From inflation to dark energy through a dynamical Λ: an attempt at alleviating fundamental cosmic puzzles

After decades of successful hot big-bang paradigm, cosmology still lacks a framework in which the early inflationary phase of the universe smoothly matches the radiation epoch and evolves to the present “quasi” de Sitter spacetime. No less intriguing is that the current value of the effective vacuum energy density is vastly smaller than the value that triggered inflation. In this paper, we propose a new class of cosmologies capable of overcoming, or highly alleviating, some of these acute cosmic puzzles. Powered by a decaying vacuum energy density, the spacetime emerges from a pure nonsingular de Sitter vacuum stage, “gracefully” exits from inflation to a radiation phase followed by dark matter and vacuum regimes, and, finally, evolves to a late-time de Sitter phase.

Glaciers and climate in northern Sweden during the 19th and 20th century

Our understanding of the climate of northern Sweden during the late Holocene is largely dependent on proxy-data series. These datasets remain spatially and temporally sparse and instrumental series are rare prior to the mid 19th century. Nevertheless, the glaciology and paleo-glaciology of the region has a strong potential significance for the exploration of climate change scenarios, past and future. The aim of this thesis is to investigate the 19th and 20th century climate in the northern Swedish mountain range. This provides a good opportunity to analyse the natural variability of the climate before the onset of the industrial epoch. Developing a temporal understanding of fluctuations in glacier front positions and glacier mass balance that is linked to a better understanding of their interaction and relative significance to climate is fundamental in the assessment of past climate. I have chosen to investigate previously unexplored temperature data from northern Sweden from between 1802 and 1860 and combined it with a temperature series from a synoptic station in Haparanda, which began operation in 1859, in order to create a reliable long temperature series for the period 1802 to 2002. I have also investigated two different glaciers, Pårteglaciären and Salajekna, which are located in different climatic environments. These glaciers have, from a Swedish perspective, long observational records. Furthermore, I have investigated a recurring jökulhlaup at the glacier Sälkaglaciären in order to analyse glacier-climate relationships with respect to the jökulhlaups. A number of datasets are presented, including: glacier frontal changes, in situ and photogrammetric mass balance data, in situ and satellite radar interferometry measurements of surface velocity, radar measurements, ice volume data and a temperature series. All these datasets are analysed in order to investigate the response of the glaciers to climatic stimuli, to attribute specific behaviour to particular climates and to analyse the 19th and 20th century glacier/climate relationships in northern Sweden. The 19th century was characterized by cold conditions in northern Sweden, particularly in winter. Significant changes in the amplitude of the annual temperature cycle are evident. Through the 19th century there is a marked decreasing trend in the amplitude of the data, suggesting a change towards a prevalence of maritime (westerly) air masses, something which has characterised the 20th century. The investigations on Salajekna support the conclusion that the major part of the 19th century was cold and dry. The 19th century advance of Salajekna was probably caused by colder climate in the late 18th and early 19th centuries, coupled with a weakening of the westerly airflow. The investigations on Pårteglaciären show that the glacier has a response time of ~200 years. It also suggests that there was a relatively high frequency of easterly winds providing the glacier with winter precipitation during the 19th century. Glaciers have very different response times and are sensitive to different climatic parameters. Glaciers in rather continental areas of the Subarctic and Arctic can have very long response times because of mass balance considerations and not primarily the glacier dynamics. This is of vital importance for analyzing Arctic and Subarctic glacier behaviour in a global change perspective. It is far from evident that the behaviour of the glacier fronts today reflects the present climate.

