Lattice QED photonic wavepackets on ladder geometries

openIn this thesis we explore numerical simulations, including Tensor Networks (TNs) methods, to study Hamiltonian Lattice Gauge Theories (LGTs), a numerical framework for investigating non-perturbative properties of Quantum Field Theories. We develop a model-independent approach for constructing Matrix Product Operators (MPOs) representations of 1-dimensional quasiparticles with definite momenta, and apply it to Hamiltonian Lattice Quantum Electrodynamics (QED) on a ladder geometry. By means of exact diagonalization at intermediate system sizes, we obtain the first excitation band states (the Bloch functions) representing the single-(quasi)particle states (the photons) expressed as entangled states of local lattice gauge fields. We then construct the corresponding maximally-localized Wannier functions through minimization of a spread functional. Once we identify, via a linear algebra problem, the operation that constructs the localized Wannier excitation from the ground state (dressed vacuum), we can express the creation operator, for any wavepacket of such quasiparticles, as a Matrix Product Operator. The aforementioned steps constitute a constructive strategy to prepare an arbitrary input state for a quasiparticle scattering simulation in real time, and the scattering process itself can be carried out with any standard algorithm for time-evolution with Matrix Product States.In this thesis we explore numerical simulations, including Tensor Networks (TNs) methods, to study Hamiltonian Lattice Gauge Theories (LGTs), a numerical framework for investigating non-perturbative properties of Quantum Field Theories. We develop a model-independent approach for constructing Matrix Product Operators (MPOs) representations of 1-dimensional quasiparticles with definite momenta, and apply it to Hamiltonian Lattice Quantum Electrodynamics (QED) on a ladder geometry. By means of exact diagonalization at intermediate system sizes, we obtain the first excitation band states (the Bloch functions) representing the single-(quasi)particle states (the photons) expressed as entangled states of local lattice gauge fields. We then construct the corresponding maximally-localized Wannier functions through minimization of a spread functional. Once we identify, via a linear algebra problem, the operation that constructs the localized Wannier excitation from the ground state (dressed vacuum), we can express the creation operator, for any wavepacket of such quasiparticles, as a Matrix Product Operator. The aforementioned steps constitute a constructive strategy to prepare an arbitrary input state for a quasiparticle scattering simulation in real time, and the scattering process itself can be carried out with any standard algorithm for time-evolution with Matrix Product States

Magma mixing

In order to increase our understanding of magma mixing processes and their impact on the geochemical evolution of silicate melt we present in the following works, the first set of experiments performed using natural basaltic and rhyolitic melts. In particular, we investigate the interplay of physical dynamics and chemical exchanges between these two melts using time-series mixing experiments performed under controlled, chaotic, dynamical conditions. The variation of major and trace elements is studied in detail by electron microprobe (EMPA) and Laser Ablation ICP-MS (LA-ICP-MS) and the time-evolution of chemical exchanges during mixing is investigated. Using the concentration variance as a proxy to measure the rate of chemical element homogenization in time, a model to quantify chemical element mobility during chaotic mixing of natural silicate melts is proposed. The morphology of mixing patterns at different times is quantified by measuring their fractal dimension and an empirical relationship between mixing time and morphological complexity is derived. The complexity of mixing patterns is also compared to the degree of homogenization of chemical elements during mixing and empirical relationships are established between the fractal dimension and the variation of concentration variance of chemical elements in time. Finally we discuss the petrological and volcanological implications of this work.Um unser Verständnis über die Prozesse bei der Vermischung von Magmen und dessen Auswirkungen auf die geochemische Entwicklung von Silikatschmelzen zu verbessern, werden in dieser Arbeit erstmalig eine Reihe von „Magma Mixing“ Experimenten vorgestellt, in der natürliche Basalte und Rhyolite verwendet werden. In dynamischen Zeitreihen-Mischungsexperimenten, die unter kontrollierten, chaotischen, dynamischen, Bedingungen abliefen, wurde vor allem das Zusammenspiel der physikalischen Prozessen durch das mechanische Vermengen zweier Schmelzen und der resultierenden chemischen Austauschreaktionen durch Diffusion an den Grenzflächen zwischen diesen beiden Schmelzen untersucht. Die Variation von Haupt- und Spurenelementen wurde mittels Elektronen-Mikrosonde (EMPA) und Laser Ablation ICP-MS (LA-ICP-MS) im Detail untersucht und zusätzlich konnte die zeitliche Entwicklung des chemischen Austauschs während des Mischungsvorgang dargestellt werden. Die Varianz der Konzentration einzelner Elemente über die Grenzflächen zwischen Basalt und Rhyolit hinweg wurde als Proxy verwendet, um die Homogenisierungsrate der chemischen Elemente bezogen auf die Zeit zu bestimmen. Dies wird als Modell vorgeschlagen, mit dem die Mobilität chemischer Elemente während chaotischem Mischens von natürlichen Silikatschmelzen quantifiziert werden kann. Im Weiteren wurde mit Hilfe von Fraktalanalyse die Morphologie der Mischungsmustern zu unterschiedlichen Zeiten quantifiziert und eine empirische Beziehung zwischen Mischzeit und morphologischer Komplexität abgeleitet. Die Komplexität der Mischungsmuster wurde zudem mit dem Grad der Homogenisierung der chemischen Elemente während des Mischens verglichen. Dadurch konnten empirische Beziehungen zwischen der fraktalen Dimension von Mischungsmorphologien und der zeitlichen Variation der Konzentration von chemischen Elementen abgeleitet werden. Im Laufe dieser Arbeit werden zudem die petrologischen und vulkanologischen Auswirkungen diskutiert

volcanic ash aggregation enhanced by seawater interaction the case of the secche di lazzaro phreatomagmatic deposit stromboli

