149 research outputs found
Entanglement for a Bimodal Cavity Field Interacting with a Two-Level Atom
Negativity has been adopted to investigate the entanglement in a system
composed of a two-level atom and a two-mode cavity field. Effects of Kerr-like
medium and the number of photon inside the cavity on the entanglement are
studied. Our results show that atomic initial state must be superposed, so that
the two cavity field modes can be entangled. Moreover, we also conclude that
the number of photon in the two cavity mode should be equal. The interaction
between modes, namely, the Kerr effect, has a significant negative
contribution. Note that the atom frequency and the cavity frequency have an
indistinguishable effect, so a corresponding approximation has been made in
this article. These results may be useful for quantum information in optics
systems.Comment: Accepted by Commun. Theor. Phy
High Stability Positron Beam Generation Based on Ultra-intense Laser
Relativistic positron beams were generated by laser wakefield electrons bombarding on solid target. Very stable positron beams were generated in our experiments. The total yield of positrons is about 4.4 x 10(8)/shot. The energy spectra of positrons and electrons obey quasi-Maxwell distribution. Compared with the direct method, the indirect method produces positrons (38.5 MeV) and electrons (50.5 MeV) with much higher slope temperature
The complete mitochondrial genomes of five longicorn beetles (Coleoptera: Cerambycidae) and phylogenetic relationships within Cerambycidae
Cerambycidae is one of the most diversified groups within Coleoptera and includes nearly 35,000 known species. The relationships at the subfamily level within Cerambycidae have not been convincingly demonstrated and the gene rearrangement of mitochondrial genomes in Cerambycidae remains unclear due to the low numbers of sequenced mitogenomes. In the present study, we determined five complete mitogenomes of Cerambycidae and investigated the phylogenetic relationship among the subfamilies of Cerambycidae based on mitogenomes. The mitogenomic arrangement of all five species was identical to the ancestral Cerambycidae type without gene rearrangement. Remarkably, however, two large intergenic spacers were detected in the mitogenome of Pterolophia sp. ZJY-2019. The origins of these intergenic spacers could be explained by the slipped-strand mispairing and duplication/random loss models. A conserved motif was found between trnS2 and nad1 gene, which was proposed to be a binding site of a transcription termination peptide. Also, tandem repeat units were identified in the A C T-rich region of all five mitogenomes. The monophyly of Lamiinae and Prioninae was strongly supported by both MrBayes and RAxML analyses based on nucleotide datasets, whereas the Cerambycinae and Lepturinae were recovered as non-monophyletic
Six complete mitochondrial genomes of mayflies from three genera of Ephemerellidae (Insecta: Ephemeroptera) with inversion and translocation of trnI rearrangement and their phylogenetic relationships
As a small order of Pterygota (Insecta), Ephemeroptera has almost 3,500 species around the world. Ephemerellidae is a widely distributed common group of Ephemeroptera. However, the relationship among Ephe
The accretion flow geometry of MAXI J1820+070 through broadband noise research with Insight-HXMT
Here we present a detailed study of the broadband noise in the power density
spectra of the black hole X-ray binary MAXI J1820+070 during the hard state of
its 2018 outburst, using the Hard X-ray Modulation Telescope (Insight-HXMT)
observations. The broadband noise shows two main humps, which might separately
correspond to variability from a variable disk and two Comptonization regions.
We fitted the two humps with multiple Lorentzian functions and studied the
energy-dependent properties of each component up to 100--150 keV and their
evolution with spectral changes. The lowest frequency component is considered
as the sub-harmonic of QPO component and shows different energy dependence
compared with other broadband noise components. We found that although the
fractional rms of all the broadband noise components mainly decrease with
energy, their rms spectra are different in shape. Above 20--30 keV, the
characteristic frequencies of these components increase sharply with energy,
meaning that the high-energy component is more variable on short timescales.
