Publications by authors named "Allwood-Spiers S"

Purpose: Compared with lower field strengths, DWI at 7 T faces the combined challenges of increased distortion and blurring due to B inhomogeneity, and increased signal dropouts due to B inhomogeneity. This study addresses the B limitations using slice-specific static parallel transmission (pTx) in a multi-shot, readout-segmented EPI diffusion imaging sequence.

Methods: DWI was performed in 7 healthy subjects using MRI at 7 T and readout-segmented EPI.

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Background: The associations between deprivation and illness trajectory after hospitalisation for coronavirus disease-19 (COVID-19) are uncertain.

Methods: A prospective, multicentre cohort study was conducted on post-COVID-19 patients, enrolled either in-hospital or shortly post-discharge. Two evaluations were carried out: an initial assessment and a follow-up at 28-60 days post-discharge.

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Background: Post-COVID-19 syndromes have associated with female sex, but the pathophysiological basis is uncertain.

Aim: There are sex differences in myocardial inflammation identified using cardiac magnetic resonance (CMR) in post-COVID-19 patients, and in patient reported health outcomes following COVID-19 infection.

Design: This prospective study investigated the time-course of multiorgan injury in survivors of COVID-19 during convalescence.

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Background: We investigated the associations of healthcare worker status with multisystem illness trajectory in hospitalised post-COVID-19 individuals.

Methods And Results: One hundred and sixty-eight patients were evaluated 28-60 days after the last episode of hospital care. Thirty-six (21%) were healthcare workers.

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Purpose: To investigate the effects of using different parallel-transmit (pTx) head coils and specific absorption rate (SAR) supervision strategies on pTx pulse design for ultrahigh-field MRI using a 3D-MPRAGE sequence.

Methods: The PTx universal pulses (UPs) and fast online-customized (FOCUS) pulses were designed with pre-acquired data sets (B , B maps, specific absorption rate [SAR] supervision data) from two different 8 transmit/32 receive head coils on two 7T whole-body MR systems. For one coil, the SAR supervision model consisted of per-channel RF power limits.

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Article Synopsis
  • The study investigates long-term effects of COVID-19 on patients who were hospitalized, focusing on multisystem involvement and health outcomes over time.
  • At 28-60 days post-discharge, COVID-19 patients showed significant issues such as cardio-renal complications, reduced quality of life, increased anxiety and depression, and lower exercise capacity compared to controls.
  • Follow-up revealed that a considerable percentage of COVID-19 patients experienced rehospitalization or death, indicating ongoing health challenges that may strain healthcare resources in the future.
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Characterizing structural and tissue abnormalities of the kidney is fundamental to understanding kidney disease. Functional multi-parametric renal magnetic resonance imaging (MRI) is a noninvasive imaging strategy whereby several sequences are employed within a single session to quantify renal perfusion, tissue oxygenation, fibrosis, inflammation, and oedema without using ionizing radiation. In this review, we discuss evidence surrounding its use in several clinical settings including acute kidney injury, chronic kidney disease, hypertension, polycystic kidney disease and around renal transplantation.

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Objective: To assess interobserver reproducibility of different regions of interest (ROIs) on multi-parametric renal MRI using commercially available software.

Materials And Methods: Healthy volunteers (HV), patients with heart failure (HF) and renal transplant recipients (Tx) were recruited. Localiser scans, T1 mapping and pseudo-continuous arterial spin labelling (pCASL) were performed.

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Introduction And Background: A significant proportion of patients with intermediate and high risk squamous cell cancer of the oropharynx (OPSCC) continue to relapse locally despite radical chemoradiotherapy (CRT). The toxicity of the current combination of intensified dose per fraction radiotherapy and platinum based chemotherapy limits further uniform intensification. If a predictive biomarker for outcomes from CRT can be identified during treatment then individualised and adaptive treatment strategies may be employed.

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Article Synopsis
  • The study investigates how the number of charged particles produced in proton-lead collisions changes depending on how central the collision is, using data collected by the ATLAS detector at the Large Hadron Collider.
  • It focuses on measuring the mean charged-particle multiplicity across various pseudorapidity values and finds that the particle distribution demonstrates significant variation based on collision centrality, becoming more asymmetric as collisions become more central.
  • Three models are used to estimate the number of nucleons involved in the collision, revealing differing outcomes for charged-particle multiplicities, which emphasizes the need to consider color fluctuations in these interactions for more accurate modeling.
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The jet energy scale (JES) and its systematic uncertainty are determined for jets measured with the ATLAS detector using proton-proton collision data with a centre-of-mass energy of [Formula: see text] TeV corresponding to an integrated luminosity of [Formula: see text][Formula: see text]. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells using the anti-[Formula: see text] algorithm with distance parameters [Formula: see text] or [Formula: see text], and are calibrated using MC simulations. A residual JES correction is applied to account for differences between data and MC simulations.

