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- Resource Type:
- Article
- Creator:
- LeFevre, Jo-Anne and Sénéchal, Monique
- Abstract:
- One hundred and ten English-speaking children schooled in French were followed from kindergarten to Grade 2 (Mage: T1 = 5;6, T2 = 6;4, T3 = 6;11, T4 = 7;11). The findings provided strong support for the Home Literacy Model (Sénéchal & LeFevre, 2002) because in this sample the home language was independent of the language of instruction. The informal literacy environment at home predicted growth in English receptive vocabulary from kindergarten to Grade 1, whereas parent reports of the formal literacy environment in kindergarten predicted growth in children's English early literacy between kindergarten and Grade 1 and growth in English word reading during Grade 1. Furthermore, 76% of parents adjusted their formal literacy practices according to the reading performance of their child, in support of the presence of a responsive home literacy curriculum among middle-class parents.
- Date Created:
- 2014-01-01
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- Resource Type:
- Article
- Creator:
- Albert, Jacques, Dakka, Milad A., Shevchenko, Yanina, and Chen, Chengkun
- Abstract:
- We show that the tilted-grating-assisted excitation of surface plasmon polaritons on gold coated single-mode optical fibers depends strongly on the state of polarization of the core-guided light, even in fibers with cylindrical symmetry. Rotating the linear polarization of the guided light by 90° relative to the grating tilt plane is sufficient to turn the plasmon resonances on and off with more than 17 dB of extinction ratio. By monitoring the amplitude changes of selected individual cladding mode resonances we identify what we believe to be a new refractive index measurement method that is shown to be accurate to better than 5 × 10-5.
- Date Created:
- 2010-03-01
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- Resource Type:
- Article
- Creator:
- Lever, Rosemary, Ouellette, Gene, Pagan, Stephanie, and Sénéchal, Monique
- Abstract:
- The goal of the present intervention research was to test whether guided invented spelling would facilitate entry into reading for at-risk kindergarten children. The 56 participating children had poor phoneme awareness, and as such, were at risk of having difficulty acquiring reading skills. Children were randomly assigned to one of three training conditions: invented spelling, phoneme segmentation, or storybook reading. All children participated in 16 small group sessions over eight weeks. In addition, children in the three training conditions received letter-knowledge training and worked on the same 40 stimulus words that were created from an array of 14 letters. The findings were clear: on pretest, there were no differences between the three conditions on measures of early literacy and vocabulary, but, after training, invented spelling children learned to read more words than did the other children. As expected, the phoneme-segmentation and invented-spelling children were better on phoneme awareness than were the storybook-reading children. Most interesting, however, both the invented spelling and the phoneme-segmentation children performed similarly on phoneme awareness suggesting that the differential effect on learning to read was not due to phoneme awareness per se. As such, the findings support the view that invented spelling is an exploratory process that involves the integration of phoneme and orthographic representations. With guidance and developmentally appropriate feedback, invented spelling provides a milieu for children to explore the relation between oral language and written symbols that can facilitate their entry in reading.
- Date Created:
- 2012-04-01
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- Resource Type:
- Article
- Creator:
- Shao, Li-Yang, Albert, Jacques, Coyle, Jason P., and Barry, Seán T.
- Abstract:
- The conformal coating of a 50 nm-thick layer of copper nanoparticles deposited with pulse chemical vapor deposition of a copper (I) guanidinate precursor on the cladding of a single mode optical fiber was monitored by using a tilted fiber Bragg grating (TFBG) photo-inscribed in the fiber core. The pulse-per-pulse growth of the copper nanoparticles is readily obtained from the position and amplitudes of resonances in the reflection spectrum of the grating. In particular, we confirm that the real part of the effective complex permittivity of the deposited nano-structured copper layer is an order of magnitude larger than that of a bulk copper film at an optical wavelength of 1550 nm. We further observe a transition in the growth behavior from granular to continuous film (as determined from the complex material permittivity) after approximately 20 pulses (corresponding to an effective thickness of 25 nm). Finally, despite the remaining granularity of the film, the final copper-coated optical fiber is shown to support plasmon waves suitable for sensing, even after the growth of a thin oxide layer on the copper surface.
