12,271 research outputs found
Combinatorial Bounds and Characterizations of Splitting Authentication Codes
We present several generalizations of results for splitting authentication
codes by studying the aspect of multi-fold security. As the two primary
results, we prove a combinatorial lower bound on the number of encoding rules
and a combinatorial characterization of optimal splitting authentication codes
that are multi-fold secure against spoofing attacks. The characterization is
based on a new type of combinatorial designs, which we introduce and for which
basic necessary conditions are given regarding their existence.Comment: 13 pages; to appear in "Cryptography and Communications
Smartphone chronic gaming consumption and positive coping practice
Purpose: Chronic consumption practice has been greatly accelerated by mobile, interactive and smartphone gaming technology devices. This study explores how chronic consumption of smartphone gaming produces positive coping practice. Design/methodology/approach: Underpinned by cognitive framing theory, empirical insights from eleven focus groups (n=62) reveal how smartphone gaming enhances positive coping amongst gamers and non-gamers. Findings: The findings reveal how the chronic consumption of games allows technology to act with privileged agency that resolves tensions between individuals and collectives. Consumption narratives of smartphone games, even when play is limited, lead to the identification of three cognitive frames through which positive coping processes operate: (a) the market generated frame, (b) the social being frame, and (c) the citizen frame. Research limitations/implications: This paper adds to previous research by providing an understanding of positive coping practice in the smartphone chronic gaming consumption. Originality/value: In smartphone chronic gaming consumption, cognitive frames enable positive coping by fostering appraisal capacities in which individuals confront, hegemony, culture and alterity-morality concerns
Exploring the Foundations of Music Education Learning Communities in Rural Texas School Districts
This explanatory sequential mixed method study identified the challenges of creating, implementing, evaluating, and revising a Music Education Learning Community (MELC) model in developing/metro-commuting rural school districts outside the Dallas-Fort Worth Metroplex of Texas. Influences such as Professional Learning Communities (PLC), the Community Learning Exchange (CLE), and educational partnerships have accelerated the need for applied collaborations to improve music programs. This study showed increased support through a Music Education Learning Community (MELC). MELCs enhanced the skills and knowledge of music educators, families, and community organizations through collaborative analysis, an exchange of expertise, and frequent dialogue. The focus of this study was twofold: it identified limitations that music educators overcame to increase participation from music educators, families, and community organizations and how information was best disseminated to educators, families, and community organizations consistently for the continued growth of the MELC. Data was collected from school districts outside the Dallas Fort Worth Metroplex. An analysis of MELCs revealed the importance of community engagement, partnerships and collaborations despite the challenges of communication among all stakeholders. The findings suggested that further investigation could explore how MELC ‘s implementation might enhance fine arts programs in rural areas. A deeper understanding of learning communities regarding the different levels of interaction could have a stimulating effect on the design and implementation of future MELC programs
Direct Observation of a Fractional Charge
We performed measurements of Quantum Shot Noise in order to determine the
quasiparticle charge in the Fractional Quantum Hall regime. The noise is
generated by a current flow through a partially transmitting Quantum Point
Contact in a 2DEG. The noise is directly proportional to the charge of the
quasiparticles, thus allowing direct determination of the charge. We measured
Quantum Shot Noise at a filling factor of 1/3 and found that the charge is e/3;
as predicted by Laughlin.Comment: 3 pages, PostScript, 4 figures. Submitted to Natur
Integrated Optical Polarization of Nearby Galaxies
We performed an integrated optical polarization survey of 70 nearby galaxies
to study the relationship between linear polarization and galaxy properties. To
date this is the largest survey of its kind. The data were collected at
McDonald Observatory using the Imaging Grism Polarimeter on the Otto Struve
2.1m telescope. Most of the galaxies did not have significant level of linear
polarization, where the bulk is <1%. A fraction of the galaxies showed a loose
correlation between the polarization and position angle of the galaxy,
indicating that dust scattering is the main source of optical polarization. The
unbarred spiral galaxies are consistent with the predicted relationship with
inclination from scattering models of ~sin^2i.Comment: accepted in ApJ, 21 pages, 5 figure
On the Von Neumann Entropy of Graphs
The von Neumann entropy of a graph is a spectral complexity measure that has
recently found applications in complex networks analysis and pattern
recognition. Two variants of the von Neumann entropy exist based on the graph
Laplacian and normalized graph Laplacian, respectively. Due to its
computational complexity, previous works have proposed to approximate the von
Neumann entropy, effectively reducing it to the computation of simple node
degree statistics. Unfortunately, a number of issues surrounding the von
Neumann entropy remain unsolved to date, including the interpretation of this
spectral measure in terms of structural patterns, understanding the relation
between its two variants, and evaluating the quality of the corresponding
approximations.
