WorldWideScience

Sample records for 2-pt clustering measurements

  1. Ti/HfO2/Pt阻变存储单元中的氧空位聚簇分布%Cluster distribution for oxygen vacancy in Ti/HfO2/Pt resistive switching memory device

    蒋然; 杜翔浩; 韩祖银; 孙维登

    2015-01-01

    The origin of the resistance switching behavior in HfO2 is explained in terms of filament formation/rupture under an applied voltage. In order to investigate the position and process of conductive filament in resistive switching memory, the resistive switching and chemical structure of Ti/HfO2/Pt memory device are studied. Through current-voltage measurement, typical resistive switching behavior is observed in Ti/HfO2/Pt device cells; through detecting Hf 4f with different depths by using X-ray photoelectron spectroscopy. It is observed that the Hf4+ decreases monotonically with depth increasing towards HfO2/Pt interface in low resistance state, while a fluctuation distribution of Hf4+ is shown in high resistance state and in the pristine Ti/HfO2/Pt device. The concentration of Hf4+ in high resistance state is higher than that in low resistance state, which is confirmed by measuring the electron energy loss spectrum. Additionally, the O 1s spectrum shows a similar result consistent with the Hf 4f one. The above result is explained by the existence of locally accumulated oxygen vacancies in the oxide bulk layer in high resistance state and pristine states. It is proposed that the oxygen vacancy clusters dominantly determine the resistivity by the connecting/rupture between the neighbor cluster sites in the bulk. The cluster defects are the preexisting structural distortion/injure by charge trapping defects due to the fixed charge which could confine the nucleation of oxygen vacancies and bigger distortion could be enhanced or recovered via the transportation of oxygen vacancies under the external voltage. Oxygen vacancies are driven away from the clusters under SET electrical stimulus, and then recover back to original cluster sites under RESET process. The previous presumption of the ideal evenly-distributed state for oxygen vacancies in the bulk of resistance random access memories (RRAMs) device leads to an issue about where the filaments occur/form first since

  2. Measuring Volatility Clustering in Stock Markets

    Gabjin Oh; Seunghwan Kim; Cheoljun Eom; Taehyuk Kim

    2007-01-01

    We propose a novel method to quantify the clustering behavior in a complex time series and apply it to a high-frequency data of the financial markets. We find that regardless of used data sets, all data exhibits the volatility clustering properties, whereas those which filtered the volatility clustering effect by using the GARCH model reduce volatility clustering significantly. The result confirms that our method can measure the volatility clustering effect in financial market.

  3. Disentangling correlated scatter in cluster mass measurements

    Noh, Yookyung

    2012-01-01

    The challenge of obtaining galaxy cluster masses is increasingly being addressed by multiwavelength measurements. As scatters in measured cluster masses are often sourced by properties of or around the clusters themselves, correlations between mass scatters are frequent and can be significant, with consequences for errors on mass estimates both directly and those obtained via stacking. Using a high resolution 250 Mpc/h side N-body simulation, combined with proxies for observational cluster mass measurements, we obtain mass scatter correlations and covariances for 243 individual clusters along ~96 lines of sight each, both separately and together. We use principal component analysis (PCA) to characterize scatter trends and variations between clusters. The dominant mass scatter combination identified by PCA is common to many clusters, and tends to dominate the mass scatters when viewing the cluster along its long axis. We also correlate cluster mass scatter, environmental and intrinsic properties, and use PCA t...

  4. Cluster Tree Based Hybrid Document Similarity Measure

    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.

  5. Atmospheric Measurements of Neutral Nucleating Clusters (Invited)

    Zhao, J.; Eisele, F. L.; Smith, J. N.; Chen, M.; Jiang, J.; Kuang, C.; McMurry, P. H.

    2010-12-01

    Nanoparticles produced by nucleation can subsequently grow to cloud condensation nuclei (CCN) within one or two days and hence affect cloud formation, precipitation, and atmospheric radiation budgets. As an intermediate stage between molecules and nanoparticles, neutral molecular clusters are believed to play an important role in processes that lead to boundary layer nucleation. Therefore, knowledge of chemical composition, concentrations, thermodynamic properties, and evolution of neutral molecular clusters is essential to better elucidate the nucleation mechanism and to reduce the uncertainty in nucleation rates used in global climate models. Here we present laboratory and field measurements from a recently developed chemical ionization mass spectrometer (the Cluster-CIMS) designed to measure atmospheric neutral clusters (Zhao et al., 2010). The sensitivity of the Cluster-CIMS was significantly improved by using a unique conical octopole device in the first vacuum stage for transmitting and focusing ions, which was further confirmed by ion trajectory simulations using SIMION. The ion cluster formation in the atmospheric-pressure inlet was controlled by two processes: neutral ionization and ion-induced clustering (IIC), which can be differentiated from the time independency of the intensity ratio between the cluster and monomer ions. Two methods were employed to separate neutral clusters from the ion-induced clustering. The concentrations and distribution of the neutral nucleating clusters containing up to 4 H2SO4 are estimated from the above methods at three measurement sites in the US (NCAR foothill laboratory, Manitou Forest Observatory, and Atlanta). Typically, the molecular cluster concentrations are well correlated with the concentrations of nanoparticles measured simultaneously during the nucleation event periods. The Cluster-CIMS was employed to measure clusters containing both sulfuric acid and amines in summer 2010 at NCAR foothill laboratory

  6. Clustering of Sun Exposure Measurements

    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...

  7. Measuring the growth of galaxy clusters

    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.

  8. Gibbs cluster measures on configuration spaces

    Bogachev, Leonid

    2010-01-01

    The distribution $g_{cl}$ of a Gibbs cluster point process in $X=\\mathbb{R}^{d}$ (with i.i.d. random clusters attached to points of a Gibbs configuration with distribution $g$) is studied via the projection of an auxiliary Gibbs measure $\\hat{g}$ in the space of configurations $\\hat{gamma}=\\{(x,\\bar{y})\\}\\subset X\\times\\mathfrak{X}$, where $x\\in X$ indicates a cluster "center" and $\\bar{y}\\in\\mathfrak{X}:=\\bigsqcup_{n} X^n$ represents a corresponding cluster relative to $x$. We show that the measure $g_{cl}$ is quasi-invariant with respect to the group $\\mathrm{Diff}_{0}(X)$ of compactly supported diffeomorphisms of $X$, and prove an integration-by-parts formula for $g_{cl}$. The associated equilibrium stochastic dynamics is then constructed using the method of Dirichlet forms. These results are quite general; in particular, the uniqueness of the background Gibbs measure $g$ is not required. The paper is an extension of the earlier results for Poisson cluster measures %obtained by the authors [J. Funct. Analy...

  9. On the NP-Completeness of Some Graph Cluster Measures

    Sima, Jiri; Schaeffer, Satu Elisa

    2005-01-01

    Graph clustering is the problem of identifying sparsely connected dense subgraphs (clusters) in a given graph. Proposed clustering algorithms usually optimize various fitness functions that measure the quality of a cluster within the graph. Examples of such cluster measures include the conductance, the local and relative densities, and single cluster editing. We prove that the decision problems associated with the optimization tasks of finding the clusters that are optimal with respect to the...

  10. External Evaluation Measures for Subspace Clustering

    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...... evaluation. Typically, publications glorify the high quality of one approach only justified by an arbitrary evaluation measure. However, such conclusions can only be drawn if the evaluation measures themselves are fully understood. In this paper, we provide the basis for systematic evaluation in the emerging...... research area of subspace clustering. We formalize general quality criteria for subspace clustering measures not yet addressed in the literature. We compare the existing external evaluation methods based on these criteria and pinpoint limitations. We propose a novel external evaluation measure which meets...

  11. A Test for Cluster Bias: Detecting Violations of Measurement Invariance across Clusters in Multilevel Data

    Jak, Suzanne; Oort, Frans J.; Dolan, Conor V.

    2013-01-01

    We present a test for cluster bias, which can be used to detect violations of measurement invariance across clusters in 2-level data. We show how measurement invariance assumptions across clusters imply measurement invariance across levels in a 2-level factor model. Cluster bias is investigated by testing whether the within-level factor loadings…

  12. Quantum measurement problem and cluster separability

    Hajicek, Petr

    2010-01-01

    A modified Beltrametti-Cassinelli-Lahti model of measurement apparatus that satisfies both the probability reproducibility condition and the objectification requirement is constructed. Only measurements on microsystems are considered. The cluster separability forms a basis for the first working hypothesis: the current version of quantum mechanics leaves open what happens to systems when they change their separation status. New rules that close this gap can therefore be added without disturbin...

  13. Similarity measures for clustering sequences and sets of data

    García García, Darío

    2011-01-01

    The main object of this PhD. Thesis is the definition of new similarity measures for data sequences, with the final purpose of clustering those sequences. Clustering consists in the partitioning of a dataset into isolated subsets or clusters. Data within a given cluster should be similar, and at the same different from data in other clusters. The relevance of data sequences clustering is ever-increasing, due to the abundance of this kind of data (multimedia sequences, movement analysis, stock...

  14. Clustering and Bias Measurements of SDSS Voids

    Clampitt, Joseph; Sánchez, Carles

    2015-01-01

    Using a void catalog from the SDSS survey, we present the first measurements of void clustering and the corresponding void bias. Over the range 30-200 Mpc/h the void auto-correlation is detected at 5-sigma significance for voids of radius 15-20 Mpc/h. We also measure the void-galaxy cross-correlation at higher signal-to-noise and compare the inferred void bias with the autocorrelation results. Void bias is constant with scale for voids of a given size, but its value falls from 5.6 +/- 1.0 to below zero as the void radius increases from 15 to 30 Mpc/h. The comparison of our measurements with carefully matched galaxy mock catalogs, with no free parameters related to the voids, shows that model predictions can be reliably made for void correlations. We study the dependence of void bias on tracer density and void size with a view to future applications. In combination with our previous lensing measurements of void mass profiles, these clustering measurements provide another step towards using voids as cosmologica...

  15. NetCluster: A clustering-based framework to analyze internet passive measurements data

    Chiaraviglio, Luca; Bianco, Andrea; Baralis, Elena Maria; Mellia, Marco; Cerquitelli, Tania

    2013-01-01

    Internet measured data collected via passive measurement are analyzed to obtain localization information on nodes by clustering (i.e., grouping together) nodes that exhibit similar network path properties. Since traditional clustering algorithms fail to correctly identify clusters of homogeneous nodes, we propose the NetCluster novel framework, suited to analyze Internet measurement datasets. We show that the proposed framework correctly analyzes synthetically generated traces. Finally, we ap...

  16. Magnetic ordering of new intermetallic compound Tb2PtSi3

    The new ternary intermetallic compound Tb2PtSi3 crystallizing in the ordered hexagonal structure has been studied by means of susceptibility, magnetization, magnetic relaxation, specific heat and electrical resistivity measurements. The results reveal that Tb2PtSi3 orders ferromagnetically below Tc = 22 K and undergoes an additional magnetic phase transition near T1 = 10 K. The distribution of two kinds of Tb atoms at crystallographically non-equivalent positions seems to be responsible for the complex magnetic structure. Below Tc, cleary irreversible magnetism and the phenomenon of long time magnetic relaxation are observed in this system and discussed in terms of domain-wall pinning effects. (author)

  17. Understanding of cluster size deviation by measuring the dimensions of cluster jet from conical nozzles

    Chen, Guanglong; Geng, Xiaotao; Xu, Hongxia; Mi, Yiming; Zhang, Xiuli; Wang, Lili; Kim, Dong Eon

    2013-03-01

    This work aims to understand the cluster size deviation from the prediction by an existing scaling law for conical nozzles. The dimensions of cluster jet at different heights above a nozzle along the direction of gas flow are measured. This study indicates that the dimension of cluster jet is underestimated in the existing scaling law and this under-estimation leads to the over-estimation of the equivalent diameter of conical nozzle. Thus the underestimation of the dimension of cluster jet may be one of possible factors responsible for the cluster size deviation (the degree of the deviation depends on details of cluster jet).

  18. Clustering function: a measure of social influence

    Bloznelis, Mindaugas; Kurauskas, Valentas

    2012-01-01

    A commonly used characteristic of statistical dependence of adjacency relations in real networks, the clustering coefficient, evaluates chances that two neighbours of a given vertex are adjacent. An extension is obtained by considering conditional probabilities that two randomly chosen vertices are adjacent given that they have r common neighbours. We denote such probabilities cl(r) and call r-> cl(r) the clustering function. We compare clustering functions of several networks having non-negl...

  19. Limitations on Precision Cosmology using Mass Measurements of Galaxy Clusters

    Hallman, E J; Burns, J O; Norman, M L; Hallman, Eric J.; Motl, Patrick M.; Burns, Jack O.; Norman, Michael L.

