WorldWideScience

Sample records for 2-pt clustering measurements

  1. Clustering of Sun Exposure Measurements

    DEFF Research Database (Denmark)

    Have, Anna Szynkowiak; Larsen, Jan; Hansen, Lars Kai

    2002-01-01

    Sun-habits exposure and eventually assessing the risk of skin cancer. A general probabilistic framework originally developed for text and Web mining is demonstrated to be useful for clustering of behavioral data. The framework combines principal component subspace projection with probabilistic......In a medically motivated Sun-exposure study, questionnaires concerning Sun-habits were collected from a number of subjects together with UV radiation measurements. This paper focuses on identifying clusters in the heterogeneous set of data for the purpose of understanding possible relations between...

  2. Cluster Tree Based Hybrid Document Similarity Measure

    Directory of Open Access Journals (Sweden)

    M. Varshana Devi

    2015-10-01

    Full Text Available <Cluster tree based hybrid similarity measure is established to measure the hybrid similarity. In cluster tree, the hybrid similarity measure can be calculated for the random data even it may not be the co-occurred and generate different views. Different views of tree can be combined and choose the one which is significant in cost. A method is proposed to combine the multiple views. Multiple views are represented by different distance measures into a single cluster. Comparing the cluster tree based hybrid similarity with the traditional statistical methods it gives the better feasibility for intelligent based search. It helps in improving the dimensionality reduction and semantic analysis.

  3. Measuring the growth of galaxy clusters

    CERN Document Server

    Diaferio, Antonaldo

    2015-01-01

    We suggest how we can use the mass profile of galaxy clusters beyond their virial radius to measure their mass accretion rate, a key prediction of structure formation models. The mass profile can be estimated by applying the caustic technique to dense redshift surveys of clusters and their outskirts, where dynamical equilibrium does not necessarily hold. An additional probe of the mass growth of clusters is their mass fraction in substructures. We show that the caustic technique, that identifies cluster substructures as a by-product, returns catalogs of substructures with mass larger than a few $10^{13}h^{-1}M_\\odot$ that are between 60% and 80% complete, depending on the density of the redshift survey.

  4. Spectral Clustering with Local Projection Distance Measurement

    Directory of Open Access Journals (Sweden)

    Chen Diao

    2015-01-01

    Full Text Available Constructing a rational affinity matrix is crucial for spectral clustering. In this paper, a novel spectral clustering via local projection distance measure (LPDM is proposed. In this method, the Local-Projection-Neighborhood (LPN is defined, which is a region between a pair of data, and other data in the LPN are projected onto the straight line among the data pairs. Utilizing the Euclidean distance between projective points, the local spatial structure of data can be well detected to measure the similarity of objects. Then the affinity matrix can be obtained by using a new similarity measurement, which can squeeze or widen the projective distance with the different spatial structure of data. Experimental results show that the LPDM algorithm can obtain desirable results with high performance on synthetic datasets, real-world datasets, and images.

  5. Syntheses and structural analyses of variable-stoichiometric Au-Pt-Ni carbonyl/phosphine clusters, Pt3(Pt(1-x)Ni(x))(AuPPh3)2(mu2-CO)4(CO)(PPh3)3 and Pt2(Pt(2-y)Ni(y))(AuPPh3)2(mu2-CO)4(CO)2(PPh3)2, with ligation-induced site-specific Pt/Ni substitutional disorder within butterfly-based Pt3(Pt(1-x)Ni(x))Au2 and Pt2(Pt(2-y)Ni(y))Au2 core-geometries.

    Science.gov (United States)

    de Silva, Namal; Nichiporuk, Rita V; Dahl, Lawrence F

    2006-05-21

    In ongoing attempts of directed synthesis of high-nuclearity Au-Pt carbonyl/phosphine clusters with [Ni6(CO)12]2- used as reducing agent and CO source, we have isolated and characterized two new closely related variable-stoichiometric trimetallic clusters, Pt3(Pt(1-x)Ni(x))(AuPPh3)2(mu2-CO)4(CO)(PPh3)3 (1) and Pt2(Pt(2-y)Ni(y))(AuPPh3)2(mu2-CO)4(CO)2(PPh3)2 (2). Their M4Au2 cores may be envisioned as substitutional disordered butterfly-based M4Au2 frameworks (M = Pt/Ni) formed by connections of the two basal M(B) atoms with both (Au-Au)-linked Au(PPh3) moieties. Based upon low-temperature CCD X-ray diffraction studies of eight crystals obtained from different samples, ligation-induced site-specific Pt/Ni substitutional disorder (involving formal insertion of Ni in place of Pt) in a given crystal was found to occur only at the one OC-attached basal M(B) site in 1 or at both OC-attached basal M(B) sites in 2 corresponding to a crystal composite of the Pt3(Pt(1-x)Ni(x))Au2 core in 1 or of the Pt2(Pt(2-y)Ni(y))Au2 core in 2; the Ph3P-attached M(B) site (M(B) = Pt) in 1 and two wingtip M(w) sites (M(w) = Pt) in 1 and 2 were not substitutionally disordered. The resulting variable stoichiometry of the M4Au2 core in 1 may be viewed as a crystal composite of two superimposed individual stereoisomers, Pt4(AuPPh3)2(mu2-CO)4(CO)(PPh3)3 (1a) and Pt3Ni(AuPPh3)2(mu2-CO)4(CO)(PPh3)3 (1b), in the averaged unit cell of a given crystal. Likewise, 2 represents the crystal-averaged composite of three individual stereoisomers, Pt4(AuPPh3)2(mu2-CO)4(CO)2(PPh3)2 (2a), Pt3Ni(AuPPh3)2(mu2-CO)4(CO)2(PPh3)2 (2b), and Pt2Ni2(AuPPh3)2(mu2-CO)4(CO)2(PPh3)2 (2c). Formal Ni substitution for Pt at only the basal M(B) site(s) in the four crystal composites each of 1 and 2 was found to vary widely from 17% to 79% Ni in 1 and from 21% to 95% Ni in 2. Nevertheless, reasonably close Pt/Ni occupancy factors were found within each of the four pairs of composite crystals selected from samples obtained from

  6. Relief of frustration in the Heisenberg pyrochlore antiferromagnet Gd2Pt2O7

    Science.gov (United States)

    Hallas, A. M.; Sharma, A. Z.; Cai, Y.; Munsie, T. J.; Wilson, M. N.; Tachibana, M.; Wiebe, C. R.; Luke, G. M.

    2016-10-01

    The gadolinium pyrochlores Gd2B2O7 are among the best realizations of antiferromagnetically coupled Heisenberg spins on a pyrochlore lattice. We present a magnetic characterization of Gd2Pt2O7 , a unique member of this family. Magnetic susceptibility, heat capacity, and muon spin relaxation measurements show that Gd2Pt2O7 undergoes an antiferromagnetic ordering transition at TN=1.6 K. This transition is strongly first order, as indicated by the sharpness of the heat capacity anomaly, thermal hysteresis in the magnetic susceptibility, and a nondivergent relaxation rate in μ SR . The form of the heat capacity below TN suggests that the ground state is an anisotropic collinear antiferromagnet with an excitation spectrum that is gapped by 0.245(1) meV. The ordering temperature in Gd2Pt2O7,TN=1.6 K, is a substantial 160% increase from other gadolinium pyrochlores, which are all known to order at 1 K or lower. We attribute this enhancement in TN to the B -site cation, platinum. Despite being nonmagnetic, platinum has a filled 5 d t2 g orbital and an empty 5 d eg orbital that can facilitate superexchange. Thus, the magnetic frustration in Gd2Pt2O7 is partially "relieved," thereby promoting magnetic order.

  7. Measurement of cluster-cluster interaction in liquids by deposition and AFM of silicon clusters onto HOPG surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Galinis, Gediminas; Torricelli, Gauthier; Akraiam, Atea; Haeften, Klaus von, E-mail: kvh6@le.ac.uk [University of Leicester, Department of Physics and Astronomy (United Kingdom)

    2012-08-15

    We have investigated the interaction and aggregation of novel fluorescent silicon nanoclusters in liquids by measuring the size distribution of dried clusters on graphite. The clusters were produced by gas aggregation and co-deposition with a beam of water vapour. Drops of the solutions were placed on freshly cleaved highly oriented pyrolitic graphite, subsequently vacuum dried and investigated by atomic force microscopy (AFM) in ultra high vacuum. The AFM images show single clusters and agglomerates. The height distributions are Gaussian-shaped with average heights of 1 nm and widths of 1 nm. The heights never exceed 3 nm. In some regions a second cluster layer is observed. In all samples the separation between first and second layers is larger than the separation between the first layer and the graphite substrate, which we attribute to a stronger interaction between clusters and surface than the cluster self-interaction. We conclude that the separation between first and second layer represents a much better fingerprint of the original size distribution of the clusters in solution than the height of the first layer. The observation of a second cluster layer is important for using silicon clusters as building blocks for cluster-assembled materials.

  8. Selective formation of tetrahedral Pt nanocrystals from K2PtCl6/PVP

    Institute of Scientific and Technical Information of China (English)

    YU Yingtao; XU Boqing

    2003-01-01

    Tetrahedral platinum (Pt) nanocrystals (3-8 nm) are synthesized in high selectivity (ca. 80%) from hydrogen reduction of aqueous K2PtCl6 by using polyvinylpyrrolidone (PVP: Mw≈360000) as a protector. Morphology (TEM) measurements of the metal colloids and UV-Vis absorption of the colloidal solution are employed to monitor the tetrahedron formation during the syntheses with varying K2PtCl6/PVP ratios. The results clearly show a two-stage process for the selective formation of tetrahedral nanocrystals. Rapid nucleation and crystal formation at the early stage result in round-like crystallites and the external facet evolution in thereafter slow crystal growth leads selectively to the formation of the tetrahedrons.

  9. Measuring Gravitational Redshifts in Galaxy Clusters

    CERN Document Server

    Kaiser, Nick

    2013-01-01

    Wojtak {\\it et al} have stacked 7,800 clusters from the SDSS survey in redshift space. They find a small net blue-shift for the cluster galaxies relative to the brightest cluster galaxies, which agrees quite well with the gravitational redshift from GR. Zhao {\\it et al.} have pointed out that, in addition to the gravitational redshift, one would expect to see transverse Doppler (TD) redshifts, and that these two effects are generally of the same order. Here we show that there are other corrections that are also of the same order of magnitude. The fact that we observe galaxies on our past light cone results in a bias such that more of the galaxies observed are moving away from us in the frame of the cluster than are moving towards us. This causes the observed average redshift to be $\\langle \\delta z \\rangle = -\\langle \\Phi \\rangle + \\langle \\beta^2 \\rangle / 2 + \\langle \\beta_x^2 \\rangle$, with $\\beta_x$ is the line of sight velocity. That is if we average over galaxies with equal weight. If the galaxies in ea...

  10. The mass accretion rate of galaxy clusters: a measurable quantity

    CERN Document Server

    De Boni, Cristiano; Diaferio, Antonaldo; Giocoli, Carlo; Baldi, Marco

    2015-01-01

    We explore the possibility of measuring the mass accretion rate of galaxy clusters by using dense galaxy redshift surveys of their outer regions. By approximating the accretion with the infall of a spherical shell, the mass accretion rate only depends on the mass profile of the cluster in a thin shell at radii larger than $R_{200}$. This approximation is rather crude in hierarchical clustering scenarios, where both smooth accretion and aggregation of smaller dark matter haloes contribute to the mass accretion of clusters. Nevertheless, in the redshift range $z=[0,1]$, our prescription returns an average mass accretion rate within $20 \\%$ of the average rate derived with the more realistic merger trees of dark matter haloes extracted from $N$-body simulations. The mass accretion rate of galaxy clusters has been the topic of numerous detailed numerical and theoretical investigations, but so far it has remained inaccessible to measurements in the real Universe. Our result suggests that measuring the mass accreti...

  11. Dynamical Mass Measurements of Contaminated Galaxy Clusters Using Machine Learning

    Science.gov (United States)

    Ntampaka, M.; Trac, H.; Sutherland, D. J.; Fromenteau, S.; Póczos, B.; Schneider, J.

    2016-11-01

    We study dynamical mass measurements of galaxy clusters contaminated by interlopers and show that a modern machine learning algorithm can predict masses by better than a factor of two compared to a standard scaling relation approach. We create two mock catalogs from Multidark’s publicly available N-body MDPL1 simulation, one with perfect galaxy cluster membership information and the other where a simple cylindrical cut around the cluster center allows interlopers to contaminate the clusters. In the standard approach, we use a power-law scaling relation to infer cluster mass from galaxy line-of-sight (LOS) velocity dispersion. Assuming perfect membership knowledge, this unrealistic case produces a wide fractional mass error distribution, with a width of {{Δ }}ε ≈ 0.87. Interlopers introduce additional scatter, significantly widening the error distribution further ({{Δ }}ε ≈ 2.13). We employ the support distribution machine (SDM) class of algorithms to learn from distributions of data to predict single values. Applied to distributions of galaxy observables such as LOS velocity and projected distance from the cluster center, SDM yields better than a factor-of-two improvement ({{Δ }}ε ≈ 0.67) for the contaminated case. Remarkably, SDM applied to contaminated clusters is better able to recover masses than even the scaling relation approach applied to uncontaminated clusters. We show that the SDM method more accurately reproduces the cluster mass function, making it a valuable tool for employing cluster observations to evaluate cosmological models.

  12. Gaussian covariance matrices for anisotropic galaxy clustering measurements

    CERN Document Server

    Grieb, Jan Niklas; Salazar-Albornoz, Salvador; Vecchia, Claudio dalla

    2015-01-01

    Measurements of the redshift-space galaxy clustering have been a prolific source of cosmological information in recent years. In the era of precision cosmology, accurate covariance estimates are an essential step for the validation of galaxy clustering models of the redshift-space two-point statistics. For cases where only a limited set of simulations is available, assessing the data covariance is not possible or only leads to a noisy estimate. Also, relying on simulated realisations of the survey data means that tests of the cosmology dependence of the covariance are expensive. With these two points in mind, this work aims at presenting a simple theoretical model for the linear covariance of anisotropic galaxy clustering observations with synthetic catalogues. Considering the Legendre moments (`multipoles') of the two-point statistics and projections into wide bins of the line-of-sight parameter (`clustering wedges'), we describe the modelling of the covariance for these anisotropic clustering measurements f...

  13. Galaxy cluster scaling relations measured with APEX-SZ

    CERN Document Server

    Bender, A N; Ade, P A R; Basu, K; Bertoldi, F; Burkutean, S; Clarke, J; Dahlin, D; Dobbs, M; Ferrusca, D; Flanigan, D; Halverson, N W; Holzapfel, W L; Horellou, C; Johnson, B R; Kermish, Z D; Klein, M; Kneissl, R; Lanting, T; Lee, A T; Mehl, J; Menten, K M; Muders, D; Nagarajan, A; Pacaud, F; Reichardt, C L; Richards, P L; Schaaf, R; Schwan, D; Sommer, M W; Spieler, H; Tucker, C; Westbrook, B

    2014-01-01

    We present thermal Sunyaev-Zel'dovich effect (SZE) measurements for 42 galaxy clusters observed at 150 GHz with the APEX-SZ experiment. For each cluster, we model the pressure profile and calculate the integrated Comptonization $Y$ to estimate the total thermal energy of the intracluster medium (ICM). We compare the measured $Y$ values to X-ray observables of the ICM from the literature (cluster gas mass $M_{gas}$, temperature $T_X$, and $Y_X =M_{gas}T_X$) that relate to total cluster mass. We measure power law scaling relations, including an intrinsic scatter, between the SZE and X-ray observables for both the X-ray selected and uniform REFLEX-DXL cluster sample and the full ad hoc APEX-SZ sample. We observe that the lack of uniform X-ray analysis for the full cluster sample introduces significant variability into the measured scaling relations and dominates the level of intrinsic scatter. For the REFLEX-DXL sample, we find results consistent with a self-similar model of cluster evolution dominated by gravit...

  14. Measuring the dark energy with quasar clustering

    CERN Document Server

    Calvão, M O; Waga, I

    2002-01-01

    We show, through Monte Carlo simulations, that the Alcock-Pazynski test, as applied to quasar clustering, is a powerful tool to probe the cosmological density and equation of state parameters, Omega_{m0}, Omega_{x0} and w. By taking into account peculiar velocity corrections to the correlation function we obtain, for the Two-Degree Field QSO Redshift Survey (2QZ), the predicted 1\\sigma and 2\\sigma confidence contours. It turns out that the test is competitive with future supernova and galaxy number count ones, besides being complementary to them, for fixed curvature. In particular, we find out that it is especially sensitive to the difference Omega_{m0}-Omega_{Lambda 0}, thus being ideal to combine with CMB results.

  15. Dynamical Mass Measurements of Contaminated Galaxy Clusters Using Machine Learning

    CERN Document Server

    Ntampaka, M; Sutherland, D J; Fromenteau, S; Poczos, B; Schneider, J

    2015-01-01

    We study dynamical mass measurements of galaxy clusters contaminated by interlopers and show that a modern machine learning (ML) algorithm can predict masses by better than a factor of two compared to a standard scaling relation approach. We create two mock catalogs from Multidark's publicly-available N-body MDPL1 simulation, one with perfect galaxy cluster membership information and the other where a simple cylindrical cut around the cluster center allows interlopers to contaminate the clusters. In the standard approach, we use a power law scaling relation to infer cluster mass from galaxy line of sight (LOS) velocity dispersion. Assuming perfect membership knowledge, this unrealistic case produces a wide fractional mass error distribution, with width = 0.87. Interlopers introduce additional scatter, significantly widening the error distribution further (width = 2.13). We employ the Support Distribution Machine (SDM) class of algorithms to learn from distributions of data to predict single values. Applied to...

  16. External Evaluation Measures for Subspace Clustering

    DEFF Research Database (Denmark)

    Günnemann, Stephan; Färber, Ines; Müller, Emmanuel;

    2011-01-01

    Knowledge discovery in databases requires not only development of novel mining techniques but also fair and comparable quality assessment based on objective evaluation measures. Especially in young research areas where no common measures are available, researchers are unable to provide a fair eva...

  17. The 2pt+: an enhanced 2 point correlation function

    CERN Document Server

    Ave, M; Cronin, J; Neto, J R T de Mello; Olinto, A V; Pavlidou, V; Privitera, P; Siffert, B B; Schmidt, F; Venters, T

    2009-01-01

    We introduce a new method for testing departure from isotropy of points on a sphere based on an enhanced form of the two-point correlation function that we named 2pt+. This method uses information from the two extra variables that define the vector between two points on a sphere. We show that this is a powerful method to test departure from isotropy of a distribution of points on a sphere especially when the number of events is small. We apply the method to a few examples in astronomy and discuss the relevance for limited datasets, such as the case of ultra-high energy cosmic rays.

  18. Probing molecular spin clusters by local measurements

    Science.gov (United States)

    Troiani, Filippo; Paris, Matteo G. A.

    2016-09-01

    We address the characterization of molecular nanomagnets at the quantum level and analyze the performance of local measurements in estimating the physical parameters in their spin Hamiltonians. To this aim, we compute key quantities in quantum estimation theory, such as the classical and the quantum Fisher information, in the prototypical case of a heterometallic antiferromagnetic ring. We show that local measurements, performed only on a portion of the molecule, allow a precise estimate of the parameters related to both magnetic defects and avoided level crossings.

  19. Gaussian covariance matrices for anisotropic galaxy clustering measurements

    Science.gov (United States)

    Grieb, Jan Niklas; Sánchez, Ariel G.; Salazar-Albornoz, Salvador; Dalla Vecchia, Claudio

    2016-04-01

    Measurements of the redshift-space galaxy clustering have been a prolific source of cosmological information in recent years. Accurate covariance estimates are an essential step for the validation of galaxy clustering models of the redshift-space two-point statistics. Usually, only a limited set of accurate N-body simulations is available. Thus, assessing the data covariance is not possible or only leads to a noisy estimate. Further, relying on simulated realizations of the survey data means that tests of the cosmology dependence of the covariance are expensive. With these points in mind, this work presents a simple theoretical model for the linear covariance of anisotropic galaxy clustering observations with synthetic catalogues. Considering the Legendre moments (`multipoles') of the two-point statistics and projections into wide bins of the line-of-sight parameter (`clustering wedges'), we describe the modelling of the covariance for these anisotropic clustering measurements for galaxy samples with a trivial geometry in the case of a Gaussian approximation of the clustering likelihood. As main result of this paper, we give the explicit formulae for Fourier and configuration space covariance matrices. To validate our model, we create synthetic halo occupation distribution galaxy catalogues by populating the haloes of an ensemble of large-volume N-body simulations. Using linear and non-linear input power spectra, we find very good agreement between the model predictions and the measurements on the synthetic catalogues in the quasi-linear regime.

  20. Harmonic measure for percolation and ising clusters including rare events.

    Science.gov (United States)

    Adams, David A; Sander, Leonard M; Ziff, Robert M

    2008-10-03

    We obtain the harmonic measure of the hulls of critical percolation clusters and Ising-model Fortuin-Kastelyn clusters using a biased random-walk sampling technique which allows us to measure probabilities as small as 10{-300}. We find the multifractal D(q) spectrum including regions of small and negative q. Our results for external hulls agree with Duplantier's theoretical predictions for D(q) and his exponent -23/24 for the harmonic measure probability distribution for percolation. For the complete hull, we find the probability decays with an exponent of -1 for both systems.

  1. Measuring consistent masses for 25 Milky Way globular clusters

    Energy Technology Data Exchange (ETDEWEB)

    Kimmig, Brian; Seth, Anil; Ivans, Inese I.; Anderton, Tim; Gregersen, Dylan [Physics and Astronomy Department, University of Utah, SLC, UT 84112 (United States); Strader, Jay [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Caldwell, Nelson [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-02-01

    We present central velocity dispersions, masses, mass-to-light ratios (M/Ls ), and rotation strengths for 25 Galactic globular clusters (GCs). We derive radial velocities of 1951 stars in 12 GCs from single order spectra taken with Hectochelle on the MMT telescope. To this sample we add an analysis of available archival data of individual stars. For the full set of data we fit King models to derive consistent dynamical parameters for the clusters. We find good agreement between single-mass King models and the observed radial dispersion profiles. The large, uniform sample of dynamical masses we derive enables us to examine trends of M/L with cluster mass and metallicity. The overall values of M/L and the trends with mass and metallicity are consistent with existing measurements from a large sample of M31 clusters. This includes a clear trend of increasing M/L with cluster mass and lower than expected M/Ls for the metal-rich clusters. We find no clear trend of increasing rotation with increasing cluster metallicity suggested in previous work.

  2. Cluster formation as a measure of interpretability in multiple testing.

    Science.gov (United States)

    Shaffer, Juliet Popper

    2008-10-01

    Multiple test procedures are usually compared on various aspects of error control and power. Power is measured as some function of the number of false hypotheses correctly identified as false. However, given equal numbers of rejected false hypotheses, the pattern of rejections, i.e. the particular set of false hypotheses identified, may be crucial in interpreting the results for potential application.In an important area of application, comparisons among a set of treatments based on random samples from populations, two different approaches, cluster analysis and model selection, deal implicitly with such patterns, while traditional multiple testing procedures generally focus on the outcomes of subset and pairwise equality hypothesis tests, without considering the overall pattern of results in comparing methods. An important feature involving the pattern of rejections is their relevance for dividing the treatments into distinct subsets based on some parameter of interest, for example their means. This paper introduces some new measures relating to the potential of methods for achieving such divisions. Following Hartley (1955), sets of treatments with equal parameter values will be called clusters. Because it is necessary to distinguish between clusters in the populations and clustering in sample outcomes, the population clusters will be referred to as P -clusters; any related concepts defined in terms of the sample outcome will be referred to with the prefix outcome. Outcomes of multiple comparison procedures will be studied in terms of their probabilities of leading to separation of treatments into outcome clusters, with various measures relating to the number of such outcome clusters and the proportion of true vs. false outcome clusters. The definitions of true and false outcome clusters and related concepts, and the approach taken here, is in the tradition of hypothesis testing with attention to overall error control and power, but with added consideration of

  3. Subaru Weak Lensing Measurements of Four Strong Lensing Clusters: Are Lensing Clusters Over-Concentrated?

    Energy Technology Data Exchange (ETDEWEB)

    Oguri, Masamune; Hennawi, Joseph F.; Gladders, Michael D.; Dahle, Haakon; Natarajan, Priyamvada; Dalal, Neal; Koester, Benjamin P.; Sharon, Keren; Bayliss, Matthew

    2009-01-29

    We derive radial mass profiles of four strong lensing selected clusters which show prominent giant arcs (Abell 1703, SDSS J1446+3032, SDSS J1531+3414, and SDSS J2111-0115), by combining detailed strong lens modeling with weak lensing shear measured from deep Subaru Suprime-cam images. Weak lensing signals are detected at high significance for all four clusters, whose redshifts range from z = 0.28 to 0.64. We demonstrate that adding strong lensing information with known arc redshifts significantly improves constraints on the mass density profile, compared to those obtained from weak lensing alone. While the mass profiles are well fitted by the universal form predicted in N-body simulations of the {Lambda}-dominated cold dark matter model, all four clusters appear to be slightly more centrally concentrated (the concentration parameters c{sub vir} {approx} 8) than theoretical predictions, even after accounting for the bias toward higher concentrations inherent in lensing selected samples. Our results are consistent with previous studies which similarly detected a concentration excess, and increases the total number of clusters studied with the combined strong and weak lensing technique to ten. Combining our sample with previous work, we find that clusters with larger Einstein radii are more anomalously concentrated. We also present a detailed model of the lensing cluster Abell 1703 with constraints from multiple image families, and find the dark matter inner density profile to be cuspy with the slope consistent with -1, in agreement with expectations.

  4. Association Rule Pruning based on Interestingness Measures with Clustering

    Directory of Open Access Journals (Sweden)

    R. Bhaskaran

    2009-11-01

    Full Text Available Association rule mining plays vital part in knowledge mining. The difficult task is discovering knowledge or useful rules from the large number of rules generated for reduced support. For pruning or grouping rules, several techniques are used such as rule structure cover methods, informative cover methods, rule clustering, etc. Another way of selecting association rules is based on interestingness measures such as support, confidence, correlation, and so on. In this paper, we study how rule clusters of the pattern Xi -> Y are distributed over different interestingness measures.

  5. SURVEY ON CLUSTERING ALGORITHM AND SIMILARITY MEASURE FOR CATEGORICAL DATA

    Directory of Open Access Journals (Sweden)

    S. Anitha Elavarasi

    2014-01-01

    Full Text Available Learning is the process of generating useful information from a huge volume of data. Learning can be either supervised learning (e.g. classification or unsupervised learning (e.g. Clustering Clustering is the process of grouping a set of physical objects into classes of similar object. Objects in real world consist of both numerical and categorical data. Categorical data are not analyzed as numerical data because of the absence of inherit ordering. This paper describes about ten different clustering algorithms, its methodology and the factors influencing its performance. Each algorithm is evaluated using real world datasets and its pro and cons are specified. The various similarity / dissimilarity measure applied to categorical data and its performance is also discussed. The time complexity defines the amount of time taken by an algorithm to perform the elementary operation. The time complexity of various algorithms are discussed and its performance on real world data such as mushroom, zoo, soya bean, cancer, vote, car and iris are measured. In this survey Cluster Accuracy and Error rate for four different clustering algorithm (K-modes, fuzzy K-modes, ROCK and Squeezer, two different similarity measure (DISC and Overlap and DILCA applied for hierarchy and partition algorithm are evaluated.

  6. Clustering Measurements of broad-line AGNs: Review and Future

    CERN Document Server

    Krumpe, Mirko; Coil, Alison L

    2013-01-01

    Despite substantial effort, the precise physical processes that lead to the growth of super-massive black holes in the centers of galaxies are still not well understood. These phases of black hole growth are thought to be of key importance in understanding galaxy evolution. Forthcoming missions such as eROSITA, HETDEX, eBOSS, BigBOSS, LSST, and Pan-STARRS will compile by far the largest ever Active Galactic Nuclei (AGNs) catalogs which will allow us to measure the spatial distribution of AGNs in the universe with unprecedented accuracy. For the first time, AGN clustering measurements will reach a level of precision that will not only allow for an alternative approach to answering open questions in AGN/galaxy co-evolution but will open a new frontier, allowing us to precisely determine cosmological parameters. This paper reviews the large-scale clustering measurements of broad line AGNs. We summarize how clustering is measured and which constraints can be derived from AGN clustering measurements, we discuss re...

  7. The mass accretion rate of galaxy clusters: a measurable quantity

    CERN Document Server

    De Boni, Cristiano

    2016-01-01

    We are interested in investigating the growth of structures at the nonlinear scales of galaxy clusters from an observational perspective: we explore the possibility of measuring the mass accretion rate of galaxy clusters from their mass profile beyond the virial radius. We derive the accretion rate from the mass of a spherical shell whose infall velocity is extracted from $N$-body simulations. In the redshift range $z=[0,2]$, our prescription returns an average mass accretion rate within $20-40 \\%$ of the average rate derived from the merger trees of dark matter haloes extracted from $N$-body simulations. Our result suggests that measuring the mean mass accretion rate of a sample of galaxy clusters is actually feasible, thus providing a new potential observational test of the cosmological and structure formation models.

  8. Cluster bias: Testing measurement invariance in multilevel data

    NARCIS (Netherlands)

    Jak, S.

    2013-01-01

    In this thesis we presented methods and procedures to test and account for measurement bias in multilevel data. Multilevel data are data with a clustered structure, for instance data of children grouped in classrooms, or data of employees in teams. For example, with data of children in classes, we c

  9. Pixel-Cluster Counting Luminosity Measurement In ATLAS

    CERN Document Server

    McCormack, William Patrick; The ATLAS collaboration

    2016-01-01

    A precision measurement of the delivered luminosity is a key component of the ATLAS physics program at the Large Hadron Collider (LHC). A fundamental ingredient of the strategy to control the systematic uncertainties affecting the absolute luminosity has been to compare the measure- ments of several luminometers, most of which use more than one counting technique. The level of consistency across the various methods provides valuable cross-checks as well as an estimate of the detector-related systematic uncertainties. This poster describes the development of a luminosity algorithm based on pixel-cluster counting in the recently installed ATLAS inner b-layer (IBL), using data recorded during the 2015 pp run at the LHC. The noise and background contamination of the luminosity-associated cluster count is minimized by a multi-component fit to the measured cluster-size distribution in the forward pixel modules of the IBL. The linearity, long-term stability and statistical precision of the cluster- counting method a...

  10. Pixel-Cluster Counting Luminosity Measurement in ATLAS

    CERN Document Server

    McCormack, William Patrick; The ATLAS collaboration

    2016-01-01

    A precision measurement of the delivered luminosity is a key component of the ATLAS physics program at the Large Hadron Collider (LHC). A fundamental ingredient of the strategy to control the systematic uncertainties affecting the absolute luminosity has been to compare the measurements of several luminometers, most of which use more than one counting technique. The level of consistency across the various methods provides valuable cross-checks as well as an estimate of the detector-related systematic uncertainties. This poster describes the development of a luminosity algorithm based on pixel-cluster counting in the recently installed ATLAS inner b-layer (IBL), using data recorded during the 2015 pp run at the LHC. The noise and background contamination of the luminosity-associated cluster count is minimized by a multi-component fit to the measured cluster-size distribution in the forward pixel modules of the IBL. The linearity, long-term stability and statistical precision of the cluster-counting method are ...

  11. MEASUREMENT OF NANOMETER SCALE CADMIUM SELENIDE NANOCRYSTALS AND CLUSTER MOLECULES

    Institute of Scientific and Technical Information of China (English)

    Jeffrey Yang

    2003-01-01

    High performance Dynamic Light Scattering (DLS) has been used to determine the hydrodynamic diameters of CdSe nanocrystals as well as CdSe cluster molecules in a size range of 1 to 10 nm (Eichh(o)fer et al., 2001).The method enables the determination of their particle size, including their ligand shells, in solution. The results are consistent with the blue shift of the absorption bands, as well as Transmission Electron Microscope (TEM) experiments.The sizes of the cluster molecules were estimated from space filling models constructed from the results of a single crystal X-ray structure determination. DLS gave comparable results for the size of both types of compound, indicating that it is potentially an important additional measurement technique to TEM, which uses harsh measurement conditions,and to powder X-ray diffraction, which is difficult to interpret below 5 nm.

  12. Unbiased methods for removing systematics from galaxy clustering measurements

    CERN Document Server

    Elsner, Franz; Peiris, Hiranya V

    2015-01-01

    Measuring the angular clustering of galaxies as a function of redshift is a powerful method for tracting information from the three-dimensional galaxy distribution. The precision of such measurements will dramatically increase with ongoing and future wide-field galaxy surveys. However, these are also increasingly sensitive to observational and astrophysical contaminants. Here, we study the statistical properties of three methods proposed for controlling such systematics - template subtraction, basic mode projection, and extended mode projection - all of which make use of externally supplied template maps, designed to characterise and capture the spatial variations of potential systematic effects. Based on a detailed mathematical analysis, and in agreement with simulations, we find that the template subtraction method in its original formulation returns biased estimates of the galaxy angular clustering. We derive closed-form expressions that should be used to correct results for this shortcoming. Turning to th...

  13. Distinguishing Functional DNA Words; A Method for Measuring Clustering Levels

    Science.gov (United States)

    Moghaddasi, Hanieh; Khalifeh, Khosrow; Darooneh, Amir Hossein

    2017-01-01

    Functional DNA sub-sequences and genome elements are spatially clustered through the genome just as keywords in literary texts. Therefore, some of the methods for ranking words in texts can also be used to compare different DNA sub-sequences. In analogy with the literary texts, here we claim that the distribution of distances between the successive sub-sequences (words) is q-exponential which is the distribution function in non-extensive statistical mechanics. Thus the q-parameter can be used as a measure of words clustering levels. Here, we analyzed the distribution of distances between consecutive occurrences of 16 possible dinucleotides in human chromosomes to obtain their corresponding q-parameters. We found that CG as a biologically important two-letter word concerning its methylation, has the highest clustering level. This finding shows the predicting ability of the method in biology. We also proposed that chromosome 18 with the largest value of q-parameter for promoters of genes is more sensitive to dietary and lifestyle. We extended our study to compare the genome of some selected organisms and concluded that the clustering level of CGs increases in higher evolutionary organisms compared to lower ones. PMID:28128320

  14. Distinguishing Functional DNA Words; A Method for Measuring Clustering Levels

    Science.gov (United States)

    Moghaddasi, Hanieh; Khalifeh, Khosrow; Darooneh, Amir Hossein

    2017-01-01

    Functional DNA sub-sequences and genome elements are spatially clustered through the genome just as keywords in literary texts. Therefore, some of the methods for ranking words in texts can also be used to compare different DNA sub-sequences. In analogy with the literary texts, here we claim that the distribution of distances between the successive sub-sequences (words) is q-exponential which is the distribution function in non-extensive statistical mechanics. Thus the q-parameter can be used as a measure of words clustering levels. Here, we analyzed the distribution of distances between consecutive occurrences of 16 possible dinucleotides in human chromosomes to obtain their corresponding q-parameters. We found that CG as a biologically important two-letter word concerning its methylation, has the highest clustering level. This finding shows the predicting ability of the method in biology. We also proposed that chromosome 18 with the largest value of q-parameter for promoters of genes is more sensitive to dietary and lifestyle. We extended our study to compare the genome of some selected organisms and concluded that the clustering level of CGs increases in higher evolutionary organisms compared to lower ones.

  15. Can A Galaxy Redshift Survey Measure Dark Energy Clustering?

    CERN Document Server

    Takada, M

    2006-01-01

    (abridged) A wide-field galaxy redshift survey allows one to probe galaxy clustering at largest spatial scales, which carries an invaluable information on horizon-scale physics complementarily to the cosmic microwave background (CMB). Assuming the planned survey consisting of z~1 and z~3 surveys with areas of 2000 and 300 square degrees, respectively, we study the prospects for probing dark energy clustering from the measured galaxy power spectrum, assuming the dynamical properties of dark energy are specified in terms of the equation of state and the effective sound speed c_e in the context of an adiabatic cold dark matter (CDM) model. The dark energy clustering adds a power to the galaxy power spectrum amplitude at spatial scales greater than the sound horizon, and the enhancement is sensitive to redshift evolution of the net dark energy density, i.e. the equation of state. We find that the galaxy survey, when combined with Planck, can distinguish dark energy clustering from a smooth dark energy model such ...

  16. Heavy-Fermion Compound of the Ternary Phosphide Ce2Pt8P with a Non-Centrosymmetric Structure

    Science.gov (United States)

    Kase, Naoki; Furukawa, Shoh; Nakano, Tomohito; Takeda, Naoya

    2017-01-01

    The low-temperature properties of Ce2Pt8P are studied by magnetic susceptibility χ(T), electrical resistivity ρ(T), and specific heat C(T) measurements. The crystal structure is considered to be analogs of the CePt3Si-type structure. From the magnetic susceptibility χ(T), the effective paramagnetic moment μeff is estimated to be 2.30 μB/Ce, suggesting that the valence state of Ce ions is expected to be close to trivalent (Ce3+). The paramagnetic Curie-Weiss temperature θcw is determined to be 12 K. The electrical resistivity ρ(T) shows -ln T dependence with a small slope from 10 to 3 K, which indicates a weak Kondo anomaly. The specific heat exhibits a λ-type anomaly at around T* = 1.0 K, while the magnetic entropy at T* is reduced to 80% of R ln 2. The linear coefficient of specific heat is determined to be 145 mJ/(mol-Ce·K2). From several measurements, Ce2Pt8P can be classified as a moderate heavy-fermion compound. The ground state is far from the quantum-critical point (QCP) compared with CePt3Si. La2Pt8P shows normal metallic behavior and no superconductivity is observed above 0.28 K.

  17. Measuring the Ultimate Mass of Galaxy Clusters: Redshifts and Mass Profiles from the Hectospec Cluster Survey (HeCS)

    CERN Document Server

    Rines, Kenneth; Diaferio, Antonaldo; Kurtz, Michael J

    2012-01-01

    The infall regions of galaxy clusters represent the largest gravitationally bound structures in a $\\Lambda$CDM universe. Measuring cluster mass profiles into the infall regions provides an estimate of the ultimate mass of these haloes. We use the caustic technique to measure cluster mass profiles from galaxy redshifts obtained with the Hectospec Cluster Survey (HeCS), an extensive spectroscopic survey of galaxy clusters with MMT/Hectospec. We survey 58 clusters selected by X-ray flux at 0.1$<$$z$$<$0.3. The survey includes 21,314 unique MMT/Hectospec redshifts for individual galaxies; 10,275 of these galaxies are cluster members. For each cluster we acquired high signal-to-noise spectra for $\\sim 200$ cluster members and a comparable number of foreground/background galaxies. The cluster members trace out infall patterns around the clusters. The members define a very narrow red sequence. The velocity dispersions decline with radius; we demonstrate that the determination of the velocity dispersion is inse...

  18. Measuring the 3D shape of X-ray clusters

    CERN Document Server

    Samsing, Johan; Hansen, Steen H

    2012-01-01

    Observations and numerical simulations of galaxy clusters strongly indicate that the hot intracluster x-ray emitting gas is not spherically symmetric. In many earlier studies spherical symmetry has been assumed partly because of limited data quality, however new deep observations and instrumental designs will make it possible to go beyond that assumption. Measuring the temperature and density profiles are of interest when observing the x-ray gas, however the spatial shape of the gas itself also carries very useful information. For example, it is believed that the x-ray gas shape in the inner parts of galaxy clusters is greatly affected by feedback mechanisms, cooling and rotation, and measuring this shape can therefore indirectly provide information on these mechanisms. In this paper we present a novel method to measure the three-dimensional shape of the intracluster x-ray emitting gas. We can measure the shape from the x-ray observations only, i.e. the method does not require combination with independent mea...

  19. Spam Source Clustering by Constructing Spammer Network with Correlation Measure

    Science.gov (United States)

    Shin, Jeongkyu; Kim, Seunghwan

    Spam filtering is one of the most challenging problems in electric message systems. In general, recent studies on specifying real spam source are based on content filtering because spammers usually falsify their origin. We propose a method to specify spam source based on structural analysis with complex network. We assume that each spam sources either has the same victim list or uses the same spam-hosting program. We treat spam source - target relationship as a bipartite network and construct weighted spam source network by network projection using correlation measure. We find that community clustering methods are inappropriate with spammer network. We group spammers with gradient-based grouping, which uses correlations between nodes as gradient between nodes. We convert them into local minima, which helps to cluster spammers into a few spam source groups. We investigate the weblog spam data with the proposed method and validate it. The method that we propose can be applied to diverse categorization problems, such as multiple text categorization and network subunit clustering.

  20. Using cluster analysis in measuring social domain of territorial brand

    Directory of Open Access Journals (Sweden)

    Zlata Stepanova

    2009-10-01

    Full Text Available Territorial brand has a social dimension reflected in the social equilibrium and measurable with social effectiveness indicators. The paper offers social effectiveness analysis of territory using investigation object “territorial and social systems (TSS” with their further classification according to social types based on cluster analysis. This method allows the authors to distinct four social types of TSS in Sverdlovsk region in accordance with such characteristics as financial activity, quality of life, social stability and ill-being levels. The results of investigation could be useful for brand policy of territorial authorities.

  1. Spatio-Temporal Deforestation Measurement Using Automatic Clustering

    Directory of Open Access Journals (Sweden)

    Irene Erlyn Wina Rachmawan

    2016-06-01

    Full Text Available Deforestation is one of the crucial issues in Indonesia. In 2012, deforestation rate in Indonesia reached 0.84 million hectares, exceeding Brazil. According to the 2009 Guinness World Records, Indonesia's deforestation rate was 1.8 million hectares per year between 2000 and 2005. An interesting view is the fact that Indonesia government denied the deforestation rate in those years and said that the rate was only 1.08 million hectares per year in 2000 and 2005. The different problem is on the technique how to deal with the deforestation rate. In this paper, we proposed a new approach for automatically identifying the deforestation area and measuring the deforestation rate. This approach involves differential image processing for detecting Spatio-temporal nature changes of deforestation. It consists series of important features extracted from multiband satellite images which are considered as the dataset of the research. These data are proceeded through the following stages: (1 Automatic clustering for multiband satellite images, (2 Reinforcement Programming to optimize K-Means clustering, (3 Automatic interpretation for deforestation areas, and (4 Deforestation measurement adjusting with elevation of the satellite. For experimental study, we applied our proposed approach to analyze and measure the deforestation in Mendawai, South Borneo. We utilized Landsat 7 to obtain the multiband images for that area from the year 2001 to 2013. Our proposed approach is able to identify the deforestation area and measure the rate. The experiment with our proposed approach made a temporal measurement for the area and showed the increasing deforestation size of the area 1.80 hectares during those years.

  2. Improved correction of VIPERS angular selection effects in clustering measurements

    Science.gov (United States)

    Pezzotta, A.; Granett, B. R.; Bel, J.; Guzzo, L.; de la Torre, S.; Aff004

    2016-10-01

    Clustering estimates in galaxy redshift surveys need to account and correct for the way targets are selected from the general population, as to avoid biasing the measured values of cosmological parameters. The VIMOS Public Extragalactic Redshift Survey (VIPERS) is no exception to this, involving slit collisions and masking effects. Pushed by the increasing precision of the measurements, e.g. of the growth rate f, we have been re-assessing these effects in detail. We present here an improved correction for the two-point correlation function, capable to recover the amplitude of the monopole of the two-point correlation function ξ(r) above 1 h-1 Mpc to better than 2.

  3. A hybrid distance measure for clustering expressed sequence tags originating from the same gene family.

    Directory of Open Access Journals (Sweden)

    Keng-Hoong Ng

    Full Text Available BACKGROUND: Clustering is a key step in the processing of Expressed Sequence Tags (ESTs. The primary goal of clustering is to put ESTs from the same transcript of a single gene into a unique cluster. Recent EST clustering algorithms mostly adopt the alignment-free distance measures, where they tend to yield acceptable clustering accuracies with reasonable computational time. Despite the fact that these clustering methods work satisfactorily on a majority of the EST datasets, they have a common weakness. They are prone to deliver unsatisfactory clustering results when dealing with ESTs from the genes derived from the same family. The root cause is the distance measures applied on them are not sensitive enough to separate these closely related genes. METHODOLOGY/PRINCIPAL FINDINGS: We propose a hybrid distance measure that combines the global and local features extracted from ESTs, with the aim to address the clustering problem faced by ESTs derived from the same gene family. The clustering process is implemented using the DBSCAN algorithm. We test the hybrid distance measure on the ten EST datasets, and the clustering results are compared with the two alignment-free EST clustering tools, i.e. wcd and PEACE. The clustering results indicate that the proposed hybrid distance measure performs relatively better (in terms of clustering accuracy than both EST clustering tools. CONCLUSIONS/SIGNIFICANCE: The clustering results provide support for the effectiveness of the proposed hybrid distance measure in solving the clustering problem for ESTs that originate from the same gene family. The improvement of clustering accuracies on the experimental datasets has supported the claim that the sensitivity of the hybrid distance measure is sufficient to solve the clustering problem.

  4. Clustering tomography: measuring cosmological distances through angular clustering in thin redshift shells

    CERN Document Server

    Salazar-Albornoz, Salvador; Padilla, Nelson D; Baugh, Carlton M

    2014-01-01

    We test the cosmological implications of studying galaxy clustering using a tomographic approach, by computing the galaxy two-point angular correlation function $\\omega(\\theta)$ in thin redshift shells using a spectroscopic-redshift galaxy survey. The advantages of this procedure are that it is not necessary to assume a fiducial cosmology in order to convert measured angular positions and redshifts into distances, and that it gives several (less accurate) measurements of the angular diameter distance $D_\\rm{A}(z)$ instead of only one (more precise) measurement of the effective average distance $D_\\rm{V}(z)$, which results in better constraints on the expansion history of the Universe. We test our model for $\\omega(\\theta)$ and its covariance matrix against a set of mock galaxy catalogues and show that this technique is able to extract unbiased cosmological constraints. Also, assuming the best-fit $\\Lambda$CDM cosmology from the cosmic microwave background measurements from the Planck satellite, we forecast th...

  5. Dwarf Galaxies in the Coma Cluster: I. Velocity Dispersion Measurements

    CERN Document Server

    Kourkchi, E; Carter, D; Karick, A M; Mármol-Queraltó, E; Chiboucas, K; Tully, R B; Mobasher, B; Guzmán, R; Matković, A; Gruel, N

    2011-01-01

    We present the study of a large sample of early-type dwarf galaxies in the Coma cluster observed with DEIMOS on the Keck II to determine their internal velocity dispersion. We focus on a subsample of 41 member dwarf elliptical galaxies for which the velocity dispersion can be reliably measured, 26 of which were studied for the first time. The magnitude range of our sample is $-21measurement of the velocity dispersion and their error estimates. The measurements were performed using {\\it pPXF (penalised PiXel Fitting)} and using the Calcium triplet absorption lines. We use Monte Carlo bootstrapping to study various sources of uncertainty in our measurements, namely statistical uncertainty, template mismatch and other systematics. We find that the main source of uncertainty is the template mismatch effect which is reduced by using templates with a range of spectral types. Combining our measurements with those from the literature, we study the Faber-Jackson...

  6. The cosmological analysis of X-ray cluster surveys; III. Bypassing cluster mass measurements

    CERN Document Server

    Pierre, M; Faccioli, L; Clerc, N; Gastaud, R; Koulouridis, E; Pacaud, F

    2016-01-01

    Despite strong theoretical arguments, the use of clusters as cosmological probes is, in practice, frequently questioned because of the many uncertainties impinging on cluster mass estimates. Our aim is to develop a fully self-consistent cosmological approach of X-ray cluster surveys, exclusively based on observable quantities, rather than masses. This procedure is justified given the possibility to directly derive the cluster properties via ab initio modelling, either analytically or by using hydrodynamical simulations. In this third paper, we evaluate the method on cluster toy-catalogues. We model the population of detected clusters in the count-rate -- hardness-ratio -- angular size -- redshift space and compare the corresponding 4-dimensional diagram with theoretical predictions. The best cosmology+physics parameter configuration is determined using a simple minimisation procedure; errors on the parameters are derived by scanning the likelihood hyper-surfaces with a wide range of starting values. The metho...

  7. Synthesis and Characterization of Monodisperse Metallodielectric SiO2@Pt@SiO2 Core-Shell-Shell Particles.

    Science.gov (United States)

    Petrov, Alexey; Lehmann, Hauke; Finsel, Maik; Klinke, Christian; Weller, Horst; Vossmeyer, Tobias

    2016-01-26

    Metallodielectric nanostructured core-shell-shell particles are particularly desirable for enabling novel types of optical components, including narrow-band absorbers, narrow-band photodetectors, and thermal emitters, as well as new types of sensors and catalysts. Here, we present a facile approach for the preparation of submicron SiO2@Pt@SiO2 core-shell-shell particles. As shown by transmission and scanning electron microscopy, the first steps of this approach allow for the deposition of closed and almost perfectly smooth platinum shells onto silica cores via a seeded growth mechanism. By choosing appropriate conditions, the shell thickness could be adjusted precisely, ranging from ∼3 to ∼32 nm. As determined by X-ray diffraction, the crystalline domain sizes of the polycrystalline metal shells were ∼4 nm, regardless of the shell thickness. The platinum content of the particles was determined by atomic absorption spectroscopy and for thin shells consistent with a dense metal layer of the TEM-measured thickness. In addition, we show that the roughness of the platinum shell strongly depends on the storage time of the gold seeds used to initiate reductive platinum deposition. Further, using polyvinylpyrrolidone as adhesion layer, it was possible to coat the metallic shells with very homogeneous and smooth insulating silica shells of well-controlled thicknesses between ∼2 and ∼43 nm. After depositing the particles onto silicon substrates equipped with interdigitated electrode structures, the metallic character of the SiO2@Pt particles and the insulating character of the SiO2 shells of the SiO2@Pt@SiO2 particles were successfully demonstrated by charge transport measurements at variable temperatures.

  8. Measurement Error Correction Formula for Cluster-Level Group Differences in Cluster Randomized and Observational Studies

    Science.gov (United States)

    Cho, Sun-Joo; Preacher, Kristopher J.

    2016-01-01

    Multilevel modeling (MLM) is frequently used to detect cluster-level group differences in cluster randomized trial and observational studies. Group differences on the outcomes (posttest scores) are detected by controlling for the covariate (pretest scores) as a proxy variable for unobserved factors that predict future attributes. The pretest and…

  9. Turbulent processes in Earth's magnetosheath by Cluster mission measurements

    Science.gov (United States)

    Kozak, L. V.; Lui, A. T. Y.; Kronberg, E. A.; Prokhorenkov, A. S.

    2017-02-01

    Methods and approaches which can be used for the analysis of hydrodynamic and magnetohydrodynamic turbulent flows are chosen for this study. It is defined that the best methods for determination of turbulent process types are the methods of statistical physics. Within the statistical approach the fractal analysis (height of the maximum of probability density fluctuations of the studied parameters) and multifractal analysis (study of a power dependence of high order statistical moments and construction of multifractal spectrum) are considered. It is indicated that the statistical analysis of turbulent process properties can be supplemented with spectral studies (wavelet analysis). Physical processes in the transition regions of the magnetosphere: foreshock, shock, post-shock and magnetosheath are investigated using high frequency measurements by Cluster satellites. Extended self-similarity analysis and structure function analysis demonstrate the presence of super-diffusion processes and the highest values of generalized diffusion coefficients observed in post-shock region. It can be noted that different approaches for the analysis of turbulent processes give similar results and indicate the presence of super-diffusion processes in the transition region of the Earth's magnetosphere. This fact must be taken into account when constructing quantitative models of a transfer process. Wavelet analysis shows the presence of cascade and inverse cascade processes in the Earth's magnetosheath. Good agreement with other studies and our new results contribute to improvement of our understanding of turbulence.

  10. Clusters as benchmarks for measuring fundamental stellar parameters

    CERN Document Server

    Bell, Cameron P M

    2016-01-01

    In this contribution I will discuss fundamental stellar parameters as determined from young star clusters; specifically those with ages less than or approximately equal to that of the Pleiades. I will focus primarily on the use of stellar evolutionary models to determine the ages and masses of stars, as well as discuss the limitations of such models using a combination of both young clusters and eclipsing binary systems. In addition, I will also highlight a few interesting recent results from large on-going spectroscopic surveys (specifically Gaia-ESO and APOGEE/IN-SYNC) which are continuing to challenge our understanding of the formation and early evolutionary stages of young clusters.

  11. Searching for Excess Rotation Measures in Galaxy Clusters with the NVSS

    Indian Academy of Sciences (India)

    M. Johnston-Hollitt; G. Grimwood

    2011-12-01

    We present a statistical analysis of the rotation measure (RM) catalogue from the NVSS in search for a statistical excess of rotation measure through Abell clusters. After excluding the data known to be affected by the large-scale magnetic field of the Galaxy ( ≤ |30|), we consider RMs as a function of normalized Abell radius for 496 galaxy clusters. Despite that it is now well established that galaxy clusters contain magnetic fields, we find no evidence of an increase of the rotation measure for lines of sight toward Abell clusters. Additionally, we find no evidence for statistically different rotation measure values between cluster lines of sight and RMs up to 7 Abell radii from the cluster over that expected from the intrinsic variation of the NVSS dataset. We suggest this is the result of sparse spatial coverage of suitably polarized sources in the NVSS.

  12. A Monte Carlo approach for determining cluster evaporation rates from concentration measurements

    Science.gov (United States)

    Kupiainen-Määttä, Oona

    2016-11-01

    Evaporation rates of small negatively charged sulfuric acid-ammonia clusters are determined by combining detailed cluster formation simulations with cluster distributions measured in the CLOUD experiment at CERN. The analysis is performed by varying the evaporation rates with Markov chain Monte Carlo (MCMC), running cluster formation simulations with each new set of evaporation rates and comparing the obtained cluster distributions to the measurements. In a second set of simulations, the fragmentation of clusters in the mass spectrometer due to energetic collisions is studied by treating also the fragmentation probabilities as unknown parameters and varying them with MCMC. This second set of simulations results in a better fit to the experimental data, suggesting that a large fraction of the observed HSO4- and HSO4- ṡ H2SO4 signals may result from fragmentation of larger clusters, most importantly the HSO4- ṡ (H2SO4)2 trimer.

  13. 18 GHz SZ Measurements of the Bullet Cluster

    Indian Academy of Sciences (India)

    Siddharth S. Malu; Ravi Subrahmanyan

    2011-12-01

    We present 18 GHz observations of the Bullet cluster using the Austalia Telescope Compact Array (ATCA), which show structure in the Sunyaev–Zeldovich effect; in particular, a deep, compact feature which does not correspond to any bright feature in X-ray, optical or lensing maps. In general, the relatively deeper SZE features appear to avoid the regions with the most intense X-ray emission. SZE displaced from X-ray centres implies that modeling cluster dynamics is non-trivial. The SZE distribution in the western parts of the cluster are co-spatial with the radio halo indicative of a common origin for the hot and relativistic electrons in the turbulent wake of the Bullet.

  14. Enhancing Time Series Clustering by Incorporating Multiple Distance Measures with Semi-Supervised Learning

    Institute of Scientific and Technical Information of China (English)

    周竞; 朱山风; 黄晓地; 张彦春

    2015-01-01

    Time series clustering is widely applied in various areas. Existing researches focus mainly on distance measures between two time series, such as dynamic time warping (DTW) based methods, edit-distance based methods, and shapelets-based methods. In this work, we experimentally demonstrate, for the first time, that no single distance measure performs significantly better than others on clustering datasets of time series where spectral clustering is used. As such, a question arises as to how to choose an appropriate measure for a given dataset of time series. To answer this question, we propose an integration scheme that incorporates multiple distance measures using semi-supervised clustering. Our approach is able to integrate all the measures by extracting valuable underlying information for the clustering. To the best of our knowledge, this work demonstrates for the first time that the semi-supervised clustering method based on constraints is able to enhance time series clustering by combining multiple distance measures. Having tested on clustering various time series datasets, we show that our method outperforms individual measures, as well as typical integration approaches.

  15. Cluster-state quantum computing enhanced by high-fidelity generalized measurements.

    Science.gov (United States)

    Biggerstaff, D N; Kaltenbaek, R; Hamel, D R; Weihs, G; Rudolph, T; Resch, K J

    2009-12-11

    We introduce and implement a technique to extend the quantum computational power of cluster states by replacing some projective measurements with generalized quantum measurements (POVMs). As an experimental demonstration we fully realize an arbitrary three-qubit cluster computation by implementing a tunable linear-optical POVM, as well as fast active feedforward, on a two-qubit photonic cluster state. Over 206 different computations, the average output fidelity is 0.9832+/-0.0002; furthermore the error contribution from our POVM device and feedforward is only of O(10(-3)), less than some recent thresholds for fault-tolerant cluster computing.

  16. Measuring customer loyalty using an extended RFM and clustering technique

    Directory of Open Access Journals (Sweden)

    Zohre Zalaghi

    2014-05-01

    Full Text Available Today, the ability to identify the profitable customers, creating a long-term loyalty in them and expanding the existing relationships are considered as the key and competitive factors for a customer-oriented organization. The prerequisite for having such competitive factors is the presence of a very powerful customer relationship management (CRM. The accurate evaluation of customers’ profitability is considered as one of the fundamental reasons that lead to a successful customer relationship management. RFM is a method that scrutinizes three properties, namely recency, frequency and monetary for each customer and scores customers based on these properties. In this paper, a method is introduced that obtains the behavioral traits of customers using the extended RFM approach and having the information related to the customers of an organization; it then classifies the customers using the K-means algorithm and finally scores the customers in terms of their loyalty in each cluster. In the suggested approach, first the customers’ records will be clustered and then the RFM model items will be specified through selecting the effective properties on the customers’ loyalty rate using the multipurpose genetic algorithm. Next, they will be scored in each cluster based on the effect that they have on the loyalty rate. The influence rate each property has on loyalty is calculated using the Spearman’s correlation coefficient.

  17. Measures of Galaxy Environment - III. Difficulties in identifying proto-clusters at z ~ 2

    CERN Document Server

    Shattow, Genevieve M; Skibba, Ramin A; Muldrew, Stuart I; Pearce, Frazer R; Abbas, Ummi

    2013-01-01

    Galaxy environment is frequently discussed, but inconsistently defined. It is especially difficult to measure at high redshift where only photometric redshifts are available. With a focus on early forming proto-clusters, we use a semi-analytical model of galaxy formation to show how the environment measurement around high redshift galaxies is sensitive to both scale and metric, as well as to cluster viewing angle, evolutionary state, and the availability of either spectroscopic or photometric data. We use two types of environment metrics (nearest neighbour and fixed aperture) at a range of scales on simulated high-z clusters to see how "observed" overdensities compare to "real" overdensities. We also "observationally" identify z = 2 proto-cluster candidates in our model and track the growth histories of their parent halos through time, considering in particular their final state at z = 0. Although the measured environment of early forming clusters is critically dependent on all of the above effects (and in pa...

  18. Ellipticity-age relation for globular clusters in the Large Magellanic Cloud. 1. Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Frenk, C.S.; Fall, S.M. (Cambridge Univ. (UK). Inst. of Astronomy)

    1982-05-01

    The ellipticities of 52 globular clusters in the LMC and 93 in the Galaxy have been estimated by the eye-measurement of their images on Sky Survey enlargements. These were checked against star counts in 12 clusters of the LMC sample, using a procedure developed for this purpose, and against star counts in 19 clusters of the galactic sample, using determinations reported by Kholopov. The results from the eye and count methods are in excellent agreement and a comparison of the two samples shows that the globular clusters in the LMC are significantly flatter than those in the Galaxy. As a means of investigating evolutionary effects, UBV photometry has been used to arrange the LMC clusters in a sequence of relative ages that is equivalent to the one devised by Searle, Wilkinson and Bagnuolo. The results show that young clusters are flatter on average than old clusters and that the shapes of the oldest clusters in the LMC are similar to those of galactic globular clusters. The dependence of ellipticity on age may be due to changes in the shapes of the clusters, changes in the condition of their formation or some combination of both effects.

  19. Improved optical mass tracer for galaxy clusters calibrated using weak lensing measurements

    CERN Document Server

    Reyes, Reinabelle; Hirata, Christopher M; Bahcall, Neta; Seljak, Uros

    2008-01-01

    We develop an improved mass tracer for clusters of galaxies from optically observed parameters, and calibrate the mass relation using weak gravitational lensing measurements. We employ a sample of ~ 13,000 optically-selected clusters from the Sloan Digital Sky Survey (SDSS) maxBCG catalog, with photometric redshifts in the range 0.1-0.3. The optical tracers we consider are cluster richness, cluster luminosity, luminosity of the brightest cluster galaxy (BCG), and combinations of these parameters. We measure the weak lensing signal around stacked clusters as a function of the different tracers, and use it to determine the tracer with the least amount of scatter. We further use the weak lensing data to calibrate the mass normalization. We find that the best mass estimator for massive clusters is a combination of cluster richness, N_{200}, and the luminosity of the brightest cluster galaxy, L_{BCG}: M_{200\\bar{\\rho}} = (1.27 +/- 0.08) (N_{200}/20)^{1.20 +/- 0.09} (L_{BCG}/\\bar{L}_{BCG}(N_{200}))^{0.71 +/- 0.14} ...

  20. Atmospheric sulphuric acid and neutral cluster measurements using CI-APi-TOF

    Directory of Open Access Journals (Sweden)

    T. Jokinen

    2011-12-01

    Full Text Available The first ambient measurements using nitrate ion based Chemical Ionization with the Atmospheric Pressure interface Time-Of-Flight mass spectrometer (CI-APi-TOF for sulphuric acid and neutral cluster detection are presented. We have found CI-APi-TOF a highly stable and sensitive tool for molecular sulphuric acid detection. The lowest limit of detection for sulphuric acid was determined to be 3 × 104 molecules cm−3 for two hour averaging. Signals from sulphuric acid clusters up to tetramer accompanied by ammonia were also obtained but these were found to result from naturally charged clusters formed by ion induced clustering in the atmosphere during nucleation. Opposite to earlier studies with cluster mass spectrometers, we had no indication of neutral clusters. The reason is either less efficient charging of clusters in comparison to molecular sulphuric acid, or in low concentration of neutral clusters at our measurement site during these particular nucleation events. We show that utilizing high resolution mass spectrometry is crucial in separating the weak sulfuric acid cluster signal from the other compounds.

  1. Atmospheric sulphuric acid and neutral cluster measurements using CI-APi-TOF

    Directory of Open Access Journals (Sweden)

    T. Jokinen

    2012-05-01

    Full Text Available The first ambient measurements using nitrate ion based Chemical Ionization with the Atmospheric Pressure interface Time-Of-Flight mass spectrometer (CI-APi-TOF for sulphuric acid and neutral cluster detection are presented. We have found CI-APi-TOF a highly stable and sensitive tool for molecular sulphuric acid detection. The lowest limit of detection for sulphuric acid was determined to be 3.6 × 104 molecules cm−3 for 15 min averaging. Signals from sulphuric acid clusters up to tetramer containing ammonia were also obtained but these were found to result from naturally charged clusters formed by ion induced clustering in the atmosphere during nucleation. Opposite to earlier studies with cluster mass spectrometers, we had no indication of neutral clusters. The reason is either less efficient charging of clusters in comparison to molecular sulphuric acid, or the low concentration of neutral clusters at our measurement site during these particular nucleation events. We show that utilizing high resolution mass spectrometry is crucial in separating the weak sulfuric acid cluster signal from other compounds.

  2. Orbital-exchange and fractional quantum number excitations in an f-electron metal, Yb2Pt2Pb

    Science.gov (United States)

    Wu, L. S.; Gannon, W. J.; Zaliznyak, I. A.; Tsvelik, A. M.; Brockmann, M.; Caux, J.-S.; Kim, M. S.; Qiu, Y.; Copley, J. R. D.; Ehlers, G.; Podlesnyak, A.; Aronson, M. C.

    2016-06-01

    Exotic quantum states and fractionalized magnetic excitations, such as spinons in one-dimensional chains, are generally expected to occur in 3d transition metal systems with spin 1/2. Our neutron-scattering experiments on the 4f-electron metal Yb2Pt2Pb overturn this conventional wisdom. We observe broad magnetic continuum dispersing in only one direction, which indicates that the underlying elementary excitations are spinons carrying fractional spin-1/2. These spinons are the emergent quantum dynamics of the anisotropic, orbital-dominated Yb moments. Owing to their unusual origin, only longitudinal spin fluctuations are measurable, whereas the transverse excitations such as spin waves are virtually invisible to magnetic neutron scattering. The proliferation of these orbital spinons strips the electrons of their orbital identity, resulting in charge-orbital separation.

  3. MEASUREMENT OF GALAXY CLUSTER INTEGRATED COMPTONIZATION AND MASS SCALING RELATIONS WITH THE SOUTH POLE TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Saliwanchik, B. R.; Montroy, T. E. [Physics Department, Center for Education and Research in Cosmology and Astrophysics, Case Western Reserve University, Cleveland, OH 44106 (United States); Aird, K. A. [University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Bayliss, M. [Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138 (United States); Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Bocquet, S.; Desai, S. [Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, D-81679 München (Germany); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Cho, H. M. [NIST Quantum Devices Group, 325 Broadway, Mailcode 817.03, Boulder, CO 80305 (United States); Clocchiatti, A. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica (Chile); De Haan, T.; Dobbs, M. A.; Dudley, J. P. [Department of Physics, McGill University, 3600 Rue University, Montreal, QC H3A 2T8 (Canada); Foley, R. J.; Forman, W. R., E-mail: benjamin.saliwanchik@case.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); and others

    2015-02-01

    We describe a method for measuring the integrated Comptonization (Y {sub SZ}) of clusters of galaxies from measurements of the Sunyaev-Zel'dovich (SZ) effect in multiple frequency bands and use this method to characterize a sample of galaxy clusters detected in the South Pole Telescope (SPT) data. We use a Markov Chain Monte Carlo method to fit a β-model source profile and integrate Y {sub SZ} within an angular aperture on the sky. In simulated observations of an SPT-like survey that include cosmic microwave background anisotropy, point sources, and atmospheric and instrumental noise at typical SPT-SZ survey levels, we show that we can accurately recover β-model parameters for inputted clusters. We measure Y {sub SZ} for simulated semi-analytic clusters and find that Y {sub SZ} is most accurately determined in an angular aperture comparable to the SPT beam size. We demonstrate the utility of this method to measure Y {sub SZ} and to constrain mass scaling relations using X-ray mass estimates for a sample of 18 galaxy clusters from the SPT-SZ survey. Measuring Y {sub SZ} within a 0.'75 radius aperture, we find an intrinsic log-normal scatter of 21% ± 11% in Y {sub SZ} at a fixed mass. Measuring Y {sub SZ} within a 0.3 Mpc projected radius (equivalent to 0.'75 at the survey median redshift z = 0.6), we find a scatter of 26% ± 9%. Prior to this study, the SPT observable found to have the lowest scatter with mass was cluster detection significance. We demonstrate, from both simulations and SPT observed clusters that Y {sub SZ} measured within an aperture comparable to the SPT beam size is equivalent, in terms of scatter with cluster mass, to SPT cluster detection significance.

  4. Measurement of Galaxy Cluster Integrated Comptonization and Mass Scaling Relations with the South Pole Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Saliwanchik, B. R.; et al.

    2015-01-22

    We describe a method for measuring the integrated Comptonization (Y (SZ)) of clusters of galaxies from measurements of the Sunyaev-Zel'dovich (SZ) effect in multiple frequency bands and use this method to characterize a sample of galaxy clusters detected in the South Pole Telescope (SPT) data. We use a Markov Chain Monte Carlo method to fit a β-model source profile and integrate Y (SZ) within an angular aperture on the sky. In simulated observations of an SPT-like survey that include cosmic microwave background anisotropy, point sources, and atmospheric and instrumental noise at typical SPT-SZ survey levels, we show that we can accurately recover β-model parameters for inputted clusters. We measure Y (SZ) for simulated semi-analytic clusters and find that Y (SZ) is most accurately determined in an angular aperture comparable to the SPT beam size. We demonstrate the utility of this method to measure Y (SZ) and to constrain mass scaling relations using X-ray mass estimates for a sample of 18 galaxy clusters from the SPT-SZ survey. Measuring Y (SZ) within a 0.'75 radius aperture, we find an intrinsic log-normal scatter of 21% ± 11% in Y (SZ) at a fixed mass. Measuring Y (SZ) within a 0.3 Mpc projected radius (equivalent to 0.'75 at the survey median redshift z = 0.6), we find a scatter of 26% ± 9%. Prior to this study, the SPT observable found to have the lowest scatter with mass was cluster detection significance. We demonstrate, from both simulations and SPT observed clusters that Y (SZ) measured within an aperture comparable to the SPT beam size is equivalent, in terms of scatter with cluster mass, to SPT cluster detection significance.

  5. Delft Cluster Railway transition zones & Switches: Factual report short-term measurement 2009

    NARCIS (Netherlands)

    Hölscher, P.; Hartman, A.D.

    2009-01-01

    For the Delft Cluster 'Railway transition zones and switches' project, extensive measurements are made. The measurements are divided into three types. The short-term measurement of may 2009 is the subject of this report. The long-term and soil investigation measurements are described in other report

  6. A Raspberry Pi Cluster Instrumented for Fine-Grained Power Measurement

    Directory of Open Access Journals (Sweden)

    Michael F. Cloutier

    2016-09-01

    Full Text Available Power consumption has become an increasingly important metric when building large supercomputing clusters. One way to reduce power usage in large clusters is to use low-power embedded processors rather than the more typical high-end server CPUs (central processing units. We investigate various power-related metrics for seventeen different embedded ARM development boards in order to judge the appropriateness of using them in a computing cluster. We then build a custom cluster out of Raspberry Pi boards, which is specially designed for per-node detailed power measurement. In addition to serving as an embedded cluster testbed, our cluster’s power measurement, visualization and thermal features make it an excellent low-cost platform for education and experimentation.

  7. Testing ASTRO-H Measurements of Bulk and Turbulent Gas Motions in Galaxy Clusters

    CERN Document Server

    Ota, Naomi; Lau, Erwin T

    2015-01-01

    Gas motions in galaxy clusters play important roles in determining the properties of the intracluster medium (ICM) and constraining cosmological parameters using X-ray and Sunyaev-Zel'dovich effect observations of galaxy clusters. The upcoming ASTRO-H mission, equipped with high-resolution X-ray spectrometer, will make the first direct measurements of gas motions in galaxy clusters through measurements of Doppler shifting and broadening of emission lines. However, the physical interpretation of the data will be challenging due to the complex thermal and velocity structures of the ICM. In this work, we investigate how well we can measure bulk and turbulent gas motions in the ICM with ASTRO-H, by analyzing mock ASTRO-H simulations of galaxy clusters extracted from cosmological hydrodynamic simulations. We assess how photon counts, spectral fitting methods, multiphase ICM structure, deprojections, and region selection affect the measurements of gas motions. We show that while ASTRO-H is capable of recovering the...

