Attentional modulation of neural processing of shape, color, and velocity in humans

Positron emission tomography (PET) was used to measure changes in regional cerebral blood flow of normal subjects, while they were discriminating different attributes (shape, color, and velocity) of the same set of visual stimuli. Psychophysical evidence indicated that the sensitivity for discriminating subtle stimulus changes was higher when subjects focused attention on one attribute than when they divided attention among several attributes. Correspondingly, attention enhanced the activity of different regions of extrastriate visual cortex that appear to be specialized for processing information related to the selected attribute.     

Sodium- and potassium-sensitive glass electrodes for biological use

Continuous, accurate recording in circulating fluids from a sodium and a potassium electrode is described. The Na electrode is capable of discriminating Delta[Na(+)] of less than 1 meq/lit. in 140 meq/lit., and the K electrode is capable of discriminating Delta[K(+)] of less than 1 meq/lit. in the range of 1 to 10 meq/lit. with good reproducibility. The electrodes may be used singly or in pairs with a common reference calomel electrode for simultaneous monitoring of A [Na(+) 1 and Delta[K(+)] in mixed solutions. Problems of streaming potential dependent on flow rate and electrode shape, as well as transient K(+) response by the Na electrode, are discussed.     

Recognition of cognate transfer RNA by the 30S ribosomal subunit

Crystal structures of the 30S ribosomal subunit in complex with messenger RNA and cognate transfer RNA in the A site, both in the presence and absence of the antibiotic paromomycin, have been solved at between 3.1 and 3.3 angstroms resolution. Cognate transfer RNA (tRNA) binding induces global domain movements of the 30S subunit and changes in the conformation of the universally conserved and essential bases A1492, A1493, and G530 of 16S RNA. These bases interact intimately with the minor groove of the first two base pairs between the codon and anticodon, thus sensing Watson-Crick base-pairing geometry and discriminating against near-cognate tRNA. The third, or "wobble," position of the codon is free to accommodate certain noncanonical base pairs. By partially inducing these structural changes, paromomycin facilitates binding of near-cognate tRNAs.     

近而能远——对外汉语教学中同义词教学新解

依据对外汉语教学的特点,结合前人的研究成果,对同义词教学的相关问题进行了系统性的探讨,在同义词的教学原则及辨析方法等问题的论述上有所创新。明确提出了同义词教学应遵循的冷热分频、结合语境及从易从简从系统这三个原则;辨析方面,在遵循现代汉语研究中常规辨析方法的基础上,强调文化阐释及汉外对比的重要性。     

Top-down versus bottom-up control of attention in the prefrontal and posterior parietal cortices

Attention can be focused volitionally by "top-down" signals derived from task demands and automatically by "bottom-up" signals from salient stimuli. The frontal and parietal cortices are involved, but their neural activity has not been directly compared. Therefore, we recorded from them simultaneously in monkeys. Prefrontal neurons reflected the target location first during top-down attention, whereas parietal neurons signaled it earlier during bottom-up attention. Synchrony between frontal and parietal areas was stronger in lower frequencies during top-down attention and in higher frequencies during bottom-up attention. This result indicates that top-down and bottom-up signals arise from the frontal and sensory cortex, respectively, and different modes of attention may emphasize synchrony at different frequencies.     

六倍体小黑麦染色体的荧光原位杂交分析

采用基因组原位杂交(GISH)和荧光原位杂交(FISH)技术对六倍体小黑麦进行了研究,以鉴定其含有的黑麦染色体的数目和结构特点,了解小黑麦基因组组成,为其在小麦遗传育种中的应用提供参考.分别以黑麦基因组DNA及pSc200和pSc250探针进行顺序GISH-FISH分析,结果显示该小黑麦含有21对染色体,来源于黑麦的2对染色体的长臂端部出现pSc200和pSc250信号,而另外5对染色体的两端部都有该信号.以Oligo-pSc119.2-1,pSc200和pSc250探针对小黑麦进行了双色FISH分析,发现小黑麦的Oligo-pSc119.2-1信号与黑麦基本相似,而pSc200和pSc250信号与黑麦的差异较大.以黑麦基因组DNA及Oligo-pAs1-1和Oligo-pSc119.2-1为探针对小黑麦进行顺序GISH-FISH分析,鉴定其基因组组成为AABBRR;同时发现小黑麦染色体的一些FISH信号发生了变化,其原因可能是小黑麦形成过程中染色体结构发生了改变,从而导致小黑麦的DNA重复序列呈现多态性.     

