The Fundamental Properties of Planet-Forming Disks: a Model-Data Comparison

This thesis presents a comprehensive investigation of the properties of protoplanetary disks, the birthplaces of planets. This work is motivated by the rapidly increasing quality of observational data, which necessitates better theories and ways to compare them with what we observe. Firstly, we showcase how the size of the millimeter continuum emitting region constrains disk masses. We assess the method’s efficacy by conducting detailed dust evolution calculations and considering diverse disk properties, particularly in disks exhibiting radial substructures. We then constrain the disk dust grain size distribution by observing only the largest and smallest grains within it. Merging physical dust models with radiative transfer calculations, we compare the model outcomes with the observations of the IM Lup disk, revealing a segregated grain size distribution and providing new insight into grain formation mechanisms and potential triggers for planetesimal formation. Additionally, we characterize the inner disk of the very low-mass star 2MASSJ16053215-1933159 through atomic and molecular hydrogen lines. Using the observational capabilities of the James Webb Space Telescope (JWST), we measure gas temperature, mass, and the stellar accretion rate while showcasing JWST potential in the characterization of protoplanetary disk structures. Lastly, we investigate the gas density and temperature across Class II protoplanetary disks in Taurus using the NOEMA instrument. Employing machine learning-enhanced chemistry and analyzing optically thin and thick CO isotopologue emission, we successfully constrain disk masses and temperatures

PtSi Clustering In Silicon Probed by Transport Spectroscopy

Metal silicides formed by means of thermal annealing processes are employed as contact materials in microelectronics. Control of the structure of silicide/silicon interfaces becomes a critical issue when the device characteristic size is reduced below a few tens of nanometers. Here we report on silicide clustering occurring within the channel of PtSi/Si/PtSi Schottky barrier transistors. This phenomenon is investigated through atomistic simulations and low-temperature resonant tunneling spectroscopy. Our results provide evidence for the segregation of a PtSi cluster with a diameter of a few nanometers from the silicide contact. The cluster acts as metallic quantum dot giving rise to distinct signatures of quantum transport through its discrete energy states

On the Iteration Complexity of Hypergradient Computation

We study a general class of bilevel problems, consisting in the minimization of an upper-level objective which depends on the solution to a parametric fixed-point equation. Important instances arising in machine learning include hyperparameter optimization, meta-learning, and certain graph and recurrent neural networks. Typically the gradient of the upper-level objective (hypergradient) is hard or even impossible to compute exactly, which has raised the interest in approximation methods. We investigate some popular approaches to compute the hypergradient, based on reverse mode iterative differentiation and approximate implicit differentiation. Under the hypothesis that the fixed point equation is defined by a contraction mapping, we present a unified analysis which allows for the first time to quantitatively compare these methods, providing explicit bounds for their iteration complexity. This analysis suggests a hierarchy in terms of computational efficiency among the above methods, with approximate implicit differentiation based on conjugate gradient performing best. We present an extensive experimental comparison among the methods which confirm the theoretical findings.Comment: accepted at ICML 2020; 19 pages, 4 figures; code at https://github.com/prolearner/hypertorch (corrected typos and one reference

TRANSMIT: Training Research and Applications Network to Support the Mitigation of Ionospheric Threats

TRANSMIT is an initiative funded by the European Commission through a Marie Curie Initial Training Network (ITN). Main aim of such networks is to improve the career perspectives of researchers who are in the first five years of their research career in both public and private sectors. In particular TRANSMIT will provide a coordinated program of academic and industrial training, focused on atmospheric phenomena that can significantly impair a wide range of systems and applications that are at the core of several activities embedded in our daily life. TRANSMIT deals with the harmful effects of the ionosphere on these systems, which will become increasingly significant as we approach the next solar maximum, predicted for 2013. Main aim of the project is to develop real time integrated state of the art tools to mitigate ionospheric threats to Global Navigation Satellite Systems (GNSS) and several related applications, such as civil aviation, marine navigation and land transportation. The project will provide Europe with the next generation of researchers in this field, equipping them with skills developed through a comprehensive and coordinated training program. Theirs research projects will develop real time integrated state of the art tools to mitigate these ionospheric threats to GNSS and several applications that rely on these systems. The main threat to the reliable and safe operation of GNSS is the variable propagation conditions encountered by GNSS signals as they pass through the ionosphere. At a COST 296 MIERS (Mitigation of Ionospheric Effects on Radio Systems) workshop held at the University of Nottingham in 2008, the establishment of a sophisticated Ionospheric Perturbation Detection and Monitoring (IPDM) network (http://ipdm.nottingham.ac.uk/) was proposed by European experts and supported by the European Space Agency (ESA) as the way forward to deliver the state of the art to protect the range of essential systems vulnerable to these ionospheric threats. Through a set of carefully designed research work packages TRANSMIT will be the enabler of the IPDM network. The goal of TRANSMIT is therefore to provide a concerted training programme including taught courses, research training projects, secondments at the leading European institutions, and a set of network wide events, with summer schools, workshops and a conference, which will arm the researchers of tomorrow with the necessary skills and knowledge to set up and run the proposed service. TRANSMIT will count on an exceptional set of partners, encompassing both academia and end users, including the aerospace and satellite communications sectors, as well as GNSS system designers and service providers, major user operators and receiver manufacturers. TRANSMIT's objectives are: A. Develop new techniques to detect and monitor ionospheric threats, with the introduction of new prediction and forecasting models, mitigation tools and improved system design; B. Advance the physical modeling of the underlying processes associated with the ionospheric plasma environment and the knowledge of its influences on human activity; C. Establish a prototype of a real time system to monitor the ionosphere, capable of providing useful assistance to users, which exploits all available resources and adds value for European services and products; D. Incorporate solutions to this system that respond to all end user needs and that are applicable in all geographical regions of European interest (polar, high and mid-latitudes, equatorial region). TRANSMIT will pave the way to establish in Europe a system capable of mitigating ionospheric threats on GNSS signals in real tim