  8. Investigation of IrO2/Pt Electrocatalysts in Unitized Regenerative Fuel Cells

    Directory of Open Access Journals (Sweden)

    V. Baglio

    2011-01-01

    Full Text Available IrO2/Pt catalysts (at different concentrations were synthesized by incipient wetness technique and characterized by XRD, XRF, and SEM. Water electrolysis/fuel cell performances were evaluated in a 5 cm2 single cell under Unitized Regenerative Fuel Cell (URFC configuration. The IrO2/Pt composition of 14/86 showed the highest performance for water electrolysis and the lowest one as fuel cell. It is derived that for fuel cell operation an excess of Pt favours the oxygen reduction process whereas IrO2 promotes oxygen evolution. From the present results, it appears that the diffusion characteristics and the reaction rate in fuel cell mode are significantly lower than in the electrolyser mode. This requires the enhancement of the gas diffusion properties of the electrodes and the catalytic properties for cathode operation in fuel cells.

  9. Fault-tolerant measurement-based quantum computing with continuous-variable cluster states.

    Science.gov (United States)

    Menicucci, Nicolas C

    2014-03-28

    A long-standing open question about Gaussian continuous-variable cluster states is whether they enable fault-tolerant measurement-based quantum computation. The answer is yes. Initial squeezing in the cluster above a threshold value of 20.5 dB ensures that errors from finite squeezing acting on encoded qubits are below the fault-tolerance threshold of known qubit-based error-correcting codes. By concatenating with one of these codes and using ancilla-based error correction, fault-tolerant measurement-based quantum computation of theoretically indefinite length is possible with finitely squeezed cluster states.

  10. Electrochemical characterization of IrO{sub 2}-Pt and RuO{sub 2}-Pt mixtures as bifunctional electrodes for unitized regenerative fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Escalante-Garcia, I.L.; Duron-Torres, S.M. [Univ. Autonoma de Zacatecas, Zacatecas (Mexico). Unidad Academica de Ciencias Quimicas; Cruz, J.C.; Arriaga-Hurtado, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Pedro Escobedo (Mexico)

    2010-07-15

    A unitized regenerative fuel cell (URFC) is a single electrochemical cell that has the potential to meet the required features of an idealized energy cycle whereby hydrogen can be produced from renewable energy sources. A URFC is a system which can operate as a polymer electrolyte water electrolyzer (PEMWE) or as a polymer electrolyte fuel cell (PEMFC). In the PEMWE mode, water is converted into hydrogen and oxygen by using electricity from solar or wind energy. In the PEMFC mode, the stored hydrogen and oxygen are supplied to generate electricity and water. Combining PEMWEs and PEMFCs remains a great challenge because several practical and structural features must be considered. The limiting reaction steps at the oxygen electrode for PEMFC or PEMWE are the oxygen reduction reaction (ORR) and the water oxidation reaction (OER), respectively. The high-efficiency therefore depends on the type of electrocatalysts and the capability of the oxygen electrode to operate under PEMFC or PEMWE conditions. As such, much research has gone into the development of a new oxygen electrode design for URFCs. Several bifunctional electrodes for OER and ORR were designed in this study using platinum (Pt) and iridium oxide (IrO{sub 2}) electrocatalysts or Pt and ruthenium oxide (RuO{sub 2}) supported electrocatalysts on Ebonex{sup R}. According to electrochemical characterization by CV, LV and EIS in aqueous 0.5 M H{sub 2}SO{sub 4}, IrO{sub 2}-Pt and RuO{sub 2}-Pt supported on Ebonex have high electrocatalytic properties for ORR and OER, indicating potential use in URFCs. IrO{sub 2} based electrodes were more stable than RuO{sub 2} based electrodes. 31 refs., 2 tabs., 6 figs.

  11. Spatial distribution and tunneling of H and D atoms in (NH{sub 4}){sub 2}PtCl{sub 6} and (ND{sub 4}){sub 2}PtCl{sub 6} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Onoda-Yamamuro, Noriko [Department of Natural Sciences, College of Science and Engineering, Tokyo Denki Univ., Hatoyama, Saitama (Japan); Yamamuro, Osamu; Matsuo, Takasuke [Department of Chemistry, Graduate School of Science, Osaka Univ., Toyonaka, Osaka (Japan); Torii, Syuuki [Institute of Material Sciences, Univ. of Tsukuba, Tsukuba, Ibaraki (Japan); Kamiyama, Takashi [Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan); Kume, Yoshio [Department of Basic Science, Azabu Univ., Sagamihara, Kanagawa (Japan)

    2001-03-01

    Neutron powder diffraction experiments on (NH{sub 4}){sub 2}PtCl{sub 6} and (ND{sub 4}){sub 2}PtCl{sub 6} have been performed using the time-of-flight high-resolution powder diffractometer Sirius at the pulsed cold neutron source in KEK. The Rietveld and Fourier analysis of the data collected at 6 K revealed that the hydrogen atom in (NH{sub 4}){sub 2}PtCl{sub 6} is located about the three-fold axis with three distinct maxima of the distribution function. The result is interpreted in terms of the rotational tunneling of NH{sub 4}{sup +}. (author)

  12. Universality of quantum computation with cluster states and (X, Y)-plane measurements

    Science.gov (United States)

    Mantri, Atul; Demarie, Tommaso F.; Fitzsimons, Joseph F.

    2017-01-01

    Measurement-based quantum computing (MBQC) is a model of quantum computation where quantum information is coherently processed by means of projective measurements on highly entangled states. Following the introduction of MBQC, cluster states have been studied extensively both from the theoretical and experimental point of view. Indeed, the study of MBQC was catalysed by the realisation that cluster states are universal for MBQC with (X, Y)-plane and Z measurements. Here we examine the question of whether the requirement for Z measurements can be dropped while maintaining universality. We answer this question in the affirmative by showing that universality is possible in this scenario. PMID:28216652

  13. ClusTrack: feature extraction and similarity measures for clustering of genome-wide data sets.

    Directory of Open Access Journals (Sweden)

    Halfdan Rydbeck

    Full Text Available Clustering is a popular technique for explorative analysis of data, as it can reveal subgroupings and similarities between data in an unsupervised manner. While clustering is routinely applied to gene expression data, there is a lack of appropriate general methodology for clustering of sequence-level genomic and epigenomic data, e.g. ChIP-based data. We here introduce a general methodology for clustering data sets of coordinates relative to a genome assembly, i.e. genomic tracks. By defining appropriate feature extraction approaches and similarity measures, we allow biologically meaningful clustering to be performed for genomic tracks using standard clustering algorithms. An implementation of the methodology is provided through a tool, ClusTrack, which allows fine-tuned clustering analyses to be specified through a web-based interface. We apply our methods to the clustering of occupancy of the H3K4me1 histone modification in samples from a range of different cell types. The majority of samples form meaningful subclusters, confirming that the definitions of features and similarity capture biological, rather than technical, variation between the genomic tracks. Input data and results are available, and can be reproduced, through a Galaxy Pages document at http://hyperbrowser.uio.no/hb/u/hb-superuser/p/clustrack. The clustering functionality is available as a Galaxy tool, under the menu option "Specialized analyzis of tracks", and the submenu option "Cluster tracks based on genome level similarity", at the Genomic HyperBrowser server: http://hyperbrowser.uio.no/hb/.

  14. Towards an Evaluation of Air Surveillance Track Clustering Algorithms via External Cluster Quality Measures

    Science.gov (United States)

    2013-01-01

    output. This function is referred to as PRM (for "Peak Rolling Mean") in the following table. By combining these track separation measures with the...9.39 5 1055 Mean-60k 60 km 403 10.28 5 858 Mean-70k 70 km 369 11.62 6 712 Mean-80k Simple Mean n/a 80 km 350 12.54 6 611 PRM :50-30k 30 km 427...7.49 4 1801 PRM :50-40k 40 km 375 6.79 4 2454 PRM :50-50k 50 km 405 7.06 4 2139 PRM :50-60k 60 km 412 7.46 4 1928 PRM :50-70k 70 km 427 7.76 4 1685

  15. The optical measurement of large cluster tracks in a gas jet

    Science.gov (United States)

    Chen, Zhiyuan; Liu, Dong; Han, Jifeng; Bai, Lixin

    2016-08-01

    We propose an optical method based on Rayleigh scattering for the direct measurement of cluster tracks produced by a high-pressure gas jet. The tracks of the argon and methane clusters are acquired by a high-speed camera. It is found that the cluster sizes of these tracks are within the range of 7E + 03~1E + 07 for argon and 2E + 06~4E + 08 for methane. Most argon tracks are continuous and their intensity changes gradually, while the majority of the methane tracks are separated into discrete fractions and their intensity alters periodically along the flight path, which may indicate the methane clusters are more unstable and easily to break up. Special methane clusters which may fly at an axial velocity of less than 2.5m/s are also found. This method is very sensitive to large gas cluster and has broad application prospects in cluster physics.

  16. Cluster evaluation of Brazilian and Moroccan goat populations using physical measurements

    Directory of Open Access Journals (Sweden)

    Luanna Chácara Pires

    2013-10-01

    Full Text Available The aim of this study was to compare the genetic diversity of 12 populations of goats in Brazil and Morocco (n = 796 through the use of physical measurements and different multivariate techniques. Traits measured included wither height (WH, distance from the brisket to the ground (BH and ear length (EL. The standardized Euclidean distance (D was adopted. The D values were submitted to clustering analysis using hierarchical methods (from nearest neighbor and UPGMA - Unweighted Pair Group Method with Arithmetic Mean and the numbers of clusters were analyzed using the Tocher optimization method. The population clustering was different depending on the method of analysis used. Among the hierarchical methods, UPGMA showed the best fit (CCC = 0.82. The Tocher method enabled the formation of four different clusters. Although the hierarchical and Tocher methods resulted in different cluster formations, both contributed to the interpretation of the genetic cluster divergence. The results obtained through UPGMA and Tocher optimization enable their use for future studies that may include a larger number of biometric variables on greater numbers of individuals and additional populations.

  17. Scattering of emission lines in galaxy cluster cores: measuring electron temperature

    CERN Document Server

    Khedekar, S; Sazonov, S; Sunyaev, R; Emsellem, E

    2014-01-01

    The central galaxies of some clusters can be strong emitters in the Ly$\\alpha$ and H$\\alpha$ lines. This emission may arise either from the cool/warm gas located in the cool core of the cluster or from the bright AGN within the central galaxy. The luminosities of such lines can be as high as $10^{42} - 10^{44}$ erg/s. This emission originating from the core of the cluster will get Thomson scattered by hot electrons of the intra-cluster medium (ICM) with an optical depth $\\sim$ 0.01 giving rise to very broad ($\\Delta \\lambda / \\lambda \\sim$ 15%) features in the scattered spectrum. We discuss the possibility of measuring the electron density and temperature using information on the flux and width of the highly broadened line features.

  18. Precision Measurements of the Cluster Red Sequence using an Error Corrected Gaussian Mixture Model

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Jiangang; /Fermilab /Michigan U.; Koester, Benjamin P.; /Chicago U.; Mckay, Timothy A.; /Michigan U.; Rykoff, Eli S.; /UC, Santa Barbara; Rozo, Eduardo; /Ohio State U.; Evrard, August; /Michigan U.; Annis, James; /Fermilab; Becker, Matthew; /Chicago U.; Busha, Michael; /KIPAC, Menlo Park /SLAC; Gerdes, David; /Michigan U.; Johnston, David E.; /Northwestern U. /Brookhaven

    2009-07-01

    The red sequence is an important feature of galaxy clusters and plays a crucial role in optical cluster detection. Measurement of the slope and scatter of the red sequence are affected both by selection of red sequence galaxies and measurement errors. In this paper, we describe a new error corrected Gaussian Mixture Model for red sequence galaxy identification. Using this technique, we can remove the effects of measurement error and extract unbiased information about the intrinsic properties of the red sequence. We use this method to select red sequence galaxies in each of the 13,823 clusters in the maxBCG catalog, and measure the red sequence ridgeline location and scatter of each. These measurements provide precise constraints on the variation of the average red galaxy populations in the observed frame with redshift. We find that the scatter of the red sequence ridgeline increases mildly with redshift, and that the slope decreases with redshift. We also observe that the slope does not strongly depend on cluster richness. Using similar methods, we show that this behavior is mirrored in a spectroscopic sample of field galaxies, further emphasizing that ridgeline properties are independent of environment. These precise measurements serve as an important observational check on simulations and mock galaxy catalogs. The observed trends in the slope and scatter of the red sequence ridgeline with redshift are clues to possible intrinsic evolution of the cluster red-sequence itself. Most importantly, the methods presented in this work lay the groundwork for further improvements in optically-based cluster cosmology.

  19. Measuring Baryon Acoustic Oscillations from the clustering of voids

    CERN Document Server

    Liang, Yu; Chuang, Chia-Hsun; Kitaura, Francisco-Shu; Tao, Charling

    2015-01-01

    We investigate the necessary methodology to optimally measure the baryon acoustic oscillation (BAO) signal, from voids based on galaxy redshift catalogues. To this end, we study the dependency of the BAO signal on the population of voids classified by their sizes. We find for the first time the characteristic features of the correlation function of voids including the first robust detection of BAOs in mock galaxy catalogues. These show an anti-correlation around the scale corresponding to the smallest size of voids in the sample (the void exclusion effect), and dips at both sides of the BAO peak, which can be used to determine the significance of the BAO signal without any priori model. Furthermore, our analysis demonstrates that there is a scale dependent bias for different populations of voids depending on the radius, with the peculiar property that the void population with the largest BAO significance corresponds to tracers with approximately zero bias on the largest scales. We further investigate the meth...

  20. Two-level Robust Measurement Fusion Kalman Filter for Clustering Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng; QI Wen-Juan; DENG Zi-Li

    2014-01-01

    This paper investigates the distributed fusion Kalman filtering over clustering sensor networks. The sensor network is partitioned as clusters by the nearest neighbor rule and each cluster consists of sensing nodes and cluster-head. Using the minimax robust estimation principle, based on the worst-case conservative system with the conservative upper bounds of noise variances, two-level robust measurement fusion Kalman filter is presented for the clustering sensor network systems with uncertain noise variances. It can significantly reduce the communication load and save energy when the number of sensors is very large. A Lyapunov equation approach for the robustness analysis is presented, by which the robustness of the local and fused Kalman filters is proved. The concept of the robust accuracy is presented, and the robust accuracy relations among the local and fused robust Kalman filters are proved. It is proved that the robust accuracy of the two-level weighted measurement fuser is equal to that of the global centralized robust fuser and is higher than those of each local robust filter and each local weighted measurement fuser. A simulation example shows the correctness and effectiveness of the proposed results.

  1. Satellite quenching time-scales in clusters from projected phase space measurements matched to simulated orbits

    Science.gov (United States)

    Oman, Kyle A.; Hudson, Michael J.

    2016-12-01

    We measure the star formation quenching efficiency and time-scale in cluster environments. Our method uses N-body simulations to estimate the probability distribution of possible orbits for a sample of observed Sloan Digital Sky Survey galaxies in and around clusters based on their position and velocity offsets from their host cluster. We study the relationship between their star formation rates and their likely orbital histories via a simple model in which star formation is quenched once a delay time after infall has elapsed. Our orbit library method is designed to isolate the environmental effect on the star formation rate due to a galaxy's present-day host cluster from `pre-processing' in previous group hosts. We find that quenching of satellite galaxies of all stellar masses in our sample (109-10^{11.5}M_{⊙}) by massive (> 10^{13} M_{⊙}) clusters is essentially 100 per cent efficient. Our fits show that all galaxies quench on their first infall, approximately at or within a Gyr of their first pericentric passage. There is little variation in the onset of quenching from galaxy-to-galaxy: the spread in this time is at most ˜2 Gyr at fixed M*. Higher mass satellites quench earlier, with very little dependence on host cluster mass in the range probed by our sample.

  2. Non-parametric method for measuring gas inhomogeneities from X-ray observations of galaxy clusters

    CERN Document Server

    Morandi, Andrea; Cui, Wei

    2013-01-01

    We present a non-parametric method to measure inhomogeneities in the intracluster medium (ICM) from X-ray observations of galaxy clusters. Analyzing mock Chandra X-ray observations of simulated clusters, we show that our new method enables the accurate recovery of the 3D gas density and gas clumping factor profiles out to large radii of galaxy clusters. We then apply this method to Chandra X-ray observations of Abell 1835 and present the first determination of the gas clumping factor from the X-ray cluster data. We find that the gas clumping factor in Abell 1835 increases with radius and reaches ~2-3 at r=R_{200}. This is in good agreement with the predictions of hydrodynamical simulations, but it is significantly below the values inferred from recent Suzaku observations. We further show that the radially increasing gas clumping factor causes flattening of the derived entropy profile of the ICM and affects physical interpretation of the cluster gas structure, especially at the large cluster-centric radii. Our...

  3. Reactions of R(2)P-P(SiMe(3))Li with [(R'(3)P)(2)PtCl(2)]. A general and efficient entry to phosphanylphosphinidene complexes of platinum. Syntheses and structures of [(eta(2)-P=(i)Pr(2))Pt(p-Tol(3)P)(2)], [(eta(2)-P=(t)Bu(2))Pt(p-Tol(3)P)(2)], [{eta(2)-P=(N(i)Pr(2))(2)}Pt(p-Tol(3)P)(2)] and [{(Et(2)PhP)(2)Pt}(2)P(2)].

    Science.gov (United States)

    Domańska-Babul, Wioleta; Chojnacki, Jaroslaw; Matern, Eberhard; Pikies, Jerzy

    2009-01-07

    The reactions of lithium derivatives of diphosphanes R(2)P-P(SiMe(3))Li (R = (t)Bu, (i)Pr, Et(2)N and (i)Pr(2)N) with [(R'(3)P)(2)PtCl(2)] (R'(3)P = Et(3)P, Et(2)PhP, EtPh(2)P and p-Tol(3)P) proceed in a facile manner to afford side-on bonded phosphanylphosphinidene complexes of platinum [(eta(2)-P=R(2))Pt(PR'(3))(2)]. The related reactions of Ph(2)P-P(SiMe(3))Li with [(R'(3)P)(2)PtCl(2)] did not yield [(eta(2)-P=PPh(2))Pt(PR'(3))(2)] and resulted mainly in the formation of [{(R'(3)P)(2)Pt}(2)P(2)], Ph(2)P-PLi-PPh(2), (Me(3)Si)(2)PLi and (Me(3)Si)(3)P. Crystallographic data are reported for the compounds [(eta(2)-P=R(2))Pt(p-Tol(3)P)(2)] (R = (t)Bu, (i)Pr, ((i)Pr(2)N)(2)P) and for [{(Et(2)PhP)(2)Pt}(2)P(2)].

  4. A New Distance Measurement to NGC 4874 in the Coma Cluster

    Science.gov (United States)

    Bartier, Crystal-Lynn; Jensen, Joseph; Blakeslee, John

    2017-01-01

    By measuring distances to remote galaxies we can determine the size, expansion rate, and age of the Universe. One of the best ways to measure distance is known as surface brightness fluctuations (SBF). The purpose of this research is to improve the current distance to the Coma Cluster by making accurate SBF distance measurements to two galaxies, NGC 4874 and NGC 4921. We analyzed HST WFC3 images in the F110W and F160W bands for NGC 4874 and ACS F814W and F606W for NGC 4921. Although NGC 4921 has a Cepheid distance measurement, we were unable to make an SBF measurement to NGC 4921 due to the presence of dust and young stars. The results of the distance measurement to NGC 4874 will be compared with previous distance measurements for the Coma Cluster. We also present a comparison of the globular cluster luminosity function for NGC 4874 measured using Source Extractor and a modified version of Dophot to help determine the photometric accuracy of our measurements in the presence of the bright galaxy background.

  5. Comprehensive Measurement for Carrying Capacity of Resources and Environment of City Clusters in Central China

    Institute of Scientific and Technical Information of China (English)

    FANG Chuanglin; LIU Xiaoli

    2010-01-01

    Studying the carrying capacity of resources and environment of city clusters in the central China has impor-tant practical guidance significance for promoting the healthy,sustainable and stable development of this region.Ac-cording to their influencing factors and reciprocity mechanism,using system dynamics approaches,this paper built a SD model for measuring the carrying capacity of resources and environment of the city clusters in the central China,and through setting different development models,the comprehensive measurement analysis on the carrying capacity was carried out.The results show that the model of promoting socio-economic development under the protection of resources and environment is the optimal model for promoting the harmony development of resources,environment,society and economy in the city clusters.According to this model,the optimum population scale of the city clusters in2020 is 42.80×106 persons,and the moderate economic development scale is 22.055× 1012 yuan(RMB).In 1996-2020,the carrying capacity of resources and environment in the city clusters took on obvious phase-change characteristics.During the studied period,it is basically at the initial development stage,and will come through the development process from slow development to speedup development.

  6. Standardized Effect Size Measures for Mediation Analysis in Cluster-Randomized Trials

    Science.gov (United States)

    Stapleton, Laura M.; Pituch, Keenan A.; Dion, Eric

    2015-01-01

    This article presents 3 standardized effect size measures to use when sharing results of an analysis of mediation of treatment effects for cluster-randomized trials. The authors discuss 3 examples of mediation analysis (upper-level mediation, cross-level mediation, and cross-level mediation with a contextual effect) with demonstration of the…

  7. HLM in Cluster-Randomised Trials--Measuring Efficacy across Diverse Populations of Learners

    Science.gov (United States)

    Hegedus, Stephen; Tapper, John; Dalton, Sara; Sloane, Finbarr

    2013-01-01

    We describe the application of Hierarchical Linear Modelling (HLM) in a cluster-randomised study to examine learning algebraic concepts and procedures in an innovative, technology-rich environment in the US. HLM is applied to measure the impact of such treatment on learning and on contextual variables. We provide a detailed description of such…

  8. Deterministic Secure Quantum Communication with Cluster State and Bell-Basis Measurements

    Institute of Scientific and Technical Information of China (English)

    YUAN Hao; HE Qin; HU Xiao-Yuan; HOU Kui; HAN Lian-Fang; SHI Shou-Hua

    2008-01-01

    We present a novel protocol for deterministic secure quantum communication by using the four-qubit cluster state as quantum channel. It is shown that two legitimate users can directly transmit the secret messages based on Bell-basis measurements and classical communication. The present protocol makes use of the ideas of block transmission and decoy particle checking technique. It has a high capacity as each cluster state can carry two bits of information, and has a high intrinsic efficiency because almost all the instances except the decoy checking particles (its number is negligible) are useful. Furthermore, this protocol is feasible with present-day technique.

  9. Prospects for clustering and lensing measurements with forthcoming intensity mapping and optical surveys

    CERN Document Server

    Pourtsidou, Alkistis; Crittenden, Robert; Metcalf, R Benton

    2015-01-01

    We explore the potential of using intensity mapping surveys (MeerKAT, SKA) and optical galaxy surveys (DES, LSST) to detect HI clustering and weak gravitational lensing of 21cm emission in auto- and cross-correlation. Our forecasts show that high precision measurements of the clustering and lensing signals can be made in the near future using the intensity mapping technique. Such studies can be used to test the intensity mapping method, and constrain parameters such as the HI density $\\Omega_{\\rm HI}$, the HI bias $b_{\\rm HI}$ and the galaxy-HI correlation coefficient $r_{\\rm HI-g}$.

  10. Prospects for clustering and lensing measurements with forthcoming intensity mapping and optical surveys

    Science.gov (United States)

    Pourtsidou, A.; Bacon, D.; Crittenden, R.; Metcalf, R. B.

    2016-06-01

    We explore the potential of using intensity mapping surveys (MeerKAT, SKA) and optical galaxy surveys (DES, LSST) to detect H I clustering and weak gravitational lensing of 21 cm emission in auto- and cross-correlation. Our forecasts show that high-precision measurements of the clustering and lensing signals can be made in the near future using the intensity mapping technique. Such studies can be used to test the intensity mapping method, and constrain parameters such as the H I density Ω _{H I}, the H I bias b_{H I} and the galaxy-H I correlation coefficient r_{H I-g}.

  11. Ionization-cluster distributions of alpha-particles in nanometric volumes of propane: measurement and calculation.

    Science.gov (United States)

    De Nardo, L; Colautti, P; Conte, V; Baek, W Y; Grosswendt, B; Tornielli, G

    2002-12-01

    The probability of the formation of ionization clusters by primary alpha-particles at 5.4 MeV in nanometric volumes of propane was studied experimentally and by Monte Carlo simulation, as a function of the distance between the center line of the particle beam and the center of the target volume. The volumes were of cylindrical shape, 3.7 mm in diameter and height. As the investigations were performed at gas pressures of 300 Pa and 350 Pa, the dimensions of the target volume were equivalent to 20.6 nm or 24.0 nm in a material of density 1.0 g/cm(3). The dependence of ionization-cluster formation on distance was studied up to values equivalent to about 70 nm. To validate the measurements, a Monte Carlo model was developed which allows the experimental arrangement and the interactions of alpha-particles and secondary electrons in the counter gas to be properly simulated. This model is supplemented by a mathematical formulation of cluster size formation in nanometric targets. The main results of our study are (i) that the mean ionization-cluster size in the delta-electron cloud of an alpha-particle track segment, decreases as a function of the distance between the center line of the alpha-particle beam and the center of the sensitive target volume to the power of 2.6, and (ii) that the mean cluster size in critical volumes and the relative variance of mean cluster size due to delta-electrons are invariant at distances greater than about 20 nm. We could imagine that the ionization-cluster formation in nanometric volumes might in future provide the physical basis for a redefinition of radiation quality.

  12. Efficient photodegradation of methyl violet dye using TiO2/Pt and TiO2/Pd photocatalysts

    Science.gov (United States)

    Saeed, Khalid; Khan, Idrees; Gul, Tamanna; Sadiq, Mohammad

    2017-02-01

    Titanium oxide supported palladium (TiO2/Pd) and titanium oxide supported platinum (TiO2/Pt) nanoparticles were prepared from their precursors through the incipient wetness method. The TiO2/Pd and TiO2/Pt nanoparticles were characterized by scanning electron microscopy (SEM), and energy dispersive X-rays (EDX), while the photodegradation study of methyl violet was performed by UV/VIS spectrophotometry. The morphological study shows that the Pd and Pt were well deposited on the surface of TiO2, which was confirmed by EDX. Both TiO2/Pd and TiO2/Pt nanoparticles were used as photocatalysts for the photodegradation of methyl violet in aqueous media under UV-light irradiation. The photodegradation study revealed that the TiO2/Pd and TiO2/Pt nanoparticles degraded about 95 and 78% of dye within 20 min, respectively. The effect of various parameters such as catalyst dosage, concentration of dye, and medium on the photocatalytic degradation was examined. The activity of recovered TiO2/Pd and TiO2/Pt nanoparticles was studied.

  13. Using SVD on Clusters to Improve Precision of Interdocument Similarity Measure.

    Science.gov (United States)

    Zhang, Wen; Xiao, Fan; Li, Bin; Zhang, Siguang

    2016-01-01

    Recently, LSI (Latent Semantic Indexing) based on SVD (Singular Value Decomposition) is proposed to overcome the problems of polysemy and homonym in traditional lexical matching. However, it is usually criticized as with low discriminative power for representing documents although it has been validated as with good representative quality. In this paper, SVD on clusters is proposed to improve the discriminative power of LSI. The contribution of this paper is three manifolds. Firstly, we make a survey of existing linear algebra methods for LSI, including both SVD based methods and non-SVD based methods. Secondly, we propose SVD on clusters for LSI and theoretically explain that dimension expansion of document vectors and dimension projection using SVD are the two manipulations involved in SVD on clusters. Moreover, we develop updating processes to fold in new documents and terms in a decomposed matrix by SVD on clusters. Thirdly, two corpora, a Chinese corpus and an English corpus, are used to evaluate the performances of the proposed methods. Experiments demonstrate that, to some extent, SVD on clusters can improve the precision of interdocument similarity measure in comparison with other SVD based LSI methods.

  14. Using SVD on Clusters to Improve Precision of Interdocument Similarity Measure

    Directory of Open Access Journals (Sweden)

    Wen Zhang

    2016-01-01

    Full Text Available Recently, LSI (Latent Semantic Indexing based on SVD (Singular Value Decomposition is proposed to overcome the problems of polysemy and homonym in traditional lexical matching. However, it is usually criticized as with low discriminative power for representing documents although it has been validated as with good representative quality. In this paper, SVD on clusters is proposed to improve the discriminative power of LSI. The contribution of this paper is three manifolds. Firstly, we make a survey of existing linear algebra methods for LSI, including both SVD based methods and non-SVD based methods. Secondly, we propose SVD on clusters for LSI and theoretically explain that dimension expansion of document vectors and dimension projection using SVD are the two manipulations involved in SVD on clusters. Moreover, we develop updating processes to fold in new documents and terms in a decomposed matrix by SVD on clusters. Thirdly, two corpora, a Chinese corpus and an English corpus, are used to evaluate the performances of the proposed methods. Experiments demonstrate that, to some extent, SVD on clusters can improve the precision of interdocument similarity measure in comparison with other SVD based LSI methods.

  15. Cross-correlation Weak Lensing of SDSS Galaxy Clusters I: Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sheldon, Erin S.; Johnston, David E.; Scranton, Ryan; Koester, Ben P.; McKay, Timothy A.; Oyaizu, Hiroaki; Cunha, Carlos; Lima, Marcos; Lin, Huan; Frieman, Joshua A.; Wechsler, Risa H.; Annis, James; Mandelbaum, Rachel; Bahcall, Neta A.; Fukugita, Masataka

    2007-09-28

    This is the first in a series of papers on the weak lensing effect caused by clusters of galaxies in Sloan Digital Sky Survey. The photometrically selected cluster sample, known as MaxBCG, includes {approx}130,000 objects between redshift 0.1 and 0.3, ranging in size from small groups to massive clusters. We split the clusters into bins of richness and luminosity and stack the surface density contrast to produce mean radial profiles. The mean profiles are detected over a range of scales, from the inner halo (25 kpc/h) well into the surrounding large scale structure (30 Mpc/h), with a significance of 15 to 20 in each bin. The signal over this large range of scales is best interpreted in terms of the cluster-mass cross-correlation function. We pay careful attention to sources of systematic error, correcting for them where possible and bounding them where not. We find that the profiles scale strongly with richness and luminosity. We find the signal within a given richness bin depends upon luminosity, suggesting that luminosity is more closely correlated with mass than galaxy counts. We split the samples by redshift but detect no significant evolution. The profiles are not well described by power laws. In a subsequent series of papers we invert the profiles to three-dimensional mass profiles, show that they are well fit by a halo model description, measure mass-to-light ratios and provide a cosmological interpretation.

  16. Detection of universality of dark matter profile from Subaru weak lensing measurements of 50 massive clusters

    CERN Document Server

    Niikura, Hiroko; Okabe, Nobuhiro; Martino, Rossella; Takahashi, Ryuichi

    2015-01-01

    We develop a novel method of measuring the lensing distortion profiles of clusters with stacking the scaled amplitudes of background galaxy ellipticities as a function of the scaled centric radius according to the NFW prediction of each cluster, based on the assumption that the different clusters in a sample follow the universal NFW profile. First we demonstrate the feasibility of this method using both the analytical NFW model and simulated halos in high-resolution $N$-body simulations. We then apply, as a proof of concept, this method to the Subaru weak lensing data and the XMM/Chandra X-ray observables for a sample of 50 massive clusters in the redshift range $0.15\\le z\\le 0.3$, where their halo masses range over an order of magnitude. To estimate the NFW parameters of each cluster, we use the halo mass proxy relation of X-ray observables, based on either the hydrostatic equilibrium or the gas mass, and then infer the halo concentration from the model $c(M)$ relation. We evaluate a performance of the NFW s...

  17. Satellite quenching timescales in clusters from projected phase space measurements matched to simulated orbits

    CERN Document Server

    Oman, Kyle A

    2016-01-01

    We measure the star formation quenching efficiency and timescale in cluster environments. Our method uses N-body simulations to estimate the probability distribution of possible orbits for a sample of observed SDSS galaxies in and around clusters based on their position and velocity offsets from their host cluster. We study the relationship between their star formation rates and their likely orbital histories via a simple model in which star formation is quenched once a delay time after infall has elapsed. Our orbit library method is designed to isolate the environmental effect on the star formation rate due to a galaxy's present-day host cluster from `pre-processing' in previous group hosts. We find that quenching of satellite galaxies of all stellar masses in our sample ($10^{9}-10^{11.5}\\,{\\rm M}_\\odot$) by massive ($> 10^{13}\\,{\\rm M}_\\odot$) clusters is essentially $100$ per cent efficient. Our fits show that all galaxies quench on their first infall, approximately at or within a Gyr of their first peric...

  18. Physical Properties of (NH4)2Pt(CN)4[Clo.42].3H2O: A new Quasi-One-Dimensional Conductor

    DEFF Research Database (Denmark)

    Carneiro, Kim; Petersen, A. S.; Underhill, A. E.;

    1979-01-01

    The quasi-one-dimensional conductor (NH4)2[Pt(CN)4]Cl0.42·3H2O, ACP(Cl), has been studied experimentally by means of electrical conduction measurements, x-ray diffuse scattering, and neutron inelastic scattering. This allows the determination of all the physical parameters of interest for the the......The quasi-one-dimensional conductor (NH4)2[Pt(CN)4]Cl0.42·3H2O, ACP(Cl), has been studied experimentally by means of electrical conduction measurements, x-ray diffuse scattering, and neutron inelastic scattering. This allows the determination of all the physical parameters of interest...... to drop, and second, an increased Fermi wave vector kF introduces a change in the electron-phonon coupling constant λ via the bare phonon frequency ω(2kF). Third, the interchain coupling η is enhanced in ACP(Cl), which seems to be related to the hydrogen bonding of the NH4+ ions. We also present...

  19. Quantifying Substructure Measures In X-ray Images of Galaxy Cluster Mergers With SLAM

    Science.gov (United States)

    Chatzikos, Marios; Sarazin, C. L.; O'Shea, B. W.

    2014-01-01

    I use the Simulation Library of Astrophysical galaxy cluster Mergers (SLAM) database to quantify the effects of mergers on X-ray observables. SLAM consists of a set of 156 adiabatic simulations of binary galaxy cluster mergers, that covers 2 orders of magnitude in the mass of the primary cluster, four values for the mass contrast, and four values for the angular momentum of the collision. In this talk I describe results on substructure measures obtained for various viewing angles. I have quantified the substructure in X-ray images using both center shifts and power ratios. Mergers of intermediate mass contrasts produce substructure signals that can persist in X-ray images for at least 1-2 sound crossing times. The amplitude of both measures depends strongly on the initial mass contrast. The measures for major mergers (mass contrast less than 3) appear to depend on the system mass, while for minor mergers (mass contrast between 3 and 10) they are generally independent of the system mass. Neither measure reflects the true dynamical state of the system closely, although the center shifts appear to be a better proxy. Comparisons with the virial and hydrostatic disequilibrium parameters reveal that there is no value of either substructure measure that unambiguously distinguishes merging from relaxing systems. Implications for SZE observations will also be discussed.

  20. Modeling for Formation of Conducting Path in Cu/SiO2/Pt Memory Devices: Based on Soft Breakdown Mechanism

    Science.gov (United States)

    Luo, J. M.

    2013-09-01

    The forming process before resistive switching in Cu/ SiO2/Pt memory devices, corresponding to the formation of conducting path, can be regarded as the dielectric soft breakdown. Based on the analysis of breakdown mechanism, a dynamic model combining the transition of Cu ions with the space-charge effect has been proposed, and demonstrates that the forming voltage depends on the thickness of oxide, the sweep rate of voltage and temperature. The predictions of the model are consistent with the experiment data reported in the literature and it is believed that the transition of Cu ions across the oxide and the accumulation of Cu ions at the SiO2/Pt interface could be responsible for the conductive path formation in Cu/SiO2/Pt memory devices.

  1. Testing X-ray Measurements of Galaxy Cluster Outskirts with Cosmological Simulations

    CERN Document Server

    Avestruz, Camille; Nagai, Daisuke; Vikhlinin, Alexey

    2014-01-01

    The study of galaxy cluster outskirts has emerged as one of the new frontiers in extragalactic astrophysics and cosmology with the advent of new observations in X-ray and microwave. However, the thermodynamic properties and chemical enrichment of this diffuse and azimuthally asymmetric component of the intra-cluster medium are still not well understood. This work, for the first time, systematically explores potential observational biases in these regions. To assess X-ray measurements of galaxy cluster properties at large radii ($>{R}_{500c}$), we use mock Chandra analyses of cosmological galaxy cluster simulations. The pipeline is identical to that used for Chandra observations, but the biases discussed in this paper are relevant for all X-ray observations outside of ${R}_{500c}$. We find the following from our analysis: (1) filament regions can contribute as much as a factor of 3 to the emission measure, (2) X-ray temperatures and metal abundances from model fitted mock X-ray spectra respectively vary to the...

  2. Weak Lensing Measurement of the Mass--Richness Relation of SDSS redMaPPer Clusters

    CERN Document Server

    Simet, Melanie; Mandelbaum, Rachel; Rozo, Eduardo; Rykoff, Eli; Sheldon, Erin; Wechsler, Risa H

    2016-01-01

    We perform a measurement of the mass--richness relation of the redMaPPer galaxy cluster catalogue using weak lensing data from the Sloan Digital Sky Survey. We have carefully characterized a broad range of systematic uncertainties, including shear calibration errors, photo-$z$ biases, dilution by member galaxies, source obscuration, magnification bias, incorrect assumptions about cluster mass profiles, cluster centering, halo triaxiality, and projection effects. We also compare measurements of the lensing signal from two independently-produced shear and photometric redshift catalogues to characterize systematic errors in the lensing signal itself. Using a sample of 5,570 clusters from $0.1\\le z\\le 0.33$, the normalization of our power-law mass vs.\\ $\\lambda$ relation is $\\log_{10}[M_{200m}/h^{-1}\\ M_{\\odot}]$ = $14.344 \\pm 0.021$ (statistical) $\\pm 0.023$ (systematic) at a richness $\\lambda=40$, a 7 per cent calibration uncertainty, with a power-law index of $1.33^{+0.09}_{-0.10}$ ($1\\sigma$). The detailed sy...

  3. Clustering of Sloan Digital Sky Survey III Photometric Luminous Galaxies: The Measurement, Systematics and Cosmological Implications

    CERN Document Server

    Ho, Shirley; Seo, Hee-Jong; de Putter, Roland; Ross, Ashley J; White, Martin; Padmanabhan, Nikhil; Saito, Shun; Schlegel, David J; Schlafly, Eddie; Seljak, Uros; Hernandez-Monteagudo, Carlos; Sanchez, Ariel G; Percival, Will J; Blanton, Michael; Skibba, Ramin; Schneider, Don; Reid, Beth; Mena, Olga; Viel, Matteo; Eisenstein, Daniel J; Prada, Francisco; Weaver, Benjamin; Bahcall, Neta; Bizyaev, Dimitry; Brewinton, Howard; Brinkman, Jon; da Costa, Luiz Nicolaci; Gott, John R; Malanushenko, Elena; Malanushenko, Viktor; Nichol, Bob; Oravetz, Daniel; Pan, Kaike; Palanque-Delabrouille, Nathalie; Ross, Nicholas P; Simmons, Audrey; de Simoni, Fernando; Snedden, Stephanie; Yeche, Christophe

    2012-01-01

    The Sloan Digital Sky Survey (SDSS) surveyed 14,555 square degrees, and delivered over a trillion pixels of imaging data. We present a study of galaxy clustering using 900,000 luminous galaxies with photometric redshifts, spanning between $z=0.45$ and $z=0.65$, constructed from the SDSS using methods described in Ross et al. (2011). This data-set spans 11,000 square degrees and probes a volume of $3h^{-3} \\rm{Gpc}^3$, making it the largest volume ever used for galaxy clustering measurements. We present a novel treatment of the observational systematics and its applications to the clustering signals from the data set. In this paper, we measure the angular clustering using an optimal quadratic estimator at 4 redshift slices with an accuracy of ~15% with bin size of delta_l = 10 on scales of the Baryon Acoustic Oscillations (BAO) (at l~40-400). We derive cosmological constraints using the full-shape of the power-spectra. For a flat Lambda CDM model, when combined with Cosmic Microwave Background Wilkinson Microw...

  4. Thermodynamics of liquids: standard molar entropies and heat capacities of common solvents from 2PT molecular dynamics.

    Science.gov (United States)

    Pascal, Tod A; Lin, Shiang-Tai; Goddard, William A

    2011-01-07

    We validate here the Two-Phase Thermodynamics (2PT) method for calculating the standard molar entropies and heat capacities of common liquids. In 2PT, the thermodynamics of the system is related to the total density of states (DoS), obtained from the Fourier Transform of the velocity autocorrelation function. For liquids this DoS is partitioned into a diffusional component modeled as diffusion of a hard sphere gas plus a solid component for which the DoS(υ) → 0 as υ→ 0 as for a Debye solid. Thermodynamic observables are obtained by integrating the DoS with the appropriate weighting functions. In the 2PT method, two parameters are extracted from the DoS self-consistently to describe diffusional contributions: the fraction of diffusional modes, f, and DoS(0). This allows 2PT to be applied consistently and without re-parameterization to simulations of arbitrary liquids. We find that the absolute entropy of the liquid can be determined accurately from a single short MD trajectory (20 ps) after the system is equilibrated, making it orders of magnitude more efficient than commonly used perturbation and umbrella sampling methods. Here, we present the predicted standard molar entropies for fifteen common solvents evaluated from molecular dynamics simulations using the AMBER, GAFF, OPLS AA/L and Dreiding II forcefields. Overall, we find that all forcefields lead to good agreement with experimental and previous theoretical values for the entropy and very good agreement in the heat capacities. These results validate 2PT as a robust and efficient method for evaluating the thermodynamics of liquid phase systems. Indeed 2PT might provide a practical scheme to improve the intermolecular terms in forcefields by comparing directly to thermodynamic properties.

  5. Segmentation of Mushroom and Cap width Measurement using Modified K-Means Clustering Algorithm

    Directory of Open Access Journals (Sweden)

    Eser Sert

    2014-01-01

    Full Text Available Mushroom is one of the commonly consumed foods. Image processing is one of the effective way for examination of visual features and detecting the size of a mushroom. We developed software for segmentation of a mushroom in a picture and also to measure the cap width of the mushroom. K-Means clustering method is used for the process. K-Means is one of the most successful clustering methods. In our study we customized the algorithm to get the best result and tested the algorithm. In the system, at first mushroom picture is filtered, histograms are balanced and after that segmentation is performed. Results provided that customized algorithm performed better segmentation than classical K-Means algorithm. Tests performed on the designed software showed that segmentation on complex background pictures is performed with high accuracy, and 20 mushrooms caps are measured with 2.281 % relative error.

  6. Cluster Forests

    CERN Document Server

    Yan, Donghui; Jordan, Michael I

    2011-01-01

    Inspired by Random Forests (RF) in the context of classification, we propose a new clustering ensemble method---Cluster Forests (CF). Geometrically, CF randomly probes a high-dimensional data cloud to obtain "good local clusterings" and then aggregates via spectral clustering to obtain cluster assignments for the whole dataset. The search for good local clusterings is guided by a cluster quality measure $\\kappa$. CF progressively improves each local clustering in a fashion that resembles the tree growth in RF. Empirical studies on several real-world datasets under two different performance metrics show that CF compares favorably to its competitors. Theoretical analysis shows that the $\\kappa$ criterion is shown to grow each local clustering in a desirable way---it is "noise-resistant." A closed-form expression is obtained for the mis-clustering rate of spectral clustering under a perturbation model, which yields new insights into some aspects of spectral clustering.

  7. Stretching dependence of the vibration modes of a single-molecule Pt-H-2-Pt bridge

    DEFF Research Database (Denmark)

    Djukic, D.; Thygesen, Kristian Sommer; Untiedt, C.

    2005-01-01

    isotope substitution is obtained. The stretching dependence for each of the modes allows uniquely classifying them as longitudinal or transversal modes. The interpretation of the experiment in terms of a Pt-H-2-Pt bridge is verified by density-functional theory calculations for the stability, vibrational...

  8. Electrochemical oxidation of ammonia-containing wastewater using Ti/RuO2-Pt electrode

    Directory of Open Access Journals (Sweden)

    Wei-wu HU

    2009-12-01

    Full Text Available The electrochemical oxidation degradation processes for artificial and actual wastewater containing ammonia were carried out with a Ti/RuO2-Pt anode and a Ti plate cathode. We studied the effects of different current densities, space sizes between the two electrodes, and amounts of added NaCl on ammonia-containing wastewater treatment. It was shown that, after a 30-min treatment under the optimal conditions, which were a current density of 20 mA/cm2, a space size between the two electrodes of 1 cm, and an added amount of 0.5 g/L of NaCl, the COD concentration in municipal wastewater was 40 mg/L, a removal rate of 90%; and the NH3-N concentration was 7 mg/L, a removal rate of 88.3%. The effluent of municipal wastewater qualified for Class A of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002.

  9. Synthesis of Platinum Nanoparticles from K2PtCl4 Solution Using Bacterial Cellulose Matrix

    Directory of Open Access Journals (Sweden)

    H. F. Aritonang

    2014-01-01

    Full Text Available Platinum (Pt nanoparticles have been synthesized from a precursor solution of potassium tetrachloroplatinate (K2PtCl4 using a matrix of bacterial cellulose (BC. The formation of Pt nanoparticles occurs at the surface and the inside of the BC membrane by reducing the precursor solution with a hydrogen gas reductant. The Pt nanoparticles obtained from the variations of precursor concentration, between 3 mM and 30 mM, and the formation of Pt nanoparticles have been studied using X-ray diffraction (XRD, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS, and thermogravimetry analysis (TGA. Based on X-ray diffraction patterns, Pt particles have sizes between 6.3 nm and 9.3 nm, and the Pt particle size increases with an increase in precursor concentration. The morphology of the Pt nanoparticles was observed by SEM-EDS and the content of Pt particles inside the membrane is higher than that on the surface of BC membranes. This analysis corresponds to the TGA analysis, but the TGA analysis is more representative in how it describes the content of Pt particles in the BC membrane.

  10. Magnetic field gradients inferred from multi-point measurements of Cluster FGM and EDI

    Science.gov (United States)

    Teubenbacher, Robert; Nakamura, Rumi; Giner, Lukas; Plaschke, Ferdinand; Baumjohann, Wolfgang; Magnes, Werner; Eichelberger, Hans; Steller, Manfred; Torbert, Roy

    2013-04-01

    We use Cluster data from fluxgate magnetometer (FGM) and electron drift instrument (EDI) to determine the magnetic field gradients in the near-Earth magnetotail. Here we use the magnetic field data from FGM measurements as well as the gyro-time data of electrons determined from the time of flight measurements of EDI. The results are compared with the values estimated from empirical magnetic field models for different magnetospheric conditions. We also estimated the spin axis offset of FGM based on comparison between EDI and FGM data and discuss the possible effect in determining the current sheet characteristics.

  11. Measuring the Mass Distribution in Z is Approximately 0.2 Cluster Lenses with XMM, HST and CFHT

    Science.gov (United States)

    2004-01-01

    Being the most massive gravitationally bound objects in the Universe, clusters of galaxies are prime targets for studies of structure formation and evolution. Specifically the comoving space density of virialized clusters of a given mass (or X-ray temperature), but also the frequency and degree of substructure, as well as the shape of the cluster mass profile are quantities whose current values and evolution as a function of lookback time can provide important constraints on the cosmological and physical parameters of structure formation theories. The project funded by NASA grant NAG 5-10041 intended to take such studies to a new level by combining observations of a well-selected cluster sample by three state-of-the-art telescopes: HST, to accurately measure the mass distribution in the cluster core (approx. 0.5 h(sup -1)(sub 50) Mpc) via strong gravitational lensing; CFHT, to measure the large scale mass distribution out to approx. 3 Mpc via weak lensing; and XMM, to measure the gas density and temperature distribution accurately on intermediate scales mass measurements through accurate, spatially resolved X-ray temperature measurements (particularly in the cosmologically most sensitive range of kT> 5 keV) is central to the questions outlined above. This set of observations promised to yield the best cluster mass measurements obtained so far for a representative sample, thus allowing us to: 1) Measure the high-mass end of the local cluster mass function; 2) Test predictions of a universal cluster mass profile; 3) calibrate the mass-temperature and temperature-luminosity relations for clusters and the scatter around these relations, which is vital for studies of cluster evolution using the X-ray temperature and X-ray luminosity functions.

  12. A MODIFIED ANT-BASED TEXT CLUSTERING ALGORITHM WITH SEMANTIC SIMILARITY MEASURE

    Institute of Scientific and Technical Information of China (English)

    Haoxiang XIA; Shuguang WANG; Taketoshi YOSHIDA

    2006-01-01

    Ant-based text clustering is a promising technique that has attracted great research attention. This paper attempts to improve the standard ant-based text-clustering algorithm in two dimensions. On one hand, the ontology-based semantic similarity measure is used in conjunction with the traditional vector-space-model-based measure to provide more accurate assessment of the similarity between documents. On the other, the ant behavior model is modified to pursue better algorithmic performance.Especially, the ant movement rule is adjusted so as to direct a laden ant toward a dense area of the same type of items as the ant's carrying item, and to direct an unladen ant toward an area that contains an item dissimilar with the surrounding items within its Moore neighborhood. Using WordNet as the base ontology for assessing the semantic similarity between documents, the proposed algorithm is tested with a sample set of documents excerpted from the Reuters-21578 corpus and the experiment results partly indicate that the proposed algorithm perform better than the standard ant-based text-clustering algorithm and the k-means algorithm.

  13. Sunyaev-Zel'dovich Cluster Profiles Measured with the South Pole Telescope

    CERN Document Server

    Plagge, T; Ade, P A R; Aird, K A; Bleem, L E; Carlstrom, J E; Chang, C L; Cho, H -M; Crawford, T M; Crites, A T; de Haan, T; Dobbs, M A; George, E M; Hall, N R; Halverson, N W; Holder, G P; Holzapfel, W L; Hrubes, J D; Joy, M; Keisler, R; Knox, L; Lee, A T; Leitch, E M; Lueker, M; Marrone, D; McMahon, J J; Mehl, J; Meyer, S S; Mohr, J J; Montroy, T E; Padin, S; Pryke, C; Reichardt, C L; Ruhl, J E; Schaffer, K K; Shaw, L; Shirokoff, E; Spieler, H G; Stalder, B; Staniszewski, Z; Stark, A A; Vanderlinde, K; Vieira, J D; Williamson, R; Zahn, O

    2009-01-01

    We present Sunyaev-Zel'dovich measurements of 15 massive X-ray selected galaxy clusters obtained with the South Pole Telescope. The Sunyaev-Zel'dovich (SZ) cluster signals are measured at 150 GHz, and concurrent 220 GHz data are used to reduce astrophysical contamination. Radial profiles are computed using a technique that takes into account the effects of the beams and filtering. In several clusters, significant SZ decrements are detected out to a substantial fraction of the virial radius. The profiles are fit to the beta model and to a generalized NFW pressure profile, and are scaled and stacked to probe their average behavior. We find model parameters that are consistent with previous studies: beta=0.86 and r_core/r_500 = 0.20 for the beta model, and (alpha, beta, gamma, c_500)=(1.0,5.5,0.5,1.0) for the generalized NFW model. Both models fit the SPT data comparably well, and both are consistent with the average SZ profile out to the virial radius. The integrated Compton-y parameter Y_SZ is computed for eac...

  14. Bayesian latent variable models for hierarchical clustered count outcomes with repeated measures in microbiome studies.

    Science.gov (United States)

    Xu, Lizhen; Paterson, Andrew D; Xu, Wei

    2017-04-01

    Motivated by the multivariate nature of microbiome data with hierarchical taxonomic clusters, counts that are often skewed and zero inflated, and repeated measures, we propose a Bayesian latent variable methodology to jointly model multiple operational taxonomic units within a single taxonomic cluster. This novel method can incorporate both negative binomial and zero-inflated negative binomial responses, and can account for serial and familial correlations. We develop a Markov chain Monte Carlo algorithm that is built on a data augmentation scheme using Pólya-Gamma random variables. Hierarchical centering and parameter expansion techniques are also used to improve the convergence of the Markov chain. We evaluate the performance of our proposed method through extensive simulations. We also apply our method to a human microbiome study.

  15. The complex of measures on inclusion of small businesses in innovation clusters

    Directory of Open Access Journals (Sweden)

    A. V. Kupchinsky

    2016-01-01

    Full Text Available Modern practice of managing and its display in scientific publications demonstrate that development of world economy with all evidence proves the major role and the importance of sector of small business structures in national economy. In the modern world the national economy in many respects began to be determined by the balanced and sustainable development of the small business structures recognized now as conductors and creators of new opening and technologies, moreover, as the strategic instrument of the structural transformations of a modern economic system of the country often directed to high-quality increase in efficiency of reproduction process of regional economy. Now in Russia the level of development of an innovative entrepreneurship is very low. It is possible to state lack of properly created institutional environment for development of a small entrepreneurship in the innovative sphere. Clasterisation represents process of consolidation of a number of the organizations of various industries for increase in competitiveness, implementation of innovations, effective development and receipt of other benefits. According to separation of economy on real and virtual, the possibility of creation of both real, and virtual clusters increases. Creation and development of regional clusters will help to create the necessary level of activity of small business structures in innovative activities that will favorably affect increase in competitiveness of both regional, and national economy. The package of measures including measures for involvement of small business structures in clusters is developed for development of a cluster initiative and increase in innovative development of the region. Application of this program will allow to reach synergy effect at the expense of high degree of concentration and cooperation of small business structures and increase in effectiveness of their activities.

  16. Cluster Ion Spectrometry (CIS) data quality indexes as a support for analysing magnetospheric measurements

    Science.gov (United States)

    Dandouras, Iannis; Barthe, Alain; Brunato, Sylvain; Rème, Henri; Laakso, Harri

    2016-04-01

    The Cluster Science Archive (CSA) aims at preserving the complete set of the measurements collected by the four Cluster spacecraft, so that they are usable in the long-term by the world-wide scientific community as well as by the instrument teams. This implies that the instrument data, properly calibrated, are filed together with the descriptive and documentary elements making it possible to select and interpret them. The CIS (Cluster Ion Spectrometry) experiment is a comprehensive ionic plasma spectrometry package onboard the Cluster spacecraft, capable of obtaining full three-dimensional ion distributions (about 0 to 40 keV/e) with a time resolution of one spacecraft spin (4 sec) and with mass-per-charge composition determination. For the archival of the CIS data a multi-level approach has been adopted. The CSA archival includes processed raw data, moments of the ion distribution functions, and calibrated high-resolution data in a variety of physical units. The latter are 3-D ion distribution functions, 2-D pitch-angle distributions and 1-D omni-directional fluxes. The CIS data archive includes also experiment documentation, graphical products for browsing through the data, data caveats and data quality indexes. The later constitute a novel product, which has been prepared in order to help the user asses the quality of the data acquired in different magnetospheric regions and during various operational modes. It provides information on which are in each case the issues that can affect the data quality, which are the data products affected, and gives a simple quantitative measurement of the severity of these issues. The principle of the CIS data quality indexes will be described and the various issues, that can under some conditions affect the data quality and are thus taken into account in generating the data quality indexes, will be discussed.

  17. Cluster-cluster clustering

    Science.gov (United States)

    Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C. S.

    1985-01-01

    The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales.

  18. Cluster-cluster clustering

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C.S.

    1985-08-01

    The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales. 30 references.

  19. THE MULTI-EPOCH NEARBY CLUSTER SURVEY: TYPE Ia SUPERNOVA RATE MEASUREMENT IN z {approx} 0.1 CLUSTERS AND THE LATE-TIME DELAY TIME DISTRIBUTION

    Energy Technology Data Exchange (ETDEWEB)

    Sand, David J.; Graham, Melissa L. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Bildfell, Chris; Pritchet, Chris [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, STN CSC, Victoria BC V8W 3P6 (Canada); Zaritsky, Dennis; Just, Dennis W.; Herbert-Fort, Stephane [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Hoekstra, Henk [Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden (Netherlands); Sivanandam, Suresh [Dunlap Institute for Astronomy and Astrophysics, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mahdavi, Andisheh, E-mail: dsand@lcogt.net [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States)

    2012-02-20

    We describe the Multi-Epoch Nearby Cluster Survey, designed to measure the cluster Type Ia supernova (SN Ia) rate in a sample of 57 X-ray selected galaxy clusters, with redshifts of 0.05 < z < 0.15. Utilizing our real-time analysis pipeline, we spectroscopically confirmed twenty-three cluster SNe Ia, four of which were intracluster events. Using our deep Canada-France-Hawaii Telescope/MegaCam imaging, we measured total stellar luminosities in each of our galaxy clusters, and we performed detailed supernova (SN) detection efficiency simulations. Bringing these ingredients together, we measure an overall cluster SN Ia rate within R{sub 200} (1 Mpc) of 0.042{sup +0.012}{sub -0.010}{sup +0.010}{sub -0.008} SNuM (0.049{sup +0.016}{sub -0.014}{sup +0.005}{sub -0.004} SNuM) and an SN Ia rate within red-sequence galaxies of 0.041{sup +0.015}{sub -0.015}{sup +0.005}{sub -0.010} SNuM (0.041{sup +0.019}{sub -0.015}{sup +0.005}{sub -0.004} SNuM). The red-sequence SN Ia rate is consistent with published rates in early-type/elliptical galaxies in the 'field'. Using our red-sequence SN Ia rate, and other cluster SN measurements in early-type galaxies up to z {approx} 1, we derive the late-time (>2 Gyr) delay time distribution (DTD) of SN Ia assuming a cluster early-type galaxy star formation epoch of z{sub f} = 3. Assuming a power-law form for the DTD, {Psi}(t){proportional_to}t{sup s} , we find s = -1.62 {+-} 0.54. This result is consistent with predictions for the double degenerate SN Ia progenitor scenario (s {approx} -1) and is also in line with recent calculations for the double detonation explosion mechanism (s {approx} -2). The most recent calculations of the single degenerate scenario DTD predicts an order-of-magnitude drop-off in SN Ia rate {approx}6-7 Gyr after stellar formation, and the observed cluster rates cannot rule this out.

  20. Finding Clothing That Fit through Cluster Analysis and Objective Interestingness Measures

    Science.gov (United States)

    Peña, Isis; Viktor, Herna L.; Paquet, Eric

    Clothes should fit consumers well, be aesthetically pleasing and comfortable. However, repeated studies of customers’ levels of satisfaction indicate that this is often not the case. For example, more robust males often find it difficult to find pants that are the correct length and fit their waists well. What, then, are the typical body profiles of the population? Would it be possible to identify the measurements that are of importance for different sizes and genders? Furthermore, assuming that we have access to an anthropometric database would there be a way to guide the data mining process to discover only those relevant body measurements that are of the most interest for apparel designers? This paper describes our results when addressing these questions through cluster analysis and interestingness measures-based feature selection. We explore a database containing anthropometric measurements as well as 3-D body scans, of a representative sample of the Dutch population.

  1. The Cosmic Large-Scale Structure in X-rays (CLASSIX) Cluster Survey I: Probing galaxy cluster magnetic fields with line of sight rotation measures

    CERN Document Server

    Boehringer, Hans; Kronberg, Philipp P

    2016-01-01

    To search for a signature of an intracluster magnetic field, we compare measurements of Faraday rotation of polarised extragalactic radio sources in the line of sight of galaxy clusters with those outside. We correlated a catalogue of 1383 rotation measures (RM) of extragalactic polarised radio sources with X-ray luminous galaxy clusters from the CLASSIX survey (combining REFLEX II and NORAS II). We compared the RM in the line of sight of clusters within their projected radii of r_500 with those outside and found a significant excess of the dispersion of the RM in the cluster regions. Since the observed RM is the result of Faraday rotation in several presumably uncorrelated magnetised cells of the intracluster medium, the observations correspond to quantities averaged over several magnetic field directions and strengths. Therefore the interesting quantity is the standard deviation of the RM for an ensemble of clusters. We found a standard deviation of the RM inside r_500 of about 120 +- 21 rad m^-2. This comp...

  2. New Neutron-Capture Measurements in 23 Open Clusters. I. The R-Process

    CERN Document Server

    Overbeek, Jamie C; Jacobson, Heather R

    2016-01-01

    Neutron-capture elements, those with Z > 35, are the least well-understood in terms of nucleosynthesis and formation environments. The rapid neutron-capture, or r-process, elements are formed in the environments and/or remnants of massive stars, while the slow neutron-capture, or s-process, elements are primarily formed in low-mass AGB stars. These elements can provide much information about Galactic star formation and enrichment, but observational data is limited. We have assembled a sample of 68 stars in 23 open clusters that we use to probe abundance trends for six neutron-capture elements (Eu, Gd, Dy, Mo, Pr, and Nd) with cluster age and location in the disk of the Galaxy. In order to keep our analysis as homogenous as possible, we use an automated synthesis fitting program, which also enables us to measure multiple (3-10) lines for each element. We find that the pure r-process elements (Eu, Gd, and Dy) have positive trends with increasing cluster age, while the mixed r- and s- process elements (Mo, Pr, a...

  3. A Machine Learning Approach for Dynamical Mass Measurements of Galaxy Clusters

    CERN Document Server

    Ntampaka, Michelle; Sutherland, Dougal J; Battaglia, Nicholas; Poczos, Barnabas; Schneider, Jeff

    2014-01-01

    We present a modern machine learning approach for cluster dynamical mass measurements that is a factor of two improvement over using a conventional scaling relation. Different methods are tested against a mock cluster catalog constructed using halos with mass >= 10^14 Msolar/h from Multidark's publicly-available N-body MDPL halo catalog. In the conventional method, we use a standard M(sigma_v) power law scaling relation to infer cluster mass, M, from line-of-sight (LOS) galaxy velocity dispersion, sigma_v. The resulting fractional mass error distribution is broad, with width = 0.86 (68% scatter), and has extended high-error tails. The standard scaling relation can be simply enhanced by including higher-order moments of the LOS velocity distribution. Applying the kurtosis as a linear correction term to log(sigma_v) reduces the width of the error distribution to 0.74 (15% improvement). Machine learning can be used to take full advantage of all the information in the velocity distribution. We employ the Support ...

  4. Measuring and Modelling the Redshift Evolution of Clustering the Hubble Deep Field North

    CERN Document Server

    Arnouts, S; Moscardini, L; Matarrese, S; Lucchin, F; Fontana, A; Giallongo, E; Arnouts, Stephane; Cristiani, Stefano; Moscardini, Lauro; Matarrese, Sabino; Lucchin, Francesco; Fontana, Adriano; Giallongo, Emanuele

    1999-01-01

    (abridged) The evolution of galaxy clustering from z=0 to z=4.5 is analyzed using the angular correlation function and the photometric redshift distribution of galaxies brighter than I_{AB}\\le 28.5 in the HDF North. The reliability of the photometric redshift estimates is discussed on the basis of the available spectroscopic redshifts, comparing different codes and investigating the effects of photometric errors. The redshift bins in which the clustering properties are measured are then optimized to take into account the uncertainties of the photometric redshifts. The results show that the comoving correlation length has a small decrease in the range 0clustering evolution indicates that the observed high-redshift galaxies are biased tracers of the dark matter with an effective bias b strongly i...

  5. Measurement of 15 MeV gamma-rays with the Ge cluster detectors of EUROBALL

    CERN Document Server

    Million, B; Camera, F; Brambilla, S; Gadea, A; Giugni, D; Herskind, B; Kmiecik, M; Isocrate, R; Leoni, S; Maj, A; Prelz, F; Wieland, O

    2000-01-01

    A measurement of the response to 15.1 MeV gamma-rays has been made for the Ge cluster detectors in the EUROBALL array. Each cluster detector consists of seven germanium capsules surrounded by a single anticompton shield of BGO. The reaction D( sup 1 sup 1 B,gamma) sup 1 sup 2 C+n at E sub b sub e sub a sub m =19.1 MeV has been employed. The 'adding-back' of signals simultaneously present in the capsules composing each cluster detector has been made on an event by event basis. The intensity in full-energy peak increases by a factor of three as compared to that of the spectrum obtained by summing the individual spectra of the 7 capsules. The pulse height to energy conversion is found to be very linear from few hundreds keV to 15 MeV. The efficiency is discussed relative to that of large volume BaF sub 2 scintillators.

  6. Incorporating Photometric Redshift Probability Density Information into Real-Space Clustering Measurements

    CERN Document Server

    Myers, Adam D; Ball, Nicholas M

    2009-01-01

    The use of photometric redshifts in cosmology is increasing. Often, however these photo-zs are treated like spectroscopic observations, in that the peak of the photometric redshift, rather than the full probability density function (PDF), is used. This overlooks useful information inherent in the full PDF. We introduce a new real-space estimator for one of the most used cosmological statistics, the 2-point correlation function, that weights by the PDF of individual photometric objects in a manner that is optimal when Poisson statistics dominate. As our estimator does not bin based on the PDF peak it substantially enhances the clustering signal by usefully incorporating information from all photometric objects that overlap the redshift bin of interest. As a real-world application, we measure QSO clustering in the Sloan Digital Sky Survey (SDSS) and find that our estimator improves the clustering signal by a factor equivalent to increasing the survey size by a factor of 2 to 3. Our technique uses spectroscopic ...

  7. Cluster-based statistics for brain connectivity in correlation with behavioral measures.

    Directory of Open Access Journals (Sweden)

    Cheol E Han

    Full Text Available Graph theoretical approaches have successfully revealed abnormality in brain connectivity, in particular, for contrasting patients from healthy controls. Besides the group comparison analysis, a correlational study is also challenging. In studies with patients, for example, finding brain connections that indeed deepen specific symptoms is interesting. The correlational study is also beneficial since it does not require controls, which are often difficult to find, especially for old-age patients with cognitive impairment where controls could also have cognitive deficits due to normal ageing. However, one of the major difficulties in such correlational studies is too conservative multiple comparison correction. In this paper, we propose a novel method for identifying brain connections that are correlated with a specific cognitive behavior by employing cluster-based statistics, which is less conservative than other methods, such as Bonferroni correction, false discovery rate procedure, and extreme statistics. Our method is based on the insight that multiple brain connections, rather than a single connection, are responsible for abnormal behaviors. Given brain connectivity data, we first compute a partial correlation coefficient between every edge and the behavioral measure. Then we group together neighboring connections with strong correlation into clusters and calculate their maximum sizes. This procedure is repeated for randomly permuted assignments of behavioral measures. Significance levels of the identified sub-networks are estimated from the null distribution of the cluster sizes. This method is independent of network construction methods: either structural or functional network can be used in association with any behavioral measures. We further demonstrated the efficacy of our method using patients with subcortical vascular cognitive impairment. We identified sub-networks that are correlated with the disease severity by exploiting diffusion

  8. MITO measurements of the Sunyaev-Zeldovich Effect in the Coma cluster of galaxies

    CERN Document Server

    De Petris, M; Lamagna, L; Melchiorri, F; Orlando, A E; Palladino, E; Rephaeli, Y; Colafrancesco, Sergio; Kreysa, E; Signore, M

    2002-01-01

    We have measured the Sunyaev-Zeldovich effect towards the Coma cluster (A1656) with the MITO experiment, a 2.6-m telescope equipped with a 4-channel 17 arcminute (FWHM) photometer. Measurements at frequency bands 143+/-15, 214+/-15, 272+/-16 and 353+/-13 GHz, were made during 120 drift scans of Coma. We describe the observations and data analysis that involved extraction of the S-Z signal by employing a spatial and spectral de-correlation scheme to remove a dominant atmospheric component. The deduced values of the thermal S-Z effect in the first three bands are DT_{0} = -179+/-38,-33+/-81,170+/-35 microKelvin in the cluster center. The corresponding optical depth, tau=(4.1+/-0.9) 10^{-3}, is consistent (within errors) with both the value from a previous low frequency S-Z measurement, and the value predicted from the X-ray deduced gas parameters.

  9. Influence of CeO2 morphology on the catalytic activity of CeO2-Pt hybrids for CO oxidation.

    Science.gov (United States)

    Singhania, Nisha; Anumol, E A; Ravishankar, N; Madras, Giridhar

    2013-11-21

    Ceria, because of its excellent redox behavior and oxygen storage capacity, is used as a catalyst for several technologically important reactions. In the present study, different morphologies of nano-CeO2 (rods, cubes, octahedra) were synthesized using the hydrothermal route. An ultrafast microwave-assisted method was used to efficiently attach Pt particles to the CeO2 polyhedra. These nanohybrids were tested as catalysts for the CO oxidation reaction. The CeO2/Pt catalyst with nanorods as the support was found to be the most active catalyst. XPS and IR spectroscopy measurements were carried out in order to obtain a mechanistic understanding and it was observed that the adsorbed carbonates with lower stability on the reactive planes of nanorods and cubes are the major contributor to this enhanced catalytic activity.

  10. ONE THOUSAND AND ONE CLUSTERS: MEASURING THE BULK FLOW WITH THE PLANCK ESZ AND X-RAY-SELECTED GALAXY CLUSTER CATALOGS

    Energy Technology Data Exchange (ETDEWEB)

    Mody, Krishnan [Mathematics Department, Princeton University, Princeton, NJ 08544 (United States); Hajian, Amir, E-mail: kmody@princeton.edu, E-mail: ahajian@cita.utoronto.ca [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada)

    2012-10-10

    We present our measurement of the 'bulk flow' using the kinetic Sunyaev-Zel'dovich (kSZ) effect in the Wilkinson Microwave Anisotropy Probe (WMAP) seven-year data. As the tracer of peculiar velocities, we use Planck Early Sunyaev-Zel'dovich Detected Cluster Catalog and a compilation of X-ray-detected galaxy cluster catalogs based on ROSAT All-Sky Survey. We build a full-sky kSZ template and fit it to the WMAP data in W band. Using a Wiener filter we maximize the signal-to-noise ratio of the kSZ cluster signal in the data. We find no significant detection of the bulk flow, and our results are consistent with the {Lambda}CDM prediction.

  11. One Thousand and One Clusters: Measuring the Bulk Flow with the Planck ESZ and X-Ray Selected Galaxy Cluster Catalogs

    CERN Document Server

    Mody, Krishnan

    2012-01-01

    We present our measurement of the "bulk flow" using the kinetic Sunyaev-Zel'dovich (kSZ) effect in the WMAP 7-year data. As the tracer of peculiar velocities, we use Planck Early Sunyaev-Zel'dovich Detected Cluster Catalog and a compilation of X-ray detected galaxy cluster catalogs based on ROSAT All-Sky Survey. We build a full-sky kSZ template and fit it to the WMAP data in W-band. Using a Wiener filter we maximize the signal to noise ratio of the kSZ cluster signal in the data. We find no significant detection of the bulk flow, and our results are consistent with the LCDM prediction.

