多视点学习条件下场景内在参照系的建立

The aim of the present study was to investigate whether people can establish two oblique spatial reference directions to represent objects’ locations in memory. Participants learned a layout of objects from two oblique viewpoints (0º and 225º) and made judgments of relative direction (“Imagine you are standing at X, facing Y, please point to Z”). Experiments 1 to 3 showed that performance in pointing were better at either one of the familiar imagined headings (0º and 225º) in most of the participants even when they were instructed to learn the layout along their actual heading at both learning directions, and when their actual headings at the test were the same as the imagined headings. Experiments 4 to 6 showed performance in pointing could be equivalent at the two familiar imagined headings for significant number of the participants when participants learned two different set of objects occupied at the same locations from the two learning viewpoints, and when participants learned the same layout of objects together with two different layouts from the two learning viewpoints. These results suggest that the orientation dependent performance in Experiments 1 to 3 cannot be attributed to the possibility that participants had formed two oblique spatial reference directions during learning but only used one of them during testing. Experiments 7 and 8 further showed that the performance of pointing at the two familiar viewpoints were significantly different when participants experienced one viewpoint by learning the actual layout and the other viewpoint by learning the map of the same layout, and when participants experienced two viewpoints alternatively over the ten times of learning sessions. All these results strongly suggest that people establish only one spatial reference system to represent locations of objects when they learn the same layout in the same background from two oblique viewpoints.

Modification of a poly(methyl methacrylate) injection-molded microchip and its use for high performance analysis of DNA

Inexpensive and permanently modified poly(methyl methacrylate)(PMMA) microchips were fabricated by an injection-molding process. A novel sealing method for plastic microchips at room temperature was introduced. Run-to-run and chip-to-chip reproducibility was good, with relative standard deviation values between 1-3% for the run-to-run and less than 2.1% for the chip-to-chip comparisons. Acrylonitrile-butadiene-styrene (ABS) was used as an additive in PMMA substrates. The proportions of PMMA and ABS were optimized. ABS may be considered as a modifier, which obviously improved some characteristics of the microchip, such as the hydrophilicity and the electro-osmotic flow (EOF). The detection limit of Rhodamine 6G dye for the modified microchip on the home-made microchip analyzer showed a dramatic 100-fold improvement over that for the unmodified PMMA chip. A detection limit of the order of 10(-20) mole has been achieved for each injected phiX-174/HaeIII DNA fragment with the baseline separation between 271 and 281 bp, and fast separation of 11 DNA restriction fragments within 180 seconds. Analysis of a PCR product from the tobacco ACT gene was performed on the modified microchip as an application example.

Reaction path for oxidation of ethylene to acetic acid over Pd/WO3-ZrO2 in the presence of water

Pd-supported on WO3-ZrO2 (W/Zr atomic ratio=0.2) calcined at 1073 K was found to be highly active and selective for gas-phase oxidation of ethylene to acetic acid in the presence of water at 423 K and 0.6 MPa. Contact time dependence demonstrated that acetic acid is formed via acetaldehyde formed by a Wacker-type reaction, not through ethanol by hydration of ethylene.