非变性原位杂交技术在芝麻染色体识别上的探索与应用

【目的】研究和确定芝麻ND-FISH最优试验条件,并对其在芝麻染色体识别中的可行性进行探索。【方法】以寡聚核苷酸(AC)8为探针,研究不同洗脱强度、酶解时间和杂交时间对ND-FISH的影响,确定芝麻ND-FISH最优试验方案。【结果】芝麻ND-FISH最优方案：制片在浓度100 μg•mL-1 RNase A酶解1 h,探针浓度6 µL（20 ng•µL-1）,杂交4 h,4 × SSC/0.2% Tween 20溶液洗脱10 min;18条染色体存在(AC)8杂交信号,其中,14条染色体上存在较强杂交信号,4条染色体上有较弱杂交信号,结合染色体长度及臂比,18条染色体可有效识别。【结论】利用ND-FISH技术、以(AC)8为探针成功识别栽培芝麻的18条染色体。     

A Semiconductor-Based Photonic Memory Cell

Photonic signals were efficiently stored in a semiconductor-based memory cell. The incident photons were converted to electron-hole pairs that were locally stored in a quantum well that was laterally modulated by a field-effect tunable electrostatic superlattice. At large superlattice potential amplitudes, these pairs were stored for a time that was at least five orders of magnitude longer than their natural lifetime. At an arbitrarily chosen time, they were released in a short and intense flash of incoherent light, which was triggered by flattening the superlattice amplitude.     

Cloning and expression of a Xenopus embryonic gap junction protein

Gap junctions in the early amphibian embryo may play a fundamental role in the regulation of differentiation by mediating the cell-to-cell transfer of chemical signals. A complementary DNA encoding a gap junction present in Xenopus oocytes and early embryos has now been cloned and sequenced. This protein sequence is homologous to the well-characterized gap junction structural proteins rat connexin32 and connexin43. RNA blot analysis of total Xenopus oocyte RNA showed hybridization to a single 1.6-kilobase band. This messenger RNA is abundant in oocytes, decreases to levels below the sensitivity of our assay by stage 15 (18 hours), and is not detectable in RNA from a number of adult organs. To confirm that the oocyte cDNA encodes a gap junction channel, the protein was over expressed in Xenopus oocytes by injection of RNA synthesized in vitro. Pairs of RNA-injected oocytes formed many more time- and voltage-sensitive cell-cell channels than water-injected pairs.     

利用RGA-PCR方法进行水稻抗瘟基因分子标记

用28对RGA引物对LTH近等基因系品种进行PCR扩增，其中11对引物扩增出特异性条带。将扩增到的33个特异性片段回收并进行重扩增，有11个片段产生单一条带。选择2个片段HS-1和HS-19进行探针标记。经Southern杂交发现。探针HS-1在含有Pi—ta^2抗瘟基因品种F-128—1、NO4中有特异杂交信号，表明该片段可能与抗瘟基因Pi—ta^2连锁或是其一部分。对特异性片段HS-1进行克隆、测序，全长为478bp，与Mago等从水稻中克隆的一个抗病基因同源序列RGA29有95％同源性。     

建立一个重组自交系群体所需的自交代数(英文)

