IMAGING DIAGNOSIS—MAGNETIC RESONANCE IMAGING FEATURES OF CRANIOMANDIBULAR OSTEOPATHY IN AN AIREDALE TERRIER

An Airedale Terrier was presented for evaluation of depression and reluctance to be touched on the head. Magnetic resonance (MR) imaging of the head was performed. The images revealed bone lesions affecting the calvarium at the level of the coronal suture and left mandibular ramus, with focal cortical destruction, expansion, and reactive new bone formation. Skull lesions were hypointense on T1‐weighted sequences, hyperintense on T2‐weighted sequences, and showed an intense and homogeneous enhancement after gadolinium administration. Reactive new bone formation and periosteal proliferation were confirmed histopathologically. The clinical signs, imaging findings, and histopathological examination were consistent with craniomandibular osteopathy.     

车用磁流变减振器的磁路设计

磁流变减振器磁路的设计是减振器设计中较为重要的一步,为使磁路的设计思路更加完善,对影响磁路性能的各关键问题应进行比较细致的分析。选择合理的磁路参数和设计方法决定着减振器的设计能否满足性能要求,利用有限元分析软件ANSYS对设计的磁路结构进行了仿真,结果表明设计的磁路结构满足性能要求,磁路设计方法较为合理,通过分析仿真结果可对磁路结构进一步优化,使设计的磁路结构性能得到最大的发挥。     

基于磁流变半主动悬架的振动压路机动力学与控制

在对振动压路机和磁流变减振器研究的基础上,应用磁流变减振器对振动压路机进行半主动控制,并对其进行动力学仿真研究.仿真结果表明,采用磁流变减振器进行半主动控制的振动压路机,其减振性能明显改善.     

单线圈径向流磁流变阀优化设计与性能分析

针对磁流变阀通过改变内部结构提高压降而导致阀体积增大、内部通道易阻塞的问题,在不改变普通单线圈径向流磁流变阀内部基本结构及外观尺寸的基础上,对单线圈径向流磁流变阀压降与压降可调系数进行了多目标优化,设计了一种带有隔磁套筒的单线圈径向流磁流变阀,并阐述了其工作原理,基于Bingham模型推导了其压降数学模型。采用有限元法建立了磁流变阀二维仿真模型,观察径向圆盘阻尼间隙处磁感应强度分布规律,建立约束条件,分析了磁流变阀关键部件尺寸对剪切屈服应力与压降等相关性能的影响。运用ANSYS零阶和一阶优化工具对磁流变阀进行几何尺寸参数优化,并对优化前后磁流变阀有效阻尼间隙处的平均磁感应强度,以及进出口压降进行仿真对比分析。在磁流变阀动态性能测试平台上,对优化前后磁流变阀压降性能进行实验测试对比,实验结果表明,当励磁电流为1. 8 A时,优化前磁流变阀压降为1. 84 MPa,优化后磁流变阀压降为2. 58 MPa,增加了40. 22%;优化前磁流变阀压降可调系数为7. 94,优化后压降可调系数为10. 07,增加了26. 83%;不同负载对磁流变阀压降效果影响不大。     

树突状细胞甘露糖受体在旋毛虫感染中的变化研究

应用流式细胞术(FCM)检测旋毛虫感染后小鼠肠系膜淋巴结(MLN)中树突状细胞(DC)上甘露糖受体(MR)的影响。培养小鼠骨髓源树突状细胞(BMDC)并负载旋毛虫排泄/分泌抗原(ES抗原),FCM检测BMDC上MR的变化情况。结果显示,感染第7天MLN中DC表面MR出现下调,但在14 d后出现上调,差异显著(P0.05)。体外实验发现,BMDC负载ES抗原后MR出现下调,直到第48小时出现上调,差异显著(P0.05)。本研究证明旋毛虫感染后可以引起树突状细胞上MR的变化,表明MR可能是ES抗原的识别受体。这为研制旋毛虫树突状细胞疫苗提供了支持,并对寄生虫免疫逃避机制的研究提供了思路。     

