On sectional and bisectional curvature of the H

Let M be an H-umbilical submanifold of an almost Hermitian manifold M˜. Some relations expressing the difference of bisectional and of sectional curvatures of M˜ and of M are obtained. The geometric notion of related bases for a pair of oriented planes permits to write the second members in a completely geometrical form. When the planes are not orthogonal, more simple formulas are obtained. The paper ends with a remark, concerning the vector field JH, and some special cases

|\epsilon|-Near-Zero materials in the near-infrared

We consider a mixture of metal coated quantum dots dispersed in a polymer matrix and, using a modified version of the standard Maxwell-Garnett mixing rule, we prove that the mixture parameters (particles radius, quantum dots gain, etc.) can be chosen so that the effective medium permittivity has an absolute value very close to zero in the near-infrared, i.e. |Re(epsilon)|<<1 and |Im (epsilon)|<<1 at the same near-infrared wavelength. Resorting to full-wave simulations, we investigate the accuracy of the effective medium predictions and we relate their discrepancy with rigorous numerical results to the fact that |epsilon|<<1 is a critical requirement. We show that a simple method for reducing this discrepancy, and hence for achieving a prescribed value of |\epsilon|, consists in a subsequent fine-tuning of the nanoparticles volume filling fraction.Comment: 3 pages, 3 figure

Dependence of the irradiation-induced growth kinetics of satellites on the nanoclusters dimension

A paraître dans NIM B, présenté par G. Rizza (LSI)International audienceIrradiation with MeV gold ions of embedded Au nanoclusters in silica matrix results in the formation of a ring of satellites in its surrounding. We show that changing the initial nanoclusters size modifies both the size and the density of the satellites, and therefore alters their kinetic growth. Finally we discuss the limitation of the ion implantation technique to form a model system to study the satellites kinetic growth and we propose a new approach based on the chemical synthesis of metallic nanoparticles to obtain the proper configuration

Optimisation of the Detection Sensitivity of Plasmonic Nanoantenna Based Sensors for Mid-infrared Spectroscopy

AbstractIn this paper we report on the optimisation of the optical characteristics of 2D-arrays of plasmonic gold nanoantennas (NA) that can be used as high sensitivity mid-infrared spectroscopic sensor for the detection of chemical/biological substances by using the Surface Enhanced Infrared Absorption (SEIRA) technique. This approach allows to detect the presence of a substance adsorbed on the NA by measuring its optical absorption under the conditions for which the maximum of the reflectivity response of the 2D-array occurs at the same wavelength of the substance maximum absorption peak. In particular, by acting on the 2D-array periodicity, NA shape, size and thickness, numerical simulations of the 2D-array detection response, based on Finite Element Method (FEM), demonstrate that is possible to obtain an increase in the detection sensitivity of more than three orders of magnitude with respect to that one achievable if the same substance is deposited on an unstructured planar metal surface, independently from the wavelength at which the substance absorption occurs. Moreover, we present the results of an analysis of the dependence of the 2D-array maximum reflectivity and peak wavelength on the geometrical parameters characterising the NA and the 2D-array

Diabetes influences cancer risk in patients with increased carotid atherosclerosis burden

Background and aims: Atherosclerosis and cancer share several risk factors suggesting that at least in part their pathogenesis is sustained by common mechanisms. To investigate this relation we followed a group of subjects with carotid atherosclerosis at baseline up for malignancy development.Methods and results: we carried out an observational study exploring cancer incidence (study endpoint) in subjects with known carotid atherosclerosis at baseline (n = 766) without previous cancer or carotid vascular procedures. During the follow-up (160 +/- 111 weeks) 24 cancer occurred, corresponding to an overall annual incidence rate of 0.11%. 10 diagnosis of cancer occurred in individuals with a carotid stenosis &gt;50% (n = 90) whereas 14 in patients with a carotid stenosis &lt;50% patients (n = 676) (p &lt; 0.001). Respect to patients without cancer, diabetes was markedly more common in subjects with cancer diagnosis during the FU (37.3%vs75.0%, p &lt; 0.001). After controlling for classic risk factors, carotid stenosis &gt;50% (HR = 2.831, 95%CI = 1.034-5.714; p = 0.036) and diabetes (HR = 4.831, 95%CI = 1.506-15.501; p = 0.008) remained significantly associated with cancer diagnosis.Conclusions: to our knowledge this is the first study reporting a significant risk of cancer development in subjects with diabetes and high risk of cerebrovascular events, highlighting the need of a carefully clinical screening for cancer in diabetic patients with overt carotid atherosclerosis. (C) 2019 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved