767 research outputs found
Dissecting Small RNA Loading Pathway in \u3cem\u3eDrosophila melanogaster\u3c/em\u3e: A Dissertation
In the preceding chapters, I have discussed my doctoral research on studying the siRNA loading pathway in Drosophila using both biochemical and genetic approaches. We established a gel shift system to identify the intermediate complexes formed during siRNA loading. We detected at least three complexes, named complex B, RISC loading complex (RLC) and RISC. Using kinetic modeling, we determined that the siRNA enters complex B and RLC early during assembly when it remains double-stranded, and then matures in RISC to generate Argonaute bearing only the single-stranded guide. We further characterized the three complexes. We showed that complex B comprises Dcr-1 and Loqs, while both RLC and RISC contain Dcr-2 and R2D2. Our study suggests that the Dcr-2/R2D2 heterodimer plays a central role in RISC assembly. We observed that Dcr-1/Loqs, which function together to process pre-miRNA into mature miRNA, were also involved in siRNA loading. This was surprising, because it has been proposed that the RNAi pathway and miRNA pathway are separate and parallel, with each using a unique set of proteins to produce small RNAs, to assemble functional RNA-guided enzyme complexes, and to regulate target mRNAs. We further examined the molecular function of Dcr-1/Loqs in RNAi pathway. Our data suggest that, in vivo and in vitro, the Dcr-1/Loqs complex binds to siRNA. In vitro, the binding of the Dcr-1/Loqs complex to siRNA is the earliest detectable step in siRNA-triggered Ago2-RISC assembly. Futhermore, the binding of Dcr-1/Loqs to siRNA appears to facilitate dsRNA dicing by Dcr-2/R2D2, because the dicing activity is much lower in loqslysate than in wild type.
Long inverted repeat (IR) triggered white silencing in fly eyes is an example of endogenous RNAi. Consistent with our finding that Dcr-1/Loqs function to load siRNA, less white siRNA accumulates in loqs mutant eyes compared to wild type. As a result, loqs mutants are partially defective in IR trigged whitesilencing. Our data suggest considerable functional and genetic overlap between the miRNA and siRNA pathways, with the two sharing key components previously thought to be confined to just one of the two pathways.
Based on our study on siRNA loading pathway, we also elucidated the molecular function of Armitage (Armi) protein in RNAi. We showed that armi is required for RNAi. Lysates from armi mutant ovaries are defective for RNAi in vitro. Native gel analysis of protein-siRNA complexes suggests that armi mutants support early steps in the RNAi pathway, i.e., the formation of complex B and RLC, but are defective in the production of the RISC
Research on The Issue of Payments in The Cross-Border E-Commerce
Cross-border e-commerce is the combination of “Internet+” International Trade, which shorten the distance between products and market in time and space, and promote trade development. While cross-border payment services play an important role in cross-border e-commerce, once the payment services is not successful, it means we are unable to make a deal, so, it pushes the completion of cross-border e-commerce transactions. This paper researches the concept of cross-border e-commerce and cross-border payment, and develops a model to describe current situation of China’s cross-border payment business, summarizes the domestic and foreign cross-border e-commerce platform to solve cross-border payments service solutions. Finally, we analyze the opportunities and challenges of Xi\u27an city facing e-commerce cross-border payment, and proposes solutions
The Development and Tendency of Cross-Border E-Commerce in China
Recent years witness the rapidly development of cross-border e-commerce in China, which presents as the springing up of the cross-border e-commerce platforms and enterprises. Beginning from analyzing the development of cross-border e-commerce in China, this article introduces the business modes and transaction process of cross-border e-commerce, finds out several problems which are against further development, and predicts the tendency of cross-border E-commerce
Decreasing the uncertainty of atomic clocks via real-time noise distinguish
The environmental perturbation on atoms is the key factor restricting the
performance of atomic frequency standards, especially in long term scale. In
this letter, we demonstrate a real-time noise distinguish operation of atomic
clocks. The operation improves the statistical uncertainty by about an order of
magnitude of our fountain clock which is deteriorated previously by extra
noises. The frequency offset bring by the extra noise is also corrected. The
experiment proves the real-time noise distinguish operation can reduce the
contribution of ambient noises and improve the uncertainty limit of atomic
clocks.Comment: 5 pages, 4 figures, 1 tabl
Revise thermal winds of remnant neutron stars in gamma-ray bursts
It seems that the wealth of information revealed by the multi-messenger
observations of the binary neutron star (NS) merger event, GW170817/GRB
170817A/kilonova AT2017gfo, places irreconcilable constraints to models of the
prompt emission of this gamma-ray burst (GRB). The observed time delay between
the merger of the two NSs and the trigger of the GRB and the thermal tail of
the prompt emission can hardly be reproduced by these models simultaneously. We
argue that the merger remnant should be an NS (last for, at least, a large
fraction of 1s), and that the difficulty can be alleviated by the delayed
formation of the accretion disk due to the absorption of high-energy neutrinos
emitted by the NS and the delayed emergence of an effective viscous in the
