178 research outputs found
Evidence for C II Diffuse Line Emission at Redshift z2.6
C II is one of the brightest emission lines from star-forming galaxies and is an excellent tracer for star formation. Recent work measured the C II emission line amplitude for redshifts 2 < z < 3.2 by cross-correlating Planck High Frequency Instrument emission maps with tracers of overdensity from the Baryon Oscillation Spectroscopic Sky Survey, finding I(CII)=6.6(sup +5.0, sub 4.810(exp 4) Jy/sr at 95per cent confidence level. In this paper, we present a refinement of this earlier work by improving the mask weighting in each of the Planck bands and the precision in the covariance matrix. We report a detection of excess emission in the 545 GHz Planck band separate from the cosmic infrared background (CIB) present in the 353857 GHz Planck bands. This excess is consistent with redshifted C II emission, in which case we report b(CII)I(CII)=2.0(sup +1.2, sub 1.110(exp 5) Jy/sr at 95 per cent confidence level, which strongly favours many collisional excitation models of C II emission. Our detection shows strong evidence for a model with a non-zero C II parameter, though line intensity mapping observations at high spectral resolution will be needed to confirm this result
FIELD EXPERIMENTAL STUDY ON EXTERNAL PRESTRESSING REINFORCEMENT OF A 420M PC CONTINUOUS BEAM BRIDGE
In this paper, the practical engineering of a 420 m PC continuous beam bridge is taken as the research object, and an external prestressing reinforcement method is proposed to reinforce the damaged and cracked girder. The paper is to study the structural performance of PC continuous beam bridge before and after reinforcement. The heavy vehicle loading test of reinforced PC continuous beam bridge was carried out. A total of three test spans were selected, and each test span selected seven deflection test section and a strain test section. The corresponding finite element model was established and verified by the test results. Finally, it was concluded in this study that the external prestressing reinforcement method has a good effect on improving the loading capacity and overall performance of damaged bridges
AOBase: a database for antisense oligonucleotides selection and design
Antisense oligonucleotides (ODNs) technology is one of the important approaches for the sequence-specific knockdown of gene expression. ODNs have been used as research tools in the post-genome era, as well as new types of therapeutic agents. Since finding effective target sites within RNA is a hard work for antisense ODNs design, various experimental methods and computational approaches have been proposed. For better sharing of the experimented and published ODNs, valid and invalid ODNs reported in literatures are screened, collected and stored in AOBase. Till now, ∼700 ODNs against 46 target mRNAs are contained in AOBase. Entries can be explored via TargetSearch and AOSearch web retrieval interfaces. AOBase can not only be useful in ODNs selection for gene function exploration, but also contribute to mining rules and developing algorithms for rational ODNs design. AOBase is freely accessible via
Efficient simulations of ionized ISM emission lines: A detailed comparison between the FIRE high-redshift suite and observations
The Atacama Large Millimeter/Submillimeter Array (ALMA) in the sub-millimeter
and the James Webb Space Telescope (JWST) in the infrared have achieved robust
spectroscopic detections of emission lines from the interstellar medium (ISM)
in some of the first galaxies. These unprecedented measurements provide
valuable information regarding the ISM properties, stellar populations, galaxy
morphologies, and kinematics in these high-redshift galaxies and, in principle,
offer powerful tests of state-of-the-art galaxy formation models, as
implemented in hydrodynamical simulations. To facilitate direct comparisons
between simulations and observations, we develop a fast post-processing
pipeline for predicting the line emission from the HII regions around simulated
star particles, accounting for spatial variations in the surrounding gas
density, metallicity, temperature, and incident radiation spectrum. Our ISM
line emission model currently captures H, H, and all of the
[OIII] and [OII] lines targeted by ALMA and the JWST at . We illustrate
the power of this approach by applying our line emission model to the publicly
available FIRE high- simulation suite and perform a detailed comparison with
current observations. We show that the FIRE mass--metallicity relation is in
agreement with ALMA/JWST measurements after accounting for the
inhomogeneities in ISM properties. We also quantitatively validate the one-zone
model description, which is widely used for interpreting [OIII] and H
line luminosity measurements. This model is publicly available and can be
implemented on top of a broad range of galaxy formation simulations for
comparison with JWST and ALMA measurements.Comment: 15 pages, 13 figure
Selection of antisense oligonucleotides based on multiple predicted target mRNA structures
BACKGROUND: Local structures of target mRNAs play a significant role in determining the efficacies of antisense oligonucleotides (ODNs), but some structure-based target site selection methods are limited by uncertainties in RNA secondary structure prediction. If all the predicted structures of a given mRNA within a certain energy limit could be used simultaneously, target site selection would obviously be improved in both reliability and efficiency. In this study, some key problems in ODN target selection on the basis of multiple predicted target mRNA structures are systematically discussed. RESULTS: Two methods were considered for merging topologically different RNA structures into integrated representations. Several parameters were derived to characterize local target site structures. Statistical analysis on a dataset with 448 ODNs against 28 different mRNAs revealed 9 features quantitatively associated with efficacy. Features of structural consistency seemed to be more highly correlated with efficacy than indices of the proportion of bases in single-stranded or double-stranded regions. The local structures of the target site 5' and 3' termini were also shown to be important in target selection. Neural network efficacy predictors using these features, defined on integrated structures as inputs, performed well in "minus-one-gene" cross-validation experiments. CONCLUSION: Topologically different target mRNA structures can be merged into integrated representations and then used in computer-aided ODN design. The results of this paper imply that some features characterizing multiple predicted target site structures can be used to predict ODN efficacy
A centimeter-scale achromatic hybrid metalens with polarization-insensitivity in the visible
Metalenses, featuring ultra-compactness and CMOS compatibility, are limited
by the compromise between the diameter, numerical aperture, and working
waveband. To address this problem, we propose and numerically demonstrate a
centimeter-scale metasurface-refractive hybrid metalens working in the band of
440 - 700 nm. Revisiting the general Snell law, we present the phase profile of
a chromatic aberration correction metasurface that can apply to a plano-convex
refractive lens of an arbitrary surface type. Simulated by our semi-vector
method, the designed achromatic hybrid metalens achieves 81% chromatic
aberration suppression and polarization insensitivity. Broadband imaging
results of the hybrid metalens are further provided, verifying the achromatism
of the designed hybrid metalens. It can find applications in camera lenses and
other optical systems that need compact, high-performance lenses.Comment: 10 pages, 5 figures
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