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1.
Guo-Quan Shi Huajun Zhu & Zhen-Guo Yan 《Communications In Computational Physics》2022,31(4):1215-1241
A priori subcell limiting approach is developed for high-order flux reconstruction/correction procedure via reconstruction (FR/CPR) methods on two-dimensional unstructured quadrilateral meshes. Firstly, a modified indicator based on
modal energy coefficients is proposed to detect troubled cells, where discontinuities
exist. Then, troubled cells are decomposed into nonuniform subcells and each subcell has one solution point. A second-order finite difference shock-capturing scheme
based on nonuniform nonlinear weighted (NNW) interpolation is constructed to perform the calculation on troubled cells while smooth cells are calculated by the CPR
method. Numerical investigations show that the proposed subcell limiting strategy on
unstructured quadrilateral meshes is robust in shock-capturing. 相似文献
2.
目的:探讨改良三点式重睑术的临床应用疗效。方法:2012年6月-2019年6月,共165例单睑患者采用了改良三点式重睑术,沿术前标记线将三点处皮肤切开,剪刀将切口下唇的眼轮匝肌适当去除,同时将切口与切口在皮下层打通,剪除切口与切口之间的眼轮匝肌,6-0可吸收线挂睑板前筋膜或提上睑肌腱膜及切口下唇皮下组织缝合,三点切口各缝1针。再用6-0单丝尼龙线按照常规重睑线缝合方法挂切口下唇皮肤、睑板前筋膜或提上睑肌腱膜及切口上唇皮肤缝合打结,三点切口各缝1针。伴内眦赘皮者同时行内眦赘皮矫正术。结果:152例患者获得随访,随访患者大部分获得了比较满意的重睑,睁眼重睑流畅、自然,闭眼刀口痕迹不明显。2例患者出现内侧重睑线变浅,1例患者出现外侧重睑线变浅,所有患者均未出现重睑消失。5例患者双侧重睑线有轻度不对称。患者总体满意率为94.7%(144/152)。结论:改良三点式重睑术具有创伤小、并发症少、效果逼真、不易脱落、手术痕迹不明显等优点,值得推广应用。 相似文献
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A typical time series in functional magnetic resonance imaging (fMRI) exhibits autocorrelation, that is, the samples of the time series are dependent. In addition, temporal filtering, one of the crucial steps in preprocessing of functional magnetic resonance images, induces its own autocorrelation. While performing connectivity analysis in fMRI, the impact of the autocorrelation is largely ignored. Recently, autocorrelation has been addressed by variance correction approaches, which are sensitive to the sampling rate. In this article, we aim to investigate the impact of the sampling rate on the variance correction approaches. Toward this end, we first derived a generalized expression for the variance of the sample Pearson correlation coefficient (SPCC) in terms of the sampling rate and the filter cutoff frequency, in addition to the autocorrelation and cross‐covariance functions of the time series. Through simulations, we illustrated the importance of the variance correction for a fixed sampling rate. Using the real resting state fMRI data sets, we demonstrated that the data sets with higher sampling rates were more prone to false positives, in agreement with the existing empirical reports. We further demonstrated with single subject results that for the data sets with higher sampling rates, the variance correction strategy restored the integrity of true connectivity. 相似文献
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6.
《Journal of Clinical Orthopaedics and Trauma》2020,11(5):956-960
Spine deformities could be considered a possible manifestation of the childhood hypotonia, typical feature of Kleefstra Syndrome (KS). There is a paucity of literature describing posterior spinal fusion in the Kleefstra syndrome patient. For patients who develop severe scoliotic curve, bracing is often ineffective and surgery is recommended. We report the first corrective surgery for scoliosis in one patient with KS.We describe a case of 13-year-old female with severe developmental scoliosis in KS. Preoperative examination showed a thoracolumbar scoliosis with left convex thoracic curve (T3-T9, 97°) and right convex thoracolumbar curve (T9-L3, 88°). Posterior correction, pedicle screw fixation and bone graft fusion T3-L5 was performed. Postoperatively, the thoracic curve was corrected to 33° while the thoracolumbar one to 26° and better standing posture was obtained. Six month follow-up images showed no loosening of the hardware. The patient is still in our follow-up program.Scoliosis seems to be a rare evenience of the severe hypotonia of patients with KS. We report the first case of scoliosis in KS treated successfully with surgery. Corrective surgery for spinal deformity, such as scoliosis, could help in posture and improve the quality of life especially in complicated patients such as syndromic ones. 相似文献
7.
