592 research outputs found
Normal modes and time evolution of a holographic superconductor after a quantum quench
We employ holographic techniques to investigate the dynamics of the order
parameter of a strongly coupled superconductor after a perturbation that drives
the system out of equilibrium. The gravity dual that we employ is the Soliton background at zero temperature. We first analyze the normal
modes associated to the superconducting order parameter which are purely real
since the background has no horizon. We then study the full time evolution of
the order parameter after a quench. For sufficiently a weak and slow
perturbation we show that the order parameter undergoes simple undamped
oscillations in time with a frequency that agrees with the lowest normal model
computed previously. This is expected as the soliton background has no horizon
and therefore, at least in the probe and large limits considered, the
system will never return to equilibrium. For stronger and more abrupt
perturbations higher normal modes are excited and the pattern of oscillations
becomes increasingly intricate. We identify a range of parameters for which the
time evolution of the order parameter become quasi chaotic. The details of the
chaotic evolution depend on the type of perturbation used. Therefore it is
plausible to expect that it is possible to engineer a perturbation that leads
to the almost complete destruction of the oscillating pattern and consequently
to quasi equilibration induced by superposition of modes with different
frequencies.Comment: 10 pages, 7 figures, corrected typos, expanded section on chaotic
oscillations and new results for other quenc
Axion-meson mixing in light of recent lattice - simulations and their two-photon couplings within chiral theory
We study the mixing of the QCD/QCD-like axion and light-flavor mesons within the framework of chiral perturbation theory up to
next-to-leading order in this work. The axion-meson mixing formulas are
calculated order by order in the -expansion scheme, namely the
joint expansions of the momentum, light-quark masses and . We provide
axion-meson mixing relations in terms of the -- mixing
parameters and their masses. The recent lattice simulations on the
- systems turn out to be able to offer valuable inputs to
constrain the unknown low-energy constants. The relation of the mass and decay
constant of the axion is then further explored based on our updated
calculations. The two-photon couplings of the light-flavor mesons, together
with the axion, are also investigated in the chiral theory up to
next-to-leading order in the -counting scheme.Comment: 23 pages, 3 figure
O,O′-Diethyl {(Z)-[(2-chlorophenyl)(cyano)methylene]aminooxy}thiophosphonate
The title molecule, C12H14ClN2O3PS, has a cis configuration with respect to the C=N bond. Intermolecular C—H⋯O interactions interconnect the molecules into chains along the c axis. The chains are further connected into a two-dimensional network parallel to the bc plane by weak π–π interactions between adjacent aromatic rings (centroid–centroid distance = 3.772Å)
Cationic liposomes induce cytotoxicity in HepG2 via regulation of lipid metabolism based on whole-transcriptome sequencing analysis
Abstract
Backgroud
Cationic liposomes (CLs) can be used as non-viral vectors in gene transfer and drug delivery. However, the underlying molecular mechanism of its cytotoxicity has not been well elucidated yet.
Methods
We herein report a systems biology approach based on whole-transcriptome sequencing coupled with computational method to identify the predominant genes and pathways involved in the cytotoxicity of CLs in HepG2 cell line.
Results
Firstly, we validated the concentration-dependent cytotoxicity of CLs with an IC50 of 120 μg/ml in HepG2 exposed for 24 h. Subsequently, we used whole-transcriptome sequencing to identify 220 (77 up- and 143 down-regulated) differentially expressed genes (DEGs). Gene ontology (GO) and pathway analysis showed that these DEGs were mainly related to cholesterol, steroid, lipid biosynthetic and metabolic processes. Additionally, “key regulatory” genes were identified using gene act, pathway act and co-expression network analysis, and expression levels of 11 interested altered genes were confirmed by quantitative real time PCR. Interestingly, no cell cycle arrest was observed through flow cytometry.
