1731 research outputs found
Sort by
Dove ballano i moldavi la terra geme: etnografia su una pratica culturale in emigrazione
No full textLa migrazione è un processo di cambiamento socio-economico, ma anche socio-culturale. Numerosi studi hanno messo in evidenza le modalità attraverso le quali concezioni culturali e pratiche sociali pre-migratorie persistono nei paesi di destinazione. A questo scopo è stata condotta una lunga osservazione etnografica su un flusso migratorio consolidatosi nell’ultimo decennio tra la Moldavia e un’area di insediamento dell’Italia settentrionale, focalizzandosi sull’uso e il significato della danza tradizionale nel nuovo contesto. Lo studio etnografico multi-situato presentato è partito dall’ipotesi che nel cambiamento dal Paese d’origine a quello di destinazione anche ciò che appare come pervicace mantenimento delle «tradizioni» sia attraversato da processi di adattamento, innovazione e creatività. Si è voluto pertanto scandagliare il peso dell’innovazione e della creatività nella «riproduzione» culturale in emigrazione.
Dopo aver chiarito in quali situazioni, con quali modalità e con quale attribuzione di significati si danza nel Paese d’origine, vengono descritti i contesti e i luoghi in cui i migranti danzano, e analizzate similitudini e differenze tra la pratica in emigrazione e quella nel Paese d’origine. Viene poi affrontato il tema della costruzione e attribuzione di significato alla danza nel contesto di destinazione, e il processo attraverso il quale essa diventa un atto identitario. L’analisi si sofferma anche sui canali e sui processi di trasmissione della danza in emigrazione, mettendo di volta in volta in evidenza gli elementi che la differenziano da quella che ha luogo in Moldavia. Vengono approfondite le caratteristiche dell’infrastruttura organizzativa che nasce nel contesto di destinazione per garantire il mantenimento della pratica della danza e la sua fruizione anche al di fuori del contesto familiare, considerando sia l’impianto organizzativo che emerge dal rapporto tra migranti e istituzioni locali sia l’infrastruttura nata per rispondere alla richiesta di intrattenimento espressa dalla comunità moldava in emigrazione. Oltre a mettere in luce gli elementi che differenziano questi meccanismi organizzativi da quelli utilizzati nel Paese d’origine, si descriveranno i contatti transnazionali richiesti dal funzionamento dell’infrastruttura deputata al mantenimento della danza. Infine, viene discusso il valore della pratica della danza come strumento di rappresentazione dei migranti moldavi all’estero e di rappresentanza nel momento in cui subentrano delle forme di riconoscimento istituzionale
Coating for energetic and sensing applications
No full textThis work explores the possibility to enhance the performance of photovoltaic devices through Wavelength Shifting and Luminescent Solar Concentration. New matrices for these applications, namely parylene, polysiloxane and fluorinated polyimide have been successfully tested
Imprevedibilmente sospesi tra stabilizzazione e istituzionalizzazione: uno studio sugli spin-off della ricerca universitaria
No full textIl presente lavoro si inserisce nell’ampio filone di studi che nel corso degli anni ha indagato i modi in cui nuove forme organizzative si stabilizzano e, in un secondo momento, si istituzionalizzano, diventando modi di agire dati per scontati in un determinato mercato, settore economico e/o società.
In particolare, si è scelto di guardare alla tematica delle nuove forme organizzative dalla prospettiva delle reti d’azione, considerando come oggetto di studio i processi organizzativi innovativi e focalizzandosi quindi sui modi in cui da questi emergono e, eventualmente, si stabilizzano e/o si istituzionalizzano alcune reti d’azione. Per inserirsi in maniera originale in questo dibattito si sono presi in considerazione gli spin-off universitari, intesi come processi in cui gruppi di membri dell’università, fondano una propria impresa al fine di commercializzare idee, risultati scientifici e prototipi tecnologici derivanti dalla ricerca accademica. Coerentemente con la lente teorica di riferimento ci si è approcciati a questo fenomeno domandandosi "É possibile che dai processi di spin-off emergano forme organizzative stabilizzate e/o istituzionalizzate? In tal caso, come?”.
