63 research outputs found
Wireless Communications with Space-Time Modulated Metasurfaces
Space-time modulated metasurfaces (STMMs) are a newly investigated technology
for next 6G generation wireless communication networks. An STMM augments the
spatial phase function with a time-varying one across the elements, allowing
for the conveyance of information that possibly modulates the impinging signal.
Hence, STMM represents an evolution of reconfigurable intelligent surfaces
(RIS), which only design the spatial phase pattern. STMMs convey signals
without a relevant increase in the energy budget, which is convenient for
applications where energy is a strong constraint. This paper proposes a
mathematical model for STMM-based wireless communication, that creates the
basics for two potential STMM architectures. One has excellent design
flexibility, whereas the other is more cost-effective. The model describes
STMM's distinguishing features, such as space-time coupling, and their impact
on system performance. The proposed STMM model addresses the design criteria of
a full-duplex system architecture, in which the temporal signal originating at
the STMM generates a modulation overlapped with the incident one. The presented
numerical results demonstrate the efficacy of the proposed model and its
potential to revolutionize wireless communication
Space-Time Phase Coupling in STMM-based Wireless Communications
Space-time modulated metasurfaces (STMMs) are a recently proposed
generalization of reconfigurable intelligent surfaces, which include a proper
time-varying phase at the metasurface elements, enabling higher flexibility and
control of the reflected signals. The spatial component can be designed to
control the direction of reflection, while the temporal one can be adjusted to
change the frequency of the reflected signal or to convey information. However,
the coupling between the spatial and temporal phases at the STMM can adversely
affect its performance. Therefore, this paper analyzes the system parameters
that affect the space-time coupling. Furthermore, two methods for space-time
decoupling are investigated. Numerical results highlight the effectiveness of
the proposed decoupling methods and reveal that the space-time phase coupling
increases with the bandwidth of the temporal phase, the size of the STMM, and
with grazing angles of incidence onto the STMM.Comment: 6 page
Advanced Tri-Sectoral Multi-User Millimeter-Wave Smart Repeater
Smart Repeaters (SR) can potentially enhance the coverage in Millimeter-wave
(mmWave) wireless communications. However, the angular coverage of the existing
two-panel SR is too limited to make the SR a truly cost-effective mmWave range
extender. This paper proposes the usage of a tri-sectoral Advanced SR (ASR) to
extend the angular coverage with respect to conventional SR. We propose a
multi-user precoder optimization for ASR in a downlink multi-carrier
communication system to maximize the number of served User Equipments (UEs)
while guaranteeing constraints on per-UE rate and time-frequency resources.
Numerical results show the benefits of the ASR against conventional SR in terms
of both cumulative spectral efficiency and number of served UEs (both improved
by an average factor 2), varying the system parameters
RF-Assisted Free-Space Optics for 5G Vehicle-to-Vehicle Communications
Vehicle-to-Vehicle (V2V) communications are being proposed, tested and
deployed to improve road safety and traffic efficiency. However, the automotive
industry poses strict requirements for safety-critical applications, that call
for reliable, low latency and high data rate communications. In this context,
it is widely agreed that both Radio-Frequency (RF) technologies at mmWaves and
Free-Space Optics (FSO) represent promising solutions, although their
performances are severely degraded by transmitter-receiver misalignment due to
the challenging high-mobility conditions. By combining RF and FSO technologies,
this paper proposes a FSO-based V2V communication system where the pointing
coordinates of laser sources are based on vehicle's information exchanged over
a reliable low-rate RF link. Numerical simulations demonstrate that such
compensation mechanism is mandatory to counteract the unavoidable misalignments
induced by vehicle dynamics, and thus to enable FSO technology for V2V
communications even in high mobility scenarios.Comment: Accepted in IEEE ICC 201
Reconfigurable and Static EM Skins on Vehicles for Localization
Electromagnetic skins (EMSs) have been recently considered as a booster for
wireless sensing, but their usage on mobile targets is relatively novel and
could be of interest when the target reflectivity can/must be increased to
improve its detection or the estimation of parameters. In particular, when
illuminated by a wide-bandwidth signal (e.g., from a radar operating at
millimeter waves), vehicles behave like \textit{extended targets}, since
multiple parts of the vehicle's body effectively contribute to the
back-scattering. Moreover, in some cases perspective deformations challenge the
correct localization of the vehicle. To address these issues, we propose
lodging EMSs on vehicles' roof to act as high-reflectivity planar
retro-reflectors toward the sensing terminal. The advantage is twofold:
\textit{(i)} by introducing a compact high-reflectivity structure on the
target, we make vehicles behave like \textit{point targets}, avoiding
perspective deformations and related ranging biases and \textit{(ii)} we
increase the reflectivity the vehicle, improving localization performance. We
detail the EMS design from the system-level to the full-wave-level considering
both reconfigurable intelligent surfaces (RIS) and cost-effective static
passive electromagnetic skins (SP-EMSs). Localization performance of the
