99 research outputs found
TDDFT calculations for excitation spectra of solids and superstructures utilizing mGGA
The first principles study plays a very important role in developing new generation of materials, such
as organic semiconductors and long polymer chains, as well as understanding of physical properties of
nanoparticles , inorganic semiconductors and semiconductor alloys. In this work, we start from the Kohn-Sham one-particle equation Schr¨odinger equation and solve it by expanding its eigenfunctions in terms of the linear augmented-slater-type orbits(LASTO) under full potential with the exchange-correlation potential
functional given by meta-generalized gradient approximation(mGGA). Our theoretical results were compared
to WIEN2K’s, and good agreement was obtained. As the application, we apply TDDFT plus mGGA to
calculate optical spectra for bulk solids. The result shows good agreement with experimental data.
III-V ternary alloys AxB1−xC are promising materials for optoelectronic, high-speed electronic and
microwave applications, such as infrared emitting diodes and detectors, high electron mobility transistors,
heterojunction bipolar transistors, quantum-dot lasers, modulators and ultrafast switches. We adopted
the TDDFT theory and the cluster averaging method to compute the spectra of III-V ternary alloys with
arbitrary concentration x. We find great agreement between theoretical and experimental data. The success
of this method is mainly because that we approximate the transition matrix elements by the LDA p-matrix
elements via (mGGA) which contains the singularity of the type fXC,00(q) ∼ 1/q2 as q → 0. Thus, Our
studies provide some insight into the theoretical calculation of optical spectra of semiconductor alloys
Boosting Few-shot 3D Point Cloud Segmentation via Query-Guided Enhancement
Although extensive research has been conducted on 3D point cloud
segmentation, effectively adapting generic models to novel categories remains a
formidable challenge. This paper proposes a novel approach to improve point
cloud few-shot segmentation (PC-FSS) models. Unlike existing PC-FSS methods
that directly utilize categorical information from support prototypes to
recognize novel classes in query samples, our method identifies two critical
aspects that substantially enhance model performance by reducing contextual
gaps between support prototypes and query features. Specifically, we (1) adapt
support background prototypes to match query context while removing extraneous
cues that may obscure foreground and background in query samples, and (2)
holistically rectify support prototypes under the guidance of query features to
emulate the latter having no semantic gap to the query targets. Our proposed
designs are agnostic to the feature extractor, rendering them readily
applicable to any prototype-based methods. The experimental results on S3DIS
and ScanNet demonstrate notable practical benefits, as our approach achieves
significant improvements while still maintaining high efficiency. The code for
our approach is available at
https://github.com/AaronNZH/Boosting-Few-shot-3D-Point-Cloud-Segmentation-via-Query-Guided-EnhancementComment: Accepted to ACM MM 202
A Significant Increase of RNAi Efficiency in Human Cells by the CMV Enhancer with a tRNAlys Promoter
RNA interference (RNAi) is the process of mRNA degradation induced by double-stranded RNA in a sequence-specific manner. Different types of promoters, such as U6, H1, tRNA, and CMV, have been used to control the inhibitory effect of RNAi expression vectors. In the present study, we constructed two shRNA expression vectors, respectively, controlled by tRNAlys
and CMV enhancer-tRNAlys promoters. Compared to the vectors with tRNAlys or U6 promoter, the vector with a CMV enhancer-tRNAlys promoter silenced pokemon more efficiently on both the mRNA and the protein levels. Meanwhile, the silencing of pokemon inhibited the proliferation of MCF7 cells, but the induction of apoptosis of MCF7 cells was not observed. We conclude that the CMV enhancer-tRNAlys promoter may be a powerful tool in driving intracellular expression of shRNA which can efficiently silence targeted gene
Spin Density wave instability in a ferromagnet
Ferromagnetic (FM) and incommensurate spin-density wave (ISDW) states are an
unusual set of competing magnetic orders that are seldom observed in the same
material without application of a polarizing magnetic field. We report, for the
first time, the discovery of an ISDW state that is derived from a FM ground
state through a Fermi surface (FS) instability in FeGa. This was
achieved by combining neutron scattering experiments with first principles
simulations. Neutron diffraction demonstrates that FeGa is in an ISDW
state at intermediate temperatures and that there is a conspicuous re-emergence
of ferromagnetism above 360 K. First principles calculations show that the ISDW
ordering wavevector is in excellent agreement with a prominent nesting
condition in the spin-majority FS demonstrating the discovery of a novel
instability for FM metals; ISDW formation due to Fermi surface nesting in a
spin-polarized Fermi surface.Comment: 6 pages with 4 figures. Supplemental Materials Include
Coupling physical constraints with machine learning for satellite-derived evapotranspiration of the Tibetan Plateau
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