11,796 research outputs found
Autocatalytic reaction-diffusion processes in restricted geometries
We study the dynamics of a system made up of particles of two different
species undergoing irreversible quadratic autocatalytic reactions: . We especially focus on the reaction velocity and on the average time at
which the system achieves its inert state. By means of both analytical and
numerical methods, we are also able to highlight the role of topology in the
temporal evolution of the system
Universal features of information spreading efficiency on -dimensional lattices
A model for information spreading in a population of mobile agents is
extended to -dimensional regular lattices. This model, already studied on
two-dimensional lattices, also takes into account the degeneration of
information as it passes from one agent to the other. Here, we find that the
structure of the underlying lattice strongly affects the time at which
the whole population has been reached by information. By comparing numerical
simulations with mean-field calculations, we show that dimension is
marginal for this problem and mean-field calculations become exact for .
Nevertheless, the striking nonmonotonic behavior exhibited by the final degree
of information with respect to and the lattice size appears to be
geometry independent.Comment: 8 pages, 9 figure
Autocatalytic reaction-diffusion processes in restricted geometries
We study the dynamics of a system made up of particles of two different
species undergoing irreversible quadratic autocatalytic reactions: . We especially focus on the reaction velocity and on the average time at
which the system achieves its inert state. By means of both analytical and
numerical methods, we are also able to highlight the role of topology in the
temporal evolution of the system
The meaning of different forms of structural myocardial injury, immune response and timing of infarct necrosis and cardiac repair
Although a decline in the all-cause and cardiac mortality rates following myocardial infarction (MI) during the past 3 decades has been reported, MI is a major cause of death and disability worldwide. From a pathological point of view MI consists in a particular myocardial cell death due to prolonged ischemia. After the onset of myocardial ischemia, cell death is not immediate, but takes a finite period of time to develop. Once complete myocytes’ necrosis has occurred, a process leading to a healed infarction takes place. In fact, MI is a dynamic process that begins with the transition from reversible to irreversible ischemic injury and culminates in the replacement of dead myocardium by a fibrous scar. The pathobiological mechanisms underlying this process are very complex, involving an inflammatory response by several pathways, and pose a major challenge to ability to improve our knowledge. An improved understanding of the pathobiology of cardiac repair after MI and further studies of its underlying mechanisms provide avenues for the development of future strategies directed toward the identification of novel therapies. The chronologic dating of MI is of great importance both to clinical and forensic investigation, that is, the ability to create a theoretical timeline upon which either clinicians or forensic pathologists may increase their ability to estimate the time of MI. Aging of MI has very important practical implications in clinical practice since, based on the chronological dating of MI, attractive alternatives to solve therapeutic strategies in the various phases of MI are developing
Numerical precision radiative corrections to the Dalitz plot of baryon semileptonic decays including the spin-momentum correlation of the decaying and emitted baryons
We calculate the radiative corrections to the angular correlation between the
polarization of the decaying and the direction of the emitted spin one-half
baryons in the semileptonic decay mode. The final results are presented, first,
with the triple integration of the bremsstrahlung photon ready to be performed
numerically and, second, in an analytical form. A third presentation of our
results in the form of numerical arrays of coefficients to be multiplied by the
quadratic products of form factors is discussed. This latter may be the most
practical one to use in Monte Carlo simulations. A series of crosschecks is
performed. Previous results to order (alpha/pi)(q/M_1) for the decays of
unpolarized baryons are reviewed, too, where q is the momentum transfer and M_1
is the mass of the decaying baryon. This paper is self-contained and organized
to make it accessible and reliable in the analysis of the Dalitz plot of
precision experiments involving heavy quarks and is not compromised to fixing
the form factors at predetermined values. It is assumed that the real photons
are kinematically discriminated. Otherwise, our results have a general
model-independent applicability.Comment: 34 pages, 4 tables, no figures. Some sections have been shortened.
Conclusions remain unchange
Anisotropic renormalized fluctuations in the microwave resistivity in YBCO
We discuss the excess conductivity above Tc due to renormalized
order-parameter fluctuations in YBCO at microwave frequencies. We calculate the
effects of the uniaxial anisotropy on the renormalized fluctuations in the
Hartree approximation, extending the isotropic theory developed by Dorsey
[Phys. Rev. B 43, 7575 (1991)]. Measurements of the real part of the microwave
resistivity at 24 and 48 GHz and of the dc resistivity are performed on
different YBCO films. The onset of the superconducting transition and the
deviation from the linear temperature behavior above Tc can be fully accounted
for by the extended theory. According to the theoretical calculation here
presented, a departure from gaussian toward renormalized fluctuations is
observed. Very consistent values of the fundamental parameters (critical
temperature, coherence lenghts, penetration depth) of the superconducting state
are obtained.Comment: RevTex, 8 pages with 5 figures included, to be published in Physical
Review
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