995 research outputs found
Fast fluorescence dynamics in non-ratiometric calcium indicators
A fluorescence decay of high-affinity non-ratiometric Ca2+ indicator Oregon
Green BAPTA-1 (OGB-1) is analyzed with unprecedented temporal resolution in the
two-photon excitation regime. A triple exponential decay is shown to best fit
the fluorescence dynamics of OGB-1. We provide a new model for accurate
measurements of the free Ca2+ concentration and dissociation constants of
non-ratiometric calcium indicators.Comment: 3 pages, 2 figures, figures revised, added chi-square goodness of fi
Postpartum psychosis and sleep disorders: what is the link?
Introduction:
The term "postpartum psychosis" refers to a severe mental illness that begins abruptly shortly after childbirth. The pathophysiology of postpartum psychosis is poorly understood, but factors such as primiparity, difficult labor, genetic predisposition, and hormonal changes have been suggested as
etiological factors. It is argued that sleep loss resulting from the interaction of various putative causal factors may be the final common pathway in the development of psychosis in susceptible women
On the Application of a Monolithic Array for Detecting Intensity-Correlated Photons Emitted by Different Source Types
It is not widely appreciated that many subtleties are involved in the
accurate measurement of intensity-correlated photons; even for the original
experiments of Hanbury Brown and Twiss (HBT). Using a monolithic 4x4 array of
single-photon avalanche diodes (SPADs), together with an off-chip algorithm for
processing streaming data, we investigate the difficulties of measuring
second-order photon correlations g2 in a wide variety of light fields that
exhibit dramatically different correlation statistics: a multimode He-Ne laser,
an incoherent intensity-modulated lamp-light source and a thermal light source.
Our off-chip algorithm treats multiple photon-arrivals at pixel-array pairs, in
any observation interval, with photon fluxes limited by detector saturation, in
such a way that a correctly normalized g2 function is guaranteed. The impact of
detector background correlations between SPAD pixels and afterpulsing effects
on second-order coherence measurements is discussed. These results demonstrate
that our monolithic SPAD array enables access to effects that are otherwise
impossible to measure with stand-alone detectors.Comment: 17 pages, 6 figure
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