25 research outputs found
Typicality in spin network states of quantum geometry
In this work, we extend the so-called typicality approach, originally
formulated in statistical mechanics contexts, to -invariant spin-network
states. Our results do not depend on the physical interpretation of the spin
network; however, they are mainly motivated by the fact that spin-network
states can describe states of quantum geometry, providing a gauge-invariant
basis for the kinematical Hilbert space of several background-independent
approaches to quantum gravity. The first result is, by itself, the existence of
a regime in which we show the emergence of a typical state. We interpret this
as the proof that in that regime there are certain (local) properties of
quantum geometry which are "universal". Such a set of properties is heralded by
the typical state, of which we give the explicit form. This is our second
result. In the end, we study some interesting properties of the typical state,
proving that the area law for the entropy of a surface must be satisfied at the
local level, up to logarithmic corrections which we are able to bound.Comment: Typos and mistakes fixe
Fisher Metric, Geometric Entanglement and Spin Networks
Starting from recent results on the geometric formulation of quantum
mechanics, we propose a new information geometric characterization of
entanglement for spin network states in the context of quantum gravity. For the
simple case of a single-link fixed graph (Wilson line), we detail the
construction of a Riemannian Fisher metric tensor and a symplectic structure on
the graph Hilbert space, showing how these encode the whole information about
separability and entanglement. In particular, the Fisher metric defines an
entanglement monotone which provides a notion of distance among states in the
Hilbert space. In the maximally entangled gauge-invariant case, the
entanglement monotone is proportional to a power of the area of the surface
dual to the link thus supporting a connection between entanglement and the
(simplicial) geometric properties of spin network states. We further extend
such analysis to the study of non-local correlations between two non-adjacent
regions of a generic spin network graph characterized by the bipartite
unfolding of an Intertwiner state. Our analysis confirms the interpretation of
spin network bonds as a result of entanglement and to regard the same spin
network graph as an information graph, whose connectivity encodes, both at the
local and non-local level, the quantum correlations among its parts. This gives
a further connection between entanglement and geometry.Comment: 29 pages, 3 figures, revised version accepted for publicatio
Biodiversity patterns of dry grasslands in the Central Apennines (Italy) along a precipitation gradient : experiences from the 10th EDGG Field Workshop
The 10th EDGG Field Workshop took place in a sector of the Central Apennine Mountains, Italy, in June 2017. Altogether, 22 researchers from nine European and Asian countries attended this Field Workshop. We sampled plant and insect biodiversity in submontane and lower-montane grasslands along a precipitation gradient, from the L’Aquila valley and the Fucino basin to the “Abruzzo, Lazio & Molise” National Park. The standardized EDGG sampling protocol, involving nested-plot series and additional 10-m2 relevés, was used. In the course of seven days of intensive fieldwork, we sampled 20 biodiversity plots along with 57 additional normal plots (yielding a total dataset of 97 10-m2 plots). Methodological additions tested in this workshop included the assessment of observer-related error (around 12% of the 10-m2 plots was resurveyed by a different team). In all plots, vascular plants, bryophytes and lichens were sampled. At each nested-plot series, also insects (Auchenorrhyncha) were sampled by local specialists, who developed an ad-hoc sampling procedure
Chronic constipation diagnosis and treatment evaluation: The "CHRO.CO.DI.T.E." study
Background: According to Rome criteria, chronic constipation (CC) includes functional constipation (FC) and irritable bowel syndrome with constipation (IBS-C). Some patients do not meet these criteria (No Rome Constipation, NRC). The aim of the study was is to evaluate the various clinical presentation and management of FC, IBS-C and NRC in Italy. Methods: During a 2-month period, 52 Italian gastroenterologists recorded clinical data of FC, IBS-C and NRC patients, using Bristol scale, PAC-SYM and PAC-QoL questionnaires. In addition, gastroenterologists were also asked to record whether the patients were clinically assessed for CC for the first time or were in follow up. Diagnostic tests and prescribed therapies were also recorded. Results: Eight hundred seventy-eight consecutive CC patients (706 F) were enrolled (FC 62.5%, IBS-C 31.3%, NRC 6.2%). PAC-SYM and PAC-QoL scores were higher in IBS-C than in FC and NRC. 49.5% were at their first gastroenterological evaluation for CC. In 48.5% CC duration was longer than 10 years. A specialist consultation was requested in 31.6%, more frequently in IBS-C than in NRC. Digital rectal examination was performed in only 56.4%. Diagnostic tests were prescribed to 80.0%. Faecal calprotectin, thyroid tests, celiac serology, breath tests were more frequently suggested in IBS-C and anorectal manometry in FC. More than 90% had at least one treatment suggested on chronic constipation, most frequently dietary changes, macrogol and fibers. Antispasmodics and psychotherapy were more frequently prescribed in IBS-C, prucalopride and pelvic floor rehabilitation in FC. Conclusions: Patients with IBS-C reported more severe symptoms and worse quality of life than FC and NRC. Digital rectal examination was often not performed but at least one diagnostic test was prescribed to most patients. Colonoscopy and blood tests were the "first line" diagnostic tools. Macrogol was the most prescribed laxative, and prucalopride and pelvic floor rehabilitation represented a "second line" approach. Diagnostic tests and prescribed therapies increased by increasing CC severity
Analisi economica degli interventi distribuiti di gestione dei deflussi urbani
L’applicazione degli interventi distribuiti di gestione dei deflussi urbani è stata effettuata finora in maniera piuttosto disomogenea in Europa ed in particolare in Italia, probabilmente anche in seguito alle difficoltà legate alla valutazione dell'efficienza idraulica ed economica di tali interventi. Obiettivo del presente lavoro è quello di analizzare l’aspetto economico di alcune BMP per quanto riguarda sia i costi di realizzazione sia quelli di manutenzione, nell’ottica della valutazione dell'efficienza delle BMP e delle problematiche relative alla implementazione di sistemi di drenaggio nel contesto della pianificazione territoriale.
Attraverso la classificazione, la descrizione e l’analisi approfondita di alcune tipologie di BMP è stato identificato, per ciascuna di esse, uno schema costruttivo di riferimento sulla base del quale è stata svolta una dettagliata valutazione dei costi, effettuando considerazioni anche sulle attività di manutenzione. Il calcolo del costo complessivo è basato sulla metodologia del Whole Life Costing (WLC)
Mesozoic Syn- and Postrifting Evolution of the Central Apennines, Italy: The Role of Triassic Evaporites
Jurassic-Cretaceous syn- and postrift successions from the central Apennines were backstripped to gain information on the Mesozoic evolution of the passive margin of the Adriatic Plate. Early Jurassic rifting led to the development of a horst-and-graben paleogeography (the Latium-Abruzzi Carbonate Platform and the Sabina-Umbria-Marche Pelagic Basin). Subsidence curves were built for both carbonate platform and pelagic-basin domains from original and literature stratigraphic data. The paleodepositional depths of the deepwater sediments were reconstructed from field geology data, including new paleontological data. It is proposed that after the deposition of lower Hettangian shallow-water carbonates, an abrupt increase in paleowater depth, to 600-1000 m, occurred during the late Hettangian-Sinemurian synrift stage. The postrift stage was characterized by basin filling, with decreasing paleowater depths during the Jurassic, and by a new deepening during the Cretaceous. Our backstripping curves show, for the Sabina-Umbria-Marche Basin, a short period (<5 m.yr.) of rapid tectonic subsidence at the beginning of the Jurassic, followed by very slow (likely thermally controlled) or absent tectonic subsidence until the Cretaceous. The slight increase in subsidence observed from Cenomanian time is linked to a renewal of extensional tectonics. The Latium-Abruzzi Carbonate Platform shows variable subsidence rates in both place and time. Fast subsidence occurred in the Rhaetian-Hettangian, Toarcian, Berriasian, and Cenomanian and is linked with extensional or transtensional tectonic events. After the Early Jurassic rifting, subsidence rates (on average 30-40 m/m.yr.) affecting the Latium-Abruzzi Carbonate Platform were faster than those recorded by the Sabina-Umbria-Marche Basin. Faster postrift subsidence in carbonate platform areas is a geological paradox that is here explained by the lateral flow of upper Triassic evaporites toward the deepwater domains, as a result of higher sedimentary loading in the carbonate platform areas and the onset of a pressure gradient toward the pelagic basin at the depth of the evaporites