753 research outputs found
Aberration cancellation in quantum interferometry
We report the first experimental demonstration of even-order aberration
cancellation in quantum interferometry. The effect is a spatial counterpart of
the spectral group velocity dispersion cancellation, which is associated with
spectral entanglement. It is manifested in temporal interferometry by virtue of
the multi-parameter spatial-spectral entanglement. Spatially-entangled photons,
generated by spontaneous parametric down conversion, were subjected to spatial
aberrations introduced by a deformable mirror that modulates the wavefront. We
show that only odd-order spatial aberrations affect the quality of quantum
interference
Determination of perfluoroalkyl acids in different tissues of graminaceous plants
A method for the determination of 12 perfluoroalkylacids (PFAA) in vegetal samples was proposed. The analytical procedure was developed to optimize the detention of short-chain PFAA (C<8) due to their higher potential to be translocated and bioaccumulated in plants than long-chain congeners. The method, based on ultrasonic extraction, clean-up and HPLC-MS/MS analysis, determined PFAA in the different plant tissues allowing to study the PFAA distribution and partition in vegetal compartments. The performance of this analytical procedure was validated by analysing samples (root, stem and leaf) of reed grass. The validated method was then applied to graminaceous plants from an agricultural area impacted by a fluorochemical plant discharge (Northern Italy). The PFAA congeners were detected in the most of samples with PFAA concentrations in whole plant ranging from < LOD to 10.4 ng g-1 ww and with a greater rate of PFAA accumulation in corn cob than corn kernel. The proposed approach is particularly relevant in edible plant investigation because PFAA levels recorded in the comestible fractions provide information for human risk assessment due to vegetable consumption. Furthermore data on the remaining not edible parts, intended for breeding forage, are also useful for the assessment of the PFAA transfer in the breeding trophic chain
Vision-State Fusion: Improving Deep Neural Networks for Autonomous Robotics
Vision-based perception tasks fulfill a paramount role in robotics,
facilitating solutions to many challenging scenarios, such as acrobatics
maneuvers of autonomous unmanned aerial vehicles (UAVs) and robot-assisted high
precision surgery. Most control-oriented and egocentric perception problems are
commonly solved by taking advantage of the robot state estimation as an
auxiliary input, particularly when artificial intelligence comes into the
picture. In this work, we propose to apply a similar approach for the first
time - to the best of our knowledge - to allocentric perception tasks, where
the target variables refer to an external subject. We prove how our general and
intuitive methodology improves the regression performance of deep convolutional
neural networks (CNNs) with ambiguous problems such as the allocentric 3D pose
estimation. By analyzing three highly-different use cases, spanning from
grasping with a robotic arm to following a human subject with a pocket-sized
UAV, our results consistently improve the R2 metric up to +0.514 compared to
their stateless baselines. Finally, we validate the in-field performance of a
closed-loop autonomous pocket-sized UAV in the human pose estimation task. Our
results show a significant reduction, i.e., 24% on average, on the mean
absolute error of our stateful CNN.Comment: 8 pages, 8 figure
Complementary encoding of spatial information in hippocampal astrocytes
Calcium dynamics into astrocytes influence the activity of nearby neuronal structures. However, because previous reports show that astrocytic calcium signals largely mirror neighboring neuronal activity, current information coding models neglect astrocytes. Using simultaneous two-photon calcium imaging of astrocytes and neurons in the hippocampus of mice navigating a virtual environment, we demonstrate that astrocytic calcium signals encode (i.e., statistically reflect) spatial information that could not be explained by visual cue information. Calcium events carrying spatial information occurred in topographically organized astrocytic subregions. Importantly, astrocytes encoded spatial information that was complementary and synergistic to that carried by neurons, improving spatial position decoding when astrocytic signals were considered alongside neuronal ones. These results suggest that the complementary place dependence of localized astrocytic calcium signals may regulate clusters of nearby synapses, enabling dynamic, context-dependent variations in population coding within brain circuits
Phase control of a longitudinal momentum entangled photon state by a deformable membrane mirror
We propose a paradigmatic demonstration of the potentialities of a deformable
mirror for closed-loop control of a two-photon momentum-entangled state,
subject to phase fluctuations. A custom-made membrane mirror is used to set a
relative phase shift between the arms of an interferometric apparatus. The
control algorithm estimates the phase of the quantum state, by measurements of
the coincidence events at the output ports of the interferometer, and uses the
measurements results to provide a feedback signal to the deformable mirror.
