光通信技术讲座--(五):WDM系统光节点器件

介绍WDM系统光节点所用到的器件,如波长转换器、光分插复用器及其使用的光隔离器和光环形器.     

Interleukin-1 beta-converting enzyme mediates cisplatin-induced apoptosis in malignant glioma cells

Increasing the susceptibility of tumor cells to apoptotic cell death following chemotherapy is of importance to the outcome of cancer treatment. Although the tumor suppressor gene p53 is required for efficient induction of apoptosis by chemotherapeutic agents, it is not the only apoptosis mediator gene. The molecular mechanisms mediating apoptosis following chemotherapy via p53-dependent or p53-independent pathways remain unclear. We show here that cis-diamminedichloroplatinum (cisplatin) induces the expression of interleukin-1 beta-converting enzyme (ICE), a mammalian homologue of the Caenorhabditis elegans cell death gene ced-3, in murine and human malignant glioma cells during apoptosis regardless of their p53 status. Furthermore, overexpression of the murine ICE gene induces apoptosis in these tumor cells. The apoptosis induced by cisplatin treatment or murine ICE overexpression can be suppressed by the tetrapeptide ICE inhibitor Ac-YVAD-CMK or the apoptosis inhibitors bcl-2 or bcl-2-related bcl-XL gene. These findings suggest that ICE may mediate apoptosis induced by chemotherapy, and its induction could represent a novel approach for the effective treatment of malignant glioma.     

巧点火锅鸳鸯谱

北风起．火锅热。户外寒气逼人，屋内热气腾腾．鲜红的肉片。翠生生的青菜．在或红或白滚烫的锅中上下飞舞，仅是这灵动的姿态就让人禁受不住媚惑，抬手、举箸．一番狼吞虎咽，于是热气从心底缓缓升起，寒冷顿时一扫而空。[编者按]     

MOS RF reliability subject to dynamic voltage stress-modeling and analysis

Dynamic stress on MOSFETs with 900-MHz inverter-like waveforms as well as static (or dc) stress were evaluated experimentally. It showed that the degradation due to dynamic stress is less than that of dc stress for our test transistors. A compact model is used to evaluate the degradation in radio frequency performances, such as transconductance, cutoff frequency, linearity, and noise figure. A class-AB power amplifier is presented as an example to demonstrate the effect of dynamic stress on RF circuit performance.     

Response of simulated propellant and explosives to projectile impact—II. Fragmentation

This paper is the second of a series concerned with the penetration and perforation phenomena in two types of propellant and explosive simulant, named Propergol, due to the impact at normal incidence of both blunt and conically-tipped steel strikers. The collision results in fragmentation, plug formation and generation of a cloud of debris that includes particles of measurable dimensions traveling with significant velocities. Both the fragment size and area as well as the ejecta mass are determined experimentally as a function of Propergol specimen thickness and impact velocity or energy. The cumulative number of fragments as a function of size for the Propergol is uniformly found to be a bi-linear semi-logarithmic relationship with the bifurcation occurring at the mean crystal radius. Individual crystals and the crater generated are examined by means of a scanning electron microscope.

A phenomenological model of the fragmentation process is constructed, based on an assumed spherical shape of the fragments and the bi-linear fragment distribution, using energy methods. This is combined with a perforation analysis that considers the process to be sequentially composed of initial indentation, fragmentation, and sliding and deflection of the Propergol disks. An evaluation of this model providing fragment volumes as a function of impact velocity is compared with experimental results and found to be in good agreement.     

艰难兴大业踏雪寻梅来——访香港著名企业家沈家燊

序：“为什么我的眼里常含泪水，因为我对这土地爱的深沉。”每次读到艾青的这句诗，我都攀不住在想诗人到底有着怎样的情节．而这情节又是怎棒化成澎湃的激情？当面对沈家柴先生那闪烁着光芒，自信、执着、激情四射的眼神时，我缝于找到了答案：正是对一个国家、一座城市拥有了不移信念、不倦热情、不衰挚爱，他才有了面对错综复杂矛盾时的坦荡胸怀，才会有了风雨兼程的无怨无悔。沈家集为这句诗做出了最生动的逄释，他以自己的方式在津洁大地上刻写着人生的价值，他将心和力奉献给了天津。     

A Shortcut Method for Estimating the HETP of Structured Packed Distillation Columns at Elevated Pressure

A shortcut model is developed for predicting the HETP of a structured packed distillation column operating at elevated pressure. The proposed model incorporates the geometrical parameters of the packing, physical properties of the vapor and liquid phases, and the hydrodynamics of the two‐phase flow. The proposed model is tested and validated by comparing the predicted results with the present experimental data and some published HETP data. The results show that the proposed model can predict the experimental data with a deviation smaller than 20 %.     

Risk-Based Allocation of Distribution System Maintenance Resources

Asset management is an important activity in present day distribution system planning and operation. Utilities are constantly striving to optimize the use of resources available for maintenance while ensuring system reliability is within satisfactory limits. This paper proposes a method to allocate maintenance resources to various distribution system assets. To determine the effects of maintenance, a predictive reliability assessment tool is developed. This paper describes the model on which this tool is based. The results obtained from reliability assessment can be used along with an optimizer to allocate resources to various maintenance tasks in a distribution system.