1,713 research outputs found
Geometric and topological aspects of quantum defects
No full textIn this thesis we present a detailed study of the dynamics of closed, twisted quantum vortices in Bose-Einstein condensates already published in two papers (Foresti & Ricca, 2019; Foresti & Ricca 2020). The study of how geometric and topological features affect the dynamics of vortices is very important for the description of interactions between vortices and for their reconnections. We generalize twist for quantum defects defying the concept of \emph{twist phase}. Then we find a modified Gross-Pitaevskii equation for the time evolution of a twisted vortex state. We discover that such a state is unstable and its evolution is dominated by a non-Hermitian Hamiltonian underlying the non-reversibility nature of the dynamics of twisted defects. Using the hydrodynamics description of Bose-Einsteins condensates and applying Kleinert's theory (Kleinert, 2018) to manage multi-valued phase fields, we find a complete set of integro-differential equations that quantitatively describe the dynamics of twisted vortices. Depending on the nature of the twist phase injected we propose two different stabilization mechanisms: if the twist phase is global then a secondary, central vortex is produced changing the linking number of the system. This mechanism can be seen as dominated by the presence of a topological phase and it is analyzed using Kleinert's theory. We thus prove theoretically what has been discovered numerically in (Zuccher & Ricca, 2018). In case of a local twist phase, no secondary vortex will form and the system produces unstable Kelvin waves with exponentially growing amplitude in regions where \Lapl\theta_{tw} > 0. We demonstrate that to minimize the energy and to stabilize the system the vortex coils producing non-zero writhe and extinguishing its twist phase. This mechanism can be seen as produced by the effect of a geometric phase on the system. We also propose an experiment to inject a twist phase on a quantum vortex in order to prove or disprove such stabilization mechanisms.
Bibliography.
Foresti, M. and Ricca, R. L. 2019
Defect production by pure twist induction as Aharonov-Bohm effect.
\textit{Phys. Rev. E} \textbf{100}, 023107.
M. Foresti \& R.L. Ricca,
Hydrodynamics of a quantum vortex in presence of twist.
\textit{J. Fluid Mech.} \textbf{904}, A25.
Kleinert, H. 2008
\textit{Multivalued Fields in Condensed Matter, Electromagnetism and Gravitation}.
World Scientific, Singapore.
Zuccher, S. and Ricca, R. L. 2018,
Twist effects in quantum vortices and phase defects.
\textit{Fluid Dyn. Res.} \textbf{50}, 1--13
Twist effects on quantum vortex defects
No full textWe demonstrate that on a quantum vortex in Bose-Einstein condensates can form a new, central phase singularity. We define the twist phase for isophase surfaces and show that if the injection of a twist phase is global this phenomenon is given by an analog of the AharonovBohm effect. We show analytically that the injection of a twist phase makes the filament unstable, that is the GP equation is modified by a new term that makes the Hamiltonian non-Hermitian. Using Kleinert’s theory for multi-valued fields we show that this instability is compensated by the creation of the second vortex, possibly linked with the first one
TUTELA DEL LAVORO E LIBERTA' D'IMPRESA NEI PROCESSI DI ESTERNALIZZAZIONE
No full textL’elaborato analizza le conseguenze lavoristiche della successione fra imprenditori, muovendo da una ricognizione delle varie tipologie di esternalizzazione con le relative esigenze e principali criticità.
L’indagine si concentra in primo luogo sul trasferimento d’azienda, esaminando la normativa e la giurisprudenza europee per passare poi alla disciplina di diritto interno, alle procedure sindacali e a uno specifico focus sul trasferimento delle aziende in crisi.
Successivamente l’autore si sofferma sull’appalto, prendendone in particolare considerazione gli indici di genuinità, i criteri di distinzione dalla somministrazione illecita di manodopera e la tutela delle maestranze in caso di avvicendamento fra imprese.
Da ultimo, la ricerca approfondisce le c.d. “clausole sociali”, sia di prima che di seconda generazione, valutandone la compatibilità con il diritto eurounitario e con la costituzione nonché riflettendo sui possibili rimedi in caso di loro violazione.The author analyzes the labour consequences of the succession between entrepreneurs, starting from a recognition of the various types of outsourcing with the related needs and main critical issues.
The survey focuses primarily on the transfer of businesses, examining European legislation and case-law and then moving on to internal legislation, trade union procedures and a specific focus on the transfer of companies in crisis.
The author then dwells on the contract, taking into account in particular the indications of authenticity, the criteria of distinction from the illicit administration of labour and the protection of workers in the event of turnover between companies.