Per rispondere a queste domande si è scelta la Grounded Theory e si sono utilizzate le tecniche dell’osservazione diretta, dell’intervista etnografica e dell’analisi dei documenti al fine di raccogliere dati empirici da cui emerga una spiegazione teorica del fenomeno. Seguendo la logica del campionamento teorico, parallelamente alla raccolta e all’analisi dati, si è arrivati a scegliere tre casi di spin-off, diversi per anzianità e contesto di appartenenza.
La ricerca ha raggiunto principalmente due tipi di contributi. In primo luogo si è mostrato come le forme organizzative nate dai processi di spin-off, inizialmente pensate come modi di trasformare i risultati della ricerca universitaria in prodotti e/o servizi commerciabili, siano al centro di processi di banalizzazione che le rendono simili nelle logiche e nei modelli d’azione a qualsiasi altra forma organizzativa presente nel contesto economico-sociale di riferimento. In secondo luogo, si sono analizzate le complesse e contraddittorie relazioni esistenti tra stabilizzazione e istituzionalizzazione, sottolineando che non necessariamente il rapporto tra tali processi è sequenziale, uno può sfociare nell’altro e viceversa, contribuendo a cambiare, in maniera più o meno radicale, l’ordine istituzionale esistente
Analysis and Development of an Innovative Prefabricated Beam-to-Column Joint
No full textThe use of pre-fabricated concrete components and their related coupling systems in seismic engineering constitutes a subject of wide and deep interest among researchers, practitioners and manufacturers all over the world, as demonstrated by a large number of studies conducted, among other Countries, especially in Japan, New Zealand and United States since the early ‘80s and, in relatively more recent times, in Italy. A key issue is given by the possibility to apply the typical benefits of the pre-fabrication not only to low rise industrial/commercial structures, but also to multi-storey frames for public and strategic buildings such as schools, hospitals and many others, as well as to high-rise residential premises built in areas characterized by a medium to high seismic intensity. On the basis of what stated above, an original structural system made by prefabricated composite steel truss-concrete beams and centrifuged high-strength concrete columns is presented in the following. Specifically designed joints are provided to couple the different structural components in order to guarantee an overall ease of construction with reduced tolerance problems and self-bearing capacity during temporary erection phases, with a consequent reduction in schedule and costs. The use of high performance concrete for columns allows for a high bearing capacity with limited overall dimensions and the consequent maximization of the commercial or saleable space. The original layout of the system proposed has led to the need to perform an intensive theoretical and experimental research activity. The finite element model of the structural system was calibrated upon both static and cyclic testing evidence carried out on full scale samples built in Italy and tested at the Tongji University-Shanghai, China. On the basis of the data collected, the tuned model was used to carry out further analyses and to deepen the specific knowledge on several further aspects, as specified in the following. Firstly, an estimation of the joint’s strength domain, suitable for everyday’s design was carried out based on a component-approach. Then, a structural optimization on the component used to guarantee hogging and sagging bending moment resistance to the joint, was carried out in order to achieve the minimization of the construction material employed. Furthermore, the estimation of the seismic performance of the joint, based on the evaluation of a purposely defined vulnerability parameter, supplied encouraging results with reference to the applicability of the investigated technology over most of the National territory. Finally an improved layout of the joint, with reference to confined concrete and the related possibility to achieve a suitable seismic response also at edge joints, is presented
Il diritto alla salute a geometria variabile
No full textNella trattazione si svolge un'analisi di una delle molteplici dimensioni del diritto alla salute, ossia il diritto ad ottenere prestazioni sanitarie. Il principio d'eguaglianza formale e sostanziale costituisce il filo rosso della disamina, svolta attraverso l'impiego del metodo comparato e finalizzata alla verifica del grado di somiglianza o diversità tra gli ordinamenti presi in considerazione. Sono stati a tal fine prescelti i sistemi italiano, britannico e spagnolo poiché essi, oltre a condividere l'adozione del medesimo modello di sistema sanitario di tipo universalista, sono anche caratterizzati da una decentralizzazione asimmetrica nella forma di Stato, che incide profondamente sulle modalità della garanzia del diritto e sulla sua concretizzazione rispetto al territorio. Ci si sofferma, inoltre, sulle nuove “sfide” che il diritto dell'Unione Europea reca con sé in questo campo.
