Correlation methods for the analysis of X-ray polarimetric signals

X-ray polarimetric measurements are based on studying the distribution of the directions of scattered photons or photoelectrons and on the search of a sinusoidal modulation with a period of {\pi}. We developed two tools for investigating these angular distributions based on the correlations between counts in phase bins separated by fixed phase distances. In one case we use the correlation between data separated by half of the bin number (one period) which is expected to give a linear pattern. In the other case, the scatter plot obtained by shifting by 1/8 of the bin number (1/4 of period) transforms the sinusoid in a circular pattern whose radius is equal to the amplitude of the modulation. For unpolarized radiation these plots are reduced to a random point distribution centred at the mean count level. This new methods provide direct visual and simple statistical tools for evaluating the quality of polarization measurements and for estimating the polarization parameters. Furthermore they are useful for investigating distortions due to systematic effects

The 5th edition of the Roma-BZCAT. A short presentation

The 5th edition of the Roma-BZCAT Multifrequency Catalogue of Blazars is available in a printed version and online at the ASDC website (http://www.asdc.asi.it/bzcat); it is also in the NED database. It presents several relevant changes with respect to the past editions which are briefly described in this paper.Comment: 5 pages, 3 figures. Accepted for publication in Astrophysics and Space Scienc

Comparison of direct and indirect methods for minimum lap time optimal control problems

Minimum lap time simulations are especially important in the design, optimisation and setup of race vehicles. Such problems usually come in different flavours, e.g. quasi-steady state models vs full dynamic models and pre-defined (fixed) trajectory problems vs free trajectory problems. This work is focused on full dynamic models with free trajectory. Practical solution techniques include direct methods (i.e. solution of an NLP problem, widespread approach) and indirect method (i.e. based on Pontryagins principle, less common, yet quite efficient in some cases). In this contribution the performance of the direct and indirect methods are compared in a number of vehicle related problems

The colours of BL Lac objects: a new approach to their classification

We selected a sample of 437 BL Lac objects, taken from the RomaBZCat catalogue, for which spectroscopic information and SDSS photometry is available. We propose a new classification of BL Lacs in which the sources' type is not defined only on the basis of the peak frequency of the synchrotron component in their Spectral Energy Distribution (types L and H), but also on the relevance of this component with respect to the brightness of the host galaxy (types N and G, for nuclear or galaxy dominated sources). We found that the SDSS colour index u-r=1.4 is a good separator between these two types. We used multiband colour-colour plots to study the properties of the BL Lac classes and found that in the X-ray to radio flux ratio vs u-r plot most of the N (blue) sources are located in a rather narrow strip, while the G-sources (red) are spread in a large area, and most of them are located in galaxy clusters or interacting systems, suggesting that their X-ray emission is not from a genuine BL Lac nucleus but it is related to their environment. Of the about 135 sources detected in the gamma-rays by Fermi-GST, nearly all belong to the N-type, indicating that only this type of sources should be considered as genuine BL Lac nuclei. The J-H, H-K plot of sources detected in the 2MASS catalogue is consistent with that of the "bona fide" BL Lac objects, independently of their N or G classification from the optical indices, indicating the existence in G-type sources of a K-band excess possibly due to a steep, low frequency peaked emission which deserves further investigations. We propose to use these colour plots as a further tool for searching candidate counterparts of newly discovered high-energy sources.Comment: 11 pages, 7 figures. Submitted 29/08/2011 to MNRAS, first referee report received 31/10/2011, accepted 21/02/201

Timing analysis of 10-day long BeppoSAX observation of GRS 1915+105 in its ρ class

Published online at http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=6

L3DAS21 Challenge: Machine Learning for 3D Audio Signal Processing

The L3DAS21 Challenge is aimed at encouraging and fostering collaborative research on machine learning for 3D audio signal processing, with particular focus on 3D speech enhancement (SE) and 3D sound localization and detection (SELD). Alongside with the challenge, we release the L3DAS21 dataset, a 65 hours 3D audio corpus, accompanied with a Python API that facilitates the data usage and results submission stage. Usually, machine learning approaches to 3D audio tasks are based on single-perspective Ambisonics recordings or on arrays of single-capsule microphones. We propose, instead, a novel multichannel audio configuration based multiple-source and multiple-perspective Ambisonics recordings, performed with an array of two first-order Ambisonics microphones. To the best of our knowledge, it is the first time that a dual-mic Ambisonics configuration is used for these tasks. We provide baseline models and results for both tasks, obtained with state-of-the-art architectures: FaSNet for SE and SELDNet for SELD. This report is aimed at providing all needed information to participate in the L3DAS21 Challenge, illustrating the details of the L3DAS21 dataset, the challenge tasks and the baseline models.Comment: Documentation paper for the L3DAS21 Challenge for IEEE MLSP 2021. Further information on www.l3das.com/mlsp202

