1,763 research outputs found
The amateurs. A complete guide for non-professional dramatic organizations.
Thesis (M.A.)--Boston University
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A weakly correlated Fermi liquid state with a small Fermi surface in lightly doped SrIrO
We characterize the electron doping evolution of
(SrLa)IrO by means of angle-resolved photoemission.
Concomitant with the metal insulator transition around we find
the emergence of coherent quasiparticle states forming a closed small Fermi
surface of volume , where is the independently measured La
concentration. The quasiparticle weight remains large along the entire
Fermi surface, consistent with the moderate renormalization of the low-energy
dispersion. This indicates a conventional, weakly correlated Fermi liquid state
with a momentum independent residue in lightly doped
SrIrO$_7&.Comment: 5 pages, 4 figure
Limiting the effects of earthquakes on gravitational-wave interferometers
Ground-based gravitational wave interferometers such as the Laser
Interferometer Gravitational-wave Observatory (LIGO) are susceptible to
high-magnitude teleseismic events, which can interrupt their operation in
science mode and significantly reduce the duty cycle. It can take several hours
for a detector to stabilize enough to return to its nominal state for
scientific observations. The down time can be reduced if advance warning of
impending shaking is received and the impact is suppressed in the isolation
system with the goal of maintaining stable operation even at the expense of
increased instrumental noise. Here we describe an early warning system for
modern gravitational-wave observatories. The system relies on near real-time
earthquake alerts provided by the U.S. Geological Survey (USGS) and the
National Oceanic and Atmospheric Administration (NOAA). Hypocenter and
magnitude information is generally available in 5 to 20 minutes of a
significant earthquake depending on its magnitude and location. The alerts are
used to estimate arrival times and ground velocities at the gravitational-wave
detectors. In general, 90\% of the predictions for ground-motion amplitude are
within a factor of 5 of measured values. The error in both arrival time and
ground-motion prediction introduced by using preliminary, rather than final,
hypocenter and magnitude information is minimal. By using a machine learning
algorithm, we develop a prediction model that calculates the probability that a
given earthquake will prevent a detector from taking data. Our initial results
indicate that by using detector control configuration changes, we could prevent
interruption of operation from 40-100 earthquake events in a 6-month
time-period
Anisotropic exchange and spin-wave damping in pure and electron-doped SrIrO
The collective magnetic excitations in the spin-orbit Mott insulator
(SrLa)IrO () were investigated by
means of resonant inelastic x-ray scattering. We report significant magnon
energy gaps at both the crystallographic and antiferromagnetic zone centers at
all doping levels, along with a remarkably pronounced momentum-dependent
lifetime broadening. The spin-wave gap is accounted for by a significant
anisotropy in the interactions between isospins, thus
marking the departure of SrIrO from the essentially isotropic
Heisenberg model appropriate for the superconducting cuprates.Comment: 6 pages, 4 figure
The importance of XY anisotropy in Sr2IrO4 revealed by magnetic critical scattering experiments
The magnetic critical scattering in SrIrO has been characterized
using X-ray resonant magnetic scattering (XRMS) both below and above the 3D
antiferromagnetic ordering temperature, T. The order parameter
critical exponent below T is found to be \beta=0.195(4), in the
range of the 2D XYh universality class. Over an extended temperature range
above T, the amplitude and correlation length of the intrinsic
critical fluctuations are well described by the 2D Heisenberg model with XY
anisotropy. This contrasts with an earlier study of the critical scattering
over a more limited range of temperature which found agreement with the theory
of the isotropic 2D Heisenberg quantum antiferromagnet, developed to describe
the critical fluctuations of the conventional Mott insulator LaCuO and
related systems. Our study therefore establishes the importance of XY
anisotropy in the low-energy effective Hamiltonian of SrIrO, the
prototypical spin-orbit Mott insulator.Comment: 6 pages, 4 figure
Right ventricular function is a predictor for sustained ventricular tachycardia requiring anti-tachycardic pacing in arrhythmogenic ventricular cardiomyopathy: insight into transvenous vs. subcutaneous implantable cardioverter defibrillator insertion
