Differential expression of two distinct T-cell receptors during thymocyte development

The product of the T-cell receptor (TCR) gamma-gene has recently been found to be expressed on a subset of both peripheral cells and thymocytes. As an initial approach to understanding the role of this gamma-chain of TCR (TCR gamma) in T-cell development, we have studied the ontogeny of TCR expression at the protein level in the developing murine thymus. We show here that the first T3-associated TCR to be expressed in the developing thymus is a disulphide-linked heterodimer composed of a gamma-chain of relative molecular mass 35,000 (Mr 35K) and a 45K partner (termed TCR delta). This TCR gamma delta is first detected approximately two days before the appearance of cell-surface TCR alpha beta heterodimers. We report that N-glycosidase digestions reveal that all of the gamma-protein expressed on fetal thymocytes, as in adult CD4-8-(L3T4-, Lyt2-) thymocytes, bear N-linked carbohydrate side chains. The major gamma-gene transcribed in mature, alpha beta-bearing T cells (V gamma 1.2C gamma 2)encodes no N-linked glycosylation site so these results suggest that the fetal gamma delta receptor defines a distinct T-cell lineage whose development in the thymus precedes classical alpha beta-bearing cells.     

高频放大器中几种扩展带宽技术的研究

详细分析了适用于高频放大器四种有效扩展带宽的技术。分别为反比例级联技术、并联峰值技术、电容峰值技术和分布式放大器,分析了它们的工作原理及它们的优点、缺点,及适用场合。     

Enhanced detection in the aperture of focal attention during simple discrimination tasks

There is increasing evidence that it is possible to shift an aperture of focal attention to a position in visual space independent of fixation and that this can be done much faster than the eyes are able to move. Recently, we showed that such serial scrutiny by the aperture of focal attention is required before an observer is able to tell what a target is (for example, to know whether the orientation of a line segment is horizontal or vertical). Here we considered whether attention directed towards a specific position in the visual field for an orientation discrimination task improves performance on a simple detection task in the area to which attention is directed. We found that a small test flash could be detected when it was positioned near a peripheral line target presented briefly, if the orientation of the target had to be identified. The test flash could not be detected when presented at some distance from the same target or when another target had to be identified. This enhancement implies that even simple identification tasks such as orientation discrimination are not performed passively by the visual system.     

Requirement for integrins during Drosophila wing development

The position-specific (PS) integrins of Drosophila are highly homologous to vertebrate integrins, most of which are cell-surface receptors for extracellular matrix components. Integrins are heterodimers, each consisting of noncovalently associated alpha- and beta-subunits. As for the subfamilies of vertebrate integrins, the same beta-subunit is found in both Drosophila PS integrins, combined with a specific alpha-subunit to generate either a complete functional PS1 or PS2 integrin. Both alpha- and beta-subunits are large transmembrane proteins (relative molecular masses greater than 100,000). Either one or both of these two PS integrins are expressed in most fly tissues during development. A particularly intriguing pattern of expression is found in the mature wing imaginal disc, where the PS1 integrin is expressed primarily on the presumptive dorsal wing epithelium, and the PS2 integrin is found almost exclusively on the ventral epithelium. Immediately after pupariation, the central wing pouch evaginates, folding along its centre to appose the epithelia that will secret the dorsal and ventral surfaces of the adult wing blade. Here we report the results of a genetic analysis indicating that both of the PS integrins are required to maintain the close apposition of the dorsal and ventral wing epithelia during morphogenesis. Also, we conclude that the integrins are not necessary for the maintenance of the cell lineage restriction between the two presumptive wing surfaces in the developing imaginal disc.     

一种宽带光纤拉曼放大器数值模拟的新算法

以后向泵浦的宽带光纤拉曼放大器为模型,基于平均功率的思想,运用矩阵迭代法模拟信号光和泵浦光在光纤中的传输特性,数值计算出拉曼增益曲线.这种算法结合了平均功率法的快速和矩阵迭代法的简单易控制的优点,在保证计算精度的情况下能提高计算速度.理论分析结果和实验结果均显示该算法可以准确模拟拉曼放大过程.该算法可以为设计制作光纤拉曼放大器提供参考.     

Research on the Bit Computation Model for Time Variable Channel Bandwidth

For the encoding bit-rate problem in H.264 wireless video communication,this paper analyzes the bit-rate computation model and the Mean Square Error distortion model,establishes the relation between the quantization parameter of the encoding bit-rate and the intra frame refresh rate of the macro block,and put forward a new ideal about the coding rate on the basis of general binomial computation model theory. Furthermore,this method not only can adaptively adjust the bit allocation and quantization parameter and prevents buffer from overflowing downward or upward under given network bandwidth,but also can apply the rate-distortion to optimize the solution method,control the encoding bits accurately and optimizes the allocation between the intra and inter frame encoding macro block.     

