2,733 research outputs found

    Relativistic photoionization cross sections for C II

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    High resolution measurements of photoionization cross sections for atomic ions are now being made on synchrotron radiation sources. The recent measurements by Kjeldsen etal. (1999) showed good agreement between the observed resonance features and the the theoretical calculations in the close coupling approximation (Nahar 1995). However, there were several observed resonances that were missing in the theoretical predictions. The earlier theoretical calculation was carried out in LS coupling where the relativistic effects were not included. Present work reports photoionization cross sections including the relativistic effects in Breit-Pauli R-matrix (BPRM) approximation. The configuration interaction eigenfunction expansion for the core ion C III consists of 20 fine structure levels dominated by the configurations from 1s^22s^2 to 1s^22s3d. Detailed features in the calculated cross sections exhibit the missing resonances due to fine structure. The results benchmark the accuracy of BPRM photoionization cross sections as needed for recent and ongoing experiments.Comment: 13 pages, 3 figure

    A Unique Volume Balance Approach for Verifying the Three-Dimensional Hydrodynamic Numerical Models in Surface Waterbody Simulation

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    The hydrodynamic numerical modeling is increasingly becoming a widely used tool for simulating the surface waterbodies including rivers, lakes, and reservoirs. A challenging step in any model development is the verification tests, especially at the early stage of development. In this study, a unique approach was developed by implementing the volume balance principle in order to verify the three-dimensional hydrodynamic models for surface waterbody simulation. A developed and verified three-dimensional hydrodynamic and water quality model, called W3, was employed by setting a case study model to be verified using the volume balance technique. The model was qualified by calculating the error in the accumulated water volume within the domain every time step. Results showed that the volume balance reached a constant error over the simulation period, indicating a robust model setup

    Romanticizing Brahms: Early Recordings and the [De]Construction of Brahmsian Identity

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    Despite most pianists' claims of historical deference and creative agency, their performances of Brahms's piano works are nothing like the early-recorded performances of the composer and his students: gaps that are mediated by understandings of Brahms's Classical canonic identity, the performance norms that protect that identity, and those norms' underlying aesthetic ideology of control. This predication of Brahmsian identity on restraint leaves the composer and his students in a precarious situation, as their recordings evidence an approach that is governed by the inhibitions typically associated with Romanticism. This volume seeks to problematize understandings of Brahms's identity: by investigating the origins and vestiges of the aesthetic ideology of control; by analysing and copying the recordings of pianists in the composer's inner circle; and by applying these pianists' styles in ways that are just as disruptive to modern notions of Brahmsian identity as their early-recorded models. In so doing, a thoroughly Romantic performance style emerges that catalyses a fundamental shift in understanding as related to Brahms's identity; thereby opening up a new palette of expressive and technical resources, and both elucidating and narrowing persistent gaps between modern and early-recorded Brahms style, as well as between what performers believe, know, and ultimately do.Research in and through artistic practic

    An easy proof of Jensen's theorem on the uniqueness of infinity harmonic functions

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    We present a new, easy, and elementary proof of Jensen's Theorem on the uniqueness of infinity harmonic functions. The idea is to pass to a finite difference equation by taking maximums and minimums over small balls.Comment: 4 pages; comments added, proof simplifie

    Busy toy designs reduce the specificity of mothers' references to toy parts during toy play with their toddlers

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    When a parent is playing with a toy with his or her child, might a toy's "busy" visual design negatively impact the specificity and quality of the parent's talk? In this study, 24 mother-toddler (M = 23.5 months) dyads played with both (a) unmodified visually busy commercial toys and (b) modified visually "simple" versions of these commercial toys. Our focus was on the specificity of mothers' 552 references to the main parts of the toys (i.e., the rings of a stacking ring toy and the blocks of a nesting block toy), which was found to be impacted by the toys' visual design. That is, with simple toys, mothers produced a significantly greater proportion of specific references (e.g., the blue ring) than non-specific references (e.g., this/that one). Indeed, the proportion of specific references was three times greater in play with the simple toys than with the busy toys. Busy toys also reduced the number of references to parts of the toy overall and children's exposure to vocabulary such as colour terms used within specific references. These results underscore that the visual design of toys is an important aspect to consider, particularly in contexts where the goal may be to foster adult-child language and a child's exposure to more information-rich vocabulary terms during toy play with an adult. © 2019, Canadian Association of Speech-Language Pathologists and Audiologists. All rights reserved

    Creatine supplementation on cognitive performance following exercise in female Muay Thai athletes