  12. Measuring the Mean and Scatter of the X-ray Luminosity -- Optical Richness Relation for maxBCG Galaxy Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Rykoff, E.S.; McKay, T.A.; Becker, M.A.; Evrard, A.; Johnston, D.E.; Koester, B.P.; Rozo, E.; Sheldon, E.S.; Wechsler, Risa H.

    2007-10-02

    We interpret and model the statistical weak lensing measurements around 130,000 groups and clusters of galaxies in the Sloan Digital Sky Survey presented by Sheldon et al. (2007). We present non-parametric inversions of the 2D shear profiles to the mean 3D cluster density and mass profiles in bins of both optical richness and cluster i-band luminosity. Since the mean cluster density profile is proportional to the cluster-mass correlation function, the mean profile is spherically symmetric by the assumptions of large-scale homogeneity and isotropy. We correct the inferred 3D profiles for systematic effects, including non-linear shear and the fact that cluster halos are not all precisely centered on their brightest galaxies. We also model the measured cluster shear profile as a sum of contributions from the brightest central galaxy, the cluster dark matter halo, and neighboring halos. We infer the relations between mean cluster virial mass and optical richness and luminosity over two orders of magnitude in cluster mass; the virial mass at fixed richness or luminosity is determined with a precision of {approx} 13% including both statistical and systematic errors. We also constrain the halo concentration parameter and halo bias as a function of cluster mass; both are in good agreement with predictions from N-body simulations of LCDM models. The methods employed here will be applicable to deeper, wide-area optical surveys that aim to constrain the nature of the dark energy, such as the Dark Energy Survey, the Large Synoptic Survey Telescope and space-based surveys.

  13. SSM-DBSCANand SSM-OPTICS : Incorporating a new similarity measure for Density based Clustering of Web usage data.

    Directory of Open Access Journals (Sweden)

    Ms K.Santhisree

    2011-08-01

    Full Text Available Clustering web sessions is to group web sessions based on similarity and consists of minimizing the intra-group similarity and maximizing the inter-group similarity. Here in this paper we developed a new similarity measure named SSM(Sequence Similarity Measure and enhanced an existing DBSCAN and OPTICS clustering techniques namely SSM-DBSCAN, and SSM-OPTICS for clustering web sessions for web personalization. Then we adopted various similarity measures like Euclidean distance, Jaccard, Cosine and Fuzzy similarity measures to measure the similarity of web sessions using sequence alignment to determine learning behaviors of web usage data. This new measure hassignificant results when comparing similarities between web sessions with other previous measures. We performed a variety of experiments in the context of density based clustering, using existing DBSCANand OPTICS and developed SSM-DBSCAN and SSM-OPTICS based on sequence alignment to measure similarities between web sessions where sessions are chronologically ordered sequences of page visits. Finally the time and the memory required to perform clustering using SSM is less when compared to other similarity measures.

  14. Centroid neural network with a divergence measure for GPDF data clustering.

    Science.gov (United States)

    Park, Dong-Chul; Kwon, Oh-Hyun; Chung, Jio

    2008-06-01

    An unsupervised competitive neural network for efficient clustering of Gaussian probability density function (GPDF) data of continuous density hidden Markov models (CDHMMs) is proposed in this paper. The proposed unsupervised competitive neural network, called the divergence-based centroid neural network (DCNN), employs the divergence measure as its distance measure and utilizes the statistical characteristics of observation densities in the HMM for speech recognition problems. While the conventional clustering algorithms used for the vector quantization (VQ) codebook design utilize only the mean values of the observation densities in the HMM, the proposed DCNN utilizes both the mean and the covariance values. When compared with other conventional unsupervised neural networks, the DCNN successfully allocates more code vectors to the regions where GPDF data are densely distributed while it allocates fewer code vectors to the regions where GPDF data are sparsely distributed. When applied to Korean monophone recognition problems as a tool to reduce the size of the codebook, the DCNN reduced the number of GPDFs used for code vectors by 65.3% while preserving recognition accuracy. Experimental results with a divergence-based k-means algorithm and a divergence-based self-organizing map algorithm are also presented in this paper for a performance comparison.

  15. Measuring Group Synchrony: A Cluster-Phase Method for Analyzing Multivariate Movement Time-Series

    Directory of Open Access Journals (Sweden)

    Michael eRichardson

    2012-10-01

    Full Text Available A new method for assessing group synchrony is introduced as being potentially useful for objectively determining degree of group cohesiveness or entitativity. The cluster-phase method of Frank and Richardson (2010 was used to analyze movement data from the rocking chair movements of six-member groups who rocked their chairs while seated in a circle facing the center. In some trials group members had no information about others’ movements (their eyes were shut or they had their eyes open and gazed at a marker in the center of the group. As predicted, the group level synchrony measure was able to distinguish between situations where synchrony would have been possible and situations where it would be impossible. Moreover, other aspects of the analysis illustrated how the cluster phase measures can be used to determine the type of patterning of group synchrony, and, when integrated with multi-level modeling, can be used to examine individual-level differences in synchrony and dyadic level synchrony as well.

  16. The role of clustering effects in interpreting nondiffusive transport measurements in tokamaks

    Science.gov (United States)

    Graves, J. P.; Dendy, R. O.; Hopcraft, K. I.; Jakeman, E.

    2002-05-01

    Recent measurements in tokamak plasmas provide clear evidence for rapid nondiffusive transport and non-Gaussian fluctuations, and have been widely interpreted in terms of the sandpile and self-organized criticality (SOC) paradigms. Many of the statistical physics inferences that can be drawn from observations of, for example, avalanching transport remain to be explored. This paper will show that the statistical characterization of both experimentally observed and simulated avalanching transport phenomena reveals several points of contact with existing stochastic process models that have seldom been deployed in a plasma physics context. It will be shown that statistical physics techniques developed to model clustering of events can be used to characterize microscopic fluctuations in both local density and flux, as well as the global transport properties to which they give rise. This provides a fresh interpretation for some of the key aspects of observed critical gradient-driven transport phenomenology in tokamaks. In particular it provides new evidence for scale-free correlations in the fluctuations which drive the transport, and quantifies their distribution in terms of few-parameter non-Gaussian models. The correlation properties of density fluctuations can be interpreted in terms of random walk models, whereas flux fluctuations cannot: instead they can be described by the discrete negative binomial distribution, which again indicates clustering. Some of the spatio-temporal correlations considered emulate multichannel measurements in tokamaks, and it is shown how these can be used to characterize the transport of naturally arising coherent structures.

  17. CLUSTERING OF SLOAN DIGITAL SKY SURVEY III PHOTOMETRIC LUMINOUS GALAXIES: THE MEASUREMENT, SYSTEMATICS, AND COSMOLOGICAL IMPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Shirley; White, Martin; Schlegel, David J.; Seljak, Uros; Reid, Beth [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, MS 50R-5045, Berkeley, CA 94720 (United States); Cuesta, Antonio; Padmanabhan, Nikhil [Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06511 (United States); Seo, Hee-Jong [Berkeley Center for Cosmological Physics, LBL and Department of Physics, University of California, Berkeley, CA 94720 (United States); De Putter, Roland [ICC, University of Barcelona (IEEC-UB), Marti i Franques 1, E-08028 Barcelona (Spain); Ross, Ashley J.; Percival, Will J. [Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom); Saito, Shun [Department of Astronomy, University of California Berkeley, CA (United States); Schlafly, Eddie [Department of Astronomy, Harvard University, 60 Garden St. MS 20, Cambridge, MA 02138 (United States); Hernandez-Monteagudo, Carlos [Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA), Plaza de San Juan 1, planta 2, E-44001 Teruel (Spain); Sanchez, Ariel G. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Blanton, Michael [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Skibba, Ramin [Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Schneider, Don [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Mena, Olga [Instituto de Fisica Corpuscular, Universidad de Valencia-CSIC (Spain); Viel, Matteo, E-mail: cwho@lbl.gov [INAF-Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-34131 Trieste (Italy); and others

    2012-12-10

    The Sloan Digital Sky Survey (SDSS) surveyed 14,555 deg{sup 2}, and delivered over a trillion pixels of imaging data. We present a study of galaxy clustering using 900,000 luminous galaxies with photometric redshifts, spanning between z = 0.45 and z = 0.65, constructed from the SDSS using methods described in Ross et al. This data set spans 11,000 deg{sup 2} and probes a volume of 3 h {sup -3} Gpc{sup 3}, making it the largest volume ever used for galaxy clustering measurements. We describe in detail the construction of the survey window function and various systematics affecting our measurement. With such a large volume, high-precision cosmological constraints can be obtained given careful control and understanding of the observational systematics. We present a novel treatment of the observational systematics and its applications to the clustering signals from the data set. In this paper, we measure the angular clustering using an optimal quadratic estimator at four redshift slices with an accuracy of {approx}15%, with a bin size of {delta}{sub l} = 10 on scales of the baryon acoustic oscillations (BAOs; at l {approx} 40-400). We also apply corrections to the power spectra due to systematics and derive cosmological constraints using the full shape of the power spectra. For a flat {Lambda}CDM model, when combined with cosmic microwave background Wilkinson Microwave Anisotropy Probe 7 (WMAP7) and H{sub 0} constraints from using 600 Cepheids observed by Wide Field Camera 3 (WFC3; HST), we find {Omega}{sub {Lambda}} = 0.73 {+-} 0.019 and H{sub 0} to be 70.5 {+-} 1.6 s{sup -1} Mpc{sup -1} km. For an open {Lambda}CDM model, when combined with WMAP7 + HST, we find {Omega}{sub K} = 0.0035 {+-} 0.0054, improved over WMAP7+HST alone by 40%. For a wCDM model, when combined with WMAP7+HST+SN, we find w = -1.071 {+-} 0.078, and H{sub 0} to be 71.3 {+-} 1.7 s{sup -1} Mpc{sup -1} km, which is competitive with the latest large-scale structure constraints from large spectroscopic

  18. Electrolytic Fixation of CO2 by Electrocarboxylation of RX on Nanocrystalline TiO2-Pt Cathode

    Institute of Scientific and Technical Information of China (English)

    CHU, Dao-Bao(褚道葆); LI, Xiao-Hua(李晓华); LIU, Xin-Yuan(刘心元); YAO, Wen-Li(姚文俐)

    2004-01-01

    Electrolytic fixation of CO2 was investigated by electrocarboxylation of organic halides (RX), and four esters (Ⅰ, Ⅱ, Ⅲ, Ⅳ) were obtained in moderate yields. Electrochemical reduction esterifications of RX in the presence of CO2 were carried out on nanocrystalline TiO2-Pt electrode. The electrochemical behavior of RX in the presence of CO2 was investigated by the technique of cyclic voltammetry, and the probable reaction mechanism was proposed.

  19. Measuring the clustering of photometric quasars through blind mitigation of systematics

    Science.gov (United States)

    Leistedt, Boris; Peiris, Hiranya V.; Roth, Nina

    2014-05-01

    We present accurate measurements of the large-scale clustering of photometric quasars from the Sloan Digital Sky Survey. These results, detailed in Leistedt & Peiris (2014), rely on a novel technique to identify and treat systematics when measuring angular power spectra, using null-tests and analytical marginalisation. This approach can be used to maximise the extraction of information from current and future galaxy or quasar surveys. For example, it enables to robustly constrain primordial non-Gaussianity (PNG), which modifies the bias of galaxies and quasars on large scales - the most sensitive to observational systematics. The constraints on PNG obtained with the quasar power spectra are detailed in Leistedt, Peiris & Roth (2014); these are the most stringent constraints to date obtained with a single tracer of the large-scale structure.

  20. Cluster randomised trial of the impact of biosecurity measures on poultry health in backyard flocks.

    Science.gov (United States)

    Conan, Anne; Goutard, Flavie Luce; Holl, Davun; Ra, Sok; Ponsich, Aurélia; Tarantola, Arnaud; Sorn, San; Vong, Sirenda

    2013-12-01

    In Cambodia, most poultry are raised in backyard flocks with a low level of biosecurity, which increases the risk of spread of infectious diseases. The aim of this study was to evaluate the effectiveness of a practical biosecurity intervention based on affordable basic measures. A cluster randomised trial was conducted in 18 villages in Cambodia from November 2009 to February 2011. Generalised estimating equations were used to test the association between the intervention and mortality rates in flocks of chickens and ducks. Mortality rates in chicken flocks in intervention villages (mean 6.3%, range 3.5-13.8%, per month) were significantly higher than in control villages (mean 4.5%, range 2.0-9.7%, per month; Pbiosecurity intervention implemented in this study was not associated with improvements in poultry mortality rates. These findings suggest that basic biosecurity measures may not suffice to limit the spread of infectious diseases in backyard poultry flocks in Cambodia.

  1. Measuring the Density of a Molecular Cluster Injector via Visible Emission from an Electron Beam

    Energy Technology Data Exchange (ETDEWEB)

    Lundberg, D. P.; Kaita, R.; Majeski, R. M.; Stotler, D. P.

    2010-06-28

    A method to measure the density distribution of a dense hydrogen gas jet is pre- sented. A Mach 5.5 nozzle is cooled to 80K to form a flow capable of molecular cluster formation. A 250V, 10mA electron beam collides with the jet and produces Hα emission that is viewed by a fast camera. The high density of the jet, several 1016cm-3, results in substantial electron depletion, which attenuates the Hα emission. The attenuated emission measurement, combined with a simplified electron-molecule collision model, allows us to determine the molecular density profile via a simple iterative calculation.

  2. A Measurement of the Rate of Type Ia Supernovae in Galaxy Clusters from the SDSS-II Supernova Survey

    CERN Document Server

    Dilday, Benjamin; Becker, Andrew; Bender, Ralf; Castander, Francisco; Cinabro, David; Frieman, Joshua A; Galbany, Lluís; Garnavich, Peter; Goobar, Ariel; Hopp, Ulrich; Ihara, Yutaka; Jha, Saurabh W; Kessler, Richard; Lampeitl, Hubert; Marriner, John; Miquel, Ramon; Mollá, Mercedes; Nichol, Robert C; Nordin, Jakob; Riess, Adam G; Sako, Masao; Schneider, Donald P; Smith, Mathew; Sollerman, Jesper; Wheeler, J Craig; Östman, Linda; Bizyaev, Dmitry; Brewington, Howard; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Dan; Pan, Kaike; Simmons, Audrey; Snedden, Stephanie

    2010-01-01

    ABRIDGED We present measurements of the Type Ia supernova (SN) rate in galaxy clusters based on data from the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. The cluster SN Ia rate is determined from 9 SN events in a set of 71 C4 clusters at z <0.17 and 27 SN events in 492 maxBCG clusters at 0.1 < z < 0.3$. We find values for the cluster SN Ia rate of $({0.37}^{+0.17+0.01}_{-0.12-0.01}) \\mathrm{SNu}r h^{2}$ and $({0.55}^{+0.13+0.02}_{-0.11-0.01}) \\mathrm{SNu}r h^{2}$ ($\\mathrm{SNu}x = 10^{-12} L_{x\\sun}^{-1} \\mathrm{yr}^{-1}$) in C4 and maxBCG clusters, respectively, where the quoted errors are statistical and systematic, respectively. The SN rate for early-type galaxies is found to be $({0.31}^{+0.18+0.01}_{-0.12-0.01}) \\mathrm{SNu}r h^{2}$ and $({0.49}^{+0.15+0.02}_{-0.11-0.01})$ $\\mathrm{SNu}r h^{2}$ in C4 and maxBCG clusters, respectively. The SN rate for the brightest cluster galaxies (BCG) is found to be $({2.04}^{+1.99+0.07}_{-1.11-0.04}) \\mathrm{SNu}r h^{2}$ and $({0.36}^{+0.84+0.01}_...

  3. MEASURING THE LUMINOSITY AND VIRIAL BLACK HOLE MASS DEPENDENCE OF QUASAR–GALAXY CLUSTERING AT z ∼ 0.8

    Energy Technology Data Exchange (ETDEWEB)

    Krolewski, Alex G.; Eisenstein, Daniel J., E-mail: akrolewski@college.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-04-10

    We study the dependence of quasar clustering on quasar luminosity and black hole mass by measuring the angular overdensity of photometrically selected galaxies imaged by the Wide-field Infrared Survey Explorer (WISE) about z ∼ 0.8 quasars from SDSS. By measuring the quasar–galaxy cross-correlation function and using photometrically selected galaxies, we achieve a higher density of tracer objects and a more sensitive detection of clustering than measurements of the quasar autocorrelation function. We test models of quasar formation and evolution by measuring the luminosity dependence of clustering amplitude. We find a significant overdensity of WISE galaxies about z ∼ 0.8 quasars at 0.2–6.4 h{sup −1} Mpc in projected comoving separation. We find no appreciable increase in clustering amplitude with quasar luminosity across a decade in luminosity, and a power-law fit between luminosity and clustering amplitude gives an exponent of −0.01 ± 0.06 (1 σ error). We also fail to find a significant relationship between clustering amplitude and black hole mass, although our dynamic range in true mass is suppressed due to the large uncertainties in virial black hole mass estimates. Our results indicate that a small range in host dark matter halo mass maps to a large range in quasar luminosity.

  4. A Measurement of Gravitational Lensing of the Cosmic Microwave Background by Galaxy Clusters Using Data from the South Pole Telescope

    CERN Document Server

    Baxter, E J; Dodelson, S; Aird, K A; Allen, S W; Ashby, M L N; Bautz, M; Bayliss, M; Benson, B A; Bleem, L E; Bocquet, S; Brodwin, M; Carlstrom, J E; Chang, C L; Chiu, I; Cho, H-M; Clocchiatti, A; Crawford, T M; Crites, A T; Desai, S; Dietrich, J P; de Haan, T; Dobbs, M A; Foley, R J; Forman, W R; George, E M; Gladders, M D; Gonzalez, A H; Halverson, N W; Harrington, N L; Hennig, C; Hoekstra, H; Holder, G P; Holzapfel, W L; Hou, Z; Hrubes, J D; Jones, C; Knox, L; Lee, A T; Leitch, E M; Liu, J; Lueker, M; Luong-Van, D; Mantz, A; Marrone, D P; McDonald, M; McMahon, J J; Meyer, S S; Millea, M; Mocanu, L M; Murray, S S; Padin, S; Pryke, C; Reichardt, C L; Rest, A; Ruhl, J E; Saliwanchik, B R; Saro, A; Sayre, J T; Schaffer, K K; Shirokoff, E; Song, J; Spieler, H G; Stalder, B; Stanford, S A; Staniszewski, Z; Stark, A A; Story, K T; van Engelen, A; Vanderlinde, K; Vieira, J D; Vikhlinin, A; Williamson, R; Zahn, O; Zenteno, A

    2014-01-01

    Clusters of galaxies are expected to gravitationally lens the cosmic microwave background (CMB) and thereby generate a distinct signal in the CMB on arcminute scales. Measurements of this effect can be used to constrain the masses of galaxy clusters using CMB data alone. Here we present a measurement of lensing of the CMB by galaxy clusters using data from the South Pole Telescope (SPT). We develop a maximum likelihood approach to extract the CMB cluster lensing signal and validate the method on mock data. We quantify the effects of several potential sources of systematic error and find that they generally act to reduce the best-fit cluster mass. The net magnitude of the systematic shift to lower cluster mass is approximately the size of our statistical error bar, and we do not attempt to correct for it. We apply the maximum likelihood technique to 513 clusters selected via their SZ signatures in SPT data, and rule out the null hypothesis of no lensing at 3.0$\\sigma$. The lensing-derived mass estimate for the...

  5. Light-controlled propulsion, aggregation and separation of water-fuelled TiO2/Pt Janus submicromotors and their ``on-the-fly'' photocatalytic activities

    Science.gov (United States)

    Mou, Fangzhi; Kong, Lei; Chen, Chuanrui; Chen, Zhihong; Xu, Leilei; Guan, Jianguo

    2016-02-01

    In this work, water-fuelled TiO2/Pt Janus submicromotors with light-controlled motions have been developed by utilizing the asymmetrical photocatalytic water redox reaction over TiO2/Pt Janus submicrospheres under UV irradiation. The motion state, speed, aggregation and separation behaviors of the TiO2/Pt Janus submicromotor can be reversibly, wirelessly and remotely controlled at will by regulating the ``on/off'' switch, intensity and pulsed/continuous irradiation mode of UV light. The motion of the water-fuelled TiO2/Pt Janus submicromotor is governed by light-induced self-electrophoresis under the local electrical field generated by the asymmetrical water oxidation and reduction reactions on its surface. The TiO2/Pt Janus submicromotors can interact with each other through the light-switchable electrostatic forces, and hence continuous and pulsed UV irradiation can make the TiO2/Pt Janus submicromotors aggregate and separate at will, respectively. Because of the enhanced mass exchange between the environment and active submicromotors, the separated TiO2/Pt Janus submicromotors powered by the pulsed UV irradiation show a much higher activity for the photocatalytic degradation of the organic dye than the aggregated TiO2/Pt submicromotors. The water-fuelled TiO2/Pt Janus submicromotors developed here have some outstanding advantages as ``swimming'' photocatalysts for organic pollutant remediation in the macro or microenvironment (microchannels and microwells in microchips) because of their small size, long-term stability, wirelessly controllable motion behaviors and long life span.In this work, water-fuelled TiO2/Pt Janus submicromotors with light-controlled motions have been developed by utilizing the asymmetrical photocatalytic water redox reaction over TiO2/Pt Janus submicrospheres under UV irradiation. The motion state, speed, aggregation and separation behaviors of the TiO2/Pt Janus submicromotor can be reversibly, wirelessly and remotely controlled at will by

  6. A global study of hot flow anomalies using Cluster multi-spacecraft measurements

    Directory of Open Access Journals (Sweden)

    G. Facskó

    2009-05-01

    Full Text Available Hot flow anomalies (HFAs are studied using observations of the magnetometer and the plasma instrument aboard the four Cluster spacecraft. We study several specific features of tangential discontinuities on the basis of Cluster measurements from the time periods of February–April 2003, December 2005–April 2006 and January–April 2007, when the separation distance of spacecraft was large. The previously discovered condition (Facskó et al., 2008 for forming HFAs is confirmed, i.e. that the solar wind speed and fast magnetosonic Mach number values are higher than average. Furthermore, this constraint is independent of the Schwartz et al. (2000’s condition for HFA formation. The existence of this new condition is confirmed by simultaneous ACE magnetic field and solar wind plasma observations at the L1 point, at 1.4 million km distance from the Earth. The temperature, particle density and pressure parameters observed at the time of HFA formation are also studied and compared to average values of the solar wind plasma. The size of the region affected by the HFA was estimated by using two different methods. We found that the size is mainly influenced by the magnetic shear and the angle between the discontinuity normal and the Sun-Earth direction. The size grows with the shear and (up to a certain point with the angle as well. After that point it starts decreasing. The results are compared with the outcome of recent hybrid simulations.

  7. Measuring the distance-redshift relation with the baryon acoustic oscillations of galaxy clusters

    CERN Document Server

    Veropalumbo, Alfonso; Moscardini, Lauro; Moresco, Michele; Cimatti, Andrea

    2015-01-01

    We analyse the largest spectroscopic samples of galaxy clusters to date, and provide observational constraints on the distance-redshift relation from baryon acoustic oscillations. The cluster samples considered in this work have been extracted from the Sloan Digital Sky Survey at three median redshifts, $z=0.2$, $z=0.3$, and $z=0.5$. The number of objects is $12910$, $42215$, and $11816$, respectively. We detect the peak of baryon acoustic oscillations for all the three samples. The derived distance constraints are: $r_s/D_V(z=0.2)=0.18 \\pm 0.01$, $r_s/D_V(z=0.3)=0.124 \\pm 0.004$ and $r_s/D_V(z=0.5)=0.080 \\pm 0.002$. Combining these measurements, we obtain robust constraints on cosmological parameters. Our results are in agreement with the standard $\\Lambda$ cold dark matter model. Specifically, we constrain the Hubble constant in a $\\Lambda$CDM model, $H_0 = 64_{-9}^{+14} \\, \\mathrm{km} \\, \\mathrm{s}^{-1}\\mathrm{Mpc}^{-1}$, the density of curvature energy, in the $o\\Lambda$CDM context, $\\Omega_K = -0.015_{-0...

  8. The use of nanoscale visible light-responsive photocatalyst TiO2-Pt for the elimination of soil-borne pathogens.

    Directory of Open Access Journals (Sweden)

    Ya-Lei Chen

    Full Text Available Exposure to the soil-borne pathogens Burkholderia pseudomallei and Burkholderia cenocepacia can lead to severe infections and even mortality. These pathogens exhibit a high resistance to antibiotic treatments. In addition, no licensed vaccine is currently available. A nanoscale platinum-containing titania photocatalyst (TiO(2-Pt has been shown to have a superior visible light-responsive photocatalytic ability to degrade chemical contaminants like nitrogen oxides. The antibacterial activity of the catalyst and its potential use in soil pathogen control were evaluated. Using the plating method, we found that TiO(2-Pt exerts superior antibacterial performance against Escherichia coli compared to other commercially available and laboratory prepared ultraviolet/visible light-responsive titania photocatalysts. TiO(2-Pt-mediated photocatalysis also affectively eliminates the soil-borne bacteria B. pseudomallei and B. cenocepacia. An air pouch infection mouse model further revealed that TiO(2-Pt-mediated photocatalysis could reduce the pathogenicity of both strains of bacteria. Unexpectedly, water containing up to 10% w/v dissolved soil particles did not reduce the antibacterial potency of TiO(2-Pt, suggesting that the TiO(2-Pt photocatalyst is suitable for use in soil-contaminated environments. The TiO(2-Pt photocatalyst exerted superior antibacterial activity against a broad spectrum of human pathogens, including B. pseudomallei and B. cenocepacia. Soil particles (<10% w/v did not significantly reduce the antibacterial activity of TiO(2-Pt in water. These findings suggest that the TiO(2-Pt photocatalyst may have potential applications in the development of bactericides for soil-borne pathogens.

  9. Feature selection using feature dissimilarity measure and density-based clustering: Application to biological data

    Indian Academy of Sciences (India)

    Debarka Sengupta; Indranil Aich; Sanghamitra Bandyopadhyay

    2015-10-01

    Reduction of dimensionality has emerged as a routine process in modelling complex biological systems. A large number of feature selection techniques have been reported in the literature to improve model performance in terms of accuracy and speed. In the present article an unsupervised feature selection technique is proposed, using maximum information compression index as the dissimilarity measure and the well-known density-based cluster identification technique DBSCAN for identifying the largest natural group of dissimilar features. The algorithm is fast and less sensitive to the user-supplied parameters. Moreover, the method automatically determines the required number of features and identifies them. We used the proposed method for reducing dimensionality of a number of benchmark data sets of varying sizes. Its performance was also extensively compared with some other well-known feature selection methods.

  10. A Measurement of the Rate of Type Ia Supernovae in Galaxy Clusters from the SDSS-II Supernova Survey

    Energy Technology Data Exchange (ETDEWEB)

    Dilday, Benjamin; /Rutgers U., Piscataway /Chicago U. /KICP, Chicago; Bassett, Bruce; /Cape Town U., Dept. Math. /South African Astron. Observ.; Becker, Andrew; /Washington U., Seattle, Astron. Dept.; Bender, Ralf; /Munich, Tech. U. /Munich U. Observ.; Castander, Francisco; /Barcelona, IEEC; Cinabro, David; /Wayne State U.; Frieman, Joshua A.; /Chicago U. /Fermilab; Galbany, Lluis; /Barcelona, IFAE; Garnavich, Peter; /Notre Dame U.; Goobar, Ariel; /Stockholm U., OKC /Stockholm U.; Hopp, Ulrich; /Munich, Tech. U. /Munich U. Observ. /Tokyo U.

    2010-03-01

    We present measurements of the Type Ia supernova (SN) rate in galaxy clusters based on data from the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. The cluster SN Ia rate is determined from 9 SN events in a set of 71 C4 clusters at z {le} 0.17 and 27 SN events in 492 maxBCG clusters at 0.1 {le} z {le} 0.3. We find values for the cluster SN Ia rate of (0.37{sub -0.12-0.01}{sup +0.17+0.01}) SNur h{sup 2} and (0.55{sub -0.11-0.01}{sup +0.13+0.02}) SNur h{sup 2} (SNux = 10{sup -12}L{sub x{circle_dot}}{sup -1} yr{sup -1}) in C4 and maxBCG clusters, respectively, where the quoted errors are statistical and systematic, respectively. The SN rate for early-type galaxies is found to be (0.31{sub -0.12-0.01}{sup +0.18+0.01}) SNur h{sup 2} and (0.49{sub -0.11-0.01}{sup +0.15+0.02}) SNur h{sup 2} in C4 and maxBCG clusters, respectively. The SN rate for the brightest cluster galaxies (BCG) is found to be (2.04{sub -1.11-0.04}{sup +1.99+0.07}) SNur h{sup 2} and (0.36{sub -0.30-0.01}{sup +0.84+0.01}) SNur h{sup 2} in C4 and maxBCG clusters, respectively. The ratio of the SN Ia rate in cluster early-type galaxies to that of the SN Ia rate in field early-type galaxies is 1.94{sub -0.91-0.015}{sup +1.31+0.043} and 3.02{sub -1.03-0.048}{sup +1.31+0.062}, for C4 and maxBCG clusters, respectively. The SN rate in galaxy clusters as a function of redshift, which probes the late time SN Ia delay distribution, shows only weak dependence on redshift. Combining our current measurements with previous measurements, we fit the cluster SN Ia rate data to a linear function of redshift, and find r{sub L} = [(0.49{sub -0.14}{sup +0.15}) + (0.91{sub -0.81}{sup +0.85}) x z] SNuB h{sup 2}. A comparison of the radial distribution of SNe in cluster to field early-type galaxies shows possible evidence for an enhancement of the SN rate in the cores of cluster early-type galaxies. With an observation of at most 3 hostless, intra-cluster SNe Ia, we estimate the fraction of cluster SNe that are

  11. The power of teaming up HST and Gaia: the first proper motion measurement of the distant cluster NGC 2419

    Science.gov (United States)

    Massari, D.; Posti, L.; Helmi, A.; Fiorentino, G.; Tolstoy, E.

    2017-02-01

    Aims: We present the first measurement of the proper motion and orbit of the very distant and intriguing globular cluster NCG 2419. Methods: We have combined data from HST and Gaia DR1 to derive the relative proper motions of stars in the direction of the cluster. To tie these to an absolute reference frame, we have used a background galaxy located in the field. Results: We find the absolute proper motion of NGC 2419 to be (μαcos(δ), μδ) = (-0.17 ± 0.26,-0.49 ± 0.17) mas yr-1. We have integrated the orbit of the cluster in a Galactic potential and found it to oscillate between 53 kpc and 98 kpc on an almost polar orbit. This, and the fact that it shares the same sense of rotation around the Milky Way, make it very likely that NGC 2419 is a former cluster of the Sagittarius dwarf spheroidal galaxy.

  12. The power of teaming up HST and Gaia: the first proper motion measurement of the distant cluster NGC 2419

    CERN Document Server

    Massari, Davide; Helmi, Amina; Fiorentino, Giuliana; Tolstoy, Eline

    2016-01-01

    Aims: We present the first measurement of the proper motion and orbit of the very distant and intriguing globular cluster NCG 2419. Methods: We have combined data from HST and Gaia DR1 to derive the relative proper motions of stars in the direction to the cluster. To tie to an absolute reference frame we have used a background galaxy located in the field. Results: We find the absolute proper motion of NGC 2419 to be $(\\mu_{\\alpha}\\cos(\\delta)$, $\\mu_{\\delta}$)=($-0.17\\pm0.26,-0.49\\pm0.17$) mas/yr. We have integrated the orbit of the cluster in a Galactic potential and found it to oscillate between $\\sim$53 kpc and $\\sim$98 kpc on a nearly polar orbit. This makes it very likely that NGC 2419 is a former cluster of the Sagittarius dwarf spheroidal galaxy, also because it shares the same sense of rotation around the Milky Way.

  13. THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. III. MEASURING AGES AND MASSES OF PARTIALLY RESOLVED STELLAR CLUSTERS

    Energy Technology Data Exchange (ETDEWEB)

    Beerman, Lori C.; Johnson, L. Clifton; Fouesneau, Morgan; Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Ben F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Seth, Anil C. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Bianchi, Luciana C. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Caldwell, Nelson [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Dolphin, Andrew E. [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Gouliermis, Dimitrios A. [Zentrum fuer Astronomie, Institut fuer Theoretische Astrophysik, Universitaet Heidelberg, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Kalirai, Jason S. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Larsen, Soren S. [Department of Astrophysics, IMAPP, Radboud University Nijmegen, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands); Melbourne, Jason L. [Caltech Optical Observatories, Division of Physics, Mathematics and Astronomy, Mail Stop 301-17, California Institute of Technology, Pasadena, CA 91125 (United States); Rix, Hans-Walter [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Skillman, Evan D., E-mail: beermalc@astro.washington.edu [Department of Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)

    2012-12-01

    The apparent age and mass of a stellar cluster can be strongly affected by stochastic sampling of the stellar initial mass function (IMF), when inferred from the integrated color of low-mass clusters ({approx}<10{sup 4} M {sub Sun }). We use simulated star clusters to show that these effects are minimized when the brightest, rapidly evolving stars in a cluster can be resolved, and the light of the fainter, more numerous unresolved stars can be analyzed separately. When comparing the light from the less luminous cluster members to models of unresolved light, more accurate age estimates can be obtained than when analyzing the integrated light from the entire cluster under the assumption that the IMF is fully populated. We show the success of this technique first using simulated clusters, and then with a stellar cluster in M31. This method represents one way of accounting for the discrete, stochastic sampling of the stellar IMF in less massive clusters and can be leveraged in studies of clusters throughout the Local Group and other nearby galaxies.

  14. The HI Content of Galaxies in Groups and Clusters as Measured by ALFALFA

    Science.gov (United States)

    Odekon, Mary Crone; Koopmann, Rebecca A.; Haynes, Martha P.; Finn, Rose A.; McGowan, Christopher; Micula, Adina; Reed, Lyle; Giovanelli, Riccardo; Hallenbeck, Gregory

    2016-06-01

    We present the HI content of galaxies in nearby groups and clusters as measured by the 70% complete Arecibo Legacy Fast-ALFA (ALFALFA) survey, including constraints from ALFALFA detection limits. Our sample includes 22 systems at distances between 70 and 160 Mpc over the mass range 12.5<' {log} M/{M}⊙ < 15.0, for a total of 1986 late-type galaxies. We find that late-type galaxies in the centers of groups lack HI at fixed stellar mass relative to the regions surrounding them. Larger groups show evidence of a stronger dependence of HI properties on environment, despite a similar dependence of color on environment at fixed stellar mass. We compare several environment variables to determine which is the best predictor of galaxy properties; group-centric distance r and r/{R}200 are similarly effective predictors, while local density is slightly more effective and group size and halo mass are slightly less effective. While both central and satellite galaxies in the blue cloud exhibit a significant dependence of HI content on local density, only centrals show a strong dependence on stellar mass, and only satellites show a strong dependence on halo mass. Finally, we see evidence that HI is deficient for blue cloud galaxies in denser environments even when both stellar mass and color are fixed. This is consistent with a picture where HI is removed or destroyed, followed by reddening within the blue cloud. Our results support the existence of pre-processing in isolated groups, along with an additional rapid mechanism for gas removal within larger groups and clusters, perhaps ram-pressure stripping.

  15. The origin of polarity dependent switching type in solution processed Pt/TiO2/Pt memory devices

    Science.gov (United States)

    Biju, K. P.

    2015-06-01

    Resistive switching characteristics of sol-gel processed TiO2 thin films are investigated. The influence of polarity of the forming voltage on switching type in Pt/TiO2/Pt stack is investigated. Reliability and stability of the device is significantly improved by choosing a proper voltage polarity on electroforming. The device shows excellent switching properties such as high on/off ratio (> 20), good cycling endurance and long retention (> 104 s) and possible to use multi bit storage has been demonstrated. The switching mechanism is explained by a physical model based on localized generation/recovery of oxygen vacancy defects.

  16. Measuring Complementary Electronic Structure Properties of both Deposited and Gas Phase Clusters using STM, UPS, and PES: Size-Selected Clusters on Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, Kit H.

    2014-03-05

    In this project, we studied size-selected cluster interactions with surfaces, with other clusters on surfaces, and with external stimuli. These studies focused on mobility as a function of cluster size, surface morphologies as a function of composition and coverage, ion-induced modification and reactivity of clusters as a function of composition, the structural evolution of cluster cuboids culminating in the characterization of theoretically-predicted “baby crystal” clusters, and unusual fractal pattern formation due to deposition.

  17. A Model gamma-Alumina-Supported Rhenium-Platinum Catalyst Prepared from [Re2Pt(CO)12]: 1. Synthesis and Spectroscopic Characterization.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Fung, A.S.; McDeVitt, M.R.; Tooley, P.A.; Kelley, M.J.; Gates, B.C.

    1993-01-01

    Catalysts supported on -Al2O3 were prepared from [Re2Pt(CO)12], and from Pt (NH3)4(NO3)2 and NH4ReO4. The former samples were characterized by infrared and X-ray photoelectron spectroscopies (XPS) and by temperature-programmed reduction (TPR); the latter were characterized by TPR. [Re2Pt(CO)12] was

  18. Radio Measurements of the stellar proper motions in the core of the Orion Nebula Cluster

    CERN Document Server

    Dzib, Sergio A; Rodríguez, Luis F; Gómez, Laura; Forbrich, Jan; Menten, Karl M; Kounkel, Marina A; Mioduszewski, Amy J; Hartmann, Lee; Tobin, John J; Rivera, Juana L

    2016-01-01

    Using multi-epoch VLA observations, covering a time baseline of 29.1 years, we have measured the proper motions of 88 young stars with compact radio emission in the core of the Orion Nebula Cluster (ONC) and the neighboring BN/KL region. Our work increases the number of young stars with measured proper motion at radio frequencies by a factor of 2.5 and enables us to perform a better statistical analysis of the kinematics of the region than was previously possible. Most stars (79 out of 88) have proper motions consistent with a Gaussian distribution centered on $\\overline{\\mu_{\\alpha}\\cos{\\delta}}=1.07\\pm0.09\\quad{\\rm mas\\,yr^{-1}}$, and $\\overline{\\mu_{\\delta}}=-0.84\\pm0.16\\quad{\\rm mas\\,yr^{-1}}$, with velocity dispersions of $\\sigma_{\\alpha}=1.08\\pm0.07\\quad{\\rm mas\\,\\,yr^{-1}},$ $\\sigma_{\\delta}=1.27\\pm0.15\\quad{\\rm mas\\,\\,yr^{-1}}$. We looked for organized movements of these stars but found no clear indication of radial expansion/contraction or rotation. The remaining nine stars in our sample show peculia...

  19. A new method for measuring metallicities of young super star clusters

    Energy Technology Data Exchange (ETDEWEB)

    Gazak, J. Zachary; Kudritzki, Rolf; Bresolin, Fabio [Institute for Astronomy, University of Hawai' i, 2680 Woodlawn Dr, Honolulu, HI 96822 (United States); Davies, Ben; Bastian, Nate [Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Bergemann, Maria [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Plez, Bertrand [Laboratoire Univers et Particules de Montpellier, Université Montpellier 2, CNRS, F-34095 Montpellier (France); Evans, Chris [UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom); Patrick, Lee [Institute for Astronomy, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom); Schinnerer, Eva [MPI for Astronomy, Konigstuhl 17, D-69117 Heidelberg (Germany)

    2014-06-01

    We demonstrate how the metallicities of young super star clusters (SSC) can be measured using novel spectroscopic techniques in the J-band. The near-infrared flux of SSCs older than ∼6 Myr is dominated by tens to hundreds of red supergiant stars. Our technique is designed to harness the integrated light of that population and produces accurate metallicities for new observations in galaxies above (M83) and below (NGC 6946) solar metallicity. In M83 we find [Z] = +0.28 ± 0.14 dex using a moderate resolution (R ∼ 3500) J-band spectrum and in NGC 6496 we report [Z] = -0.32 ± 0.20 dex from a low resolution spectrum of R ∼ 1800. Recently commissioned low resolution multiplexed spectrographs on the Very Large Telescope (KMOS) and Keck (MOSFIRE) will allow accurate measurements of SSC metallicities across the disks of star-forming galaxies up to distances of 70 Mpc with single night observation campaigns using the method presented in this paper.

  20. Time Delay Measurements for the Cluster-lensed Sextuple Quasar SDSS J2222+2745

    CERN Document Server

    Dahle, H; Sharon, K; Bayliss, M B; Rigby, J R

    2015-01-01

    We report first results from an ongoing monitoring campaign to measure time delays between the six images of the quasar SDSS J2222+2745, gravitationally lensed by a galaxy cluster. The time delay between A and B, the two most highly magnified images, is measured to be $\\tau_{AB} = 43.0 \\pm 4.5$ days (95% confidence interval), consistent with previous model predictions for this lens system. The strong intrinsic variability of the quasar also allows us to derive a tentative time delay value of $\\tau_{CA} = 694^{+23}_{-4}$ days between image C and A, in spite of modest overlap between their light curves in the current data set. Longer values of $\\tau_{CA} \\lesssim 830$ days cannot yet be firmly excluded, but further monitoring should be sufficient to confirm the tentative value during 2015. Image C, which is predicted to lead all the other lensed quasar images, has undergone a sharp, monotonic flux increase of 60-75% during 2014. The same brightening is predicted to occur in images A and B during 2016. The ampli...

  1. The Panchromatic Hubble Andromeda Treasury III. Measuring Ages and Masses of Partially Resolved Stellar Clusters

    CERN Document Server

    Beerman, Lori C; Fouesneau, Morgan; Dalcanton, Julianne J; Weisz, Daniel R; Seth, Anil C; Williams, Ben F; Bell, Eric F; Bianchi, Luciana C; Caldwell, Nelson; Dolphin, Andrew E; Gouliermis, Dimitrios A; Kalirai, Jason S; Larsen, Søren S; Melbourne, Jason L; Rix, Hans-Walter; Skillman, Evan D

    2012-01-01

    The apparent age and mass of a stellar cluster can be strongly affected by stochastic sampling of the stellar initial mass function, when inferred from the integrated color of low mass clusters (less than ~10^4 solar masses). We use simulated star clusters to show that these effects are minimized when the brightest, rapidly evolving stars in a cluster can be resolved, and the light of the fainter, more numerous unresolved stars can be analyzed separately. When comparing the light from the less luminous cluster members to models of unresolved light, more accurate age estimates can be obtained than when analyzing the integrated light from the entire cluster under the assumption that the initial mass function is fully populated. We show the success of this technique first using simulated clusters, and then with a stellar cluster in M31. This method represents one way of accounting for the discrete, stochastic sampling of the stellar initial mass function in less massive clusters and can be leveraged in studies o...

  2. Proper motions of the Arches cluster with Keck-LGS Adaptive Optics: the first kinematic mass measurement of the Arches

    CERN Document Server

    Clarkson, Will; Morris, Mark; Lu, Jessica; Stolte, Andrea; McCrady, Nate; Do, Tuan; Yelda, Sylvana

    2011-01-01

    We report the first detection of the intrinsic velocity dispersion of the Arches cluster - a young (~2 Myr), massive (~10,000 Solar Mass) starburst cluster located near the Galactic center. This was accomplished using proper motion measurements within the central region of the cluster, obtained with the laser guide star adaptive optics system at Keck Observatory over a 3 year time baseline (2006-2009). This uniform dataset results in proper motion measurements that are improved by a factor ~5 over previous measurements from heterogeneous instruments, yielding internal velocity dispersion estimates 0.15 +/- 0.01 mas/yr, which corresponds to 5.4 +/- 0.4 km/s at a distance of 8.4 kpc. Projecting a simple model for the cluster onto the sky to compare with our proper motion dataset, in conjunction with surface density data, we estimate the total present-day mass of the cluster to be 15,000 (+7400 -6000) Solar masses. The mass in stars observed within a cylinder of radius R=0.4 pc is found to be 9000 (+4000 -3500) ...

  3. Measuring redshift through X-ray spectroscopy of galaxy clusters: results from Chandra data and future prospects

    CERN Document Server

    Yu, Heng; Borgani, Stefano; Rosati, Piero; Zhu, Zong-Hong

    2011-01-01

    The ubiquitous presence of the Fe line complex in the X-ray spectra of galaxy clusters offers the possibility of measuring their redshift without resorting to spectroscopic follow-up observations. In this paper we assess the accuracy with which the redshift of galaxy clusters can be recovered from X-ray spectral analysis of Chandra archival data. This study indicates a strategy to build large surveys of clusters whose identification and redshift measurement are both based on X-ray data alone. We apply a blind search for K--shell and L--shell Fe line complex in X-ray cluster spectra using Chandra archival observations of galaxy clusters. The presence of the Fe line in the ICM spectra can be detected by simply analyzing the C-statistics variation $\\Delta C_{stat}$ as a function of the redshift parameter. We repeat the measurement under different conditions, and compare the X-ray derived redshift $z_X$ with the one obtained through optical spectroscopy $z_o$. We explore also how a number of priors on metallicity...

  4. Abundance Constraints and Direct Redshift Measurement of the Diffuse X-ray Emission from a Distant Cluster of Galaxies

    CERN Document Server

    Hashimoto, Y; Böhringer, H; Fabian, A C; Hasinger, G; Mainieri, V; Brunner, H; Hashimoto, Yasuhiro; Barcons, Xavier; Boehringer, Hans; Fabian, Andrew C.; Hasinger, Guenther; Mainieri, Vincenzo; Brunner, Hermann

    2004-01-01

    We report on the XMM-Newton (XMM) observation of RXJ1053.7+5735, one of the most distant X-ray selected clusters of galaxies, which also shows an unusual double-lobed X-ray morphology, indicative of a possible equal-mass cluster merger. The cluster was discovered during the ROSAT deep pointings in the direction of the Lockman Hole. All XMM Lockman Hole observations (PV, AO-1 & AO-2 phases) with the European Photon Imaging Camera (EPIC) were combined for the analysis, totaling exposure times ~ 648 ks, 738 ks, and 758 ks for pn, MOS1, and MOS2, respectively. With this 'deep' dataset, we could detect the Fe K line and obtain a strong constraint on cluster metallicity, which is difficult to achieve for clusters at z > 1. The best-fit abundance is 0.46 +0.11/-0.07 times the solar value. The Fe line emission also allows us to directly estimate the redshift of diffuse gas, with a value z = 1.14 +0.01/-0.01. This is one of the first clusters whose X-ray redshift is directly measured prior to the secure knowledge ...

  5. A new method for measuring ion clusters produced by charged particles in nanometre track sections of DNA size

    Science.gov (United States)

    Pszona, S.; Kula, J.; Marjanska, S.

    2000-06-01

    A new method is presented for measuring the frequency distribution of ion clusters, formed in nanometre sections of track, by charged particles. The simulated nanometer-size sites are produced in a device, called the Jet Counter. It consists of a pulse-operated valve which injects an expanding jet of nitrogen gas into an interaction chamber. The resulting distributions of ion clusters produced by alpha particle tracks (from 241Am) in sections ranging from 2 to around 10 nm at unit density in nitrogen gas have been measured. Analysis of the experimental results confirm that the primary ionisation distributions produced in the nanometer sections comply with the Poisson distribution. The ionisation cluster distributions produced in the 2-10 nm track-segments are the first ever to be determined experimentally.

  6. A new method for measuring ion clusters produced by charged particles in nanometre track sections of DNA size

    Energy Technology Data Exchange (ETDEWEB)

    Pszona, S. E-mail: pszona@ipj.gov.pl; Kula, J.; Marjanska, S

    2000-06-11

    A new method is presented for measuring the frequency distribution of ion clusters, formed in nanometre sections of track, by charged particles. The simulated nanometer-size sites are produced in a device, called the Jet Counter. It consists of a pulse-operated valve which injects an expanding jet of nitrogen gas into an interaction chamber. The resulting distributions of ion clusters produced by alpha particle tracks (from {sup 241}Am) in sections ranging from 2 to around 10 nm at unit density in nitrogen gas have been measured. Analysis of the experimental results confirm that the primary ionisation distributions produced in the nanometer sections comply with the Poisson distribution. The ionisation cluster distributions produced in the 2-10 nm track-segments are the first ever to be determined experimentally.

  7. Magnetic and thermoelectric properties of a heterogeneous mixed-valence system, Yb sub 2 Pt sub 3 Sn sub 5

    CERN Document Server

    Muro, Y; Kim, M S; Takabatake, T; Godart, C; Rogl, P

    2003-01-01

    We have studied the valence states and thermoelectric properties of Yb sub 2 T sub 3 Sn sub 5 (T=Pt and Pd) with two inequivalent Yb sites. For Yb sub 2 Pt sub 3 Sn sub 5 , the 4 f-hole occupation number n sub f is estimated to be 0.4 at 300 K from the magnetic susceptibility and L sub I sub I sub I -edge absorption spectrum. Intermediate-valence behaviors manifest themselves in a largely negative value of the paramagnetic Curie temperature, -216 K, a broad peak at 300 K in the magnetic part of the resistivity, and a large minimum in the thermopower, -38 mu V/K at 60 K. The specific heat shows no transition down to 0.6 K. These results are explained by a model in which Yb ions in one site are divalent and those in the other site are in a valence fluctuating state with a Kondo temperature of 200 K. Thus, Yb sub 2 Pt sub 3 Sn sub 5 is a rare example of the heterogeneous mixed-valence system. An isostructural compound Yb sub 2 Pd sub 3 Sn sub 5 has a larger unit-cell volume by 2.4%, which allows the Yb ions in b...

  8. Fabrication and Characterization of New Ti-TiO2-Al and Ti-TiO2--Pt Tunnel Diodes

    Directory of Open Access Journals (Sweden)

    Yaksh Rawal

    2012-01-01

    Full Text Available Remotely empowered wireless sensor networks use different energy resources including photovoltaic solar cells, wireless power transmission, and batteries. As another option the electromagnetic energy available in the ambient can be harvested to power these remote sensors. This is particularly valuable if it is desirable to harvest the ambient energy available in the wide range of electromagnetic spectrum. This has motivated the research for developing energy harvesting devices which can absorb this energy and produce a DC voltage. Rectenna, an antenna coupled with a rectifier, is the main component used for absorbing electromagnetic radiation at GHz and THz frequencies. Rectifying MIM tunnel diodes are able to operate at tens and hundreds of GHz frequency. As the preliminary steps towards development of high-frequency rectifiers, this paper presents fabrication and DC characterization of two new MIM diodes, Ti-TiO2-Al and Ti-TiO2-Pt. G-V analysis of the fabricated diodes verifies tunneling. Brinkman-Dynes-Rowell model is used to extract oxide thickness of which the derived value is around 9 nm. Ti-TiO2-Pt diode exhibits rectification ratio of 15 at 0.495 V, which is more than rectification ratio reported in earlier works.

  9. The increase of rural development measures efficiency at the micro-regions level by cluster analysis. A Romanian case study

    Directory of Open Access Journals (Sweden)

    Maria VINCZE

    2011-06-01

    Full Text Available The aim of this paper is to demonstrate the role of cluster analysis of rural localities as the basis for a more efficient way of choosing the rural development measures to be used to stimulate rural socio-economic growth. We present evidence of the typologies of rural localities determined by hierarchical cluster using the Ward method. We used five groups of criteria: 1. characterising labour force supply (10 indicators; 2. those which describe the structure of employment via economic activities (5 indicators; 3. characteristics of living standards (7 indicators, 4. labour force, natural resources and local income characteristics (11 indicators. All of these indicators, used in the first stage of factor analysis, and in the second stage in the cluster analyses, permit classification of rural localities in different clusters, which, generally need different measures for rural employment growth. We offer a short description of the groups of localities which belong to different clusters. This information can help local, county and regional level decision makers to identify the most efficient approaches to stimulating rural development.

  10. Fast segmentation of industrial quality pavement images using Laws texture energy measures and k -means clustering

    Science.gov (United States)

    Mathavan, Senthan; Kumar, Akash; Kamal, Khurram; Nieminen, Michael; Shah, Hitesh; Rahman, Mujib

    2016-09-01

    Thousands of pavement images are collected by road authorities daily for condition monitoring surveys. These images typically have intensity variations and texture nonuniformities that make their segmentation challenging. The automated segmentation of such pavement images is crucial for accurate, thorough, and expedited health monitoring of roads. In the pavement monitoring area, well-known texture descriptors, such as gray-level co-occurrence matrices and local binary patterns, are often used for surface segmentation and identification. These, despite being the established methods for texture discrimination, are inherently slow. This work evaluates Laws texture energy measures as a viable alternative for pavement images for the first time. k-means clustering is used to partition the feature space, limiting the human subjectivity in the process. Data classification, hence image segmentation, is performed by the k-nearest neighbor method. Laws texture energy masks are shown to perform well with resulting accuracy and precision values of more than 80%. The implementations of the algorithm, in both MATLAB® and OpenCV/C++, are extensively compared against the state of the art for execution speed, clearly showing the advantages of the proposed method. Furthermore, the OpenCV-based segmentation shows a 100% increase in processing speed when compared to the fastest algorithm available in literature.

  11. Plasma convection in the magnetotail lobes: statistical results from Cluster EDI measurements

    Directory of Open Access Journals (Sweden)

    S. Haaland

    2008-08-01

    Full Text Available A major part of the plasma in the Earth's magnetotail is populated through transport of plasma from the solar wind via the magnetotail lobes. In this paper, we present a statistical study of plasma convection in the lobes for different directions of the interplanetary magnetic field and for different geomagnetic disturbance levels. The data set used in this study consists of roughly 340 000 one-minute vector measurements of the plasma convection from the Cluster Electron Drift Instrument (EDI obtained during the period February 2001 to June 2007. The results show that both convection magnitude and direction are largely controlled by the interplanetary magnetic field (IMF. For a southward IMF, there is a strong convection towards the central plasma sheet with convection velocities around 10 km s−1. During periods of northward IMF, the lobe convection is almost stagnant. A By dominated IMF causes a rotation of the convection patterns in the tail with an oppositely directed dawn-dusk component of the convection for the northern and southern lobe. Our results also show that there is an overall persistent duskward component, which is most likely a result of conductivity gradients in the footpoints of the magnetic field lines in the ionosphere.

  12. Cluster magnetic field observations in the magnetosheath: four-point measurements of mirror structures

    Directory of Open Access Journals (Sweden)

    E. A. Lucek

    Full Text Available The Cluster spacecraft have returned the first simultaneous four-point measurements of the magnetosheath. We present an analysis of data recorded on 10 November 2000, when the four spacecrafts observed an interval of strong mirrorlike activity. Correlation analysis between spacecraft pairs is used to examine the scale size of the mirror structures in three dimensions. Two examples are presented which suggest that the scale size of mirror structures is ~ 1500–3000 km along the flow direction, and shortest along the magnetopause normal (< 600 km, which, in this case, is approximately perpendicular to both the mean magnetic field and the magnetosheath flow vector. Variations on scales of ~ 750–1000 km are found along the maximum variance direction. The level of correlation in this direction, however, and the time lag observed, are found to be variable. These first results suggest that variations occur on scales of the order of the spacecraft separation ( ~ 1000 km in at least two directions, but analysis of further examples and a statistical survey of structures observed with different magnetic field orientations and tetrahedral configurations will enable us to describe more fully the size and orientation of mirror structures.

    Key words. Magnetosphenic physics (magnetosheath; plasma waves and instabilities

  13. HST measures of Mass Accretion Rates in the Orion Nebula Cluster

    CERN Document Server

    Manara, C F; Da Rio, N; Lodato, G; Hillenbrand, L A; Stassun, K G; Soderblom, D R

    2012-01-01

    The present observational understanding of the evolution of the mass accretion rates (Macc) in pre-main sequence stars is limited by the lack of accurate measurements of Macc over homogeneous and large statistical samples of young stars. Such observational effort is needed to properly constrain the theory of star formation and disk evolution. Based on HST/WFPC2 observations, we present a study of Macc for a sample of \\sim 700 sources in the Orion Nebula Cluster, ranging from the Hydrogen-burning limit to M\\ast \\sim 2M\\odot. We derive Macc from both the U-band excess and the H{\\alpha} luminosity (LH{\\alpha}), after determining empirically both the shape of the typical accretion spectrum across the Balmer jump and the relation between the accretion luminosity (Lacc) and LH{\\alpha}, that is Lacc/L\\odot = (1.31\\pm0.03)\\cdotLH{\\alpha}/L\\odot + (2.63\\pm 0.13). Given our large statistical sample, we are able to accurately investigate relations between Macc and the parameters of the central star such as mass and age....

  14. The HI Content of Galaxies in Groups and Clusters as Measured by ALFALFA

    CERN Document Server

    Odekon, Mary Crone; Haynes, Martha P; Finn, Rose A; McGowan, Christopher; Micula, Adina; Reed, Lyle; Giovanelli, Riccardo; Hallenbeck, Gregory

    2016-01-01

    We present the HI content of galaxies in nearby groups and clusters as measured by the 70% complete Arecibo Legacy Fast-ALFA (ALFALFA) survey, including constraints from ALFALFA detection limits. Our sample includes 22 systems at distances between 70-160 Mpc over the mass range 12.5

  15. Cosmology with velocity dispersion counts: an alternative to measuring cluster halo masses

    Science.gov (United States)

    Caldwell, C. E.; McCarthy, I. G.; Baldry, I. K.; Collins, C. A.; Schaye, J.; Bird, S.

    2016-11-01

    The evolution of galaxy cluster counts is a powerful probe of several fundamental cosmological parameters. A number of recent studies using this probe have claimed tension with the cosmology preferred by the analysis of the Planck primary cosmic microwave background (CMB) data, in the sense that there are fewer clusters observed than predicted based on the primary CMB cosmology. One possible resolution to this problem is systematic errors in the absolute halo mass calibration in cluster studies, which is required to convert the standard theoretical prediction (the halo mass function) into counts as a function of the observable (e.g. X-ray luminosity, Sunyaev-Zel'dovich flux, and optical richness). Here we propose an alternative strategy, which is to directly compare predicted and observed cluster counts as a function of the one-dimensional velocity dispersion of the cluster galaxies. We argue that the velocity dispersion of groups/clusters can be theoretically predicted as robustly as mass but, unlike mass, it can also be directly observed, thus circumventing the main systematic bias in traditional cluster counts studies. With the aid of the BAHAMAS suite of cosmological hydrodynamical simulations, we demonstrate the potential of the velocity dispersion counts for discriminating even similar Λ cold dark matter models. These predictions can be compared with the results from existing redshift surveys such as the highly complete Galaxy And Mass Assembly survey, and upcoming wide-field spectroscopic surveys such as the Wide Area Vista Extragalactic Survey and the Dark Energy Survey Instrument.

  16. Biased total mass of cool core galaxy clusters by Sunyaev-Zel'dovich Effect measurements

    CERN Document Server

    Conte, A; Comis, B; Lamagna, L; De Gregori, S

    2010-01-01

    The Sunyaev Zel'dovich (SZ) effect is one of the most powerful cosmological tools to investigate the large-scale Universe, in which clusters of galaxies are the most interesting target. The great advantage of the SZ effect of being redshift independent, in contrast with visible and X-ray observations, allows to directly estimate cluster total mass from the integrated comptonization parameter Y, even for faraway clusters. However, the lack of a complete knowledge of the Intra-Cluster gas (ICg) physics can affect the results. Taking into account self-similar temperature and density profiles of the ICg, we study how different ICg morphologies can affect the cluster total mass estimation. Due to the large percentage of cool core (CC) clusters, we analyze this class starting with a limited sample of eight objects, observed by Chandra. We simulate SZ observations of these clusters through X-ray derived information, and re-analyze the mock SZ data with the simplistic assumption for the ICg of an isothermal beta mode...

  17. Time Delay Measurements for the Cluster-lensed Sextuple Quasar SDSS J2222+2745

    Science.gov (United States)

    Dahle, H.; Gladders, M. D.; Sharon, K.; Bayliss, M. B.; Rigby, J. R.

    2015-11-01

    We report first results from an ongoing monitoring campaign to measure time delays between the six images of the quasar SDSS J2222+2745, gravitationally lensed by a galaxy cluster. The time delay between A and B, the two most highly magnified images, is measured to be {τ }{{AB}}=47.7+/- 6.0 days (95% confidence interval), consistent with previous model predictions for this lens system. The strong intrinsic variability of the quasar also allows us to derive a time delay value of {τ }{{CA}}=722+/- 24 days between image C and A, in spite of modest overlap between their light curves in the current data set. Image C, which is predicted to lead all the other lensed quasar images, has undergone a sharp, monotonic flux increase of 60%-75% during 2014. A corresponding brightening is firmly predicted to occur in images A and B during 2016. The amplitude of this rise indicates that time delays involving all six known images in this system, including those of the demagnified central images D-F, will be obtainable from further ground-based monitoring of this system during the next few years. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, and including observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnologi´a e Innovación Productiva (Argentina).

  18. Separating spatial and temporal variations in auroral electric and magnetic fields by Cluster multipoint measurements

    Directory of Open Access Journals (Sweden)

    T. Karlsson

    2004-07-01

    Full Text Available Cluster multipoint measurements of the electric and magnetic fields from a crossing of auroral field lines at an altitude of 4RE are used to show that it is possible to resolve the ambiguity of temporal versus spatial variations in the fields. We show that the largest electric fields (of the order of 300mV/m when mapped down to the ionosphere are of a quasi-static nature, unipolar, associated with upward electron beams, stable on a time scale of at least half a minute, and located in two regions of downward current. We conclude that they are the high-altitude analogues of the intense return current/black auroral electric field structures observed at lower altitudes by Freja and FAST. In between these structures there are temporal fluctuations, which are shown to likely be downward travelling Alfvén waves. The periods of these waves are 20-40s, which is not consistent with periods associated with either the Alfvénic ionospheric resonator, typical field line resonances or substorm onset related Pi2 oscillations. The multipoint measurements enable us to estimate a lower limit to the perpendicular wavelength of the Alfvén waves to be of the order of 120km, which suggests that the perpendicular wavelength is similar to the dimension of the region between the two quasi-static structures. This might indicate that the Alfvén waves are ducted within a wave guide, where the quasi-static structures are associated with the gradients making up this waveguide.

  19. Radio Measurements of the Stellar Proper Motions in the Core of the Orion Nebula Cluster

    Science.gov (United States)

    Dzib, Sergio A.; Loinard, Laurent; Rodríguez, Luis F.; Gómez, Laura; Forbrich, Jan; Menten, Karl M.; Kounkel, Marina A.; Mioduszewski, Amy J.; Hartmann, Lee; Tobin, John J.; Rivera, Juana L.

    2017-01-01

    Using multi-epoch Very Large Array observations, covering a time baseline of 29.1 years, we have measured the proper motions of 88 young stars with compact radio emission in the core of the Orion Nebula Cluster (ONC) and the neighboring BN/KL region. Our work increases the number of young stars with measured proper motion at radio frequencies by a factor of 2.5 and enables us to perform a better statistical analysis of the kinematics of the region than was previously possible. Most stars (79 out of 88) have proper motions consistent with a Gaussian distribution centered on \\overline{{μ }α \\cos δ }=1.07+/- 0.09 mas yr‑1, and \\overline{{μ }δ }=-0.84+/- 0.16 mas yr‑1, with velocity dispersions of {σ }α =1.08+/- 0.07 mas yr‑1, {σ }δ =1.27+/- 0.15 mas yr‑1. We looked for organized movements of these stars but found no clear indication of radial expansion/contraction or rotation. The remaining nine stars in our sample show peculiar proper motions that differ from the mean proper motions of the ONC by more than 3σ. One of these stars, V 1326 Ori, could have been expelled from the Orion Trapezium 7000 years ago. Two could be related to the multi-stellar disintegration in the BN/KL region, in addition to the previously known sources BN, I and n. The others either have high uncertainties (so their anomalous proper motions are not firmly established) or could be foreground objects.

  20. Electric field measurements on Cluster: comparing the double-probe and electron drift techniques

    Directory of Open Access Journals (Sweden)

    A. I. Eriksson

    2006-03-01

    Full Text Available The four Cluster satellites each carry two instruments designed for measuring the electric field: a double-probe instrument (EFW and an electron drift instrument (EDI. We compare data from the two instruments in a representative sample of plasma regions. The complementary merits and weaknesses of the two techniques are illustrated. EDI operations are confined to regions of magnetic fields above 30 nT and where wave activity and keV electron fluxes are not too high, while EFW can provide data everywhere, and can go far higher in sampling frequency than EDI. On the other hand, the EDI technique is immune to variations in the low energy plasma, while EFW sometimes detects significant nongeophysical electric fields, particularly in regions with drifting plasma, with ion energy (in eV below the spacecraft potential (in volts. We show that the polar cap is a particularly intricate region for the double-probe technique, where large nongeophysical fields regularly contaminate EFW measurments of the DC electric field. We present a model explaining this in terms of enhanced cold plasma wake effects appearing when the ion flow energy is higher than the thermal energy but below the spacecraft potential multiplied by the ion charge. We suggest that these conditions, which are typical of the polar wind and occur sporadically in other regions containing a significant low energy ion population, cause a large cold plasma wake behind the spacecraft, resulting in spurious electric fields in EFW data. This interpretation is supported by an analysis of the direction of the spurious electric field, and by showing that use of active potential control alleviates the situation.

  1. Measuring the matter distribution within z=0.2 cluster lenses with XMM-Newton

    CERN Document Server

    Marty, P B; Sadat, R; Bardeau, S; Czoske, O; Ebeling, H; Smail, I

    2003-01-01

    We present an analysis of 7 clusters observed by XMM as part of our survey of 17 most X-ray luminous clusters of galaxies at z=0.2 selected for a comprehensive and unbiased study of the mass distribution in massive clusters. Using public software, we have set up an automated pipeline to reduce the EPIC MOS & pn spectro-imaging data, optimized for extended sources analysis. We also developped a code to perform intensive spectral and imaging analysis particularly focussing on proper background estimate and removal. XMM deep spectro-imaging of these clusters allowed us to fit a standard beta-model to their gas emission profiles as well as a standard MEKAL emission model to their extracted spectra, and test their inferred characteristics against already calibrated relations.

  2. Chandra measurements of a complete sample of X-ray luminous galaxy clusters: the luminosity-mass relation

    Science.gov (United States)

    Giles, P. A.; Maughan, B. J.; Dahle, H.; Bonamente, M.; Landry, D.; Jones, C.; Joy, M.; Murray, S. S.; van der Pyl, N.

    2017-02-01

    We present the results of work involving a statistically complete sample of 34 galaxy clusters, in the redshift range 0.15 ≤ z ≤ 0.3 observed with Chandra. We investigate the luminosity-mass (LM) relation for the cluster sample, with the masses obtained via a full hydrostatic mass analysis. We utilize a method to fully account for selection biases when modelling the LM relation, and find that the LM relation is significantly different from the relation modelled when not account for selection effects. We find that the luminosity of our clusters is 2.2 ± 0.4 times higher (when accounting for selection effects) than the average for a given mass and its mass is 30 per cent lower than the population average for a given luminosity. Equivalently, using the LM relation measured from this sample without correcting for selection biases would lead to the underestimation by 40 per cent of the average mass of a cluster with a given luminosity. Comparing the hydrostatic masses to mass estimates determined from the YX parameter, we find that they are entirely consistent, irrespective of the dynamical state of the cluster.

  3. Cosmology with velocity dispersion counts: an alternative to measuring cluster halo masses

    CERN Document Server

    Caldwell, C E; Baldry, I K; Collins, C A; Schaye, J; Bird, S

    2016-01-01

    The evolution of galaxy cluster counts is a powerful probe of several fundamental cosmological parameters. A number of recent studies using this probe have claimed tension with the cosmology preferred by the analysis of the Planck primary CMB data, in the sense that there are fewer clusters observed than predicted based on the primary CMB cosmology. One possible resolution to this problem is systematic errors in the absolute halo mass calibration in cluster studies, which is required to convert the standard theoretical prediction (the halo mass function) into counts as a function of the observable (e.g., X-ray luminosity, Sunyaev-Zel'dovich flux, optical richness). Here we propose an alternative strategy, which is to directly compare predicted and observed cluster counts as a function of the one-dimensional velocity dispersion of the cluster galaxies. We argue that the velocity dispersion of groups/clusters can be theoretically predicted as robustly as mass but, unlike mass, it can also be directly observed, ...

  4. Study of cluster formation and its effects on Rayleigh and Raman scattering measurements in a Mach 6 wind tunnel

    Science.gov (United States)

    Shirinzadeh, B.; Hillard, M. E.; Blair, A. B.; Exton, R. J.

    1991-01-01

    Using a frequency-doubled Nd-YAG pulsed laser and a single-intensified CCD camera, Rayleigh scattering measurements have been performed to study the cluster formation in a Mach 6 wind tunnel at NASA Langley Research Center. These studies were conducted both in the free stream and in a model flow field for various flow conditions to gain an understanding of the dependence of the Rayleigh scattering (by clusters) on the local pressures and temperatures in the facility. Using the same laser system, simultaneous measurements of the local temperature have also been performed using the rotational Raman scattering of molecular nitrogen and determined the densities of molecular oxygen and nitrogen by using the vibrational Raman scattering from these species. Quantitative results are presented in detail with emphasis on the applicability of the Rayleigh scattering for obtaining quantitative measurements of molecular densities both in the free stream and in the model flow field.

  5. Photocatalytic properties of TiO2 and TiO2/Pt: a sol-precipitation, sonochemical and hydrothermal approach.

    Science.gov (United States)

    Žunič, Vojka; Vukomanović, Marija; Škapin, Srečo D; Suvorov, Danilo; Kovač, Janez

    2014-01-01

    In this work we prepared TiO2 nano-powders and TiO2/Pt nano-composites via three synthesis methods (sol-precipitation, sonochemical method, hydrothermal method) starting with the same precursors and media. To evaluate and compare the physical properties of the prepared materials, X-ray diffraction analysis, BET measurements, FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron microscopy (TEM, HRTEM, SAED) were applied. The results showed changes to the TiO2 phase composition and crystallinity, the specific surface area as well as the platinum's particle shape and size, depending on the method of synthesis. To determine the photocatalytic efficiency of the prepared materials, the photocatalytic discoloration of the methylene blue solution was evaluated using UV-Vis spectroscopy. The important properties required for a high photocatalytic activity, related to the surface characteristics and the phase composition, were determined in terms of the synthesis method. It was concluded that the optimum characteristics were obtained when using the hydrothermal approach, where the TiO2 had two phases, i.e., - anatase and rutile, a Pt-phase in the form of nanoparticles and adsorbed Pt-molecular species, as well as the presence of available free surface hydroxyl groups. Such characteristics had a critical influence on the photocatalytic activity of the final material.

