Phonemes, Rimes, Vocabulary, and Grammatical Skills as Foundations of Early Reading Development: Evidence From a Longitudinal Study.

The authors present the results of a 2-year longitudinal study of 90 British children beginning at school entry when they were 4 years 9 months old (range = 4 years 2 months to 5 years 2 months). The relationships among early phonological skills, letter knowledge, grammatical skills, and vocabulary knowledge were investigated as predictors of word recognition and reading comprehension. Word recognition skills were consistently predicted by earlier measures of letter knowledge and phoneme sensitivity (but not by vocabulary knowledge, rhyme skills, or grammatical skills). In contrast, reading comprehension was predicted by prior word recognition skills, vocabulary knowledge, and grammatical skills. The results are related to current theories about the role of phonological, grammatical, and vocabulary skills in the development of early reading skills. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cluster-based location service schemes in VANETs: current state,challenges and future directions

Vehicular Ad hoc Networks (VANETs) have drawn incredible interest in both academic and industrial sectors due to their potential applications and services. Vehicles’ position plays a significant role in many location-based applications and services such as public emergency, vehicles tracking, resource discovery, traffic monitoring and position-based routing. A location service is used to keep up-to-date records of current positions of vehicles. However, locating vehicles’ positions and maintaining an accurate view of the entire network are quite challenging tasks due to the high number of nodes, and high and fast nodes mobility which results in rapid topological changes and sudden network disconnections. In the past literature, various location-based services have been proposed to solve the above mentioned issues. Moreover, the cluster-based location service schemes have gained a growing interest due to their advantages over non-cluster-based schemes. The cluster-based schemes improve the network scalability, reduce the communications overhead and resolve the mobility issues within the clusters preventing them from propagating in the whole network. Therefore, this paper presents the taxonomy of the existing location service schemes, inspects the cluster-based location service by highlighting their strengths and limitations, and provides a comparison between location-based clustering and application specific clustering such as the one used in routing, information dissemination, channel access management and security. In addition, the existing clustering schemes, challenges and future directions for efficient cluster-based location service are also discussed.

     

Electrochemical performance of spherical LiCoO2 with high stability in neutral aqueous electrolyte

Layer-structured lithium cobalt oxide (LCO) is one of promising electrode materials for secondary aqueous lithium-ion batteries, yet the effect of structural proton insertion in LCO in neutral aqueous electrolytes cannot be ignored. Present study investigates the electrochemical performance of polycrystalline spherical LCO in neutral aqueous saturated Li₂SO₄ solution. Herein, we for the first time demonstrate the dependence of LCO stability on the discharge cutoff potential. The applied LCO electrodes show good cycling stability within the potential window of 0.65–1.1 V vs. SCE, while electrochemical impedance spectrum (EIS) analysis detects no sign of proton intercalation. Moreover, the spherical LCO free from the proton intercalation exhibits a superior rate capability with 78% discharge capacity retention at 80 C. The lithium-ion chemical diffusion coefficient being seven times than that of irregular shaped LCO sample can be responsible for such significant rate capability. The cyclability testing depicts the better performance of spherical LCO in comparison with the counterpart, especially in terms of electrode activation time. Post cycling electrode characterization displays that the discharge capacity fading of LCO mainly results from the crystal grain deformation due to high potential cycling and can be alleviated by reducing the depth of charge.     

Effect of microstructure change on resistance of spherical LiCoO2 to electrode degradation for proton intercalation

Lithium cobalt oxide (LCO) with layered crystal structure suffers the structural proton intercalation in aqueous electrolytes of low pH values, little information is available about the effect of microstructure change on the cycling stability of LCO in response to the proton intercalation. In this work, electrochemical properties of three kinds of LCO spheres with different microstructures are studied in neutral aqueous 0.5 M Li₂SO₄ solution. The investigated materials were obtained by calcining the spherical LCO precursors at various temperatures, which were synthesized via a modified solid phase method for lithiation of spherical Co₃O₄. Structure and morphology of materials were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The spherical LCO prepared at lower temperature shows more superior electrochemical stability. Herein, the resistance of spherical LCO with a particular microstructure to the electrode degradation for the proton intercalation can be measured by the frequency of occurrences of greater-than-100% coulombic efficiencies during cycling. Meanwhile, the capability of retaining the capacity contribution from the order-to-disorder transformation of lithium ions on the hexagonal lattice of host site after the first-order phase transition was proposed to compare and investigate the cyclability of the three kinds of spherical LCO with different microstructures.     