In this paper we aim to answer these questions by first analysing and
comparing the quadratic approximations of the two variants and then performing
an extensive set of experiments on both synthetic and real-world graphs. We
find that 1) the two entropies lead to the emergence of similar structures, but
with some significant differences; 2) the correlation between them ranges from
weakly positive to strongly negative, depending on the topology of the
underlying graph; 3) the quadratic approximations fail to capture the presence
of non-trivial structural patterns that seem to influence the value of the
exact entropies; 4) the quality of the approximations, as well as which variant
of the von Neumann entropy is better approximated, depends on the topology of
the underlying graph
Evidence translation in a youth mental health service: clinician perspectives
An evidence–practice gap is well established in the mental health field, and knowledge translation is identified as a key strategy to bridge the gap. This study outlines a knowledge translation strategy, which aims to support clinicians in using evidence in their practice within a youth mental health service ( headspace). We aim to evaluate the strategy by exploring clinicians’ experiences and preferences. The translation strategy includes the creation and dissemination of evidence translation resources that summarize the best available evidence and practice guidelines relating to the management of young people with mental disorders. Semi-structured interviews were conducted with 14 youth mental health clinicians covering three topics: experiences with evidence translation resources, preferences for evidence presentation, and suggestions regarding future translation efforts. Interviews were recorded, transcribed verbatim, coded, and analyzed using thematic analysis. Themes were both predetermined by interview topic and identified freely from the data. Clinicians described their experiences with the evidence translation resources as informing decision making, providing a knowledge base, and instilling clinical confidence. Clinicians expressed a preference for brief, plain language summaries and for involvement and consultation during the creation and dissemination of resources. Suggestions to improve the dissemination strategy and the development of new areas for evidence resources were identified. The knowledge translation efforts described support clinicians in the provision of mental health services for young people. The preferences and experiences described have valuable implications for services implementing knowledge translation strategies
Electron transport in the dye sensitized nanocrystalline cell
Dye sensitised nanocrystalline solar cells (Gr\"{a}tzel cells) have achieved
solar-to-electrical energy conversion efficiencies of 12% in diffuse daylight.
The cell is based on a thin film of dye-sensitised nanocrystalline TiO
interpenetrated by a redox electrolyte. The high surface area of the TiO
and the spectral characteristics of the dye allow the device to harvest 46% of
the solar energy flux. One of the puzzling features of dye-sensitised
nano-crystalline solar cells is the slow electron transport in the titanium
dioxide phase. The available experimental evidence as well as theoretical
considerations suggest that the driving force for electron collection at the
substrate contact arises primarily from the concentration gradient, ie the
contribution of drift is negligible. The transport of electrons has been
characterised by small amplitude pulse or intensity modulated illumination.
Here, we show how the transport of electrons in the Gr\"{a}tzel cell can be
described quantitatively using trap distributions obtained from a novel charge
extraction method with a one-dimensional model based on solving the continuity
equation for the electron density. For the first time in such a model, a back
reaction with the I ions in the electrolyte that is second order in the
electron density has been included.Comment: 6 pages, 5 figures, invited talk at the workshop 'Nanostructures in
Photovoltaics' to appear in Physica
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