Lo studio della configurazione costituzionale del diritto alla salute in ciascun ordinamento, della sua articolazione in relazione all'assetto decentralizzato dello Stato e, infine, del crescente spazio di intervento dell'Unione Europea in materia di salute porteranno ad individuare alcune linee comuni, pur all'interno di una (relativa) diversità dei punti di partenza e degli strumenti adottati in ciascuno Stato per rispondere a problemi tendenzialmente comuni.
Il diritto costituzionale alla salute viene così (ri)qualificato come una situazione giuridica a fattispecie complessa, ma in sé unitaria, proponendo l'abbandono della tradizionale distinzione tra una dimensione cd. fondamentale ed una cd. sociale dello stesso. Si tratta, dunque, di un diritto a tutela “graduale”, che si misura nell'ampiezza dello spazio di discrezionalità lasciato al legislatore per assicurarne la garanzia, cui corrisponde, in modo inversamente proporzionale, una gradazione del potere di controllo giurisdizionale.
In tale contesto emergono anche le istanze talora centrifughe e talaltra centripete nella tutela del diritto alla salute in ordinamenti caratterizzati da un assetto decentralizzato, ove si rinviene la tendenza a trovare risposte territoriali a problemi locali, in tensione con l'esigenza di garantire un adeguato livello d'eguaglianza intersoggettiva sull'intero territorio nazionale. Le soluzioni (fra loro parzialmente differenti) di ciascun ordinamento conducono al comune risultato di privilegiare l'adozione di decisioni condivise attraverso procedimenti in cui sia previsto il coinvolgimento dei soggetti interessati.
Sarà, infine, possibile tracciare il profilo di un diritto delle prestazioni sanitarie, da intendersi come sistema di tutele soggettive per l'accesso a trattamenti medici, alla luce anche dei “nuovi” vincoli che derivano dall'ordinamento dell'Unione Europea. Affiorano alcuni elementi comuni, che rappresentano le modalità di garanzia di effettività del diritto alla salute, con riguardo al profilo preso in esame, e che possono trovare eguale applicazione a livello sovranazionale, nazionale e anche territoriale.
In questo modo, il cd. procedure-oriented approach, i principi di condivisone e compartecipazione nell'adozione delle scelte relative alla salute, nonché la garanzia di un controllo giurisdizionale delle decisioni costituiscono un modello di tutela del diritto alla salute che si presta ad una circolazione virtuosa all'interno dello spazio europeo
Spacetime metrology with LISA Pathfinder
No full textLISA is the proposed ESA-NASA space-based gravitational wave detector in the 0.1 mHz - 0.1 Hz band. LISA Pathfinder is the down-scaled version of a single LISA arm. In this thesis it is shown that the arm -- named Doppler link -- can be treated as a differential accelerometer, measuring the relative acceleration between test masses. LISA Pathfinder -- the in-flight test of the LISA instrumentation -- is currently in the final implementation and planned to be launched in 2014. It will set stringent constraints, with unprecedented pureness, on the ability to put test masses in geodesic motion to within the required differential acceleration of 3\times10^{-14} m s^{-2} Hz^{-1/2} and track their relative motion to within the required differential displacement measurement noise of 9\times10^{-12} m Hz^{-1/2}, at frequencies relevant for the detection of gravitational waves. Given the scientific objectives, it will carry out -- for the first time with such high accuracy required for gravitational wave detection -- the science of spacetime metrology, in which the Doppler link between two free-falling test masses measures the spacetime curvature. This thesis contains a novel approach to the calculation of the Doppler response to gravitational waves. It shows that the parallel transport of 4-vectors records the history of gravitational wave signals passing through photons exchanged between an emitter and a receiver. In practice, the Doppler link is implemented with 4 bodies (two test masses and two spacecrafts) in LISA and 3 bodies (two test masses within a spacecraft) in LISA Pathfinder. Different non-idealities may originate in the measurement process and noise sources couple the motion of the test masses with that of the spacecraft. To compensate for such disturbances and stabilize the system a control logic is implemented during the measurement. The complex closed-loop dynamics of LISA Pathfinder can be condensed into operators acting on the physical coordinates describing the relative motion. The formalism can handle the couplings between the test masses and the spacecraft, the sensing noise, as well as the cross-talk, and allows for the system calibration. It suppresses the transients in the estimated residual acceleration noise between the test masses. The scope of system identification is indeed