EMS-aided sensing system is also assessed by Cram\'er-Rao bound analysis in
both narrowband and spatially wideband operating conditions
Drug repositioning : a machine-learning approach through data integration
Existing computational methods for drug repositioning either rely only on the gene expression response of cell lines after treatment, or on drug-to-disease relationships, merging several information levels. However, the noisy nature of the gene expression and the scarcity of genomic data for many diseases are important limitations to such approaches. Here we focused on a drug-centered approach by predicting the therapeutic class of FDA-approved compounds, not considering data concerning the diseases. We propose a novel computational approach to predict drug repositioning based on state-of-the-art machine-learning algorithms. We have integrated multiple layers of information: i) on the distances of the drugs based on how similar are their chemical structures, ii) on how close are their targets within the protein-protein interaction network, and iii) on how correlated are the gene expression patterns after treatment. Our classifier reaches high accuracy levels (78%), allowing us to re-interpret the top misclassifications as re-classifications, after rigorous statistical evaluation. Efficient drug repurposing has the potential to significantly impact the whole field of drug development. The results presented here can significantly accelerate the translation into the clinics of known compounds for novel therapeutic uses
INSIdE NANO : a systems biology framework to contextualize the mechanism-of-action of engineered nanomaterials
Engineered nanomaterials (ENMs) are widely present in our daily lives. Despite the efforts to characterize their mechanism of action in multiple species, their possible implications in human pathologies are still not fully understood. Here we performed an integrated analysis of the effects of ENMs on human health by contextualizing their transcriptional mechanism-of-action with respect to drugs, chemicals and diseases. We built a network of interactions of over 3,000 biological entities and developed a novel computational tool, INSIdE NANO, to infer new knowledge about ENM behavior. We highlight striking association of metal and metal-oxide nanoparticles and major neurodegenerative disorders. Our novel strategy opens possibilities to achieve fast and accurate read-across evaluation of ENMs and other chemicals based on their biosignatures.Peer reviewe
Long-term, low-dose tigecycline to treat relapsing bloodstream infection due to KPC-producing Klebsiella pneumoniae after major hepatic surgery
Summary A 68-year-old male underwent a right hepatectomy, resection of the biliary convergence, and a left hepatic jejunostomy for a Klatskin tumour. The postoperative course was complicated by biliary abscesses with relapsing bloodstream infections due to Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae (KPC-Kp). A 2-week course of combination antibiotic therapy failed to provide source control and the bacteraemia relapsed. Success was obtained with a regimen of tigecycline 100mg daily for 2 months, followed by tigecycline 50mg daily for 6 months, then 50mg every 48h for 3 months. No side effects were reported
Cooperative Coherent Multistatic Imaging and Phase Synchronization in Networked Sensing
Coherent multistatic radio imaging represents a pivotal opportunity for
forthcoming wireless networks, which involves distributed nodes cooperating to
achieve accurate sensing resolution and robustness. This paper delves into
cooperative coherent imaging for vehicular radar networks. Herein, multiple
radar-equipped vehicles cooperate to improve collective sensing capabilities
and address the fundamental issue of distinguishing weak targets in close
proximity to strong ones, a critical challenge for vulnerable road users
protection. We prove the significant benefits of cooperative coherent imaging
in the considered automotive scenario in terms of both probability of correct
detection, evaluated considering several system parameters, as well as
resolution capabilities, showcased by a dedicated experimental campaign wherein
the collaboration between two vehicles enables the detection of the legs of a
pedestrian close to a parked car. Moreover, as \textit{coherent} processing of
several sensors' data requires very tight accuracy on clock synchronization and
sensor's positioning -- referred to as \textit{phase synchronization} -- (such
that to predict sensor-target distances up to a fraction of the carrier
wavelength), we present a general three-step cooperative multistatic phase
synchronization procedure, detailing the required information exchange among
vehicles in the specific automotive radar context and assessing its feasibility
and performance by hybrid Cram\'er-Rao bound.Comment: 13 page
Observation of single phonon-mediated quantum transport in a silicon single-electron CMOS transistor by RMS noise analysis
We explore phonon-mediated quantum transport through electronic noise
characterization of a commercial CMOS transistor. The device behaves as a
single electron transistor thanks to a single impurity atom in the channel. A
low noise cryogenic CMOS transimpedance amplifier is exploited to perform
low-frequency noise characterization down to the single electron, single donor
and single phonon regime simultaneously, not otherwise visible through standard
stability diagrams. Single electron tunneling as well as phonon-mediated
features emerges in rms-noise measurements. Phonons are emitted at high
frequency by generation-recombination phenomena by the impurity atom. The
phonon decay is correlated to a Lorentzian noise at low frequency.Comment: 5 pages, 3 figures, submitted to AP
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