在数量性状基因定位研究中，重组自交系是一种比较有用的群体。但建立一个重组自交系群体通常是很费时的。本文讨论了就某一物种的特定杂交组合而言，建立一个重组自交系群体所需的自交代数，并提出了估计所需自交代数的方法。数值分析表明，即使将每条染色体当作１个分离单位的话，建立一个重组自交系群体所需的自交代数也比通常认为的来得多（例如，对于一个具有１０对同源染色体的物种而言，至少需要自交１１代）。因此，这在实际研究中应引起注意     

拟斯卑尔脱山羊草的FISH核型分析

【目的】建立拟斯卑尔脱山羊草的FISH核型,分析明确不同来源拟斯卑尔脱山羊草的FISH核型特点,比较不同拟斯卑尔脱山羊草及其与普通小麦的FISH核型差异。【方法】以荧光标记的寡核苷酸Oligo-pTa535和Oligo-pSc119.2为探针,利用荧光原位杂交(fluorescence in situ hybridization,FISH)技术分析pTa535和pSc119.2在不同拟斯卑尔脱山羊草、四倍体小麦和普通小麦染色体上的杂交信号分布特点;以禾本科植物着丝粒专化寡核苷酸Oligo-CCS1为探针,明确拟斯卑尔脱山羊草的着丝粒位置,测量拟斯卑尔脱山羊草染色体相关参数;通过FISH核型比较明确不同拟斯卑尔脱山羊草及其与小麦核型的多态性差异。【结果】Oligo-pTa535主要分布在小麦的D和A组染色体上,在小麦的B组染色体上仅有零星分布,在5份拟斯卑尔脱山羊草的染色体中未显示Oligo-pTa535杂交信号。Oligo-pSc119.2杂交信号主要分布在小麦的B组染色体上,在小麦的A、D组染色体中分布较少,但在5份拟斯卑尔脱山羊草染色体上均有广泛分布。根据Oligo-pTa535和Oligo-pSc119.2杂交信号在小麦染色体上的分布特点,可以将小麦的不同染色体相互区分开来。Oligo-pSc119.2杂交信号在不同倍性、不同品种的小麦B组染色体上的分布特点基本相似,而不同来源拟斯卑尔脱山羊草的Oligo-pSc119.2的FISH核型差异较大,甚至在同一细胞内的2条同源染色体上Oligo-pSc119.2杂交信号的分布也具有明显差异。不同来源的拟斯卑尔脱山羊草与小麦B染色体组的FISH核型存在明显差异。PI542238的7对染色体均为中间着丝粒染色体,核型公式为2n=14=14m。其余4份拟斯卑尔脱山羊草的4S染色体均为近中着丝粒染色体,其余染色体均为中间着丝粒染色体,核型公式皆为2n=14=12m+2sm。【结论】拟斯卑尔脱山羊草染色体上含有丰富的与pSc119.2高度同源的重复序列,不含有与pTa535高度同源的重复序列。不同来源的拟斯卑尔脱山羊草之间以及同一来源的拟斯卑尔脱山羊草的个体间甚至同一个体内的同源染色体间在pSc119.2的分布上均具有遗传多样性。以Oligo-pSc119.2为探针建立的拟斯卑尔脱山羊草染色体FISH核型与小麦B组染色体的核型具有显著差异。利用荧光标记的Oligo-pTa535和Oligo-pSc119.2为探针进行FISH分析,可以准确区分拟斯卑尔脱山羊草的不同染色体,并能将拟斯卑尔脱山羊草与小麦的染色体区分开来。     

串联重复序列在籼粳亚种间的差异及其与栽培稻遗传分化关系的研究

以中籼稻南京11号(N11)和粳稻巴利拉(Balilla)杂交F1代的DH群体为材料，利用荧光原位杂交技术(FISH)结合程氏指数分类，分析2个串联重复序列Os48、45S rDNA在DH群体中的分布，探讨串联重复序列在栽培稻籼、粳亚种间的差异及其与栽培稻遗传分化的关系。结果表明：串联重复序列45S rDNA在DH群体中的分布具有明显的籼、粳特异性；Os48在DH群体中的分布趋势与程氏指数的分类结果一致，而杂交信号为2对的6个DH株系都表现为粳型，利用减数分裂的粗线期染色体进行分析，这6个株系的Os48所在染色体均为第5、6号。从本研究结果可知，串联重复序列Os48、45S rDNA与栽培稻遗传分化有较密切的关系，可作为研究籼、粳分化的标记。     

