This paper addresses the problem of critical operations in Degraded Visual Environment (DVE). DVE usually refer when the perception of a pilot is degraded by environmental factors, including the presence of obscurants from bad weather (e.g. fog, rain, snow) or accidental events (e.g. brownout, whiteout, smoke). Critical operations in DVE are a growing field of research as it is a cause of numerous fatal accidents for operational forces. Due to the lack of efficient sources and sensors in the Terahertz (THz) region, this domain has remained an unexplored part of the electromagnetic spectrum. Recently, the potential use of sub-Terahertz waves has been proposed to see through dense clouds of obscurants (e.g. sand, smoke) in DVE conditions. In order to conduct a performance evaluation of sub-Terahertz systems, several sub-terahertz systems (e.g. bolometer- array cameras, liquid helium cooled bolometers) were operated in artificial controlled DVE conditions at ONERA facilities. The purpose of this paper is to report field experiments results in controlled DVE conditions: attenuation measurements from 400 GHz to 700 GHz with a performance evaluation of different sub-Terahertz systems are presented.

Graphene, known as one carbon layer material, holds attractive properties due to its hexagonal lattice, also called honeycomb structure. Since the seminal work on mechanically exfoliated few layer graphene, more growth processes were explored: Chemical Vapor Deposition (CVD) on metals or on silicon carbide (SiC); chemical reduction of graphene oxides and SiC sublimation. In contrast to the other graphene growth techniques, thermal decomposition of SiC provides wafer-scale homogeneous graphene spontaneously forming on semi-insulating substrate. SiC sublimation is the most promising option to achieve the transfer free and wafer-scale graphene. Furthermore, graphene/SiC is compatible with lithography techniques for further applications; thereby epitaxial graphene on SiC is a potential candidate for nanoelectronics. Until now, monolayer graphene growth by SiC sublimation at a pressure closed to the atmospheric pressure (around 900 mbar) and at high temperature (>1650°C) is well known . However, to obtain films with different and controlled characteristics such as the number of graphene layers or the type of doping by controlling the growth parameters remains challenging. We will present the initial growth stages from buffer layer to monolayer graphene on SiC (0001) as a function of the temperature at low pressure (10 mbar). A reproducible synthesis of low p-type doped monolayer graphene was optimized (few 10^11 cm-2). The p-type doping are obtained here on the bare samples without any post-growth process such as lithography. A prototypal HTA-100 furnace developed by Annealsys Company has allowed the synthesis of these original samples. All the samples were characterized by Raman spectroscopy and Atomic Force Microscopy (AFM). In addition, transport measurements (at room temperature and low temperature with high magnetic field) were carried out in the case of continuous monolayer graphene films showing especially characteristics of Quantum Hall Effect.

An overview of main results concerning THz detection related to plasma nonlinearities in nanometer field effect transistors is presented. In particular the physical limits of the responsivity, speed and the dynamic range of these detectors are discussed. As a conclusion, we will present applications of the FET THz detectors for construction of focal plane arrays. These arrays, together with in purpose developed diffractive 3D printed optics lead to construction of the demonstrators of the fast postal security imagers and nondestructive industrial quality control systems. We will show also first results of FET based imaging that uses for contrast not only usual THz radiation amplitude, but also the degree of its circular polarization. Sub-THz high resolution gas spectroscopy is shown to be a powerful means to diagnose various diseases via exhaled breath analysis.

Patients with vascular parkinsonism have higher cognitive decline and more basal ganglia lesions. We aimed to evaluate the relationship of cognitive impairment with functional connectivity between the basal ganglia and cingulate cortex in vascular parkinsonism.;Thirty patients (8 with vascular parkinsonism and 22 with Parkinson disease) and 23 controls were enrolled. The Mattis Dementia Rating Scale and the Stroop Task were used to assess cognitive decline. MR imaging examinations included T1-MPRAGE, FLAIR, and resting-state fMRI sequences. MPRAGE was segmented to obtain basal ganglia and cingulate cortex volumes. FLAIR was segmented to obtain white matter hyperintensity lesion volume. Resting-state fMRI sequences were used to compare basal ganglia functional connectivity with the cingulate cortex between patients and controls.;Patients with vascular parkinsonism exhibited impaired attention, resistance to interference, and inhibitory control and an increased number of errors on the Stroop Task. They also had higher caudate nucleus and white matter hyperintensity lesion volumes, which were positively correlated (ρ = 0.75, P < .0001). Caudate nucleus functional connectivity with the perigenual anterior cingulate cortex was increased in patients with vascular parkinsonism compared with controls and patients with Parkinson disease, and it was positively correlated with the caudate nucleus volume (ρ = 0.44, P = .016). Caudate nucleus functional connectivity with the posterior cingulate cortex was decreased in patients with vascular parkinsonism compared with controls and negatively correlated with the number of errors on the Stroop test (ρ = -0.51, P = .0003).;In patients with vascular parkinsonism, cognitive decline could be related to changes of caudate nucleus functional connectivity with the cingulate cortex at resting-state, which may be induced by ischemia-related remodelling.

Pancreatic β-cells modulate insulin secretion through rapid sensing of blood glucose and integration of gut-derived signals. Increased insulin demand during pregnancy and obesity alters islet function and mass and leads to gestational diabetes mellitus and type 2 diabetes in predisposed individuals. However, it is unclear how blood-borne factors dynamically access the islets of Langerhans. Thus, understanding the changes in circulating molecule distribution that accompany compensatory β-cell expansion may be key to developing novel antidiabetic therapies. Here, using two-photon microscopy in vivo in mice, we demonstrate that islets are almost instantly exposed to peaks of circulating molecules, which rapidly pervade the tissue before clearance. In addition, both gestation and short-term high-fat-diet feeding decrease molecule extravasation and uptake rates in vivo in islets, independently of β-cell expansion or islet blood flow velocity. Together, these data support a role for islet vascular permeability in shaping β-cell adaptive responses to metabolic demand by modulating the access and sensing of circulating molecules.

Characterization of normal age-related changes in resting state brain networks associated with working memory performance is a major prerequisite for studying neurodegenerative diseases. The aim of this study was to investigate the relationship between performing a working memory task (under MRI) and resting-state brain networks in a large cohort of healthy elderly subjects (n=337). Functional connectivity and interactions between networks were assessed within the default mode (DMN), salience (SN), and right and left central executive (CEN) networks in two groups of subjects classed by their performance (low and high). The low performance group showed lower functional connectivity in both the DMN and SN, and higher functional connectivity in the right and left CEN compared to the high performance group. Overall the functional connectivity within the DMN and the CEN were correlated. The lower functional connectivity within the DMN and SN in the low performance group is suggestive of altered attentional and memory processes and/or altered motivation. The higher functional connectivity within the CEN could be related to compensatory mechanisms, without which the subjects would have even lower performances. The correlation between the DMN and CEN suggests a modulation between the lower functional connectivity within the DMN and the higher functional connectivity within the CEN when performance is reduced. Finally, this study suggests that performance modifications in healthy elderly subjects are associated with reorganization of functional connectivity within the DMN, SN, and CEN.