Ultrastructural immunogold localization of major sperm protein (MSP) in spermatogenic cells of the nematode Acrobeles complexus (Nematoda,Rhabditida)

The nematode spermatozoa represent a highly modified (aberrant) type of male gametes that lack a flagellum but for which the process of spermatogenesis culminates in the production of a crawling spermatozoon on the basis of the cytoskeletal component known as “major sperm protein”, or MSP. MSP is also known as an important hormone triggering oocyte maturation and ovulation in the model nematode Caenorhabditis elegans, where this protein was first identified. However, direct evidence of MSP localization and of its fate in nematode spermatogenic cells is rare. In this study, the spermatogenesis and sperm structure in the rhabditid nematode Acrobeles complexus (Rhabditida: Tylenchina: Cephalobomorpha: Cephaloboidea: Cephalobidae) has been examined with electron microscopy. Morphological observations were followed by high-pressure freezing and freeze-substitution fixation which allows post-embedding immunogold localization of MSP in all stages of sperm development using antibodies raised for MSP of C. elegans. In spermatocytes, synthetic activity results in the development of specific cellular components, fibrous bodies (FB) and membranous organelles (MO), which appear as FB-MO complexes where the filamentous matter of FB has been MSP-labeled. The spermatids subdivide into a residual body with superfluous cytoplasm, and a main cell body which contains nucleus, mitochondria and FB-MO complexes. These complexes dissociate into individual components, MO and FB, with the MSP being localized in FB. Immature spermatozoa from testes are opaque cells where a centrally located nucleus is surrounded by mitochondria, MO and FB clustered together, the MSP still being localized only in FB. Cytoplasm of mature spermatozoa from spermatheca is segregated into external pseudopods lacking organelles and a central cluster of mitochondria with intact MO surrounding the central nucleus. The FB ultimately disappear, and the MSP labeling becomes concentrated in the filamentous content of pseudopods and cytoplasm of the main cell body. Although the spermatogenesis and sperm structure of A. complexus is similar to that of many other rhabditid nematodes, their intact MO makes the morphology of the mature spermatozoa distinct from the “rhabditid pattern” and may be considered as a synapomorphy. The MSP localization in spermatogenic cells of A. complexus also follows the “rhabditid pattern” described in C. elegans and Ascaris spp. Our results and techniques of MSP labeling of A. complexus spermatogeneous cells reveal new possibilities to elucidate different research questions on MSP localization in nematodes related to C. elegans. Furthermore, the laboratory-cultured A. complexus strains can be used as a new and fascinating model to study MO and MSP functions in nematode reproduction.     

具有高阈值电压和大栅压摆幅的常关型槽栅AlGaN/GaN金属氧化物半导体高电子迁移率晶体管

介绍了一种具有高阈值电压和大栅压摆幅的常关型槽栅AlGaN/GaN金属氧化物半导体高电子迁移率晶体管。采用原子层淀积(ALD)方法实现Al₂O₃栅介质的沉积。槽栅常关型AlGaN/GaN MOS-HEMT的栅长(L_g)为2 μm,栅宽(W_g)为0.9 mm(0.45 mm×2),栅极和源极(L_gs)之间的距离为5 μm,栅极和漏极(L_gd)之间的距离为10 μm。在栅压为－20 V时,槽栅常关型AlGaN/GaN MOS-HEMT的栅漏电仅为0.65 nA。在栅压为+12 V时,槽栅常关型AlGaN/GaN MOS-HEMT的栅漏电为225 nA。器件的栅压摆幅为－20~+12 V。在栅压V_gs=+10 V时,槽栅常关型AlGaN/GaN MOS-HEMT电流和饱和电流密度分别达到了98 mA和108 mA/mm (W_g=0.9 mm), 特征导通电阻为4 mΩ·cm²。槽栅常关型AlGaN/GaN MOS-HEMT的阈值电压为+4.6 V,开启与关断电流比达到了5×10⁸。当V_ds=7 V时,器件的峰值跨导为42 mS/mm (W_g=0.9 mm,V_gs=+10 V)。在V_gs=0 V时,栅漏间距为10 μm的槽栅常关型AlGaN/GaN MOS-HEMT的关断击穿电压为450 V,关断泄露电流为0.025 mA/mm。     

比较逻辑的研究

本文引入几种比较运算,并讨论了它们的表示、有关性质及其在处理逻辑函数中的应用。此外,还提出了使用晶体管的比较逻辑门及通用比较逻辑门的设计。作者认为,由于比较运算揭示了电路中开关元件的作用实质,因此,充分利用晶体管功能的比较逻辑单元,可在数字集成电路的设计中得到应用。     

钢闸门支承滑道摩擦随时间变化的研究

研究了胶木、油尼龙和铜塑固体自润滑复合材料（ＴＳ－７０）３种平面滑动钢闸门支承滑道的摩擦时间效应,介绍了胶木和ＴＳ－７０滑道摩擦时间效应的原型试验结果,用粘着理论解释胶木与油尼龙滑道摩擦时间效应强、ＴＳ－７０滑道摩擦时间效应弱的原因在于粘弹性材料的蠕变大,引起实际接触面积增大,粘弹性材料的剪切模量的时间效应也大,使界面剪切强度增大。     

