169 research outputs found
Elastic Temporal Waveguiding
We provide a theoretical framework to mold time-modulated lattices with
frequency conversion and wave-steering capabilities. We initially focus on 1D
lattices, whereby a sufficiently slow time-modulation of the stiffness is
employed to convert the frequency content of impinging waves. Based on the
adiabatic theorem, we demonstrate that undesired reflections, which emerge in
time-discontinuous materials, can be eliminated by a careful choice of the
modulation velocity. The concept is later explored in the context of 2D
lattices, whereby a slow time modulation of the stiffness not only induces
frequency conversion without back-scattering, but also serves as a mechanism to
steer waves. Our paper explores a new and exciting way to control wave
propagation in elastodynamics with scattering-free guiding capabilities, and
may open new avenues for the manipulation and transport of information through
elastic waves
Edge States and Topological Pumping in Stiffness Modulated Elastic Plates
We demonstrate that modulations of the stiffness properties of an elastic
plate along a spatial dimension induce edge states spanning non-trivial gaps
characterized by integer valued Chern numbers. We also show that topological
pumping is induced by smooth variations of the phase of the modulation profile
along one spatial dimension, which results in adiabatic edge-to-edge
transitions of the edge states. The concept is first illustrated numerically
for sinusoidal stiffness modulations, and then experimentally demonstrated in a
plate with square-wave thickness profile. The presented numerical and
experimental results show how continuous modulations of properties may be
exploited in the quest for topological phases of matter. This opens new
possibilities for topology-based waveguiding through slow modulations along a
second dimension, spatial or temporal
Experimental multiphase estimation on a chip
Multiparameter estimation is a general problem that aims at measuring unknown
physical quantities, obtaining high precision in the process. In this context,
the adoption of quantum resources promises a substantial boost in the
achievable performances with respect to the classical case. However, several
open problems remain to be addressed in the multiparameter scenario. A crucial
requirement is the identification of suitable platforms to develop and
experimentally test novel efficient methodologies that can be employed in this
general framework. We report the experimental implementation of a
reconfigurable integrated multimode interferometer designed for the
simultaneous estimation of two optical phases. We verify the high-fidelity
operation of the implemented device, and demonstrate quantum-enhanced
performances in two-phase estimation with respect to the best classical case,
post-selected to the number of detected coincidences. This device can be
employed to test general adaptive multiphase protocols due to its high
reconfigurability level, and represents a powerful platform to investigate the
multiparameter estimation scenario.Comment: 10+7 pages, 7+4 figure
Privacy and Transparency in Blockchain-based Smart Grid Operations
In the past few years, blockchain technology has emerged in numerous smart grid applications,
enabling the construction of systems without the need for a trusted third party. Blockchain
offers transparency, traceability, and accountability, which lets various energy management system
functionalities be executed through smart contracts, such as monitoring, consumption analysis,
and intelligent energy adaptation. Nevertheless, revealing sensitive energy consumption information
could render users vulnerable to digital and physical assaults. This paper presents a novel method
for achieving a dual balance between privacy and transparency, as well as accountability and
verifiability. This equilibrium requires the incorporation of cryptographic tools like Secure Mul-
tiparty Computation and Verifiable Secret Sharing within the distributed components of a multi-
channel blockchain and its associated smart contracts. We corroborate the suggested architecture
throughout the entire process of a Demand Response scenario, from the collection of energy data
to the ultimate reward. To address our proposal’s constraints, we present countermeasures against
accidental crashes and Byzantine behavior while ensuring that the solution remains appropriate
for low-performance IoT devices
SIOUX project: a simultaneous multiband camera for exoplanet atmospheres studies
The exoplanet revolution is well underway. The last decade has seen
order-of-magnitude increases in the number of known planets beyond the Solar
system. Detailed characterization of exoplanetary atmospheres provide the best
means for distinguishing the makeup of their outer layers, and the only hope
for understanding the interplay between initial composition chemistry,
temperature-pressure atmospheric profiles, dynamics and circulation. While
pioneering work on the observational side has produced the first important
detections of atmospheric molecules for the class of transiting exoplanets,
important limitations are still present due to the lack of sys- tematic,
repeated measurements with optimized instrumentation at both visible (VIS) and
near-infrared (NIR) wavelengths. It is thus of fundamental importance to
explore quantitatively possible avenues for improvements. In this paper we
report initial results of a feasibility study for the prototype of a versatile
multi-band imaging system for very high-precision differential photometry that
exploits the choice of specifically selected narrow-band filters and novel
ideas for the execution of simultaneous VIS and NIR measurements. Starting from
the fundamental system requirements driven by the science case at hand, we
describe a set of three opto-mechanical solutions for the instrument prototype:
1) a radial distribution of the optical flux using dichroic filters for the
wavelength separation and narrow-band filters or liquid crystal filters for the
observations; 2) a tree distribution of the optical flux (implying 2 separate
foci), with the same technique used for the beam separation and filtering; 3)
an exotic solution consisting of the study of a complete optical system (i.e. a
brand new telescope) that exploits the chromatic errors of a reflecting surface
for directing the different wavelengths at different foci
Splanchnic vein thrombosis : current perspectives
Splanchnic vein thrombosis (SVT) including portal, mesenteric, splenic vein thrombosis and the Budd-Chiari syndrome, is a manifestation of unusual site venous thromboembolism. SVT presents with a lower incidence than deep vein thrombosis of the lower limbs and pulmonary embolism, with portal vein thrombosis and Budd-Chiari syndrome being respectively the most and the least common presentations of SVT. SVT is classified as provoked if secondary to a local or systemic risk factor, or unprovoked if the causative trigger cannot be identified. Diagnostic evaluation is often affected by the lack of specificity of clinical manifestations: the presence of one or more risk factors in a patient with a high clinical suspicion may suggest the execution of diagnostic tests. Doppler ultrasonography represents the first line diagnostic tool because of its accuracy and wide availability. Further investigations, such as computed tomography and magnetic resonance angiography, should be executed in case of suspected thrombosis of the mesenteric veins, suspicion of SVT-related complications, or to complete information after Doppler ultrasonography. Once SVT diagnosis is established, a careful patient evaluation should be performed in order to assess the risks and benefits of the anticoagulant therapy and to drive the optimal treatment intensity. Due to the low quality and large heterogeneity of published data, guidance documents and expert opinion could direct therapeutic decision, suggesting which patients to treat, which anticoagulant to use and the duration of treatment.peer-reviewe
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