The gaps between the sizes of large clusters in 2D critical percolation

Evidence previously presented by one of the authors (1) suggests strongly that chromospheric activity decreases with age in main sequence stars. This tentative conclusion rests principally upon a comparison of the members of large clusters (Hyades, Praesepe, Pleiades) with non-cluster objects in the general field, including the Sun. It is at least conceivable, however, that cluster and non-cluster stars might differ in some fundamental fashion which could influence the degree of chromospheric activity, and that the observed differences in chromospheric activity would then be attributable to the circumstances of stellar origin rather than to age.

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Triple Fixation For Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100196 ◽

1968 ◽

Vol 26 ◽

pp. 90-91 ◽

Cited By ~ 1

Author(s):

M. A. Hayat

Keyword(s):

Electron Microscopy ◽

Endoplasmic Reticulum ◽

Electron Beam ◽

Plasma Membrane ◽

Myelin Sheath ◽

Good Deal ◽

Granular Structure ◽

Oxidizing Agent ◽

Fixation Technique ◽

Large Clusters

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.

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The interaction of a manganese-oxidising bacterium as part of a biofilm growing on distribution pipe materials

Water Science & Technology ◽

10.2166/wst.2000.0458 ◽

2000 ◽

Vol 41 (4-5) ◽

pp. 295-300 ◽

Cited By ~ 3

Author(s):

F. Murdoch ◽

P.G. Smith

Keyword(s):

Biofilm Formation ◽

Bacterial Activity ◽

Confocal Laser ◽

Pipe Surface ◽

X Ray ◽

Pseudomonas Spp ◽

Eds Analysis ◽

Large Clusters ◽

Pipe Materials ◽

Confocal Laser Microscope

The deposition of manganese within a biofilm growing on the surface of high-density polyethlene (HDPE) and polyvinychloride (PVC) was studied over a period of four months. The manganese rich water used in the study was inoculated with a manganese oxidising Pseudomonas spp. The level of Mn2+ in the water was monitored and was found to decrease as the biofilm formation increased. This was confirmed by energy dispersive X-ray spectroscopy (EDS) analysis which showed the detection of manganese was dependent on the presence of a biofilm. After two months a 100% removal of Mn2+ was observed in all the flasks inoculated by the Pseudomonas spp. and manganese micro-nodules, the formation of which were reported in Murdoch and Smith (1999), were being formed in large clusters across the surfaces of both the HDPE and PVC. The manganese peak area from the EDS spectrum analysis of the micro-nodules was significantly larger than was measured in the biofilm when these micro-nodules were absent. The scanning confocal laser microscope (SCLM) images of three-week samples showed high bacterial activity around areas where manganese micro-nodules were starting to form on the pipe surface.

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EphA2 super-enhancer promotes tumor progression by recruiting FOSL2 and TCF7L2 to activate the target gene EphA2

Cell Death and Disease ◽

10.1038/s41419-021-03538-6 ◽

2021 ◽

Vol 12 (3) ◽

Author(s):

Shuang Cui ◽

Qiong Wu ◽

Ming Liu ◽

Mu Su ◽

ShiYou Liu ◽

...

Keyword(s):

Tumor Progression ◽

Tumor Cells ◽

Target Gene ◽

Super Enhancer ◽

Proliferation And Metastasis ◽

Active Transcription ◽

Hct 116 ◽

Large Clusters

AbstractSuper-enhancers or stretch enhancers (SEs) consist of large clusters of active transcription enhancers which promote the expression of critical genes that define cell identity during development and disease. However, the role of many super-enhancers in tumor cells remains unclear. This study aims to explore the function and mechanism of a new super-enhancer in various tumor cells. A new super-enhancer that exists in a variety of tumors named EphA2-Super-enhancer (EphA2-SE) was found using multiple databases and further identified. CRISPR/Cas9-mediated deletion of EphA2-SE results in the significant downregulation of its target gene EphA2. Mechanistically, we revealed that the core active region of EphA2-SE comprises E1 component enhancer, which recruits TCF7L2 and FOSL2 transcription factors to drive the expression of EphA2, induce cell proliferation and metastasis. Bioinformatics analysis of RNA-seq data and functional experiments in vitro illustrated that EphA2-SE deletion inhibited cell growth and metastasis by blocking PI3K/AKT and Wnt/β-catenin pathway in HeLa, HCT-116 and MCF-7 cells. Overexpression of EphA2 in EphA2-SE−/− clones rescued the effect of EphA2-SE deletion on proliferation and metastasis. Subsequent xenograft animal model revealed that EphA2-SE deletion suppressed tumor proliferation and survival in vivo. Taken together, these findings demonstrate that EphA2-SE plays an oncogenic role and promotes tumor progression in various tumors by recruiting FOSL2 and TCF7L2 to drive the expression of oncogene EphA2.