- Date Created:
- 2011-06-01
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- Resource Type:
- Article
- Creator:
- Adler, Andy, Loyka, Sergey, and Youmaran, Richard
- Date Created:
- 2009-01-01
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- Resource Type:
- Article
- Creator:
- Morin, Pat, Hurtado, Ferran, Bose, Prosenjit, and Carmi, Paz
- Abstract:
- We prove that, for every simple polygon P having k ≥ 1 reflex vertices, there exists a point q ε P such that every half-polygon that contains q contains nearly 1/2(k + 1) times the area of P. We also give a family of examples showing that this result is the best possible.
- Date Created:
- 2011-04-01
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- Resource Type:
- Article
- Creator:
- Hayes, M. John, Langlois, Robert, and Weiss, Abraham
- Abstract:
- Conventional training simulators commonly use a hexapod configuration to provide motion cues. While widely used, studies have shown that hexapods are incapable of producing the range of motion required to achieve high fidelity simulation required in many applications. A novel alternative is the Atlas motion platform. This paper presents a new generalized kinematic model of the platform which can be applied to any spherical platform actuated by three omnidirectional wheels. In addition, conditions for slip-free and singularity-free motions are identified. Two illustrative examples are given for different omnidirectional wheel configurations.
- Date Created:
- 2011-02-01
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- Resource Type:
- Article
- Creator:
- Wiener, Michael J. and Van Oorschot, Paul C.
- Abstract:
- A simple new technique of parallelizing methods for solving search problems which seek collisions in pseudorandom walks is presented. This technique can be adapted to a wide range of cryptanalytic problems which can be reduced to finding collisions. General constructions are given showing how to adapt the technique to finding discrete logarithms in cyclic groups, finding meaningful collisions in hash functions, and performing meet-in-the-middle attacks such as a known-plaintext attack on double encryption. The new technique greatly extends the reach of practical attacks, providing the most cost-effective means known to date for defeating: the small subgroup used in certain schemes based on discrete logarithms such as Schnorr, DSA, and elliptic curve cryptosystems; hash functions such as MD5, RIPEMD, SHA-1, MDC-2, and MDC-4; and double encryption and three-key triple encryption. The practical significance of the technique is illustrated by giving the design for three $10 million custom machines which could be built with current technology: one finds elliptic curve logarithms in GF(2155) thereby defeating a proposed elliptic curve cryptosystem in expected time 32 days, the second finds MD5 collisions in expected time 21 days, and the last recovers a double-DES key from two known plaintexts in expected time 4 years, which is four orders of magnitude faster than the conventional meet-in-the-middle attack on double-DES. Based on this attack, double-DES offers only 17 more bits of security than single-DES.
- Date Created:
- 1999-01-01
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- Resource Type:
- Article
- Creator:
- Wiener, Michael J., Van Oorschot, Paul C., and Diffie, Whitfield
- Abstract:
- We discuss two-party mutual authentication protocols providing authenticated key exchange, focusing on those using asymmetric techniques. A simple, efficient protocol referred to as the station-to-station (STS) protocol is introduced, examined in detail, and considered in relation to existing protocols. The definition of a secure protocol is considered, and desirable characteristics of secure protocols are discussed.
- Date Created:
- 1992-06-01
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- Resource Type:
- Article
- Creator:
- Yan, Donghang, Wang, Zhiyuan, Yu, Hongan, Wu, Xianguo, and Zhang, Jidong
- Abstract:
- A near infrared (NIR) electrochromic attenuator based on a dinuclear ruthenium complex and polycrystalline tungsten oxide was fabricated and characterized. The results show that the use of the NIR-absorbing ruthenium complex as a counter electrode material can improve the device performance. By replacing the visible electrochromic ferrocene with the NIR-absorbing ruthenium complex, the optical attenuation at 1550 nm was enhanced from 19.1 to 30.0 dB and color efficiency also increased from 29.2 to 121.2 cm2/C.
- Date Created:
- 2005-12-01