1731 research outputs found
Sort by
Network identification via multivariate correlation analysis
Full text linkIn this thesis an innovative approach to assess connectivity in a complex network was proposed. In network connectivity studies, a major problem is to estimate the links between the elements of a system in a robust and reliable way. To address this issue, a statistical method based on Pearson’s correlation coefficient was proposed. The former inherits the versatility of the latter, declined in a general applicability to any kind of system and the capability to evaluate cross–correlation of time series pairs both simultaneously and at different time lags. In addition, our method has an increased “investigation power”, allowing to estimate correlation at different time scale–resolutions. The method was tested on two very different kind of systems: the brain and a set of meteorological stations in the Trentino region. In both cases, the purpose was to reconstruct the existence of significant links between the elements of the two systems at different temporal resolutions. In the first case, the signals used to reconstruct the networks are magnetoencephalographic (MEG) recordings acquired from human subjects in resting–state. Zero–delays cross–correlations were estimated on a set of MEG time series corresponding to the regions belonging to the default mode network (DMN) to identify the structure of the fully–connected brain networks at different time scale resolutions. A great attention was devoted to test the correlation significance, estimated by means of surrogates of the original signal. The network structure is defined by means of the selection of four parameter values: the level of significance α, the efficiency η0, and two ranking parameters, R1 and R2, used to merge the results obtained from the whole dataset in a single average behav- ior. In the case of MEG signals, the functional fully–connected networks estimated at different time scale resolutions were compared to identify the best observation window at which the network dynamics can be highlighted. The resulting best time scale of observation was ∼ 30 s, in line with the results present in the scientific liter- ature. The same method was also applied to meteorological time series to possibly assess wind circulation networks in the Trentino region. Although this study is pre- liminary, the first results identify an interesting clusterization of the meteorological stations used in the analysis
Women with children first? Parenthood, policies, and gender gaps in three European labour markets
Full text linkParenthood divides today the careers of women and men. A family gap has emerged in labour markets: Women pay economic and career prices for motherhood, while the career progression of men marches on come fatherhood. Gender inequality in paid work persists despite institutional change aimed at mitigating it or curbing it altogether. Labour market and welfare institutions have variously departed from the family wage model once supporting male breadwinning through secure, well-paid employment, surrounded by social protections. In particular, the United Kingdom, Germany, and the Netherlands moved away from this family wage model in recent decades. This move has been marked by two main transformations, namely the expansion of family leave rights and the flexibilisation of employment relationships. Yet, beyond commonalities, policy trajectories have diverged in the three countries and so have their consequences for the family gap and gender inequality more broadly.
Hence, I ask here how the family gap has shaped in the midst of akin and yet distinct changes in the labour market and welfare institutions formerly devoted to the family wage principle in the UK, Germany, and the Netherlands. By highlighting progress and stall in the ways these three countries came to modify their male breadwinner order, my main tenet is that policies aimed at women and families are not by default women- or family-friendly. The family gap, I argue, is often the unintended or perverse by-product of gradual and selective institutional change.
Throughout, this overarching question is addressed drawing on panel data analysis, quasi-experimental designs, and experimental data. Chapter I analyses whether men get a wage boost caused by fatherhood or rather select into fatherhood based on prior wages. Chapter II and III evaluate the effects of changes to parental leave and working-time legislation on the motherhood wage penalty and gender career gaps more at large, respectively. Chapter IV examines discrimination at the hiring stage in two sex-typical occupations. No overarching narrative emerges. Rather, an approach grounded on causal inference, applied to the scientific explanation of gender gaps as well as to the evaluation of social policies, is advocated for
Il voto di lista per l'elezione dell'organo amministrativo nelle società per azioni quotate: aspetti pratici e prospettive evolutive
Full text linkIl voto di lista è un istituto che il legislatore ha scelto di imporre quale unico sistema utilizzabile per l'elezione dell'organo amministrativo di tutte le società per azioni quotate a seguito dei noti scandali finanziari dei primi anni duemila e che rappresenta un unicum nel panorama internazionale.
Attesa la funzione di strumento volto a tutelare i soci di minoranza del voto di lista, il presente lavoro trae spunto da una serie di vicende verificatesi nel corso delle assemblea dei soci di alcune importanti società che hanno mostrato i limiti di tale sistema elettorale e si propone di verificare se, a fronte di questo ipotesi di fallimento dell'istituto, sia auspicabile un intervento normativo di modifica della disciplina di cui all'art. 147-ter del Testo Unico della Finanza ovvero se il dato normativo conceda rebus sic stantibus spazi di autonomia statutari sufficienti a fronteggiare le problematiche emerse nella prassi.
