5,538 research outputs found
On the Approximation of Functionals of Very Large Hermitian Matrices represented as Matrix Product Operators
Survey of finance companies, 1996
Finance companies are major suppliers of credit to consumers and businesses. The sector is made up of roughly 1,250 nondepository financial institutions, with 20 firms accounting for three-fourths of the receivables. The Federal Reserve System has been surveying the assets and liabilities of finance companies, typically at five-year intervals, since June 1955. This article summarizes the results of the 1996 survey. Special features of that survey are a breakdown of automobile leases into consumer and business components and, relative to previous surveys, greater detail on the composition of real estate credit and more information on securitized loans and leases.Finance companies
Return period curves for extreme 5-min rainfall amounts at the Barcelona urban network
Heavy rainfall episodes are relatively common in the conurbation of Barcelona and neighbouring cities (NE Spain), usually due to storms generated by convective phenomena in summer and eastern and south-eastern advections in autumn. Prevention of local flood episodes and right design of urban drainage have to take into account the rainfall intensity spread instead of a simple evaluation of daily rainfall amounts. The database comes from 5-min rain amounts recorded by tipping buckets in the Barcelona urban network along the years 1994–2009. From these data, extreme 5-min rain amounts are selected applying the peaks-over-threshold method for thresholds derived from both 95% percentile and the mean excess plot. The return period curves are derived from their statistical distribution for every gauge, describing with detail expected extreme 5-min rain amounts across the urban network. These curves are compared with those derived from annual extreme time series. In this way, areas in Barcelona submitted to different levels of flood risk from the point of view of rainfall intensity are detected. Additionally, global time trends on extreme 5-min rain amounts are quantified for the whole network and found as not statistically significant.Peer ReviewedPostprint (author's final draft
The nature of the dense core population in the pipe nebula: core and cloud kinematics from C18O observations
We present molecular-line observations of 94 dark cloud cores identified in
the Pipe nebula through near-IR extinction mapping. Using the Arizona Radio
Observatory 12m telescope, we obtained spectra of these cores in the J=1-0
transition of C18O. We use the measured core parameters, i.e., antenna
temperature, linewidth, radial velocity, radius and mass, to explore the
internal kinematics of these cores as well as their radial motions through the
larger molecular cloud. We find that the vast majority of the dark extinction
cores are true cloud cores rather than the superposition of unrelated
filaments. While we identify no significant correlations between the core's
internal gas motions and the cores' other physical parameters, we identify
spatially correlated radial velocity variations that outline two main kinematic
components of the cloud. The largest is a 15pc long filament that is
surprisingly narrow both in spatial dimensions and in radial velocity.
Beginning in the Stem of the Pipe, this filament displays uniformly small C18O
linewidths (dv~0.4kms-1) as well as core to core motions only slightly in
excess of the gas sound speed. The second component outlines what appears to be
part of a large (2pc; 1000 solar mass) ring-like structure. Cores associated
with this component display both larger linewidths and core to core motions
than in the main cloud. The Pipe Molecular Ring may represent a primordial
structure related to the formation of this cloud.Comment: Accepted to ApJ. 14 pages, 11 figures. Complete table at end of
documen
A High Throughput Workflow Environment for Cosmological Simulations
The next generation of wide-area sky surveys offer the power to place
extremely precise constraints on cosmological parameters and to test the source
of cosmic acceleration. These observational programs will employ multiple
techniques based on a variety of statistical signatures of galaxies and
large-scale structure. These techniques have sources of systematic error that
need to be understood at the percent-level in order to fully leverage the power
of next-generation catalogs. Simulations of large-scale structure provide the
means to characterize these uncertainties. We are using XSEDE resources to
produce multiple synthetic sky surveys of galaxies and large-scale structure in
support of science analysis for the Dark Energy Survey. In order to scale up
our production to the level of fifty 10^10-particle simulations, we are working
to embed production control within the Apache Airavata workflow environment. We
explain our methods and report how the workflow has reduced production time by
40% compared to manual management.Comment: 8 pages, 5 figures. V2 corrects an error in figure
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