时滞昼夜节律起搏器模型的稳定性分析及仿真

以滞量为参数,讨论昼夜节律起搏器模型线性部分特征方程根的分布情况,得到该系统的稳定性和Hopf分支产生的条件。研究了时滞昼夜节律起搏器模型的动力学性质,为时间生物学的应用提供理论依据。     

Attosecond synchronization of high-harmonic soft x-rays

Subfemtosecond light pulses can be obtained by superposing several high harmonics of an intense laser pulse. Provided that the harmonics are emitted simultaneously, increasing their number should result in shorter pulses. However, we found that the high harmonics were not synchronized on an attosecond time scale, thus setting a lower limit to the achievable x-ray pulse duration. We showed that the synchronization could be improved considerably by controlling the underlying ultrafast electron dynamics, to provide pulses of 130 attoseconds in duration. We discuss the possibility of achieving even shorter pulses, which would allow us to track fast electron processes in matter.     

Modulation of neuronal interactions through neuronal synchronization

Brain processing depends on the interactions between neuronal groups. Those interactions are governed by the pattern of anatomical connections and by yet unknown mechanisms that modulate the effective strength of a given connection. We found that the mutual influence among neuronal groups depends on the phase relation between rhythmic activities within the groups. Phase relations supporting interactions between the groups preceded those interactions by a few milliseconds, consistent with a mechanistic role. These effects were specific in time, frequency, and space, and we therefore propose that the pattern of synchronization flexibly determines the pattern of neuronal interactions.     

麋鹿皮肤成纤维细胞的细胞周期同步化研究

为给体细胞核移植提供更多的G0/G1期供体细胞以提高克隆的成功率,本试验采用不同的接触抑制和血清饥饿时间及含羞草酸(mimosine)不同浓度和时间3种方法对麋鹿皮肤成纤维细胞进行同期化处理,然后利用流式细胞仪分析细胞周期.结果表明,接触抑制24 h G0/G1期比例可达91.95%;血清饥饿24 h有89.42%的细胞处于G0/G1期,当处理时间超过144 h细胞凋亡和异常聚集的比例会增加;适宜浓度(0.4 mmol ·L-1)的含羞草酸处理24 h能使麋鹿成纤维细胞同步化至G0/G1期,但易引起细胞损伤.     

Variations in the Earth's Orbit: Pacemaker of the Ice Ages

1) Three indices of global climate have been monitored in the record of the past 450,000 years in Southern Hemisphere ocean-floor sediments. 2) Over the frequency range 10(-4) to 10(-5) cycle per year, climatic variance of these records is concentrated in three discrete spectral peaks at periods of 23,000, 42,000, and approximately 100,000 years. These peaks correspond to the dominant periods of the earth's solar orbit, and contain respectively about 10, 25, and 50 percent of the climatic variance. 3) The 42,000-year climatic component has the same period as variations in the obliquity of the earth's axis and retains a constant phase relationship with it. 4) The 23,000-year portion of the variance displays the same periods (about 23,000 and 19,000 years) as the quasi-periodic precession index. 5) The dominant, 100,000-year climatic [See table in the PDF file] component has an average period close to, and is in phase with, orbital eccentricity. Unlike the correlations between climate and the higher-frequency orbital variations (which can be explained on the assumption that the climate system responds linearly to orbital forcing), an explanation of the correlation between climate and eccentricity probably requires an assumption of nonlinearity. 6) It is concluded that changes in the earth's orbital geometry are the fundamental cause of the succession of Quaternary ice ages. 7) A model of future climate based on the observed orbital-climate relationships, but ignoring anthropogenic effects, predicts that the long-term trend over the next sevem thousand years is toward extensive Northern Hemisphere glaciation.     

小波多速率调制同步系统的FPGA实现

以FPGA为平台,提出了一种小波多速率调制同步系统的硬件实现方案。利用最大似然估计算法,采取帧同步与载波相位恢复相结合的方式,解决了小波调制在同步上对定时误差敏感等问题,同时也可以对假同步进行检测和纠正。仿真结果证明了该方案的可行性和有效性。     

Amygdalar and hippocampal theta rhythm synchronization during fear memory retrieval

The amygdalohippocampal circuit plays a pivotal role in Pavlovian fear memory. We simultaneously recorded electrical activity in the lateral amygdala (LA) and the CA1 area of the hippocampus in freely behaving fear-conditioned mice. Patterns of activity were related to fear behavior evoked by conditioned and indifferent sensory stimuli and contexts. Rhythmically synchronized activity at theta frequencies increased between the LA and the CA1 after fear conditioning and became significant during confrontation with conditioned fear stimuli and expression of freezing behavior. Synchronization of theta activities in the amygdalohippocampal network represents a neuronal correlate of conditioned fear, apt to improve neuronal communication during memory retrieval.     

