82 research outputs found
Integration of Hog Market between China and the United States 2000-2014
This study aims to ascertain the possible existence of integration between the hog markets in China and the United States. Using national monthly data from January 2000 to December 2014, our results indicate that hog prices between China and the U.S. are cointegrated. Such a result suggests no arbitrage between the two markets. We discuss the reasons why such arbitrage abandons; and conclude that it can be postulated the empirical evidence in integrated U.S. soybean prices alongside other factors may contribute to this result
The Tectonics and Volcanism of Venus: New Modes Facilitated by Realistic Crustal Rheology and Intrusive Magmatism
To explain Venus' young surface age and lack of plate tectonics, Venus'
tectonic regime has often been proposed to be either an episodic-lid regime
with global lithospheric overturns, or an equilibrium resurfacing regime with
numerous volcanic and tectonic activities. Here, we use global 2-D
thermochemical convection models with realistic parameters, including rheology
(dislocation creep, diffusion creep, and plastic yielding), an experiment-based
plagioclase (An) crustal rheology, and intrusive magmatism, to
investigate the tectonics and mantle evolution of Venus. We find that surface
tectonics is strongly affected by crustal rheology. With a ''weak''
plagioclase-rheology crust, models exhibit episodic overturns but with
continuously high surface mobility and high distributed surface strain rates
between overturns, leading to a new tectonic regime that we name ''deformable
episodic lid''. On the other hand, olivine-crustal-rheology models exhibit
either standard episodic-lid tectonics, i.e. with mobility that is high during
overturns and near zero between overturns, or stagnant-lid tectonics, i.e. with
near-zero mobility over the entire model time. Also, a combination of
plagioclase crustal rheology and dislocation creep can weaken the lithosphere
sufficiently to facilitate lithospheric overturns without applying plastic
yielding. Internally, the composition-dependent density profile results in a
''basalt barrier'' at the mantle transition zone, which strongly affects Venus'
mantle evolution. Only strong plumes can penetrate this basalt barrier and
cause global lithospheric overturns. This basalt barrier also causes global
internal episodic overturns that generate global volcanic resurfacing in
stagnant-lid models, which suggests a new resurfacing mechanism (we name it
''stagnant episodic-volcanic-resurfacing'') that does not involve lithospheric
overturns.Comment: Minor changes to previous version. Accepted by Icarus. Main text 54
pages, 17 figures, abstract abbreviate
Co2N nanoparticles embedded N-doped mesoporous carbon as efficient electrocatalysts for oxygen reduction reaction
Co-N-C electrocatalysts have attracted great attention in electrocatalytic ORR (oxygen reduction reaction) field. In this work, we propose to prepare Co 2 N nanoparticles embedded N-doped mesoporous carbon by a facile method including in situ copolymerization and pyrolysis under NH 3 atmosphere. The results show that more N atoms can be doped in carbon framework by NH 3 pyrolysis, it is also found that pyrolysis temperature and Co content can influence the ORR performance of samples. The sample prepared by adding Co precursor and pyrolysis at 700 °C has high N content (11.86 at.%) and relative large specific surface area (362 m 2 g −1 ), and it also exhibited superior electrocatalytic ORR performance in terms of E onset (−0.038 V vs. SCE), E 1/2 (−0.126 V vs. SCE) and large current density (5.22 mA cm −2 ). Additionally, the sample also shows better stability and resistance to methanol poisoning than Pt/C catalyst. The synergistic effect of Co-N active centers and hierarchical porous structures contribute the excellent electrocatalytic activity, which are considering as alternative catalysts for ORR in full cells
Hyperspectral Target Detection Based on Low-Rank Background Subspace Learning and Graph Laplacian Regularization
Hyperspectral target detection is good at finding dim and small objects based
on spectral characteristics. However, existing representation-based methods are
hindered by the problem of the unknown background dictionary and insufficient
utilization of spatial information. To address these issues, this paper
proposes an efficient optimizing approach based on low-rank representation
(LRR) and graph Laplacian regularization (GLR). Firstly, to obtain a complete
and pure background dictionary, we propose a LRR-based background subspace
learning method by jointly mining the low-dimensional structure of all pixels.
