137 research outputs found

    Three Patterns Programmable Russian Form Functional Electrical Stimulator

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    In this paper, a programmable, multi-pattern, wide frequency and duty cycle range electrical stimulator is presented. Using a programmable micro-controller, two waves of carrier and modulating sources are produced. By modulating the two sources, 3 bi-phasic charge-balanced rectangular, triangular and sinusoidal stimulating patterns are produced. The frequency range of the carrier is fixed at 2.5 kHz and the carrier source frequency can be adjusted between 1 and 500 Hz. The duty cycle of both sources can be adjusted between 10% and 90%

    Effect of pressure on single-chain magnets with repeating units of the MnIII-NiII-MnIII trimer

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    The single-chain magnet (SCM) system [Mn2(saltmen)2Ni(pao)2(L)2](A)2 (L: intrachain attaching ligand of NiII ion; A-1: interchain counteranion) is a ferromagnetic one-dimensional network system with repeating units of the MnIII-NiII-MnIII trimer which itself behaves as a single-molecule magnet with an S=3 spin ground state and negative uniaxial single-ion anisotropy (D) parallel to the bridging direction. The slow relaxation of the magnetic moment in this SCM system originates in an energy barrier for spin reversal (ΔE), which is closely related to the ferromagnetic interaction between the trimers (Jtrimer) as well as to the D of the trimer. We have investigated the effects of pressure on three compounds representative of the above SCM family through ac susceptibility measurements under hydrostatic pressures up to P=13.5 kbar and crystal structural analysis experiments up to P=20.0 kbar, and have observed a pronounced enlargement of ΔE when J was artificially increased. The application of hydrostatic pressure brought about the systematic enhancement of EΔ (a maximum increase of 10% within the pressure region of the experiments). The pressure dependence of EΔ varied according to the kind of attaching ligand L involved and the intrachain structure, and we have experimentally found that isotropic lattice shrinkage is desirable if a continuous increase of ΔE in this system is aimed at

    Spin correlation and relaxational dynamics in molecular-based single-chain magnets

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    We report the combined measurements of the dc susceptibility X0, the ac susceptibility X, and the NMR relaxation rate T for the molecular-based heterometallic single-chain magnet [Mn(saltmen)]2[Ni(pao)2(py)2](PF6)2. At low temperatures, this system is well described by a one-dimensional array of effective spin S=3 chains comprising the MnIII-NiII-MnIII trimers and treated as the S=3 Ising chain with the single-ion term (Blume-Capel model). Using the exact solution of the model and based on the picture that the random motion of the local domain walls dominates the low-temperature spin dynamics, we succeeded in reproducing the experimental results of the dc susceptibility X0, the ac susceptibility X, and the 19F-NMR relaxation rate T in a consistent manner

    Spin correlation and relaxational dynamics in molecular-based single-chain magnets

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    We report the combined measurements of the dc susceptibility 0, the ac susceptibility , and the NMR relaxation rate T for the molecular-based heterometallic single-chain magnet [Mn(saltmen)]2[Ni(pao)2(py)2](PF6)2. At low temperatures, this system is well described by a one-dimensional array of effective spin S=3 chains comprising the MnIII-NiII-MnIII trimers and treated as the S=3 Ising chain with the single-ion term (Blume-Capel model). Using the exact solution of the model and based on the picture that the random motion of the local domain walls dominates the low-temperature spin dynamics, we succeeded in reproducing the experimental results of the dc susceptibility 0, the ac susceptibility , and the 19F-NMR relaxation rate T in a consistent manner

