A comparison of semiglobal and local dense matching algorithms for surface reconstruction

Encouraged by the growing interest in automatic 3D image-based reconstruction, the development and improvement of robust stereo matching techniques is one of the most investigated research topic of the last years in photogrammetry and computer vision. The paper is focused on the comparison of some stereo matching algorithms (local and global) which are very popular both in photogrammetry and computer vision. In particular, the Semi-Global Matching (SGM), which realizes a pixel-wise matching and relies on the application of consistency constraints during the matching cost aggregation, will be discussed. The results of some tests performed on real and simulated stereo image datasets, evaluating in particular the accuracy of the obtained digital surface models, will be presented. Several algorithms and different implementation are considered in the comparison, using freeware software codes like MICMAC and OpenCV, commercial software (e.g. Agisoft PhotoScan) and proprietary codes implementing Least Square e Semi-Global Matching algorithms. The comparisons will also consider the completeness and the level of detail within fine structures, and the reliability and repeatability of the obtainable data

Seismic Response Analysis of Continuous Multispan Bridges with Partial Isolation

Partially isolated bridges are a particular class of bridges in which isolation bearings are placed only between the piers top and the deck whereas seismic stoppers restrain the transverse motion of the deck at the abutments. This paper proposes an analytical formulation for the seismic analysis of these bridges, modelled as beams with intermediate viscoelastic restraints whose properties describe the pier-isolator behaviour. Different techniques are developed for solving the seismic problem. The first technique employs the complex mode superposition method and provides an exact benchmark solution to the problem at hand. The two other simplified techniques are based on an approximation of the displacement field and are useful for preliminary assessment and design purposes. A realistic bridge is considered as case study and its seismic response under a set of ground motion records is analyzed. First, the complex mode superposition method is applied to study the characteristic features of the dynamic and seismic response of the system. A parametric analysis is carried out to evaluate the influence of support stiffness and damping on the seismic performance. Then, a comparison is made between the exact solution and the approximate solutions in order to evaluate the accuracy and suitability of the simplified analysis techniques for evaluating the seismic response of partially isolated bridges

Sorting of multiple molecular species on cell membranes

Eukaryotic cells maintain their inner order by a hectic process of distillation of molecular factors taking place on the surface of their lipid membranes. To understand the properties of this molecular sorting process, a physical model of the process has been recently proposed [arXiv:1811.06760], based on (a) the phase separation of a single, initially dispersed molecular species into spatially localized sorting domains on the lipid membrane, and (b) domain-induced membrane bending leading to the nucleation of submicrometric lipid vesicles, naturally enriched in the molecules of the engulfed sorting domain. The analysis of the model has shown the existence of an optimal region of the parameter space where sorting is most efficient. Here, the model is extended to account for the simultaneous distillation of a pool of distinct molecular species. We find that the mean time spent by sorted molecules on the membrane increases with the heterogeneity of the pool (i.e., the number of distinct molecular species sorted) according to a simple scaling law, and that a large number of distinct molecular species can in principle be sorted in parallel on a typical cell membrane region without significantly interfering with each other. Moreover, sorting is found to be most efficient when the distinct molecular species have comparable homotypic affinities. We also consider how valence (i.e., the average number of interacting neighbors of a molecule in a sorting domain) affects the sorting process, finding that higher-valence molecules can be sorted with greater efficiency than lower-valence molecules

Intrapartum cardiotocography patterns observed in suspected clinical and subclinical chorioamnionitis in term fetuses.

AIM: To evaluate the cardiotocography (CTG) features observed in suspected intrapartum chorioamnionitis in term fetuses according to the recently suggested criteria for the pathophysiological interpretation of the fetal heart rate and their correlation with perinatal outcomes. METHODS: Retrospective analysis of nonconsecutive CTG traces. 'CTG chorioamnionitis' was diagnosed either based on a persistent rise in the baseline for the given gestation or on a persistent increase in the baseline fetal heart rate during labor >10% without preceding CTG signs of hypoxia and in the absence of maternal pyrexia. Perinatal outcomes were compared among cases with no sign of chorioamnionitis, in those with only CTG features suspicious for chorioamnionitis and in those who developed clinical chorioamnionitis. RESULTS: Two thousand one hundred and five CTG traces were analyzed. Of these, 356 fulfilled the criteria for "CTG chorioamnionitis". Higher rates of Apgar <7 at 1 and 5 min (21.6% vs 9.0% and 9.8% vs 2.0%, respectively, P < 0.01 for both) and lower umbilical artery pH (7.14 ± 0.11 vs 7.19 ± 0.11, P < 0.01) and an over fivefold higher rate of neonatal intensive care unit admission (16.6% vs 2.9%, P < 0.01) were noted in the 'CTG chorioamnionitis' group. Differences in the incidence of abnormal CTG patterns were noted between cases who eventually had clinical evidence of chorioamnionitis (89/356) and those showing CTG features suspicious for chorioamnionitis in the absence of clinical evidence of chorioamnionitis (267/356). CONCLUSION: Intrapartum CTG features of suspected chorioamnionitis are associated with adverse perinatal outcomes