Nell'analizzare le caratteristiche del voto di lista si è avuto modo di rilevare come il riconoscimento a livello legislativo di un vero e proprio diritto, per i soci di minoranza, di nominare un componente dell'organo gestorio, abbia avuto inevitabili riflessi sia sul sempre sfuggente concetto di interesse sociale sia sul ruolo di cui è investito il consiglio di amministrazione, al quale non sembra potersi oggi disconoscere anche una funzione di composizione, almeno in senso lato, dei diversi interessi riferibili alle varie tipologie di soci (industriali, investitori di breve, medio o lungo periodo...).
Dall'elaborazione dei dati a sugli assetti proprietari delle società le cui assemblee si sono trovate a dover fronteggiare ipotesi di c.d. inversione della maggioranza con la minoranza è emerso come il voto di lista rischi di andare in crisi in presenza di emittenti il cui capitale è particolarmente diffuso tra il pubblico, almeno in relazione a quanto tradizionalmente si verifica in un mercato storicamente caratterizzato da assetti proprietari fortemente concentrati com'è quello italiano. Traendo in parte spunto dall'esperienza statunitense - ove al contrario la public company è realtà diffusissima - si è giunti alla conclusione per cui, pur non mancando allo stato attuale spazi di autonomia statutaria a disposizione degli emittenti per rispondere ad eventuali situazione di fallimento del voto di lista, sarebbe opportuno che il legislatore, nel medio periodo, mettesse mano alla disciplina in oggetto affiancando all'attuale sistema (che, in virtù dei suoi indubbi pregi, andrebbe comunque mantenuto obbligatorio per le società ad azionariato concentrato) un sistema elettorale alternativo che le società in cui nessun socio detenga più del 20% (massimo 30%) dei diritti di voto esercitabili nell'assemblea ordinaria potrebbero volontariamente adottare.
Il sistema immaginato si propone di realizzare una maggiore proporzionalità nella ripartizione dei seggi tra le varie liste di candidati e si caratterizza in particolare per la previsione di un obbligo per il consiglio di amministrazione uscente di presentare una propria lista e per la possibilità di votare singoli candidati anche appartenenti a liste diverse e non necessariamente una ed una sola lista in blocco
Assessing functional connectivity in the newborn brain using fNIRS
Full text linkFunctional connectivity represents a powerful approach to describe the intrinsic activity of the brain. It reveals the organization and correlations among anatomically separated regions supporting similar cognitive and sensory processes. Using functional Magnetic Resonance Imaging (fMRI), the recurrent spatial characteristics of these patterns have been extensively explored in the adult brain and their disruption has been found to be associated with psychiatric and developmental disorders. Unveiling the processes of emergence of resting state networks at a very early stage of life could shed light on the neuronal origins of these diseases. However, the study of the inception and development of functional connectivity in the newborn brain poses exceptional challenges, due to the complexity of dealing with non-compliant subjects. To this end, cortical activity at birth can be investigated using functional Near Infrared Spectroscopy (fNIRS) that represents a promising non-invasive neuroimaging method for developmental studies.
In the present thesis, I applied fNIRS to assess functional connectivity in term neonates. The first part of the dissertation is dedicated to investigating the maturation of a specific resting state network, the Default Mode Network, within the first 48 hours of life. The study aimed to examine its emergence, for the first time, using optical imaging on newborns immediately after birth. While the majority of fMRI literature focused on large-scale spatial patterns, I took a different approach measuring an intrinsic and localized fingerprint feature of the network, consistently detected in adult subjects.
In the second part of the dissertation, I aimed at improving the anatomical representation of brain connectivity, inferred only from signals collected at the scalp. Thus, I developed and validated a method for the reconstruction of spatially distributed functional signals on a dedicated template for term newborn subjects. The intent is to promote the shift from a sensor space description (one signal for each channel) to a source space representation in which the origin of the signal is reconstructed with better anatomical fidelity. The reliability of the reconstruction method was tested on synthetic and real data. In the former case, I simulated spatially correlated neural activity in the cortex, thus enabling assessment of the reconstructed images against a ground-truth map.
Analyses of functional connectivity in both sensor and source space showed that the Default Mode Network is still immature at birth, with a lack of homotopic correlation in the lateral parietal cortices, and no evidence of anticorrelation with the Dorsal Attention Network, a well established feature in the adult brain.
