Yonsei University

About: Yonsei University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Population & Cancer. The organization has 50162 authors who have published 106172 publications receiving 2279044 citations. The organization is also known as: Yonsei.

Recurrent lumbar disc herniation : Results of operative management

Abstract: Study Design. A retrospective evaluation of 28 patients with recurrent lumbar disc herniation. Objectives. To analyze the outcome of the revisions (repeat discectomy), the risk factors of recurrent disc herniation, and the factors that influenced the outcomes of repeat discectomy. Summary of Background Data. Recurrent herniation following disc excision has been reported in 5–11% of patients. There have been many studies on recurrent disc herniation, but these studies have analyzed mixed patient populations. Methods. Recurrent lumbar disc herniation was defined as disc herniation at the same level, regardless of ipsilateral or contralateral herniation, with a pain-free interval greater than 6 months. Eight women and 20 men were studied. The levels of disc herniation were L4–L5 (19 cases) and L5–S1 (9 cases). Gadolinium-enhanced magnetic resonance imaging was performed in all patients. Revision surgery was performed in all patients by using conventional open discectomy. The pain-free interval, side and degree of herniation, operation time, duration of hospital stay, and clinical improvement rate were recorded. Results. The mean pain-free interval was 60.8 months. There were 21 cases of ipsilateral herniation and 7 cases of contralateral herniation. The degrees of herniation in revision were protrusion (14 cases), subligamentous extrusion (3 cases), transligamentous extrusion (8 cases), and sequestration (3 cases). The degrees of herniation in the previous discectomy were protrusion (17 cases), subligamentous extrusion (10 cases), and transligamentous extrusion (1 case). The length of surgery was significantly different (P = 0.003) between the revision surgery and the previous discectomy. There were no significant differences between revision and previous surgery in terms of hospital stay or clinical improvement rates. Age, gender, smoking, professions, traumatic events, level and degree of herniation, and pain-free interval did not affect the clinical outcomes. Conclusion. Conventional open discectomy as a revision surgery for recurrent lumbar disc herniation showed satisfactory results that were comparable with those of primary discectomy. Based on the results of this study, repeat discectomy can be recommended for the management of recurrent lumbar disc herniation.

Suppression Pattern of Neutral Pions at High Transverse Momentum in Au plus Au Collisions at root S-NN=200 GeV and Constraints on Medium Transport Coefficients

Abstract: For Au + Au collisions at 200 GeV, we measure neutral pion production with good statistics for transverse momentum, p(T), up to 20 GeV/c. A fivefold suppression is found, which is essentially constant for 5 in the parton quenching model. The spectral shape is similar for all collision classes, and the suppression does not saturate in Au + Au collisions.

Interference mitigation using uplink power control for two-tier femtocell networks

Abstract: This paper proposes two interference mitigation strategies that adjust the maximum transmit power of femtocell users to suppress the cross-tier interference at a macrocell base station (BS). The open-loop and the closed-loop control suppress the cross-tier interference less than a fixed threshold and an adaptive threshold based on the noise and interference (NI) level at the macrocell BS, respectively. Simulation results show that both schemes effectively compensate the uplink throughput degradation of the macrocell BS due to the cross-tier interference and that the closed-loop control provides better femtocell throughput than the open-loop control at a minimal cost of macrocell throughput.

Flexible polymeric dry electrodes for the long-term monitoring of ECG

Abstract: In this paper, we present a novel polymeric dry electrode that (1) changes its shape in a way that supports the electrode's contact with the skin and (2) that does not cause skin irritations or allergic reactions For a polymeric substrate of electrodes, we have used the elastomer poly(dimethylsiloxane), which is known to be inexpensive, biocompatible, and amenable to micro-molding, and to have excellent gas and water permeability We have established a process by which one can deposit a metal layer on the PDMS substrate, etch the electrode patterns chemically and with good resolution, and package the electrode so that it is easily wearable on the forearm We measured the impedance according to the frequency change and compared the results with those of Ag/AgCl electrodes Afterward, we measured the ECG signal and investigated possible artifacts caused by motion For the feasibility of long-term monitoring, we examined the influence of surface electrodes on the skin after 7 days of ECG monitoring In conclusion, our PDMS-based dry electrode measured the ECG signals with comparatively good fidelity, but showed better skin compatibility after long-term tests We expect that our method for the production of PDMS-based dry electrodes will be broadly applicable to the field of ubiquitous biosignal monitoring