2,093 research outputs found
REDBACK: Open-source software for efficient noise-reduction in plate kinematic reconstructions
Knowledge of past plate motions derived from ocean-floor finite rotations is an important asset of the Earth Sciences, because it allows linking a variety of shallow-rooted and deep-rooted geological processes. Efforts have recently been taken toward inferring finite rotations at the unprecedented temporal resolution of 1 Myr or less, and more data are anticipated in the near future. These reconstructions, like any data set, feature a degree of noise that compromises significantly our ability to make geodynamical inferences. Bayesian Inference has been recently shown to be effective in reducing the impact of noise on plate kinematics inferred from high-temporal-resolution finite-rotation data sets. We describe REDBACK, an open-source software that implements transdimensional hierarchical Bayesian Inference for efficient noise-reduction in plate kinematic reconstructions. Algorithm details are described and illustrated by means of a synthetic test
Global P wave tomography of Earth's lowermost mantle from partition modeling
Determining the scale-length, magnitude, and distribution of heterogeneity in the lowermost mantle is crucial to understanding whole mantle dynamics, and yet it remains a much debated and ongoing challenge in geophysics. Common shortcomings of current se
Reply to the discussion by Charollais et al. on “Reconciling strontium-isotope and K–Ar ages with biostratigraphy: the case of the Urgonian platform, Early Cretaceous of the Jura mountains, Western Switzerland” by Godet et al. (2011), Swiss Journal of Geosciences, 104, 147–160
Benchmarking computer platforms for lattice QCD applications
We define a benchmark suite for lattice QCD and report on benchmark results
from several computer platforms. The platforms considered are apeNEXT, CRAY
T3E, Hitachi SR8000, IBM p690, PC-Clusters, and QCDOC.Comment: 3 pages, Lattice03, machines and algorithm
Low Frequency Tilt Seismology with a Precision Ground Rotation Sensor
We describe measurements of the rotational component of teleseismic surface
waves using an inertial high-precision ground-rotation-sensor installed at the
LIGO Hanford Observatory (LHO). The sensor has a noise floor of 0.4 nrad at 50 mHz and a translational coupling of less than 1 rad/m
enabling translation-free measurement of small rotations. We present
observations of the rotational motion from Rayleigh waves of six teleseismic
events from varied locations and with magnitudes ranging from M6.7 to M7.9.
These events were used to estimate phase dispersion curves which shows
agreement with a similar analysis done with an array of three STS-2
seismometers also located at LHO
Application of redox sensitive proxies and carbonate clumped isotopes to Mesozoic and Palaeozoic radiaxial fibrous calcite cements
Upper crustal structure of central Java, Indonesia, from transdimensional seismic ambient noise tomography
Delineating the crustal structure of central Java is crucial for understanding its complex tectonic setting. However, seismic imaging of the strong heterogeneity typical of such a tectonically active region can be challenging, particularly in the upper crust where velocity contrasts are strongest and steep bodywave ray paths provide poor resolution. To overcome these difficulties, we apply the technique of ambient noise tomography (ANT) to data collected during the Merapi Amphibious Experiment (MERAMEX), which covered central Java with a temporary deployment of over 120 seismometers during 2004 May-October. More than 5000 Rayleigh wave Green's functions were extracted by cross-correlating the noise simultaneously recorded at available station pairs. We applied a fully non-linear 2-D Bayesian probabilistic inversion technique to the retrieved traveltimes. Features in the derived tomographic images correlate well with previous studies, and some shallow structures that were not evident in previous studies are clearly imaged with ANT. The Kendeng Basin and several active volcanoes appear with very low group velocities, and anomalies with relatively high velocities can be interpreted in terms of crustal sutures and/or surface geological features
Hardware and software status of QCDOC
QCDOC is a massively parallel supercomputer whose processing nodes are based
on an application-specific integrated circuit (ASIC). This ASIC was
custom-designed so that crucial lattice QCD kernels achieve an overall
sustained performance of 50% on machines with several 10,000 nodes. This strong
scalability, together with low power consumption and a price/performance ratio
of $1 per sustained MFlops, enable QCDOC to attack the most demanding lattice
QCD problems. The first ASICs became available in June of 2003, and the testing
performed so far has shown all systems functioning according to specification.
We review the hardware and software status of QCDOC and present performance
figures obtained in real hardware as well as in simulation.Comment: Lattice2003(machine), 6 pages, 5 figure
Response to ''Comment on 'Enhanced Jc's of YBa2Cu3O7 - x-Ag ex situ annealed coevaporated films on LaAlO3 (100) substrates''' (Appl. Phys. Lett. 67, 3650 (1995))
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