Acquisizione Ground Penetrating Radar monocanale e multicanale ad alta risoluzione nei contesti geoarcheologici. Il sito archeologico medievale dell'abbazia di Badia Pozzeveri

L’obiettivo del presente lavoro di tesi consiste nel constatare la capacità del Ground Penetrating Radar (Georadar, GPR) nelle prospezioni geoarcheologiche nell’identificare la presenza di possibili targets riconducibili a strutture d’interesse. Quanto detto è stato raggiunto seguendo un percorso ragionato che ha previsto, in primo luogo, la costruzione di un’efficace sequenza processing del dato, cercando di giustificare sotto un’ottica critica quanto più possibile ogni singolo step e analizzando al contempo quei passaggi spesso non convenzionali nel mondo dell’elaborazione dati GPR. Il dato elaborato è stato quindi sfruttato per la realizzazione di determinati sets di time slices da cui poter osservare la presenza, al variare della profondità temporale, di aree particolarmente riflettive da connettere a probabili strutture antropiche sepolte. Un’ultima fase lavorativa, consequenziale alle precedenti, è infine rivolta all’interpretazione dei radargrammi soggetti a processing mediante l’analisi di un numero campione di profili interessanti i targets individuati. Si è dunque cercato di fornire una probabile origine alle riflessioni maggiormente caratterizzanti i radargrammi. Nello specifico l’oggetto del presente studio ha previsto l’acquisizione, l’elaborazione e la restituzione dei dati rilevati nel corso del progetto di ricerca geoarcheologica svolta nel contesto del sito archeologico dell’abbazia medievale di Badia Pozzeveri (Altopascio – LU) la cui struttura doveva probabilmente occupare un’area più ampia rispetto a quella odierna. L’ipotesi animatrice dell’indagine non sembra essere frutto di semplici speculazioni: una maggiore estensione della struttura ecclesiastica, oggi non più visibile, sembra infatti confermata dalla letteratura in materia ed inoltre la stessa forma in pianta attuale denuncia di per se geometrie anomale nei confronti dei canoni di costruzione delle “colleghe” la cui origine è contemporanea. In particolare due sono state le prospezioni interessanti l’area immediatamente prospiciente la facciata dell’abbazia, ad un primo survey realizzato mediante strumentazione monocanale (avente frequenza nominale pari a 400 MHz) ne è seguito un secondo tramite tecnologia multicanale denominata STREAM X (7 canali, frequenza nominale 200 MHz). La motivazione che ha spinto all’esecuzione di due indagini è da ricondurre alla volontà di confermare quanto deducibile dal primo sondaggio, sfruttando le capacità del GPR multicanale il cui uso consente, in tempi di lavoro ragionevoli, una maggiore copertura della zona interessata. L’elaborazione dei dati è stata realizzata mediante GPR Slice, uno dei software più completi e diffusi per il trattamento dei dati radar. Nei riguardi della tesi in oggetto essa può essere pensata come articolata in parti quali: 1. Inquadramento dell’area indagata 2. Aspetti teorici 3. Breve analisi della strumentazione utilizzata e processing del dato 4. Restituzione del dato attraverso la costruzione e la visualizzazione di time slices 5. Interpretazioni delle principali riflessioni caratterizzanti i radargrammi soggetti ad elaborazione Ad un breve inquadramento dell’area indagata segue quindi una seconda fase che abbraccia ciò che concerne la teoria della fisica delle onde elettromagnetiche e del GPR, includendo inoltre gli aspetti base relativi alle proprietà di un’antenna. Nella terza fase l’attenzione