61 research outputs found
Multi-channel architecture for electronic quantum-Hall interferometry
We propose a new architecture for implementing electronic interferometry in
quantum Hall bars. It exploits scattering among parallel edge channels. In
contrast to previous developments, this one employs a simply-connected mesa
admitting serial concatenation of building elements closer to optical
analogues. Implementations of Mach-Zehnder and Hambury-Brown-Twiss
interferometers are discussed together with new structures yet unexplored in
quantum electronics.Comment: 4 pages, 5 figure
Gauge fields and interferometry in folded graphene
Folded graphene flakes are a natural byproduct of the micromechanical
exfoliation process. In this Letter we show by a combination of analytical and
numerical methods that such systems behave as intriguing interferometers due to
the interplay between an externally applied magnetic field and the gauge field
induced by the deformations in the region of the fold.Comment: 4 pages, 3 figure
Characterizing electron entanglement in multiterminal mesoscopic conductors
We show that current correlations at the exit ports of a beam splitter can be
used to detect electronic entanglement for a fairly general input state. This
includes the situation where electron pairs can enter the beam splitter from
the same port or be separated due to backscattering. The proposed scheme allows
to discriminate between occupation-number and degree-of-freedom entanglement.Comment: 5 pages, 1 figure. Ref. adde
Electronic Hong-Ou-Mandel interferometer for multi-mode entanglement detection
We show that multi-mode entanglement of electrons in a mesoscopic conductor
can be detected by a measurement of the zero-frequency current correlations in
an electronic Hong-Ou-Mandel interferometer. By this mean, one can further
establish a lower bound to the entanglement of formation of two-electron input
states. Our results extend the work of Burkard and Loss [Phys. Rev. Lett. 91,
087903 (2003)] to many channels and provide a way to test the existence of
entangled states involving both orbital and spin degrees of freedom.Comment: 6 pages. Revised version. Ref. adde
Blockade and Counterflow Supercurrent in exciton-condensate Josephson junctions
We demonstrate that perfect conversion between charged supercurrents in
superconductors and neutral supercurrents in electron-hole pair condensates is
possible via a new Andreev-like scattering mechanism. As a result, when two
superconducting circuits are coupled through a bilayer exciton condensate, the
superflow in both layers is drastically modified. Depending on the phase biases
the supercurrents can be completely blocked or exhibit perfect drag.Comment: 4 pages, 2 figure
Wear behavior characterization of hydrogels constructs for cartilage tissue replacement
This paper aims to characterize the wear behavior of hydrogel constructs designed for human articular cartilage replacement. To this purpose, poly (ethylene glycol) diacrylate (PEGDA) 10% w/v and gellan gum (GG) 1.5% w/v were used to reproduce the superior (SUP) cartilage layer and PEGDA 15% w/v and GG 1.5% w/v were used to reproduce the deep (DEEP) cartilage layer, with or without graphene oxide (GO). These materials (SUP and DEEP) were analyzed alone and in combination to mimic the zonal architecture of human articular cartilage. The developed constructs were tested using a four-station displacement control knee joint simulator under bovine calf serum. Roughness and micro-computer tomography (µ-CT) measurements evidenced that the hydrogels with 10% w/v of PEGDA showed a worse behavior both in terms of roughness increase and loss of uniformly distributed density than 15% w/v of PEGDA. The simultaneous presence of GO and 15% w/v PEGDA contributed to keeping the hydrogel construct’s characteristics. The Raman spectra of the control samples showed the presence of unreacted C=C bonds in all the hydrogels. The degree of crosslinking increased along the series SUP < DEEP + SUP < DEEP without GO. The Raman spectra of the tested hydrogels showed the loss of diacrylate groups in all the samples, due to the washout of unreacted PEGDA in bovine calf serum aqueous environment. The loss decreased along the series SUP > DEEP + SUP > DEEP, further confirming that the degree of photo-crosslinking of the starting materials plays a key role in determining their wear behavior. µ-CT and Raman spectroscopy proved to be suitable techniques to characterize the structure and composition of hydrogels
Geometric phases and Andreev reflection in hybrid rings
We study the Andreev reflection of a hybrid mesoscopic ring in the presence
of a crown-like magnetic texture. By calculating the linear-response
conductance as a function of the Zeeman splitting and the magnetic flux through
the ring, we are able to identify signatures of the Berry phase acquired by the
electrons during transport. This is proposed as a novel detection scheme of the
spin-related Berry phase, having the advantage of a larger signal contrast and
robustness against ensemble averaging.Comment: 6 pages, 6 figures. To appear in Phys. Rev.
Andreev reflection in graphene nanoribbons
We study Andreev reflection in graphene nanoribbon/superconductor hybrid
junctions. By using a tight-binding approach and the scattering formalism we
show that finite-size effects lead to notable differences with respect to the
bulk graphene case. At subgap voltages, conservation of pseudoparity, a quantum
number characterizing the ribbon states, yields either a suppression of Andreev
reflection when the ribbon has an even number of sites in the transverse
direction or perfect Andreev reflection when the ribbon has an odd number of
sites. In the former case the suppression of Andreev reflection induces an
insulating behavior even when the junction is biased; electron conduction can
however be restored by applying a gate voltage.Comment: 6 pages, 6 figure
MEDIATION: An eMbEddeD System for Auditory Feedback of Hand-water InterAcTION while Swimming
Cesarini D, Calvaresi D, Farnesi C, et al. MEDIATION: An eMbEddeD System for Auditory Feedback of Hand-water InterAcTION while Swimming. Procedia Engineering. 2016;147:324-329.In swimming sport, the proper perception of moving water masses is a key factor. This paper presents an embedded system for the acquisition of values of pressure on swimmers hands and their transformation into sound. The sound, obtained using sonification, is used as an auditive representation of hand-water interactions while swimming in water. The sound obtained is used as an auditive feedback for the swimmer and as an augmented communication channel between the swimming trainer and the athlete. The developed system is self-contained, battery powered and able to work continuously for over eight hours, thus, representing a viable solution for daily usage in swimmers training. Preliminary results from in-pool experiments with both novel and experienced swimmers demonstrate the high acceptability of this technology and its promising future evolution and usage possibilities
Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis
BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
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