585 research outputs found
Photon mediated interaction between distant quantum dot circuits
Engineering the interaction between light and matter is an important goal in
the emerging field of quantum opto-electronics. Thanks to the use of cavity
quantum electrodynamics architectures, one can envision a fully hybrid
multiplexing of quantum conductors. Here, we use such an architecture to couple
two quantum dot circuits . Our quantum dots are separated by 200 times their
own size, with no direct tunnel and electrostatic couplings between them. We
demonstrate their interaction, mediated by the cavity photons. This could be
used to scale up quantum bit architectures based on quantum dot circuits or
simulate on-chip phonon-mediated interactions between strongly correlated
electrons
Chemical analysis and aqueous solution properties of Charged Amphiphilic Block Copolymers PBA-b-PAA synthesized by MADIX
We have linked the structural and dynamic properties in aqueous solution of
amphiphilic charged diblock copolymers poly(butyl acrylate)-b-poly(acrylic
acid), PBA-b-PAA, synthesized by controlled radical polymerization, with the
physico-chemical characteristics of the samples. Despite product imperfections,
the samples self-assemble in melt and aqueous solutions as predicted by
monodisperse microphase separation theory. However, the PBA core are abnormally
large; the swelling of PBA cores is not due to AA (the Flory parameter
chiPBA/PAA, determined at 0.25, means strong segregation), but to h-PBA
homopolymers (content determined by Liquid Chromatography at the Point of
Exclusion and Adsorption Transition LC-PEAT). Beside the dominant population of
micelles detected by scattering experiments, capillary electrophoresis CE
analysis permitted detection of two other populations, one of h-PAA, and the
other of free PBA-b-PAA chains, that have very short PBA blocks and never
self-assemble. Despite the presence of these free unimers, the self-assembly in
solution was found out of equilibrium: the aggregation state is history
dependant and no unimer exchange between micelles occurs over months
(time-evolution SANS). The high PBA/water interfacial tension, measured at 20
mN/m, prohibits unimer exchange between micelles. PBA-b-PAA solution systems
are neither at thermal equilibrium nor completely frozen systems: internal
fractionation of individual aggregates can occur.Comment: 32 pages, 16 figures and 4 tables submitted to Journal of Interface
and Colloidal Scienc
Variable Selection and Model Averaging in Semiparametric Overdispersed Generalized Linear Models
We express the mean and variance terms in a double exponential regression
model as additive functions of the predictors and use Bayesian variable
selection to determine which predictors enter the model, and whether they enter
linearly or flexibly. When the variance term is null we obtain a generalized
additive model, which becomes a generalized linear model if the predictors
enter the mean linearly. The model is estimated using Markov chain Monte Carlo
simulation and the methodology is illustrated using real and simulated data
sets.Comment: 8 graphs 35 page
Anatomical study and reanalysis of the nomenclature of the anterolateral complex of the knee focusing on the distal iliotibial band: identification and description of the condylar strap
Background: The capsulo-osseous layer, short lateral ligament, mid-third lateral capsular ligament, lateral capsular ligament and anterolateral ligament are terms that have been used interchangeably to describe what is probably the same structure. This has resulted in confusion regarding the anatomy and function of the anterolateral complex of the knee and its relation to the distal iliotibial band.
Purpose: To characterize the macroscopic anatomy of the anterolateral complex of the knee, in particular the femoral condylar attachment of the distal iliotibial band (ITB). We identified a specific and consistent anatomical structure that was not accurately described previously, connects the deep surface of the ITB to the condylar area, and is distinct from the anterolateral ligament, the capsulo-osseous layer and the Kaplan fibers.
Study Design: Descriptive laboratory study.
Methods: Sixteen fresh-frozen human cadaveric knees were used to study the anterolateral complex of the knee. Standardized dissections were performed that included a qualitative and quantitative assessment of the anatomy through both anterior (n=5) and posterior (n=11) approaches.
Results: The femoral condylar attachment of the distal ITB was not reliably identified by anterior dissection but was in all posterior dissections. A distinct anatomical structure, hereafter termed condylar strap (CS), was identified between the femur and the lateral gastrocnemius on one side and the deep surface of the ITB on the other, in all posteriorly dissected specimens. The structure had a mean thickness of 0.88 mm, and its femoral insertion was located between the distal Kaplan fibers and the epicondyle. The proximal femoral attachment of the structure had a mean width of 15.82 mm and the width of the distal insertion of the structure on the ITB was 13.27 mm. The mean length of the structure was 26.33 mm on its distal border and 21.88 mm on its proximal border. Qualitative evaluation of behavior in internal rotation revealed that this anatomical structure became tensioned and created a tenodesis effect on the ITB.
Conclusions: There is a consistent structure that attaches to the deep ITB and the femoral epicondylar area. The orientation of fibers suggest that it may have a role in anterolateral knee stability.