The Secche di Lazzaro formation (ca. 6.2-7 kys BP) is a phreatomagmatic deposit situated in the southwestern part of the island of Stromboli (Aeolian Archipelago, Italy). The volcanic sequence is comprised of three main units. In the lower unit accretionary lapilli are particularly abundant and are characterized by strong cementation between the particles and an uncommon resistance to breakage. To understand the processes behind the formation of the Secche di Lazzaro (SdL) accretionary lapilli a multi-analytical approach was used on the lapilli Aggregate Tuff (AT), and on single Accretionary Lapilli (AL). We carried out granulometric analysis, Field Emission – Scanning Electron Microscopy (FE-SEM), Electron Microprobe Analysis (EMPA), X-ray powder diffraction (XRPD) and 3D imaging by X-ray micro-tomography (X-mCT). The granulometric data show that most particles in the AT have a diameter equal to Φ -1 corresponding to 2 mm. The EMPA, FE-SEM and XRPD analyses reveal the presence of different mineral phases, mainly plagioclase, K-feldspar, halite, and clinopyroxene, together with volcanic glass. From the X-mCT analysis, we constrained the particle distribution and estimated the porosity of AL. The results of the FE-SEM images provided the chemical distribution within individual lapilli allowing the identification of rim and core zoning as well as the presence of halite located both on the border of single lapilli and on the juncture between different lapilli. Moreover, halite occurs among different aggregates in single AL, thus acting as a binding agent, as well as within rim pores. The results of this work shed new light into the formation of accretionary lapilli in phreatomagmatic eruption a t volcanic island involving marine water

1. On the Effects of the Introduction of the Deficit Reduction Plans on the Dynamic of the Public Health Expenditure in Italy. 2. Heterogeneous Expectations and Stock Market Participation

LUISS PhD Thesi

Ascoltare, sentire, non sentire: La voce del silenzio in Pianissimo (1914)

Nell’esperienza sbarbariana l’udito è il senso presente in absentia. Il diario lirico di Pianissimo deriva dall’incapacità di sentire e di sentirsi. Da un lato la raccolta rivela il bisogno urgente di raccontare e raccontarsi, dall’altro denuncia la difficoltà -che presto si tramuta in impossibilità-di sentire e di sentirsi. Pertanto il poeta non più in grado di ascoltare la voce della propria anima, è costretto a rinunciare alla propria essenza, al linguaggio della poesia . Derubato della sua identità, elegge il mondo fenomenico dello sguardo quale unica forma di sopravvivenza e, rinunciando ad ogni forma di trascendenza, si fa cosa tra le cose, aderendo, inevitabilmente, «ad ogni pietra della città sorda». Questo processo di reificazione, tuttavia, non avviene né senza tensioni, né senza contraddizioni, derivando entrambe dal disagio e dal tormento di chi vive «la tremenda privazione d’ogni consenso con la vita»

A Virtual Village Network Architecture for improving the elderly people quality of life

Elder people often feel pushed to the margins by the generational shift and suffer from loss of identity and hence they lose motivation, recognition and self-esteem: they are often considered to be no longer capable of performing any service. This paper proposes an ICT network architecture oriented to improve the quality of life of elderly people and their caregivers focused on the user need satisfaction and reducing negative feelings like insecurity, vulnerability, loneliness and depression. This Virtual Village Network architecture is organized on 3 levels: 1. the Virtual Service Centre (VSC) that, through a proper home interface, carries out the support, the monitoring, the prevention and the social facilitation; 2. the Intelligent Domotic Health Networks (DHN) a domotic modular network with high local evaluation ability through which the VSC can monitor the home and/or the user’s state of wellness and of health ; 3. the Dynamical Village Network (DVN) that is an ICT network of users. The idea is to build an ICT network of “virtual social neighbours” facilitating user relationships, able to have positive influences on the interactive abilities and self-image of the elderly, and to prevent or overcome solitude, isolation and their negative effects on the elderly person’s overall quality of life and health. The whole architecture is pervaded by strict attention paid to security and privacy

Cell wall component and mycotoxin moieties involved in binding of fumonisin B1 and B2 by lactic acid bacteria.

International audienceAims: The ability of lactic acid bacteria (LAB) to bind fumonisins B1 and B2 (FB1, FB2) in fermented foods and feeds and in the gastrointestinal tract could contribute to decrease their bioavailability and toxic effects on farm animals and humans. The aim of this work was to identify the bacterial cell wall component(s) and the functional group(s) of FB involved in the LAB-FB interaction. Methods and Results: The effect of physicochemical, enzymatic and genetic treatments of bacteria and the removal/inactivation of the functional groups of FB on toxin binding were evaluated. Treatments affecting the bacterial wall polysaccharides, lipids and proteins increased binding, while those degrading peptidoglycan (PG) partially decreased it. In addition, purified PG from Gram-positive bacteria bound FB in a manner analogue to that of intact LAB. For FB, tricarballylic acid (TCA) chains play a significant role in binding as hydrolysed FB had less affinity for LAB. Conclusions: Peptidoglycan and TCA are important components of LAB and FB, respectively, involved in the binding interaction. Significance and Impact of the Study: Lactic acid bacteria binding efficiency seems related to the peptide moiety structure of the PG. This information can be used to select probiotics with increased FB binding efficiency