170 research outputs found
Real Time Full-Color Imaging in a Meta-Optical Fiber Endoscope
Endoscopes are an important component for the development of minimally
invasive surgeries. Their size is one of the most critical aspects, because
smaller and less rigid endoscopes enable higher agility, facilitate larger
accessibility, and induce less stress on the surrounding tissue. In all
existing endoscopes, the size of the optics poses a major limitation in
miniaturization of the imaging system. Not only is making small optics
difficult, but their performance also degrades with downscaling. Meta-optics
have recently emerged as a promising candidate to drastically miniaturize
optics while achieving similar functionalities with significantly reduced size.
Herein, we report an inverse-designed meta-optic, which combined with a
coherent fiber bundle enables a 33% reduction in the rigid tip length over
traditional gradient-index (GRIN) lenses. We use the meta-optic fiber endoscope
(MOFIE) to demonstrate real-time video capture in full visible color, the
spatial resolution of which is primarily limited by the fiber itself. Our work
shows the potential of meta-optics for integration and miniaturization of
biomedical devices towards minimally invasive surgery
Non-volatile Phase-only Transmissive Spatial Light Modulators
Free-space modulation of light is crucial for many applications, from light
detection and ranging to virtual or augmented reality. Traditional means of
modulating free-space light involves spatial light modulators based on liquid
crystals and microelectromechanical systems, which are bulky, have large pixel
areas (~10 micron x 10 micron), and require high driving voltage. Recent
progress in meta-optics has shown promise to circumvent some of the
limitations. By integrating active materials with sub-wavelength pixels in a
meta-optic, the power consumption can be dramatically reduced while achieving a
faster speed. However, these reconfiguration methods are volatile and hence
require constant application of control signals, leading to phase jitter and
crosstalk. Additionally, to control a large number of pixels, it is essential
to implement a memory within each pixel to have a tractable number of control
signals. Here, we develop a device with nonvolatile, electrically programmable,
phase-only modulation of free-space infrared radiation in transmission using
the low-loss phase-change material (PCM) Sb2Se3. By coupling an ultra-thin PCM
layer to a high quality (Q)-factor (Q~406) diatomic metasurface, we demonstrate
a phase-only modulation of ~0.25pi (~0.2pi) in simulation (experiment), ten
times larger than a bare PCM layer of the same thickness. The device shows
excellent endurance over 1,000 switching cycles. We then advance the device
geometry, to enable independent control of 17 meta-molecules, achieving ten
deterministic resonance levels with a 2pi phase shift. By independently
controlling the phase delay of pixels, we further show tunable far-field beam
shaping. Our work paves the way to realizing non-volatile transmissive
phase-only spatial light modulators
Benchopt: Reproducible, efficient and collaborative optimization benchmarks
Numerical validation is at the core of machine learning research as it allows
to assess the actual impact of new methods, and to confirm the agreement
between theory and practice. Yet, the rapid development of the field poses
several challenges: researchers are confronted with a profusion of methods to
compare, limited transparency and consensus on best practices, as well as
tedious re-implementation work. As a result, validation is often very partial,
which can lead to wrong conclusions that slow down the progress of research. We
propose Benchopt, a collaborative framework to automate, reproduce and publish
optimization benchmarks in machine learning across programming languages and
hardware architectures. Benchopt simplifies benchmarking for the community by
providing an off-the-shelf tool for running, sharing and extending experiments.
To demonstrate its broad usability, we showcase benchmarks on three standard
learning tasks: -regularized logistic regression, Lasso, and ResNet18
training for image classification. These benchmarks highlight key practical
findings that give a more nuanced view of the state-of-the-art for these
problems, showing that for practical evaluation, the devil is in the details.
We hope that Benchopt will foster collaborative work in the community hence
improving the reproducibility of research findings.Comment: Accepted in proceedings of NeurIPS 22; Benchopt library documentation
is available at https://benchopt.github.io
A tablet-based quantitative assessment of manual dexterity for detection of early psychosis
BackgroundWe performed a pilot study on whether tablet-based measures of manual dexterity can provide behavioral markers for detection of first-episode psychosis (FEP), and whether cortical excitability/inhibition was altered in FEP.MethodsBehavioral and neurophysiological testing was undertaken in persons diagnosed with FEP (Nâ=â20), schizophrenia (SCZ, Nâ=â20), autism spectrum disorder (ASD, Nâ=â20), and in healthy control subjects (Nâ=â20). Five tablet tasks assessed different motor and cognitive functions: Finger Recognition for effector (finger) selection and mental rotation, Rhythm Tapping for temporal control, Sequence Tapping for control/memorization of motor sequences, Multi Finger Tapping for finger individuation, and Line Tracking for visuomotor control. Discrimination of FEP (from other groups) based on tablet-based measures was compared to discrimination through clinical neurological soft signs (NSS). Cortical excitability/inhibition, and cerebellar brain inhibition were assessed with transcranial magnetic stimulation.ResultsCompared to controls, FEP patients showed slower reaction times and higher errors in Finger Recognition, and more variability in Rhythm Tapping. Variability in Rhythm Tapping showed highest specificity for the identification of FEP patients compared to all other groups (FEP vs. ASD/SCZ/Controls; 75% sensitivity, 90% specificity, AUCâ=â0.83) compared to clinical NSS (95% sensitivity, 22% specificity, AUCâ=â0.49). Random Forest analysis confirmed FEP discrimination vs. other groups based on dexterity variables (100% sensitivity, 85% specificity, balanced accuracyâ=â92%). The FEP group had reduced short-latency intra-cortical inhibition (but similar excitability) compared to controls, SCZ, and ASD. Cerebellar inhibition showed a non-significant tendency to be weaker in FEP.ConclusionFEP patients show a distinctive pattern of dexterity impairments and weaker cortical inhibition. Easy-to-use tablet-based measures of manual dexterity capture neurological deficits in FEP and are promising markers for detection of FEP in clinical practice
