12 research outputs found
Hartree-Fock Theory of Hole Stripe States
We report on Hartree-Fock theory results for stripe states of two-dimensional
hole systems in quantum wells grown on GaAs (311)A substrates. We find that the
stripe orientation energy has a rich dependence on hole density, and on
in-plane field magnitude and orientation. Unlike the electron case, the
orientation energy is non-zero for zero in-plane field, and the ground state
orientation can be either parallel or perpendicular to a finite in-plane field.
We predict an orientation reversal transition in in-plane fields applied along
the direction.Comment: 5 pages including 4 figure
Single-Band Model for Diluted Magnetic Semiconductors: Dynamical and Transport Properties and Relevance of Clustered States
Dynamical and transport properties of a simple single-band spin-fermion
lattice model for (III,Mn)V diluted magnetic semiconductors (DMS) is here
discussed using Monte Carlo simulations. This effort is a continuation of
previous work (G. Alvarez, Phys. Rev. Lett. 89, 277202 (2002)) where the static
properties of the model were studied. The present results support the view that
the relevant regime of J/t (standard notation) is that of intermediate
coupling, where carriers are only partially trapped near Mn spins, and locally
ordered regions (clusters) are present above the Curie temperature T_C. This
conclusion is based on the calculation of the resistivity vs. temperature, that
shows a soft metal to insulator transition near T_C, as well on the analysis of
the density-of-states and optical conductivity. In addition, in the clustered
regime a large magnetoresistance is observed in simulations. Formal analogies
between DMS and manganites are also discussed.Comment: Revtex4, 20 figures. References updated, minor changes to figures and
tex
Partitioning the Heritability of Tourette Syndrome and Obsessive Compulsive Disorder Reveals Differences in Genetic Architecture
The direct estimation of heritability from genome-wide common variant data as implemented in the program Genome-wide Complex Trait Analysis (GCTA) has provided a means to quantify heritability attributable to all interrogated variants. We have quantified the variance in liability to disease explained
Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures
Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo
Global circumferential and radial strain among patients with immune checkpoint inhibitor myocarditis
BACKGROUND Global circumferential strain (GCS) and global radial strain (GRS) are reduced with cytotoxic chemotherapy. There are limited data on the effect of immune checkpoint inhibitor (ICI) myocarditis on GCS and GRS.
OBJECTIVES This study aimed to detail the role of GCS and GRS in ICI myocarditis.
METHODS In this retrospective study, GCS and GRS from 75 cases of patients with ICI myocarditis and 50 ICI-treated
patients without myocarditis (controls) were compared. Pre-ICI GCS and GRS were available for 12 cases and 50 controls.
Measurements were performed in a core laboratory blinded to group and time. Major adverse cardiovascular events
(MACEs) were defined as a composite of cardiogenic shock, cardiac arrest, complete heart block, and cardiac death.
RESULTS Cases and controls were similar in age (66 15 years vs 63 12 years; P Œ 0.20), sex (male: 73% vs 61%; P Œ
0.20) and cancer type (P Œ 0.08). Pre-ICI GCS and GRS were also similar (GCS: 22.6% 3.4% vs 23.5% 3.8%; P Œ
0.14; GRS: 45.5% 6.2% vs 43.6% 8.8%; P Œ 0.24). Overall, 56% (n Œ 42) of patients with myocarditis presented
with preserved left ventricular ejection fraction (LVEF). GCS and GRS were lower in myocarditis compared with on-ICI
controls (GCS: 17.5% 4.2% vs 23.6% 3.0%; P < 0.001; GRS: 28.6% 6.7% vs 47.0% 7.4%; P < 0.001). Over a
median follow-up of 30 days, 28 cardiovascular events occurred. A GCS (HR: 4.9 [95% CI: 1.6-15.0]; P Œ 0.005) and GRS
(HR: 3.9 [95% CI: 1.4-10.8]; P Œ 0.008) below the median was associated with an increased event rate. In receiveroperating characteristic (ROC) curves, GCS (AUC: 0.80 [95% CI: 0.70-0.91]) and GRS (AUC: 0.76 [95% CI: 0.64-0.88])
showed better performance than cardiac troponin T (cTnT) (AUC: 0.70 [95% CI: 0.58-0.82]), LVEF (AUC: 0.69 [95% CI:
0.56-0.81]), and age (AUC: 0.54 [95% CI: 0.40-0.68]). Net reclassification index and integrated discrimination
improvement demonstrated incremental prognostic utility of GRS over LVEF (P Œ 0.04) and GCS over cTnT (P Œ 0.002).
