4,857 research outputs found

    Determining the Electron-Phonon Coupling Strength in Correlated Electron Systems from Resonant Inelastic X-ray Scattering

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    We show that high resolution Resonant Inelastic X-ray Scattering (RIXS) provides direct, element-specific and momentum-resolved information on the electron-phonon (e-p) coupling strength. Our theoretical analysis demonstrates that the e-p coupling can be extracted from RIXS spectra by determining the differential phonon scattering cross section. An alternative, very direct manner to extract the coupling is to use the one and two-phonon loss ratio, which is governed by the e-p coupling strength and the core-hole life-time. This allows measurement of the e-p coupling on an absolute energy scale.Comment: 4 pages, 3 figure

    A multi-disciplinary and comparative approach to evaluating pre-trial detention decisions: towards evidence-based reform

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    The decision to remand a defendant into custody pre-trial is one of the most controversial criminal justice decisions because it deprives individuals of their liberty while they are presumed to be innocent of a crime. Indeed, pre-trial detention decisions can have significant consequences for defendants, which need to be balanced against the potential implications of bail for public safety and the course of criminal proceedings. Despite this, court-based bail and remand decision-making remains relatively underexplored. In this paper, we compare court-based bail/remand decision-making in England and Wales and The Netherlands. We focus on (i) the procedure and structure of decision-making; (ii) the substantive relevant legal frameworks; (iii) the courts in which the decisions are made and the decision-makers in those courts; (iv) the conditions characterizing the decision task; and (v) the court’s reasoning of bail and remand in custody decisions. Using a comparative and multi-disciplinary approach, relying on Law, Criminology and Psychology, we make predictions about bail and remand in custody rates in the two jurisdictions as well as the decision performance of court-based decision-makers. These predictions are then evaluated using available (official) statistics and past research. We identify the need to collect more nuanced statistical data on bail and remand in custody rates and point to potentially fruitful avenues for future research. A comparative, multi-disciplinary, evidence-based approach can underpin remand reform in England and Wales, The Netherlands and beyond

    Doping dependence of magnetic excitations of 1D cuprates as probed by Resonant Inelastic x-ray Scattering

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    We study the dynamical, momentum dependent two- and four-spin response functions in doped and undoped 1D cuprates, as probed by resonant inelastic x-ray scattering, using an exact numerical diagonalization procedure. In the undoped tJt-J system the four-spin response vanishes at π\pi, whereas the two-spin correlator is peaked around π/2\pi/2, with generally larger spectral weight. Upon doping spectra tend to soften and broaden, with a transfer of spectral weight towards higher energy. However, the total spectral weight and average peak position of either response are only weakly affected by doping up to a concentration of 1/8. Only the two-spin response at π\pi changes strongly, with a large reduction of spectral weight and enhancement of excitation energy. At other momenta the higher-energy, generic features of the magnetic response are robust against doping. It signals the presence of strong short-range antiferromagnetic correlations, even after doping mobile holes into the system. We expect this to hold also in higher dimensions.Comment: 7 pages, 5 figure

    Between adaptability and the urge to control: making long-term water policies in the Netherlands

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    Triggered by recent flood catastrophes and increasing concerns about climate change, scientists as well as policy makers increasingly call for making long-term water policies to enable a transformation towards flood resilience. A key question is how to make these long-term policies adaptive so that they are able to deal with uncertainties and changing circumstances. The paper proposes three conditions for making long-term water policies adaptive, which are then used to evaluate a new Dutch water policy approach called ‘Adaptive Delta Management’. Analysing this national policy approach and its translation to the Rotterdam region reveals that Dutch policymakers are torn between adaptability and the urge to control. Reflecting on this dilemma, the paper suggests a stronger focus on monitoring and learning to strengthen the adaptability of long-term water policies. Moreover, increasing the adaptive capacity of society also requires a stronger engagement with local stakeholders including citizens and businesses

    Decentralized Implementation of Flood Resilience Measures – A Blessing or a Curse? Lessons from the Thames Estuary 2100 Plan and the Royal Docks Regeneration

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    This article presents a case study on the implementation of the Thames Estuary 2100 Plan in the Royal Docks, a regeneration project in the East of London. On paper, the Thames Estuary 2100 Plan advances the shift from traditional flood control to flood resilience, because of its long-term horizon, estuary-wide approach, and emphasis on floodplain management. In practice, however, we identify three frictions between vision and reality: a lack of local ownership of the plan, a lack of clear guidance for floodplain management, and limited capacities with local authority. These frictions suggest an ongoing ‘public-public divide’ in decentralized governance

    Correlation induced electron-hole asymmetry in quasi-2D iridates

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    We determine the motion of a charge (hole or electron) added to the Mott insulating, antiferromagnetic (AF) ground-state of quasi-2D iridates such as Ba 2 IrO 4 or Sr 2 IrO 4 . We show that correlation effects, calculated within the self-consistent Born approximation, render the hole and electron case very different. An added electron forms a spin-polaron, which closely resembles the well-known cuprates, but the situation of a removed electron is far more complex. Many-body 5d 4 configurations form which can be singlet and triplets of total angular momentum J and strongly affect the hole motion between AF sublattices. This not only has important ramifications for the interpretation of (inverse-)photoemission experiments of quasi-2D iridates but also demonstrates that the correlation physics in electron- and hole-doped iridates is fundamentally different.Comment: 11 pages main text, 11 pages supplementary, 10 figure

    Electronic Correlations in Oligo-acene and -thiophene Organic Molecular Crystals

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    From first principles calculations we determine the Coulomb interaction between two holes on oligo-acene and -thiophene molecules in a crystal, as a function of the oligomer length. The relaxation of the molecular geometry in the presence of holes is found to be small. In contrast, the electronic polarization of the molecules that surround the charged oligomer, reduces the bare Coulomb repulsion between the holes by approximately a factor of two. In all cases the effective hole-hole repulsion is much larger than the calculated valence bandwidth, which implies that at high doping levels the properties of these organic semiconductors are determined by electron-electron correlations.Comment: 5 pages, 3 figure

    Theory for Magnetism and Triplet Superconductivity in LiFeAs

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    Superconducting pnictides are widely found to feature spin-singlet pairing in the vicinity of an antiferromagnetic phase, for which nesting between electron and hole Fermi surfaces is crucial. LiFeAs differs from the other pnictides by (i) poor nesting properties and (ii) unusually shallow hole pockets. Investigating magnetic and pairing instabilities in an electronic model that incorporates these differences, we find antiferromagnetic order to be absent. Instead we observe almost ferromagnetic fluctuations which drive an instability toward spin-triplet p-wave superconductivity.Comment: Published versio
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