Robust self-trapping of vortex beams in a saturable optical medium

We report the first observation of robust self-trapping of vortex beams propagating in a uniform condensed medium featuring local saturable self-focusing nonlinearity. Optical vortices with topological charge m=1, that remain self-trapped over ~ 5 Rayleigh lengths, are excited in carbon disulfide using a helical light beam at 532 nm and intensities from 8 to 10 GW/cm^2. At larger intensities, the vortex beams lose their stability, spontaneously breaking into two fragments. Numerical simulations based on the nonlinear Schr\"odinger equation including the three-photon absorption and nonpolynomial saturation of the refractive nonlinearity demonstrate close agreement with the experimental findings.Comment: 27 pages, 7 figures,to be published in Phys. Rev. A (2016

Using Mobile Applications for Paperless Assignments in Mathematics: A Pilot Study

Maths writing does not lend itself easily to a traditional computer keyboard (Livingstone et al., 1988), which is the reason why maths software was not successful in meeting the needs of tertiary students. Scanners were not portable enough to carry them everywhere and not many students will have their own. With the development of smart phones and tablet computers since 2010, a significant amount of applications that can scan, handwrite and annotate documents are being developing (Reyna 2010). Digital pens have been around for a long time, but only in the past years we have seen a few that work smoothly (Bradford, 2013). They are adding the ability to smoothly draw on high resolution screens to the repertoire of applications, imitating the paper experience. This creates a new opportunity for tertiary institutions to initiate the paperless submission of assignments in maths courses. At present, there is a research gap on how math courses are using mobile technology in assignment submission. This pilot study will address this gap, investigating academics’ and students’ perspectives/experiences using a mobile paperless workflow for assignment submission

Gist and Verbatim in Narrative Memory

A major concern regarding the study of narratives regards how they are indexed and retrieved. This is a question which touches on the structure of human memory in general. Indeed, if narratives capture the substance of human thought, then data that we have already collected regarding human memory is of central importance to the computational study of narrative. Fuzzy Trace Theory assumes that memory for narrative is simultaneously stored at multiple levels of abstraction and, whenever possible, decision-makers interpret a stimulus qualitatively and therefore operate on a simple - typically categorical - "gist" representation. Here, we present a computational model of Fuzzy Trace Theory applied to explain the impact of changes in a narrative upon risky-choice framing effects. Overall, our theory predicts the outcome of 20 experimental effects using only three basic assumptions: 1) preference for lowest level of gist, that is, categorical processing; 2) decision options that fall within the same categorical description are then interpreted using finer-grained (ordinal or verbatim) distinctions; and 3) once the options are mentally represented, decision preferences are generated on the basis of simple positive vs. negative valences stored in long-term memory (e.g., positive value for human lives). A fourth assumption - that negatively-valenced decision options are preferentially converted to positive decision options - is used when categories are not otherwise comparable

Appellation of Origin Status and Economic Development: A Case Study of the Mezcal Industry

Mezcal is an alcoholic beverage produced only in selected regions of Mexico under appellation of origin status from the Word Intellectual Property Organization. While it has been produced in Mexico for many centuries, mezcal’s appellation of origin was only granted in 1995. Therefore efforts to produce and market it as a premium product have a relatively short history. This case study examines developments in the production and marketing of this unique product, and the activities of the marketing cooperative El Tecuán in Guerrero State in this process.mezcal, Mexico, appellation, marketing, cooperative, Community/Rural/Urban Development, Marketing,

Enabling Future Sustainability Transitions: An Urban Metabolism Approach to Los Angeles Pincetl et al. Enabling Future Sustainability Transitions

Summary: This synthesis article presents an overview of an urban metabolism (UM) approach using mixed methods and multiple sources of data for Los Angeles, California. We examine electric energy use in buildings and greenhouse gas emissions from electricity, and calculate embedded infrastructure life cycle effects, water use and solid waste streams in an attempt to better understand the urban flows and sinks in the Los Angeles region (city and county). This quantification is being conducted to help policy-makers better target energy conservation and efficiency programs, pinpoint best locations for distributed solar generation, and support the development of policies for greater environmental sustainability. It provides a framework to which many more UM flows can be added to create greater understanding of the study area's resource dependencies. Going forward, together with policy analysis, UM can help untangle the complex intertwined resource dependencies that cities must address as they attempt to increase their environmental sustainability

Acceptability and Feasibility of Web-based Diabetes Instruction for Latinos with Limited Education and Computer Experience

Introduction: The internet offers an important avenue for developing diabetes self-management skills, but many Latinos have limited experience with computer-based instruction. Objective: To evaluate the feasibility and acceptability of delivering a web-based diabetes education program in a computer classroom for Spanish-speaking Latinos. Methods: Spanish-speaking Latinos (n=26) attended two classroom sessions to learn computer skills while navigating a web-based diabetes education platform. Diabetes knowledge was assessed before and after the intervention; structured interviews were completed to assess program acceptability. Results: Half of participants (50%) had not previously used a computer. Post-intervention, diabetes knowledge improved significantly (p=.001). The majority of participants (86%) indicated a preference for web-based instruction as a stand-alone program or as an adjunct to traditional classroom training, particularly citing the advantage of being able to engage the material at their own pace. Conclusion: With limited support, Latinos with minimal computer experience can effectively engage in web-based diabetes education