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The Copernicus Marine Environment Monitoring Service Ocean State Report
The Copernicus Marine Environment Monitoring Service (CMEMS) Ocean State Report (OSR) provides an annual report of the state of the global ocean and European regional seas for policy and decision-makers with the additional aim of increasing general public awareness about the status of, and changes in, the marine environment. The CMEMS OSR draws on expert analysis and provides a 3-D view (through reanalysis systems), a view from above (through remote-sensing data) and a direct view of the interior (through in situ measurements) of the global ocean and the European regional seas. The report is based on the unique CMEMS monitoring capabilities of the blue (hydrography, currents), white (sea ice) and green (e.g. Chlorophyll) marine environment. This first issue of the CMEMS OSR provides guidance on Essential Variables, large-scale changes and specific events related to the physical ocean state over the period 1993â2015. Principal findings of this first CMEMS OSR show a significant increase in global and regional sea levels, thermosteric expansion, ocean heat content, sea surface temperature and Antarctic sea ice extent and conversely a decrease in Arctic sea ice extent during the 1993â2015 period. During the year 2015 exceptionally strong large-scale changes were monitored such as, for example, a strong El Niño Southern Oscillation, a high frequency of extreme storms and sea level events in specific regions in addition to areas of high sea level and harmful algae blooms. At the same time, some areas in the Arctic Ocean experienced exceptionally low sea ice extent and temperatures below average were observed in the North Atlantic Ocean
Atmospheric Science with InSight
International audienceIn November 2018, for the first time a dedicated geophysical station, the InSight lander, will be deployed on the surface of Mars. Along with the two main geophysical packages, the Seismic Experiment for Interior Structure (SEIS) and the Heat-Flow and Physical Properties Package (HP3), the InSight lander holds a highly sensitive pressure sensor (PS) and the Temperature and Winds for InSight (TWINS) instrument, both of which (along with the InSight FluxGate (IFG) Magnetometer) form the Auxiliary Sensor Payload Suite (APSS). Associated with the RADiometer (RAD) instrument which will measure the surface brightness temperature, and the Instrument Deployment Camera (IDC) which will be used to quantify atmospheric opacity, this will make InSight capable to act as a meteorological station at the surface of Mars. While probing the internal structure of Mars is the primary scientific goal of the mission, atmospheric science remains a key science objective for InSight. InSight has the potential to provide a more continuous and higher-frequency record of pressure, air temperature and winds at the surface of Mars than previous in situ missions. In the paper, key results from multiscale meteorological modeling, from Global Climate Models to Large-Eddy Simulations, are described as a reference for future studies based on the InSight measurements during operations. We summarize the capabilities of InSight for atmospheric observations, from profiling during Entry, Descent and Landing to surface measurements (pressure, temperature, winds, angular momentum), and the plans for how InSightâs sensors will be used during operations, as well as possible synergies with orbital observations. In a dedicated section, we describe the seismic impact of atmospheric phenomena (from the point of view of both ânoiseâ to be decorrelated from the seismic signal and âsignalâ to provide information on atmospheric processes). We discuss in this framework Planetary Boundary Layer turbulence, with a focus on convective vortices and dust devils, gravity waves (with idealized modeling), and large-scale circulations. Our paper also presents possible new, exploratory, studies with the InSight instrumentation: surface layer scaling and exploration of the Monin-Obukhov model, aeolian surface changes and saltation / lifing studies, and monitoring of secular pressure changes. The InSight mission will be instrumental in broadening the knowledge of the Martian atmosphere, with a unique set of measurements from the surface of Mars
MICROSCOPE mission: first results of a space test of the equivalence principle
According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10â15 precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force. Analysis of the first data gives ÎŽ(Ti,Pt)=[â1±9(stat)±9(syst)]Ă10â15 (1Ï statistical uncertainty) for the titanium-platinum Eötvös parameter characterizing the relative difference in their free-fall accelerations
BLOOM: A 176B-Parameter Open-Access Multilingual Language Model
Large language models (LLMs) have been shown to be able to perform new tasks
based on a few demonstrations or natural language instructions. While these
capabilities have led to widespread adoption, most LLMs are developed by
resource-rich organizations and are frequently kept from the public. As a step
towards democratizing this powerful technology, we present BLOOM, a
176B-parameter open-access language model designed and built thanks to a
collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer
language model that was trained on the ROOTS corpus, a dataset comprising
hundreds of sources in 46 natural and 13 programming languages (59 in total).
We find that BLOOM achieves competitive performance on a wide variety of
benchmarks, with stronger results after undergoing multitask prompted
finetuning. To facilitate future research and applications using LLMs, we
publicly release our models and code under the Responsible AI License
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