308 research outputs found
Detecting Lensing-Induced Diffraction in Astrophysical Gravitational Waves
Gravitational waves emitted from compact binary coalescence can be subject to
wave diffraction if they are gravitationally lensed by an intervening mass
clump whose Schwarzschild timescale matches the wave period. Waves in the
ground-based frequency band --Hz are sensitive to clumps with
masses -- enclosed within the impact parameter.
These can be the central parts of low mass --
dark matter halos, which are predicted in Cold Dark Matter scenarios but are
challenging to observe. Neglecting finely-tuned impact parameters, we focus on
lenses aligned generally on the Einstein scale for which multiple lensed images
may not form in the case of an extended lens. In this case, diffraction induces
amplitude and phase modulations whose sizes -- are small
enough so that standard matched filtering with unlensed waveforms do not
degrade, but are still detectable for events with high signal-to-noise ratio.
We develop and test an agnostic detection method based on dynamic programming,
which does not require a detailed model of the lensed waveforms. For
pseudo-Jaffe lenses aligned up to the Einstein radius, we demonstrate that a
pair of fully upgraded aLIGO/Virgo detectors can extract diffraction imprints
from binary black hole mergers out to --. The prospect will
improve dramatically for a third-generation detector for which binary black
hole mergers out to -- will all become valuable sources.Comment: 14 pages including references; 8 figures; comments are welcom
Gravitational lensing of gravitational waves: A statistical perspective
In this paper, we study the strong gravitational lensing of gravitational
waves (GWs) from a statistical perspective, with particular focus on the high
frequency GWs from stellar binary black hole coalescences. These are most
promising targets for ground-based detectors such as Advanced Laser
Interferometer Gravitational Wave Observatory (aLIGO) and the proposed Einstein
Telescope (ET) and can be safely treated under the geometrical optics limit for
GW propagation. We perform a thorough calculation of the lensing rate, by
taking account of effects caused by the ellipticity of lensing galaxies, lens
environments, and magnification bias. We find that in certain GW source rate
scenarios, we should be able to observe strongly lensed GW events once per year
() in the aLIGO survey at its design sensitivity; for the
proposed ET survey, the rate could be as high as . These
results depend on the estimate of GW source abundance, and hence can be
correspondingly modified with an improvement in our understanding of the merger
rate of stellar binary black holes. We also compute the fraction of four-image
lens systems in each survey, predicting it to be per cent for the
aLIGO survey and per cent for the ET survey. Finally, we evaluate the
possibility of missing some images due to the finite survey duration, by
presenting the probability distribution of lensing time delays. We predict that
this selection bias will be insignificant in future GW surveys, as most of the
lens systems ( per cent) will have time delays less than month,
which will be far shorter than survey durations.Comment: 10 pages, 5 figures, 1 table. Revised to match version published in
MNRA
Interplay between Chiral Charge Density Wave and Superconductivity in Kagome Superconductors: A Self-consistent Theoretical Analysis
Inspired by the recent discovery of a successive evolutions of electronically
ordered states, we present a self-consistent theoretical analysis that treats
the interactions responsible for the chiral charge order and superconductivity
on an equal footing. It is revealed that the self-consistent theory captures
the essential features of the successive temperature evolutions of the
electronic states from the high-temperature ``triple-"
charge-density-wave state to the nematic charge-density-wave phase, and finally
to the low-temperature superconducting state coexisting with the nematic charge
density wave. We provide a comprehensive explanation for the temperature
evolutions of the charge ordered states and discuss the consequences of the
intertwining of the superconductivity with the nematic charge density wave. Our
findings not only account for the successive temperature evolutions of the
ordered electronic states discovered in experiments but also provide a natural
explanation for the two-fold rotational symmetry observed in both the
charge-density-wave and superconducting states. Moreover, the intertwining of
the superconductivity with the nematic charge density wave order may also be an
advisable candidate to reconcile the divergent or seemingly contradictory
experimental outcomes regarding the superconducting properties
Systemically administered liposome-encapsulated Ad-PEDF potentiates the anti-cancer effects in mouse lung metastasis melanoma
BACKGROUND: The use of adenoviral vector for gene therapy is still an important strategy for advanced cancers, however, the lack of the requisite coxsackie-adenovirus receptor in cancer cells and host immune response to adenovirus limit the application of adenoviral vector in vivo. METHOD: We designed the antiangiogenic gene therapy with recombinant PEDF adenovirus (Ad-PEDF) encapsulated in cationic liposome (Ad-PEDF/Liposome), and investigated the anti-tumor efficacy of Ad-PEDF/Liposome complex on inhibition of tumor metastasis. RESULTS: We found that systemic administration of Ad-PEDF/liposome was well tolerated and resulted in marked suppression of tumor growth, and was more potent than uncoated Ad-PEDF to induce apoptosis in B16-F10 melanoma cells and inhibit murine pulmonary metastases in vivo. After Ad-luciferase was encapsulated with liposome, its distribution decreased in liver and increased in lung. The anti-Ad IgG level of Ad-PEDF/Liposome was significantly lower than Ad-PEDF used alone. CONCLUSION: The present findings provide evidences of systematic administration of cationic liposome-encapsulated Ad-PEDF in pulmonary metastatic melanoma mice model, and show an encouraging therapeutic effect for further exploration and application of more complexes based on liposome-encapsulated adenovirus for more cancers
Alterations in amino acid levels and metabolite ratio of spinal cord in rat with myocardial ischemia-reperfusion injury by proton magnetic resonance spectroscopy
Abstract
Objectives The mechanism behind spinal metabolites and myocardial ischemia-reperfusion (IR) injury is not well understood. Proton magnetic resonance spectroscopic analysis of spinal cord extracts provides a quick evaluation of the specific metabolic activity in rats with myocardial IR injury. We investigated the relationship between the IR-related variables and the changes in spinal metabolites.