  6. Epitaxial crystals of Bi2Pt2O7 pyrochlore through the transformation of δ–Bi2O3 fluorite

    Directory of Open Access Journals (Sweden)

    Araceli Gutiérrez–Llorente

    2015-03-01

    Full Text Available Bi2Pt2O7 pyrochlore is thought to be one of the most promising oxide catalysts for application in fuel cell technology. Unfortunately, direct film growth of Bi2Pt2O7 has not yet been achieved, owing to the difficulty of oxidizing platinum metal in the precursor material to Pt4+. In this work, in order to induce oxidation of the platinum, we annealed pulsed laser deposited films consisting of epitaxial δ–Bi2O3 and co-deposited, comparatively disordered platinum. We present synchrotron x-ray diffraction results that show the nonuniform annealed films contain the first epitaxial crystals of Bi2Pt2O7. We also visualized the pyrochlore structure by scanning transmission electron microscopy, and observed ordered cation vacancies in the epitaxial crystals formed in a bismuth-rich film but not in those formed in a platinum-rich film. The similarity between the δ–Bi2O3 and Bi2Pt2O7 structures appears to facilitate the pyrochlore formation. These results provide the only route to date for the formation of epitaxial Bi2Pt2O7.

  7. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS anisotropic galaxy clustering

    Science.gov (United States)

    Chuang, Chia-Hsun; Prada, Francisco; Pellejero-Ibanez, Marcos; Beutler, Florian; Cuesta, Antonio J.; Eisenstein, Daniel J.; Escoffier, Stephanie; Ho, Shirley; Kitaura, Francisco-Shu; Kneib, Jean-Paul; Manera, Marc; Nuza, Sebastián E.; Rodríguez-Torres, Sergio; Ross, Ashley; Rubiño-Martín, J. A.; Samushia, Lado; Schlegel, David J.; Schneider, Donald P.; Wang, Yuting; Weaver, Benjamin A.; Zhao, Gongbo; Brownstein, Joel R.; Dawson, Kyle S.; Maraston, Claudia; Olmstead, Matthew D.; Thomas, Daniel

    2016-10-01

    With the largest spectroscopic galaxy survey volume drawn from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), we can extract cosmological constraints from the measurements of redshift and geometric distortions at quasi-linear scales (e.g. above 50 h-1 Mpc). We analyse the broad-range shape of the monopole and quadrupole correlation functions of the BOSS Data Release 12 (DR12) CMASS galaxy sample, at the effective redshift z = 0.59, to obtain constraints on the Hubble expansion rate H(z), the angular- diameter distance DA(z), the normalized growth rate f(z)σ8(z), and the physical matter density Ωm h2. We obtain robust measurements by including a polynomial as the model for the systematic errors, and find it works very well against the systematic effects, e.g. ones induced by stars and seeing. We provide accurate measurements {DA(0.59)rs,fid/rs, H(0.59)rs/rs,fid, f(0.59)σ8(0.59), Ωm h2} = {1427 ± 26 Mpc, 97.3 ± 3.3 km s-1 Mpc-1, 0.488 ± 0.060, 0.135 ± 0.016}, where rs is the comoving sound horizon at the drag epoch and rs,fid = 147.66 Mpc is the sound scale of the fiducial cosmology used in this study. The parameters which are not well constrained by our galaxy clustering analysis are marginalized over with wide flat priors. Since no priors from other data sets, e.g. cosmic microwave background (CMB), are adopted and no dark energy models are assumed, our results from BOSS CMASS galaxy clustering alone may be combined with other data sets, i.e. CMB, SNe, lensing or other galaxy clustering data to constrain the parameters of a given cosmological model. The uncertainty on the dark energy equation of state parameter, w, from CMB+CMASS is about 8 per cent. The uncertainty on the curvature fraction, Ωk, is 0.3 per cent. We do not find deviation from flat ΛCDM.

  8. Comparison of Sunyaev-Zel'dovich measurements from Planck and from the Arcminute Microkelvin Imager for 99 galaxy clusters

    CERN Document Server

    Perrott, Y C; Rumsey, C; Brown, M L; Feroz, F; Grainge, K J B; Hobson, M P; Lasenby, A N; MacTavish, C J; Pooley, G G; Saunders, R D E; Schammel, M P; Scott, P F; Shimwell, T W; Titterington, D J; Waldram, E M; Aghanim, N; Arnaud, M; Ashdown, M; Aussel, H; Barrena, R; Bikmaev, I; Böhringer, H; Burenin, R; Carvalho, P; Chon, G; Comis, B; Dahle, H; Democles, J; Douspis, M; Harrison, D; Hempel, A; Hurier, G; Khamitov, I; Kneissl, R; Macías-Pérez, J F; Melin, J -B; Pointecouteau, E; Pratt, G W; Rubiño-Mart\\in, J A; Stolyarov, V; Sutton, D

    2014-01-01

    We present observations and analysis of a sample of 123 galaxy clusters from the 2013 Planck catalogue of Sunyaev-Zel'dovich sources with the Arcminute Microkelvin Imager (AMI), a ground-based radio interferometer. AMI provides an independent measurement with higher angular resolution, 3 arcmin compared to the Planck beams of 5-10 arcmin. The AMI observations thus provide validation of the cluster detections, improved positional estimates, and a consistency check on the fitted 'size' ($\\theta_{s}$) and 'flux' ($Y_{\\rm tot}$) parameters in the Generalised Navarro, Frenk and White (GNFW) model. We detect 99 of the clusters. We use the AMI positional estimates to check the positional estimates and error-bars produced by the Planck algorithms PowellSnakes and MMF3. We find that $Y_{\\rm tot}$ values as measured by AMI are biased downwards with respect to the Planck constraints, especially for high Planck-SNR clusters. We perform simulations to show that this can be explained by deviation from the 'universal' press...

  9. A new EEG measure using the 1D cluster variation method

    Science.gov (United States)

    Maren, Alianna J.; Szu, Harold H.

    2015-05-01

    A new information measure, drawing on the 1-D Cluster Variation Method (CVM), describes local pattern distributions (nearest-neighbor and next-nearest neighbor) in a binary 1-D vector in terms of a single interaction enthalpy parameter h for the specific case where the fractions of elements in each of two states are the same (x1=x2=0.5). An example application of this method would be for EEG interpretation in Brain-Computer Interfaces (BCIs), especially in the frontier of invariant biometrics based on distinctive and invariant individual responses to stimuli containing an image of a person with whom there is a strong affiliative response (e.g., to a person's grandmother). This measure is obtained by mapping EEG observed configuration variables (z1, z2, z3 for next-nearest neighbor triplets) to h using the analytic function giving h in terms of these variables at equilibrium. This mapping results in a small phase space region of resulting h values, which characterizes local pattern distributions in the source data. The 1-D vector with equal fractions of units in each of the two states can be obtained using the method for transforming natural images into a binarized equi-probability ensemble (Saremi & Sejnowski, 2014; Stephens et al., 2013). An intrinsically 2-D data configuration can be mapped to 1-D using the 1-D Peano-Hilbert space-filling curve, which has demonstrated a 20 dB lower baseline using the method compared with other approaches (cf. SPIE ICA etc. by Hsu & Szu, 2014). This CVM-based method has multiple potential applications; one near-term one is optimizing classification of the EEG signals from a COTS 1-D BCI baseball hat. This can result in a convenient 3-D lab-tethered EEG, configured in a 1-D CVM equiprobable binary vector, and potentially useful for Smartphone wireless display. Longer-range applications include interpreting neural assembly activations via high-density implanted soft, cellular-scale electrodes.

  10. (In,Sn)2O3/TiO2/Pt Schottky-type diode switch for the TiO2 resistive switching memory array

    Science.gov (United States)

    Shin, Yong Cheol; Song, Jaewon; Kim, Kyung Min; Choi, Byung Joon; Choi, Seol; Lee, Hyun Ju; Kim, Gun Hwan; Eom, Taeyong; Hwang, Cheol Seong

    2008-04-01

    A Schottky-type diode switch consisting of a Pt /(In,Sn)2O3/TiO2/Pt stack was fabricated for applications to cross-bar type resistive-switching memory arrays. The high (0.55eV) and low potential barrier at the TiO2/Pt and TiO2/(In,Sn)2O3 junctions, respectively, constitute the rectifying properties of the stacked structure. The forward/reverse current ratio was as high as ˜1.6×104 at an applied voltage of ˜1V. When Pt /TiO2/Pt memory was connected to this diode in series, there was an insignificant interference on the memory function from the diode under the forward bias and virtually no resistive switching under a reverse bias.

  11. Constraints on measurement-based quantum computation in effective cluster states

    CERN Document Server

    Klagges, D

    2011-01-01

    The aim of this work is to study the physical properties of a one-way quantum computer in an effective low-energy cluster state. We calculate the optimal working conditions as a function of the temperature and of the system parameters. The central result of our work is that any effective cluster state implemented in a perturbative framework is fragile against special kinds of external perturbations. Qualitative aspects of our work are important for any implementation of effective low-energy models containing strong multi-site interactions.

  12. APPLICATION OF MULTIDIMENSIONAL CLASSIFICATION TOOLS FOR INDUSTRIAL POLICY MEASURES SUBSTANTIATION: CASE OF IMDUSTRIAL CLUSTER

    Directory of Open Access Journals (Sweden)

    Svetlana Smirnova

    2015-05-01

    Full Text Available The modeling stage of development of industrial cluster is significant for the formation of industrial policy and institutional conditions for economic growth. The work deals with the modeling stage of the life cycle of industrial cluster, the results of testing applied to the petrochemical industry of the Russian Federation. Also, highlights issues approbation of this method by applying the results of simulation as a training set for building the classification tree and the interpretation of the results to justify investment and infrastructure projects.

  13. High precision single-cluster Monte Carlo measurement of the critical exponents of the classical 3D Heisenberg model

    CERN Document Server

    Holm, C

    1992-01-01

    We report measurements of the critical exponents of the classical three-dimensional Heisenberg model on simple cubic lattices of size $L^3$ with $L$ = 12, 16, 20, 24, 32, 40, and 48. The data was obtained from a few long single-cluster Monte Carlo simulations near the phase transition. We compute high precision estimates of the critical coupling $K_c$, Binder's parameter $U^* and the critical exponents $\

  14. Generating a four-photon polarization-entangled cluster state with homodyne measurement via cross-Kerr nonlinearity

    Institute of Scientific and Technical Information of China (English)

    Su Shi-Lei; Wang Yuan; Guo Qi; Wang Hong-Fu; Zhang Shou

    2012-01-01

    We propose a protocol to generate a four-photon polarization-entangled cluster state with cross-Kerr nonlinearity by using the interference of polarized photons. The protocol is based on optical elements,cross-Kerr nonlinearity,and homodyne measurement,therefore it is feasible with current experimental technology.The success probability of our protocol is optimal,this property makes our protocol more efficient than others in the applications of quantum communication.

  15. Investigation of psychophysical similarity measures for selection of similar images in the diagnosis of clustered microcalcifications on mammograms.

    Science.gov (United States)

    Muramatsu, Chisako; Li, Qiang; Schmidt, Robert; Shiraishi, Junji; Doi, Kunio

    2008-12-01

    The presentation of images with lesions of known pathology that are similar to an unknown lesion may be helpful to radiologists in the diagnosis of challenging cases for improving the diagnostic accuracy and also for reducing variation among different radiologists. The authors have been developing a computerized scheme for automatically selecting similar images with clustered microcalcifications on mammograms from a large database. For similar images to be useful, they must be similar from the point of view of the diagnosing radiologists. In order to select such images, subjective similarity ratings were obtained for a number of pairs of clustered microcalcifications by breast radiologists for establishment of a "gold standard" of image similarity, and the gold standard was employed for determination and evaluation of the selection of similar images. The images used in this study were obtained from the Digital Database for Screening Mammography developed by the University of South Florida. The subjective similarity ratings for 300 pairs of images with clustered microcalcifications were determined by ten breast radiologists. The authors determined a number of image features which represent the characteristics of clustered microcalcifications that radiologists would use in their diagnosis. For determination of objective similarity measures, an artificial neural network (ANN) was employed. The ANN was trained with the average subjective similarity ratings as teacher and selected image features as input data. The ANN was trained to learn the relationship between the image features and the radiologists' similarity ratings; therefore, once the training was completed, the ANN was able to determine the similarity, called a psychophysical similarity measure, which was expected to be close to radiologists' impressions, for an unknown pair of clustered microcalcifications. By use of a leave-one-out test method, the best combination of features was selected. The correlation

  16. The ACS Virgo Cluster Survey IV: Data Reduction Procedures for Surface Brightness Fluctuation Measurements with the Advanced Camera for Surveys

    CERN Document Server

    Mei, S; Tonry, J L; Jordan, A; Peng, E W; Côté, P; Ferrarese, L; Merritt, D; Milosavljevic, M; West, M J; Mei, Simona; Blakeslee, John P.; Tonry, John L.; Jordan, Andres; Peng, Eric W.; Cote, Patrick; Ferrarese, Laura; Merritt, David; Milosavljevic, Milos; West, Michael J.

    2005-01-01

    The Advanced Camera for Surveys (ACS) Virgo Cluster Survey is a large program to image 100 early-type Virgo galaxies using the F475W and F850LP bandpasses of the Wide Field Channel of the ACS instrument on the Hubble Space Telescope (HST). The scientific goals of this survey include an exploration of the three-dimensional structure of the Virgo Cluster and a critical examination of the usefulness of the globular cluster luminosity function as a distance indicator. Both of these issues require accurate distances for the full sample of 100 program galaxies. In this paper, we describe our data reduction procedures and examine the feasibility of accurate distance measurements using the method of surface brightness fluctuations (SBF) applied to the ACS Virgo Cluster Survey F850LP imaging. The ACS exhibits significant geometrical distortions due to its off-axis location in the HST focal plane; correcting for these distortions by resampling the pixel values onto an undistorted frame results in pixel correlations tha...

  17. Sunyaev-Zel'dovich-Measured Pressure Profiles from the Bolocam X-ray/SZ Galaxy Cluster Sample

    CERN Document Server

    Sayers, Jack; Mantz, Adam; Golwala, Sunil R; Ameglio, Silvia; Downes, Tom P; Koch, Patrick M; Lin, Kai-Yang; Maughan, Ben J; Molnar, Sandor M; Moustakas, Leonidas; Mroczkowski, Tony; Pierpaoli, Elena; Shitanishi, Jennifer A; Siegel, Seth; Umetsu, Keiichi; Van der Pyl, Nina

    2012-01-01

    We describe Sunyaev-Zel'dovich (SZ) effect measurements and analysis of the intracluster medium (ICM) pressure profiles of a set of 45 massive galaxy clusters imaged using Bolocam at the Caltech Submillimeter Observatory. We have used masses determined from Chandra X-ray observations to scale each cluster's profile by the overdensity radius R500 and the mass-and-redshift-dependent normalization factor P500. We deproject the average pressure profile of our sample into 13 logarithmically spaced radial bins between 0.07R500 and 3.5R500. We find that a generalized Navarro, Frenk, and White (gNFW) profile describes our data with sufficient goodness-of-fit and best-fit parameters (C500, alpha, beta, gamma, P0 = 1.18, 0.86, 3.67, 0.67, 4.29). We also use the X-ray data to define cool-core and disturbed subsamples of clusters, and we constrain the average pressure profiles of each of these subsamples. We find that given the precision of our data the average pressure profiles of disturbed and cool-core clusters are co...

  18. Initial Development of a Measure of Emotional Dysregulation for Individuals with Cluster B Personality Disorders

    Science.gov (United States)

    Newhill, Christina E.; Mulvey, Edward P.; Pilkonis, Paul A.

    2004-01-01

    Individuals with DSM-IV Cluster B personality disorders are at particular risk of violence toward self or others. Emotional dysregulation is likely to be a factor in such incidents and is a central issue addressed in therapies with personality-disordered individuals. This article reports findings from a study that developed an original 18-item…

  19. Spatial dependence of magnetopause energy transfer: Cluster measurements verifying global simulations

    Directory of Open Access Journals (Sweden)

    I. Dandouras

    2011-05-01

    Full Text Available We investigate the spatial variation of magnetopause energy conversion and transfer using Cluster spacecraft observations of two magnetopause crossing events as well as using a global magnetohydrodynamic (MHD simulation GUMICS-4. These two events, (16 January 2001, and 26 January 2001 are similar in all other aspects except for the sign of the interplanetary magnetic field (IMF y-component that has earlier been found to control the spatial dependence of energy transfer. In simulations of the two events using observed solar wind parameters as input, we find that the GUMICS-4 energy transfer agrees with the Cluster observations spatially and is about 30 % lower in magnitude. According to the simulation, most of the the energy transfer takes place in the plane of the IMF (as previous modelling results have suggested, and the locations of the load and generator regions on the magnetopause are controlled by the IMF orientation. Assuming that the model results are as well in accordance with the in situ observations also on other parts of the magnetopause, we are able to pin down the total energy transfer during the two Cluster magnetopause crossings. Here, we estimate that the instantaneous total power transferring through the magnetopause during the two events is at least 1500–2000 GW, agreeing with ε scaled using the mean magnetopause area in the simulation. Hence the combination of the simulation results and the Cluster observations indicate that the ε parameter is probably underestimated by a factor of 2–3.

  20. DelftCluster Railway transition zones & Switches: Factual report long-term measurements

    NARCIS (Netherlands)

    Hartman, A.D.; Hölscher, P.

    2009-01-01

    For the Delft Cluster project “Railway Transition zones” extensive field-testing has been performed. Testing took place on the railway track Gouda-Goverwelle (GoGo) on a culvert and on a Switch. Many different parties were involved in the testing and numerous different types of tests were performed.

  1. A Validation of the Spectral Power Clustering Technique (SPCT by Using a Rogowski Coil in Partial Discharge Measurements

    Directory of Open Access Journals (Sweden)

    Jorge Alfredo Ardila-Rey

    2015-10-01

    Full Text Available Both in industrial as in controlled environments, such as high-voltage laboratories, pulses from multiple sources, including partial discharges (PD and electrical noise can be superimposed. These circumstances can modify and alter the results of PD measurements and, what is more, they can lead to misinterpretation. The spectral power clustering technique (SPCT allows separating PD sources and electrical noise through the two-dimensional representation (power ratio map or PR map of the relative spectral power in two intervals, high and low frequency, calculated for each pulse captured with broadband sensors. This method allows to clearly distinguishing each of the effects of noise and PD, making it easy discrimination of all sources. In this paper, the separation ability of the SPCT clustering technique when using a Rogowski coil for PD measurements is evaluated. Different parameters were studied in order to establish which of them could help for improving the manual selection of the separation intervals, thus enabling a better separation of clusters. The signal processing can be performed during the measurements or in a further analysis.

  2. X-ray measured metallicities of the intra-cluster medium: a good measure for the metal mass?

    CERN Document Server

    Kapferer, W; Weratschnig, J; Schindler, S

    2007-01-01

    Aims. We investigate whether X-ray observations map heavy elements in the Intra-Cluster Medium (ICM) well and whether the X-ray observations yield good estimates for the metal mass, with respect to predictions on transport mech- anisms of heavy elements from galaxies into the ICM. We further test the accuracy of simulated metallicity maps. Methods. We extract synthetic X-ray spectra from N-body/hydrodynamic simulations including metal enrichment pro- cesses, which we then analyse with the same methods as are applied to observations. By changing the metal distribution in the simulated galaxy clusters, we investigate the dependence of the overall metallicity as a function of the metal distribution. In addition we investigate the difference of X-ray weighted metal maps produced by simulations and metal maps extracted from artifcial X-ray spectra, which we calculate with SPEX2.0 and analyse with XSPEC12.0. Results. The overall metallicity depends strongly on the distribution of metals within the galaxy cluster. T...

  3. Data Clustering

    Science.gov (United States)

    Wagstaff, Kiri L.

    2012-03-01

    clustering, in which some partial information about item assignments or other components of the resulting output are already known and must be accommodated by the solution. Some algorithms seek a partition of the data set into distinct clusters, while others build a hierarchy of nested clusters that can capture taxonomic relationships. Some produce a single optimal solution, while others construct a probabilistic model of cluster membership. More formally, clustering algorithms operate on a data set X composed of items represented by one or more features (dimensions). These could include physical location, such as right ascension and declination, as well as other properties such as brightness, color, temporal change, size, texture, and so on. Let D be the number of dimensions used to represent each item, xi ∈ RD. The clustering goal is to produce an organization P of the items in X that optimizes an objective function f : P -> R, which quantifies the quality of solution P. Often f is defined so as to maximize similarity within a cluster and minimize similarity between clusters. To that end, many algorithms make use of a measure d : X x X -> R of the distance between two items. A partitioning algorithm produces a set of clusters P = {c1, . . . , ck} such that the clusters are nonoverlapping (c_i intersected with c_j = empty set, i != j) subsets of the data set (Union_i c_i=X). Hierarchical algorithms produce a series of partitions P = {p1, . . . , pn }. For a complete hierarchy, the number of partitions n’= n, the number of items in the data set; the top partition is a single cluster containing all items, and the bottom partition contains n clusters, each containing a single item. For model-based clustering, each cluster c_j is represented by a model m_j , such as the cluster center or a Gaussian distribution. The wide array of available clustering algorithms may seem bewildering, and covering all of them is beyond the scope of this chapter. Choosing among them for a

  4. The Prospects for Constraining Dark Energy withFuture X-ray Cluster Gas Mass Fraction Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Rapetti, David; Allen, Steven W.

    2007-10-15

    We examine the ability of a future X-ray observatory, with capabilities similar to those planned for the Constellation-X mission, to constrain dark energy via measurements of the cluster X-ray gas mass fraction, fgas. We find that fgas measurements for a sample of {approx}500 hot (kT{approx}> 5keV), X-ray bright, dynamically relaxed clusters, to a precision of {approx}5 percent, can be used to constrain dark energy with a Dark Energy Task Force (DETF; Albrecht et al. 2006) figure of merit of 20-50. Such constraints are comparable to those predicted by the DETF for other leading, planned 'Stage IV' dark energy experiments. A future fgas experiment will be preceded by a large X-ray or SZ survey that will find hot, X-ray luminous clusters out to high redshifts. Short 'snapshot' observations with the new X-ray observatory should then be able to identify a sample of {approx}500 suitably relaxed systems. The redshift, temperature and X-ray luminosity range of interest has already been partially probed by existing X-ray cluster surveys which allow reasonable estimates of the fraction of clusters that will be suitably relaxed for fgas work to be made; these surveys also show that X-ray flux contamination from point sources is likely to be small for the majority of the targets of interest. Our analysis uses a Markov Chain Monte Carlo method which fully captures the relevant degeneracies between parameters and facilities the incorporation of priors and systematic uncertainties in the analysis. We explore the effects of such uncertainties, for scenarios ranging from optimistic to pessimistic. We conclude that the fgas experiment offers a competitive and complementary approach to the best other large, planned dark energy experiments. In particular, the fgas experiment will provide tight constraints on the mean matter and dark energy densities, with a peak sensitivity for dark energy work at redshifts midway between those of supernovae and baryon acoustic

  5. Measuring Ethnic Clustering and Exposure with the Q statistic: An Exploratory Analysis of Irish, Germans, and Yankees in 1880 Newark.

    Science.gov (United States)

    Páez, Antonio; Ruiz, Manuel; López, Fernando; Logan, John

    2012-01-01

    The study of population patterns has animated a large body of urban social research over the years. An important part of this literature is concerned with the identification and measurement of segregation patterns. Recently, emphatic calls have been made to develop measures that are better able to capture the geography of population patterns. The objective of this paper is to demonstrate the application of the Q statistic, developed for the analysis of spatial association of qualitative variables, to the detection of ethnic clustering and exposure patterns. The application is to historical data from 1880 Newark in the United States, with individuals classified by ethnicity and geo-coded by place of residence. Three ethnic groups, termed Irish, Germans, and Yankees are considered. Exploratory analysis with the Q statistic identifies significant differences in the tendency of individuals and building occupancy to cluster by ethnicity. In particular, there is evidence of a strong affinity within ethnic clusters, and some intermingling between Yankee and Irish residents. In contrast, the exposure of Germans to individuals of other groups is found to be more limited.

  6. Measuring the Redshift Evolution of Clustering the Hubble Deep Field South

    CERN Document Server

    Arnouts, S; Cristiani, S; Fontana, A; Giallongo, E; Matarrese, S; Moscardini, L; Saracco, P; Vanzella, E

    2002-01-01

    We present an analysis of the evolution of galaxy clustering in the redshift interval 0clustering signal is obtained in different redshift bins using two different approaches: a standard one, which uses the best redshift estimate of each object, and a second one, which takes into account the redshift probability function of each object. This second method makes it possible to improve the information in the redshift intervals where contamination from objects with insecure redshifts is important. With both methods, we find that the clustering strength up to z~3.5 in the HDF-S is consistent with the previous results in the HDF-N. While at redshift lower than z~1 the HDF galaxy population is un/anti-biased (b<1) with respect to the underlying dark matter, at high redshift the bias increases up to b~2-3, depending on the cosmol...

  7. Crystal structure of the coordination polymer [FeIII2{PtII(CN4}3

    Directory of Open Access Journals (Sweden)

    Maksym Seredyuk

    2015-01-01

    Full Text Available The title complex, poly[dodeca-μ-cyanido-diiron(IIItriplatinum(II], [FeIII2{PtII(CN4}3], has a three-dimensional polymeric structure. It is built-up from square-planar [PtII(CN4]2− anions (point group symmetry 2/m bridging cationic [FeIIIPtII(CN4]+∞ layers extending in the bc plane. The FeII atoms of the layers are located on inversion centres and exhibit an octahedral coordination sphere defined by six N atoms of cyanide ligands, while the PtII atoms are located on twofold rotation axes and are surrounded by four C atoms of the cyanide ligands in a square-planar coordination. The geometrical preferences of the two cations for octahedral and square-planar coordination, respectively, lead to a corrugated organisation of the layers. The distance between neighbouring [FeIIIPtII(CN4]+∞ layers corresponds to the length a/2 = 8.0070 (3 Å, and the separation between two neighbouring PtII atoms of the bridging [PtII(CN4]2− groups corresponds to the length of the c axis [7.5720 (2 Å]. The structure is porous with accessible voids of 390 Å3 per unit cell.

  8. Size-effects on energy relaxation and excited-species desorption in krypton clusters: Fluorescence lifetime measurements with 10 eV laser excitation

    Science.gov (United States)

    Kanaev, A. V.; Museur, L.; Castex, M. C.

    1997-09-01

    Fluorescence lifetime measurements of KrN clusters (N¯=2-2000) have been carried out using intense 10 eV laser excitation near 3P2 metastable atomic energy level. Two principal groups of electronically excited dimers Kr2* have been found in desorption: dimers, loosely bound near the (3P2+1S0) dissociation limit, ejected from cooled clusters and dimers undergoing vibrational relaxation from hot clusters. The desorption is principally terminated when N¯⩾50 at./cluster. The relaxation kinetics seems to converge to the properties of a solid state for 102⩽N¯⩽103 at./cluster. A variation of the Kr2*(1u/0u-) radiative lifetime, from 264 ns (in gas phase) to 440 ns (N¯=102), has been found. An equilibrium cluster temperature of 57 K has been calculated from this τ(N) dependence.

  9. First multispacecraft ion measurements in and near the Earth’s magnetosphere with the identical Cluster ion spectrometry (CIS experiment

    Directory of Open Access Journals (Sweden)

    H. Rème

    Full Text Available On board the four Cluster spacecraft, the Cluster Ion Spectrometry (CIS experiment measures the full, three-dimensional ion distribution of the major magnetospheric ions (H+, He+, He++, and O+ from the thermal energies to about 40 keV/e. The experiment consists of two different instruments: a COmposition and DIstribution Function analyser (CIS1/CODIF, giving the mass per charge composition with medium (22.5° angular resolution, and a Hot Ion Analyser (CIS2/HIA, which does not offer mass resolution but has a better angular resolution (5.6° that is adequate for ion beam and solar wind measurements. Each analyser has two different sensitivities in order to increase the dynamic range. First tests of the instruments (commissioning activities were achieved from early September 2000 to mid January 2001, and the operation phase began on 1 February 2001. In this paper, first results of the CIS instruments are presented showing the high level performances and capabilities of the instruments. Good examples of data were obtained in the central plasma sheet, magnetopause crossings, magnetosheath, solar wind and cusp measurements. Observations in the auroral regions could also be obtained with the Cluster spacecraft at radial distances of 4–6 Earth radii. These results show the tremendous interest of multispacecraft measurements with identical instruments and open a new area in magnetospheric and solar wind-magnetosphere interaction physics.

    Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetopheric configuration and dynamics; solar wind - magnetosphere interactions

  10. CLASH-X: A Comparison of Lensing and X-ray Techniques for Measuring the Mass Profiles of Galaxy Clusters

    CERN Document Server

    Donahue, Megan; Mahdavi, Andisheh; Umetsu, Keiichi; Ettori, Stefano; Merten, Julian; Postman, Marc; Hoffer, Aaron; Baldi, Alessandro; Coe, Dan; Czakon, Nicole; Bartelmann, Mattias; Benitez, Narciso; Bouwens, Rychard; Bradley, Larry; Broadhurst, Tom; Ford, Holland; Gastaldello, Fabio; Grillo, Claudio; Infante, Leopoldo; Jouvel, Stephanie; Koekemoer, Anton; Kelson, Daniel; Lahav, Ofer; Lemze, Doron; Medezinski, Elinor; Melchior, Peter; Meneghetti, Massimo; Molino, Alberto; Moustakas, John; Moustakas, Leonidas A; Nonino, Mario; Rosati, Piero; Sayers, Jack; Seitz, Stella; Van der Wel, Arjen; Zheng, Wei; Zitrin, Adi

    2014-01-01

    We present profiles of temperature, gas mass, and hydrostatic mass estimated from X-ray observations of CLASH clusters. We compare measurements from XMM and Chandra and compare both sets to CLASH gravitational lensing mass profiles. We find that Chandra and XMM measurements of electron density and enclosed gas mass as functions of radius are nearly identical, indicating that any differences in hydrostatic masses inferred from X-ray observations arise from differences in gas-temperature estimates. Encouragingly, gas temperatures measured in clusters by XMM and Chandra are consistent with one another at ~100 kpc radii but XMM temperatures systematically decline relative to Chandra temperatures as the radius of the temperature measurement increases. One plausible reason for this trend is large-angle scattering of soft X-ray photons in excess of that amount expected from the standard XMM PSF correction. We present the CLASH-X mass-profile comparisons in the form of cosmology-independent and redshift-independent c...

  11. The Next Generation Virgo Cluster Survey. V. modeling the dynamics of M87 with the made-to-measure method

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ling; Long, R. J.; Mao, Shude [National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Rd, Chaoyang District, Beijing 100012 (China); Peng, Eric W.; Li, Biao [Department of Astronomy, Peking University, Beijing 100871 (China); Liu, Chengze [Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Caldwell, Nelson [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Blakeslee, John P.; Côté, Patrick; Ferrarese, Laura; Gwyn, Stephen [National Research Council of Canada, Victoria, BC V9E 2E7 (Canada); Cuillandre, Jean-Charles [Canada-France-Hawaii Telescope Corporation, Kamuela, HI 96743 (United States); Durrell, Patrick [Department of Physics and Astronomy, Youngstown State University, One University Plaza, Youngstown, OH 44555 (United States); Emsellem, Eric [Université de Lyon 1, CRAL, Observatoire de Lyon, 9 av. Charles André, F-69230 Saint-Genis Laval, CNRS, UMR 5574, ENS de Lyon (France); Jordán, Andrés; Muñoz, Roberto; Puzia, Thomas [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago (Chile); Lançon, Ariane [Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l' Universite, F-67000 Strasbourg (France); Mei, Simona, E-mail: lzhu@mpia-hd.mpg.de [GEPI, Observatoire de Paris, 77 av. Denfert Rochereau, F-75014 Paris (France)

    2014-09-01

    We study the dynamics of the giant elliptical galaxy M87 from the central to the outermost regions with the made-to-measure (M2M) method. We use a new catalog of 922 globular cluster line-of-sight velocities extending to a projected radius of 180 kpc (equivalent to 25 M87 effective radii), and SAURON integral field unit data within the central 2.4 kpc. There are 263 globular clusters, mainly located beyond 40 kpc, newly observed by the Next Generation Virgo Survey. For the M2M modeling, the gravitational potential is taken as a combination of a luminous matter potential with a constant stellar mass-to-light ratio and a dark matter potential modeled as a logarithmic potential. Our best-fit dynamical model returns a stellar mass-to-light ratio in the I band of M/L{sub I} = 6.0 ± 0.3 M{sub ⊙} L{sub ⊙}{sup −1} with a dark matter potential scale velocity of 591 ± 50 km s{sup –1} and scale radius of 42 ± 10 kpc. We determine the total mass of M87 within 180 kpc to be (1.5 ± 0.2) × 10{sup 13} M {sub ☉}. The mass within 40 kpc is smaller than previous estimates determined using globular cluster kinematics that did not extend beyond ∼45 kpc. With our new globular cluster velocities at much larger radii, we see that globular clusters around 40 kpc show an anomalously large velocity dispersion which affected previous results. The mass we derive is in good agreement with that inferred from ROSAT X-ray observation out to 180 kpc. Within 30 kpc our mass is also consistent with that inferred from Chandra and XMM-Newton X-ray observations, while within 120 kpc it is about 20% smaller. The model velocity dispersion anisotropy β parameter for the globular clusters in M87 is small, varying from –0.2 at the center to 0.2 at ∼40 kpc, and gradually decreasing to zero at ∼120 kpc.

  12. SUNYAEV-ZEL'DOVICH-MEASURED PRESSURE PROFILES FROM THE BOLOCAM X-RAY/SZ GALAXY CLUSTER SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Sayers, J.; Czakon, N. G.; Golwala, S. R.; Downes, T. P.; Mroczkowski, T.; Siegel, S. [Division of Physics, Math, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Mantz, A. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ameglio, S.; Pierpaoli, E.; Shitanishi, J. A. [University of Southern California, Los Angeles, CA 90089 (United States); Koch, P. M.; Lin, K.-Y.; Umetsu, K. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Maughan, B. J.; Van der Pyl, N. [H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol Bs8 ITL (United Kingdom); Molnar, S. M. [LeCosPA Center, National Taiwan University, Taipei 10617, Taiwan (China); Moustakas, L., E-mail: jack@caltech.edu [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States)

    2013-05-10

    We describe Sunyaev-Zel'dovich (SZ) effect measurements and analysis of the intracluster medium (ICM) pressure profiles of a set of 45 massive galaxy clusters imaged using Bolocam at the Caltech Submillimeter Observatory. We deproject the average pressure profile of our sample into 13 logarithmically spaced radial bins between 0.07R{sub 500} and 3.5R{sub 500}, and we find that a generalized Navarro, Frenk, and White (gNFW) profile describes our data with sufficient goodness-of-fit and best-fit parameters (C{sub 500}, {alpha}, {beta}, {gamma}, P{sub 0} = 1.18, 0.86, 3.67, 0.67, 4.29). We use X-ray data to define cool-core and disturbed subsamples of clusters, and we constrain the average pressure profiles of each of these subsamples. We find that, given the precision of our data, the average pressure profiles of disturbed and cool-core clusters are consistent with one another at R {approx}> 0.15R{sub 500}, with cool-core systems showing indications of higher pressure at R {approx}< 0.15R{sub 500}. In addition, for the first time, we place simultaneous constraints on the mass scaling of cluster pressure profiles, their ensemble mean profile, and their radius-dependent intrinsic scatter between 0.1R{sub 500} and 2.0R{sub 500}. The scatter among profiles is minimized at radii between {approx_equal} 0.2R{sub 500} and {approx_equal} 0.5R{sub 500}, with a value of {approx_equal} 20%. These results for the intrinsic scatter are largely consistent with previous analyses, most of which have relied heavily on X-ray derived pressures of clusters at significantly lower masses and redshifts compared to our sample. Therefore, our data provide further evidence that cluster pressure profiles are largely universal with scatter of {approx_equal} 20%-40% about the universal profile over a wide range of masses and redshifts.

  13. High-Latitude Plasma Convection from Cluster EDI Measurements: North-South Asymmetries

    Science.gov (United States)

    Haaland, S.; Foerster, M.; Paschmann, G.; Torbert, R. B.; Vaith, H.

    2009-12-01

    Recent observations have shown that the ionospheric response to processes in the magnetosphere can be very dissimilar in the northern and southern hemispheres. In this paper we present a statistical study of ionospheric convection patterns obtained from 7 years of electric field observations from the Cluster mission. The results show some prominent asymmetries between the two hemispheres, but most of the differences can probably be attributed to ionospheric conductivities. The results also demonstrate that magnetospheric convection is not simply the result of processes in the magnetospheric boundaries and the magnetotail, but that it is modified and partly controlled by ionospheric effects.

  14. The Clustering of Galaxies in the Completed SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from DR12 galaxy clustering -- towards an accurate model

    CERN Document Server

    Chuang, Chia-Hsun; Rodríguez-Torres, Sergio; Ross, Ashley J; Zhao, Gong-bo; Wang, Yuting; Cuesta, Antonio J; Rubiño-Martín, J A; Prada, Francisco; Alam, Shadab; Beutler, Florian; Eisenstein, Daniel J; Gil-Marín, Héctor; Grieb, Jan Niklas; Ho, Shirley; Kitaura, Francisco-Shu; Percival, Will J; Rossi, Graziano; Salazar-Albornoz, Salvador; Samushia, Lado; Sánchez, Ariel G; Satpathy, Siddharth; Slosar, Anže; Tinker, Jeremy L; Tojeiro, Rita; Vargas-Magaña, Mariana; Vazquez, Jose A; Brownstein, Joel R; Nichol, Robert C; Olmstead, Matthew D

    2016-01-01

    We analyse the broad-range shape of the monopole and quadrupole correlation functions of the BOSS Data Release 12 (DR12) CMASS and LOWZ galaxy sample to obtain constraints on the Hubble expansion rate $H(z)$, the angular-diameter distance $D_A(z)$, the normalised growth rate $f(z)\\sigma_8(z)$, and the physical matter density $\\Omega_mh^2$. We adopt wide and flat priors on all model parameters in order to ensure the results are those of a `single-probe' galaxy clustering analysis. We also marginalise over three nuisance terms that account for potential observational systematics affecting the measured monopole. However, such Monte Carlo Markov Chain analysis is computationally expensive for advanced theoretical models, thus we develop a new methodology to speed up our analysis. We obtain $\\{D_A(z)r_{s,fid}/r_s$Mpc, $H(z)r_s/r_{s,fid}$kms$^{-1}$Mpc$^{-1}$, $f(z)\\sigma_8(z)$, $\\Omega_m h^2\\}$ = $\\{956\\pm28$ , $75.0\\pm4.0$ , $0.397 \\pm 0.073$, $0.143\\pm0.017\\}$ at $z=0.32$ and $\\{1421\\pm23$, $96.7\\pm2.7$ , $0.497 ...

  15. Mass Calibration and Cosmological Analysis of the SPT-SZ Galaxy Cluster Sample Using Velocity Dispersion $\\sigma_v$ and X-ray $Y_\\textrm{X}$ Measurements

    CERN Document Server

    Bocquet, S; Mohr, J J; Aird, K A; Ashby, M L N; Bautz, M; Bayliss, M; Bazin, G; Benson, B A; Bleem, L E; Brodwin, M; Carlstrom, J E; Chang, C L; Chiu, I; Cho, H M; Clocchiatti, A; Crawford, T M; Crites, A T; Desai, S; de Haan, T; Dietrich, J P; Dobbs, M A; Foley, R J; Forman, W R; Gangkofner, D; George, E M; Gladders, M D; Gonzalez, A H; Halverson, N W; Hennig, C; Hlavacek-Larrondo, J; Holder, G P; Holzapfel, W L; Hrubes, J D; Jones, C; Keisler, R; Knox, L; Lee, A T; Leitch, E M; Liu, J; Lueker, M; Luong-Van, D; Marrone, D P; McDonald, M; McMahon, J J; Meyer, S S; Mocanu, L; Murray, S S; Padin, S; Pryke, C; Reichardt, C L; Rest, A; Ruel, J; Ruhl, J E; Saliwanchik, B R; Sayre, J T; Schaffer, K K; Shirokoff, E; Spieler, H G; Stalder, B; Stanford, S A; Staniszewski, Z; Stark, A A; Story, K; Stubbs, C W; Vanderlinde, K; Vieira, J D; Vikhlinin, A; Williamson, R; Zahn, O; Zenteno, A

    2014-01-01

    We present a velocity dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg2 of the survey along with 63 velocity dispersion ($\\sigma_v$) and 16 X-ray Yx measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. The calibrations using $\\sigma_v$ and Yx are consistent at the $0.6\\sigma$ level, with the $\\sigma_v$ calibration preferring ~16% higher masses. We use the full cluster dataset to measure $\\sigma_8(\\Omega_ m/0.27)^{0.3}=0.809\\pm0.036$. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming the sum of the neutrino masses is $\\sum m_\

  16. Bayesian Nonparametric Measurement of Factor Betas and Clustering with Application to Hedge Fund Returns

    Directory of Open Access Journals (Sweden)

    Urbi Garay

    2016-03-01

    Full Text Available We define a dynamic and self-adjusting mixture of Gaussian Graphical Models to cluster financial returns, and provide a new method for extraction of nonparametric estimates of dynamic alphas (excess return and betas (to a choice set of explanatory factors in a multivariate setting. This approach, as well as the outputs, has a dynamic, nonstationary and nonparametric form, which circumvents the problem of model risk and parametric assumptions that the Kalman filter and other widely used approaches rely on. The by-product of clusters, used for shrinkage and information borrowing, can be of use to determine relationships around specific events. This approach exhibits a smaller Root Mean Squared Error than traditionally used benchmarks in financial settings, which we illustrate through simulation. As an illustration, we use hedge fund index data, and find that our estimated alphas are, on average, 0.13% per month higher (1.6% per year than alphas estimated through Ordinary Least Squares. The approach exhibits fast adaptation to abrupt changes in the parameters, as seen in our estimated alphas and betas, which exhibit high volatility, especially in periods which can be identified as times of stressful market events, a reflection of the dynamic positioning of hedge fund portfolio managers.

  17. A 3-dimensional rigid cluster thorax model for kinematic measurements during gait.

    Science.gov (United States)

    Kiernan, D; Malone, A; O'Brien, T; Simms, C K

    2014-04-11

    The trunk has been shown to work as an active segment rather than a passenger unit during gait and it is felt that trunk kinematics should be given more consideration during gait assessment. While 3-dimensional assessment of the thorax with respect to the pelvis and laboratory can provide a comprehensive description of trunk movement, the majority of existing 3-D thorax models demonstrate shortcomings such as the need for multiple skin marker configurations, difficult landmark identification and practical issues for assessment on female subjects. A small number of studies have used rigid cluster models to quantify thorax movement, however the models and points of attachment are not well described and validation rarely considered. The aim of this study was to propose an alternative rigid cluster 3-D thorax model to quantify movement during gait and provide validation of this model. A rigid mount utilising active markers was developed and applied over the 3rd thoracic vertebra, previously reported as an area of least skin movement artefact on the trunk. The model was compared to two reference thorax models through simultaneous recording during gait on 15 healthy subjects. Excellent waveform similarity was demonstrated between the proposed model and the two reference models (CMC range 0.962-0.997). Agreement of discrete parameters was very-good to excellent. In addition, ensemble average graphs demonstrated almost identical curve displacement between models. The results suggest that the proposed model can be confidently used as an alternative to other thorax models in the clinical setting.

  18. Measurement of oxidatively-induced clustered DNA lesions using a novel adaptation of single cell gel electrophoresis (comet assay).

    Science.gov (United States)

    Georgakilas, Alexandros G; Holt, Stewart M; Hair, Jessica M; Loftin, Charles W

    2010-12-01

    The two basic groups of complex DNA damage are double-strand breaks (DSBs) and non-DSB oxidatively-induced clustered DNA lesions (OCDLs). The single-cell gel electrophoresis (SCGE) or comet assay has been widely used for the detection of low levels of various types of DNA lesions including single-strand breaks (SSBs), DSBs, and oxidized bases per individual cell. There are limited data on the use of the comet assay for the detection of non-DSB clustered DNA lesions using different repair enzymes as enzymatic probes. This unit discusses a novel adaptation of the comet assay used to measure these unique types of lesions. Until now OCDL yields have been measured using primarily pulsed-field agarose gel electrophoresis. The advantages offered by the current approach are: (1) measurement of OCDL levels per individual cell; (2) use of a small number of cells (∼10,000) and relatively low doses of ionizing radiation (1 to 2 Gy) or low levels of oxidative stress, which are not compatible with standard agarose gel electrophoresis; and finally, (3) the assay is fast and allows direct comparison with pulsed-field gel electrophoresis results.

  19. Unravelling the origin of large-scale magnetic fields in galaxy clusters and beyond through Faraday Rotation Measures with the SKA

    CERN Document Server

    Bonafede, A; Brüggen, M; Akahori, T; Carretti, E; Colafrancesco, S; Feretti, L; Ferrari, C; Giovannini, G; Govoni, F; Johnston-Hollitt, M; Murgia, M; Rudnick, L; Scaife, A; Vacca, V

    2015-01-01

    We investigate the possibility for the SKA to detect and study the magnetic fields in galaxy clusters and in the less dense environments surrounding them using Faraday Rotation Measures. To this end, we produce 3-dimensional magnetic field models for galaxy clusters of different masses and in different stages of their evolution, and derive mock rotation measure observations of background radiogalaxies. According to our results, already in phase I, we will be able to infer the magnetic field properties in galaxy clusters as a function of the cluster mass, down to $10^{13}$ solar-masses. Moreover, using cosmological simulations to model the gas density, we have computed the expected rotation measure through shock-fronts that occur in the intra-cluster medium during cluster mergers. The enhancement in the rotation measure due to the density jump will permit to constraint the magnetic field strength and structure after the shock passage. SKA observations of polarised sources located behind galaxy clusters will an...

  20. CHEERS: Future perspectives for abundance measurements in clusters with XMM-Newton

    CERN Document Server

    de Plaa, J

    2016-01-01

    The CHEERS (CHEmical Enrichment RGS Sample) observations of clusters of galaxies with XMM-Newton have shown to be valuable to constrain the chemical evolution of the universe. The soft X-ray spectrum contains lines of the most abundant metals from N to Ni, which provide relatively accurate abundances that can be compared to supernova enrichment models. The accuracy of the abundances is currently limited by systematic uncertainties introduced by the available instruments and uncertainties in the modeling of the spectra, which are of the order of 20-30%. We discuss the possible gain of extending the current samples at low and high redshift. We conclude that expanding the samples would be expensive in terms of exposure time, but will not yield significantly improved results, because the current samples already reach the systematic limits. New instrumentation, like Astro-H2 and ATHENA, and improvements to the atomic databases are needed to make significant advances in this field.

  1. Clustering of Local Group distances: publication bias or correlated measurements? III. The Small Magellanic Cloud

    CERN Document Server

    de Grijs, Richard

    2015-01-01

    Aiming at providing a firm mean distance estimate to the Small Magellanic Cloud (SMC), and thus to place it within the internally consistent Local Group distance framework we recently established, we compiled the current-largest database of published distance estimates to the galaxy. Based on careful statistical analysis, we derive mean distance estimates to the SMC using eclipsing binary systems, variable stars, stellar population tracers, and star cluster properties. Their weighted mean leads to a final recommendation for the mean SMC distance of $(m-M)_0^{\\rm SMC} = 18.96 \\pm 0.02$ mag, where the uncertainty represents the formal error. Systematic effects related to lingering uncertainties in extinction corrections, our physical understanding of the stellar tracers used, and the SMC's complex geometry---including its significant line-of-sight depth, its irregular appearance which renders definition of the galaxy's center uncertain, as well as its high inclination and possibly warped disk---may contribute a...

  2. M/L, H-alpha Rotation Curves, and HI Measurements for 329 Nearby Cluster and Field Spirals: I. Data

    CERN Document Server

    Vogt, N P; Herter, T; Giovanelli, R; Vogt, Nicole P.; Haynes, Martha P.; Herter, Terry; Giovanelli, Riccardo

    2004-01-01

    A survey of 329 nearby galaxies (redshift z < 0.045) has been conducted to study the distribution of mass and light within spiral galaxies over a range of environments. The 18 observed clusters and groups span a range of richness, density, and X-ray temperature, and are supplemented by a set of 30 isolated field galaxies. Optical spectroscopy taken with the 200-inch Hale Telescope provides separately resolved H-alpha and [NII] major axis rotation curves for the complete set of galaxies, which are analyzed to yield velocity widths and profile shapes, extents and gradients. HI line profiles provide an independent velocity width measurement and a measure of HI gas mass and distribution. I-band images are used to deconvolve profiles into disk and bulge components, to determine global luminosities and ellipticities, and to check morphological classification. These data are combined to form a unified data set ideal for the study of the effects of environment upon galaxy evolution.

  3. Clustering of Local Group distances: publication bias or correlated measurements? I. The Large Magellanic Cloud

    CERN Document Server

    de Grijs, Richard; Bono, Giuseppe

    2014-01-01

    The distance to the Large Magellanic Cloud (LMC) represents a key local rung of the extragalactic distance ladder. Yet, the galaxy's distance modulus has long been an issue of contention, in particular in view of claims that most newly determined distance moduli cluster tightly - and with a small spread - around the "canonical" distance modulus, (m-M)_0 = 18.50 mag. We compiled 233 separate LMC distance determinations published between 1990 and 2013. Our analysis of the individual distance moduli, as well as of their two-year means and standard deviations resulting from this largest data set of LMC distance moduli available to date, focuses specifically on Cepheid and RR Lyrae variable-star tracer populations, as well as on distance estimates based on features in the observational Hertzsprung-Russell diagram. We conclude that strong publication bias is unlikely to have been the main driver of the majority of published LMC distance moduli. However, for a given distance tracer, the body of publications leading ...

  4. CLASH-X: A comparison of lensing and X-ray techniques for measuring the mass profiles of galaxy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Donahue, Megan; Voit, G. Mark; Hoffer, Aaron; Baldi, Alessandro [Physics and Astronomy Department, Michigan State University, East Lansing, MI 48824 (United States); Mahdavi, Andisheh [San Francisco State University, San Francisco, CA 94132 (United States); Umetsu, Keiichi; Czakon, Nicole [Institute of Astronomy and Astrophysics, Academia Sinica, Roosevelt Road, Taipei 10617, Taiwan (China); Ettori, Stefano [INFN, Sezione di Bologna, viale Berti Pichat 6/2, I-40127 Bologna (Italy); Merten, Julian [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Postman, Marc; Coe, Dan; Bradley, Larry [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bartelmann, Mattias [Universität Heidelberg, Zentrum für Astronomie, Philosophenweg 12, D-69120 Heidelberg (Germany); Benitez, Narciso [Instituto de Astrofisica de Andalucia (CSIC), C/Camino Bajo de Huétor 24, Granada E-18008 (Spain); Bouwens, Rychard [Leiden Observatories, Niels Bohrweb 2, NL-2333 CA Leiden (Netherlands); Broadhurst, Tom [Department of Theoretical Physics, University of the Basque Country, E-48080 Bilbao (Spain); Ford, Holland [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Gastaldello, Fabio [INAF-IASF, via Bassini 15, I-20133 Milan (Italy); Grillo, Claudio [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Infante, Leopoldo, E-mail: donahue@pa.msu.edu [Dept Astronomía-Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, 22 Santiago (Chile); and others

    2014-10-20

    We present profiles of temperature, gas mass, and hydrostatic mass estimated from new and archival X-ray observations of CLASH clusters. We compare measurements derived from XMM and Chandra observations with one another and compare both to gravitational lensing mass profiles derived with CLASH Hubble Space Telescope and Subaru Telescope lensing data. Radial profiles of Chandra and XMM measurements of electron density and enclosed gas mass are nearly identical, indicating that differences in hydrostatic masses inferred from X-ray observations arise from differences in gas-temperature measurements. Encouragingly, gas temperatures measured in clusters by XMM and Chandra are consistent with one another at ∼100-200 kpc radii, but XMM temperatures systematically decline relative to Chandra temperatures at larger radii. The angular dependence of the discrepancy suggests that additional investigation on systematics such as the XMM point-spread function correction, vignetting, and off-axis responses is yet required. We present the CLASH-X mass-profile comparisons in the form of cosmology-independent and redshift-independent circular-velocity profiles. We argue that comparisons of circular-velocity profiles are the most robust way to assess mass bias. Ratios of Chandra hydrostatic equilibrium (HSE) mass profiles to CLASH lensing profiles show no obvious radial dependence in the 0.3-0.8 Mpc range. However, the mean mass biases inferred from the weak-lensing (WL) and SaWLens data are different. As an example, the weighted-mean value at 0.5 Mpc is (b) = 0.12 for the WL comparison and (b) = –0.11 for the SaWLens comparison. The ratios of XMM HSE mass profiles to CLASH lensing profiles show a pronounced radial dependence in the 0.3-1.0 Mpc range, with a weighted mean mass bias value rising to (b) ≳ 0.3 at ∼1 Mpc for the WL comparison and (b) ≈ 0.25 for the SaWLens comparison. The enclosed gas mass profiles from both Chandra and XMM rise to a value ≈1/8 times the total

  5. Segmentation of synthetic aperture radar image using multiscale information measure-based spectral clustering

    Institute of Scientific and Technical Information of China (English)

    Haixia Xu; Zheng Tian; Mingtao Ding

    2008-01-01

    @@ A multiscale information measure (MIM), calculable from per-pixel wavelet coefficients, but relying on global statistics of synthetic aperture radar (SAR) image, is proposed. It fully exploits the variations in speckle pattern when the image resolution varies from course to fine, thus it can capture the intrinsic texture of the scene backscatter and the texture due to speckle simultaneously. Graph spectral segmentation methods based on MIM and the usual similarity measure are carried out on two real SAR images.Experimental results show that MIM can characterize texture information of SAR image more effectively than the commonly used similarity measure.

  6. Biosensor based on measurements of the clustering dynamics of magnetic particles

    DEFF Research Database (Denmark)

    2014-01-01

    Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample.......Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample....

  7. The clustering of massive Primordial Black Holes as Dark Matter: measuring their mass distribution with Advanced LIGO

    CERN Document Server

    Clesse, Sebastien

    2016-01-01

    The recent detection by Advanced LIGO of gravitational waves (GW) from the merging of a binary black hole system sets new limits on the merging rates of massive primordial black holes (PBH) that could be a significant fraction or even the totality of the dark matter in the Universe. aLIGO opens the way to the determination of the distribution and clustering of such massive PBH. If PBH clusters have a similar density to the one observed in ultra-faint dwarf galaxies, we find merging rates comparable to aLIGO expectations. Massive PBH dark matter predicts the existence of thousands of those dwarf galaxies where star formation is unlikely because of gas accretion onto PBH, which would possibly provide a solution to the missing satellite and too-big-to-fail problems. Finally, we study the possibility of using aLIGO and future GW antennas to measure the abundance and mass distribution of PBH in the range [5 - 200] Msun to 10\\% accuracy.

  8. Relationship between the CMB, SZ Cluster Counts, and Local Hubble Parameter Measurements in a Simple Void Model

    CERN Document Server

    Ichiki, Kiyotomo; Oguri, Masamune

    2015-01-01

    The discrepancy between the amplitudes of matter fluctuations inferred from Sunyaev-Zel'dovich (SZ) cluster number counts, the primary temperature, and the polarization anisotropies of the cosmic microwave background (CMB) measured by the Planck satellite can be reconciled if the local universe is embedded in an under-dense region as shown by Lee, 2014. Here using a simple void model assuming the open Friedmann-Robertson-Walker geometry and a Markov Chain Monte Carlo technique, we investigate how deep the local under-dense region needs to be to resolve this discrepancy. Such local void, if exists, predicts the local Hubble parameter value that is different from the global Hubble constant. We derive the posterior distribution of the local Hubble parameter from a joint fitting of the Planck CMB data and SZ cluster number counts assuming the simple void model. We show that the predicted local Hubble parameter value of $H_{\\rm loc}=70.1\\pm0.34~{\\rm km\\,s^{-1}Mpc^{-1}}$ is in better agreement with direct local Hub...

  9. The clustering of massive Primordial Black Holes as Dark Matter: Measuring their mass distribution with advanced LIGO

    Science.gov (United States)

    Clesse, Sébastien; García-Bellido, Juan

    2017-03-01

    The recent detection by Advanced LIGO of gravitational waves (GW) from the merging of a binary black hole system sets new limits on the merging rates of massive primordial black holes (PBH) that could be a significant fraction or even the totality of the dark matter in the Universe. aLIGO opens the way to the determination of the distribution and clustering of such massive PBH. If PBH clusters have a similar density to the one observed in ultra-faint dwarf galaxies, we find merging rates comparable to aLIGO expectations. Massive PBH dark matter predicts the existence of thousands of those dwarf galaxies where star formation is unlikely because of gas accretion onto PBH, which would possibly provide a solution to the missing satellite and too-big-to-fail problems. Finally, we study the possibility of using aLIGO and future GW antennas to measure the abundance and mass distribution of PBH in the range [5-200] M⊙ to 10% accuracy.

  10. Biosensor based on the measurements of clustering dynamics of magnetic particles using a double pass setup

    DEFF Research Database (Denmark)

    2014-01-01

    Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample. The setup may be implemented in a disc...

  11. Measuring Human Performance on Clustering Problems: Some Potential Objective Criteria and Experimental Research Opportunities

    Science.gov (United States)

    Brusco, Michael J.

    2007-01-01

    The study of human performance on discrete optimization problems has a considerable history that spans various disciplines. The two most widely studied problems are the Euclidean traveling salesperson problem and the quadratic assignment problem. The purpose of this paper is to outline a program of study for the measurement of human performance on…

  12. Clustering of Local Group distances: publication bias or correlated measurements? IV. The Galactic Center

    CERN Document Server

    de Grijs, Richard

    2016-01-01

    Aiming at deriving a statistically well-justified Galactic Center distance, $R_0$, and reducing any occurrence of publication bias, we compiled the most comprehensive and most complete database of Galactic Center distances available to date, containing 273 new or revised $R_0$ estimates published since records began in October 1918 until June 2016. We separate our $R_0$ compilation into direct and indirect distance measurements. The latter include a large body of estimates that rely on centroid determinations for a range of tracer populations as well as measurements based on kinematic observations of objects at the solar circle, combined with a mass and/or rotational model of the Milky Way. Careful assessment of the Galactic Center distances resulting from orbital modeling and statistical parallax measurements in the Galactic nucleus yields our final Galactic Center distance recommendation of $R_0 = 8.3 \\pm 0.2 \\mbox{ (statistical)} \\pm 0.4 \\mbox{ (systematic)}$ kpc. The centroid-based distances are in good a...

  13. A new method of measuring the cluster peculiar velocity power spectrum

    CERN Document Server

    Zhang, Pengjie; Juszkiewicz, Roman; Stebbins, Albert

    2008-01-01

    We propose to use spatial correlations of the kinetic Sunyaev-Zeldovich (KSZ) flux as an estimator of the peculiar velocity power spectrum. In contrast with conventional techniques, our new method does not require measurements of the thermal SZ signal or the X-ray temperature. Moreover, this method has the special advantage that the expected systematic errors are always sub-dominant to statistical errors on all scales and redshifts of interest. We show that future large sky coverage KSZ surveys may allow a peculiar velocity power spectrum estimates of an accuracy reaching ~10%.

  14. An Efficient Technique to Implement Similarity Measures in Text Document Clustering using Artificial Neural Networks Algorithm

    Directory of Open Access Journals (Sweden)

    K. Selvi

    2014-12-01

    Full Text Available Pattern recognition, envisaging supervised and unsupervised method, optimization, associative memory and control process are some of the diversified troubles that can be resolved by artificial neural networks. Problem identified: Of late, discovering the required information in massive quantity of data is the challenging tasks. The model of similarity evaluation is the central element in accomplishing a perceptive of variables and perception that encourage behavior and mediate concern. This study proposes Artificial Neural Networks algorithms to resolve similarity measures. In order to apply singular value decomposition the frequency of word pair is established in the given document. (1 Tokenization: The splitting up of a stream of text into words, phrases, signs, or other significant parts is called tokenization. (2 Stop words: Preceding or succeeding to processing natural language data, the words that are segregated is called stop words. (3 Porter stemming: The main utilization of this algorithm is as part of a phrase normalization development that is characteristically completed while setting up in rank recovery technique. (4 WordNet: The compilation of lexical data base for the English language is called as WordNet Based on Artificial Neural Networks, the core part of this study work extends n-gram proposed algorithm. All the phonemes, syllables, letters, words or base pair corresponds in accordance to the application. Future work extends the application of this same similarity measures in various other neural network algorithms to accomplish improved results.

  15. Photo-z Quality Cuts and their Effect on the Measured Galaxy Clustering

    CERN Document Server

    Martí, Pol; Bauer, Anne; Gaztañaga, Enrique

    2014-01-01

    Photometric galaxy surveys are an essential tool to further our understanding of the large-scale structure of the universe, its matter and energy content and its evolution. These surveys necessitate the determination of the galaxy redshifts using photometric techniques (photo-z). Oftentimes, it is advantageous to remove from the galaxy sample those for which one suspects that the photo-z estimation might be unreliable. In this paper, we show that applying these photo-z quality cuts blindly can grossly bias the measured galaxy correlations within and across photometric redshift bins. We then extend the work of Ho et al. (2012) and Ross et al. (2011) to develop a simple and effective method to correct for this using the data themselves. Finally, we apply the method to the Mega-Z catalog, containing about a million luminous red galaxies in the redshift range 0.45 < z < 0.65. After splitting the sample into four \\Delta z = 0.05 photo-z bins using the BPZ algorithm, we see how our corrections bring the measu...

  16. Clustering of local group distances: Publication bias or correlated measurements? II. M31 and beyond

    Energy Technology Data Exchange (ETDEWEB)

    De Grijs, Richard [Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871 (China); Bono, Giuseppe [Dipartimento di Fisica, Università di Roma Tor Vergata, via Della Ricerca Scientifica 1, I-00133, Roma (Italy)

    2014-07-01

    The accuracy of extragalactic distance measurements ultimately depends on robust, high-precision determinations of the distances to the galaxies in the local volume. Following our detailed study addressing possible publication bias in the published distance determinations to the Large Magellanic Cloud (LMC), here we extend our distance range of interest to include published distance moduli to M31 and M33, as well as to a number of their well-known dwarf galaxy companions. We aim at reaching consensus on the best, most homogeneous, and internally most consistent set of Local Group distance moduli to adopt for future, more general use based on the largest set of distance determinations to individual Local Group galaxies available to date. Based on a careful, statistically weighted combination of the main stellar population tracers (Cepheids, RR Lyrae variables, and the magnitude of the tip of the red-giant branch), we derive a recommended distance modulus to M31 of (m−M){sub 0}{sup M31}=24.46±0.10 mag—adopting as our calibration an LMC distance modulus of (m−M){sub 0}{sup LMC}=18.50 mag—and a fully internally consistent set of benchmark distances to key galaxies in the local volume, enabling us to establish a robust and unbiased, near-field extragalactic distance ladder.

  17. Clustering of Local Group distances: publication bias or correlated measurements? II. M31 and beyond

    CERN Document Server

    de Grijs, Richard

    2014-01-01

    The accuracy of extragalactic distance measurements ultimately depends on robust, high-precision determinations of the distances to the galaxies in the local volume. Following our detailed study addressing possible publication bias in the published distance determinations to the Large Magellanic Cloud (LMC), here we extend our distance range of interest to include published distance moduli to M31 and M33, as well as to a number of their well-known dwarf galaxy companions. We aim at reaching consensus on the best, most homogeneous, and internally most consistent set of Local Group distance moduli to adopt for future, more general use based on the largest set of distance determinations to individual Local Group galaxies available to date. Based on a careful, statistically weighted combination of the main stellar population tracers (Cepheids, RR Lyrae variables, and the magnitude of the tip of the red-giant branch), we derive a recommended distance modulus to M31 of $(m-M)_0^{\\rm M31} = 24.46 \\pm 0.10$ mag---ado...

  18. Measuring the Scatter of the Mass-Richness Relation in Galaxy Clusters in Photometric Imaging Surveys by Means of Their Correlation Function

    Energy Technology Data Exchange (ETDEWEB)

    Campa, Julia [Barcelona, Autonoma U.; Flaugher, Brenna [Fermilab; Estrada, Juan [Fermilab

    2015-12-04

    The knowledge of the scatter in the mass-observable relation is a key ingredient for a cosmological analysis based on galaxy clusters in a photometric survey. We demonstrate here how the linear bias measured in the correlation function for clusters can be used to determine the value of the scatter. The new method is tested in simulations of a 5.000 square degrees optical survey up to z~1, similar to the ongoing Dark Energy Survey. The results indicate that the scatter can be measured with a precision of 5% using this technique.

  19. The dark side of galaxy colour: evidence from new SDSS measurements of galaxy clustering and lensing

    Energy Technology Data Exchange (ETDEWEB)

    Hearin, Andrew P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States). Fermilab Center for Particle Astrophysics; Watson, Douglas F. [Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics (KICP); Becker, Matthew R. [Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics (KICP); KICP, Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Reyes, Reinabelle [Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics (KICP); Berlind, Andreas A. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Physics and Astronomy; Zentner, Andrew R. [Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC), PA (United States)

    2014-08-12

    The age matching model has recently been shown to predict correctly the luminosity L and g-r color of galaxies residing within dark matter halos. The central tenet of the model is intuitive: older halos tend to host galaxies with older stellar populations. In this paper, we demonstrate that age matching also correctly predicts the g-r color trends exhibited in a wide variety of statistics of the galaxy distribution for stellar mass M* threshold samples. In particular, we present new measurements of the galaxy two-point correlation function and the galaxy-galaxy lensing signal as a function of M* and g-r color from the Sloan Digital Sky Survey, and show that age matching exhibits remarkable agreement with these and other statistics of low-redshift galaxies. In so doing, we also demonstrate good agreement between the galaxy-galaxy lensing observed by SDSS and the signal predicted by abundance matching, a new success of this model. We describe how age matching is a specific example of a larger class of Conditional Abundance Matching models (CAM), a theoretical framework we introduce here for the first time. CAM provides a general formalism to study correlations at fixed mass between any galaxy property and any halo property. The striking success of our simple implementation of CAM provides compelling evidence that this technique has the potential to describe the same set of data as alternative models, but with a dramatic reduction in the required number of parameters. CAM achieves this reduction by exploiting the capability of contemporary N-body simulations to determine dark matter halo properties other than mass alone, which distinguishes our model from conventional approaches to the galaxy-halo connection.

  20. Detection of thin current sheets and associated reconnection in the Earth's turbulent magnetosheath using cluster multi-point measurements

    Science.gov (United States)

    Chasapis, Alexandros; Retino, Alessandro; Sahraoui, Fouad; Greco, Antonella; Vaivads, Andris; Sundkvist, David; Canu, Patrick

    2013-04-01

    Magnetic reconnection occurs in turbulent plasma within a large number of volume-filling thin current sheets and is one major candidate for energy dissipation of turbulent plasma. Such dissipation results in particle heating and non-thermal particle acceleration. In situ observations are needed to study the detailed properties of thin current sheets and associated reconnection, in order to determine its importance as a dissipation mechanism at small scales. In particular, multi-point measurements are crucial to unambiguously identify spatial scales (e.g current sheet thickness) and estimate key quantities such as E*J. Here we present a study of the properties of thin current sheets detected in the Earths magnetosheath downstream of the quasi-parallel shock by using Cluster spacecraft data. The current sheets were detected by the rotation of the magnetic field as computed by four-point measurements. We study the distribution of current sheets as a function of the magnetic shear angle θ, their duration and the waiting time between consecutive current sheets. We found that high shear (θ > 90 degrees) current sheets show different properties with respect to low shear current sheets (θ < 90 degrees). These high-shear current sheets account for about ˜ 20% of the total and have an average thickness comparable to the ion inertial length. We also compare our four-point detection method with other single-point methods (e.g. Partial Variance of Increments - PVI) and we discuss the results of such comparison.

  1. Galaxy Cluster Scaling Relations between Bolocam Sunyaev-Zel'dovich Effect and Chandra X-ray Measurements

    CERN Document Server

    Czakon, N G; Mantz, A; Golwala, S R; Downes, T P; Koch, P M; Lin, K -Y; Molnar, S M; Moustakas, L A; Mroczkowski, T; Pierpaoli, E; Shitanishi, J A; Siegel, S; Umetsu, K

    2014-01-01

    We present scaling relations between the integrated Sunyaev-Zel'dovich Effect (SZE) signal, $Y_{\\rm SZ}$, its X-ray analogue, $Y_{\\rm X}$$\\equiv$$M_{\\rm gas}$$T_{\\rm X}$, and total mass, $M_{\\rm tot}$, for the 45 galaxy clusters in the Bolocam X-ray-SZ (BOXSZ) sample. All parameters are integrated within $r_{2500}$. $Y_{2500}$ values are measured using SZE data collected with Bolocam, operating at 140 GHz at the Caltech Submillimeter Observatory (CSO). The temperature, $T_{\\rm X}$, and mass, $M_{\\rm gas,2500}$, of the intracluster medium are determined using X-ray data collected with \\emph{Chandra}, and $M_{\\rm tot}$ is derived from $M_{\\rm gas}$ using a constant gas mass fraction. Our analysis accounts for several potential sources of bias, including: selection effects, contamination from radio point sources, and the loss of SZE signal due to noise filtering and beam-smoothing effects. We measure the $Y_{2500}$-$Y_{\\rm X}$ scaling to have a logarithmic slope of $0.84\\pm0.07$, and a fractional intrinsic scatt...

  2. Mixed cerium-platinum oxides: Electronic structure of [CeO]Ptn (n = 1, 2) and [CeO2]Pt complex anions and neutrals

    Science.gov (United States)

    Ray, Manisha; Kafader, Jared O.; Topolski, Josey E.; Jarrold, Caroline Chick

    2016-07-01

    The electronic structures of several small Ce-Pt oxide complexes were explored using a combination of anion photoelectron (PE) spectroscopy and density functional theory calculations. Pt and Pt2 both accept electron density from CeO diatomic molecules, in which the cerium atom is in a lower-than-bulk oxidation state (+2 versus bulk +4). Neutral [CeO]Pt and [CeO]Pt2 complexes are therefore ionic, with electronic structures described qualitatively as [CeO+2]Pt-2 and [CeO+]Pt2-, respectively. The associated anions are described qualitatively as [CeO+]Pt-2 and [CeO+]Pt2-2, respectively. In both neutrals and anions, the most stable molecular structures determined by calculations feature a distinct CeO moiety, with the positively charged Ce center pointing toward the electron rich Pt or Pt2 moiety. Spectral simulations based on calculated spectroscopic parameters are in fair agreement with the spectra, validating the computationally determined structures. In contrast, when Pt is coupled with CeO2, which has no Ce-localized electrons that can readily be donated to Pt, the anion is described as [CeO2]Pt-. The molecular structure predicted computationally suggests that it is governed by charge-dipole interactions. The neutral [CeO2]Pt complex lacks charge-dipole stabilizing interactions, and is predicted to be structurally very different from the anion, featuring a single Pt-O-Ce bridge bond. The PE spectra of several of the complexes exhibit evidence of photodissociation with Pt- daughter ion formation. The electronic structures of these complexes are related to local interactions in Pt-ceria catalyst-support systems.

