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$_2$ interpenetrated by a redox electrolyte. The high surface area of the TiO$_2$ 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$_3^-$ 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

The Effect of Ash and Inorganic Pigment Fill on the Atomic Oxygen Erosion of Polymers and Paints (ISMSE-12)

Low atomic oxygen fluence (below 1x10(exp 20) atoms/sq cm) exposure of polymers and paints that have a small ash content and/or inorganic pigment fill does not cause a significant difference in erosion yield compared to unfilled (neat) polymers or paints. However, if the ash and/or inorganic pigment content is increased, the surface population of the inorganic content will begin to occupy a significant fraction of the surface area as the atomic oxygen exposure increases because the ash is not volatile and remains as a loosely attached surface layer. This results in a reduction of the flux of atomic oxygen reacting with the polymer and a reduction in the rate of erosion of the polymer remaining. This paper presents the results of ground laboratory and low Earth orbital (LEO) investigations to evaluate the fluence dependence of atomic oxygen erosion yields of polymers and paints having inorganic fill content