562 research outputs found

    Megathrust Heterogeneity, Crustal Accretion, and a Topographic Embayment in the Western Nepal Himalaya : Insights From the Inversion of Thermochronological Data

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    Between 81 degrees 30MODIFIER LETTER PRIMEE and 83 degrees E, the Himalayan range's "perfect" arcuate shape is interrupted by an embayment. We hypothesize that thrust geometry and duplexing along the megathrust at midlower-crustal depths play a leading role in growth of the embayment as well the southern margin of the Tibetan plateau. To test this hypothesis, we conducted thermokinematic modeling of published thermochronologic data from the topographic and structural embayment in the western Nepal Himalaya to investigate the three-dimensional geometry and kinematics of the megathrust at midlower-crustal depths. Models that can best reproduce observed cooling ages suggest that the megathrust in the western Nepal Himalaya is best described as two ramps connected by a long flat that extends further north than in segments to the east and west. These models suggest that the high-slope zone along the embayment lies above the foreland limb of an antiformal crustal accretion zone on the megathrust with lateral and oblique ramps at midlower-crustal depths. The lateral and oblique ramps may have initiated by ca. 10 Ma. This process may have controlled along-strike variation in Himalayan-plateau growth and therefore development of the topographic embayment. Finally, we analyze geological and morphologic features and propose an evolution model in which landscape and drainage systems across the central-western Himalaya evolve in response to crustal accretion at depth and the three-dimensional geometry of the megathrust. Our work highlights the importance of crustal accretion at different depths in orogenic-wedge growth and that the midlower crustal accretion determines the location of plateau edge.Peer reviewe

    Measurement of Unpolarized and Polarized Cross Sections for Deeply Virtual Compton Scattering on the Proton at Jefferson Laboratory with CLAS

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    This paper reports the measurement of polarized and unpolarized cross sections for the ep → e \u27p\u27 γ reaction, which is composed of deeply virtual Compton scattering (DVCS) and Bethe-Heitler (BH) processes, at an electron beam energy of 5.88 GeV at the Thomas Jefferson National Accelerator Facility using the Large Acceptance Spectrometer CLAS. The unpolarized cross sections and polarized cross section differences have been measured over broad kinematics, 0.10 2 \u3c 4.8 GeV2,and 0.09 \u3c −t\u3c 2.00 GeV2. The results are found to be consistent with previous CLAS data, and these new data are discussed in the framework of the generalized parton distribution approach. Calculations with two widely used phenomenological models are approximately compatible with the experimental results over a large portion of the kinematic range of the data

    Psychological Functioning in Pediatric Patients with Single Ventricle Congenital Heart Disease: A Meta-Analysis and Systematic Review Protocol

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    Mental health is an important yet understudied area of care for patients with congenital heart disease. Through limited studies, it is known that children and adults with congenital heart disease have increased incidence of mental health disorders when compared to their peers [1-3]. Some studies estimate that over half of adult patients with congenital heart disease have significant symptoms of a mood or anxiety disorder [3], although it is very likely that these symptoms are underrecognized. It is also known that in adults with congenital heart disease, depression is responsible for the variability of self-reported health status of patients, including physical functioning [4]. A prior review and meta-analysis of patient with complex congenital heart disease showed an increased risk of internalizing and externalizing behavior problems, however this review was not specific to the single ventricle population [5]. A recent review and meta-analysis of patients with children and adults with single ventricle physiology found worse health-related quality of life outcomes in this population [6], however currently less is known about psychological functioning specifically in the pediatric single ventricle population. The aim of this systematic review is to summarize and meta-analyze the existing literature of psychological outcomes in pediatric single ventricle patients. It is hypothesized that pediatric patients with single ventricle heart disease will have an increased risk of internalizing and externalizing problems as compared to their peers.No funding associated with this projecthttp://deepblue.lib.umich.edu/bitstream/2027.42/167623/3/SVSysRevProposal2021.pdfDescription of SVSysRevProposal2021.pdf : This is a protocol for an evidence sythesis project on Psychological Functioning in Pediatric Patients with Single Ventricle Congenital Heart DiseaseSEL

    A comparison of forward and backward pp pair knockout in 3He(e,e'pp)n

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    Measuring nucleon-nucleon Short Range Correlations (SRC) has been a goal of the nuclear physics community for many years. They are an important part of the nuclear wavefunction, accounting for almost all of the high-momentum strength. They are closely related to the EMC effect. While their overall probability has been measured, measuring their momentum distributions is more difficult. In order to determine the best configuration for studying SRC momentum distributions, we measured the 3^3He(e,eâ€Čpp)n(e,e'pp)n reaction, looking at events with high momentum protons (pp>0.35p_p > 0.35 GeV/c) and a low momentum neutron (pn<0.2p_n< 0.2 GeV/c). We examined two angular configurations: either both protons emitted forward or one proton emitted forward and one backward (with respect to the momentum transfer, q⃗\vec q). The measured relative momentum distribution of the events with one forward and one backward proton was much closer to the calculated initial-state pppp relative momentum distribution, indicating that this is the preferred configuration for measuring SRC.Comment: 8 pages, 9 figures, submitted to Phys Rev C. Version 2 incorporates minor corrections in response to referee comment

    Boosted three-dimensional black-hole evolutions with singularity excision

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    Binary black hole interactions provide potentially the strongest source of gravitational radiation for detectors currently under development. We present some results from the Binary Black Hole Grand Challenge Alliance three- dimensional Cauchy evolution module. These constitute essential steps towards modeling such interactions and predicting gravitational radiation waveforms. We report on single black hole evolutions and the first successful demonstration of a black hole moving freely through a three-dimensional computational grid via a Cauchy evolution: a hole moving ~6M at 0.1c during a total evolution of duration ~60M

    Bond-disordered spin systems: Theory and application to doped high-Tc compounds

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    We examine the stability of magnetic order in a classical Heisenberg model with quenched random exchange couplings. This system represents the spin degrees of freedom in high-TcT_\textrm{c} compounds with immobile dopants. Starting from a replica representation of the nonlinear σ\sigma-model, we perform a renormalization-group analysis. The importance of cumulants of the disorder distribution to arbitrarily high orders necessitates a functional renormalization scheme. From the renormalization flow equations we determine the magnetic correlation length numerically as a function of the impurity concentration and of temperature. From our analysis follows that two-dimensional layers can be magnetically ordered for arbitrarily strong but sufficiently diluted defects. We further consider the dimensional crossover in a stack of weakly coupled layers. The resulting phase diagram is compared with experimental data for La2−x_{2-x}Srx_xCuO4_4.Comment: 12 pages, 5 figure

    Measurement of Exclusive π0\pi^0 Electroproduction Structure Functions and their Relationship to Transversity GPDs

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    Exclusive π0\pi^0 electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q2Q^2, xBx_B, tt, and ϕπ\phi_\pi, in the Q2Q^2 range from 1.0 to 4.6 GeV2^2,\ −t-t up to 2 GeV2^2, and xBx_B from 0.1 to 0.58. Structure functions σT+ϔσL,σTT\sigma_T +\epsilon \sigma_L, \sigma_{TT} and σLT\sigma_{LT} were extracted as functions of tt for each of 17 combinations of Q2Q^2 and xBx_B. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates σT+ϔσL\sigma_T +\epsilon \sigma_L and fails to account for σTT\sigma_{TT} and σLT\sigma_{LT}, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm that exclusive π0\pi^0 electroproduction offers direct experimental access to the transversity GPDs.Comment: 6 pages, 2 figure
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