The visual control of reaching and grasping: Binocular disparity and motion parallax.

The primary visual sources of depth and size information are binocular cues and motion parallax. Here, the authors determine the efficacy of these cues to control prehension by presenting them in isolation from other visual cues. When only binocular cues were available, reaches showed normal scaling of the transport and grasp components with object distance and size. However, when only motion parallax was available, only the transpont component scaled reliably. No additional increase in scaling was found when both cues were available simultaneously. Therefore, although equivalent information is available from binocular and motion parallax information, the latter may be of relatively limited use for the control of the grasp. Binocular disparity appears selectively important for the control of the grasp. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impurity induced disordering of GaInAs quantum wells with barriers of AlGaInAs or of GaInAsP

Impurity induced disordering of GaInAs quantum well structures with barriers of AlGaInAs and of GaInAsP has been investigated using boron and fluorine. The impurities were introduced by ion implantation followed by thermal annealing. Annealing unimplanted P-based quaternary material at temperatures greater than 500° C caused a blue shift of the exciton peak. At annealing temperatures greater than 650° C red shifts in the exciton peak of unimplanted Al-based quaternary material were observed. Boron implantation caused small blue shifts of the exciton peak in both material systems at low annealing temperatures. Much larger blue shifts were observed in the fluorine implanted samples.     

Impairments of movement kinematics in patients with Huntington's disease: a comparison with and without a concurrent task

This study aimed to quantify the efficiency and smoothness of voluntary movement in Huntington's disease (HD) by the use of a graphics tablet that permits analysis of movements profiles. In particular, we aimed to ascertain whether a concurrent task (digit span) would affect the kinematics of goal-directed movements. Twelve patients with HD and their matched controls performed 12 vertical zig-zag movements, with both left and right hands (with and without the concurrent task), to large or small circular targets over long or short extents. The concurrent task was associated with shorter movement times and reduced right-hand superiority. Patients with HD were overall slower, especially, with long strokes, and had similar peak velocities for both small and large targets, so that controls could better accommodate differences in target size. Patients with HD spent more time decelerating, especially with small targets, whereas controls allocated more nearly equal proportions of time to the acceleration and deceleration phases of movement, especially with large targets. Short strokes were generally less force inefficient than were long strokes, especially so for either hand in either group in the absence of the concurrent task, and for the right hand is its presence. With the concurrent task, however, the left hand's behavior changed differentially for the two groups; for patients with HD, it became more force efficient with short strokes and even less efficient with long strokes, whereas for controls, it became more efficient with long strokes. Controls may be able to divert attention away from the inferior left hand, increasing its automaticity, whereas patients with HD, because of disease, may be forced to engage even further online visual control under the demands of a concurrent task. Patients with HD may perhaps become increasingly reliant on terminal visual guidance, which indicates an impairment in constructing and refining an internal representation of the movement necessary for its effective execution. Basal ganglia dysfunction may impair the ability to use internally generated cues to guide movement.     

Mass transfer from a carbon dioxide jet to tap water

When a jet of soluble gas is directed on to liquid surface, the kinetic energy of the jet is transferred to the liquid giving rise to circulation, which in turn enhances mass transfer. Consequently, the mass transfer coefficient is related to the characteristics of the jet.     

Cation Transport at 25°C from Binary Cd2+–Mn+ Mixtures in a H2O-CHCl3–H2O Liquid Membrane System Containing a Series of Macrocyclic Carriers[1]

Macrocycle-mediated fluxes of Cd(NO₃)₂ and of several binary mixtures of Cd(NO₃)₂ with the nitrate salt of either Na⁺, K⁺, Rb⁺ Cs⁺, Ag⁺, Ca²⁺, Sr²⁺, Pb²⁺, Zn²⁺, or Cu²⁺ have been determined in a H₂O-CHCl₃–H₂O liquid membrane system. Of the macrocycles studied, 2.2 and 2.2DD most successfully transported Cd²⁺ In the Cd²⁺–Mⁿ⁺ mixtures, Cd²⁺ was transported selectively with 2.2 when Mⁿ⁺ was either an alkali or an alkaline earth cation. However, when Mⁿ⁺ was either Ag⁺, Pb²⁺, or Cu²⁺ the Cd²⁺ flux was reduced sharply. Generally, cation flux was greater for 2.2DD than for 2.2 with selectivity for Cd²⁺ being altered also in several cases. Relative fluxes from binary cation mixtures depend on metal cation radius, macrocycle cavity diameter, ligand ring substituent and log K for metal ion-macrocycle interaction.     

