Giant nonlinear response at the nanoscale driven by bound states in the continuum

Being motivated by the recent prediction of high-$Q$ supercavity modes in subwavelength dielectric resonators, we study the second-harmonic generation from isolated subwavelength AlGaAs nanoantennas pumped by a structured light. We reveal that nonlinear effects at the nanoscale can be enhanced dramatically provided the resonator parameters are tuned to the regime of the bound state in the continuum. We predict a record-high conversion efficiency for nanoscale resonators that exceeds by two orders of magnitude the conversion efficiency observed at the conditions of magnetic dipole Mie resonance, thus opening the way for highly-efficient nonlinear metadevices.Comment: 7 pages, 4 figures, 1 tabl

Fast and simple qubit-based synchronization for quantum key distribution

We propose Qubit4Sync, a synchronization method for Quantum Key Distribution (QKD) setups, based on the same qubits exchanged during the protocol and without requiring additional hardware other than the one necessary to prepare and measure the quantum states. Our approach introduces a new cross-correlation algorithm achieving the lowest computational complexity, to our knowledge, for high channel losses. We tested the robustness of our scheme in a real QKD implementation

Role of Prion protein-EGFR multimolecular complex during neuronal differentiation of human dental pulp-derived stem cells

Cellular prion protein (PrPC) is expressed in a wide variety of stem cells in which regulates their self-renewal as well as differentiation potential. In this study we investigated the presence of PrPCin human dental pulp-derived stem cells (hDPSCs) and its role in neuronal differentiation process. We show that hDPSCs expresses early PrPCat low concentration and its expression increases after two weeks of treatment with EGF/bFGF. Then, we analyzed the association of PrPCwith gangliosides and EGF receptor (EGF-R) during neuronal differentiation process. PrPCassociates constitutively with GM2 in control hDPSCs and with GD3 only after neuronal differentiation. Otherwise, EGF-R associates weakly in control hDPSCs and more markedly after neuronal differentiation. To analyze the functional role of PrPCin the signal pathway mediated by EGF/EGF-R, a siRNA PrP was applied to ablate PrPCand its function. The treatment with siRNA PrP significantly prevented Akt and ERK1/2 phosphorylation induced by EGF. Moreover, siRNA PrP treatment significantly prevented neuronal-specific antigens expression induced by EGF/bFGF, indicating that cellular prion protein is essential for EGF/bFGF-induced hDPSCs differentiation. These results suggest that PrPCinteract with EGF-R within lipid rafts, playing a role in the multimolecular signaling complexes involved in hDPSCs neuronal differentiation

Large mammal remains from the early pleistocene site of Podere San Lorenzo (Perugia, Central Italy)

Most of the research on fossil mammals from Umbria (central Italy) has been carried out in the southwestern branch of the Tiber basin, due to its paleontological richness. This portion of the basin extends from Perugia to Terni and corresponds to a well-defined half-graben filled with fluvial-lacustrine deposits. The paleontological sample presented here was discovered in a sand and gravel quarry at Podere San Lorenzo, East of the town of Deruta. The stratigraphic succession exposed in the quarry is no longer visible, but we describe here a new outcrop (Palazzone), which is not far from Podere San Lorenzo and shows comparable facies associations. The two successions were deposited in a fluvial environment characterized by an average reduction of the hydrodynamic energy from the bottom upwards. They are referred to the Early Pleistocene Santa Maria di Ciciliano Subsyntheme (Madonna dei Bagni Lithofacies). Large mammal remains are attributed to Mammuthus cf. meridionalis (Nesti, 1825), Stephanorhinus etruscus (Falconer, 1859), Equus stenonis Cocchi, 1867, Leptobos cf. etruscus (Falconer, 1868), ‘Pseudodama’ nestii (Azzaroli, 1947), and Sus strozzii Forsyth Major, 1881. Some hyena coprolites are also reported. The assemblage is typical of the early Late Villafranchian Land Mammal Age and can be referred to the Olivola/Tasso Faunal Units (about 2.0–1.8 Ma). This is in agreement with the alleged age of some other assemblages found in the southwestern branch of the Tiber basin (e.g., Torre Picchio, Villa San Faustino, Colle Sant’Andrea, Pantalla)

Annotating the Inferior Alveolar Canal: the Ultimate Tool

The Inferior Alveolar Nerve (IAN) is of main interest in the maxillofacial field, as an accurate localization of such nerve reduces the risks of injury during surgical procedures. Although recent literature has focused on developing novel deep learning techniques to produce accurate segmentation masks of the canal containing the IAN, there are still strong limitations due to the scarce amount of publicly available 3D maxillofacial datasets. In this paper, we present an improved version of a previously released tool, IACAT (Inferior Alveolar Canal Annotation Tool), today used by medical experts to produce 3D ground truth annotation. In addition, we release a new dataset, ToothFairy, which is part of the homonymous MICCAI2023 challenge hosted by the Grand-Challenge platform, as an extension of the previously released Maxillo dataset, which was the only publicly available. With ToothFairy, the number of annotations has been increased as well as the quality of existing data

On Escherichia coli Resistance to Fluid Shear Stress and Its Significance for Water Disinfection