窖藏方法对树莓花期调节及杂交效果的影响

试验于2009年11月初取田间牛叠肚植株进行假植,剪留株高1 m,放入地下窖内湿沙覆盖,2010年5月初移出窑外定植于自然温度环境中正常栽培管理.结果表明,牛叠肚初花期推迟2~3 d,末花期推迟9 d,实现与栽培品种花期重叠1~7 d,解决父母本花期不相遇问题.常规条件下,4个栽培树莓品种美国22号、哈瑞太慈、胜利和秋福为母本与2个牛叠肚株系SM5、SM6杂交结实率为48.7%~88.0%.采用地下窖藏处理后,以牛叠肚不同株系为母本和栽培树莓为父本时杂交效果表现差异,SM6为母本杂交亲和性好,杂交结实率为42.8%~93.7%;SM5为母本与栽培树莓品种的杂交亲和性差,除SM5×胜利杂交结实率为12.7%,其他组合结实率为0.     

应用生殖激素对小尾寒羊同期发情效果研究

应用羊用孕酮栓、孕马血清促性腺激素和氯前列烯醇相结合的方法对 99只空怀小尾寒羊和 36只哺乳母羊 (产后 2 5～ 35d)进行同期发情试验研究。结果表明 ,99只空怀母羊在 2 4h内的同期发情率达到 81 8% ,4 8h内为 89 9%。孕酮栓在空怀母羊阴道内埋置不同时间 (12d与 14d)的同期发情率无显著差异 (P >0 0 5 ) ;对空怀母羊注射不同剂量 (330IU/只和 2 5 0IU/只 )孕马血清促性腺激素对羊的同期发情率的影响无显著差异 (P >0 0 5 )。 36只哺乳母羊在 2 4h与 4 8h内的同期发情率均为 80 6 % (2 9/36 ) ,对哺乳母羊注射孕马血清促性腺激素 2 5 0IU/只的同期发情率为 90 0 % (18/2 0 ) ,优于注射 330IU/只的同期发情率 6 8 8% (11/16 )。     

回转式精准同步穴注水机构的设计与试验研究

移栽后注水能够缩短钵苗的生长周期,且能起到抗旱保苗效果。传统的灌溉方式需水量大,造成水资源浪费。以玉米钵苗为研究对象,通过玉米钵苗土槽试验,确定单株钵苗的注水量100 m L以上。结合单株钵苗的注水量与本课题组正在开发的旱田钵苗移栽机构特点,设计一种穴注水机构及其试验台,并对穴注水机构出水口的运动轨迹进行分析。该机构最突出的特点是内腔不动,外腔旋转,且内腔设计一个扇形槽口,使该机构能同时对准前后两个穴口注水。选取出水口内径、电机转速和水箱液面高度为主要影响因子,水量为考核指标,进行单因素试验和正交试验。结果表明,当出水口内径16 mm,电机转速288 r·min-1水箱液面高度32 cm,注水量最大为156 m L。研究结果可为旱田钵苗移栽穴注水装备的研制提供技术依据。     

不同处理方法对徐淮白山羊同期发情的效果

以徐淮白山羊为对象,设计了3种不同的短期同期发情处理方法,对同期发情率、发情后卵巢状态观察及情期受胎率进行了统计分析与评价.结果表明:组1(CIDR+PG+PMSG)和组3(PG+PMSG)的同期发情率分别为82.5%,82%,显著高于组2(PG+三合激素)(P<0.05);组1处理后发情羊的卵巢状态明显优于其他2组;而且组1的情期受胎率也显著高于组2和组3(P<0.05).综上可见,CIDR + PG + PMSG是徐淮白山羊最有效的短期同期发情处理方法.     

基于JMS的森林资源分布式异构数据库间数据同步的研究

针对分布式网络环境下异构数据库间数据同步的问题,提出了一种基于JMS的数据同步方法,并对该方法实现过程中涉及到的关键技术进行了研究。     

凤仙根尖细胞有丝分裂同步化诱导

为了简易快速地获得大量凤仙有丝分裂中期染色体,采用羟基脲和氟乐灵结合的双阻断法对凤仙根尖进行处理,诱导根尖细胞有丝分裂中期同步化.结果表明,以1.25 mmol/L羟基脲处理16 h,1 μmol/L氟乐灵处理4 h,细胞有丝分裂中期指数可达60%以上.有丝分裂正常,未见染色体畸变现象.     

基于数字高程模型的森林火灾远程视频同步跟踪算法

根据手电筒光束照射障碍物形成光圈的过程和摄像机的参数建立摄像机视域的数学模型,利用Janus算法．对视域中心点坐标进行求解;利用圆的正多边形逼近算法,对过视域中心点且垂直于中心视线的平面的边界点坐标进行求解;再次利用Janus算法,提取摄像机视域在数字高程模型上的对应边界点;最后,以浙江省临安市三桥乡的数字高程模型数据为基础,编程实现此算法,并旋转摄像机进行同步跟踪试验。结果表明：该算法能够实现摄像机视域与数字高程模型的同步跟踪显示,从而实现了视频监控技术与地理信息系统技术的信息联动。图6参14     

湖羊同期发情与杜泊绵羊人工授精技术

本试验设计了5种不同的同期发情方法对300只湖羊进行处理,对湖羊同期发情技术进行了系统研究。并采用杜泊绵羊鲜精人工授精技术对同期发情羊群进行集中杂交配种,对不同处理羊群的同期发情率、人工授精受胎率进行了统计分析与评价。