the calibration of the instrument and the compensation of different effects. After introducing a model for LISA Pathfinder along the optical axis and an example of cross-talk from other degrees of freedom to the optical axis, this thesis describes some data analysis procedures applied to synthetic experiments and tested on a realistic simulator provided by ESA. The same procedures will also be adopted during the mission. Those identification experiments can also be optimized to get an improvement in precision of the noise parameters that the performances of the mission depend on. This thesis demonstrates the fundamental relevance of system identification for the success of LISA Pathfinder in demonstrating the principles of spacetime metrology needed for all future space-based missions
Response of Flush End-Plate Joints under Combined Actions
No full textIn this work, aspects concerning the behaviour of steel joints under combined actions are investigated. Adopting the philosophy of the component method the attention focused on the analysis of a basic component of the connection: the T-stub. Research works carried out in the recent past extensively investigated the T-stub response under tension, while no data are available for the T-stub's response under combined tension (N) and shear force (V). In the thesis experimental, numerical and theoretical studies on this topic are presented.
The starting point is the experimental activity carried out at University of Trento on column T-stubs under different combinations of axial and shear force. The experimental outcomes strongly highlighted the influence of the loading conditions on the strength and deformation capacity of the T-stub. In a second phase 3D numerical models were developed and calibrated to reproduce the actual behaviour of the T-stubs. The numerical simulations were then extended to different specimen geometries to investigate the main geometrical parameters which could affect the T-stub response.
On the basis of experimental and numerical data a theoretical model based on limit analysis was then developed. It allows predicting a simplified load-displacement curve of the T-stub under a generic combination of N and V. The results obtained from the analytical model seem to reproduce with sufficient accuracy the complex behaviour of the T-stub, allowing to appraise the elastic stiffness and the yield load
Silicon nanocrystals: from bio-imager to erbium sensitizer
No full textThe work in this thesis has been centred on the light emitting properties of silicon nanocrystals and the possible applications of this particular material platform to various topics ranging from bio-imaging to erbium ion sensitization. Silicon nanocrystals as bio-imaging agent have been investigated by employing colloidal dispersion of individual silicon nanocrystals where surface properties could be controlled to a great extent. By using a suitable functionalization scheme, high quality hydrophilic luminescent nanoparticles were produced. Using the improvements in the physical coating, bio-imaging on living cells (in vitro) was demonstrated showing that silicon nanocrystals have a great potential in bio-imaging and offer a promising alternative to commonly used fluorescence dyes.
A part from being good light emitters, silicon nanocrystals could also amplify the light. This is a reason why the part of the work in this thesis has been dedicated to the investigation of silicon nanocrystals as a gain material. While most of the studies on this topic are concentrated on the nanocrystal surface as a driving mechanism behind the optical amplification, the work presented in this thesis concerns the study of a zero phonon (direct) optical transition as a possible source of optical amplification in this material system. To this scope, investigation of the dynamics of the system on a nanosecond time-scale and under high excitation conditions has been employed. Additional insight on ultrafast dynamics has been obtained by using optical cavities in the form of optically active free-standing micro-disk resonators.
Finally, in the last part of this thesis a study of Er3+-doped Silicon-Rich-Oxide (SRO) materials and Er3+-doped SRO based devices is presented. This part of the work differs from the rest of the work reported in this thesis as is not focused on the light emitting properties of silicon nanocrystals but mostly on their non-radiative process engineering (energy transfer to erbium ions). Er3+ doped SRO opens the route towards compact waveguide amplifiers and lasers and allows for the possibility of electrical injection schemes, which are not realizable in standard erbium amplifiers used in EDFA for telecom applications. To that end, novel opto-electronic structures were proposed, modeled and manufactured and preliminary results of their performance were presented.