基于电磁信号导航的智能车系统设计与开发

运用嵌入式系统的开发方法,详细描述了一套基于电磁导航原理设计的智能车系统开发过程。系统设计目标是:在保证智能车不脱离运行轨道的前提下,速度尽可能地快。系统选取32位微控制器MK60DX256ZVLQ10为主控芯片,通过完整地设计并优化小车的硬件系统、软件系统和机械系统,最终实现了智能车通过自行检测轨道导线激发的电磁波自主循迹行驶。     

Some polar sets for the generalized Brownian sheet

Let (t)(t ∈ R ₊ ^N ) be the d-dimensional N-parameter generalized Brownian sheet. We study the polar sets for (t). It is proved that for any a ∈ R ^d , P{ (t) = a, for some t ∈ R _> ^N } = and the probability that (t) has k-multiple points is 1 or 0 according as whether 2kN > d(k − 1)β or 2kN < d(k−1)α. These results contain and extend the results of the Brownian sheet, where R _> ^N = (0,+∞) ^N ,R ₊ ^N =[10,+∞) ^N ,0< α≤1 and β≥1. Biography: LI Huiqiong (1966–), female, Associate professor, research direction: stochastic process and random fractal.     

对中国反就业歧视立法规制的探索

形形色色的就业歧视不仅影响了我国经济的发展,还是对我国公民基本政治权利--平等权和劳动权的侵犯.本文在考察了美国反就业歧视方面的立法、司法实践的基础上,提出建立、完善我国相关法制的建议,以期保障我国公民的平等就业劳动权.     

对中国反就业歧视立法规制的探索

形形色色的就业歧视不仅影响了我国经济的发展,还是对我国公民基本政治权利——平等权和劳动权的侵犯。本文在考察了美国反就业歧视方面的立法、司法实践的基础上,提出建立、完善我国相关法制的建议,以期保障我国公民的平等就业劳动权。     

消除闲置时间的EPON动态带宽分配算法

提出一种消除以太无源光网络（ethernet passive optical net, EPON)闲置时间损耗的动态带宽分配算法。算法将全网所有光网络单元（optical network unit,ONU）在逻辑上划分为彼此互无交集的2区,对2区ONU进行分离调度,当一区ONU传输数据时就为另一区ONU授权。由于实施分区调度,相邻周期不同区ONU数据的发送在时间上就可以形成衔接,从而消除了传统EPON调度中存在的闲置时间损耗,提高了系统效率。仿真结果表明,该算法能够很好地提高系统吞吐量和带宽利用率,降低网络平均时延。     

微机械滤波器3 dB通带特性参数新计算模型

以含2个振子的微机械滤波器为对象,提出了一组3dB截止频率、3dB带宽和通带波纹度计算模型.首先,考虑到微机械滤波器的阻尼很小,在振动方程的基础上推导出了通带波纹度近似计算模型.然后,将微机械滤波器的幅频响应函数在2个固有频率处做Taylor二阶展开,再考虑到幅频响应函数的一阶导数在2个固有频率处近似为零,推导出了3dB截止频率及3dB带宽近似计算模型.最后,用计算实例证明了这些近似计算模型的精确性.     

关于扩展泄漏同轴电缆带宽的研究

根据基本电磁理论，从理论上对泄漏同轴电缆（以后简称LCX）的辐射模式进行了分析，推导出其辐射场的数学表达式．根据单模辐射产生的条件，讨论了怎样抑制高次模辐射来扩展单模辐射的带宽．之后，探讨了一种扩展八字开槽泄漏同轴电缆带宽的方法，为泄漏同轴电缆用于超宽带通信提供了一种可实践的途径．该结论对于设计应用于超宽带通信的泄漏同轴电缆有着重要意义．     

电导线性化标定的传感器信号的采集

给出了电导线性化标定的传感器信号的两种采集方法 ,进行了误差分析比较 ,并得出了利用“集成运放方法”的优越性 .     

汽轮发电机组故障诊断的并行关联模型

提出了一种新的汽轮发电机组故障诊断模型－并行关联诊断模型（ＰＲＤＭ）。ＰＲＤＭ将复杂问题分解成为相对简单又相互关联的子问题,再根据各个子问题的具体特性由多个相对独立的子系统并行协同工作,简化了求解的复杂程度。和传统的诊断专家系统相比,ＰＲＤＭ具有知识维护容易,推理机制灵活,推理效率高的优点,智能化程度有了进一步提高,适用于大型复杂系统的故障诊断。ＰＲＤＭ已经成功地应用于汽轮发电机组的故障诊断。     

有限型子转移的攀援集

研究了有限型子转移攀援集的大小.证明了对于第l行和第l列全为1的N阶0,1方阵所决定的有限型子转移而言,其中l∈{0,1,…,N-1},若它有正拓扑熵,则它的每一个极大Li-Yorke攀援集的基数为c;对于每行至少有两个元素为1且1在对角线上至少出现两次的N阶0,1方阵所决定的有限型子转移而言,若它是拓扑传递的,则存在ε0,使得它的每一个极大(F1,F2)-ε-攀援集的基数为c,其中F1与F2是与它的乘积系统兼容的Furstenberg族且kBF1,kBF2.     

全功能联结词集合的一个注记

本文对数理逻辑中的各种联结词所构成的集合进行了讨论,得到全功能联结词集合,指出了12个全功能联结词集合.其中,一阶全功能联结词集合2个;二阶全功能联结词集合7个;三阶全功能联结词集合3个;没有四阶及四阶以上的全功能联结词集合.