4,996 research outputs found
Crowd synchrony and quorum sensing in delay-coupled lasers
Crowd synchrony and quorum sensing arise when a large number of dynamical
elements communicate with each other via a common information pool. Previous
evidence in different fields, including chemistry, biology and civil
engineering, has shown that this type of coupling leads to synchronization,
when coupling is instantaneous and the number of coupled elements is large
enough. Here we consider a situation in which the transmission of information
between the system components and the coupling pool is not instantaneous. To
that end, we model a system of semiconductor lasers optically coupled to a
central laser with a delay. Our results show that, even though the lasers are
non-identical due to their distinct optical frequencies, zero-lag
synchronization arises. By changing a system parameter, we can switch between
two different types of synchronization transition. The dependence of the
transition with respect to the delay-coupling parameters is studied.Comment: 4 pages, 4 figure
Innovation and jobs: evidence from manufacturing firms
This paper is aimed at structurally assessing the employment effects of the innovative activities of firms. We estimate firm level displacement and compensation effects in a model in which the stock of knowledge capital raises firm relative efficiency through process innovations and firm demand through product innovations. Displacement is estimated from the elasticity of employment with respect to innovation in the (conditional or Hicksian) demand for labour. Compensation effects are estimated from a firm-specific demand relationship. We also assess the enlargement and weakening of these effects due to firm agentsâ behaviour aimed at appropriating innovation rents. We find that the potential employment compensation effect of process innovations surpasses the displacement effect, both in the short and long run (when competitors react), and that product innovation doubles the expanding impact by unit of expenditure, but also that agentsâ behaviour can seriously reduce these effects. The actual elasticity of employment to knowledge capital is estimated, however, not far from unity, while âpassiveâ productivity growth is suggested to have null or negative employment effects.
Updated global fit to three neutrino mixing: status of the hints of theta13 > 0
We present an up-to-date global analysis of solar, atmospheric, reactor and
accelerator neutrino data in the framework of three-neutrino oscillations. We
discuss in detail the statistical significance of the observed "hint" of
non-zero theta13 in the solar sector at the light of the latest experimental
advances, such as the Borexino spectral data, the lower value of Gallium rate
recently measured in SAGE, and the low energy threshold analysis of the
combined SNO phase I and phase II. We also study the robustness of the results
under changes of the inputs such as the choice of solar model fluxes and a
possible modification of the Gallium capture cross-section as proposed by SAGE.
In the atmospheric sector we focus on the latest results for nu_e appearance
from MINOS and on the recent Super-Kamiokande results from the combined phases
I, II and III, and we discuss their impact on the determination of theta13.
Finally, we combine all the data into a global analysis and determine the
presently allowed ranges of masses and mixing.Comment: 20 pages, 9 figures. Acknowledgments correcte
Dynamical Consequences of Bandpass Feedback Loops in a Bacterial Phosphorelay
Under conditions of nutrient limitation, Bacillus subtilis cells terminally differentiate into a dormant spore state. Progression to sporulation is controlled by a genetic circuit consisting of a phosphorelay embedded in multiple transcriptional feedback loops, which is used to activate the master regulator Spo0A by phosphorylation. These transcriptional regulatory interactions are âbandpassâ-like, in the sense that activation occurs within a limited band of Spo0A~P concentrations. Additionally, recent results show that the phosphorelay activation occurs in pulses, in a cell-cycle dependent fashion. However, the impact of these pulsed bandpass interactions on the circuit dynamics preceding sporulation remains unclear. In order to address this question, we measured key features of the bandpass interactions at the single-cell level and analyzed them in the context of a simple mathematical model. The model predicted the emergence of a delayed phase shift between the pulsing activity of the different sporulation genes, as well as the existence of a stable state, with elevated Spo0A activity but no sporulation, embedded within the dynamical structure of the system. To test the model, we used time-lapse fluorescence microscopy to measure dynamics of single cells initiating sporulation. We observed the delayed phase shift emerging during the progression to sporulation, while a re-engineering of the sporulation circuit revealed behavior resembling the predicted additional state. These results show that periodically-driven bandpass feedback loops can give rise to complex dynamics in the progression towards sporulation
Robust Cosmological Bounds on Neutrinos and their Combination with Oscillation Results
We perform a global analysis of cosmological observables in generalized
cosmologies which depart from CDM models by allowing non-vanishing
curvature , dark energy with equation of state with , the presence of additional relativistic degrees of freedom , and neutrino masses . By combining the data from
cosmic microwave background (CMB) experiments (in particular the latest results
from WMAP-7), the present day Hubble constant (H0) measurement, the
high-redshift Type-I supernovae (SN) results and the information from large
scale structure (LSS) surveys, we determine the parameters in the
10-dimensional parameter space for such models. We present the results from the
analysis when the full shape information from the LSS matter power spectrum
(LSSPS) is included versus when only the corresponding distance measurement
from the baryon acoustic oscillations (BAO) is accounted for. We compare the
bounds on the neutrino mass scale in these generalized scenarios with those
obtained for the 6+1 parameter analysis in models and
we also study the dependence of those on the set of observables included in the
analysis. Finally we combine these results with the information on neutrino
mass differences and mixing from the global analysis of neutrino oscillation
experiments and derive the presently allowed ranges for the two laboratory
probes of the absolute scale of neutrino mass: the effective electron neutrino
mass in single beta decay and the effective Majorana neutrino mass in
neutrinoless decay.Comment: 19 pages, 4 figures. Acknowledgments correcte
Cortical Spike Synchrony as a Measure of Input Familiarity
J.G.O. was supported by the Ministerio de Economia y Competividad and FEDER (Spain, project FIS2015-66503-C3-1-P) and the ICREA Academia programme. E.U. acknowledges support from the Scottish Universities Life Sciences Alliance (SULSA) and HPC-Europa2.Peer reviewedPostprin
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