First-trimester fetal neurosonography: technique and diagnostic potential

Most of the brain abnormalities are present in fact also at first trimester but only a few of these are detected at such early stage. According to the current recommendations for the first trimester ultrasound, the fetal head structures that should be visualized are limited to the cranial bones, the midline falx and the choroid-plexus-filled ventricles. Using this basic approach almost all cases of acrania, alobar holoprosencephaly and cephalocele are usually detected, however the majority of the other abnormalities of the fetal central nervous system remain undiagnosed until midtrimester. Such anomalies are potentially detectable if the sonographic study is extended to additional anatomic details which are not currently included in the existing guidelines. The aim of this review article is to describe how to assess the normal fetal brain at first trimester expert multiplanar neurosonography and to demonstrate the early sonographic findings which characterize some major fetal brain abnormalities. This article is protected by copyright. All rights reserved

The entropy of randomized network ensembles

Randomized network ensembles are the null models of real networks and are extensivelly used to compare a real system to a null hypothesis. In this paper we study network ensembles with the same degree distribution, the same degree-correlations or the same community structure of any given real network. We characterize these randomized network ensembles by their entropy, i.e. the normalized logarithm of the total number of networks which are part of these ensembles. We estimate the entropy of randomized ensembles starting from a large set of real directed and undirected networks. We propose entropy as an indicator to assess the role of each structural feature in a given real network.We observe that the ensembles with fixed scale-free degree distribution have smaller entropy than the ensembles with homogeneous degree distribution indicating a higher level of order in scale-free networks.Comment: (6 pages,1 figure,2 tables

Zircon as a provenance tracer: Coupling Raman spectroscopy and Usingle bondPb geochronology in source-to-sink studies

Usingle bondPb zircon geochronology is one of the most widely used techniques in sedimentary provenance analysis. Unfortunately, the ability of this method to identify sediment sources is often degraded by sediment recycling and mixing of detritus from different source rocks sharing similar age signatures. These processes create non-unique zircon Usingle bondPb age signatures and thereby obscure the provenance signal. We here address this problem by combining detrital zircon Usingle bondPb geochronology with Raman spectroscopy. The position and width of the Raman signal in zircon scales with its degree of metamictization, which in turn is sensitive to temperature. Thus, combined U-Pb + Raman datasets encode information about the crystallization history of detrital zircons as well as their thermal history. Using three borehole samples from Mozambique as part of a source-to-sink study of interest for hydrocarbon exploration, we show that zircon populations with similar Usingle bondPb age distributions can exhibit different Raman signatures. The joint U-Pb + Raman analysis allowed us to identify three different annealing trends, which were linked to specific thermal events. Thus we were able to differentiate a dominant Pan-African Usingle bondPb age peak into several sub-populations and highlight the major effect of Karoo tectono-magmatic events. In our case study, we used Raman also as a means to systematically identify all zircon grains in heavy-mineral mounts, resulting in considerable time savings. Raman spectroscopy is a non-destructive and cost-effective method that is easily integrated in the zircon Usingle bondPb dating workflow to augment the resolution power of detrital zircon Usingle bondPb geochronology

ISUOG Safety Committee updated recommendation on use of respirators by practitioners undertaking obstetric and gynecological ultrasound in context of SARS-CoV-2 Omicron variant of concern

status: publishe

Design methods for existing r.c. frames equipped with elasto-plastic or viscoelastic dissipative braces

Dissipative braces have proven to be very efficient devices for new buildings and seismic retrofitting of existing structures. In this paper a design method for dissipative braces based on elastic-plastic or viscoelastic behaviour, inserted in reinforced concrete existing frames with limited ductility, is proposed. The design method takes into account the dissipative behaviour of both the two components (r.c. frame and dampers). With regard to elasticplastic devices, buckling restrained braces (BRBs) are considered, whereas High Damping Rubber (HDR) based devices are considered as viscoelastic devices. The behaviour of HDR is quite complex and both stiffness and damping depend on the strain amplitude and strain rate. Equivalent linear models may however be used to simulate their behaviour at a fixed displacement amplitude and frequency, with an acceptable approximation level