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Performing inclusion and exclusion in the peer group. Children's social organization and peer socializing practices in the classroom
Get PDFThis PhD thesis investigates children’s peer practices in two primary schools in Italy, focusing on the ordinary and the Italian L2 classroom. The study is informed by the paradigm of language socialization and considers peer interactions as a ‘double opportunity space’, allowing both children’s co-construction of their social organization and children’s sociolinguistic development. These two foci of attention are explored on the basis of children’s social interaction and of the verbal, embodied, and material resources that children agentively deploy during their mundane activities in the peer group.
The study is based on a video ethnography that lasted nine months. Approximately 30 hours of classroom interactions were video-recorded, transcribed, and analyzed with an approach that combines the micro-analytic instruments of Conversation Analysis and the use of ethnographic information. Three main social phenomena were selected for analysis: (a) children’s enactment of the role of the teacher, (b) children’s reproduction of must-formatted rules, and (c) children’s argumentative strategies during peer conflict. The analysis highlights the centrality of the institutional frame for children’s peer interactions in the classroom. Moreover, the study illustrates that children socialize their classmates to the linguistic, social, and moral expectations of the context in and through various practices. Notably, these practices are also germane to the local negotiation of children’s social organization and hierarchy.
Therefore, the thesis underlines that children’s peer interactions are both a resource for children’s sociolinguistic development and a potentially problematic locus where social exclusion is constructed and brought to bear. These insights are relevant for teachers’ professional practice. Children’s peer interactions are a resource that can be integrated in everyday didactics. Nevertheless, the role of the teacher in supervising and steering children’s peer practices appears crucial: an acritical view of children’s autonomous work, often implied in teaching methods such as peer tutoring, needs to be problematized
Flow of Complex Fluids in Geological Fractures
Get PDFIn this study, the lubrication theory is used to model flow in geological fractures and analyse the compound effect of medium heterogeneity and complex fluid rheology. Such studies are warranted as the Newtonian rheology is adopted in most numerical models because of its ease of use, despite non-Newtonian fluids being ubiquitous in subsurface applications. Past studies on Newtonian and non-Newtonian flow in single rock fractures are summarized in Chapter 1. Chapter 2 presents analytical and semi-analytical conceptual models for flow of a shear-thinning fluid in rock fractures having a simplified geometry, providing a first insight on their permeability. in Chapter 3, a lubrication-based 2-D numerical model is first implemented to solve flow of an Ellis fluid in rough fractures; the finite-volumes model developed is more computationally effective than conducting full 3-D simulations, and introduces an acceptable approximation as long as the flow is laminar and the fracture walls relatively smooth. The compound effect of shear-thinning fluid nature and fracture heterogeneity promotes flow localization, which in turn affects the performance of industrial activities and remediation techniques. In Chapter 4, a Monte Carlo framework is adopted to produce multiple realizations of synthetic fractures, and analyze their ensemble statistics pertaining flow for a variety of real non-Newtonian fluids; the Newtonian case is used as a benchmark. In Chapter 5 and Chapter 6, a conceptual model of the hydro-mechanical aspects of backflow occurring in the last phase of hydraulic fracturing is proposed and experimentally validated, quantifying the effects of the relaxation induced by the flow
A Plausible Science for an Elusive Object. Population, Society, and Government in T.R. Malthus' Political Thought
Get PDFQuesta tesi è un’analisi storico-concettuale del pensiero politico di Thomas Robert Malthus. Si vedrà in particolar modo come la crisi rivoluzionaria tardo settecentesca, cui si sommano i rivolgimenti economici e sociali connessi alla nascita della produzione manifatturiera, spinge l’autore a ripensare alcuni concetti fondamentali del pensiero politico moderno. Popolazione, società, governo e costituzione sono gli oggetti principali di questa ricerca: il principio di