Stabilization of the coincidence rate to within 1.5 standard deviation of the
Poissonian noise is demonstrated over 2000 seconds.Comment: RevTex, 6 page
Cyber Security aboard Micro Aerial Vehicles: An OpenTitan-based Visual Communication Use Case
Autonomous Micro Aerial Vehicles (MAVs), with a form factor of 10cm in
diameter, are an emerging technology thanks to the broad applicability enabled
by their onboard intelligence. However, these platforms are strongly limited in
the onboard power envelope for processing, i.e., less than a few hundred mW,
which confines the onboard processors to the class of simple microcontroller
units (MCUs). These MCUs lack advanced security features opening the way to a
wide range of cyber security vulnerabilities, from the communication between
agents of the same fleet to the onboard execution of malicious code. This work
presents an open source System on Chip (SoC) design that integrates a 64 bit
Linux capable host processor accelerated by an 8 core 32 bit parallel
programmable accelerator. The heterogeneous system architecture is coupled with
a security enclave based on an open source OpenTitan root of trust. To
demonstrate our design, we propose a use case where OpenTitan detects a
security breach on the SoC aboard the MAV and drives its exclusive GPIOs to
start a LED blinking routine. This procedure embodies an unconventional visual
communication between two palm sized MAVs: the receiver MAV classifies the LED
state of the sender (on or off) with an onboard convolutional neural network
running on the parallel accelerator. Then, it reconstructs a high-level message
in 1.3s, 2.3 times faster than current commercial solutions
A novel approach to the analysis of muscle synergies based on the average threshold crossing technique
The work herein presented aimed to investigate the application of the Average Threshold Crossing (ATC) technique in the analysis of muscle synergies. The ability of the technique to approximate different modulations of the electromyographic (EMG) data was assessed via simulations. By selecting the proper threshold and window length, it was possible to obtain R2 similarity values above 0.8. This result improved by averaging the ATC envelopes over multiple epochs. The technique was also tested on real EMG data collected from 8 subjects during over ground walking. The synergies extracted using the ATC technique showed high similarity with the ones obtained with a standard approach using the EMG envelopes for both weights and temporal activations
Transparent control in overground walking exoskeleton reveals interesting changing in subject's stepping frequency
ABSTRACT: Lower-limb gait training (GT) exoskeletons have been successfully used in rehabilitation programs to overcome the burden of locomotor impairment. However, providing suitable net interaction torques to assist patient movements is still a challenge. Previous transparent operation approaches have been tested in treadmill-based GT exoskeletons to improve user-robot interaction. However, it is not yet clear how a transparent lower-limb GT system affects user’s gait kinematics during overground walking, which unlike treadmill-based systems, requires active participation of the subjects to maintain stability. In this study, we implemented a transparent operation strategy on the ExoRoboWalker, an overground GT exoskeleton, to investigate its effect on the user’s gait. The approach employs a feedback zero-torque controller with feedforward compensation for the exoskeleton’s dynamics and actuators’ impedance. We analyzed the data of five healthy subjects walking overground with the exoskeleton in transparent mode (ExoTransp) and non-transparent mode (ExoOff) and walking without exoskeleton (NoExo). The transparent controller reduced the user-robot interaction torque and improved the user’s gait kinematics relative to ExoOff. No significant difference in stride length is observed between ExoTransp and NoExo (p = 0.129). However, the subjects showed a significant difference in cadence between ExoTransp (50.9± 1.1 steps/min) and NoExo (93.7 ± 8.7 steps/min) (p = 0.015), but not between ExoTransp and ExoOff (p = 0.644). Results suggest that subjects wearing the exoskeleton adjust their gait as in an attention-demanding task changing the spatiotemporal gait characteristics likely to improve gait balance
JRC Data Policy
The work on the JRC Data Policy followed the task identified in the JRC Management Plan 2014 to develop a dedicated data policy to complement the JRC Policy on Open Access to Scientific Publications and Supporting Guidance, and to promote open access to research data in the context of Horizon 2020. Important policy commitments and the relevant regulatory basis within the European Union and the European Commission include: the Commission Decision on the reuse of Commission documents, Commission communication on better access to scientific information, Commission communication on a reinforced European research area partnership for excellence and growth, Commission recommendation on access to and preservation of scientific information, and the EU implementation of the G8 Open Data Charter.JRC.H.6-Digital Earth and Reference Dat
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