Working memory and second language development: A complex, dynamic future?

Working memory (WM) is inherently dynamic and complex, being a multi-faceted system that links storage and processing components; yet it is widely understood as internal. Hence, in second language (L2) research, its connection to complex dynamic systems theory (CDST) remains underspecified. This paper seeks to bridge a gap between CDST and WM in L2 research. First, definitions of WM are reviewed, along with evidence for its relationship to L2 outcomes. Next, a brief overview of CDST highlights its metatheoretical and methodological implications. Three perspectives are presented to illustrate how WM can be viewed in terms of major tenets in CDST. These consider WM effects as: (1) context-dependent, (2) interrelated with those of other variables, and (3) amenable to change across the lifespan. Despite this reappraisal, numerous challenges remain. Thus, in addition to noting research opportunities, the paper also considers measurement issues, such as the determination of boundaries and selection of appropriate timescales. In closing, while WM studies have shown its influence on L2 proficiency and processing, to more fully understand its dynamic nature, what is needed is further research on the reciprocal influences of bilingual development and changes in WM components, such as control of attention

Service To Industry By Public Libraries

published or submitted for publicatio

An Improved Algorithm for Generating Database Transactions from Relational Algebra Specifications

Alloy is a lightweight modeling formalism based on relational algebra. In prior work with Fisler, Giannakopoulos, Krishnamurthi, and Yoo, we have presented a tool, Alchemy, that compiles Alloy specifications into implementations that execute against persistent databases. The foundation of Alchemy is an algorithm for rewriting relational algebra formulas into code for database transactions. In this paper we report on recent progress in improving the robustness and efficiency of this transformation

Conceptual Design of Software: A Research Agenda

A research agenda in software design is outlined, focusing on the role of concepts. The notions of concepts as "abstract affordances" and of conceptual integrity are discussed, and a series of small examples of conceptual models is given

Real-time Spectroscopy with Sub-GHz Resolution using Amplified Dispersive Fourier Transformation

Dispersive Fourier transformation is a powerful technique in which spectral information is mapped into the time domain using chromatic dispersion. It replaces a spectrometer with an electronic digitizer, and enables real-time spectroscopy. The fundamental problem in this technique is the trade-off between the detection sensitivity and spectral resolution, a limitation set by the digitizer's bandwidth. This predicament is caused by the power loss associated with optical dispersion. We overcome this limitation using Raman amplified spectrum-to-time transformation. An extraordinary loss-less -11.76 ns/nm dispersive device is used to demonstrate single-shot gas absorption spectroscopy with 950 MHz resolution--a record in real-time spectroscopy.Comment: The following article has been accepted by Applied Physics Letter

Knowledge Flow Analysis for Security Protocols

Knowledge flow analysis offers a simple and flexible way to find flaws in security protocols. A protocol is described by a collection of rules constraining the propagation of knowledge amongst principals. Because this characterization corresponds closely to informal descriptions of protocols, it allows a succinct and natural formalization; because it abstracts away message ordering, and handles communications between principals and applications of cryptographic primitives uniformly, it is readily represented in a standard logic. A generic framework in the Alloy modelling language is presented, and instantiated for two standard protocols, and a new key management scheme.Comment: 20 page

Molecular Mechanics of Oxaliplatin and an Oxaliplatin Derivative with Their Relevant Biological Targets

Molecular mechanics and dynamics calculations were used to simulate reactions of oxaliplatin and Pt(Me2dach)(oxalate) with methionine and guanine, where Me2dach is N,N-dimethyl-1,2-diaminocyclohexane. The results were consistent with steric effects that resulted in chelation when Pt(Me2dach)(oxalate) reacted with N-acetylmethionine experimentally (Williams et al., 2013). The energy difference due to ligand bulk that was predicted using molecular mechanics was also consistent with experimental results: oxaliplatin’s ligand bulk did not prevent the formation of bis products with 9-ethylguanine and N-acetylmethionine, but the ligand bulk of Pt(Me2dach)(oxalate) did prevent bis product formation with N-acetylmethionine, resulting in chelation with the sulfur and oxygen atoms of the methionine residue (Williams et al., 2013).Pt(Me2dach)(oxalate) did not prevent bis products with 9-ethylguanine (Williams et al., 2013)

Bispectrum signatures of a modified vacuum in single field inflation with a small speed of sound

Deviations from the Bunch-Davies vacuum during an inflationary period can leave a testable imprint on the higher-order correlations of the CMB and large scale structures in the Universe. The effect is particularly pronounced if the statistical non-Gaussianity is inherently large, such as in models of inflation with a small speed of sound, e.g. DBI. First reviewing the motivations for a modified vacuum, we calculate the non-Gaussianity for a general action with a small speed of sound. The shape of its bispectrum is found to most resemble the 'orthogonal' or 'local' templates depending on the phase of the Bogolyubov parameter. In particular, for DBI models of inflation the bispectrum can have a profound 'local' template feature, in contrast to previous results. Determining the projection into the observational templates allows us to derive constraints on the absolute value of the Bogolyubov parameter. In the small sound speed limit, the derived constraints are generally stronger than the existing constraint derived from the power spectrum. The bound on the absolute value of the Bogolyubov parameter ranges from the 10^-6 to the 10^-3 level for H/\Lambda_c = 10^-3, depending on the specific details of the model, the sound speed and the phase of the Bogolyubov parameter.Comment: 34 pages, 8 figures, 2 appendices. New in this version: added references, fixed typos, modified sentences. Version submitted to JCA

The effect of bond coat oxidation on the microstructure and endurance of two thermal barrier coating systems

A series of isothermal and cyclic oxidation tests were carried out on two thermal barrier coating systems consisting of a CMSX-4 nickel-based superalloy substrate, NiCoCrAlY overlay bond coat applied by two different techniques and a yttria stabilised zirconia topcoat applied by electron beam physical vapour deposition (EBPVD). The bond coats were applied by either high velocity oxy-fuel spraying (HVOF) or EBPVD. Isothermal oxidation tests were carried out at 950°C, 1050°C and 1150°C for both coating system for up to 3000 hours. Cyclic oxidation testing was conducted at 1150°C in one hour cycles to coating failure on both coatings. A detailed examination on the oxide thickness was conducted on all specimens, along with characterisation of the bond coat and TGO. This was coupled with examination of specimen cross-sections for cracking and signs of coating degradation. Isothermal oxidation showed sub parabolic oxide growth consistent with the literature. Detailed analysis of oxide thickness showed a normal distribution but with increasing standard deviation with increasing oxidation time. Both bond coats were dual phase, β + γ. The EBPVD applied bond coat only, was found to contain yttrium rich precipitates in the bond coat and TGO. Both coatings showed no increase in surface roughness after either isothermal or thermal cycle testing. Short sub-critical cracks were observed at the TGO/topcoat interface in the HVOF applied bond coat only associated with the flanks of asperities. Coating failure in both coatings occurred at the TGO/bond coat interface on cooling and was likely driven by the thermal expansion mismatch between the TGO, topcoat and substrate. The initial mechanism of crack formation was not determined conclusively but could be a wedge cracking type mechanism