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    BACKGROUND: Creatine supplementation has some beneficial effects on cognitive processing in healthy adults, including athletes; however the effects on cognitive function following exhaustive exercise in athletes is unknown. Therefore, the purpose was to determine the effects of 28 days of creatine supplementation on tasks of cognitive performance immediately following exhaustive exercise in Muay Thai female athletes compared to placebo. METHODS: Using a repeated measures, double-blind, placebo controlled design, 26 female Muay Thai athletes (age: 26 ± 5 years; body mass: 65.1 ± 6.6 kg; height: 162 ± 5 cm; training experience: 2.6 ± 0.6 years) were randomized to supplement with creatine monohydrate (3 g/day) or placebo (maltodextrin) for 28 days. Prior to and following supplementation, measures of cognitive performance were assessed (visual and auditory reaction time, corsi block test, visual forward digit span, and Erikson Flanker Task) immediately after exercise. RESULTS: There was a time main effect for auditory reaction time (p = 0.035), with no differences between groups. There was a trend for an interaction effect for visual reaction time (p = 0.067), visual go-no-go reaction time (p = 0.087), and Erikson Flanker task (p = 0.06), with exploratory post hoc tests revealing improvements over time in the creatine group (p \u3c 0.05) with no changes in the PLA group (p \u3e 0.05). CONCLUSION: Twenty-eight days of creatine supplementation appeared to have a small but positive effect on cognitive performance following exhaustive exercise in female Muay Thai athletes. Future research using a larger dose over a longer duration is warranted

    Calculating the mass fraction of primordial black holes

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    We reinspect the calculation for the mass fraction of primordial black holes (PBHs) which are formed from primordial perturbations, finding that performing the calculation using the comoving curvature perturbation c in the standard way vastly overestimates the number of PBHs, by many orders of magnitude. This is because PBHs form shortly after horizon entry, meaning modes significantly larger than the PBH are unobservable and should not affect whether a PBH forms or not - this important effect is not taken into account by smoothing the distribution in the standard fashion. We discuss alternative methods and argue that the density contrast, Δ, should be used instead as super-horizon modes are damped by a factor k2. We make a comparison between using a Press-Schechter approach and peaks theory, finding that the two are in close agreement in the region of interest. We also investigate the effect of varying the spectral index, and the running of the spectral index, on the abundance of primordial black holes

    Children show neural sensitivity to facial trustworthiness as measured by fast periodic visual stimulation

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    Acknowledgements We would like to thank Mirha Khan for helping to test pilot participants. Funding This research was supported by an Australian Government Research Training Program Scholarship to SS, and Australian Research Council (ARC) Discovery Early Career Research Award to C.S. [DE190101043], ARC Discovery Project to C.S. and R.P. [DP220101026], and R.P. and L. J. [DP140101743].Peer reviewedPostprin

    Perceptions and experiences of intrusive behaviour and stalking: Comparing LGBTIQ and heterosexual groups

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    The present research employed a mixed-methods approach and quasi-experimental design to examine perceptions and experiences of intrusive behavior (comprising 47 individual intrusive activities) within individuals identifying as lesbian, gay, bisexual, transgender, intersex, or queer (LGBTIQ) with a matched (in terms of age, sex, and income) sample of individuals identifying as heterosexual (N = 214). Despite only minor differences between the LGBTIQ and heterosexual groups concerning perceptions of the acceptability of intrusive behavior, the LGBTIQ group was more likely to report experiencing a range of individual intrusive activities and to report experiencing stalking victimization (self-reported rates of 35.5% vs. 15.0%). Participant sex and personal experience of being stalked were minimally associated with perceptions of the acceptability of intrusive behavior. Sexual orientation significantly predicted whether a person had experienced stalking victimization, whereas participant sex did not. The qualitative analysis revealed that the two groups shared some experiences of intrusive behavior, whereas others represented a unique subset of intrusions that related to sexual orientation

    A first-principles study of oxygen vacancy pinning of domain walls in PbTiO3

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    We have investigated the interaction of oxygen vacancies and 180-degree domain walls in tetragonal PbTiO3 using density-functional theory. Our calculations indicate that the vacancies do have a lower formation energy in the domain wall than in the bulk, thereby confirming the tendency of these defects to migrate to, and pin, the domain walls. The pinning energies are reported for each of the three possible orientations of the original Ti-O-Ti bonds, and attempts to model the results with simple continuum models are discussed.Comment: 8 pages, with 3 postscript figures embedded. Uses REVTEX and epsf macros. Also available at http://www.physics.rutgers.edu/~dhv/preprints/lh_dw/index.htm
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