    2005-01-01

    We critically analyze the role of clusters of galaxies as probes for precision cosmology. Using synthetic observations of numerically simulated clusters viewed through their X-ray emission and thermal Sunyaev-Zeldovich effect (SZE), we reduce the observations to attain measurements of the cluster gas mass. We utilize both parametric models such as the isothermal cluster model and non-parametric models that involve the geometric deprojection of the cluster emission assuming spherical symmetry. We are thus able to quantify the possible sources of uncertainty and systematic bias associated with the common simplifying assumptions used in reducing real cluster observations including isothermality and hydrostatic equilibrium. We find that intrinsic variations in clusters limit the precision of observational gas mass estimation to ~10% to 80% confidence excluding instrumental effects. For the full cluster sample, methods that use SZE profiles out to roughly the virial radius are the most accurate and precise way to ...

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

    Ntampaka, Michelle; Trac, Hy; Sutherland, Dougal; Fromenteau, Sebastien; Poczos, Barnabas; Schneider, Jeff

    2016-01-01

    Galaxy clusters are a rich source of information for examining fundamental astrophysical processes and cosmological parameters, however, employing clusters as cosmological probes requires accurate mass measurements derived from cluster observables. 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 a mock catalog from Multidark's publicly-available N-body MDPL1 simulation 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. The presence of interlopers in the catalog produces a wide, flat fractional mass error distribution, with 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 distributions of galaxy observables such as LOS velocity and projected distance from the cluster center, SDM yields better than a factor-of-two improvement (width = 0.67). Remarkably, SDM applied to contaminated clusters is better able to recover masses than even a 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.

  1. A Survey on Internal Validity Measure for Cluster Validation

    L.Jegatha Deborah

    2010-12-01

    Full Text Available Data Clustering is a technique of finding similar characteristics among the data set which are always hidden in nature and grouping them into groups, called as clusters. Different clustering algorithms exhibit different results, since they are very sensitive to the characteristics of original data set especially noise and dimension. The quality of such clustering process determines the purity of cluster and hence it is very important to evaluate the results of the clustering algorithm. Due to this, Cluster validation activity had been a major and challenging task. The major factor which influences cluster validation is the internal cluster validity measure of choosing the optimal number of clusters. The main objective of this article is to present a detailed description of the mathematical working of few cluster validity indices and not all, to classify these indices and to explore the ideas for the future promotion of the work in the domain of cluster validation. In addition to this, a maximization objective function is defined assuming to provide a cluster validation activity.

  2. Applicability of condensation particle counters to measure atmospheric clusters

    Sipilä, M.; Lehtipalo, K.; M. Kulmala; T. Petäjä; Junninen, H.; Aalto, P.P.; Manninen, H. E.; E.-M. Kyrö; Asmi, E.; Riipinen, I; J. Curtius; A. Kürten; S. Borrmann; C. D. O'Dowd

    2008-01-01

    The ambient and laboratory molecular and ion clusters were investigated. Here we present data on the ambient concentrations of both charged and uncharged molecular clusters as well as the performance of a pulse height condensation particle counter (PH-CPC) and an expansion condensation particle counter (E-CPC). The ambient molecular cluster concentrations were measured using both instruments, and they were deployed in conjunction with ion spectrometers and other aerosol instruments in Hyytiäl...

  3. Measuring Gravitational Redshifts in Galaxy Clusters

    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...

  4. Investigation of chemical distribution in the oxide bulk layer in Ti/HfO{sub 2}/Pt memory devices using x-ray photoelectron spectroscopy

    Jiang, Ran; Du, Xianghao; Han, Zuyin; Sun, Weideng [School of Physics, Shandong University, Jinan, Shandong 250100 (China)

    2015-04-27

    Resistive switching (RS) of Ti/HfO{sub 2}/Pt memory devices was studied using X-ray photoelectron spectroscopy. Hf{sup 4+} monotonously decreases with depth increasing towards to HfO{sub 2}/Pt interface in low resistance state, while a fluctuation distribution of Hf{sup 4+} is shown in high resistance state (HRS) and in the pristine Ti/HfO{sub 2}/Pt devices (without any SET or RESET process). It is explained by the existence of locally accumulated oxygen vacancies (clusters) in the oxide bulk layer in HRS and pristine states. A dynamic model of RS processes was proposed that the oxygen vacancy clusters dominantly determines the resistivity by the connecting/rupture between the neighbor cluster sites in the bulk.

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

    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...

  6. A new method to measure the mass of galaxy clusters

    Falco, Martina; Wojtak, Radoslaw; Brinckmann, Thejs; Lindholmer, Mikkel; Pandolfi, Stefania

    2013-01-01

    The mass measurement of galaxy clusters is an important tool for the determination of cosmological parameters describing the matter and energy content of the Universe. However, the standard methods rely on various assumptions about the shape or the level of equilibrium of the cluster. We present a novel method of measuring cluster masses. It is complementary to most of the other methods, since it only uses kinematical information from outside the virialized cluster. Our method identifies objects, as galaxy sheets or filaments, in the cluster outer region, and infers the cluster mass by modeling how the massive cluster perturbs the motion of the structures from the Hubble flow. At the same time, this technique allows to constrain the three-dimensional orientation of the detected structures with a good accuracy. We use a cosmological numerical simulation to test the method. We then apply the method to the Coma cluster, where we find two galaxy sheets, and measure the mass of Coma to be Mvir=(9.2\\pm2.4)10^{14} M...

  7. Gaussian covariance matrices for anisotropic galaxy clustering measurements

    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...

  8. The Mass Accretion Rate of Galaxy Clusters: A Measurable Quantity

    De Boni, C.; Serra, A. L.; Diaferio, A.; Giocoli, C.; Baldi, M.

    2016-02-01

    We explore the possibility of measuring the mass accretion rate (MAR) of galaxy clusters from their mass profiles beyond the virial radius R200. We derive the accretion rate from the mass of a spherical shell whose inner radius is 2R200, whose thickness changes with redshift, and whose infall velocity is assumed to be equal to the mean infall velocity of the spherical shells of dark matter halos extracted from N-body simulations. This approximation is rather crude in hierarchical clustering scenarios where both smooth accretion and aggregation of smaller dark matter halos contribute to the mass accretion of clusters. Nevertheless, in the redshift range z = [0, 2], our prescription returns an average MAR within 20%-40% of the average rate derived from the merger trees of dark matter halos extracted from N-body simulations. The MAR 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. Since the measurement of the mass profile of clusters beyond their virial radius can be performed with the caustic technique applied to dense redshift surveys of the cluster outer regions, our result suggests that measuring the mean MAR of a sample of galaxy clusters is actually feasible. We thus provide a new potential observational test of the cosmological and structure formation models.

  9. Time expansion chamber and single ionization cluster measurement

    The time expansion chamber (TEC), a new type of drift chamber, allows the measurement of microscopic details of ionization. The mean drift time interval from subsequent sngle ionization clusters of a relativistic particle in the TEC can be made large enough compared to the width of a anode signal to allow the recording of the clusters separately. Since single primary electrons can be detected, the cluster counting would allow an improved particle separation using the relativistic rise of primary ionization. In another application, very high position accuracy for track detectors or improved energy resolution may be obtained. Basic ionization phenomena and drift properties can be measured at the single electron level

  10. Measures of between-cluster variability in cluster randomized trials with binary outcomes.

    Thomson, Andrew; Hayes, Richard; Cousens, Simon

    2009-05-30

    Cluster randomized trials (CRTs) are increasingly used to evaluate the effectiveness of health-care interventions. A key feature of CRTs is that the observations on individuals within clusters are correlated as a result of between-cluster variability. Sample size formulae exist which account for such correlations, but they make different assumptions regarding the between-cluster variability in the intervention arm of a trial, resulting in different sample size estimates. We explore the relationship for binary outcome data between two common measures of between-cluster variability: k, the coefficient of variation and rho, the intracluster correlation coefficient. We then assess how the assumptions of constant k or rho across treatment arms correspond to different assumptions about intervention effects. We assess implications for sample size estimation and present a simple solution to the problems outlined. PMID:19378266

  11. Applicability of condensation particle counters to measure atmospheric clusters

    M. Sipilä

    2008-03-01

    Full Text Available The ambient and laboratory molecular and ion clusters were investigated. Here we present data on the ambient concentrations of both charged and uncharged molecular clusters as well as the performance of a pulse height condensation particle counter (PH-CPC and an expansion condensation particle counter (E-CPC. The ambient molecular cluster concentrations were measured using both instruments, and they were deployed in conjunction with ion spectrometers and other aerosol instruments in Hyytiälä, Finland at the SMEAR II station during 1 March to 30 June 2007. The observed cluster concentrations varied and were from ca. 1000 to 100 000 cm−3. Both instruments showed similar concentrations. The average size of detected clusters was approximately 1.8 nm. As the atmospheric measurements at sub 2-nm particles and molecular clusters are a challenging task, and we were most likely unable to detect the smallest clusters, the reported concentrations are our best estimates for minimum cluster concentrations in boreal forest environment.

  12. Statistical measures and magic numbers in metal clusters

    In this work, a shell model for metal clusters up to 220 valence electrons is used to obtain the fractional occupation probabilities of the electronic orbitals. Then, the calculation of a statistical measure of complexity and the Fisher-Shannon information is carried out. An increase of both magnitudes with the number of valence electrons is observed. The shell structure is reflected by the behavior of the statistical complexity. The magic numbers are indicated by the Fisher-Shannon information. So, as in the case of atomic nuclei, the study of statistical indicators also unveil the existence of magic numbers in metal clusters. - Highlights: → This work quantifies information-theoretic indicators in metal clusters. → Statistical complexity and the Fisher-Shannon information are calculated. → The magic numbers of metal clusters are revealed by the measurements. → These statistical measures are useful as descriptors for quantum systems.

  13. Statistical measures and magic numbers in metal clusters

    Sanudo, Jaime, E-mail: jsr@unex.e [Departamento de Fisica, Facultad de Ciencias, Universidad de Extremadura, E-06071 Badajoz (Spain); BIFI, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Lopez-Ruiz, Ricardo, E-mail: rilopez@unizar.e [DIIS and BIFI, Facultad de Ciencias, Universidad de Zaragoza, E-50009 Zaragoza (Spain)

    2011-04-11

    In this work, a shell model for metal clusters up to 220 valence electrons is used to obtain the fractional occupation probabilities of the electronic orbitals. Then, the calculation of a statistical measure of complexity and the Fisher-Shannon information is carried out. An increase of both magnitudes with the number of valence electrons is observed. The shell structure is reflected by the behavior of the statistical complexity. The magic numbers are indicated by the Fisher-Shannon information. So, as in the case of atomic nuclei, the study of statistical indicators also unveil the existence of magic numbers in metal clusters. - Highlights: This work quantifies information-theoretic indicators in metal clusters. Statistical complexity and the Fisher-Shannon information are calculated. The magic numbers of metal clusters are revealed by the measurements. These statistical measures are useful as descriptors for quantum systems.

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

    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...

  15. Galaxy cluster scaling relations measured with APEX-SZ

    Bender, A. N.; Kennedy, J.; 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.

    2016-08-01

    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 Mgas, temperature TX, and YX = MgasTX) that relate to total cluster mass. We measure power-law scaling relations, including an intrinsic scatter, between the SZE and X-ray observables for three subsamples within the set of 42 clusters that have uniform X-ray analysis in the literature. We observe that differences between these X-ray analyses introduce significant variance into the measured scaling relations, particularly affecting the normalization. For all three subsamples, we find results consistent with a self-similar model of cluster evolution dominated by gravitational effects. Comparing to predictions from numerical simulations, these scaling relations prefer models that include cooling and feedback in the ICM. Lastly, we measure an intrinsic scatter of ˜28 per cent in the Y - YX scaling relation for all three subsamples.

  16. Theoretical prediction of the fundamental properties for the ternary Li2PtH6 and Na2PtH6

    Li2PtH6 and Na2PtH6 are good candidate for hydrogen storage. The structural, elastic, electronic and optical properties of Li2PtH6 and Na2PtH6 compounds have been investigated using pseudo-potential plane–wave method based on the density functional theory. Computed lattice constant and H atom positional parameter at equilibrium agree well with the available experimental data. A quadratic pressure dependence of the elastic stiffness is found. A set of isotropic elastic parameters and related properties, namely bulk and shear moduli, Young's modulus, Poisson's ratio, average sound velocity and Debye temperature are numerically estimated in the framework of the Voigt–Reuss–Hill approximation for Li2PtH6 and Na2PtH6 polycrystalline aggregate. The analyses of the band structure indicates that Li2PtH6 and Na2PtH6 are indirect gap semiconductors. The static dielectric constant and static refractive index are inversely proportional to the fundamental gap. Highlights: ► We predict elastic moduli, energy gaps and optical parameters. ► Electron effective mass is anisotropic. ► Li2PtH6 and Na2PtH6 are indirect gap semiconductors. ► The contribution to the optical spectra from main transitions are predicted.

  17. Measuring the Mass-to-Light Ratio of Cluster Galaxies

    Natarajan, P.

