Spin-polarized tunneling of La0.67Sr0.33MnO3/YBa2Cu3O7-d junctions

The transport properties between ferromagnets and high-Tc superconductors are investigated in La0.67Sr0.33MnO3/YBa2Cu3O7-d (LSMO/YBCO)junctions in the geometry of cross-strip lines. The conductance spectra show zero-bias conductance peaks (ZBCP), reflecting the charge transport in the ab-plane. When an external magnetic field is applied to the junctions, the conductance spectra show two notable features, i.e., an increase of background conductance and an asymmetric ZBCP splitting whose amplitude responds nonlinearly to the applied field. It is shown that the magnetic field response are consistent with a theoretical prediction of tunneling spectroscopy when the presence of a ferromagnetic barrier between a spin-polarized ferromagnet and a d-wave superconductor is assumed.Comment: 10 Pages, 7 EPS figures, Submitted to Phys. Rev.

Casimir and van der Waals force between two plates or a sphere (lens) above a plate made of real metals

The Casimir and van der Waals forces acting between two metallic plates or a sphere (lens) above a plate are calculated accounting for the finite conductivity of the metals. The simple formalism of surface modes is briefly presented which allows the possibility to obtain the generalization of Lifshitz results for the case of two semi-spaces covered by the thin layers. Additional clarifications of the regularization procedure provides the means to obtain reliable results not only for the force but also for the energy density. This, in turn, leads to the value of the force for the configuration of a sphere (lens) above a plate both of which are covered by additional layers. The Casimir interaction between Al and Au test bodies is recalculated using the optical tabulated data for the complex refractive index of these metals. The computations turn out to be in agreement with the perturbation theory up to the fourth order in relative penetration depth of electromagnetic zero point oscillations into the metal. The disagreements between the results recently presented in the literature are resolved. The Casimir force between Al bodies covered by the thin Au layers is computed and the possibility to neglect spatial dispersion effects is discussed as a function the layer thickness. The van der Waals force is calculated including the transition region to the Casimir force. The pure non-retarded van der Waals force law between Al and Au bodies is shown to be restricted to a very narrow distance interval from 0.5 nm to (2--4) nm. New, more exact, values of the Hamaker constant for Al and Au are determined.Comment: 5 figure

Perinatal outcomes associated with combination antiretroviral therapy compared to monotherapy: systematic review and meta-analysis

Objectives: Increasing numbers of women living with HIV (WLHIV) worldwide receive combination antiretroviral therapy (cART) during pregnancy. We aimed to assess the risk of adverse perinatal outcomes in pregnant WLHIV receiving cART compared to pregnant WLHIV receiving zidovudine monotherapy. Design: Systematic review and meta-analysis. Methods: We searched four electronic literature databases (PubMed, CINAHL, Global Health, EMBASE) for studies published between 01/01/1980-20/04/2020 using a comprehensive search strategy. Studies reporting data on WLHIV receiving cART compared to WLHIV receiving monotherapy for 11 adverse perinatal outcomes were sought: preterm birth (PTB), very PTB, spontaneous PTB, low birthweight (LBW), very LBW, preterm and term LBW, small for gestational age (SGA), very SGA (VSGA), stillbirth, and neonatal death. Random-effects meta-analyses were conducted to calculate relative risk (RR) and 95% confidence intervals (95% CI). Results: We included 30 studies reporting on 317,101 women in 27 countries. WLHIV receiving cART were at increased risk of PTB (RR 1.32, 95%CI 1.18-1.46), LBW (1.35, 1.19-1.53), SGA (1.32, 1.13-1.53), VSGA (1.64, 1.34-2.02), and stillbirth (2.41, 1.83-3.17) compared to WLHIV receiving monotherapy. The significance of these results was maintained in subgroup analyses for studies conducted in low-and-middle-income countries and average quality studies. Additionally, WLHIV receiving non-nucleoside reverse transcriptase inhibitor-based cART were associated with increased risk of PTB, LBW, and stillbirth, while WLHIV receiving protease inhibitor-based cART were associated with increased risk of PTB, compared to WLHIV receiving monotherapy. Conclusion: Pregnant WLHIV receiving cART are associated with increased risk of adverse perinatal outcomes, compared to WLHIV receiving monotherapy.</p

Design and analysis of a new medial reciprocal linkage using a lower limb paralysis simulator

STUDY DESIGN: A feasibility study on the effect of a new reciprocating orthosis on specific gait parameters for use by people with spinal cord injury. OBJECTIVES: The aim of this study was to design and develop a new medial linkage orthosis (MLO) mechanism incorporating a reciprocating motion and to determine its efficacy in improving specific spatiotemporal, kinematic and kinetic parameters while ambulating when worn by healthy subjects. This was achieved via the use of a lower limb paralysis simulator (LLPS). METHODS: A reciprocating joint with a remote center of motion was designed for use as an MLO. A prototype was fabricated and incorporated into an orthosis and equipped with a saddle to make the reciprocating motion possible. The efficacy of the orthosis was evaluated on four able-bodied healthy subjects who were trained to walk with the MLO attached to the LLPS. RESULTS: Mean walking speed, stride length, stride time and cadence was 0.09±0.007 m s(-1), 0.42±0.01 m, 4.89±0.45 s and 29.54±4.32 steps min(-1), respectively, when healthy subjects walked with the new orthosis. The mean hip joint torque produced was 0.36±0.13 Nm. CONCLUSION: In this study a new MLO was designed and fabricated that provided a reciprocating mechanism using a four-bar mechanism to set the virtual axis of the mechanism in a more proximal position than hinge-type joints. Further investigation is currently underway to assess its effect on gait parameters and energy expenditure in paraplegic patients

Highly efficient on-chip direct electronic–plasmonic transducers

10.1038/s41566-017-0003-51110623-62