popolazione è la legge scientifica cui il reverendo Malthus ricorre per elaborare le proprie teorie sul governo, il quale deve sempre porsi come scopo quello di preservare – o migliorare – la costituzione della società. La presenza politica di masse di poveri in società conduce l’autore alla ricerca di un principio scientifico in grado di fondare nella natura le gerarchie e la disuguaglianza da più parti contestate; in quanto dipendono da «leggi fondamentali», per Malthus le gerarchie e la disuguaglianza che da esse deriva sono un tratto costitutivo della società. La teologia, la morale e l’economia politica sono scienze di cui l’autore si serve per argomentare intorno all’incontestabile natura della povertà e della disuguaglianza tra i sessi, e per affermare le modalità di una loro proficua amministrazione. In India e in Irlanda, poi, le condizioni naturali di cui il principio di popolazione suggella la necessità si scoprono soggette a sfide del tutto originali rispetto a quelle osservabili in Inghilterra. Lì, allora, lo sforzo malthusiano di costruire una scienza all’altezza della complessità dell’oggetto sociale rivela con somma chiarezza la propria ambizione di naturalizzare la politica e garantire le condizioni di disciplinamento degli individui al lavoro e alla subordinazione. Il dispositivo di naturalizzazione che giace al cuore del sistema malthusiano rappresenta la cifra del problema Malthus che apre questa ricerca e ne scandisce i momenti salienti.This thesis is a conceptual-historical analysis of the political thought of Thomas Robert Malthus. In particular, I will highlight how the late Eighteenth-century revolutionary crisis, combined with the economic and social upheavals connected to the birth of the first factory-systems, led the author to rethink some fundamental concepts of modern political thought. Population, society, government and constitution are the main objects of my research: the principle of population is the scientific law that Malthus formulated to elaborate his theories on government, which for him must always aim at preserving - or improving - the constitution of society. The political presence of masses of poor people in society pushed the author to find a scientific principle capable of grounding in nature the hierarchies that were contested by many; insofar as they depend on "fundamental laws", for Malthus hierarchies and inequality are constitutive of society. Theology, morality and political economy are the main disciplines that the author used both to argue that poverty and female “delicacy” are natural, and to affirm the ways in which they can be profitably governed. In India and Ireland - two places that Malthus looked at because of the strategic position they occupied within the British Empire - the natural conditions of which the principle of population seals the necessity are found to be subject to completely original challenges compared to those observed in England. There, the Malthusian effort to construct a science equal to the social object reveals its ambition to naturalise politics and guarantee the conditions for disciplining individuals, men and women, to work and stop nourishing “unreasonable” expectations of wellbeing. The naturalisation device that lies at the heart of the Malthusian system represents a key element of the Malthusian problem that opens this research and marks its salient moments
Big data analytics per la diagnostica predittiva e proattiva di sistemi batteria di auto elettriche
Get PDFThe idea behind the project is to develop a methodology for analyzing and developing techniques for the diagnosis and the prediction of the state of charge and health of lithium-ion batteries for automotive applications.
For lithium-ion batteries, residual functionality is measured in terms of state of health; however, this value cannot be directly associated with a measurable value, so it must be estimated. The development of the algorithms is based on the identification of the causes of battery degradation, in order to model and predict the trend. Therefore, models have been developed that are able to predict the electrical, thermal and aging behavior.
In addition to the model, it was necessary to develop algorithms capable of monitoring the state of the battery, online and offline. This was possible with the use of algorithms based on Kalman filters, which allow the estimation of the system status in real time. Through machine learning algorithms, which allow offline analysis of battery deterioration using a statistical approach, it is possible to analyze information from the entire fleet of vehicles. Both systems work in synergy in order to achieve the best performance.
Validation was performed with laboratory tests on different batteries and under different conditions. The development of the model allowed to reduce the time of the experimental tests. Some specific phenomena were tested in the laboratory, and the other cases were artificially generated.L'idea alla base del progetto è stata quella di sviluppare una metodologia di analisi e di sviluppo di tecniche per la diagnosi e la previsione dello stato di carica e di salute delle batterie agli ioni di litio per applicazioni automobilistiche.
Per le batterie agli ioni di litio, la funzionalità residua è misurata in termini di stato di salute, tuttavia questo valore non può essere direttamente associato ad un valore misurabile, di conseguenza è necessario stimarlo.
Lo sviluppo degli algoritmi è basato sull'identificazione delle cause di degrado delle batterie, al fine di modellarne e prevederne il comportamento. Sono stati dunque sviluppati modelli in grado di prevedere il comportamento elettrico e termico, e di invecchiamento della batteria.
Oltre al modello, è stato necessario sviluppare algoritmi in grado di monitorare lo stato della batteria, online e offline, questo è stato possibile con l'utilizzo di algoritmi basati su filtri di Kalman, che permettono la stima dello stato del sistema in tempo reale. Attraverso algoritmi di machine learning, che consentono di analizzare offline il deterioramento della batteria con un approccio statistico, è possibile analizzare le informazioni dell'intera flotta di veicoli. Entrambi i sistemi lavorano in sinergia al fine di ottenere le migliori prestazioni.
