Preschool executive control on the Shape School task: Measurement considerations and utility.

Executive functions (EF) necessary for purposeful goal-directed activities undergo rapid change and development during the preschool years. However, of the few psychometrically valid measures of EF suitable for use with preschoolers, information on task sensitivity and predictive validity is scant. The neurodevelopmental correlates of early executive difficulties are also largely unknown. In this study, the discriminant and predictive validity of the recently developed Shape School task (Espy, Bull, Martin, & Stroup, 2006) was examined with data from a regional sample of 209 preschool children at age 4 years. A 2-tiered measurement approach was used, with task completion examined in addition to efficiency. Children's performance was also examined in relation to functioning in a range of neurodevelopmental domains. The Shape School task showed some usefulness in capturing expected differences between at-risk and typically developing children. Performance loaded heavily on language and global cognitive abilities. However, several other factors were also implicated, including attention, motor skills, and ocular control. In addition, task completion and efficiency scores appeared to reflect different aspects of performance, and their associations with neurodevelopmental function and later academic achievement on the Woodcock-Johnson Tests of Achievement at age 6 years also differed. Implications for the application of the Shape School task are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

几乎没有纹波的快速稳定同步PWM-DAC滤波器

一种实现高分辨率数模转换的廉价方法是把微控制器PWM输出与精确模拟电压参考、CMOS开关、模拟滤波结合起来（参考文献1）。然而，PWM-DAC设计带来了一个很大的问题：如何充分抑制开关的输出中不可避免的较大AC纹波分量？当人们为DAC控制使用典型的16比特微控制器PWM外设时，纹波问题变得特别严重。     

Perspectives on supercomputing: three decades of change

I am fortunate to have had access to supercomputers for the last 28 years. Over this time I have used them to simulate time-dependent fluid flows in the compressible regime. Strong shocks and unstable multifluid boundaries, along with the phenomenon of fluid turbulence, have provided the simulation complexity that demands supercomputer power. The supercomputers I have used-the CDC 6600, 7600, and Star-100, the Cray-1, Cray-XMP, Cray-2, and Cray C-90, the Connection Machines CM-2 and CM-5, the Cray T3D, and the Silicon Graphics Challenge Array and Power Challenge Array-span three revolutions in supercomputer design: the introduction of vector supercomputing, parallel supercomputing on multiple CPUs, and supercomputing on hierarchically organized clusters of microprocessors with cache memories. The last revolution is still in progress, so its outcome is somewhat uncertain. I view these design revolutions through the prism of my specialty and through applications of the supercomputers I have used. Also, because these supercomputer design changes have driven equally important changes in numerical algorithms and the programs that implement them, I describe the three revolutions from this perspective     

The thermal and mechanical behavior of poly(ethylene terephthalate) fibers incorporating novel thermotropic liquid crystalline copolymers

This investigation explores the potential of improving the performance of poly(ethylene terephthalate) fibers by incorporating novel thermotropic liquid crystalline copolymers. Fibers were obtained by melt extrusion and the effect of processing conditions, i.e., spinning temperature, stretch ratio, and post treatment evaluated. The fibers were tested for mechanical performance, dimensional instability (shrinkage), and the development of shrinkage stresses. A segmented block copolymer consisting of rigid-rod, diad, and flexible coil segments was found to improve the performance of poly(ethylene terephthalate) (PET) fibers. At a concentration of 20 wt %, the alternating block copolymer increased the tensile modulus of the fibers by 40% and decreased free shrinkage by 20% compared to neat PET. © 1994 John Wiley & Sons, Inc.     

Electricity in Victorian Liverpool 1851-1901

At the beginning of the 20th century Liverpool (UK), having had a public electricity supply a decade before cities such as Manchester, Leeds or Bristol, held a prominent position in the electrical world. A study of the Merseyside area shows it to have been the location of many pioneering applications of electrical energy which predated, often by many years, their adoption in towns and cities elsewhere. When in 1879 the Liverpool Corporation Electric Lighting Act was passed, it became the first on the statute book specifically related to lighting by electricity. The events are examined which led to these considerable developments in the Victorian era     

Non-attendance at a nurse-run asthma clinic

MView is a tool for converting the results of a sequence database search into the form of a coloured multiple alignment of hits stacked against the query. Alternatively, an existing multiple alignment can be processed. In either case, the output is simply HTML, so the result is platform independent and does not require a separate application or applet to be loaded. AVAILABILITY: Free from http://www.sander.ebi.ac.uk/mview/ subject to copyright restrictions. CONTACT: brown@ebi.ac.uk     

Wavelength stabilization of a DBR laser using an in-fiber Braggfilter

A control loop that stabilizes the wavelength of a tunable distributed-Bragg-reflector (DBR) laser is discussed. An in-fiber Bragg grating is used as the wavelength reference. Over a 25-hour period, this control loop held the laser wavelength constant to within 0.022 nm. This variation is traced to the temperature dependence of the in-fiber Bragg grating and can be reduced by controlling the grating's temperature     

REFLECTIONS UPON ART AND MANUFACTURE1

The writer is struck by the interesting fact that in all manufactured articles in which there is an appeal to taste, those articles sell best and bring the highest return in money which possess the imprint of art. A truly beautiful thing increases rather than diminishes in value. Objects of pure utility, making no appeal to taste, are priced according to the exigencies of competition. They possess no added value, recognized as inherent in art. It would seem that the recognition of this intangible quality, which differentiates a beautiful and at the same time useful thing from that which is purely useful, but possesses no beauty, might be a subject of very great interest for a manufacturer. The great mass of the purchasing world is content to pay the higher price for the article which stimulates his imagination and affords him pleasure.     

AGN 191976: a novel thromboxane A2-mimetic with ocular hypotensive properties

The possible subdivision of thromboxane A2-sensitive (TP) receptors is currently a controversial subject. We report herein on a novel thromboxane A2 mimetic, AGN 191976, which has almost identical pharmacological activity to the well-characterized prostaglandin H2/thromboxane A2 (PGH2/TxA2) mimetic U-46619, but its effects on intraocular pressure are quite distinct from U-46619. Prostanoid receptor activity was determined in vitro using different smooth muscle assays and platelets. Intraocular pressure was measured tonometrically in ocular normotensive Beagle dogs and Cynomolgus monkeys. Conjunctival microvascular permeability was determined in guinea pigs. Despite closely resembling U-46619 as a potent and selective TP receptor agonist, AGN 191976 was a potent ocular hypotensive in dogs and monkeys whereas U-46619 did not lower IOP in either species. The ocular hypotensive effect of AGN 191976 in dogs was attenuated by pretreatment with the TP receptor antagonist SQ 29548. Thus, the ocular hypotensive effects of AGN 191976 are consistent with TP receptor stimulation. Both TxA2-mimetics caused plasma leakage in the guinea pig conjunctiva. The disparate activities of U-46619 and AGN 191976 in our studies suggest the existence of heterogeneous populations of TP-receptors in the eye.