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L'archivio del Capitolo della Cattedrale di Trento: produzione e conservazione documentaria (secoli XIII - XX): con un'edizione delle più antiche pergamene (1147-1250)
No full textLo sviluppo delle forme di produzione e conservazione dei documenti del Capitolo della cattedrale di Trento può essere sommariamente distinto in tre fasi: nella prima, risalente al secolo XIII, l'Archivio capitolare si presentava come un tipico archivio thesaurus. Dagli ultimi anni del Duecento e in maniera più decisa nei due o tre secoli successivi, dal XIV all'inizio del XVI, si può invece collocare una fase di sperimentazione e di stabilizzazione delle modalità di produzione e di conservazione dei documenti, propedeutica alla fase che si aprì con la seconda metà del Cinquecento, quando cominciarono a formarsi strutture tipiche di una cancelleria. In questo processo è possibile riconoscere alcune caratteristiche che accomunano la storia dell'Archivio capitolare a quella di altre realtà ecclesiastiche e laiche dellâItalia centro-settentrionale e in generale di tutta l'area alpina e centro europea. La varietà di situazioni locali, tuttavia, non permette di individuare "tipologie evolutive" o modelli transitati da una realtà all'altra, ma solo "linee di tendenza comuni: lo studio della formazione dei sistemi documentari nei diversi centri permette di individuare una struttura comune e comprensibile nelle sue linee essenziali. Essi però si organizzano secondo schemi di razionalità legati alle idee di necessitas e di utilitas, che costituiscono dei criteri di relatività, mutuati fra l'altro dalla cultura ecclesiastica". In questa prospettiva, è importante tenere in particolare considerazione alcuni elementi, peraltro tra loro collegati, quali il passaggio dalla tipologia dell'archivio thesaurus a quella dell'archivio di sedimentazione, l'utilizzo del registro e la formazione delle serie di registri, il ruolo del notariato.
Nel primo capitolo della tesi si cercherà di far luce sulle modalità di conservazione della documentazione e in generale sulle condizioni dell'Archivio del Capitolo dalle sue origini fino ad oggi. Il secondo capitolo sarà invece dedicato alla produzione documentaria. Nel terzo saranno focalizzati i sistemi di amministrazione dei beni dei canonici. Nel quarto capitolo, infine, si formuleranno alcune ipotesi conclusive, raccordando quanto descritto analiticamente nelle pagine precedenti.
In conclusione si propone l'edizione delle più antiche pergamene conservate nell'Archivio capitolare (1147 - 1250)
New Strategies for Computing Gröbner Bases
No full textGröbner bases are special sets of polynomials, which are useful to solve problems in many fields such as computer vision, geometric modeling, geometric theorem proving, optimization, control theory, statistics, communications, biology, robotics, coding theory, and cryptography.
The major disadvantage of algorithms to compute Gröbner bases is that computations can use a lot of computer power. One of the reasons is the amount of useless critical pairs that the algorithm has to compute. Hence, a lot of effort has been put into developing new criteria to detect such pairs in advance.
This thesis is devoted to describe efficient algorithms for the computation of Gröbner bases, with particular emphasis to those based on polynomial signatures. The idea of associating each polynomial with a signature on which the criteria and reduction steps depend, has become extremely popular in part due to its good performance.
Our main result combines the criteria from Gao-Volny-Wang's algorithm with the knowledge of Hilbert Series. A parallel implementation of the algorithm is also investigated to improve the computational efficiency. Our algorithm is implemented in CoCoALib, a C++ free library for computations in commutative algebra
Computer simulation of electron transport in solids with applications to materials analysis and characterization
No full textMonte Carlo (MC) technique allows solving mathematical and physical problems of great complexity. One of the main topics that can be approached using the MC strategies concerns the study of the electron-solid interaction (transport MC).
Transport MC allows predicting the behavior of charged particles traveling through the matter and it has been widely utilized in many applications. Among them, on the side of the chemical analysis of the surfaces and the interfaces of materials, let us mention Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Reflection Electron Energy Loss Spectroscopy (REELS), and Auger Electron Spectroscopy (AES).
Concerning the simulation of the backscattering coefficient, it can be utilized for evaluating the chemical composition of the target, for measuring the thickness of thin surface films -- even in case of multi-layered structures, and so on. Regarding the secondary electron emission, MC simulation can be used for the study of image contrast in silicon p-n junctions, for line-scan calculations of resist materials with given geometrical cross-sections deposited on silicon substrates, etc.
