23,659 research outputs found
Hadronic and electromagnetic probes of hot and dense matter in a Boltzmann+Hydrodynamics model of relativistic nuclear collisions
We present recent results on bulk observables and electromagnetic probes
obtained using a hybrid approach based on the Ultrarelativistic Quantum
Molecular Dynamics transport model with an intermediate hydrodynamic stage for
the description of heavy-ion collisions at AGS, SPS and RHIC energies. After
briefly reviewing the main results for particle multiplicities, elliptic flow,
transverse momentum and rapidity spectra, we focus on photon and dilepton
emission from hot and dense hadronic matter.Comment: To appear in the proceedings of WISH 2010: International Workshop on
Interplay between Soft and Hard interactions in particle production at
ultrarelativistic energies, Catania, Italy, 8-10 September 201
Bankruptcy risk model and empirical tests
We analyze the size dependence and temporal stability of firm bankruptcy risk
in the US economy by applying Zipf scaling techniques. We focus on a single
risk factor-the debt-to-asset ratio R-in order to study the stability of the
Zipf distribution of R over time. We find that the Zipf exponent increases
during market crashes, implying that firms go bankrupt with larger values of R.
Based on the Zipf analysis, we employ Bayes's theorem and relate the
conditional probability that a bankrupt firm has a ratio R with the conditional
probability of bankruptcy for a firm with a given R value. For 2,737 bankrupt
firms, we demonstrate size dependence in assets change during the bankruptcy
proceedings. Prepetition firm assets and petition firm assets follow Zipf
distributions but with different exponents, meaning that firms with smaller
assets adjust their assets more than firms with larger assets during the
bankruptcy process. We compare bankrupt firms with nonbankrupt firms by
analyzing the assets and liabilities of two large subsets of the US economy:
2,545 Nasdaq members and 1,680 New York Stock Exchange (NYSE) members. We find
that both assets and liabilities follow a Pareto distribution. The finding is
not a trivial consequence of the Zipf scaling relationship of firm size
quantified by employees-although the market capitalization of Nasdaq stocks
follows a Pareto distribution, the same distribution does not describe NYSE
stocks. We propose a coupled Simon model that simultaneously evolves both
assets and debt with the possibility of bankruptcy, and we also consider the
possibility of firm mergers.Comment: 8 pages, 8 figure
Energy Dependence of High Moments for Net-proton Distributions
High moments of multiplicity distributions of conserved quantities are
predicted to be sensitive to critical fluctuations. To understand the effect of
the complicated non-critical physics backgrounds on the proposed observable, we
have studied various moments of net-proton distributions with AMPT, Hijing,
Therminator and UrQMD models, in which no QCD critical point physics is
implemented. It is found that the centrality evolution of various moments of
net-proton distributions can be uniformly described by a superposition of
emission sources. In addition, in the absence of critical phenomena, some
moment products of net-proton distribution, related to the baryon number
susceptibilities ratio in Lattice QCD calculation, are predicted to be constant
as a function of the collision centrality. We argue that a non-monotonic
dependence of the moment products as a function collision centrality and the
beam energy may be used to locate the QCD critical point.Comment: SQM2009 Proceeding, 6 pages, 5 figure
On the distribution of career longevity and the evolution of home run prowess in professional baseball
Statistical analysis is a major aspect of baseball, from player averages to
historical benchmarks and records. Much of baseball fanfare is based around
players exceeding the norm, some in a single game and others over a long
career. Career statistics serve as a metric for classifying players and
establishing their historical legacy. However, the concept of records and
benchmarks assumes that the level of competition in baseball is stationary in
time. Here we show that power-law probability density functions, a hallmark of
many complex systems that are driven by competition, govern career longevity in
baseball. We also find similar power laws in the density functions of all major
performance metrics for pitchers and batters. The use of performance-enhancing
drugs has a dark history, emerging as a problem for both amateur and
professional sports. We find statistical evidence consistent with
performance-enhancing drugs in the analysis of home runs hit by players in the
last 25 years. This is corroborated by the findings of the Mitchell Report [1],
a two-year investigation into the use of illegal steroids in major league
baseball, which recently revealed that over 5 percent of major league baseball
players tested positive for performance-enhancing drugs in an anonymous 2003
survey.Comment: 5 pages, 5 figures, 2-column revtex4 format. Revision has change of
title, a figure added, and minor changes in response to referee comment
Dried fruits, nuts, and cancer risk and survival: a review of the evidence and future research directions
Dried fruits and nuts contain high amounts of nutrients and phytochemicals—all of which may have anticarcinogenic, anti-inflammatory, and antioxidant properties. This narrative review summarizes the evidence for dried fruits and nuts and cancer incidence, mortality, and survival and their potential anticancer properties. The evidence for dried fruits in cancer outcomes is limited, but existing studies have suggested an inverse relationship between total dried fruit consumption and cancer risk. A higher consumption of nuts has been associated with a reduced risk of several site-specific cancers in prospective cohort studies, including cancers of the colon, lung, and pancreas, with relative risks per 5 g/day increment equal to 0.75 (95% CI 0.60, 0.94), 0.97 (95% CI 0.95, 0.98), and 0.94 (95% CI 0.89, 0.99), respectively. A daily intake of total nuts of 28 g/day has also been associated with a 21% reduction in the rate of cancer mortality. There is also some evidence that frequent nut consumption is associated with improved survival outcomes among patients with colorectal, breast, and prostate cancer; however, further studies are needed. Future research directions include the investigation of additional cancer types, including rare types of cancer. For cancer prognosis, additional studies with pre- and postdiagnosis dietary assessment are warranted
Bounded Counter Languages
We show that deterministic finite automata equipped with two-way heads
are equivalent to deterministic machines with a single two-way input head and
linearly bounded counters if the accepted language is strictly bounded,
i.e., a subset of for a fixed sequence of symbols . Then we investigate linear speed-up for counter machines. Lower
and upper time bounds for concrete recognition problems are shown, implying
that in general linear speed-up does not hold for counter machines. For bounded
languages we develop a technique for speeding up computations by any constant
factor at the expense of adding a fixed number of counters
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