37,108 research outputs found
Quark Spectral Function and Deconfinement at Nonzero Temperature
The maximum entropy method is used to compute the quark spectral function at
nonzero temperature. We solve the gap equation of quantum chromodynamics (QCD)
self-consistently, employing a rainbow kernel which phenomenologically models
results from Dyson-Schwinger equations (DSE) and lattice QCD. We use the
criterion of positivity restoration of the spectral function as a signal for
deconfinement. Our calculation indicates that the critical temperature of
deconfinement is slightly smaller than the one of chiral symmetry
restoration : in the chiral limit, and
with physical light quark masses. Since these deviations are within the
systematic error of our approach, it is reasonable to conclude that chiral
symmetry restoration and deconfinement coincide at zero chemical potential
Nucleus Driven Electronic Pulsation
We derive and solve by the spectral method the equations for a neutral system
of ultra-relativistic electrons that are compressed to the radius of the
nucleus and subject to a driving force. This driving force can be thought of as
originating from a nuclear breathing mode, a possibility we discuss in detail
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Learning distance to subspace for the nearest subspace methods in high-dimensional data classification
The nearest subspace methods (NSM) are a category of classification methods widely applied to classify high-dimensional data. In this paper, we propose to improve the classification performance of NSM through learning tailored distance metrics from samples to class subspaces. The learned distance metric is termed as ‘learned distance to subspace’ (LD2S). Using LD2S in the classification rule of NSM can make the samples closer to their correct class subspaces while farther away from their wrong class subspaces. In this way, the classification task becomes easier and the classification performance of NSM can be improved. The superior classification performance of using LD2S for NSM is demonstrated on three real-world high-dimensional spectral datasets
Commodity Markets, Price Limiters and Speculative Price Dynamics
We develop a behavioral commodity market model with consumers, producers and heterogeneous speculators to characterize the nature of commodity price fluctuations and to explore the efectiveness of price stabilization schemes. Within our model, nonlinear interactions between market participants can create either bull or bear markets, or irregular price fluctuations between bulland bear markets. Both the imposition of a bottoming price level (to support producers) or a topping price level (to protect consumers) can reduce market price volatility. However, simple policy rules, such as price limiters, may have unexpected consequences in a complex environment: a minimum price level decreases the average price while a maximum price limit increases the average price. In addition, price limiters influence the price dynamics in an intricate way and may cause volatility clustering.commodity markets; price stabilization; simple limiters; technical and fundamental anaysis; bifurcation analysis; chaos control
Microscopic theory of single-electron tunneling through molecular-assembled metallic nanoparticles
We present a microscopic theory of single-electron tunneling through metallic
nanoparticles connected to the electrodes through molecular bridges. It
combines the theory of electron transport through molecular junctions with the
description of the charging dynamics on the nanoparticles. We apply the theory
to study single-electron tunneling through a gold nanoparticle connected to the
gold electrodes through two representative benzene-based molecules. We
calculate the background charge on the nanoparticle induced by the charge
transfer between the nanoparticle and linker molecules, the capacitance and
resistance of molecular junction using a first-principles based Non-Equilibrium
Green's Function theory. We demonstrate the variety of transport
characteristics that can be achieved through ``engineering'' of the
metal-molecule interaction.Comment: To appear in Phys. Rev.
Intelligent Disaster Response via Social Media Analysis - A Survey
The success of a disaster relief and response process is largely dependent on
timely and accurate information regarding the status of the disaster, the
surrounding environment, and the affected people. This information is primarily
provided by first responders on-site and can be enhanced by the firsthand
reports posted in real-time on social media. Many tools and methods have been
developed to automate disaster relief by extracting, analyzing, and visualizing
actionable information from social media. However, these methods are not well
integrated in the relief and response processes and the relation between the
two requires exposition for further advancement. In this survey, we review the
new frontier of intelligent disaster relief and response using social media,
show stages of disasters which are reflected on social media, establish a
connection between proposed methods based on social media and relief efforts by
first responders, and outline pressing challenges and future research
directions.Comment: 14 pages, 3 figures, 104 references, accepted in SIGKDD Exploration
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