Finally, the research deepens the "social clauses", both first and second generation, assessing their compatibility with European law and with the constitution and reflecting on possible remedies in case of their violation
Ultra Low Carbon Vehicles: New Parameters for Automotive Design
No full textAs the influence of vehicle emissions on our environment has become better understood, the UK government has recently placed urgent emphasis on the implementation of low carbon
technologies in the automotive industry through: the UK Low Carbon Industrial Strategy. The overall objective is to offer big incentives to consumers and support for the development of infrastructure and engineering solutions. This scheme however does not consider how the development of functional and experiential user value might drive consumer demand, contributing to the adoption of low carbon vehicles (LCVs) in the mass market.
With the emergence of the North East of England as the UK’s first specialised region for the development of ultra-low carbon vehicles (ULCVs), ONE North East, as a development agency for the region's economic and business development, and Northumbria University Ideas-lab have supported a project to facilitate innovation through the collaboration of technology, research and development (R&D) and business. The High Value Low Carbon (HVLC) project aims to envisage
new user value made possible by the integration of low carbon vehicle platforms with new process and network technologies. The HVLC consortium represents vehicle manufacturers and their suppliers as well as technology based companies and through an ongoing process of design concept generation the project offers a hub for innovation led enterprise.
Whilst new technological developments in areas such as power generation, nano materials, hydrogen fuel cells, printed electronics and networked communications will all impact on future automotive design, the mass adoption of low carbon technologies represents a paradigm shift for the motorist. This paper aims to describe how the mapping of new parameters will lead to new transport scenarios that will create the space for new collaborative research on user experiences supported by innovative technologies and related services
Recommended from our members
Matteo Maria Boiardo (1441-1494)
No full textMatteo Maria Boiardo – contemporary of Sir Thomas Malory and forerunner of Shakespeare, Spenser, Milton, Cervantes, Tolkien, and C.S. Lewis – is best known as the author of the Orlando Innamorato [Orlando in Love], a poem in ottava rima organically merging Carolingian epic and Arthurian romance. He was also a lyric and pastoral poet, playwright, and translator of classical texts into the Italian vernacular. Matteo was active in Italy during the years of 1463 throughout 1494, the year of his death
Uno sguardo all'Est. Lavoro e diritti fondamentali in Russia e negli altri Paesi della Comunità di Stati indipendenti
No full textNel contributo l'autore, dopo aver esaminato i diritti fondamentali del lavoro presenti nelle Costituzioni dei Paesi della Comunità di Stati indipendenti, si sofferma sul diritto del lavoro russo. La trattazione, a carattere diacronico, abbraccia i rami principali del diritto del lavoro: il rapporto individuale, le relazioni collettive, il mercato del lavoro. L'autore rileva una sorprendente continuità nelle linee essenziali del diritto del lavoro russo, pur nel susseguirsi di sistemi socioeconomici completamente diversi. Egli conclude che il diritto del lavoro russo appartiene saldamente alla matrice europea della materia.The contribution of the author starts by examining fundamental labour rights recognised by the Constitutions of the Countries of the Community of Independent States. Then the author focuses upon Russian Labour Law, going through the history of the main branches of the discipline: the individual relationship, industrial relations, the labour market. The article finds a surprising continuity in the essential lines of Russian Labour Law, in spite of the completely different socio-economic systems that were experimented in Russia during the twentieth century. The author concludes that Russian Labour Law clearly belongs to the European matrix of the discipline
Efficient few-shot learning for pixel-precise handwritten document layout analysis
No full textLayout analysis is a task of uttermost importance in ancient handwritten
document analysis and represents a fundamental step toward the simplification
of subsequent tasks such as optical character recognition and automatic
transcription. However, many of the approaches adopted to solve this problem
rely on a fully supervised learning paradigm. While these systems achieve very
good performance on this task, the drawback is that pixel-precise text labeling
of the entire training set is a very time-consuming process, which makes this
type of information rarely available in a real-world scenario. In the present
paper, we address this problem by proposing an efficient few-shot learning
framework that achieves performances comparable to current state-of-the-art
fully supervised methods on the publicly available DIVA-HisDB dataset.Comment: Accepted for publication at IEEE/CVF Winter Conference on
Applications of Computer Vision (WACV), 202
Corpo, spazio, architettura. Fenomenologia dell’esperienza spaziale Matteo Vegetti, Fabrizia Bandi (eds.), Editrice Morcelliana, Brescia 2024
No full textThe author reviews "Corpo, spazio, architettura: Fenomenologia dell’esperienza spaziale," edited by Matteo Vegetti and Fabrizia Bandi. The book examines the philosophical underpinnings of spatial experience through a phenomenological lens, engaging with both traditional and contemporary notions of how space, body, and architecture interconnect. The author highlights the text\u27s exploration of how architects and designers might integrate phenomenological insights into their work, transforming space from mere physical dimensions into lived, experienced reality. The review appreciates the book’s thematic organization, which starts with foundational theories from Merleau-Ponty and expands through discussions on virtual spaces and the future of architecture in the digital age. Through this anthology, readers gain a comprehensive view of the architectural implications of phenomenological thought, making it a critical resource for anyone involved in the conceptualization and design of space
- …