Alternative water treatment techniques are needed to overcome the limitations of chemical disinfectants. Stemming from recent findings which point to high levels of shear stress induced by flow as the cause of microbial removal in water, we conducted systematic experiments on bacterial solutions in well-controlled hydrodynamic conditions to evaluate the effect of different levels of shear stress on the viability of Escherichia coli. We investigated a wide range of shear stresses (57–4240 Pa) using viscous substrates prepared by mixing a bacterial solution with thickeners (2-hydroxyethyl cellulose and/or guar gum). Substrate samples were tested for up to 60 min in a laminar shear flow at a constant temperature using a rotational rheometer equipped with a cone-plate measuring system so that the whole sampling volume was exposed to the same shear stress. Results show that, contrary to previous studies, high shear stresses (i.e., of order 103 Pa) do not induce inactivation or lysis of E. coli, even for prolonged exposure times. Stemming from our results and a thorough discussion of the literature on E. coli mechanical lysis and modeling cell dynamics, we infer that E. coli can resist high shear forces because of stress relaxation in a wide range of hydrodynamic conditions

Ventricular androgenic-anabolic steroid-related remodeling: an immunohistochemical study

Background: Several fatal cases of bodybuilders, following a myocardial infarction after long exposure to androgenicanabolic steroids (AAS), are reported. In recent years, evidence has emerged of cases of heart failure related to AAS consumption, with no signs of coronary or aorta atherosclerosis. This study aims to further investigate the pathogenesis of the ventricular AAS-related remodeling performing immunohistochemistry (IHC). Method: In order to examine innate immunity activity and myocytes and endothelial cell apoptosis, IHC analyses were performed on heart tissue of two cases of bodybuilders who died after years of supratherapeutic use of metelonone and nandrolone and where no atherosclerosis or thrombosis were found, using the following antibodies: anti-CD68, anti-iNOS, anti-CD163, anti-CD 15, anti-CD8, anti-CD4, anti-HIF1 α, and in situ TUNEL staining. Results: Results confirm the experimental findings of recent research that, in the absence of other pathological factors, if intensive training is combined with AAS abuse, myocytes and endothelial cells undergo apoptotic alterations. The absence of inflammatory reactions and the presence of an increased number of M2 macrophages in the areas of fibrotic remodeling confirm that the fibrotic changes in the heart are apoptosisrelated and not necrosis-related. Conclusions In conclusion, the study indicates that, in very young subjects with chronic hypoxia-related alterations of the heart, signs of a heart failure in the other organs and a history of AAS abuse, death can be ascribed to progressive heart failure due to the direct apoptotic cardiac and endothelial changes produced by AAS

Shaping the Radiation Pattern of Second-Harmonic Generation from AlGaAs Dielectric Nanoantennas

We fabricate AlGaAs nanodisk antennas on a glass substrate and demonstrate experimentally the shaping of radiation patterns and polarization of the second harmonic emission in both forward and backward directions.The paper and the participation of all the authors have been made possible in the framework of the Erasmus Mundus NANOPHI project, contract number 2013 5659/002-001. L.C., C.D.A., and A.L. acknowledge financial support from U.S. Army (“Engineering second order nonlinear effects in optical antennas”) and CARIPLO (“SHAPES, Second-HArmonic Plasmon-Enhanced Sensing”). D.N. acknowledges the support of the Australian Research Council and of the Visiting Program of the University of Brescia

On the Very-Large-Scale Motions in Smooth-Bed Open-Channel Flows

Bimodal distribution of the streamwise velocity pre-multiplied spectra in canonical turbulent flows (pipe, channel and boundary layer flow) is well documented in the literature. The two peaks of this distribution are associated with eddies of a defined size and they are called Large-Scale Motion (LSM) and Very-Large-Scale Motion (VLSM). These eddy structures are very important inasmuch they contain a significant fraction of the total kinetic energy of the flow. The LSMs and VLSMs size is proportional to the characteristic outer length scale of the flow (i.e. the radius, the channel half width and the boundary layer thickness); the former’s length is a few while the latter is some tens of . However, little is known about their size and scaling in open-channel flows. The knowledge of LSMs and VLSMs in open-channel flows (i.e. rivers, tides and marine currents) is important, not only from a theoretical point of view, but most of all for their impact on key transport and mixing processes occurring in many geophysical flows (e.g., sediment dynamics, transport of nutrients, microorganisms movement, etc.). The present study aims to shed light into the dynamics of LSMs and VLSMs in open-channel flow through a laboratory study. The experiments were conducted in a recirculating open-channel flume 50 m long, 0.61 m wide and 1 m deep with a smooth concrete bed. During the experiments, the instantaneous velocity in the streamwise and bed-normal directions was measured with the aid of a 2D Laser Doppler Anemometer (LDA). The conditions in every experiment were that of fully developed smooth turbulent flow. The experiments were designed in order to highlight the influence of various relevant non-dimensional groups (presumably) involved on the LSMs and VLSMs dynamics. The main results are that the evolution of LSMs and VLSMs seems not to be affected by the Von Karman and the Froude Number (in the range of conditions analysed). As suggested also in the literature, the results hint that the non-dimensional parameter that mostly influences these vortices seems to be the aspect ratio. For values of the aspect ratio below 5 (that represent a condition of 3D motion, with the instauration of secondary flows in the flume), the size of these vortices is reduced by more than half with respect to a situation of an aspect ratio greater than 5