3,148 research outputs found
Generalized Competing Glauber-type Dynamics and Kawasaki-type Dynamics
In this article, we have given a systematic formulation of the new
generalized competing mechanism: the Glauber-type single-spin transition
mechanism, with probability p, simulates the contact of the system with the
heat bath, and the Kawasaki-type spin-pair redistribution mechanism, with
probability 1-p, simulates an external energy flux. These two mechanisms are
natural generalizations of Glauber's single-spin flipping mechanism and
Kawasaki's spin-pair exchange mechanism respectively. On the one hand, the new
mechanism is in principle applicable to arbitrary systems, while on the other
hand, our formulation is able to contain a mechanism that just directly
combines single-spin flipping and spin-pair exchange in their original form.
Compared with the conventional mechanism, the new mechanism does not assume the
simplified version and leads to greater influence of temperature. The fact,
order for lower temperature and disorder for higher temperature, will be
universally true. In order to exemplify this difference, we applied the
mechanism to 1D Ising model and obtained analytical results. We also applied
this mechanism to kinetic Gaussian model and found that, above the critical
point there will be only paramagnetic phase, while below the critical point,
the self-organization as a result of the energy flux will lead the system to an
interesting heterophase, instead of the initially guessed antiferromagnetic
phase. We studied this process in details.Comment: 11 pages,1 figure
Calycosin regulates glucocorticoid-induced apoptosis via Nrf2/ARE signaling in MC3T3-E1 cells
Purpose: To determine the anti-osteoporotic effect of calycosin (CA) and investigate the mechanism involved.Methods: To establish a cell model of osteoporosis, MC3T3-E1 cells were treated with dexamethasone (DEX). Subsequently, the levels of accumulated reactive oxygen species (ROS) and subsequent apoptotic cell death (using flow cytometry) were determined. Relevant mRNA and protein expression levels were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunoblot respectively.Results: CA reduced the apoptosis and accumulation of ROS in DEX-treated cells. DEX induced the expression of caspase-3/-8/-9 in the cleavage of poly ADP-ribose polymerase (PARP), whereas CA treatment decreased expression levels of caspase-3/-8/-9 and PARP. In addition, DEX treatment significantly suppressed the expression of nuclear factor-erythroid 2-related factor 2 (Nrf2) as well as its downstream targets, viz, heme oxygenase-1 and quinone oxidoreductase-1. Interestingly, CA treatment reversed this suppressive effect. It was also found that Nrf2 small interfering RNA effectively inhibited the protective effects of CA against DEX-induced ROS overproduction as well as apoptosis.Conclusion: CA attenuates the cytotoxicity of DEX via inhibition of the generation of ROS and promotion of Nrf2 expression. These findings offer novel insights into a molecular approach to the treatment of glucocorticoid-induced osteoporosis via the application of natural compounds.Keywords: Calycosin, Osteoporosis, Nrf2, Antioxidant response elements, Apoptosi
Plasma Generation and Application in a Laser Ablation Pulsed Plasma Thruster
The laser ablation plasma thruster is a novel electric propulsion thruster, which combined the laser ablation and electromagnetic acceleration. In order to investigate the plasma expansion and ionization in the laser ablation plasma thruster, which was difficult to obtain from experiments, the heat conduction model and fluid dynamics model were established. The heat conduction model was established to calculate the target ablation, taking into account temperature-dependent material properties, phase transition, dielectric transition and phase explosion. The fluid dynamics model was used to calculate the plasma properties, taking into account ionization, plasma absorption and shielding. The ablation plasma velocity, temperature and electron number density were predicted by using the numerical method. The calculated results showed that the peak values of ablation plasma velocity, temperature and electron number density fraction were distributed at the front of the plasma plume. Moreover, the discharge characteristics and thrust performance were tested with different charged energy, structural parameters and propellants. The thrust performance was proven to be improved by electromagnetic acceleration
Impact of the Staphylococcus epidermidis LytSR two-component regulatory system on murein hydrolase activity, pyruvate utilization and global transcriptional profile
<p>Abstract</p> <p>Background</p> <p><it>Staphylococcus epidermidis </it>has emerged as one of the most important nosocomial pathogens, mainly because of its ability to colonize implanted biomaterials by forming a biofilm. Extensive studies are focused on the molecular mechanisms involved in biofilm formation. The LytSR two-component regulatory system regulates autolysis and biofilm formation in <it>Staphylococcus aureus</it>. However, the role of LytSR played in <it>S. epidermidis </it>remained unknown.