10,679 research outputs found
On the bar pattern speed determination of NGC 3367
An important dynamic parameter of barred galaxies is the bar pattern speed.
Among several methods that are used for the determination of the pattern speed
the Tremaine-Weinberg method has the advantage of model independency and
accuracy. In this work we apply the method to a simulated bar including gas
dynamics and study the effect of 2D spectroscopy data quality on robustness of
the method. We added a white noise and a Gaussian random field to the data and
measured the corresponding errors in the pattern speed. We found that a signal
to noise ratio in surface density ~5 introduces errors of ~20% for the Gaussian
noise, while for the white noise the corresponding errors reach ~50%. At the
same time the velocity field is less sensitive to contamination. On the basis
of the performed study we applied the method to the NGC 3367 spiral galaxy
using H{\alpha} Fabry-Perot interferometry data. We found for the pattern speed
43 \pm 6 km/s/kpc for this galaxy.Comment: Accepted for publication in ApJ. 16 pages, 16 figure
Double Inverse Stochastic Resonance with Dynamic Synapses
We investigate the behavior of a model neuron that receives a
biophysically-realistic noisy post-synaptic current based on uncorrelated
spiking activity from a large number of afferents. We show that, with static
synapses, such noise can give rise to inverse stochastic resonance (ISR) as a
function of the presynaptic firing rate. We compare this to the case with
dynamic synapses that feature short-term synaptic plasticity, and show that the
interval of presynaptic firing rate over which ISR exists can be extended or
diminished. We consider both short-term depression and facilitation.
Interestingly, we find that a double inverse stochastic resonance (DISR), with
two distinct wells centered at different presynaptic firing rates, can appear.Comment: 12 pages, 7 figure
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