Directional $\mathcal{H}^2$ Compression Algorithm: Optimisations and Application to a Discontinuous Galerkin BEM for the Helmholtz Equation

This study aimed to specialise a directional $\mathcal{H}^2 (\mathcal{D}\mathcal{H}^2)$ compression to matrices arising from the discontinuous Galerkin (DG) discretisation of the hypersingular equation in acoustics. The significant finding is an algorithm that takes a DG stiffness matrix and finds a near-optimal $\mathcal{D}\mathcal{H}^2$ approximation for low and high-frequency problems. We introduced the necessary special optimisations to make this algorithm more efficient in the case of a DG stiffness matrix. Moreover, an automatic parameter tuning strategy makes it easy to use and versatile. Numerical comparisons with a classical Boundary Element Method (BEM) show that a DG scheme combined with a $\mathcal{D}\mathcal{H}^2$ gives better computational efficiency than a classical BEM in the case of high-order finite elements and $hp$ heterogeneous meshes. The results indicate that DG is suitable for an auto-adaptive context in integral equations.     

A New Asymmetric Directional Microphone Algorithm With Automatic Mode‐Switching Ability for Binaural Hearing Support Devices

For hearing support devices, it is important to minimize the negative effect of ambient noises for speech recognition but also, at the same time, supply natural ambient sounds to the hearing‐impaired person. However, conventional fixed bilateral asymmetric directional microphone (DM) algorithms cannot perform in such a way when the DM‐mode device and a dominant noise (DN) source are placed on the same lateral hemisphere. In this study, a new binaural asymmetric DM algorithm that can overcome the defects of conventional algorithms is proposed. The proposed algorithm can estimate the position of a specific DN in the 90°–270° range and switch directional‐ and omnidirectional‐mode devices automatically if the DM‐mode device and the DN are placed in opposite lateral hemispheres. Computer simulation and KEMAR mannequin recording tests demonstrated that the performance of the conventional algorithm deteriorated when the DM‐mode device and the DN were placed in the opposite hemisphere; in contrast, the performance of the proposed algorithm was consistently maintained regardless of directional variations in the DN. Based on these experimental results, the proposed algorithm may be able to improve speech quality and intelligibility for hearing‐impaired persons who have similar degrees of hearing impairment in both ears.     

系统性护理干预对乳腺微创旋切术患者心理及康复情况的影响分析

目的:探究系统性护理干预对乳腺微创旋切术患者心理状态及康复情况的影响。方法:将120例接受乳腺微创旋切术治疗的患者随机分为观察组(60例)和对照组(60例)。对照组采用常规护理干预,观察组采用系统性护理干预。比较两组患者术后疼痛、心理状态、并发症发生情况及对护理的满意度。结果:观察组护理满意度96.67%显著高于对照组的80.00%,观察组并发症发生率6.67%显著低于对照组的30.00%,差异有统计学意义(P<0.05)。观察组术后2h、6h、12h、24h的疼痛数字等级评定量表(Numerical rating scale,NRS)评分低于对照组,且观察组抑郁自评量表(Self-rating depression scale,SDS)评分、焦虑自评量表(Self-rating anxiety scale,SAS)评分均低于对照组,依从性评分显著高于对照组,差异有统计学意义(P<0.05)。结论:系统性护理干预在乳腺微创旋切术中应用效果良好,可有效降低并发症发生率,减轻患者疼痛及负性心理,提高其依从性及护理满意度,值得临床推广应用。     

Lower Extremity Revascularization Using Directional Atherectomy: 12-Month Prospective Results of the DEFINITIVE LE Study

ObjectivesThe aim of this study was to assess the safety and effectiveness of directional atherectomy (DA) for endovascular treatment of peripheral arterial disease (PAD) in infrainguinal arteries in patients with claudication or critical limb ischemia.BackgroundTo date, no prospective, multicenter, independently-adjudicated study has evaluated the effectiveness and durability of DA in the treatment of PAD. Previous DA studies have not been prospectively powered to evaluate any differences in outcomes in patients with and without diabetes.MethodsDEFINITIVE LE (Determination of EFfectiveness of the SilverHawk® PerIpheral Plaque ExcisioN System (SIlverHawk Device) for the Treatment of Infrainguinal VEssels / Lower Extremities) prospectively enrolled subjects at 47 multinational centers with an infrainguinal lesion length up to 20 cm. Primary endpoints were defined as primary patency at 12 months for claudicants and freedom from major unplanned amputation for critical limb ischemia (CLI) subjects. A pre-specified statistical hypothesis evaluated noninferiority of primary patency in diabetic versus nondiabetic claudicants. Independent angiographic and sonographic core laboratories assessed outcomes, and events were adjudicated by a clinical events committee.ResultsA total of 800 subjects were enrolled. The 12-month primary patency was 78% (95% confidence interval: 74.0% to 80.6%) in claudicants, with a 77% rate in the diabetic subgroup versus 78% in the nondiabetic subgroup (noninferior, p < 0.001). The rate of freedom from major unplanned amputation of the target limb at 12 months in CLI subjects was 95% (95% confidence interval: 90.7% to 97.4%). Periprocedural adverse events included embolization (3.8%), perforation (5.3%), and abrupt closure (2.0%). The bail-out stent rate was 3.2%.ConclusionsThe DEFINITIVE LE study demonstrated that DA is a safe and effective treatment modality at 12 months for a diverse patient population with either claudication or CLI. Furthermore, DA was shown to be noninferior for treating PAD in patients with diabetes compared with those without diabetes. (Study of SilverHawk/TurboHawk in Lower Extremity Vessels [DEFINITIVE LE]; NCT00883246).     