Conclusions
These data are expected to provide deep insights into the molecular mechanism of CLs cytotoxicity.https://deepblue.lib.umich.edu/bitstream/2027.42/144776/1/40360_2018_Article_230.pd
GRB 120729A: External Shock Origin for Both the Prompt Gamma-Ray Emission and Afterglow
Gamma-ray burst (GRB) 120729A was detected by Swift/BAT and Fermi/GBM, and then rapidly observed by Swift/XRT, Swift/UVOT, and ground-based telescopes. It had a single long and smooth \gamma-ray emission pulse, which extends continuously to the X-rays. We report Lick/KAIT observations of the source, and make temporal and spectral joint fits of the multiwavelength light curves of GRB 120729A. It exhibits achromatic light-curve behavior, consistent with the predictions of the external shock model. The light curves are decomposed into four typical phases: onset bump (Phase I), normal decay (Phase II), shallow decay (Phase III), and post-jet break (Phase IV). The spectral energy distribution (SED) evolves from prompt \gamma-ray emission to the afterglow with photon index from Γγ=1.36 to Γ≈1.75. There is no obvious evolution of the SED during the afterglow. ...(Please see article full tet for complete abstract.
Correction: Hong, K. et al. Actinomycetes for Marine Drug Discovery Isolated from Mangrove Soils and Plants in China. Mar. Drugs 2009, 7, 24–44
We found an error in our paper published in Marine Drugs [1]. [...
Influence Mechanism of Main Roof Height on Surrounding Rock Stability of Gob-Side Entry Driving
The main roof directly affects the stress environment and the control effect of the surrounding rock of gob-side entry driving. A mechanical model of the surrounding rock of gob-side entry driving was established to analyze the influence mechanism of different main roof heights on the surrounding rock stability of the roadway under similar geological conditions. In addition, the influences of the main roof heights on the stress distribution of the surrounding rock were qualitatively analyzed. A quantitative analysis of the stress and deformation distribution characteristics of the surrounding rock were conducted by Universal Distinct Element Code (UDEC) when the heights were 0, 5, and 10 m based on the actual geological conditions. Results show that waste rocks in the caving zone and damaged immediate roof could provide four different stress combinations to key rock block, which is affected by the main roof height and other related parameters. With the increase in the main roof height, the hinged stress between the key rock blocks and the plastic damage area of the physical coal wall are reduced, the damage range of immediate roof gradually increases, and the vertical stress of narrow coal pillars first increases to 5.22 MPa and then remains at approximately 1.92 MPa. Therefore, the supporting strength of roof and the physical coal wall should be enhanced. Research results are successfully applied in the Yanjiahe Coal Mine. The conclusions provide significant theoretical guidance for controlling surrounding rock stability of the roadway under similar conditions
Heterodichogamy in Kingdonia (Circaeasteraceae, Ranunculales)
Background and Aims Preliminary field observations in 2001 and 2002 suggested that Kingdonia uniflora (Circaeasteraceae, Ranunculales) exhibits heterodichogamy, an unusual kind of reproductive heteromorphy, hitherto unreported in Ranunculales and known from only one other genus in basal eudicots. Methods During several subsequent years flowers were observed in the field. Flowers were fixed in FAA and studied with microtome sections series and with the scanning electron microscope. Key Results The flowers proved to be heterodichogamous, with protandrous and protogynous morphs, which have a 1 : 1 ratio. Both morphs equally set fruit. Each year a single flower is formed at the tip of a rhizome or more rarely two flowers. The flowers are already open when they appear at the soil surface, before they are receptive and before pollen is dispersed. In both floral morphs the styles elongate early and the stigmas are positioned above the anthers before anthesis begins. In protogynous flowers the stigmas become receptive in this position; later the styles become reflexed and then the anthers dehisce. In contrast, in protandrous flowers the stamen filaments elongate during early anthesis such that the dehiscing anthers come to lie above the (still unreceptive) stigmas; after dehiscence of all anthers in a flower the styles begin to elongate and become receptive. Conclusions This is the first record of heterodichogamy in a representative of Ranunculales, in an herbaceous eudicot, and in a plant with uniflorous ramets. The occurrence of heterodichogamy in Kingdonia in which clonal reproduction appears to be dominant might be an adaptation to avoid mating between the ramets from a common mother individual (genet
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