128,299 research outputs found
EVOLUTIONARY ALGORITHMS FOR OVERLAPPING CORRELATION CLUSTERING
Abstract. In Overlapping Correlation Clustering (OCC), a number of objects are assigned to clusters. Two objects in the same cluster have correlated characteristics. As opposed to traditional clustering where objects are assigned to a single cluster, in OCC objects may be assigned to one or more clusters. since an object can have characteristics that are correlated with objects in more than one cluster. In this paper, we present Biased Random-Key Genetic Algorithms for OCC. Computational experiments are presented. 1
Motif Clustering and Overlapping Clustering for Social Network Analysis
Motivated by applications in social network community analysis, we introduce
a new clustering paradigm termed motif clustering. Unlike classical clustering,
motif clustering aims to minimize the number of clustering errors associated
with both edges and certain higher order graph structures (motifs) that
represent "atomic units" of social organizations. Our contributions are
two-fold: We first introduce motif correlation clustering, in which the goal is
to agnostically partition the vertices of a weighted complete graph so that
certain predetermined "important" social subgraphs mostly lie within the same
cluster, while "less relevant" social subgraphs are allowed to lie across
clusters. We then proceed to introduce the notion of motif covers, in which the
goal is to cover the vertices of motifs via the smallest number of (near)
cliques in the graph. Motif cover algorithms provide a natural solution for
overlapping clustering and they also play an important role in latent feature
inference of networks. For both motif correlation clustering and its extension
introduced via the covering problem, we provide hardness results, algorithmic
solutions and community detection results for two well-studied social networks
Galaxy Clustering at z ~ 2 and Halo Radii
The amplitude of the angular two-point galaxy correlation function w(\theta)
for galaxies at z~2 is estimated for galaxies in the Hubble Deep Field by using
a U < 27 complete sub-sample.
(i) It is confirmed that the amplitude of the correlation can be corrected
for the integral constraint without having to make assumptions about the shape
of the correlation function and by avoiding the introduction of linear error
terms. The estimate using this technique is w(5'') = 0.10 \pm 0.09.
(ii) If the biases introduced in faint galaxy selection due to obscuration by
large objects are not corrected for by masking areas around them, then the
estimate would be w(5'') =0.16\pm 0.07.
(iii) The effective (3-D) galaxy pair separation at 5'' and this redshift
range is ~ 25-250 /h kpc, so the correction to the spatial correlation function
\xi(r) due to exclusion of overlapping galaxy dark matter haloes should be
considered. For clustering stable in proper units in an \Omega=1,\lambda=0
universe, our w(5\arcs) estimate (a) implies a present-day correlation length
of r_0 ~ 2.6^{+1.1}_{-1.7}/h Mpc if halo overlapping is ignored, but (b) for a
present-day correlation length of r_0=5.5/h Mpc implies that a typical halo
exclusion radius is r_halo=70^{+420}_{-30}/h kpc.
(iv) The decreasing correlation period (DCP) of a high initial bias in the
spatial correlation function is not detected at this redshift. For an
\Omega=1,\lambda=0 universe and (proper) stable clustering, possible detections
of the DCP in other work would imply that \xi at redshifts greater than z_t =
1.7\pm0.9 would be [(1+z)/(1+z_t)]^{2.1\pm3.6} times higher than at z_t, which
is consistent with our lack of a detection at z ~ 2.Comment: 17 pages, 13 figures, accepted for MNRAS, additional FITS files with
HDF images available at http://www.iap.fr/users/roukema/xi2
The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: a tomographic analysis of structure growth and expansion rate from anisotropic galaxy clustering
We perform a tomographic analysis of structure growth and expansion rate from
the anisotropic galaxy clustering of the combined sample of Baryon Oscillation
Spectroscopic Survey (BOSS) Data Release 12, which covers the redshift range of
. In order to extract the redshift information of anisotropic
galaxy clustering, we analyse this data set in nine overlapping redshift slices
in configuration space and perform the joint constraints on the parameters
using the correlation function multipoles.
The analysis pipeline is validated using the MultiDark-Patchy mock catalogues.
