [− 0.45, − 0.16], p = 0.034) but did not differ on regional tau burden or tau accumulation over time. APOE-ε4 participants showed higher Aβ (βstd [95%CI]: 0.64 [0.42, 0.82], p < 0.001) and tau burden (βstd range: 0.27-0.51, all p < 0.006). In mediation analyses, APOE-ε4 only retained an Aβ-independent effect on tau in the ERC. APOE-ε4 showed a trend towards increased tau accumulation over time in Braak-V/VI compared to APOE-ε3 homozygotes (βstd [95%CI]: 0.10 [− 0.02, 0.18], p = 0.11), and this association was fully mediated by baseline Aβ. Conclusion: Our data suggest that the established protective effect of the APOE-ε2 allele against developing clinical AD is primarily linked to resistance against Aβ deposition rather than tau pathology