    1996-12-01

    There is ample evidence from lensing for the clumping of dark matter on different scales within clusters, although the spatial extent of dark halos of cluster galaxies are yet to be constrained. The issue is of crucial importance as it addresses the key question of whether the mass to light ratio of galaxies is a function of the environment, and if it is indeed significantly different in the high density regions like cluster cores as opposed to the field. Weak shear maps of the outer regions of clusters have been successfully used to map the distribution of mass at large radii. However the typical smoothing lengths generally employed preclude the systematic study of the effects of galactic-scale substructure on the measured weak lensing signal. We present two new methods to study the effect of bright cluster galaxies on the cluster weak shear field - aperture averaging of the local shear and a maximum likelihood method to obtain limits on parameters that characterize galaxy halos. The composite lensing effect of a cluster is modeled by the superposition of mass clumps with different scales: a large-scale clump to describe the cluster and smaller scale ones for individual cluster galaxies. Working in the local frame of each perturber, the shear induced by the larger scale component can be efficiently subtracted, yielding the averaged shear field induced by the smaller-scale mass component. Cluster galaxy halos are modeled using simple scaling relations and the background high redshift population is modeled in consonance with observations from redshift surveys and lensing constraints. We demonstrate using simulations that these observed local weak-shear effects on galaxy scales within the cluster can be used to statistically constrain reliably the mean M/L of cluster members, and fiducial parameters like the halo size, velocity dispersion and hence mass of cluster galaxies. The results of the members, and fiducial parameters like the halo size and the velocity

  18. Measuring cluster masses with CMB lensing: a statistical approach

    Melin, Jean-Baptiste

    2014-01-01

    We present a method for measuring the masses of galaxy clusters using the imprint of their gravitational lensing signal on the cosmic microwave background (CMB) temperature anisotropies. The method first reconstructs the projected gravitational potential with a quadratic estimator and then applies a matched filter to extract cluster mass. The approach is well-suited for statistical analyses that bin clusters according to other mass proxies. We find that current experiments, such as Planck, the South Pole Telescope and the Atacama Cosmology Telescope, can practically implement such a statistical methodology, and that future experiments will reach sensitivities sufficient for individual measurements of massive systems. As illustration, we use simulations of Planck observations to demonstrate that it is possible to constrain the mass scale of a set of 62 massive clusters with prior information from X-ray observations, similar to the published Planck ESZ-XMM sample. We examine the effect of the thermal (tSZ) and ...

  19. Hydrometeor classification from polarimetric radar measurements: a clustering approach

    Grazioli, Jacopo; Tuia, Devis; Berne, Alexis

    2015-01-01

    A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number of hydrometeor classes (nopt) that can be reliably identified from a large set of polarimetric data is determined. This is done by means of an unsupervised clustering technique guided by criteria related both to data similarity and to spatial smoothness of the classified images. In a second step, the nopt clusters are assign...

  20. Gaussian covariance matrices for anisotropic galaxy clustering measurements

    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.

  1. Measuring Consistent Masses for 25 Milky Way Globular Clusters

    Kimmig, Brian; Ivans, Inese I; Strader, Jay; Caldwell, Nelson; Anderton, Tim; Gregersen, Dylan

    2014-01-01

    We present central velocity dispersions, masses, mass to light ratios ($M/L$s), and rotation strengths for 25 Galactic globular clusters. We derive radial velocities of 1951 stars in 12 globular clusters 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 $M/L$s for the metal-rich clusters. We find no clear trend of increasing rotation with increasi...

  2. Sensitivity evaluation of dynamic speckle activity measurements using clustering methods

    We evaluate and compare the use of competitive neural networks, self-organizing maps, the expectation-maximization algorithm, K-means, and fuzzy C-means techniques as partitional clustering methods, when the sensitivity of the activity measurement of dynamic speckle images needs to be improved. The temporal history of the acquired intensity generated by each pixel is analyzed in a wavelet decomposition framework, and it is shown that the mean energy of its corresponding wavelet coefficients provides a suited feature space for clustering purposes. The sensitivity obtained by using the evaluated clustering techniques is also compared with the well-known methods of Konishi-Fujii, weighted generalized differences, and wavelet entropy. The performance of the partitional clustering approach is evaluated using simulated dynamic speckle patterns and also experimental data.

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

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

    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.

  5. Measuring \\Omega_0 from the Entropy Evolution of Clusters

    Kay, Scott T.; Bower, Richard G.

    1998-01-01

    In this paper, we have extended the entropy-driven model of cluster evolution developed by Bower (1997) in order to be able to predict the evolution of galaxy clusters for a range of cosmological scenarios. We have applied this model to recent measurements of the evolution of the L_x-T normalisation and X-ray luminosity function in order to place constraints on cosmological parameters. We find that these measurements alone do not select a particular cosmological frame-work. An additional cons...

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

    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.

  7. Magnetic and transport properties of Pr2Pt3Si5

    Anand, V.K.; Anupam; Hossain, Z.; Ramakrishnan, S.; Thamizhavel, A.; Adroja, D.T.

    2012-03-31

    We have investigated the magnetic and transport properties of a polycrystalline Pr2Pt3Si5 sample through the dc and ac magnetic susceptibilities, electrical resistivity, and specific heat measurements. The Rietveld refinement of the powder X-ray diffraction data reveals that Pr2Pt3Si5 crystallizes in the U2Co3Si5-type orthorhombic structure (space group Ibam). Both the dc and ac magnetic susceptibility data measured at low fields exhibit sharp anomaly near 15 K. In contrast, the specific heat data exhibit only a broad anomaly implying no long range magnetic order down to 2 K. The broad Schottky-type anomaly in low temperature specific heat data is interpreted in terms of crystal electric field (CEF) effect, and a CEF-split singlet ground state is inferred. The absence of the long range order is attributed to the presence of nonmagnetic singlet ground state of the Pr3+ ion. The electrical resistivity data exhibit metallic behavior and are well described by the Bloch-Grüniesen-Mott relation.

  8. Unbiased methods for removing systematics from galaxy clustering measurements

    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...

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

    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.

  10. Text Clustering Using a Suffix Tree Similarity Measure

    Huang, Chenghui; Yin, Jian; Fang HOU

    2011-01-01

    In text mining area, popular methods use the bag-of-words models, which represent a document as a vector. These methods ignored the word sequence information, and the good clustering result limited to some special domains. This paper proposes a new similarity measure based on suffix tree model of text documents. It analyzes the word sequence information, and then computes the similarity between the text documents of corpus by applying a suffix tree similarity that combines with TF-IDF weighti...

  11. Statistical measures applied to metal clusters: evidence of magic numbers

    Sanudo, Jaime; Lopez-Ruiz, Ricardo

    2010-01-01

    In this work, a shell model for metal clusters up to 220 valence electrons is used to obtain the fractional occupation probabilities of the electronic orbitals. Then, the calculation of a statistical measure of complexity and the Fisher-Shannon information is carried out. An increase of both magnitudes with the number of valence electrons is observed. The shell structure is reflected by the behavior of the statistical complexity. The magic numbers are indicated by the Fisher-Shannon informati...

  12. Hydrometeor classification from polarimetric radar measurements: a clustering approach

    Grazioli, J.; D. Tuia; Berne, A.

    2014-01-01

    A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number nopt of hydrometeor classes that can be reliably identified from a large set of polarimetric data is determined. This is done by means of an unsupervised clustering technique guided by criteria related both to data similarity and to spatial smoothness of the classified images. In a second s...

  13. Hydrometeor classification from polarimetric radar measurements: a clustering approach

    Grazioli, J.; D. Tuia; Berne, A.

    2015-01-01

    A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number of hydrometeor classes (nopt) that can be reliably identified from a large set of polarimetric data is determined. This is done by means of an unsupervised clustering technique guided by criteria related both to data similarity and to spatial smoothness of the classified images. In a s...

  14. Unbiased methods for removing systematics from galaxy clustering measurements

    Elsner, Franz; Leistedt, Boris; Peiris, Hiranya V.

    2016-02-01

    Measuring the angular clustering of galaxies as a function of redshift is a powerful method for extracting 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 characterize 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 the basic mode projection algorithm, we prove it to be free of any bias, whereas we conclude that results computed with extended mode projection are biased. Within a simplified setup, we derive analytical expressions for the bias and discuss the options for correcting it in more realistic configurations. Common to all three methods is an increased estimator variance induced by the cleaning process, albeit at different levels. These results enable unbiased high-precision clustering measurements in the presence of spatially varying systematics, an essential step towards realizing the full potential of current and planned galaxy surveys.

  15. A Hybrid Distance Measure for Clustering Expressed Sequence Tags Originating from the Same Gene Family

    Ng, Keng-Hoong; Ho, Chin-Kuan; Phon-Amnuaisuk, Somnuk

    2012-01-01

    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 commo...

  16. Measuring the neutrino mass from future wide galaxy cluster catalogues

    We present forecast errors on a wide range of cosmological parameters obtained from a photometric cluster catalogue of a future wide-field Euclid-like survey. We focus in particular on the total neutrino mass as constrained by a combination of the galaxy cluster number counts and correlation function. For the latter we consider only the shape information and the Baryon Acoustic Oscillations (BAO), while marginalising over the spectral amplitude and the redshift space distortions. In addition to the cosmological parameters of the standard ΛCDM+ν model we also consider a non-vanishing curvature, and two parameters describing a redshift evolution for the dark energy equation of state. For completeness, we also marginalise over a set of ''nuisance'' parameters, representing the uncertainties on the cluster mass determination. We find that combining cluster counts with power spectrum information greatly improves the constraining power of each probe taken individually, with errors on cosmological parameters being reduced by up to an order of magnitude. In particular, the best improvements are for the parameters defining the dynamical evolution of dark energy, where cluster counts break degeneracies. Moreover, the resulting error on neutrino mass is at the level of σ(Mν) ∼ 0.9 eV, comparable with that derived from present Lyα forest measurements and Cosmic Microwave background (CMB) data in the framework of a non-flat Universe. Further adopting Planck priors and reducing the number of free parameters to a ΛCDM+ν cosmology allows to place constraints on the total neutrino mass of σ(Mν) ∼ 0.08 eV, close to the lower bound enforced by neutrino oscillation experiments. Finally, in the optimistic case where uncertainties in the calibration of the mass-observable relation were so small to be neglected, the combination of Planck priors with cluster counts and power spectrum would constrain the total neutrino mass down to σ(Mν) ∼ 0.034 eV, i.e. the minimum

  17. Optimizing an Organized Modularity Measure for Topographic Graph Clustering: a Deterministic Annealing Approach

    Rossi, Fabrice; Villa-Vialaneix, Nathalie

    2010-01-01

    This paper proposes an organized generalization of Newman and Girvan's modularity measure for graph clustering. Optimized via a deterministic annealing scheme, this measure produces topologically ordered graph clusterings that lead to faithful and readable graph representations based on clustering induced graphs. Topographic graph clustering provides an alternative to more classical solutions in which a standard graph clustering method is applied to build a simpler graph that is then represen...

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

    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. Text Clustering Using a Suffix Tree Similarity Measure

    Chenghui HUANG

    2011-10-01

    Full Text Available In text mining area, popular methods use the bag-of-words models, which represent a document as a vector. These methods ignored the word sequence information, and the good clustering result limited to some special domains. This paper proposes a new similarity measure based on suffix tree model of text documents. It analyzes the word sequence information, and then computes the similarity between the text documents of corpus by applying a suffix tree similarity that combines with TF-IDF weighting method. Experimental results on standard document benchmark corpus RUTERS and BBC indicate that the new text similarity measure is effective. Comparing with the results of the other two frequent word sequence based methods, our proposed method achieves an improvement of about 15% on the average of F-Measure score.

  20. Pivotal, cluster and interface measures for critical planar percolation

    Garban, Christophe; Schramm, Oded

    2010-01-01

    This work is the first in a series of papers devoted to the construction and study of scaling limits of dynamical and near-critical planar percolation and related objects like invasion percolation and the Minimal Spanning Tree. We show here that the counting measure on the set of pivotal points of critical site percolation on the triangular grid, normalized appropriately, has a scaling limit, which is a function of the scaling limit of the percolation configuration. We also show that this limit measure is conformally covariant, with exponent 3/4. Similar results hold for the counting measure on macroscopic open clusters (the area measure), and for the counting measure on interfaces (length measure). Since the aforementioned processes are very much governed by pivotal sites, the construction and properties of the "local time"-like pivotal measure are key results in this project. Another application is that the existence of the limit length measure on the interface is a key step towards constructing the so-call...

