Compressive Sensing for Dynamic XRF Scanning

X-Ray Fluorescence (XRF) scanning is a widespread technique of high importance and impact since it provides chemical composition maps crucial for several scientific investigations. There are continuous requirements for larger, faster and highly resolved acquisitions in order to study complex structures. Among the scientific applications that benefit from it, some of them, such as wide scale brain imaging, are prohibitively difficult due to time constraints. However, typically the overall XRF imaging performance is improving through technological progress on XRF detectors and X-ray sources. This paper suggests an additional approach where XRF scanning is performed in a sparse way by skipping specific points or by varying dynamically acquisition time or other scan settings in a conditional manner. This paves the way for Compressive Sensing in XRF scans where data are acquired in a reduced manner allowing for challenging experiments, currently not feasible with the traditional scanning strategies. A series of different compressive sensing strategies for dynamic scans are presented here. A proof of principle experiment was performed at the TwinMic beamline of Elettra synchrotron. The outcome demonstrates the potential of Compressive Sensing for dynamic scans, suggesting its use in challenging scientific experiments while proposing a technical solution for beamline acquisition software.Comment: 16 pages, 7 figures, 1 tabl

Reconciling Parker Solar Probe observations and magnetohydrodynamic theory

The Parker Solar Probe mission provides a unique opportunity to characterize several features of the solar wind at different heliocentric distances. Recent findings have shown a transition in the inertial range spectral and scaling properties around 0.4-0.5 au when moving away from the Sun. Here we provide, for the first time, how to reconcile these observational results on the radial evolution of the magnetic and velocity field fluctuations with two scenarios drawn from the magnetohydrodynamic theory. The observed breakdown is the result of the radial evolution of magnetic field fluctuations and plasma thermal expansion affecting the distribution between magnetic and velocity fluctuations. The two scenarios point towards an evolving nature of the coupling between fields that can be also reconciled with Kraichnan and Kolmogorov pictures of turbulence. Our findings have important implications for turbulence studies and modeling approaches.Comment: 9 pages, 4 figure

Comprehensive Sun-to-Earth analysis of the Geoeffective Solar event of June 21, 2015: Effects on the Magnetosphere - Plasmasphere - Ionosphere system

A full-halo coronal mass ejection left the sun on June 21, 2015 from the active region NOAA 12371 encountering Earth on June 22, 2015, generating a G3 strong geomagnetic storm. The CME was associated with an M2 class flare observed at 01:42 UT, located near the center disk (N12E16). Using satellite data from solar, heliospheric, magnetospheric missions and ground-based instruments, we performed a comprehensive Sun-to-Earth analysis. In particular, we analyzed the active region evolution using ground-based and satellite instruments (BBSO, IRIS, HINODE, SDO/AIA, RHESSI -- Halpha, EUV, UV, X), the AR magnetograms, using data from SDO HMI, the relative particle data, using PAMELA instruments and the effects of interplanetary perturbation on cosmic ray intensity. We also evaluated the 1-8 $\AA$ soft X-ray and low-frequenct ($\sim$ 1 MHz) Type III radio burst time-integrated intensity (or fluence) of the flare in order to make a prediction of the associated Solar Energetic Particle (SEP) event by using the model developed by \cite{Laurenza09}. Inaddition, using ground based observations from lower to higher latitudes (INTERMAGNET - EMMA, etc.), we reconstructed the ionospheric current system associated to the geomagnetic Sudden Commencement. Furthermore, SuperDARN measurements are used to image the global ionospheric polar convection during the SSC and during the principal phases of the geomagnetic storm. Moreover, we investigated the dynamics of the plasmasphere during the different phases of the geomagnetic storm by examining the time evolution of the radial profiles of the equatorial plasma mass density derived from field line resonances detected at the EMMA network (1.5 $<$ L $<$ 6.5). Finally, we presented the general features of the geomagnetic response to the CME, by applying innovative data analysis tools that allow to investigate the time variation of ground-based observations of the Earth's magnetic field during the associated geomagnetic storm

Elemental composition of soils and sediments by using portable X-ray fluorescence (pXRF) spectroscopy: a preliminary study

