8,525 research outputs found
A General Equilibrium Model of Sovereign Default and Business Cycles
Emerging markets business cycle models treat default risk as part of an exogenous interest rate on working capital, while sovereign default models treat income fluctuations as an exogenous endowment process with ad-hoc default costs. We propose instead a general equilibrium model of both sovereign default and business cycles. In the model, some imported inputs require working capital financing; default triggers an efficiency loss as these inputs are replaced by imperfect substitutes; and default on public and private obligations occurs simultaneously. The model explains several features of cyclical dynamics around defaults, countercyclical spreads, high debt ratios, and key business cycle moments.
A Solution to the Disconnect between Country Risk and Business Cycle Theories
We propose a model that solves the crucial disconnect between business cycle models that treat default risk as an exogenous interest rate on working capital, and sovereign default models that treat output fluctuations as an exogenous process with ad-hoc default costs. The model explains observed output dynamics around defaults, countercyclical spreads, high debt ratios, and key business cycle moments. Three features of the model are central for these results: working capital loans pay for imported inputs; default triggers an efficiency loss as imported inputs are replaced by imperfect domestic substitutes; and default on public and private foreign obligations occurs simultaneously.
Design and performance analysis of network code division multiplexing for wireless sensor networks
© 2015 IEEE. In this paper, we investigate the performance of a wireless sensor network, in which multiple groups of source nodes communicate with their respective destination nodes with the help of a common relay network. A network code division multiplexing (NCDM) scheme is proposed to remove the inter-session interference among multiple transmission sessions at each destination. We focus on analyzing the soft processing algorithm of the NCDM scheme. Based on the analysis results, a new code design criteria for the construction of the generator matrix is proposed. Simulation results show that by following the proposed code design criteria, the bit error ratio (BER) performance gap between the scheme we studied and the serial session scheme can be managed effectively. In serial session scheme, source nodes in a number of groups communicate with their respective destinations in a time division manner
An enhanced convolutional neural network model for answer selection
© 2017 International World Wide Web Conference Committee (IW3C2), published under Creative Commons CC BY 4.0 License. Answer selection is an important task in question answering (QA) from the Web. To address the intrinsic difficulty in encoding sentences with semantic meanings, we introduce a general framework, i.e., Lexical Semantic Feature based Skip Convolution Neural Network (LSF-SCNN), with several optimization strategies. The intuitive idea is that the granular representations with more semantic features of sentences are deliberately designed and estimated to capture the similarity between question-answer pairwise sentences. The experimental results demonstrate the effectiveness of the proposed strategies and our model outperforms the state-of-the-art ones by up to 3.5% on the metrics of MAP and MRR
Production and decay of the neutral top-pion in high energy colliders
We study the production and decay of the neutral top-pion
predicted by topcolor-assisted technicolor(TC2) theory. Our results show that,
except the dominant decay modes , and , the
can also decay into and modes. It can
be significantly produced at high energy collider(LC) experiments
via the processes and . We further calculate the production cross sections of the
processes and . We find that the signatures of the neutral top-pion
can be detected via these processes.Comment: Latex file, 13 Pages, 6 eps figures. to be published in Phys.Rev.
Nanometric holograms based on a topological insulator material
Holography has extremely extensive applications in conventional optical instruments spanning optical microscopy and imaging, three-dimensional displays and metrology. To integrate holography with modern low-dimensional electronic devices, holograms need to be thinned to a nanometric scale. However, to keep a pronounced phase shift modulation, the thickness of holograms has been generally limited to the optical wavelength scale, which hinders their integration with ultrathin electronic devices. Here, we break this limit and achieve 60 nm holograms using a topological insulator material. We discover that nanometric topological insulator thin films act as an intrinsic optical resonant cavity due to the unequal refractive indices in their metallic surfaces and bulk. The resonant cavity leads to enhancement of phase shifts and thus the holographic imaging. Our work paves a way towards integrating holography with flat electronic devices for optical imaging, data storage and information security
Ultrathin MgB2 films fabricated on Al2O3 substrate by hybrid physical-chemical vapor deposition with high Tc and Jc
Ultrathin MgB2 superconducting films with a thickness down to 7.5 nm are
epitaxially grown on (0001) Al2O3 substrate by hybrid physical-chemical vapor
deposition method. The films are phase-pure, oxidation-free and continuous. The
7.5 nm thin film shows a Tc(0) of 34 K, which is so far the highest Tc(0)
reported in MgB2 with the same thickness. The critical current density of
ultrathin MgB2 films below 10 nm is demonstrated for the first time as Jc ~
10^6 A cm^{-2} for the above 7.5 nm sample at 16 K. Our results reveal the
excellent superconducting properties of ultrathin MgB2 films with thicknesses
between 7.5 and 40 nm on Al2O3 substrate.Comment: 7 pages, 4 figures, 2 table
The and decays with the fourth generation
If the fourth generation fermions exist, the new quarks could influence the
branching ratios of the decays of and . We
obtain two solutions of the fourth generation CKM factor
from the decay of . We use these
two solutions to calculate the new contributions of the fourth generation quark
to Wilson coefficients of the decay of . The branching ratio
and the forward-backward asymmetry of the decay of in the two
cases are calculated. Our results are quite different from that of SM in one
case, almost same in another case. If Nature chooses the formmer, the meson
decays could provide a possible test of the forth generation existence.Comment: 10 pages, 5 figure
High-resolution (375 m) cloud microstructure as seen from the NPP/VIIRS satellite imager
VIIRS (Visible Infrared Imaging Radiometer Suite), onboard the Suomi NPP
(National Polar-orbiting Partnership) satellite, has an improved resolution of
750 m with respect to the 1000 m of the Moderate Resolution Imaging
Spectroradiometer for the channels that allow retrieving cloud
microphysical parameters such as cloud drop effective radius (<i>r</i><sub>e</sub>).
VIIRS also has an imager with five channels of double resolution of 375 m,
which was not designed for retrieving cloud products. A methodology for a
high-resolution retrieval of <i>r</i><sub>e</sub> and microphysical presentation of the
cloud field based on the VIIRS imager was developed and evaluated with
respect to MODIS in this study. The tripled microphysical resolution with
respect to MODIS allows obtaining new insights for cloud–aerosol
interactions, especially at the smallest cloud scales, because the VIIRS
imager can resolve the small convective elements that are sub-pixel for
MODIS cloud products. Examples are given for new insights into ship tracks in
marine stratocumulus, pollution tracks from point and diffused sources in
stratocumulus and cumulus clouds over land, deep tropical convection in
pristine air mass over ocean and land, tropical clouds that develop in smoke
from forest fires and in heavy pollution haze over densely populated regions
in southeastern Asia, and for pyro-cumulonimbus clouds.
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It is found that the VIIRS imager provides more robust physical
interpretation and refined information for cloud and aerosol microphysics as
compared to MODIS, especially in the initial stage of cloud formation. VIIRS
is found to identify significantly more fully cloudy pixels when small
boundary layer convective elements are present. This, in turn, allows for a
better quantification of cloud–aerosol interactions and impacts on
precipitation-forming processes
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