Context detection and abstraction in smart environments

Context-aware computing is currently considered the most promising approach to overcome information overload and to speed up access to relevant information and services. Context-awareness may be derived from many sources, including user profile and preferences, network information, sensor analysis; usually context-awareness relies on the ability of computing devices to interact with the physical world, i.e. with the natural and artificial objects hosted within the "environment”. Ideally, context-aware applications should not be intrusive and should be able to react according to user’s context, with minimum user effort. Context is an application dependent multidimensional space and the location is an important part of it since the very beginning. Location can be used to guide applications, in providing information or functions that are most appropriate for a specific position. Hence location systems play a crucial role. There are several technologies and systems for computing location to a vary degree of accuracy and tailored for specific space model, i.e. indoors or outdoors, structured spaces or unstructured spaces. The research challenge faced by this thesis is related to pedestrian positioning in heterogeneous environments. Particularly, the focus will be on pedestrian identification, localization, orientation and activity recognition. This research was mainly carried out within the “mobile and ambient systems” workgroup of EPOCH, a 6FP NoE on the application of ICT to Cultural Heritage. Therefore applications in Cultural Heritage sites were the main target of the context-aware services discussed. Cultural Heritage sites are considered significant test-beds in Context-aware computing for many reasons. For example building a smart environment in museums or in protected sites is a challenging task, because localization and tracking are usually based on technologies that are difficult to hide or harmonize within the environment. Therefore it is expected that the experience made with this research may be useful also in domains other than Cultural Heritage. This work presents three different approaches to the pedestrian identification, positioning and tracking: Pedestrian navigation by means of a wearable inertial sensing platform assisted by the vision based tracking system for initial settings an real-time calibration; Pedestrian navigation by means of a wearable inertial sensing platform augmented with GPS measurements; Pedestrian identification and tracking, combining the vision based tracking system with WiFi localization. The proposed localization systems have been mainly used to enhance Cultural Heritage applications in providing information and services depending on the user’s actual context, in particular depending on the user’s location.

Architettura delle centrali idroelettriche italiane 1910-1940. L'esperienza di Giovanni Muzio e Piero Portaluppi

Oggetto della ricerca è il tema dello spazio delle centrali idroelettriche costruite nella prima metà del Novecento dagli architetti Giovanni Muzio e Piero Portaluppi. L’individuazione del tema sorge dalla volontà di indagare quali siano stati gli sviluppi dal punto di vista architettonico all’interno di un genere così specifico durante un periodo di tempo in cui gli stili architettonici e le tendenze hanno subito stravolgimenti ed evoluzioni che ancora oggi trovano una difficile connotazione e definizione precisa. L’analisi dell’architettura delle centrali idroelettriche, effettuata ripercorrendo le principali vicende del settore idroelettrico dalla fine del secolo scorso al secondo dopoguerra, oltre a considerare il rapporto con il contesto territoriale e culturale del nostro Paese vuole prendere in considerazione anche il particolare rapporto che in più casi si è venuto a creare tra committenti e progettisti. Compito della tesi è rileggere un settore poco indagato finora e capire se vi sia stata effettivamente una evoluzione architettonica dal punto di vista tipologico o se la centrale sia stata sempre affrontata come semplice esercizio di “vestizione” di un involucro precostituito da precise esigenze tecniche. La ricerca infatti si pone come obiettivo lo studio delle centrali non solo dal punto di vista tipologico e spaziale dei suoi principali elementi, ma si pone come obiettivo anche lo studio della loro distribuzione nel sito in cui sono sorte, distribuzione che spesso ha portato alla formazione di una sorta di vera e propria “città elettrica”, in cui la composizione dei vari elementi segue una logica compositiva ben precisa. Dal punto di vista del contributo originale la ricerca vuole proporre una serie di riflessioni ed elaborati inerenti alcune centrali non ancora indagate. Nel caso specifico di Portaluppi l’apporto originale consiste nell’aver portato alla luce notizie inerenti centrali che sono sempre state poste in secondo piano rispetto le ben più note e studiate centrali della Val d’Ossola. Nel caso invece di Muzio il contributo consiste in una analisi approfondita e in una comparazione di documenti che di solito sono sempre stati pubblicati come semplice apparato iconografico, ma che messi a confronto danno una lettura di quelle che sono state le fasi e le elaborazioni progettuali apportate dall’autore. Il tema della ricerca è stato affrontato poi attraverso una lettura delle fonti dirette relative agli scritti degli autori, con una contemporanea lettura di testi, articoli e interventi tratti dalle riviste appartenenti al periodo in esame per comprendere al meglio il panorama culturale e architettonico che hanno fatto da scenario alle esperienze di entrambe le figure oggetto di studio. Infine la ricerca si è concentrata sull’analisi di alcune opere in particolare - due centrali idroelettriche per ciascun autore oggetto della tesi - scelte perché considerate rappresentative sia per impianto spaziale e tipologico, sia per le scelte compositive e stilistiche adottate. La lettura dei manufatti architettonici scelti è stata condotta con l’analisi di copie di elaborati grafici originali, foto d’epoca e altri documenti reperiti grazie ad una ricerca condotta in vari archivi. Le centrali scelte nell’ambito delle esperienze maturate da Muzio e Portaluppi sono state individuate per rappresentare il quadro relativo allo sviluppo e alla ricerca di un nuovo linguaggio formale da adottare nell’ambito dell’architettura di questi manufatti. Per entrambi i protagonisti oggetto della ricerca sono state individuate due centrali in grado di dare una visione il più possibile completa dell’evoluzione della tematica delle centrali idroelettriche all’interno della loro esperienza, prendendo in considerazione soprattutto gli aspetti legati all’evoluzione del loro linguaggio compositivo e stilistico. L’individuazione delle centrali da analizzare è stata dettata prendendo in considerazione alcuni fattori come il tipo di impianto, le relazioni e confronto con il contesto geografico e naturale e le soluzioni adottate.

