Relevant bibliographies by topics / Blocchi a gravità

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  2. Dissertations / Theses

Academic literature on the topic 'Blocchi a gravità'

Author: Grafiati
Published: 4 June 2021
Last updated: 4 February 2022

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Journal articles on the topic "Blocchi a gravità"

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Schewe, Phillip F. "Bloch oscillations measure gravity." Physics Today 59, no. 10 (October 2006): 22. http://dx.doi.org/10.1063/1.4797303.

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Brito, F. A., L. Losano, and J. R. L. Santos. "The extension method for Bloch branes." International Journal of Modern Physics A 36, no. 10 (April 10, 2021): 2150075. http://dx.doi.org/10.1142/s0217751x21500755.

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The nature of gravity and its strength compared with other forces are fundamental challenges faced by the actual science. A path to understand the hierarchy problem of gravity consists in adding an extra dimension to Einstein–Hilbert’s general relativity. Therefore, gravity would be the only force leaking through this region of space–time also known as brane. Despite the success of the mathematical description for the hierarchy issue through simple thin branes, it is also possible to derive a consistent theory of gravity using thick branes. This work unveils a new procedure to determine analytic hybrid thick braneworld models. The discussions were based on the so-called Bloch branes, which are constructed via a two-field model coupled with gravity in five-dimensional space–time. Both fields used to build the Bloch branes depend only on the extra dimension, and the hybrid branes present internal structure, characterizing them as thick. In this work, we were able to derive new analytic thick brane models by using the extension method. Some of these new branes present a Minkowski space–time immersed inside of the fifth dimension. We showed how the symmetry of the emergent branes can be controlled via specific parameters. We also analyzed the stability conditions for each braneworld family, showing possible stable states for gravitons.
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Papini, Giorgio. "Condensation phenomena in gravity." Modern Physics Letters A 35, no. 30 (July 27, 2020): 2050250. http://dx.doi.org/10.1142/s0217732320502508.

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Gravity can play a role in critical phenomena. Topological singularities induce ground state degeneracy and break the continuum symmetry of the vacuum. They also generate momenta oscillations about an average momentum and a positive gravitational susceptibility. Gravitational analogues of the laws of Curie and Bloch have been found for a one-dimensional model. The critical temperature for a change in phase from bound to unbound vortices has also been calculated in a XY-model.
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Artoni, M., G. C. La Rocca, and G. Ferrari. "Quasi-periodic Wannier–Stark ladders from driven atomic Bloch oscillations." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470, no. 2171 (November 8, 2014): 20140421. http://dx.doi.org/10.1098/rspa.2014.0421.

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Periodic Wannier–Stark ladder structures of the energy resonances associated with Bloch oscillations can be readily modified into quasi-periodic ones that exhibit peculiar self-similar effects. A compact theoretical description of the dynamics of driven Bloch oscillations is developed here within the quasi-momentum representation. We identify a rather viable scheme based on ultracold atomic wavepackets subject to gravity in a driven optical lattice potential where a self-similar scaling could be observed. Its feasibility in terms of realistic experimental parameters is also discussed.
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Marongwe, Stuart. "A Covariant Canonical Quantization of General Relativity." Advances in High Energy Physics 2018 (December 19, 2018): 1–7. http://dx.doi.org/10.1155/2018/4537058.

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A Hamiltonian formulation of General Relativity within the context of the Nexus Paradigm of quantum gravity is presented. We show that the Ricci flow in a compact matter free manifold serves as the Hamiltonian density of the vacuum as well as a time evolution operator for the vacuum energy density. The metric tensor of GR is expressed in terms of the Bloch energy eigenstate functions of the quantum vacuum allowing an interpretation of GR in terms of the fundamental concepts of quantum mechanics.
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Giampieri, Emanuela, Alessandra Ratti, Alessandra Beretta, Cinzia Mattavelli, Elena Ferrarini, Carlo Pruneri, and Italo Carta. "Determinants of hospitalization from psychiatric E.R. from S. Gerardo hospital in Monza: epidemiological cross-sectional study." Epidemiology and Psychiatric Sciences 11, no. 4 (December 2002): 266–76. http://dx.doi.org/10.1017/s1121189x00005844.