è rivolta in primo luogo sulla strumentazione impiegata e sui parametri d’acquisizione (polarizzazione antenna, frequenza nominale, time window, campionamento spaziale, temporale e risoluzione) ed in secondo luogo al processing del dato. In particolare i dati grezzi, sia mono che multicanale, dopo essere stati sottoposti al pre-processing (detrendizzazione del dato e ricerca di un T0 comune) vengono soggetti ad elaborazione seguendo, per quanto riguarda i dati multicanale, due diversi approcci, un primo sviluppato attraverso gli steps ritenuti necessari ed un secondo caratterizzato da passaggi rientranti in ciò che spesso viene definito over processing. Ciò al fine di valutare se l’applicazione di quest’ultimi al dato possa portare reali benefici nella visualizzazione del target d’interesse. Il primo processing flow prevede dunque quei passaggi comuni nell’elaborazione dati GPR quali: filtraggio passa banda, recupero delle ampiezze e rimozione del background. Il secondo processing flow include gli steps appena citati arrichendo il tutto con: spectral whitening, deconvoluzione spiking, deconvoluzione omomorfa e filtraggio boxcar, passaggi questi spesso non applicati in ambiente georadar per la natura stessa dell’onda elettromagnetica. La fase in questione è stata chiaramente svolta con un’ottica critica per una valutazione dell’effettiva efficacia dei singoli passaggi e di come questi si riflettano nell’elaborazione e nella restituzione del dato. Dopo un’attenta comprensione dei parametri di costruzione, alle tre elaborazioni (monocanale + multicanale minima ed “avanzata”) è seguita la realizzazione di time slices, al fine di poter osservare le variazioni d’ampiezza al variare della profondità e di comprendere, se possibile, gli effettivi vantaggi e svantaggi in termini qualitativi (e di tempistica di lavoro) apportati dalle diverse sequenze d’elaborazione seguite. Un metro di paragone per le time slices è stato in particolare offerto dall’elaborazione eseguita direttamente in sito nell’immediato post acquisizione tramite software GREED. Si tratta comunque di un’elaborazione semplicistica (date anche le ridotte soluzioni offerte dal software) i cui risultati tendono ad offrire geometrie dallo stampo “ideale” il cui compito consiste esclusivamente nel fornire un punto di partenza per lo studio del volume indagato. L’ultima fase include infine l’analisi dei radargrammi, attraverso il quale si cerca di fornire una possibile origine alle riflessioni più evidenti e/o caratteristiche; un aiuto è stato qui fornito dal software il quale prevede la possibilità di effettuare incroci tra i profili e le time slices. L’esito dell’intera operazione può essere reputato più che positivo, l’indagine monocanale sembra infatti rilevare corpi riconducibili a strutture sepolte e ciò sembra essere confermato dall’indagine multicanale (capace per altro d’individuare ampiezze d’onda riflesse non riscontrate dal monocanale); malgrado l’area coinvolta da quest’ultima sia in realtà meno estesa dal settore investigato dal GPR monocanale, evidenti sono i targets comuni individuati. Tali oggetti sembrano dunque confermare l’ipotesi della modifica strutturale dell’abbazia nel corso nei secoli, la quale in passato doveva vantare un’estensione decisamente più ampia rispetto a quella oggi visibile. Inoltre l’applicazione di passaggi del processing non convenzionali al dato grezzo ha permesso di ottenere, al contrario di quanto talvolta accade (overprocessing), immagini migliori rispetto a quelle ottenute attraverso un’elaborazione base