Controllo dell'atto di prensione: coinvolgimento dell'area V6A nell'orientamento del polso

Prehension in an act of coordinated reaching and grasping. The reaching component is concerned with bringing the hand to object to be grasped (transport phase); the grasping component refers to the shaping of the hand according to the object features (grasping phase) (Jeannerod, 1981). Reaching and grasping involve different muscles, proximal and distal muscles respectively, and are controlled by different parietofrontal circuit (Jeannerod et al., 1995): a medial circuit, involving area of superior parietal lobule and dorsal premotor area 6 (PMd) (dorsomedial visual stream), is mainly concerned with reaching; a lateral circuit, involving the inferior parietal lobule and ventral premotor area 6 (PMv) (dorsolateral visual stream), with grasping. Area V6A is located in the caudalmost part of the superior parietal lobule, so it belongs to the dorsomedial visual stream; it contains neurons sensitive to visual stimuli (Galletti et al. 1993, 1996, 1999) as well as cells sensitive to the direction of gaze (Galletti et al. 1995) and cells showing saccade-related activity (Nakamura et al. 1999; Kutz et al. 2003). Area V6A contains also arm-reaching neurons likely involved in the control of the direction of the arm during movements towards objects in the peripersonal space (Galletti et al. 1997; Fattori et al. 2001). The present results confirm this finding and demonstrate that during the reach-to-grasp the V6A neurons are also modulated by the orientation of the wrist. Experiments were approved by the Bioethical Committee of the University of Bologna and were performed in accordance with National laws on care and use of laboratory animals and with the European Communities Council Directive of 24th November 1986 (86/609/EEC), recently revised by the Council of Europe guidelines (Appendix A of Convention ETS 123). Experiments were performed in two awake Macaca fascicularis. Each monkey was trained to sit in a primate chair with the head restrained to perform reaching and grasping arm movements in complete darkness while gazing a small fixation point. The object to be grasped was a handle that could have different orientation. We recorded neural activity from 163 neurons of the anterior parietal sulcus; 116/163 (71%) neurons were modulated by the reach-to-grasp task during the execution of the forward movements toward the target (epoch MOV), 111/163 (68%) during the pulling of the handle (epoch HOLD) and 102/163 during the execution of backward movements (epoch M2) (t_test, p ≤ 0.05). About the 45% of the tested cells turned out to be sensitive to the orientation of the handle (one way ANOVA, p ≤ 0.05). To study how the distal components of the movement, such as the hand preshaping during the reaching of the handle, could influence the neuronal discharge, we compared the neuronal activity during the reaching movements towards the same spatial location in reach-to-point and reach-to-grasp tasks. Both tasks required proximal arm movements; only the reach-to-grasp task required distal movements to orient the wrist and to shape the hand to grasp the handle. The 56% of V6A cells showed significant differences in the neural discharge (one way ANOVA, p ≤ 0.05) between the reach-to-point and the reach-to-grasp tasks during MOV, 54% during HOLD and 52% during M2. These data show that reaching and grasping are processed by the same population of neurons, providing evidence that the coordination of reaching and grasping takes place much earlier than previously thought, i.e., in the parieto-occipital cortex. The data here reported are in agreement with results of lesions to the medial posterior parietal cortex in both monkeys and humans, and with recent imaging data in humans, all of them indicating a functional coupling in the control of reaching and grasping by the medial parietofrontal circuit.

