Explicit characterization of the identity configuration in an Abelian Sandpile Model

Since the work of Creutz, identifying the group identities for the Abelian Sandpile Model (ASM) on a given lattice is a puzzling issue: on rectangular portions of Z^2 complex quasi-self-similar structures arise. We study the ASM on the square lattice, in different geometries, and a variant with directed edges. Cylinders, through their extra symmetry, allow an easy determination of the identity, which is a homogeneous function. The directed variant on square geometry shows a remarkable exact structure, asymptotically self-similar.Comment: 11 pages, 8 figure

ANALYSIS OF THE TRADITIONAL PASSIVE SYSTEMS PERFORMANCE THROUGH THE APPLICATION OF CFD SOFTWARE

The need to reduce energy consumption is pushing the building design research to the evaluation of passive conditioning systems, since urban buildings are one of the major energy dissipater resulting in emission of CO2. This approach is not modern, but it is historically rooted in the architectural culture of the Mediterranean area and in the Middle East. The passive systems have ancient origins: they were developed to mitigate the summer heat and the winter cold. To understand the reasons that led to the development of passive systems, it should be remembered that about One-Fifth of the emerged planet surface and One-Third of the world's population live in conditions of warm-dry or hot-humid. In addition, most continental areas, even above high values of latitude (50\ub0), are characterized by climatic conditions with summer temperatures over the limit levels of comfort. Nowadays the scientific knowledge and the modern technologies allow to understand the working of passive systems in order to apply them on buildings to improve indoor comfort. This can be obtained through a new approach that involves the elaboration of design strategies based on the development of techniques and on computational and control tools. This work will show the results of a research that aims to verify the working of natural passive cooling systems employed in existing ancient buildings throughout CFD (Computational Fluid Dynamic) software application. Particularly we will define, through computational tools, models and study cases to compare and to set proposals able to actualize the original passive systems conceived and developed in an empirical way

New Developments in the Spectral Asymptotics of Quantum Gravity

A vanishing one-loop wave function of the Universe in the limit of small three-geometry is found, on imposing diffeomorphism-invariant boundary conditions on the Euclidean 4-ball in the de Donder gauge. This result suggests a quantum avoidance of the cosmological singularity driven by full diffeomorphism invariance of the boundary-value problem for one-loop quantum theory. All of this is made possible by a peculiar spectral cancellation on the Euclidean 4-ball, here derived and discussed.Comment: 7 pages, latex file. Paper prepared for the Conference "QFEXT05: Quantum Field Theory Under the Influence of External Conditions", Barcelona, September 5 - September 9, 2005. In the final version, the presentation has been further improved, and yet other References have been adde

Machine-Learning Based Microwave Sensing: A Case Study for the Food Industry

Despite the meticulous attention of food industries to prevent hazards in packaged goods, some contaminants may still elude the controls. Indeed, standard methods, like X-rays, metal detectors and near-infrared imaging, cannot detect lowdensity materials. Microwave sensing is an alternative method that, combined with machine learning classifiers, can tackle these deficiencies. In this paper we present a design methodology applied to a case study in the food sector. Specifically, we offer a complete flow from microwave dataset acquisition to deployment of the classifiers on real-time hardware and we show the effectiveness of this method in terms of detection accuracy. In the case study, we apply the machine-learning based microwave sensing approach to the case of food jars flowing at high speed on a conveyor belt. First, we collected a dataset from hazelnutcocoa spread jars which were uncontaminated or contaminated with various intrusions, including low-density plastics. Then, we performed a design space exploration to choose the best MLPs as binary classifiers, which resulted to be exceptionally accurate. Finally, we selected the two most light-weight models for implementation on both an ARM-based CPU and an FPGA SoC, to cover a wide range of possible latency requirements, from loose to strict, to detect contaminants in real-time. The proposed design flow facilitates the design of the FPGA accelerator that might be required to meet the timing requirements by using a high-level approach, which might be suited for the microwave domain experts without specific digital hardware skills

ISOGAL-DENIS detection of red giants with weak mass loss in the Galactic Bulge

The ISOGAL project is a survey of the stellar populations, structure, and recent star formation history of the inner disk and bulge of the Galaxy. ISOGAL combines 15 and 7micron ISOCAM observations with DENIS IJKs data to determine the nature of a source and the interstellar extinction. In this paper we report an ISOGAL study of a small field in the inner Galactic Bulge (l=0deg, b=1.0deg, area=0.035 sq. deg) as a prototype of the larger area ISOGAL survey of the inner Galaxy. The five wavelengths of ISOGAL+DENIS, together with the relatively low and constant extinction in front of this specific field, allow reliable determination of the nature of the sources. The primary scientific result of this paper is evidence that the most numerous class of ISOGAL 15micron sources are Red Giants in the Galactic bulge and central disk, with luminosities just above or close to the RGB tip and weak mass-loss rates. They form loose sequences in the magnitude-colour diagrams [15]/Ks-[15] and [15]/[7]-[15]. Their large excesses at 15micron with respect to 2micron and 7micron is due to circumstellar dust produced by mass-loss at low rates. These ISOGAL results are the first systematic evidence and study of dust emission at this early stage (''Intermediate'' AGB), before the onset of the large mass-loss phase. It is thus well established that efficient dust formation is already associated with such low mass-loss rates during this early phase.Comment: 15 pages, 9 figures, accepted for publication in Astronomy and Astrophysics Journa

Somatostatin receptor PET/CT imaging for the detection and staging of pancreatic NET. A systematic review and meta-analysis

We investigated the diagnostic performance of Somatostatin Receptor Positron Emission Tomography/Computed Tomography (SSR-PET/CT) for the detection of primary lesion and initial staging of pancreatic neuroendocrine tumors (pNETs). A comprehensive literature search up to January 2020 was performed selecting studies in presence of: sample size ≥10 patients; index test (i.e., 68Ga-DOTATOC or 68Ga-DOTANOC or 68Ga-DOTATATE PET/CT); and outcomes (i.e., detection rate (DR), true positive, true negative, false positive, and false-negative). The methodological quality was evaluated with QUADAS-2. Pooled DR and pooled sensitivity and specificity for the identification of the primary tumor were assessed by a patient-based and a lesion-based analysis. Thirty-eight studies were selected for the qualitative analysis, while 18 papers were included in the meta-analysis. The number of pNET patients ranged from 10 to 142, for a total of 1143 subjects. At patient-based analysis, the pooled sensitivity and specificity for the assessment of primary pNET were 79.6% (95% confidence interval (95%CI): 71–87%) and 95% (95%CI: 75–100%) with a heterogeneity of 59.6% and 51.5%, respectively. Pooled DR for the primary lesion was 81% (95%CI: 65–90%) and 92% (95%CI: 80–97%), respectively, at patient-based and lesion-based analysis. In conclusion, SSR-PET/CT has high DR and diagnostic performances for primary lesion and initial staging of pNETs

Probing the quantum-gravity realm with slow atoms

For the study of Planck-scale modifications of the energy-momentum dispersion relation, which had been previously focused on the implications for ultrarelativistic (ultrafast) particles, we consider the possible role of experiments involving nonrelativistic particles, and particularly atoms. We extend a recent result establishing that measurements of "atom-recoil frequency" can provide insight that is valuable for some theoretical models. And from a broader perspective we analyze the complementarity of the nonrelativistic and the ultrarelativistic regimes in this research area.Comment: LaTex, 13 page