AIMS: Arrhythmogenic right ventricular cardiomyopathy (ARVC) patients develop ventricular arrhythmias (VAs) responsive to anti-tachycardia pacing (ATP). However, VA episodes have not been characterized in accordance with the device therapy, and with the emergence of the subcutaneous implantable cardioverter defibrillator (S-ICD), the appropriate device prescription in ARVC remains unclear. Study aim was to characterize VA events in ARVC patients during follow-up in accordance with device therapy and elicit if certain parameters are predictive of specific VA events. METHODS AND RESULTS: This was a retrospective single-centre study utilizing prospectively collated registry data of ARVC patients with ICDs. Forty-six patients were included [54.0 ± 12.1 years old and 20 (43.5%) secondary prevention devices]. During a follow-up of 12.1 ± 6.9 years, 31 (67.4%) patients had VA events [n = 2, 6.5% ventricular fibrillation (VF), n = 14], 45.2% VT falling in VF zone resulting in ICD shock(s), n = 10, 32.3% VT resulting in ATP, and n = 5, 16.1% patients had both VT resulting in ATP and ICD shock(s). Lead failure rates were high (11/46, 23.9%). ATP was successful in 34.5% of patients. Severely impaired right ventricular (RV) function was an independent predictor of VT resulting in ATP (hazard ratio 16.80, 95% confidence interval 3.74–75.2; P < 0.001) with a high predictive accuracy (area under the curve 0.88, 95%CI 0.76–1.00; P < 0.001). CONCLUSION: VA event rates are high in ARVC patients with a majority having VT falling in the VF zone resulting in ICD shock(s). S-ICDs could be of benefit in most patients with ARVC with the absence of severely impaired RV function which has the potential to avoid consequences of the high burden of lead failure
Collapse of the Mott gap and emergence of a nodal liquid in lightly doped SrIrO
Superconductivity in underdoped cuprates emerges from an unusual electronic
state characterised by nodal quasiparticles and an antinodal pseudogap. The
relation between this state and superconductivity is intensely studied but
remains controversial. The discrimination between competing theoretical models
is hindered by a lack of electronic structure data from related doped Mott
insulators. Here we report the doping evolution of the Heisenberg
antiferromagnet SrIrO, a close analogue to underdoped cuprates. We
demonstrate that metallicity emerges from a rapid collapse of the Mott gap with
doping, resulting in lens-like Fermi contours rather than disconnected Fermi
arcs as observed in cuprates. Intriguingly though, the emerging electron liquid
shows nodal quasiparticles with an antinodal pseudogap and thus bares strong
similarities with underdoped cuprates. We conclude that anisotropic pseudogaps
are a generic property of two-dimensional doped Mott insulators rather than a
unique hallmark of cuprate high-temperature superconductivity
The potential role of cost-utility analysis in the decision to implement major system change in acute stroke services in metropolitan areas in England
BACKGROUND: The economic implications of major system change are an important component of the decision to implement health service reconfigurations. Little is known about how best to report the results of economic evaluations of major system change to inform decision-makers. Reconfiguration of acute stroke care in two metropolitan areas in England, namely London and Greater Manchester (GM), was used to analyse the economic implications of two different implementation strategies for major system change. METHODS: A decision analytic model was used to calculate difference-in-differences in costs and outcomes before and after the implementation of two major system change strategies in stroke care in London and GM. Values in the model were based on patient level data from Hospital Episode Statistics, linked mortality data from the Office of National Statistics and data from two national stroke audits. Results were presented as net monetary benefit (NMB) and using Programme Budgeting and Marginal Analysis (PBMA) to assess the costs and benefits of a hypothetical typical region in England with approximately 4000 strokes a year. RESULTS: In London, after 90 days, there were nine fewer deaths per 1000 patients compared to the rest of England (95% CI -24 to 6) at an additional cost of £770,027 per 1000 stroke patients admitted. There were two additional deaths (95% CI -19 to 23) in GM, with a total costs saving of £156,118 per 1000 patients compared to the rest of England. At a £30,000 willingness to pay the NMB was higher in London and GM than the rest of England over the same time period. The results of the PBMA suggest that a GM style reconfiguration could result in a total greater health benefit to a region. Implementation costs were £136 per patient in London and £75 in GM. CONCLUSIONS: The implementation of major system change in acute stroke care may result in a net health benefit to a region, even one functioning within a fixed budget. The choice of what model of stroke reconfiguration to implement may depend on the relative importance of clinical versus cost outcomes
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