1,805 research outputs found
[2-(Tetrazol-1-yl)acetato-κO]tris(triphenylphosphine-κP)silver(I) monohydrate
The AgI atom in the title compound, [Ag(C3H3N4O2)(C18H15P)3]·H2O, exists in a distorted tetrahedral environment. The uncoordinated water molecule forms only one hydrogen bond to the uncoordinated carbonyl O atom
Stage-Aware Feature Alignment Network for Real-Time Semantic Segmentation of Street Scenes
Over the past few years, deep convolutional neural network-based methods have made great progress in semantic segmentation of street scenes. Some recent methods align feature maps to alleviate the semantic gap between them and achieve high segmentation accuracy. However, they usually adopt the feature alignment modules with the same network configuration in the decoder and thus ignore the different roles of stages of the decoder during feature aggregation, leading to a complex decoder structure. Such a manner greatly affects the inference speed. In this paper, we present a novel Stage-aware Feature Alignment Network (SFANet) based on the encoder-decoder structure for real-time semantic segmentation of street scenes. Specifically, a Stage-aware Feature Alignment module (SFA) is proposed to align and aggregate two adjacent levels of feature maps effectively. In the SFA, by taking into account the unique role of each stage in the decoder, a novel stage-aware Feature Enhancement Block (FEB) is designed to enhance spatial details and contextual information of feature maps from the encoder. In this way, we are able to address the misalignment problem with a very simple and efficient multi-branch decoder structure. Moreover, an auxiliary training strategy is developed to explicitly alleviate the multi-scale object problem without bringing additional computational costs during the inference phase. Experimental results show that the proposed SFANet exhibits a good balance between accuracy and speed for real-time semantic segmentation of street scenes. In particular, based on ResNet-18, SFANet respectively obtains 78.1% and 74.7% mean of class-wise Intersection-over-Union (mIoU) at inference speeds of 37 FPS and 96 FPS on the challenging Cityscapes and CamVid test datasets by using only a single GTX 1080Ti GPU
Observation of the chiral anomaly induced negative magneto-resistance in 3D Weyl semi-metal TaAs
Weyl semi-metal is the three dimensional analog of graphene. According to the
quantum field theory, the appearance of Weyl points near the Fermi level will
cause novel transport phenomena related to chiral anomaly. In the present
paper, we report the first experimental evidence for the long-anticipated
negative magneto-resistance generated by the chiral anomaly in a newly
predicted time-reversal invariant Weyl semi-metal material TaAs. Clear
Shubnikov de Haas oscillations (SdH) have been detected starting from very weak
magnetic field. Analysis of the SdH peaks gives the Berry phase accumulated
along the cyclotron orbits to be {\pi}, indicating the existence of Weyl
points.Comment: Submitted in February'1
The evolutionary paths towards complexity: a metabolic perspective
As sessile organisms, land plants have exploited their metabolic systems to produce a panoply of structurally and functionally diverse natural chemicals and polymers to adapt to challenging ecosystems. Many of these core and specialized metabolites confer chemical shields against a multitude of abiotic stresses, while others play important roles in plants' interactions with their biotic environments. Plant specialized metabolites can be viewed as complex traits in the sense that the biosynthesis of these molecules typically requires multistep metabolic pathways comprising numerous specific enzymes belonging to diverse protein fold families. Resolving the evolutionary trajectories underlying the emergence of these specialized metabolic pathways will impact a fundamental question in biology – how do complex traits evolve in a Darwinian fashion? Here, I discuss several general patterns observed in rapidly evolving specialized metabolic systems in plants, and surmise mechanistic features at enzyme, pathway and organismal levels that rationalize the remarkable malleability of these systems through stepwise evolution. Future studies, focused on fine sampling of metabolic enzymes and pathways in phylogenetically related plant species, or employing directed evolution strategies in synthetic systems, will significantly broaden our perspective on how biological complexity arises at the metabolic level.Howard Hughes Medical InstitutePioneer Foundation (Postdoctoral Fellowship
A Pseudo DNA Cryptography Method
The DNA cryptography is a new and very promising direction in cryptography
research. DNA can be used in cryptography for storing and transmitting the
information, as well as for computation. Although in its primitive stage, DNA
cryptography is shown to be very effective. Currently, several DNA computing
algorithms are proposed for quite some cryptography, cryptanalysis and
steganography problems, and they are very powerful in these areas. However, the
use of the DNA as a means of cryptography has high tech lab requirements and
computational limitations, as well as the labor intensive extrapolation means
so far. These make the efficient use of DNA cryptography difficult in the
security world now. Therefore, more theoretical analysis should be performed
before its real applications.
In this project, We do not intended to utilize real DNA to perform the
cryptography process; rather, We will introduce a new cryptography method based
on central dogma of molecular biology. Since this method simulates some
critical processes in central dogma, it is a pseudo DNA cryptography method.
The theoretical analysis and experiments show this method to be efficient in
computation, storage and transmission; and it is very powerful against certain
attacks. Thus, this method can be of many uses in cryptography, such as an
enhancement insecurity and speed to the other cryptography methods. There are
also extensions and variations to this method, which have enhanced security,
effectiveness and applicability.Comment: A small work that quite some people asked abou
The antitumor activity of umbelliferone in human renal cell carcinoma via regulation of the p110γ catalytic subunit of PI3Kγ
Umbelliferone exhibits extensive pharmacological activity, including anti-immunomodulatory, anti-inflammatory and antigenotoxicity activities. However, its antitumor properties still remain unclear in human renal cell carcinoma (RCC) cells. Our results have revealed that treatment of human RCC cells (786-O, OS-RC-2, and ACHN) with umbelliferone reduced cell proliferation in a concentration-dependent manner and induced dose-dependent apoptotic events. In addition, cell cycle analysis determined that umbelliferone treatment induced cell cycle arrest in the G1 phase in a dose-dependent manner. Furthermore, western blotting analysis showed a dose-dependent decrease in Ki67, MCM2, Bcl-2, CDK2, CyclinE1, CDK4, and CyclinD1 and a dose-dependent increase in Bax in RCC cells cultured with umbelliferone. Similarly, umbelliferone exhibited a dose-dependent reduction of p110γ when using western blotting analyses. Taken together, these results provide an insight into the pharmacology regarding the potential application of umbelliferone, which contributes to cell death by decreasing p110γ protein expression
Research and experimental verification on low-frequency long-range underwater sound propagation dispersion characteristics under dual-channel sound speed profiles in the Chukchi Plateau
The dual-channel sound speed profiles of the Chukchi Plateau and the Canadian
Basin have become current research hotspots due to their excellent
low-frequency sound signal propagation ability. Previous research has mainly
focused on using sound propagation theory to explain the changes in sound
signal energy. This article is mainly based on the theory of normal modes to
study the fine structure of low-frequency wide-band sound propagation
dispersion under dual-channel sound speed profiles. In this paper, the problem
of the intersection of normal mode dispersion curves caused by the dual-channel
sound speed profile (SSP) has been explained, the blocking effect of seabed
terrain changes on dispersion structures has been analyzed, and the normal
modes has been separated by using modified warping operator. The above research
results have been verified through a long-range seismic exploration experiment
at the Chukchi Plateau. At the same time, based on the acoustic signal
characteristics in this environment, two methods for estimating the distance of
sound sources have been proposed, and the experiment data at sea has also
verified these two methods.Comment: 30 pages, 18 figure
Norcantharidin induces G2/M arrest and apoptosis via activation of ERK and JNK, but not p38 signaling in human renal cell carcinoma ACHN cells
Renal cell carcinoma (RCC) is generally acknowledged as the most resistant primary malignancy unresponsive to conventional radiotherapy and chemotherapy treatments. Norcantharidin (NCTD), a therapeutic compound derived from medicinal plants, has been shown to trigger apoptosis, as well as antimetastatic and antioxidant activities in several tumor cells. However, NCTD’s mechanism of antitumor activity in the RCC cell line remains unclear. In this study, we report that NCTD led to a time- and dose-dependent inhibition of cell proliferation. It had also markedly induced apoptosis and G2/M phase cell cycle arrest in a dose-dependent manner by decreasing the expressions of pro-caspase-3, pro-caspase-9, cyclin B1, and pCDC25C while increasing active caspase-3, cleaved-PARP, P21, and pCDC2 levels. Interestingly, NCTD treatment provoked the phosphorylation of extracellular-regulated protein kinase (ERK) and c-Jun-N-terminal kinase (JNK), but not of p38 MAPK. Moreover, SCH772984 and SP600125, ERK and JNK inhibitors, respectively, could partially abolish NCTD-induced apoptosis and G2/M phase cell cycle arrest. Collectively, these findings suggest that NCTD might activate JNK and ERK signaling pathways, consequently inducing apoptosis and G2/M arrest through the modulation of related proteins. This study provided evidence that NCTD is a promising therapeutic drug for the treatment of RCC
Research and experimental verification on low-frequency long-range sound propagation characteristics under ice-covered and range-dependent marine environment in the Arctic
At present, research on sound propagation under the Arctic ice mainly focuses
on modeling and experimental verification of sound propagation under sea ice
cover and unique sound velocity profiles. Among them, the main research object
of concern is sound transmission loss, and this article will delve into the
time-domain waveform and fine dispersion structure of low-frequency broadband
acoustic signals. Firstly, based on the theory of normal modes, this article
derives the horizontal wavenumber expression and warping transformation
operator for refractive normal modes in the Arctic deep-sea environment.
Subsequently, based on measured ocean environmental parameters and sound field
simulation calculations, this article studied the general laws of low-frequency
long-range sound propagation signals in the Arctic deep-sea environment, and
elucidated the impact mechanism of environmental factors such as seabed terrain
changes, horizontal changes in sound velocity profiles (SSPs), and sea ice
cover on low-frequency long-range sound propagation in the Arctic. This article
validates the above research viewpoint through a sound propagation experiment
conducted in the Arctic with a propagation distance exceeding 1000km. The
marine environment of this experiment has obvious horizontal variation
characteristics. At the same time, this article takes the lead in utilizing the
warping transformation of refractive normal waves in the Arctic waters to
achieve single hydrophone based separation of normal waves and extraction of
dispersion structures, which is conducive to future research on underwater
sound source localization and environmental parameter inversion based on
dispersion structures.Comment: 46 pages, 35 figure
- …