The aim of this work is to investigate some physical problems related to the transport of electrons in solid targets. The theoretical results will be validated through a comparison with the available experimental data
Security of Publish/Subscribe Systems
No full textThe increasing demand for content-centric applications has motivated researchers to rethink and redesign the way information is stored and delivered on the Internet. Increasingly, network traffic consists of content dissemination to multiple recipients. However, the host-centric architecture of the Internet was designed for point-to-point communication between two fixed endpoints. As a result, there is a mismatch between the current Internet architecture and current data or content-centric applications, where users demand data, regardless of the source of the information, which in many cases is unknown to them.
Content-based networking has been proposed to address such demands with the advantage of increased efficiency, network load reduction, low latency, and energy efficiency. The publish/subscribe (pub/sub) communication paradigm is the most complex and mature example of such a network. Another example is Information Centric Networking (ICN), a global-scale version of pub/sub systems that aims at evolving the Internet from its host-based packet delivery to directly retrieving information by name. Both approaches completely decouple senders (or publishers) and receivers (or subscribers) being very suitable for content-distribution applications or event-driven applications such as instant news delivery, stock quote dissemination, and pervasive computing. To enable this capability, at the core of pub/sub systems are distributed routers or brokers that forward information based on its content. The basic operation that brokers need to perform is to match incoming messages or publications against registered interests or subscriptions.
Though a lot of research has focused on increasing the networking efficiency, security has been only marginally addressed. We believe there are several reasons for this. First of all, security solutions designed for point-to-point communication such as symmetric-key encryption do not scale up to pub/sub systems or ICN applications, mainly because publishers and subscribers are decoupled and it is infeasible for them to establish or to maintain contact and therefore to exchange keying material. In this thesis we analyse several such emerging applications like Smart Energy Systems, Smart Cities and eHealth applications that require greater decoupling of publishers and subscribers, and possible full decoupling.
Second, in large applications that run over public networks and span several administrative domains, brokers cannot be trusted with the content of exchanged messages. Therefore, what pub/sub systems need are solutions that allow brokers to match the content of publications against subscriptions without learning anything about their content. This task is made even more difficult when subscriptions are complex, representing conjunctions and disjunctions of both numeric and non-numeric inequalities. The solutions we surveyed were unable to provide publication and subscription confidentiality, while at the same time supporting complex subscription filters and keeping key management scalable.
Another challenge for publish/subscribe systems is enforcing fine-grained access control policies on the content of publications. Access control policies are usually enforced by a trusted third party or by the owner holding the data. However, such solutions are not possible for pub/sub systems. When brokers are not trusted, even the policies themselves should remain private as they can reveal sensitive information about the data.
In this thesis we address these challenges and design a novel security solution for pub/sub systems when brokers are not trusted such that: (i) it provides confidentiality of publications and subscriptions, (ii) it does not require publishers and subscribers to share keys, (iii) it allows subscribers to express complex subscription filters in the form of general Boolean expressions of predicates, and (iv) it allows enforcing fine-grained access control policies on the data. We provide a security analysis of the scheme.
%We further consider active attackers that corrupt messages or try to disrupt the network by replaying old legitimate messages, or that the publishers and subscribers themselves could misbehave, and provide solutions for data integrity, authentication and non-repudiation.
Furthermore, to secure data caching and replication in the network, a key requirement for ICN systems and recently also of pub/sub systems that extended brokers with database functionality, we show how our solution can be transformed in an encrypted search solution able to index publications at the broker side and allow subscribers to make encrypted queries. This is the first full-fledged multi-user encrypted search scheme that allows complex queries. We analyse the inference exposure of our index using different threat models.
To allow our encrypted routing solution to scale up to large applications or performance constrained applications that require real-time delivery of messages, we also discuss subscription indexing and the inference exposure of the index.
