1,140 research outputs found
Full Sky Study of Diffuse Galactic Emission at Decimeter Wavelengths
A detailed knowledge of the Galactic radio continuum is of high interest for
studies of the dynamics and structure of the Galaxy as well as for the problem
of foreground removal in Cosmic Microwave Background measurements. In this work
we present a full-sky study of the diffuse Galactic emission at frequencies of
few GHz, where synchrotron radiation is by far the dominant component. We
perform a detailed combined analysis of the extended surveys at 408, 1420 and
2326 MHz (by Haslam et al. 1982, Reich 1982, Reich & Reich, 1986 and Jonas et
al. 1998, respectively). Using the technique applied by Schlegel et al. (1998)
to the IRAS data, we produce destriped versions of the three maps. This allows
us to construct a nearly-full-sky map of the spectral index and of the
normalization factor with sub-degree angular resolution. The resulting
distribution of the spectral indices has an average of beta = 2.695 and
dispersion sigma_{beta} = 0.120. This is representative for the Galactic
diffuse synchrotron emission, with only minor effects from free-free emission
and point sources.Comment: 10 pages, 16 jpeg figures, accepted to Astronomy & Astrophysics,
Comments and figure adde
Progressive deformation patterns from an accretionary prism (Helminthoid flysch, Ligurian Alps, Italy)
This paper reports the results of a field-based structural investigation of a well-exposed paleo-accretionary prism, which experienced complex deformation in a low-grade metamorphic setting. Field analyses focused on the description of structural fabrics, with the main emphasis upon parameters like the orientation, style and kinematics of foliations, folds and shear zones. We address the research to the south-westernmost part of the Alpine chain, the Ligurian Alps, where, despite their origin as turbidite sequences deposited into the closing Alpine Tethys Ocean, the Helminthoid Flysch Nappes are presently distributed in the outer part of the chain, above the foreland. The new dataset highlights different deformation patterns related to the different spatial distribution of the flysch units. This regional-scale partitioning of strain is hence associated with progressive deformation within a two-stage geodynamic evolution. Correlations among the different orogenic domains allow the proposal of a kinematic model that describes the motion of the Helminthoid Flysch from the inner to the outer part of the orogen, encompassing the shift from subduction- to collision-related Alpine geodynamic phases
Development of microwave superconducting microresonators for neutrino mass measurement in the HOLMES framework
The European Research Council has recently funded HOLMES, a project with the
aim of performing a calorimetric measurement of the electron neutrino mass
measuring the energy released in the electron capture decay of 163Ho. The
baseline for HOLMES are microcalorimeters coupled to Transition Edge Sensors
(TESs) read out with rf-SQUIDs, for microwave multiplexing purposes. A
promising alternative solution is based on superconducting microwave
resonators, that have undergone rapid development in the last decade. These
detectors, called Microwave Kinetic Inductance Detectors (MKIDs), are
inherently multiplexed in the frequency domain and suitable for even
larger-scale pixel arrays, with theoretical high energy resolution and fast
response. The aim of our activity is to develop arrays of microresonator
detectors for X-ray spectroscopy and suitable for the calorimetric measurement
of the energy spectra of 163Ho. Superconductive multilayer films composed by a
sequence of pure Titanium and stoichiometric TiN layers show many ideal
properties for MKIDs, such as low loss, large sheet resistance, large kinetic
inductance, and tunable critical temperature . We developed Ti/TiN
multilayer microresonators with within the range from 70 mK to 4.5 K and
with good uniformity. In this contribution we present the design solutions
adopted, the fabrication processes and the characterization results
Digital Deblurring of CMB Maps II: Asymmetric Point Spread Function
In this second paper in a series dedicated to developing efficient numerical
techniques for the deblurring Cosmic Microwave Background (CMB) maps, we
consider the case of asymmetric point spread functions (PSF). Although
conceptually this problem is not different from the symmetric case, there are
important differences from the computational point of view because it is no
longer possible to use some of the efficient numerical techniques that work
with symmetric PSFs. We present procedures that permit the use of efficient
techniques even when this condition is not met. In particular, two methods are
