Noise characterization of an Optical Frequency Comb using Offline Cross-Correlation

Using an offline cross-correlation technique, we have analyzed the noise behavior of a new type of optical frequency comb (OFC), which is carrier envelope offset (CEO) free by configuration, due to difference frequency generation. In order to evaluate the instrument's ultimate noise floor, the phase and amplitude noise of a stabilized OFC are measured simultaneously using two analog-to-digital converters. Carrier recovery and phase detection are done by post-processing, eliminating the need for external phase-locked loops and complex calibration techniques. In order to adapt the measurement noise floor and the number of averages used in cross correlation, an adaptive frequency resolution for noise measurement is applied. Phase noise results are in excellent agreement with measurements of the fluctuations of the repetition frequency of the OFC obtained from optical signal

Pluralité des références spatiales et sociales pour les acteurs d'un contrat de rivière

National audienceRiver contracts lead smoothly stakeholders in a watershed to share points of view and enhance the emergence of collective and coherent projects.With a methodology based on collective decision support experirnents, we have interviewed a set of stakeholders of Orb Valley River Contract.This shows a variability of relevant spaces within our stakeholders sarnple, according to their physical location within or outside the basin, as well as according to their domain of action. These differences are not only based on zoning but also on the relevance of the basin as the cornmon space.As from the social point of view, embedded actors are perceived more through the local conséquences of their actions than through actual interactions. This enhance issues of coherence and conflicts. Orb valley institution seems the main coordination place.Les contrats de rivière amènent d'une manière assez souple les acteurs concernés par la gestion de l'eau sur un bassin versant à partager des points de vue et favorisent l'émergence de projets communs et cohérents. A partir d'expériences en aide à la décision collective, nous avons mené un travail d'enquêtes auprès d'acteurs du Contrat de Rivière de l'Orb. Il en ressort une variabilité des espaces de référence parmi les acteurs interviewés, selon leur localisation physique à l'intérieur ou à l'extérieur du bassin versant, et selon le rayonnement de leur activité (local ou global). Cette variabilité relève non seulement du découpage du même espace d'ensemble, le bassin versant, mais aussi de sa pertinence. Les acteurs, quant à eux, sont plus perçus à travers les conséquences locales de leurs actions que par de réelles interactions, d'où des problèmes de cohérence et de conflits perçus entre ces actions. Le syndicat mixte de la vallée de l'Orb semble le principal lieu de coordination

Aromatic oligoamide foldamers as versatile scaffolds for induced circularly polarized luminescence at adjustable wavelengths

International audienceQuinoline oligoamide foldamers appended with non-chiral fluorophores and derivatized with a camphanyl chiral inducer display strong chiroptical properties at tunable wavelengths as proved by CD and CPL spectroscopies. Induced CPL activity with high luminescence dissymmetry factors was observed in the visible range at wavelengths specific to the fluorophores

Org. Chem. Front.

The synthesis and characterization of an original π-extended cationic azahelicene is reported. The phenanthrene-fused aza[7]helicene derivative encompasses a total of ten aromatic fused rings leading to a dissymmetric yet helically folded structure, as revealed by NMR and X-ray diffraction analyses. The polyaromatic and cationic nature of the new azahelicenium makes it soluble in both organic and aqueous media, which allowed photophysical studies in solvents of different polarities. The extended chromophoric species demonstrates a broad absorption over the whole visible range and orange-red fluorescence emission. Chiral resolution of the racemate was performed subsequently, affording two optically pure and configurationally stable azahelicenium enantiomers. Multi-band circular dichroism and long-wavelength circularly polarized emission were observed, associated with remarkable absorption and luminescence dissymmetry factors, both in organic and aqueous media.Program Initiative d’Excellenc

Smart Phone, Smart Science: How the Use of Smartphones Can Revolutionize Research in Cognitive Science

Investigating human cognitive faculties such as language, attention, and memory most often relies on testing small and homogeneous groups of volunteers coming to research facilities where they are asked to participate in behavioral experiments. We show that this limitation and sampling bias can be overcome by using smartphone technology to collect data in cognitive science experiments from thousands of subjects from all over the world. This mass coordinated use of smartphones creates a novel and powerful scientific “instrument” that yields the data necessary to test universal theories of cognition. This increase in power represents a potential revolution in cognitive science

