3,172 research outputs found

    Nondegeneracy and Stability of Antiperiodic Bound States for Fractional Nonlinear Schr\"odinger Equations

    Full text link
    We consider the existence and stability of real-valued, spatially antiperiodic standing wave solutions to a family of nonlinear Schr\"odinger equations with fractional dispersion and power-law nonlinearity. As a key technical result, we demonstrate that the associated linearized operator is nondegenerate when restricted to antiperiodic perturbations, i.e. that its kernel is generated by the translational and gauge symmetries of the governing evolution equation. In the process, we provide a characterization of the antiperiodic ground state eigenfunctions for linear fractional Schr\"odinger operators on R\mathbb{R} with real-valued, periodic potentials as well as a Sturm-Liouville type oscillation theory for the higher antiperiodic eigenfunctions.Comment: 46 pages, 2 figure

    Opting Out of Opting In: Switching Our Profile Workflow to Include Every University Faculty Member

    Get PDF
    Starting this semester, Charles C. Sherrod Library at East Tennessee State University (ETSU) began shifting our SelectedWorks service model from an opt-in (we create profiles for faculty who send us their CV) process to a quicker and easier opt-out (we create profiles for all faculty) model. Our lightning talk will provide an overview of this opt-out model and how we laid the groundwork for its success. We started by engendering support amongst the Deans, Faculty Senate, and University Research Council, detailing the benefits of a university-wide profile service and assuaging any fears or concerns that an opt-out model might generate regarding utility and privacy. We also undertook a substantial harvesting project as part of this project using Digital Common\u27s PubMed and Scopus integration to harvest thousands of ETSU-affiliated records into our repository. We create these instant profiles by aggregating publicly assessable information (such as contact information, education, etc.) from available sources such as university departmental pages, LinkedIn, ResearchGate, etc. to complete their About information without needing a copy of their CV. We then import all available works into the profile from the aforementioned harvesting project. Once completed, we email the faculty member in question and give them two weeks to accept or decline their profile before going live. This will greatly expand the reach of our department\u27s service and further integrate our portion of the library into the academic community of the university

    Transitions in coral reef accretion rates linked to intrinsic ecological shifts on turbid-zone nearshore reefs

    Get PDF
    Nearshore coral communities within turbid settings are typically perceived to have limited reef-building capacity. However, several recent studies have reported reef growth over millennial time scales within such environments and have hypothesized that depth-variable community assemblages may act as equally important controls on reef growth as they do in clear-water settings. Here, we explicitly test this idea using a newly compiled chronostratigraphic record (31 cores, 142 radiometric dates) from seven proximal (but discrete) nearshore coral reefs located along the central Great Barrier Reef (Australia). Uniquely, these reefs span distinct stages of geomorphological maturity, as reflected in their elevations below sea level. Integrated age-depth and ecological data sets indicate that contemporary coral assemblage shifts, associated with changing light availability and wave exposure as reefs shallowed, coincided with transitions in accretion rates at equivalent core depths. Reef initiation followed a regional ∌1 m drop in sea level (1200–800 calibrated yr B.P.) which would have lowered the photic floor and exposed new substrate for coral recruitment by winnowing away fine seafloor sediments. We propose that a two-way feedback mechanism exists where past growth history influences current reef morphology and ecology, ultimately driving future reef accumulation and morphological change. These findings provide the first empirical evidence that nearshore reef growth trajectories are intrinsically driven by changes in coral community structure as reefs move toward sea level, a finding of direct significance for predicting the impacts of extrinsically driven ecological change (e.g., coral-algal phase shifts) on reef growth potential within the wider coastal zone on the Great Barrier Reef

    A Tale of Two Cities: A Comparative Case Study of Community Engagement and Costs in Two Levy Campaigns

    Get PDF
    Using Anderson’s (1998) framework for authentic community engagement and Levin and McEwan’s (2001) “ingredients method,” this comparative case study analyzed contrasting approaches to levy campaigns undertaken by two suburban school districts and the associated costs of the campaigns. We found that District A ran a campaign that “authentically” engaged community members with lower opportunity costs for district personnel (administrators and teachers) and success at the polls. District B ran a “central office campaign” with higher opportunity costs for district personnel and defeat at the polls. While overall costs for District A were higher than those of District B, costs per registered voter were lower for District A than District B

