2,428 research outputs found
Trace-element geochemistry of mantle olivine and application to mantle petrogenesis and geothermobarometry
Probabilities of Large Earthquakes in the San Francisco Bay Region, California
In 1987 a Working Group on California Earthquake Probabilities was organized by the U.S. Geological
Survey at the recommendation of the National Earthquake Prediction Evaluation Council (NEPEC). The
membership included representatives from private industry, academia, and the U.S. Geological Survey. The
Working Group computed long-term probabilities of earthquakes along the major faults of the San Andreas
fault system on the basis of consensus interpretations of information then available. Faults considered by the
Working Group included the San Andreas fault proper, the San Jacinto and Imperial-faults of southern
California, and the Hayward fault of northern California. The Working Group issued a final report of its
findings in 1988 (Working Group, 1988) that was reviewed and endorsed by NEPEC.
As a consequence of the magnitude 7.1 Loma Prieta, California, earthquake of October 17, 1989, a
second Working Group on California Earthquake Probabilities was organized under the auspices of NEPEC.
Its charge was to review and, as necessary, revise the findings of the 1988 report on the probability of large
earthquakes in the San Francisco Bay region. In particular, the Working Group was requested to examine the
probabilities of large earthquakes in the context of new interpretations or physical changes resulting from the
Loma Prieta earthquake. In addition, it was to consider new information pertaining to the San Andreas and other
faults in the region obtained subsequent to the release of the 1988 report. Insofar as modified techniques and
improved data have been used in this study, the same approach might also, of course, modify the probabilities
for southern California. This reevaluation has, however, been specifically limited to the San Francisco Bay
region.
This report is intended to summarize the collective knowledge and judgments of a diverse group of
earthquake scientists to assist in formulation of rational earthquake policies. A considerable body of information
about active faults in the San Francisco Bay region leads to the conclusion that major earthquakes are likely
within the next tens of years. Several techniques can be used to compute probabilities of future earthquakes,
although there are uncertainties about the validity of specific assumptions or models that must be made when
applying these techniques. The body of this report describes the data and detailed assumptions that lead to
specific probabilities for different fault segments. Additional data and future advances in our understanding of
earthquake physics may alter the way that these probabilities are estimated. Even though this uncertainty must
be acknowledged, we emphasize that the findings of this report are supported by other lines of argument and
are consistent with our best understanding of the likelihood for the occurrence of earthquakes in the San
Francisco Bay region
Pseudobulges in the Disk Galaxies NGC 7690 and NGC 4593
We present Ks-band surface photometry of NGC 7690 (Hubble type Sab) and NGC
4593 (SBb). We find that, in both galaxies, a major part of the "bulge" is as
flat as the disk and has approximately the same color as the inner disk. In
other words, the "bulges" of these galaxies have disk-like properties. We
conclude that these are examples of "pseudobulges" -- that is, products of
secular dynamical evolution. Nonaxisymmetries such as bars and oval disks
transport disk gas toward the center. There, star formation builds dense
stellar components that look like -- and often are mistaken for -- merger-built
bulges but that were constructed slowly out of disk material. These
pseudobulges can most easily be recognized when, as in the present galaxies,
they retain disk-like properties. NGC 7690 and NGC 4593 therefore contribute to
the growing evidence that secular processes help to shape galaxies.
NGC 4593 contains a nuclear ring of dust that is morphologically similar to
nuclear rings of star formation that are seen in many barred and oval galaxies.
The nuclear dust ring is connected to nearly radial dust lanes in the galaxy's
bar. Such dust lanes are a signature of gas inflow. We suggest that gas is
currently accumulating in the dust ring and hypothesize that the gas ring will
starburst in the future. The observations of NGC 4593 therefore suggest that
major starburst events that contribute to pseudobulge growth can be episodic.Comment: 10 pages, 3 Postscript figures; requires emulateapj.cls,
apjfonts.sty, and psfig.sty; accepted for publication in ApJ; for a version
with full resolution figures, see
http://chandra.as.utexas.edu/~kormendy/n7690.pd
Why have asset price properties changed so little in 200 years
We first review empirical evidence that asset prices have had episodes of
large fluctuations and been inefficient for at least 200 years. We briefly
review recent theoretical results as well as the neurological basis of trend
following and finally argue that these asset price properties can be attributed
to two fundamental mechanisms that have not changed for many centuries: an
innate preference for trend following and the collective tendency to exploit as
much as possible detectable price arbitrage, which leads to destabilizing
feedback loops.Comment: 16 pages, 4 figure
Future Seismic Hazards in Southern California - Phase I: Implications of the 1992 Landers Earthquake Sequence
Southern California and its seismologists received a wake-up call on June 28, 1992. The
largest earthquake to strike southern California in 40 years occurred near the town of Landers,
located 30 km north of the San Andreas fault. It had a magnitude of 7.5 (M7.5). Three and one-half
hours later, a M6.5 aftershock struck the Big Bear area 40 km (kilometers) to the west of
Landers. An ad hoc working group was rapidly convened in July, 1992, to evaluate how the
Landers-Big Bear earthquake sequence might affect future large earthquakes along major faults
in southern California. In particular, what are the chances of large earthquakes in the next few
years and how do they compare to previous estimates (such as those of the Working Group on
California Earthquake Probabilities -- WGCEP, 1988)? Such an evaluation was made for central
California after the Lorna Prieta earthquake of 1989 (WGCEP, 1990). The charge to the Landers