La validazione è stata eseguita con test di laboratorio su diverse batterie e in diverse condizioni. Lo sviluppo del modello ha permesso di ridurre il tempo delle prove sperimentali. Alcuni fenomeni specifici sono stati testati in laboratorio, e gli altri casi sono stati generati artificialmente
Development and Implementation of the Plasma Focus Technology for Radiation Therapy Applications
Get PDFA Plasma Focus device can confine in a small region a plasma generated during the pinch phase. When the plasma is in the pinch condition it creates an environment that produces several kinds of radiations. When the filling gas is nitrogen, a self-collimated backwardly emitted electron beam, slightly spread by the coulomb repulsion, can be considered one of the most interesting outputs. That beam can be converted into X-ray pulses able to transfer energy at an Ultra-High Dose-Rate (UH-DR), up to 1 Gy pulse-1, for clinical applications, research, or industrial purposes. The radiation fields have been studied with the PFMA-3 hosted at the University of Bologna, finding the radiation behavior at different operating conditions and working parameters for a proper tuning of this class of devices in clinical applications. The experimental outcomes have been compared with available analytical formalisms as benchmark and the scaling laws have been proposed. A set of Monte Carlo models have been built with direct and adjoint techniques for an accurate X-ray source characterization and for setting fast and reliable irradiation planning for patients. By coupling deterministic and Monte Carlo codes, a focusing lens for the charged particles has been designed for obtaining a beam suitable for applications as external radiotherapy or intra-operative radiation therapy. The radiobiological effectiveness of the UH PF DR, a FLASH source, has been evaluated by coupling different Monte Carlo codes estimating the overall level of DNA damage at the multi-cellular and tissue levels by considering the spatial variation effects as well as the radiation field characteristics. The numerical results have been correlated to the experimental outcomes. Finally, ambient dose measurements have been performed for tuning the numerical models and obtaining doses for radiation protection purposes. The PFMA-3 technology has been fully characterized toward clinical implementation and installation in a medical facility
Light & Electron beam - the perfect combination for the observation and application of photo active materials
Get PDFThe aim of the present PhD thesis is to investigate the properties of innovative nanomaterials for energy conversion. The materials have been deeply studied by means of a wide spectrum of different techniques based on both light and electron sources, in order to get an insight into the correlation between the properties of each material and the activity towards different energy conversion applications. The activity has been carried out in the framework of a collaboration between the “G.Ciamician” Chemistry Department of the University of Bologna and the CNR-IMM Bologna.
Four main topics have been explored: in the first part, luminescent silicon nanocrystals (SiNCs) have been discussed, suggesting a new approach to improve their optical properties as active material in complementary optoelectronic devices and photovoltaic cells. The luminescence of SiNCs have been exploited to increase the efficiency of conventional photovoltaic cells by means of an innovative architecture. Specifically, SiNCs were shown to be very promising light emitters in luminescent solar concentrators (LSC). The second part of the work has been focused on the study of high phosphorescent molecular chromophores, suggesting a new approach in their use as optical sensors successfully applied to the field of polymeric materials. This is due to the enhanced emission of light that appears in rigid, constrained or crystalline state, that is commonly called: "Aggregation-Induced Emission (AIE)". Such phenomenon is characteristic for molecular structures such as persulfurated benzene chromophores, hereafter named asterisks. The last two parts were focused on conventional and in-situ Transmission Electron Microscopy (TEM) morphological and structural characterization of photoactive and catalytic materials for energetic applications and in particular water splitting
Advanced cell culture platforms: methods for drug testing with microfluidics and microstructured devices
Get PDFAdvanced cell cultures are developing rapidly in biomedical research. Nowadays, various approaches and technologies are being used, however, these culturing systems present limitations from increasing complexity, requiring high costs, and not easily customization. We present two versatile and cost-effective methods for developing culturing systems that integrate 3D cell culture and microfluidic platforms. Firstly, for drug screening applications, many high-quality cell spheres of homogeneous size and shape are required. Conventional approaches usually have a dearth of control over the size and geometry of cell spheres and require sample collection and manipulation. To overcome this difficulty, in this study, hundreds of spheroids of several cell lines were generated using multi-well plates that housed our microdevices. Tumor spheroids grow at a uniform rate (in scaffolded or scaffold-free environments) and can be harvested at will. Microscopy imaging are done in real time during or after the culture. After in situ immunostaining, fluorescence imaging can be conducted while keeping the spatial distribution of spheroids in the microwells. Drug effects were successfully observed through viability, growth, and morphologic investigations. Also, we fabricated a microfluidic device suitable for directed and selective cell culture treatments. The microfluidic device was used to reproduce and confirm in vitro investigations carried out using normal culture methods, using a microglia cell line. The device layout and the syringe pump system, entirely designed in our lab, successfully allowed culture growth and medium flow regulation. Solution flows can be finely controlled, allowing treatments and immunofluorescence in one single chamber selectively. To conclude, we propose the development of two culturing platforms (microstructured well devices and in-flow microfluidic chip), which are the result of separate scientific investigations but have the primary goal of performing treatments in a reproducible manner. Our devices shall improve future studies on drug exposure testing, representing adjustable and versatile cell culture systems
Ions and Small Molecules as Modulators of F1FO-ATPase, Mitochondrial Bioenergetics and Cell Metabolism
Get PDFThe properties of the mitochondrial F1FO-ATPase activated by the natural cofactor Mg2+ or by Ca2+, were studied, mainly on heart mitochondria from swine, widely used in translational medicine. The Ca2+ driven conformational changes in the F1FO-ATPase form the mitochondrial permeability transition pore (mPTP), which triggers regulated cell death and is involved in severe pathologies. The Ca2+-activated F1FO-ATPase hydrolyzes ATP with kinetics slightly different from those of the Mg2+-ATPase. Known F1-ATPase inhibitors inhibit both the Ca2+-activated F1FO-ATPase and the mPTP formation strengthening the molecular link between them. The different Gd3+ effects on the Ca2+- and Mg2+-activated F1FO-ATPases confirm their difference as also phenylglyoxal which preferentially inhibits the Ca2+-activated F1FO-ATPase. The effects of phenylarsine and dibromobimane, which interact with differently distant Cys thiols, show that mPTP opening is ruled by nearby or distant dithiols. Bergamot polyphenols and melatonin inhibit the mPTP and ROS formation. H2S, a known cardiovascular protector, unaffects the F1FO-ATPase, but inhibits Ca2+ absorption and indirectly the mPTP, both in swine heart and mussel midgut gland mitochondria. New generation triazoles inhibit the Ca2+-activated F1FO-ATPase and the mPTP, but unaffect the Mg2+-activated F1FOATPase.