  3. Planck Intermediate Results II: Comparison of Sunyaev-Zeldovich measurements from Planck and from the Arcminute Microkelvin Imager for 11 galaxy clusters

    CERN Document Server

    Planck,; Ashdown, M; Aumont, J; Baccigalupi, C; Balbi, A; Banday, A J; Barreiro, R B; Battaner, E; Battye, R; Benabed, K; Benoît, A; Bersanelli, M; Bhatia, R; Bikmaev, I; Böhringer, H; Bonaldi, A; Bond, J R; Borrill, J; Bouchet, F R; Bourdin, H; Brown, M L; Bucher, M; Burenin, R; Burigana, C; Butler, R C; Cabella, P; Carvalho, P; Catalano, A; Cayón, L; Chamballu, A; Chary, R -R; Chiang, L -Y; Chon, G; Clements, D L; Colafrancesco, S; Colombi, S; Crill, B P; Cuttaia, F; Da Silva, A; Dahle, H; Davies, R D; Davis, R J; de Bernardis, P; de Gasperis, G; de Rosa, A; de Zotti, G; Delabrouille, J; Démoclès, J; Dickinson, C; Diego, J M; Dolag, K; Dole, H; Donzelli, S; Doré, O; Douspis, M; Dupac, X; Enßlin, T A; Eriksen, H K; Feroz, F; Finelli, F; Flores-Cacho, I; Forni, O; Fosalba, P; Frailis, M; Franceschi, E; Fromenteau, S; Ganga, K; Génova-Santos, R T; Giard, M; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Grainge, K J B; Gregorio, A; Gruppuso, A; Hansen, F K; Harrison, D; Henrot-Versillé, S; Hernández-Monteagudo, C; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Huffenberger, K M; Hurier, G; Hurley-Walker, N; Jagemann, T; Juvela, M; Keihänen, E; Khamitov, I; Kneissl, R; Knoche, J; Kunz, M; Kurki-Suonio, H; Lagache, G; Lasenby, A; Lawrence, C R; Jeune, M Le; Leach, S; Leonardi, R; Liddle, A; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Luzzi, G; Macías-Pérez, J F; MacTavish, C J; Maino, D; Mandolesi, N; Marleau, F; Marshall, D J; Martínez-González, E; Masi, S; Massardi, M; Matarrese, S; Matthai, F; Mazzotta, P; Melchiorri, A; Melin, J -B; Mendes, L; Mennella, A; Miville-Deschênes, M -A; Montier, L; Morgante, G; Munshi, D; Naselsky, P; Natoli, P; Noviello, F; Olamaie, M; Osborne, S; Pajot, F; Paoletti, D; Pasian, F; Patanchon, G; Pearson, T J; Perdereau, O; Perrott, Y C; Perrotta, F; Piacentini, F; Pierpaoli, E; Platania, P; Pointecouteau, E; Polenta, G; Popa, L; Poutanen, T; Pratt, G W; Puget, J -L; Rachen, J P; Rebolo, R; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Ristorcelli, I; Rocha, G; Rodríguez-Gonzálvez, C; Rosset, C; Rossetti, M; Rubiño-Martín, J A; Rusholme, B; Saunders, R D E; Savini, G; Schammel, M P; Scott, D; Shimwell, T W; Smoot, G F; Starck, J -L; Stivoli, F; Stolyarov, V; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Terenzi, L; Toffolatti, L; Tomasi, M; Tristram, M; Valenziano, L; Van Tent, B; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; Yvon, D; Zacchei, A; Zonca, A

    2012-01-01

    A comparison is presented of Sunyaev-Zeldovich measurements for 11 galaxy clusters as obtained by Planck and by the ground-based interferometer, the Arcminute Microkelvin Imager. Assuming a universal spherically-symmetric Generalised Navarro, Frenk & White (GNFW) model for the cluster gas pressure profile, we jointly constrain the integrated Compton-Y parameter (Y_500) and the scale radius (theta_500) of each cluster. Our resulting constraints in the Y_500-theta_500 2D parameter space derived from the two instruments overlap significantly for eight of the clusters, although, overall, there is a tendency for AMI to find the Sunyaev-Zeldovich signal to be smaller in angular size and fainter than Planck. Significant discrepancies exist for the three remaining clusters in the sample, namely A1413, A1914, and the newly-discovered Planck cluster PLCKESZ G139.59+24.18. The robustness of the analysis of both the Planck and AMI data is demonstrated through the use of detailed simulations, which also discount confu...

  4. Normal-state charge dynamics of ternary platinum germanide superconductor La{sub 2}Pt{sub 3}Ge{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Song, S. J.; Moon, S. J. [Dept. of Physics, Hanyang University, Seoul (Korea, Republic of); Sung, N. H.; Cho, B. K. [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of)

    2015-12-15

    We report on the infrared spectroscopic studies of the normal-state electronic response of rare-earth ternary platinum germanide superconductor La{sub 2}Pt{sub 3}Ge{sub 5}. We analyzed the temperature-dependent optical conductivity spectra using the Drude-Lorentz oscillator model. We found that the two Drude responses with distinct scattering rates are required to explain the charge dynamics at 10 K while a single Drude mode could reproduce the far-infrared conductivity at higher temperatures. Our results indicated the two-band character of the electronic structure and highlighted the disparate temperature evolution of the electrodynamics of the two electronic states.

  5. Pt/MOx/SiO2, Pt/MOx/TiO2, and Pt/MOx/Al2O3 Catalysts for CO Oxidation

    OpenAIRE

    Hongmei Qin; Xiaoshuang Qian; Tao Meng; Yi Lin; Zhen Ma

    2015-01-01

    Conventional supported Pt catalysts have often been prepared by loading Pt onto commercial supports, such as SiO2, TiO2, Al2O3, and carbon. These catalysts usually have simple metal-support (i.e., Pt-SiO2) interfaces. To tune the catalytic performance of supported Pt catalysts, it is desirable to modify the metal-support interfaces by incorporating an oxide additive into the catalyst formula. Here we prepared three series of metal oxide-modified Pt catalysts (i.e., Pt/MOx/SiO2, Pt/MOx/TiO2, a...

  6. The effect of H2SO4 - amine clustering on chemical ionization mass spectrometry (CIMS) measurements of gas-phase sulfuric acid

    DEFF Research Database (Denmark)

    Kurten, T.; Petaja, T.; Smith, J.;

    2011-01-01

    by the CIMS instrument, though the most reliable computational methods employed predict this fraction to be small; on the order of ten percent or less. Third, the amine molecules will evaporate practically immediately after charging, thus evading detection. These effects may need to be taken into account......The state-of-the art method for measuring atmospheric gas-phase sulfuric acid is chemical ionization mass spectrometry (CIMS) based on nitrate reagent ions. We have assessed the possible effect of the sulfuric acid molecules clustering with base molecules on CIMS measurements using computational...... chemistry. From the computational data, three conclusions can be drawn. First, a significant fraction of the gas-phase sulfuric acid molecules are very likely clustered with amines if the amine concentration is around or above a few ppt. Second, some fraction of these acid-amine clusters may not be charged...

  7. Heat flux measured acoustically at Grotto Vent, a hydrothermal vent cluster on the Endeavour Segment, Juan de Fuca Ridge

    Science.gov (United States)

    Xu, G.; Jackson, D. R.; Bemis, K. G.; Rona, P. A.

    2013-12-01

    Over the past several decades, quantifying the heat output has been a unanimous focus of studies at hydrothermal vent fields discovered around the global ocean. Despite their importance, direct measurements of hydrothermal heat flux are very limited due to the remoteness of most vent sites and the complexity of hydrothermal venting. Moreover, almost all the heat flux measurements made to date are snapshots and provide little information on the temporal variation that is expected from the dynamic nature of a hydrothermal system. The Cabled Observatory Vent Imaging Sonar (COVIS, https://sites.google.com/a/uw.edu/covis/) is currently connected to the Endeavour node of the NEPTUNE Canada observatory network (http://www.neptunecanada.ca) to monitor the hydrothermal plumes issuing from a vent cluster (Grotto) on the Endeavour Segment of the Juan de Fuca Ridge. COVIS is acquiring a long-term (20-months to date) time series of the vertical flow rate and volume flux of the hydrothermal plume above Grotto through the Doppler analysis of the acoustic backscatter data (Xu et al., 2013). We then estimate the plume heat flux from vertical flow rate and volume flux using our newly developed inverse method. In this presentation, we will briefly summarize the derivation of the inverse method and present the heat-flux time series obtained consequently with uncertainty quantification. In addition, we compare our heat-flux estimates with the one estimated from the plume in-situ temperatures measured using a Remotely Operative Vehicle (ROV) in 2012. Such comparison sheds light on the uncertainty of our heat flux estimation. Xu, G., Jackson, D., Bemis, K., and Rona, P., 2013, Observations of the volume flux of a seafloor hydrothermal plume using an acoustic imaging sonar, Geochemistry, Geophysics Geosystems, 2013 (in press).

  8. CLASH-VLT: CONSTRAINTS ON THE DARK MATTER EQUATION OF STATE FROM ACCURATE MEASUREMENTS OF GALAXY CLUSTER MASS PROFILES

    Energy Technology Data Exchange (ETDEWEB)

    Sartoris, Barbara; Borgani, Stefano; Girardi, Marisa [Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, Via Tiepolo 11, I-34143 Trieste (Italy); Biviano, Andrea; Balestra, Italo; Nonino, Mario [INAF/Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34143 Trieste (Italy); Rosati, Piero [Dipartimento di Fisica e Scienze della Terra, Universita' di Ferrara, Via Saragat 1, I-44122 Ferrara (Italy); Umetsu, Keiichi; Czakon, Nicole [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Bartelmann, Matthias [Zentrum für Astronomie der Universität Heidelberg, ITA, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Grillo, Claudio [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Lemze, Doron; Medezinski, Elinor [Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Zitrin, Adi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Mercurio, Amata [INAF/Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli (Italy); Postman, Marc; Bradley, Larry; Coe, Dan [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Broadhurst, Tom [Department of Theoretical Physics, University of the Basque Country, P.O. Box 644, E-48080 Bilbao (Spain); Melchior, Peter, E-mail: sartoris@oats.inaf.it [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); and others

    2014-03-01

    A pressureless scenario for the dark matter (DM) fluid is a widely adopted hypothesis, despite the absence of direct observational evidence. According to general relativity, the total mass-energy content of a system shapes the gravitational potential well, but different test particles perceive this potential in different ways depending on their properties. Cluster galaxy velocities, being <cluster mass. We exploit this phenomenon to constrain the equation of state (EoS) parameter of the fluid, primarily DM, contained in galaxy clusters. We use complementary information provided by the kinematic and lensing mass profiles of the galaxy cluster MACS 1206.2–0847 at z = 0.44, as obtained in an extensive imaging and spectroscopic campaign within the Cluster Lensing And Supernova survey with Hubble. The unprecedented high quality of our data set and the properties of this cluster are well suited to determine the EoS parameter of the cluster fluid. Since baryons contribute at most 15% to the total mass in clusters and their pressure is negligible, the EoS parameter we derive describes the behavior of the DM fluid. We obtain the most stringent constraint on the DM EoS parameter to date, w = (p{sub r} + 2 p{sub t} )/(3 c {sup 2}ρ) = 0.00 ± 0.15 (stat) ± 0.08 (syst), averaged over the radial range 0.5 Mpc ≤ r ≤ r {sub 200}, where p{sub r} and p{sub t} are the radial and tangential pressure, and ρ is the density. We plan to further improve our constraint by applying the same procedure to all clusters from the ongoing Cluster Lensing And Supernova Survey with Hubble-Very Large Telescope program.

  9. Detection of quasi-periodic processes in repeated measurements: New approach for the fitting and clusterization of different data

    Science.gov (United States)

    Nigmatullin, R.; Rakhmatullin, R.

    2014-12-01

    Many experimentalists were accustomed to think that any independent measurement forms a non-correlated measurement that depends weakly from others. We are trying to reconsider this conventional point of view and prove that similar measurements form a strongly-correlated sequence of random functions with memory. In other words, successive measurements "remember" each other at least their nearest neighbors. This observation and justification on real data help to fit the wide set of data based on the Prony's function. The Prony's decomposition follows from the quasi-periodic (QP) properties of the measured functions and includes the Fourier transform as a partial case. New type of decomposition helps to obtain a specific amplitude-frequency response (AFR) of the measured (random) functions analyzed and each random function contains less number of the fitting parameters in comparison with its number of initial data points. Actually, the calculated AFR can be considered as the generalized Prony's spectrum (GPS), which will be extremely useful in cases where the simple model pretending on description of the measured data is absent but vital necessity of their quantitative description is remained. These possibilities open a new way for clusterization of the initial data and new information that is contained in these data gives a chance for their detailed analysis. The electron paramagnetic resonance (EPR) measurements realized for empty resonator (pure noise data) and resonator containing a sample (CeO2 in our case) confirmed the existence of the QP processes in reality. But we think that the detection of the QP processes is a common feature of many repeated measurements and this new property of successive measurements can attract an attention of many experimentalists. To formulate some general conditions that help to identify and then detect the presence of some QP process in the repeated experimental measurements. To find a functional equation and its solution that

  10. Solar wind entry via flux tube into magnetosphere observed by Cluster measurements at dayside magnetopause during southward IMF

    Institute of Scientific and Technical Information of China (English)

    YAN GuangQing; LIU ZhenXing; SHEN Chao; M.Dunlop; A.Balogh; H.Rème; Y.V.Bogdanova; A.Fazakerley

    2009-01-01

    By analyzing hot ion and electron parameters together with magnetic field measurements from Cluster,an event of magnetopause crossing of the spacecraft has been investigated. At the latitude of about 40°and magnetic local time (MLT) of 13:20 during the southward interplanetary magnetic field (IMF), a transition layer was observed, with the magnetospheric field configuration and cold dense plasma features of the magnetosheath. The particle energy-time spectrograms inside the layer were similar to but still a little different from those in the magnetosheath, obviously indicating the solar wind entry into the magnetosphere. The direction and magnitude of the accelerated ion flow implied that reconnection might possibly cause such a solar wind entry phenomenon. The bipolar signature of the normal magnetic component BN in magnetopause coordinates further supported happening of reconnection there.The solar wind plasma flowed toward the magnetopause and entered the magnetosphere along the reconnected flux tube. The magnetospheric branch of the reconnected flux tube was still inside the magnetosphere after reconnection and supplied the path for the solar wind entry into the dayside magnetosphere. The case analysis gives observational evidence and more details of how the reconnection process at the dayside low latitude magnetopause caused the solar wind entry into the magnetosphere.

  11. Solar wind entry via flux tube into magnetosphere observed by Cluster measurements at dayside magnetopause during southward IMF

    Institute of Scientific and Technical Information of China (English)

    M.; Dunlop; A.; Balogh; H.; Rème; Y.; V.; Bogdanova; A.; Fazakerley

    2009-01-01

    By analyzing hot ion and electron parameters together with magnetic field measurements from Cluster, an event of magnetopause crossing of the spacecraft has been investigated. At the latitude of about 40° and magnetic local time (MLT) of 13:20 during the southward interplanetary magnetic field (IMF), a transition layer was observed, with the magnetospheric field configuration and cold dense plasma features of the magnetosheath. The particle energy-time spectrograms inside the layer were similar to but still a little different from those in the magnetosheath, obviously indicating the solar wind entry into the magnetosphere. The direction and magnitude of the accelerated ion flow implied that reconnection might possibly cause such a solar wind entry phenomenon. The bipolar signature of the normal magnetic component BN in magnetopause coordinates further supported happening of reconnection there. The solar wind plasma flowed toward the magnetopause and entered the magnetosphere along the reconnected flux tube. The magnetospheric branch of the reconnected flux tube was still inside the magnetosphere after reconnection and supplied the path for the solar wind entry into the dayside magnetosphere. The case analysis gives observational evidence and more details of how the reconnection process at the dayside low latitude magnetopause caused the solar wind entry into the magnetosphere.

  12. Coupling between whistler waves and ion-scale solitary waves: cluster measurements in the magnetotail during a substorm.

    Science.gov (United States)

    Tenerani, A; Le Contel, O; Califano, F; Pegoraro, F; Robert, P; Cornilleau-Wehrlin, N; Sauvaud, J A

    2012-10-12

    We present a new model of self-consistent coupling between low frequency, ion-scale coherent structures with high frequency whistler waves in order to interpret Cluster data. The idea relies on the possibility of trapping whistler waves by inhomogeneous external fields where they can be spatially confined and propagate for times much longer than their characteristic electronic time scale. Here we take the example of a slow magnetosonic soliton acting as a wave guide in analogy with the ducting properties of an inhomogeneous plasma. The soliton is characterized by a magnetic dip and density hump that traps and advects high frequency waves over many ion times. The model represents a new possible way of explaining space measurements often detecting the presence of whistler waves in correspondence to magnetic depressions and density humps. This approach, here given by means of slow solitons, but more general than that, is alternative to the standard approach of considering whistler wave packets as associated with nonpropagating magnetic holes resulting from a mirror-type instability.

  13. Measuring human rights violations in a conflict-affected country: results from a nationwide cluster survey in Central African Republic

    Directory of Open Access Journals (Sweden)

    Roberts Les

    2011-03-01

    Full Text Available Abstract Background Measuring human rights violations is particularly challenging during or after armed conflict. A recent nationwide survey in the Central African Republic produced estimates of rates of grave violations against children and adults affected by armed conflict, using an approach known as the "Neighborhood Method". Methods In June and July, 2009, a random household survey was conducted based on population estimates from the 2003 national census. Clusters were assigned systematically proportional to population size. Respondents in randomly selected households were interviewed regarding incidents of killing, intentional injury, recruitment into armed groups, abduction, sexual abuse and rape between January 1, 2008 and the date of interview, occurring in their homes' and those of their three closest neighbors. Results Sixty of the selected 69 clusters were surveyed. In total, 599 women were interviewed about events in 2,370 households representing 13,669 persons. Estimates of annual rates of each violation occurring per 1000 people in each of two strata are provided for children between the ages of five and 17, adults 18 years of age and older and the entire population five years and older, along with a combined and weighted national rate. The national rates for children age five to 17 were estimated to be 0.98/1000/year (95% CI: 0.18 - 1.78 for recruitment, 2.56/1000/year (95% CI: 1.50 - 3.62 for abduction, 1.13/1000/year (95% CI: 0.33 - 1.93 for intentional injury, 10.72/1000 girls/year (95% CI: 7.40 - 14.04 for rape, and 4.80/1000 girls/year (95% CI: 2.61 - 6.00 for sexual abuse. No reports of any violation against a person under the age of five were recorded and there were no reports of rape or sexual abuse of males. No children were reported to have been killed during the recall period. Rape and abduction were the most frequently reported events. Conclusions The population-based figures greatly augment existing information on

  14. Pt/MOx/SiO2, Pt/MOx/TiO2, and Pt/MOx/Al2O3 Catalysts for CO Oxidation

    Directory of Open Access Journals (Sweden)

    Hongmei Qin

    2015-04-01

    Full Text Available Conventional supported Pt catalysts have often been prepared by loading Pt onto commercial supports, such as SiO2, TiO2, Al2O3, and carbon. These catalysts usually have simple metal-support (i.e., Pt-SiO2 interfaces. To tune the catalytic performance of supported Pt catalysts, it is desirable to modify the metal-support interfaces by incorporating an oxide additive into the catalyst formula. Here we prepared three series of metal oxide-modified Pt catalysts (i.e., Pt/MOx/SiO2, Pt/MOx/TiO2, and Pt/MOx/Al2O3, where M = Al, Fe, Co, Cu, Zn, Ba, La for CO oxidation. Among them, Pt/CoOx/SiO2, Pt/CoOx/TiO2, and Pt/CoOx/Al2O3 showed the highest catalytic activities. Relevant samples were characterized by N2 adsorption-desorption, X-ray diffraction (XRD, transmission electron microscopy (TEM, H2 temperature-programmed reduction (H2-TPR, X-ray photoelectron spectroscopy (XPS, CO temperature-programmed desorption (CO-TPD, O2 temperature-programmed desorption (O2-TPD, and CO2 temperature-programmed desorption (CO2-TPD.

  15. Cluster analysis for applications

    CERN Document Server

    Anderberg, Michael R

    1973-01-01

    Cluster Analysis for Applications deals with methods and various applications of cluster analysis. Topics covered range from variables and scales to measures of association among variables and among data units. Conceptual problems in cluster analysis are discussed, along with hierarchical and non-hierarchical clustering methods. The necessary elements of data analysis, statistics, cluster analysis, and computer implementation are integrated vertically to cover the complete path from raw data to a finished analysis.Comprised of 10 chapters, this book begins with an introduction to the subject o

  16. LoCuSS: Hydrostatic Mass Measurements of the High-$L_X$ Cluster Sample -- Cross-calibration of Chandra and XMM-Newton

    CERN Document Server

    Martino, Rossella; Bourdin, Hervé; Smith, Graham P; Bartalucci, Iacopo; Marrone, Daniel P; Finoguenov, Alexis; Okabe, Nobuhiro

    2014-01-01

    We present a consistent analysis of Chandra and XMM-Newton observations of an approximately mass-selected sample of 50 galaxy clusters at $0.15cluster mass measurements, we derive the mass profiles of the 21 clusters that have been observed with both satellites, extracting surface brightness and temperature profiles from identical regions of the respective datasets. We obtain consistent results for the gas and total hydrostatic cluster masses: the average ratio of Chandra- to XMM-Newton-based measurements of $M_{\\rm gas}$ and $M_X$ at $r_{500}$ are $0.99\\pm0.02$ and $1.02\\pm0.05$, respectively with an intrinsic scatter of $\\sim3\\%$ for gas masses and $\\sim8...

  17. Cluster headache

    Science.gov (United States)

    Histamine headache; Headache - histamine; Migrainous neuralgia; Headache - cluster; Horton's headache; Vascular headache - cluster ... A cluster headache begins as a severe, sudden headache. The headache commonly strikes 2 to 3 hours after you fall ...

  18. Chandra measurements of non-thermal X-ray emission from massive, merging, radio-halo clusters

    CERN Document Server

    Million, E T

    2008-01-01

    We report the discovery of spatially-extended, non-thermal or hot, quasi-thermal emission components in Chandra X-ray spectra for five of a sample of seven massive, merging galaxy clusters with powerful radio halos: Abell 665, 2163, 2255, 2319, and 1E0657-56. The emission components can be fitted by power-law models with mean photon indices in the range 1.4 20 keV. A control sample of regular, dynamically relaxed clusters without radio halos but with comparable thermal temperatures and luminosities shows no evidence for similar components in their Chandra spectra. Detailed X-ray spectral mapping reveals the complex thermodynamic states of the radio halo clusters. We report the discovery of a clear, large-scale shock front in Abell 2219. Our deepest observations, of the Bullet Cluster 1E0657-56, demonstrate a spatial correlation between the strongest power law X-ray emission, highest thermal pressure, and brightest 1.34GHz radio halo emission in this cluster. The integrated flux and mean spectral index of the...

  19. Star Clusters

    OpenAIRE

    Gieles, M.

    1993-01-01

    Star clusters are observed in almost every galaxy. In this thesis we address several fundamental problems concerning the formation, evolution and disruption of star clusters. From observations of (young) star clusters in the interacting galaxy M51, we found that clusters are formed in complexes of stars and star clusters. These complexes share similar properties with giant molecular clouds, from which they are formed. Many (70%) of the young clusters will not survive the fist 10 Myr, due to t...

  20. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: galaxy clustering measurements in the low redshift sample of Data Release 11

    CERN Document Server

    Tojeiro, Rita; Burden, Angela; Samushia, Lado; Manera, Marc; Percival, Will J; Beutler, Florian; Cuesta, Antonio J; Dawson, Kyle; Eisenstein, Daniel J; Ho, Shirley; Howett, Cullan; McBride, Cameron K; Montesano, Francisco; Parejko, John K; Reid, Beth; Sánchez, Ariel G; Schlegel, David J; Schneider, Donald P; Tinker, Jeremy L; Magaña, Mariana Vargas; White, Martin

    2014-01-01

    We present the distance measurement to z = 0.32 using the 11th data release of the Sloan Digital Sky Survey-III Baryon Acoustic Oscillation Survey (BOSS). We use 313,780 galaxies of the low-redshift (LOWZ) sample over 7,341 square-degrees to compute $D_V = (1264 \\pm 25)(r_d/r_{d,fid})$ - a sub 2% measurement - using the baryon acoustic feature measured in the galaxy two-point correlation function and power-spectrum. We compare our results to those obtained in DR10. We study observational systematics in the LOWZ sample and quantify potential effects due to photometric offsets between the northern and southern Galactic caps. We find the sample to be robust to all systematic effects found to impact on the targeting of higher-redshift BOSS galaxies, and that the observed north-south tensions can be explained by either limitations in photometric calibration or by sample variance, and have no impact on our final result. Our measurement, combined with the baryonic acoustic scale at z = 0.57, is used in Anderson et a...

  1. The {\\triangledown}^{\\!\\!\\!\\!\\!\\!\\smash{\\raise2pt\\\\ssty\\rightharpoonup}} \\cdot \\skew2\\vec{E} term does not change the Aharonov-Casher scattering cross section

    Science.gov (United States)

    Shikakhwa, M. S.; Al-Qaq, E.

    2010-09-01

    The Aharonov-Casher (AC) Hamiltonian with the inclusion of the {\\triangledown}^{\\!\\!\\!\\!\\!\\!\\smash{\\raise2pt\\\\ssty\\rightharpoonup}} \\cdot \\skew2\\vec{E} term, which introduces a new singular interaction at the origin, is considered. Proceeding within the framework of the model of a finite-radius filament that is shrunk to zero at the end, the effect of the inclusion of this term on the original AC cross section is investigated. While the inclusion of this term gives rise to components of the radial wavefunctions that are irregular at the origin, it is found that the original AC cross section is the same whether one includes it or not, and regardless of whether the resulting singular interaction is attractive or repulsive. The underlying physics is discussed, and the physical equivalence with the spin one-half AB case is established.

  2. Reacción de ligandos azufrados con el complejo au2pt (ch2p(Sph24,cl2

    Directory of Open Access Journals (Sweden)

    Guillermo Garzón

    2010-07-01

    Full Text Available Se describe la reacción de intercambio del cloro en el complejo au2pt (ch2p(Sph24,cl2 por los ligandos SCH2Ph-,S2CN(CH2CH3,2- y SCN-. Los nuevos derivados azufrados se caracterizan por análisis químico, espectroscopia infrarroja, electrónica y resonancia magnética nuclear protónica. Los ligandos se coordinan por el azufre a los dos átomos sw oro metálico en forma simétrica. El análisis elemental concuerda con las estequiomctrías y estructuras propuestas.

  3. High-latitude plasma convection during Northward IMF as derived from in-situ magnetospheric Cluster EDI measurements

    Directory of Open Access Journals (Sweden)

    M. Förster

    2008-09-01

    Full Text Available In this study, we investigate statistical, systematic variations of the high-latitude convection cell structure during northward IMF. Using 1-min-averages of Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for six and a half years (February 2001 till July 2007, and mapping the spatially distributed measurements to a common reference plane at ionospheric level in a magnetic latitude/MLT grid, we obtained regular drift patterns according to the various IMF conditions. We focus on the particular conditions during northward IMF, where lobe cells at magnetic latitudes >80° with opposite (sunward convection over the central polar cap are a permanent feature in addition to the main convection cells at lower latitudes. They are due to reconnection processes at the magnetopause boundary poleward of the cusp regions. Mapped EDI data have a particular good coverage within the central part of the polar cap, so that these patterns and their dependence on various solar wind conditions are well verified in a statistical sense. On average, 4-cell convection pattern are shown as regular structures during periods of nearly northward IMF with the tendency of a small shift toward negative clock angles. The positions of these high-latitude convection foci are within 79° to 85° magnetic latitude and 09:00–15:00 MLT. The MLT positions are approximately symmetric ±2 h about 11:30 MLT, i.e. slightly offset from midday toward prenoon hours, while the maximum (minimum potential of the high-latitude cells is at higher magnetic latitudes near their maximum potential difference at ≈−10° to −15° clock angle for the North (South Hemisphere. With increasing clock angle distances from ≈IMFBz+, a gradual transition occurs from the 4-cell pattern via a 3-cell to the common 2-cell convection pattern, in the course of which one of the medium-scale high-latitude dayside cells diminishes and disappears while the

  4. Diffuse optical intracluster light as a measure of stellar tidal stripping: the cluster CL0024+17 at $z\\sim $0.4 observed at LBT

    CERN Document Server

    Giallongo, E; Grazian, A; Gallozzi, S; Castellano, M; Fiore, F; Fontana, A; Pentericci, L; Boutsia, K; Paris, D; Speziali, R; Testa, V

    2013-01-01

    We have evaluated the diffuse intracluster light (ICL) in the central core of the galaxy cluster CL0024+17 at $z\\sim 0.4$ observed with the prime focus camera (LBC) at LBT. The measure required an accurate removal of the galaxies light within $\\sim 200$ kpc from the center. The residual background intensity has then been integrated in circular apertures to derive the average ICL intensity profile. The latter shows an approximate exponential decline as expected from theoretical cold dark matter models. The radial profile of the ICL over the galaxies intensity ratio (ICL fraction) is increasing with decreasing radius but near the cluster center it starts to bend and then decreases where the overlap of the halos of the brightest cluster galaxies becomes dominant. Theoretical expectations in a simplified CDM scenario show that the ICL fraction profile can be estimated from the stripped over galaxy stellar mass ratio in the cluster. It is possible to show that the latter quantity is almost independent of the prope...

  5. CLASH-VLT: Constraints on the Dark Matter Equation of State from Accurate Measurements of Galaxy Cluster Mass Profiles

    CERN Document Server

    Sartoris, Barbara; Rosati, Piero; Borgani, Stefano; Umetsu, Keiichi; Bartelmann, Matthias; Girardi, Marisa; Grillo, Claudio; Lemze, Doron; Zitrin, Adi; Balestra, Italo; Mercurio, Amata; Nonino, Mario; Postman, Marc; Czakon, Nicole; Bradley, Larry; Broadhurst, Tom; Coe, Dan; Medezinski, Elinor; Melchior, Peter; Meneghetti, Massimo; Merten, Julian; Annunziatella, Marianna; Benitez, Narciso; Czoske, Oliver; Donahue, Megan; Ettori, Stefano; Ford, Holland; Fritz, Alexander; Kelson, Dan; Koekemoer, Anton; Kuchner, Ulrike; Lombardi, Marco; Maier, Christian; Mou, Leonidas A; Munari, Emiliano; Presotto, Valentina; Scodeggio, Marco; Seitz, Stella; Tozzi, Paolo; Zheng, Wei; Ziegler, Bodo

    2014-01-01

    A pressureless scenario for the Dark Matter (DM) fluid is a widely adopted hypothesis, despite the absence of a direct observational evidence. According to general relativity, the total mass-energy content of a system shapes the gravitational potential well, but different test particles perceive this potential in different ways depending on their properties. Cluster galaxy velocities, being $\\ll$c, depend solely on the gravitational potential, whereas photon trajectories reflect the contributions from the gravitational potential plus a relativistic-pressure term that depends on the cluster mass. We exploit this phenomenon to constrain the Equation of State (EoS) parameter of the fluid, primarily DM, contained in galaxy clusters. We use the complementary information provided by the kinematic and lensing mass profiles of the galaxy cluster MACS 1206.2-0847 at $z=0.44$, as obtained in an extensive imaging and spectroscopic campaign within the CLASH survey. The unprecedented high quality of our data-set and the p...

  6. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: single-probe measurements from CMASS and LOWZ anisotropic galaxy clustering

    CERN Document Server

    Chuang, Chia-Hsun; Beutler, Florian; Eisenstein, Daniel J; Escoffier, Stephanie; Ho, Shirley; Kneib, Jean-Paul; Manera, Marc; Nuza, Sebastian E; Schlegel, David J; Schneider, Donald P; Weaver, Benjamin A; Brownstein, Joel R; Dawson, Kyle S; Maraston, Claudia; Thomas, Daniel

    2013-01-01

    With the largest spectroscopic galaxy survey volume drawn from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), we can extract cosmological constraints from the measurements of redshift and geometric distortions at quasi-linear scales (e.g. above 50 Mpc/h), which can be modeled by perturbation theory. We analyze the broad-range shape of the monopole and quadrupole correlation functions of the BOSS Data Release 11 (DR11) CMASS galaxy sample, at the effective redshift z=0.57, to obtain constraints on the Hubble expansion rate H(z), the angular-diameter distance D_A(z), the normalized growth rate f(z)\\sigma_8(z), and the physical matter density \\Omega_mh^2. We provide accurate measurements on {H^{-1}R_{fid}^{-1.0}, D_A R_{fid}^{-0.96}, f\\sigma_8(\\Omega_m h^2)^{0.45}}, where R_{fid}\\equiv r_s/r_{s,fid}, r_s is the comoving sound horizon at the drag epoch, and r_{s,fid} is the sound scale of the fiducial cosmology used in this study. We also extract cosmological constraints from BOSS DR11 LOWZ sample, ...

  7. Comparison of intraclass correlation coefficient estimates and standard errors between using cross-sectional and repeated measurement data: the Safety Check cluster randomized trial.

    Science.gov (United States)

    Ip, Edward H; Wasserman, Richard; Barkin, Shari

    2011-03-01

    Designing cluster randomized trials in clinical studies often requires accurate estimates of intraclass correlation, which quantifies the strength of correlation between units, such as participants, within a cluster, such as a practice. Published ICC estimates, even when available, often suffer from the problem of wide confidence intervals. Using data from a national, randomized, controlled study concerning violence prevention for children--the Safety Check--we compare the ICC values derived from two approaches only baseline data and using both baseline and follow-up data. Using a variance component decomposition approach, the latter method allows flexibility in handling complex data sets. For example, it allows for shifts in the outcome variable over time and for an unbalanced cluster design. Furthermore, we evaluate the large-sample formula for ICC estimates and standard errors using the bootstrap method. Our findings suggest that ICC estimates range from 0.012 to 0.11 for providers within practice and range from 0.018 to 0.11 for families within provider. The estimates derived from the baseline-only and repeated-measurements approaches agree quite well except in cases in which variation over repeated measurements is large. The reductions in the widths of ICC confidence limits from using repeated measurement over baseline only are, respectively, 62% and 42% at the practice and provider levels. The contribution of this paper therefore includes two elements, which are a methodology for improving the accuracy of ICC, and the reporting of such quantities for pediatric and other researchers who are interested in designing clustered randomized trials similar to the current study.

  8. Development of Criteria and Identification of Particle Cluster Size Based on Measurements of Void Fraction in Gas-Solid Systems

    Energy Technology Data Exchange (ETDEWEB)

    David Roelant; Seckin Gokaltun

    2009-06-30

    A circulating fluidized bed (CFB) built at FIU was used to study particle motion in the riser in order to simulate flow regimes in a cold gasifier. High speed imaging was used in order to capture the dynamics of the particles flowing in the riser. The imaging method used here is called the shadow sizing technique which allowed the determination of particle areas and trajectories at various flow rates in the riser. The solid volume fraction and particle velocities calculated using the images acquired during the experiments can be related to granular temperature in order to detect formations of clusters in the riser section of the CFB. The shadow sizing technique was observed to be an effective method in detecting dynamics of particles in motion and formation of clusters when supported with high-speed imaging.

  9. Field-scale prediction of soil moisture patterns by means of a fuzzy c-means clustering algorithm, digital elevation data, and sparse TDR measurements

    Science.gov (United States)

    Schröter, Ingmar; Paasche, Hendik; Dietrich, Peter; Wollschläger, Ute

    2014-05-01

    Soil moisture is a key variable of the hydrological cycle. For example, it controls partitioning of rainfall into a runoff and an infiltration component and modulating physical, chemical and biological processes within the soil. For a better understanding of these processes, knowledge about the spatio-temporal distribution of soil moisture is indispensable. For the field to the small catchment scale with survey areas up to a few square kilometres, there are numerous new and innovative ground-based and remote sensing technologies available which have great potential to provide temporal information about soil moisture patterns. The aim of this work is to design an optimal soil moisture monitoring program for a low-mountain catchment in central Germany. In a first step, the fuzzy c-means clustering technique (Paasche et al., 2006) was used to identify structure-relevant patterns in a set of different terrain attributes derived from a DEM. Based on these patterns optimal measurement locations were identified to conduct in-situ soil moisture measurements. To consider different wetting and drying states in the catchment, several TDR measurement campaigns were conducted from April to October 2013. The TDR measurements have been integrated with the structure-relevant patterns obtained by the fuzzy cluster analysis to regionally predict soil moisture. In this study, we outline the conceptual framework of this integrative approach and present first results from field measurements. The results of the project are expected to improve the monitoring and understanding of small catchment-scale hydrological processes and to contribute to a better representation of soil moisture dynamics in physically-based, hydrological models operating at the field to the small catchment scale. Reference: Paasche, H., J. Tronicke, K. Holliger, A.G. Green, and H. Maurer (2006): Integration of diverse physical-property models: Subsurface zonation and petrophysical parameter estimation based on fuzzy

  10. Proposta de um sistema de avaliação do desempenho para arranjos produtivos locais Purpose of a performance measurement system for an industrial cluster

    Directory of Open Access Journals (Sweden)

    Edwin Vladimir Cardoza Galdámez

    2009-03-01

    managing collective efficiency and performance improvement of the companies of the cluster. The purpose of this article is to describe a model for the performance measurement and management of a cluster. In order to develop this study, a field research was carried out in two industrial clusters: Ibitinga, a textile industry cluster and Jau, a Lady's footwear cluster. The results show the applicability of performance measurement systems for the performance management of a cluster. It also helps to integrate the objectives of performance establishing actions, evaluating results promoting cooperation to improve the collective efficiency of a cluster.

  11. MASS CALIBRATION AND COSMOLOGICAL ANALYSIS OF THE SPT-SZ GALAXY CLUSTER SAMPLE USING VELOCITY DISPERSION σ {sub v} AND X-RAY Y {sub X} MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Bocquet, S.; Saro, A.; Mohr, J. J.; Bazin, G.; Chiu, I.; Desai, S. [Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, D-81679 München (Germany); Aird, K. A. [University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ashby, M. L. N.; Bayliss, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bautz, M. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Benson, B. A. [Fermi National Accelerator Laboratory, Batavia, IL 60510-0500 (United States); Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Cho, H. M. [NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States); Clocchiatti, A. [Departamento de Astronomia y Astrosifica, Pontificia Universidad Catolica (Chile); De Haan, T., E-mail: bocquet@usm.lmu.de [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); and others

    2015-02-01

    We present a velocity-dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg{sup 2} of the survey along with 63 velocity dispersion (σ {sub v}) and 16 X-ray Y {sub X} measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. Our method accounts for cluster selection, cosmological sensitivity, and uncertainties in the mass calibrators. The calibrations using σ {sub v} and Y {sub X} are consistent at the 0.6σ level, with the σ {sub v} calibration preferring ∼16% higher masses. We use the full SPT{sub CL} data set (SZ clusters+σ {sub v}+Y {sub X}) to measure σ{sub 8}(Ω{sub m}/0.27){sup 0.3} = 0.809 ± 0.036 within a flat ΛCDM model. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming that the sum of the neutrino masses is ∑m {sub ν} = 0.06 eV, we find the data sets to be consistent at the 1.0σ level for WMAP9 and 1.5σ for Planck+WP. Allowing for larger ∑m {sub ν} further reconciles the results. When we combine the SPT{sub CL} and Planck+WP data sets with information from baryon acoustic oscillations and Type Ia supernovae, the preferred cluster masses are 1.9σ higher than the Y {sub X} calibration and 0.8σ higher than the σ {sub v} calibration. Given the scale of these shifts (∼44% and ∼23% in mass, respectively), we execute a goodness-of-fit test; it reveals no tension, indicating that the best-fit model provides an adequate description of the data. Using the multi-probe data set, we measure Ω{sub m} = 0.299 ± 0.009 and σ{sub 8} = 0.829 ± 0.011. Within a νCDM model we find ∑m {sub ν} = 0.148 ± 0.081 eV. We present a consistency test of the cosmic growth rate using SPT clusters. Allowing both the growth index γ and the dark energy equation

  12. Surface decorated platinum carbonyl clusters

    Science.gov (United States)

    Ciabatti, Iacopo; Femoni, Cristina; Iapalucci, Maria Carmela; Longoni, Giuliano; Zacchini, Stefano; Zarra, Salvatore

    2012-06-01

    Four molecular Pt-carbonyl clusters decorated by Cd-Br fragments, i.e., [Pt13(CO)12{Cd5(μ-Br)5Br2(dmf)3}2]2- (1), [Pt19(CO)17{Cd5(μ-Br)5Br3(Me2CO)2}{Cd5(μ-Br)5Br(Me2CO)4}]2- (2), [H2Pt26(CO)20(CdBr)12]8- (3) and [H4Pt26(CO)20(CdBr)12(PtBr)x]6- (4) (x = 0-2), have been obtained from the reactions between [Pt3n(CO)6n]2- (n = 2-6) and CdBr2.H2O in dmf at 120 °C. The structures of these molecular clusters with diameters of 1.5-2 nm have been determined by X-ray crystallography. Both 1 and 2 are composed of icosahedral or bis-icosahedral Pt-CO cores decorated on the surface by Cd-Br motifs, whereas 3 and 4 display a cubic close packed Pt26Cd12 metal frame decorated by CO and Br ligands. An oversimplified and unifying approach to interpret the electron count of these surface decorated platinum carbonyl clusters is suggested, and extended to other low-valent organometallic clusters and Au-thiolate nanoclusters.Four molecular Pt-carbonyl clusters decorated by Cd-Br fragments, i.e., [Pt13(CO)12{Cd5(μ-Br)5Br2(dmf)3}2]2- (1), [Pt19(CO)17{Cd5(μ-Br)5Br3(Me2CO)2}{Cd5(μ-Br)5Br(Me2CO)4}]2- (2), [H2Pt26(CO)20(CdBr)12]8- (3) and [H4Pt26(CO)20(CdBr)12(PtBr)x]6- (4) (x = 0-2), have been obtained from the reactions between [Pt3n(CO)6n]2- (n = 2-6) and CdBr2.H2O in dmf at 120 °C. The structures of these molecular clusters with diameters of 1.5-2 nm have been determined by X-ray crystallography. Both 1 and 2 are composed of icosahedral or bis-icosahedral Pt-CO cores decorated on the surface by Cd-Br motifs, whereas 3 and 4 display a cubic close packed Pt26Cd12 metal frame decorated by CO and Br ligands. An oversimplified and unifying approach to interpret the electron count of these surface decorated platinum carbonyl clusters is suggested, and extended to other low-valent organometallic clusters and Au-thiolate nanoclusters. CCDC 867747 and 867748. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nr30400g

  13. Clustering of resting state networks.

    Directory of Open Access Journals (Sweden)

    Megan H Lee

    Full Text Available BACKGROUND: The goal of the study was to demonstrate a hierarchical structure of resting state activity in the healthy brain using a data-driven clustering algorithm. METHODOLOGY/PRINCIPAL FINDINGS: The fuzzy-c-means clustering algorithm was applied to resting state fMRI data in cortical and subcortical gray matter from two groups acquired separately, one of 17 healthy individuals and the second of 21 healthy individuals. Different numbers of clusters and different starting conditions were used. A cluster dispersion measure determined the optimal numbers of clusters. An inner product metric provided a measure of similarity between different clusters. The two cluster result found the task-negative and task-positive systems. The cluster dispersion measure was minimized with seven and eleven clusters. Each of the clusters in the seven and eleven cluster result was associated with either the task-negative or task-positive system. Applying the algorithm to find seven clusters recovered previously described resting state networks, including the default mode network, frontoparietal control network, ventral and dorsal attention networks, somatomotor, visual, and language networks. The language and ventral attention networks had significant subcortical involvement. This parcellation was consistently found in a large majority of algorithm runs under different conditions and was robust to different methods of initialization. CONCLUSIONS/SIGNIFICANCE: The clustering of resting state activity using different optimal numbers of clusters identified resting state networks comparable to previously obtained results. This work reinforces the observation that resting state networks are hierarchically organized.

  14. Measuring Galaxy Clustering and the Evolution of [CII] Mean Intensity with far-IR Line Intensity Mapping During 0.5 < z < 1.5

    CERN Document Server

    Uzgil, Bade D; Bradford, Charles M; Lidz, Adam

    2014-01-01

    Infrared fine-structure emission lines from trace metals are powerful diagnostics of the interstellar medium in galaxies. We explore the possibility of studying the redshifted far-IR fine-structure line emission using the three-dimensional (3-D) power spectra obtained with an imaging spectrometer. The intensity mapping approach measures the spatio-spectral fluctuations due to line emission from all galaxies, including those below the individual detection threshold. The technique provides 3-D measurements of galaxy clustering and moments of the galaxy luminosity function. Furthermore, the linear portion of the power spectrum can be used to measure the total line emission intensity including all sources through cosmic time with redshift information naturally encoded. Total line emission, when compared to the total star formation activity and/or other line intensities reveals evolution of the interstellar conditions of galaxies in aggregate. As a case study, we consider measurement of [CII] autocorrelation in th...

  15. DYNAMO-HST survey: clumps in nearby massive turbulent discs and the effects of clump clustering on kiloparsec scale measurements of clumps

    Science.gov (United States)

    Fisher, David B.; Glazebrook, Karl; Damjanov, Ivana; Abraham, Roberto G.; Obreschkow, Danail; Wisnioski, Emily; Bassett, Robert; Green, Andy; McGregor, Peter

    2017-01-01

    We present ˜100 pc resolution Hubble Space Telescope Hα images of 10 galaxies from the DYnamics of Newly-Assembled Massive Objects (DYNAMO) survey of low-z turbulent disc galaxies, and use these to undertake the first detailed systematic study of the effects of resolution and clump clustering on observations of clumps in turbulent discs. In the DYNAMO-HST sample, we measure clump diameters spanning the range dclump ˜ 100-800 pc, and individual clump star formation rates as high as ˜5 M⊙ yr-1. DYNAMO clumps have very high SFR surface densities, ΣSFR ˜ 1 - 15 M⊙ yr-1 kpc-2, ˜100 × higher than in H II regions of nearby spirals. Indeed, SFR surface density provides a simple dividing line between massive star-forming clumps and local star-forming regions, where massive star-forming clumps have ΣSFR > 0.5 M⊙ yr-1 kpc-2. When degraded to match the observations of galaxies in z ˜ 1-3 surveys, DYNAMO galaxies are similar in morphology and measured clump properties to clumpy galaxies observed in the high-z Universe. Emission peaks in the simulated high-redshift maps typically correspond to multiple clumps in full resolution images. This clustering of clumps systematically increases the apparent size and SFR of clumps in 1 kpc resolution maps, and decreases the measured SFR surface density of clumps by as much as a factor of 20×. From these results we can infer that clump clustering is likely to strongly affect the measured properties of clumps in high-z galaxies, which commonly have kiloparsec scale resolution.

  16. Why are rapidly rotating M dwarfs in the Pleiades so (infra)red? New period measurements confirm rotation-dependent color offsets from the cluster sequence

    CERN Document Server

    Covey, Kevin R; Law, Nicholas M; Liu, Jiyu; Ahmadi, Aida; Laher, Russ; Levitan, David; Sesar, Branimir; Surface, Jason

    2016-01-01

    Stellar rotation periods measured in open clusters have proved to be extremely useful for studying stars' angular momentum content and rotationally driven magnetic activity, which are both age- and mass-dependent processes. While period measurements have been obtained for hundreds of solar-mass members of the Pleiades, period measurements exist for only a few low-mass ($<$0.5 M$_{\\odot}$) members of this key laboratory for stellar evolution theory. To fill this gap, we report rotation periods for 132 low-mass Pleiades members (including nearly 100 with M $\\leq$ 0.45 M$_{\\odot}$), measured from photometric monitoring of the cluster conducted by the Palomar Transient Factory in late 2011 and early 2012. These periods extend the portrait of stellar rotation at 125 Myr to the lowest-mass stars and re-establish the Pleiades as a key benchmark for models of the transport and evolution of stellar angular momentum. Combining our new rotation periods with precise BVIJHK photometry reported by Stauffer et al. and Ka...

  17. A cluster-glass magnetic state in R5Pd2 (R = Ho, Tb) compounds evidenced by AC-susceptibility and neutron scattering measurements.

    Science.gov (United States)

    Gubkin, A F; Sherstobitova, E A; Terentyev, P B; Hoser, A; Baranov, N V

    2013-06-12

    AC- and DC-susceptibility, high-field magnetization and neutron diffraction measurements have been performed in order to study the magnetic state of R5Pd2 (R = Ho, Tb) compounds. The results show that both compounds undergo cluster-glass freezing upon cooling below Tf. According to the neutron diffraction a long-range magnetic order is absent down to 2 K and magnetic clusters with short-range incommensurate antiferromagnetic correlations exist not only below Tf but also in a wide temperature range above the freezing temperature (at least up to 2Tf). A complex cluster-glass magnetic state existing in Ho5Pd2 and Tb5Pd2 down to low temperatures results in rather complicated magnetization behavior in DC and AC magnetic fields. Such an unusual magnetic state in compounds with a high rare-earth concentration may be associated with the layered type of their crystal structure and with substantial atomic disorder, which results in frustrations in the magnetic subsystem.

  18. Theoretical modeling of spin crossover in metal-organic frameworks: [Fe(pz)2Pt(CN)4] as a case study.

    Science.gov (United States)

    Cirera, Jordi; Babin, Volodymyr; Paesani, Francesco

    2014-10-20

    Metal-organic frameworks (MOFs) with spin-crossover behavior are promising materials for applications in memory storage and sensing devices. A key parameter that characterizes these materials is the transition temperature T1/2, defined as the temperature with equal populations of low-spin and high-spin species. In this study, we describe the development, implementation, and application of a novel hybrid Monte Carlo/molecular dynamics method that builds upon the Ligand Field Molecular Mechanics approach and enables the modeling of spin-crossover properties in bulk materials. The new methodology is applied to the study of a spin-crossover MOF with molecular formula [Fe(pz)2Pt(CN)4] (pz = pyrazine). The total magnetic moment of the material is determined as a function of the temperature from direct calculations of the relative equilibrium populations of both low-spin and high-spin states of each Fe(II) center of the framework. The T1/2 value, calculated from the temperature dependence of the magnetization curve, is in good agreement with the available experimental data. A comparison between the spin-crossover behavior of the isolated secondary building block of the framework and the bulk material is presented, which reveals the origin of the different spin-crossover properties of the isolated molecular system and corresponding MOF structure.

  19. On TPC cluster reconstruction

    CERN Document Server

    Dydak, F; Nefedov, Y; Wotschack, J; Zhemchugov, A

    2004-01-01

    For a bias-free momentum measurement of TPC tracks, the correct determination of cluster positions is mandatory. We argue in particular that (i) the reconstruction of the entire longitudinal signal shape in view of longitudinal diffusion, electronic pulse shaping, and track inclination is important both for the polar angle reconstruction and for optimum r phi resolution; and that (ii) self-crosstalk of pad signals calls for special measures for the reconstruction of the z coordinate. The problem of 'shadow clusters' is resolved. Algorithms are presented for accepting clusters as 'good' clusters, and for the reconstruction of the r phi and z cluster coordinates, including provisions for 'bad' pads and pads next to sector boundaries, respectively.

  20. Meaningful Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Sanfilippo, Antonio P.; Calapristi, Augustin J.; Crow, Vernon L.; Hetzler, Elizabeth G.; Turner, Alan E.

    2004-05-26

    We present an approach to the disambiguation of cluster labels that capitalizes on the notion of semantic similarity to assign WordNet senses to cluster labels. The approach provides interesting insights on how document clustering can provide the basis for developing a novel approach to word sense disambiguation.

  1. Measurement of circulating transcripts and gene cluster analysis predicts and defines therapeutic efficacy of peptide receptor radionuclide therapy (PRRT) in neuroendocrine tumors

    Energy Technology Data Exchange (ETDEWEB)

    Bodei, L. [European Institute of Oncology, Division of Nuclear Medicine, Milan (Italy); LuGenIum Consortium, Milan, Rotterdam, Bad Berka, London, Italy, Netherlands, Germany (Country Unknown); Kidd, M. [Wren Laboratories, Branford, CT (United States); Modlin, I.M. [LuGenIum Consortium, Milan, Rotterdam, Bad Berka, London, Italy, Netherlands, Germany (Country Unknown); Yale School of Medicine, New Haven, CT (United States); Severi, S.; Nicolini, S.; Paganelli, G. [Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Nuclear Medicine and Radiometabolic Units, Meldola (Italy); Drozdov, I. [Bering Limited, London (United Kingdom); Kwekkeboom, D.J.; Krenning, E.P. [LuGenIum Consortium, Milan, Rotterdam, Bad Berka, London, Italy, Netherlands, Germany (Country Unknown); Erasmus Medical Center, Nuclear Medicine Department, Rotterdam (Netherlands); Baum, R.P. [LuGenIum Consortium, Milan, Rotterdam, Bad Berka, London, Italy, Netherlands, Germany (Country Unknown); Zentralklinik Bad Berka, Theranostics Center for Molecular Radiotherapy and Imaging, Bad Berka (Germany)

    2016-05-15

    Peptide receptor radionuclide therapy (PRRT) is an effective method for treating neuroendocrine tumors (NETs). It is limited, however, in the prediction of individual tumor response and the precise and early identification of changes in tumor size. Currently, response prediction is based on somatostatin receptor expression and efficacy by morphological imaging and/or chromogranin A (CgA) measurement. The aim of this study was to assess the accuracy of circulating NET transcripts as a measure of PRRT efficacy, and moreover to identify prognostic gene clusters in pretreatment blood that could be interpolated with relevant clinical features in order to define a biological index for the tumor and a predictive quotient for PRRT efficacy. NET patients (n = 54), M: F 37:17, median age 66, bronchial: n = 13, GEP-NET: n = 35, CUP: n = 6 were treated with {sup 177}Lu-based-PRRT (cumulative activity: 6.5-27.8 GBq, median 18.5). At baseline: 47/54 low-grade (G1/G2; bronchial typical/atypical), 31/49 {sup 18}FDG positive and 39/54 progressive. Disease status was assessed by RECIST1.1. Transcripts were measured by real-time quantitative reverse transcription PCR (qRT-PCR) and multianalyte algorithmic analysis (NETest); CgA by enzyme-linked immunosorbent assay (ELISA). Gene cluster (GC) derivations: regulatory network, protein:protein interactome analyses. Statistical analyses: chi-square, non-parametric measurements, multiple regression, receiver operating characteristic and Kaplan-Meier survival. The disease control rate was 72 %. Median PFS was not achieved (follow-up: 1-33 months, median: 16). Only grading was associated with response (p < 0.01). At baseline, 94 % of patients were NETest-positive, while CgA was elevated in 59 %. NETest accurately (89 %, χ{sup 2} = 27.4; p = 1.2 x 10{sup -7}) correlated with treatment response, while CgA was 24 % accurate. Gene cluster expression (growth-factor signalome and metabolome) had an AUC of 0.74 ± 0.08 (z-statistic = 2.92, p < 0

  2. Weighted Clustering

    DEFF Research Database (Denmark)

    Ackerman, Margareta; Ben-David, Shai; Branzei, Simina

    2012-01-01

    We investigate a natural generalization of the classical clustering problem, considering clustering tasks in which different instances may have different weights.We conduct the first extensive theoretical analysis on the influence of weighted data on standard clustering algorithms in both...... the partitional and hierarchical settings, characterizing the conditions under which algorithms react to weights. Extending a recent framework for clustering algorithm selection, we propose intuitive properties that would allow users to choose between clustering algorithms in the weighted setting and classify...... algorithms accordingly....

  3. Localized attack on clustering networks

    CERN Document Server

    Dong, Gaogao; Du, Ruijin; Shao, Shuai; Stanley, H Eugene; Shlomo, Havlin

    2016-01-01

    Clustering network is one of which complex network attracting plenty of scholars to discuss and study the structures and cascading process. We primarily analyzed the effect of clustering coefficient to other various of the single clustering network under localized attack. These network models including double clustering network and star-like NON with clustering and random regular (RR) NON of ER networks with clustering are made up of at least two networks among which exist interdependent relation among whose degree of dependence is measured by coupling strength. We show both analytically and numerically, how the coupling strength and clustering coefficient effect the percolation threshold, size of giant component, critical coupling point where the behavior of phase transition changes from second order to first order with the increase of coupling strength between the networks. Last, we study the two types of clustering network: one type is same with double clustering network in which each subnetwork satisfies ...

  4. Cluster Lenses

    CERN Document Server

    Kneib, Jean-Paul; 10.1007/s00159-011-0047-3

    2012-01-01

    Clusters of galaxies are the most recently assembled, massive, bound structures in the Universe. As predicted by General Relativity, given their masses, clusters strongly deform space-time in their vicinity. Clusters act as some of the most powerful gravitational lenses in the Universe. Light rays traversing through clusters from distant sources are hence deflected, and the resulting images of these distant objects therefore appear distorted and magnified. Lensing by clusters occurs in two regimes, each with unique observational signatures. The strong lensing regime is characterized by effects readily seen by eye, namely, the production of giant arcs, multiple-images, and arclets. The weak lensing regime is characterized by small deformations in the shapes of background galaxies only detectable statistically. Cluster lenses have been exploited successfully to address several important current questions in cosmology: (i) the study of the lens(es) - understanding cluster mass distributions and issues pertaining...

  5. Clustering Objects from Multiple Collections

    NARCIS (Netherlands)

    Hollink, V.; Someren, M. van; Boer, V. de

    2009-01-01

    Clustering methods cluster objects on the basis of a similarity measure between the objects. In clustering tasks where the objects come from more than one collection often part of the similarity results from features that are related to the collections rather than features that are relevant for the

  6. Clustering objects from multiple collections

    NARCIS (Netherlands)

    Hollink, V.; van Someren, M.; de Boer, V.

    2009-01-01

    Clustering methods cluster objects on the basis of a similarity measure between the objects. In clustering tasks where the objects come from more than one collection often part of the similarity results from features that are related to the collections rather than features that are relevant for the

  7. Coma cluster of galaxies

    Science.gov (United States)

    1999-01-01

    Atlas Image mosaic, covering 34' x 34' on the sky, of the Coma cluster, aka Abell 1656. This is a particularly rich cluster of individual galaxies (over 1000 members), most prominently the two giant ellipticals, NGC 4874 (right) and NGC 4889 (left). The remaining members are mostly smaller ellipticals, but spiral galaxies are also evident in the 2MASS image. The cluster is seen toward the constellation Coma Berenices, but is actually at a distance of about 100 Mpc (330 million light years, or a redshift of 0.023) from us. At this distance, the cluster is in what is known as the 'Hubble flow,' or the overall expansion of the Universe. As such, astronomers can measure the Hubble Constant, or the universal expansion rate, based on the distance to this cluster. Large, rich clusters, such as Coma, allow astronomers to measure the 'missing mass,' i.e., the matter in the cluster that we cannot see, since it gravitationally influences the motions of the member galaxies within the cluster. The near-infrared maps the overall luminous mass content of the member galaxies, since the light at these wavelengths is dominated by the more numerous older stellar populations. Galaxies, as seen by 2MASS, look fairly smooth and homogeneous, as can be seen from the Hubble 'tuning fork' diagram of near-infrared galaxy morphology. Image mosaic by S. Van Dyk (IPAC).

  8. The ACS Fornax Cluster Survey. V. Measurement and Recalibration of Surface Brightness Fluctuations and a Precise Value of the Fornax--Virgo Relative Distance

    CERN Document Server

    Blakeslee, John P; Mei, Simona; Cote, Patrick; Ferrarese, Laura; Infante, Leopoldo; Peng, Eric W; Tonry, John L; West, Michael J

    2009-01-01

    We present g-z color and z-band surface brightness fluctuations (SBF) measurements for 43 early-type galaxies in the Fornax cluster imaged with HST/ACS. These are combined with measurements for Virgo cluster galaxies to derive a revised, nonlinear calibration of the z-band SBF absolute magnitude as a function of g-z. In all, we tabulate recalibrated SBF distances for 134 galaxies in Virgo, Fornax, the Virgo W' group, and NGC4697 in the Virgo Southern Extension. The calibration procedure yields a precise relative distance modulus for Fornax with respect to Virgo of 0.42+/-0.03 mag, or a distance ratio 1.214 +/- 0.017. The resulting Fornax distance modulus is 31.51 +/-0.03 +/-0.15 mag, 20.0 +/-0.3 +/-1.4 Mpc, where the second set of error bars reflects systematic uncertainty from our assumed Virgo distance of 16.5 Mpc. The rms distance scatter for the early-type Fornax galaxies is 0.49^{+0.11}_{-0.15} Mpc, consistent with its compact appearance on the sky. This translates to a depth scatter smaller than the int...

  9. On the Cluster Physics of Sunyaev-Zel'dovich and X-ray Surveys III: Measurement Biases and Cosmological Evolution of Gas and Stellar Mass Fractions

    CERN Document Server

    Battaglia, N; Pfrommer, C; Sievers, J L

    2012-01-01

    Gas masses tightly correlate with the virial masses of galaxy clusters, allowing for a precise determination of cosmological parameters by means of large-scale X-ray surveys. However, according to recent Suzaku X-ray measurements, gas mass fractions, f_gas, appear to be considerably larger than the cosmic mean at the virial radius, R_200, questioning the accuracy of the cosmological parameter estimations. Here, we use a large suite of cosmological hydrodynamical simulations to study measurement biases of f_gas. We employ different variants of simulated physics, including radiative gas physics, star formation, and thermal feedback by active galactic nuclei. Computing the mass profiles in 48 angular cones, whose footprints partition the sphere, we find anisotropic gas and total mass distributions that imply an angular variance of f_gas at the level of 30%. This anisotropic distribution originates from the recent formation epoch of clusters and from the strong internal baryon-to-dark-matter density bias. In the ...

  10. The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: double-probe measurements from BOSS galaxy clustering \\& Planck data -- towards an analysis without informative priors

    CERN Document Server

    Pellejero-Ibanez, Marcos; Rubiño-Martín, J A; Cuesta, Antonio J; Wang, Yuting; Zhao, Gong-bo; Ross, Ashley J; Rodríguez-Torres, Sergio; Prada, Francisco; Slosar, Anže; Vazquez, Jose A; Alam, Shadab; Beutler, Florian; Eisenstein, Daniel J; Gil-Marín, Héctor; Grieb, Jan Niklas; Ho, Shirley; Kitaura, Francisco-Shu; Percival, Will J; Rossi, Graziano; Salazar-Albornoz, Salvador; Samushia, Lado; Sánchez, Ariel G; Satpathy, Siddharth; Seo, Hee-Jong; Tinker, Jeremy L; Tojeiro, Rita; Vargas-Magaña, Mariana; Brownstein, Joel R; Nichol, Robert C; Olmstead, Matthew D

    2016-01-01

    We develop a new methodology called double-probe analysis with the aim of minimizing informative priors in the estimation of cosmological parameters. We extract the dark-energy-model-independent cosmological constraints from the joint data sets of Baryon Oscillation Spectroscopic Survey (BOSS) galaxy sample and Planck cosmic microwave background (CMB) measurement. We measure the mean values and covariance matrix of $\\{R$, $l_a$, $\\Omega_b h^2$, $n_s$, $log(A_s)$, $\\Omega_k$, $H(z)$, $D_A(z)$, $f(z)\\sigma_8(z)\\}$, which give an efficient summary of Planck data and 2-point statistics from BOSS galaxy sample, where $R=\\sqrt{\\Omega_m H_0^2}\\,r(z_*)$, and $l_a=\\pi r(z_*)/r_s(z_*)$, $z_*$ is the redshift at the last scattering surface, and $r(z_*)$ and $r_s(z_*)$ denote our comoving distance to $z_*$ and sound horizon at $z_*$ respectively. The advantage of this method is that we do not need to put informative priors on the cosmological parameters that galaxy clustering is not able to constrain well, i.e. $\\Omega_b...

  11. Neutrosophic Hierarchical Clustering Algoritms

    Directory of Open Access Journals (Sweden)

    Rıdvan Şahin

    2014-03-01

    Full Text Available Interval neutrosophic set (INS is a generalization of interval valued intuitionistic fuzzy set (IVIFS, whose the membership and non-membership values of elements consist of fuzzy range, while single valued neutrosophic set (SVNS is regarded as extension of intuitionistic fuzzy set (IFS. In this paper, we extend the hierarchical clustering techniques proposed for IFSs and IVIFSs to SVNSs and INSs respectively. Based on the traditional hierarchical clustering procedure, the single valued neutrosophic aggregation operator, and the basic distance measures between SVNSs, we define a single valued neutrosophic hierarchical clustering algorithm for clustering SVNSs. Then we extend the algorithm to classify an interval neutrosophic data. Finally, we present some numerical examples in order to show the effectiveness and availability of the developed clustering algorithms.

  12. Photoionization of rare gas clusters

    Science.gov (United States)

    Zhang, Huaizhen

    This thesis concentrates on the study of photoionization of van der Waals clusters with different cluster sizes. The goal of the experimental investigation is to understand the electronic structure of van der Waals clusters and the electronic dynamics. These studies are fundamental to understand the interaction between UV-X rays and clusters. The experiments were performed at the Advanced Light Source at Lawrence Berkeley National Laboratory. The experimental method employs angle-resolved time-of-flight photoelectron spectrometry, one of the most powerful methods for probing the electronic structure of atoms, molecules, clusters and solids. The van der Waals cluster photoionization studies are focused on probing the evolution of the photoelectron angular distribution parameter as a function of photon energy and cluster size. The angular distribution has been known to be a sensitive probe of the electronic structure in atoms and molecules. However, it has not been used in the case of van der Waals clusters. We carried out outer-valence levels, inner-valence levels and core-levels cluster photoionization experiments. Specifically, this work reports on the first quantitative measurements of the angular distribution parameters of rare gas clusters as a function of average cluster sizes. Our findings for xenon clusters is that the overall photon-energy-dependent behavior of the photoelectrons from the clusters is very similar to that of the corresponding free atoms. However, distinct differences in the angular distribution point at cluster-size-dependent effects were found. For krypton clusters, in the photon energy range where atomic photoelectrons have a high angular anisotropy, our measurements show considerably more isotropic angular distributions for the cluster photoelectrons, especially right above the 3d and 4p thresholds. For the valence electrons, a surprising difference between the two spin-orbit components was found. For argon clusters, we found that the

  13. Cluster Chemistry

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ Cansisting of eight scientists from the State Key Laboratory of Physical Chemistry of Solid Surfaces and Xiamen University, this creative research group is devoted to the research of cluster chemistry and creation of nanomaterials.After three-year hard work, the group scored a series of encouraging progresses in synthesis of clusters with special structures, including novel fullerenes, fullerene-like metal cluster compounds as well as other related nanomaterials, and their properties study.

  14. Measuring Galaxy Clustering and the Evolution of [C II] Mean Intensity with Far-IR Line Intensity Mapping during 0.5 < z < 1.5

    Science.gov (United States)

    Uzgil, Bade; Aguirre, James E.; Bradford, Charles; Lidz, Adam

    2016-01-01

    Infrared fine-structure emission lines from trace metals are powerful diagnostics of the interstellar medium in galaxies. We explore the possibility of studying the redshifted far-IR fine-structure line emission using the three-dimensional (3D) power spectra obtained with an imaging spectrometer. The intensity mapping approach measures the spatio-spectral fluctuations due to line emission from all galaxies, including those below the individual detection threshold. The technique provides 3D measurements of galaxy clustering and moments of the galaxy luminosity function. Furthermore, the linear portion of the power spectrum can be used to measure the total line emission intensity including all sources through cosmic time with redshift information naturally encoded. As a case study, we consider measurement of [C II] autocorrelation in the 0.5 < z < 1.5 epoch, where interloper lines are minimized, using far-IR/submillimeter balloon-borne and future space-borne instruments with moderate and high sensitivity, respectively. In this context, we compare the intensity mapping approach to blind galaxy surveys based on individual detections. We find that intensity mapping is nearly always the best way to obtain the total line emission because blind, wide-field galaxy surveys lack sufficient depth and deep pencil beams do not observe enough galaxies in the requisite luminosity and redshift bins. Also, intensity mapping is often the most efficient way to measure the power spectrum shape, depending on the details of the luminosity function and the telescope aperture.

  15. A Comparison and Joint Analysis of Sunyaev-Zel’dovich Effect Measurements from Planck and Bolocam for a Set of 47 Massive Galaxy Clusters

    Science.gov (United States)

    Sayers, Jack; Golwala, Sunil R.; Mantz, Adam B.; Merten, Julian; Molnar, Sandor M.; Naka, Michael; Pailet, Gregory; Pierpaoli, Elena; Siegel, Seth R.; Wolman, Ben

    2016-11-01

    We measure the Sunyaev-Zel’dovich (SZ) signal toward a set of 47 clusters with a median mass of 9.5 × 1014 M ⊙ and a median redshift of 0.40 using data from Planck and the ground-based Bolocam receiver. When Planck XMM-like masses are used to set the scale radius {θ }{{s}}, we find consistency between the integrated SZ signal, {Y}5{{R}500}, derived from Bolocam and Planck based on generalized Navarro, Frenk, and White model fits using A10 shape parameters, with an average ratio of 1.069 ± 0.030 (allowing for the ≃5% Bolocam flux calibration uncertainty). We also perform a joint fit to the Bolocam and Planck data using a modified A10 model with the outer logarithmic slope β allowed to vary, finding β = 6.13 ± 0.16 ± 0.76 (measurement error followed by intrinsic scatter). In addition, we find that the value of β scales with mass and redshift according to β \\propto {M}0.077+/- 0.026× {(1+z)}-0.06+/- 0.09. This mass scaling is in good agreement with recent simulations. We do not observe the strong trend of β with redshift seen in simulations, though we conclude that this is most likely due to our sample selection. Finally, we use Bolocam measurements of Y 500 to test the accuracy of the Planck completeness estimate. We find consistency, with the actual number of Planck detections falling approximately 1σ below the expectation from Bolocam. We translate this small difference into a constraint on the effective mass bias for the Planck cluster cosmology results, with (1-b)=0.93+/- 0.06.

