2,785 research outputs found
Two distinct desynchronization processes caused by lesions in globally coupled neurons
To accomplish a task, the brain works like a synchronized neuronal network
where all the involved neurons work together. When a lesion spreads in the
brain, depending on its evolution, it can reach a significant portion of
relevant area. As a consequence, a phase transition might occur: the neurons
desynchronize and cannot perform a certain task anymore. Lesions are
responsible for either disrupting the neuronal connections or, in some cases,
for killing the neuron. In this work, we will use a simplified model of
neuronal network to show that these two types of lesions cause different types
of desynchronization.Comment: 5 pages, 3 figure
Energy and volume of vector fields on spherical domains
We present in this paper a \boundary version" for theorems about minimality
of volume and energy functionals on a spherical domain of threedimensional
Euclidean sphere
Asymmetric information and imperfect competition in the loan market
We measure the consequences of asymmetric information in the Italian market for small business
lines of credit. Exploiting detailed, proprietary data on a random sample of Italian firms, the population
of medium and large Italian banks, individual lines of credit between them, and subsequent individual
defaults, we estimate models of demand for credit, loan pricing, loan use, and firm default based on
the seminal work of Stiglitz and Weiss (1981) to measure the extent and consequences of asymmetric
information in this market. While our data include a measure of observable credit risk comparable to that
available to a bank during the application process, we allow firms to have private information about the
underlying riskiness of their project. This riskiness influences banks’ pricing of loans as higher interest
rates attract a riskier pool of borrowers, increasing aggregate default probabilities. Data on default, loan
size, demand, and pricing separately identify the distribution of private riskiness from heterogeneous
firm disutility from paying interest. Preliminary results suggest evidence of asymmetric information,
separately identifying adverse selection and moral hazard. We use our results to quantify the impact of
asymmetric information on pricing and welfare, and the role imperfect competition plays in mediating
these effects
Phase synchronization of coupled bursting neurons and the generalized Kuramoto model
Bursting neurons fire rapid sequences of action potential spikes followed by
a quiescent period. The basic dynamical mechanism of bursting is the slow
currents that modulate a fast spiking activity caused by rapid ionic currents.
Minimal models of bursting neurons must include both effects. We considered one
of these models and its relation with a generalized Kuramoto model, thanks to
the definition of a geometrical phase for bursting and a corresponding
frequency. We considered neuronal networks with different connection topologies
and investigated the transition from a non-synchronized to a partially
phase-synchronized state as the coupling strength is varied. The numerically
determined critical coupling strength value for this transition to occur is
compared with theoretical results valid for the generalized Kuramoto model.Comment: 31 pages, 5 figure
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