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Hemispheric Specialization Tied to Lateralized Motor Preference in Human and Non-Human Primates
No full textIn literature there are large discrepancies about methods to assess cerebral lateralization in both human and nonhuman primate populations. This study aimed to allow valid comparisons across different primate species by employing a quantitative Multidimensional Method. A comprehensive range of interactions with both social and non-social targets were considered to verify which aspects might elicit the manifestation of lateralized behaviours underpinned by asymmetrical neuronal functions. Spontaneous activities were observed in two groups of zoo great apes, chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla gorilla), and a group of 3-4 year-old typical pre-school children. Results demonstrated a strong consistency in both human and non-human species for a right-hand/left hemisphere dominance during contact with inanimate targets (i.e. objects and environmental items), suggesting a
evolutionary hemispheric specialization influenced by object animacy. Additionally, both great ape species significantly preferred to keep conspecifics closer than 3 metres to their left during manual activities, suggesting a right hemisphere specialization for emotion processing. Only the silverback gorilla (alpha male) manifested the opposite pattern, potentially related to his hierarchical role within the gorilla society. No side preference was found in typical children however, their young age may indicate that they are still undergoing hemispheric development for emotion processing. This study supports an evolutionary origin of hemispheric specialization underling manipulative and social asymmetric behaviours that occurred prior to the split of humans from great apes
Computational Methods for the Assessment of Brain Connectivity in Visuo-Motor Integration Processes
Get PDFThe identification of the networks connecting different brain areas, as well as the understanding of their role in executing complex behavioral tasks, are crucial issues in cognitive neurosciences. In this context, several time series analysis approaches are available for the investigation of brain connectivity from non-invasive electroencephalographic (EEG) and magnetoencephalographic (MEG) recordings. Among them, multivariate autoregressive (MVAR) models, studied in the frequency domain, allow quantitative assessment of connectivity separately for each specific brain rhythm. In spite of its widespread utilization and great potential, MVAR-based brain connectivity analysis is complicated by a number of theoretical and practical aspects. An important issue is that the MVAR model, commonly applied to neurophysiological time series, accounts only for lagged effects among the series, forsaking instantaneous (i.e., not lagged) effects. Despite this, instantaneous correlations among EEG/MEG signals are largely expected, mainly as a consequence of volume conduction, and the impact of their exclusion on frequency-domain connectivity measures has not been investigated yet. The aim of the present thesis was to introduce and validate a new methodological framework for the frequency-domain evaluation of brain connectivity during visuo-motor integration processes. To this end, we provided first a comprehensive description of the most common MVAR-based connectivity measures, enhancing their theoretical interpretation. Then, we introduced an extended MVAR (eMVAR) model representation explicitly accounting for instantaneous effects. Accordingly, new frequency-domain connectivity measures were defined, and procedures for improving model identification and significance assessment were given. The proposed approach was validated on theoretical illustrative examples, and then applied to EEG and MEG multichannel data recorded from subjects performing a visuo-motor task combining precise grip motor commands with sensory visual feedback. The theoretical validation showed that, in the presence of significant instantaneous correlations, the traditional MVAR formulation may yield misleading connectivity patterns, while the correct patterns can be detected from the new measures based on eMVAR model identification. The practical application showed that instantaneous correlations are non negligible in the considered neurophysiological recordings, strongly suggesting the necessity of using the proposed eMVAR model in place of the traditional one. Results showed that execution of the visuo-motor task evokes the activation of a specific network subserving sensorimotor integration, which involves occipito-parietal and precentral cortices. The new connectivity measures revealed connections which were peculiar of different brain rhythms. Specifically, in the alpha frequency band (8-13 Hz) we documented an enhanced driving role of the visual cortex on the left motor cortex, suggesting a relation between this rhythm and the lateralization of the visuo-motor task. In the beta band (13-30 Hz), task-induced connectivity changes were bilateral, suggesting an involvement of both hemispheres. In both alpha and beta bands, the new connectivity measures suggested an important role for the parietal cortex in mediating the information flow from visual to motor areas, confirming previous evidences from invasive studies based on intra-cranical recordings, TMS or PET examinations.