CONCLUSIONS GCS and GRS are lower in ICI myocarditis, and the magnitude of reduction has prognostic significance.
(J Am Coll Cardiol Img 2022;15:1883â1896) © 2022 the American College of Cardiology Foundation. Published by
Elsevier. All rights reserved
Myocardial T1 and T2 mapping by magnetic resonance in patients with immune checkpoint inhibitorâassociated myocarditis
BACKGROUND Myocarditis is a potentially fatal complication of immune checkpoint inhibitor (ICI) therapy. Data on the
utility of cardiovascular magnetic resonance (CMR) T1 and T2 mapping in ICI myocarditis are limited.
OBJECTIVES This study sought to assess the value of CMR T1 and T2 mapping in patients with ICI myocarditis.
METHODS In this retrospective study from an international registry of patients with ICI myocarditis, clinical and CMR
findings (including T1 and T2 maps) were collected. Abnormal T1 and T2 were defined as 2 SD above site (vendor/field
strength specific) reference values and a z-score was calculated for each patient. Major adverse cardiovascular events
(MACE) were a composite of cardiovascular death, cardiogenic shock, cardiac arrest, and complete heart block.
RESULTS Of 136 patients with ICI myocarditis with a CMR, 86 (63%) had T1 maps and 79 (58%) also had T2 maps.
Among the 86 patients (66.3 13.1 years of age), 36 (41.9%) had a left ventricular ejection fraction <55%. Across all
patients, mean z-scores for T1 and T2 values were 2.9 1.9 (p < 0.001) and 2.2 2.1 (p < 0.001), respectively. On
Siemens 1.5-T scanner (n Œ 67), native T1 (1,079.0 55.5 ms vs. 1,000.3 22.1 ms; p < 0.001) and T2 (56.2 4.9 ms vs.
49.8 2.2 ms; p < 0.001) values were elevated compared with reference values. Abnormal T1 and T2 values were seen in
78% and 43% of the patients, respectively. Applying the modified Lake Louise Criteria, 95% met the nonischemic
myocardial injury criteria and 53% met the myocardial edema criteria. Native T1 values had excellent discriminatory value
for subsequent MACE, with an area under the curve of 0.91 (95% confidence interval: 0.84 to 0.98). Native T1 values (for
every 1-unit increase in z-score, hazard ratio: 1.44; 95% confidence interval: 1.12 to 1.84; p Œ 0.004) but not T2 values
were independently associated with subsequent MACE.
CONCLUSIONS The use of T1 mapping and application of the modified Lake Louise Criteria provides important diagnostic value, and T1 mapping provides prognostic value in patients with ICI myocarditis.
(J Am Coll Cardiol 2021;77:1503â16) © 2021 by the American College of Cardiology Foundation
Whole-exome sequencing identifies rare and low-frequency coding variants associated with LDL cholesterol
Elevated low-density lipoprotein cholesterol (LDL-C) is a treatable, heritable risk factor for cardiovascular disease. Genome-wide association studies (GWASs) have identified 157 variants associated with lipid levels but are not well suited to assess the impact of rare and low-frequency variants. To determine whether rare or low-frequency coding variants are associated with LDL-C, we exome sequenced 2,005 individuals, including 554 individuals selected for extreme LDL-C (>98th or <2nd percentile). Follow-up analyses included sequencing of 1,302 additional individuals and genotype-based analysis of 52,221 individuals. We observed significant evidence of association between LDL-C and the burden of rare or low-frequency variants in PNPLA5, encoding a phospholipase-domain-containing protein, and both known and previous
Search for intermediate-mass black hole binaries in the third observing run of Advanced LIGO and Advanced Virgo
International audienceIntermediate-mass black holes (IMBHs) span the approximate mass range 100â105âMâ, between black holes (BHs) that formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mass âŒ150âMâ providing direct evidence of IMBH formation. Here, we report on a dedicated search of O3 data for further IMBH binary mergers, combining both modeled (matched filter) and model-independent search methods. We find some marginal candidates, but none are sufficiently significant to indicate detection of further IMBH mergers. We quantify the sensitivity of the individual search methods and of the combined search using a suite of IMBH binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. Our most stringent limit is for equal mass and aligned spin BH binary of total mass 200âMâ and effective aligned spin 0.8 at 0.056 Gpcâ3 yrâ1 (90% confidence), a factor of 3.5 more constraining than previous LIGO-Virgo limits. We also update the estimated rate of mergers similar to GW190521 to 0.08 Gpcâ3 yrâ1.Key words: gravitational waves / stars: black holes / black hole physicsCorresponding author: W. Del Pozzo, e-mail: [email protected]â Deceased, August 2020