  1. Assessment for the role of rare earth oxide in the R2O3 - RuO2 - Pt composite electrode

    Our work has showed several results related to assessment for the role of rare earth oxide in the R2O3 - RuO2 - Pt composite electrode. The precursor method was used for preparing composite electrode in the following forms: a- RuO2 - Pt electrode b- La2O3 (55%) - RuO2 (45%) - Pt electrode c- CeO2 (60%) - RuO2 (40%) - Pt electrode By measurements of anodic polarization and cyclic potential for the types of a, b, c electrodes we can see that the La2O3 (55%) - 45% RuO2 - Pt electrode will be the best anodic electrode. It means that the partial replacement of ruthenium oxide by lanthanum oxide in composite oxide electrode will be an effective one. (author)

  2. Comparison of Electrodes for High-Performance Electrochemical Capacitors: Multi-Layer MnO2/Pt and Composite MnO2/Pt on Carbon Nanofibres.

    Lee, Yu-Jin; An, Geon-Hyoung; Ahn, Hyo-Jin

    2015-11-01

    Four different types of electrodes for high-performance electrochemical capacitors were prepared using electrospinning method and/or impregnation methods: (1) conventional carbon nanofibres (CNF) supports, and CNFs decorated with (2) MnO2 nanophases, (3) multi-layer MnO2/Pt nanophases, and (4) composite MnO2 and Pt nanophases. Their morphological, structural, chemical, and electrochemical properties were characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and galvanostatic charge/discharge measurements. Composite MnO2 and Pt nanophases decorated on the CNFs exhibited superior capacitance (-252.3 F/g at 10 mV/s), excellent capacitance retention (-93.5% after 300 cycles), and high energy densities (13.53-18.06 Wh/kg). The enhanced electrochemical performances can be explained by the composite structure, presenting well-dispersed MnO2 nanophases leading to high capacitance, and well-dispersed Pt nanophases leading to improved electrical conductivity. PMID:26726621

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

    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...

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

    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...

  5. A new approach to quantum measurement problem: cluster separability

    HajIcek, Petr, E-mail: hajicek@itp.unibe.ch [Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland)

    2011-07-08

    The paper describes a solution to the problem of quantum measurement that has been proposed recently. The literal understanding of the basic rule of quantum mechanics on identical particles violates the cluster separation principle and so leads to difficulties. A proposal due to Peres of how such difficulties could be removed is reformulated and extended. Cluster separability leads to a locality requirement on observables and to the key notion of separation status. Separation status of a microsystem is shown to change in preparation and registration processes. The indispensability of detectors plays an important role. Changes of separation status are alterations of kinematic description rather than some parts of dynamical trajectories and so more radical than 'collapse of the wave function'. Textbook quantum mechanics does not provide any information of how separation status changes run, hence new rules must be formulated. This enables to satisfy the objectification requirement for registrations. To show how the ideas work, a simplified model of registration apparatus is constructed.

  6. Gas bulk motion in the Perseus cluster measured with SUZAKU

    Tamura, Takayuki; Iizuka, R; Fukazawa, Y; Hayashida, K; Ueda, S; Matsushita, K; Sato, K; Nakazawa, K; Ota, N; Takizawa, M

    2013-01-01

    We present the results from Suzaku observations of the Perseus galaxy cluster, which is relatively close, the brightest in the X-ray sky and a relaxed object with a cool core. A number of exposures of central regions and offset pointing with the X-ray Imaging Spectrometer cover a region within radii of 20'-30'. The central data are used to evaluate the instrumental energy-scale calibration with accuracy confirmed to within around 300 km/s, by the spatial and temporal variation of the instruments. These deep and well-calibrated data are used to measure X-ray redshifts of the intracluster medium. A hint of gas bulk motion, with radial velocity of about -(150-300) km/s, relative to the main system was found at 2-4 arcmin (45-90kpc) west of the cluster center, where an X-ray excess and a cold front were found previously. No other velocity structure was discovered. Over spatial scales of 50-100kpc and within 200kpc radii of the center, the gas-radial-velocity variation is below 300 km/s, while over scales of 400 k...

  7. Hydrometeor classification from polarimetric radar measurements: a clustering approach

    Grazioli, J.; Tuia, D.; Berne, A.

    2015-01-01

    A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number of hydrometeor classes (nopt) that can be reliably identified from a large set of polarimetric data is determined. This is done by means of an unsupervised clustering technique guided by criteria related both to data similarity and to spatial smoothness of the classified images. In a second step, the nopt clusters are assigned to the appropriate hydrometeor class by means of human interpretation and comparisons with the output of other classification techniques. The main innovation in the proposed method is the unsupervised part: the hydrometeor classes are not defined a priori, but they are learned from data. The approach is applied to data collected by an X-band polarimetric weather radar during two field campaigns (from which about 50 precipitation events are used in the present study). Seven hydrometeor classes (nopt = 7) have been found in the data set, and they have been identified as light rain (LR), rain (RN), heavy rain (HR), melting snow (MS), ice crystals/small aggregates (CR), aggregates (AG), and rimed-ice particles (RI).

  8. Hydrometeor classification from polarimetric radar measurements: a clustering approach

    J. Grazioli

    2014-08-01

    Full Text Available A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number nopt of hydrometeor classes that can be reliably identified from a large set of polarimetric data is determined. This is done by means of an unsupervised clustering technique guided by criteria related both to data similarity and to spatial smoothness of the classified images. In a second step, the nopt clusters are assigned to the appropriate hydrometeor class by means of human interpretation and comparisons with the output of other classification techniques. The main innovation in the proposed method is the unsupervised part: the hydrometeor classes are not defined a-priori, but they are learned from data. The proposed approach is applied to data collected by an X-band polarimetric weather radar during two field campaigns (totalling about 3000 h of precipitation. Seven hydrometeor classes have been found in the data set and they have been associated to drizzle (DZ, light rain (LR, heavy rain (HR, melting snow (MS, ice crystals/small aggregates (CR, aggregates (AG, rimed particles (RI.

  9. Hydrometeor classification from polarimetric radar measurements: a clustering approach

    J. Grazioli

    2015-01-01

    Full Text Available A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number of hydrometeor classes (nopt that can be reliably identified from a large set of polarimetric data is determined. This is done by means of an unsupervised clustering technique guided by criteria related both to data similarity and to spatial smoothness of the classified images. In a second step, the nopt clusters are assigned to the appropriate hydrometeor class by means of human interpretation and comparisons with the output of other classification techniques. The main innovation in the proposed method is the unsupervised part: the hydrometeor classes are not defined a priori, but they are learned from data. The approach is applied to data collected by an X-band polarimetric weather radar during two field campaigns (from which about 50 precipitation events are used in the present study. Seven hydrometeor classes (nopt = 7 have been found in the data set, and they have been identified as light rain (LR, rain (RN, heavy rain (HR, melting snow (MS, ice crystals/small aggregates (CR, aggregates (AG, and rimed-ice particles (RI.

  10. Resistive switching characteristics of Ni/HfO2/Pt ReRAM

    Zhang Xiao

    2012-01-01

    This study investigated the resistive switching characteristics of the Ni/HfO2/Pt structure for nonvolatile memory application.The Ni/HfO2/Pt device showed bipolar resistive switching (RS) without a forming process,and the formation and rupture of conducting filaments are responsible for the resistive switching phenomenon,In addition,the device showed some excellent memory performances,including a large on/offratio (> 3 × 105),very good data retention (> 103 s @ 200 ℃) and uniformity of switching parameters.Considering these results,the Ni/HfO2/Pt device has the potential for nonvolatile memory applications.

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

    Carneiro, Kim; Petersen, A. S.; Underhill, A. E.; Wood, D. J.; Watkins, D. M.; Mackenzie, Gordon A.

    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...

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

    Salazar-Albornoz, Salvador; Sánchez, Ariel G.; Padilla, Nelson D.; Baugh, Carlton M.

    2014-10-01

    We test the cosmological implications of studying galaxy clustering using a tomographic approach, by computing the galaxy two-point angular correlation function ω(θ) 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 DA(z) instead of only one (more precise) measurement of the effective average distance DV(z), which results in better constraints on the expansion history of the Universe. We test our model for ω(θ) 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-fitting Λ cold dark matter (ΛCDM) cosmology from the cosmic microwave background measurements from the Planck satellite, we forecast the result of applying this tomographic approach to the final Baryon Oscillation Spectroscopic Survey catalogue in combination with Planck for three flat cosmological models, and compare them with the expected results of the isotropic baryon acoustic oscillation (BAO) measurements post-reconstruction on the same galaxy catalogue combined with Planck. While BAOs are more accurate for constraining cosmological parameters for the standard ΛCDM model, the tomographic technique gives better results when we allow the dark energy equation of state wDE to deviate from -1, resulting in a performance similar to BAOs in the case of a constant value of wDE, and a moderate improvement in the case of a time-dependent value of wDE, increasing the value of the figure of merit in the w0-wa plane up to 15 per cent.

  13. Clustering

    Jinfei Liu

    2013-04-01

    Full Text Available DBSCAN is a well-known density-based clustering algorithm which offers advantages for finding clusters of arbitrary shapes compared to partitioning and hierarchical clustering methods. However, there are few papers studying the DBSCAN algorithm under the privacy preserving distributed data mining model, in which the data is distributed between two or more parties, and the parties cooperate to obtain the clustering results without revealing the data at the individual parties. In this paper, we address the problem of two-party privacy preserving DBSCAN clustering. We first propose two protocols for privacy preserving DBSCAN clustering over horizontally and vertically partitioned data respectively and then extend them to arbitrarily partitioned data. We also provide performance analysis and privacy proof of our solution..

  14. Resistance-switching mechanism of SiO2:Pt-based Mott memory

    Zhang, Keke; Lu, Nianduan; Li, Ling; Liu, Qi; Liu, Ming

    2015-12-01

    We proposed a basic resistance-switching mechanism for Mott memory based on the SiO2:Pt system to explain why device performance depends on the electrode. The competition between collection current and drift current in SiO2:Pt system was attributed to the polarity of the set voltage depending on the work function of the electrode. The proposed theory, based on the energy band of SiO2:Pt calculated using first-principles calculations, explains the perplexing phenomenon wherein a SiO2:Pt device cannot show reproducible resistance-switching behavior with a symmetric electrode. The theoretical set voltage agrees with prior experimental results, which verifies our theory.

  15. A highly efficient measure of mass segregation in star clusters

    Olczak, C; Henning, Th

    2011-01-01

    Investigations of mass segregation are of vital interest for the understanding of the formation and dynamical evolution of stellar systems on a wide range of spatial scales. Our method is based on the minimum spanning tree (MST) that serves as a geometry-independent measure of concentration. Compared to previous such approaches we obtain a significant refinement by using the geometrical mean as an intermediate-pass. It allows the detection of mass segregation with much higher confidence and for much lower degrees of mass segregation than other approaches. The method shows in particular very clear signatures even when applied to small subsets of the entire population. We confirm with high significance strong mass segregation of the five most massive stars in the Orion Nebula Cluster (ONC). Our method is the most sensitive general measure of mass segregation so far and provides robust results for both data from simulations and observations. As such it is ideally suited for tracking mass segregation in young sta...

  16. Comparison of chemical clustering methods using graph- and fingerprint-based similarity measures

    Raymond, J.W.; Blankley, C.J.; Willett, P.

    2003-01-01

    This paper compares several published methods for clustering chemical structures, using both graph- and fingerprint-based similarity measures. The clusterings from each method were compared to determine the degree of cluster overlap. Each method was also evaluated on how well it grouped structures into clusters possessing a non-trivial substructural commonality. The methods which employ adjustable parameters were tested to determine the stability of each parameter for datasets of varying size...

  17. Magnetic and transport properties of Pr{sub 2}Pt{sub 3}Si{sub 5}

    Anand, V.K., E-mail: vivekkranand@gmail.com [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005 (India); ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot Oxon, OX11 0QX (United Kingdom); Anupam; Hossain, Z. [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Ramakrishnan, S.; Thamizhavel, A. [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005 (India); Adroja, D.T. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot Oxon, OX11 0QX (United Kingdom)

    2012-08-15

    We have investigated the magnetic and transport properties of a polycrystalline Pr{sub 2}Pt{sub 3}Si{sub 5} sample through the dc and ac magnetic susceptibilities, electrical resistivity, and specific heat measurements. The Rietveld refinement of the powder X-ray diffraction data reveals that Pr{sub 2}Pt{sub 3}Si{sub 5} crystallizes in the U{sub 2}Co{sub 3}Si{sub 5}-type orthorhombic structure (space group Ibam). Both the dc and ac magnetic susceptibility data measured at low fields exhibit sharp anomaly near 15 K. In contrast, the specific heat data exhibit only a broad anomaly implying no long range magnetic order down to 2 K. The broad Schottky-type anomaly in low temperature specific heat data is interpreted in terms of crystal electric field (CEF) effect, and a CEF-split singlet ground state is inferred. The absence of the long range order is attributed to the presence of nonmagnetic singlet ground state of the Pr{sup 3+} ion. The electrical resistivity data exhibit metallic behavior and are well described by the Bloch-Grueniesen-Mott relation. - Highlights: Black-Right-Pointing-Pointer We report synthesis, structural, magnetic and transport properties of a new compound Pr{sub 2}Pt{sub 3}Si{sub 5}. Black-Right-Pointing-Pointer No long range magnetic order is observed down to 2 K. Black-Right-Pointing-Pointer A broad Schottky-type anomaly is observed in low-T specific heat due to crystal field effect. Black-Right-Pointing-Pointer A singlet ground state in this compound is held responsible for the absence of long range order. Black-Right-Pointing-Pointer The electrical resistivity is well described by the metallic Bloch-Grueniesen-Mott relation.