Finally, we implement our solution as a set of middleware-agnostic libraries and deploy them on two popular content-based networking implementations: a pub/sub system called PADRES, and an ICN called CCNx. Performance analysis shows that our solution is scalable
Deep ventilation in Lake Baikal: a simplified model for a complex natural phenomenon
No full textLake Baikal (Southern Siberia) is the world's oldest, deepest and largest freshwater body by volume. In spite of its enormous depth, episodically (i.e. almost twice a year) large volumes of surface, cold and oxygenated water sink towards the bottom of the lake. This phenomenon is known as deep ventilation and determines the periodical, partial renewal of deep water, playing a key role in the ecology of the whole lacustrine system. Despite deep ventilation has been widely observed, still significant uncertainties exist about the detailed characterization of deep downwellings.
In order to tackle this issue, a simplified, one-dimensional numerical model has been developed, which allows for a suitable simulation of deep ventilation in profound lakes. Three main algorithms are at the basis of the model: a reaction-diffusion equation for temperature and other tracers (e.g. dissolved oxygen), and two Lagrangian algorithms, the first to handle buoyancy-driven convection due to density instability (including thermobaric effects) and the other to reproduce the deep downwelling mechanism. Thanks to its simple structure, such a model ensures a considerable computational speed that makes it suitable to perform long-term simulations (i.e. decades, centuries). At the same time, it has been shown to be appropriate for quantitatively and qualitatively simulating deep ventilation, well capturing the relative contribution of the different processes involved.
The model has been applied to investigate deep ventilation in the South Basin of Lake Baikal. The numerical results have been shown to be in good agreement with observed data (concerning temperature, CFC-12 and dissolved oxygen profiles), indicating a proper performance of the core algorithms. The analysis of results allowed for a detailed description of the major mixing and thermal dynamics of the lake, and for an in-depth characterization of deep water renewal (e.g. typical downwelling temperatures and volumes, vertical distribution of sinking water, energy balance). Numerical simulations have been performed under current conditions and climate change scenarios, thus permitting to assess the future behavior of the lake and the possible impact on deep ventilation, in response to the expected evolution of climate.
In addition to the main results discussed above, this study provided some additional outcomes: a simplified lumped model to convert air temperature into surface water temperature of lakes, and a novel downscaling procedure to transform meteorological data (i.e. wind speed and air temperature) from the global scale to the lake scale.
In the light of the proven performance of the deep ventilation model, further improvements of the model could bring to the development of a suitable module to simulate biogeochemical processes in the lake, thus providing valuable information to assess the role of deep ventilation in affecting the lake ecosystem
3D Camera Based on Gain-Modulated CMOS Avalanche Photodiodes
No full textIn the last several years, both scientific and industrial community have shown an increasing interest in range imaging due to its potential use in various application domains such as robotics, vehicle safety, gaming, mobile applications as well as many others. Among the diversity of techniques available for range detection, Time-of-Flight (TOF) offers advantages in terms of compact system realization, good performance and low required computational power. Recent works have shown a trend towards higher resolutions, with a consequent reduction of pixel size, higher modulation frequencies and demodulation contrast to allow a higher distance precision.
In this thesis we propose a new concept of range camera exploiting linear-mode avalanche photodiodes as in-pixel demodulating detectors. Due to photocurrent gain modulation, avalanche photodiodes can combine optical sensing and light signal demodulation in a single device. The main advantage of the avalanche photodiode implementation is the possibility to operate at high frequencies due to its very wide bandwidth that, in turn, influences the precision in distance measurement.
In a first stage, the concept was experimentally validated on single pixel structures. These measurement results encouraged the implementation of a time-of-flight image sensor. A 64x64 pixel array has been designed and fabricated in a 0.35um standard CMOS technology.
The pixel pitch is 30um with a fill-factor of 25.7%. Demodulation contrast exceeds 85% at 25MHz modulation frequency. A 3D camera system demonstrates best precision of 1.9cm and a 3D frame rate of 200fps.
Additional tests performed on single pixels have shown demodulation contrast as high as 80% measured at 200MHz modulation frequency
"Small is beautiful"?: Essays on the cooperative banking sector: The case of credit cooperative banks in Italy from 2004 to 2011
Get PDFSmall Italian banks have experienced a substantial growth since the mid-1990s and have not disappeared in the wave of the liberalization process that started in 1992. Two main reasons have emerged to explain their growth: (i) the consolidation process of larger banks that disregards smaller customers and (ii) their lending strategy based on localism, proximity, small dimensions, and peer monitoring. Small banks could exploit their ability in collecting soft information and they often use them along with hard information to reduce the asymmetries of information and moral hazard issues in transactions.