Prime Focus Spectrograph (PFS) for the Subaru Telescope: Overview, recent progress, and future perspectives

PFS (Prime Focus Spectrograph), a next generation facility instrument on the 8.2-meter Subaru Telescope, is a very wide-field, massively multiplexed, optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed over the 1.3 deg field of view. The spectrograph has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously observe spectra from 380nm to 1260nm in one exposure at a resolution of ~1.6-2.7A. An international collaboration is developing this instrument under the initiative of Kavli IPMU. The project is now going into the construction phase aiming at undertaking system integration in 2017-2018 and subsequently carrying out engineering operations in 2018-2019. This article gives an overview of the instrument, current project status and future paths forward.Comment: 17 pages, 10 figures. Proceeding of SPIE Astronomical Telescopes and Instrumentation 201

ALK germline mutations in patients with neuroblastoma: a rare and weakly penetrant syndrome

Neuroblastic tumours may occur in a predisposition context. Two main genes are involved: PHOX2B, observed in familial cases and frequently associated with other neurocristopathies (Ondine's and Hirschsprung's disease); and ALK, mostly in familial tumours. We have assessed the frequency of mutations of these two genes in patients with a presumable higher risk of predisposition. We sequenced both genes in 26 perinatal cases (prebirth and o1 month of age, among which 10 were multifocal), 16 multifocal postnatal (41 month) cases, 3 pairs of affected relatives and 8 patients with multiple malignancies. The whole coding sequences of the two genes were analysed in tumour and/or constitutional DNAs. We found three ALK germline mutations, all in a context of multifocal tumours. Two mutations (T1151R and R1192P) were inherited and shared by several unaffected patients, thus illustrating an incomplete penetrance. Younger age at tumour onset did not seem to offer a relevant selection criterion for ALK analyses. Conversely, multifocal tumours might be the most to benefit from the genetic screening. Finally, no PHOX2B germline mutation was found in this series. In conclusion, ALK deleterious mutations are rare events in patients with a high probability of predisposition. Other predisposing genes remain to be discovered

Progress with the Prime Focus Spectrograph for the Subaru Telescope: a massively multiplexed optical and near-infrared fiber spectrograph

The Prime Focus Spectrograph (PFS) is an optical/near-infrared multi-fiber spectrograph with 2394 science fibers, which are distributed in 1.3 degree diameter field of view at Subaru 8.2-meter telescope. The simultaneous wide wavelength coverage from 0.38 um to 1.26 um, with the resolving power of 3000, strengthens its ability to target three main survey programs: cosmology, Galactic archaeology, and galaxy/AGN evolution. A medium resolution mode with resolving power of 5000 for 0.71 um to 0.89 um also will be available by simply exchanging dispersers. PFS takes the role for the spectroscopic part of the Subaru Measurement of Images and Redshifts project, while Hyper Suprime-Cam works on the imaging part. To transform the telescope plus WFC focal ratio, a 3-mm thick broad-band coated glass-molded microlens is glued to each fiber tip. A higher transmission fiber is selected for the longest part of cable system, while one with a better FRD performance is selected for the fiber-positioner and fiber-slit components, given the more frequent fiber movements and tightly curved structure. Each Fiber positioner consists of two stages of piezo-electric rotary motors. Its engineering model has been produced and tested. Fiber positioning will be performed iteratively by taking an image of artificially back-illuminated fibers with the Metrology camera located in the Cassegrain container. The camera is carefully designed so that fiber position measurements are unaffected by small amounts of high special-frequency inaccuracies in WFC lens surface shapes. Target light carried through the fiber system reaches one of four identical fast-Schmidt spectrograph modules, each with three arms. Prototype VPH gratings have been optically tested. CCD production is complete, with standard fully-depleted CCDs for red arms and more-challenging thinner fully-depleted CCDs with blue-optimized coating for blue arms.Comment: 14 pages, 12 figures, submitted to "Ground-based and Airborne Instrumentation for Astronomy V, Suzanne K. Ramsay, Ian S. McLean, Hideki Takami, Editors, Proc. SPIE 9147 (2014)