675 research outputs found

    Distribution of the magnetization reversal duration in sub-ns spin-transfer switching

    Full text link
    We study the distribution of switching times in spin-transfer switching induced by sub-ns current pulses in pillar-shaped spin-valves. The pulse durations leading to switching follow a comb-like distribution, multiply-peaked at a few most probable, regularly spaced switching durations. These durations reflect the precessional nature of the switching, which occurs through a fluctuating integer number of precession cycles. This can be modeled considering the thermal variance of the initial magnetization orientations and the occurrence of vanishing total torque in the possible magnetization trajectories. Biasing the spin-valve with a hard axis field prevents some of these occurrences, and can provide an almost perfect reproducibility of the switching duration.Comment: submitted to PR

    Induced sensorimotor brain plasticity controls pain in phantom limb patients

    Get PDF
    The cause of pain in a phantom limb after partial or complete deafferentation is an important problem. A popular but increasingly controversial theory is that it results from maladaptive reorganization of the sensorimotor cortex, suggesting that experimental induction of further reorganization should affect the pain, especially if it results in functional restoration. Here we use a brain-machine interface (BMI) based on real-time magnetoencephalography signals to reconstruct affected hand movements with a robotic hand. BMI training induces significant plasticity in the sensorimotor cortex, manifested as improved discriminability of movement information and enhanced prosthetic control. Contrary to our expectation that functional restoration would reduce pain, the BMI training with the phantom hand intensifies the pain. In contrast, BMI training designed to dissociate the prosthetic and phantom hands actually reduces pain. These results reveal a functional relevance between sensorimotor cortical plasticity and pain, and may provide a novel treatment with BMI neurofeedback.This research was conducted under the ‘Development of BMI Technologies for Clinical Application’ of SRPBS by MEXT and AMED. This research was also supported in part by JST PRESTO; JSPS KAKENHI JP24700419, JP26560467, JP22700435, JP26242088, JP26282165, JP15H05710 and JP15H05920; Brain/MINDS and SICP from AMED; ImPACT; Ministry of Health, Labor, and Welfare (18261201); and the Japan Foundation of Aging and Health

    Search for Λ6^6_\LambdaH hypernucleus by the 6^6Li(π,K+)(\pi^-,K^+) reaction at pπp_{\pi^-} = 1.2 GeV/cc

    Get PDF
    We have carried out an experiment to search for a neutron-rich hypernucleus, Λ6^6_{\Lambda}H, by the 6^6Li(π,K+\pi^-,K^+) reaction at pπp_{\pi^-} =1.2 GeV/cc. The obtained missing mass spectrum with an estimated energy resolution of 3.2 MeV (FWHM) showed no peak structure corresponding to the Λ6^6_{\Lambda}H hypernucleus neither below nor above the Λ4^4_{\Lambda}H+2n+2n particle decay threshold. An upper limit of the production cross section for the bound Λ6^6_{\Lambda}H hypernucleus was estimated to be 1.2 nb/sr at 90% confidence level.Comment: 6 pages, 5 figures, published versio
    corecore