disk. Further, we extend the consideration of the effect of the energy
deposition of neutrinos emitted from the NS. If the NS is the central object of
a GRB with a distance and duration similar to that of GRB 170817A, thermal
emission of the thermal bubble inflated by the NS after the termination of
accretion may be detectable. If our scenario is verified, it would be of
interest to investigate the cooling of nascent NSs.Comment: 9 pages, 1 figure, RAA accepte
Research on systemic risk contagion of Chinese financial institutions based on GARCH-VMD-Copula-CoVaR model
With the development of China’s financial market, the risk contagion effect among financial institutions is increasing and becoming more complicated. Few literatures have explored the risk
transmission paths of Chinese financial institutions at different frequencies. In order to make up for the gaps in this research field,
variable mode decomposition (VMD) technology is introduced in
this paper, combined with the Copula-GARCH model to construct
the GARCH-VMD-Copula-CoVaR model, which describes the risk
contagion paths of major financial institutions in the Chinese
financial market at different frequencies (long-term, medium-term
and short-term). The research results show that risk dependence
and contagion between financial institutions have the characteristics of bidirectionality, asymmetry and time-varying in all frequency studies, and there are differences in different frequencies
To investigate the magnetic-field-induced distortion of NSs through GRB X-ray plateaus
Magnetic field may distort neutron stars (NSs), but the effect has not been
robustly tested through gravitational-wave observation yet due to the absence
of a fast rotating Galactic magnetar. The central objects of Gamma-ray bursts
(GRBs) could be millisecond magnetars. Under the magnetar scenario on the X-ray
plateaus of GRB afterglows,the spindown evolution modulated by the
gravitational-wave radiation may be inferred from some special samples, so that
the magnetically-induced distorting can be further estimated. According to two
samples, GRB 060807 and GRB 070521, we found that the correlation between the
effective ellipticity, , and effective dipole magnetic
field strength on a neutron star (NS) surface, , is
.
This result demands that with
being the internal toroidal magnetic field strength of NSs. We suggested that
the torque generated during few unsymmetrical massive-star collapses may induce
differential rotations in proto-NSs to amplify the internal toroidal fields.Comment: 8 pages, 2 figures, RAA submitte
VDIP-TGV: Blind Image Deconvolution via Variational Deep Image Prior Empowered by Total Generalized Variation
Recovering clear images from blurry ones with an unknown blur kernel is a
challenging problem. Deep image prior (DIP) proposes to use the deep network as
a regularizer for a single image rather than as a supervised model, which
achieves encouraging results in the nonblind deblurring problem. However, since
the relationship between images and the network architectures is unclear, it is
hard to find a suitable architecture to provide sufficient constraints on the
estimated blur kernels and clean images. Also, DIP uses the sparse maximum a
posteriori (MAP), which is insufficient to enforce the selection of the
recovery image. Recently, variational deep image prior (VDIP) was proposed to
impose constraints on both blur kernels and recovery images and take the
standard deviation of the image into account during the optimization process by
the variational principle. However, we empirically find that VDIP struggles
with processing image details and tends to generate suboptimal results when the
blur kernel is large. Therefore, we combine total generalized variational (TGV)
regularization with VDIP in this paper to overcome these shortcomings of VDIP.
TGV is a flexible regularization that utilizes the characteristics of partial
derivatives of varying orders to regularize images at different scales,
reducing oil painting artifacts while maintaining sharp edges. The proposed
VDIP-TGV effectively recovers image edges and details by supplementing extra
gradient information through TGV. Additionally, this model is solved by the
alternating direction method of multipliers (ADMM), which effectively combines
traditional algorithms and deep learning methods. Experiments show that our
proposed VDIP-TGV surpasses various state-of-the-art models quantitatively and
qualitatively.Comment: 13 pages, 5 figure
All Labels Together: Low-shot Intent Detection with an Efficient Label Semantic Encoding Paradigm
In intent detection tasks, leveraging meaningful semantic information from
intent labels can be particularly beneficial for few-shot scenarios. However,
existing few-shot intent detection methods either ignore the intent labels,
(e.g. treating intents as indices) or do not fully utilize this information
(e.g. only using part of the intent labels). In this work, we present an
end-to-end One-to-All system that enables the comparison of an input utterance
with all label candidates. The system can then fully utilize label semantics in
this way. Experiments on three few-shot intent detection tasks demonstrate that
One-to-All is especially effective when the training resource is extremely
scarce, achieving state-of-the-art performance in 1-, 3- and 5-shot settings.
Moreover, we present a novel pretraining strategy for our model that utilizes
indirect supervision from paraphrasing, enabling zero-shot cross-domain
generalization on intent detection tasks. Our code is at
https://github.com/jiangshdd/AllLablesTogether.Comment: Accepted by IJCNLP-AACL 202
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