美国《数学评论》光盘版2004年收录中国高校学报统计

利用美国《数学评论》2004年光盘，对其收录的90余种中国高校学报进行了检索统计．结果表明：2004年总计收录1858条，江苏、山东、北京和上海为入选期刊数最多的省市，收录量列前3住的依次是四川、山东和江苏。其中四川大学学报（0490—6756）收录量最多，为87条，四川师范大学学报自然科学版（1001-8395）收录76条，为师范大学学报收录最多的期刊。     

DETERMINATION OF T1 RELAXATION TIME OF NORMAL EQUINE TENDONS USING MAGIC ANGLE MAGNETIC RESONANCE IMAGING

Seven isolated equine front limbs were used to establish the normal T1 relaxation time of equine superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), and suspensory ligament (SL) using magic angle magnetic resonance (MR) imaging. MR imaging of the metacarpi was performed with the limbs positioned at 55° (the magic angle) relative to the main magnetic field. Transverse spin‐echo proton density and inversion recovery images were acquired. T1 relaxation time was calculated based on ratios of signal intensity determined from the different pulse sequences. T1 relaxation times for SDFT, DDFT, and SL were 288 (±17), 244 (±14), and 349 (±16) ms, respectively. The difference in T1 values between SDFT, DDFT, and SL was statistically significant. T1 values of equine tendons can be determined with magic angle imaging on a clinical MR system using <10 min total scan time. The knowledge of the normal range of T1 values may be useful to identify horses with chronic tendinopathy, where based on the human literature, an increased T1 value may be expected.     

EVALUATION OF MAGNETIC RESONANCE SAFETY OF VETERINARY RADIOFREQUENCY IDENTIFICATION DEVICES AT 1 T

Implants containing metallic components have the potential to become heated or move within the patient while in the magnetic resonance (MR) environment. Despite containing a ferromagnetic core and having been in use for over 20 years, no information is available on the safety of veterinary radiofrequency identification devices during MR examinations. These devices are the most commonly encountered metallic implants in dogs and cats undergoing MR imaging. Three commercial veterinary microchips were evaluated for safety in the MR environment at 1 T. Parameters tested were translational force, torque, heating, artifact production, and function. Translation and torque were larger than that expected from normal activity under normal gravity. No significant heating was observed. Signal void artifacts may affect diagnosis if they are too close to the area of clinical importance. Microchip function was unaffected by routine clinical MR imaging. Capsule formation around devices is a major factor in counteracting translation and torque. Our findings support that is acceptable for patients to undergo MR imaging with this 1 T system following an interval of 3 months postimplantation to allow capsule growth. Because of the complex interactions involved, these observations may not be translatable to MR scanners of different field strength and/or manufacturer. Further safety testing of these and other radiofrequency identification devices is therefore recommended at different field strengths and equipment specifications.     

MAGNETIC RESONANCE IMAGING OF PULP IN NORMAL AND DISEASED EQUINE CHEEK TEETH

A retrospective analysis of 619 upper and lower cheek teeth from 62 horses was performed. Based on clinical findings, as well as radiographic and magnetic resonance (MR) imaging findings, the teeth were classified into five groups. There were 20 teeth with abnormal MR imaging signals as well as clinical alterations and 599 healthy teeth. Using MR imaging, the appearance of pulp in diseased and disease‐free teeth was compared, and the appearance of abnormal pulp was studied. Subsequently, the ability of MR imaging to diagnose pulpitis and pulp necrosis in teeth with normal external appearance was investigated. In horses with clinically verified dental disease, abnormal MR imaging findings were confirmed in the pulp of all affected teeth. An enlarged blurred pulp image with a lower signal intensity was observed only in clinically diseased teeth and was a reliable criterion for diagnosing dental disease on MR imaging. On the other hand, partial or complete absence of pulp in all MR imaging sequences was observed in both diseased and nondiseased teeth. These data demonstrate that pulp changes in equine cheek teeth can be evaluated using MR imaging.     

四元数矩阵的中心化子

推广了数域上的矩阵中心化子理论,得到了实四元数体矩阵上的中心化子理论。