Clinical Relevance: This new anatomical description may help surgeons to optimize technical aspects of lateral extra-articular procedures in cases of anterolateral knee laxity
Evidence for a Peierls phase-transition in a three-dimensional multiple charge-density waves solid
The effect of dimensionality on materials properties has become strikingly
evident with the recent discovery of graphene. Charge ordering phenomena can be
induced in one dimension by periodic distortions of a material's crystal
structure, termed Peierls ordering transition. Charge-density waves can also be
induced in solids by strong Coulomb repulsion between carriers, and at the
extreme limit, Wigner predicted that crystallization itself can be induced in
an electrons gas in free space close to the absolute zero of temperature.
Similar phenomena are observed also in higher dimensions, but the microscopic
description of the corresponding phase transition is often controversial, and
remains an open field of research for fundamental physics. Here, we photoinduce
the melting of the charge ordering in a complex three-dimensional solid and
monitor the consequent charge redistribution by probing the optical response
over a broad spectral range with ultrashort laser pulses. Although the
photoinduced electronic temperature far exceeds the critical value, the
charge-density wave is preserved until the lattice is sufficiently distorted to
induce the phase transition. Combining this result with it ab initio}
electronic structure calculations, we identified the Peierls origin of multiple
charge-density waves in a three-dimensional system for the first time.Comment: Accepted for publication in Proc. Natl. Acad. Sci. US
Multi-terminal spin-dependent transport in ballistic carbon nanotubes
We study theoretically nonlocal spin transport in a ballistic carbon nanotube
contacted to two ferromagnetic leads and two normal-metal leads. When the
magnetizations of the two ferromagnets are changed from a parallel to an
antiparallel configuration, the circuit shows a hysteretic behavior which is
specific to the few-channel regime. In the coherent limit, the amplitude of the
magnetic signals is strongly enhanced due to resonance effects occurring inside
the nanotube. Our calculations pave the way for experiments on low-dimensional
nonlocal spin transport, which should give results remarkably different from
the experiments realized so far in the multichannel diffusive incoherent
regime.Comment: 9 pages, 8 figure
Positive cross-correlations due to Dynamical Channel-Blockade in a three-terminal quantum dot
We investigate current fluctuations in a three-terminal quantum dot in the
sequential tunneling regime. In the voltage-bias configuration chosen here, the
circuit is operated like a beam splitter, i.e. one lead is used as an input and
the other two as outputs. In the limit where a double occupancy of the dot is
not possible, a super-Poissonian Fano factor of the current in the input lead
and positive cross-correlations between the current fluctuations in the two
output leads can be obtained, due to dynamical channel-blockade. When a single
orbital of the dot transports current, this effect can be obtained by lifting
the spin-degeneracy of the circuit with ferromagnetic leads or with a magnetic
field. When several orbitals participate in the electronic conduction, lifting
spin-degeneracy is not necessary. In all cases, we show that a super-Poissonian
Fano factor for the input current is not equivalent to positive
cross-correlations between the outputs. We identify the conditions for
obtaining these two effects and discuss possible experimental realizations.Comment: 18 pages, 20 Figures, submitted to Phys. rev.
Meniscal ossicle in a professional soccer player
SummaryMeniscal ossicles are an unusual finding and a rare cause for knee pain. They are often initially diagnosed as a loose body, chondrocalcinosis or meniscal calcification within the knee joint. Few cases have been reported in the literature. We present a case of a meniscal ossicle with an associated femoral cartilage lesion in a healthy 26-year-old male professional soccer player who presented with swelling and pain. The purpose of this article is to discuss the origins, radiological features, clinical symptoms and prognosis of meniscal ossicles
Harnessing spin precession with dissipation
International audienceNon-collinear spin transport is at the heart of spin or magnetization control in spintronics devices. The use of nanoscale conductors exhibiting quantum effects in transport could provide new paths for that purpose. Here we study non-collinear spin transport in a quantum dot. We use a device made out of a single-wall carbon nanotube connected to orthogonal ferromagnetic electrodes. In the spin transport signals, we observe signatures of out of equilibrium spin precession that are electrically tunable through dissipation. This could provide a new path to harness spin precession in nanoscale conductors
High lateral portal for sparing the infrapatellar fat-pad during ACL reconstruction
SummaryDuring arthroscopic ACL reconstruction, intra-articular visualization can be compromised by the interposition of the infrapatellar fat pad (IPFP) between the scope and the notch. In this technical note, we describe our technique of using lateral higher arthroscopic portal, starting arthroscopy with the resection of the ligamentum mucosum and performing the tibial tunnel in 40° of knee flexion to optimise the intra-articular view without IPFP debridement. This technique was performed in 112 consecutive arthroscopic ACL reconstructions and compared to that in the previous 112 cases in which a conventional method was used. The use of this technique was associated with a shorter operative time and no increase in the difficulty in performing associated meniscal procedures
- …