Our results suggest that the hot inner flow in MAXI J1820+070 is likely to be
inhomogeneous. We propose a geometry with a truncated accretion disk, two
Comptonization regions
Fast transitions of X-ray variability in the black hole transient GX 339--4: comparison with MAXI J1820+070 and MAXI J1348-630
Fast transitions between different types of power density spectra (PDS)
happening over timescales of several tens of seconds are rare phenomena in
black hole X-ray binaries. In this paper, we report a broadband spectral-timing
analysis of the fast transitions observed in the 2021 outburst of GX 339-4
using NICER and HXMT observations. We observe transitions between band-limited
noise-dominated PDS and type-B quasi-periodic oscillations (QPOs), and their
rapid appearance or disappearance. We also make a detailed comparison between
the fast transitions in GX 339-4 with those seen in MAXI J1820+070 and MAXI
J1348--630. By comparing the spectra of the periods with and without type-B
QPOs, we find that the spectral ratios above 10 keV are nearly constant or
slightly decreasing, and the values are different between sources. Below 10
keV, the flux change of the Comptonization component is inversely proportional
to the flux change of the thermal component, suggesting that the appearance of
type-B QPOs is associated with a redistribution of the accretion power between
the disc and the Comptonizing emission region. The spectral ratios between the
periods with type-B QPO and those with broadband noise are significantly
different from that with type-B QPO and without type-B QPO, where the ratios
(type-B QPO/broadband noise) show a maximum at around 4 keV and then decrease
gradually towards high energies. Finally, we discuss the possible change of the
geometry of the inner accretion flow and/or jet during the transitions
Inhibition of mitotic kinase Aurora suppresses Akt-1 activation and induces apoptotic cell death in all-trans retinoid acid-resistant acute promyelocytic leukemia cells
Magnetic shielding accelerates the proliferation of human neuroblastoma cell by promoting G1-phase progression
Organisms have been exposed to the geomagnetic field (GMF) throughout evolutionary history. Exposure to the hypomagnetic field (HMF) by deep magnetic shielding has recently been suggested to have a negative effect on the structure and function of the central nervous system, particularly during early development. Although changes in cell growth and differentiation have been observed in the HMF, the effects of the HMF on cell cycle progression still remain unclear. Here we show that continuous HMF exposure significantly increases the proliferation of human neuroblastoma (SH-SY5Y) cells. The acceleration of proliferation results from a forward shift of the cell cycle in G1-phase. The G2/M-phase progression is not affected in the HMF. Our data is the first to demonstrate that the HMF can stimulate the proliferation of SH-SY5Y cells by promoting cell cycle progression in the G1-phase. This provides a novel way to study the mechanism of cells in response to changes of environmental magnetic field including the GMF
R-848 triggers the expression of TLR7/8 and suppresses HIV replication in monocytes
<p>Abstract</p> <p>Background</p> <p>Toll-like receptors (TLR) 7 and 8 are important in single-stranded viral RNA recognition and may play a role in HIV infection and disease progression. We analyzed TLR7/8 expression and signaling in monocytes from HIV-infected and uninfected subjects to investigate a pathway with new potential for the suppression of HIV replication.</p> <p>Methods</p> <p>Eighty-one HIV-infected and uninfected subjects from Liaoning and Henan provinces in China participated in this study. Monocytes were isolated from subjects' peripheral blood mononuclear cells by magnetic bead selection. TLR7 and TLR8 mRNA was measured using quantitative real-time reverse transcriptase PCR. R-848 (resiquimod) was used as a ligand for TLR7 and TLR8 in order to 1) assess TLR7/8-mediated monocyte responsiveness as indicated by IL-12 p40 and TNF-α secretion and 2) to examine HIV replication in cultured monocytes in the presence of R-848.</p> <p>Results</p> <p>We found that expression of TLR7/8 mRNA in peripheral blood monocytes decreased with disease progression. TLR7 expression was decreased with stimulation with the TLR7/8 agonist, R-848, in vitro, whereas TLR8 expression was unaffected. Following R-848 stimulation, monocytes from HIV-infected subjects produced significantly less TNF-α than those from uninfected subjects, but trended towards greater production of IL-12 than stimulated monocytes from uninfected subjects. R-848 stimulation also suppressed HIV replication in cultured monocytes.</p> <p>Conclusions</p> <p>Our study provides evidence that the TLR7 and TLR8 triggering can suppress HIV replication in monocytes and lead to postpone HIV disease progression, thereby offering novel targets for immunomodulatory therapy.</p
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