142 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
Fractal geometry of Ising magnetic patterns: signatures of criticality and diffusive dynamics
We investigate the geometric properties displayed by the magnetic patterns
developing on a two-dimensional Ising system, when a diffusive thermal dynamics
is adopted. Such a dynamics is generated by a random walker which diffuses
throughout the sites of the lattice, updating the relevant spins. Since the
walker is biased towards borders between clusters, the border-sites are more
likely to be updated with respect to a non-diffusive dynamics and therefore, we
expect the spin configurations to be affected. In particular, by means of the
box-counting technique, we measure the fractal dimension of magnetic patterns
emerging on the lattice, as the temperature is varied. Interestingly, our
results provide a geometric signature of the phase transition and they also
highlight some non-trivial, quantitative differences between the behaviors
pertaining to the diffusive and non-diffusive dynamics
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
Two interacting diffusing particles on low-dimensional discrete structures
In this paper we study the motion of two particles diffusing on
low-dimensional discrete structures in presence of a hard-core repulsive
interaction. We show that the problem can be mapped in two decoupled problems
of single particles diffusing on different graphs by a transformation we call
'diffusion graph transform'. This technique is applied to study two specific
cases: the narrow comb and the ladder lattice. We focus on the determination of
the long time probabilities for the contact between particles and their
reciprocal crossing. We also obtain the mean square dispersion of the particles
in the case of the narrow comb lattice. The case of a sticking potential and of
'vicious' particles are discussed.Comment: 9 pages, 6 postscript figures, to appear in 'Journal of Physics
A',-January 200
Target annihilation by diffusing particles in inhomogeneous geometries
The survival probability of immobile targets, annihilated by a population of
random walkers on inhomogeneous discrete structures, such as disordered solids,
glasses, fractals, polymer networks and gels, is analytically investigated. It
is shown that, while it cannot in general be related to the number of distinct
visited points, as in the case of homogeneous lattices, in the case of bounded
coordination numbers its asymptotic behaviour at large times can still be
expressed in terms of the spectral dimension , and its exact
analytical expression is given. The results show that the asymptotic survival
probability is site independent on recurrent structures (),
while on transient structures () it can strongly depend on the
target position, and such a dependence is explicitly calculated.Comment: To appear in Physical Review E - Rapid Communication
Salivary cytokines as biomarkers for oral squamous cell carcinoma: A systematic review
The prognosis of patients with oral squamous carcinoma (OSCC) largely depends on the stage at diagnosis, the 5-year survival rate being approximately 30% for advanced tumors. Early diagnosis, including the detection of lesions at risk for malignant transformation, is crucial for limiting the need for extensive surgery and for improving disease-free survival. Saliva has gained popularity as a readily available source of biomarkers (including cytokines) useful for diagnosing specific oral and systemic conditions. Particularly, the close interaction between oral dysplastic/neoplastic cells and saliva makes such fluid an ideal candidate for the development of non-invasive and highly accurate diagnostic tests. The present review has been designed to answer the question: “Is there evidence to support the role of specific salivary cytokines in the diagnosis of OSCC?” We retrieved 27 observational studies satisfying the inclusion and exclusion criteria. Among the most frequent cytokines investigated as candidates for OSCC biomarkers, IL-6, IL-8, TNF-α are present at higher concentration in the saliva of OSCC patients than in healthy controls and may therefore serve as basis for the development of rapid tests for early diagnosis of oral cancer
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