4,515 research outputs found

    Dimensional crossover and cold-atom realization of topological Mott insulators

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    We propose a cold-atom setup which allows for a dimensional crossover from a two-dimensional quantum spin Hall insulating phase to a three-dimensional strong topological insulator by tuning the hopping between the layers. We further show that additional Hubbard onsite interactions can give rise to spin liquid-like phases: weak and strong topological Mott insulators. They represent the celebrated paradigm of a quantum state of matter which merely exists because of the interplay of the non-trivial topology of the band structure and strong interactions. While the theoretical understanding of this phase has remained elusive, our proposal shall help to shed some light on this exotic state of matter by paving the way for a controlled experimental investigation in optical lattices.Comment: 4+ pages, 3 figures; includes Supplemental Material (3 pages, 1 figure

    Establishing National Ocean Service Priorities for Estuarine, Coastal, and Ocean Modeling: Capabilities, Gaps, and Preliminary Prioritization Factors

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    This report was developed to help establish National Ocean Service priorities and chart new directions for research and development of models for estuarine, coastal and ocean ecosystems based on user-driven requirements and supportive of sound coastal management, stewardship, and an ecosystem approach to management. (PDF contains 63 pages

    Effect of 3 dietary phytogenic products on production performance and coccidiosis in challenged broiler chickens

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    A pen trial using 1,080 male Ross 308 broiler chicks (6 treatments with 6 replicates each) was conducted to examine the effects of 3 dietary phytogenic products on avian coccidiosis. The dietary treatments included (1) a negative control (NC), (2) a positive control (PC) without feed additive, (3) Narasin at 0.7 kg/t (COCC), (4) PHYT1 (oregano) at 2.0 kg/t, (5) PHYT2 (combination of Curcuma, saponins, and inulin) at 1.0 kg/t, and (6) PHYT3 (Quillaja) at 1.0 kg/t. Treatments 2 through 6 were challenged with a mixture of Eimeria acervulina, Eimeria maxima, and Eimeria tenella at d 15 via feed. Standard performance parameters and coccidial lesion scoring (d 22) were conducted. One week after coccidial challenge, chicks BW of the COCC treatment and the NC were higher than all other treatments. Body weights on d 39 were 2.47 (NC), 2.34 (PC), 2.51 (COCC), 2.35 (PHYT1), 2.39 (PHYT2), and 2.41 kg (PHYT3) with an SEM of 0.033. For the entire trial period, Narasin yielded a significantly better FCR in comparison with the PC and PHYT3. Overall mean lesion score was 0.54 (NC), 0.91 (PC), 0.50 (COCC), 0.81 (PHYT 1), 1.02 (PHYT 2), and 1.13 (PHYT 3) with an SEM of 0.122. It was concluded that all 3 phytogenic products were not effective at the used dosage in alleviating the negative effects observed in coccidiosis-challenged bird

    Abdominaler Schmerz

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    Zusammenfassung: Abdominalschmerzen können Ausdruck einer Vielzahl intra- und extraabdomineller Erkrankungen sein. Angesichts dieses breiten ätiologischen Spektrums gilt es, im Initialstadium der Diagnostik zielgerichtet vorzugehen, um ohne Zeitverzug die Ursache und damit letzlich die Dringlichkeit weitergehender Maßnahmen zu bestimmen. Ziel dieser Evaluation ist eine initiale risikostratifizierte Triagierung des Patienten. Im Gegensatz zu somatischen Ursachen abdominalen Schmerzes ist eine derartige kausale Therapie bei funktionellen Erkrankungen des Gastrointestinaltraktes zum gegenwärtigen Zeitpunkt nur sehr begrenzt möglich, sodass hierbei der Fokus auf eine bedarfs- und symptomadaptierte Behandlung gelegt werden sol

    Planning reform, land release and the supply of housing

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    There is a growing interest in academic and policy circles in the relationship between land use planning policy and housing supply. Housing researchers are interested in the extent to which planning policies and practises may be exacerbating housing affordability questions, while planning academics and practitioners focus on what effect their policies actually have on the characteristics of housing supply. Policies seeking a diversity of built form are underpinned by attempts to reduce energy consumption through smaller house sizes and the design of less car dependent suburbs. Urban Growth Boundaries (UGBs) and increased net housing densities seek to slow the expansion of cities into hinterlands and reduce travel costs. The impact of UGBs on house prices is one of a number of issues that remains contested (Nelson et al 2007; Buxton and Scheurer 2007)

    Electron irradiation effects on superconductivity in PdTe2_2: an application of a generalized Anderson theorem

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    Low temperature (\sim 20~K) electron irradiation with 2.5 MeV relativistic electrons was used to study the effect of controlled non-magnetic disorder on the normal and superconducting properties of the type-II Dirac semimetal PdTe2_2. We report measurements of longitudinal and Hall resistivity, thermal conductivity and London penetration depth using tunnel-diode resonator technique for various irradiation doses. The normal state electrical resistivity follows Matthiessen rule with an increase of the residual resistivity at a rate of \sim0.77μΩ \mu \Omegacm/(C/cm2)(\textrm{C}/\textrm{cm}^2). London penetration depth and thermal conductivity results show that the superconducting state remains fully gapped. The superconducting transition temperature is suppressed at a non-zero rate that is about sixteen times slower than described by the Abrikosov-Gor'kov dependence, applicable to magnetic impurity scattering in isotropic, single-band ss-wave superconductors. To gain information about the gap structure and symmetry of the pairing state, we perform a detailed analysis of these experimental results based on insight from a generalized Anderson theorem for multi-band superconductors. This imposes quantitative constraints on the gap anisotropies for each of the possible pairing candidate states. We conclude that the most likely pairing candidate is an unconventional A1g+A_{1g}^{+-} state. While we cannot exclude the conventional A1g++A_{1g}^{++} and the triplet A1uA_{1u}, we demonstrate that these states require additional assumptions about the orbital structure of the disorder potential to be consistent with our experimental results, e.g., a ratio of inter- to intra-band scattering for the singlet state significantly larger than one. Due to the generality of our theoretical framework, we think that it will also be useful for irradiation studies in other spin-orbit-coupled multi-orbital systems.Comment: 22 pages, 12 figure

    Low energy measurement of the 7Be(p,gamma)8B cross section

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    We have measured the cross section of the 7Be(p,gamma)8B reaction for E_cm = 185.8 keV, 134.7 keV and 111.7 keV using a radioactive 7Be target (132 mCi). Single and coincidence spectra of beta^+ and alpha particles from 8B and 8Be^* decay, respectively, were measured using a large acceptance spectrometer. The zero energy S factor inferred from these data is 18.5 +/- 2.4 eV b and a weighted mean value of 18.8 +/- 1.7 eV b (theoretical uncertainty included) is deduced when combining this value with our previous results at higher energies.Comment: Accepted for publication in Phys. Rev. Let
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