</p> <p>Results</p> <p>In the present study, we demonstrated that <it>lytSR </it>knock-out in <it>S. epidermidis </it>did not alter susceptibility to Triton X-100 induced autolysis. Quantitative murein hydrolase assay indicated that disruption of <it>lytSR </it>in <it>S. epidermidis </it>resulted in decreased activities of extracellular murein hydrolases, although zymogram showed no apparent differences in murein hydrolase patterns between <it>S. epidermidis </it>strain 1457 and its <it>lytSR </it>mutant. Compared to the wild-type counterpart, 1457<it>ΔlytSR</it> produced slightly more biofilm, with significantly decreased dead cells inside. Microarray analysis showed that <it>lytSR </it>mutation affected the transcription of 164 genes (123 genes were upregulated and 41 genes were downregulated). Specifically, genes encoding proteins responsible for protein synthesis, energy metabolism were downregulated, while genes involved in amino acid and nucleotide biosynthesis, amino acid transporters were upregulated. Impaired ability to utilize pyruvate and reduced activity of arginine deiminase was observed in 1457<it>ΔlytSR</it>, which is consistent with the microarray data.</p> <p>Conclusions</p> <p>The preliminary results suggest that in <it>S. epidermidis </it>LytSR two-component system regulates extracellular murein hydrolase activity, bacterial cell death and pyruvate utilization. Based on the microarray data, it appears that <it>lytSR </it>inactivation induces a stringent response. In addition, LytSR may indirectly enhance biofilm formation by altering the metabolic status of the bacteria.</p
CHARACTERISTICS AND KINETICS OF BIOMASS PYLOLYSIS IN A MICRO FLUIDIZED BED REACTOR
A Micro Fluidized Bed Reactor (MFBR) was developed to enable on-line pulse feeding and isothermal differential reaction of particle reactant. Application of the MFBR to biomass pyrolysis demonstrated that the resulting globe kinetics parameters were 11.77 kJ/mol and 1.45 s-1 on the gas release characteristics, respectively
Curricular Object Manipulation in LiDAR-based Object Detection
This paper explores the potential of curriculum learning in LiDAR-based 3D
object detection by proposing a curricular object manipulation (COM) framework.
The framework embeds the curricular training strategy into both the loss design
and the augmentation process. For the loss design, we propose the COMLoss to
dynamically predict object-level difficulties and emphasize objects of
different difficulties based on training stages. On top of the widely-used
augmentation technique called GT-Aug in LiDAR detection tasks, we propose a
novel COMAug strategy which first clusters objects in ground-truth database
based on well-designed heuristics. Group-level difficulties rather than
individual ones are then predicted and updated during training for stable
results. Model performance and generalization capabilities can be improved by
sampling and augmenting progressively more difficult objects into the training
samples. Extensive experiments and ablation studies reveal the superior and
generality of the proposed framework. The code is available at
https://github.com/ZZY816/COM.Comment: Accepted by CVPR 2023. The code is available at
https://github.com/ZZY816/CO
2,6-Dichloro-N-(4-chlorophenyl)benzamide
In the title compound, C13H8Cl3NO, the dihedral angle between the benzene rings is 63.2 (2)°. In the crystal, N—H⋯O hydrogen bonds link the molecules into C(4) chains propagating in [001]. Weak aromatic π–π stacking also occurs [centroid–centroid separations = 3.759 (3) and 3.776 (3) Å]
Field Driven Pairing State Phase Transition in d_x^2-y^2+id_xy-Wave Superconductors
Within the framework of the Ginzburg-Landau theory for
-wave superconductors, we discuss the pairing state phase
transition in the absence of the Zeeman coupling between the Cooper pair
orbital angular momentum and the magnetic field. We find that above a
temperature , the pairing state in a magnetic field is pure
-wave. However, below , the pairing state is
-wave at low fields, and it becomes pure
-wave at higher fields. Between these pairing states there
exists a field driven phase transition . The transition field increases with
decreasing temperature. In the field-temperature phase diagram, the phase
transition line is obtained theoretically by a combined use of a variational
method and the Virial theorem. The analytical result is found to be in good
agreement with numerical simulation results of the Gingzburg-Landau equations.
The validity of the variational method is discussed. The difference to the case
with the Zeeman coupling is discussed, which may be utilized to the detection
of the Zeeman coupling.Comment: 5 pages, 2 figures, submitted to PRB Brief Repor
Molecular states from interactions
In 2019, two new structures and at
the invariant mass spectrum of observed by the LHCb
Collaboration triggers a hot discussion about their inner structure. Although
many works study seem to indicate that these two states are conventional
three-quark states, and might still be
hadronic molecule state, because the mass of and
are close to the threshold. In this work, we
perform a systematical investigation of the possible heavy molecular states
from the interaction of in a one-boson-exchange approach. The
interaction of the system considered is described by the -channel ,
, and mesons exchange. With the one-boson-exchange potentials
obtained, the bound states with different quantum number
configurations are got by solving the non-relativistic Schr\"{o}dinger
equation. Our calculation suggests that recently observed
can be assigned as a -wave molecular state of with
. However, the state cannot be
accommodated in the current -wave molecular picture. The
calculation also favors the existence of a -wave state that can
not be associated with the . The results in this work are
helpful for understanding the high wave molecular states, and future
experimental search for the new molecular states
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