有基本流动的渠道中的孤立波

<正> 迄今为止,大多数关于渠道中的孤立波的研究都作了静水的假定,从而避免了波与流相互作用的难题。但在自然界的江河中大都有基本流动,这就要求我们研究有基本流动情况下渠道中的孤立波。Benjamin,Peters,Turpin等人先后在这方面做了一些工作。 我们研究无粘、不可压缩流体的运动,基本流动沿着渠道方向,渠道断面及坐标如图

Split-aperture laser pulse compressor design tolerant to alignment and line-density differences

We introduce a four-pass laser pulse compressor design based on two grating apertures with two gratings per aperture that is tolerant to some alignment errors and, importantly, to grating-to-grating period variations. Each half-beam samples each grating in a diamond-shaped compressor that is symmetric about a central bisecting plane. For any given grating, the two half-beams impinge on opposite sides of its surface normal. It is shown that the two split beams have no pointing difference from paired gratings with different periods. Furthermore, no phase shift between half-beams is incurred as long as the planes containing a grating line and the surface normal for each grating of the pair are parallel. For grating pairs satisfying this condition, gratings surfaces need not be on the same plane, as changes in the gap between the two can compensate to bring the beams back in phase. © 2008 Optical Society of America.

Non-invasive methods for identifying oocysts of Sarcocystis spp. from definitive hosts

Because the excreted sporocysts and/or oocysts of various species of Sarcocystis may not be discriminated morphologically, we sought to validate a diagnostic technique based on variation in the 18S rDNA sequence. Oocysts and/or sporocysts; from three taxa

Unexpected promotion of Au/TiO2 by nitrate for CO oxidation

The catalytic activity for Au/TiO2 for CO oxidation can be significantly enhanced by the addition of nitrates and this may relate to the variable catalyst performance observed in many studies.