arXiv subjects

J. Yin

Publications and source records attributed to J. Yin.

21 records · Page 2Linked to original sources

arXiv2008

Properties and Chemical Evolution of the M31 Disk: Comparison with the Milky Way

By adopting the chemical evolution model of the Milky Way disk, we have studied the star formation and chemical evolution history for M31 galaxy disk. We mainly concentrated on the global properties of the M31 disk. The model has been scaled to the related disk parameters, mainly the disk scale length and total disk baryon mass of M31, which we have adopted to be $r_d$=5.5kpc and $M_{tot} = 7\times 10^{10}$ \ms. It is found that, when the classical Kennicutt star formation law was applied, the obtained radial profiles of gas surface density and star formation rate (SFR) have great difference from the observed results in M31 disk. Then we have adopted modified SFR as we did for the Milky Way galaxy, that is the SFR is radial dependent. Detailed calculations show that by adjusting the star formation efficiency, it is possible to get reasonable gas and abundance profiles, but the total disk SFR is a factor of 2-3 higher than that estimated from observations. And also the predicted SFR radial profile is also much higher than what GALEX observed in the outer part. Possible reasons could be that the M31 disk has been interacted by other factors which seriously altered the star formation history, or the observed SFR is underestimated due to inappropriate extinction correction.

astro-ph↗

arXiv2005

Experimental Fault-Tolerant Quantum Cryptography in a Decoherence-Free Subspace

we experimentally implement a fault-tolerant quantum key distribution protocol with two photons in a decoherence-free subspace (DFS). It is demonstrated that our protocol can yield good key rate even with large bit-flip error rate caused by collective rotation, while the usual realization of BB84 protocol cannot produce any secure final key given the same channel. Since the experiment is performed in polarization space and does not need the calibration of reference frame, important applications in free-space quantum communication are expected. Moreover, our method can also be used to robustly transmit an arbitrary two-level quantum state in a type of DFS.

quant-ph↗

arXiv2004

Ion Transit Pathways and Gating in ClC Chloride Channels

ClC chloride channels possess a homodimeric structure in which each monomer contains an independent chloride ion pathway. ClC channel gating is regulated by chloride ion concentration, pH, and voltage. Based on structural and physiological evidence, it has been proposed that a glutamate residue on the extracellular end of the selectivity filter acts as a fast gate. We utilize a new search algorithm which incorporates electrostatic information to explore the ion transit pathways through wild-type and mutant bacterial ClC channels. Examination of the chloride ion permeation pathways supports the proposed important role of the glutamate residue in gating. An external chloride binding site previously postulated in physiological experiments is located near a conserved basic residue adjacent to the gate. In addition, access pathways are found for proton migration to the gate, enabling pH control at hyperpolarized membrane potentials. A chloride ion in the selectivity filter is required for the pH-dependent gating mechanism.

physics.bio-ph↗