Extensive thrombophlebitis with reactive thrombocytosis in a high risk Chinese parturient associated with retained placenta increta: a case report

Forty-three patients with spastic quadriplegia (mean age 7.9 years, range 3.3 to 17.2 years) underwent bone mineral density (BMD) measurement of the lumbar spine and were evaluated between 2.6 and 5.5 years (mean 3.8) later to determine whether this measurement had predicted risk of fracture over the subsequent period of observation. Other potential risk factors that were evaluated include body weight z score, serum vitamin D levels, previous fracture, and hip spica casting. The baseline measurements showed that BMD falls further below normal with increasing age and was more than one standard deviation below age-matched normal mean in 38 of the 43 patients. Fracture rate did not differ between those with low and those with very low spinal BMD. Similarly, serum vitamin D levels and body weight z scores were not predictive of fracture. However, fracture rate was over fourfold greater following spica casting and more than threefold greater following an initial fracture. Fracture rates in the study group were similar to those reported for age- and sex-matched normal children, though generally the location of the fractures and mechanisms of injury differed.     

On the detection of motion and the computation of optical flow

A method for the detection of motion in image sequences is presented. In this method, the intensity history at each pixel is convolved with the second derivative in time of a temporal Gaussian smoothing function. The zero crossings in a single frame of the resulting function indicate the positions of moving edges. Intensity changes in time due to illumination effects do not produce zero crossings; thus, they are not interpreted as motion by the present method. It is also shown that the spatial and temporal derivatives of this function can be used to compute the component of the optical flow that is normal to the zero-crossing contours. This computation is also insensitive to nonconvective temporal and spatial variations in the image intensity that are caused by illumination effects     

Reliability assessment for solders with a stress buffer layer using ball shear strength test and board-level finite element analysis

The stress buffer layer (SBL) is a widely applied improvement in many advanced packages used to release the stress concentration at solder joints. However, it has been generally found that the metal line adjacent to the SBL may suffer larger deformation and its reliability should be addressed. In this study, the panel level package (PLP) technology with solder on polymer (SOP) structure is selected as the testing sample to investigate the effect of SBL. The ball shear strength test is conducted first to investigate the reliability of metal trace in PLP. In addition, finite element (FE) analysis is applied to understand the actual thermo-mechanical behavior of PLP after its assembly. The package-level and board-level reliability assessments are compared, and the suggested layout of the redistribution layer on the SBL is provided herein.     

Effects of hot carrier induced interface state generation insubmicron LDD MOSFET's

A two-dimensional numerical simulation including a new interface state generation model has been developed to study the performance variation of a LDD MOSFET after a dc voltage stress. The spatial distribution of hot carrier induced interface states is calculated with a breaking silicon-hydrogen bond model. Mobility degradation and reduction of conduction charge due to interface traps are considered. A 0.6 μm LDD MOSFET was fabricated. The drain current degradation and the substrate current variation after a stress were characterized to compare the simulation. A reduction of the substrate current at V_g ≃0.5 V_d in a stressed device was observed from both the measurement and the simulation. Our study reveals that the reduction is attributed to a distance between a maximum channel electric field and generated interface states     

基于媒体用户访问行为偏好模型的代理缓存算法

目前,代理缓存技术广泛应用于改善流媒体传输的服务质量.文章从实际用户日志文件的分析出发,利用发现的用户浏览流媒体对象时的行为分布模型,提出了一种新的视频流媒体缓存算法.仿真结果证明,该算法可以通过记录很少的用户访问信息获取较高的性能表现.     

Analysis of adaptive bandwidth allocation in wireless networks with multilevel degradable quality of service

A wireless/mobile network supporting multilevel quality of service (QoS) is considered. In such a network, users or applications can tolerate a certain degree of QoS degradation. Bandwidth allocation to users can, therefore, be adjusted dynamically according to the underlying network condition so as to increase bandwidth utilization and service provider's revenue. However, arbitrary QoS degradation may be unsatisfactory or unacceptable to the users, hence resulting in their subsequent defection. Instead of only focusing on bandwidth utilization or blocking/dropping probability, two new user-perceived QoS metrics, degradation ratio and upgrade/degrade frequency, are proposed. A Markov model is then provided to derive these QoS metrics. Using this model, we evaluate the effects of adaptive bandwidth allocation on user-perceived QoS and show the existence of trade offs between system performance and user-perceived QoS. We also show how to exploit adaptive bandwidth allocation to increase system utilization (for the system administrator) with controlled QoS degradation (for the users). By considering various mobility patterns, the simulation results are shown to match our analytical results, demonstrating the applicability of our analytical model to more general cases.     

An introduction to Wu's method for mechanical theorem proving in geometry

Wu's algebraic method for mechanically proving geometry theorems is presented at a level as elementary as possible with sufficient examples for further understanding the complete method.The work reported here was supported by NSF Grant DCR-8503498.