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Measurements of four-lepton (4ℓ, ℓ=e,μ) production cross sections at the Z resonance in pp collisions at the LHC with the ATLAS detector are presented. For dilepton and four-lepton invariant mass regions m(ℓ+ℓ(-)) > 5 GeV and 80 View Article and Find Full Text PDF

This Letter presents a search for quantum black-hole production using 20.3 fb-1 of data collected with the ATLAS detector in pp collisions at the LHC at √s = 8 TeV. The quantum black holes are assumed to decay into a final state characterized by a lepton (electron or muon) and a jet.

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A search is presented for dark matter pair production in association with a W or Z boson in pp collisions representing 20.3  fb(-1) of integrated luminosity at √s=8  TeV using data recorded with the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet with the jet mass consistent with a W or Z boson, and with large missing transverse momentum are analyzed.

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This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using 4.7  fb(-1) of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at √s=7  TeV. Final states containing one or two isolated leptons (electrons or muons) and jets are considered.

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This paper presents a study of the performance of the muon reconstruction in the analysis of proton-proton collisions at [Formula: see text] TeV at the LHC, recorded by the ATLAS detector in 2010. This performance is described in terms of reconstruction and isolation efficiencies and momentum resolutions for different classes of reconstructed muons. The results are obtained from an analysis of [Formula: see text] meson and [Formula: see text] boson decays to dimuons, reconstructed from a data sample corresponding to an integrated luminosity of 40 pb[Formula: see text].

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A likelihood-based discriminant for the identification of quark- and gluon-initiated jets is built and validated using 4.7 fb[Formula: see text] of proton-proton collision data at [Formula: see text] [Formula: see text] collected with the ATLAS detector at the LHC. Data samples with enriched quark or gluon content are used in the construction and validation of templates of jet properties that are the input to the likelihood-based discriminant.

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The integrated elliptic flow of charged particles produced in Pb+Pb collisions at [Formula: see text] TeV has been measured with the ATLAS detector using data collected at the Large Hadron Collider. The anisotropy parameter, [Formula: see text], was measured in the pseudorapidity range [Formula: see text] with the event-plane method. In order to include tracks with very low transverse momentum [Formula: see text], thus reducing the uncertainty in [Formula: see text] integrated over [Formula: see text], a [Formula: see text] data sample recorded without a magnetic field in the tracking detectors is used.

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Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton-proton collision data collected in 2011 at [Formula: see text] TeV and corresponding to an integrated luminosity of 4.7 fb[Formula: see text].

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A measurement is presented of the [Formula: see text] production cross section at [Formula: see text] = 7 TeV using [Formula: see text] collision data corresponding to an integrated luminosity of 383 [Formula: see text], collected with the ATLAS experiment at the LHC. Selection of [Formula: see text](1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, [Formula: see text], and rapidity, [Formula: see text], of the [Formula: see text](1020) meson in the fiducial region 500 [Formula: see text] 1200 MeV, [Formula: see text] 0.

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A search is presented for direct top squark pair production using events with at least two leptons including a same-flavour opposite-sign pair with invariant mass consistent with the [Formula: see text] boson mass, jets tagged as originating from [Formula: see text]-quarks and missing transverse momentum. The analysis is performed with proton-proton collision data at [Formula: see text] collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20.3 fb[Formula: see text].

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Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, Δφ, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the Δφ dependence of jet yields in 0.14 nb(-1) of √(s(NN))=2.

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Two-particle correlations in relative azimuthal angle (Δø) and pseudorapidity (Δη) are measured in sqrt[s(NN)] = 5.02 TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1 μb(-1) of data as a function of transverse momentum (p(T)) and the transverse energy (ΣE(T)(Pb)) summed over 3.

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The ATLAS experiment has observed 1995 Z boson candidates in data corresponding to 0.15  nb(-1) of integrated luminosity obtained in the 2011 LHC Pb+Pb run at sqrt[s(NN)]=2.76  TeV.

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