9,194 research outputs found
Counterparty Risk Subject To ATE
Rating trigger ATE (Additional Termination Event) is a counterparty risk mitigant that allows banks to terminate and close out bilateral derivative contracts if the credit rating of the counterparty falls below the trigger level. Since credit default is often preceded by rating downgrades, ATE clause effectively reduces the counterparty credit risk by early termination of exposure. However, there is still the risk that counterparty may default without going through severe downgrade. This article presents a practical model for valuating CVA in the presence of ATE.Counterparty Risk, Credit Valuation Adjustment, Rating Transition, Rating Trigger, Additional Termination Event
An updated catalog of M31 globular-like clusters: UBVRI photometry, ages, and masses
We present an updated UBVRI photometric catalog containing 970 objects in the
field of M31, selected from the Revised Bologna Catalog (RBC v.4.0), including
965, 967, 965, 953, and 827 sources in the individual UBVRI bands,
respectively, of which 205, 123, 14, 126, and 109 objects do not have
previously published photometry. Photometry is performed using archival images
from the Local Group Galaxies Survey, which covers 2.2 deg^2 along the major
axis of M31. We focus on 445 confirmed `globular-like' clusters and candidates,
comprising typical globular and young massive clusters. The ages and masses of
these objects are derived by comparison of their observed spectral-energy
distributions with simple stellar population synthesis. Approximately half of
the clusters are younger than 2 Gyr, suggesting that there has been significant
recent active star formation in M31, which is consistent with previous results.
We note that clusters in the halo (r_ projected>30kpc) are composed of two
different components, older clusters with ages >10 Gyr and younger clusters
with ages around 1 Gyr. The spatial distributions show that the young clusters
(<2 Gyr) are spatially coincident with the galaxy's disk, including the `10 kpc
ring,' the `outer ring,' and the halo of M31, while the old clusters (> 2 Gyr)
are spatially correlated with the bulge and halo. We also estimate the masses
of the 445 confirmed clusters and candidates in M31 and find that our estimates
agree well with previously published values. We find that none of the young
disk clusters can survive the inevitable encounters with giant molecular clouds
in the galaxy's disk and that they will eventually disrupt on timescales of a
few Gyr. Specifically, young disk clusters with a mass of 10^4 M_\odot are
expected to dissolve within 3.0 Gyr and will, thus, not evolve to become
globular clusters.Comment: 35 pages, 20 figures and 5 tables, accepted for publication in Ap
Star clusters in M33: updated UBVRI photometry, ages, metallicities, and masses
The photometric characterization of M33 star clusters is far from complete.
In this paper, we present homogeneous photometry of 708 star clusters
and cluster candidates in M33 based on archival images from the Local Group
Galaxies Survey, which covers 0.8 deg along the galaxy's major axis. Our
photometry includes 387, 563, 616, 580, and 478 objects in the bands,
respectively, of which 276, 405, 430, 457, and 363 do not have previously
published photometry. Our photometry is consistent with previous
measurements (where available) in all filters. We adopted Sloan Digital Sky
Survey photometry for complementary purposes, as well as Two Micron
All-Sky Survey near-infrared photometry where available. We fitted the
spectral-energy distributions of 671 star clusters and candidates to derive
their ages, metallicities, and masses based on the updated {\sc parsec} simple
stellar populations synthesis models. The results of our minimization
routines show that only 205 of the 671 clusters () are older than 2 Gyr,
which represents a much smaller fraction of the cluster population than that in
M31 (), suggesting that M33 is dominated by young star clusters (
Gyr). We investigate the mass distributions of the star clusters---both open
and globular clusters---in M33, M31, the Milky Way, and the Large Magellanic
Cloud. Their mean values are , 5.43, 2.72, and
4.18, respectively. The fraction of open to globular clusters is highest in the
Milky Way and lowest in M31. Our comparisons of the cluster ages, masses, and
metallicities show that our results are basically in agreement with previous
studies (where objects in common are available); differences can be traced back
to differences in the models adopted, the fitting methods used, and stochastic
sampling effects.Comment: 32 pages, 12 figures, 2 tables, accepted for publication in ApJ
Improving End-to-End Speech Recognition with Policy Learning
Connectionist temporal classification (CTC) is widely used for maximum
likelihood learning in end-to-end speech recognition models. However, there is
usually a disparity between the negative maximum likelihood and the performance
metric used in speech recognition, e.g., word error rate (WER). This results in
a mismatch between the objective function and metric during training. We show
that the above problem can be mitigated by jointly training with maximum
likelihood and policy gradient. In particular, with policy learning we are able
to directly optimize on the (otherwise non-differentiable) performance metric.
We show that joint training improves relative performance by 4% to 13% for our
end-to-end model as compared to the same model learned through maximum
likelihood. The model achieves 5.53% WER on Wall Street Journal dataset, and
5.42% and 14.70% on Librispeech test-clean and test-other set, respectively
Valuing the health impacts from particulate air pollution in Tianjin
Although China has made dramatic economic progress in recent years, air pollution continues to be the most visible environmental problem and imposes significant health and economic costs on society. Using data on pollutant concentration and population for 2003, this paper estimates the economic costs of health related effects due to particulate air pollution in urban areas of Tianjin, China. Exposure-response functions are used to quantify the impact on human health. Value of a statistical life and benefit transfer are used to obtain the unit value of some health effects. Our results show significant health costs associated with air pollution in Tianjin. The total economic cost is estimated to be US$1.1 billion, about 3.7% of Tianjin’s GDP in 2003. The findings underscore the importance of urban air pollution control. Finally, the policy implications for alternative energy options and climate policies are given.particulate air pollution, PM10, economic valuation, Tianjin
Water Use in China’s Domestic, Industrial and Agricultural Sectors: An Empirical Analysis
Demand management plays an increasingly important role in dealing with water scarcity in China. It is important to understand the level and pattern of water use in various sectors across the regions for any measures being put into effect. The aim of this study is to enhance the understanding of the factors that influence water demand by examining closely the water use in domestic, industrial and agricultural sectors. Using province level panel data from 1997 to 2003, the examination shows that the regional disparity in the level and pattern of water uses is considerable. The estimation of water demand shows that both economic and climatic variables have significant effects on water demand. The results suggest an income elasticity of 0.42 for the domestic sector, an output elasticity of -0.32 for industrial water use (per unit of output), and an output elasticity of –0.24 for irrigated agriculture (per land area).water use, regional variation, elasticity, demand management
A critical look at power law modelling of the Internet
This paper takes a critical look at the usefulness of power law models of the
Internet. The twin focuses of the paper are Internet traffic and topology
generation. The aim of the paper is twofold. Firstly it summarises the state of
the art in power law modelling particularly giving attention to existing open
research questions. Secondly it provides insight into the failings of such
models and where progress needs to be made for power law research to feed
through to actual improvements in network performance.Comment: To appear Computer Communication
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