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

    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. PMID:26731341

  19. Mammographic calcification cluster detection and threshold gold thickness measurements

    Warren, L. M.; Mackenzie, A.; Cooke, J.; Given-Wilson, R.; Wallis, M. G.; Chakraborty, D. P.; Dance, D. R.; Young, K. C.

    2012-03-01

    European Guidelines for quality control in digital mammography specify acceptable and achievable standards of image quality (IQ) in terms of threshold gold thickness using the CDMAM test object. However, there is little evidence relating such measurements to cancer detection. This work investigated the relationship between calcification detection and threshold gold thickness. An observer study was performed using a set of 162 amorphous selenium direct digital (DR) detector images (81 no cancer and 81 with 1-3 inserted calcification clusters). From these images four additional IQs were simulated: different digital detectors (computed radiography (CR) and DR) and dose levels. Seven observers marked and rated the locations of suspicious regions. DBM analysis of variances was performed on the JAFROC figure of merit (FoM) yielding 95% confidence intervals for IQ pairs. Automated threshold gold thickness (Tg) analysis was performed for the 0.25mm gold disc diameter on CDMAM images at the same IQs (16 images per IQ). Tg was plotted against FoM and a power law fitted to the data. There was a significant reduction in FoM for calcification detection for CR images compared with DR; FoM decreased from 0.83 to 0.63 (pIQ. Since the majority of threshold gold thicknesses for the various IQs were above the acceptable standard despite large variations in calcification detection by radiologists, current EU guidelines may need revising.

  20. Measurement of initial clustering on the radon decay product 218Po

    The formation of water clusters on 218Po ions is studied. The formation of the water clusters is discussed in the light of the classical theory of clustering, the clustering theory of Hawrynski and a kinetic model of clustering. The design of a specialized electric mobility spectrometer to measure the electric mobilities of the water clusters at various humidity levels is discussed. From the mobilities the radii of, and a number of water molecules in, the clusters are calculated using kinetic gas theory. The determinations were done for humidity levels between 0,16 and 96% relative humidity, and the results compared with the theoretical predictions. It was found that the classical theory underestimates the sizes of the clusters and the theory of Hawrynski overestimates the cluster sizes. It is concluded that the spectrometer is capable of high resolution measurement of the electric mobility of the small clusters. The underlying result of the clustering theories is that stable clusters with particular radii are formed at each humidity level. 91 refs., 70 figs., 11 tabs

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

    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.

  2. Clusters as benchmarks for measuring fundamental stellar parameters

    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.

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

    Biggerstaff, Devon N.; Rudolph, Terry; Kaltenbaek, Rainer; Hamel, Deny; Weihs, Gregor; Resch, Kevin J.

    2009-01-01

    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 diferent computations, the average output fidelity is 0.9832 +/- 0.0002; furthermor...

  4. Measuring the neutrino mass from future wide galaxy cluster catalogues

    Carbone, Carmelita; Moscardini, Lauro; Cimatti, Andrea

    2011-01-01

    [abridged]We present forecast errors on a wide range of cosmological parameters obtained from a photometric cluster catalogue of a future wide-field Euclid-like survey. We focus in particular on the total neutrino mass as constrained by a combination of the galaxy cluster number counts and correlation function. For the latter we consider only the shape information and the Baryon Acoustic Oscillations (BAO), while marginalising over the spectral amplitude and the redshift space distortions. In addition to the cosmological parameters of the standard LCDM+nu model we also consider a non-vanishing curvature, and two parameters describing a redshift evolution for the dark energy equation of state. For completeness, we also marginalise over a set of "nuisance" parameters, representing the uncertainties on the cluster mass determination. We find that combining cluster counts with power spectrum information greatly improves the constraining power of each probe taken individually, with errors on cosmological parameter...

  5. Structural, magnetic and transport properties of single-crystalline U2Pt2In

    Single crystals of the heavy-electron compound U2Pt2In have been grown by a modified mineralization technique. The x-ray structure refinement shows that U2Pt2In single crystals form in the Zr3Al2 structure, instead of the U3Si2 structure reported for polycrystalline material. The polymorphism of U2Pt2In is attributed to the experimental parameters, such as pressure and temperature, during the sample preparation process. The single-crystal susceptibility data reveal a weak maximum for Xc at Tmax=7.9 K, indicating the presence of short-range antiferromagnetic correlations, while Xa has the tendency to diverge at low T (T>2 K). The electrical resistivity of the single crystals (T>0.3 K) is best described by ρ∼Tα with α∼1.1(1) for I parallel to a and α∼0.3(2) for I parallel to c. The magnetic and transport data show pronounced deviations from the standard Fermi-liquid picture, and lead to a classification of U2Pt2In as a non-Fermi-liquid compound. As the origin of NFL behaviour in U2Pt2In we propose the proximity to a quantum critical point or Kondo disorder. (author)

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

    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.

  7. 18 GHz SZ Measurements of the Bullet Cluster

    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.

  8. On the NP-Completeness of Some Graph Cluster Measures

    Šíma, Jiří; Schaeffer, S.E.

    Berlin : Springer, 2006 - (Wiedermann, J.; Tel, G.; Pokorný, J.; Bieliková, M.; Štuller, J.), s. 530-537 ISBN 3-540-31198-X. - (Lecture Notes in Computer Science. 3831). [SOFSEM 2006. Conference on Current Trends in Theory and Practice of Computer Science /32./. Měřín (CZ), 21.01.2006-27.01.2006] R&D Projects: GA MŠk(CZ) 1M0545 Grant ostatní: Academy of Finland(FI) 126235 Institutional research plan: CEZ:AV0Z10300504 Keywords : graph clustering * conductance * density * cluster editing * NP-completeness Subject RIV: BA - General Mathematics

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

    Baglio, V.; C. D'Urso; Di Blasi, A.; Ornelas, R; Arriaga, L.G.; Antonucci, V.; Aricò, A.S.

    2011-01-01

    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 where...

  10. Weak hierarchies associated with similarity measures--an additive clustering technique.

    Bandelt, H J; Dress, A W

    1989-01-01

    A new and apparently rather useful and natural concept in cluster analysis is studied: given a similarity measure on a set of objects, a sub-set is regarded as a cluster if any two objects a, b inside this sub-set have greater similarity than any third object outside has to at least one of a, b. These clusters then form a closure system which can be described as a hypergraph without triangles. Conversely, given such a system, one may attach some weight to each cluster and then compose a similarity measure additively, by letting the similarity of a pair be the sum of weights of the clusters containing that particular pair. The original clusters can be reconstructed from the obtained similarity measure. This clustering model is thus located between the general additive clustering model of Shepard and Arabie (1979) and the standard hierarchical model. Potential applications include fitting dendrograms with few additional nonnested clusters and simultaneous representation of some families of multiple dendrograms (in particular, two-dendrogram solutions), as well as assisting the search for phylogenetic relationships by proposing a somewhat larger system of possibly relevant "family groups", from which an appropriate choice (based on additional insight or individual preferences) remains to be made. PMID:2706398

  11. Measurement of the halo bias from stacked shear profiles of galaxy clusters

    Covone, Giovanni; Kilbinger, Martin; Cardone, Vincenzo F

    2014-01-01

    We present the observational evidence of the 2-halo term in the stacked shear profile of a sample of about 1200 optically selected galaxy clusters based on imaging data and the public shear catalog from the CFHTLenS. We find that the halo bias, a measure of the correlated distribution of matter around galaxy clusters, has amplitude and correlation with galaxy cluster mass in very good agreement with the predictions based on the LCDM standard cosmological model. The mass-concentration relation is flat but higher than theoretical predictions. We also confirm the close scaling relation between the optical richness of galaxy clusters and their mass.

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

    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.

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

    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.

  14. MEASURING THE DARK FLOW WITH PUBLIC X-RAY CLUSTER DATA

    We present new results on the dark flowfrom a measurement of the dipole in the distribution of peculiar velocities of galaxy clusters, applying the methodology proposed and developed by us earlier. Our latest measurement is conducted using new, low-noise 7 yr WMAP data as well as an all-sky sample of X-ray-selected galaxy clusters compiled exclusively from published catalogs. Our analysis of the cosmic microwave background signature of the kinematic Sunyaev-Zel'dovich (SZ) effect finds a statistically significant dipole at the location of galaxy clusters. The residual dipole outside the cluster regions is small, rendering our overall measurement 3σ-4σ significant. The amplitude of the dipole correlates with cluster properties, being larger for the most X-ray luminous clusters, as required if the signal is produced by the SZ effect. Since it is measured at zero monopole, the dipole cannot be due to the thermal SZ effect. Our results are consistent with those obtained earlier by us from 5 yr WMAP data and using a proprietary cluster catalog. In addition, they are robust to quadrupole removal, demonstrating that quadrupole leakage contributes negligibly to the signal. The lower noise of the 7 yr WMAP also allows us, for the first time, to obtain tentative empirical confirmation of our earlier conjecture that the adopted filtering alters the sign of the kinematic SZ (KSZ) effect for realistic clusters and thus of the deduced direction of the flow. The latter is consistent with our earlier measurement in both the amplitude and direction. Assuming the filtering indeed alters the sign of the KSZ effect from the clusters, the direction agrees well also with the results of independent work using galaxies as tracers at lower distances. We make all maps and cluster templates derived by us from public data available to the scientific community to allow independent tests of our method and findings.

  15. WIYN OPEN CLUSTER STUDY. XXIV. STELLAR RADIAL-VELOCITY MEASUREMENTS IN NGC 6819

    We present the current results from our ongoing radial-velocity (RV) survey of the intermediate-age (2.4 Gyr) open cluster NGC 6819. Using both newly observed and other available photometry and astrometry, we define a primary target sample of 1454 stars that includes main-sequence, subgiant, giant, and blue straggler stars, spanning a magnitude range of 11 ≤V≤ 16.5 and an approximate mass range of 1.1-1.6 M sun. Our sample covers a 23 arcminute (13 pc) square field of view centered on the cluster. We have measured 6571 radial velocities for an unbiased sample of 1207 stars in the direction of the open cluster NGC 6819, with a single-measurement precision of 0.4 km s-1 for most narrow-lined stars. We use our RV data to calculate membership probabilities for stars with ≥3 measurements, providing the first comprehensive membership study of the cluster core that includes stars from the giant branch through the upper main sequence. We identify 480 cluster members. Additionally, we identify velocity-variable systems, all of which are likely hard binaries that dynamically power the cluster. Using our single cluster members, we find a cluster average RV of 2.34 ± 0.05 km s-1. We use our kinematic cluster members to construct a cleaned color-magnitude diagram from which we identify rich giant, subgiant, and blue straggler populations and a well defined red clump. The cluster displays a morphology near the cluster turnoff clearly indicative of core convective overshoot. Finally, we discuss a few stars of note, one of which is a short-period red-clump binary that we suggest may be the product of a dynamical encounter.

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

    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...

  17. Observation of neutral sulfuric acid-amine containing clusters in laboratory and ambient measurements

    J. Zhao

    2011-11-01

    Full Text Available Recent ab initio calculations showed that amines can enhance atmospheric sulfuric acid-water nucleation more effectively than ammonia, and this prediction has been substantiated in laboratory measurements. Laboratory studies have also shown that amines can effectively displace ammonia in several types of ammonium clusters. However, the roles of amines in cluster formation and growth at a microscopic molecular scale (from molecular sizes up to 2 nm have not yet been well understood. Processes that must be understood include the incorporation of amines into sulfuric acid clusters and the formation of organic salts in freshly nucleated particles, which contributes significantly to particle growth rates. We report the first laboratory and ambient measurements of neutral sulfuric acid-amine clusters using the Cluster CIMS, a recently-developed mass spectrometer designed for measuring neutral clusters formed in the atmosphere during nucleation. An experimental technique, which we refer to as Semi-Ambient Signal Amplification (SASA, was employed. Sulfuric acid was added to ambient air, and the concentrations and composition of clusters in this mixture were analyzed by the Cluster CIMS. This experimental approach led to significantly higher cluster concentrations than are normally found in ambient air, thereby increasing signal-to-noise levels and allowing us to study reactions between gas phase species in ambient air and sulfuric acid containing clusters. Mass peaks corresponding to clusters containing four H2SO4 molecules and one amine molecule were clearly observed, with the most abundant sulfuric acid-amine clusters being those containing a C2- or C4-amine (i.e. amines with masses of 45 and 73 amu. Evidence for C3- and C5-amines (i.e. amines with masses of 59 and 87 amu was also found, but their correlation with sulfuric acid tetramer was not as strong as was observed for the C2- and C4-amines. The formation mechanisms for

  18. Effect of Volatility Clustering on Indifference Pricing of Options by Convex Risk Measures

    Kumar, Rohini

    2015-01-01

    In this article, we look at the effect of volatility clustering on the risk indifference price of options described by Sircar and Sturm in their paper (Sircar, R., & Sturm, S. (2012). From smile asymptotics to market risk measures. Mathematical Finance. Advance online publication. doi:10.1111/mafi.12015). The indifference price in their article is obtained by using dynamic convex risk measures given by backward stochastic differential equations. Volatility clustering is modelled by a fast mea...