生态环境变化趋势的物元可拓识别法

为了建立森林火灾后生态变化趋势的分类识别模型 ,在确定判别指标及分类标准的基础上 ,针对火灾后生态变化遥感监测资料和调查信息的复杂性以及单因素识别与类别划分结果之间的不相容性特点 ,应用物元可拓集方法 ,构造物元矩阵 ,根据计算出的关联度值大小对森林火灾后生态变化趋势进行可拓识别。实例分析表明 ,物元可拓法应用于森林生态变化趋势识别结果与实际调查结果基本吻合。     

转基因大豆、玉米、水稻深加工产品的五重巢式 PCR技术检测

本试验针对已商品化的转基因大豆、玉米和水稻的主要外源基因Cry1A(B)基因、BAR基因、CP4-EPSPS基因和PAT基因及共有的内标准基因RBCL基因设计了10对引物,对从超市购买的进口大豆、玉米和水稻的11种深加工制品(未标注是否含有转基因成分)进行了五重巢式PCR定性检测。第1轮普通五重PCR检测,11个待测样品均未出现任何转基因成分,其灵敏度为0.5%;第2轮将普通五重PCR扩增产物进行五重巢式PCR检测,结果在卵磷脂、大豆蛋白质粉、巧克力饮品和婴儿米粉中扩增出RBCL基因,玉米淀粉和玉米泥中扩增出RBCL基因、Cry1A(B)基因和PAT基因;玉米蛋白粉扩增出RBCL基因、Cry1A(B)基因和BAR基因,营养麦片扩增出内参RBCL基因和Cry1A(B)基因,在大豆精炼油、色拉油和玉米油中未检测出上述2种基因和另外3种外源基因CP4-EPSPS、BAR和PAT,其检测灵敏度为0.005%。结果提示,五重巢式PCR检测方法适用于转基因大豆、玉米和水稻深加工产品的定性检测。     

绿豆高密度分子遗传图谱的构建

【目的】在前期研究的基础上,进一步利用绿豆基因组SSR、EST-SSR、STS和普通菜豆基因组SSR等标记构建绿豆遗传连锁图谱,为绿豆重要性状相关基因的定位、克隆及分子标记辅助选育新品种等研究搭建技术平台。【方法】利用澳大利亚引进的Berken（高感豆象绿豆栽培种）× ACC41（高抗豆象绿豆野生种）及其重组自交系（recombinant inbreed line,RIL）群体,对6 686对引物进行PCR扩增及多态性筛选,包括6 100对绿豆基因组SSR、149对EST-SSR、13对STS和424对普通菜豆基因组SSR引物,将亲本间多态性引物,进一步分析重组自交系群体。结合前期研究的分子标记数据,利用Mapmarker/Exp 3.0软件构建遗传图谱,并设置LOD≥3.0,最大图距50.00 cM。用Joinmap 4.0软件进行图谱整合。【结果】用2个亲本共筛选了6 686对SSR引物,共有3 691对引物有稳定的扩增产物,得到有多态的引物有588对。其中,通过磁珠富集法开发的绿豆SSR引物6 100对,有效扩增3 459对,有效扩增率56.7%,得到多态性引物559对;通过转录组测序开发的绿豆MGCP引物149对,有效扩增126对,有效扩增率84.6%,得到多态性引物21对;通过磁珠富集法开发的菜豆SSR引物424对,有效扩增97对,有效扩增率22.9%,得到多态性引物6对;绿豆STS引物13对,有效扩增9对,有效扩增率69.2%,得到多态性引物2对。表明不同来源和种类的SSR引物在RIL群体亲本中的有效扩增率有明显差别,绿豆EST-SSR引物（84.6%）最高,绿豆STS引物（69.2%）和SSR引物（55.7%）次之,菜豆SSR引物（22.9%）最低。获得一张含有585个标记（499个SSR标记、74个RFLP标记、9个STS标记和3个RAPD标记）的绿豆遗传图谱,图谱总长732.9 cM,包括11个连锁群,每个标记间的平均距离为1.25 cM,平均长度为66.63 cM。每个连锁群长度为45.2-112.8 cM,每条染色体上面的标记数为35-92个,平均53.18个。标记位点数最多的连锁群LG1含92个标记,长度为112.8 cM;标记位点数最少的连锁群LG11仅含有35个标记,长度为48.7 cM。对图谱的585个标记位点进行χ2测验,在P＜0.05和P＜0.01条件下,分别有79个和151个标记表现为偏分离,占总标记位点数的39.3%。【结论】构建了一张目前国内外发表的标记数最多、密度最高的绿豆遗传连锁图谱。     