considered: a procedure based on a Kronecker approximation technique that can
be implemented with the numerical methods used with symmetric PSFs but that has
the limitation of requiring only mildly asymmetric PSFs. The second is a
variant of the classic Tikhonov technique that works even with very asymmetric
PSFs but that requires discarding the edges of the maps. We provide details for
efficient implementations of the algorithms. Their performance is tested on
simulated CMB maps.Comment: 9 pages, 13 Figure
A Statistical Analysis of the "Internal Linear Combination" Method in Problems of Signal Separation as in CMB Observations
AIMS: The separation of foreground contamination from cosmic microwave
background (CMB) observations is one of the most challenging and important
problem of digital signal processing in Cosmology. In literature, various
techniques have been presented, but no general consensus about their real
performances and properties has been reached. This is due to the
characteristics of these techniques that have been studied essentially through
numerical simulations based on semi-empirical models of the CMB and the
Galactic foregrounds. Such models often have different level of sophistication
and/or are based on different physical assumptions (e.g., the number of the
Galactic components and the level of the noise). Hence, a reliable comparison
is difficult. What actually is missing is a statistical analysis of the
properties of the proposed methodologies. Here, we consider the "Internal
Linear Combination" method (ILC) which, among the separation techniques,
requires the smallest number of "a priori" assumptions. This feature is of
particular interest in the context of the CMB polarization measurements at
small angular scales where the lack of knowledge of the polarized backgrounds
represents a serious limit. METHODS: The statistical characteristics of ILC are
examined through an analytical approach and the basic conditions are fixed in a
way to work satisfactorily. RESULTS: ILC provides satisfactory results only
under rather restrictive conditions. This is a critical fact to take into
consideration in planning the future ground-based observations (e.g., with
ALMA) where, contrary to the satellite experiments, there is the possibility to
have a certain control of the experimental conditions.Comment: A version of this manuscript without figures has been accepted for
publication by A&A. A & A 2008, accepte
Long-term neuropsychological sequelae, emotional wellbeing and quality of life in patients with acquired thrombotic thrombocytopenic purpura
Neurological symptoms related to microthrombosis are the hallmark of acute manifestations of acquired thrombotic thrombocytopenic purpura. Despite the achievement of hematological remission, patients may report persisting neurological impairment that affects their quality of life. To assess the long-term neuropsychological consequences of acute thrombotic thrombocytopenic purpura, we recruited 35 acquired thrombotic thrombocytopenic purpura patients (77% females, median age at onset 41 years, interquartile range 35-48) regularly followed at our out-patient clinic of thrombotic microangiopathies in Milan (Italy) from December 2015 to October 2016. Patients underwent a psychological evaluation of memory and attentional functions, emotional wellbeing and health-related quality of life at least 3 months after their last acute thrombotic thrombocytopenic purpura event (median 36 months, interquartile range 17-54). During the psychological consultation, 17 patients (49%) referred persisting subjective neurological impairment in the frame of a remission phase, with at least one symptom as disorientation, loss of concentration, dizziness, lack of balance, headache and diplopia. Neuropsychological assessment revealed lower scores than the Italian general population pertaining to direct, indirect and deferred memory. A higher degree of impairment of memory domains was found in patients with neurological involvement at the time of presentation of the first acute thrombotic thrombocytopenic purpura episode. Anxiety and depression were detected in 7 (20%) and 15 (43%) patients, respectively. Health-related quality of life was lower than the Italian general population, with mental domains more impacted than physical domains (mean difference 58.43, 95% confidence interval [-71.49, -45.37]). Our study demonstrates compromised memory and attention functions, persisting anxiety/depression symptoms and a generally reduced quality of life in patients surviving from acute acquired thrombotic thrombocytopenic purpura. New clinical strategies should be considered to improve these symptoms
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