Both the timing and kinetics of neurotransmitter release depend on the positioning of clustered Ca2+ channels in active zones to docked synaptic vesicles on presynaptic plasma membranes. However, how ...active zones form is not known. Here, we show that RIM and RIM-BP, via specific multivalent bindings, form dynamic and condensed assemblies through liquid-liquid phase separation. Voltage-gated Ca2+ channels (VGCCs), via C-terminal-tail-mediated direct binding to both RIM and RIM-BP, can be enriched to the RIM and RIM-BP condensates. We further show that RIM and RIM-BP, together with VGCCs, form dense clusters on the supported lipid membrane bilayers via phase separation. Therefore, RIMs and RIM-BPs are plausible organizers of active zones, and the formation of RIM and RIM-BP condensates may cluster VGCCs into nano- or microdomains and position the clustered Ca2+ channels with Ca2+ sensors on docked vesicles for efficient and precise synaptic transmissions.
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•RIM and RIM-BP mixture forms liquid-liquid phase-separation-mediated condensates•Specific multivalent interaction between RIM and RIM-BP is essential for the LLPS•RIM and RIM-BP condensates cluster Ca2+ channels in solution and on membrane surface•RIM and RIM-BP are plausible organizers of presynaptic active zones
Clustering of Ca2+ channels at presynaptic active zones is critical for precise control of neurotransmitter release. Wu et al. show that the presynaptic active zone scaffold proteins RIM and RIM-BP form self-assembled condensates via liquid-liquid phase separations capable of clustering voltage-gated Ca2+ channels on lipid membrane bilayers.
A quantum memory, for storing and retrieving flying photonic quantum states, is a key interface for realizing long-distance quantum communication and large-scale quantum computation. While many ...experimental schemes demonstrating high storage and retrieval efficiency have been performed with weak coherent light pulses, all quantum memories for true single photons achieved so far have efficiencies far below 50%, a threshold value for practical applications. Here, we report the demonstration of a quantum memory for single-photon polarization qubits with an efficiency of >85% and a fidelity of >99%, based on balanced two-channel electromagnetically induced transparency in laser-cooled rubidium atoms. For the single-channel quantum memory, the optimized efficiency for storing and retrieving single-photon temporal waveforms can be as high as 90.6%. This result pushes the photonic quantum memory closer to practical applications in quantum information processing.A quantum memory for single-photon polarization qubits with an efficiency of >85% and a fidelity of >99% is demonstrated. It is achieved by suppressing the noise and by controlling the spectral–temporal states of single photons in laser-cooled Rb atoms.
Non-Hermitian optical systems with parity-time (PT) symmetry have recently revealed many intriguing prospects that outperform conservative structures. The previous works are mostly rooted in complex ...arrangements with controlled gain-loss interplay. Here, we demonstrate anti-PT symmetry inherent in the nonlinear optical interaction based upon forward optical four-wave mixing in a laser-cooled atomic ensemble with negligible linear gain and loss. We observe that the pair of frequency modes undergo a nontrivial anti-PT phase transition between coherent power oscillation and optical parametric amplification in presence of a large phase mismatch.
We report an experiment demonstrating the generation of directional thermal radiation with a spectral brightness that is about 9 times greater than that of the ambient pumping reservoir. The ...experiment is based on the recent proposal for a nontraditional quantum heat engine and uses cold Rb atoms, electromagnetically induced transparency, and photon correlation spectroscopy Phys. Rev. A 94, 053859 (2016)PLRAAN2469-992610.1103/PhysRevA.94.053859.
Efficient charge transfer between ZnO quantum dots (QDs) and graphene is demonstrated by decorating ZnO QDs on top of graphene, with the assistance of oxygen molecules from the air. The electrical ...response of the device to UV light is greatly enhanced, and a photoconductive gain of up to 107 can be obtained.
