银鲫卵对两类精核发育的初级控制作用模式的研究

通过对银鲫(雌核发育型)和红鲤、红鲫、转性红鲤(两性融合发育型)两类精子在雌核发育银鲫卵中的不同发育行为的比较研究,初步证实银鲫卵的初级控制对精核发育的抑制作用具有选择性:对同源精子,初级控制呈负抑制作用模式,精核可以在银鲫卵中不同程度的发育;而对异源精子,初级控制呈正抑制作用模式,精核处于固缩状态.两类精核在银鲫卵质中的特殊发育行为可能与银鲫种群中性比的变化存在着某种关系,雄性银鲫的出现可能与“精核遗传物质”的随机渗入有关。     

JLab Hall-A上小角度GDH实验中的粒子鉴别及其效率

在JLab的A大厅上的小角度GDH实验中, 因为散射截面及截面不对称度的测量需要干净的电子样本和足够的事例统计, 径迹在簇射量能器和气体阈契仑柯夫探测器理的信息被用来完成粒子鉴别的任务. 通过优化粒子在两种探测器里的信息筛选条件, 可以得到较高的电子接收效率和π的去除能力. 因为探测器的分辨能力与粒子的动量等运动学参量有关, 所以对于不同的数据的粒子鉴别条件分别进行了优化, 并得到了对应的电子接收效率和π的去除能力.     

高分辨宽测绘带星载合成孔径雷达频域重构算法

针对传统星载合成孔径雷达(SAR)系统高分辨率和宽测绘带之间的矛盾,采用方位向偏置相位中心结合距离向波束扫描（ScanSAR）模式实现同时高分辨宽测绘带SAR成像,并针对雷达脉冲发射频率、平台速度和天线尺寸不满足严格约束条件导致的方位向非均匀采样提出了频域重构算法。该算法可以实现精确频谱重构,并且极大地提高了系统设计和参数选择的灵活性。五扫六通道SAR系统的频域重构算法的仿真结果显示成对回波抑制达60 dB以上,方位模糊比达-23 dB,证明了该算法的有效性。     

MEIOTIC CHROMOSOME BEHAVIOR IN FEMALE INTERSEXES OF ARTIFICIAL TRIPLOID TRANSPARENT-COLORED CRUCIAN CARP

Chromosome behavior in meiosis was studied by ail-drying, C-banding and surface-spreading methods in female intersexes of artificial triploid transparent-colored crucian carp (Corassius auratus). Chromosome pairing and contraction were obviously asynchronous. The preferential pairing of two homologous chromosomes was the major pattern of chromosome pairing, and a few triple pairing, repeated pairing, telomere or centromere associating and multiple pairing were also observed in the pachytene cells. The metaphase I cells were main-ly composed of univalents, bivalents and trivalents, as well as a few of other multivalents, such as tetravalents, pentavalents, hexavalents and heptavalents, were also found in some metaphase I cells. The chromosome elements including uni-, bi-, tri- and other multivalents varied considerably among the metaphase I cells, and the associating patterns of multivalents were also diverse. Some 6 n and 12 n cells, in which premeiotic endomitosis occurred once or twice, were found at     

Transmission and Dwell Time Oscillations Caused by Coexistence of Tunneling and Propagating in a Trapezoidal Barrier

Abstract A refined one of our exactly solvable trapezoidal barrier potential model [Thin Solids Films, 414 （2002） 136）] for metal-insulator-metal tunnel junctions has Seen presented. According to the refined model, the longitudinal kinetic energy （ExL） and the effective mass （m^＊L） of the electron8 in the electrode on the left of the barrier distinguish from that on the right. It is found that as ExL is greater than the shorter side of the resultant trapezoidal barrier potential, there will be a coexistence of the tunneling and propagating in the barrier. The results demonstrate that the damped oscillating electron waves localized in the propagating barrier subregion lead to the oscillation and enhancement in the transmission coefficient DT and dwell time TD. For the barrier height φ1=2.6 eV and φ2 = 1.4 eV, the width d=22 A and ExL = 1.0 eV, DT and TD have a maximum of 0.054 and 0.58x10^-15 s at V = 2.04 V and 2.18 V, respectively. This suggests that a real tunneling may be a hybrid.     

