Publications by authors named "H M Chapman"

Sub-ångström spatial resolution of electron density coupled with sub-femtosecond to few-femtosecond temporal resolution is required to directly observe the dynamics of the electronic structure of a molecule after photoinitiation or some other ultrafast perturbation, such as by soft X-rays. Meeting this challenge, pushing the field of quantum crystallography to attosecond timescales, would bring insights into how the electronic and nuclear degrees of freedom couple, enable the study of quantum coherences involved in molecular dynamics, and ultimately enable these dynamics to be controlled. Here, we propose to reach this realm by employing convergent-beam x-ray crystallography with high-power attosecond pulses from a hard-x-ray free-electron laser.

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Importance: There are limited data to guide practices to reduce surgical site infections following sacral neuromodulation; however, many surgeons prescribe prophylactic postoperative antibiotics after device implantation.

Objective: The aim of the study was to compare the proportion of patients with sacral neuromodulation device-associated surgical site infections after use of prophylactic postoperative antibiotics versus none.

Study Design: This was a multicenter retrospective cohort study of patients undergoing sacral neuromodulation device implantation at 11 institutions from January 2014 to December 2023, comparing outcomes in patients who did versus did not receive prophylactic postoperative antibiotic treatment.

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Background: Desmotomy of the accessory ligament of the superficial digital flexor tendon (AL-SDFT) has been described for the treatment of superficial digital flexor tendon (SDFT) tendinopathy in Thoroughbred and Standardbred racehorses, and in event horses. To our knowledge, the outcome of this procedure has not been described in a population of warmblood horses.

Objective: To report on the outcome of treatment of SDFT tendinopathy in warmblood horses using tenoscopic desmotomy of the main part of the AL-SDFT.

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High-resolution X-ray imaging of noncrystalline objects is often achieved through the approach of scanning coherent diffractive imaging known as ptychography. The imaging resolution is usually limited by the scattering properties of the sample, where weak diffraction signals at the highest scattering angles compete with parasitic scattering. Here, we demonstrate that X-ray multilayer Laue lenses with a high numerical aperture (NA) can be used to create a strong reference beam that holographically boosts weak scattering from the sample over a large range of scattering angles, enabling high-resolution imaging that is tolerant of such background.

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We report on recent developments that enable megahertz hard X-ray phase contrast imaging (MHz XPCI) experiments at the Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX) instrument of the European XFEL facility (EuXFEL). We describe the technical implementation of the key components, including an MHz fast camera and a modular indirect X-ray microscope system based on fast scintillators coupled through a high-resolution optical microscope, which enable full-field X-ray microscopy with phase contrast of fast and irreversible phenomena. The image quality for MHz XPCI data showed significant improvement compared with a pilot demonstration of the technique using parallel beam illumination, which also allows access to up to 24 keV photon energies at the SPB/SFX instrument of the EuXFEL.

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