962 research outputs found
Structure from motion systems for architectural heritage. A survey of the internal loggia courtyard of Palazzo dei Capitani, Ascoli Piceno, Italy
We present the results of a point-cloud-based survey deriving from the use of image-based techniques, in particular with multi-image monoscopic digital photogrammetry systems and software, the so-called “structure-from-motion” technique. The aim is to evaluate the advantages and limitations of such procedures in architectural surveying, particularly in conditions that are “at the limit”. A particular case study was chosen: the courtyard of Palazzo dei Capitani del Popolo in Ascoli Piceno, Italy, which can be considered the ideal example due to its notable vertical, rather than horizontal, layout. In this context, by comparing and evaluating the different results, we present experimentation regarding this single case study with the aim of identifying the best workflow to realise a complex, articulated set of representations—using 3D modelling and 2D processing—necessary to correctly document the particular characteristics of such an architectural object
Towards Quantum Superpositions of a Mirror: an Exact Open Systems Analysis - Calculational Details
We give details of calculations analyzing the proposed mirror superposition
experiment of Marshall, Simon, Penrose, and Bouwmeester within different
stochastic models for state vector collapse. We give two methods for exactly
calculating the fringe visibility in these models, one proceeding directly from
the equation of motion for the expectation of the density matrix, and the other
proceeding from solving a linear stochastic unravelling of this equation. We
also give details of the calculation that identifies the stochasticity
parameter implied by the small displacement Taylor expansion of the CSL model
density matrix equation. The implications of the two results are briefly
discussed. Two pedagogical appendices review mathematical apparatus needed for
the calculations.Comment: 9 pages, LaTeX. Minor changes mad
Analysing spatiotemporal patterns of Covid-19 confirmed deaths at the NUTS-2 regional level
During the ongoing Covid-19 pandemic, understanding the spatiotemporal patterns of the virus is crucial for policymakers to intervene promptly. The relevance of spatial proximity in the spread of the pandemic necessitates adequate tools, and noisy data must be properly treated. This study proposes obtaining clusters of European regions using smoothed curves of daily deaths from March 2020-March 2022. A functional representation of the curves
Comparing unconstrained parametrization methods for return covariance matrix prediction
Forecasting covariance matrices is a difficult task in many research fields since the predicted matrices should be at least positive semidefinite. This problem can be overcome by including constraints in the predictive model or through a parametrization of the matrices to be predicted. In this paper, we focus on the latter approach in a financial application and analyse four parametrizations of the covariance matrices of asset returns. The aim of the manuscript is to understand if the parametrizations of the covariance matrices exhibit differences in terms of predictive accuracy. To this end, we critically analyse their predictive performance through both a Monte Carlo simulation and an empirical application with daily and weekly realized covariance matrices of stock assets. Our findings highlight that the Cholesky decomposition and the parametrization recently introduced by Archakov and Hansen are the overall best-performing methods in terms of forecasting accuracy
Responsive Urban Models by Processing Sets of Heterogeneous Data
This paper presents some steps in experimentation aimed at describing urban spaces made following the series of earthquakes that affected a vast area of central Italy starting on 24 August 2016. More specifically, these spaces pertain to historical centres of limited size and case studies that can be called "problematic" (due to complex morphological and settlement conditions, because they are difficult to access, or because they have been affected by calamitous events, etc.). The main objectives were to verify the use of sets of heterogeneous data that are already largely available to define a workflow and develop procedures that would allow some of the steps to be automated as much as possible. The most general goal was to use the experimentation to define a methodology to approach the problem aimed at developing descriptive responsive models of the urban space, that is, morphological and computer-based models capable of being modified in relation to the constantly updated flow of input data
Floquet Prethermalization in a Bose-Hubbard System
Periodic driving has emerged as a powerful tool in the quest to engineer new
and exotic quantum phases. While driven many-body systems are generically
expected to absorb energy indefinitely and reach an infinite-temperature state,
the rate of heating can be exponentially suppressed when the drive frequency is
large compared to the local energy scales of the system -- leading to
long-lived 'prethermal' regimes. In this work, we experimentally study a
bosonic cloud of ultracold atoms in a driven optical lattice and identify such
a prethermal regime in the Bose-Hubbard model. By measuring the energy
absorption of the cloud as the driving frequency is increased, we observe an
exponential-in-frequency reduction of the heating rate persisting over more
than 2 orders of magnitude. The tunability of the lattice potentials allows us
to explore one- and two-dimensional systems in a range of different interacting
regimes. Alongside the exponential decrease, the dependence of the heating rate
on the frequency displays features characteristic of the phase diagram of the
Bose-Hubbard model, whose understanding is additionally supported by numerical
simulations in one dimension. Our results show experimental evidence of the
phenomenon of Floquet prethermalization, and provide insight into the
characterization of heating for driven bosonic systems
Leptin, Ghrelin and TNF-α before and after Hypo-caloric Traditional Chinese Diet and Auricular Acupuncture
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Endovascular Treatment of Aorto-iliac Aneurysms: Four-year Results of Iliac Branch Endograft
Introduction: The aim of this report was to analyse early and mid-term outcomes of endovascular treatment (endovascular aneurysm repair, EVAR) for aorto-iliac aneurysms with the use of an iliac branch device (IBD). Report: A total of 85 EVAR procedures with IBD were electively carried out in 81 patients between September 2007 and August 2012. Technical success was obtained in 98.7% of the cases. The mean follow-up duration was 20.4 months (SD ± 15.4). There was one IBD occlusion (1.2%). Estimated 48 months' survival, freedom from re-intervention and branch occlusion were 76.7%, 88.3% and 98%, respectively. Conclusions: EVAR for aorto-iliac aneurysms using IBD is an effective procedure with low complication and re-intervention rates at mid-term follow-up
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