ad hoc working group included analyzing the seismicity for the last several years in southern
California and the new paleoseismic, geologic, and geodetic data recently available for southern
California. To inform the public about the potential hazard of plausible earthquakes, the working
group was also asked to map the predicted severity of ground shaking for such earthquakes
compared to that from the Landers earthquake
First-principles study of the inversion thermodynamics and electronic structure of FeM2X4 (thio)spinels (M = Cr, Mn, Co, Ni; X = O, S)
FeM2X4 spinels, where M is a transition metal and X is oxygen or sulfur, are candidate materials for spin filters, one of the key devices in spintronics. We present here a computational study of the inversion thermodynamics and the electronic structure of these (thio)spinels for M = Cr, Mn, Co, Ni, using calculations based on the density functional theory with on-site Hubbard corrections (DFT+U). The analysis of the configurational free energies shows that different behaviour is expected for the equilibrium cation distributions in these structures: FeCr2X4 and FeMn2S4 are fully normal, FeNi2X4 and FeCo2S4 are intermediate, and FeCo2O4 and FeMn2O4 are fully inverted. We have analyzed the role played by the size of the ions and by the crystal field stabilization effects in determining the equilibrium inversion degree. We also discuss how the electronic and magnetic structure of these spinels is modified by the degree of inversion, assuming that this could be varied from the equilibrium value. We have obtained electronic densities of states for the completely normal and completely inverse cation distribution of each compound. FeCr2X4, FeMn2X4, FeCo2O4 and FeNi2O4 are half-metals in the ferrimagnetic state when Fe is in tetrahedral positions. When M is filling the tetrahedral positions, the Cr-containing compounds and FeMn2O4 are half-metallic systems, while the Co and Ni spinels are insulators. The Co and Ni sulfide counterparts are metallic for any inversion degree together with the inverse FeMn2S4. Our calculations suggest that the spin filtering properties of the FeM2X4 (thio)spinels could be modified via the control of the cation distribution through variations in the synthesis conditions
Bayesian D-Optimal Choice Designs for Mixtures
__Abstract__
\n
\nConsumer products and services can often be described as mixtures of ingredients. Examples are the mixture of ingredients in a cocktail and the mixture of different components of waiting time (e.g., in-vehicle and out-of-vehicle travel time) in a transportation setting. Choice experiments may help to determine how the respondents\' choice of a product or service is affected by the combination of ingredients. In such studies, individuals are confronted with sets of hypothetical products or services and they are asked to choose the most preferred product or service from each set.
\n
\nHowever, there are no studies on the optimal design of choice experiments involving mixtures. We propose a method for generating an optimal design for such choice experiments. To this end, we first introduce mixture models in the choice context and next present an algorithm to construct optimal experimental designs, assuming the multinomial logit model is used to analyze the choice data. To overcome the problem that the optimal designs depend on the unknown parameter values, we adopt a Bayesian D-optimal design approach. We also consider locally D-optimal designs and compare the performance of the resulting designs to those produced by a utility-neutral (UN) approach in which designs are based on the assumption that individuals are indifferent between all choice alternatives. We demonstrate that our designs are quite different and in general perform better than the UN designs
Outcome of primary resurfacing hip replacement: evaluation of risk factors for early revision: 12,093 replacements from the Australian Joint Registry
BACKGROUND AND PURPOSE: The outcome of modern resurfacing remains to be determined. The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) started collection of data on hip resurfacing at a time when modern resurfacing was started in Australia. The rate of resurfacing has been higher in Australia than in many other countries. As a result, the AOANJRR has one of the largest series of resurfacing procedures. This study was undertaken to determine the results of this series and the risk factors associated with revision. PATIENTS AND METHODS: Data from the AOANJRR were used to analyze the survivorship of 12,093 primary resurfacing hip replacements reported to the Joint Replacement Registry between September 1999 and December 2008. This was compared to the results of primary conventional total hip replacement reported during the same period. The Kaplan-Meier method and proportional hazards models were used to determine risk factors such as age, sex, femoral component size, primary diagnosis, and implant design. RESULTS: Female patients had a higher revision rate than males; however, after adjusting for head size, the revision rates were similar. Prostheses with head sizes of less than 50 mm had a higher revision rate than those with head sizes of 50 mm or more. At 8 years, the cumulative per cent revision of hip resurfacing was 5.3 (4.6-6.2), as compared to 4.0 (3.8-4.2) for total hip replacement. However, in osteoarthritis patients aged less than 55 years with head sizes of 50 mm or more, the 7-year cumulative per cent revision for hip resurfacing was 3.0 (2.2-4.2). Also, hips with dysplasia and some implant designs had an increased risk of revision. INTERPRETATION: Risk factors for revision of resurfacing were older patients, smaller femoral head size, patients with developmental dysplasia, and certain implant designs. These results highlight the importance of patient and prosthesis selection in optimizing the outcome of hip resurfacing
Atomic Resonance and Scattering
Contains reports on six research projects.National Science Foundation (Grant PHY 83-06273)U.S. Navy - Office of Naval Research (Contract N00014-79-C-0183)Joint Services Electronics Program (Contract DAALO03-86-K-0002)National Science Foundation (Grant PHY 84-11483)National Science Foundation (Grant PHY 86-05893)National Science Foundation (Grant ECS 84-21392)U.S. Navy - Office of Naval Research (Contract N00014-83-K-0695)National Science Foundation (Grant CHE 84-21392
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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