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RIASSUNTOScopo – Individuare i fattori predittivi di ricovero in pazienti che giungono presso il Pronto Soccorso con problem psichiatrici. Disegno – Studio epidemiologico trasversale condotto presso il Pronto Soccorso dell'Ospedale S. Gerardo di Monza, tra il 1 giugno 1995 ed il 31 maggio 1997. Sono stati inclusi tutti i soggetti di età maggiore di 18 anni per i quali sia stata richiesta una valutazione psichiatrica. E' stato sondato il peso di variabili socio-demografiche, di variabili cliniche e di variabili di servizio sulla decisione di ricovero. Principali misure utilizzate – I dati sono stati raccolti mediante una scheda appositamente costruita, compilata dal medico di guardia al momento della visita. I dati sono stati analizzati tramite analisi univariata e regressione logistica. Risultati – Sono stati raccolti dati inerenti 2076 casi. All'analisi univariata la probabilita di ricovero è risultata più elevata per soggetti tra i 39 ed i 48 anni, celibi o nubili, disoccupati, affetti da schizofrenia, da disturbi deH'umore o da disturbi di personalità. Il ricovero è più probabile in proporzione alia gravità, all'ideazione suicidiaria ed a precedenti ricoveri. Tra i sintomi troviamo che l'ansia protegge dal ricovero laddove allucinazioni, delirio, assenza di critica di malattia, blocco psicomotorio, agitazione psicomotoria, stato confusionale, crisi pantoclastiche, bizzarrie comportamentali, alterazioni dello stato di coscienza e precedenti ricoveri incrementano la probabilità di ospedalizzazione. Il lunedì ed il venerdì sono i giorni a più alta frequenza di ricoveri. La regressione logistica conferma il ruolo predittivo di età, sintomi, aggressività, gravità ed ideazione suicidiaria, e dei giorni della settimana tra le variabili di servizio. Conclusione – Tra i fattori predittivi di ricovero in SPDC le variabili cliniche mantengono un ruolo predominante, rispetto a fattori socio-demografici. Accanto a queste, tuttavia, si nota un peso rilevante deH'organizzazione del servizio con un aumento del tasso di ricoveri proprio nei giorni a cavallo del fine settimana, quando i servizi territoriali chiudono.
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Papini, Giorgio. "Some Classical and Quantum Aspects of Gravitoelectromagnetism." Entropy 22, no. 10 (September 27, 2020): 1089. http://dx.doi.org/10.3390/e22101089.

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It has been shown that, even in linear gravitation, the curvature of space-time can induce ground state degeneracy in quantum systems, break the continuum symmetry of the vacuum and give rise to condensation in a system of identical particles. Condensation takes the form of a temperature-dependent correlation over distances, of momenta oscillations about an average momentum, of vortical structures and of a positive gravitational susceptibility. In the interaction with quantum matter and below a certain range, gravity is carried by an antisymmetric, second order tensor that satisfies Maxwell-type equations. Some classical and quantum aspects of this type of “gravitoelectromagnetism” were investigated. Gravitational analogues of the laws of Curie and Bloch were found for a one-dimensional model. A critical temperature for a change in phase from unbound to isolated vortices can be calculated using an XY-model.
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Cladé, P., S. Guellati-Khélifa, C. Schwob, F. Nez, L. Julien, and F. Biraben. "A promising method for the measurement of the local acceleration of gravity using Bloch oscillations of ultracold atoms in a vertical standing wave." Europhysics Letters (EPL) 71, no. 5 (September 2005): 730–36. http://dx.doi.org/10.1209/epl/i2005-10163-6.

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Tseluiko, D., M. G. Blyth, and D. T. Papageorgiou. "Stability of film flow over inclined topography based on a long-wave nonlinear model." Journal of Fluid Mechanics 729 (July 24, 2013): 638–71. http://dx.doi.org/10.1017/jfm.2013.331.

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AbstractThe stability of a viscous liquid film flowing under gravity down an inclined wall with periodic corrugations is investigated. A long-wave model equation valid at near-critical Reynolds numbers is used to study the film dynamics, and calculations are performed for either sinusoidal or rectangular wall corrugations assuming either a fixed flow rate in the film or a fixed volume of fluid within each wall period. Under the two different flow assumptions, steady solution branches are delineated including subharmonic branches, for which the period of the free surface is an integer multiple of the wall period, and the existence of quasi-periodic branches is demonstrated. Floquet–Bloch theory is used to determine the linear stability of steady, periodic solutions and the nature of any instability is analysed using the method of exponentially weighted spaces. Under certain conditions, and depending on the wall period, the flow may be convectively unstable for small wall amplitudes but undergo transition to absolute instability as the wall amplitude increases, a novel theoretical finding for this class of flows; in other cases, the flow may be convectively unstable for small wall amplitudes but stable for larger wall amplitudes. Solutions with the same spatial period as the wall become unstable at a critical Reynolds number, which is strongly dependent on the period size. For sufficiently small wall periods, the corrugations have a destabilizing effect by lowering the critical Reynolds number above which instability occurs. For slightly larger wall periods, small-amplitude corrugations are destabilizing but sufficiently large-amplitude corrugations are stabilizing. For even larger wall periods, the opposite behaviour is found. For sufficiently large wall periods, the corrugations are destabilizing irrespective of their amplitude. The predictions of the linear theory are corroborated by time-dependent simulations of the model equation, and the presence of absolute instability under certain conditions is confirmed. Boundary element simulations on an inverted substrate reveal that wall corrugations can have a stabilizing effect at zero Reynolds number.
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Xie, Qun-Ying, Jie Yang, and Li Zhao. "Resonance mass spectra of gravity and fermion on Bloch branes." Physical Review D 88, no. 10 (November 12, 2013). http://dx.doi.org/10.1103/physrevd.88.105014.