This thesis was produced in collaboration with the Department of Physics of the University of Trento
Bridging the gap between theory and implementation in cognitive networks: developing reasoning in today's networks
No full textCommunication networks are becoming increasingly complex and dynamic. The networking paradigm commonly employed, on the other hand, has not changed over the years, and, as a result, performs poorly in today's environments.
Only very recently, a new paradigm named cognitive networking has been devised with the objective to make networks more intelligent, thereby overcoming traditional limitations and potentially achieving better performance. According to such vision, networks should be able to monitor themselves, reason upon the environment, act towards the achievement of specific goals and learn from experience.
Thus far, several cognitive network architectures have been conceived and proposed in the literature, but, despite researchers seem to agree on the need for a holistic approach, their architectures pursue such a global vision only in part, as they do not consider networks nor network nodes in their entirety.
In the present work, we analyze the aspects to be tackled in order to enable this holistic view and propose to base reasoning on both intra- and inter-node interactions, with the ultimate aim to devise a complete cognitive network architecture.
After a thorough analysis of advantages and drawbacks of generic reasoning framework, we select the most apt to form the basis on which to build the cognitive network we envision.
We first formalize its application in network environments, by determining the steps to follow in the process to equip traditional network with cognitive capabilities.
Then, we shift the focus from the design side to the implementation side, by identifying the problems that could be faced when realizing such a network, and by proposing a set of optional refinements that could be taken into account to further improve the performance in some specific situations.
Finally, we tackle the problem of reducing the time needed for the cognitive process to reason.
Validation through simulations shows that explicitly considering cross-layer intra- and inter-node interactions when reasoning has a twofold effect. First, it leads to better performance levels than those that can be achieved by today's non-intelligent networks, and second, it helps to better understand existent causal relationships between variables in a network
New proposals for the popularization of braid theory
No full textBraid theory is a very active research field. Braids can be studied from variuos points of view and have applications in different fields, e.g. in mathematical physics and in biology.
In this thesis we provide a formal introduction to some topics in the mathematical theory of braids and two possible approaches to this field at a popular level: a movie and a workshop.
The scientific movie addressed to a non-specialist audience has been realized using the free ray-tracer POV-Ray. It is divided into four parts, each of which has a length of about 15 minutes. The content ranges from the introduction of basic concepts to deep results.
The workshop activity is based on the action of braids on loops and aims to invite and lead the audience to a mathematical formalization of the principal concepts involved: braids, curves and group actions
Elastic Properties of Textured Nanocrystalline Thin Films
No full textPolycrystalline thin films and coatings often show preferred orientation of grains and crystalline domains, and develop a residual stress state as an effect of the growth mechanisms. These features can be conveniently measured by means of non-contact and non-destructive X-ray diffraction. As the technique only measures a map of strains along selected directions, stress evaluation requires a suitable constitutive equation, where the expression of moduli can be far from trivial if texture effects are to be taken into account; additionally, a grain interaction model needs to be enforced to describe strain and stress distribution among grains in the aggregate, based on background assumptions.
Several grain interaction models are available from literature: usually, a model or a combination of them provides a good fit of experimental data; often however underlying hypotheses are too restrictive or require unavailable information on certain microstructural parameters, leading this approach to fail. For this reason an experimental method was developed, for the characterisation of elastic properties and residual stress in thin film components by means of X-ray diffraction during in-situ mechanical testing.
This thesis presents a review of major literature works describing grain interaction modelling in textured components, and their implementation in X-ray diffraction stress analysis procedures. Following, the method for experimental characterisation of thin film elastic properties is described in detail. Applications are presented in the final chapter, that illustrates selected case studies on electrodeposited coatings
Il corpo nell'opera di Francesco d'Assisi e di Iacopone da Todi
No full textLa visione di un universo permeato dalla gloria di Dio che Francesco d’Assisi sviluppa nel Cantico di frate sole e nelle sue opere latine, e che risulta anche dalle testimonianze dei primi biografi, è stata interpretata da vari studiosi (Duby, Manselli, Pasero) come un implicito rovesciamento della concezione catara secondo cui il mondo non è stato creato dal Dio celeste, ma da un demiurgo malvagio. A prima vista, la concezione del corpo e della creazione materiale che emerge dall’opera poetica del francescano Iacopone da Todi si trova agli antipodi di quella del santo.
