激光全息干涉在三维温度场可视化中的应用

介绍了实时激光全息干涉技术应用于三维温度场可视化的原理、实验装置与光路系统、实验结果等。通过实验成功地实现了3 种条件下三维温度场的可视化,定性地获得了溶液加热后内部温度的变化规律,并观测到溶液受热的初始阶段存在随时间迁移的“蘑菇”形干涉条纹。     

Far-Infrared Optics Design & Verification

Compact quasi-optics are difficult to design with any confidence using techniques developed for visible wavelengths. In this paper we investigate the performance of existing software design tools (ASAP, CODE V, GLAD) as well as a Gaussian beam mode analysis technique not yet available as commercial software. We have devised a set of test cases and used these to study the underlying methodologies and physics of these packages and we probe their suitability for the analysis of submillimetre-wave systems and components. We have used the physical optics package GRASP as our benchmark software.     

Linogram reconstruction for magnetic resonance imaging (MRI)

Reconstruction of magnetic resonance images (MRIs) by backprojection, which commonly uses techniques analogous to those employed for X-ray computed tomography, is discussed. The recently developed method of linogram reconstruction, an alternative to conventional/backprojection methods of reconstruction from projections, has been adapted for MRI, taking advantage of MRI's flexibility in choosing projection geometry. By avoiding the computationally intensive interpolations required for backprojection, linograms offer significant savings in reconstruction time over conventional backprojection and may offer a slight improvement in resolution as well.     

Reconstructions from a Nonstandard CT Scanner

A position sensitive detector of novel design has been developed to permit CT information to be obtained using a radiotherapy simulator. The scanner has been engineered to obtain the outline of high contrast internal anatomy such as lung tissue and external body contour for the purpose of assisting radiation treatment planning including inhomogeneity corrections. The mode of operation of the scanner is described and the novel reconstruction problem presented by this scanner is discussed. Clinical images are shown which illustrate the usefulness of this scanner in assisting in the conservative management of patients receiving postoperative radiotherapy for breast cancer.     

ADI新一代高速互连串行总线及其目标应用

互连设计师正从同步并行总线转移到点对点高速串行链接(带嵌入式时钟和数据).这种转移使很多通信系统设计人员想知道在串行和并行互连之间进行选择时如何折衷考虑.本文通过详细分析新一代高速互连串行总线和其目标应用给出了答案.     

Cascade position control of a single pneumatic artificial muscle–mass system with hysteresis compensation

The inherent hysteresis in a pneumatic artificial muscle (PAM) makes it difficult to control accurately the position of the PAM’s end effector. This hysteresis causes energy loss and the area of the hysteresis loop is dependent on the amplitude of the motion and on the underlying causes of the hysteresis phenomenon. This means that if the hysteresis energy loss is properly compensated, a more accurate positioning would be achieved. In this paper, the pressure/length hysteresis of a single PAM is modeled by using a Maxwell-slip model. The obtained model is used in the feedforward path of a cascade position control scheme, in which the inner loop is designed to cope with the nonlinearity of the pressure buildup inside the PAM, whereas the outer loop is designed to cope with the nonlinearity of the PAM dynamics itself. The experimental results show that position control of a single PAM–mass system with hysteresis compensation (HC) is effectively improved compared to a control without HC, and the control system shows high robustness to load changes.     

Group Delay Enhancement in Circular Arrays of Microring Resonators

Circular arrays of microring resonators are proposed for enhancing the group delay of slow-wave microring lattice structures. Large peak delay enhancements can be obtained and dynamically tuned by simply varying the loop coupling coefficient. It is also shown that maximally flat group delay responses can be achieved in these structures for potential application in compact dispersionless optical delay elements.     

Rotation-Vibration Constants for the nu1, nu22, nu24, nu22 + nu24, and Ground States in Pyrrole (12C4H5N)