EoR in alternative cosmological scenarios

The aim of this Thesis is to investigate the possibility that the observations related to the epoch of reionization can probe not only the evolution of the IGM state, but also the cosmological background in which this process occurs. In fact, the history of the IGM ionization is indeed affected by the evolution of the sources of ionizing photons that, under the assumption of a structure formation paradigm determined by the hierarchic growth of the matter uctuations, results strongly dependent on the characteristics of the background universe. For the purpose of our investigation, we have analysed the reionization history in innovative cosmological frameworks, still in agreement with the recent observational tests related to the SNIa and the CMB probes, comparing our results with the reionization scenario predicted by the commonly used LCDM cosmology. In particular, in this Thesis we have considered two different alternative universes. The first one is a at universe dominated at late epochs by a dynamic dark energy component, characterized by an equation of state evolving in time. The second cosmological framework we have assumed is a LCDM characterized by a primordial overdensity field having a non-Gaussian probability distribution. The reionization scenario have been investigated, in this Thesis, through semi-analytic approaches based on the hierarichic growth of the matter uctuations and on suitable assumptions concerning the ionization and the recombination of the IGM. We make predictions for the evolution and the distribution of the HII regions, and for the global features of reionization, that can be constrained by future observations. Finally, we brie y discuss the possible future prospects of this Thesis work.

Architectures for Context Aware Services in Smart Environments

This thesis deals with Context Aware Services, Smart Environments, Context Management and solutions for Devices and Service Interoperability. Multi-vendor devices offer an increasing number of services and end-user applications that base their value on the ability to exploit the information originating from the surrounding environment by means of an increasing number of embedded sensors, e.g. GPS, compass, RFID readers, cameras and so on. However, usually such devices are not able to exchange information because of the lack of a shared data storage and common information exchange methods. A large number of standards and domain specific building blocks are available and are heavily used in today's products. However, the use of these solutions based on ready-to-use modules is not without problems. The integration and cooperation of different kinds of modules can be daunting because of growing complexity and dependency. In this scenarios it might be interesting to have an infrastructure that makes the coexistence of multi-vendor devices easy, while enabling low cost development and smooth access to services. This sort of technologies glue should reduce both software and hardware integration costs by removing the trouble of interoperability. The result should also lead to faster and simplified design, development and, deployment of cross-domain applications. This thesis is mainly focused on SW architectures supporting context aware service providers especially on the following subjects: - user preferences service adaptation - context management - content management - information interoperability - multivendor device interoperability - communication and connectivity interoperability Experimental activities were carried out in several domains including Cultural Heritage, indoor and personal smart spaces – all of which are considered significant test-beds in Context Aware Computing. The work evolved within european and national projects: on the europen side, I carried out my research activity within EPOCH, the FP6 Network of Excellence on “Processing Open Cultural Heritage” and within SOFIA, a project of the ARTEMIS JU on embedded systems. I worked in cooperation with several international establishments, including the University of Kent, VTT (the Technical Reserarch Center of Finland) and Eurotech. On the national side I contributed to a one-to-one research contract between ARCES and Telecom Italia. The first part of the thesis is focused on problem statement and related work and addresses interoperability issues and related architecture components. The second part is focused on specific architectures and frameworks: - MobiComp: a context management framework that I used in cultural heritage applications - CAB: a context, preference and profile based application broker which I designed within EPOCH Network of Excellence - M3: "Semantic Web based" information sharing infrastructure for smart spaces designed by Nokia within the European project SOFIA - NoTa: a service and transport independent connectivity framework - OSGi: the well known Java based service support framework The final section is dedicated to the middleware, the tools and, the SW agents developed during my Doctorate time to support context-aware services in smart environments.