We obtain a measurement precision of for , for
and for , depending on the
effective redshift of the slices. We report a joint measurement of with the full covariance matrix in nine redshift
slices. We use our joint BAO and RSD measurement combined with external
datasets to constrain the gravitational growth index , and find
, which is consistent with the CDM prediction
within 95\% CL.Comment: 8 pages, 8 figures, 2 tables, accepted for publication MNRAS. The
measured results including the full covariance matrices are made available at
https://github.com/ytcosmo/TomoBAORSD and tomographic clustering data used in
this work is available at https://sdss3.org//science/boss_publications.ph
On the evolution of clustering of 24um-selected galaxies
This paper investigates the clustering properties of a complete sample of
1041 24um-selected sources brighter than F[24um]=400 uJy in the overlapping
region between the SWIRE and UKIDSS UDS surveys. We have concentrated on the
two (photometric) interval ranges z=[0.6-1.2] (low-z sample) and z>1.6 (high-z
sample) as it is in these regions were we expect the mid-IR population to be
dominated by intense dust-enshrouded activity such as star formation and black
hole accretion. Investigations of the angular correlation function produce a
correlation length are r0~15.9 Mpc for the high-z sample and r0~8.5 Mpc for the
low-z one. Comparisons with physical models reveal that the high-z sources are
exclusively associated with very massive (M>~10^{13} M_sun)haloes, comparable
to those which locally host groups-to-clusters of galaxies, and are very common
within such (rare) structures. Conversely, lower-z galaxies are found to reside
in smaller halos (M_min~10^{12} M_sun) and to be very rare in such systems.
While recent studies have determined a strong evolution of the 24um luminosity
function between z~2 and z~0, they cannot provide information on the physical
nature of such an evolution. Our clustering results instead indicate that this
is due to the presence of different populations of objects inhabiting different
structures, as active systems at z<~1.5 are found to be exclusively associated
with low-mass galaxies, while very massive sources appear to have concluded
their active phase before this epoch. Finally, we note that the small-scale
clustering data seem to require steep profiles for the distribution of galaxies
within their halos. This is suggestive of close encounters and/or mergers which
could strongly favour both AGN and star-formation activity.Comment: 13 pages, 8 figures, to appear in MNRA
Correlations in the (Sub)millimeter Background from ACT × BLAST
We present measurements of the auto- and cross-frequency correlation power spectra of the cosmic (sub)millimeter background at 250, 350, and 500 μm (1200, 860, and 600 GHz) from observations made with the Balloon-borne Large Aperture Submillimeter Telescope (BLAST); and at 1380 and 2030 μm (218 and 148 GHz) from observations made with the Atacama Cosmology Telescope (ACT). The overlapping observations cover 8.6 deg^2 in an area relatively free of Galactic dust near the south ecliptic pole. The ACT bands are sensitive to radiation from the cosmic microwave background, to the Sunyaev-Zel'dovich effect from galaxy clusters, and to emission by radio and dusty star-forming galaxies (DSFGs), while the dominant contribution to the BLAST bands is from DSFGs. We confirm and extend the BLAST analysis of clustering with an independent pipeline and also detect correlations between the ACT and BLAST maps at over 25σ significance, which we interpret as a detection of the DSFGs in the ACT maps. In addition to a Poisson component in the cross-frequency power spectra, we detect a clustered signal at 4σ, and using a model for the DSFG evolution and number counts, we successfully fit all of our spectra with a linear clustering model and a bias that depends only on redshift and not on scale. Finally, the data are compared to, and generally agree with, phenomenological models for the DSFG population. This study demonstrates the constraining power of the cross-frequency correlation technique to constrain models for the DSFGs. Similar analyses with more data will impose tight constraints on future models
ModuLand plug-in for Cytoscape: determination of hierarchical layers of overlapping network modules and community centrality
Summary: The ModuLand plug-in provides Cytoscape users an algorithm for
determining extensively overlapping network modules. Moreover, it identifies
several hierarchical layers of modules, where meta-nodes of the higher
hierarchical layer represent modules of the lower layer. The tool assigns
module cores, which predict the function of the whole module, and determines
key nodes bridging two or multiple modules. The plug-in has a detailed
JAVA-based graphical interface with various colouring options. The ModuLand
tool can run on Windows, Linux, or Mac OS. We demonstrate its use on protein
structure and metabolic networks. Availability: The plug-in and its user guide
can be downloaded freely from: http://www.linkgroup.hu/modules.php. Contact:
[email protected] Supplementary information: Supplementary
information is available at Bioinformatics online.Comment: 39 pages, 1 figure and a Supplement with 9 figures and 10 table
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