Relevance of sink-size estimation for within-field zone delineation in vineyards

Source to sink size ratio, i.e.: the relative abundance of photosynthetically active organs (leaves) with regards to photosynthate demanding organs (mainly bunches), is widely known to be one of the main drivers of grape oenological quality. However, due to the difficulty of remote sink size estimation, Precision Viticulture (PV) has been mainly based on within-field zone delineation using vegetation indices. This approach has given only moderately satisfactory results for discriminating zones with differential quality. The aim of this work was to investigate an approach to delineate within-vineyard quality zones that includes an estimator of sink size in the data-set. The study was carried out during two consecutive seasons on a 4.2 ha gobelet-trained cv. ‘Tempranillo’ vineyard. Zone delineation was performed using Normalized Difference Vegetation Index (NDVI), soil apparent electrical conductivity (EC_a) and bunch number (BN) data. These variables were considered separately, in pairs, or the three altogether, using fuzzy k-means cluster analysis for combinations. The zones delineated based on single variables did not allow a sufficient discrimination for grape composition at harvest, NDVI being the only variable that by itself resulted in zones that to some extent differed in grape composition. On the contrary, when two variables were combined, discrimination in terms of grape composition improved remarkably, provided the sink size estimation variable (BN) was included in the combination. Lastly, the combination of the three variables yielded the best discriminating zoning, improving slightly on those provided by NDVI + BN and EC_a + BN combinations. Thus, the relevance of including a variable related to sink size (in this case the number of bunches per plant) has been confirmed, which makes its consideration highly advisable for any PV work aiming at zone delineation for grape quality purposes.     

基于高SBS阈值的HNLF产生高重复频率超短光脉冲

基于光纤中的四波混频(FWM)产生高重复频率超短光脉冲的原理,并为抑制光纤中的受激Brillouin散射(SBS),采用非均匀掺杂高SBS阈值非线性光纤,通过FWM对双拍频信号进行整形压缩,实验上获得了100GHz的高重复率超短光脉冲序列,进而分析了入纤功率对输出光脉冲的影响。     

MR水成像技术在聚丙烯酰胺水凝胶注射隆胸术后的应用和临床价值

目的探讨MR水成像技术对聚丙烯酰胺水凝胶（PAHG）注射隆乳术后的MRI表现及其应用价值。方法回顾性分析55例PAHG注射隆乳者的乳腺MRI及MR水成像技术的临床资料。结果55例110只乳房MRI常规检查显示：PAHG于T2WI呈高信号,T1WI呈低信号;PAHG周围见低信号包膜样结构影;MR水成像技术图像显示PAHG呈显著高信号,周围皮肤、皮下脂肪、乳腺腺体、肌肉、胸膜及肋骨组织均被抑制,呈低信号表现,PAHG假体可三维立体显示。结论MR水成像技术能对PAHG注射隆乳术后的性状有准确的判断,有较高的诊断价值和临床指导意义。