Manipulating the Quantum State of an Electrical Circuit

We have designed and operated a superconducting tunnel junction circuit that behaves as a two-level atom: the ``quantronium''. An arbitrary evolution of its quantum state can be programmed with a series of microwave pulses, and a projective measurement of the state can be performed by a pulsed readout sub-circuit. The measured quality factor of quantum coherence Qphi=25000 is sufficiently high that a solid-state quantum processor based on this type of circuit can be envisioned.Comment: 4 figures include

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

Controlling spin in an electronic interferometer with spin-active interfaces

We consider electronic current transport through a ballistic one-dimensional quantum wire connected to two ferromagnetic leads. We study the effects of the spin-dependence of interfacial phase shifts (SDIPS) acquired by electrons upon scattering at the boundaries of the wire. The SDIPS produces a spin splitting of the wire resonant energies which is tunable with the gate voltage and the angle between the ferromagnetic polarizations. This property could be used for manipulating spins. In particular, it leads to a giant magnetoresistance effect with a sign tunable with the gate voltage and the magnetic field applied to the wire.Comment: 5 pages, 3 figures. to be published in Europhysics Letter

HSV2 acute retinal necrosis: diagnosis and monitoring with quantitative polymerase chain reaction

Purpose To describe a case of HSV2 acute retinal necrosis (ARN) diagnosed and monitored with quantitative polymerase chain reaction (PCR) in ocular fluids. Design Case report. Methods Quantitative PCR was performed in the aqueous humor (AH) and vitreous using primers specific for herpes virus. Results A positive PCR was found for HSV2 in the AH (>100,000,000 viral copies − 8.00log/ml). After therapy, another anterior chamber tap showed a reduction of the viral load at 4.28log/ml (19205 copies), confirming the efficacy of the treatment. After six months, PCR on the vitreous still showed the presence of HSV2 viral particles in the eye (3.14 log DNA copies/ml, 1379 copies) although the lesion was healed. Conclusions This case demonstrates that PCR is useful to detect viral DNA in AH and vitreous and to monitor viral activity and therapeutic response. Viral DNA persists in ocular fluids for months in the presence of a healed infectio

Combined ACL reconstruction and Segond fracture fixation fails to abolish anterolateral rotatory instability

The Segond Fracture (SF) is considered pathognomonic of an anterior cruciate ligament (ACL) tear. However, the precise anatomy of the soft tissue attachments responsible for avulsion of SF’s have been a cause of controversy in the literature with some authors suggesting that they occur due to avulsion of the iliotibial band (ITB) and others reporting that it is the anterolateral ligament (ALL). A thirty-one-year-old male patient presented with a work-related injury to his right knee that resulted in ACL tear and a SF. Open SF fixation and arthroscopic ACL reconstruction were performed. The anatomical dissection performed in order to fix the SF demonstrated that the avulsion had occurred as a result of the tibial attachment of the ALL with a completely intact ITB. At one-year postoperative follow-up, the ACL graft had restored anterior tibial translation to within normal limits. However, residual rotational knee laxity was observed in the absence of any other secondary restraint lesions. This is an important finding because it highlights that patients with SF may be at increased risk of persistent instability after ACL reconstruction even in the presence of an anatomically correctly positioned and well-functioning ACL graft. It also demonstrates that anatomical reduction and fixation of SF at the time of ACLR does not necessarily restore normal knee kinematics and consideration should be given to recession of the fixation or augmentation of the ALL when dealing with this injury pattern. A thirty-one-year-old male patient presented with a work-related injury to his right knee that occurred when he was struck by a truck at low speed. The mechanism of injury involved anterior tibial translation, varus stress and internal rotation. Physical examination revealed the following findings: large joint effusion, range of motion 0-100º, no neurological or vascular deficit, positive Lachman’s test with a soft end-point, a side-to-side anteroposterior laxity difference of 7mm measured by the Rolimeter device (Aircast, Europe), and a grade II pivot-shift (clunk). Plain radiographs demonstrated a fracture of the anterolateral border of the tibial plateau (figure 1A) and MRI showed a complete anterior cruciate ligament (ACL) rupture with a concomitant 3x16x18mm fracture of the anterolateral tibial border (figure 1B). MRI did not demonstrate any other intra- or extra-articular injuries. Specifically, there was no evidence of injury to any other ligamentous structure, chondral injury, lateral condyle notch sign, or any type of meniscal tear

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.

Arthrogenic muscle inhibition after ACL reconstruction: a scoping review of the efficacy of interventions

Objective: To determine whether reported therapeutic interventions for arthrogenic muscle inhibition (AMI) in patients with ACL injuries, following ACL reconstruction, or in laboratory studies of AMI, are effective in improving quadriceps activation failure when compared with standard therapy in control groups. Design: A scoping review of the efficacy of interventions was conducted in accordance with the methodological framework of Arksey and O'Malley and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Search terms included 'arthrogenic muscle inhibition', 'quadriceps activation following knee injuries', 'anterior cruciate' or 'knee’ combined with 'quadriceps activation', 'quadriceps inhibition', 'corticomotor', 'arthrogenic', 'brain activation' and 'neuroplasticity'. Articles were evaluated for risk of bias using the PEDro (Physiotherapy Evidence Database) criteria. The overall quality of evidence for each intervention was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE). Data sources: PubMed, EMBASE and Cumulative Index to Nursing and Allied Health Literature databases. Eligibility criteria for selecting studies: Isolated case reports and articles reporting outcomes in patients with chronic disease or major trauma were excluded. All other original research articles were included. Results: 780 potential articles were identified. 20 met the inclusion criteria. These studies provided a moderate quality of evidence to support the efficacy of cryotherapy and physical exercises in the management of AMI. There was low-quality evidence for efficacy of neuromuscular electrical stimulation and transcutaneous electrical nerve stimulation, and very low-quality evidence for efficacy of ultrasound and vibration. Conclusions: This scoping review demonstrated moderate-quality evidence for the efficacy of cryotherapy and physical exercises in improving quadriceps activation failure after ACL injury and reconstruction. These therapeutic modalities are therefore recommended in the management of AMI

How to rapidly abolish knee extension deficit after injury or surgery: a practice-changing video pearl from the Scientific Anterior Cruciate Ligament Network International (SANTI) Study Group

Knee extension deficit is frequently observed after anterior cruciate ligament reconstruction or rupture and other acute knee injuries. Loss of terminal extension often occurs because of hamstring contracture and quadriceps inactivation rather than mechanical intra-articular pathology. Failure to regain full extension in the first few weeks after anterior cruciate ligament reconstruction is a recognized risk factor for adverse long-term outcomes, and therefore, it is important to try to address it. In this technical note, a simple, rapid, and effective technique to help regain full knee extension and abolish quadriceps activation failure is described

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

Nanospintronics with carbon nanotubes

One of the actual challenges of spintronics is the realization of a spin-transistor allowing to control spin transport through an electrostatic gate. In this review, we report on different experiments which demonstrate a gate control of spin transport in a carbon nanotube connected to ferromagnetic leads. We also discuss some theoretical approaches which can be used to analyze spin transport in these systems. We emphasize the roles of the gate-tunable quasi-bound states inside the nanotube and the coherent spin-dependent scattering at the interfaces between the nanotube and its ferromagnetic contacts.Comment: 35 pages, 15 figures, some figures in gi