  19. A comparison of cluster and systematic sampling methods for measuring crude mortality.

    2006-01-01

    OBJECTIVE: To compare the results of two different survey sampling techniques (cluster and systematic) used to measure retrospective mortality on the same population at about the same time. METHODS: Immediately following a cluster survey to assess mortality retrospectively in a town in North Darfur, Sudan in 2005, we conducted a systematic survey on the same population and again measured mortality retrospectively. This was only possible because the geographical layout of the town, and the ava...

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

    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.

  1. Memristive tri-stable resistive switching at ruptured conducting filaments of a Pt/TiO2/Pt cell

    A tri-stable memristive switching was demonstrated on a Pt/TiO2/Pt device and its underlying mechanism was suggested through a series of electrical measurements. Tri-stable switching could be initiated from a device in unipolar reset status. The unipolar reset status was obtained by performing an electroforming step on a pristine cell which was then followed by unipolar reset switching. It was postulated that tri-stable switching occurred at the location where the conductive filament (initially formed by the electroforming step) was ruptured by a subsequent unipolar reset process. The mechanism of the tri-stable memristive switching presented in this article was attributed to the migration of oxygen ions through the ruptured filament region and the resulting modulation of the Schottky-like interfaces. The assertion was further supported by a comparison study performed on a Pt/TiO2/TiO2−x/Pt cell. (paper)

  2. APPLICATION OF ENHANCED CLUSTERING TECHNIQUE USING SIMILARITY MEASURE FOR MARKET SEGMENTATION

    M M Kodabagi

    2014-06-01

    Full Text Available Segmentation is one of the very important strategic tools used by the marketer. Segmentation strategy is based on the concept that no firm can satisfy all needs of one customer or one need of all the customers. The customers are too numerous and diverse in their buying requirements, hence the marketers or companies cannot cater to the requirements of all customers that too in a broad market such as two-wheelers. Cluster analysis is a class of techniques used to identify the group of customers with similar behaviors given a large database of customer data containing their properties and past buying records. Clustering is one of the unsupervised learning method in which a set of data points are separated into uniform groups. The k-means is one of the most widely used clustering techniques used for various applications. The main drawback of original k-means clustering algorithm is dead centers. Dead centers are centers that have no associated data points. The original k-means clustering algorithm with Euclidian distance treats all features equally and does not accurately reflect the similarity among data points. In this paper, an attempt has been made to apply enhanced clustering algorithm which uses similarity measure for clustering (segmentation of two-wheeler market data. The enhanced clustering algorithm works in two phases; Seed Point Selection and Clustering. The method adapts new strategy to cluster data points more efficiently and accurately, and also avoids dead centers. The enhanced clustering algorithm is found to be efficient in meaningf

  3. Rayleigh Scattering Density Measurements, Cluster Theory, and Nucleation Calculations at Mach 10

    Balla, R. Jeffrey; Everhart, Joel L.

    2012-01-01

    In an exploratory investigation, quantitative unclustered laser Rayleigh scattering measurements of density were performed in the air in the NASA Langley Research Center's 31 in. Mach 10 wind tunnel. A review of 20 previous years of data in supersonic and Mach 6 hypersonic flows is presented where clustered signals typically overwhelmed molecular signals. A review of nucleation theory and accompanying nucleation calculations are also provided to interpret the current observed lack of clustering. Data were acquired at a fixed stagnation temperature near 990Kat five stagnation pressures spanning 2.41 to 10.0 MPa (350 to 1454 psi) using a pulsed argon fluoride excimer laser and double-intensified charge-coupled device camera. Data averaged over 371 images and 210 pixels along a 36.7mmline measured freestream densities that agree with computed isentropic-expansion densities to less than 2% and less than 6% at the highest and lowest densities, respectively. Cluster-free Mach 10 results are compared with previous clustered Mach 6 and condensation-free Mach 14 results. Evidence is presented indicating vibrationally excited oxygen and nitrogen molecules are absorbed as the clusters form, release their excess energy, and inhibit or possibly reverse the clustering process. Implications for delaying clustering and condensation onset in hypersonic and hypervelocity facilities are discussed.

  4. Pivot and cluster strategy: a preventive measure against diagnostic errors

    Shimizu T

    2012-11-01

    Full Text Available Taro Shimizu,1 Yasuharu Tokuda21Rollins School of Public Health, Emory University, Atlanta, GA, USA; 2Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, JapanAbstract: Diagnostic errors constitute a substantial portion of preventable medical errors. The accumulation of evidence shows that most errors result from one or more cognitive biases and a variety of debiasing strategies have been introduced. In this article, we introduce a new diagnostic strategy, the pivot and cluster strategy (PCS, encompassing both of the two mental processes in making diagnosis referred to as the intuitive process (System 1 and analytical process (System 2 in one strategy. With PCS, physicians can recall a set of most likely differential diagnoses (System 2 of an initial diagnosis made by the physicians’ intuitive process (System 1, thereby enabling physicians to double check their diagnosis with two consecutive diagnostic processes. PCS is expected to reduce cognitive errors and enhance their diagnostic accuracy and validity, thereby realizing better patient outcomes and cost- and time-effective health care management.Keywords: diagnosis, diagnostic errors, debiasing

  5. Novel TiO2-Pt@SiO2 nanocomposites with high photocatalytic activity

    Wu, Hao-Shuai; Sun, Ling-Dong; Zhou, Huan-Ping; Yan, Chun-Huan

    2012-05-01

    This article reports a facile and controllable two-step method to construct TiO2-Pt@SiO2 nanocomposites. TiO2 nanoparticles (NPs), with small size and high surface energy, were synthesized by a solvothermal reaction process. The TiO2-Pt@SiO2 nanocomposites were fabricated by a reverse micro-emulsion method. SiO2 shell coated NPs were adopted for further photocatalytic reaction. Because of their small size and high surface energy, TiO2@SiO2 and TiO2-Pt@SiO2 nanocomposites show higher photocatalytic activity than commercial Degussa P25. Compared with TiO2@SiO2, TiO2-Pt@SiO2nanocomposites have improved photocatalytic activity due to the Pt induced spatial separation of electrons and holes. The silica shells not only maintain the structure of the nanocomposites but also prevent their aggregation during the photocatalytic reactions, which is highly important for the good durability of the photocatalyst. This strategy is simple, albeit efficient, and can be extended to the synthesis of other composites of noble metals. It has opened a new window for the construction of hetero-nanocomposites with high activity and durability, which would serve as excellent models in catalytic systems of both theoretical and practical interest.This article reports a facile and controllable two-step method to construct TiO2-Pt@SiO2 nanocomposites. TiO2 nanoparticles (NPs), with small size and high surface energy, were synthesized by a solvothermal reaction process. The TiO2-Pt@SiO2 nanocomposites were fabricated by a reverse micro-emulsion method. SiO2 shell coated NPs were adopted for further photocatalytic reaction. Because of their small size and high surface energy, TiO2@SiO2 and TiO2-Pt@SiO2 nanocomposites show higher photocatalytic activity than commercial Degussa P25. Compared with TiO2@SiO2, TiO2-Pt@SiO2nanocomposites have improved photocatalytic activity due to the Pt induced spatial separation of electrons and holes. The silica shells not only maintain the structure of the

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

    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.

  7. Regional Cluster Development Measures and New Technology Based Firms Cultivation in Japan

    Kirihata, Tetsuya

    2008-01-01

    The aim of this paper is to reveal significant factors within a cluster that influence the fostering of new technology based firms (hereafter abbreviated NTBFs) and determine which measures should be given priority in aiding regional improvement. In this paper, a questionnaire survey was conducted with project directors of regional knowledge cluster headquarters promoted by the Ministry of Education, Culture, Sports, Science and Technology, NTBFs, as well as, external specialists such as atto...

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

    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/.

  9. Sound field measurement in a double layer cavitation cluster by rugged miniature needle hydrophones.

    Koch, Christian

    2016-03-01

    During multi-bubble cavitation the bubbles tend to organize themselves into clusters and thus the understanding of properties and dynamics of clustering is essential for controlling technical applications of cavitation. Sound field measurements are a potential technique to provide valuable experimental information about the status of cavitation clouds. Using purpose-made, rugged, wide band, and small-sized needle hydrophones, sound field measurements in bubble clusters were performed and time-dependent sound pressure waveforms were acquired and analyzed in the frequency domain up to 20 MHz. The cavitation clusters were synchronously observed by an electron multiplying charge-coupled device (EMCCD) camera and the relation between the sound field measurements and cluster behaviour was investigated. Depending on the driving power, three ranges could be identified and characteristic properties were assigned. At low power settings no transient and no or very low stable cavitation activity can be observed. The medium range is characterized by strong pressure peaks and various bubble cluster forms. At high power a stable double layer was observed which grew with further increasing power and became quite dynamic. The sound field was irregular and the fundamental at driving frequency decreased. Between the bubble clouds completely different sound field properties were found in comparison to those in the cloud where the cavitation activity is high. In between the sound field pressure amplitude was quite small and no collapses were detected. PMID:24953962

  10. Challenges for Precision Cosmology with X-ray and Sunyaev-Zeldovich Effect Gas Mass Measurements of Galaxy Clusters

    Hallman, Eric J.; Motl, Patrick M; Burns, Jack O.; Michael L. Norman

    2005-01-01

    We critically analyze the measurement of galaxy cluster gas masses, which is central to cosmological studies that rely on the galaxy cluster gas mass fraction. Using synthetic observations of numerically simulated clusters viewed through their X-ray emission and thermal Sunyaev-Zeldovich effect (SZE), we reduce the observations to obtain measurements of the cluster gas mass. We are thus able to quantify the possible sources of uncertainty and systematic bias associated with the common simplif...

  11. Investigation of parameters of chorus wave packets measured by the cluster spacecraft

    Complete text of publication follows. Chorus emissions are generated by a nonlinear mechanism involving wave-particle interaction with energetic electrons. Discrete chorus wave packets are narrow-band tones usually rising in frequency. Measurements of the Cluster spacecraft lead to the discovery of strong temporal and spatial variations of the amplitude in the source region. We investigate amplitudes and frequency sweep rates of chorus wave packets measured by the WBD instrument onboard Cluster. These parameters are related to the total electron density measured by the WHISPER active sounder. We compare the Cluster measurements with estimates based on the backward wave oscillator (BWO) model. Both show an increasing frequency sweep rate with the decreasing cold plasma density. Furthermore, investigations of chorus amplitudes and frequency sweep rates allow us to experimentally obtain important parameters of the BWO theory.

  12. Imputation of Continuous Tree Suitability over the Continental United States from Sparse Measurements Using Associative Clustering

    Hargrove, W. W.; Kumar, J.; Hoffman, F. M.; Potter, K. M.; Mills, R. T.

    2012-12-01

    Up-scaling from sparse measurements to a continuous raster of estimated values is a common problem in Earth System Science. We present a new general-purpose empirical imputation method based on associative clustering, which associates sparse measurements of dependent variables with particular multivariate clustered combinations of the independent variables, and then uses several methods to estimate values for unmeasured clusters, based on directional proximity in multidimensional data space, at both the cluster and map cell levels of resolution. We demonstrate this new imputation tool on tree species range distribution maps, which describe the suitable extent and expected growth performance of a particular tree species over a wide area. Range maps having continuous estimates of tree growth performance are more useful than more classical tree range maps that simply show binary occurence suitability. The USDA Forest Service Forest Inventory Assessment (FIA) plots provide information about the occurence and growth performance for various tree species across the US, but such measurements are limited to FIA plots. Using Associative Clustering, we scale up the discontinuous FIA Inventory growth measurements into continuous maps that show the expected growth and suitabilty for individual tree species covering the Continental United States. A multivariate cluster analysis was applied to global output from a General Circulation Model (GCM) consisting of 17 variables downscaled to 4km2 resolution. Present global growing conditions were divided into 30 thousand relatively homogeneous ecoregions describing climatic and topographic conditions. At every mapcell a multi-linear regression was applied in 17 dimensional hyperspace to derive the suitability of a tree species where not measured using the forest inventory data. The continuous species distribution maps obtained were compared and validated against existing tree range suitability maps. Associative Clustering is intended

  13. Clustering Protein Sequences Using Affinity Propagation Based on an Improved Similarity Measure

    Fan Yang

    2010-01-01

    Full Text Available The sizes of the protein databases are growing rapidly nowadays, thus it becomes increasingly important to cluster protein sequences only based on sequence information. In this paper we improve the similarity measure proposed by Kelil et al, then cluster sequences using the Affinity propagation (AP algorithm and provide a method to decide the input preference of AP algorithm. We tested our method extensively and compared its performance with other four methods on several datasets of COG, G protein, CAZy, SCOP database. We consistently observed that, the number of clusters that we obtained for a given set of proteins approximate to the correct number of clusters in that set. Moreover, in our experiments, the quality of the clusters when quantified by F-measure was better than that of other algorithms (on average, it is 15% better than that of BlastClust, 56% better than that of TribeMCL, 23% better than that of CLUSS, and 42% better than that of Spectral clustering.

