2,792 research outputs found

    A survey of boat-based recreational fishing in inner Shark Bay 2016/17

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    Monitoring the temporal and spatial variability in recreational fishing provides necessary information for assessing resource sustainability, monitoring resource allocation and informing fisheries management. This is particularly important in inner Shark Bay because recreational fishing occurs in a World Heritage Area and Marine Park. The majority of boat-based recreational fishers in inner Shark Bay target Pink Snapper (Chrysophrys auratus) and three genetically distinct stocks of this species occur in the Denham Sound, Eastern Gulf and Freycinet Estuary Management Zones

    On the relation between the Feynman paradox and Aharonov-Bohm effects

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    The magnetic Aharonov-Bohm (A-B) effect occurs when a point charge interacts with a line of magnetic flux, while its dual, the Aharonov-Casher (A-C) effect, occurs when a magnetic moment interacts with a line of charge. For the two interacting parts of these physical systems, the equations of motion are discussed in this paper. The generally accepted claim is that both parts of these systems do not accelerate, while Boyer has claimed that both parts of these systems do accelerate. Using the Euler-Lagrange equations we predict that in the case of unconstrained motion only one part of each system accelerates, while momentum remains conserved. This prediction requires a time dependent electromagnetic momentum. For our analysis of unconstrained motion the A-B effects are then examples of the Feynman paradox. In the case of constrained motion, the Euler-Lagrange equations give no forces in agreement with the generally accepted analysis. The quantum mechanical A-B and A-C phase shifts are independent of the treatment of constraint. Nevertheless, experimental testing of the above ideas and further understanding of A-B effects which is central to both quantum mechanics and electromagnetism may be possible.Comment: 21 pages, 5 figures, recently submitted to New Journal of Physic

    Nonequilibrium Atom-Dielectric Forces Mediated by a Quantum Field

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    In this paper we give a first principles microphysics derivation of the nonequilibrium forces between an atom, treated as a three dimensional harmonic oscillator, and a bulk dielectric medium modeled as a continuous lattice of oscillators coupled to a reservoir. We assume no direct interaction between the atom and the medium but there exist mutual influences transmitted via a common electromagnetic field. By employing concepts and techniques of open quantum systems we introduce coarse-graining to the physical variables - the medium, the quantum field and the atom's internal degrees of freedom, in that order - to extract their averaged effects from the lowest tier progressively to the top tier. The first tier of coarse-graining provides the averaged effect of the medium upon the field, quantified by a complex permittivity (in the frequency domain) describing the response of the dielectric to the field in addition to its back action on the field through a stochastic forcing term. The last tier of coarse- graining over the atom's internal degrees of freedom results in an equation of motion for the atom's center of mass from which we can derive the force on the atom. Our nonequilibrium formulation provides a fully dynamical description of the atom's motion including back action effects from all other relevant variables concerned. In the long-time limit we recover the known results for the atom-dielectric force when the combined system is in equilibrium or in a nonequilibrium stationary state.Comment: 24 pages, 2 figure

    Enduro Campers

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    The Enduro Campers senior project team (Formerly known as Lobo Campers senior project team) was recruited by Mr. Leif Stein to assist in the design, manufacturing, and testing of the materials and components of his company’s expedition box camper. The two main focuses of the project, divided into two sub-teams, were on the testing and manufacturing process of the materials used in the camper, and on the design and analysis of the camper’s access door, step box, and other subsystems. The focus of the materials analysis and manufacturing team was based around the design parameter to use composite sandwich panels for the majority of the camper structure as set by Mr. Stein. This made the manufacturing and analysis of the camper much more complex than if a homogeneous material such as aluminum was used for the structure’s body. This increase in complexity is because composites are more difficult than homogenous materials to manufacture, test, and analyze. Because of this, the company needed a standardized physical testing procedure as well as an optimized bonding process for the sandwich materials. In order to choose the combination of materials for the sandwich panel construction, the project required a material analysis through physical testing and development of an FEA material model. The program ABAQUS was used to model the sandwich panel and can be applied to future analyses that Mr. Stein will need for larger, specific sections of the camper’s structure under different loading cases. The sub-component design & analysis team delivered a design for the door and step box of the camper that allows for maximum accessibility while maintaining the camper’s structural integrity while sealing the cabin from the elements. This design is also aesthetically pleasing, as these are the main visible components on the expedition box product. The design derived by our team was based on input from Mr. Stein, as well as the findings from the materials research team through analysis and physical testing. The manufacturing process of the step box was started and plans were handed to Mr. Stein for completion. This final design report goes over the project’s scope of work, concept design development, final design choices, manufacturing, design verification, project management, and the conclusions and recommendations the team has for Mr. Stein and his developing company. The report also includes recommendations for future analysis that can be helpful to better understanding the sandwich material used in the construction of the camper

    Applications of Gas Imaging Micro-Well Detectors to an Advanced Compton Telescope

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    We present a concept for an Advanced Compton Telescope (ACT) based on the use of pixelized gas micro-well detectors to form a three-dimensional electron track imager. A micro-well detector consists of an array of individual micro-patterned proportional counters opposite a planar drift electrode. When combined with thin film transistor array readouts, large gas volumes may be imaged with very good spatial and energy resolution at reasonable cost. The third dimension is determined from the drift time of the ionization electrons. The primary advantage of this approach is the excellent tracking of the Compton recoil electron that is possible in a gas volume. Such good electron tracking allows us to reduce the point spread function of a single incident photon dramatically, greatly improving the imaging capability and sensitivity. The polarization sensitivity, which relies on events with large Compton scattering angles, is particularly enhanced. We describe a possible ACT implementation of this technique, in which the gas tracking volume is surrounded by a CsI calorimeter, and present our plans to build and test a small prototype over the next three years.Comment: 7 pages, 6 figures, to appear in New Astronomy Reviews (proceedings of the Seeon Conference "Astronomy with Radioactivities IV and Filling the Sensitivity Gap in MeV Astronomy"