Giovanni Pozzi ha osservato come nelle Laude sia assente “qualsiasi valutazione del creato come entità recante l’impronta divina”; ma, lungi dal comportare un dualismo ontologico di tipo “gnostico”, come quello dei catari, questo atteggiamento va ricollegato secondo lo studioso svizzero alla tradizione dell’ascetismo cristiano, e in particolare al linguaggio del “disprezzo” del corpo e del mondo che verso la fine del secolo XIII aveva trovato una delle sue espressioni più violente ed efficaci nel De contemptu mundi di Lotario di Segni, il futuro papa Innocenzo III. Queste lucide considerazioni non mancano tuttavia di porre una serie di problemi storici ed ermeneutici che appaiono decisivi per una corretta comprensione delle opere letterarie dei due primi grandi scrittori religiosi della nostra letteratura: qual è il rapporto fra la concezione francescana del corpo (e più in generale del mondo materiale) e la riflessione cristiana dei secoli precedenti su questi temi? In particolare, come si può situarla rispetto ai grandi filoni teologici del XII e del XIII secolo: mistica cisterciense e vittorina, pensiero ascetico, eresia catara? E quali sono i rapporti fra la concezione di Francesco e quella che si delinea con straordinario vigore lirico nelle Laude di Iacopone? Quali sono i modelli del poeta di Todi? Fra i due grandi scrittori mistici e ascetici del Duecento italiano vi è realmente, a proposito della visione del corpo e della corporeità, radicale opposizione? Oppure possono essere individuati anche punti di contatto, elementi di continuità o di mediazione? E come si spiegano degli atteggiamenti così diversi nel fondatore e in uno dei primi grandi seguaci del movimento francescano? A questi, ed ad altri più puntuali interrogativi si è cercato di rispondere nel presente lavoro. Per giungere a risposte motivate e convincenti, si è ritenuto necessario partire da un approfondito esame delle concezioni del corpo e della materia nella tradizione del pensiero cristiano fino al Duecento. In particolare, sono apparse di fondamentale importanza le correnti teologiche del secolo precedente, il XII, correnti il cui influsso nella concezione del mondo di Francesco e di Iacopone appare determinante. Nella prima parte della tesi, abbiamo così dedicato un capitolo alla tematica del contemptus mundi quale è sviluppata nel grande trattato di Lotario di Segni. In un secondo capitolo è studiata la complessa – e talvolta almeno apparentemente contraddittoria – concezione del corpo e delle realtà materiali nelle due maggiori correnti della teologia mistica nel XII secolo, quella cisterciense e quella vittorina, alle quali si rifarà direttamente anche il francescano Bonaventura da Bagnoregio. Inoltre, si è ritenuto necessario studiare in maniera approfondita le dottrine eterodosse dei catari, che ebbero certamente un grande peso – come si è accennato – nella riflessione cristiana di questo periodo sul corpo e sulla materia. A partire da queste premesse dottrinali – che sono state spesso trascurate o sottovalutate dai filologi, ma alle quali la critica più recente incomincia a dedicare la dovuta attenzione – nella seconda parte della tesi abbiamo sottoposto a una accurata analisi la concezione e la rappresentazione del corpo, e della “corporeità” in generale, nelle opere italiane e latine di Francesco d’Assisi e di Iacopone da Todi. Ne sono derivate conclusioni molto più articolate e sfumate di quanto possa far pensare una lettura superficiale dei loro testi: gli stretti rapporti che si possono osservare in entrambi gli autori con la precedente tradizione ascetica e mistica valgono a mettere in luce tutta una serie di rapporti profondi fra di loro, specialmente intorno al nodo cruciale del corpo di Cristo. E questo vale, a nostro parere, a far risaltare ancor meglio gli aspetti originali dei testi maggiori di Francesco e di Iacopone, a farci gustare appieno la loro “poesia del corpo”
Price Formation, Income Distribution, and the Business Cycle in a Stock-Flow Consistent Monetary Model
No full textThis Thesis follows the Post-Keynesian stock-flow consistent approach. This thesis provides some insight into the dynamics of aggregate behavior by means of numerical simulations, suggesting interesting closures grounded in Godley and Lavoie 2007 book. This thesis studies and analyzes some phenomena that could be involved, or affected, by the recent global financial crisis. The thesis contributions are study how house price variations affect both the real and the financial sides of the economy, study financial integration and see its effects on integrated economies, and explore the impact of credit crunch and it contagion on both domestic and foreign economies
Sintering of Co2MnO4 spinel for protective coatings in SOFC
Get PDFProtective coatings are often deposited on SOFC interconnectors to avoid poisoning of cathode from chromium species that evaporate from stainless steel interconnects or supports. Co2MnO4 spinel compounds are usually considered as the main constituent of protection barriers. Nevertheless, such ceramic sinters at high temperatures (>1200°C) and this can be problematic for the properties of the stainless steel components. One of the major issues is, in fact, the creation of a compact and impermeable coating at relatively low temperature in order to preserve the metal substrate. In the present research work, Co2MnO4 spinel was synthesized by various methods (solid-state, gel-combustion, co-precipitation and reverse micelle) and the obtained specific surface area, structure and particle size were correlated with thermal behaviour, sintering temperature and achieved density. It was found that regardless the synthesis process the only obtained phase is Co2MnO4. Specific surface area from 0,8 to 65 m2g-1 was obtained, depending on the synthesis method.