Petrology and geochemistry of Lipari Island (Aeolian archipelago): constraints on magma genesis and evolution

A full set of geochemical and Sr, Nd and Pb isotope data both on bulk-rock and mineral samples is provided for volcanic rocks representative of the whole stratigraphic succession of Lipari Island in the Aeolian archipelago. These data, together with petrographic observations and melt/fluid inclusion investigations from the literature, give outlines on the petrogenesis and evolution of magmas through the magmatic and eruptive history of Lipari. This is the result of nine successive Eruptive Epochs developing between 271 ka and historical times, as derived from recentmost volcanological and stratigraphic studies, combined with available radiometric ages and correlation of tephra layers and marine terrace deposits. These Eruptive Epochs are characterized by distinctive vents partly overlapping in space and time, mostly under control of the main regional tectonic trends (NNW-SSE, N-S and minor E-W). A large variety of lava flows, scoriaceous deposits, lava domes, coulees and pyroclastics are emplaced, ranging in composition through time from calcalkaline (CA) and high-K (HKCA) basaltic andesites to rhyolites. CA and HKCA basaltic andesitic to dacitic magmas were erupted between 271 and 81 ka (Eruptive Epochs 1-6) from volcanic edifices located along the western coast of the island (and subordinately the eastern Monterosa) and the M.Chirica and M.S.Angelo stratocones. These mafic to intermediate magmas mainly evolved through AFC and RAFC processes, involving fractionation of mafic phases, assimilation of wall rocks and mixing with newly injected mafic magmas. Following a 40 ka-long period of volcanic quiescence, the rhyolitic magmas were lately erupted from eruptive vents located in the southern and north-eastern sectors of Lipari between 40 ka and historical times (Eruptive Epochs 7-9). They are suggested to derive from the previous mafic to intermediate melts through AFC processes. During the early phases of rhyolitic magmatism (Eruptive Epochs 7-8), enclaves-rich rocks and banded pumices, ranging in composition from HKCA dacites to low-SiO2 rhyolites were erupted, representing the products of magma mixing between fresh mafic magmas and the fractionated rhyolitic melts. The interaction of mantle-derived magmas with the crust represents an essential process during the whole magmatic hystory of Lipari, and is responsible for the wide range of observed geochemical and isotopic variations. The crustal contribution was particularly important during the intermediate phases of activity of Lipari when the cordierite-bearing lavas were erupted from the M. S.Angelo volcano (Eruptive Epoch 5, 105 ka). These lavas are interpreted as the result of mixing and subsequent hybridization of mantle-derived magmas, akin to the ones characterizing the older phases of activity of Lipari (Eruptive Epochs 1-4), and crustal anatectic melts derived from dehydration-melting reactions of metapelites in the lower crust. A comparison between the adjacent islands of Lipari and Vulcano outlines that their mafic to intermediate magmas seem to be genetically connected and derive from a similar mantle source affected by different degrees of partial melting (and variable extent of crustal assimilation) producing either the CA magmas of Lipari (higher degrees) or the HKCA to SHO magmas of Vulcano (lower degrees). On a regional scale, the most primitive rocks (SiO2<56%, MgO>3.5%) of Lipari, Vulcano, Salina and Filicudi are suggested to derive from a similar MORB-like source, variably metasomatized by aqueous fluids coming from the slab and subordinately by the additions of sediments.

The Universe 10 Billion years ago: Morphologies, Star-formation rates and Galactic-scale winds in z ∼ 2 Galaxies

This thesis is devoted to the study of the properties of high-redsfhit galaxies in the epoch 1 < z < 3, when a substantial fraction of galaxy mass was assembled, and when the evolution of the star-formation rate density peaked. Following a multi-perspective approach and using the most recent and high-quality data available (spectra, photometry and imaging), the morphologies and the star-formation properties of high-redsfhit galaxies were investigated. Through an accurate morphological analyses, the built up of the Hubble sequence was placed around z ~ 2.5. High-redshift galaxies appear, in general, much more irregular and asymmetric than local ones. Moreover, the occurrence of morphological k-­correction is less pronounced than in the local Universe. Different star-formation rate indicators were also studied. The comparison of ultra-violet and optical based estimates, with the values derived from infra-red luminosity showed that the traditional way of addressing the dust obscuration is problematic, at high-redshifts, and new models of dust geometry and composition are required. Finally, by means of stacking techniques applied to rest-frame ultra-violet spectra of star-forming galaxies at z~2, the warm phase of galactic-scale outflows was studied. Evidence was found of escaping gas at velocities of ~ 100 km/s. Studying the correlation of inter-­stellar absorption lines equivalent widths with galaxy physical properties, the intensity of the outflow-related spectral features was proven to depend strongly on a combination of the velocity dispersion of the gas and its geometry.