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On the scaling of fragmentation and energy dissipation in collisions of dust aggregates

Granular Matter ◽

10.1007/s10035-021-01101-w ◽

2021 ◽

Vol 23 (2) ◽

Author(s):

Philipp Umstätter ◽

Herbert M. Urbassek

Keyword(s):

Energy Dissipation ◽

Collision Energy ◽

Velocity Range ◽

Collision Velocity ◽

Granular Mechanics ◽

Extra Factor ◽

Cluster Fragmentation ◽

Silica Clusters ◽

Large Clusters ◽

Small Clusters

Abstract Fragmentation of granular clusters may be studied by experiments and by granular mechanics simulation. When comparing results, it is often assumed that results can be compared when scaled to the same value of $$E/E_{\mathrm{sep}}$$ E / E sep , where E denotes the collision energy and $$E_{\mathrm{sep}}$$ E sep is the energy needed to break every contact in the granular clusters. The ratio $$E/E_{\mathrm{sep}}\propto v^2$$ E / E sep ∝ v 2 depends on the collision velocity v but not on the number of grains per cluster, N. We test this hypothesis using granular-mechanics simulations on silica clusters containing a few thousand grains in the velocity range where fragmentation starts. We find that a good parameter to compare different systems is given by $$E/(N^{\alpha }E_{\mathrm{sep}})$$ E / ( N α E sep ) , where $$\alpha \sim 2/3$$ α ∼ 2 / 3 . The occurrence of the extra factor $$N^{\alpha }$$ N α is caused by energy dissipation during the collision such that large clusters request a higher impact energy for reaching the same level of fragmentation than small clusters. Energy is dissipated during the collision mainly by normal and tangential (sliding) forces between grains. For large values of the viscoelastic friction parameter, we find smaller cluster fragmentation, since fragment velocities are smaller and allow for fragment recombination. Graphic abstract

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A novel bidirectional clustering algorithm based on local density

Scientific Reports ◽

10.1038/s41598-021-93244-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Baicheng Lyu ◽

Wenhua Wu ◽

Zhiqiang Hu

Keyword(s):

Clustering Algorithm ◽

Local Density ◽

Clustering Algorithms ◽

Cluster Number ◽

Denoising Method ◽

Number Of Clusters ◽

Data Points ◽

Cutoff Distance ◽

Large Clusters ◽

Small Clusters

AbstractWith the widely application of cluster analysis, the number of clusters is gradually increasing, as is the difficulty in selecting the judgment indicators of cluster numbers. Also, small clusters are crucial to discovering the extreme characteristics of data samples, but current clustering algorithms focus mainly on analyzing large clusters. In this paper, a bidirectional clustering algorithm based on local density (BCALoD) is proposed. BCALoD establishes the connection between data points based on local density, can automatically determine the number of clusters, is more sensitive to small clusters, and can reduce the adjusted parameters to a minimum. On the basis of the robustness of cluster number to noise, a denoising method suitable for BCALoD is proposed. Different cutoff distance and cutoff density are assigned to each data cluster, which results in improved clustering performance. Clustering ability of BCALoD is verified by randomly generated datasets and city light satellite images.

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Schur complement spectral bounds for large hybrid FETI-DP clusters and huge three-dimensional scalar problems

Journal of Numerical Mathematics ◽

10.1515/jnma-2020-0048 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Zdeněk Dostál ◽

Tomáš Brzobohatý ◽

Oldřich Vlach

Keyword(s):

Condition Number ◽

Three Dimensional ◽

Schur Complement ◽

Decomposition Methods ◽

Stiffness Matrices ◽

Spectral Bounds ◽

Schur Complements ◽

Linear Problems ◽

Primal Method ◽

Large Clusters

Abstract Bounds on the spectrum of Schur complements of subdomain stiffness matrices with respect to the interior variables are key ingredients of the convergence analysis of FETI (finite element tearing and interconnecting) based domain decomposition methods. Here we give bounds on the regular condition number of Schur complements of “floating” clusters arising from the discretization of 3D Laplacian on a cube decomposed into cube subdomains. The results show that the condition number of the cluster defined on a fixed domain decomposed into m × m × m cube subdomains connected by face and optionally edge averages increases proportionally to m. The estimates support scalability of unpreconditioned H-FETI-DP (hybrid FETI dual-primal) method. Though the research is most important for the solution of variational inequalities, the results of numerical experiments indicate that unpreconditioned H-FETI-DP with large clusters can be useful also for the solution of huge linear problems.

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The role of ammonia in sulfuric acid ion induced nucleation

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-2859-2008 ◽

2008 ◽

Vol 8 (11) ◽

pp. 2859-2867 ◽

Cited By ~ 80

Author(s):

I. K. Ortega ◽

T. Kurtén ◽

H. Vehkamäki ◽

M. Kulmala

Keyword(s):

Sulfuric Acid ◽

Quantum Chemical ◽

Local Minimum ◽

Good Accuracy ◽

Energy Surface ◽

Ground Level ◽

Computational Effort ◽

Free Energy Surface ◽

Large Clusters

Abstract. We have developed a new multi-step strategy for quantum chemical calculations on atmospherically relevant cluster structures that makes calculation for large clusters affordable with a good accuracy-to-computational effort ratio. We have applied this strategy to evaluate the relevance of ternary ion induced nucleation; we have also performed calculations for neutral ternary nucleation for comparison. The results for neutral ternary nucleation agree with previous results, and confirm the important role of ammonia in enhancing the growth of sulfuric acid clusters. On the other hand, we have found that ammonia does not enhance the growth of ionic sulfuric acid clusters. The results also confirm that ion-induced nucleation is a barrierless process at high altitudes, but at ground level there exists a barrier due to the presence of a local minimum on the free energy surface.

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