Among the small banks, cooperative banks have an additional advantage due their member-based ownership structure. They use this to increase the quantity and quality of the soft information compared to other small banks.
Italian Credit Cooperative Banks (Banche di Credito Cooperativo, hereafter CCBs) have performed particularly well in expanding their business and in increasing both members and branches, largely due to the weakening of their legal constraints in 1992. However, this growth has not been homogenous and there are differences in growth patterns at the dimensional and the geographical levels.
This dissertation focuses on three research questions concerning CCBs:
1. The role of size in the recent growth of CCBs: the literature on bankâs growth has shown mixed results on the relationship between growth and size. In particular, two main features have been studied: (i) the role of size in the growth of loans, assets and members by testing the Law of Proportionate Effect (LPE); (ii) the role played by other covariates in the growth of loans, assets and members by testing a multivariate regression model. Applying these models to CCBs, the results show that LPE is rejected in favour of a negative relation between size and growthâi.e., smaller CCBs have grown faster. Their faster growth is related to the financial variablesâ the cost-income level and average earnings (or costs) from interest rates. Moreover, environmental variables play a significant role in explaining the growth.
2. The impact of social capital on the performance of CCBs: given their cooperative form, lending technology, and control mechanisms, the presence of CCBs are expected to be higher in areas where people are more connected and the level of trust is higher. This assumption is related to a small but growing literature on the effects of trust and social capital on the viability and growth of cooperatives at the macro-level. The impact of social capital variables (number of people joining associations and the trust level) on the market share of CCBs at province level turn out to be positive and significant. The results for the market share hold for both the overall credit market and the specific SME credit market. Moreover, the higher presence universalistic associations (associations pursuing general goals â e.g. environmental protection) as compared to particularistic association (those with a particularistic goal, e.g. sports club) have a positive impact on the market share. Finally, only CCBs seem to gain from the presence of larger social capital in comparison to other local banks
3. The relation between the governance structure and interest rate pricing as a way to reward members: CCB members do not usually receive dividends, instead benefit from better financial conditionsâi.e., better interest rates. However, while the borrowers are interested in reduced interest rate on loans, the depositors prefer an increase in the interest rate on their deposits. The reward choices of CCBs are described using a model based on the bankâs rewarding priorities and the median voter framework is suitably adapted for the CCBs governance structure. An empirical investigation on the impact of the majority composition in the general assembly on the interest rates pricing is attempted. The tests show that the interest rates policies of CCBs match with the median voter prediction in the case of a borrower majority, while a depositor majority kept the interest rates on deposits lower. This could be seen as a way to control the costs. CCBs follow a strategy to benefit both types of members and to be consistent with their balance sheet constraints
Multilayer Micromachined RF MEMS Filters at Ka and L/S Band For On-Board Satellite Communication Systems
No full textThis doctorate thesis focuses on the application of micromachining fabrication technologies for the realization of Radio Frequency (RF) bandpass filters. The work has been inspired and supported by the European Space Agency (ESA) Contract No. 22706/09/NL/GLC of the ARTES 5 Workplan 2008 “Micro-machined Filters in Multi-layer Technology for Satellite On-board Communication Systems” (MIGNON Project). The main purpose of the project is the design and realization of high performance bandpass filters in the Ka and L/S band for on board applications. The use of modern micromachining technologies should allow for space and weight reduction as well as for a cost effective realization of these devices. In addition the tight tolerances obtained with micromachining techniques facilitate an industrial fabrication of filters with high yield. The thesis proposes novel concepts to accomplish this task and provides also the fabrication processes suitable to realize the devices. In addition this work gives also a deeper insight into critical fabrication steps like wafer to wafer thermocompression bonding using gold (Au) and silver (Ag) as an intermediate layer and fabrication of Through Silicon Vias (TSV)
Simultaneous partial Nitritation, Anammox and Denitrification (SNAD) process for treating ammonium-rich wastewaters
No full textBiological nitrogen removal from strong ammonium wastewaters received a great deal of attention during the last years. Since the discovery of anammox bacteria the traditional theory of biological nitrogen removal has been extended to new nitrogen metabolic pathways. This thesis deals with the study of Simultaneous partial Nitritation, Anammox and Denitrification (SNAD) process in a Sequencing Batch Reactor (SBR) to treat wastewaters with a high ammonium load and low biodegradable organic matter, such as anaerobic digester effluent and old landfill leachate. The bacterial diversity in the reactor was investigated by analysis of specific gene clone libraries, Polymerase Chain Reaction (PCR) and fluorescence in situ hybridization (FISH). SNAD process is a complex biological process where different populations with opposed environmental requirements coexist, thus, experiments have been performed with a lab – scale reactor, focusing on the assessment of the feasibility of SBR configuration for achieving a simultaneous carbon and nitrogen removal. In addition, proper operational conditions, control strategies and a suitable loads were investigated
Haptic-based object-directed behavior: the role of parietal operculum.