Hydrodynamical simulations of early-type galaxies: effects of galaxy shape and stellar dynamics on hot coronae

Early-Type galaxies (ETGs) are embedded in hot (10^6-10^7 K), X-ray emitting gaseous haloes, produced mainly by stellar winds and heated by Type Ia supernovae explosions, by the thermalization of stellar motions and occasionally by the central super-massive black hole (SMBH). In particular, the thermalization of the stellar motions is due to the interaction between the stellar and the SNIa ejecta and the hot interstellar medium (ISM) already residing in the ETG. A number of different astrophysical phenomena determine the X-ray properties of the hot ISM, such as stellar population formation and evolution, galaxy structure and internal kinematics, Active Galactic Nuclei (AGN) presence, and environmental effects. With the aid of high-resolution hydrodynamical simulations performed on state-of-the-art galaxy models, in this Thesis we focus on the effects of galaxy shape, stellar kinematics and star formation on the evolution of the X-ray coronae of ETGs. Numerical simulations show that the relative importance of flattening and rotation are functions of the galaxy mass: at low galaxy masses, adding flattening and rotation induces a galactic wind, thus lowering the X-ray luminosity; at high galaxy masses the angular momentum conservation keeps the central regions of rotating galaxies at low density, whereas in non-rotating models a denser and brighter atmosphere is formed. The same dependence from the galaxy mass is present in the effects of star formation (SF): in light galaxies SF contributes to increase the spread in Lx, while at high galaxy masses the halo X-ray properties are marginally sensitive to SF effects. In every case, the star formation rate at the present epoch quite agrees with observations, and the massive, cold gaseous discs are partially or completely consumed by SF on a time-scale of few Gyr, excluding the presence of young stellar discs at the present epoch.

Code synchronization and interference management techniques for satellite navigation and communications

This thesis collects the outcomes of a Ph.D. course in Telecommunications engineering and it is focused on enabling techniques for Spread Spectrum (SS) navigation and communication satellite systems. It provides innovations for both interference management and code synchronization techniques. These two aspects are critical for modern navigation and communication systems and constitute the common denominator of the work. The thesis is organized in two parts: the former deals with interference management. We have proposed a novel technique for the enhancement of the sensitivity level of an advanced interference detection and localization system operating in the Global Navigation Satellite System (GNSS) bands, which allows the identification of interfering signals received with power even lower than the GNSS signals. Moreover, we have introduced an effective cancellation technique for signals transmitted by jammers, exploiting their repetitive characteristics, which strongly reduces the interference level at the receiver. The second part, deals with code synchronization. More in detail, we have designed the code synchronization circuit for a Telemetry, Tracking and Control system operating during the Launch and Early Orbit Phase; the proposed solution allows to cope with the very large frequency uncertainty and dynamics characterizing this scenario, and performs the estimation of the code epoch, of the carrier frequency and of the carrier frequency variation rate. Furthermore, considering a generic pair of circuits performing code acquisition, we have proposed a comprehensive framework for the design and the analysis of the optimal cooperation procedure, which minimizes the time required to accomplish synchronization. The study results particularly interesting since it enables the reduction of the code acquisition time without increasing the computational complexity. Finally, considering a network of collaborating navigation receivers, we have proposed an innovative cooperative code acquisition scheme, which allows exploit the shared code epoch information between neighbor nodes, according to the Peer-to-Peer paradigm.