  16. The Clustering of Galaxies in the SDSS-III DR10 Baryon Oscillation Spectroscopic Survey: No Detectable Colour Dependence of Distance Scale or Growth Rate Measurements

    CERN Document Server

    Ross, Ashley J; Burden, Angela; Percival, Will J; Tojeiro, Rita; Manera, Marc; Beutler, Florian; Brinkmann, J; Brownstein, Joel R; Carnero, Aurelio; da Costa, Luiz A N; Eisenstein, Daniel J; Guo, Hong; Ho, Shirley; Maia, Marcio A G; Montesano, Francesco; Muna, Demitri; Nichol, Robert C; Nuza, Sebastian E; Sanchez, Ariel G; Schneider, Donald P; Skibba, Ramin A; Sobreira, Flavia; Streblyanska, Alina; Swanson, Molly E C; Thomas, Daniel; Tinker, Jeremy L; Wake, David A; Zehavi, Idit; Zhao, Gong-bo

    2013-01-01

    We study the clustering of galaxies, as a function of their colour, from Data Release Ten (DR10) of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). We select 122,967 galaxies with 0.43 < z < 0.7 into a "Blue" sample and 131,969 into a "Red" sample based on k+e corrected (to z=0.55) r-i colours and i band magnitudes. The samples are chosen to each contain more than 100,000 galaxies, have similar redshift distributions, and maximize the difference in clustering amplitude. The Red sample has a 40% larger bias than the Blue (b_Red/b_Blue = 1.39+-0.04), implying the Red galaxies occupy dark matter halos with an average mass that is 0.5 log Mo greater. Spherically averaged measurements of the correlation function, \\xi 0, and the power spectrum are used to locate the position of the baryon acoustic oscillation (BAO) feature of both samples. Using \\xi 0, we obtain distance scales, relative to our reference LCDM cosmology, of 1.010+-0.027 for the Red sample and 1.005+-0.031 for the Blue. After apply...

  17. Clustered regression with unknown clusters

    CERN Document Server

    Barman, Kishor

    2011-01-01

    We consider a collection of prediction experiments, which are clustered in the sense that groups of experiments ex- hibit similar relationship between the predictor and response variables. The experiment clusters as well as the regres- sion relationships are unknown. The regression relation- ships define the experiment clusters, and in general, the predictor and response variables may not exhibit any clus- tering. We call this prediction problem clustered regres- sion with unknown clusters (CRUC) and in this paper we focus on linear regression. We study and compare several methods for CRUC, demonstrate their applicability to the Yahoo Learning-to-rank Challenge (YLRC) dataset, and in- vestigate an associated mathematical model. CRUC is at the crossroads of many prior works and we study several prediction algorithms with diverse origins: an adaptation of the expectation-maximization algorithm, an approach in- spired by K-means clustering, the singular value threshold- ing approach to matrix rank minimization u...

  18. The Clustering of Galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Measuring H(z) and D_A(z) at z = 0.57 with Clustering Wedges

    CERN Document Server

    Kazin, Eyal A; Cuesta, Antonio J; Beutler, Florian; Chuang, Chia-Hsun; Eisenstein, Daniel J; Manera, Marc; Padmanabhan, Nikhil; Percival, Will J; Prada, Francisco; Ross, Ashley J; Seo, Hee-Jong; Tinker, Jeremy; Tojeiro, Rita; Xu, Xiaoying; Brinkmann, J; Joel, Brownstein; Nichol, Robert C; Schlegel, David J; Schneider, Donald P; Thomas, Daniel

    2013-01-01

    We analyze the 2D correlation function of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) CMASS sample of massive galaxies of the ninth data release to measure cosmic expansion H and the angular diameter distance D_A at a mean redshift of = 0.57. We apply, for the first time, a new correlation function technique called clustering wedges. Using a physically motivated model, the anisotropic baryonic acoustic feature in the galaxy sample is detected at a significance level of 4.7 sigma compared to a featureless model. The baryonic acoustic feature is used to obtain model independent constraints cz/H/r_s = 12.28 +- 0.82 (6.7 per-cent accuracy) and D_A/r_s = 9.05 +- 0.27 (3.0 per-cent) with a correlation coefficient of -0.5, where r_s is the sound horizon scale at the end of the baryonic drag era. We conduct thorough tests on the data and 600 simulated realizations, finding robustness of the results regardless of the details of the analysis method. Combining with r_s constraints from the Cosmic Microw...

  19. Subspace clustering through attribute clustering

    Institute of Scientific and Technical Information of China (English)

    Kun NIU; Shubo ZHANG; Junliang CHEN

    2008-01-01

    Many recently proposed subspace clustering methods suffer from two severe problems. First, the algorithms typically scale exponentially with the data dimensionality or the subspace dimensionality of clusters. Second, the clustering results are often sensitive to input parameters. In this paper, a fast algorithm of subspace clustering using attribute clustering is proposed to over-come these limitations. This algorithm first filters out redundant attributes by computing the Gini coefficient. To evaluate the correlation of every two non-redundant attributes, the relation matrix of non-redundant attributes is constructed based on the relation function of two dimensional united Gini coefficients. After applying an overlapping clustering algorithm on the relation matrix, the candidate of all interesting subspaces is achieved. Finally, all subspace clusters can be derived by clustering on interesting subspaces. Experiments on both synthesis and real datasets show that the new algorithm not only achieves a significant gain of runtime and quality to find subspace clusters, but also is insensitive to input parameters.

  20. Measuring patient safety culture: an assessment of the clustering of responses at unit level and hospital level

    NARCIS (Netherlands)

    Smits, M.; Wagner, C.; Spreeuwenberg, P.; Wal, van der G.

    2009-01-01

    OBJECTIVES: To test the claim that the Hospital Survey on Patient Safety Culture (HSOPS) measures patient safety culture instead of mere individual attitudes and to determine the most appropriate level (individual, unit or hospital level) for interventions aimed at improving the culture of patient s

  1. Measuring patient safety culture : an assessment of the clustering of responses at unit level and hospital level

    NARCIS (Netherlands)

    Smits, M.; Wagner, C.; Spreeuwenberg, P.; Wal, G. van der; Groenewegen, P.P.

    2009-01-01

    Objectives: To test the claim that the Hospital Survey on Patient Safety Culture (HSOPS) measures patient safety culture instead of mere individual attitudes and to determine the most appropriate level (individual, unit or hospital level) for interventions aimed at improving the culture of patient s

  2. Diffuse optical intracluster light as a measure of stellar tidal stripping: The cluster CL0024+17 at z ∼ 0.4 observed at the large binocular telescope

    Energy Technology Data Exchange (ETDEWEB)

    Giallongo, E.; Menci, N.; Grazian, A.; Gallozzi, S.; Castellano, M.; Fiore, F.; Fontana, A.; Pentericci, L.; Boutsia, K.; Paris, D.; Speziali, R.; Testa, V. [INAF—Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monteporzio (Italy)

    2014-01-20

    We have evaluated the diffuse intracluster light (ICL) in the central core of the galaxy cluster CL0024+17 at z ∼ 0.4 observed with the prime focus camera (Large Binocular Camera) at the Large Binocular Telescope. The measure required an accurate removal of the galaxies' light within ∼200 kpc from the center. The residual background intensity has then been integrated in circular apertures to derive the average ICL intensity profile. The latter shows an approximate exponential decline as expected from theoretical cold dark matter models where the ICL is due to the integrated contribution of light from stars that are tidally stripped from the halo of their host galaxies due to encounters with other galaxies in the cluster cold dark matter (CDM) potential. The radial profile of the ICL over the galaxies intensity ratio (ICL fraction) is increasing with decreasing radius, but near the cluster center it starts to bend and then decreases where the overlap of the halos of the brightest cluster galaxies becomes dominant. Theoretical expectations in a simplified CDM scenario show that the ICL fraction profile can be estimated from the stripped over galaxy stellar mass ratio in the cluster. It is possible to show that the latter quantity is almost independent of the properties of the individual host galaxies but mainly depends on the average cluster properties. The predicted ICL fraction profile is thus very sensitive to the assumed CDM profile, total mass, and concentration parameter of the cluster. Adopting values very similar to those derived from the most recent lensing analysis in CL0024+17, we find a good agreement with the observed ICL fraction profile. The galaxy counts in the cluster core have then been compared with that derived from composite cluster samples in larger volumes, up to the clusters virial radius. The galaxy counts in the CL0024+17 core appear flatter and the amount of bending with respect to the average cluster galaxy counts imply a loss of

  3. Solid-state structures of (R sub 3 P) sub 2 PtX sub 2 complexes as determined by a combination of sup 13 C( sup 1 H) and sup 31 P( sup 1 H) NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rahn, J.A.; Nelson, J.H. (Univ. of Nevada, Reno (USA)); Baltusis, L. (Varian Instrument Div., Palo Alto, CA (USA))

    1990-02-21

    Cross-polarization, combined with magic-angle spinning, has been employed to obtain high-resolution solid-state {sup 13}C and {sup 31}P NMR spectra of a series of 31 (R{sub 3}P){sub 2}PtX{sub 2} complexes. These data together with spectra obtained in solution were used to compare the solid-state structures with those in solution. It was found that most of these complexes, which have regular square-planar structures in solution, are distorted in the solid state. The extent of the solid-state distortion is a function of the bulk of the coordinated ligands and increases as the ligand size increases. The solid-state distortions appear to result from intramolecular steric effects for cis-(R{sub 3}P){sub 2}PtX{sub 2} and probably from intermolecular crystal packing forces for trans-(R{sub 3}P){sub 2}PtX{sub 2}. 37 refs., 6 figs., 3 tabs.

  4. Cluster editing

    DEFF Research Database (Denmark)

    Böcker, S.; Baumbach, Jan

    2013-01-01

    . The problem has been the inspiration for numerous algorithms in bioinformatics, aiming at clustering entities such as genes, proteins, phenotypes, or patients. In this paper, we review exact and heuristic methods that have been proposed for the Cluster Editing problem, and also applications......The Cluster Editing problem asks to transform a graph into a disjoint union of cliques using a minimum number of edge modifications. Although the problem has been proven NP-complete several times, it has nevertheless attracted much research both from the theoretical and the applied side...

  5. Cluster analysis

    CERN Document Server

    Everitt, Brian S; Leese, Morven; Stahl, Daniel

    2011-01-01

    Cluster analysis comprises a range of methods for classifying multivariate data into subgroups. By organizing multivariate data into such subgroups, clustering can help reveal the characteristics of any structure or patterns present. These techniques have proven useful in a wide range of areas such as medicine, psychology, market research and bioinformatics.This fifth edition of the highly successful Cluster Analysis includes coverage of the latest developments in the field and a new chapter dealing with finite mixture models for structured data.Real life examples are used throughout to demons

  6. Weighted Clustering

    CERN Document Server

    Ackerman, Margareta; Branzei, Simina; Loker, David

    2011-01-01

    In this paper we investigate clustering in the weighted setting, in which every data point is assigned a real valued weight. We conduct a theoretical analysis on the influence of weighted data on standard clustering algorithms in each of the partitional and hierarchical settings, characterising the precise conditions under which such algorithms react to weights, and classifying clustering methods into three broad categories: weight-responsive, weight-considering, and weight-robust. Our analysis raises several interesting questions and can be directly mapped to the classical unweighted setting.

  7. Total Plasma Density Determination In The Earth's Space Environment From The Active and Passive Measurements of The Cluster/whisper Experiment

    Science.gov (United States)

    Trotignon, J. G.; Canu, P.; Dandouras, I.; Darrouzet, F.; Décréau, P. M. E.; Hitier, R.; Le Guirriec, E.; Lemaire, J.; Rauch, J. L.; Rème, H.

    The WHISPER experiment that is onboard the four CLUSTER satellites is a classical relaxation sounder. It therefore sends short pulses (0.5 ms or 1 ms) at given frequen- cies in the surrounding medium. The answer from the probed plasma is subsequently received and analysed onboard. A fast Fourier transform is applied to the received sig- nal and the calculated frequency spectrum transmitted to the ground. The frequency at which the pulse is transmitted varies step by step, 1 kHz or 2 kHz in width, from 2 kHz to 80 kHz, i.e., in a frequency range that includes the plasma frequency expected in the Earth's space environment from the plasmapause to the solar wind. In active (sounding) mode, plasma resonances are thus triggered by WHISPER at characteris- tic frequencies from which the total plasma density and, possibly, the magnetic field modulus are derived. Whenever the transmitter is switched off, the WHISPER behaves like a simple wave receiver. The electric field component of natural waves are then recorded, its frequency spectrum determined onboard and fed into the telemetry. The objective of the presentation is to show how the total plasma density is derived from the active and passive measurements of the WHISPER. Different types of plasma res- onances are actually excited depending on the nature of the encountered plasma. Once the resonances are identified, their frequency locations are used for plasma density determinations. The characteristic frequencies of the plasma being known from the active measurements, natural waves (passive measurements) may be identified more easily. Their characteristics, such as cut-off or maximum-intensity frequencies, may be used for plasma density measurement purposes, which allows the gaps between active sequences to be filled in. Some examples in the solar wind, the magnetosheath, and the plasmapause are shown. A particular attention is paid to the latter. The hot to cold electron density ratio may indeed be estimated, and

  8. A metric measure for weight matrices of variable lengths—with applications to clustering and classification of hidden Markov models

    Science.gov (United States)

    Yu, Yi-Kuo

    2007-02-01

    We construct a metric measure among weight matrices that are commonly used in non-interacting statistical physics systems, computational biology problems, as well as in general applications such as hidden Markov models. The metric distance between two weight matrices is obtained via aligning the matrices and thus can be evaluated by dynamic programming. Capable of allowing reverse complements in distance evaluation, this metric accommodates both gapless and gapped alignments between two weight matrices. The distance statistics among random motifs is also studied. We find that the average square distance and its standard error grow with different powers of motif length, and the normalized square distance follows a Gaussian distribution for large motif lengths.

  9. Measuring galaxy clustering and the evolution of [C II] mean intensity with far-IR line intensity mapping during 0.5 < z < 1.5

    Energy Technology Data Exchange (ETDEWEB)

    Uzgil, B. D.; Aguirre, J. E.; Lidz, A. [University of Pennsylvania, Philadelphia, PA 19104 (United States); Bradford, C. M., E-mail: badeu@sas.upenn.edu [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States)

    2014-10-01

    Infrared fine-structure emission lines from trace metals are powerful diagnostics of the interstellar medium in galaxies. We explore the possibility of studying the redshifted far-IR fine-structure line emission using the three-dimensional (3D) power spectra obtained with an imaging spectrometer. The intensity mapping approach measures the spatio-spectral fluctuations due to line emission from all galaxies, including those below the individual detection threshold. The technique provides 3D measurements of galaxy clustering and moments of the galaxy luminosity function. Furthermore, the linear portion of the power spectrum can be used to measure the total line emission intensity including all sources through cosmic time with redshift information naturally encoded. Total line emission, when compared to the total star formation activity and/or other line intensities, reveals evolution of the interstellar conditions of galaxies in aggregate. As a case study, we consider measurement of [C II] autocorrelation in the 0.5 < z < 1.5 epoch, where interloper lines are minimized, using far-IR/submillimeter balloon-borne and future space-borne instruments with moderate and high sensitivity, respectively. In this context, we compare the intensity mapping approach to blind galaxy surveys based on individual detections. We find that intensity mapping is nearly always the best way to obtain the total line emission because blind, wide-field galaxy surveys lack sufficient depth and deep pencil beams do not observe enough galaxies in the requisite luminosity and redshift bins. Also, intensity mapping is often the most efficient way to measure the power spectrum shape, depending on the details of the luminosity function and the telescope aperture.

  10. Cluster Radioactivity in 127I

    Directory of Open Access Journals (Sweden)

    K. Manimaran

    2013-08-01

    Full Text Available Using the preformation cluster model of Gupta and collaborators we have studied all the possible cluster decay modes of 127 I. The calculated half-lives are compared with recently measured lower limits of cluster decay half-lives (for the clusters like 24Ne, 28Mg, 30Mg, 32Si, 34Si, 48Ca and 49Sc of 127I. Our calculated half-life values lies well above the experimentally measured lower limits and the trend of the values also matches with experimental ones.

  11. Optical radii of galaxy clusters

    CERN Document Server

    Girardi, M; Giuricin, G; Mardirossian, F; Mezzetti, M; Girardi, M; Biviano, A; Giuricin, G; Mardirossian, F; Mezzetti, M

    1994-01-01

    We analyze the density profiles and virial radii for a sample of 90 nearby clusters, using galaxies with available redshifts and positions. Each cluster has at least 20 redshifts measured within an Abell radius, and all the results come from galaxy sets of at least 20 members. Most of the density profiles of our clusters are well fitted by hydrostatic-isothermal-like profiles. The slopes we find for many cluster density profiles are consistent with the hypothesis that the galaxies are in equilibrium with the binding cluster potential. The virial radii correlate with the core radii at a very high significance level. The observed relationship between the two size estimates is in agreement with the theoretical one computed by using the median values of the density profile parameters fitted on our clusters. After correcting for incompleteness in our cluster sample, we provide the universal distributions functions of core and virial radii (obtained within half an Abell radius).

  12. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: RSD measurement from the LOS-dependent power spectrum of DR12 BOSS galaxies

    CERN Document Server

    Gil-Marín, Héctor; Brownstein, Joel R; Chuang, Chia-Hsun; Grieb, Jan Niklas; Ho, Shirley; Kitaura, Francisco-Shu; Maraston, Claudia; Prada, Francisco; Rodríguez-Torres, Sergio; Ross, Ashley J; Samushia, Lado; Schlegel, David J; Thomas, Daniel; Tinker, Jeremy L; Zhao, Gong-Bo

    2015-01-01

    We measure and analyse the clustering of the Baryon Oscillation Spectroscopic Survey (BOSS) relative to the line-of-sight (LOS), for LOWZ and CMASS galaxy samples drawn from the final Data Release 12 (DR12). The LOWZ sample contains 361\\,762 galaxies with an effective redshift of $z_{\\rm lowz}=0.32$, and the CMASS sample 777\\,202 galaxies with an effective redshift of $z_{\\rm cmass}=0.57$. From the power spectrum monopole and quadrupole moments around the LOS, we measure the growth of structure parameter $f$ times the amplitude of dark matter density fluctuations $\\sigma_8$ by modeling the Redshift-Space Distortion signal. When the geometrical Alcock-Paczynski effect is also constrained from the same data, we find joint constraints on $f\\sigma_8$, the product of the Hubble constant and the comoving sound horizon at the baryon drag epoch $H(z)r_s(z_d)$, and the angular distance parameter divided by the sound horizon $D_A(z)/r_s(z_d)$. We find $f(z_{\\rm lowz})\\sigma_8(z_{\\rm lowz})=0.394\\pm0.062$, $D_A(z_{\\rm l...

  13. Monte carlo simulation of base and nucleotide excision repair of clustered DNA damage sites. II. Comparisons of model predictions to measured data.

    Science.gov (United States)

    Semenenko, V A; Stewart, R D

    2005-08-01

    Clustered damage sites other than double-strand breaks (DSBs) have the potential to contribute to deleterious effects of ionizing radiation, such as cell killing and mutagenesis. In the companion article (Semenenko et al., Radiat. Res. 164, 180-193, 2005), a general Monte Carlo framework to simulate key steps in the base and nucleotide excision repair of DNA damage other than DSBs is proposed. In this article, model predictions are compared to measured data for selected low-and high-LET radiations. The Monte Carlo model reproduces experimental observations for the formation of enzymatic DSBs in Escherichia coli and cells of two Chinese hamster cell lines (V79 and xrs5). Comparisons of model predictions with experimental values for low-LET radiation suggest that an inhibition of DNA backbone incision at the sites of base damage by opposing strand breaks is active over longer distances between the damaged base and the strand break in hamster cells (8 bp) compared to E. coli (3 bp). Model estimates for the induction of point mutations in the human hypoxanthine guanine phosphoribosyl transferase (HPRT) gene by ionizing radiation are of the same order of magnitude as the measured mutation frequencies. Trends in the mutation frequency for low- and high-LET radiation are predicted correctly by the model. The agreement between selected experimental data sets and simulation results provides some confidence in postulated mechanisms for excision repair of DNA damage other than DSBs and suggests that the proposed Monte Carlo scheme is useful for predicting repair outcomes.

  14. A Comparison and Joint Analysis of Sunyaev-Zel'dovich Effect Measurements from Planck and Bolocam for a set of 47 Massive Galaxy Clusters

    CERN Document Server

    Sayers, Jack; Mantz, Adam B; Molnar, Sandor M; Naka, Michael; Pailet, Gregory; Pierpaoli, Elena; Siegel, Seth R; Wolman, Ben

    2016-01-01

    We measure the SZ signal toward a set of 47 clusters with a median mass of $9.5 \\times 10^{14}$ M$_{\\odot}$ and a median redshift of 0.40 using data from Planck and the ground-based Bolocam receiver. When Planck XMM-like masses are used to set the scale radius $\\theta_{\\textrm{s}}$, we find consistency between the integrated SZ signal, $Y_{\\textrm{5R500}}$, derived from Bolocam and Planck based on gNFW model fits using A10 shape parameters, with an average ratio of $1.069 \\pm 0.030$ (allowing for the $\\simeq 5$% Bolocam flux calibration uncertainty). We also perform a joint fit to the Bolocam and Planck data using a modified A10 model with the outer logarithmic slope $\\beta$ allowed to vary, finding $\\beta = 6.13 \\pm 0.16 \\pm 0.76$ (measurement error followed by intrinsic scatter). In addition, we find that the value of $\\beta$ scales with mass and redshift according to $\\beta \\propto M^{0.077 \\pm 0.026} \\times (1+z)^{-0.06 \\pm 0.09}$. This mass scaling is in good agreement with recent simulations. We do not ...

  15. Planck intermediate results: II. Comparison of sunyaev-zeldovich measurements from planck and from the arcminute microkelvin imager for 11 galaxy clusters

    DEFF Research Database (Denmark)

    Bucher, M.; Delabrouille, J.; Ganga, K.;

    2013-01-01

    , there is a tendency for AMI to find the Sunyaev-Zeldovich signal to be smaller in angular size and fainter than Planck. Significant discrepancies exist for the three remaining clusters in the sample, namely A1413, A1914, and the newly-discovered Planck cluster PLCKESZ G139.59+24.18. The robustness of the analysis...

  16. Fuzzy Clustering

    DEFF Research Database (Denmark)

    Berks, G.; Keyserlingk, Diedrich Graf von; Jantzen, Jan;

    2000-01-01

    and clustering are the basic concerns in medicine. Classification depends on definitions of the classes and their required degree of participant of the elements in the cases' symptoms. In medicine imprecise conditions are the rule and therefore fuzzy methods are much more suitable than crisp ones. Fuzzy c....... A symptom may belong to more than one class. For instance to the class of very severe disease and to the class of failure of awareness of the own disturbance. The description of language failures by c-mean classification of analyzed factors correspond in many but not in all cases to the traditional......-mean clustering is an easy and well improved tool, which has been applied in many medical fields. We used c-mean fuzzy clustering after feature extraction from an aphasia database. Factor analysis was applied on a correlation matrix of 26 symptoms of language disorders and led to five factors. The factors...

  17. COMPARISON OF PURITY AND ENTROPY OF K-MEANS CLUSTERING AND FUZZY C MEANS CLUSTERING

    Directory of Open Access Journals (Sweden)

    Satya Chaitanya Sripada

    2011-06-01

    Full Text Available Clustering is one the main area in data mining literature. There are various algorithms for clustering. The evaluation of the performance isdone by validation measures. The external validation measures are used to measure the extent to which cluster labels affirm with theexternally given class labels. The aim of this paper is to compare the for K-means and Fuzzy C means clustering using the Purity andEntropy. The data used for evaluating the external measures is medical data.

  18. Kelvin-Helmholtz instabilities at the sloshing cold fronts in the Virgo cluster as a measure for the effective ICM viscosity

    CERN Document Server

    Roediger, E; Forman, W R; Nulsen, P E J; Churazov, E

    2012-01-01

    Sloshing cold fronts (CFs) arise from minor merger triggered gas sloshing. Their detailed structure depends on the properties of the intra-cluster medium (ICM): hydrodynamical simulations predict the CFs to be distorted by Kelvin-Helmholtz instabilities (KHIs), but aligned magnetic fields, viscosity, or thermal conduction can suppress the KHIs. Thus, observing the detailed structure of sloshing CFs can be used to constrain these ICM properties. Both smooth and distorted sloshing CFs have been observed, indicating that the KHI is suppressed in some clusters, but not in all. Consequently, we need to address at least some sloshing clusters individually before drawing general conclusions about the ICM properties. We present the first detailed attempt to constrain the ICM properties in a specific cluster from the structure of its sloshing CF. Proximity and brightness make the Virgo cluster an ideal target. We combine observations and Virgo-specific hydrodynamical sloshing simulations. Here we focus on a Spitzer-li...

  19. Comparative Study of K-means and Robust Clustering

    Directory of Open Access Journals (Sweden)

    Shashi Sharma

    2013-09-01

    Full Text Available Data mining is the mechanism of implementing patterns in large amount of data sets involving methods at the intersection of artificial intelligence, machine learning, statistics, and database systems. Clustering is the very big area in which grouping of same type of objects in data mining. Clustering has divided into different categories – partitioned clustering and hierarchical clustering. In this paper we study two types of clustering first is Kmeans which is part of partitioned clustering. Kmeans clustering generates a specific number of disjoint, flat (non-hierarchical clusters. Second clustering is robust clustering which is part of hierarchical clustering. This clustering uses Jaccard coefficient instead of using the distance measures to find the similarity between the data or documents to classify the clusters. We show comparison between Kmeans clustering and robust clustering which is better for categorical data.

  20. THE CONTRIBUTION OF RADIO GALAXY CONTAMINATION TO MEASUREMENTS OF THE SUNYAEV-ZEL'DOVICH DECREMENT IN MASSIVE GALAXY CLUSTERS AT 140 GHz WITH BOLOCAM

    Energy Technology Data Exchange (ETDEWEB)

    Sayers, J.; Mroczkowski, T.; Czakon, N. G.; Golwala, S. R.; Downes, T. P.; Muchovej, S. J. C.; Siegel, S. [Division of Physics, Math, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Mantz, A. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ameglio, S.; Pierpaoli, E.; Shitanishi, J. A. [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089 (United States); Koch, P. M.; Lin, K.-Y.; Umetsu, K. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Molnar, S. M. [LeCosPA Center, National Taiwan University, Taipei 10617, Taiwan (China); Moustakas, L., E-mail: jack@caltech.edu [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States)

    2013-02-20

    We describe in detail our characterization of the compact radio source population in 140 GHz Bolocam observations of a set of 45 massive galaxy clusters. We use a combination of 1.4 and 30 GHz data to select a total of 28 probable cluster-member radio galaxies and also to predict their 140 GHz flux densities. All of these galaxies are steep-spectrum radio sources and they are found preferentially in the cool-core clusters within our sample. In particular, 11 of the 12 brightest cluster-member radio sources are associated with cool-core systems. Although none of the individual galaxies are robustly detected in the Bolocam data, the ensemble-average flux density at 140 GHz is consistent with, but slightly lower than, the extrapolation from lower frequencies assuming a constant spectral index. In addition, our data indicate an intrinsic scatter of {approx_equal} 30% around the power-law extrapolated flux densities at 140 GHz, although our data do not tightly constrain this scatter. For our cluster sample, which is composed of high-mass and moderate-redshift systems, we find that the maximum fractional change in the Sunyaev-Zel'dovich signal integrated over any single cluster due to the presence of these radio sources is {approx_equal} 20%, and only {approx_equal} 1/4 of the clusters show a fractional change of more than 1%. The amount of contamination is strongly dependent on cluster morphology, and nearly all of the clusters with {>=}1% contamination are cool-core systems. This result indicates that radio contamination is not significant compared with current noise levels in 140 GHz images of massive clusters and is in good agreement with the level of radio contamination found in previous results based on lower frequency data or simulations.

  1. A cluster randomised controlled trial to evaluate the effectiveness of fluoride varnish as a public health measure to reduce caries in children.

    Science.gov (United States)

    Hardman, M C; Davies, G M; Duxbury, J T; Davies, R M

    2007-01-01

    This cluster randomised controlled study assessed the effectiveness of twice-yearly applications of fluoride varnish as a public health measure to reduce dental caries in children living in relatively deprived communities. The test (n = 334) and control (n = 330) children in 2 school years (unit of randomisation) attended 24 state primary schools and were 6-8 years of age at the start. Good baseline balance was found. Duraphat varnish was applied at school on 5 occasions over 26 months, by dental therapists. A combined visual and fibre-optic transillumination examination included all surfaces of primary and first permanent molars at baseline and after 26 months for small and large enamel and dentine lesions. At the final examination the only statistically significant difference was in the caries increment for small enamel lesions in the primary dentition, with the test children having fewer lesions. This study failed to demonstrate that the twice-yearly application of fluoride varnish provided at school reduced dental caries in children living in this community. The low level of response and a lower than expected caries increment had a major impact on the effectiveness of the intervention, since the children who participated were least likely to have benefited from the programme, whereas those who might have benefited did not consent.

  2. DYNAMO-HST Survey: Clumps in Nearby Massive Turbulent Disks and the Effects of Clump Clustering on Kiloparsec Scale Measurements of Clumps

    CERN Document Server

    Fisher, David B; Damjanov, Ivana; Abraham, Roberto G; Obreschkow, Danail; Wisnioski, Emily; Bassett, Robert; Green, Andy; McGregor, Peter

    2016-01-01

    We present $\\sim$100 pc resolution Hubble Space Telescope H$\\alpha$ images of 10 galaxies from the DYnamics of Newly-Assembled Massive Objects (DYNAMO) survey of low-$z$ turbulent disk galaxies, and use these to undertake the first detailed systematic study of the effects of resolution and clump clustering on observations of clumps in turbulent disks. In the DYNAMO-{\\em HST} sample we measure clump diameters spanning the range $d_{clump} \\sim 100-800$~pc, and individual clump star formation rates as high as $\\sim5$~M$_{\\odot}$~yr$^{-1}$. DYNAMO clumps have very high SFR surface densities, $\\Sigma_{SFR}\\sim 15$~M$_{\\odot}$~yr$^{-1}$~kpc$^{-2}$, $\\sim100\\times$ higher than in H{\\sc ii} regions of nearby spirals. Indeed, SFR surface density provides a simple dividing line between massive star forming clumps and local star forming regions, where massive star forming clumps have $\\Sigma_{SFR}> 0.5$~M$_{\\odot}$~yr$^{-1}$~kpc$^{-2}$. When degraded to match the observations of galaxies in $z\\sim 1-3$ surveys, DYNAMO ...

  3. Clustering of Luminous Red Galaxies IV: Baryon Acoustic Peak in the Line-of-Sight Direction and a Direct Measurement of H(z)

    CERN Document Server

    Gaztanaga, Enrique; Hui, Lam

    2008-01-01

    This is the 4th paper in a series where we study the clustering of LRG galaxies in the latest spectroscopic SDSS data release, DR6, which has 75000 LRG galaxies sampling 1.1 (Gpc/h)^3 to z=0.47. Here we study the 2-point correlation function, separated in perpendicular (sigma) and line-of-sight (pi) directions. We find a significant detection of a peak at r=110 Mpc/h, which shows as a circular ring in the sigma-pi plane. There is also a significant detection of the peak along the line-of-sight (LOS) direction both in sub-samples at low, z=0.15-30, and high redshifts, z=0.40-0.47. The overall shape and location of the peak is consistent with baryon acoustic oscillations (BAO). The amplitude in the line-of-sight direction, however, is larger than conventional expectations. We argue this is due to magnification bias. Because the data is shot noise dominated, a lensing boost in signal translates into a boost in S/N. We take advantage of this high S/N to produce, for the first time, a direct measurement of the Hub...

  4. Dynamic regional phase synchrony (DRePS): An Instantaneous Measure of Local fMRI Connectivity Within Spatially Clustered Brain Areas.

    Science.gov (United States)

    Omidvarnia, Amir; Pedersen, Mangor; Walz, Jennifer M; Vaughan, David N; Abbott, David F; Jackson, Graeme D

    2016-05-01

    Dynamic functional brain connectivity analysis is a fast expanding field in computational neuroscience research with the promise of elucidating brain network interactions. Sliding temporal window based approaches are commonly used in order to explore dynamic behavior of brain networks in task-free functional magnetic resonance imaging (fMRI) data. However, the low effective temporal resolution of sliding window methods fail to capture the full dynamics of brain activity at each time point. These also require subjective decisions regarding window size and window overlap. In this study, we introduce dynamic regional phase synchrony (DRePS), a novel analysis approach that measures mean local instantaneous phase coherence within adjacent fMRI voxels. We evaluate the DRePS framework on simulated data showing that the proposed measure is able to estimate synchrony at higher temporal resolution than sliding windows of local connectivity. We applied DRePS analysis to task-free fMRI data of 20 control subjects, revealing ultra-slow dynamics of local connectivity in different brain areas. Spatial clustering based on the DRePS feature time series reveals biologically congruent local phase synchrony networks (LPSNs). Taken together, our results demonstrate three main findings. Firstly, DRePS has increased temporal sensitivity compared to sliding window correlation analysis in capturing locally synchronous events. Secondly, DRePS of task-free fMRI reveals ultra-slow fluctuations of ∼0.002-0.02 Hz. Lastly, LPSNs provide plausible spatial information about time-varying brain local phase synchrony. With the DRePS method, we introduce a framework for interrogating brain local connectivity, which can potentially provide biomarkers of human brain function in health and disease. Hum Brain Mapp 37:1970-1985, 2016. © 2016 Wiley Periodicals, Inc.

  5. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: measurements of the growth of structure and expansion rate at z=0.57 from anisotropic clustering

    CERN Document Server

    Reid, Beth A; White, Martin; Percival, Will J; Manera, Marc; Padmanabhan, Nikhil; Ross, Ashley J; Sánchez, Ariel G; Bailey, Stephen; Bizyaev, Dmitry; Bolton, Adam S; Brewington, Howard; Brinkmann, J; Brownstein, Joel R; Cuesta, Antonio J; Eisenstein, Daniel J; Gunn, James E; Honscheid, Klaus; Malanushenko, Elena; Malanushenko, Viktor; Maraston, Claudia; McBride, Cameron K; Muna, Demitri; Nichol, Robert C; Oravetz, Daniel; Pan, Kaike; de Putter, Roland; Roe, N A; Ross, Nicholas P; Schlegel, David J; Schneider, Donald P; Seo, Hee-Jong; Shelden, Alaina; Sheldon, Erin S; Simmons, Audrey; Skibba, Ramin A; Snedden, Stephanie; Swanson, Molly E C; Thomas, Daniel; Tinker, Jeremy; Tojeiro, Rita; Verde, Licia; Wake, David A; Weaver, Benjamin A; Weinberg, David H; Zehavi, Idit; Zhao, Gong-Bo

    2012-01-01

    We analyze the anisotropic clustering of massive galaxies from the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) sample, which consists of 264,283 galaxies in the redshift range 0.43 0.57, and when combined imply \\Omega_{\\Lambda} = 0.74 +/- 0.016, independent of the Universe's evolution at z<0.57. In our companion paper (Samushia et al. prep), we explore further cosmological implications of these observations.

  6. Quotients of cluster categories

    OpenAIRE

    Jorgensen, Peter

    2007-01-01

    Higher cluster categories were recently introduced as a generalization of cluster categories. This paper shows that in Dynkin types A and D, half of all higher cluster categories are actually just quotients of cluster categories. The other half can be obtained as quotients of 2-cluster categories, the "lowest" type of higher cluster categories. Hence, in Dynkin types A and D, all higher cluster phenomena are implicit in cluster categories and 2-cluster categories. In contrast, the same is not...

  7. Regional Innovation Clusters

    Data.gov (United States)

    Small Business Administration — The Regional Innovation Clusters serve a diverse group of sectors and geographies. Three of the initial pilot clusters, termed Advanced Defense Technology clusters,...

  8. Brightest Cluster Galaxies and Core Gas Density in REXCESS Clusters

    CERN Document Server

    Haarsma, D B; Donahue, M; Bruch, S; Boehringer, H; Croston, J H; Pratt, G W; Voit, G M; Arnaud, M; Pierini, D

    2009-01-01

    We investigate the relationship between brightest cluster galaxies (BCGs) and their host clusters using a sample of nearby galaxy clusters from the Representative XMM-Newton Cluster Structure Survey (REXCESS). The sample was imaged with the Southern Observatory for Astrophysical Research (SOAR) in R band to investigate the mass of the old stellar population. Using a metric radius of 12h^-1 kpc, we find that the BCG luminosity depends weakly on overall cluster mass as L_BCG \\propto M_cl^0.18+-0.07, consistent with previous work. We found that 90% of the BCGs are located within 0.035 R_500 of the peak of the X-ray emission, including all of the cool core (CC) clusters. We also found an unexpected correlation between the BCG metric luminosity and the core gas density for non-cool core (non-CC) clusters, following a power law of n_e \\propto L_BCG^2.7+-0.4 (where n_e is measured at 0.008 R_500). The correlation is not easily explained by star formation (which is weak in non-CC clusters) or overall cluster mass (wh...

  9. Cluster forcing

    DEFF Research Database (Denmark)

    Christensen, Thomas Budde

    -industrialism and the ‘liveable' region. In this paper the cluster strategies that have been applied to the automotive sector in Wales are analysed. The paper includes a theoretical discussion on how the cluster concept has been applied to industrial policies, along with an empirical analysis of the application of the concept...... automotive sector in Wales. The paper draws from a survey of Welsh automotive suppliers on the characteristics of the local business environment and innovation. On the basis of the survey it is concluded that the public sector has an important task ahead concerning the linkages between universities and local...... businesses. The universities were not considered by the participating companies to be important parts of the local business environment and inputs from universities did not appear to be an important source to access knowledge about new product development or new techniques in production, distribution...

  10. UIDK-means: A multi-dimensional uncertain measurement data clustering algorithm%UIDK-means:多维不确定性测量数据聚类算法

    Institute of Scientific and Technical Information of China (English)

    彭宇; 罗清华; 彭喜元

    2011-01-01

    In uncertain measurement data clustering methods for networked measurement and test information system ,most methods assume the probability density function or probability distribution function of the measurement data is known, which is in contradiction with the issue that this information is rarely available. So in this paper, interval dato combined with statistic information is used to express multi-dimensional uncertain measurement data reasonably, a new uncertain distance computing method is proposed to measure the similarity of different uncertain data. And a new uncertain multi-dimension data clustering algorithm-UIDK-means based on the interval data is proposed and applied to uncertain measurement data. Experiment results show that the uncertain clustering algorithm can obtain better clustering precision with low computing complexity.%在网络化测试测量信息体系的不确定性测量数据聚类方法研究中,普遍假定测量数据的概率密度函数或者概率分布函数等信息是已知的,这与实际应用系统中这些信息难以获取的情况是相悖的,鉴于此,利用区间数的方法,结合测量数据的统计值来合理地表示多维不确定性测试测量数据,并采用低计算复杂度的不确定性数据距离计算方法,提出一种基于区间数的多维不确定性数据聚类方法--UIDK-means.实验结果表明,该方法具有较高的聚类精度和较低的计算复杂度.

  11. Multivariate Spatio-Temporal Clustering: A Framework for Integrating Disparate Data to Understand Network Representativeness and Scaling Up Sparse Ecosystem Measurements

    Science.gov (United States)

    Hoffman, F. M.; Kumar, J.; Maddalena, D. M.; Langford, Z.; Hargrove, W. W.

    2014-12-01

    Disparate in situ and remote sensing time series data are being collected to understand the structure and function of ecosystems and how they may be affected by climate change. However, resource and logistical constraints limit the frequency and extent of observations, particularly in the harsh environments of the arctic and the tropics, necessitating the development of a systematic sampling strategy to maximize coverage and objectively represent variability at desired scales. These regions host large areas of potentially vulnerable ecosystems that are poorly represented in Earth system models (ESMs), motivating two new field campaigns, called Next Generation Ecosystem Experiments (NGEE) for the Arctic and Tropics, funded by the U.S. Department of Energy. Multivariate Spatio-Temporal Clustering (MSTC) provides a quantitative methodology for stratifying sampling domains, informing site selection, and determining the representativeness of measurement sites and networks. We applied MSTC to down-scaled general circulation model results and data for the State of Alaska at a 4 km2 resolution to define maps of ecoregions for the present (2000-2009) and future (2090-2099), showing how combinations of 37 bioclimatic characteristics are distributed and how they may shift in the future. Optimal representative sampling locations were identified on present and future ecoregion maps, and representativeness maps for candidate sampling locations were produced. We also applied MSTC to remotely sensed LiDAR measurements and multi-spectral imagery from the WorldView-2 satellite at a resolution of about 5 m2 within the Barrow Environmental Observatory (BEO) in Alaska. At this resolution, polygonal ground features—such as centers, edges, rims, and troughs—can be distinguished. Using these remote sensing data, we up-scaled vegetation distribution data collected on these polygonal ground features to a large area of the BEO to provide distributions of plant functional types that can

  12. The HST/ACS Coma Cluster Survey. IV. Intergalactic Globular Clusters and the Massive Globular Cluster System at the Core of the Coma Galaxy Cluster

    NARCIS (Netherlands)

    Peng, Eric W.; Ferguson, Henry C.; Goudfrooij, Paul; Hammer, Derek; Lucey, John R.; Marzke, Ronald O.; Puzia, Thomas H.; Carter, David; Balcells, Marc; Bridges, Terry; Chiboucas, Kristin; del Burgo, Carlos; Graham, Alister W.; Guzmán, Rafael; Hudson, Michael J.; Matković, Ana; Merritt, David; Miller, Bryan W.; Mouhcine, Mustapha; Phillipps, Steven; Sharples, Ray; Smith, Russell J.; Tully, Brent; Verdoes Kleijn, Gijs

    2011-01-01

    Intracluster stellar populations are a natural result of tidal interactions in galaxy clusters. Measuring these populations is difficult, but important for understanding the assembly of the most massive galaxies. The Coma cluster of galaxies is one of the nearest truly massive galaxy clusters and is

  13. The HST/ACS Coma Cluster Survey : IV. Intergalactic Globular Clusters and the Massive Globular Cluster System at the Core of the Coma Galaxy Cluster

    NARCIS (Netherlands)

    Peng, Eric W.; Ferguson, Henry C.; Goudfrooij, Paul; Hammer, Derek; Lucey, John R.; Marzke, Ronald O.; Puzia, Thomas H.; Carter, David; Balcells, Marc; Bridges, Terry; Chiboucas, Kristin; del Burgo, Carlos; Graham, Alister W.; Guzman, Rafael; Hudson, Michael J.; Matkovic, Ana; Merritt, David; Miller, Bryan W.; Mouhcine, Mustapha; Phillipps, Steven; Sharples, Ray; Smith, Russell J.; Tully, Brent; Kleijn, Gijs Verdoes

    2011-01-01

    Intracluster stellar populations are a natural result of tidal interactions in galaxy clusters. Measuring these populations is difficult, but important for understanding the assembly of the most massive galaxies. The Coma cluster of galaxies is one of the nearest truly massive galaxy clusters and is

  14. Clustering Millions of Faces by Identity.

    Science.gov (United States)

    Otto, Charles; Wang, Dayong; Jain, Anil

    2017-03-07

    Given a large collection of unlabeled face images, we address the problem of clustering faces into an unknown number of identities. This problem is of interest in social media, law enforcement, and other applications, where the number of faces can be of the order of hundreds of million, while the number of identities (clusters) can range from a few thousand to millions. To address the challenges of run-time complexity and cluster quality, we present an approximate Rank-Order clustering algorithm that performs better than popular clustering algorithms (k-Means and Spectral). Our experiments include clustering up to 123 million face images into over 10 million clusters. Clustering results are analyzed in terms of external (known face labels) and internal (unknown face labels) quality measures, and run-time. Our algorithm achieves an F-measure of 0:87 on the LFW benchmark (13K faces of 5; 749 individuals), which drops to 0:27 on the largest dataset considered (13K faces in LFW + 123M distractor images). Additionally, we show that frames in the YouTube benchmark can be clustered with an F-measure of 0:71. An internal per-cluster quality measure is developed to rank individual clusters for manual exploration of high quality clusters that are compact and isolated.

  15. The Mass Function of Nearby Galaxy Clusters

    CERN Document Server

    Biviano, A; Giuricin, G; Mardirossian, F; Mezzetti, M

    1993-01-01

    We present the distribution of virial masses for nearby galaxy clusters, as obtained from a data-set of 75 clusters, each having at least 20 galaxy members with measured redshifts within 1 Abell radius. After having accounted for problems of incompleteness of the data-set, we fitted a power-law to the cluster mass distribution.

  16. M/L, H-alpha Rotation Curves, and HI Measurements for 329 Nearby Cluster and Field Spirals: II. Evidence for Galaxy Infall

    CERN Document Server

    Vogt, N P; Giovanelli, R; Herter, T; Vogt, Nicole P.; Haynes, Martha P.; Giovanelli, Riccardo; Herter, Terry

    2004-01-01

    We have conducted a study of optical and HI properties of spiral galaxies (size, luminosity, H-alpha flux distribution, circular velocity, HI gas mass) to explore the role of gas stripping as a driver of morphological evolution in clusters. We find a strong correlation between the spiral and S0 fractions within clusters, and the spiral fraction scales tightly with cluster X-ray gas luminosity. We explore young star formation and identify spirals that are (1) asymmetric, with truncated H-alpha emission and HI gas reservoirs on the leading edge of the disk, on a first pass through the dense intracluster medium in the cores of rich clusters; (2) strongly HI deficient and stripped, with star formation confined to the inner 5 kpc/h and 3 disk scale lengths; (3) reddened, extremely HI deficient and quenched, where star formation has been halted across the entire disk. We propose that these spirals are in successive stages of morphological transformation, between infalling field spirals and cluster S0s, and that the...

  17. Brightest Cluster Galaxies and Core Gas Density in REXCESS Clusters

    Science.gov (United States)

    Haarsma, Deborah B.; Leisman, Luke; Donahue, Megan; Bruch, Seth; Böhringer, Hans; Croston, Judith H.; Pratt, Gabriel W.; Voit, G. Mark; Arnaud, Monique; Pierini, Daniele

    2010-04-01

    We investigate the relationship between brightest cluster galaxies (BCGs) and their host clusters using a sample of nearby galaxy clusters from the Representative XMM-Newton Cluster Structure Survey. The sample was imaged with the Southern Observatory for Astrophysical Research in R band to investigate the mass of the old stellar population. Using a metric radius of 12 h -1 kpc, we found that the BCG luminosity depends weakly on overall cluster mass as L BCG vprop M 0.18±0.07 cl, consistent with previous work. We found that 90% of the BCGs are located within 0.035 r 500 of the peak of the X-ray emission, including all of the cool core (CC) clusters. We also found an unexpected correlation between the BCG metric luminosity and the core gas density for non-cool-core (non-CC) clusters, following a power law of ne vprop L 2.7±0.4 BCG (where ne is measured at 0.008 r 500). The correlation is not easily explained by star formation (which is weak in non-CC clusters) or overall cluster mass (which is not correlated with core gas density). The trend persists even when the BCG is not located near the peak of the X-ray emission, so proximity is not necessary. We suggest that, for non-CC clusters, this correlation implies that the same process that sets the central entropy of the cluster gas also determines the central stellar density of the BCG, and that this underlying physical process is likely to be mergers.

  18. An Automatic Clustering Technique for Optimal Clusters

    CERN Document Server

    Pavan, K Karteeka; Rao, A V Dattatreya; 10.5121/ijcsea.2011.1412

    2011-01-01

    This paper proposes a simple, automatic and efficient clustering algorithm, namely, Automatic Merging for Optimal Clusters (AMOC) which aims to generate nearly optimal clusters for the given datasets automatically. The AMOC is an extension to standard k-means with a two phase iterative procedure combining certain validation techniques in order to find optimal clusters with automation of merging of clusters. Experiments on both synthetic and real data have proved that the proposed algorithm finds nearly optimal clustering structures in terms of number of clusters, compactness and separation.

  19. Applications of Cluster Analysis to the Creation of Perfectionism Profiles: A Comparison of two Clustering Approaches

    Directory of Open Access Journals (Sweden)

    Jocelyn H Bolin

    2014-04-01

    Full Text Available Although traditional clustering methods (e.g., K-means have been shown to be useful in the social sciences it is often difficult for such methods to handle situations where clusters in the population overlap or are ambiguous. Fuzzy clustering, a method already recognized in many disciplines, provides a more flexible alternative to these traditional clustering methods. Fuzzy clustering differs from other traditional clustering methods in that it allows for a case to belong to multiple clusters simultaneously. Unfortunately, fuzzy clustering techniques remain relatively unused in the social and behavioral sciences. The purpose of this paper is to introduce fuzzy clustering to these audiences who are currently relatively unfamiliar with the technique. In order to demonstrate the advantages associated with this method, cluster solutions of a common perfectionism measure were created using both fuzzy clustering and K-means clustering, and the results compared. Results of these analyses reveal that different cluster solutions are found by the two methods, and the similarity between the different clustering solutions depends on the amount of cluster overlap allowed for in fuzzy clustering.

  20. 3D stellar kinematics at the Galactic center: measuring the nuclear star cluster spatial density profile, black hole mass, and distance

    CERN Document Server

    Do, T; Yelda, S; Ghez, A M; Bullock, J; Kaplinghat, M; Lu, J R; Peter, A G H; Phifer, K

    2013-01-01

    We present 3D kinematic observations of stars within the central 0.5 pc of the Milky Way nuclear star cluster using adaptive optics imaging and spectroscopy from the Keck telescopes. Recent observations have shown that the cluster has a shallower surface density profile than expected for a dynamically relaxed cusp, leading to important implications for its formation and evolution. However, the true three dimensional profile of the cluster is unknown due to the difficulty in de-projecting the stellar number counts. Here, we use spherical Jeans modeling of individual proper motions and radial velocities to constrain for the first time, the de-projected spatial density profile, cluster velocity anisotropy, black hole mass ($M_\\mathrm{BH}$), and distance to the Galactic center ($R_0$) simultaneously. We find that the inner stellar density profile of the late-type stars, $\\rho(r)\\propto r^{-\\gamma}$ to have a power law slope $\\gamma=0.05_{-0.60}^{+0.29}$, much more shallow than the frequently assumed Bahcall $\\&am...

  1. Fuzzy clustering of mechanisms

    Indian Academy of Sciences (India)

    Amitabha Ghosh; Dilip Kumar Pratihar; M V V Amarnath; Guenter Dittrich; Jorg Mueller

    2012-10-01

    During the course of development of Mechanical Engineering, a large number of mechanisms (that is, linkages to perform various types of tasks) have been conceived and developed. Quite a few atlases and catalogues were prepared by the designers of machines and mechanical systems. However, often it is felt that a clustering technique for handling the list of large number of mechanisms can be very useful,if it is developed based on a scientific principle. In this paper, it has been shown that the concept of fuzzy sets can be conveniently used for this purpose, if an adequate number of properly chosen attributes (also called characteristics) are identified. Using two clustering techniques, the mechanisms have been classified in the present work and in future, it may be extended to develop an expert system, which can automate type synthesis phase of mechanical design. To the best of the authors’ knowledge, this type of clustering of mechanisms has not been attempted before. Thus, this is the first attempt to cluster the mechanisms based on some quantitative measures. It may help the engineers to carry out type synthesis of the mechanisms.

  2. Tropospheric Ozonesonde Profiles at Long-Term U.S. Monitoring Sites: 2. Links Between Trinidad Head, CA, Profile Clusters and Inland Surface Ozone Measurements

    Science.gov (United States)

    Stauffer, Ryan M.; Thompson, Anne M.; Oltmans, Samual J.; Johnson, Bryan J.

    2017-01-01

    Much attention has been focused on the transport of ozone (O3) to the western U.S., particularly given the latest revision of the National Ambient Air Quality Standard to 70 parts per billion by volume (ppbv) of O3. This makes quantifying the contributions of stratosphere-to-troposphere exchange, local pollution, and pollution transport to this region essential. To evaluate free-tropospheric and surface O3 in the western U.S., we use self-organizing maps to cluster 18 years of ozonesonde profiles from Trinidad Head, CA. Three of nine O3 mixing ratio profile clusters exhibit thin laminae of high O3 above Trinidad Head. The high O3 layers are located between 1 and 6 km above mean sea level and reside above an inversion associated with a northern location of the Pacific subtropical high. Ancillary data (reanalyses, trajectories, and remotely sensed carbon monoxide) help identify the high O3 sources in one cluster, but distinguishing mixed influences on the elevated O3 in other clusters is difficult. Correlations between the elevated tropospheric O3 and surface O3 at high-altitude monitors at Lassen Volcanic and Yosemite National Parks, and Truckee, CA, are marked and long lasting. The temporal correlations likely result from a combination of transport of baseline O3 and covarying meteorological parameters. Days corresponding to the high O3 clusters exhibit hourly surface O3 anomalies of +5-10 ppbv compared to a climatology; the positive anomalies can last up to 3 days after the ozonesonde profile. The profile and surface O3 links demonstrate the importance of regular ozonesonde profiling at Trinidad Head.

  3. Tropospheric ozonesonde profiles at long-term U.S. monitoring sites: 2. Links between Trinidad Head, CA, profile clusters and inland surface ozone measurements

    Science.gov (United States)

    Stauffer, Ryan M.; Thompson, Anne M.; Oltmans, Samuel J.; Johnson, Bryan J.

    2017-01-01

    Much attention has been focused on the transport of ozone (O3) to the western U.S., particularly given the latest revision of the National Ambient Air Quality Standard to 70 parts per billion by volume (ppbv) of O3. This makes quantifying the contributions of stratosphere-to-troposphere exchange, local pollution, and pollution transport to this region essential. To evaluate free-tropospheric and surface O3 in the western U.S., we use self-organizing maps to cluster 18 years of ozonesonde profiles from Trinidad Head, CA. Three of nine O3 mixing ratio profile clusters exhibit thin laminae of high O3 above Trinidad Head. The high O3 layers are located between 1 and 6 km above mean sea level and reside above an inversion associated with a northern location of the Pacific subtropical high. Ancillary data (reanalyses, trajectories, and remotely sensed carbon monoxide) help identify the high O3 sources in one cluster, but distinguishing mixed influences on the elevated O3 in other clusters is difficult. Correlations between the elevated tropospheric O3 and surface O3 at high-altitude monitors at Lassen Volcanic and Yosemite National Parks, and Truckee, CA, are marked and long lasting. The temporal correlations likely result from a combination of transport of baseline O3 and covarying meteorological parameters. Days corresponding to the high O3 clusters exhibit hourly surface O3 anomalies of +5-10 ppbv compared to a climatology; the positive anomalies can last up to 3 days after the ozonesonde profile. The profile and surface O3 links demonstrate the importance of regular ozonesonde profiling at Trinidad Head.

  4. The Sloan Nearby Cluster Weak Lensing Survey

    CERN Document Server

    Kubo, Jeffrey M; Hardin, Frances Mei; Kubik, Donna; Lawhorn, Kelsey; Lin, Huan; Nicklaus, Liana; Nelson, Dylan; Reis, Ribamar R R; Seo, Hee-Jong; Soares-Santos, Marcelle; Stebbins, Albert; Yunker, Tony

    2009-01-01

    We describe and present initial results of a weak lensing survey of nearby ($\\rm{z}\\lesssim0.1$) galaxy clusters in the Sloan Digital Sky Survey (SDSS). In this first study, galaxy clusters are selected from the SDSS spectroscopic galaxy cluster catalogs of \\citet{miller05} and \\citet{berlind06}. We report a total of seven individual low redshift cluster weak lensing measurements which include: A2048, A1767, A2244, A1066, A2199, and two clusters specifically identified with the C4 algorithm. Our program of weak lensing of nearby galaxy clusters in the SDSS will eventually reach $\\sim 200$ clusters, making it the largest weak lensing survey of individual galaxy clusters to date.

  5. Polarizability effect in metallic clusters

    Indian Academy of Sciences (India)

    Ş Şentürk; K Harigaya; O Özsoy

    2006-03-01

    Langevin approach implemented in the inelastic cross-sections measured for the low-energy electrons colliding with metallic clusters points out that statical form of the polarizability dominate at energies less than 1.25 eV. The dynamical form comes into play at energies around 1.3 eV. The form of the polarizabilities indicates that polarizability of the metallic clusters is energy-dependent.

  6. Using PEACE Data from the four CLUSTER Spacecraft to Measure Compressibility, Vorticity, and the Taylor Microscale in the Magnetosheath and Plasma Sheet

    Science.gov (United States)

    Goldstein, Melvyn L.; Parks, George; Gurgiolo, C.; Fazakerley, Andrew N.

    2008-01-01

    We present determinations of compressibility and vorticity in the magnetosheath and plasma sheet using moments from the four PEACE thermal electron instruments on CLUSTER. The methodology used assumes a linear variation of the moments throughout the volume defined by the four satellites, which allows spatially independent estimates of the divergence, curl, and gradient. Once the vorticity has been computed, it is possible to estimate directly the Taylor microscale. We have shown previously that the technique works well in the solar wind. Because the background flow speed in the magnetosheath and plasma sheet is usually less than the Alfven speed, the Taylor frozen-in-flow approximation cannot be used. Consequently, this four spacecraft approach is the only viable method for obtaining the wave number properties of the ambient fluctuations. Our results using electron velocity moments will be compared with previous work using magnetometer data from the FGM experiment on Cluster.

  7. CONSIDERATIONS REGARDING THE FACTORS THAT INFLUENCE THE PERFORMANCE OF CLUSTER

    Directory of Open Access Journals (Sweden)

    DANA-CODRUŢA DUDĂ-DĂIANU

    2012-05-01

    Full Text Available Economic performance is an objective of each cluster and innovation is a result of future performance indicator. The working paper proposed to measure the cluster performance based on three success factors: competitiveness cluster, cluster growth and the degree of the objectives. Based on Porter's diamond model will be a breakdown of the main factors influencing the development of clusters and their delineation in general and specific factors cluster. In the same time, will analyze the main directions that define performance clusters: access to resources, access to specialized knowledge, entrepreneurship based on the opportunities, collaboration between organizations and cluster specific organizational culture.

  8. Improvements on GPS Location Cluster Analysis for the Prediction of Large Carnivore Feeding Activities: Ground-Truth Detection Probability and Inclusion of Activity Sensor Measures.

    Directory of Open Access Journals (Sweden)

    Kevin A Blecha

    Full Text Available Animal space use studies using GPS collar technology are increasingly incorporating behavior based analysis of spatio-temporal data in order to expand inferences of resource use. GPS location cluster analysis is one such technique applied to large carnivores to identify the timing and location of feeding events. For logistical and financial reasons, researchers often implement predictive models for identifying these events. We present two separate improvements for predictive models that future practitioners can implement. Thus far, feeding prediction models have incorporated a small range of covariates, usually limited to spatio-temporal characteristics of the GPS data. Using GPS collared cougar (Puma concolor we include activity sensor data as an additional covariate to increase prediction performance of feeding presence/absence. Integral to the predictive modeling of feeding events is a ground-truthing component, in which GPS location clusters are visited by human observers to confirm the presence or absence of feeding remains. Failing to account for sources of ground-truthing false-absences can bias the number of predicted feeding events to be low. Thus we account for some ground-truthing error sources directly in the model with covariates and when applying model predictions. Accounting for these errors resulted in a 10% increase in the number of clusters predicted to be feeding events. Using a double-observer design, we show that the ground-truthing false-absence rate is relatively low (4% using a search delay of 2-60 days. Overall, we provide two separate improvements to the GPS cluster analysis techniques that can be expanded upon and implemented in future studies interested in identifying feeding behaviors of large carnivores.

  9. M/L, Hα Rotation Curves, and H I Gas Measurements for 329 Nearby Cluster and Field Spirals. III. Evolution in Fundamental Galaxy Parameters

    Science.gov (United States)

    Vogt, Nicole P.; Haynes, Martha P.; Giovanelli, Riccardo; Herter, Terry

    2004-06-01

    We have conducted a study of optical and H I properties of spiral galaxies (size, luminosity, Hα flux distribution, circular velocity, H I gas mass) to investigate causes (e.g., nature vs. nurture) for variation within the cluster environment. We find H I-deficient cluster galaxies to be offset in fundamental plane space, with disk scale lengths decreased by a factor of 25%. This may be a relic of early galaxy formation, caused by the disk coalescing out of a smaller, denser halo (e.g., higher concentration index) or by truncation of the hot gas envelope due to the enhanced local density of neighbors, although we cannot completely rule out the effect of the gas stripping process. The spatial extent of Hα flux and the B-band radius also decreases, but only in early-type spirals, suggesting that gas removal is less efficient within steeper potential wells (or that stripped late-type spirals are quickly rendered unrecognizable). We find no significant trend in stellar mass-to-light ratios or circular velocities with H I gas content, morphological type, or clustercentric radius, for star-forming spiral galaxies throughout the clusters. These data support the findings of a companion paper that gas stripping promotes a rapid truncation of star formation across the disk and could be interpreted as weak support for dark matter domination over baryons in the inner regions of spiral galaxies.

  10. Cluster headache

    Directory of Open Access Journals (Sweden)

    Ducros Anne

    2008-07-01

    Full Text Available Abstract Cluster headache (CH is a primary headache disease characterized by recurrent short-lasting attacks (15 to 180 minutes of excruciating unilateral periorbital pain accompanied by ipsilateral autonomic signs (lacrimation, nasal congestion, ptosis, miosis, lid edema, redness of the eye. It affects young adults, predominantly males. Prevalence is estimated at 0.5–1.0/1,000. CH has a circannual and circadian periodicity, attacks being clustered (hence the name in bouts that can occur during specific months of the year. Alcohol is the only dietary trigger of CH, strong odors (mainly solvents and cigarette smoke and napping may also trigger CH attacks. During bouts, attacks may happen at precise hours, especially during the night. During the attacks, patients tend to be restless. CH may be episodic or chronic, depending on the presence of remission periods. CH is associated with trigeminovascular activation and neuroendocrine and vegetative disturbances, however, the precise cautive mechanisms remain unknown. Involvement of the hypothalamus (a structure regulating endocrine function and sleep-wake rhythms has been confirmed, explaining, at least in part, the cyclic aspects of CH. The disease is familial in about 10% of cases. Genetic factors play a role in CH susceptibility, and a causative role has been suggested for the hypocretin receptor gene. Diagnosis is clinical. Differential diagnoses include other primary headache diseases such as migraine, paroxysmal hemicrania and SUNCT syndrome. At present, there is no curative treatment. There are efficient treatments to shorten the painful attacks (acute treatments and to reduce the number of daily attacks (prophylactic treatments. Acute treatment is based on subcutaneous administration of sumatriptan and high-flow oxygen. Verapamil, lithium, methysergide, prednisone, greater occipital nerve blocks and topiramate may be used for prophylaxis. In refractory cases, deep-brain stimulation of the

  11. Partitional clustering algorithms

    CERN Document Server

    2015-01-01

    This book summarizes the state-of-the-art in partitional clustering. Clustering, the unsupervised classification of patterns into groups, is one of the most important tasks in exploratory data analysis. Primary goals of clustering include gaining insight into, classifying, and compressing data. Clustering has a long and rich history that spans a variety of scientific disciplines including anthropology, biology, medicine, psychology, statistics, mathematics, engineering, and computer science. As a result, numerous clustering algorithms have been proposed since the early 1950s. Among these algorithms, partitional (nonhierarchical) ones have found many applications, especially in engineering and computer science. This book provides coverage of consensus clustering, constrained clustering, large scale and/or high dimensional clustering, cluster validity, cluster visualization, and applications of clustering. Examines clustering as it applies to large and/or high-dimensional data sets commonly encountered in reali...

  12. Clustering and Community Detection with Imbalanced Clusters

    OpenAIRE

    Aksoylar, Cem; Qian, Jing; Saligrama, Venkatesh

    2016-01-01

    Spectral clustering methods which are frequently used in clustering and community detection applications are sensitive to the specific graph constructions particularly when imbalanced clusters are present. We show that ratio cut (RCut) or normalized cut (NCut) objectives are not tailored to imbalanced cluster sizes since they tend to emphasize cut sizes over cut values. We propose a graph partitioning problem that seeks minimum cut partitions under minimum size constraints on partitions to de...

  13. Effect of UV lamp irradiation during oxidation of Zr/Pt/Si structure on electrical properties of Pt/ZrO{sub 2}/Pt/Si structure

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Joon Woo [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Lim, Jae-Won, E-mail: flashlim@kigam.re.kr [Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of); Mimura, Kouji; Uchikoshi, Masahito [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Miyazaki, Takamichi [School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Isshiki, Minoru [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2010-03-15

    Metal-insulator-metal (MIM) capacitors were fabricated using ZrO{sub 2} films and the effects of structural and native defects of the ZrO{sub 2} films on the electrical and dielectric properties were investigated. For preparing ZrO{sub 2} films, Zr films were deposited on Pt/Si substrates by ion beam deposition (IBD) system with/without substrate bias voltages and oxidized at 200 deg. C for 60 min under 0.1 MPa O{sub 2} atmosphere with/without UV light irradiation ({lambda} = 193 nm, Deep UV lamp). The ZrO{sub 2}({approx}12 nm) films on Pt({approx}100 nm)/Si were characterized by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM), capacitance-voltage (C-V) and current-voltage (I-V) measurements were carried out on MIM structures. ZrO{sub 2} films, fabricated by oxidizing the Zr film deposited with substrate bias voltage under UV light irradiation, show the highest capacitance (784 pF) and the lowest leakage current density. The active oxygen species formed by UV irradiation are considered to play an important role in the reduction of the leakage current density, because they can reduce the density of oxygen vacancies.

  14. Cluster headaches.

    Science.gov (United States)

    Ryan, R E; Ryan, R E

    1989-12-01

    The patient with cluster headaches will be afflicted with the most severe type of pain that one will encounter. If the physician can do something to help this patient either by symptomatic or, more importantly, prophylactic treatment, he or she will have a most thankful patient. This type of headache is seen most frequently in men, and occurs in a cyclic manner. During an acute cycle, the patient will experience a daily type of pain that may occur many times per day. The pain is usually unilateral and may be accompanied by unilateral lacrimation, conjunctivitis, and clear rhinorrhea. Prednisone is the first treatment we employ. Patients are seen for follow-up approximately twice a week, and their medication is lowered in an appropriate manner, depending on their response to the treatment. Regulation of dosage has to be individualized, and when one reaches the lower dose such as 5 to 10 mg per day, the drug may have to be tapered more slowly, or even maintained at that level for a period of time to prevent further recurrence of symptoms. We frequently will use an intravenous histamine desensitization technique to prevent further attacks. We will give the patient an ergotamine preparation to use for symptomatic relief. As these patients often have headaches during the middle of the night, we will place the patient on a 2-mg ergotamine preparation to take prior to going to bed in the evening. This often works in a prophylactic nature, and prevents the nighttime occurrence of a headache. We believe that following these principles to make the accurate diagnosis and institute the proper therapy will help the practicing otolaryngologist recognize and treat patients suffering from this severe pain.

  15. IRAC imaging of GOGREEN clusters

    Science.gov (United States)

    McGee, Sean; Balogh, Michael; Cooper, Michael; Gilbank, David; Lidman, Chris; Muzzin, Adam; Old, Lyndsay; Rudnick, Greg; Wilson, Gillian; Yee, Howard

    2016-08-01

    We propose deep IRAC imaging of three galaxy clusters drawn from the GOGREEN survey of 21 galaxy clusters in the redshift range 1 Magellan and CFHT imaging and by an ongoing Gemini Large Programme, with which we are obtaining deep spectroscopy of > 1000 member and > 600 field galaxies. With these data and our own lower-redshift descendant data, we will measure 1) the evolution of the quenched fraction and its dependence on distance from the cluster center and 2) the relation between stellar and halo mass and its evolution. This will provide unique constraints to our in-house theoretical models at an epoch where there are currently almost none available. The imaging that we propose will ensure all 21 GOGREEN clusters have deep IRAC data, ensuring the lasting legacy of this benchmark sample.

  16. Intuitionistic fuzzy hierarchical clustering algorithms

    Institute of Scientific and Technical Information of China (English)

    Xu Zeshui

    2009-01-01

    Intuitionistic fuzzy set (IFS) is a set of 2-tuple arguments, each of which is characterized by a mem-bership degree and a nonmembership degree. The generalized form of IFS is interval-valued intuitionistic fuzzy set (IVIFS), whose components are intervals rather than exact numbers. IFSs and IVIFSs have been found to be very useful to describe vagueness and uncertainty. However, it seems that little attention has been focused on the clus-tering analysis of IFSs and IVIFSs. An intuitionistic fuzzy hierarchical algorithm is introduced for clustering IFSs, which is based on the traditional hierarchical clustering procedure, the intuitionistic fuzzy aggregation operator, and the basic distance measures between IFSs: the Hamming distance, normalized Hamming, weighted Hamming, the Euclidean distance, the normalized Euclidean distance, and the weighted Euclidean distance. Subsequently, the algorithm is extended for clustering IVIFSs. Finally the algorithm and its extended form are applied to the classifications of building materials and enterprises respectively.

  17. Prediction of (195) Pt NMR chemical shifts of dissolution products of H2 [Pt(OH)6 ] in nitric acid solutions by DFT methods: how important are the counter-ion effects?

