Is follicular atresia biphasic?

OBJECTIVE: To examine the rate of human follicular depletion and the interpretation of curved scatters on log-linear plots. DESIGN: Four mathematical models were tested with use of data drawn from published autopsy studies and histologic analyses of ovaries. SETTING: None. PATIENT(S): None. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): None. RESULT(S): Human oocyte depletion data do not support the inference of a biphasic follicular atresia. On original measurement scales there is no perturbation in the data between ages 37 and 40, and the instantaneous rate of follicle loss is lower after age 40 than ever before. CONCLUSION(S): There is no abrupt increase in the "rate" of follicular atresia that corresponds with a drop in fecundability or an increase in risk of chromosomal abnormalities at approximately age 38. The apparent abrupt increase in rate of follicular depletion is an artifact of log-linear transformation.     

Homologue matching applications: Recognition of overlapped chromosomes

Automated Giemsa-banded chromosome image research has been largely restricted to classification schemes associated with isolated chromosomes within metaphase spreads. Overlapping chromosomes cause difficulties in the automated chromosome karyotyping process. First, overlapping chromosomes must be recognised and decomposed into the proper chromosome parts. Secondly, the decomposed chromosomes must be classified. The first difficulty is associated with image segmentation. The second area is a pattern recognition problem. Even if chromosomes within overlapping clusters are decomposed properly, classification capability is impaired due to feature distortion in the overlapped regions. In normal human metaphase spreads, chromosomes occur in homologous pairs for the autosomal classes, 1–22, and X chromosome for females. This research presents a homologue matching approach for overlapped chromosome recognition. The undistorted grey level information in isolated chromosomes is used for identifying overlapped chromosomes. An isolated chromosome prototype is obtained using neural networks. Dynamic programming and neural networks are compared for matching the prototype to its overlapped homoloque. The homologue matching method is applied to identifying chromosome 2 in 50 metaphase spreads. Experimental results showed that homologue matching using dynamic programming matching based on the density profile achieved a higher correct recognition rate than homologue matching using three different neural network approaches.Grant Support: This research was supported in part by a grant from the University of Missouri Research board and training grant 5 T15 LM/CA07089-04 from the National Library of Medicine and National Cancer Institute, Bethesda, MD.     

基于2DMesh拓扑结构的NoC模拟器设计

片上网络模拟器的设计涉及到片上网络的拓扑结构、路由器结构、路由算法、性能分析等诸多方面。从NoC模拟器设计的角度,研究并讨论模拟器所采用的拓扑结构,路由器结构及数据包格式。介绍拓扑结构模拟、IP核模拟、路由模拟,并且用面向对象语言C＋＋实现一个NoC模拟器系统。     

一种基于关键词搜索的空间连接查询

许多实际的应用需要同时支持空间连接查询和关键词搜索。在给出基于关键词的空间连接（KSJ）查询定义的基础上,对参与KSJ查询的空间数据集建立MIR2-树索引结构,并结合一些高效的搜索剪枝策略,提出一种基于宽度优先的KSJ查询算法。实验结果表明该算法可有效支持基于关键词的空间连接查询处理。     

Exploring fecal indicator bacteria in a constructed stormwater wetland

Microbial pollution in surface waters is a concern throughout the world, with both public health and economic implications. One contributing source to such pollution is stormwater runoff, often treated using various types of stormwater control measures. However, relatively little is known regarding microbe sequestration in constructed stormwater wetlands (CSWs), one type of commonly installed stormwater control measure. In this study, indicator bacteria concentrations in both the water and sediment of a CSW were evaluated at multiple locations. Results suggested that fecal coliform concentrations in stormwater runoff decrease through the system, with relatively consistent concentrations noted throughout the second half of the wetland. This potentially indicates a baseline concentration of fecal coliform is present due to internal processes such as animal activity and microbial persistence. However, wetland sediments showed little E. coli present during most sampling events, with minimal patterns existing with respect to sediment sampling location. CSW designs should promote optimization of hydraulic retention time and minimization of stormwater velocities to promote sedimentation and degradation of microbes by way of wetland treatment functions.     

基于范围分割数据的负载平衡算法的研究*

基于范围分割提出了一个有效的、渐近的负载平衡算法,可确保在任意时间的存储平衡,理论分析证明了该方法的有效性。     

A Minimalist Fault-Tolerant Microcontroller Design for Embedded Spacecraft Computing

Inexpensive commodity microcontrollers are extremely attractive for offloading low-level, real-time computations from high-performance spacecraft computers due to their high functional density and low power, but they have not been widely used because of their low radiation tolerance. This paper presents a fault-tolerant microcontroller configuration specifically designed to tolerate space-radiation effects that be used for embedded real-time control in spacecraft. The requirements and fault-environment are examined, then an architecture is presented. An experimental testbed is described along with fault-insertion test results.     

虚拟仪器结构及其可视化编程的技术进展

阐述了在仪器和测试领域中具有广泛发展前景的虚拟仪器的硬件结构、测控技术以及虚拟仪器测试软件结构及其开发软件平台。     

一种信号峰值幅度分析系统的设计

详细介绍信号峰值幅度分析器系统的原理和硬件结构等。系统以 89C5 1为控制核心 ,两级采样保持电路 ,能够甄别输入信号的上升沿及峰值信息 ;设计的并口通讯模块适用于台式和笔记本微机。