899 research outputs found

    Aspects of electron-phonon interactions with strong forward scattering in FeSe Thin Films on SrTiO3_3 substrates

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    Mono- and multilayer FeSe thin films grown on SrTiO3_\mathrm{3} and BiTiO3_\mathrm{3} substrates exhibit a greatly enhanced superconductivity over that found in bulk FeSe. A number of proposals have been advanced for the mechanism of this enhancement. One possibility is the introduction of a cross-interface electron-phonon (ee-phph) interaction between the FeSe electrons and oxygen phonons in the substrates that is peaked in the forward scattering (small q{\bf q}) direction due to the two-dimensional nature of the interface system. Motivated by this, we explore the consequences of such an interaction on the superconducting state and electronic structure of a two-dimensional system using Migdal-Eliashberg theory. This interaction produces not only deviations from the expectations of conventional phonon-mediated pairing but also replica structures in the spectral function and density of states, as probed by angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and quasi-particle interference imaging. We also discuss the applicability of Migdal-Eliashberg theory for a situation where the \ep interaction is peaked at small momentum transfer and in the FeSe/STO system

    Dynamics of a single exciton in strongly correlated bilayers

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    We formulated an effective theory for a single interlayer exciton in a bilayer quantum antiferromagnet, in the limit that the holon and doublon are strongly bound onto one interlayer rung by the Coulomb force. Upon using a rung linear spin wave approximation of the bilayer Heisenberg model, we calculated the spectral function of the exciton for a wide range of the interlayer Heisenberg coupling \alpha=J_{\perp}/Jz. In the disordered phase at large \alpha, a coherent quasiparticle peak appears representing free motion of the exciton in a spin singlet background. In the N\'{e}el phase, which applies to more realistic model parameters, a ladder spectrum arises due to Ising confinement of the exciton. The exciton spectrum is visible in measurements of the dielectric function, such as c-axis optical conductivity measurements.Comment: 28 pages, 12 figure

    Perspectives from Think College Students on Inclusive Practices at the Collegiate Level

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    Promoting inclusion at all levels of education is crucial in the process of positively influencing and encouraging student learning both for students with disabilities and their peers. This presentation will provide information about the Think College program and include perspectives from Think College students and their college peers about their experiences. Participants should be able to understand more about the Think College program, but more importantly gain an understanding about how the experiences within the program impact students’ lives

    Measurement error correlation within blocks of indicators in consistent partial least squares:Issues and remedies

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    Purpose The purpose of this paper is to enhance consistent partial least squares (PLSc) to yield consistent parameter estimates for population models whose indicator blocks contain a subset of correlated measurement errors. Design/methodology/approach Correction for attenuation as originally applied by PLSc is modified to include a priori assumptions on the structure of the measurement error correlations within blocks of indicators. To assess the efficacy of the modification, a Monte Carlo simulation is conducted. Findings In the presence of population measurement error correlation, estimated parameter bias is generally small for original and modified PLSc, with the latter outperforming the former for large sample sizes. In terms of the root mean squared error, the results are virtually identical for both original and modified PLSc. Only for relatively large sample sizes, high population measurement error correlation, and low population composite reliability are the increased standard errors associated with the modification outweighed by a smaller bias. These findings are regarded as initial evidence that original PLSc is comparatively robust with respect to misspecification of the structure of measurement error correlations within blocks of indicators. Originality/value Introducing and investigating a new approach to address measurement error correlation within blocks of indicators in PLSc, this paper contributes to the ongoing development and assessment of recent advancements in partial least squares path modeling

    Using Computer-assisted Qualitative Data Analysis Software (CAQDAS) to Re-examine Traditionally Analyzed Data: Expanding our Understanding of the Data and of Ourselves as Scholars

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    As diverse members of a college of education evaluation committee one of our charges is to support faculty as we document and improve our teaching. Our committee asked faculty to respond to three qualitative questions, documenting ways in which interdepartmental and cross-department conversations are used to promote reflective thinking about our practice. Three of us investigated the use of CAQDAS to provide an additional level of analysis and how we learned more about ourselves as scholars through this collaboration. Our findings include recommendations regarding the use of CAQDAS to support collaborative efforts by diverse scholars