基于混合多特征的微动脉瘤检测方法

糖尿病性视网膜病变(DR)会严重损害糖尿病患者的视力健康,而微动脉瘤(MA)是DR的早期迹象,可为DR早期诊断提供有益信息,然而仅凭肉眼靠经验观察眼底图像,对大规模筛查难以胜任。因此自动识别和检测势在必行。应用自适应阈值分割法提取候选区域,设计联合定向局部对比度特征(DLC)与哈尔特征(Haar)等混合多特征向量,通过邻近算法(KNN)实现自动分类,并与其他机器学习的常用分类方法,如朴素贝叶斯(NB)、支持向量机(SVM)以及同方向进行了对比研究。所提出的方法在e-ophtha MA公开数据集上进行测试,获得的ROC曲线线下面积(AUC)、敏感性、特异性、FROC-Score分别为0.961 3、0.914 4、0.890 0和 0.386 0。与其他方法比较,本方法在FROC曲线上取得最优结果。     

特殊器械在冠心病介入诊疗中的应用价值

目的:分析评价特殊器械在冠心病介入诊疗中的应用价值.方法:分析328例冠心病介入诊疗患者病例资料,记录包括抽吸导管、冠脉旋磨、血管内超声显像(IVUS)、冠脉血流储备测定(FFR)及主动脉内气囊反搏(IABP)等特殊器械在各类冠心病患者的使用情况,观察使用最多的特殊器械在主要冠脉血管病变使用情况及特殊器械使用中发生慢血流、心包填塞及死亡情况.结果:特殊器械中抽吸导管使用率最高(62.5％),其余依次为IVUS(15.0％)、FFR(14.3％)、冠脉旋磨(6.4％)及IABP(1.8％);在使用率最高的血栓抽吸导管应用中,前降支病变使用率最高(42.4％),其余依次为右冠脉部位占38.1％、回旋支病变占18.6％、左主干病变占1.0％;使用血栓抽吸导管患者中4例发生慢血流情况,占特殊器械使用的(1.2％);冠脉旋磨中有1例发生心包填塞,占特殊器械使用的(0.3％).结论:在冠心病诊疗中有选择的开展特殊器械的应用可提高冠心病介入诊疗水平.     

Real‐time multi‐directional flow MRI using model‐based reconstructions of undersampled radial FLASH – A feasibility study

The purpose of this work was to develop an acquisition and reconstruction technique for two‐ and three‐directional (2d and 3d) phase‐contrast flow MRI in real time. A previous real‐time MRI technique for one‐directional (1d) through‐plane flow was extended to 2d and 3d flow MRI by introducing in‐plane flow sensitivity. The method employs highly undersampled radial FLASH sequences with sequential acquisitions of two or three flow‐encoding datasets and one flow‐compensated dataset. Echo times are minimized by merging the waveforms of flow‐encoding and radial imaging gradients. For each velocity direction individually, model‐based reconstructions by regularized nonlinear inversion jointly estimate an anatomical image, a set of coil sensitivities and a phase‐contrast velocity map directly. The reconstructions take advantage of a dynamic phase reference obtained by interpolating consecutive flow‐compensated acquisitions. Validations include pulsatile flow phantoms as well as in vivo studies of the human aorta at 3 T. The proposed method offers cross‐sectional 2d and 3d flow MRI of the human aortic arch at 53 and 67 ms resolution, respectively, without ECG synchronization and during free breathing. The in‐plane resolution was 1.5 × 1.5 mm² and the slice thickness 6 mm. In conclusion, real‐time multi‐directional flow MRI offers new opportunities to study complex human blood flow without the risk of combining differential phase (i.e., velocity) information from multiple heartbeats as for ECG‐gated data. The method would benefit from a further reduction of acquisition time and accelerated computing to allow for extended clinical trials.