    鎖骨下動脈閉塞性動脈硬化症に対する血管内超音波評価を併用したステント留置術の長期治療成績

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    The objective of this study was to determine long-term outcomes after stent placement for subclavian artery (SA) obstructive lesions assisted by intraoperative intravascular ultrasound (IVUS). The study included 25 lesions in 24 patients who underwent stent placement assisted by intraoperative IVUS for subclavian artery stenosis or obstruction at our hospital between January 2003 and August 2010. Outcome was evaluated based on the results within 30 postoperative days (technical success rate, improvement in upper extremity ischemia, steal syndrome, left-right blood pressure difference, and perioperative complications) and the results after 30 postoperative days (incidence of vertebrobasilar artery territory infarction and restenosis). Stent placement and vessel dilatation were successful in all patients, without perioperative complications. Upper extremity ischemia, steal syndrome, and left-right blood pressure difference disappeared in all cases. During follow-up observation (6-96 months; median 51 months), no restenosis occurred at the stent placement site in any patient. In one case, four years after initial treatment, stenosis was noted proximal to the stent placement site. Satisfactory long-term as well as short-term outcomes were achieved after stent placement for SA obstructive lesions assisted by intraoperative IVUS evaluation.博士(医学)・乙第1362号・平成27年5月28日Copyright © 2014 by SAGE Publications. The definitive version is available at " http://dx.doi.org/10.15274/NRJ-2014-10023

    不安定プラークを伴った頚動脈狭窄症に対するクローズセルステントを用いたステントインステント法による頚動脈ステント留置術

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    Purpose: To examine whether carotid artery stenting (CAS) of stenoses with unstable plaque using a closed-cell stent-in-stent technique prevents plaque protrusion. Materials and Methods: Between December 2014 and August 2018, 35 consecutive patients (mean age 75.8 years; 29 men) with carotid artery stenosis (20 symptomatic) and unstable plaque diagnosed by magnetic resonance imaging were prospectively analyzed. Mean diameter stenosis was 83.5%. All CAS procedures were performed with stent-in-stent placement of Carotid Wallstents using an embolic protection device and conservative postdilation. The technical success rate, incidence of plaque protrusion, ischemic stroke rate within 30 days, and new ipsilateral ischemic lesions on diffusion-weighted imaging (DWI) within 48 hours after CAS were prospectively assessed. Follow-up outcomes included the incidences of ipsilateral stroke and restenosis. Results: The technical success rate was 100%. No plaque protrusion or stroke occurred in any patient. New ischemic lesions were observed on DWI in 10 (29%) patients. During the mean 11.6-month follow-up, no ipsilateral strokes occurred. Two (6%) patients developed asymptomatic restenosis recorded as 53% lumen narrowing and occlusion, respectively. Conclusion: CAS using a closed-cell stent-in-stent technique for unstable plaque may be useful for preventing plaque protrusion and ischemic complications.博士(医学)・乙第1444号・令和元年12月5日This is a non-final version of an article published in final form in "https://doi.org/10.1177/1526602819847698

    Application of susceptibility weighted imaging (SWI) for evaluation of draining veins of arteriovenous malformation: utility of magnitude images.

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    INTRODUCTION: The current study evaluated the signal characteristics of susceptibility weighted imaging (SWI) of arteriovenous malformation (AVM), especially for draining veins. For this purpose, we identified the draining veins of the AVM on angiography and evaluated the signal on magnitude image for SWI (SWI-mag) and minimum intensity projection image (SWI-minIP). METHODS: Subjects were 14 cases with angiographically proven AVM. SWI-mag, SWI-minIP, and time-of-flight (TOF) magnetic resonance angiography were acquired. For the draining veins of the AVM identified on angiography, we analyzed signal intensity on the images listed above, and classified it into hyperintensity (hyper), mixed intensity (mixed), hypointensity (hypo), and no visualization. RESULTS: On the analysis of 27 angiographically proven draining veins, 19 draining veins were classified as hyper, 3 as mixed, 0 as hypo, and 6 as no visualization on SWI-mag. On TOF images, 21 draining veins were classified as hyper, 2 as mixed, 0 as hypo, and 4 as no visualization, while 6 draining veins did not show hyperintensity on TOF, and SWI-mag visualized 3 of these 6 veins as hyper. CONCLUSION: SWI-mag depicted most draining veins of AVM as hyperintensity. We speculate that this is mainly due to the higher concentration of oxygenated hemoglobin (oxy-Hb) and inflow effect of the draining vein. SWI-mag seems to be useful in the analysis and follow-up for AVM as the signal on the image may reflect physiological status.博士(医学)・乙第1316号・平成25年7月22
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