Overall the work presented in the thesis contributes to the understanding of functional connectivity in the infant’s brain and provides useful tools for source-based connectivity analysis and for probe design and optimization
Simple objects in the heart of a t-structure
Full text linkHistorically, the study of modules over finite dimensional algebras has started with the study of the ones with finite dimension. This is sufficient when dealing with a finite dimensional algebra of finite representation type, where there are only finitely many indecomposable modules of finite length. Indecomposable modules of infinite length occur when dealing with algebras of infinite representation type and the study of pure-injective modules over a finite dimensional algebra is crucial for the problem of describing infinite dimensional modules. In this talk, we consider a specific class of finite dimensional algebras of infinite representation type, called "tubular algebras". Pure-injective modules over tubular algebra have been partially classified by Angeleri Hügel and Kussin, in 2016, and we want to give a contribution to the classification of the ones of "irrational slope". In this talk, first, via a derived equivalence, we move to a more geometrical framework, ie. we work in the category of quasi-coherent sheaves over a tubular curve, and we approach our classification problem from the point of view of tilting/cotilting theory. More precisely, we consider specific torsion pairs cogenerated by infinite dimensional cotilting sheaves and we study the Happel-Reiten-Smalø heart of the corresponding t-structure in the derived category. These hearts are locally coherent Grothendieck categories and, in these categories, the pure-injective sheaves over the tubular curve become injective objects. In order to study injective objects in a Grothendieck category is fundamental the classification of the simple objects. In the seminar, we use some techniques coming from continued fractions and universal extensions to provide a method to construct an infinite dimensional sheaf of a prescribed irrational slope that becomes simple in the Grothendieck category given as the heart of a precise t-structure
Decision Support of Security Assessment of Software Vulnerabilities in Industrial Practice
Full text linkSoftware vulnerabilities are a well-known problem in current software projects. The situation becomes even more complicated, due to the ever-increasing complexity of the interconnections between both commercial and free open-source software (FOSS) projects. In this dissertation, we are aiming to facilitate the security assessment process in an industrial context.
We start from the level of the own code of an individual software project, for which we propose a differential benchmarking approach for automatic assessment of static analysis security testing tools. We have demonstrated this approach, using 70 revisions of four major versions of Apache Tomcat with 62 distinct vulnerability fixes as a ground-truth set to test 7 tools.
Since modern software projects often import functionality via software dependencies, that can also introduce vulnerabilities into the dependent project, we propose a methodology for counting actually vulnerable dependencies. We have evaluated the methodology on the set of 200 most used industry-relevant FOSS libraries, that resulted in 10905 distinct library instances when considering all the library versions.
Finally, we have investigated the situation on the level of the FOSS ecosystem. Here we have studied decision-making strategies of developers for selecting and updating dependencies, as well as the influence of security concerns on the developers' decisions from quantitative and qualitative perspectives. For the qualitative study we have run 15 semi-structured interviews with software developers from 15 companies located in 7 countries
La pena dell'esilio e l'umanesimo di Andrea Alciato. Fonti, tradizione, filologia
No full textIl quesito sulla natura e sui caratteri dell'incontro fra il bando-esilio di tradizione 'medievale' e la cultura umanistica della prima generazione di 'giuristi-umanisti', agli inizi del XVI secolo, è all'origine di una ricerca che ha l'intento di fornire un contributo nuovo agli studi sulle dottrine di ius commune sul bando. L'indagine ha avuto come oggetto l'opera di Andrea Alciato, eletto a rappresentante primo di quella generazione, ed è dunque stata estesa a Guillaume Budé e a Ulrich Zasius, nel dialogo fra i membri del cosiddetto Triumvirato umanistico. Ne è emerso un quadro culturale europeo comune e diffuso, dove la continuità della dottrina umanistica rispetto alla tradizione medievale sul bando si arricchisce degli apporti nuovi del sapere 'pluridisciplinare', storico-filologico e giuridico, proprio dei nuovi intellettuali
THz Radiation Detection Based on CMOS Technology
Full text linkThe Terahertz (THz) band of the electromagnetic spectrum, also defined as sub-millimeter waves, covers the frequency range from 300 GHz to 10 THz. There are several unique characteristics of the radiation in this frequency range such as the non-ionizing nature, since the associated power is low and therefore it is considered as safe technology in many applications. THz waves have the capability of penetrating through several materials such as plastics, paper, and wood. Moreover, it provides a higher resolution compared to conventional mmWave technologies thanks to its shorter wavelengths.
The most promising applications of the THz technology are medical imaging, security/surveillance imaging, quality control, non-destructive materials testing and spectroscopy.
The potential advantages in these fields provide the motivation to develop room-temperature THz detectors. In terms of low cost, high volume, and high integration capabilities, standard CMOS technology has been considered as an excellent platform to achieve fully integrated THz imaging systems.
In this Ph.D. thesis, we report on the design and development of field effect transistor (FET) THz direct detectors operating at low THz frequency (e.g. 300 GHz), as well as at higher THz frequencies (e.g. 800 GHz – 1 THz). In addition, we investigated the implementation issues that limit the power coupling efficiency with the integrated antenna, as well as the antenna-detector impedance-matching condition. The implemented antenna-coupled FET detector structures aim to improve the detection behavior in terms of responsivity and noise equivalent power (NEP) for CMOS based imaging applications.