In parallel, the energy metabolism was investigated in mammalian cells. In boar sperm ATP is mainly produced by mitochondrial oxidative phosphorylation (OXPHOS), even if it decreases over time because of less active mitochondria. Insufficient ATP may induce sperm dysfunction. Also, canine mesenchymal stem cells rely on OXPHOS; those from umbilical cord which produce more ATP than those from adipose tissue, seem preferable for transplant studies. The intestinal porcine enterocyte cell line IPEC-J2, used for human gut research, responds to different fetal bovine serum concentrations by remodeling OXPHOS without altering the bioenergetic parameters. The IPEC-J2 bioenergetics is modulated by Vitamin K vitamers. These data shoulder cell bioenergetics as precious tool for medical research
High performance and energy-efficient instruction cache design and optimisation for ultra-low-power multi-core clusters
Get PDFHigh Energy efficiency and high performance are the key regiments for Internet of Things (IoT) end-nodes. Exploiting cluster of multiple programmable processors has recently emerged as a suitable solution to address this challenge. However, one of the main bottlenecks for multi-core architectures is the instruction cache. While private caches fall into data replication and wasting area, fully shared caches lack scalability and form a bottleneck for the operating frequency. Hence we propose a hybrid solution where a larger shared cache (L1.5) is shared by multiple cores connected through a low-latency interconnect to small private caches (L1). However, it is still limited by large capacity miss with a small L1. Thus, we propose a sequential prefetch from L1 to L1.5 to improve the performance with little area overhead. Moreover, to cut the critical path for better timing, we optimized the core instruction fetch stage with non-blocking transfer by adopting a 4 x 32-bit ring buffer FIFO and adding a pipeline for the conditional branch. We present a detailed comparison of different instruction cache architectures' performance and energy efficiency recently proposed for Parallel Ultra-Low-Power clusters. On average, when executing a set of real-life IoT applications, our two-level cache improves the performance by up to 20% and loses 7% energy efficiency with respect to the private cache. Compared to a shared cache system, it improves performance by up to 17% and keeps the same energy efficiency. In the end, up to 20% timing (maximum frequency) improvement and software control enable the two-level instruction cache with prefetch adapt to various battery-powered usage cases to balance high performance and energy efficiency
Big Code Applications and Approaches
Get PDFThe availability of a huge amount of source code from code archives and open-source projects opens up the possibility to merge machine learning, programming languages, and software engineering research fields. This area
is often referred to as Big Code where programming languages are treated instead of natural languages while different features and patterns of code can be exploited to perform many useful tasks and build supportive tools.
Among all the possible applications which can be developed within the area of Big Code, the work presented in this research thesis mainly focuses on two
particular tasks: the Programming Language Identification (PLI) and the Software Defect Prediction (SDP) for source codes.
Programming language identification is commonly needed in program comprehension and it is usually performed directly by developers. However, when it comes at big scales, such as in widely used archives (GitHub, Software
Heritage), automation of this task is desirable. To
accomplish this aim, the problem is analyzed from different points of view (text and image-based learning approaches) and different models are created paying particular attention to their scalability.
Software defect prediction is a fundamental step in software development for improving quality and assuring the reliability of software products. In the past, defects were searched by manual inspection or using automatic static and dynamic analyzers. Now, the automation of this task can be tackled using learning approaches that can speed up and improve related procedures. Here, two models have been built and analyzed to detect some of the commonest bugs and errors at different code granularity levels (file and method levels).
Exploited data and models’ architectures are analyzed and described in detail. Quantitative and qualitative results are reported for both PLI and SDP tasks while differences and similarities concerning other related works are discussed