    Science.gov (United States)

    Tsipis, Athanassios C; Karapetsas, Ioannis N

    2016-08-01

    (195) Pt NMR chemical shifts of octahedral Pt(IV) complexes with general formula [Pt(NO3 )n (OH)6 - n ](2-) , [Pt(NO3 )n (OH2 )6 - n ](4 - n) (n = 1-6), and [Pt(NO3 )6 - n  - m (OH)m (OH2 )n ](-2 + n - m) formed by dissolution of platinic acid, H2 [Pt(OH)6 ], in aqueous nitric acid solutions are calculated employing density functional theory methods. Particularly, the gauge-including atomic orbitals (GIAO)-PBE0/segmented all-electron relativistically contracted-zeroth-order regular approximation (SARC-ZORA)(Pt) ∪ 6-31G(d,p)(E)/Polarizable Continuum Model computational protocol performs the best. Excellent second-order polynomial plots of δcalcd ((195) Pt) versus δexptl ((195) Pt) chemical shifts and δcalcd ((195) Pt) versus the natural atomic charge QPt are obtained. Despite of neglecting relativistic and spin orbit effects the good agreement of the calculated δ (195) Pt chemical shifts with experimental values is probably because of the fact that the contribution of relativistic and spin orbit effects to computed σ(iso) (195) Pt magnetic shielding of Pt(IV) coordination compounds is effectively cancelled in the computed δ (195) Pt chemical shifts, because the relativistic corrections are expected to be similar in the complexes and the proper reference standard used. To probe the counter-ion effects on the (195) Pt NMR chemical shifts of the anionic [Pt(NO3 )n (OH)6 - n ](2-) and cationic [Pt(NO3 )n (OH2 )6 - n ](4 - n) (n = 0-3) complexes we calculated the (195) Pt NMR chemical shifts of the neutral (PyH)2 [Pt(NO3 )n (OH)6 - n ] (n = 1-6; PyH = pyridinium cation, C5 H5 NH(+) ) and [Pt(NO3 )n (H2 O)6 - n ](NO3 )4 - n (n = 0-3) complexes. Counter-anion effects are very important for the accurate prediction of the (195) Pt NMR chemical shifts of the cationic [Pt(NO3 )n (OH2 )6 - n ](4 - n) complexes, while counter-cation effects are less important for the anionic [Pt(NO3 )n (OH)6

  18. M/L, H-alpha Rotation Curves, and HI Measurements for 329 Nearby Cluster and Field Spirals: III. Evolutionin Fundamental Galaxy Parameters

    CERN Document Server

    Vogt, N P; Giovanelli, R; Herter, T; Vogt, Nicole P.; Haynes, Martha P.; Giovanelli, Riccardo; Herter, Terry

    2004-01-01

    We have conducted a study of optical and HI properties of spiral galaxies (size, luminosity, H-alpha flux distribution, circular velocity, HI gas mass) to investigate causes (e.g., nature versus nurture) for variation within the cluster environment. We find HI deficient cluster galaxies to be offset in Fundamental Plane space, with disk scale lengths decreased by a factor of 25%. This may be a relic of early galaxy formation, caused by the disk coalescing out of a smaller, denser halo (e.g., higher concentration index) or by truncation of the hot gas envelope due to the enhanced local density of neighbors, though we cannot completely rule out the effect of the gas stripping process. The spatial extent of H-alpha flux and the B-band radius also decreases, but only in early type spirals, suggesting that gas removal is less efficient within steeper potential wells (or that stripped late type spirals are quickly rendered unrecognizable). We find no significant trend in stellar mass-to-light ratios or circular vel...

  19. Factorial PD-Clustering

    CERN Document Server

    Tortora, Cristina; Summa, Mireille Gettler

    2011-01-01

    Factorial clustering methods have been developed in recent years thanks to the improving of computational power. These methods perform a linear transformation of data and a clustering on transformed data optimizing a common criterion. Factorial PD-clustering is based on Probabilistic Distance clustering (PD-clustering). PD-clustering is an iterative, distribution free, probabilistic, clustering method. Factorial PD-clustering make a linear transformation of original variables into a reduced number of orthogonal ones using a common criterion with PD-Clustering. It is demonstrated that Tucker 3 decomposition allows to obtain this transformation. Factorial PD-clustering makes alternatively a Tucker 3 decomposition and a PD-clustering on transformed data until convergence. This method could significantly improve the algorithm performance and allows to work with large dataset, to improve the stability and the robustness of the method.

  20. Breaking the hierarchy - a new cluster selection mechanism for hierarchical clustering methods

    Directory of Open Access Journals (Sweden)

    Zweig Katharina A

    2009-10-01

    Full Text Available Abstract Background Hierarchical clustering methods like Ward's method have been used since decades to understand biological and chemical data sets. In order to get a partition of the data set, it is necessary to choose an optimal level of the hierarchy by a so-called level selection algorithm. In 2005, a new kind of hierarchical clustering method was introduced by Palla et al. that differs in two ways from Ward's method: it can be used on data on which no full similarity matrix is defined and it can produce overlapping clusters, i.e., allow for multiple membership of items in clusters. These features are optimal for biological and chemical data sets but until now no level selection algorithm has been published for this method. Results In this article we provide a general selection scheme, the level independent clustering selection method, called LInCS. With it, clusters can be selected from any level in quadratic time with respect to the number of clusters. Since hierarchically clustered data is not necessarily associated with a similarity measure, the selection is based on a graph theoretic notion of cohesive clusters. We present results of our method on two data sets, a set of drug like molecules and set of protein-protein interaction (PPI data. In both cases the method provides a clustering with very good sensitivity and specificity values according to a given reference clustering. Moreover, we can show for the PPI data set that our graph theoretic cohesiveness measure indeed chooses biologically homogeneous clusters and disregards inhomogeneous ones in most cases. We finally discuss how the method can be generalized to other hierarchical clustering methods to allow for a level independent cluster selection. Conclusion Using our new cluster selection method together with the method by Palla et al. provides a new interesting clustering mechanism that allows to compute overlapping clusters, which is especially valuable for biological and

  1. Rotation and flattening of globular clusters

    Science.gov (United States)

    Fall, S. M.; Frenk, C. S.

    1985-01-01

    Methods for measuring globular cluster ellipticities and the results of such measurements are reviewed, and the processes that determine the shapes of globular clusters and the ways in which they change with time are discussed. The use of the virial tensor theorem to study the connection between the global rotation, velocity anisotropy, and the shape of a self-gravitating system is addressed, and the employment of N-body models to simulate the evolution of globular clusters with initially anisotropic velocity distributions is examined. The application of a simple evaporation model and Fokker-Planck integrations to study the two-body diffusion in globular clusters is reviewed.

  2. Possibilistic Exponential Fuzzy Clustering

    Institute of Scientific and Technical Information of China (English)

    Kiatichai Treerattanapitak; Chuleerat Jaruskulchai

    2013-01-01

    Generally,abnormal points (noise and outliers) cause cluster analysis to produce low accuracy especially in fuzzy clustering.These data not only stay in clusters but also deviate the centroids from their true positions.Traditional fuzzy clustering like Fuzzy C-Means (FCM) always assigns data to all clusters which is not reasonable in some circumstances.By reformulating objective function in exponential equation,the algorithm aggressively selects data into the clusters.However noisy data and outliers cannot be properly handled by clustering process therefore they are forced to be included in a cluster because of a general probabilistic constraint that the sum of the membership degrees across all clusters is one.In order to improve this weakness,possibilistic approach relaxes this condition to improve membership assignment.Nevertheless,possibilistic clustering algorithms generally suffer from coincident clusters because their membership equations ignore the distance to other clusters.Although there are some possibilistic clustering approaches that do not generate coincident clusters,most of them require the right combination of multiple parameters for the algorithms to work.In this paper,we theoretically study Possibilistic Exponential Fuzzy Clustering (PXFCM) that integrates possibilistic approach with exponential fuzzy clustering.PXFCM has only one parameter and not only partitions the data but also filters noisy data or detects them as outliers.The comprehensive experiments show that PXFCM produces high accuracy in both clustering results and outlier detection without generating coincident problems.

  3. Consistência do padrão de agrupamento de cultivares de feijão conforme medidas de dissimilaridade e métodos de agrupamento Clustering pattern consistency of common bean cultivars by dissimilarity measures and clustering methods

    Directory of Open Access Journals (Sweden)

    Alberto Cargnelutti Filho

    2010-03-01

    Full Text Available O objetivo deste trabalho foi avaliar a consistência do padrão de agrupamento de cultivares de feijão (Phaseolus vulgaris L., obtido a partir da combinação de oito medidas de dissimilaridade e oito métodos de agrupamento. Treze cultivares de feijão foram avaliadas em nove experimentos conduzidos entre os anos agrícolas de 2000/2001 e 2004/2005, e agrupadas de acordo com caracteres de produção (produtividade de grãos, número de vagens por planta, de fenologia (número de dias da emergência ao florescimento e da emergência à colheita e de morfologia (altura de inserção da primeira e da última vagem. Foram realizadas análises de variância, de correlação, de diagnóstico de multicolinearidade, de agrupamento e de comparação de médias. A consistência do padrão de agrupamento foi avaliada por meio do coeficiente de correlação cofenética. Há variabilidade na consistência do padrão de agrupamento das cultivares de feijão, obtido a partir da combinação de diferentes medidas de dissimilaridade e métodos de agrupamento. Maior consistência nos padrões de agrupamento de cultivares de feijão é verificada com o método da ligação média entre grupo, obtido a partir da matriz de distância euclidiana.The objective of this work was to evaluate the clustering pattern consistency in common bean cultivars (Phaseolus vulgaris L. obtained from the combination of the eight dissimilarity measures and eight clustering methods. Thirteen common bean cultivars were evaluated in nine experiments conducted in the growing seasons between 2000/2001 and 2004/2005 and grouped according to productive (grain yield and number of pods per plant, phenological (number of days between seedling emergence and flowering, and number of days from emergence to harvest and morphological (height of first pod insertion and height of the final pod insertion characters. Analyses of variance, correlation, diagnoses of multicollinearity, cluster and

  4. PHAT Stellar Cluster Survey. II. Andromeda Project Cluster Catalog

    CERN Document Server

    Johnson, L Clifton; Dalcanton, Julianne J; Wallace, Matthew L; Simpson, Robert J; Lintott, Chris J; Kapadia, Amit; Skillman, Evan D; Caldwell, Nelson; Fouesneau, Morgan; Weisz, Daniel R; Williams, Benjamin F; Beerman, Lori C; Gouliermis, Dimitrios A; Sarajedini, Ata

    2015-01-01

    We construct a stellar cluster catalog for the Panchromatic Hubble Andromeda Treasury (PHAT) survey using image classifications collected from the Andromeda Project citizen science website. We identify 2,753 clusters and 2,270 background galaxies within ~0.5 deg$^2$ of PHAT imaging searched, or ~400 kpc$^2$ in deprojected area at the distance of the Andromeda galaxy (M31). These identifications result from 1.82 million classifications of ~20,000 individual images (totaling ~7 gigapixels) by tens of thousands of volunteers. We show that our crowd-sourced approach, which collects >80 classifications per image, provides a robust, repeatable method of cluster identification. The high spatial resolution Hubble Space Telescope images resolve individual stars in each cluster and are instrumental in the factor of ~6 increase in the number of clusters known within the survey footprint. We measure integrated photometry in six filter passbands, ranging from the near-UV to the near-IR. PHAT clusters span a range of ~8 ma...

  5. AGN Physics from QSO Clustering

    CERN Document Server

    Croom, S; Shanks, T; Outram, P J; Smith, R; Miller, L; Loaring, N; Kenyon, S; Couch, W; Croom, Scott; Boyle, Brian; Shanks, Tom; Outram, Phil; Smith, Robert; Miller, Lance; Loaring, Nicola; Kenyon, Suzanne; Couch, Warrick

    2003-01-01

    We review the current status of QSO clustering measurements, particular with respect to their relevance in understanding AGN physics. Measurements based on the 2dF QSO Redshift Survey (2QZ) find a scale length for QSO clustering of s_0=5.76(+0.17-0.27) h-1 Mpc at a redshift ~1.5, very similar to low redshift galaxies. There is no evidence of evolution in the clustering of QSOs from z~0.5 to z~2.2. This lack of evolution and low clustering amplitude suggests a short life time for AGN activity of the order ~10^6-10^7 years. Large surveys such at the 2QZ and SDSS also allow the the study of QSO environments in 3D for the first time (at least at low redshift), early results from this work seem to show no difference between the environments of QSOs and normal galaxies. Future studies e.g. measuring clustering as a function of black hole mass, and deep QSO surveys should provide further insight into the formation and evolution of AGN.

  6. Dissolution of Globular Clusters

    OpenAIRE

    Baumgardt, Holger

    2006-01-01

    Globular clusters are among the oldest objects in galaxies, and understanding the details of their formation and evolution can bring valuable insight into the early history of galaxies. This review summarises the current knowledge about the dissolution of star clusters and discusses the implications of star cluster dissolution for the evolution of the mass function of star cluster systems in galaxies.

  7. Structures of Mn clusters

    Indian Academy of Sciences (India)

    Tina M Briere; Marcel H F Sluiter; Vijay Kumar; Yoshiyuki Kawazoe

    2003-01-01

    The geometries of several Mn clusters in the size range Mn13–Mn23 are studied via the generalized gradient approximation to density functional theory. For the 13- and 19-atom clusters, the icosahedral structures are found to be most stable, while for the 15-atom cluster, the bcc structure is more favoured. The clusters show ferrimagnetic spin configurations.

  8. Multilevel Techniques for the Clustering Problem

    Directory of Open Access Journals (Sweden)

    Noureddine Bouhmala

    2014-02-01

    Full Text Available Data Mining is concerned with the discovery of int eresting patterns and knowledge in data repositories. Cluster Analysis which belongs to the core methods of data mining is the process of discovering homogeneous groups called clusters. Given a data-set and some measure of similarity between data objects, the goal in most c lustering algorithms is maximizing both the homogeneity within each cluster and the heterogene ity between different clusters. In this work, two multilevel algorithms for the clustering problem are introduced. The multilevel paradigm suggests looking at the clustering proble m as a hierarchical optimization process going through different levels evolving from a coar se grain to fine grain strategy. The clustering problem is solved by first reducing the problem level by level to a coarser problem where an initial clustering is computed. The clustering of the coarser problem is mapped back level-by- level to obtain a better clustering of the original problem by refining the intermediate different clustering obtained at various levels. A benchmark using a number of data sets collected from a variety of domains is used to compare the effective ness of the hierarchical approach against its single-level counterpart.

  9. Contextualizing the Cluster

    DEFF Research Database (Denmark)

    Giacomin, Valeria

    This dissertation examines the case of the palm oil cluster in Malaysia and Indonesia, today one of the largest agricultural clusters in the world. My analysis focuses on the evolution of the cluster from the 1880s to the 1970s in order to understand how it helped these two countries to integrate......-researched topic in the cluster literature – the emergence of clusters, their governance and institutional change, and competition between rival cluster locations – through the case of the Southeast Asian palm oil cluster....

  10. Preparation of Co-axis TiO_2-Pt Nanotubes and Research on the Photocatalysis%TiO_2-Pt同轴纳米管制备及光催化性能研究

    Institute of Scientific and Technical Information of China (English)

    孙勇飞; 施德俊; 王小希; 殷好勇

    2012-01-01

    该文利用毛细管作用和还原气氛处理相结合的方法,以TiO2纳米颗粒为原料制备了贵金属Pt纳米颗粒填充的TiO2-Pt同轴纳米管复合材料,并对其形貌和结构进行了表征。然后在紫外光源的照射下对甲基橙进行光催化降解实验,光催化实验结果表明该复合纳米材料具有比TiO2纳米颗粒更高的光催化降解甲基橙的催化活性。%The Co-axis TiO2-Pt nanotubes were prepared by inserting Pt nanoparticles into H2Ti3O7 nanotubes using capillary action and subsequently annealing at reduction atmosphere.The morphologies and structure were characterized by TEM,XRD,and EDX.The photocatalysis results show that the as prepared nanotubes have higher photocatalytic activities in degradation of methyl orange than that of TiO2 nanoparticles.

  11. Fabrication of MgAl2Si2O8 : M0.01 (M = Ni2+, Cu2+, Pd2+, Pt2+ and Ru3+): catalytic effects for the reduction of 2- or 4-nitroanilines in water

    Indian Academy of Sciences (India)

    Serkan Dayan; Sevgi Öztürk; Nilgün Kayaci; Nilgun Kalaycioglu Ozpozan; Esra Öztürk

    2015-10-01

    Five new MgAl2Si2O8 : M0.01 (M = Ni2+, Cu2+, Pd2+, Pt2+ and Ru3+) materials were developed for the reduction of nitroarenes as catalysts by conventional solid state reaction at 1300°C. The prepared materials were characterized by thermal analysis, Fourier transform infrared spectroscopy, X-ray powder diffraction analysis, scanning electron microscopy, energy-dispersive X-ray analysis and nitrogen adsorption–desorption analysis. The catalytic activities of the prepared catalysts were tested in the reduction of 2- or 4-nitroanilines in aqueous media at ambient temperature in the presence of NaBH4 by UV–vis spectrophotometer. Furthermore, the MgAl2Si2O8 : M0.01 catalysts can be recovered by filtration and reused for five cycles for the reduction of 2-nitroaniline. These results show that the MgAl2Si2O8 : M0.01 catalysts can be used in practical applications in the reduction of nitroanilines.

  12. Factored Translation with Unsupervised Word Clusters

    DEFF Research Database (Denmark)

    Rishøj, Christian; Søgaard, Anders

    2011-01-01

    Unsupervised word clustering algorithms — which form word clusters based on a measure of distributional similarity — have proven to be useful in providing beneficial features for various natural language processing tasks involving supervised learning. This work explores the utility of such word c....... While such an “oracle” method is not identified, evaluations indicate that unsupervised word cluster are most beneficial in sentences without unknown words....

  13. Vacancy-indium clusters in implanted germanium

    KAUST Repository

    Chroneos, Alexander I.

    2010-04-01

    Secondary ion mass spectroscopy measurements of heavily indium doped germanium samples revealed that a significant proportion of the indium dose is immobile. Using electronic structure calculations we address the possibility of indium clustering with point defects by predicting the stability of indium-vacancy clusters, InnVm. We find that the formation of large clusters is energetically favorable, which can explain the immobility of the indium ions. © 2010 Elsevier B.V. All rights reserved.

  14. Clustering in analytical chemistry.

    Science.gov (United States)

    Drab, Klaudia; Daszykowski, Michal

    2014-01-01

    Data clustering plays an important role in the exploratory analysis of analytical data, and the use of clustering methods has been acknowledged in different fields of science. In this paper, principles of data clustering are presented with a direct focus on clustering of analytical data. The role of the clustering process in the analytical workflow is underlined, and its potential impact on the analytical workflow is emphasized.

  15. Voting-based consensus clustering for combining multiple clusterings of chemical structures

    Directory of Open Access Journals (Sweden)

    Saeed Faisal

    2012-12-01

    Full Text Available Abstract Background Although many consensus clustering methods have been successfully used for combining multiple classifiers in many areas such as machine learning, applied statistics, pattern recognition and bioinformatics, few consensus clustering methods have been applied for combining multiple clusterings of chemical structures. It is known that any individual clustering method will not always give the best results for all types of applications. So, in this paper, three voting and graph-based consensus clusterings were used for combining multiple clusterings of chemical structures to enhance the ability of separating biologically active molecules from inactive ones in each cluster. Results The cumulative voting-based aggregation algorithm (CVAA, cluster-based similarity partitioning algorithm (CSPA and hyper-graph partitioning algorithm (HGPA were examined. The F-measure and Quality Partition Index method (QPI were used to evaluate the clusterings and the results were compared to the Ward’s clustering method. The MDL Drug Data Report (MDDR dataset was used for experiments and was represented by two 2D fingerprints, ALOGP and ECFP_4. The performance of voting-based consensus clustering method outperformed the Ward’s method using F-measure and QPI method for both ALOGP and ECFP_4 fingerprints, while the graph-based consensus clustering methods outperformed the Ward’s method only for ALOGP using QPI. The Jaccard and Euclidean distance measures were the methods of choice to generate the ensembles, which give the highest values for both criteria. Conclusions The results of the experiments show that consensus clustering methods can improve the effectiveness of chemical structures clusterings. The cumulative voting-based aggregation algorithm (CVAA was the method of choice among consensus clustering methods.

  16. IntroductionThe Cluster mission

    Directory of Open Access Journals (Sweden)

    M. Fehringer

    Full Text Available The Cluster mission, ESA’s first cornerstone project, together with the SOHO mission, dating back to the first proposals in 1982, was finally launched in the summer of 2000. On 16 July and 9 August, respectively, two Russian Soyuz rockets blasted off from the Russian cosmodrome in Baikonour to deliver two Cluster spacecraft, each into their proper orbit. By the end of August 2000, the four Cluster satellites had reached their final tetrahedral constellation. The commissioning of 44 instruments, both individually and as an ensemble of complementary tools, was completed five months later to ensure the optimal use of their combined observational potential. On 1 February 2001, the mission was declared operational. The main goal of the Cluster mission is to study the small-scale plasma structures in three dimensions in key plasma regions, such as the solar wind, bow shock, magnetopause, polar cusps, magnetotail and the auroral zones. With its unique capabilities of three-dimensional spatial resolution, Cluster plays a major role in the International Solar Terrestrial Program (ISTP, where Cluster and the Solar and Heliospheric Observatory (SOHO are the European contributions. Cluster’s payload consists of state-of-the-art plasma instrumentation to measure electric and magnetic fields from the quasi-static up to high frequencies, and electron and ion distribution functions from energies of nearly 0 eV to a few MeV. The science operations are coordinated by the Joint Science Operations Centre (JSOC, at the Rutherford Appleton Laboratory (UK, and implemented by the European Space Operations Centre (ESOC, in Darmstadt, Germany. A network of eight national data centres has been set up for raw data processing, for the production of physical parameters, and their distribution to end users all over the world. The latest information on the Cluster mission can be found at http://sci.esa.int/cluster/.

  17. Testing chameleon gravity with the Coma cluster

    CERN Document Server

    Terukina, Ayumu; Yamamoto, Kazuhiro; Bacon, David; Koyama, Kazuya; Nichol, Robert C

    2013-01-01

    We propose a novel method to test the gravitational interactions in the outskirts of galaxy clusters. When gravity is modified, this is typically accompanied by an introduction of an additional scalar degree of freedom, which mediates an attractive fifth force. The presence of an extra gravitational coupling, however, is tightly constrained by local measurements. In chameleon modifications of gravity, local tests can be evaded by employing a screening mechanism that suppresses the fifth force in dense environments. While the chameleon field may be screened in the interior of the cluster, its outer region can still be affected by the extra force, introducing a deviation between the hydrostatic and lensing mass of the cluster. Thus, the chameleon modification can be tested by combining the gas and lensing measurements of the cluster. We demonstrate the operability of our method with the Coma cluster, for which both a lensing measurement and gas observations from the X-ray surface brightness, the X-ray temperatu...

  18. Tracing cosmic evolution with clusters of galaxies

    CERN Document Server

    Voit, G M

    2004-01-01

    The most successful cosmological models to date envision structure formation as a hierarchical process in which gravity is constantly drawing lumps of matter together to form increasingly larger structures. Clusters of galaxies currently sit atop this hierarchy as the largest objects that have had time to collapse under the influence of their own gravity. Thus, their appearance on the cosmic scene is also relatively recent. Two features of clusters make them uniquely useful tracers of cosmic evolution. First, clusters are the biggest things whose masses we can reliably measure because they are the largest objects to have undergone gravitational relaxation and entered into virial equilibrium. Mass measurements of nearby clusters can therefore be used to determine the amount of structure in the universe on scales of 10^14 to 10^15 solar masses, and comparisons of the present-day cluster mass distribution with the mass distribution at earlier times can be used to measure the rate of structure formation, placing ...

  19. Fuzzy clustering with Minkowski distance

    NARCIS (Netherlands)

    P.J.F. Groenen (Patrick); U. Kaymak (Uzay); J.M. van Rosmalen (Joost)

    2006-01-01

    textabstractDistances in the well known fuzzy c-means algorithm of Bezdek (1973) are measured by the squared Euclidean distance. Other distances have been used as well in fuzzy clustering. For example, Jajuga (1991) proposed to use the L_1-distance and Bobrowski and Bezdek (1991) also used the L_inf

  20. Mature clustered, regularly interspaced, short palindromic repeats RNA (crRNA) length is measured by a ruler mechanism anchored at the precursor processing site.

    Science.gov (United States)

    Hatoum-Aslan, Asma; Maniv, Inbal; Marraffini, Luciano A

    2011-12-27

    Precise RNA processing is fundamental to all small RNA-mediated interference pathways. In prokaryotes, clustered, regularly interspaced, short palindromic repeats (CRISPR) loci encode small CRISPR RNAs (crRNAs) that protect against invasive genetic elements by antisense targeting. CRISPR loci are transcribed as a long precursor that is cleaved within repeat sequences by CRISPR-associated (Cas) proteins. In many organisms, this primary processing generates crRNA intermediates that are subject to additional nucleolytic trimming to render mature crRNAs of specific lengths. The molecular mechanisms underlying this maturation event remain poorly understood. Here, we defined the genetic requirements for crRNA primary processing and maturation in Staphylococcus epidermidis. We show that changes in the position of the primary processing site result in extended or diminished maturation to generate mature crRNAs of constant length. These results indicate that crRNA maturation occurs by a ruler mechanism anchored at the primary processing site. We also show that maturation is mediated by specific cas genes distinct from those genes involved in primary processing, showing that this event is directed by CRISPR/Cas loci.

  1. Application effect of cluster care intervention measures in the patients with ventilator-associated pneumonia%集束化护理措施在呼吸机相关性肺炎患者中应用效果

    Institute of Scientific and Technical Information of China (English)

    刘东岩; 孙铁英

    2013-01-01

    Objective To explore the effect of cluster care intervention of ventilator-associated pneumonia in mechanically ventilated patients. Methods 111 cases of mechanically ventilated patients from August 2010 to August 2012 in Deparment of Respiratory Medicine of Beijing Shijitan hospital as the research object, based on the presence or absence of the implementation of ventilator-associated pneumonia cluster of care measures would be consistent with the study inclusion criteria and exclusion criteria the patients were divided into usual care group and cluster care intervention group, the incidence of mechanical ventilation and ventilator-associated pneumonia, basic care of patients with the pass rate and patient care satisfaction in the two groups were compared. Results The duration of mechanical ventilation and ventilator associated pneumonia incidence of the patients in the cluster care intervention group was significantly lower than that of the usual care group, the difference was significant (P < 0.05), while the cluster pass rate of basic nursing care intervention group patients satisfaction and patient care were significantly higher than that of the usual care group, the difference was significant (P < 0.05). Conclusion Cluster care intervention measures of ventilator-associated pneumonia can significantly reduce the mechanical ventilation time and ventilator-associated pneumonia incidence in the patients with mechanical ventilation, and improve the satisfaction of the basic quality of care and patient care services, and it is worthy of further promotion.%目的 探讨呼吸机相关性肺炎集束化护理措施在机械通气患者中的应用效果.方法 选择2010年8月~2012年8月首都医科大学附属北京世纪坛医院呼吸内科住院治疗的111例机械通气患者为研究对象,根据有无实施呼吸机相关性肺炎集束化护理措施将符合本研究纳入标准和排除标准的患者分为常规护理组和集束化护理干预组,

  2. Size Determination of Argon Clusters from a Rayleigh Scattering Experiment

    Institute of Scientific and Technical Information of China (English)

    LEI An-Le; ZHAI Hua-Jin; LIU Bing-Chen; LI Zhong; NI Guo-Yuan; XU Zhi-Zhan

    2000-01-01

    Argon clusters are produced in the process of adiabatic expansion of a high backing pressure gas into vacuum through a nozzle. The cluster size is determined by a Rayleigh scattering measurement. The scattered signal measured is proportional to the 2.78th power of gas stagnation pressure. The average cluster sizes vary from 100 to more than 12000 atoms/cluster with the argon gas backing pressures ranging between 3 to 45 atm.

  3. The Preventive Effect of Neonatal Ventilator Associated Pneumonia Cluster Nursing Intervention Measures%集束化护理干预措施预防新生儿呼吸机相关肺炎的效果

    Institute of Scientific and Technical Information of China (English)

    李慧

    2016-01-01

    Objective To investigate the preventive effect of neonatal ventilator associated pneumonia cluster nursing intervention measures. Methods Admitted to the extraction of 80 cases of ventilator associated pneumonia in children were analyzed,were random-ly divided into two groups, patients in control group received routine nursing care;observation group with cluster nursing intervention, clinical effects were compared between the two groups. Results By comparing the observed group was signiifcantly better than the control group,signiifcant differences, with statistical signiifcance.Conclusion Neonatal ventilator-associated pneumonia in implement-ing cluster nursing intervention,can effectively improve the therapeutic effect, reduce VAP incidence, reduce hospitalization time and for clinical promotion and application.%目的:探讨集束化护理干预措施预防新生儿呼吸机相关肺炎的效果。方法抽取的收治的80例呼吸机相关肺炎患儿进行分析,随机分组,对照组实施常规护理;观察组采用集束化护理干预,对比两组的临床效果。结果通过对比,观察组明显优于对照组,差异显著,具有统计学意义。结论针对新生儿呼吸机相关肺炎患儿实施集束化护理干预,能够有效提高治疗效果,降低VAP的发生率,减少住院时间,适合临床的推广与运用。

  4. The Clustering of the SDSS DR7 Main Galaxy Sample I: A 4 per cent Distance Measure at z=0.15

    CERN Document Server

    Ross, Ashley J; Howlett, Cullan; Percival, Will J; Burden, Angela; Manera, Marc

    2014-01-01

    We create a sample of spectroscopically identified galaxies with $z < 0.2$ from the Sloan Digital Sky Survey (SDSS) Data Release 7, covering 6813 deg$^2$. Galaxies are chosen to sample the highest mass haloes, with an effective bias of 1.5, allowing us to construct 1000 mock galaxy catalogs (described in Paper II), which we use to estimate statistical errors and test our methods. We use an estimate of the gravitational potential to "reconstruct" the linear density fluctuations, enhancing the Baryon Acoustic Oscillation (BAO) signal in the measured correlation function and power spectrum. Fitting to these measurements, we determine $D_{V}(z_{\\rm eff}=0.15) = (664\\pm25)(r_d/r_{d,{\\rm fid}})$ Mpc; this is a better than 4 per cent distance measurement. This "fills the gap" in BAO distance ladder between previously measured local and higher redshift measurements, and affords significant improvement in constraining the properties of dark energy. Combining our measurement with other BAO measurements from BOSS and...

  5. What Makes Clusters Decline?

    DEFF Research Database (Denmark)

    Østergaard, Christian Richter; Park, Eun Kyung

    2015-01-01

    Most studies on regional clusters focus on identifying factors and processes that make clusters grow. However, sometimes technologies and market conditions suddenly shift, and clusters decline. This paper analyses the process of decline of the wireless communication cluster in Denmark....... The longitudinal study on the high-tech cluster reveals that technological lock-in and exit of key firms have contributed to decline. Entrepreneurship has a positive effect on the cluster’s adaptive capabilities, while multinational companies have contradicting effects by bringing in new resources to the cluster...

  6. Comparison of Hierarchical Agglomerative Algorithms for Clustering Medical Documents

    Directory of Open Access Journals (Sweden)

    Rafa E. Al-Qutaish

    2012-06-01

    Full Text Available Extensive amount of data stored in medical documents require developing methods that help users to find what they are looking for effectively by organizing large amounts of information into a small number of meaningful clusters. The produced clusters contain groups of objects which are more similar to each other than to the members of any other group. Thus, the aim of high-quality document clustering algorithms is to determine a set of clusters in which the inter-cluster similarity is minimized and intra-cluster similarity is maximized. The most important feature in many clustering algorithms is treating the clustering problem as an optimization process, that is, maximizing or minimizing a particular clustering criterion function defined over the whole clustering solution. The only real difference between agglomerative algorithms is how they choose which clusters to merge. The main purpose of this paper is to compare different agglomerative algorithms based on the evaluation of the clusters quality produced by different hierarchical agglomerative clustering algorithms using different criterion functions for the problem of clustering medical documents. Our experimental results showed that the agglomerative algorithm that uses I1 as its criterion function for choosing which clusters to merge produced better clusters quality than the other criterion functions in term of entropy and purity as external measures.

  7. Spectral clustering based on matrix perturbation theory

    Institute of Scientific and Technical Information of China (English)

    TIAN Zheng; LI XiaoBin; JU YanWei

    2007-01-01

    This paper exposes some intrinsic characteristics of the spectral clustering method by using the tools from the matrix perturbation theory. We construct a weight matrix of a graph and study its eigenvalues and eigenvectors. It shows that the number of clusters is equal to the number of eigenvalues that are larger than 1, and the number of points in each of the clusters can be approximated by the associated eigenvalue. It also shows that the eigenvector of the weight matrix can be used directly to perform clustering; that is, the directional angle between the two-row vectors of the matrix derived from the eigenvectors is a suitable distance measure for clustering. As a result, an unsupervised spectral clustering algorithm based on weight matrix (USCAWM) is developed. The experimental results on a number of artificial and real-world data sets show the correctness of the theoretical analysis.

  8. Data clustering theory, algorithms, and applications

    CERN Document Server

    Gan, Guojun; Wu, Jianhong

    2007-01-01

    Cluster analysis is an unsupervised process that divides a set of objects into homogeneous groups. This book starts with basic information on cluster analysis, including the classification of data and the corresponding similarity measures, followed by the presentation of over 50 clustering algorithms in groups according to some specific baseline methodologies such as hierarchical, center-based, and search-based methods. As a result, readers and users can easily identify an appropriate algorithm for their applications and compare novel ideas with existing results. The book also provides examples of clustering applications to illustrate the advantages and shortcomings of different clustering architectures and algorithms. Application areas include pattern recognition, artificial intelligence, information technology, image processing, biology, psychology, and marketing. Readers also learn how to perform cluster analysis with the C/C++ and MATLAB® programming languages.

  9. Quantum information processing with noisy cluster states

    CERN Document Server

    Tame, M S; Kim, M S; Vedral, V

    2005-01-01

    We provide an analysis of basic quantum information processing protocols under the effect of intrinsic non-idealities in cluster states. These non-idealities are based on the introduction of randomness in the entangling steps that create the cluster state and are motivated by the unavoidable imperfections faced in creating entanglement using condensed-matter systems. Aided by the use of an alternative and very efficient method to construct cluster state configurations, which relies on the concatenation of fundamental cluster structures, we address quantum state transfer and various fundamental gate simulations through noisy cluster states. We find that a winning strategy to limit the effects of noise, is the management of small clusters processed via just a few measurements. Our study also reinforces recent ideas related to the optical implementation of a one-way quantum computer.

  10. Combining data visualization and statistical approaches for interpreting measurements and meta-data: Integrating heatmaps, variable clustering, and mixed regression models

    Science.gov (United States)

    The advent of new higher throughput analytical instrumentation has put a strain on interpreting and explaining the results from complex studies. Contemporary human, environmental, and biomonitoring data sets are comprised of tens or hundreds of analytes, multiple repeat measures...

  11. Properties of Star Clusters - II: Scale Height Evolution of Clusters

    CERN Document Server

    Buckner, Anne S M

    2014-01-01

    Until now it has been impossible to observationally measure how star cluster scale height evolves beyond 1Gyr as only small samples have been available. Here we establish a novel method to determine the scale height of a cluster sample using modelled distributions and Kolmogorov-Smirnov tests. This allows us to determine the scale height with a 25% accuracy for samples of 38 clusters or more. We apply our method to investigate the temporal evolution of cluster scale height, using homogeneously selected sub-samples of Kharchenko et al. (MWSC), Dias et al. (DAML02), WEBDA, and Froebrich et al. (FSR). We identify a linear relationship between scale height and log(age/yr) of clusters, considerably different from field stars. The scale height increases from about 40pc at 1Myr to 75pc at 1Gyr, most likely due to internal evolution and external scattering events. After 1Gyr, there is a marked change of the behaviour, with the scale height linearly increasing with log(age/yr) to about 550pc at 3.5Gyr. The most likely...

  12. The Cluster Substructure - Alignment Connection

    OpenAIRE

    Plionis, Manolis

    2001-01-01

    Using the APM cluster data we investigate whether the dynamical status of clusters is related to the large-scale structure of the Universe. We find that cluster substructure is strongly correlated with the tendency of clusters to be aligned with their nearest neighbour and in general with the nearby clusters that belong to the same supercluster. Furthermore, dynamically young clusters are more clustered than the overall cluster population. These are strong indications that cluster develop in ...

  13. Nuclear Clusters in Astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Kubono, S.; Binh, Dam N.; Hayakawa, S.; Hashimoto, H.; Kahl, D.; Wakabayashi, Y.; Yamaguchi, H. [Center for Nuclear Study (CNS), University of Tokyo, Wako Branch at RIKEN 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Teranishi, T. [Department of Physics, Kyushu University, Fukuoka, 812-8581 (Japan); Iwasa, N. [Department of Physics, Tohoku University, Sendai, 980-8578 (Japan); Komatsubara, T. [Department of Physics, Tsukuba University, Ibaraki, 305-8571 (Japan); Kato, S. [Department of Physics, Yamagata University, Yamagata, 990-8560 (Japan); Khiem, Le H. [Institute of Physics, Vietnam Academy for Science and Technology, Hanoi (Viet Nam)

    2010-03-01

    The role of nuclear clustering is discussed for nucleosynthesis in stellar evolution with Cluster Nucleosynthesis Diagram (CND) proposed before. Special emphasis is placed on alpha-induced stellar reactions together with molecular states for O and C burning.

  14. A brief conceptual tutorial of multilevel analysis in social epidemiology: using measures of clustering in multilevel logistic regression to investigate contextual phenomena

    DEFF Research Database (Denmark)

    Merlo, J; Chaix, B; Ohlsson, H;

    2006-01-01

    STUDY OBJECTIVE: In social epidemiology, it is easy to compute and interpret measures of variation in multilevel linear regression, but technical difficulties exist in the case of logistic regression. The aim of this study was to present measures of variation appropriate for the logistic case...... in a didactic rather than a mathematical way. Design and PARTICIPANTS: Data were used from the health survey conducted in 2000 in the county of Scania, Sweden, that comprised 10 723 persons aged 18-80 years living in 60 areas. Conducting multilevel logistic regression different techniques were applied...... propensity areas with the area educational level. The sorting out index was equal to 82%. CONCLUSION: Measures of variation in logistic regression should be promoted in social epidemiological and public health research as efficient means of quantifying the importance of the context of residence...

  15. A brief conceptual tutorial of multilevel analysis in social epidemiology: using measures of clustering in multilevel logistic regression to investigate contextual phenomena

    DEFF Research Database (Denmark)

    Merlo, J; Chaix, B; Ohlsson, H;

    2006-01-01

    in a didactic rather than a mathematical way. Design and PARTICIPANTS: Data were used from the health survey conducted in 2000 in the county of Scania, Sweden, that comprised 10 723 persons aged 18-80 years living in 60 areas. Conducting multilevel logistic regression different techniques were applied...... propensity areas with the area educational level. The sorting out index was equal to 82%. CONCLUSION: Measures of variation in logistic regression should be promoted in social epidemiological and public health research as efficient means of quantifying the importance of the context of residence......STUDY OBJECTIVE: In social epidemiology, it is easy to compute and interpret measures of variation in multilevel linear regression, but technical difficulties exist in the case of logistic regression. The aim of this study was to present measures of variation appropriate for the logistic case...

  16. CRITICAL CONFIGURATION AND PHYSICS MEASUREMENTS FOR BERYLLIUM REFLECTED ASSEMBLIES OF U(93.15)O2 FUEL RODS (1.506-CM PITCH AND 7-TUBE CLUSTERS)

    Energy Technology Data Exchange (ETDEWEB)

    Margaret A. Marshall

    2014-03-01

    Cadmium ratios were measured with enriched uranium metal foils at various locations in the assembly with the fuel tube at the 1.506-cm spacing. They are described in the following subsections. The experiment configuration was the same as the first critical configuration described in HEU-COMP-FAST-004 (Case 1). The experimenter placed 0.75-cm-diameter × 0.010-cm-thick 93.15%-235U-enriched uranium metal foils with and without 0.051-cm-thick cadmium covers at various locations in the core and top reflector. One part of the cadmium cover was cupshape and contained the uranium foil. The other part was a lid that fit over the exposed side of the foil when it was in the cup shaped section of the cover. As can be seen in the logbook, two runs were required to obtain all the measurements necessary for the cadmium ratio. The bare foil measurements within the top reflector were run first as part of the axial foil activation measurements. The results of this run are used for both the axial activation results and the cadmium ratios. Cadmium covered foils were then placed at the same location through the top reflector in a different run. Three pairs of bare and cadmium covered foils were also placed through the core tank. One pair was placed at the axial center of a fuel tube 11.35 cm from the center of the core. Two pairs of foils were placed on top of fuel tubes 3.02 and 12.06 cm from the center of the core. The activation of the uranium metal foils was measured after removal from the assembly using two lead shielded NaI scintillation detectors as follows. The NaI scintillators were carefully matched and had detection efficiencies for counting delayed-fission-product gamma rays with energies above 250 KeV within 5%. In all foil activation measurements, one foil at a specific location was used as a normalizing foil to remove the effects of the decay of fission products during the counting measurements with the NaI detectors. The normalization foil was placed on one Na

  17. Critical Configuration and Physics Measurements for Beryllium Reflected Assemblies of U(93.15)O₂ Fuel Rods (1.506-cm Pitch and 7-Tube Clusters)

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Margaret A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bess, John D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Briggs, J. Blair [Idaho National Lab. (INL), Idaho Falls, ID (United States); Murphy, Michael F. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mihalczo, John T. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    Cadmium ratios were measured with enriched uranium metal foils at various locations in the assembly with the fuel tube at the 1.506-cm spacing. They are described in the following subsections. The experiment configuration was the same as the first critical configuration described in HEU-COMP-FAST-004 (Case 1). The experimenter placed 0.75-cm-diameter × 0.010-cm-thick 93.15%-235U-enriched uranium metal foils with and without 0.051-cm-thick cadmium covers at various locations in the core and top reflector. One part of the cadmium cover was cupshape and contained the uranium foil. The other part was a lid that fit over the exposed side of the foil when it was in the cup shaped section of the cover. As can be seen in the logbook, two runs were required to obtain all the measurements necessary for the cadmium ratio. The bare foil measurements within the top reflector were run first as part of the axial foil activation measurements. The results of this run are used for both the axial activation results and the cadmium ratios. Cadmium covered foils were then placed at the same location through the top reflector in a different run. Three pairs of bare and cadmium covered foils were also placed through the core tank. One pair was placed at the axial center of a fuel tube 11.35 cm from the center of the core. Two pairs of foils were placed on top of fuel tubes 3.02 and 12.06 cm from the center of the core. The activation of the uranium metal foils was measured after removal from the assembly using two lead shielded NaI scintillation detectors as follows. The NaI scintillators were carefully matched and had detection efficiencies for counting delayed-fission-product gamma rays with energies above 250 KeV within 5%. In all foil activation measurements, one foil at a specific location was used as a normalizing foil to remove the effects of the decay of fission products during the counting measurements with the NaI detectors. The normalization foil was placed on one Na

  18. [Pathophysiology of cluster headache].

    Science.gov (United States)

    Donnet, Anne

    2015-11-01

    The aetiology of cluster headache is partially unknown. Three areas are involved in the pathogenesis of cluster headache: the trigeminal nociceptive pathways, the autonomic system and the hypothalamus. The cluster headache attack involves activation of the trigeminal autonomic reflex. A dysfunction located in posterior hypothalamic gray matter is probably pivotal in the process. There is a probable association between smoke exposure, a possible genetic predisposition and the development of cluster headache.

  19. Photon correlations for colloidal nanocrystals and their clusters

    CERN Document Server

    Shcherbina, O A; Manceau, M; Vezzoli, S; Carbone, L; De Vittorio, M; Bramati, A; Giacobino, E; Chekhova, M V; Leuchs, G

    2013-01-01

    Images of semiconductor `dot in rods' and their small clusters are studied by measuring the second-order correlation function with a spatially resolving ICCD camera. This measurement allows one to distinguish between a single dot and a cluster and, to a certain extent, to estimate the number of dots in a cluster. A more advanced measurement is proposed, based on higher-order correlations, enabling more accurate determination of the number of dots in a small cluster. Nonclassical features of the light emitted by such a cluster are analyzed.

  20. Cluster Physics with Merging Galaxy Clusters

    Directory of Open Access Journals (Sweden)

    Sandor M. Molnar

    2016-02-01

    Full Text Available Collisions between galaxy clusters provide a unique opportunity to study matter in a parameter space which cannot be explored in our laboratories on Earth. In the standard LCDM model, where the total density is dominated by the cosmological constant ($Lambda$ and the matter density by cold dark matter (CDM, structure formation is hierarchical, and clusters grow mostly by merging.Mergers of two massive clusters are the most energetic events in the universe after the Big Bang,hence they provide a unique laboratory to study cluster physics.The two main mass components in clusters behave differently during collisions:the dark matter is nearly collisionless, responding only to gravity, while the gas is subject to pressure forces and dissipation, and shocks and turbulenceare developed during collisions. In the present contribution we review the different methods used to derive the physical properties of merging clusters. Different physical processes leave their signatures on different wavelengths, thusour review is based on a multifrequency analysis. In principle, the best way to analyze multifrequency observations of merging clustersis to model them using N-body/HYDRO numerical simulations. We discuss the results of such detailed analyses.New high spatial and spectral resolution ground and space based telescopeswill come online in the near future. Motivated by these new opportunities,we briefly discuss methods which will be feasible in the near future in studying merging clusters.

  1. The Durban Auto Cluster

    DEFF Research Database (Denmark)

    Lorentzen, Jochen; Robbins, Glen; Barnes, Justin

    2004-01-01

    The paper describes the formation of the Durban Auto Cluster in the context of trade liberalization. It argues that the improvement of operational competitiveness of firms in the cluster is prominently due to joint action. It tests this proposition by comparing the gains from cluster activities i...

  2. Intra Cluster Globular Clusters around NGC 1399 in Fornax?

    CERN Document Server

    Schuberth, Y; Bassino, L; Hilker, M

    2007-01-01

    We investigate whether the globular clusters (GCs) in the recently published sample of GCs in the Fornax cluster by Bergond and coworkers are indeed intra-cluster objects. We combine the catalogue of radial velocity measurements by Bergond et al. with our CTIO MOSAIC photometry in the Washington system and analyse the relation of metal-poor and metal-rich GCs with their host galaxies. The metal-rich GCs appear to be kinematically associated with their respective host galaxies. The vast majority of the metal-poor GCs found in between the galaxies of the Fornax cluster have velocities which are consistent with them being members of the very extended NGC 1399 GC system. We find that when the sample is restricted to the most accurate velocity measurements, the GC velocity dispersion profile can be described with a mass model derived for the NGC 1399 GC system within 80 kpc. We identify one ``vagrant'' GC whose radial velocity suggests that it is not bound to any galaxy unless its orbit has a very large apogalacti...

  3. MnS clusters in natural zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Iacomi, Felicia; Vasile, Aurelia; Polychroniadis, E.K

    2003-08-15

    FTIR, ESR, optical absorption, photoconductivity, and luminescence measurements are used to evidence the nature of MnS clusters, synthesized by treating the Mn{sup 2+} forms of natural zeolites with Na{sub 2}S.

  4. Measuring $\

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Jessica Sarah [Univ. of Cambridge (United Kingdom)

    2011-01-01

    The MINOS Experiment consists of two steel-scintillator calorimeters, sampling the long baseline NuMI muon neutrino beam. It was designed to make a precise measurement of the ‘atmospheric’ neutrino mixing parameters, Δm2 atm. and sin2 (2 atm.). The Near Detector measures the initial spectrum of the neutrino beam 1km from the production target, and the Far Detector, at a distance of 735 km, measures the impact of oscillations in the neutrino energy spectrum. Work performed to validate the quality of the data collected by the Near Detector is presented as part of this thesis. This thesis primarily details the results of a vμ disappearance analysis, and presents a new sophisticated fitting software framework, which employs a maximum likelihood method to extract the best fit oscillation parameters. The software is entirely decoupled from the extrapolation procedure between the detectors, and is capable of fitting multiple event samples (defined by the selections applied) in parallel, and any combination of energy dependent and independent sources of systematic error. Two techniques to improve the sensitivity of the oscillation measurement were also developed. The inclusion of information on the energy resolution of the neutrino events results in a significant improvement in the allowed region for the oscillation parameters. The degree to which sin2 (2θ )= 1.0 could be disfavoured with the exposure of the current dataset if the true mixing angle was non-maximal, was also investigated, with an improved neutrino energy reconstruction for very low energy events. The best fit oscillation parameters, obtained by the fitting software and incorporating resolution information were: | Δm2| = 2.32+0.12 -0.08×10-3 eV2 and sin2 (2θ ) > 0.90(90% C.L.). The analysis provides the current world best measurement of the atmospheric neutrino mass

  5. Spectroscopy of clusters in the ESO Distant Cluster Survey (EDisCS)

    CERN Document Server

    Halliday, C; Poirier, S; Poggianti, B M; Jablonka, P; Aragón-Salamanca, A; Saglia, R P; De Lucia, G; Pellò, R; Simard, L; Clowe, D I; Rudnick, G; Dalcanton, J J; White, S D M; Zaritsky, D

    2004-01-01

    We present spectroscopic observations of galaxies in 4 clusters at z = 0.7-0.8 and in one cluster at z~0.5 obtained with the FORS2 spectrograph on the VLT as part of the ESO Distant Cluster Survey (EDisCS), a photometric and spectroscopic survey of 20 intermediate to high redshift clusters. We describe our target selection, mask design, observation and data reduction procedures, using these first 5 clusters to demonstrate how our strategies maximise the number of cluster members for which we obtain spectroscopy. We present catalogues containing positions, I-band magnitudes and spectroscopic redshifts for galaxies in the fields of our 5 clusters. These contain 236 cluster members, with the number of members per cluster ranging from 30 to 67. Our spectroscopic success rate, i.e. the fraction of spectroscopic targets which are cluster members, averages 50% and ranges from 30% to 75%. We use a robust biweight estimator to measure cluster velocity dispersions from our spectroscopic redshift samples. We also make a...

  6. Management of cluster headache

    DEFF Research Database (Denmark)

    Tfelt-Hansen, Peer C; Jensen, Rigmor H

    2012-01-01

    and agitation. Patients may have up to eight attacks per day. Episodic cluster headache (ECH) occurs in clusters of weeks to months duration, whereas chronic cluster headache (CCH) attacks occur for more than 1 year without remissions. Management of cluster headache is divided into acute attack treatment....... In drug-resistant CCH, neuromodulation with either occipital nerve stimulation or deep brain stimulation of the hypothalamus is an alternative treatment strategy. For most cluster headache patients there are fairly good treatment options both for acute attacks and for prophylaxis. The big problem...

  7. Cluster Decline and Resilience

    DEFF Research Database (Denmark)

    Østergaard, Christian Richter; Park, Eun Kyung

    -2011. Our longitudinal study reveals that technological lock-in and exit of key firms have contributed to impairment of the cluster’s resilience in adapting to disruptions. Entrepreneurship has a positive effect on cluster resilience, while multinational companies have contradicting effects by bringing......Most studies on regional clusters focus on identifying factors and processes that make clusters grow. However, sometimes technologies and market conditions suddenly shift, and clusters decline. This paper analyses the process of decline of the wireless communication cluster in Denmark, 1963...

  8. Water cluster fragmentation probed by pickup experiments

    Science.gov (United States)

    Huang, Chuanfu; Kresin, Vitaly V.; Pysanenko, Andriy; Fárník, Michal

    2016-09-01

    Electron ionization is a common tool for the mass spectrometry of atomic and molecular clusters. Any cluster can be ionized efficiently by sufficiently energetic electrons, but concomitant fragmentation can seriously obstruct the goal of size-resolved detection. We present a new general method to assess the original neutral population of the cluster beam. Clusters undergo a sticking collision with a molecule from a crossed beam, and the velocities of neat and doped cluster ion peaks are measured and compared. By making use of longitudinal momentum conservation, one can reconstruct the sizes of the neutral precursors. Here this method is applied to H2O and D2O clusters in the detected ion size range of 3-10. It is found that water clusters do fragment significantly upon electron impact: the deduced neutral precursor size is ˜3-5 times larger than the observed cluster ions. This conclusion agrees with beam size characterization by another experimental technique: photoionization after Na-doping. Abundant post-ionization fragmentation of water clusters must therefore be an important factor in the interpretation of experimental data; interestingly, there is at present no detailed microscopic understanding of the underlying fragmentation dynamics.

  9. Cluster Analysis of the Malaysian Hipposideros

    Science.gov (United States)

    Sazali, Siti Nurlydia; Laman, Charlie J.; Abdullah, M. T.

    2008-01-01

    A preliminary study on the morphometric variations among species in the genus Hipposideros was conducted using voucher specimens from the Universiti Malaysia Sarawak (UNIMAS) Zoological Museum and the Department of Wildlife and National Park (DWNP) Kuala Lumpur. A total of 24 individuals from six species of this genus were morphologically studied where all related measurements of body, skull and dental were measured and recorded. The statistical data subjected to the cluster analysis shows that the genus Hipposideros is divided into two major clusters where each species was clearly separated. The cluster analysis among Hipposideros species is useful for aiding in species identification.

  10. Experimental and theoretical studies of interactions between Si{7} clusters

    Science.gov (United States)

    Gynz-Rekowski, F. V.; Quester, W.; Dietsche, R.; Lim, D. C.; Bertram, N.; Fischer, T.; Ganteför, G.; Schach, M.; Nielaba, P.; Kim, Y. D.

    2007-12-01

    The possibility of using magic Si7 clusters to form a cluster material was studied experimentally and theoretically. In experiments Si7 clusters were deposited on carbon surfaces, and the electronic structure and chemical properties of the deposited clusters were measured using X-ray photoelectron spectroscopy (XPS). A non bulk-like electronic structure of Si7 was found in the Si 2p core level spectra. Si7 is suggested to form a more stable structure than the non-magic Si8 cluster and Si atoms upon deposition on carbon surfaces. Theoretically it was possible to study the interaction between the clusters without the effect of a surface. Density functional theory (DFT) calculations of potential curves of two free Si7 clusters approaching each other in various orientations hint at the formation of cluster materials rather than the fusion of clusters forming bulk-like structures.

  11. The IMF of Globular Clusters

    Science.gov (United States)

    De Marchi, G.; Paresce, F.

    1999-12-01

    Accurate luminosity functions (LF) for a dozen globular clusters have now been measured at or just beyond their half-light radius using HST. They span almost the entire cluster main sequence below 0.75 MO. All these clusters exhibit LF that rise continuously from an absolute I magnitude MI 6 to a peak at MI 8.5-9 and then drop with increasing MI. Transformation of the LF into mass functions (MF) by means of the most recent mass luminosity relations that are consistent with all presently available data on the physical properties of low mass, low metallicity stars shows that all the LF observed so far can be obtained from MF having the shape of a log-normal distribution with characteristic mass mc=0.33 +/- 0.03 MO and standard deviation sigma =1.81 +/- 0.19. In particular, the LF of the four clusters in the sample that extend well beyond the peak luminosity down to close to the Hydrogen burning limit (NGC6341, NGC6397, NGC6752, and NGC6809) can only be reproduced by such distributions and not by a single power-law in the 0.1 - 0.6 MO range. After correction for the effects of mass segregation, the variation of the ratio of the number of higher to lower mass stars with cluster mass or any simple orbital parameter or the expected time to disruption recently computed for these clusters shows no statistically significant trend over a range of this last parameter of more than a factor of 100. We conclude that the global MF of these clusters have not been measurably modified by evaporation and tidal interactions with the Galaxy and, thus, should reflect the initial distribution of stellar masses. Since the log-normal function that we find is also very similar to the one obtained independently for much younger clusters and to the form expected theoretically, the implication seems to be unavoidable that it represents the true stellar IMF for this type of stars in this mass range.

  12. Clustering high dimensional data

    DEFF Research Database (Denmark)

    Assent, Ira

    2012-01-01

    to render traditional clustering algorithms ineffective. The curse of dimensionality, among other effects, means that with increasing number of dimensions, a loss of meaningful differentiation between similar and dissimilar objects is observed. As high-dimensional objects appear almost alike, new approaches...... for clustering are required. Consequently, recent research has focused on developing techniques and clustering algorithms specifically for high-dimensional data. Still, open research issues remain. Clustering is a data mining task devoted to the automatic grouping of data based on mutual similarity. Each cluster...... that provide different cluster models and different algorithmic approaches for cluster detection. Common to all approaches is the fact that they require some underlying assessment of similarity between data objects. In this article, we provide an overview of the effects of high-dimensional spaces...

  13. Clusters in nuclei

    CERN Document Server

    Beck, Christian

    Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is today one of those domains of heavy-ion nuclear physics that faces the greatest challenges, yet also contains the greatest opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physicists has decided to collaborate in producing a comprehensive collection of lectures and tutorial reviews covering the field. This third volume follows the successful Lect. Notes Phys. 818 (Vol. 1) and 848 (Vol. 2), and comprises six extensive lectures covering the following topics:  - Gamma Rays and Molecular Structure - Faddeev Equation Approach for Three Cluster Nuclear Reactions - Tomography of the Cluster Structure of Light Nuclei Via Relativistic Dissociation - Clustering Effects Within the Dinuclear Model : From Light to Hyper-heavy Molecules in Dynamical Mean-field Approach - Clusterization in Ternary Fission - Clusters in Light N...

  14. Unconventional methods for clustering

    Science.gov (United States)

    Kotyrba, Martin

    2016-06-01

    Cluster analysis or clustering is a task of grouping a set of objects in such a way that objects in the same group (called a cluster) are more similar (in some sense or another) to each other than to those in other groups (clusters). It is the main task of exploratory data mining and a common technique for statistical data analysis used in many fields, including machine learning, pattern recognition, image analysis, information retrieval, and bioinformatics. The topic of this paper is one of the modern methods of clustering namely SOM (Self Organising Map). The paper describes the theory needed to understand the principle of clustering and descriptions of algorithm used with clustering in our experiments.

  15. Spatial cluster modelling

    CERN Document Server

    Lawson, Andrew B

    2002-01-01

    Research has generated a number of advances in methods for spatial cluster modelling in recent years, particularly in the area of Bayesian cluster modelling. Along with these advances has come an explosion of interest in the potential applications of this work, especially in epidemiology and genome research. In one integrated volume, this book reviews the state-of-the-art in spatial clustering and spatial cluster modelling, bringing together research and applications previously scattered throughout the literature. It begins with an overview of the field, then presents a series of chapters that illuminate the nature and purpose of cluster modelling within different application areas, including astrophysics, epidemiology, ecology, and imaging. The focus then shifts to methods, with discussions on point and object process modelling, perfect sampling of cluster processes, partitioning in space and space-time, spatial and spatio-temporal process modelling, nonparametric methods for clustering, and spatio-temporal ...

  16. 数字海图点群状特征的识别、量测与综合%Recognition, Measurement and Generalization for Point Cluster Features in Digital Nautical Chart

    Institute of Scientific and Technical Information of China (English)

    陆毅; 翟京生; 杜景海; 李树军

    2001-01-01

    空间分布特征的保持是点群自动综合的核心和难点所在,为此,本文定义了4个参量:分布范围、分布密度、分布中心和分布轴线,来描述点群目标的结构化信息。利用Delaunay三角网和voronoi图两种模型,着重探讨了点群分布特征的识别和量测问题,并在识别与量测的基础上,通过Voronoi图的动态构建,给出了点群自动综合模型,通过实际岛群数据的检测,证明了模型的正确性与可行性。%This paper, based on the Delaunay triangulation and Voronoi diagram model, focuses onthe discussion of spatial distribution properties by recognition and measurement. Four characteristic parameters are defined for distribution property description: distribution density of three dimensions, distribution range of two dimensions, distribution axis of one dimension, distributioncenter of zero dimension. With the aid of Delaunay triangulation and Voronoi diagram, descriptionand calculation models of above-mentioned parameters are established.   Firstly, considering the visual principles fully, a new method, which finds the distributionpolygon range by “nibbling the outside triangles”, is presented.Furthermore,different results canbe gained by using different threshold values,so the continuous-scale display nay become real.   Secondly,the distribution density is represented by Voronoi cell size and visualized as grayimage. So the density can be changed into the area that can be defined and measured easily.Wemay know where is denser and where should be simplified firstly. But one thing must be pointedout here that every point is regarded as nonobjective,and they divide the space on the equal principle. It is the basis and accords with the Voronoi principle.   Thirdly, the distribution center can be extracted from gray image. The new concept andmethods mentioned above are integrated into a recognition and measurement model for spatial distribution

  17. Global and Partial Errors in Stratified and Clustering Sampling

    OpenAIRE

    Giovanna Nicolini; Anna Lo Presti

    2005-01-01

    In this paper we split up the sampling error occurred in stratified and clustering sampling, called global error and measured by the variance of estimator, in many partial errors each one referred to a single stratum or cluster. In particular, we study, for clustering sampling, the empirical distribution of the homogeneity coefficient that is very important for settlement of partial errors.

  18. Abnormal tyrosine metabolism in chronic cluster headache.

    Science.gov (United States)

    D'Andrea, Giovanni; Leone, Massimo; Bussone, Gennaro; Fiore, Paola Di; Bolner, Andrea; Aguggia, Marco; Saracco, Maria Gabriella; Perini, Francesco; Giordano, Giuseppe; Gucciardi, Antonina; Leon, Alberta

    2017-02-01

    Objective Episodic cluster headache is characterized by abnormalities in tyrosine metabolism (i.e. elevated levels of dopamine, tyramine, octopamine and synephrine and low levels of noradrenalin in plasma and platelets.) It is unknown, however, if such biochemical anomalies are present and/or constitute a predisposing factor in chronic cluster headache. To test this hypothesis, we measured the levels of dopamine and noradrenaline together with those of elusive amines, such as tyramine, octopamine and synephrine, in plasma of chronic cluster patients and control individuals. Methods Plasma levels of dopamine, noradrenaline and trace amines, including tyramine, octopamine and synephrine, were measured in a group of 23 chronic cluster headache patients (10 chronic cluster ab initio and 13 transformed from episodic cluster), and 16 control participants. Results The plasma levels of dopamine, noradrenaline and tyramine were several times higher in chronic cluster headache patients compared with controls. The levels of octopamine and synephrine were significantly lower in plasma of these patients with respect to control individuals. Conclusions These results suggest that anomalies in tyrosine metabolism play a role in the pathogenesis of chronic cluster headache and constitute a predisposing factor for the transformation of the episodic into a chronic form of this primary headache.

  19. CLEAN: CLustering Enrichment ANalysis

    Directory of Open Access Journals (Sweden)

    Medvedovic Mario

    2009-07-01

    Full Text Available Abstract Background Integration of biological knowledge encoded in various lists of functionally related genes has become one of the most important aspects of analyzing genome-wide functional genomics data. In the context of cluster analysis, functional coherence of clusters established through such analyses have been used to identify biologically meaningful clusters, compare clustering algorithms and identify biological pathways associated with the biological process under investigation. Results We developed a computational framework for analytically and visually integrating knowledge-based functional categories with the cluster analysis of genomics data. The framework is based on the simple, conceptually appealing, and biologically interpretable gene-specific functional coherence score (CLEAN score. The score is derived by correlating the clustering structure as a whole with functional categories of interest. We directly demonstrate that integrating biological knowledge in this way improves the reproducibility of conclusions derived from cluster analysis. The CLEAN score differentiates between the levels of functional coherence for genes within the same cluster based on their membership in enriched functional categories. We show that this aspect results in higher reproducibility across independent datasets and produces more informative genes for distinguishing different sample types than the scores based on the traditional cluster-wide analysis. We also demonstrate the utility of the CLEAN framework in comparing clusterings produced by different algorithms. CLEAN was implemented as an add-on R package and can be downloaded at http://Clusteranalysis.org. The package integrates routines for calculating gene specific functional coherence scores and the open source interactive Java-based viewer Functional TreeView (FTreeView. Conclusion Our results indicate that using the gene-specific functional coherence score improves the reproducibility of the

  20. Buckling measurements up to 250 deg C on lattices of Agesta clusters and on D{sub 2}O alone in the pressurized exponential assembly TZ

    Energy Technology Data Exchange (ETDEWEB)

    Persson, R.; Andersson, A.J.W.; Wikdahl, C.E.

    1966-11-15

    Buckling determinations by means of flux mapping were performed in TZ up to 250 deg C on two lattices of Aagesta fuel assemblies in D{sub 2}O and on D{sub 2}O alone. Most of the flux measurements were made with fission counters in pressure thimbles. The perturbations caused by the thimbles were studied experimentally in various ways and compared with two group diffusion-theory calculations. In one of the lattices the effectiveness of a control rod (AglnCd) was also investigated. The results of the diffusion length experiments indicated some systematic error of the order of 0.15 - 0.10/m{sup 2} in the bucklings measured, though the temperature dependence should be well established. The bucklings of the two lattices studied (square pitches 24 and 27 cm) were found to be less sensitive to temperature than theoretical calculations predict, the temperature coefficient being more than 10 per cent smaller. The buckling changes from 20 to 250 deg C were about -2.4 and -1.8/m{sup 2}, respectively, for the two lattices. During part of the experimental period we had, for some unexplained reason, about 30 per cent excess absorption in the heavy water.

  1. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: RSD measurement from the power spectrum and bispectrum of the DR12 BOSS galaxies

    CERN Document Server

    Gil-Marín, Héctor; Verde, Licia; Brownstein, Joel R; Chuang, Chia-Hsun; Kitaura, Francisco-Shu; Rodríguez-Torres, Sergio A; Olmstead, Matthew D

    2016-01-01

    We measure and analyse the bispectrum of the final, Data Release 12, galaxy sample provided by the Baryon Oscillation Spectroscopic Survey, splitting by selection algorithm into LOWZ and CMASS galaxies. The LOWZ sample contains 361762 galaxies with an effective redshift of $z_{\\rm LOWZ}=0.32$, and the CMASS sample 777202 galaxies with an effective redshift of $z_{\\rm CMASS}=0.57$. Combining the power spectrum, measured relative to the line-of-sight, with the spherically averaged bispectrum, we are able to constrain the product of the growth of structure parameter, $f$, and the amplitude of dark matter density fluctuations, $\\sigma_8$, along with the geometric Alcock-Paczynski parameters, the product of the Hubble constant and the comoving sound horizon at the baryon drag epoch, $H(z)r_s(z_d)$, and the angular distance parameter divided by the sound horizon, $D_A(z)/r_s(z_d)$. We find $f(z_{\\rm LOWZ})\\sigma_8(z_{\\rm LOWZ})=0.460\\pm 0.066$, $D_A(z_{\\rm LOWZ})/r_s(z_d)=6.74 \\pm 0.22$, $H(z_{\\rm LOWZ})r_s(z_d)=(1...

  2. Agricultural Clusters in the Netherlands

    NARCIS (Netherlands)

    Schouten, M.A.; Heijman, W.J.M.

    2012-01-01

    Michael Porter was the first to use the term cluster in an economic context. He introduced the term in The Competitive Advantage of Nations (1990). The term cluster is also known as business cluster, industry cluster, competitive cluster or Porterian cluster. This article aims at determining and mea

  3. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: RSD measurement from the power spectrum and bispectrum of the DR12 BOSS galaxies

    Science.gov (United States)

    Gil-Marín, Héctor; Percival, Will J.; Verde, Licia; Brownstein, Joel R.; Chuang, Chia-Hsun; Kitaura, Francisco-Shu; Rodríguez-Torres, Sergio A.; Olmstead, Matthew D.

    2017-02-01

    We measure and analyse the bispectrum of the final data release 12 (DR12), galaxy sample provided by the Baryon Oscillation Spectroscopic Survey, splitting by selection algorithm into LOWZ and CMASS galaxies. The LOWZ sample contains 361 762 galaxies with an effective redshift of zLOWZ = 0.32, and the CMASS sample contains 777 202 galaxies with an effective redshift of zCMASS = 0.57. Combining the power spectrum, measured relative to the line of sight, with the spherically averaged bispectrum, we are able to constrain the product of the growth of structure parameter, f, and the amplitude of dark matter density fluctuations, σ8, along with the geometric Alcock-Paczynski parameters, the product of the Hubble constant and the comoving sound horizon at the baryon drag epoch, H(z)rs(zd), and the angular distance parameter divided by the sound horizon, DA(z)/rs(zd). After combining pre-reconstruction RSD analyses of the power spectrum monopole, quadrupole and bispectrum monopole with post-reconstruction analysis of the BAO power spectrum monopole and quadrupole, we find f(zLOWZ)σ8(zLOWZ) = 0.427 ± 0.056, DA(zLOWZ)/rs(zd) = 6.60 ± 0.13, H(zLOWZ)rs(zd) = (11.55 ± 0.38)103 km s-1 for the LOWZ sample, and f(zCMASS)σ8(zCMASS) = 0.426 ± 0.029, DA(zCMASS)/rs(zd) = 9.39 ± 0.10, H(zCMASS)rs(zd) = (14.02 ± 0.22)103 km s-1 for the CMASS sample. We find general agreement with previous Baryon Oscillation Spectroscopic Survey DR11 and DR12 measurements. Combining our data set with Planck15 we perform a null test of General Relativity through the γ-parametrization finding γ =0.733^{+0.068}_{-0.069}, which is ∼2.7σ away from the General Relativity predictions.

  4. Evaluating Clustering in Subspace Projections of High Dimensional Data

    DEFF Research Database (Denmark)

    Müller, Emmanuel; Günnemann, Stephan; Assent, Ira

    2009-01-01

    Clustering high dimensional data is an emerging research field. Subspace clustering or projected clustering group similar objects in subspaces, i.e. projections, of the full space. In the past decade, several clustering paradigms have been developed in parallel, without thorough evaluation and co...... and create a common baseline for future developments and comparable evaluations in the field. For repeatability, all implementations, data sets and evaluation measures are available on our website....

  5. Panchromatic Hubble Andromeda Treasury XVI. Star Cluster Formation Efficiency and the Clustered Fraction of Young Stars

    CERN Document Server

    Johnson, L Clifton; Dalcanton, Julianne J; Beerman, Lori C; Fouesneau, Morgan; Lewis, Alexia R; Weisz, Daniel R; Williams, Benjamin F; Bell, Eric F; Dolphin, Andrew E; Larsen, Søren S; Sandstrom, Karin; Skillman, Evan D

    2016-01-01

    We use the Panchromatic Hubble Andromeda Treasury (PHAT) survey dataset to perform spatially resolved measurements of star cluster formation efficiency ($\\Gamma$), the fraction of stellar mass formed in long-lived star clusters. We use robust star formation history and cluster parameter constraints, obtained through color-magnitude diagram analysis of resolved stellar populations, to study Andromeda's cluster and field populations over the last $\\sim$300 Myr. We measure $\\Gamma$ of 4-8% for young, 10-100 Myr old populations in M31. We find that cluster formation efficiency varies systematically across the M31 disk, consistent with variations in mid-plane pressure. These $\\Gamma$ measurements expand the range of well-studied galactic environments, providing precise constraints in an HI-dominated, low intensity star formation environment. Spatially resolved results from M31 are broadly consistent with previous trends observed on galaxy-integrated scales, where $\\Gamma$ increases with increasing star formation r...

  6. Masses of galaxy clusters from gravitational lensing

    CERN Document Server

    Hoekstra, Henk; Dahle, Haakon; Israel, Holger; Limousin, Marceau; Meneghetti, Massimo

    2013-01-01

    Despite consistent progress in numerical simulations, the observable properties of galaxy clusters are difficult to predict ab initio. It is therefore important to compare both theoretical and observational results to a direct measure of the cluster mass. This can be done by measuring the gravitational lensing effects caused by the bending of light by the cluster mass distribution. In this review we discuss how this phenomenon can be used to determine cluster masses and study the mass distribution itself. As sample sizes increase, the accuracy of the weak lensing mass estimates needs to improve accordingly. We discuss the main practical aspects of these measurements. We review a number of applications and highlight some recent results.