  14. Sgr A$^*$: a laboratory to measure the central black hole and cluster parameters

    Nucita, A A; Ingrosso, G; Qadir, A; Zakharov, A F

    2007-01-01

    Several stars orbit around a black hole candidate of mass $3.7\\times 10^6$ M$_{\\odot}$, in the region of the Galactic Center (GC). Looking for General Relativistic (GR) periastron shifts is limited by the existence of a stellar cluster around the black hole that would modify the orbits due to classical effects that might mask the GR effect. Only if one knows the cluster parameters (its mass and core radius) it is possible to unequivocally deduce the GR effects expected and then test them. In this paper it is shown that the observation of the proper motion of Sgr A$^*$, $v_{Sgr A^*} = (0.4\\pm 0.9)$ km s$^{-1}$ (\\citealt{reid2004}), could help us to constrain the cluster parameters significantly and that future measurements of the periastron shifts for at least three stars may adequately determine the cluster parameters and the mass of the black hole.

  15. Sub-10 nm nano-gap device for single-cluster transport measurements

    We present a versatile procedure for the fabrication of single electron transistor (SET) devices with nanometer-sized clusters and embedded back gate electrode. The process uses sputtering gas-aggregation for the growth of clusters and e-beam lithography with double angle shadow-edge deposition to obtain electrodes separated by nano-gaps with width below 10 nm. The nano-gap width is easily controlled only by geometrical factors such as deposited thin film thickness and evaporation angles. The usefulness of this technique is demonstrated by measuring the SET behavior of a device with a 4 nm cobalt cluster embedded in alumina, where the Coulomb blockade and incremental cluster charging can be readily identified without resorting to the differential conductivity

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

    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.

  17. Measuring the dark flow with public X-ray cluster data

    Kashlinsky, A.; Atrio-Barandela, F.; Ebeling, H.

    2010-01-01

    We present new results on the "dark flow" from a measurement of the dipole in the distribution of peculiar velocities of galaxy clusters, applying the methodology proposed and developed by us earlier. Our latest measurement is conducted using new, low-noise 7-yr WMAP data as well as an all-sky sample of X-ray selected galaxy clusters compiled exclusively from published catalogs. Our analysis of the CMB signature of the kinematic Sunyaev-Zeldovich (SZ) effect finds a statistically significant ...

  18. Relative velocity of dark matter and barions in clusters of galaxies and measurements of their peculiar velocities

    Dolag, Klaus

    2013-01-01

    The increasing sensitivity of current experiments, which nowadays routinely measure the thermal SZ effect within galaxy clusters, provide the hope that peculiar velocities of individual clusters of galaxies will be measured rather soon using the kinematic SZ effect. Also next generation of X-ray telescopes with microcalorimeters, promise first detections of the motion of the intra cluster medium (ICM) within clusters. We used a large set of cosmological, hydrodynamical simulations, which cover very large cosmological volume, hosting a large number of rich clusters of galaxies, as well as moderate volumes where the internal structures of individual galaxy clusters can be resolved with very high resolution to investigate, how the presence of baryons and their associated physical processes like cooling and star-formation are affecting the systematic difference between mass averaged velocities of dark matter and the ICM inside a cluster. We, for the first time, quantify the peculiar motion of galaxy clusters as f...

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

    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.

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

    Oman, Kyle A.; Hudson, Michael J.

    2016-09-01

    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 (109 - 1011.5 M⊙) by massive (> 1013 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.

  1. Measuring Baryon Acoustic Oscillations from the clustering of voids

    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...

  2. HerMES: Halo Occupation Number and Bias Properties of Dusty Galaxies from Angular Clustering Measurements

    Cooray, Asantha; Wang, L; Altieri, B; Arumugam, V; Auld, R; Aussel, H; Babbedge, T; Blain, A; Bock, J; Boselli, A; Buat, V; Burgarella, D; Castro-Rodriguez, N; Cava, A; Chanial, P; Clements, D L; Conley, A; Conversi, L; Dowell, C D; Dwek, E; Eales, S; Elbaz, D; Farrah, D; Fox, M; Franceschini, A; Gear, W; Glenn, J; Griffin, M; Halpern, M; Hatziminaoglou, E; Ibar, E; Isaak, K; Ivison, R J; Khostovan, A A; Lagache, G; Levenson, L; Lu, N; Madden, S; Maffei, B; Mainetti, G; Marchetti, L; Marsden, G; Mitchell-Wynne, K; Mortier, A M J; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Page, M J; Panuzzo, P; Papageorgiou, A; Pearson, C P; ?rez-Fournon, I Pe; Pohlen, M; Rawlings, J I; Raymond, G; Rigopoulou, D; Rizzo, D; Roseboom, I G; Rowan-Robinson, M; Portal, M Sanchez; Schulz, B; Scott, Douglas; Serra, P; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Symeonidis, M; Trichas, M; Tugwell, K E; Vaccari, M; Valtchanov, I; Vieira, J D; Vigroux, L; Ward, R; Wright, G; Xu, C K; Zemcov, M

    2010-01-01

    We measure the angular correlation function, w(theta), from 0.5 to 30 arcminutes of detected sources in two wide fields of the Herschel Multi-tiered Extragalactic Survey (HerMES). Our measurements are consistent with the expected clustering shape from a population of sources that trace the dark matter density field, including non-linear clustering at arcminute angular scales arising from multiple sources that occupy the same dark matter halos. By making use of the halo model to connect the spatial clustering of sources to the dark matter halo distribution, we estimate source bias and halo occupation number for dusty sub-mm galaxies at z ~ 2. We find that sub-mm galaxies with 250 micron flux densities above 30 mJy reside in dark matter halos with mass above (5\\pm4) x 10^12 M_sun, while (14\\pm8)% of such sources appear as satellites in more massive halos.

  3. Measurements of Laser Absorption and Ion Energy in Femtosecond Laser-Cluster Interaction

    LIN Jing-Quan; ZHANG Jie; LI Ying-Jun; CHEN Li-Ming; LU Tie-Zheng; TENG Hao; MAN Bao-Yuan; ZHAO Li-Zeng

    2001-01-01

    Laser absorption is measured in Xe, Ar and He clusters irradiated by 5 mJ laser pulses in 150 fs. The measurements show that the absorption efficiency strongly depends on the backing pressure of the gas jets, the laser pulse duration and the atomic number Z of the working gas. The laser absorption for Xe clusters is found to be as high as 45% at a backing pressure of 20atm and a laser intensity of 1 × 1015 W/cm2. Significant numbers of ions with energies up to 100keV are detected from Xe cluster explosion. The variation trend of the average ion energy at different backing pressures is consistent with that of the laser energy absorption.

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

    Ms K.Santhisree; Dr. A Damodaram

    2011-01-01

    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, Cosin...

  5. Measuring baryon acoustic oscillations from the clustering of voids

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

    2016-07-01

    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 dependence 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 methodology on an additional set of 1000 realistic mock galaxy catalogues reproducing the SDSS-III/BOSS CMASS DR11 data, to control the impact of sky mask and radial selection function. Our solution is based on generating voids from randoms including the same survey geometry and completeness, and a post-processing cleaning procedure in the holes and at the boundaries of the survey. The methodology and optimal selection of void populations validated in this work have been used to perform the first BAO detection from voids in observations, presented in a companion paper.

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

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

    2015-12-01

    We develop a novel method of measuring the lensing distortion profiles of clusters by stacking the "scaled" amplitudes of background galaxy ellipticities as a function of the "scaled" centric radius according to the Navarro-Frenk-White (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 a suite of 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 ≤ z ≤ 0.3, where their halo masses differ from each other by up to a factor of 10. 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 scaling relation of halo concentration with halo mass. We evaluate the performance of the NFW scaling analysis by measuring the scatters of 50 cluster lensing profiles relative to the NFW predictions over a range of radii, 0.14 ≤ R/[h-1 Mpc] ≤ 2.8. We found 4-6 σ-level evidence of the universal NFW profile in 50 clusters, for both the X-ray halo mass proxy relations, although the gas mass appears to be a better proxy of the underlying true mass. By comparing the measurements with the simulations of cluster lensing profiles taking into account the statistical errors of intrinsic galaxy shapes in the Subaru data, we argue that additional halo mass errors or intrinsic scatters of σ(M500c)/M500c ˜ 0.2-0.3 could reconcile the difference between measurements and simulations. This method allows us to some extent to preserve characteristics of individual clusters in the statistical weak lensing analysis, thereby yielding a new means of exploiting the underlying genuine

  7. CLUSS: Clustering of protein sequences based on a new similarity measure

    Brzezinski Ryszard

    2007-08-01

    Full Text Available Abstract Background The rapid burgeoning of available protein data makes the use of clustering within families of proteins increasingly important. The challenge is to identify subfamilies of evolutionarily related sequences. This identification reveals phylogenetic relationships, which provide prior knowledge to help researchers understand biological phenomena. A good evolutionary model is essential to achieve a clustering that reflects the biological reality, and an accurate estimate of protein sequence similarity is crucial to the building of such a model. Most existing algorithms estimate this similarity using techniques that are not necessarily biologically plausible, especially for hard-to-align sequences such as proteins with different domain structures, which cause many difficulties for the alignment-dependent algorithms. In this paper, we propose a novel similarity measure based on matching amino acid subsequences. This measure, named SMS for Substitution Matching Similarity, is especially designed for application to non-aligned protein sequences. It allows us to develop a new alignment-free algorithm, named CLUSS, for clustering protein families. To the best of our knowledge, this is the first alignment-free algorithm for clustering protein sequences. Unlike other clustering algorithms, CLUSS is effective on both alignable and non-alignable protein families. In the rest of the paper, we use the term "phylogenetic" in the sense of "relatedness of biological functions". Results To show the effectiveness of CLUSS, we performed an extensive clustering on COG database. To demonstrate its ability to deal with hard-to-align sequences, we tested it on the GH2 family. In addition, we carried out experimental comparisons of CLUSS with a variety of mainstream algorithms. These comparisons were made on hard-to-align and easy-to-align protein sequences. The results of these experiments show the superiority of CLUSS in yielding clusters of proteins

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

    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…

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

    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

    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. Cluster-randomized trial of a German leisure-based alcohol peer education measure

    Bühler, Anneke; Thrul, Johannes; Strüber, Evelin; Orth, Boris

    2015-01-01

    Because of scarce research, the effectiveness of substance abuse prevention in leisure settings remains unclear. In this study, we evaluated the effectiveness of a peer-led educational prevention measure with adolescent groups in unstructured leisure settings, which is a component of the complex German nationwide ‘Na Toll!’ campaign. Using a cluster-randomized two-group post-test-only design, we tested whether the measure influenced component-specific goals, namely risk and protective factors...

  12. Large carbon cluster thin film gauges for measuring aerodynamic heat transfer rates in hypersonic shock tunnels

    Different types of Large Carbon Cluster (LCC) layers are synthesized by a single-step pyrolysis technique at various ratios of precursor mixture. The aim is to develop a fast responsive and stable thermal gauge based on a LCC layer which has relatively good electrical conduction in order to use it in the hypersonic flow field. The thermoelectric property of the LCC layer has been studied. It is found that these carbon clusters are sensitive to temperature changes. Therefore suitable thermal gauges were developed for blunt cone bodies and were tested in hypersonic shock tunnels at a flow Mach number of 6.8 to measure aerodynamic heating. The LCC layer of this thermal gauge encounters high shear forces and a hostile environment for test duration in the range of a millisecond. The results are favorable to use large carbon clusters as a better sensor than a conventional platinum thin film gauge in view of fast responsiveness and stability. (paper)

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

    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...

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

    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...

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

    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.

