Search PubMed⌕ Search

Biomedical subjects

C Degli Esposti Boschi

Publications and source records attributed to C Degli Esposti Boschi.

6 recordsLinked to original sources
PubMed2006

Role of transport performance for neuron cell morphology.

The compartmental model is a basic tool for studying signal propagation in neurons; if the model parameters are adequately redefined, it can also be helpful in the study of electrical or fluid transport in other biological systems. Here we show that the input resistance in different networks that simulate the morphology of neurons is the result of the interplay between the relevant conductances, neuron morphology, and neuron size. The results suggest that neurons may grow in such a way that facilitates the current flow to the synapses, concurrently minimizing power consumption.

Animals↗
PubMed2006

Long-distance entanglement in spin systems.

Most quantum system with short-ranged interactions show a fast decay of entanglement with the distance. In this Letter, we focus on the peculiarity of some systems to distribute entanglement between distant parties. Even in realistic models, like the spin-1 Heisenberg chain, sizable entanglement is present between arbitrarily distant particles. We show that long-distance entanglement appears for values of the microscopic parameters which do not coincide with known quantum critical points, hence signaling a transition detected only by genuine quantum correlations.

Journal Article↗
PubMed2002

Effects of fluctuations on electrical properties of gap-junction connected cells in the turtle retina.

Electrical properties of gap-junction connected cells (input voltage and length constant) are shown to depend strongly on fluctuations in membrane and contact conductances. This opens new possibilities and incorporates a further difficulty to the analysis of electrophysiological data, since four, instead of two, parameters (the average values and the magnitude of fluctuations of the two conductances) have to be used in fitting the experimental data. The discussion is illustrated by investigating the effects of dopamine on signal spreading in horizontal cells of turtle retina, assuming a linear cell arrangement. It is shown that while a standard fitting with the average values of the two conductances leads to the conclusion that both are equally affected by dopamine, including fluctuations allows fitting the data by varying just the average contact conductance plus the magnitude of fluctuations.

Animals↗
PubMed2001

Detecting determinism in high-dimensional chaotic systems.

A method based upon the statistical evaluation of the differentiability of the measure along the trajectory is used to identify determinism in high-dimensional systems. The results show that the method is suitable for discriminating stochastic from deterministic systems even if the dimension of the latter is as high as 13. The method is shown to succeed in identifying determinism in electroencephalogram signals simulated by means of a high-dimensional system.

Journal Article↗
PubMed2001

Instability versus nonlinearity in certain nonautonomous oscillators: A critical dynamical transition driven by the initial energy.

The equation of motion q+Omega(2)(t)q+alpha/q/(gamma-2)q=0 (gamma>2) for the real coordinate q(t) is studied, as an example of the interplay between nonlinearity and instability. Two contrasting mechanisms determine the behavior of q(t), when the time-varying frequency Omega(t) does produce exponential instability in the linear equation q (lin)+Omega(2)(t)q(lin)=0. At low energy, the exponential instability is the dominant effect, while at high energy the bounding effect of the autonomous nonlinear term prevails. Starting from low initial energies, the result of this competition is a time-varying energy characterized by quasiperiodic peaks, with an average recurrence time T(peak). A closed critical curve S(omega) exists in the initial phase space, whose crossing corresponds to a divergence of the recurrence time T(peak). The divergence of T(peak) has a universal character, expressed by a critical exponent a=1. The critical curve S(omega) is the initial locus of the solutions that vanish asymptotically. A close relationship exists between this dynamical transition and the transition from mobile to self-trapped polarons in one spatial dimension. The application to a number of physical problems is addressed, with special attention to the Fermi-Pasta-Ulam problem and to transitions to chaos.

Journal Article↗