Sintering aids such as Nb2O5 and LiF were used to obtain dense microstructure at relatively low temperature. Considerable changes in sintering temperature were observed this being even 100-200ºC lower than that necessary for the consolidation of pure spinel though microstructure with only close pores was achieved.
A novel sintering method based on Field Assisted Techniques (FAST) that promoted flash-sintering phenomenon was finally applied to Co2MnO4. Small electric field (<7,5 V cm-1) applied to the spinel decreases the sintering temperature down to 600°C. The application of an electric field above 7,5 V cm-1 flash-sintering phenomenon takes place and sintering temperature drops to about 300°C, the sintering time being less than 1 second
Beyond Territorial Protection: Millet and Personal Autonomy as Instruments for (New) Minorities in Europe?
No full textNew and non-territorial minorities in Europe do not find adequate protection within the territorial autonomy model. After a compared analysis of contemporary millet systems (Lebanon, Israel, and Iraq), the dissertation focuses on Eruopean instruments for protecting non-territorial minorities in terms of personal autonomy, cultural autonomy, and political representation.
Europe is progressively adopting non-territorial means of minority protection, which leads to the reconsideration of the nation-State model. First, personal autnomy implies legal pluralism; secondly cultural autnomy and political representation require the progressive inclusion of diverse groups in teh decision-making processes
Displacement-Based Seismic Design of Timber Structures
Get PDFThe research is aimed at developing seismic methods for the design and evaluation of the seismic vulnerability of wooden structures, using a displacement-based approach. After a brief introduction on the seismic behaviour of timber structures, the general Direct Displacement-Based Design (Direct-DBD) procedure and the state-of-the-art are presented, with clear reference to the application of the Direct-DBD method to wooden buildings. The strength of the Direct-DBD method is its ability to design structures in a manner consistent with the level of damage expected, by directly relating the response and the expected performance of the structure. The research begins with a description of the procedural aspects of the Direct-DBD method and the parameters required for its application.
The research presented focuses on the formulation of a displacement-based seismic design procedure, applicable to one-storey wooden structures made with a portal system. This typology is very common in Europe and particularly in Italy. A series of analytical expressions have been developed to calculate design parameters. The required analytical Direct-DBD parameters are implemented based on the mechanical behaviour of the connections, made with metal dowel-type fasteners. The calibration and subsequent validation of design parameters use a Monte Carlo numerical simulation and outcomes obtained by tests in full-scale.
After the description of the Displacement-Based method for one-storey wooden structures, a series of guidelines to extend the Direct-DBD methodology to other types and categories of timber systems are proposed. The thesis presents the case of a multi-storey wood frame construction, which is a simple extension of the glulam portal frame system.
Part of this work has been done within the RELUIS Project, (REte dei Laboratori Universitari di Ingegneria Sismica), Research Line IV, which in the years between 2005 and 2008 involved several Italian universities and Italian institutes of research in the development of new seismic design methods. The Project produced the first draft of model code for the seismic design of structures based on displacement (Direct-DBD). This thesis is the background to the section of the model code developed for timber structures