Elastic characterization of nanometer-thick polymeric film for astrophysics application with an experimental-numerical method

The x-ray detectors on board astrophysics space missions require optical blocking filters that are highly transparent to x-rays. The filter design typically consists of a polymeric film that is a few tens of nanometers thick coated with aluminium. Due to the large size of the filter membrane (from a few tens to a few hundred square centimeters) and the extreme aspect ratio, together with severe loading conditions during launch and different stoichiometries of the polymer that could change its mechanical properties, a characterization study of the employed material is needed. The plane strain bulge test is a well-accepted methodology for the mechanical testing of structures that are less than a micrometer thick, and especially for freestanding membranes. Unfortunately, testing such ultra-thin films is not a simple task due to residual stress and experimental uncertainty at very low pressure. In this work, the elastic properties of an extremely thin (between 45 and 415 nm) membrane made of bare polyimide and coated with aluminium were derived through adopting a combined experimental-numerical methodology based on the bulge test and numerical simulations

Deformation analysis of ATHENA test filters made of plastic thin films supported by a mesh under differential static pressure

Within ESA Cosmic Vision 2015-2025 Science Program, ATHENA was selected to be a Large-class high energy astrophysics space mission. The observatory will be equipped with two interchangeable focal plane detectors named X-Ray Integral Field Unit (X-IFU) and Wide Field Imager (WFI). In order to optimally exploit the detector sensitivity, X-ray transparent filters are required. Such filters need to be extremely thin to maximize the X-ray transparency, that is, no more than a few tens of nm, still they must be able to sustain the severe stresses experienced during launch. Partially representative test filters were made with a thin polypropylene film, coated with Ti, and supported by a thin highly transparent mesh either in stainless steel or niobium. Differential static pressure experiments were carried out on two filter samples. In addition, the roles of the mesh on the mechanical deformation is studied, adopting a finite element model (FEM). The numerical analysis is compared with experimental results and found in good agreement. The FEM is a promising tool that allows to characterize materials and thicknesses in order to optimize the design

Tetracycline Residues in Bovine Muscle and Liver Samples from Sicily (Southern Italy) by LC-MS/MS Method: A Six-Year Study

We examined a total of 369 bovine liver and muscle samples for the detection of oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC), and doxycycline (DOX) residues by implementation and validation of a LC-MS/MS method. The method showed good recovery values between 86% and 92% at three levels of concentrations. The linearity tests revealed r2 > 0.996 for all the tetracyclines examined. Furthermore, the Youden test revealed that the method was robust. Only 14.4% of the samples showed OTC and TC residues in a concentration range of 10.4–40.2 g kg1. No CTC and DOX residues were found in all the samples analyzed. Liver samples showed the highest average values (31.5 20.6 and 21.8 18.9 for OTC and TC, respectively). The results showed a low incidence of TCs in all the samples examined, in comparison with other studies reported in the literature. A significant decrease in TC residues frequency was found from 2013 (p < 0.05). This work reports for the first time epidemiological data on the presence of TC residues in liver and muscle samples of cattle farmed in Sicily (Southern Italy). The very low incidence of TC residues indicates a continuous improvement in farming techniques in Southern Italy, which is essential to ensure consumers’ protection

Land Snails as a Valuable Source of Fatty Acids: A Multivariate Statistical Approach

The fatty acid (FA) profile of wild Theba pisana, Cornu aspersum, and Eobania vermiculata land snail samples, collected in Sicily (Southern Italy), before and after heat treatment at +100 °C were examined by gas chromatography with a flame ionization detector (GC‐FID). The results show a higher content of polyunsaturated fatty acids (PUFAs) in all of the examined raw snails samples, representing up to 48.10% of the total fatty acids contents, followed by monounsaturated fatty acids (MUFAs). The thermal processing of the snail samples examined determined an overall reduction of PUFA levels (8.13%, 7.75%, and 4.62% for T. pisana, C. aspersum and E. vermiculata samples, respectively) and a species‐specific variation of saturated fatty acid (SFA) contents. Oleic acid remained the most abundant FA of all of the snails species examined, accounting for up to 29.95% of the total FA content. A relevant decrease of ɷ3/ɷ6 ratio was found only for T. pisana samples. The principal component analysis (PCA) showed a separation of the snail samples in terms of species and heat treatment. The results of this work suggest land snails as a valuable source of MUFA and PUFA contents and boiling as appropriate treatment, according to the maintenance of healthy properties

X-IFU Filter Wheel Optical Blocking Filters Technology Demonstration Plan

The main purpose of the present plan is to provide a clear path to demonstrate the TRL5 by the Mission Adoption for the three OBFs on the X-IFU Filter Wheel (FW). An effort has been performed in trying to identify what shall be considered technology, for which the maturity has to be demonstrated, and what is design that can still contribute to improve the performances of the FW filters along phases B and C of development. The X-IFU FW filters conceptual design is similar to that defined (during phase A) and described in the "X-IFU Filter Wheel Mechanism and Electronics Design Description", and the "X-IFU Thermal Filters (THFs) Description" documents presented at the I-PRR. The preliminary design of the X-IFU FW Filters rely on heritage from previous missions and characterization tests performed in phase-A on breadboards manufactured by LUXEL Corporation (Friday Harbor, WA, USA). The adoption of a design similar to that of the X-IFU THFs for frame shape and materials, and to that of the WFI FW filters for film and coating thicknesses, as well as for overall dimensions, allow migrating part of the achievements reached by the X-IFU THFs and WFI FW filters to the X-IFU FW filters. For this reason, the TDP for the X-IFU FW filters will be mainly focused on the vibro-acoustic performances. With this respect, minor effort will be dedicated to the thick and very robust meshless filter (25 μm PI + 100 nm Al) designed to observe very bright x-ray sources. The goal of this activity is to demonstrate TRL5 before MAR for the baseline technology of filters manufactured by LUXEL (PI/Al on BeCu mesh). However, in parallel to verify also the maturity of other filter technologies and to mitigate the risks of having only one manufacturer, we will procure and test filter samples and bare meshes of other European manufacturers (OXFORD instruments, XRNanotech). The identified TECHNOLOGY development elements that we consider critical in the X-IFU FW OBFs are described in this document. In section 7 we list the breadboards (BBs) we have identified to perform the necessary characterization tests aimed at demonstrating their maturity