Molecular genetics of rust resistance in poplars (Melampsora larici-populina Kleb/Populus sp.) by bulked segregant analysis in a 2 x 2 factorial mating design

With random amplified polymorphic DNA (RAPD) markers, we have tagged a genomic region in Populus sp. involved in qualitative resistance to Melampsora larici-populina. Our approach was based on three steps: use of RAPD markers that can be quickly and efficiently researched: application of "bulked segregant analysis" technique on individuals of one interspecific family P. trichocarpa x P. deltoides to search for RAPD markers linked to resistance; and validation of these markers in two other families linked with the first one in a 2 x 2 factorial mating design. Of five detected markers, only one marker M03/04_480 was polymorphic in the three segregating families, involving 89 individuals and four different parents. We have estimated the recombination value of 1 cM with 1 cM sampling error.     

The formulation and use of mixed collectors in sulphide flotation

Mixtures of collectors have been widely used for many years in sulphide flotation, and a range of performance benefits have been reported for many different systems. The combinations of collector types have varied, as have the ratios that have been used. Synergistic effects have been obtained (greater than the sum of the parts) and in some cases the mechanisms of this improved behaviour have been identified. These benefits have been attributed to increased carrying capacity of the froth phase, faster kinetics, and more successful recovery of middling or coarse particles. It is the interaction between the various components of the mixed collector system, rather than the individual main effects, that dominate the performance benefits. The process benefits include increased paymetal recoveries and grades – as well as increased rates of recovery whilst using lower dosages of reagents. Various mechanisms have been reported and are discussed. These have been shown to affect different composition/liberation classes and sizes of mineral particles. In recent years, automated quantitative mineralogy and surface analysis technology such as ToF-SIMS have enabled the development of better information, to establish what aspect of the process has been affected. This has been successful mostly for use in a diagnostic capacity. Candidate selection for the mixed collector suite is presently based on experience and contextual knowledge. Predictive properties from these systems are a desirable future goal. Currently optimum combinations are preferably identified experimentally at laboratory scale prior to any plant trial. It is recommended that such laboratory work be performed using a factorial design with replicates and quality controls, such as may be delivered from High-Confidence Flotation Testing. The purpose of this paper is to summarise and review current theory and practice in the usage of mixtures of collectors in sulphide flotation – both in the application and in research in order to develop insights and guidelines to develop a methodology for use in a predictive capacity. A case study demonstrating this approach will be published at a later date.     

“与自然共生”：英国儿童游戏场地改造

风景园林实践在很大程度上受到政府决策的影响,以英国英格兰地区为例,劳动党政府于2008年提出的《儿童计划》和《游戏策略》,在为儿童游戏场地的更新和建设提供资金支持的同时,也间接推动了儿童场地设计导则与标准的发展。然而随着2010年政府换届,儿童户外游戏场地发展方案被移出了英国国家发展计划。将着重介绍在政策变化的背景下,于英格兰北部谢菲尔德市进行的名为“与自然共生”政府资助项目的实践经验,重点探究在政策引导的背景下,通过儿童户外游戏场地自然化改造的方式对社区户外空间进行适儿化提升的过程、方式和成果。将从多元参与协同工作的机制、儿童参与社区改造的方式以及儿童游戏场地的游戏价值提升等多个方面阐释该项目,为中国“十四五”规划背景下儿童友好型城市建设中社区环境优化提升面临的机遇与挑战提供基于英国经验的应对策略;对因地制宜地建设中国儿童友好城市及社区提供基于前沿实践的参考和建议。