55 research outputs found
Reduced phosphoCREB in Müller glia during retinal degeneration in rd10 mice
The mechanisms that trigger retinal degeneration are not well understood, despite the availability of several animal models with different mutations. In the present report, the rd10 mouse, a model for retinitis pigmentosa (RP) that contains a mutation in the gene for PDE6β (Pde6b), is used to evaluate gliosis, as a marker for retinal stress, and cyclic AMP response element binding protein (CREB) phosphorylation, which may be important early in retinal degeneration
Topological Single Photon Emission from Quantum Emitter Chains
We develop a scheme of generating highly indistinguishable single photons
from an active quantum Su-Schrieffer-Heeger chain made from a collection of
noisy quantum emitters. Surprisingly, the single photon emission spectrum of
the active quantum chain is extremely narrow compared to that of a single
emitter or topologically trivial chain. Moreover, this effect becomes
dramatically strong close to the non-trivial-to-trivial phase transition point.
Using this effect, we show that the single photon linewidth of a long
topological quantum chain can become arbitrarily narrow, constituting an ideal
source of indistinguishable single photons. Finally, taking specific examples
of actual quantum emitters, we provide a microscopic and quantitative analysis
of our model and analyze the most important parameters in view of the
experimental realization
Bulk photovoltaic effect in two-dimensional ferroelectric semiconductor -InSe
Bulk photovoltaic effect, which arises from crystal symmetry-driven charge
carrier separation, is an intriguing physical phenomenon that has attracted
extensive interest in photovoltaic application due to its junction-free
photovoltaic and potential to surpass Shockley-Queisser limit. Whereas
conventional ferroelectric materials mostly suffer from extremely low
photocurrent density and weak photovoltaic response at visible light
wavelengths. Emerging two-dimensional ferroelectric semiconductors with coupled
visible light absorption and spontaneous polarization characteristics are a
promising alternative for making functional photoferroelectrics. Herein, we
report the experimental demonstration of the bulk photovoltaic effect behavior
based on the 2D ferroelectric semiconductor {-InSe caused by an
out-of-plane polarization induced depolarization field. The {-InSe
device exhibits enhanced bulk photovoltaic response in the visible light
spectrum owing to its narrow bandgap. It was demonstrated that the generated
photovoltaic current density was nearly two orders of magnitude greater than
conventional bulk ferroelectric materials. These findings highlight the
potential of 2D ferroelectric semiconductor materials for bulk photovoltaic
applications in a broad spectral region
Deep Verifier Networks: Verification of Deep Discriminative Models with Deep Generative Models
AI Safety is a major concern in many deep learning applications such as
autonomous driving. Given a trained deep learning model, an important natural
problem is how to reliably verify the model's prediction. In this paper, we
propose a novel framework -- deep verifier networks (DVN) to verify the inputs
and outputs of deep discriminative models with deep generative models. Our
proposed model is based on conditional variational auto-encoders with
disentanglement constraints. We give both intuitive and theoretical
justifications of the model. Our verifier network is trained independently with
the prediction model, which eliminates the need of retraining the verifier
network for a new model. We test the verifier network on out-of-distribution
detection and adversarial example detection problems, as well as anomaly
detection problems in structured prediction tasks such as image caption
generation. We achieve state-of-the-art results in all of these problems.Comment: Accepted to AAAI 202
Room-temperature continuous-wave pumped exciton polariton condensation in a perovskite microcavity
Microcavity exciton polaritons (polaritons) as part-light part-matter
quasiparticles, garner significant attention for non-equilibrium Bose-Einstein
condensation at elevated temperatures. Recently, halide perovskites have
emerged as promising room-temperature polaritonic platforms thanks to their
large exciton binding energies and superior optical properties. However,
currently, inducing room-temperature non-equilibrium polariton condensation in
perovskite microcavities requires optical pulsed excitations with high
excitation densities. Herein, we demonstrate continuous-wave optically pumped
polariton condensation with an exceptionally low threshold of ~0.6 W cm-2 and a
narrow linewidth of ~1 meV. Polariton condensation is unambiguously
demonstrated by characterizing the nonlinear behavior and coherence properties.
We also identify a microscopic mechanism involving the potential landscape in
the perovskite microcavity, where numerous discretized energy levels arising
from the hybridization of adjacent potential minima enhance the polariton
relaxation, facilitating polariton condensate formation. Our findings lay the
foundation for the next-generation energy-efficient polaritonic devices
operating at room temperature.Comment: 16 pages, 4 figure
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
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