The thin and medium filters of the EPIC camera on-board XMM-Newton: measured performance after more than 15 years of operation

After more than 15 years of operation of the EPIC camera on board the XMM-Newton X-ray observatory, we have reviewed the status of its Thin and Medium filters. We have selected a set of Thin and Medium back-up filters among those still available in the EPIC consortium and have started a program to investigate their status by different laboratory measurements including: UV/VIS transmission, Raman scattering, X-Ray Photoelectron Spectroscopy, and Atomic Force Microscopy. Furthermore, we have investigated the status of the EPIC flight filters by performing an analysis of the optical loading in the PN offset maps to gauge variations in the optical and UV transmission. We both investigated repeated observations of single optically bright targets and performed a statistical analysis of the extent of loading versus visual magnitude at different epochs. We report the results of the measurements conducted up to now. Most notably, we find no evidence for change in the UV/VIS transmission of the back-up filters in ground tests spanning a 2 year period and we find no evidence for change in the optical transmission of the thin filter of the EPIC-pn camera from 2002 to 2012. We point out some lessons learned for the development and calibration programs of filters for X-ray detectors in future Astronomy missions

Fatty Acids Composition of Stomach Oil of Scopoli’s Shearwater (Calonectris diomedea) from Linosa’s Colony

Calonectris diomedea is a Procellariforms seabird having a very representative colony in Linosa Island (Southern Italy). The adult forms of C. diomedea produce a pasty oil from their proven- triculus to feed their chicks during the rearing period. In this work, we examined the fatty acids composition of the stomach oil of C. diomedea from Linosa Island by gas chromatography with flame ionization detection (GC-FID). The samples were collected at 20 and 70 days after hatching. Twenty different fatty acids (FAs) were identified. Saturated fatty acids (SFA) were the most abundant in percentage (41.6%) at day 20 followed by polyunsaturated fatty acids (PUFA, 38.7%) and monounsat- urated fatty acids (MUFA, 19.7%). MUFAs were the most abundant in samples collected at day 70 (53.8%), followed by SFAs (36.6%) and PUFAs (9.8%). Oleic acid (C18:1ω9) in the samples on day 70 was 4 times higher than that in the samples on day 20. The Principal Component Analysis (PCA) verified a clear separation of the stomach oil samples in two groups, according to the day of sampling. The results obtained confirm the role of FAs analysis of stomach oil to understand the ecology and breeding behaviour of C. diomedea, highlighting a resemblance with signatures recorded in marine organisms of Linosa Island

The large area detector onboard the eXTP mission

The Large Area Detector (LAD) is the high-throughput, spectral-timing instrument onboard the eXTP mission, a flagship mission of the Chinese Academy of Sciences and the China National Space Administration, with a large European participation coordinated by Italy and Spain. The eXTP mission is currently performing its phase B study, with a target launch at the end-2027. The eXTP scientific payload includes four instruments (SFA, PFA, LAD and WFM) offering unprecedented simultaneous wide-band X-ray timing and polarimetry sensitivity. The LAD instrument is based on the design originally proposed for the LOFT mission. It envisages a deployed 3.2 m2 effective area in the 2-30 keV energy range, achieved through the technology of the large-area Silicon Drift Detectors - offering a spectral resolution of up to 200 eV FWHM at 6 keV - and of capillary plate collimators - limiting the field of view to about 1 degree. In this paper we will provide an overview of the LAD instrument design, its current status of development and anticipated performance

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. (abridged).Comment: 48 pages, 29 figures, Accepted for publication in Experimental Astronomy with minor editin