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

Shaping field correlations with quantum antennas

Quantum antennas can shape the spatial entanglement of emitted photons originating from specific initial non-Dicke entangled states of antenna emitters. In contrast to a classical antenna, a quantum antenna might not be affecting the amplitudes and intensities distribution of the field, but only shaping the second and higher order correlations. The shape and directivity of the correlations can be optimized using quantum state inference techniques. The character of the correlations can also be controlled by changing both the geometry and the initial state of the antenna. Positive and negative correlated twin-photons, as well as multi-photons entangled states can be produced from the same antenna for different initial states of the emitters. Our approach to antenna design can find applications in imaging and high-precision sensing, as well as in the development of an emitter-field interface for quantum information processing

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