1,191 research outputs found
The distribution of wealth in the presence of altruism for simple economic models
We study the effect of altruism in two simple asset exchange models: the yard
sale model (winner gets a random fraction of the poorer player's wealth) and
the theft and fraud model (winner gets a random fraction of the loser's
wealth). We also introduce in these models the concept of bargaining
efficiency, which makes the poorer trader more aggressive in getting a
favorable deal thus augmenting his winning probabilities. The altruistic
behavior is controlled by varying the number of traders that behave
altruistically and by the degree of altruism that they show. The resulting
wealth distribution is characterized using the Gini index. We compare the
resulting values of the Gini index at different levels of altruism in both
models. It is found that altruistic behavior does lead to a more equitable
wealth distribution but only for unreasonable high values of altruism that are
difficult to expect in a real economic system.Comment: Accepted in Physica A: Statistical Mechanics and its Application
Synthesis of 1-p-methoxyphenyl- and 1-(p-methoxyphenyl)-4- methylbicyclo(2.2.1)heptan-7-one. The oxidation of 7-hydroxy-1-(p- methoxyphenyl)-4-methylbicyclo(2.2.1)heptane-7-carboxylic acid with lead tetraacetate
A simple synthetic route to 1-p-methoxyphenyl and 1-p-methoxyphenyl-4-methylbicyclo [2.2.1]heptan-7-one 6b,a has been developed through benzilic acid rearrangement of the bicyclo[2.2.1]octandiones 2b,a. The oxidation of 7-hydroxy-1-p-methoxyphenyl-4-methylbicyclo[2.2.1]heptan-7-carboxylic acid 3a with lead tetraacetate gives the carbolactone 7a which is also formed by the reaction of the ketone 6a with m-chloroperbenzoic acid
IONS (ANURADHA): Ionization states of low energy cosmic rays
IONS (ANURADHA), the experimental payload designed specifically to determine the ionization states, flux, composition, energy spectra and arrival directions of low energy (10 to 100 MeV/amu) anomalous cosmic ray ions of helium to iron in near-Earth space, had a highly successful flight and operation Spacelab-3 mission. The experiment combines the accuracy of a highly sensitive CR-39 nuclear track detector with active components included in the payload to achieve the experimental objectives. Post-flight analysis of detector calibration pieces placed within the payload indicated no measurable changes in detector response due to its exposure in spacelab environment. Nuclear tracks produced by alpha-particles, oxygen group and Fe ions in low energy anomalous cosmic rays were identified. It is calculated that the main detector has recorded high quality events of about 10,000 alpha-particles and similar number of oxygen group and heavier ions of low energy cosmic rays
Quantum entanglement: The unitary 8-vertex braid matrix with imaginary rapidity
We study quantum entanglements induced on product states by the action of
8-vertex braid matrices, rendered unitary with purely imaginary spectral
parameters (rapidity). The unitarity is displayed via the "canonical
factorization" of the coefficients of the projectors spanning the basis. This
adds one more new facet to the famous and fascinating features of the 8-vertex
model. The double periodicity and the analytic properties of the elliptic
functions involved lead to a rich structure of the 3-tangle quantifying the
entanglement. We thus explore the complex relationship between topological and
quantum entanglement.Comment: 4 pages in REVTeX format, 2 figure
Study of statistical correlations in intraday and daily financial return time series
The aim of this article is to briefly review and make new studies of
correlations and co-movements of stocks, so as to understand the
"seasonalities" and market evolution. Using the intraday data of the CAC40, we
begin by reasserting the findings of Allez and Bouchaud [New J. Phys. 13,
025010 (2011)]: the average correlation between stocks increases throughout the
day. We then use multidimensional scaling (MDS) in generating maps and
visualizing the dynamic evolution of the stock market during the day. We do not
find any marked difference in the structure of the market during a day. Another
aim is to use daily data for MDS studies, and visualize or detect specific
sectors in a market and periods of crisis. We suggest that this type of
visualization may be used in identifying potential pairs of stocks for "pairs
trade".Comment: 22 pages, 11 figures, Springer-Verlag format. To appear in the
conference proceedings of Econophys-Kolkata VI: "Econophysics of systemic
risk and network dynamics", Eds. F. Abergel, B.K. Chakrabarti, A. Chakraborti
and A. Ghosh, to be published by Springer-Verlag (Italia), Milan (2012
Radiation Induced Xerostomia: Current Concepts and Future Trends
Radiation induced xerostomia is a persistent clinical presentation that affects the quality of life in head and neck cancer patients even with the best of the intensity modulated radiotherapy protocols. Comprehensive review of the anatomic, histologic, developmental and neuronal entities of salivary glands from a regenerative perspective, ensuing radiation is taken. It also evaluates the systemic and glandular radiation responses that form the early and late clinical changes. From these, the article submits probable strategies; based on the current knowledge and future challenges involved, in reversing radiation induced xerostomia. Further, it elaborates on the status of radioprotectors and mitigators including the recently reported biologic and chemical derivatives and proposes the rationale of using combination radioprotector therapy in radiation injuries. A brief of palliative regimes, alternate treatment modes and technologic advancements in radiotherapy are also explained. Salivary gland histologic components, which need to be protected in the emerging radiotherapy protocols and can be targeted in different salivary gland regeneration therapies is highlighted. The paper contributes to an improved understanding in radiation induced xerostomia and deliberates on novel mechanisms towards enhancing quality of life in head and neck cancer radiotherapy patients
Relativistic supernovae have shorter-lived central engines or more extended progenitors: the case of SN\,2012ap
Deep late-time X-ray observations of the relativistic, engine-driven, type Ic
SN2012ap allow us to probe the nearby environment of the explosion and reveal
the unique properties of relativistic SNe. We find that on a local scale of
~0.01 pc the environment was shaped directly by the evolution of the progenitor
star with a pre-explosion mass-loss rate <5x10^-6 Msun yr-1 in line with GRBs
and the other relativistic SN2009bb. Like sub-energetic GRBs, SN2012ap is
characterized by a bright radio emission and evidence for mildly relativistic
ejecta. However, its late time (t~20 days) X-ray emission is ~100 times fainter
than the faintest sub-energetic GRB at the same epoch, with no evidence for
late-time central engine activity. These results support theoretical proposals
that link relativistic SNe like 2009bb and 2012ap with the weakest observed
engine-driven explosions, where the jet barely fails to breakout. Furthermore,
our observations demonstrate that the difference between relativistic SNe and
sub-energetic GRBs is intrinsic and not due to line-of-sight effects. This
phenomenology can either be due to an intrinsically shorter-lived engine or to
a more extended progenitor in relativistic SNe.Comment: Version accepted to ApJ. Significantly broadened discussio
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