1,125 research outputs found
Using off-diagonal confinement as a cooling method
In a recent letter [Phys. Rev. Lett. 104, 167201 (2010)] we proposed a new
confining method for ultracold atoms on optical lattices, based on off-diagonal
confinement (ODC). This method was shown to have distinct advantages over the
conventional diagonal confinement (DC) that makes use of a trapping potential,
including the existence of pure Mott phases and highly populated condensates.
In this paper we show that the ODC method can also lead to temperatures that
are smaller than with the conventional DC method, depending on the control
parameters. We determine these parameters using exact diagonalizations for the
hard-core case, then we extend our results to the soft-core case by performing
quantum Monte Carlo (QMC) simulations for both DC and ODC systems at fixed
temperatures, and analysing the corresponding entropies. We also propose a
method for measuring the entropy in QMC simulations.Comment: 6 pages, 6 figure
Current legal and institutional issues in the commercialization of phosphoric acid fuel cells
Legal and institutional factors affecting the development and commercial diffusion of phosphoric acid fuel cells are assessed. Issues for future research and action are suggested. Perceived barriers and potential opportunities for fuel cells in central and dispersed utility operations and on-site applications are reviewed, as well as the general concept of commercialization as applied to emerging energy technologies
Imaging of the Stellar Population of IC10 with Laser Guide Star Adaptive Optics and the Hubble Space Telescope
We present adaptive optics (AO) images of the central starburst region of the
dwarf irregular galaxy IC10. The Keck 2 telescope laser guide star was used to
achieve near diffraction-limited performance at H and K' (Strehls of 18% and
32%, respectively). The images are centered on the putative Wolf-Rayet (W-R)
object [MAC92]24. We combine our AO images with F814W data from HST. By
comparing the K' vs. [F814W]-K' color-magnitude diagram (CMD) with theoretical
isochrones, we find that the stellar population is best represented by at least
two bursts of star formation, one ~ 10 Myr ago and one much older (150-500
Myr). Young, blue stars are concentrated in the vicinity of [MAC92]24. This
population represents an OB association with a half-light radius of about 3 pc.
We resolve the W-R object [MAC92]24 into at least six blue stars. Four of these
components have near-IR colors and luminosities that make them robust WN star
candidates. By matching the location of C-stars in the CMD with those in the
SMC we derive a distance modulus for IC10 of about 24.5 mag. and a foreground
reddening of E(B-V) = 0.95. We find a more precise distance by locating the tip
of the giant branch in the F814W, H, and K' luminosity functions. We find a
weighted mean distance modulus of 24.48 +/- 0.08. The systematic error in this
measurement, due to a possible difference in the properties of the RGB
populations in IC10 and the SMC, is +/- 0.16 mag.Comment: 13 pages, 13 figures, ApJ in pres
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Tablet PCs in schools: Case study report: A report for Becta by the Open University
The publication provides an analysis of twelve case studies involving schools in England that were using Tablet PCs. The analysis is complemented by brief individual reports describing aspects of how each of these schools was using Tablet PCs
Teaching word recognition to children with severe learning difficulties: an exploratory comparison of teaching methods
Background: Some children with severe learning difficulties fail to begin word recognition. For these children there is a need for an effective and appropriate pedagogy. However, conflicting advice can be found regarding this derived from teaching approaches that are not based on a shared understanding of how reading develops or the skills that the non-reader needs to master.
Purpose: In this research, three techniques for teaching word recognition in this context are described and compared: (1) the handle technique, (2) morphing method and (3) word alone. It also discusses whether it is appropriate for such small-scale research to influence pedagogy.
Programme description: The handle technique uses an abstract mnemonic cue used to teach word recognition, and previous research indicates it is more successful than the presentation of words alone. The morphing method transforms a word into a photographic picture and a previous study suggested that it might also be more effective that presenting words alone.
Sample: Six children between 11 and 13 years of age were selected. The criterion for selection was being unable to recognise any words from the British Ability Scales Reading Test. All the children attended a school for children with severe learning difficulties.
Design and methods: A three-condition related design was used. The order in which the conditions were presented was counterbalanced and each child was taught 12 words, four words in each experimental condition. The children encountered each of the three methods and overall each word was taught via each method. Within conditions (teaching methods), the presentation of words was randomised. The number of words that the children could read (without cues) before each session was recorded, following the presentation of the uncued words in a random order. The difference in the number of words recognised between the three conditions was considered using a non-parametric statistical analysis.
Results: The results suggest that the handle approach might be a more effective method of teaching word recognition.
Conclusion: Research in this area is necessarily small in scale. However, it is ongoing and cumulative, and can give insights into potentially beneficial changes in classroom practice
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