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31.
This research develops a methodology that helps actors in understanding information generated from multiple construction participants. It employs semiotic theory which approaches the interpreter’s understanding of the role of the representations used in construction documents to communicate meanings to other participants. This strategy is designed to aid the interpreters’ comprehension of the use of symbols. The symbols within the construction documents are forms of representations that take the form of a visual representation of a set of markers that describe a formal language, and of markers that are used to represent natural language as well as other possible representations, such as a collection of codes for indexing documents. Symbols are replaced by signs under the semiotics theory. The use of symbols as signs is this study’s recognition of the relationship between the interpreter and the material quality of symbols. The semiotic analysis is an examination of the compromise between the meanings of a representation per se and the concept associated with the understanding of such representation. 相似文献
32.
Raja Parasuraman 《自然科学进展》2007,17(13):7-18
Molecular genetics can provide complementary information to neuroimaging methods on the neural mechanisms of perception and cognition. We investigated the role of cholinergic and neurotrophic genes in the modulation of visual attention, as reflected in behavioral, ERP, and MRI measures. Three studies examined the influence of single nucleotide polymorphisms (SNPs) in a nicotinic cholinergic gene, CHRNA4, and a neurotrophic gene, APOE. An association was found between a CHRNA4 SNP and reaction time (RT) measures of orienting of visual attention in space. This behavioral finding was complemented by an association between the same SNP and ERP components reflecting early perceptual/attentional processing. In contrast to these relatively specific effects, the APOE e4 SNP had broad effects on cognition, including visual attention and working memory. An interaction was also found between APOE and CHRNA4 for white matter volume and RT measures of attentional efficiency. These studies confirm the role of nicotinic cholinergic innervation for visual attention and show the benefits of a “multi-level phenotyping” approach in the neurogenetics of attention. 相似文献
33.
Harsha HC Suresh S Amanchy R Deshpande N Shanker K Yatish AJ Muthusamy B Vrushabendra BM Rashmi BP Chandrika KN Padma N Sharma S Badano JL Ramya MA Shivashankar HN Peri S Choudhury DR Kavitha MP Saravana R Niranjan V Gandhi TK Ghosh N Chandran S Menezes M Joy M Mohan SS Katsanis N Deshpande KS Raghothama C Prasad CK Pandey A 《Nature genetics》2005,37(4):331-332
34.
Human ES-cell-derived cardiomyocytes electrically couple and suppress arrhythmias in injured hearts 总被引:1,自引:0,他引:1
Y Shiba S Fernandes WZ Zhu D Filice V Muskheli J Kim NJ Palpant J Gantz KW Moyes H Reinecke B Van Biber T Dardas JL Mignone A Izawa R Hanna M Viswanathan JD Gold MI Kotlikoff N Sarvazyan MW Kay CE Murry MA Laflamme 《Nature》2012,489(7415):322-325
Transplantation studies in mice and rats have shown that human embryonic-stem-cell-derived cardiomyocytes (hESC-CMs) can improve the function of infarcted hearts, but two critical issues related to their electrophysiological behaviour in vivo remain unresolved. First, the risk of arrhythmias following hESC-CM transplantation in injured hearts has not been determined. Second, the electromechanical integration of hESC-CMs in injured hearts has not been demonstrated, so it is unclear whether these cells improve contractile function directly through addition of new force-generating units. Here we use a guinea-pig model to show that hESC-CM grafts in injured hearts protect against arrhythmias and can contract synchronously with host muscle. Injured hearts with hESC-CM grafts show improved mechanical function and a significantly reduced incidence of both spontaneous and induced ventricular tachycardia. To assess the activity of hESC-CM grafts in vivo, we transplanted hESC-CMs expressing the genetically encoded calcium sensor, GCaMP3 (refs 4, 5). By correlating the GCaMP3 fluorescent signal with the host ECG, we found that grafts in uninjured hearts have consistent 1:1 host–graft coupling. Grafts in injured hearts are more heterogeneous and typically include both coupled and uncoupled regions. Thus, human myocardial grafts meet physiological criteria for true heart regeneration, providing support for the continued development of hESC-based cardiac therapies for both mechanical and electrical repair. 相似文献
35.