Parola arcaica e costruzioni del moderno. I sentieri della scrittura in Julio Herrera y Reissig

L’obbiettivo del lavoro è quello di delimitare uno spazio critico che consenta di ripensare il concetto di modernità nelle culture ispanoamericane degli inizi del XX secolo. In questa direzione, si è deciso di focalizzare l’attenzione su un’opera letteraria, quella dell’uruguaiano Julio Herrera y Reissig, del tutto particolare se comparata al resto delle produzioni estetiche a essa più immediatamente contigue. Tornare a leggere Herrera y Reissig equivale, infatti, nella sostanza, a rimettere mano criticamente a tutta l’epoca modernista, interpretandola non in senso unitario, bensì plurale e frammentario. Spunto di partenza dell’analisi sono state le coordinate culturali comuni in cui quelle estetiche si sono determinate e sviluppate, per poi procedere verso una moltiplicazione di percorsi in grado di rendere conto della sostanziale discrepanza di mezzi e finalità che intercorre fra Julio Herrera y Reissig e gran parte del Modernismo a lui contemporaneo. Mantenendo come base metodologica i presupposti dell’archeologia culturale foucauldiana, è stato possibile rintracciare, nell’opera dell’uruguaiano, un eterogeneo ma costante movimento di riemersione e riutilizzo delle più svariate esperienze del pensiero – estetico e non – occidentale. Nelle particolarità d’uso a cui la tradizione è sottomessa nella scrittura di Herrera y Reissig si è reso così possibile tornare a ragionare sui punti focali dell’esperienza della modernità: il legame fra patrimonio culturale e attualità, la relazione fra sedimentazione tradizionale e novità, nonché, in definitiva, le modalità attraverso le quali alla letteratura è consentito di pensare e dire la propria storia – passata, presente e futura – e, in conseguenza, metabolizzarla, per tornare ad agire attivamente su di essa.

Families Stories. Rappresentazioni di famiglie nella letteratura per l'infanzia in Europa e negli Stati Uniti

In questa tesi dottorale viene preso in analisi il tema della famiglia, uno degli elementi fondanti della riflessione pedagogica, crocevia di una molteplicità di nuclei interpretativi con diramazioni e contaminazioni, con mutamenti attraverso le epoche storiche, rappresentati in pagine contenute nei Classici della letteratura per l’infanzia e nei migliori libri di narrativa contemporanea. Si tratta di un tema di grande ampiezza che ha comportato una scelta mirata di Autori che, nei loro romanzi hanno trattato questioni riguardanti la famiglia nelle sue pluralità delle sue tante accezioni, dalla vita familiare agli abbandoni, dalle infanzie senza famiglia alle famiglie altre. Nelle diverse epoche storiche, le loro narrazioni hanno lasciato un segno per l'originalità interpretativa che ancora oggi ci raccontano storie di vie familiale Dai romanzi ottocenteschi alle saghe fantasy degli ultimi cinquant’anni, fino ai picturebook, destinati ai più piccoli, le families stories possono costituire un materiale pedagogico privilegiato, sia offrendo occasioni di scoperta e conoscenza di sé e del mondo, attraverso le quali i lettori bambini, enigmatici frontalieri, varcano soglie verso altrovi misteriosi, sia fornendo spunti agli studiosi per approfondire tematiche multiple e complesse. Le families stories riflettono spesso in maniera critica le divergenze che possono manifestarsi tra le prassi individuate e studiate dalle scienze umane e sociali e le metafore narrative proposte dai numerosi Autori della letteratura per l’infanzia. Proponendo una prospettiva spesso spiazzante, esse interpretano la realtà a fondo, cogliendo i più piccoli ed inosservati particolari che, invece, hanno la capacità di rompere gli schemi socio-educativi dell’epoca storica in cui le storie prendono vita.

Simulations for Gravitational Lensing of 21 cm Radiation at EoR and Post-EoR Redshifts

