7,071 research outputs found
Improvement of conversion efficiency of atom-molecule Bose-Einstein condensate
We investigate the stimulated Raman adiabatic passage in two-color
photoassociation for a atom-molecule Bose-Einstein condensate. By applying two
time-varying Guassian laser pulses that fulfill generalized two-photon
resonance condition, we obtain highly efficient atom-molecule conversion. The
efficiency depends on the free-bound detuning and the delay time between the
two pulses. By adjusting the parameters optimally, we achieve 92% conversion
efficiency.Comment: 4 pages, 4 figures. To be appeared in J. Korean Phys. Society (JKPS
Storage of spin squeezing in a two-component Bose-Einstein condensate
Efficient control of spin squeezing in a two-component Bose-Einstein
Condensate is studied by rapidly turning-off the external field at a time that
maximal spin squeezing appears. We show that strong reduction of spin
fluctuation can be maintained in a nearly fixed direction for a long time. We
explain the underlying physics unambiguously, and present analytical
expressions of the maximal-squeezing time.Comment: 10 pages, 5 figures. This version is slightly different from the one
published in Phys. Rev. Let
Spin squeezing and maximal-squeezing time
Spin squeezing of a nonlinear interaction model with Josephson-like coupling
is studied to obtain time scale of maximal squeezing. Based upon two exactly
solvable cases for two and three particles, we find that the maximal-squeezing
time depends on the level spacing between the ground state and its next
neighbor eigenstate.Comment: 7 pages, 5 figures, 1 table. Resubmitted to Phys. Rev.
Epigenetic Regulation of Hepatitis B Virus Replication
Hepatitis B virus (HBV) is the most important cause of chronic viral hepatitis worldwide. The genome of HBV is 3.2Â kb partially double-stranded DNA, which is translocated to the nuclei of infected hepatocytes and converted to complete double-stranded DNA, aka covalently closed circular DNA (cccDNA). Typical course of chronic HBV infection results in inactive carrier state with clearance of viral particles in the bloodstream. However, the cccDNA can be detected in the hepatocytes from inactive carriers by sensitive methods. It has been increasingly known that epigenetic mechanisms contribute to the control of HBV replication in the inactive stage of HBV infection. Histone modification and DNA methylation have been identified in the HBV cccDNA, leading to modification of transcriptional activity. The understanding of epigenetic control of transcription will shed light on the development of new therapeutic strategy against HBV cccDNA
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