    Market-oriented interventions and climate resilience in dryland agro-pastoralism

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    The Bible in Buffalo Country

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    Arriving in the remote Arnhem Land Aboriginal settlement of Oenpelli (Gunbalanya) in 1925, Alf and Mary Dyer aimed to bring Christ to a former buffalo shooting camp and an Aboriginal population many whites considered difficult to control. The Bible in Buffalo Country: Oenpelli Mission 1925–1931 represents a snapshot of the tumultuous first six years of the Church Missionary Society's mission at Oenpelli and the superintendency of Alfred Dyer between 1925 and 1931. Drawing together documentary and photographic sources with local community memory, a story emerges of miscommunication, sickness, constant logistical issues, and an Aboriginal community choosing when and how to engage with the newcomers to their land. This book provides a fascinating and detailed record of the primary sources of the mission, placed alongside the interpretation and insight of local Traditional Owners. Its contents include the historical and archaeological context of the primary source material, the vivid mission reports and correspondence, along with stunning photographs of the mission and relevant maps, and finally the oral history of Esther Manakgu, presenting Aboriginal memory of this complex era. The Bible in Buffalo Country emerged from community desire for access to the source documents of their own history and for their story to be known by the broader Australian public. It is intended for the benefit of communities in western Arnhem Land and is also a rich resource for historians of Aboriginal history (and other scholars in relevant disciplines)

    High speed laser drilling of metals using a high repetition rate, high average power ultrafast fiber CPA system

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    We present an experimental study on the drilling of metal targets with ultrashort laser pulses at high repetition rates (from 50 kHz up to 975 kHz) and high average powers (up to 68 Watts), using an ytterbium-doped fiber CPA system. The number of pulses to drill through steel and copper sheets with thicknesses up to 1 mm have been measured as a function of the repetition rate and the pulse energy. Two distinctive effects, influencing the drilling efficiency at high repetition rates, have been experimentally found and studied: particle shielding and heat accumulation. While the shielding of subsequent pulses due to the ejected particles leads to a reduced ablation efficiency, this effect is counteracted by heat accumulation. The experimental data are in good qualitative agreement with simulations of the heat accumulation effect and previous studies on the particle emission. However, for materials with a high thermal conductivity as copper, both effects are negligible for the investigated processing parameters. Therefore, the full power of the fiber CPA system can be exploited, which allows to trepan high-quality holes in 0.5mm-thick copper samples with breakthrough times as low as 75 ms. © 2008 Optical Society of America

    Anthracycline-Induced Cardiotoxicity: Cardiac Monitoring by Continuous Wave-Doppler Ultrasound Cardiac Output Monitoring and Correlation to Echocardiography

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    Background: Anthracyclines are agents with a well-known cardiotoxicity. The study sought to evaluate the hemodynamic response to an anthracycline using real-time continuous-wave (CW)-Doppler ultrasound cardiac output monitoring (USCOM) and echocardiography in combination with serum biomarkers. Methods: 50 patients (26 male, 24 female, median age 59 years) suffering from various types of cancer received an anthracycline-based regimen. Patients' responses were measured at different time points (T0 prior to infusion, T1 6 h post infusion, T2 after 1 day, T3 after 7 days, and T4 after 3 months) with CW-Doppler ultrasound (T0-T4) and echocardiography (T1, T4) for hemodynamic parameters such as stroke volume (SV; SVUSCOM ml) and ejection fraction (EF; EFechocardiography%) and with NT-pro-BNP and hs-Troponin T (T0-T4). Results: During the 3-month observation period, the relative decrease in the EF determined by echocardiography was -2.1% (Delta T0-T4, T0 71 +/- 7.8%, T4 69.5 +/- 7%, p = 0.04), whereas the decrease in SV observed using CW-Doppler was -6.5% (Delta T0-T4, T0 54 +/- 19.2 ml, T4 50.5 +/- 20.6 ml, p = 0.14). The kinetics for serum biomarkers were inversely correlated. Conclusions: Combining real-time CW-Doppler USCOM and serum biomarkers is feasible for monitoring the immediate and chronic hemodynamic changes during an anthracycline-based regimen; the results obtained were comparable to those from echocardiography
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