256 research outputs found

    Harmonic oscillations and their switching in elliptical optical waveguide arrays

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    We have studied harmonic oscillations in an elliptical optical waveguide array in which the coupling between neighboring waveguides is varied in accord with a Kac matrix so that the propagation constant eigenvalues can take equally spaced values. As a result, long-living Bloch oscillation (BO) and dipole oscillation (DO) are obtained when a linear gradient in the propagation constant is applied. Moreover, we achieve a switching from DO to BO or vice versa by ramping up the gradient profile. The various optical oscillations as well as their switching are investigated by field evolution analysis and confirmed by Hamiltonian optics. The equally spaced eigenvalues in the propagation constant allow viable applications in transmitting images, switching and routing of optical signals.Comment: 14 pages, 5 figure

    Schrodinger cat states prepared by Bloch oscillation in a spin-dependent optical lattice

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    We propose to use Bloch oscillation of ultra-cold atoms in a spin-dependent optical lattice to prepare schrodinger cat states. Depending on its internal state, an atom feels different periodic potentials and thus has different energy band structures for its center-of-mass motion. Consequently, under the same gravity force, the wave packets associated with different internal states perform Bloch oscillation of different amplitudes in space and in particular they can be macroscopically displaced with respect to each other. In this way, a cat state can be prepared.Comment: 4 pages, 3 figures; slightly modifie

    Can auditors be independent? – Experimental evidence on the effects of client type

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    Recent regulatory initiatives stress that an independent oversight board, rather than the management board, should be the client of the auditor. In an experiment, we test whether the type of client affects auditors’ independence. Unique features of the German institutional setting enable us to realistically vary the type of auditors’ client as our treatment variable: we portray the client either as the management preferring aggressive accounting or the oversight board preferring conservative accounting. We measure auditors’ perceived client retention incentives and accountability pressure in a post-experiment questionnaire to capture potential threats to independence. We find that the type of auditors’ client affects auditors’ behaviour contingent on the degree of the perceived threats to independence. Our findings imply that both client retention incentives and accountability pressure represent distinctive threats to auditors’ independence and that the effectiveness of an oversight board in enhancing auditors’ independence depends on the underlying threat

    Exploring associations between positive and negative valanced parental comments about adolescents' bodies and eating and eating problems: a community study.

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    BACKGROUND: Adolescence is a time of rapid emotional and physical development when foundational self-concepts (including beliefs about one's weight and shape) are established. Parents are key influencers of adolescent beliefs and behaviours. This study aimed to investigate associations between perceived positive and negative parental comments on weight/shape and eating, with sons' and daughters' psychological distress and eating disorder cognitions (EDCs). METHODS: A representative mixed-sex sample of 2204 Australian adolescents (12-19 years) from the EveryBODY Study completed an online survey exploring eating behaviours, psychological wellbeing and experiences of parental comments regarding weight, shape and eating behaviours. RESULTS: Correlation analyses revealed that adolescents' reports of perceived positive parental comments on shape/weight were significantly associated with lower psychological distress and EDCs only for daughters. All perceived negative parental comments on shape/weight or eating were associated with greater psychological distress and EDCs for both sons and daughters. In the final model of the regression analysis, only perceived parental negative shape/weight and maternal negative eating comments, adolescent stage and biological sex were significantly associated with EDCs. When known contributors such as BMI percentile and psychological distress were included in the regression model, adolescent stage and perceived negative paternal comments were no longer significantly associated with EDCs. CONCLUSIONS: Overall, results show perceived negative comments were associated with poorer adolescent mental health, both their specific EDCs and general distress. Findings highlight the importance of raising awareness of potential negative impacts within family systems of comments around weight/shape and eating in these key formative years. Trial Registration The study was approved by the Macquarie University Human Research Ethics Committee (HREC 5201600312) and the New South Wales Department of Education

    The Association Between Adverse Childhood Experiences (ACEs), Bullying Victimization, and Internalizing and Externalizing Problems Among Early Adolescents: Examining Cumulative and Interactive Associations

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    Both adverse childhood experiences (ACEs) and bullying victimization are linked with mental health problems in adolescents. However, little is known about the overlap between the two factors and how this impacts adolescent mental health problems (i.e., internalizing and externalizing problems). The current study analyzed data from 8,085 participants (47.7% female; 44.1% racial/ethnic minority) in the Adolescent Brain Cognitive Development (ABCD) study, baseline (2016–2018, ages 9–10 years) to Year 2. Regression analyses were used to estimate associations between ACEs, bullying victimization and mental health problems, respectively, adjusting for sex, race/ethnicity, country of birth, household income, parental education, and study site. The findings showed that both ACEs and bullying victimization were independently associated with higher internalizing and higher externalizing problems. However, no significant interaction was found between ACEs and bullying victimization. Overall, the results align with the cumulative risk model of adversity, linking cumulative ACEs and bullying victimization to internalizing and externalizing problems in early adolescents

    Solitons in one-dimensional nonlinear Schr\"{o}dinger lattices with a local inhomogeneity

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    In this paper we analyze the existence, stability, dynamical formation and mobility properties of localized solutions in a one-dimensional system described by the discrete nonlinear Schr\"{o}dinger equation with a linear point defect. We consider both attractive and repulsive defects in a focusing lattice. Among our main findings are: a) the destabilization of the on--site mode centered at the defect in the repulsive case; b) the disappearance of localized modes in the vicinity of the defect due to saddle-node bifurcations for sufficiently strong defects of either type; c) the decrease of the amplitude formation threshold for attractive and its increase for repulsive defects; and d) the detailed elucidation as a function of initial speed and defect strength of the different regimes (trapping, trapping and reflection, pure reflection and pure transmission) of interaction of a moving localized mode with the defect.Comment: 12 pages, 10 figure

    Impact of Excess Auditor Remuneration on the Cost of Equity Capital around the World

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    This study examines the relation between excess auditor remuneration and the implied required rate of return (IRR hereafter) on equity capital in global markets. We conjecture that when auditor remuneration is excessively large, investors may perceive the auditor to be economically bonded to the client, leading to a lack of independence. This perceived lack of independence increases the information risk associated with the credibility of financial statements, thereby increasing IRR. Consistent with this notion, we find that IRR is increasing in excess auditor remuneration, but only in countries with stronger investor protection. Finding evidence of a relation only in stronger investor protection countries is consistent with the more prominent role of audited financial statements for investors' decisions in these countries. In settings in which investors are less likely to rely on audited financial statements and instead rely on alternative sources of information (i.e., in countries with weaker investor protection), the impact of client-auditor bonding should have less of an effect on investors' decisions.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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