Get PDFThe aim of this thesis is to provide new insights about the role of the left human parietal operculum (OP) in sensory motor transformations in the context of object-directed behavior. This work is divided in two main parts: and introductive part about the theory underlying the sensory motor integration and the existing literature about the parietal operculum, and an experimental part in which the experiments realized during these three years are described. In Chapter 1, the theory underlying the sensory motor transformation in the visual modality and the possible functions of the different front-parietal circuits are described on the basis of the theory proposed in the literature. A specific paragraph is dedicated to ventral premotor cortex (PMv) and its role in visually guided grasping. The Chapter 2, is a review of the literature about the cytoarchitecture, the connectivity and the physiology of humans and non- human primates parietal operculum. In Chapter 3 the literature about the role of OP of primates and humans in sensory motor integration is reviewed together with some literature about studies on lesions. In the experimental part, four transcranial magnetic stimulation (TMS) experiments are described. The last two experiments have been grouped in a single major work and results have been discussed together. In Chapter 4 the Experiment I is described. This experiment aimed to characterize the fronto-parietal network involving the connection between left OP and ipsilateral primary motor cortex (M1). By means of double coil TMS paradigm we were able to asses on five healthy volunteers the functional interaction occurring between these two regions, defining the optimal spot located into the left OP region that was producing the highest inhibition on motor evoked potentials (MEPs) peak-to peak amplitude. We moreover characterized the timing of their interplay obtaining a 5 ms short latency interaction in support of a plausible direct cortico-cortical connection. In Chapter 5 the Experiment II and Experiment III (which is subdivided in two different experiments named Experiment IIIa and Experiment IIIb) are described. On the basis of the functional connectivity between OP and ipsilateral M1 at rest proved in Experiment I, the Experiment II aimed to asses whether and how the haptic information about objects’ geometry (size) is encoded within the left OP and whether such information is used for guiding object-directed motor actions. Again, by means of double coil TMS paradigm we provided evidences supporting that the excitability of left M1 of twelve healthy volunteers, in presence of a motor plan involving the grasping of an object, was modulated accordingly with the size information stored in ipsilateral OP of such object when such physical feature was previously acquired by haptic exploration. Such modulation didn’t occur when the object size was acquired by visual modality. As control we run the same paradigm on other twelve volunteers by conditioning the ventral premotor cortex (PMv) which is well know to play a key role in the visually guided grasping obtaining a clear double dissociation between haptic and visual modality, supporting the hypothesis that haptically guided behavior relies on a distinct network respect to visually guided one.Experiment III is divided in two different experiments (Experiments IIIa and Experiments IIIb). In both of these experiments we aimed to test the effect introduced by high frequency repetitive online TMS (rTMS) during two different tasks both involving only haptic modality. In Experiment IIIa a purely discriminative match-to-sample task, in which two cylinders (either equal or different in the diameter feature) were haptically explored in sequence with 2 seconds of delay, was implemented. RTMS was delivered during the delay period and effects on accuracy and sensitivity on discrimination were tested. In such non motor task, no significant effects were obtained on performances of the twelve healthy participants. In Experiment IIIb the effects of rTMS applied during different phases of a delayed grasping of a previously haptically explored object on the kinematics of the hand preshaping were assessed. Differently form experiment IIIa, in this motor task we obtained a significant perturbation of the hand aperture during the preshaping when stimulation was applied between the exploration of the object and the grasping, during the delay phase. Such results might suggest of the involvement of OP in sensory-motor transformations as a putative element of memory when a object-directd action plan is implemented supporting the theory of the existence also for the haptic modality, of a model dual to the one proposed for the visual modality, made of two different streams processing sensory information according with the final use (for action or for perception)