As a consequence of the time-varying magnetic field induced by eddy currents, frequency drifting occurs when the sampling window of localized spectroscopy continuously shifts. The frequency drifting and the concomitant phase variations can severely affect spectroscopy results when data are acquired with multiple echo times (TEs), such as in the measurement of glutamate (Glu) concentration using the TE-averaged method. Specifically, the averaged spectra are further broadened and distorted in the presence of residual eddy currents, and editing of the coupled spins of Glu C4 protons is affected, resulting in errors in the measured relative intensity ratio. Postacquisition correction using unsuppressed water as reference can effectively minimize this detrimental effect, as manifested by the significantly enhanced signal intensity. Also, it is demonstrated that the methyl signals of creatine (Cr) at 3.0 ppm and choline (Cho) at 3.2 ppm can be used as internal references in finding frequency and phase disparities between different TEs. 相似文献
8.
目的 探索一种行之有效的、微创的乳头内陷矫正方法。方法 用钢丝、弹簧和塑料注射器制成弹性可调式的乳头内陷矫治器,利用弹性牵引作用,持续牵拉内陷乳头3~6个月。结果 14例患者均得以矫正,并获得良好的近期效果。1例患者因左侧乳头内陷严重,治疗2周时钢丝接近脱出乳头而更换矫治器并延长佩戴时间。随访患者6~12个月。效果稳定。结论 弹性可调式乳头内陷矫治器用于先天性乳头内陷的治疗,近期临床效果较好,为目前较佳的非手术治疗乳头内陷的方法,但其机理和远期效果还需进一步研究和观察。 相似文献
9.
完全型房室间隔缺损合并法洛四联症心内矫正术 总被引:2,自引:2,他引:0
目的总结心内矫正术治疗完全型房室间隔缺损合并法洛四联症(CAVSD-TOF)的经验. 方法从1985年1月至2002年5月,共行CAVSD-TOF心内矫正术12例,年龄6~16岁(11.1±2.8岁),采用右心房、右心室纵切口,前7例采用三片法补片,后5例用二片法补片修补房室间隔缺损,左侧房室瓣裂隙采用间断缝合,右心室流出道用跨瓣补片加宽. 结果术后早期死亡4例,前7例死亡3例,后5例死亡1例,死亡原因为严重低心排血量3例,灌注肺1例.长期随访6例,随访时间3个月至13.5年,无任何症状,NYHA心功能Ⅰ级或Ⅱ级. 结论 CAVSD-TOF采用右心房、右心室纵切口,二片法补片修补房室间隔缺损,常规间断缝合左侧房室瓣裂隙,跨瓣补片加宽右心室流出道能取得较良好的效果. 相似文献
10.
Ashish Raj Honglei Zhang Martin R Prince Yi Wang Ramin Zabih 《Magnetic resonance in medicine》2006,55(3):649-658
Time-resolved contrast enhanced magnetic resonance angiography (MRA) may suffer from involuntary patient motion. It is noted that while MR signal change associated with motion is large in magnitude and has smooth phase variation in k-phase, signal change associated with vascular enhancement is small in magnitude and has rapid phase variation in k-space. Based upon this observation, a novel projection onto convex sets (POCS) algorithm is developed as an automatic iterative method to remove motion artifacts. The presented POCS algorithm consists of high-pass phase filtering and convex projections in both k-space and image space. Without input of detailed motion knowledge, motion effects are filtered out, while vasculature information is preserved. The proposed method can be effective for a large class of nonrigid motions, including through-plane motion. The algorithm is stable and converges quickly, usually within five iterations. A double-blind evaluation on a set of clinical MRA cases shows that a completely unsupervised version of the algorithm produces significantly better rank scores (P=0.038) when compared to angiograms produced manually by an experienced radiologist. 相似文献