从原理和实验2方面对基于MapReduce和Spark的大数据模糊K-均值算法进行分析比较,并对2种大数据开源平台的优缺点进行了总结.由于模糊K-均值算法是一种迭代算法,需要对部分数据进行重复操作以得到最终聚类结果,因此主要从算法执行时间、同步次数、文件数目、容错性能、资源消耗这5方面进行比较,得出的结论对从事大数据研究的人员具有较高的参考价值. 相似文献
36.
储层条件下砂岩岩心驱替实验方法研究 总被引:2,自引:0,他引:2
岩石电性数据是油田含油饱和度和储量评估的关键参数,实验方法对岩石电性数据测定的准确性具有很大影响.在储层条件(储层温度、压力)下,采用常规法和隔板法两种驱替方式,对玉门油田某区8块砂岩样品进行岩心驱替实验.实验结果表明,相对于常规法,隔板法能够使岩心达到更低的束缚水饱和度;常规驱替方法会产生末端效应,岩心内饱和度分布不均匀,隔板法可以避免末端效应;在同一饱和度状态下,隔板法测得的岩心电阻率、电阻率系数和饱和度指数n低于常规驱替方法测得的数据,不同驱替方式造成的流体分布形式的差别是导致实验结果不一致的原因.虽然隔板法能够得到较好的岩石电性数据,但是实验周期比较长. 相似文献
37.
Li W Bloom JS Podsiadlowski P Miller AA Cenko SB Jha SW Sullivan M Howell DA Nugent PE Butler NR Ofek EO Kasliwal MM Richards JW Stockton A Shih HY Bildsten L Shara MM Bibby J Filippenko AV Ganeshalingam M Silverman JM Kulkarni SR Law NM Poznanski D Quimby RM McCully C Patel B Maguire K Shen KJ 《Nature》2011,480(7377):348-350
Type Ia supernovae are thought to result from a thermonuclear explosion of an accreting white dwarf in a binary system, but little is known of the precise nature of the companion star and the physical properties of the progenitor system. There are two classes of models: double-degenerate (involving two white dwarfs in a close binary system) and single-degenerate models. In the latter, the primary white dwarf accretes material from a secondary companion until conditions are such that carbon ignites, at a mass of 1.38 times the mass of the Sun. The type Ia supernova SN 2011fe was recently detected in a nearby galaxy. Here we report an analysis of archival images of the location of SN 2011fe. The luminosity of the progenitor system (especially the companion star) is 10-100 times fainter than previous limits on other type Ia supernova progenitor systems, allowing us to rule out luminous red giants and almost all helium stars as the mass-donating companion to the exploding white dwarf. 相似文献
38.
Summary Seeds ofCapsicum annuum L. cultivar cerasiformies were treated with 0.4 and 0.2% aqueous colchicine solution for 24 and 72 h respectively. Tetraploids were not realized; instead, interchange heterozygosity was observed in several plants in 0.4% treatment. The interchanges varied from 1 to 3 per plant. It is presumed that colchicine has induced chromosome breaks. 相似文献
39.
Summary The present report deals with the effect of excessive ingestion of fluoride on glycosaminoglycan (GAG). Increase in fluoride deposition in bone, and in circulating levels of fluoride in serum, are also reported. Among the 3 constituents of GAG investigated; hexosamine, uronic acid and sulphate, the content remained unaltered except for sulphate.Acknowledgment. The authors wish to acknowledge the Department of Science and Technology (DST), Government of India, for the financial aid. One of us (M.J.) acknowledges the receipt of a Junior Research Fellowship from DST, during the tenure of which the investigations were carried out. 相似文献
40.