    Effective Implementation Capacity to Impact Change Within State Education Systems to Support Students With Disabilities

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    There is a continued call for the use of practices supported by evidence to improve the quality and effectiveness of services provided for students with disabilities. Despite best intentions, our education systems continue to struggle to adopt these practices and transfer them into consistent, sustained use by practitioners. Implementation science, the multi-disciplinary study of methods and strategies to promote use of research findings in practice, seeks to address this by providing frameworks to guide creation of conditions that facilitate use of evidence-based practices. The present article describes how an implementation science approach, Active Implementation Frameworks, was used by a national technical assistance center to cultivate systemic change and create improved outcomes for students with disabilities within several state, regional, and local education agencies. A summary of the lessons learned thus far and resulting considerations for practice and policy are presented. A key lesson was that state education agencies (SEAs) supporting districts and schools in implementation of a specific, educator-student-level practice realized improved outcomes for their students with disabilities. SEAs implementing frameworks or processes without an operationalized and measurable educator-student level practice had limited or no evidence of improved student outcomes

    A Dielectric Superfluid of Polar Molecules

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    We show that, under achievable experimental conditions, a Bose-Einstein condensate (BEC) of polar molecules can exhibit dielectric character. In particular, we derive a set of self-consistent mean-field equations that couple the condensate density to its electric dipole field, leading to the emergence of polarization modes that are coupled to the rich quasiparticle spectrum of the condensate. While the usual roton instability is suppressed in this system, the coupling can give rise to a phonon-like instability that is characteristic of a dielectric material with a negative static dielectric function.Comment: Version published in New Journal of Physics, 11+ pages, 4 figure

    Using WebGIS to Develop a Spatial Bibliography for Organizing, Mapping, and Disseminating Research Information: A Case Study of Quaking Aspen

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    On the Ground • Spatial data is valuable to researchers for locating studies that occur in a particular area of interest, or one with similar attributes. • Without a standard in publishing protocol, spatial data largely goes unreported, or is difficult to find without searching the publication. • Assigning location data and displaying points on a public web map makes locating publications based on spatial location possible

    Understanding plastic packaging: The co-evolution of materials and society

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    In recent years, the environmental problems associated with plastics have become a matter of global concern. Current responses seek to replace plastics with other materials, however it is not yet clear that these alternatives will deliver improved environmental outcomes. There remains an urgent need for more nuanced understandings of plastics, their role in society, and their environmental impacts. Drawing on social science perspectives that emphasise the co-evolution of materials and society, this paper outlines a socio-technical approach to plastics and social change. In this view, plastics are understood in terms of the networks and relations of which they are part – highlighting the limitations of both technological solutions and the blanket condemnation of particular materials. The analysis focuses specifically on plastic packaging, exploring the interplay of technological innovation and consumer practices to better account for processes of change. Our arguments are advanced through reference to three case studies: the launch of a ‘roast in the bag’ chicken by a food retailer, the switch to compostable packaging by a potato crisps (chips) brand, and the refilling of plastic bottles by a cosmetics company. Particular attention is paid to the relationships between commercial, environmental and regulatory concerns. To conclude, we consider implications of the approach presented here for transdisciplinary and policy debates about the problems associated with single-use plastics

    Associations of sedentary behaviour, physical activity, blood pressure and anthropometric measures with cardiorespiratory fitness in children with cerebral palsy

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    Background - Children with cerebral palsy (CP) have poor cardiorespiratory fitness in comparison to their peers with typical development, which may be due to low levels of physical activity. Poor cardiorespiratory fitness may contribute to increased cardiometabolic risk. Purpose - The aim of this study was to determine the association between sedentary behaviour, physical activity and cardiorespiratory fitness in children with CP. An objective was to determine the association between cardiorespiratory fitness, anthropometric measures and blood pressure in children with CP. Methods- This study included 55 ambulatory children with CP [mean (SD) age 11.3 (0.2) yr, range 6-17 yr; Gross Motor Function Classification System (GMFCS) levels I and II]. Anthropometric measures (BMI, waist circumference and waist-height ratio) and blood pressure were taken. Cardiorespiratory fitness was measured using a 10 m shuttle run test. Children were classified as low, middle and high fitness according to level achieved on the test using reference curves. Physical activity was measured by accelerometry over 7 days. In addition to total activity, time in sedentary behaviour and light, moderate, vigorous, and sustained moderate-to-vigorous activity (≥10 min bouts) were calculated. Results - Multiple regression analyses revealed that vigorous activity (β = 0.339, p<0.01), sustained moderate-to-vigorous activity (β = 0.250, p<0.05) and total activity (β = 0.238, p<0.05) were associated with level achieved on the shuttle run test after adjustment for age, sex and GMFCS level. Children with high fitness spent more time in vigorous activity than children with middle fitness (p<0.05). Shuttle run test level was negatively associated with BMI (r2 = -0.451, p<0.01), waist circumference (r2 = -0.560, p<0.001), waist-height ratio (r2 = -0.560, p<0.001) and systolic blood pressure (r2 = -0.306, p<0.05) after adjustment for age, sex and GMFCS level. Conclusions - Participation in physical activity, particularly at a vigorous intensity, is associated with high cardiorespiratory fitness in children with CP. Low cardiorespiratory fitness is associated with increased cardiometabolic risk
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