21 cm cosmology opens an observational window to previously unexplored cosmological epochs such as the Epoch of Reionization (EoR), the Cosmic Dawn and the Dark Ages using powerful radio interferometers such as the planned Square Kilometer Array (SKA). Among all the other applications which can potentially improve the understanding of standard cosmology, we study the promising opportunity given by measuring the weak gravitational lensing sourced by 21 cm radiation. We performed this study in two different cosmological epochs, at a typical EoR redshift and successively at a post-EoR redshift. We will show how the lensing signal can be reconstructed using a three dimensional optimal quadratic lensing estimator in Fourier space, using single frequency band or combining multiple frequency band measurements. To this purpose, we implemented a simulation pipeline capable of dealing with issues that can not be treated analytically. Considering the current SKA plans, we studied the performance of the quadratic estimator at typical EoR redshifts, for different survey strategies and comparing two thermal noise models for the SKA-Low array. The simulation we performed takes into account the beam of the telescope and the discreteness of visibility measurements. We found that an SKA-Low interferometer should obtain high-fidelity images of the underlying mass distribution in its phase 1 only if several bands are stacked together, covering a redshift range that goes from z=7 to z=11.5. The SKA-Low phase 2, modeled in order to improve the sensitivity of the instrument by almost an order of magnitude, should be capable of providing images with good quality even when the signal is detected within a single frequency band. Considering also the serious effect that foregrounds could have on this detections, we discussed the limits of these results and also the possibility provided by these models of measuring an accurate lensing power spectrum.

Mythos und Mathematik : Hermann Brochs Roman "Die Schuldlosen" und seine Essays

„Natürlich habe ich mich [...] unausgesetzt mit Mathematik beschäftigt, umso mehr als ich sie für meine erkenntnistheoretisch-philosophischen Studien brauchte, denn ohne Mathematik lässt sich kaum mehr philosophieren.“, schreibt Hermann Broch 1948, ein Schriftsteller, der ca. zehn Jahre zuvor von sich selbst sogar behauptete, das Mathematische sei eine seiner stärksten Begabungen.rnDiesem Hinweis, die Bedeutung der Mathematik für das Brochsche Werk näher zu untersuchen, wurde bis jetzt in der Forschung kaum Folge geleistet. Besonders in Bezug auf sein Spätwerk Die Schuldlosen fehlen solche Betrachtungen ganz, sie scheinen jedoch unentbehrlich für die Entschlüsselung dieses Romans zu sein, der oft zu Unrecht als Nebenarbeit abgewertet wurde, weil ihm „mit gängigen literaturwissenschaftlichen Kategorien […] nicht beizukommen ist“ (Koopmann, 1994). rnDa dieser Aspekt insbesondere mit Blick auf Die Schuldlosen ein Forschungsdesiderat darstellt, war das Ziel der vorliegenden Arbeit, Brochs mathematische Studien genauer nachzuvollziehen und vor diesem Hintergrund eine Neuperspektivierung der Schuldlosen zu leisten. Damit wird eine Grundlage geschaffen, die einen adäquaten Zugang zur Struktur dieses Romans eröffnet.rnDie vorliegende Arbeit ist in zwei Teile gegliedert. Nach einer Untersuchung von Brochs theoretischen Betrachtungen anhand ausgewählter Essays folgt die Interpretation der Schuldlosen aus diesem mathematischen Blickwinkel. Es wird deutlich, dass Brochs Poetik eng mit seinen mathematischen Anschauungen verquickt ist, und somit nachgewiesen, dass sich die spezielle Bauform des Romans wie auch seine besondere Form des Erzählens tatsächlich aus dem mathematischen Denken des Autors ableiten lassen. Broch nutzt insbesondere die mathematische Annäherung an das Unendliche für seine Versuche einer literarischen Erfassung der komplexen Wirklichkeit seiner Zeit. Dabei spielen nicht nur Elemente der fraktalen Geometrie eine zentrale Rolle, sondern auch Brochs eigener Hinweis, es handele sich „um eine Art Novellenroman“ (KW 13/1, 243). Denn tatsächlich ergibt sich aus den poetologischen Forderungen Brochs und ihren Umsetzungen im Roman die Gattung des Novellenromans, wie gezeigt wird. Dabei ist von besonderer Bedeutung, dass Broch dem Mythos eine ähnliche Rolle in der Literatur zuspricht wie der Mathematik in den Wissenschaften allgemein.rnMit seinem Roman Die Schuldlosen hat Hermann Broch Neuland betreten, indem er versuchte, durch seine mathematische Poetik die komplexe Wirklichkeit seiner Epoche abzubilden. Denn „die Ganzheit der Welt ist nicht erfaßbar, indem man deren Atome einzelweise einfängt, sondern nur, indem man deren Grundzüge und deren wesentliche – ja, man möchte sagen, deren mathematische Struktur aufzeigt“ (Broch).