Search results for "Device"
showing 10 items of 1286 documents
Control of signal coherence in parametric frequency mixing with incoherent pumps: Narrowband mid-infrared light generation by downconversion of broad…
2012
International audience; We study, with numerical simulations using the generalized nonlinear envelope equation, the processes of optical parametric and difference- and sum-frequency generation (SFG) with incoherent pumps in optical media with both quadratic and third-order nonlinearity, such as periodically poled lithium niobate. With ultrabroadband amplified spontaneous emission pumps or continua (spectral widths > 10 THz), group-velocity matching of a near-IR pump and a short-wavelength mid-IR (MIR) idler in optical parametric generation may lead to more than 15-fold relative spectral narrowing of the generated MIR signal. Moreover, the SFG process may also lead to 6-fold signal coherence…
Optical gain, spontaneous and stimulated emission of surface plasmon polaritons in confined plasmonic waveguide
2010
International audience; We develop a theoretical model to compute the local density of states in a confined plasmonic waveguide. Based on this model, we derive a simple formula with a clear physical interpretation for the lifetime modification of emitters embedded in the waveguide. The gain distribution within the active medium is then computed following the formalism developed in a recent work [Phys. Rev. B 78, 161401 (2008)], by taking rigorously into account the pump irradiance and emitters lifetime modifications in the system. We finally apply this formalism to describe gain–assisted propagation in a dielectric–loaded surface plasmon polariton waveguide.
Lateral Fusion of Chemical Vapor Deposited N = 5 Armchair Graphene Nanoribbons
2017
Bottom-up synthesis of low-bandgap graphene nanoribbons with various widths is of great importance for their applications in electronic and optoelectronic devices. Here we demonstrate a synthesis of N = 5 armchair graphene nanoribbons (5-AGNRs) and their lateral fusion into wider AGNRs, by a chemical vapor deposition method. The efficient formation of 10- and 15- AGNRs is revealed by a combination of different spectroscopic methods, including Raman and UV−visnear-infrared spectroscopy as well as by scanning tunneling microscopy. The degree of fusion and thus the optical and electronic properties of the resulting GNRs can be controlled by the annealing temperature, providing GNR films with o…
Lipid-Filled semipermeable membrane devices and mussels as samplers of organochlorine compounds in lake water.
1995
Semipermeable membrane sampling devices (SPMDs) and caged lake mussels (Anodonta piscinalis) were simultaneously deployed at four lake watercourse sites in Central Finland four weeks in August 1992. This study was part of the regular annual monitoring of the organochlorine compounds (OCC) in pulp-mill recipient watercourses of Finland with bivalves. Chlorohydrocarbons (CHCs), chlorophenol compounds (PCPs), chloroanisoles (PCAs) and chloroveratroles (PCVs) were analyzed from lipid extract of mussels and from the synthetic triolein lipid of the SPMDs. Hexane-diethyl ether (9:1, v/v) dialysis using polyethylene membrane was applied in dean up of the SPMD lipids and, for comparison, to six sets…
Early results of a low-profile stent-graft for thoracic endovascular aortic repair
2020
Purpose To assess outcomes of a low-profile thoracic stent-graft in the treatment of thoracic aortic pathologies. Methods A retrospective analysis of all consecutive patients with aortic thoracic pathologies treated with the RelayPro device in two university hospitals between October 2018 and July 2019. Results 23 patients (65% men; mean age 63.4 ± 15 years) were treated. Pathologies included aortic dissections (n = 10), 5 residual type A (22%) and 5 type B (22%), 6 degenerative aortic aneurysms (26%), 4 penetrating aortic ulcers (17%), and aortic erosion, intramural hematoma and aortic rupture (n = 1 and 4% in each case). Two cases (9%) were emergent and two urgent. Proximal landing was a…
mHealth for the Monitoring of Brace Compliance and Wellbeing in Adolescents with Idiopathic Scoliosis: Study Protocol for a Feasibility Study
2021
Escoliosis idiopática del adolescente; Aplicación móvil; Eficacia del tratamiento Escoliosi idiopàtica de l'adolescent; Aplicació mòbil; Eficàcia del tractament Adolescent idiopathic scoliosis; Mobile application; Treatment effectiveness Attempts to optimize monitoring of brace adherence prescribed to adolescents with idiopathic scoliosis (IS) have generally relied on sensors. Sensors, however, are intrusive and do not allow the assessment of psychological and physical consequences of brace use that might underlie poor adherence. Mobile applications have emerged as alternatives to monitor brace compliance. However, the feasibility and utility of these app-based systems to assess key psychol…
Uptake mechanism of ApoE-modified nanoparticles on brain capillary endothelial cells as a blood-brain barrier model.
2012
Background The blood-brain barrier (BBB) represents an insurmountable obstacle for most drugs thus obstructing an effective treatment of many brain diseases. One solution for overcoming this barrier is a transport by binding of these drugs to surface-modified nanoparticles. Especially apolipoprotein E (ApoE) appears to play a major role in the nanoparticle-mediated drug transport across the BBB. However, at present the underlying mechanism is incompletely understood. Methodology/Principal Findings In this study, the uptake of the ApoE-modified nanoparticles into the brain capillary endothelial cells was investigated to differentiate between active and passive uptake mechanism by flow cytome…
Remote sensing of solar-induced chlorophyll fluorescence: Review of methods and applications
2009
Interest in remote sensing (RS) of solar-induced chlorophyll fluorescence (F) by terrestrial vegetation is motivated by the link of F to photosynthetic efficiency which could be exploited for large scale monitoring of plant status and functioning. Today, passive RS of F is feasible with different prototypes and commercial ground-based, airborne, and even spaceborne instruments under certain conditions. This interest is generating an increasing number of research projects linking F and RS, such as the development of new F remote retrieval techniques, the understanding of the link between the F signal and vegetation physiology and the feasibility of a satellite mission specifically designed f…
A Hardware and Secure Pseudorandom Generator for Constrained Devices
2018
Hardware security for an Internet of Things or cyber physical system drives the need for ubiquitous cryptography to different sensing infrastructures in these fields. In particular, generating strong cryptographic keys on such resource-constrained device depends on a lightweight and cryptographically secure random number generator. In this research work, we have introduced a new hardware chaos-based pseudorandom number generator, which is mainly based on the deletion of an Hamilton cycle within the $N$ -cube (or on the vectorial negation), plus one single permutation. We have rigorously proven the chaotic behavior and cryptographically secure property of the whole proposal: the mid-term eff…
Influence of Active Device Nonlinearities on the Determination of Adler's Injection.Locking Q-Factor
2011
The problem of the correct evaluation of Q-factor appearing in Adler's equation for injection-locking is addressed. Investigation has shown that recent results presented in the literature, while extending applicability of the original method, do not completely account for nonlinear effects occurring when two-port active devices are involved. To overcome such limitation, use can be made of a newly developed theory in the dynamical complex envelope domain, capable of providing first-approximation exact dynamical models of driven quasi-sinusoidal oscillators. Some preliminary results are presented here concerning a class of injection-locked oscillators with single-loop feedback type configurat…