Secondly, to fully exploit local spatial relationships and capture the
underlying geometric structure, a local region-based GLR is employed to
estimate the coefficients. Finally, the desired detection map is generated by
computing the ratio of representation errors from binary hypothesis testing.
The experiments conducted on two benchmark datasets validate the effectiveness
and superiority of the approach. For reproduction, the accompanying code is
available at https://github.com/shendb2022/LRBSL-GLR.Comment: 4 pages, 3 figures, 1 tabl
Degeneration-Tuning: Using Scrambled Grid shield Unwanted Concepts from Stable Diffusion
Owing to the unrestricted nature of the content in the training data, large
text-to-image diffusion models, such as Stable Diffusion (SD), are capable of
generating images with potentially copyrighted or dangerous content based on
corresponding textual concepts information. This includes specific intellectual
property (IP), human faces, and various artistic styles. However, Negative
Prompt, a widely used method for content removal, frequently fails to conceal
this content due to inherent limitations in its inference logic. In this work,
we propose a novel strategy named \textbf{Degeneration-Tuning (DT)} to shield
contents of unwanted concepts from SD weights. By utilizing Scrambled Grid to
reconstruct the correlation between undesired concepts and their corresponding
image domain, we guide SD to generate meaningless content when such textual
concepts are provided as input. As this adaptation occurs at the level of the
model's weights, the SD, after DT, can be grafted onto other conditional
diffusion frameworks like ControlNet to shield unwanted concepts. In addition
to qualitatively showcasing the effectiveness of our DT method in protecting
various types of concepts, a quantitative comparison of the SD before and after
DT indicates that the DT method does not significantly impact the generative
quality of other contents. The FID and IS scores of the model on COCO-30K
exhibit only minor changes after DT, shifting from 12.61 and 39.20 to 13.04 and
38.25, respectively, which clearly outperforms the previous methods
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Characteristics and ecological risk assessment of polycyclic aromatic hydrocarbons in soil seepage water in karst terrains, southwest China
Concentrations of polycyclic aromatic hydrocarbons (PAHs) in soils and soil seepage waters were analyzed along with dissolved organic carbon (DOC) to investigate the ecological risks and factors controlling the subsurface transport of PAHs in karst terrain in southwest China. The concentrations of dissolved PAHs in soil seepage water increased with depth and the mean concentrations at a depth of 80 cm were relatively high (exceeding 1147 ng/L). PAH composition in soil seepage water was dominated by low molecular weight (LMW) PAHs, whereas those associated with soil matrix were dominated by high molecular weight (HMW) PAHs. The results revealed that HMW PAHs in soil seepage water were closer to the equilibrium of dissolution than LMW and medium molecular weight (MMW) PAHs. However, due to the carrier functions of dissolved organic matter (DOM) for HMW PAHs, all PAHs can be continuously dissolved in the soil seepage water from soil matrix as the water moved vertical downward through the profiles. During this process, dynamic sorption and desorption processes were occurring between constituents in the soil seepage water and the soil matrix. This study demonstrates soil seepage water has posed a high risk to the groundwater, and effective protection is urgently needed
Radiated tumor cell-derived microparticles effectively kill stem-like tumor cells by increasing reactive oxygen species
Stem-like tumor cells (SLTCs) are thought to be the cellular entity responsible for clinical recurrence and subsequent metastasis. Inhibiting or killing SLTCs can effectively reduce recurrence and metastasis, yet little has been done to clear SLTCs because they are usually resistant to chemotherapy, radiotherapy, and even immunotherapy. In this study, we established SLTCs by low-serum culture and confirmed that the low-serum-cultured tumor cells were in a quiescent state and resistant to chemotherapy, showing features of SLTCs, consistent with the reported data. We demonstrated that SLTCs had high levels of reactive oxygen species (ROS). Based on the finding that radiated tumor cell-derived microparticles (RT-MPs) contained ROS, we used RT-MPs to kill SLTCs. We found that RT-MPs could further increase ROS levels and kill SLTCs in vivo and in vitro partially by ROS carried by the RT-MPs themselves, providing a new method for eliminating SLTCs
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