100 research outputs found
Evidence for long-term change in length, mass and migration phenology of anadromous spawners in French Atlantic salmon Salmo salar
Peer reviewed paper.
This is the peer reviewed version of the following article: Bal, G., Montorio, L., Rivot, E., Prevost, E., Bagliniere, J.-L., & Nevoux, M. (2017). Evidence for long-term change in length, mass and migration phenology of anadromous spawners in French Atlantic salmon Salmo salar. Journal of Fish Biology, 90(6), 2375â2393. https://doi.org/10.1111/jfb.13314 , which has been published in final form at https://doi.org/10.1111/jfb.13314. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.This study provides new data on Atlantic salmon Salmo salar lifeâhistory traits across France. Using a longâterm recreational angling database (1987â2013) covering 34 rivers in three regions (genetic units), a decline in individual length, mass and a delayed adult return to French rivers was reported. Temporal similarities in trait variations between regions may be attributed to common change in environmental conditions at sea. The relative rate of change in phenotypic traits was more pronounced in early maturing fish [1 seaâwinter (1SW) fish] than in late maturing fish (2SW fish). Such contrasted response within populations highlights the need to account for the diversity in life histories when exploring mechanisms of phenotypic change in S. salar. Such detailed lifeâhistory data on returning S. salar have not previously been reported from France. This study on French populations also contributes to reducing the gap in knowledge by providing further empirical evidence of a global pattern in S. salar across its distribution range. Results are consistent with the hypothesis that the observed changes in lifeâhistory traits are primarily associated with environmental changes in the North Atlantic Ocean. They also emphasize the presence of less important, but still significant contrasts between region and life history
Generation of a flat-top laser beam for gravitational wave detectors by means of a nonspherical Fabry-Perot resonator
We have tested a new kind of Fabry-Perot long-baseline optical resonator proposed to reduce the thermal noise sensitivity of gravitational wave interferometric detectors--the "mesa beam" cavity--whose flat top beam shape is achieved by means of an aspherical end mirror. We present the fundamental mode intensity pattern for this cavity and its distortion due to surface imperfections and tilt misalignments, and contrast the higher order mode patterns to the Gauss-Laguerre modes of a spherical mirror cavity. We discuss the effects of mirror tilts on cavity alignment and locking and present measurements of the mesa beam tilt sensitivity
Optical coherence tomography angiography findings in Huntingtonâs disease
Objectives: To evaluate the retinal and choriocapillaris vascular networks in macular region and the central choroidal thickness (CCT) in patients affected by Huntington disease (HD), using optical coherence tomography angiography (OCTA) and enhanced depth imaging spectral-domain OCT (EDI SD-OCT). Methods: We assessed the vessel density (VD) in superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) using OCTA, while CCT was measured by EDI SD-OCT. Results: Sixteen HD patients (32 eyes) and thirteen healthy controls (26 eyes) were enrolled in this prospective study. No significant difference in retinal and choriocapillaris VD was found between HD patients and controls while CCT turned to be thinner in patients respect to controls. There were no significant relationships between OCTA findings and neurological parameters. Conclusion: The changes in choroidal structure provide useful information regarding the possible neurovascular involvement in the physiopathology of HD. Choroidal vascular network could be a useful parameter to evaluate the vascular impairment that occurs in this neurodegenerative disease
I.B.S. coatings on large substrates: Towards an improvement of the mechanical and optical performances
présenté par A. RemillieuxLarge mirrors (350 mm), having extremely low optical loss (absorption, scattering, wavefront) were coated for the VIRGO interferometer. The new mirror generation needs better wavefront and lower mechanical loss. The first results are discussed
Original optical metrologies of large components
présentée par A. RemillieuxThe coating deposition on large optical components (diameter 350 mm) has required the development of new metrology tools at 1064 nm. To give realistic values of the optical performances, the whole surface of the component needs to be scanned. Our scatterometer (commercial system) has been upgraded to support large and heavy samples. The other metrology tools are prototypes we have developed. We can mention the absorption (photothermal effect) and birefringence bench, a control interferometer equipped with an original stitching option, the optical profilometer (RMS roughness and small defect measurements). A detailed description of these metrology benches will be exposed. Their sensitivity, accuracy and capability to map the optical properties of substrates or mirrors will be discussed. We will describe the recent developments: the stitching option adapted to the Micromap profilometer to measure the RMS roughness on larger area (exploration of a new spatial frequency domain), the accurate bulk absorption calibration
GRANIT project: a trap for gravitational quantum states of UCN
Previous studies of gravitationally bound states of ultracold neutrons showed
the quantization of energy levels, and confirmed quantum mechanical predictions
for the average size of the two lowest energy states wave functions.
Improvements in position-like measurements can increase the accuracy by an
order of magnitude only. We therefore develop another approach, consisting in
accurate measurements of the energy levels. The GRANIT experiment is devoted to
the study of resonant transitions between quantum states induced by an
oscillating perturbation.
According to Heisenberg's uncertainty relations, the accuracy of measurement
of the energy levels is limited by the time available to perform the
transitions. Thus, trapping quantum states will be necessary, and each source
of losses has to be controlled in order to maximize the lifetime of the states.
We discuss the general principles of transitions between quantum states, and
consider the main systematical losses of neutrons in a trap.Comment: presented in ISINN 15 seminar, Dubn
Measurements of a low temperature mechanical dissipation peak in a single layer of Ta2O5 doped with TiO2
Thermal noise arising from mechanical dissipation in oxide coatings is a
major limitation to many precision measurement systems, including optical
frequency standards, high resolution optical spectroscopy and interferometric
gravity wave detectors. Presented here are measurements of dissipation as a
function of temperature between 7 K and 290 K in ion-beam sputtered Ta2O5 doped
with TiO2, showing a loss peak at 20 K. Analysis of the peak provides the first
evidence of the source of dissipation in doped Ta2O5 coatings, leading to
possibilities for the reduction of thermal noise effects
Search for non-Gaussian events in the data of the VIRGO E4 engineering run
International audienc
- âŠ