Portable X-ray fluorescence spectrometry (pXRF) provides rapid and low-cost analysis in laboratory and field conditions for a wide range of environmental applications. Its successful application in soils requires a good instrument calibration and the possibility to implement custom calibrations and methods using known samples as well as reference materials. In the present study two set of samples, one from pedogenized sediments of a basin in Marradi (Italy; n=13) and the other from agricultural land in Meuse valley (Belgium; n=10), were analyzed by using a portable X-ray fluorescence (pXRF TRACER 5i made by Bruker) to detect and quantify the element species (Al, Si, Ca, Fe, Mg, K, Mn, P, S, Ba, Cd, Co, Cr, Cu, Mo, Pb, Sb, Sn, Sr and Zn). Element concentrations results were compared with analytical results from aqua regia extractions (AQ) followed by ICP-OES analysis. The aim of this work was to verify and find the best instrument setup for the specific matrix, elements and their concentration range with the purpose of using the pXRF technique directly insitu for the screening of sites potentially polluted. A standard factory calibration for soil applications was used for samples from Meuse valley, while a custom calibration for P, S, Ca and Fe quantification with the coefficient correction method was developed and used for pedogenized sediments from Marradi, as well as for Cu and Cr quantification in both sites. Comparing portable XRF and AQ results, elements could be grouped in three classes: 1) elements where the content determined by both methods is not correlated (p>0.05; Al, Si, and K); 2) elements strongly correlated (0.840.60), carbonates (Ca, r2>0.55) and oxy(hydr)oxides (Fe and Mn) have instead comparable concentrations between pXRF and AQ. Preliminary results showed that portable XRF can quickly provide data for some elucidations of important pedogenic processes involving many elements (class 2) in the studied soils. Alternative methods offer results after expensive and time-consuming analytical procedures. Moreover for environmental and human health purposes, the pXRF should be a valid tool for a rapid screening of heavy metals, such as Cu, Cr, Zn and Pb. A larger set of soil samples and further custom calibration will be tested

FABRICAÇÃO DE CHAPAS DE PARTÍCULAS AGLOMERADAS USANDO GESSO COMO MATERIAL CIMENTANTE

Neste trabalho, foram confeccionadas chapas aglomeradas, utilizando gesso como material cimentante e papel reciclável dissociado (jornal e offset) e partículas de madeira de pinus como reforços. Em todos os tratamentos, a razão madeira (ou fibras) para gesso foi mantida em 0,25 (base seca) e duas dosagens de água (w) foram empregadas: 0,4 e 0,8, correspondendo à razão água:gesso. As chapas foram prensadas a frio em prensa de laboratório, em um processo similar à produção de chapas aglomeradas convencionais. Após condicionadas em câmara climatizada, as chapas foram testadas em flexão estática, dureza, arrancamento de parafusos, absorção d’água e inchamento em espessura. Em geral, a adição de fibras causou melhoria nas propriedades das chapas. Diferenças estatísticas significativas em relação à testemunha (gesso puro) foram encontradas para resistência à flexão estática (MOR), dureza e arrancamento de parafusos em relação a alguns dos tratamentos estudados. Já a inclusão de fibras de papel reciclável, com w = 0,4, não apresentou diferenças significativas em relação à testemunha para absorção d’água e inchamento em espessura. Os melhores resultados foram encontrados com papel jornal, com um coeficiente w = 0,4

Influenza vaccination among Health Care Workers at a Regional University Adult Acute-Care Hospital in Genoa, Liguria, Italy: results from a project promoting awareness and active offer during the period 2005-2011

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Heptavalent Pneumococcal Conjugate Vaccine: growing knowledge and its implications for Italy

Introductive note A wide literature on Streptococcus Pneumoniae (Pn) infections is available, largely published in the recent years, after the introduction of the heptavalent conjugate vaccine in US and in Europe. This review is based on the most up-to-date scientific articles about this pathogen

A global permittivity map of the Martian surface from SHARAD and some geological correlations

We present the first global SHARAD permittivity map of the Martian surface and use it to constrain the subsurface geology inferred from other data sources. Geological correlations are discussed at the dichotomy boundary, Elysium Mons, and high-latitude ice-filled craters

Global permittivity mapping of the Martian surface from SHARAD

SHARAD is a subsurface sounding radar aboard NASA's Mars Reconnaissance Orbiter, capable of detecting dielectric discontinuities in the subsurface caused by compositional and/or structural changes. Echoes coming from the surface contain information on geometric properties at metre scale and on the permittivity of the upper layers of the Martian crust. A model has been developed to estimate the effect of surface roughness on echo power, depending on statistical parameters such as RMS height and topothesy. Such model is based on the assumption that topography can be characterized as a self-affine fractal, and its use allows the estimation of the dielectric properties of the first few metres of the Martian soil. A permittivity map of the surface of Mars is obtained, covering several large regions across the planet surface. The most significant correspondence with geology is observed at the dichotomy boundary, with high dielectric constant on the highlands side (7 to over 10) and lower on the lowlands side (3 to 7). Other geological correlations are discussed