Effect of practice versus information on the visual illusion

Objective The Müller-Lycr illusion is a visual illusion in which a horizontal shaft with an inward-pointing chevron （fins-out） affixed to each end is perceived longer than a shaft with outward-pointing chevrons （fins-in）. The goal of this study was to compare the effects of experience and knowledge about the Müller-Lyer illusion on participants＇ perceptual precision. Method Participants were undergraduate students （n = 108） who were not familiar with the Müller-Lyer illusion prior to the experiment. The task of participants was to adjust one movable line to make it equal to the other in Müller-Lyer figure. They received ascending and descending Müller-Lyer trials in three blocks with 20 trials each. The Experimental Group received information about the Müller-Lyer illusion prior to the third block. Results For the Experimental Group, the amount of departure in Block 3 was reduced significantly compared with previous blocks. Conclusion Knowledge about the mechanisms underlying visual illusions may play an important role in helping individuals overcome them.

纳米尺度NiLa_2O_4尖晶石催化NaBH_4还原亚胺制仲胺（英文）

由溶胶-凝胶法制得的Ni-La化合物经热分解制备了纳米尺度NiLa2O4尖晶石,在750o C焙烧后形成了结晶良好的尖晶石结构.采用差热分析、X射线衍射、透射电镜、扫描电镜和粒度分布分析等手段表征了该尖晶石的物理化学性质.结果表明,该纳米颗粒有规则的外形和确定的晶面,由平均粒径为40 nm的规整半球晶粒组成.精修的晶胞参数a=3.861205和c=12.6793.在NaBH4选择还原亚胺制相应仲胺的反应中,该新型纳米NiLa2O4尖晶石可用作高效多相催化剂,得到了较高的产物产率.所有反应可在室温和相对较短的时间内完成.在优化的反应条件下,均可得到带有不同芳基的,包括带有吸电子和供电子基团的仲胺.该催化剂回收简便,重复使用4次,其催化活性未见明显下降.

τ-可测算子迹的不等式(英文)

设m是具有忠实正规半有限迹τ的Hilbert空间上的一个半有限von Neumann代数.隶属于m的—个闭稠定算子x称为τ可测,如果存在常数λ≥0使得τ(e^(|x|)(λ,∞))<∞.将一些很有用的已知的Hilbert空间算子迹的不等式推广到τ-可测算子迹.特别是这些不等式蕴涵了n-元τ-可测算子的Clarkson不等式.同时还给出了τ-可测算子的广义平行四边形法则.

非政府组织在天文学科普方面的作用

古代伊朗科学家曾对科学,特别是天文学做出过重大贡献。当代的伊朗科学家继承了这一传统,并致力于向公众传播科学。21世纪初,由一批科学家、热心科学传播的社会人士和私营企业组成的非政府组织积极筹建马什哈德天文馆、科学中心等科普场馆。本文通过这一案例,讨论了非政府组织在科普场馆建设和科学传播中的作用、问题和可行性,并介绍了马什哈德天文学会为此采取的相应对策。