2,145 research outputs found
Partition Function Expansion on Region-Graphs and Message-Passing Equations
Disordered and frustrated graphical systems are ubiquitous in physics,
biology, and information science. For models on complete graphs or random
graphs, deep understanding has been achieved through the mean-field replica and
cavity methods. But finite-dimensional `real' systems persist to be very
challenging because of the abundance of short loops and strong local
correlations. A statistical mechanics theory is constructed in this paper for
finite-dimensional models based on the mathematical framework of partition
function expansion and the concept of region-graphs. Rigorous expressions for
the free energy and grand free energy are derived. Message-passing equations on
the region-graph, such as belief-propagation and survey-propagation, are also
derived rigorously.Comment: 10 pages including two figures. New theoretical and numerical results
added. Will be published by JSTAT as a lette
Perturbation bounds for constrained and weighted least squares problems
AbstractWe derive perturbation bounds for the constrained and weighted linear least squares (LS) problems. Both the full rank and rank-deficient cases are considered. The analysis generalizes some results of earlier works
Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution
We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction.L. F. Liu acknowledges the financial support by the FCT Investigator grant (IF/01595/2014)
Quantum theory of light diffraction
At present, the theory of light diffraction only has the simple wave-optical
approach. In this paper, we study light diffraction with the approach of
relativistic quantum theory. We find that the slit length, slit width, slit
thickness and wave-length of light have affected to the diffraction intensity
and form of diffraction pattern. However, the effect of slit thickness on the
diffraction pattern can not be explained by wave-optical approach, and it can
be explained in quantum theory. We compare the theoretical results with single
and multiple slits experiment data, and find the theoretical results are
accordance with the experiment data. Otherwise, we give some theory prediction.
We think all the new prediction will be tested by the light diffraction
experiment.Comment: 10 page
Sulfadiazine Sodium Ameliorates the Metabolomic Perturbation in Mice Infected with Toxoplasma gondii
In this study, we analyzed the global metabolomic changes associated with Toxoplasma gondii infection in mice in the presence or absence of sulfadiazine sodium (SDZ) treatment. BALB/c mice were infected with T. gondii GT1 strain and treated orally with SDZ (250 g/ml in water) for 12 consecutive days. Mice showed typical manifestations of illness at 20 days postinfection (dpi); by 30 dpi, 20% had survived and developed latent infection. We used ultraperformance liquid chromatography-mass spectrometry to profile the serum metabolomes in control (untreated and uninfected) mice, acutely infected mice, and SDZ-treated and infected mice. Infection induced significant perturbations in the metabolism of-linolenic acid, purine, pyrimidine, arginine, tryptophan, valine, glycerophospholipids, and fatty acyls. However, treatment with SDZ seemed to alleviate the serum metabolic alterations caused by infection. The restoration of the serum metabolite levels in the treated mice was associated with better clinical outcomes. These data indicate that untargeted metabolomics can reveal biochemical pathways associated with restoration of the metabolic status of T. gondii-infected mice following SDZ treatment and could be used to monitor responses to SDZ treatment. This study provides a new systems approach to elucidate the metabolic and therapeutic effects of SDZ in the context of murine toxoplasmosis. K E Y W O R D S Toxoplasma gondii, biomarkers, metabolomics, mice, serum metabolites, sulfadiazine sodium Toxoplasma gondii, an obligate intracellular protozoan parasite, is highly prevalent in warm-blooded animals and humans (1). T. gondii comprises three clonal lineages (type I, type II, and type III) (2). Despite 98% genetic similarity, dramatic differences in virulence exist among strains belonging to these T. gondii genotypes (3). Humans acquire infection mainly by ingesting undercooked meat containing tissue cysts or oocysts from contaminated water (4). Acute infection with this parasite is mediated by the aggressive, fast-replicating, tachyzoite stage, which can cause encephalitis or retinochoroiditis. In addition, reactivation of the latent form (i.e., bradyzoites-containing cysts) of T. gondii can cause life-threatening conditions and even death in immuno-compromised individuals (5)
Control of a Point Absorber using Reinforcement Learning
This work presents the application of reinforcement
learning for the optimal resistive control of a point absorber.
The model-free Q-learning algorithm is selected in order to
maximise energy absorption in each sea state. Step changes are
made to the controller damping, observing the associated penalty,
for excessive motions, or reward, i.e. gain in associated power.
Due to the general periodicity of gravity waves, the absorbed
power is averaged over a time horizon lasting several wave
periods. The performance of the algorithm is assessed through
the numerical simulation of a point absorber subject to motions
in heave in both regular and irregular waves. The algorithm is
found to converge towards the optimal controller damping in
each sea state. Additionally, the model-free approach ensures the
algorithm can adapt to changes to the device hydrodynamics over
time and is unbiased by modelling errors.The authors would like to thank the Energy Technology
Institute and the Research Council Energy Programme for
funding this research as part of the IDCORE programme
(grant EP/J500847) as well as the Engineering and Physical
Sciences Research Council (grant EP/J500847/1). In addition,
Mr. Anderlini would like to thank Wave Energy Scotland for
sponsoring his Eng.D. research project
Interactions among Lung Cancer Cells, Fibroblasts, and Macrophages in 3D Co-Cultures and the Impact on MMP-1 and VEGF Expression
In vitro cell-based models of lung cancer are frequently employed to study invasion and the mechanisms behind metastasis. However, these models often study only one cell type with two-dimensional (2D) monolayer cell cultures, which do not accurately reflect the complexity of inflammation in vivo. Here, a three-dimensional (3D) cell co-culture collagen gel model was employed, containing human lung adenocarcinoma cells (HCC), human lung fibroblast cells (MRC-5), and macrophages. Cell culture media and cell images were collected, and matrix metalloproteinase-1 (MMP-1) and vascular endothelial growth factor (VEGF) production was monitored under different cell culture conditions. We found that simulating hypoxia and/or serum starvation conditions induced elevated secretion of VEGF in the 3D co-culture model in vitro, but not MMP-1;the morphology of HCC in the 2D versus the 3D co-culture system was extremely different. MMP-1 and VEGF were secreted at higher levels in mixed cell groups rather than mono-culture groups. Therefore, incorporating lung cancer cells, fibroblasts, and macrophages may better reflect physiological metastasis mechanisms compared to mono-culture systems. Tumour stromal cells, macrophages, and fibroblast cells may promote invasion and metastasis, which also provides a new direction for the design of therapies targeted at destroying the stroma of tumor tissues
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