We have recorded the infrared absorption spectrum of pyrrole at 0.005 cm-1 spectral resolution using a Fourier transform interferometer. The rotational analysis of the symmetric out-of-plane C-H bend 22(1)0 fundamental band at 722.132993(5) cm-1 was performed, allowing 6760 lines to be assigned. These lines were fitted simultaneously to literature data on nu1 [A. Mellouki, R. Georges, M. Herman, D. L. Snavely, and S. Leytner, Chem. Phys. 220, 311-322 (1997)] and microwave lines [G. Wlodarczak, L. Martinache, J. Demaison, and B. P. Van Eijck, J. Mol. Spectrosc. 127, 200-208 (1988)]. A set of rotation parameters was determined for the ground state in Ir and IIIr representations, together with vibration-rotation constants for the v1 = 1 and v22 = 1 vibrational states. The fine structure in the strongest of the hot bands in that range was highlighted by division, from the experimental data, of the spectrum of the 22(1)0 band, computed using the vibration-rotation parameters. The rotational assignment of 930 lines in the strongest hot band was performed. The 22(1)024(1)1 vibrational assignment is proposed, leading to x22,24 = 1.90 cm-1. The transition dipole matrix element for the 22(1)0 band is estimated to || || = 2 x 10(-4) D. Copyright 1999 Academic Press.     

Long-term follow-up of juvenile nasopharyngeal angiofibromas: analysis of recurrences

BACKGROUND AND PURPOSE: The chronic phase of vasospasm after an aneurysmal subarachnoid hemorrhage may be mediated in part by early leukocyte-endothelial cell interactions. Ibuprofen is an anti-inflammatory agent that inhibits expression of certain cell adhesion molecules and therefore disrupts leukocyte-endothelial cell interactions. Its systemic administration, however, has dose-limiting side effects. We evaluated the effect of the periadventitial delivery of ibuprofen using controlled-release polymers in the rat femoral artery model of chronic posthemorrhagic vasospasm. METHODS: Before the animal studies, the release pharmacokinetics of the ibuprofen-loaded ethylene-vinyl acetate polymers were determined in vitro. Subsequently, the femoral arteries (n=266) of Fischer 344 rats (n=133) were enclosed in latex pouches bilaterally. In the toxicity study (n=15 rats), the animals were randomized into 5 dose groups in which 0%-, 10%-, 20%-, 30%-, or 50%-loaded ibuprofen polymers were evaluated. In the efficacy study, the animals were randomized into 5 time groups in which 50%-loaded ibuprofen polymers were inserted at 0 (n=58 rats), 6 (n=16), 12 (n=13), 24 (n=11), or 48 hours (n=12) after blood injection into the pouch. The rats were killed 12 days after blood exposure, at the time of maximal vasospasm in this model. Vasospasm was expressed as percent lumen patency. To evaluate the effect of ibuprofen on leukocyte migration, 8 rats were randomized into 2 groups. Macrophages and granulocytes were stained by immunohistochemistry with the use of a mouse OX-41 monoclonal antibody and counted in the periadventitial space 24 hours after blood exposure. RESULTS: In vitro pharmacokinetics showed that the 50%-loaded ibuprofen polymer released its total drug load over a 12-day period. In the toxicity study, a nonsignificant arterial vasodilatation with ibuprofen treatment was seen at higher doses, and no deleterious effects were noted on the vessel wall histologically. In the efficacy study, ibuprofen treatment resulted in significant vasospasm inhibition when treatment was initiated at 0 hour (73.7+/-4.9% versus 94.5+/-3.3% [mean+/-SEM percent lumen patency]; P<0.001) and 6 hours (69.2+/-5.7% versus 98.0+/-3.9%; P=0. 002) after blood exposure, but not at 12, 24, or 48 hours. Leukocyte immunohistochemistry showed that ibuprofen treatment resulted in significantly lower periadventitial macrophage and granulocyte counts of 25.0+/-3.9 cells per high-powered field compared with counts of 140.5+/-18.2 cells per high-powered field in the untreated vessels (P<0.001). CONCLUSIONS: The periadventitial, controlled release of ibuprofen from surgically implanted polymers significantly inhibits chronic posthemorrhagic vasospasm in this model when treatment is initiated within 6 hours of blood exposure. Vasospasm inhibition with ibuprofen correlates with a significant decrease in the number of macrophages and granulocytes in the periadventitial space. This study supports the hypothesis that inflammation mediates in part the chronic phase of posthemorrhagic vasospasm and suggests a potential alternative treatment for this condition.     

Non-uniform triggering of gg-nMOSt investigated by combined emission microscopy and transmission line pulsing

The triggering of grounded-gate nMOS transistors and field-oxide devices, essential for optimized protection design, is addressed by transmission line pulser (TLP)-pulsed emission microscopy. Current non-uniformity and instability effects in snapback operation under DC and TLP conditions are demonstrated. The comprehensive correlation of emission and electrical behavior allows an improved interpretation of device operation. Technological influences on the trigger uniformity are discussed.