The sensitization mechanism between silicon nanoparticles and erbium ions was studied and its complex nature was illustrated. Although, the acquired knowledge of physics involved was not sufficient for formulation of a complete working theory of the energy transfer process, some important physical aspects of this process have been elucidated paving the way towards its complete understanding
Ranking Aggregation Based on Belief Function Theory
No full textThe ranking aggregation problem is that to establishing a new aggregate ranking given a set of rankings of a finite set of items. This problem is met in various applications, such as the combination of user preferences, the combination of lists of documents retrieved by search engines and the combination of ranked gene lists.
In the literature, the ranking aggregation problem has been solved as an optimization of some distance between the rankings overlooking the existence of a true ranking. In this thesis we address the ranking aggregation problem assuming the existence of a true ranking on the set of items: the goal is to estimate an unknown, true ranking given a set of input rankings provided by experts with different approximation quality.
We propose a novel solution called Belief Ranking Estimator (BRE) that takes into account two aspects still unexplored in ranking combination: the approximation quality of the experts and for the first time the uncertainty related to each item position in the ranking. BRE estimates in an unsupervised way the true ranking given a set of rankings that are diverse quality estimations of the unknown true ranking.
The uncertainty on the items's position in each ranking is modeled within the Belief Function Theory framework, that allows for the combination of subjective knowledge in a non Bayesian way.
This innovative application of belief functions to rankings, allows us to encode different sources of a priori knowledge about the correctness of the ranking positions and also to weigh the reliability of the experts involved in the combination.
We assessed the performance of our solution on synthetic and real data against state-of-the-art methods. The tests comprise the aggregation of total and partial rankings in different empirical settings aimed at representing the different quality of the input rankings with respect to the true ranking. The results show that BRE provides an effective solution when the input rankings are heterogeneous in terms of approximation quality with respect to the unknown true ranking
Advanced Methods for the Retrieval of Geo-/Bio-Physical Variables from Remote Sensing Imagery
No full textThe retrieval of geo-/bio-physical variables from remote sensing imagery is a challenging and important research field. On the one hand, advances in electronics, engineering and space sciences are offering to the users community new sensors capable to acquire information on the Earth surface with higher accuracy and improved features with respect to the past. On the other hand, the need of large-scale, accurate and up-to-date mapping and monitoring of natural targets and physical processes is becoming fundamental for many application domains. This calls for the development of accurate, robust and effective retrieval methodologies.
The main goal of this thesis is to investigate and develop advanced methods and systems for the retrieval of geo-/bio-physical variables from satellite remote sensing imagery being able to exploit the potential of new and upcoming satellite systems and support real application domains. Special attention has been devoted to the definition of methods and to the analysis of data acquired in the challenging mountain environment.
The activity carried out and presented in this dissertation is oriented to investigate the main limitations of the existing methodologies for addressing the estimation problem and to develop novel and improved systems that can overcome the drawbacks identified. In particular, the following main novel contributions are proposed in this thesis:
a) A theoretical and empirical comparative analysis of non-linear machine learning regression methods, namely the Multi-Layer Perceptron Neural Network and the Support Vector Regression, for soil moisture retrieval in different operational scenarios.
b) A novel multi-objective model-selection strategy for tuning the free parameters of non-linear regression methods taking into account different quality metrics that are jointly optimized.
c) A novel hybrid approach to the retrieval of geo-/bio-physical variables from remote sensing data integrating both theoretical electromagnetic models and field reference measurements.
d) A sensitivity analysis and a retrieval system for soil moisture content estimation from new generation SAR imagery in an Alpine catchment.
e) An empirical study on the effectiveness of fully-polarimetric SAR signals for soil moisture estimation in mountain areas.
f) An improved algorithm for mapping and monitoring Green Area Index (GAI) in Alpine pastures and meadows from satellite MODIS imagery.
Qualitative and quantitative experimental results obtained on real remotely sensed data confirm the effectiveness of the proposed solutions