281 research outputs found
News and price returns from threshold behaviour and vice-versa: exact solution of a simple agent-based market model
Starting from an exact relationship between news, threshold and price return
distributions in the stationary state, I discuss the ability of the
Ghoulmie-Cont-Nadal model of traders to produce fat-tailed price returns. Under
normal conditions, this model is not able to transform Gaussian news into
fat-tailed price returns. When the variance of the news so small that only the
players with zero threshold can possibly react to news, this model produces
Levy-distributed price returns with a -1 exponent. In the special case of
super-linear price impact functions, fat-tailed returns are obtained from
well-behaved news.Comment: 4 pages, 3 figures. This is quite possibly the final version. To
appear in J. Phys
Mechanisms of Self-Organization and Finite Size Effects in a Minimal Agent Based Model
We present a detailed analysis of the self-organization phenomenon in which
the stylized facts originate from finite size effects with respect to the
number of agents considered and disappear in the limit of an infinite
population. By introducing the possibility that agents can enter or leave the
market depending on the behavior of the price, it is possible to show that the
system self-organizes in a regime with a finite number of agents which
corresponds to the stylized facts. The mechanism to enter or leave the market
is based on the idea that a too stable market is unappealing for traders while
the presence of price movements attracts agents to enter and speculate on the
market. We show that this mechanism is also compatible with the idea that
agents are scared by a noisy and risky market at shorter time scales. We also
show that the mechanism for self-organization is robust with respect to
variations of the exit/entry rules and that the attempt to trigger the system
to self-organize in a region without stylized facts leads to an unrealistic
dynamics. We study the self-organization in a specific agent based model but we
believe that the basic ideas should be of general validity.Comment: 14 pages, 7 figure
Serum antioxidant capacity and peroxide level of seven healthy subjects after consumption of different foods
This article reports experimental data related to the research article entitled \u201cDifferent effectiveness of two pastas supplemented with either lipophilic or hydrophilic/phenolic antioxidants in affecting serum as evaluated by the novel Antioxidant/Oxidant Balance approach\u201d (M.N. Laus, M. Soccio, M. Alfarano, A. Pasqualone, M.S. Lenucci, G. Di Miceli, D. Pastore, 2016) [1]. Antioxidant status of blood serum of seven healthy subjects was evaluated during four hours after consumption of two functional pastas, supplemented with either bran oleoresin or bran water extract obtained from durum wheat. For comparison, the effect of a non-supplemented reference pasta was also evaluated, as well as the effects of glucose, of the wheat grain dietary supplement Lisosan G, and of the reference pasta consumed together with Lisosan G. Serum antioxidant status was evaluated by measuring both the serum antioxidant capacity, using LOX-FL, ORAC and TEAC methods, and the serum oxidant status, assessed as peroxide level
Myocarditis and intramural coronary vasculitis in polyarteritis nodosa: an unusual treatable form of heart failure
We describe an uncommon cardiac presentation of polyarteritis nodosa. A 68-year-old woman, with a history of fatigue, weight loss, and myalgia of the lower extremities, was admitted for congestive heart failure. Coronary arteries were normal. Endomyocardial biopsy showed active lymphocytic myocarditis with associated intramural small vessels necrotizing vasculitis. The overexpression of TLR-4 and the negativity for myocardial viruses suggested an immune mediated mechanism of cardiac damage. These histologic findings associated to weight loss >4 kg not due to dieting or other factors, myalgias, and polyneuropathy, were consistent with the diagnosis of polyarteritis nodosa. Immunosuppressive treatment, consisting of cyclophosphamide and prednisolone, led to a significant improvement of cardiac function. Polyarteritis nodosa can be the cause of unexplained heart failure due to myocarditis and intramural vessels vasculitis. Its recognition is crucial to obtain a cardiac recovery with a tailored immunosuppressive treatment
Agent based reasoning for the non-linear stochastic models of long-range memory
We extend Kirman's model by introducing variable event time scale. The
proposed flexible time scale is equivalent to the variable trading activity
observed in financial markets. Stochastic version of the extended Kirman's
agent based model is compared to the non-linear stochastic models of long-range
memory in financial markets. Agent based model providing matching macroscopic
description serves as a microscopic reasoning of the earlier proposed
stochastic model exhibiting power law statistics.Comment: 10 pages, 3 figure
Comprehensive Analysis of Market Conditions in the Foreign Exchange Market: Fluctuation Scaling and Variance-Covariance Matrix
We investigate quotation and transaction activities in the foreign exchange
market for every week during the period of June 2007 to December 2010. A
scaling relationship between the mean values of number of quotations (or number
of transactions) for various currency pairs and the corresponding standard
deviations holds for a majority of the weeks. However, the scaling breaks in
some time intervals, which is related to the emergence of market shocks. There
is a monotonous relationship between values of scaling indices and global
averages of currency pair cross-correlations when both quantities are observed
for various window lengths .Comment: 13 pages, 10 figure
SWITCHING RATES AND THE ASYMPTOTIC BEHAVIOR OF HERDING MODELS
Markov chains have experienced a surge of economic interest in the form of behavioral agent-based models that aim at explaining the statistical regularities of financial returns. We review some of the relevant mathematical facts and show how they apply to agent-based herding models, with the particular goal of establishing their asymptotic behavior because several studies have pointed out that the ability of such models to reproduce the stylized facts hinges crucially on the size of the agent population (typically denoted by n), a phenomenon that is also known as n-dependence. Our main finding is that n-(in)dependence traces back to both the topology and the velocity of information transmission among heterogeneous financial agents
GWIDD: Genome-wide protein docking database
Structural information on interacting proteins is important for understanding life processes at the molecular level. Genome-wide docking database is an integrated resource for structural studies of protein–protein interactions on the genome scale, which combines the available experimental data with models obtained by docking techniques. Current database version (August 2009) contains 25 559 experimental and modeled 3D structures for 771 organisms spanned over the entire universe of life from viruses to humans. Data are organized in a relational database with user-friendly search interface allowing exploration of the database content by a number of parameters. Search results can be interactively previewed and downloaded as PDB-formatted files, along with the information relevant to the specified interactions. The resource is freely available at http://gwidd.bioinformatics.ku.edu
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