基于线计算的全加器设计

随着集成电路特征尺寸的不断缩小, 互连线在芯片内部占的比重越来越大, 但是互连线仅用于数据传输, 芯片计算能力仍然需要依靠晶体管开关实现. 如何在有限的硬件资源内进一步提高芯片的计算能力, 已经成为当前集成电路设计的核心问题. 本文通过研究金属互连线间电容耦合效应, 采用互连线串扰现象完成逻辑运算的思想, 提出一种基于线计算的全加器设计方案. 该方案首先建立线计算模型, 通过调整反相器阈值和不同干扰线与受扰线之间电容耦合强度匹配技术, 采用相同线计算电路结构实现不同功能的逻辑门电路; 然后, 在逻辑门的基础上实现基于线计算的全加器; 最后, 在TSMC 65nm CMOS工艺下仿真验证. 结果表明, 所设计的线计算电路具有正确逻辑功能, 与传统设计方法相比, 线计算逻辑门具有更低开销, 且线计算电路具有抗逆向工程能力.     

星载光电跟踪系统连续帧图像快速识别定位算法研究

为了解决星载光电跟踪系统对连续帧图像快速识别、准确定位的要求.在深入分析连续图像序列特性和星载光电跟踪系统特点的基础上,利用光电跟踪系统转台的角度变化信息,对图像序列进行帧间差值运算以获得目标残差图,并基于残差图和原始图像信息提出了一种新的目标识别定位算法,大大地减小了运算量.结合中值滤波和自适应波门跟踪算法,实现了运动目标的快速跟踪定位.通过对目标实测图像序列的实验,结果证明,该算法具有快速、稳定等优点,能满足星载光电跟踪系统实时图像跟踪的要求.     

Implementation of Controlled‐NOT Gate by Lyapunov Control

A scheme to implement the controlled‐NOT (CNOT) gate for quantum systems is proposed, which is based on Lyapunov control. The scheme does not require precise control of the interaction time since the system is stable when the control fields vanish. In particular, the control fields can be easily obtained by most initial states. As an example, the CNOT gate is realized for two atoms trapped in an optical cavity by exploiting two disturbance cases. Compared to continuous disturbance, the fidelity of the CNOT gate is higher under impulsive disturbance, however, interaction times are much longer. Numerical simulations indicate that the scheme is robust against variations of control parameters and decoherence caused by atomic spontaneous emission and cavity decay. Therefore, the scheme may provide useful applications in quantum computation.     

One-step implementation of a multi-target-qubit controlled phase gate with cat-state qubits in circuit QED

We propose a single-step implementation of a muti-target-qubit controlled phase gate with one catstate qubit (cqubit) simultaneously controlling n–1 target cqubits. The two logic states of a cqubit are represented by two orthogonal cat states of a single cavity mode. In this proposal, the gate is implemented with n microwave cavities coupled to a superconducting transmon qutrit. Because the qutrit remains in the ground state during the gate operation, decoherence caused due to the qutrit’s energy relaxation and dephasing is greatly suppressed. The gate implementation is quite simple because only a single-step operation is needed and neither classical pulse nor measurement is required. Numerical simulations demonstrate that high-fidelity realization of a controlled phase gate with one cqubit simultaneously controlling two target cqubits is feasible with present circuit QED technology. This proposal can be extended to a wide range of physical systems to realize the proposed gate, such as multiple microwave or optical cavities coupled to a natural or artificial three-level atom.     

边孔弧形闸门水流脉动压力特性研究

弧形泄水闸是水利枢纽工程中常见的挡水、泄水建筑物,其在关闭或开启过程中或者局部开启运行时,在水流脉动压力作用下会产生振动,容易引起闸门结构破坏。本文针对边孔闸门与中孔闸门不同的水流边界条件特点,制作了带导流墙与无导流墙两个弧形闸门模型。在实验室内开展了不同库水位、不同闸门开度下的物理模型试验,并对两个模型上大量测点的水流脉动压力数据进行比较分析。试验表明,导流墙的存在对脉动压力主频的影响较小,但对脉动压力均方根值影响较大;在较高库水位下相对开度位于0.2至0.3区间内时,导流墙的存在不但不会改善闸门的受力状况,反而还会导致受力增强。     

Complete Analysis of Four-Photon χ-Type Entangled State via Cross-Kerr Nonlinearity

We propose an efficient method to construct an optical four-photon |χ> state analyzer via the cross-Kerr nonlinearity combined with linear optical elements. In this protocol, two four-qubit parity-check gates and two controlled phase gates are employed. We show that all the 16 orthogonal four-qubit |χ> states can be completely discriminated with our apparatus. The scheme is feasible and realizable with current technology. It may have useful potential applications in quantum information processing which based on |χ> state.