A MST algorithm for source detection in gamma-ray images

We developed a source detection algorithm based on the Minimal Spanning Tree (MST), that is a graph-theoretical method useful for finding clusters in a given set of points. This algorithm is applied to gamma-ray bidimensional images where the points correspond to the arrival direction of photons, and the possible sources are associated with the regions where they clusterize. Some filters to select these clusters and to reduce the spurious detections are introduced. An empirical study of the statistical properties of MST on random fields is carried in order to derive some criteria to estimate the best filter values. We introduce also two parameters useful to verify the goodness of candidate sources. To show how the MST algorithm works in the practice, we present an application to an EGRET observation of the Virgo field, at high galactic latitude and with a low and rather uniform background, in which several sources are detected.Comment: 10 pages, 7 figures. Accepted for publication in MNRA

Small vessel disease and biomarkers of endothelial dysfunction after ischaemic stroke

Abstract Introduction: Although pathogenesis of small vessel disease is poorly understood, increasing evidence suggests that endothelial dysfunction may have a relevant role in development and progression of small vessel disease. In this crosssectional study, we investigated the associations between imaging signs of small vessel disease and blood biomarkers of endothelial dysfunction at two different time points in a population of ischaemic stroke patients. Patients and methods: In stroke patients treated with intravenous thrombolysis, we analysed blood levels of von Willebrand factor, intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and vascular endothelial growth factor. Three reviewers independently assessed small vessel disease features using computed tomography. At baseline and 90 days after the index stroke, we tested the associations between single and combined small vessel disease features and levels of blood biomarkers using linear regression analysis adjusting for age, sex, hypertension, diabetes, smoke. Results: A total of 263 patients were available for the analysis. Mean age (SD) was 69 (13) years, 154 (59%) patients were male.We did not find any relation between small vessel disease and endothelial dysfunction at baseline. At 90 days, leukoaraiosis was independently associated with intercellular adhesionmolecule-1 (b¼0.21; p¼0.016) and vascular cell adhesionmolecule- 1 (b¼0.22; p¼0.009), and lacunes were associated with vascular endothelial growth factor levels (b¼0.21; p¼0.009) whereas global small vessel disease burden was associated with vascular endothelial growth factor (b¼0.26; p¼0.006). Discussion: Leukoaraiosis and lacunes were associated with endothelial dysfunction, which could play a key role in pathogenesis of small vessel disease

Scientific report of the project COMpton Polarimeter with Avalanche Silicon readout (COMPASS)

Rendicontazione scientifica mandata all'INAF alla conclusione del progetto COMpton Polarimeter with Avalanche Silicon readout (COMPASS), finanziato dal bando TECNO INAF 2014COMpton Polarimeter with Avalanche Silicon readout (COMPASS) is a research and development project that aims to measure the polarization of X-ray photons through Compton Scattering. The measurement is obtained by using a set of small rods of fast scintillation materials with both low-Z (as active scatterer) and high-Z (as absorber), all read-out with Silicon Photomultipliers. By this method we can operate scattering and absorbing elements in coincidence, in order to reduce the background. This is the scientific report submitted to INAF at the end of the COMPASS project, funded through the grant TECNO INAF 201

Protocollo per l’aggiornamento delle Misure per il contrasto e il contenimento della diffusione del virus SARS-CoV-2/Covid-19 nelle Strutture di Ricerca e nella Sede della Amministrazione Centrale dello Istituto Nazionale di Astrofisica.

Il documento è da intendersi come protocollo per l’aggiornamento delle misure di contrasto alla diffusione dell’epidemia da Covid-19, anche in considerazione dell’emanazione dei nuovi provvedimenti adottati dal Governo e dal Ministero della Salute, di circolari e “comunicazioni” di Ministeri e Autorità competenti, e della legislazione vigente in materia di contrasto alla diffusione dell’epidemia da Covid-19, e contiene linee guida per la revisione e l’aggiornamento dei “Protocolli di sicurezza” adottati a livello locale dalle Strutture di Ricerca e dalla sede della Amministrazione Centrale, tenuto conto della situazione epidemiologica e della necessità di conservare misure efficaci per prevenire e ridurre il rischio di contagio. Il documento tiene conto delle nuove disposizioni normative e, in particolare, del “Protocollo condiviso di aggiornamento delle misure per il contrasto e il contenimento della diffusione del virus SARS-CoV-2/COVID-19 negli ambienti di lavoro”, siglato il 30 giugno 2022 e ha l’obiettivo di fornire indicazioni operative e linee guida aggiornate per garantire l’efficacia delle misure precauzionali di contenimento adottate per contrastare l’epidemia da Covid-19, applicando tutte le misure necessarie allo svolgimento delle attività lavorative nella massima sicurezza, tenendo in particolare conto gli aspetti che riguardano il benessere del personale nell’accezione più ampia del termine. Il documento richiama, inoltre, la necessità di promuovere e favorire, in ogni sistema di prevenzione di qualunque rischio, un ambiente di lavoro sereno, in cui i rapporti interpersonali siano improntati alla correttezza, al reciproco rispetto della libertà e dignità della persona in quanto diritti inviolabili di tutto il personale che a qualsiasi titolo lavora e opera all'interno dell'Istituto, delle lavoratrici e dei lavoratori chiamati ad applicare, a garantire il rispetto del presente documento e di chi ha lavorato per la sua stesura. Atteggiamenti offensivi, molesti, violenti e lesivi della dignità e della professionalità dell’individuo sul luogo di lavoro, oltre a costituire fattori di rischio lavorativo, sono stigmatizzati dai “Codici” adottati dall’Ente