STUDY ON THE MODE OF PRIMARY CONTROL IN THE EGG OF GYNOGENETIC CRUCIAN CARP FOR INHIBITING THE DEVELOPMENT OF TWO TYPES OF SPERM NUCLEI

By comparing the different developmental characteristics of two types of sperm nucleiwhich were from gynogenetic fish (crucian carp) and amphimictic fishes (red carp, redgoldfish and sex--reversal red carp) respectively in the eggs of gynogenetic crucian carp, itwas preliminarily revealed that there existed selective inhibiting actions of the primarycontrol in the eggs of crucian carp for inhibiting the development of the two types of spermnuclei. To homologous sperms, the primary control showed weak effect, thus leading tothe decondensation of homologous sperm nuclei at different degrees in the eggs of cruciancarp. But to heterologous sperms, the primary control showed strong effects, resulting in thetotal inhibition of the development of heterologous sperm nuclei. Moreover, our experimentalresults also showed that the different developmental behavior of the two types of spermnuclei might have a great relationship to the changes or the sex ratio in the population ofgynogenetic crucian carp. The infiltr     

Revisiting the QCD Corrections to the R-Parity Violating Processes pp/pp → eμ ＋ X

We present the theoretical predictions up to QCD next-to-leading order for the cross section of high-mass electron-muon pair production at the Tevatron and at the Large Hadron Collider （LHC）, considering only the dominant contributions from the third-generation sneutrino. The dependence of the renormalization and factorization scales on the total cross section, and the effects on the K-factor due to the uncertainty of parton distribution function are carefully investigated. By considering soft-gluon resummation effects to all orders in as of leading logarithm, we present the transverse momentum distributions of the final eμ pair.     

人工三倍体水晶彩鲫雌性型间性体减数分裂的染色体行为

本文报道了人工三倍体水晶彩鲫雌性型间性体减数分裂过程以及染色体配对和联合等行为.染色体配对和凝缩表现有明显的非同步性,在配对形式上,主要表现为两条同源染色体的优先配对,也见有少数“三联配对”、重复配对、端粒或着丝粒联合和复合配对等形式.中期Ⅰ细胞主要由单价体、二价体和三价体以及少量多价体组成,且细胞间变化很大,多价体的联合形式也较为多样.经历了一次或两次核内有丝分裂形成的六倍体和十二倍体细胞也能进入减数分裂,其配对和联合形式基本上与三倍体相似.     

掺混PODE对汽油–柴油双燃料发动机燃烧及碳烟生成特性研究

本文针对清洁燃料替代传统燃料,在光学发动机上,利用高速成像技术结合双色法采集了柴油掺混聚甲氧基二甲醚(PODE)-汽油反应活性控制压燃模式下的缸内燃烧特性及碳烟生成过程。试验结果表明：相同预混比下随着PODE的掺混增加,缸内压力峰值、放热率峰值、压力升高率都随之降低,着火延迟期延长,燃烧持续期增加,燃烧相位后移,燃烧趋于平缓。在预混比为50%时,直喷P20D80及P50D50的单循环燃烧总放热量分别为直喷P0D100总放热量的97.89%和95.39%,单循环碳烟生成总量分别为直喷P0D100的55.22%和36.55%,碳烟高温区域分别减少了52.9%和73.32%,碳烟平均温度的稳定值分别降低了6.65 K和20.25 K,碳烟平均KL因子的稳定值分别降低了10.35%和16.12%。相较而言P50D50作为直喷燃料既能保证较高燃烧热效率,又能有效抑制碳烟的生成。     

Hall-A上小角度GDH实验中量能器的刻度修正

在JLab的A大厅上的小角度GDH实验中, 采用了Fumili拟合方法对位于高分辨谱仪上的量能器进行刻度. 因为实验过程中硬件条件的变化以及大量的运动学数据的存在, 对该实验数据分批进行了刻度. 刻度结果表明, 此刻度修正是合适的. 在散射电子动量为1GeV的时候, 量能器对该粒子的分辨率为0.06GeV.