  7. The C4 clustering algorithm: Clusters of galaxies in the Sloan Digital Sky Survey

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Christopher J.; Nichol, Robert; Reichart, Dan; Wechsler, Risa H.; Evrard, August; Annis, James; McKay, Timothy; Bahcall, Neta; Bernardi, Mariangela; Boehringer,; Connolly, Andrew; Goto, Tomo; Kniazev, Alexie; Lamb, Donald; Postman, Marc; Schneider, Donald; Sheth, Ravi; Voges, Wolfgang; /Cerro-Tololo InterAmerican Obs. /Portsmouth U.,

    2005-03-01

    We present the ''C4 Cluster Catalog'', a new sample of 748 clusters of galaxies identified in the spectroscopic sample of the Second Data Release (DR2) of the Sloan Digital Sky Survey (SDSS). The C4 cluster-finding algorithm identifies clusters as overdensities in a seven-dimensional position and color space, thus minimizing projection effects that have plagued previous optical cluster selection. The present C4 catalog covers {approx}2600 square degrees of sky and ranges in redshift from z = 0.02 to z = 0.17. The mean cluster membership is 36 galaxies (with redshifts) brighter than r = 17.7, but the catalog includes a range of systems, from groups containing 10 members to massive clusters with over 200 cluster members with redshifts. The catalog provides a large number of measured cluster properties including sky location, mean redshift, galaxy membership, summed r-band optical luminosity (L{sub r}), velocity dispersion, as well as quantitative measures of substructure and the surrounding large-scale environment. We use new, multi-color mock SDSS galaxy catalogs, empirically constructed from the {Lambda}CDM Hubble Volume (HV) Sky Survey output, to investigate the sensitivity of the C4 catalog to the various algorithm parameters (detection threshold, choice of passbands and search aperture), as well as to quantify the purity and completeness of the C4 cluster catalog. These mock catalogs indicate that the C4 catalog is {approx_equal}90% complete and 95% pure above M{sub 200} = 1 x 10{sup 14} h{sup -1}M{sub {circle_dot}} and within 0.03 {le} z {le} 0.12. Using the SDSS DR2 data, we show that the C4 algorithm finds 98% of X-ray identified clusters and 90% of Abell clusters within 0.03 {le} z {le} 0.12. Using the mock galaxy catalogs and the full HV dark matter simulations, we show that the L{sub r} of a cluster is a more robust estimator of the halo mass (M{sub 200}) than the galaxy line-of-sight velocity dispersion or the richness of the cluster

  8. Kinematics of Star Clusters in M101

    CERN Document Server

    Simanton, Lesley; Miller, Bryan

    2013-01-01

    We have identified a few thousand star clusters in the nearby, late-type spiral galaxy M101, including approximately 90 candidate ancient globular clusters (GCs), from multi-band Hubble Space Telescope (HST) images. We obtained follow-up low-resolution (R approximately 2000) optical spectroscopy from Gemini-GMOS for 43 total clusters, of which 18 are old GCs and 25 are young massive clusters (YMCs). We measure radial velocities for these clusters and find that, as expected, the YMCs rotate with the HI disk. The old GCs do not show any obvious evidence for rotation and have a much higher velocity dispersion than the YMCs, suggesting that the GCs in M101 are likely part of a stellar halo or thick disk.

  9. Hotter electron generation in doped clusters

    Energy Technology Data Exchange (ETDEWEB)

    Jha, J; Krishnamurthy, M [Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005 (India)], E-mail: mkrism@tifr.res.in

    2008-02-28

    We present electron energy measurements from nano-cluster plasmas that are formed when molecule-doped rare-gas clusters are irradiated by intense, 100 fs laser pulses of intensity {approx}10{sup 15} W cm{sup -2}. In pure Ar clusters the high temperature component (energy {approx}1400 eV) is less than 1% of the low temperature component (energy {approx}130 eV), while for water-doped Ar clusters the high temperature component is as high as 7% of the low temperature component. Numerical estimates based on collisional ionization and inverse bremsstrahlung absorption indicate that the easily ionizable dopant molecules enhance the propensity for ionization ignition by significantly altering the temporal profile of the inner-ionized electron density within the cluster. (fast track communication)

  10. Precision cluster mass determination from weak lensing

    CERN Document Server

    Mandelbaum, Rachel; Baldauf, Tobias; Smith, Robert E

    2009-01-01

    Weak gravitational lensing has been used extensively in the past decade to constrain the masses of galaxy clusters, and is the most promising observational technique for providing the mass calibration necessary for precision cosmology with clusters. There are several challenges in estimating cluster masses, particularly (a) the sensitivity to astrophysical effects and observational systematics that modify the signal relative to the theoretical expectations, and (b) biases that can arise due to assumptions in the mass estimation method, such as the assumed radial profile of the cluster. All of these challenges are more problematic in the inner regions of the cluster, suggesting that their influence would ideally be suppressed for the purpose of mass estimation. However, at any given radius the differential surface density measured by lensing is sensitive to all mass within that radius, and the corrupted signal from the inner parts is spread out to all scales. We develop a new statistic that is ideal for estima...

  11. Document Clustering based on Topic Maps

    CERN Document Server

    Rafi, Muhammad; Farooq, Amir; 10.5120/1640-2204

    2011-01-01

    Importance of document clustering is now widely acknowledged by researchers for better management, smart navigation, efficient filtering, and concise summarization of large collection of documents like World Wide Web (WWW). The next challenge lies in semantically performing clustering based on the semantic contents of the document. The problem of document clustering has two main components: (1) to represent the document in such a form that inherently captures semantics of the text. This may also help to reduce dimensionality of the document, and (2) to define a similarity measure based on the semantic representation such that it assigns higher numerical values to document pairs which have higher semantic relationship. Feature space of the documents can be very challenging for document clustering. A document may contain multiple topics, it may contain a large set of class-independent general-words, and a handful class-specific core-words. With these features in mind, traditional agglomerative clustering algori...

  12. Worldwide clustering of the corruption perception

    Science.gov (United States)

    Paulus, Michal; Kristoufek, Ladislav

    2015-06-01

    We inspect a possible clustering structure of the corruption perception among 134 countries. Using the average linkage clustering, we uncover a well-defined hierarchy in the relationships among countries. Four main clusters are identified and they suggest that countries worldwide can be quite well separated according to their perception of corruption. Moreover, we find a strong connection between corruption levels and a stage of development inside the clusters. The ranking of countries according to their corruption perfectly copies the ranking according to the economic performance measured by the gross domestic product per capita of the member states. To the best of our knowledge, this study is the first one to present an application of hierarchical and clustering methods to the specific case of corruption.

  13. Clustering high dimensional data using RIA

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, Nazrina [School of Quantitative Sciences, College of Arts and Sciences, Universiti Utara Malaysia, 06010 Sintok, Kedah (Malaysia)

    2015-05-15

    Clustering may simply represent a convenient method for organizing a large data set so that it can easily be understood and information can efficiently be retrieved. However, identifying cluster in high dimensionality data sets is a difficult task because of the curse of dimensionality. Another challenge in clustering is some traditional functions cannot capture the pattern dissimilarity among objects. In this article, we used an alternative dissimilarity measurement called Robust Influence Angle (RIA) in the partitioning method. RIA is developed using eigenstructure of the covariance matrix and robust principal component score. We notice that, it can obtain cluster easily and hence avoid the curse of dimensionality. It is also manage to cluster large data sets with mixed numeric and categorical value.

  14. Clusters in neutron-rich light nuclei

    Directory of Open Access Journals (Sweden)

    Jelavić Malenica D.

    2016-01-01

    Full Text Available Due to their high selectivity, transfer and sequential decay reactions are powerful tools for studies of both single particle (nucleon and cluster states in light nuclei. Their use is particularly simple for investigations of α-particle clustering (because α-particle has Jπ=0+, which simplifies spin and parity assignments to observed cluster states, but they are also easily applicable to other types of clustering. Recent results on clustering in neutron-rich isotopes of beryllium, boron and carbon obtained measuring the 10B+10B reactions (at 50 and 72 MeV are presented. The highly efficient and segmented detector systems used, built from 4 Double Sided Silicon Strip Detectors (DSSSD allowed detection of double and multiple coincidences and, in that way, studies of states populated in transfer reactions, as well as their sequential decay.

  15. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: BAO measurement from the LOS-dependent power spectrum of DR12 BOSS galaxies

    CERN Document Server

    Gil-Marín, Héctor; Cuesta, Antonio J; Brownstein, Joel R; Chuang, Chia-Hsun; Ho, Shirley; Kitaura, Francisco-Shu; Maraston, Claudia; Prada, Francisco; Rodríguez-Torres, Sergio; Ross, Ashely J; Schlegel, David J; Schneider, Donald P; Thomas, Daniel; Tinker, Jeremy L; Tojeiro, Rita; Magaña, Mariana Vargas; Zhao, Gong-Bo

    2015-01-01

    [abridged] We present an anisotropic analysis of the baryonic acoustic oscillation (BAO) scale in the twelfth and final data release of the Baryonic Oscillation Spectroscopic Survey (BOSS). We independently analyse the LOWZ and CMASS galaxy samples: the LOWZ sample contains contains 361\\,762 galaxies with an effective redshift of $z_{\\rm LOWZ}=0.32$, and the CMASS sample consists of 777\\,202 galaxies with an effective redshift of $z_{\\rm CMASS}=0.57$. We extract the BAO peak position from the monopole power spectrum moment, $\\alpha_0$, and from the $\\mu^2$ moment, $\\alpha_2$. We report $H(z_{\\rm LOWZ})r_s(z_d)=(11.64\\pm0.62)\\cdot10^3\\,{\\rm km}s^{-1}$ and $D_A(z_{\\rm LOWZ})/r_s(z_d)=6.85\\pm0.17$ with a cross-correlation coefficient of $r_{HD_A}=0.42$, for the LOWZ sample; and $H(z_{\\rm CMASS})r_s(z_d)=(14.56\\pm0.38)\\cdot10^3\\,{\\rm km}s^{-1}$ and $D_A(z_{\\rm CMASS})/r_s(z_d)=9.42\\pm0.13$ with a cross-correlation coefficient of $r_{HD_A}=0.51$, for the CMASS sample. We combine these results with the measurements...

  16. CO2 Activation and Hydrogenation by PtHn (-) Cluster Anions.

    Science.gov (United States)

    Zhang, Xinxing; Liu, Gaoxiang; Meiwes-Broer, Karl-Heinz; Ganteför, Gerd; Bowen, Kit

    2016-08-08

    Gas phase reactions between PtHn (-) cluster anions and CO2 were investigated by mass spectrometry, anion photoelectron spectroscopy, and computations. Two major products, PtCO2 H(-) and PtCO2 H3 (-) , were observed. The atomic connectivity in PtCO2 H(-) can be depicted as HPtCO2 (-) , where the platinum atom is bonded to a bent CO2 moiety on one side and a hydrogen atom on the other. The atomic connectivity of PtCO2 H3 (-) can be described as H2 Pt(HCO2 )(-) , where the platinum atom is bound to a formate moiety on one side and two hydrogen atoms on the other. Computational studies of the reaction pathway revealed that the hydrogenation of CO2 by PtH3 (-) is highly energetically favorable.

  17. Measurement of the 1s2l3l’ Dielectronic Recombination Emission Line in Li-Like Ar and Its Contribution to the Faint X-Ray Feature Found in the Stacked Spectrum of Galaxy Clusters

    Science.gov (United States)

    Gall, Amy Christina; Silwal, Roshani; Dreiling, Joan; Borovik, Alexander; Ajello, Marco; Gillaspy, John; Kilgore, Ethan; Ralchenko, Yuri; Takacs, Endre

    2016-06-01

    Driven by the recent detection of an unidentified emission line previously reported at 3.55-3.57 keV in a stacked spectrum of galaxy clusters, we investigated the resonant DR process in Li-like Ar as a possible source of, or contributor to, the emission line. The Li-like transition 1s22l-1s2l3l’ was suggested to produce a 3.62 keV photon [1] near the unidentified line at 3.57 keV and was the primary focus of our investigation. Apart from the mentioned transitions, we have found other features that can be possible contributors to the emission in this region. The Electron Beam Ion Trap at NIST was used to produce and trap the highly-charged ions of argon. The energy of the quasi-monoenergetic electron beam was incremented in steps of 15 eV to scan over all of the Li-like Ar DR resonances. A Johann-type crystal spectrometer and a solid-state germanium detector were used to take x-ray measurements perpendicular to the electron beam. The DR cross sections were measured and normalized to the well-known photoionization cross sections using radiative recombination peaks in the measured spectra. Corrections for different instrument and method related effects such as charge state balance, electron beam space charge, and charge exchange have been considered. Our high-resolution crystal spectra allowed the experimental separation of features that are less than 2 eV apart. We have used a collisional radiative model NOMAD [2] aided by atomic data calculations by FAC [3] to interpret our observations and account for the corrections and uncertainties. Experimental results were compared to the AtomDB theoretical emission lines used to fit the galaxy cluster spectra containing the unidentified 3.57 keV line. These data points can be added benchmarks in the database and used to accurately interpret spectra from current x-ray satellites, including Hitomi, Chandra, and XMM-Newton x-ray observatories.[1] Bulbul E. et al., 2014, ApJ, 789, 13[2] Ralchenko Yu. et al., 2014, JQSRT, 71

  18. The 3XMM/SDSS Stripe 82 Galaxy Cluster Survey. I. Cluster catalogue and discovery of two merging cluster candidates

    Science.gov (United States)

    Takey, A.; Durret, F.; Mahmoud, E.; Ali, G. B.

    2016-10-01

    We present a galaxy cluster survey based on XMM-Newton observations that are located in Stripe 82 of the Sloan Digital Sky Survey (SDSS). The survey covers an area of 11.25 deg2. The X-ray cluster candidates were selected as serendipitously extended detected sources from the third XMM-Newton serendipitous source catalogue (3XMM-DR5). A cross-correlation of the candidate list that comprises 94 objects with recently published X-ray and optically selected cluster catalogues provided optical confirmations and redshift estimates for about half of the candidate sample. We present a catalogue of X-ray cluster candidates previously known in X-ray and/or optical bands from the matched catalogues or NED. The catalogue consists of 54 systems with redshift measurements in the range of 0.05-1.19 with a median of 0.36. Of these, 45 clusters have spectroscopic confirmations as stated in the matched catalogues. We spectroscopically confirmed another 6 clusters from the available spectroscopic redshifts in the SDSS-DR12. The cluster catalogue includes 17 newly X-ray discovered clusters, while the remainder were detected in previous XMM-Newton and/or ROSAT cluster surveys. Based on the available redshifts and fluxes given in the 3XMM-DR5 catalogue, we estimated the X-ray luminosities and masses for the cluster sample. We also present the list of the remaining X-ray cluster candidates (40 objects) that have no redshift information yet in the literature. Of these candidates, 25 sources are considered as distant cluster candidates beyond a redshift of 0.6. We also searched for galaxy cluster mergers in our cluster sample and found two strong candidates for newly discovered cluster mergers at redshifts of 0.11 and 0.26. The X-ray and optical properties of these systems are presented. Tables A.1, C.1, and C.2 are also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/594/A32

  19. Clustering Categorical Data:A Cluster Ensemble Approach

    Institute of Scientific and Technical Information of China (English)

    He Zengyou(何增友); Xu Xiaofei; Deng Shengchun

    2003-01-01

    Clustering categorical data, an integral part of data mining,has attracted much attention recently. In this paper, the authors formally define the categorical data clustering problem as an optimization problem from the viewpoint of cluster ensemble, and apply cluster ensemble approach for clustering categorical data. Experimental results on real datasets show that better clustering accuracy can be obtained by comparing with existing categorical data clustering algorithms.

  20. Spatial Scan Statistic: Selecting clusters and generating elliptic clusters

    DEFF Research Database (Denmark)

    Christiansen, Lasse Engbo; Andersen, Jens Strodl

    2004-01-01

    The spatial scan statistic is widely used to search for clusters. This paper shows that the usually applied elimination of overlapping clusters to find secondary clusters is sensitive to smooth changes in the shape of the clusters. We present an algorithm for generation of set of confocal elliptic...... clusters. In addition, we propose a new way to present the information in a given set of clusters based on the significance of the clusters....

  1. Disentangling Porterian Clusters

    DEFF Research Database (Denmark)

    Jagtfelt, Tue

    This dissertation investigates the contemporary phenomenon of industrial clusters based on the work of Michael E. Porter, the central progenitor and promoter of the cluster notion. The dissertation pursues two central questions: 1) What is a cluster? and 2) How could Porter’s seemingly fuzzy...... to his membership on the Commission on Industrial Competitiveness, and that the cluster notion found in his influential book, Nations, represents a significant shift in his conception of cluster compared with his early conceptions. This shift, it is argued, is a deliberate attempt by Porter to create......, contested theory become so widely disseminated and applied as a normative and prescriptive strategy for economic development? The dissertation traces the introduction of the cluster notion into the EU’s Lisbon Strategy and demonstrates how its inclusion originates from Porter’s colleagues: Professor Örjan...

  2. Online Correlation Clustering

    CERN Document Server

    Mathieu, Claire; Schudy, Warren

    2010-01-01

    We study the online clustering problem where data items arrive in an online fashion. The algorithm maintains a clustering of data items into similarity classes. Upon arrival of v, the relation between v and previously arrived items is revealed, so that for each u we are told whether v is similar to u. The algorithm can create a new cluster for v and merge existing clusters. When the objective is to minimize disagreements between the clustering and the input, we prove that a natural greedy algorithm is O(n)-competitive, and this is optimal. When the objective is to maximize agreements between the clustering and the input, we prove that the greedy algorithm is .5-competitive; that no online algorithm can be better than .834-competitive; we prove that it is possible to get better than 1/2, by exhibiting a randomized algorithm with competitive ratio .5+c for a small positive fixed constant c.

  3. Melting of sodium clusters

    CERN Document Server

    Reyes-Nava, J A; Beltran, M R; Michaelian, K

    2002-01-01

    Thermal stability properties and the melting-like transition of Na_n, n=13-147, clusters are studied through microcanonical molecular dynamics simulations. The metallic bonding in the sodium clusters is mimicked by a many-body Gupta potential based on the second moment approximation of a tight-binding Hamiltonian. The characteristics of the solid-to-liquid transition in the sodium clusters are analyzed by calculating physical quantities like caloric curves, heat capacities, and root-mean-square bond length fluctuations using simulation times of several nanoseconds. Distinct melting mechanisms are obtained for the sodium clusters in the size range investigated. The calculated melting temperatures show an irregular variation with the cluster size, in qualitative agreement with recent experimental results. However, the calculated melting point for the Na_55 cluster is about 40 % lower than the experimental value.

  4. Cosmology with cluster surveys

    Indian Academy of Sciences (India)

    Subhabrata Majumdar

    2004-10-01

    Surveys of clusters of galaxies provide us with a powerful probe of the density and nature of the dark energy. The red-shift distribution of detected clusters is highly sensitive to the dark energy equation of state parameter . Upcoming Sunyaev–Zel'dovich (SZ) surveys would provide us large yields of clusters to very high red-shifts. Self-calibration of cluster scaling relations, possible for such a huge sample, would be able to constrain systematic biases on mass estimators. Combining cluster red-shift abundance with limited mass follow-up and cluster mass power spectrum can then give constraints on , as well as on 8 and to a few per cents.

  5. CSR in Industrial Clusters

    DEFF Research Database (Denmark)

    Lund-Thomsen, Peter; Pillay, Renginee G.

    2012-01-01

    Purpose – The paper seeks to review the literature on CSR in industrial clusters in developing countries, identifying the main strengths, weaknesses, and gaps in this literature, pointing to future research directions and policy implications in the area of CSR and industrial cluster development...... in this field and their comments incorporated in the final version submitted to Corporate Governance. Findings – The article traces the origins of the debate on industrial clusters and CSR in developing countries back to the early 1990s when clusters began to be seen as an important vehicle for local economic...... development in the South. At the turn of the millennium the industrial cluster debate expanded as clusters were perceived as a potential source of poverty reduction, while their role in promoting CSR among small and medium-sized enterprises began to take shape from 2006 onwards. At present, there is still...

  6. Cluster Management Institutionalization

    DEFF Research Database (Denmark)

    Normann, Leo; Agger Nielsen, Jeppe

    2015-01-01

    This article explores a new management form – cluster management – in Danish public sector day care. Although cluster management has been widely adopted in Danish day care at the municipality level, it has attracted only sparse research attention. We use theoretical insights from Scandinavian...... institutionalism together with a longitudinal case-based inquiry into how cluster management has entered and penetrated the management practices of day care in Denmark. We demonstrate how cluster management became widely adopted in the day care field not only because of its intrinsic properties but also because...... of how it was legitimized as a “ready-to-use” management model. Further, our account reveals how cluster management translated into considerably different local variants as it travelled into specific organizations. However, these processes have not occurred sequentially with cluster management first...

  7. Exploiting Document Level Semantics in Document Clustering

    Directory of Open Access Journals (Sweden)

    Muhammad Rafi

    2016-06-01

    Full Text Available Document clustering is an unsupervised machine learning method that separates a large subject heterogeneous collection (Corpus into smaller, more manageable, subject homogeneous collections (clusters. Traditional method of document clustering works around extracting textual features like: terms, sequences, and phrases from documents. These features are independent of each other and do not cater meaning behind these word in the clustering process. In order to perform semantic viable clustering, we believe that the problem of document clustering has two main components: (1 to represent the document in such a form that it inherently captures semantics of the text. This may also help to reduce dimensionality of the document and (2 to define a similarity measure based on the lexical, syntactic and semantic features such that it assigns higher numerical values to document pairs which have higher syntactic and semantic relationship. In this paper, we propose a representation of document by extracting three different types of features from a given document. These are lexical , syntactic and semantic features. A meta-descriptor for each document is proposed using these three features: first lexical, then syntactic and in the last semantic. A document to document similarity matrix is produced where each entry of this matrix contains a three value vector for each lexical , syntactic and semantic . The main contributions from this research are (i A document level descriptor using three different features for text like: lexical, syntactic and semantics. (ii we propose a similarity function using these three, and (iii we define a new candidate clustering algorithm using three component of similarity measure to guide the clustering process in a direction that produce more semantic rich clusters. We performed an extensive series of experiments on standard text mining data sets with external clustering evaluations like: FMeasure and Purity, and have obtained

  8. Structures in Galaxy Clusters

    CERN Document Server

    Escalera, E; Girardi, M; Giuricin, G; Mardirossian, F; Mazure, A; Mezzetti, M

    1993-01-01

    The analysis of the presence of substructures in 16 well-sampled clusters of galaxies suggests a stimulating hypothesis: Clusters could be classified as unimodal or bimodal, on the basis of to the sub-clump distribution in the {\\em 3-D} space of positions and velocities. The dynamic study of these clusters shows that their fundamental characteristics, in particular the virial masses, are not severely biased by the presence of subclustering if the system considered is bound.

  9. Clustering Techniques in Bioinformatics

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Masood

    2015-01-01

    Full Text Available Dealing with data means to group information into a set of categories either in order to learn new artifacts or understand new domains. For this purpose researchers have always looked for the hidden patterns in data that can be defined and compared with other known notions based on the similarity or dissimilarity of their attributes according to well-defined rules. Data mining, having the tools of data classification and data clustering, is one of the most powerful techniques to deal with data in such a manner that it can help researchers identify the required information. As a step forward to address this challenge, experts have utilized clustering techniques as a mean of exploring hidden structure and patterns in underlying data. Improved stability, robustness and accuracy of unsupervised data classification in many fields including pattern recognition, machine learning, information retrieval, image analysis and bioinformatics, clustering has proven itself as a reliable tool. To identify the clusters in datasets algorithm are utilized to partition data set into several groups based on the similarity within a group. There is no specific clustering algorithm, but various algorithms are utilized based on domain of data that constitutes a cluster and the level of efficiency required. Clustering techniques are categorized based upon different approaches. This paper is a survey of few clustering techniques out of many in data mining. For the purpose five of the most common clustering techniques out of many have been discussed. The clustering techniques which have been surveyed are: K-medoids, K-means, Fuzzy C-means, Density-Based Spatial Clustering of Applications with Noise (DBSCAN and Self-Organizing Map (SOM clustering.

  10. Clustering of Absorbers

    CERN Document Server

    Cristiani, S; D'Odorico, V; Fontana, A; Giallongo, E; Moscardini, L; Savaglio, S

    1997-01-01

    The observed clustering of Lyman-$\\alpha$ lines is reviewed and compared with the clustering of CIV systems. We argue that a continuity of properties exists between Lyman-$\\alpha$ and metal systems and show that the small-scale clustering of the absorbers is consistent with a scenario of gravitationally induced correlations. At large scales statistically significant over and under-densities (including voids) are found on scales of tens of Mpc.

  11. Galaxy Clusters with Chandra

    CERN Document Server

    Forman, W; Markevitch, M L; Vikhlinin, A A; Churazov, E

    2002-01-01

    We discuss Chandra results related to 1) cluster mergers and cold fronts and 2) interactions between relativistic plasma and hot cluster atmospheres. We describe the properties of cold fronts using NGC1404 in the Fornax cluster and A3667 as examples. We discuss multiple surface brightness discontinuities in the cooling flow cluster ZW3146. We review the supersonic merger underway in CL0657. Finally, we summarize the interaction between plasma bubbles produced by AGN and hot gas using M87 and NGC507 as examples.

  12. Star Clusters within FIRE

    Science.gov (United States)

    Perez, Adrianna; Moreno, Jorge; Naiman, Jill; Ramirez-Ruiz, Enrico; Hopkins, Philip F.

    2017-01-01

    In this work, we analyze the environments surrounding star clusters of simulated merging galaxies. Our framework employs Feedback In Realistic Environments (FIRE) model (Hopkins et al., 2014). The FIRE project is a high resolution cosmological simulation that resolves star forming regions and incorporates stellar feedback in a physically realistic way. The project focuses on analyzing the properties of the star clusters formed in merging galaxies. The locations of these star clusters are identified with astrodendro.py, a publicly available dendrogram algorithm. Once star cluster properties are extracted, they will be used to create a sub-grid (smaller than the resolution scale of FIRE) of gas confinement in these clusters. Then, we can examine how the star clusters interact with these available gas reservoirs (either by accreting this mass or blowing it out via feedback), which will determine many properties of the cluster (star formation history, compact object accretion, etc). These simulations will further our understanding of star formation within stellar clusters during galaxy evolution. In the future, we aim to enhance sub-grid prescriptions for feedback specific to processes within star clusters; such as, interaction with stellar winds and gas accretion onto black holes and neutron stars.

  13. The Youngest Globular Clusters

    CERN Document Server

    Beck, Sara

    2014-01-01

    It is likely that all stars are born in clusters, but most clusters are not bound and disperse. None of the many protoclusters in our Galaxy are likely to develop into long-lived bound clusters. The Super Star Clusters (SSCs) seen in starburst galaxies are more massive and compact and have better chances of survival. The birth and early development of SSCs takes place deep in molecular clouds, and during this crucial stage the embedded clusters are invisible to optical or UV observations but are studied via the radio-infared supernebulae (RISN) they excite. We review observations of embedded clusters and identify RISN within 10 Mpc whose exciting clusters have a million solar masses or more in volumes of a few cubic parsecs and which are likely to not only survive as bound clusters, but to evolve into objects as massive and compact as Galactic globulars. These clusters are distinguished by very high star formation efficiency eta, at least a factor of 10 higher than the few percent seen in the Galaxy, probably...

  14. 15th Cluster workshop

    CERN Document Server

    Laakso, Harri; Escoubet, C. Philippe; The Cluster Active Archive : Studying the Earth’s Space Plasma Environment

    2010-01-01

    Since the year 2000 the ESA Cluster mission has been investigating the small-scale structures and processes of the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids. This book contains presentations made at the 15th Cluster workshop held in March 2008. It also presents several articles about the Cluster Active Archive and its datasets, a few overview papers on the Cluster mission, and articles reporting on scientific findings on the solar wind, the magnetosheath, the magnetopause and the magnetotail.

  15. Immunodominance and clonal selection inspired multiobjective clustering

    Institute of Scientific and Technical Information of China (English)

    Wenping Ma; Licheng Jiao; Maoguo Gong

    2009-01-01

    The biological immune system is a highly parallel and distributed adaptive system. The information processing abilities of the immune system provide important insights into the field of computation. Based on immunodominance in the biological immune system and the clonal selection mechanism, a novel data mining method, Immune Dominance Clonal Multiobjective Clustering algorithm (IDCMC), is presented. The algorithm divides an individual population into three sub-populations according to three different measurements, and adopts different evolution and selection strategies for each sub-population. The update of each sub-population, however, is not carried out in isolation. The periodic combination operation of the analysis of the three sub-populations represents considerable advantages in its global search ability. The clustering task is a multiobjective optimization problem, which is more robust with respect to the variety of cluster structures of different datasets than a single-objective clustering algorithm. In addition, the new algorithm can determine the num-ber of clusters automatically, which should identify the most promising clustering solutions in the candidate set. The experimental results, using artificial datasets with different manifold structure and handwritten digit datasets, show that the IDCMC outperforms the PESA-ll-based clustering method, the genetic algorithm-based clustering technique and the original K-Means algorithm in solving most of the problems tested.

  16. Document Clustering Based on Semi-Supervised Term Clustering

    Directory of Open Access Journals (Sweden)

    Hamid Mahmoodi

    2012-05-01

    Full Text Available The study is conducted to propose a multi-step feature (term selection process and in semi-supervised fashion, provide initial centers for term clusters. Then utilize the fuzzy c-means (FCM clustering algorithm for clustering terms. Finally assign each of documents to closest associated term clusters. While most text clustering algorithms directly use documents for clustering, we propose to first group the terms using FCM algorithm and then cluster documents based on terms clusters. We evaluate effectiveness of our technique on several standard text collections and compare our results with the some classical text clustering algorithms.

  17. A CLUSTERING ALGORITHM FOR MIXED NUMERIC AND CATEGORICAL DATA

    Institute of Scientific and Technical Information of China (English)

    Ohn Mar San; Van-Nam Huynh; Yoshiteru Nakamori

    2003-01-01

    Most of the earlier work on clustering mainly focused on numeric data whose inherent geometric properties can be exploited to naturally define distance functions between data points. However, data mining applications frequently involve many datasets that also consists of mixed numeric and categorical attributes. In this paper we present a clustering algorithm which is based on the k-means algorithm. The algorithm clusters objects with numeric and categorical attributes in a way similar to k-means. The object similarity measure is derived from both numeric and categorical attributes. When applied to numeric data, the algorithm is identical to the k-means. The main result of this paper is to provide a method to update the "cluster centers" of clustering objects described by mixed numeric and categorical attributes in the clustering process to minimize the clustering cost function. The clustering performance of the algorithm is demonstrated with the two well known data sets, namely credit approval and abalone databases.

  18. Issues Challenges and Tools of Clustering Algorithms

    Directory of Open Access Journals (Sweden)

    Parul Agarwal

    2011-05-01

    Full Text Available Clustering is an unsupervised technique of Data Mining. It means grouping similar objects together and separating the dissimilar ones. Each object in the data set is assigned a class label in the clustering process using a distance measure. This paper has captured the problems that are faced in real when clustering algorithms are implemented .It also considers the most extensively used tools which are readily available and support functions which ease the programming. Once algorithms have been implemented, they also need to be tested for its validity. There exist several validation indexes for testing the performance and accuracy which have also been discussed here.

  19. Hierarchical modeling of cluster size in wildlife surveys

    Science.gov (United States)

    Royle, J. Andrew

    2008-01-01

    Clusters or groups of individuals are the fundamental unit of observation in many wildlife sampling problems, including aerial surveys of waterfowl, marine mammals, and ungulates. Explicit accounting of cluster size in models for estimating abundance is necessary because detection of individuals within clusters is not independent and detectability of clusters is likely to increase with cluster size. This induces a cluster size bias in which the average cluster size in the sample is larger than in the population at large. Thus, failure to account for the relationship between delectability and cluster size will tend to yield a positive bias in estimates of abundance or density. I describe a hierarchical modeling framework for accounting for cluster-size bias in animal sampling. The hierarchical model consists of models for the observation process conditional on the cluster size distribution and the cluster size distribution conditional on the total number of clusters. Optionally, a spatial model can be specified that describes variation in the total number of clusters per sample unit. Parameter estimation, model selection, and criticism may be carried out using conventional likelihood-based methods. An extension of the model is described for the situation where measurable covariates at the level of the sample unit are available. Several candidate models within the proposed class are evaluated for aerial survey data on mallard ducks (Anas platyrhynchos).

  20. Clustering Text Data Streams

    Institute of Scientific and Technical Information of China (English)

    Yu-Bao Liu; Jia-Rong Cai; Jian Yin; Ada Wai-Chee Fu

    2008-01-01

    Clustering text data streams is an important issue in data mining community and has a number of applications such as news group filtering, text crawling, document organization and topic detection and tracing etc. However, most methods are similarity-based approaches and only use the TF*IDF scheme to represent the semantics of text data and often lead to poor clustering quality. Recently, researchers argue that semantic smoothing model is more efficient than the existing TF.IDF scheme for improving text clustering quality. However, the existing semantic smoothing model is not suitable for dynamic text data context. In this paper, we extend the semantic smoothing model into text data streams context firstly. Based on the extended model, we then present two online clustering algorithms OCTS and OCTSM for the clustering of massive text data streams. In both algorithms, we also present a new cluster statistics structure named cluster profile which can capture the semantics of text data streams dynamically and at the same time speed up the clustering process. Some efficient implementations for our algorithms are also given. Finally, we present a series of experimental results illustrating the effectiveness of our technique.

  1. Neurostimulation in cluster headache

    DEFF Research Database (Denmark)

    Pedersen, Jeppe L; Barloese, Mads; Jensen, Rigmor H

    2013-01-01

    PURPOSE OF REVIEW: Neurostimulation has emerged as a viable treatment for intractable chronic cluster headache. Several therapeutic strategies are being investigated including stimulation of the hypothalamus, occipital nerves and sphenopalatine ganglion. The aim of this review is to provide...... effective strategy must be preferred as first-line therapy for intractable chronic cluster headache....

  2. Securing personal network clusters

    NARCIS (Netherlands)

    Jehangir, Assed; Heemstra de Groot, Sonia M.

    2007-01-01

    A Personal Network is a self-organizing, secure and private network of a user’s devices notwithstanding their geographic location. It aims to utilize pervasive computing to provide users with new and improved services. In this paper we propose a model for securing Personal Network clusters. Clusters

  3. [Cluster headache differential diagnosis].

    Science.gov (United States)

    Guégan-Massardier, Evelyne; Laubier, Cécile

    2015-11-01

    Cluster headache is characterized by disabling stereotyped headache. Early diagnosis allows appropriate treatment, unfortunately diagnostic errors are frequent. The main differential diagnoses are other primary or essential headaches. Migraine, more frequent and whose diagnosis is carried by excess, trigeminal neuralgia or other trigemino-autonomic cephalgia. Vascular or tumoral underlying condition can mimic cluster headache, neck and brain imaging is recommended, ideally MRI.

  4. Cluster Management Institutionalization

    DEFF Research Database (Denmark)

    Normann, Leo; Agger Nielsen, Jeppe

    2015-01-01

    This article explores a new management form – cluster management – in Danish public sector day care. Although cluster management has been widely adopted in Danish day care at the municipality level, it has attracted only sparse research attention. We use theoretical insights from Scandinavian ins...

  5. Cluster Synchronization Algorithms

    NARCIS (Netherlands)

    Xia, Weiguo; Cao, Ming

    2010-01-01

    This paper presents two approaches to achieving cluster synchronization in dynamical multi-agent systems. In contrast to the widely studied synchronization behavior, where all the coupled agents converge to the same value asymptotically, in the cluster synchronization problem studied in this paper,

  6. Cost-Effective Clustering

    CERN Document Server

    Gottlieb, S

    2001-01-01

    Small Beowulf clusters can effectively serve as personal or group supercomputers. In such an environment, a cluster can be optimally designed for a specific problem (or a small set of codes). We discuss how theoretical analysis of the code and benchmarking on similar hardware lead to optimal systems.

  7. Relevant Subspace Clustering

    DEFF Research Database (Denmark)

    Müller, Emmanuel; Assent, Ira; Günnemann, Stephan;

    2009-01-01

    Subspace clustering aims at detecting clusters in any subspace projection of a high dimensional space. As the number of possible subspace projections is exponential in the number of dimensions, the result is often tremendously large. Recent approaches fail to reduce results to relevant subspace c...

  8. Job Oriented Monitoring Clusters

    Directory of Open Access Journals (Sweden)

    Vijayalaxmi Cigala,

    2011-03-01

    Full Text Available There has been a lot of development in the field of clusters and grids. Recently, the use of clusters has been on rise in every possible field. This paper proposes a system that monitors jobs onlarge computational clusters. Monitoring jobs is essential to understand how jobs are being executed. This helps us in understanding the complete life cycle of the jobs being executed on large clusters. Also, this paper describes how the information obtained by monitoring the jobs would help in increasing the overall throughput of clusters. Heuristics help in efficient job distribution among the computational nodes, thereby accomplishing fair job distribution policy. The proposed system would be capable of loadbalancing among the computational nodes, detecting failures, taking corrective actions after failure detection, job monitoring, system resource monitoring, etc.

  9. A Commodity Computing Cluster

    Science.gov (United States)

    Teuben, P. J.; Wolfire, M. G.; Pound, M. W.; Mundy, L. G.

    We have assembled a cluster of Intel-Pentium based PCs running Linux to compute a large set of Photodissociation Region (PDR) and Dust Continuum models. For various reasons the cluster is heterogeneous, currently ranging from a single Pentium-II 333 MHz to dual Pentium-III 450 MHz CPU machines. Although this will be sufficient for our ``embarrassingly parallelizable problem'' it may present some challenges for as yet unplanned future use. In addition the cluster was used to construct a MIRIAD benchmark, and compared to equivalent Ultra-Sparc based workstations. Currently the cluster consists of 8 machines, 14 CPUs, 50GB of disk-space, and a total peak speed of 5.83 GHz, or about 1.5 Gflops. The total cost of this cluster has been about $12,000, including all cabling, networking equipment, rack, and a CD-R backup system. The URL for this project is http://dustem.astro.umd.edu.

  10. Mathematical classification and clustering

    CERN Document Server

    Mirkin, Boris

    1996-01-01

    I am very happy to have this opportunity to present the work of Boris Mirkin, a distinguished Russian scholar in the areas of data analysis and decision making methodologies. The monograph is devoted entirely to clustering, a discipline dispersed through many theoretical and application areas, from mathematical statistics and combina­ torial optimization to biology, sociology and organizational structures. It compiles an immense amount of research done to date, including many original Russian de­ velopments never presented to the international community before (for instance, cluster-by-cluster versions of the K-Means method in Chapter 4 or uniform par­ titioning in Chapter 5). The author's approach, approximation clustering, allows him both to systematize a great part of the discipline and to develop many in­ novative methods in the framework of optimization problems. The optimization methods considered are proved to be meaningful in the contexts of data analysis and clustering. The material presented in ...

  11. Cool Cluster Correctly Correlated

    Energy Technology Data Exchange (ETDEWEB)

    Varganov, Sergey Aleksandrovich [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    Atomic clusters are unique objects, which occupy an intermediate position between atoms and condensed matter systems. For a long time it was thought that physical and chemical properties of atomic dusters monotonically change with increasing size of the cluster from a single atom to a condensed matter system. However, recently it has become clear that many properties of atomic clusters can change drastically with the size of the clusters. Because physical and chemical properties of clusters can be adjusted simply by changing the cluster's size, different applications of atomic clusters were proposed. One example is the catalytic activity of clusters of specific sizes in different chemical reactions. Another example is a potential application of atomic clusters in microelectronics, where their band gaps can be adjusted by simply changing cluster sizes. In recent years significant advances in experimental techniques allow one to synthesize and study atomic clusters of specified sizes. However, the interpretation of the results is often difficult. The theoretical methods are frequently used to help in interpretation of complex experimental data. Most of the theoretical approaches have been based on empirical or semiempirical methods. These methods allow one to study large and small dusters using the same approximations. However, since empirical and semiempirical methods rely on simple models with many parameters, it is often difficult to estimate the quantitative and even qualitative accuracy of the results. On the other hand, because of significant advances in quantum chemical methods and computer capabilities, it is now possible to do high quality ab-initio calculations not only on systems of few atoms but on clusters of practical interest as well. In addition to accurate results for specific clusters, such methods can be used for benchmarking of different empirical and semiempirical approaches. The atomic clusters studied in this work contain from a few atoms

  12. Clustering of HI galaxies in HIPASS and ALFALFA

    CERN Document Server

    Passmoor, S S; Faltenbacher, A

    2011-01-01

    We investigate the clustering of HI-selected galaxies in the ALFALFA survey and compare results with those obtained for HIPASS. Measurements of the angular correlation function and the inferred 3D-clustering are compared with results from direct spatial-correlation measurements. We are able to measure clustering on smaller angular scales and for galaxies with lower HI masses than was previously possible. We calculate the expected clustering of dark matter using the redshift distributions of HIPASS and ALFALFA and show that the ALFALFA sample is somewhat more anti-biased with respect to dark matter than the HIPASS sample.

  13. Galaxy Evolution in Rich Clusters

    Science.gov (United States)

    Schwarzkopf, U.; Hill, J. M.

    2000-12-01

    We present the first results of a study of the morphological and spectral evolution of galaxies within the dense cores of distant clusters at redshifts between z=0.4 and 1. The morphology, colors, concentration index, and asymmetry parameters of these cluster members are compared by using a combination of deep HST NICMOS and WFPC2 imaging, covering the rest-frame U and J bands. We also discuss the influence of dust obscuration on the derived measurements. Of particular interest is the morphology of galaxies at near-infrared wavelengths in rich clusters which show an excess of blue galaxies (Butcher-Oelmer effect), namely Abell 851 (z=0.4) and CL 1603+43 (z=0.92). We focus our study on optical/near-infrared measurements of galaxy asymmetry and central concentration, derived from a large number (>400) of objects detected within the core of Abell 851. The sensitivity and reliability of these parameters for galaxy classification and physical diagnostic purposes are tested. In conjunction with the use of recent source extraction software we are able to establish a fast, robust, and highly automated procedure of mapping the structural parameters of large galaxy samples. This work is supported by NASA, under contract NAS5-26555.

  14. Cluster Analysis and Clinical Asthma Phenotypes

    Science.gov (United States)

    Shaw, Dominic E.; Berry, Michael A.; Thomas, Michael; Brightling, Christopher E.; Wardlaw, Andrew J.

    2014-01-01

    Rationale Heterogeneity in asthma expression is multidimensional, including variability in clinical, physiologic, and pathologic parameters. Classification requires consideration of these disparate domains in a unified model. Objectives To explore the application of a multivariate mathematical technique, k-means cluster analysis, for identifying distinct phenotypic groups. Methods We performed k-means cluster analysis in three independent asthma populations. Clusters of a population managed in primary care (n = 184) with predominantly mild to moderate disease, were compared with a refractory asthma population managed in secondary care (n = 187). We then compared differences in asthma outcomes (exacerbation frequency and change in corticosteroid dose at 12 mo) between clusters in a third population of 68 subjects with predominantly refractory asthma, clustered at entry into a randomized trial comparing a strategy of minimizing eosinophilic inflammation (inflammation-guided strategy) with standard care. Measurements and Main Results Two clusters (early-onset atopic and obese, noneosinophilic) were common to both asthma populations. Two clusters characterized by marked discordance between symptom expression and eosinophilic airway inflammation (early-onset symptom predominant and late-onset inflammation predominant) were specific to refractory asthma. Inflammation-guided management was superior for both discordant subgroups leading to a reduction in exacerbation frequency in the inflammation-predominant cluster (3.53 [SD, 1.18] vs. 0.38 [SD, 0.13] exacerbation/patient/yr, P = 0.002) and a dose reduction of inhaled corticosteroid in the symptom-predominant cluster (mean difference, 1,829 μg beclomethasone equivalent/d [95% confidence interval, 307–3,349 μg]; P = 0.02). Conclusions Cluster analysis offers a novel multidimensional approach for identifying asthma phenotypes that exhibit differences in clinical response to treatment algorithms. PMID:18480428

  15. Ontology Partitioning: Clustering Based Approach

    Directory of Open Access Journals (Sweden)

    Soraya Setti Ahmed

    2015-05-01

    Full Text Available The semantic web goal is to share and integrate data across different domains and organizations. The knowledge representations of semantic data are made possible by ontology. As the usage of semantic web increases, construction of the semantic web ontologies is also increased. Moreover, due to the monolithic nature of the ontology various semantic web operations like query answering, data sharing, data matching, data reuse and data integration become more complicated as the size of ontology increases. Partitioning the ontology is the key solution to handle this scalability issue. In this work, we propose a revision and an enhancement of K-means clustering algorithm based on a new semantic similarity measure for partitioning given ontology into high quality modules. The results show that our approach produces meaningful clusters than the traditional algorithm of K-means.

  16. Preference clustering in customer satisfaction measurement

    DEFF Research Database (Denmark)

    Eskildsen, Jacob Kjær; Kristensen, Kai

    2006-01-01

    The scope of this paper is to analyze whether or not segments with different customer preferences and customer satisfaction can be identified. This analysis is based on customer satisfaction data from the Danish banking industry from the years 2004 and 2005. The analysis showed that the preference...

  17. Instantaneous normal mode analysis of melting of finite dust clusters.

    Science.gov (United States)

    Melzer, André; Schella, André; Schablinski, Jan; Block, Dietmar; Piel, Alexander

    2012-06-01

    The experimental melting transition of finite two-dimensional dust clusters in a dusty plasma is analyzed using the method of instantaneous normal modes. In the experiment, dust clusters are heated in a thermodynamic equilibrium from a solid to a liquid state using a four-axis laser manipulation system. The fluid properties of the dust cluster, such as the diffusion constant, are measured from the instantaneous normal mode analysis. Thereby, the phase transition of these finite clusters is approached from the liquid phase. From the diffusion constants, unique melting temperatures have been assigned to dust clusters of various sizes that very well reflect their dynamical stability properties.

  18. Atmospheric Ion Clusters: Properties and Size Distributions

    Science.gov (United States)

    D'Auria, R.; Turco, R. P.

    2002-12-01

    Ions are continuously generated in the atmosphere by the action of galactic cosmic radiation. Measured charge concentrations are of the order of 103 ~ {cm-3} throughout the troposphere, increasing to about 5 x 103 ~ {cm-3} in the lower stratosphere [Cole and Pierce, 1965; Paltridge, 1965, 1966]. The lifetimes of these ions are sufficient to allow substantial clustering with common trace constituents in air, including water, nitric and sulfuric acids, ammonia, and a variety of organic compounds [e.g., D'Auria and Turco, 2001 and references cited therein]. The populations of the resulting charged molecular clusters represent a pre-nucleation phase of particle formation, and in this regard comprise a key segment of the over-all nucleation size spectrum [e.g., Castleman and Tang, 1972]. It has been suggested that these clusters may catalyze certain heterogeneous reactions, and given their characteristic crystal-like structures may act as freezing nuclei for supercooled droplets. To investigate these possibilities, basic information on cluster thermodynamic properties and chemical kinetics is needed. Here, we present new results for several relevant atmospheric ion cluster families. In particular, predictions based on quantum mechanical simulations of cluster structure, and related thermodynamic parameters, are compared against laboratory data. We also describe a hybrid approach for modeling cluster sequences that combines laboratory measurements and quantum predictions with the classical liquid droplet (Thomson) model to treat a wider range of cluster sizes. Calculations of cluster mass distributions based on this hybrid model are illustrated, and the advantages and limitations of such an analysis are summarized. References: Castelman, A. W., Jr., and I. N. Tang, Role of small clusters in nucleation about ions, J. Chem. Phys., 57, 3629-3638, 1972. Cole, R. K., and E. T. Pierce, Electrification in the Earth's atmosphere for altitudes between 0 and 100 kilometers, J

  19. Cluster knockout reactions

    Indian Academy of Sciences (India)

    Arun K Jain; B N Joshi

    2014-04-01

    Cluster knockout reactions are expected to reveal the amount of clustering (such as that of , d and even of heavier clusters such as 12C, 16O etc.) in the target nucleus. In simple terms, incident medium high-energy nuclear projectile interacts strongly with the cluster (present in the target nucleus) as if it were existing as a free entity. Theoretically, the relatively softer interactions of the two outgoing particles with the residual nucleus lead to optical distortions and are treated in terms of distorted wave (DW) formalism. The long-range projectile–cluster interaction is accounted for, in terms of the finite range (FR) direct reaction formalism, as against the more commonly adopted zero-range (ZR) distorted wave impulse approximation (DWIA) formalism. Comparison of the DWIA calculations with the observed data provide information about the momentum distribution and the clustering spectroscopic factor of the target nucleus. Interesting results and some recent advancements in the area of (, 2) reactions and heavy cluster knockout reactions are discussed. Importance of the finite-range vertex and the final-state interactions are brought out.

  20. Software-Defined Cluster

    Institute of Scientific and Technical Information of China (English)

    聂华; 杨晓君; 刘淘英

    2015-01-01

    The cluster architecture has played an important role in high-end computing for the past 20 years. With the advent of Internet services, big data, and cloud computing, traditional clusters face three challenges: 1) providing flexible system balance among computing, memory, and I/O capabilities;2) reducing resource pooling overheads;and 3) addressing low performance-power efficiency. This position paper proposes a software-defined cluster (SDC) architecture to deal with these challenges. The SDC architecture inherits two features of traditional cluster: its architecture is multicomputer and it has loosely-coupled interconnect. SDC provides two new mechanisms: global I/O space (GIO) and hardware-supported native access (HNA) to remote devices. Application software can define a virtual cluster best suited to its needs from resources pools provided by a physical cluster, and traditional cluster ecosystems need no modification. We also discuss a prototype design and implementation of a 32-processor cloud server utilizing the SDC architecture.

  1. Spanning Tree Based Attribute Clustering

    DEFF Research Database (Denmark)

    Zeng, Yifeng; Jorge, Cordero Hernandez

    2009-01-01

    inconsistent edges from a maximum spanning tree by starting appropriate initial modes, therefore generating stable clusters. It discovers sound clusters through simple graph operations and achieves significant computational savings. We compare the Star Discovery algorithm against earlier attribute clustering...

  2. Textile Industrial Clusters in China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    "National Textile Industry Cluster Development Seminar" convened, held by China National Textile and Apparel Council, 23 cities and towns were awarded as China’s Textile Industry Cluster Pilot District. By far, China’s textile industrial clusters have grown

  3. Measurement of galaxy clustering at z ∼ 7.2 and the evolution of galaxy bias from 3.8 < z < 8 in the XDF, GOODS-S, and GOODS-N

    Energy Technology Data Exchange (ETDEWEB)

    Barone-Nugent, R. L.; Wyithe, J. S. B. [School of Physics, University of Melbourne, Parkville, Vic 3010 (Australia); Trenti, M. [Kavli Institute for Cosmology and Institute of Astronomy, University of Cambridge, Cambridge (United Kingdom); Bouwens, R. J.; Labbe, I. [Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands); Oesch, P. A.; Illingworth, G. D. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Carollo, C. M. [Institute for Astronomy, ETH Zurich, 8092 Zurich (Switzerland); Su, J. [Department of Radiology, Mayo Clinic, Rochester, MN 55905 (United States); Stiavelli, M. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Van Dokkum, P. G. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States)

    2014-09-20

    Lyman-break galaxy (LBG) samples observed during reionization (z ≳ 6) with the Hubble Space Telescope's Wide Field Camera 3 are reaching sizes sufficient to characterize their clustering properties. Using a combined catalog from the Hubble eXtreme Deep Field and CANDELS surveys, containing N = 743 LBG candidates at z ≥ 6.5 at a mean redshift of z-bar =7.2, we detect a clear clustering signal in the angular correlation function (ACF) at ≳ 4σ, corresponding to a real-space correlation length r{sub 0}=6.7{sub −1.0}{sup +0.9}h{sup −1}cMpc. The derived galaxy bias b=8.6{sub −1.0}{sup +0.9} is that of dark matter halos of M=10{sup 11.1{sub −}{sub 0}{sub .}{sub 3}{sup +{sup 0{sup .{sup 2}}}}} M{sub ⊙} at z = 7.2, and highlights that galaxies below the current detection limit (M{sub AB} ∼ –17.7) are expected in lower-mass halos (M ∼ 10{sup 8}-10{sup 10.5} M{sub ⊙} ). We compute the ACF of LBGs at z ∼ 3.8 – z ∼ 5.9 in the same surveys. A trend of increasing bias is found from z-bar =3.8 (b ∼ 3.0) to z-bar =7.2 (b ∼ 8.6), broadly consistent with galaxies at fixed luminosity being hosted in dark matter halos of similar mass at 4 ≲ z ≲ 6, followed by a slight rise in halo masses at z ≳ 7 (∼2σ confidence). Separating the data at the median luminosity of the z-bar =7.2 sample (M {sub UV} = –19.4) shows higher clustering at z-bar =5.9 for bright galaxies (r{sub 0}=5.5{sub −1.6}{sup +1.4}h{sup −1}cMpc, b=6.2{sub −1.5}{sup +1.2}) compared to faint galaxies (r{sub 0}=1.9{sub −1.0}{sup +1.1}h{sup −1}cMpc, b=2.7{sub −1.2}{sup +1.2}) implying a constant mass-to-light ratio (dlogM/dlogL)∼1.2{sub −0.8}{sup +1.8}. A similar trend is present in the z-bar =7.2 sample with larger uncertainty. Finally, our bias measurements allow us to investigate the fraction of dark matter halos hosting UV-bright galaxies (the duty cycle, ε{sub DC}). At z-bar =7.2 values near unity are preferred, which may be explained by the shortened halo

  4. THE FUNDAMENTAL PLANE OF RICH ABELL CLUSTERS

    Directory of Open Access Journals (Sweden)

    H. J. Ibarra

    2009-01-01

    Full Text Available In this study we found the existence of the FP for a final sample of 24 galaxy clusters, where sampling and signal to noise of the data allows a reliable analysis. For this purpose, we have introduced a new formalism for measure size and velocity dispersion. We found that indeed the parameter space of galaxy clusters accepts a FP (CFP R ¿ ¿1·19±0·12I¿8·18±0·44, proved the hypothesis of virialized central regions in clusters of galaxies. To do a more autoconsistent analysis we obtain the FP of galaxy clusters and found similarity to the CFP, given important consequences, showing that the mass-luminosity ratio should have the same functional form for the cluster galaxies and galaxy clusters. We showed that in fact the mass-luminosity ratio of clusters of galaxies (M/L ¿ L0·54±0·22 follows the same scaling law of elliptical galaxies. This result imposes a strong constraint to galaxies formation models.

  5. Allodynia in Cluster Headache.

    Science.gov (United States)

    Wilbrink, Leopoldine A; Louter, Mark A; Teernstra, Onno Pm; van Zwet, Erik W; Huygen, Frank Jpm; Haan, Joost; Ferrari, Michel D; Terwindt, Gisela M

    2017-03-04

    Cutaneous allodynia is an established marker for central sensitization in migraine. There is debate whether cutaneous allodynia may also occur in cluster headache, another episodic headache disorder. Here we examined the presence and severity of allodynia in a large well-defined nation-wide population of people with cluster headache.Using validated questionnaires we assessed, cross-sectionally, ictal allodynia and comorbid depression and migraine in the nation-wide "Leiden University Cluster headache neuro-Analysis" (LUCA) study. Participants with cluster headache were diagnosed according to the International Classification of Headache Disorders criteria. Multivariate regression models were used, with correction for demographic factors and cluster headache subtype (chronic vs. episodic; recent attacks cluster headache responded of whom 218/606 (36%) had allodynia during attacks. Female gender (OR 2.05, 95% CI 1.28-3.29), low age at onset (OR 0.98, 95% CI 0.96- 0.99), lifetime depression (OR 1.63; 95% CI 1.06-2.50), comorbid migraine (OR 1.96; 95% CI 1.02-3.79), and having recent attacks (OR 1.80; 95% CI 1.13-2.86), but not duration of attacks and chronic cluster headache, were independent risk factors for allodynia.The high prevalence of cutaneous allodynia with similar risk factors for allodynia as found for migraine suggests that central sensitization, like in migraine, also occurs in cluster headache. In clinical practice, awareness that people with cluster headache may suffer from allodynia can in the future be an important feature in treatment options.

  6. Introduction to cluster dynamics

    CERN Document Server

    Reinhard, Paul-Gerhard

    2008-01-01

    Clusters as mesoscopic particles represent an intermediate state of matter between single atoms and solid material. The tendency to miniaturise technical objects requires knowledge about systems which contain a ""small"" number of atoms or molecules only. This is all the more true for dynamical aspects, particularly in relation to the qick development of laser technology and femtosecond spectroscopy. Here, for the first time is a highly qualitative introduction to cluster physics. With its emphasis on cluster dynamics, this will be vital to everyone involved in this interdisciplinary subje

  7. ClusterAlive

    Science.gov (United States)

    Caruso, G.; Arezzini, S.; Ciampa, A.; Formuso, A.; Mazzoni, E.

    2015-12-01

    INFN-Pisa Scientific Computing Center is working from many years both in GRID and HPC computing. The monitoring and managing tools have been key components of the center's successful operation. The lessons learned from the use of standard tools, such as Ganglia, have been starting points for the development of new tools specific for our infrastructure. In this note we will illustrate the integration of many different monitoring tools in one single platform called ClusterAlive. Aim of ClusterAlive is to increase the HPC cluster performance and simplify maintenance operations, possibly in a proactive approach.

  8. Raspberry Pi super cluster

    CERN Document Server

    Dennis, Andrew K

    2013-01-01

    This book follows a step-by-step, tutorial-based approach which will teach you how to develop your own super cluster using Raspberry Pi computers quickly and efficiently.Raspberry Pi Super Cluster is an introductory guide for those interested in experimenting with parallel computing at home. Aimed at Raspberry Pi enthusiasts, this book is a primer for getting your first cluster up and running.Basic knowledge of C or Java would be helpful but no prior knowledge of parallel computing is necessary.

  9. Cluster modular autocontenido

    OpenAIRE

    2009-01-01

    Desde hace años es común en organizaciones educativas y de investigación el desarrollo de actividades que requieren grandes capacidades de cálculo. La solución más común a estas necesidades es la compra o construcción de un cluster HPC (High Performance Computing), pero construir un cluster acarrea problemas y costos inesperados problemas al momento de utilizarlo y mantenerlo en operaciones. Nuestro proyecto busca desarrollar y documentar técnicas para construir un cluster HPC que sea fácilme...

  10. Extending Beowulf Clusters

    Science.gov (United States)

    Steinwand, Daniel R.; Maddox, Brian; Beckmann, Tim; Hamer, George

    2003-01-01

    Beowulf clusters can provide a cost-effective way to compute numerical models and process large amounts of remote sensing image data. Usually a Beowulf cluster is designed to accomplish a specific set of processing goals, and processing is very efficient when the problem remains inside the constraints of the original design. There are cases, however, when one might wish to compute a problem that is beyond the capacity of the local Beowulf system. In these cases, spreading the problem to multiple clusters or to other machines on the network may provide a cost-effective solution.

  11. Q+: characterizing the structure of young star clusters

    Science.gov (United States)

    Jaffa, S. E.; Whitworth, A. P.; Lomax, O.

    2017-04-01

    Many young star clusters appear to be fractal, i.e. they appear to be concentrated in a nested hierarchy of clusters within clusters. We present a new algorithm for statistically analysing the distribution of stars to quantify the level of substructure. We suggest that, even at the simplest level, the internal structure of a fractal cluster requires the specification of three parameters. (i) The 3D fractal dimension, D, measures the extent to which the clusters on one level of the nested hierarchy fill the volume of their parent cluster. (ii) The number of levels, L, reflects the finite ratio between the linear size of the large root-cluster at the top of the hierarchy, and the smallest leaf-clusters at the bottom of the hierarchy. (iii) The volume-density scaling exponent, C = -d ln [δ n]/d ln [L] measures the factor by which the excess density, δn, in a structure of scale L, exceeds that of the background formed by larger structures; it is similar, but not exactly equivalent, to the exponent in Larson's scaling relation between density and size for molecular clouds. We describe an algorithm that can be used to constrain the values of (D,L,C) and apply this method to artificial and observed clusters. We show that this algorithm is able to reliably describe the three-dimensional structure of an artificial star cluster from the two-dimensional projection, and quantify the varied structures observed in real and simulated clusters.

  12. Combining cluster number counts and galaxy clustering

    Science.gov (United States)

    Lacasa, Fabien; Rosenfeld, Rogerio

    2016-08-01

    The abundance of clusters and the clustering of galaxies are two of the important cosmological probes for current and future large scale surveys of galaxies, such as the Dark Energy Survey. In order to combine them one has to account for the fact that they are not independent quantities, since they probe the same density field. It is important to develop a good understanding of their correlation in order to extract parameter constraints. We present a detailed modelling of the joint covariance matrix between cluster number counts and the galaxy angular power spectrum. We employ the framework of the halo model complemented by a Halo Occupation Distribution model (HOD). We demonstrate the importance of accounting for non-Gaussianity to produce accurate covariance predictions. Indeed, we show that the non-Gaussian covariance becomes dominant at small scales, low redshifts or high cluster masses. We discuss in particular the case of the super-sample covariance (SSC), including the effects of galaxy shot-noise, halo second order bias and non-local bias. We demonstrate that the SSC obeys mathematical inequalities and positivity. Using the joint covariance matrix and a Fisher matrix methodology, we examine the prospects of combining these two probes to constrain cosmological and HOD parameters. We find that the combination indeed results in noticeably better constraints, with improvements of order 20% on cosmological parameters compared to the best single probe, and even greater improvement on HOD parameters, with reduction of error bars by a factor 1.4-4.8. This happens in particular because the cross-covariance introduces a synergy between the probes on small scales. We conclude that accounting for non-Gaussian effects is required for the joint analysis of these observables in galaxy surveys.

  13. Toward optimal cluster power spectrum analysis

    CERN Document Server

    Smith, Robert E

    2014-01-01

    The power spectrum of galaxy clusters is an important probe of the cosmological model. In this paper we determine the optimal weighting scheme for maximizing the signal-to-noise ratio for such measurements. We find a closed form analytic expression for the optimal weights. Our expression takes into account: cluster mass, finite survey volume effects, survey masking, and a flux limit. The implementation of this weighting scheme requires knowledge of the measured cluster masses, and analytic models for the bias and space-density of clusters as a function of mass and redshift. Recent studies have suggested that the optimal method for reconstruction of the matter density field from a set of clusters is mass-weighting (Seljak et al 2009, Hamaus et al 2010, Cai et al 2011). We compare our optimal weighting scheme with this approach and also with the original power spectrum scheme of Feldman et al (1994). We show that our optimal weighting scheme outperforms these approaches for both volume- and flux-limited cluster...

  14. Simulated annealing spectral clustering algorithm for image segmentation

    Institute of Scientific and Technical Information of China (English)

    Yifang Yang; and Yuping Wang

    2014-01-01

    The similarity measure is crucial to the performance of spectral clustering. The Gaussian kernel function based on the Euclidean distance is usual y adopted as the similarity mea-sure. However, the Euclidean distance measure cannot ful y reveal the complex distribution data, and the result of spectral clustering is very sensitive to the scaling parameter. To solve these problems, a new manifold distance measure and a novel simulated anneal-ing spectral clustering (SASC) algorithm based on the manifold distance measure are proposed. The simulated annealing based on genetic algorithm (SAGA), characterized by its rapid conver-gence to the global optimum, is used to cluster the sample points in the spectral mapping space. The proposed algorithm can not only reflect local and global consistency better, but also reduce the sensitivity of spectral clustering to the kernel parameter, which improves the algorithm’s clustering performance. To efficiently ap-ply the algorithm to image segmentation, the Nystr¨om method is used to reduce the computation complexity. Experimental re-sults show that compared with traditional clustering algorithms and those popular spectral clustering algorithms, the proposed algorithm can achieve better clustering performances on several synthetic datasets, texture images and real images.

  15. Star Cluster Luminosity Functions and Cluster Formation Efficiencies in LEGUS Dwarf Galaxies

    Science.gov (United States)

    Cook, David O.; Lee, Janice C.; Adamo, Angela; Kim, Hwiyun; Ryon, Jenna E.; LEGUS Team

    2017-01-01

    We present preliminary results of star cluster luminosity functions (LFs) and cluster formation efficiencies (Γ) in the LEGUS dwarf galaxy sub-sample. We have used a combination of automated and visual identification techniques to allow us to construct a more complete sample of clusters in these low-mass, low-SFR environments compared to previous studies of dwarf galaxies. Cluster properties are derived from fitting UV and optical (NUV-I) HST photometry to both deterministic and stochastic single-aged stellar populations models. We compare the cluster formation efficiencies and LF slopes to those of previous studies in both dwarf and massive spiral galaxy environments. Recent studies have found that both the LF slope and Γ form trends with galaxy environment. Our LF slope and Γ measurements in the LEGUS dwarfs will allow us to test these trends in the extreme, low-SFR regime and provide a better understanding of the star formation process.

  16. Spatial Clustering from GALEX-SDSS samples: Star Formation History and large-scale clustering

    CERN Document Server

    Heinis, Sebastien; Szalay, A S; Arnouts, Stephane; Aragon-Calvo, Miguel A; Wyder, Ted K; Barlow, Tom A; Foster, Karl; Friedman, Peter G; Martin, D Christopher; Morrissey, Patrick; Neff, Susan G; Schiminovich, David; Seibert, Mark; Bianchi, Luciana; Donas, Jose; Heckman, Timothy M; Lee, Young-Wook; Madore, Barry F; Milliard, Bruno; Rich, R Michael; Yi, Sukyoung K

    2009-01-01

    We measure the projected spatial correlation function w_p(r_p) from a large sample combining GALEX ultraviolet imaging with the SDSS spectroscopic sample. We study the dependence of the clustering strength for samples selected on (NUV - r)_abs color, specific star formation rate (SSFR), and stellar mass. We find that there is a smooth transition in the clustering of galaxies as a function of this color from weak clustering among blue galaxies to stronger clustering for red galaxies. The clustering of galaxies within the "green valley" has an intermediate strength, and is consistent with that expected from galaxy groups. The results are robust to the correction for dust extinction. The comparison with simple analytical modeling suggests that the halo occupation number increases with older star formation epochs. When splitting according to SSFR, we find that the SSFR is a more sensitive tracer of environment than stellar mass.

  17. Oxidative-addition reactions of cyclometallated platinum(II) compounds with mercury(II) carboxylates. X-ray, crystal and molecular structure of rac-[a-(m-MeCO2)-cf,de-(2-Me2NCH2C6H4)2PtHg(O2CMe)

    NARCIS (Netherlands)

    Koten, G. van; Ploeg, A.F.M.J. van der; Vrieze, K.; Spek, A.L.

    1982-01-01

    The reactions of C~~-[(~-M~~NCo~btHain~edC fHrom~ )[P~tCP12~(S~Et2])2,a] n d [(2-MeJW6H4CH2)Li(TMEDA)] (TMEDA = tetramethylethylenediamine), and of cis-[( 2-Me2NCH2C6H4)2Pt1w1]i th Hg11(02CR)2( R = Me, i-Pr) yielded a novel type of cyclometalated Pt-Hg compound [(N-C)2(RCOJPtHg(02CR)] (N-C = 2-Me@C6

  18. Chirality in thiolate-protected gold clusters.

    Science.gov (United States)

    Knoppe, Stefan; Bürgi, Thomas

    2014-04-15

    Over recent years, research on thiolate-protected gold clusters Au(m)(SR)n has gained significant interest. Milestones were the successful determination of a series of crystal structures (Au102(SR)44, Au25(SR)18, Au38(SR)24, Au36(SR)24, and Au28(SR)20). For Au102(SR)44, Au38(SR)24, and Au28(SR)20, intrinsic chirality was found. Strong Cotton effects (circular dichroism, CD) of gold clusters protected by chiral ligands have been reported a long time ago, indicating the transfer of chiral information from the ligand into the cluster core. Our lab has done extensive studies on chiral thiolate-protected gold clusters, including those protected with chiral ligands. We demonstrated that vibrational circular dichroism can serve as a useful tool for the determination of conformation of the ligand on the surface of the cluster. The first reports on crystal structures of Au102(SR)44 and Au38(SR)24 revealed the intrinsic chirality of these clusters. Their chirality mainly arises from the arrangement of the ligands on the surface of the cluster cores. As achiral ligands are used to stabilize the clusters, racemic mixtures are obtained. However, the separation of the enantiomers by HPLC was demonstrated which enabled the measurement of their CD spectra. Thermally induced inversion allows determination of the activation parameters for their racemization. The inversion demonstrates that the gold-thiolate interface is anything but fixed; in contrast, it is rather flexible. This result is of fundamental interest and needs to be considered in future applications. A second line of our research is the selective introduction of chiral, bidentate ligands into the ligand layer of intrinsically chiral gold clusters. The ligand exchange reaction is highly diastereoselective. The bidentate ligand connects two of the protecting units on the cluster surface and thus effectively stabilizes the cluster against thermally induced inversion. A minor (but significant) influence of chiral ligands to

  19. Nuclear deformation effects in the cluster radioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Misicu, S. [Department of Theoretical Physics, NINPE-HH, Bucharest-Magurele (Romania); Protopopescu, D. [Frank Laboratory of Neutron Physics, JINR, Dubna (Russian Federation)

    1999-01-01

    We investigate the influence of the nuclear deformation on the decay rates of some cluster emission processes. The interaction between the daughter and the cluster is given by a double folding potential including quadrupole and hexadecapole deformed densities of both fragments. The nuclear part of the nucleus-nucleus interaction is density dependent and at small distances a repulsive core in the potential will occur. In the frame of the WKB-approximation the assault frequency of the cluster will depend on the geometric properties of the potential pocket whereas the penetrability will be sensitive to changes in the barrier location. The results obtained in this paper point out that various combinations of cluster and daughter deformations may account for the measured values of the decay rate. The decay rates are however more sensitive to the changes in the daughter deformation due to the large mass asymmetry of the process. (author) 10 refs, 6 figs, 1 tab

  20. Nuclear Deformation Effects in the Cluster Radioactivity

    Science.gov (United States)

    Misicu, Serban; Protopopescu, Dan

    1999-01-01

    We investigate the influence of the nuclear deformation on the decay rates of some cluster emission processes. The interaction between the daughter and the cluster is given by a double folding potential including quadrupole and hexadecupole deformed densities of both fragments. The nuclear part of the nucleus--nucleus interaction is density dependent and at small distances a repulsive core in the potential will occur. In the frame of the WKB-approximation the assault frequency of the cluster will depend on the geometric properties of the potential pocket whereas the penetrability will be sensitive to changes in the barrier location. The results obtained in this paper point out that various combinations of cluster and daughter deformations may account for the measured values of the decay rate. The decay rates are however more sensitive to the changes in the daughter deformation due to the large mass asymmetry of the process.