Fonderia Caratteri Nebiolo, 1878–1978. Nuovi studi critici

La Società Nebiolo di Torino è stata la più importante fonderia italiana di caratteri da stampa a livello nazionale e internazionale per gran parte del Novecento, fino alla sua chiusura avvenuta nel 1978. Nata da una piccola fonderia aperta nel 1852 e rilevata da Giovanni Nebiolo nel 1878, la Nebiolo venne ufficialmente costituita nel 1880. Una rapida espansione commerciale la porterà, entro la fine dell’Ottocento, a sviluppare con successo la produzione di macchine da stampa, settore nel quale dominerà il mercato italiano fino agli anni Settanta del secolo scorso. Nebiolo è ricordata soprattutto per il suo contributo nel campo dei caratteri da stampa. Lo Studio artistico – guidato in successione da Giulio Da Milano, Alessandro Butti e Aldo Novarese – ha progettato caratteri importanti che hanno segnato la storia della grafica italiana e non solo. A causa della dispersione degli archivi dell’azienda, è mancata finora una valutazione critica del suo patrimonio storico. Attraverso questo primo convegno internazionale e la pubblicazione dei suoi atti, il Nebiolo History Project offre finalmente un’ampia panoramica delle ricerche più aggiornate su aspetti finora poco indagati riguardanti la Società Nebiolo e il suo ruolo nella storia industriale e delle arti grafiche in Italia

Sample preparation strategy for the detection of steroid-like compounds using MALDI mass spectrometry imaging: pulmonary distribution of budesonide as a case study

10openInternationalItalian coauthor/editorCorticosteroids as budesonide can be effective in reducing topic inflammation processes in different organs. Therapeutic use of budesonide in respiratory diseases, like asthma, chronic obstructive pulmonary disease, and allergic rhinitis is well known. However, the pulmonary distribution of budesonide is not well understood, mainly due to the difficulties in tracing the molecule in lung samples without the addition of a label. In this paper, we present a matrix-assisted laser desorption/ionization mass spectrometry imaging protocol that can be used to visualize the pulmonary distribution of budesonide administered to a surfactant-depleted adult rabbit. Considering that budesonide is not easily ionized by MALDI, we developed an on-tissue derivatization method with Girard’s reagent P followed by ferulic acid deposition as MALDI matrix. Interestingly, this sample preparation protocol results as a very effective strategy to raise the sensitivity towards not only budesonide but also other corticosteroids, allowing us to track its distribution and quantify the drug inside lung samples.openZecchi, Riccardo; Franceschi, Pietro; Tigli, Laura; Amidani, Davide; Catozzi, Chiara; Ricci, Francesca; Salomone, Fabrizio; Pieraccini, Giuseppe; Pioselli, Barbara; Mileo, ValentinaZecchi, R.; Franceschi, P.; Tigli, L.; Amidani, D.; Catozzi, C.; Ricci, F.; Salomone, F.; Pieraccini, G.; Pioselli, B.; Mileo, V

HPLC-HRMS global metabolomics approach for the diagnosis of "olive quick decline syndrome" markers in olive trees leaves

10openInternationalItalian coauthor/editorOlive quick decline syndrome (OQDS) is a multifactorial disease affecting olive plants. The onset of this economically devastating disease has been associated with a Gram-negative plant pathogen called Xylella fastidiosa (Xf). Liquid chromatography separation coupled to high-resolution mass spectrometry detection is one the most widely applied technologies in metabolomics, as it provides a blend of rapid, sensitive, and selective qualitative and quantitative analyses with the ability to identify metabolites. The purpose of this work is the development of a global metabolomics mass spectrometry assay able to identify OQDS molecular markers that could discriminate between healthy (HP) and infected (OP) olive tree leaves. Results obtained via multivariate analysis through an HPLC-ESI HRMS platform (LTQ-Orbitrap from Thermo Scientific) show a clear separation between HP and OP samples. Among the differentially expressed metabolites, 18 different organic compounds highly expressed in the OP group were annotated; results obtained by this metabolomic approach could be used as a fast and reliable method for the biochemical characterization of OQDS and to develop targeted MS approaches for OQDS detection by foliage analysisopenAsteggiano, A.; Franceschi, P.; Zorzi, M.; Aigotti, R.; Dal Bello, F.; Baldassarre, F.; Lops, F.; Carlucci, A.; Medana, C.; Ciccarella, G.Asteggiano, A.; Franceschi, P.; Zorzi, M.; Aigotti, R.; Dal Bello, F.; Baldassarre, F.; Lops, F.; Carlucci, A.; Medana, C.; Ciccarella, G