Optimizing the reading of electronic text using rapid serial visual presentation

The focus on communications technology in recent years has led to the question of how to best display electronic text onto small-screened devices. Past studies have shown that the compact method of rapid serial visual presentation (RSVP) is efficient but not well liked. Two experiments were conducted to explore ways of improving the preference for and feasibility of RSVP. In experiment 1, the effects of a completion meter, punctuation pauses, and variable word duration were studied. Although the sentence-by-sentence and normal page formats were still superior, post-experiment ratings indicated that punctuation pauses improved user preference for RSVP, and its preference increased in general with practice. In experiment 2, a modified RSVP condition included a completion meter, punctuation pauses, interruption pauses and pauses at clause boundaries. This condition was significantly preferred to a normal RSVP condition. The present enhancements may increase the feasibility of using RSVP with small displays.     

Reading dynamically displayed text

Two experiments were carried out to find an optimal electronic text display method given limited display space. The display formats tested fell into two categories: Times Square, in which text is scrolled from right to left; and rapid, serial, visual presentation (RSVP), in which text is presented one or several words at a time to a fixed location in the display. Previous studies have indicated that Times Square format is not as efficient as page format display or, by extrapolation, as RSVP. These studies, unlike the present experiments, did not include a smooth-scrolling (pixel-by-pixel) condition. In Experiment 1, a comparison was made between multiple-word RSVP and three versions of Times Square format, differing only in the size of steps by which the display was scrolled. Except for the largest step-size, comprehension was as high in the Times Square conditions as in the RSVP condition. The subjects expressed a significant preference for smooth scrolling Times Square over any other condition. Experiment 2 showed that comprehension for smooth scrolling Times Square was at least as high as that for RSVP at presentation rates ranging from 100 to 300 words per minute. Times Square reading is discussed in terms of optokinetic nystagmus (OKN).     

The role of graphics in item selection from menus

The present experiment addressed the question of whether the addition of graphics to the alternatives on computer choice pages facilitates user performance. Twenty-one subjects made choices from pages that resembled videotex choice pages. One third of the time the alternatives were displayed in the usual way (Text-Only condition); one third of the time the alternatives were arranged in a nonlinear fashion and each alternative was accompanied by an illustration (Graphics condition); and one third of the time the alternatives were arranged in a nonlinear fashion but there were no illustrations (Control condition). Graphics had no effect on response time, but a reliable effect on accuracy: the error rate in the Graphics condition was half that in the Text-Only condition. Apparently, videotex information providers and other software designers would be well advised to consider adding simple graphics to alternatives on choice pages.     

Tuning semiconductor LaFe0.65Ti0.35O3-δ to fast ionic transport for advanced ceramics fuel cells

Heterostructure and their associated properties like band energy, band bending, and interface play a vital role in the conduction of charge carriers. Enhancement of ionic conductivity has been observed by the semiconductor SrTiO₃ and ionic conductor heterostructure formation, such insightful effect may be beneficial for electrolyte application in solid oxide fuel cells. Herein we report the formation of semiconductor and ionic materials heterostructure of LaFe_0.65Ti_0.35O_3-δ (LFT) and Sm and Ca co-doped cerium oxide Ce_0.8Sm_0.05Ca_0.15O_2-δ (SCDC) with three folds enhancement in the ionic conductivity. When LFT-SCDC heterostructure was applied in the fuel cell, LFT-SCDC work as a good electrolyte and achieve a maximum power output density of 0.98 W/cm². LFT-SCDC maintains the ionic and electronic conduction, the presence of electrons, their blockage and the fast promotion of ion transport play a key role in physical interpretation in realizing outstanding performance and understanding the mechanism of semiconductor electrolyte ceramics fuel cells. The constructed heterostructure between two different constituent phases of LFT and SCDC has established strong band bending at heterointerface, leading to the fast ionic transport in the interface. The combination of UV–visible spectroscopy and ultraviolet photoelectron spectroscopy (UPS) determine the band structure of both constituents, where the creation of oxygen vacancies are supported by X-ray photoelectron spectroscopy (XPS). It is revealed by the various investigation of electrical properties of LFT-SCDC heterostructure that it has both electronic and ionic behavior, where the built-in electric field formed by band energy alignment helps to enhance the transport of ions.