A compression method for DNA Du, Shengwang; Li, Junyi; Bian, Naizheng
PloS one,
11/2020, Letnik:
15, Številka:
11
Journal Article
Recenzirano
Odprti dostop
The development of high-throughput sequencing technology has generated huge amounts DNA data. Many general compression algorithms are not ideal for compressing DNA data, such as the LZ77 algorithm. ...On the basis of Nour and Sharawi's method,we propose a new, lossless and reference-free method to increase the compression performance. The original sequences are converted into eight intermediate files and six final files. Then, the LZ77 algorithm is used to compress the six final files. The results show that the compression time is decreased by 83% and the decompression time is decreased by 54% on average.The compression rate is almost the same as Nour and Sharawi's method which is the fastest method so far. What's more, our method has a wider range of application than Nour and Sharawi's method. Compared to some very advanced compression tools at present, such as XM and FCM-Mx, the time for compression in our method is much smaller, on average decreasing the time by more than 90%.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Entangled photon pairs, termed as biphotons, have been the benchmark tool for experimental quantum optics. The quantum-network protocols based on photon-atom interfaces have stimulated a great demand ...for single photons with bandwidth comparable to or narrower than the atomic natural linewidth. In the past decade, laser-cooled atoms have often been used for producing such biphotons, but the apparatus is too large and complicated for engineering. Here we report the generation of subnatural-linewidth (<6 MHz) biphotons from a Doppler-broadened (530 MHz) hot atomic vapour cell. We use on-resonance spontaneous four-wave mixing in a hot paraffin-coated
Rb vapour cell at 63 °C to produce biphotons with controllable bandwidth (1.9-3.2 MHz) and coherence time (47-94 ns). Our backward phase-matching scheme with spatially separated optical pumping is the key to suppress uncorrelated photons from resonance fluorescence. The result may lead towards miniature narrowband biphoton sources.
Formation of membraneless organelles or biological condensates via phase separation and related processes hugely expands the cellular organelle repertoire. Biological condensates are dense and ...viscoelastic soft matters instead of canonical dilute solutions. To date, numerous different biological condensates have been discovered, but mechanistic understanding of biological condensates remains scarce. In this study, we developed an adaptive single-molecule imaging method that allows simultaneous tracking of individual molecules and their motion trajectories in both condensed and dilute phases of various biological condensates. The method enables quantitative measurements of concentrations, phase boundary, motion behavior, and speed of molecules in both condensed and dilute phases, as well as the scale and speed of molecular exchanges between the two phases. Notably, molecules in the condensed phase do not undergo uniform Brownian motion, but instead constantly switch between a (class of) confined state(s) and a random diffusion-like motion state. Transient confinement is consistent with strong interactions associated with large molecular networks (i.e., percolation) in the condensed phase. In this way, molecules in biological condensates behave distinctly different from those in dilute solutions. The methods and findings described herein should be generally applicable for deciphering the molecular mechanisms underlying the assembly, dynamics, and consequently functional implications of biological condensates.
Single-molecule localization microscopy (SMLM) can be used to resolve subcellular structures and achieve a tenfold improvement in spatial resolution compared to that obtained by conventional ...fluorescence microscopy. However, the separation of single-molecule fluorescence events that requires thousands of frames dramatically increases the image acquisition time and phototoxicity, impeding the observation of instantaneous intracellular dynamics. Here we develop a deep-learning based single-frame super-resolution microscopy (SFSRM) method which utilizes a subpixel edge map and a multicomponent optimization strategy to guide the neural network to reconstruct a super-resolution image from a single frame of a diffraction-limited image. Under a tolerable signal density and an affordable signal-to-noise ratio, SFSRM enables high-fidelity live-cell imaging with spatiotemporal resolutions of 30 nm and 10 ms, allowing for prolonged monitoring of subcellular dynamics such as interplays between mitochondria and endoplasmic reticulum, the vesicle transport along microtubules, and the endosome fusion and fission. Moreover, its adaptability to different microscopes and spectra makes it a useful tool for various imaging systems.
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