We present here an analysis of the sensitivity of a time-domain atomic interferometer to the phase noise of the lasers used to manipulate the atomic wave packets. The sensitivity function is ...calculated in the case of a three-pulse Mach-Zehnder interferometer, which is the configuration of the two inertial sensors we are building at the Laboratoire National de Metrologie et d'Essais-Systeme de References Temps-Espace. We successfully compare this calculation to experimental measurements. The sensitivity of the interferometer is limited by the phase noise of the lasers as well as by residual vibrations. We evaluate the performance that could be obtained with state-of-the-art quartz oscillators, as well as the impact of the residual phase noise of the phase-locked loop. Requirements on the level of vibrations are derived from the same formalism.
We have developed an atom interferometer providing a full inertial base. This device uses two counterpropagating cold-atom clouds that are launched in strongly curved parabolic trajectories. Three ...single Raman beam pairs, pulsed in time, are successively applied in three orthogonal directions leading to the measurement of the three axis of rotation and acceleration. In this purpose, we introduce a new atom gyroscope using a butterfly geometry. We discuss the present sensitivity and the possible improvements.
A new ultralow‐temperature setup dedicated to soft X‐ray absorption spectroscopy and X‐ray magnetic circular dichroism (XMCD) experiments is described. Two experiments, performed on the DEIMOS ...beamline (SOLEIL synchrotron), demonstrate the outstanding performance of this new platform in terms of the lowest achievable temperature under X‐ray irradiation (T = 220 mK), the precision in controlling the temperature during measurements as well as the speed of the cooling‐down and warming‐up procedures. Moreover, owing to the new design of the setup, the eddy‐current power is strongly reduced, allowing fast scanning of the magnetic field in XMCD experiments; these performances lead to a powerful device for X‐ray spectroscopies on synchrotron‐radiation beamlines facilities.
A new ultralow‐temperature setup dedicated to soft X‐ray absorption spectroscopy and X‐ray magnetic circular dichroism experiments is described. Two experiments, performed on the DEIMOS beamline (SOLEIL synchrotron), demonstrate the outstanding performances of this new platform, particularly with regard to the lowest achievable temperature under X‐ray irradiation (T = 220 mK).
Invasive species represent a threat to aquatic ecosystems globally; however, impacts can be heterogenous across systems. Documented impacts of invasive zebra mussels (
Dreissena polymorpha
) and ...spiny water fleas (
Bythotrephes cederströmii
; hereafter
Bythotrephes
) on native fishes are variable and context dependent across locations and time periods. Here, we use a hierarchical Bayesian analysis of a 35-year dataset on two fish species from 9 lakes to demonstrate that early life growth of ecologically important fishes are influenced by these aquatic invasive species. Walleye (
Sander vitreus
) in their first year of life grew more slowly in the presence of either invader after correcting for temperature (measured by degree days), and were on average 12 or 14% smaller at the end of their first summer following invasion by
Bythotrephes
or zebra mussels, respectively. Yellow perch (
Perca flavescens
) growth was less affected by invasion. Yellow perch on average grew more slowly in their first year of life following invasion by zebra mussels, although this effect was not statistically distinguishable from zero. Early life growth of both walleye and yellow perch was less tightly coupled to degree days in invaded systems, as demonstrated by increased variance surrounding the degree day-length relationship. Smaller first-year size is related to walleye survival and recruitment to later life stages and has important implications for lake food webs and fisheries management. Future research quantifying effects of zebra mussels and
Bythotrephes
on other population-level processes and across a wider gradient of lake types is needed to understand the mechanisms driving observed changes in walleye growth.
Toxic cyanobacterial blooms, often containing multiple toxins, are a serious public health issue. However, there are no known models that predict a cyanotoxin mixture (anatoxin-a, microcystin, ...saxitoxin). This paper presents two cyanotoxin mixture models (MIX) and compares them to two microcystin (MC) models from data collected in 2016–2017 from three recurring cyanobacterial bloom locations in Kabetogama Lake, Voyageurs National Park (Minnesota, USA). Models include those using near-real-time environmental variables (readily available) and those using additional comprehensive variables (based on laboratory analyses). Comprehensive models (R2 = 0.87 MC; R2 = 0.86 MIX) explained more variability than the environmental models (R2 = 0.58 MC; R2 = 0.57 MIX). Although neither MIX model was a better fit than the MC models, the MIX models produced no false negatives in the calibration dataset, indicating that all observations above regulatory guidelines were simulated by the MIX models. This is the first known use of Virtual Beach software for a cyanotoxin mixture model, and the methods used in this paper may be applicable to other lakes or beaches.
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•Cyanotoxin mixture models produced no false negatives.•Cyanotoxin mixture models predicted all observations above regulatory guidelines.•The variance explained by cyanotoxin mixture models was similar to microcystin models.•Lake level was a potential environmental trigger of toxin production for all models.•Lagged toxin genes counts by qPCR correlated with toxins in comprehensive models.