717 research outputs found
Kinetic market models with single commodity having price fluctuations
We study here numerically the behavior of an ideal gas like model of markets
having only one non-consumable commodity. We investigate the behavior of the
steady-state distributions of money, commodity and total wealth, as the
dynamics of trading or exchange of money and commodity proceeds, with local (in
time) fluctuations in the price of the commodity. These distributions are
studied in markets with agents having uniform and random saving factors. The
self-organizing features in money distribution are similar to the cases without
any commodity (or with consumable commodities), while the commodity
distribution shows an exponential decay. The wealth distribution shows
interesting behavior: Gamma like distribution for uniform saving propensity and
has the same power-law tail, as that of the money distribution, for a market
with agents having random saving propensity.Comment: RevTeX4, 6 pages, 5 eps figures, accepted in Eur. Phys. J.
Hubungan Kadar Tumor Necrosis Factor – Α Dengan Densitas Plasmodium Pada Penderita Malaria
: Malaria is a parasitic infection that attacks the erythrocytes. This disease remains a global health problem, especially in developing countries in the tropics and subtropics. Symptomatic malaria infection include fever, chills, anemia and splenomegaly. Malaria infection can progress without any complications but can also develop systemic complications known as severe malaria. The cause of malaria is plasmodium infection, Plasmodium in humans infected erythrocytes (red blood cells) and asexual breeding experience in liver tissue and erythrocytes. In this research, the microscopic examination of blood samples for counting malaria parasites in the blood and then measured the levels of TNF-α by ELISA. This analytical study using 40 samples taken by simple random sampling. The results showed that there is a significant relationship between the amount of TNF-α levels plasmodium with. Conclusions: There were significant correlation between the levels of TNF-α with a density of plasmodium malaria in blood samples
Deteksi Blastocystis Spp Pada Tinja Anak Penderita Diare Dengan Menggunakan Metode Copro Elisa
: Diarrhea is one of the main cause of infant mortality in developing countries. Blastocystis spp can cause acute infection as well as manifest as chronic diarrhea in infants due to damaged intestinal mucosa. This study aimed to detect Blastocystis spp in the feces of children with diarrhea. This was a descriptive study with a cross-sectional design. Population consisted of all feces of children suffering from diarrhea. There were 33 samples in this study examined with the copro Elisa test. The results showed that of the 33 samples there were 60.6% of negative criteria and 39.4% of positive criteria. The highest percentage age group with diarrhea was ≤1 year of age (48.5%), while the lowest one was age group of 5-9 years (9.1%). Male sex was the dominant one. Conclusion: Most of the faeces of children with diarrhea belonged to the negative criteria tested with Copro Elisa
Direct Search for Low Mass Dark Matter Particles with CCDs
A direct dark matter search is performed using fully-depleted
high-resistivity CCD detectors . Due to their low electronic readout noise (RMS
~ 7 eV) these devices operate with a very low detection threshold of 40 eV,
making the search for dark matter particles with low masses (~ 5 GeV) possible.
The results of an engineering run performed in a shallow underground site are
presented, demonstrating the potential of this technology in the low mass
region
Critical slowing down in polynomial time algorithms
Combinatorial optimization algorithms which compute exact ground state
configurations in disordered magnets are seen to exhibit critical slowing down
at zero temperature phase transitions. Using arguments based on the physical
picture of the model, including vanishing stiffness on scales beyond the
correlation length and the ground state degeneracy, the number of operations
carried out by one such algorithm, the push-relabel algorithm for the random
field Ising model, can be estimated. Some scaling can also be predicted for the
2D spin glass.Comment: 4 pp., 3 fig
Kinetic Exchange Models for Income and Wealth Distributions
Increasingly, a huge amount of statistics have been gathered which clearly
indicates that income and wealth distributions in various countries or
societies follow a robust pattern, close to the Gibbs distribution of energy in
an ideal gas in equilibrium. However, it also deviates in the low income and
more significantly for the high income ranges. Application of physics models
provides illuminating ideas and understanding, complementing the observations.Comment: 15 pages, 20 eps figures, EPJ class; To be published as "Colloquium"
in Eur Phys J
Basic kinetic wealth-exchange models: common features and open problems
We review the basic kinetic wealth-exchange models of Angle [J. Angle, Social
Forces 65 (1986) 293; J. Math. Sociol. 26 (2002) 217], Bennati [E. Bennati,
Rivista Internazionale di Scienze Economiche e Commerciali 35 (1988) 735],
Chakraborti and Chakrabarti [A. Chakraborti, B. K. Chakrabarti, Eur. Phys. J. B
17 (2000) 167], and of Dragulescu and Yakovenko [A. Dragulescu, V. M.
Yakovenko, Eur. Phys. J. B 17 (2000) 723]. Analytical fitting forms for the
equilibrium wealth distributions are proposed. The influence of heterogeneity
is investigated, the appearance of the fat tail in the wealth distribution and
the relaxation to equilibrium are discussed. A unified reformulation of the
models considered is suggested.Comment: Updated version; 9 pages, 5 figures, 2 table
Entropy and equilibrium state of free market models
Many recent models of trade dynamics use the simple idea of wealth exchanges
among economic agents in order to obtain a stable or equilibrium distribution
of wealth among the agents. In particular, a plain analogy compares the wealth
in a society with the energy in a physical system, and the trade between agents
to the energy exchange between molecules during collisions. In physical
systems, the energy exchange among molecules leads to a state of equipartition
of the energy and to an equilibrium situation where the entropy is a maximum.
On the other hand, in the majority of exchange models, the system converges to
a very unequal condensed state, where one or a few agents concentrate all the
wealth of the society while the wide majority of agents shares zero or almost
zero fraction of the wealth. So, in those economic systems a minimum entropy
state is attained. We propose here an analytical model where we investigate the
effects of a particular class of economic exchanges that minimize the entropy.
By solving the model we discuss the conditions that can drive the system to a
state of minimum entropy, as well as the mechanisms to recover a kind of
equipartition of wealth
Yard-Sale exchange on networks: Wealth sharing and wealth appropriation
Yard-Sale (YS) is a stochastic multiplicative wealth-exchange model with two
phases: a stable one where wealth is shared, and an unstable one where wealth
condenses onto one agent. YS is here studied numerically on 1d rings, 2d square
lattices, and random graphs with variable average coordination, comparing its
properties with those in mean field (MF). Equilibrium properties in the stable
phase are almost unaffected by the introduction of a network. Measurement of
decorrelation times in the stable phase allow us to determine the critical
interface with very good precision, and it turns out to be the same, for all
networks analyzed, as the one that can be analytically derived in MF. In the
unstable phase, on the other hand, dynamical as well as asymptotic properties
are strongly network-dependent. Wealth no longer condenses on a single agent,
as in MF, but onto an extensive set of agents, the properties of which depend
on the network. Connections with previous studies of coalescence of immobile
reactants are discussed, and their analytic predictions are successfully
compared with our numerical results.Comment: 10 pages, 7 figures. Submitted to JSTA
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