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Dissertations / Theses on the topic "Blocchi a gravità"

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Anceschi, Stefano. "Progettazione della nuova banchina per attracco di navi Ro-Ro del porto di Valona (Albania) e inquadramento all'interno dei piani di sviluppo TEN-T." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.

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All’inizio del mese di luglio del 2015 prendono avvio a Valona i lavori previsti nell’ambito del progetto “Riabilitazione del porto di Valona”, finanziato dalla Cooperazione italiana con un contributo di oltre 15 milioni di euro a credito d’aiuto. Nella seguente Tesi di Laurea si analizza l’iniziativa che mira a modernizzare il complesso portuale della città in un’ottica di sviluppo integrato della regione, per supportare i crescenti flussi turistici e commerciali in entrata ed in transito. Il potenziamento del porto permetterà all’Albania di dotarsi di un porto moderno ed efficiente in linea con le normative UE, permettendo l’attracco di ben quattro navi contemporaneamente, con notevoli vantaggi sia a livello turistico che economico, principalmente nell’area Sud del Paese, ma in generale in tutta l’Albania. Si propone, progetta e dimensiona poi un ulteriore ampliamento futuro consistente nell’inserimento di un frangiflutti a massicciata con banchina interna atta ad accogliere navi Ro-Ro di dimensioni maggiori a quelle che attualmente possono attraccare nel porto. Se ne analizzano i vantaggi sia dal punto di vista materiale, ovvero in termini di protezione dal moto ondoso, che dal punto di vista economico, ossia come opera utile allo sviluppo commerciale e turistico del Sud dell’Albania. Il programma di riabilitazione e il progetto riguardante il frangiflutti mirano infatti a contribuire al piano nazionale dell’Albania di potenziamento delle infrastrutture e dei Trasporti marittimi e si inquadrano nelle previsioni di potenziamento di connessione degli Stati Balcanici alla rete TEN-T europea, rappresentandone, il porto di Valona, una delle possibili parti terminali sull’Adriatico. Si descrive inoltre come sviluppo del settore dei trasporti è considerato un catalizzatore per lo sviluppo economico, in quanto crea un potenziale di crescita stabilendo connessioni che non esistevano prima o migliorando la qualità delle connessioni esistenti.
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Gaharia, David. "Asymptotic Symmetries and Faddeev-Kulish states in QED and Gravity." Thesis, Stockholms universitet, Fysikum, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-166311.

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When calculating scattering amplitudes in gauge and gravitational theories one encounters infrared (IR) divergences associated with massless fields. These are known to be artifacts of constructing a quantum field theory starting with free fields, and the assumption that in the asymptotic limit (i.e. well before and after a scattering event) the incoming and outgoing states are non-interacting. In 1937, Bloch and Nordsieck provided a technical procedure eliminating the IR divergences in the cross-sections. However, this did not address the source of the problem: A detailed analysis reveals that, in quantum electrodynamics (QED) and in perturbative quantum gravity (PQG), the interactions cannot be ignored even in the asymptotic limit. This is due to the infinite range of the massless force-carrying bosons. By taking these asymptotic interactions into account, one can find a picture changing operator that transforms the free Fock states into asymptotically interacting Faddeev- Kulish (FK) states. These FK states are charged (massive) particles surrounded by a “cloud” of soft photons (gravitons) and will render all scattering processes infrared finite already at an S-matrix level. Recently it has been found that the FK states are closely related to asymptotic symmetries. In the case of QED the FK states are eigenstates of the large gauge transformations – U(1) transformations with a non-vanishing transformation parameter at infinity. For PQG the FK states are eigenstates of the Bondi-Metzner-Sachs (BMS) transformations – the asymptotic symmetry group of an asymptotically flat spacetime. It also appears that the FK states are related the Wilson lines in the Mandelstam quantization scheme. This would allow one to obtain the physical FK states through geometrical or symmetry arguments. We attempt to clarify this relation and present a derivation of the FK states in PQG from the gravitational Wilson line in the eikonal approximation, a result that is novel to this thesis.
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Flayac, Hugo. "Nouvelles tendances dans les condensats d'exciton-polaritons spineurs : défauts topologiques et structures de basse dimensionnalité." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00822148.

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Au long de ce manuscrit de thèse je présenterai des effets non linéaires émergents dans les condensats d'exciton-polaritons spineurs. Après un chapitre d'introduction amenant les notions de bases nécessaires, je me concentrerai dans une première partie sur les défauts topologiques quantifiés par des nombres demi-entiers et discuterai leur stabilité, accélération et nucléation en présence de champs magnétiques effectifs. Nous verrons que ces objets se comportent comme des charges magnétiques manipulables démontrant une analogie fascinante avec les monopoles de Dirac. De manière remarquable nous verrons également que ces objets peuvent être utilisés comme des signaux stables pour sonder la physique d'analogues acoustiques de trous noirs. Dans une seconde partie j'étudierai des structures de basse dimensions. Plus particulièrement, je décrirai la formation de solitons de bande interdite et les oscillations de Bloch des exciton-polaritons dans des microfils comportant des structures périodiques et d'autre part les oscillations Josephson à température ambiante dans des paires de micropilliers couplés.
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