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Nonequilibrium detonation of composite explosives
The effect of nonequilibrium diffusional flow on detonation velocities in composite explosives is examined. Detonation conditions are derived for complete equilibrium, temperature and pressure equilibrium, and two forms of pressure equilibrium. Partial equilibria are associated with systems which have not had sufficient time for transport to smooth out the gradients between spatially separate regions. The nonequilibrium detonation conditions are implemented in the CHEQ equation of state code. We show that the detonation velocity decreases as the non-chemical degrees of freedom of the explosive are allowed to equilibrate. It is only when the chemical degrees of freedom are allowed to equilibrate that the detonation velocity increases
Are metabolic equivalents (METS) an accurate method for estimating change in peak oxygen consumption after cardiac rehabilitation?
Background: Maximal cardiopulmonary exercise testing (CPET) is the âgold standardâ method of determining Vo2peak. When CPET is unavailable, VO2peak and metabolic equivalents (METs) are estimated from treadmill or cycle ergometer workloads. UK cardiac rehabilitation programmes (CR) use estimated METs to report changes in cardiorespiratory fitness (CRF). However, the accuracy of determining changes in VO2peak based on changes in estimated METs is not known. Methods: 27 patients with coronary heart disease (88.9% male; age 59.5 ± 10.0 years, body mass index 29.6 ± 3.8 kg.m-2) performed maximal CPET before and after an exercise based CR intervention. VO2peak was directly determined using ventilatory gas exchange data and was also estimated using the American College of Sports Medicine (ACSM) leg cycling equation for METs. Agreement between changes in directly determined VO2peak and VO2peak estimated from METs was tested using Bland-Altman limits of agreement (LoA), and intraclass correlation coefficients. Results: Directly determined VO2peak did not increase significantly following CR (0.5 ml.kg-1.min-1 (2.7%); p=0.332). In contrast, estimated VO2peak increased significantly (0.4 METs; 1.4 ml.kg-1.min-1; 6.7%; p=0.006). The mean bias for estimated VO2peak versus directly-determined VO2peak was 0.7 ml.kg-1.min-1 (LoA -4.7 to 5.9 ml.kg-1.min-1). Aerobic efficiency, (ÎVO2/ÎWR slope) was significantly associated with estimated VO2peak measurement error. Conclusion: Changes in estimated VO2peak determined using the ACSM equation for leg cycling are not accurate surrogates for directly determined changes in VO2peak. Reporting mean CRF changes using estimated METs may over-estimate the efficacy of CR and lead to a different interpretation of study findings compared to directly determined VO2peak
Routine exercise-based cardiac rehabilitation does not increase aerobic fitness: A CARE CR study
Background
Recent evidence suggests that routine exercise-based cardiac rehabilitation (CR) may not lead to a substantial increase in estimated peak oxygen uptake (VÌO2peak). This could reduce the potential benefits of CR and explain why CR no longer improves patient survival in recent studies. We aimed to determine whether routine exercise-based CR increases VÌO2peak using gold-standard maximal cardiopulmonary exercise testing (CPET), and to quantify the exercise training stimulus which might be insufficient in patients undertaking CR.
Methods
We studied the effects of a routine, twice weekly, exercise-based CR programme for eight weeks (intervention group) compared with abstention from supervised exercise training (control group) in patients with coronary heart disease. The primary outcome was VÌO2peak measured using CPET. We also measured changes in body composition using dual X-ray absorptiometry, carotid intima-media thickness, hs-CRP and N-terminal pro B-type natriuretic peptide at baseline, 10âŻweeks and one year. We also calculated the Calibre 5-year all-cause mortality risk score.
Results
Seventy patients (age 63.1 SD10.0âŻyears; BMI 29.2 SD4.0âŻkg·mâ2; 86% male) were recruited (nâŻ=âŻ48 intervention; nâŻ=âŻ22 controls). The mean aerobic exercise training duration was 23âŻmin per training session, and the mean exercise training intensity was 45.9% of heart rate reserve. VÌO2peak was 23·3âŻml·kg-1·minâ1 at baseline, and there were no changes in VÌO2peak between groups at any time point. The intervention had no effect on any of the secondary endpoints.
Conclusion
Routine CR does not lead to an increase in VÌO2peak and is unlikely to improve long-term outcomes
Fluvial geomorphic elements in modern sedimentary basins and their potential preservation in the rock record : A review
We appreciate very helpful reviews by Dr. Martin Stokes and three anonymous reviewers and editor Dr. Richard Marston. We also appreciate the encouragement for writing this paper from Dr. Timothy Horscroft. We acknowledge support of the sponsors of the Fluvial Systems Research Group consortium, BP, BG, Chevron, ConocoPhillips and Total.Peer reviewedPostprin
Corrigendum to Routine exercise-based cardiac rehabilitation does not increase aerobic fitness: A CARE CR study, International Journal of Cardiology, 305 (2020) 25â34
The authors regret that citation [39] was incorrectly referenced. Reference [39] should read:
The authors would like to apologise for any inconvenience caused.
DOI of original article: doi:https://doi.org/10.1016/j.ijcard.2020.01.04
Novel genetic loci associated with hippocampal volume
The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness
Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)
[no abstract available
Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background
The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58Ă10-8, Ω0V<6.35Ă10-8, and Ω0S<1.08Ă10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society
Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model
We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47Ă10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society
Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b
We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society
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