Methods Proton magnetic resonance spectroscopy (1H-MRS) was used to assess the spinal metabolites of adult rats with and without myocardial IR injury (n=6 per group). Myocardial IR injury was reproduced using intermittent occlusion of the left anterior descending coronary artery. We studied the relationship between the metabolite ratio measurement and IR-related variables. All rats underwent 1H-MRS, with the ratio of interest placed in different spinal cord segments to measure levels of twelve metabolites including N-acetylaspartate (NAA), taurine (Tau),glutamate (Glu),gamma amino acid butyric acid (GABA),creatine (Cr), and myoinositol (MI), etc.
Results Rats with myocardial IR injury had higher concentration of Tau in the upper thoracic spinal cord (p< 0.05), and lower concentration of Gly and Glu in the cervical segment of the spinal cord (p< 0.05), when compared to the Control group. The ratios of glutamate/taurine (Glu/Tau), Glu/(GABA+Tau) and Glu/Total were significantly different between the IR group and the Control group in the upper thoracic spinal cord (p< 0.05). So were the ratios of Glu/(GABA+Tau) in the cervical segment (p< 0.05),and Glu/Tau and Glu/(GABA+Tau) in the lower thoracic spinal cord (p< 0.05).
Conclusions These findings suggest that myocardial IR injury may be related to spinal biochemical alterations. It is speculated that these observed changes in the levels of spinal metabolites may be involved in the pathogenesis and regulation of myocardial IR injury.
Keywords: myocardial ischemia-reperfusion injury; spinal cord; metabolomics; proton nuclear magnetic resonanc
Comprehensive study of the blazars from Fermi-LAT LCR: The log-normal flux distribution and linear RMS-Flux relation
Fermi-LAT LCR provide continuous and regularly-sampled gamma-ray light
curves, spanning about 14 years, for a large sample of blazars. The log-normal
flux distribution and linear RMS-Flux relation of the light curves for a few of
Fermi blazar have been examined in previous studies. However, the probability
that blazars exhibit log-normal flux distribution and linear RMS-Flux relation
in their gamma-ray light curves has not been systematically explored. In this
study, we comprehensively research on the distribution of gamma-ray flux and
the statistical characteristics on a large sample of 1414 variable blazars from
the Fermi-LAT LCR catalog, including 572 FSRQs, 477 BL Lacs, and 365 BCUs, and
statistically compare their flux distributions with normal and log-normal
distributions. The results indicate that the probability of not reject
log-normal is 42.05% for the large sample, and there is still 2.05% probability
of not reject normality, based on the joint of Kolmogorov-Smirnov, Shapiro-Wilk
and Normality tests. We further find that the probability that BL Lacs conforms
to the log-normal distribution is higher than that of FSRQs. Besides, after
removing sources with less than 200 data points from this large sample, a
sample of 549 blazars, which is still a large sample comparing to the previous
studies, was obtained. Basing on dividing the light curves into segments every
20 points (or 40 points, or one year), we fitted the linear RMS-Flux relation
of this three different sets, and found that the Pearson correlation
coefficients are all close to 1 of the most blazars. This result indicates a
strong linear correlation between the RMS and the flux of this 549 blazars. The
log-normal distribution and linear RMS-Flux relation indicate that the
variability of gamma-ray flux for most blazars is non-linear and multiplicative
process.Comment: 13pages, 5figures, Accepted for publication in RA
Relativistic quantum transport theory of hadronic matter: the coupled nucleon, delta and pion system
We derive the relativistic quantum transport equation for the pion
distribution function based on an effective Lagrangian of the QHD-II model. The
closed time-path Green's function technique, the semi-classical, quasi-particle
and Born approximation are employed in the derivation. Both the mean field and
collision term are derived from the same Lagrangian and presented analytically.
The dynamical equation for the pions is consistent with that for the nucleons
and deltas which we developed before. Thus, we obtain a relativistic transport
model which describes the hadronic matter with , and degrees
of freedom simultaneously. Within this approach, we investigate the medium
effects on the pion dispersion relation as well as the pion absorption and pion
production channels in cold nuclear matter. In contrast to the results of the
non-relativistic model, the pion dispersion relation becomes harder at low
momenta and softer at high momenta as compared to the free one, which is mainly
caused by the relativistic kinetics. The theoretically predicted free cross section is in agreement with the experimental data. Medium
effects on the cross section and momentum-dependent
-decay width are shown to be substantial.Comment: 66 pages, Latex, 12 PostScript figures included; replaced by the
revised version, to appear in Phys. Rev.
CircNet: a database of circular RNAs derived from transcriptome sequencing data
Circular RNAs (circRNAs) represent a new type of regulatory noncoding RNA that only recently has been identified and cataloged. Emerging evidence indicates that circRNAs exert a new layer of post-transcriptional regulation of gene expression. In this study, we utilized transcriptome sequencing datasets to systematically identify the expression of circRNAs (including known and newly identified ones by our pipeline) in 464 RNA-seq samples, and then constructed the CircNet database (http://circnet.mbc.nctu.edu.tw/) that provides the following resources: (i) novel circRNAs, (ii) integrated miRNA-target networks, (iii) expression profiles of circRNA isoforms, (iv) genomic annotations of circRNA isoforms (e.g. 282 948 exon positions), and (v) sequences of circRNA isoforms. The CircNet database is to our knowledge the first public database that provides tissue-specific circRNA expression profiles and circRNA–miRNA-gene regulatory networks. It not only extends the most up to date catalog of circRNAs but also provides a thorough expression analysis of both previously reported and novel circRNAs. Furthermore, it generates an integrated regulatory network that illustrates the regulation between circRNAs, miRNAs and genes
- …