    Arthropod Fauna Associated with Wild and Cultivated Cranberries in Wisconsin

    Get PDF
    The cranberry (Vaccinium macrocarpon Aiton) is an evergreen, trailing shrub native to North American peatlands. It is cultivated commercially in the US and Canada, with major production centers in Wisconsin, Massachusetts, New Jersey, Washington, Québec, and British Columbia. Despite the agricultural importance of cranberry in Wisconsin, relatively little is known of its arthropod associates, particularly the arachnid fauna. Here we report preliminary data on the insect and spider communities associated with wild and cultivated cranberries in Wisconsin. We then compare the insect and spider communities of wild cranberry systems to those of cultivated cranberries, indexed by region. Approximately 7,400 arthropods were curated and identified, spanning more than 100 families, across 11 orders. The vast majority of specimens and diversity derived from wild ecosystems. In both the wild and cultivated systems, the greatest numbers of families were found among the Diptera (midges, flies) and Hymenoptera (bees, ants, wasps), but numerically, the Hymenoptera and Araneae (spiders) were dominant. Within the spider fauna, 18 new county records, as well as a new Wisconsin state record (Linyphiidae: Ceratinopsis laticeps (Em.)), were documented. While more extensive sampling will be needed to better resolve arthropod biodiversity in North American cranberry systems, our findings represent baseline data on the breadth of arthropod diversity in the Upper Midwest, USA

    Assessing food appeal and desire to eat: the effects of portion size & energy density

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Visual presentation of food provides considerable information such as its potential for palatability and availability, both of which can impact eating behavior.</p> <p>Methods</p> <p>We investigated the subjective ratings for food appeal and desire to eat when exposed to food pictures in a fed sample (n = 129) using the computer paradigm ImageRate. Food appeal and desire to eat were analyzed for the effects of food group, portion size and energy density of the foods presented as well as by participant characteristics.</p> <p>Results</p> <p>Food appeal ratings were significantly higher than those for desire to eat (57.9 ± 11.6 v. 44.7 ± 18.0; <it>p </it>< 0.05). Body mass index was positively correlated to desire to eat (<it>r </it>= 0.20; <it>p </it>< 0.05), but not food appeal. Food category analyses revealed that fruit was the highest rated food category for both appeal and desire, followed by discretionary foods. Additionally, overweight individuals reported higher ratings of desire to eat large portions of food compared to smaller portions (<it>p </it>< 0.001), although these effects were relatively small. Energy density of the foods was inversely correlated with ratings for both appeal and desire (<it>r</it>'s = - 0.27; <it>p</it>'s < 0.01).</p> <p>Conclusions</p> <p>Results support the hypothesis that individuals differentiate between food appeal and desire to eat foods when assessing these ratings using the same type of metric. Additionally, relations among food appeal and desire to eat ratings and body mass show overweight individuals could be more responsive to visual foods cues in a manner that contributes to obesity.</p

    Evaluation of the 20 L Dust Explosibility Testing Chamber and Comparison to a Modified 38 L Vessel for Underground Coal

    Get PDF
    The phenomenon of combustible dust explosions is present within many industries. Tests for explosibility of dust clouds per ASTM E1226 use a 20 L explosive chamber that places the combustible dust directly below the dispersion nozzle which generates a thorough mixture for testing purposes. However, in the underground coal mining industry, there are a number of geologic, mining, and regulatory factors that change the deposition scheme of combustible coal dust. This causes the atmosphere of a coal mine to have a variable rock dust-coal dust mixture at the time of ignition. To investigate the impact of this variable atmosphere, a series of lean explosibility tests were conducted on a sample of Pittsburgh Pulverized coal dust. These explosibility tests were conducted in a 38 L chamber with a 5 kJ Sobbe igniter. The 38 L chamber generates a variable air-dust mixture prior to ignition. The test results indicate that the 38 L chamber experiences reduced explosive pressures, and lower explosibility index values when compared to the 20 L chamber

    The First Second of Volcanic Eruptions from the Erebus Volcano Lava Lake, Antarctica—Energies, Pressures, Seismology, and Infrasound

    Get PDF
    [1] We describe a multiparameter experiment at Erebus volcano, Antarctica, employing Doppler radar, video, acoustic, and seismic observations to estimate the detailed energy budget of large (up to 40 m-diameter) bubble bursts from a persistent phonolite lava lake. These explosions are readily studied from the crater rim at ranges of less than 500 m and present an ideal opportunity to constrain the dynamics and mechanism of magmatic bubble bursts that can drive Strombolian and Hawaiian eruptions. We estimate the energy budget of the first second of a typical Erebus explosion as a function of time and energy type. We constrain gas pressures and forces using an analytic model for the expansion of a gas bubble above a conduit that incorporates conduit geometry and magma and gas parameters. The model, consistent with video and radar observations, invokes a spherical bulging surface with a base diameter equal to that of the lava lake. The model has no ad hoc free parameters, and geometrical calculations predict zenith height, velocity, and acceleration during shell expansion. During explosions, the energy contained in hot overpressured gas bubbles is freed and partitioned into other energy types, where by far the greatest nonthermal energy component is the kinetic and gravitational potential energy of the accelerated magma shell (\u3e109 J). Seismic source energy created by explosions is estimated from radar measurements and is consistent with source energy determined from seismic observations. For the generation of the infrasonic signal, a dual mechanism incorporating a terminally disrupted slug is proposed, which clarifies previous models and provides good fits to observed infrasonic pressures. A new and straightforward method is presented for determining gas volumes from slug explosions at volcanoes from remote infrasound recordings
    • 

    corecore