Since the detected THz signals by using this approach are extremely weak with limited bandwidth, the next section of this work presents a pixel-level readout chain containing a cascade of a pre-amplification and noise reduction stage based on a parametric chopper amplifier and a direct analog-to-digital conversion by means of an incremental Sigma-Delta converter. The readout circuit aims to perform a lock-in operation with modulated sources. The in-pixel readout chain provides simultaneous signal integration and noise filtering for the multi-pixel FET detector arrays and hence achieving similar sensitivity by the external lock-in amplifier.
Next, based on the experimental THz characterization and measurement results of a single pixel (antenna-coupled FET detector + readout circuit), the design and implementation of a multispectral imager containing 10 x 10 THz focal plane array (FPA) as well as 50 x 50 (3T-APS) visible pixels is presented. Moreover, the readout circuit for the visible pixel is realized as a column-level correlated double sampler. All of the designed chips have been implemented and fabricated in 0.15-µm standard CMOS technology. The physical implementation, fabrication and electrical testing preparation are discussed
Mixtures of ultracold Bose gases in one dimension: A Quantum Monte Carlo study
Full text linkIn this thesis we investigate the properties of mixtures of Bose gases in one dimensions at zero temperature using quantum Monte-Carlo methods. First we investigate the limiting case of an impurity interacting with an atomic bath. We characterize the impurity, by calculating its effective mass, binding energy as well as the contact parameter between the impurity and the bath. In particular, we find that the effective mass rapidly increases to very large values when the impurity gets strongly coupled to an otherwise weakly repulsive bath. Then we describe uniform balanced mixtures with repulsive interactions. We investigate the miscibility phase diagram of the two components and find that correlations do not alter the phase diagram predicted by mean-field theories. We investigate the Andreev-Bashkin effect , a non-dissipative drag between the the two components of the gas and find that the drag becomes very large in the strongly interacting regime. In non-homogeneous systems we also investigate the frequency of the spin-dipole mode. Finally we describe mixtures with attractive inter-species interactions, where one can obtain a liquid ground state because of the competition between the inter-species attraction and intra-species repulsion. We characterize the the liquid and we find that the liquid state can be formed if the ratio of coupling strengths between inter-species attractive and intra-species repulsive interactions exceeds a critical value
Precursor miRNAs are locally processed to regulate growth cone steering
Full text linkDuring the development of the nervous system, axons grow and generate a complex network of interconnected neurons. To establish these connections, the tip of the growing
axon, the growth cone, is guided by chemotropic cues en route to its target with exquisite precision. Axons must sometimes navigate a significant distance before reaching their final destination. As an alternative to energy-expensive protein transport from distant cell bodies, seminal studies have revealed that growth cones rely on local mRNA translation to generate certain proteins acutely on demand. These cue-induced newly synthesized proteins contribute to fuel growth cone steering.
Several groups reported the presence of Dicer at growth cones, and I observe the presence of endogenous Dicer in RGC axons of FLAG-HA2-Dicer transgenic mice. These observations raise the intriguing possibility that not only proteins but also miRNAs could be produced locally in this compartment. In my work, I have therefore explored whether
miRNA biogenesis occurs locally within growth cone and if this is important for growth cone steering, using Xenopus laevis retinal ganglion cell (RGC) axons as a model.
Specific precursor microRNAs (pre-miRNAs) are detected in pure Xenopus RGC axonal preparations by miRNA-seq and PCR, and endogenous pre-miR-181a-1 is actively tracked to distal axons by hitchhiking on vesicles. Upon exposure to Sema3A, but not Slit-2, pre-miR-181a-1/a-2 are processed within axons by Dicer into newly generated miRNAs (NGmiRNAs). In contrast, pre-miR-182 remains unprocessed upon Sema3A
exposure, highlighting a mechanism that is not only cue-, but also pre-miRNA molecule specific. Inhibiting NGmiRNAs in axons abolishes growth cone responsiveness to cues
ex vivo. miRNAs are thus locally produced and these newly generated miRNAs mediate cue-induced growth cone steering.
To deepen mechanistic insights, I assess whether newly generated miRNAs silence the translation of specific mRNAs in response to cues using FRAP analysis with a Venus reporter.
I observe that APP and TUBB3 are locally translated in axons in basal conditions and that are both silenced in response to Sema3A. I uncover that this cue-induced silencing of TUBB3 is mediated by newly generated miRNAs specifically in axons ex vivo and in vivo.
Taken together, these results indicate that newly generated miRNAs gate cue-induced silencing of a specific subset of mRNAs in time and space, thereby regulating growth
cone behavior. Local biogenesis of miRNAs in axons constitute an important additional
regulatory layer in the complex mechanism of axon targeting