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

    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. PMID:27579031

  17. Coordinated target localization base on pseudo measurement for clustered space robot

    Zhai Guang; Zhang Jingrui; Zhou Zhicheng

    2013-01-01

    This paper presents a coordinated target localization method for clustered space robot. According to the different measuring capabilities of cluster members, the master-slave coordinated relative navigation strategy for target localization with respect to slavery space robots is proposed;then the basic mathematical models, including coordinated relative measurement model and cluster centralized dynamics, are established respectively. By employing the linear Kalman filter theorem, the centralized estimator based on truth measurements is developed and analyzed firstly, and with an intention to inhabit the initial uncertainties related to target localization, the globally stabilized estimator is designed through introduction of pseudo measurements. Furthermore, the observabil-ity and controllability of stochastic system are also analyzed to qualitatively evaluate the conver-gence performance of pseudo measurement estimator. Finally, on-orbit target approaching scenario is simulated by using semi-physical simulation system, which is used to verify the conver-gence performance of proposed estimator. During the simulation, both the known and unknown maneuvering acceleration cases are considered to demonstrate the robustness of coordinated local-ization strategy.

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

    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...

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

    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...

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

    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...

  1. Surface-Regulated Nano-SnO2/Pt3Co/C Cathode Catalysts for Polymer Electrolyte Fuel Cells Fabricated by a Selective Electrochemical Sn Deposition Method.

    Nagasawa, Kensaku; Takao, Shinobu; Nagamatsu, Shin-ichi; Samjeské, Gabor; Sekizawa, Oki; Kaneko, Takuma; Higashi, Kotaro; Yamamoto, Takashi; Uruga, Tomoya; Iwasawa, Yasuhiro

    2015-10-14

    We have achieved significant improvements for the oxygen reduction reaction activity and durability with new SnO2-nanoislands/Pt3Co/C catalysts in 0.1 M HClO4, which were regulated by a strategic fabrication using a new selective electrochemical Sn deposition method. The nano-SnO2/Pt3Co/C catalysts with Pt/Sn = 4/1, 9/1, 11/1, and 15/1 were characterized by STEM-EDS, XRD, XRF, XPS, in situ XAFS, and electrochemical measurements to have a Pt3Co core/Pt skeleton-skin structure decorated with SnO2 nanoislands at the compressive Pt surface with the defects and dislocations. The high performances of nano-SnO2/Pt3Co/C originate from efficient electronic modification of the Pt skin surface (site 1) by both the Co of the Pt3Co core and surface nano-SnO2 and more from the unique property of the periphery sites of the SnO2 nanoislands at the compressive Pt skeleton-skin surface (more active site 2), which were much more active than expected from the d-band center values. The white line peak intensity of the nano-SnO2/Pt3Co/C revealed no hysteresis in the potential up-down operations between 0.4 and 1.0 V versus RHE, unlike the cases of Pt/C and Pt3Co/C, resulting in the high ORR performance. Here we report development of a new class of cathode catalysts with two different active sites for next-generation polymer electrolyte fuel cells. PMID:26412503

  2. The Integrated Sunyaev-Zeldovich Effect as the Superior Method for Measuring the Mass of Clusters of Galaxies

    Motl, P M; Burns, J O; Norman, M L; Motl, Patrick M.; Hallman, Eric J.; Burns, Jack O.; Norman, Michael L.

    2005-01-01

    We investigate empirical scaling relations between the thermal Sunyaev-Zeldovich effect (SZE) and cluster mass in simulated clusters of galaxies. The simulated clusters have been compiled from four different samples that differ only in their assumed baryonic physics. We show that the strength of the thermal SZE integrated over a significant fraction of the virialized region of the clusters is relatively insensitive to the detailed heating and cooling processes in the cores of clusters by demonstrating that the derived scaling relations are nearly identical between the four cluster samples considered. For our synthetic images, the central Comptonization parameter shows significant boosting during transient merging events, but the integrated SZE appears to be relatively insensitive to these events. Most importantly, the integrated SZE closely tracks the underlying cluster mass. Observations through the thermal SZE allow a strikingly accurate mass estimation from relatively simple measurements that do not requir...

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

    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.

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

    Jokinen, T; Sipilä, M.; Junninen, H.; M. Ehn; Lönn, G.; Hakala, J.; T. Petäjä; R. L. Mauldin III; M. Kulmala; Worsnop, D.R.

    2011-01-01

    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. Si...

  5. Clustering of reads with alignment-free measures and quality values

    Comin, Matteo; Leoni, Andrea; Schimd, Michele

    2015-01-01

    Background The data volume generated by Next-Generation Sequencing (NGS) technologies is growing at a pace that is now challenging the storage and data processing capacities of modern computer systems. In this context an important aspect is the reduction of data complexity by collapsing redundant reads in a single cluster to improve the run time, memory requirements, and quality of post-processing steps like assembly and error correction. Several alignment-free measures, based on k-mers count...

  6. Relativistic rise measurement by cluster counting method in time expansion chamber

    A new approach to the measurement of the ionization energy loss for the charged particle identification in the region of the relativistic rise was tested experimentally. The method consists of determining in a special drift chamber (TEC) the number of clusters of the primary ionization. The method gives almost the full relativistic rise and narrower landau distribution. The consequences for a practical detector are discussed

  7. Managing spacecraft measurements over a decade: The calibration and archiving of Cassini and Cluster magnetometer data

    Alconcel, L.; Fox, P.; Kellock, S. J.; Brown, P.; Lucek, E. A.; Carr, C.; Dougherty, M. K.

    2013-12-01

    As the PI institute for the magnetometer (MAG) team on the Cassini-Huygens mission to Saturn, Imperial College has been responsible for routinely delivering high quality data to NASA's Planetary Data System (PDS) since 2004. The PDS maintains an archive of information from planetary missions to allow easy user access through a web browser and provides confidence that the data has been rigorously validated. Furthermore, the data calibration yields a sensitive gauge of changes on board the spacecraft and a way to assess the risk of certain activities. When the four Earth-observing Cluster spacecraft were launched in late 2000, a framework for producing and exchanging uniform scientific data sets was already in place. It would form the basis of ESA's Cluster Active Archive (CAA) to which Imperial College, as the PI institute for the fluxgate magnetometers (FGM), has regularly contributed calibrated and validated data. Like the PDS, the CAA aims to preserve the Cluster mission information so that it remains accessible and usable in the long term. The FGM team has archived high resolution data for the mission from January 2001 to April 2013. To demonstrate the stability of our instruments, we have studied the long-term trends in both the Cassini MAG and Cluster FGM data sets. The results help us to establish confidence in the relative accuracy of the measurements. Moreover, they plainly exhibit the necessity of the calibration and archiving activities for high-value scientific space missions.

  8. Challenges for Precision Cosmology with X-Ray and Sunyaev-Zeldovich Effect Gas Mass Measurements of Galaxy Clusters

    Hallman, Eric J.; Motl, Patrick M.; Burns, Jack O.; Norman, Michael L.

    2006-09-01

    We critically analyze the measurement of galaxy cluster gas masses, which is central to cosmological studies that rely on the galaxy cluster gas mass fraction. Using synthetic observations of numerically simulated clusters viewed through their X-ray emission and thermal Sunyaev-Zeldovich effect (SZE), we reduce the observations to obtain measurements of the cluster gas mass. We quantify the possible sources of uncertainty and systematic bias associated with the common simplifying assumptions used in reducing real cluster observations, including isothermality and hydrostatic equilibrium. We find that intrinsic variations in clusters limit the precision of observational gas mass estimation to ~10% to 1 σ confidence, excluding instrumental effects. Gas mass estimates show surprisingly little trending in the scatter as a function of cluster redshift. For the full cluster sample, methods that use SZE profiles out to roughly the virial radius are the simplest, most accurate, and unbiased way to estimate cluster mass. X-ray methods are systematically more precise mass estimators than are SZE methods if merger and cool-core systems are removed, but slightly overestimate (5%-10%) the cluster gas mass on average. We find that cool-core clusters in our samples are particularly poor candidates for observational mass estimation, even when excluding emission from the core region. The effects of cooling in the cluster gas alter the radial profile of the X-ray and SZE surface brightness even outside the cool-core region. Finally, we find that methods using a universal temperature profile estimate cluster masses to higher precision than those assuming isothermality.

  9. Measuring the density of a molecular cluster injector via visible emission from an electron beam

    A method to measure the density distribution of a dense hydrogen gas jet is presented. A Mach 5.5 nozzle is cooled to 80 K to form a flow capable of molecular cluster formation. A 250 V, 10 mA electron beam collides with the jet and produces Hα emission that is viewed by a fast camera. The high density of the jet, several 1016 cm-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.

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

    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. A study on low-power, nanosecond operation and multilevel bipolar resistance switching in Ti/ZrO2/Pt nonvolatile memory with 1T1R architecture

    Low-power, bipolar resistive switching (RS) characteristics in the Ti/ZrO2/Pt nonvolatile memory with one transistor and one resistor (1T1R) architecture were reported. Multilevel storage behavior was observed by modulating the amplitude of the MOSFET gate voltage, in which the transistor functions as a current limiter. Furthermore, multilevel storage was also executed by controlling the reset voltage, leading the resistive random access memory (RRAM) to the multiple metastable low resistance state (LRS). The experimental results on the measured electrical properties of the various sized devices confirm that the RS mechanism of the Ti/ZrO2/Pt structure obeys the conducting filaments model. In application, the devices exhibit high-speed switching performances (250 ns) with suitable high/low resistance state ratio (HRS/LRS > 10). The LRS of the devices with 10 year retention ability at 80 °C, based on the Arrhenius equation, is also demonstrated in the thermal accelerating test. Furthermore, the ramping gate voltage method with fixed drain voltage is used to switch the 1T1R memory cells for upgrading the memory performances. Our experimental results suggest that the ZrO2-based RRAM is a prospective alternative for nonvolatile multilevel memory device applications. (paper)

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

    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. Detectability of Torsion Gravity via Galaxy Clustering and Cosmic Shear Measurements

    Camera, Stefano; Radicella, Ninfa

    2013-01-01

    Alterations of the gravity Lagrangian introduced in modified torsion gravity theories - also referred to as f(T) gravity - allows for an accelerated expansion in a matter dominated Universe. In this framework, the cosmic speed up is driven by an effective 'torsion fluid'. Besides the background evolution of the Universe, structure formation is also modified because of a time dependent effective gravitational constant. Here, we investigate the imprints of f(T) gravity on galaxy clustering and weak gravitational lensing to the aim of understanding whether future galaxy surveys could constrain torsion gravity and discriminate amongst it and standard general relativity. Specifically, we compute Fisher matrix forecasts for two viable f(T) models to both infer the accuracy on the measurement of the model parameters and evaluate the power that a combined clustering and shear analysis will have as a tool for model selection. We find that with such a combination of probes it will indeed be possible to tightly constrai...

  14. A bent electrostatic ion beam trap for simultaneous measurements of fragmentation and ionization of cluster ions.

    Aviv, O; Toker, Y; Errit, M; Bhushan, K G; Pedersen, H B; Rappaport, M L; Heber, O; Schwalm, D; Zajfman, D

    2008-08-01

    We describe a bent electrostatic ion beam trap in which cluster ions of several keV kinetic energy can be stored on a V-shaped trajectory by means of an electrostatic deflector placed between two electrostatic mirrors. While maintaining all the advantages of its linear counterpart [Zajfman et al., Phys. Rev. A 55, R1577 (1997); Dahan et al., Rev. Sci. Instrum. 69, 76 (1998)], such as long storage times, straight segments, and a field-free region for merged or crossed beam experiments, the bent trap allows for simultaneous measurement of charged and neutral fragments and determination of the average kinetic energy released in the fragmentation. These unique properties of the bent trap are illustrated by first results concerning the competition between delayed fragmentation and ionization of Al(n) (-) clusters after irradiation by a short laser pulse. PMID:19044339

  15. A bent electrostatic ion beam trap for simultaneous measurements of fragmentation and ionization of cluster ions

    We describe a bent electrostatic ion beam trap in which cluster ions of several keV kinetic energy can be stored on a V-shaped trajectory by means of an electrostatic deflector placed between two electrostatic mirrors. While maintaining all the advantages of its linear counterpart [Zajfman et al., Phys. Rev. A 55, R1577 (1997); Dahan et al., Rev. Sci. Instrum. 69, 76 (1998)], such as long storage times, straight segments, and a field-free region for merged or crossed beam experiments, the bent trap allows for simultaneous measurement of charged and neutral fragments and determination of the average kinetic energy released in the fragmentation. These unique properties of the bent trap are illustrated by first results concerning the competition between delayed fragmentation and ionization of Aln- clusters after irradiation by a short laser pulse

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

    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. Plasma Wave Measurements in Earth's Magnetosphere by Juno, Van Allen Probes, and Cluster

    Kurth, W. S.; Hospodarsky, G. B.; Bolton, S. J.; Gurnett, D. A.; Santolik, O.; Kletzing, C.; Thorne, R. M.; Pickett, J. S.

    2013-12-01

    On October 9, 2013, Juno will fly within about 550 km of Earth in the process of executing a gravity assist on its way to its eventual arrival at Jupiter in July 2016. Since this will be the only magnetospheric plasma regime Juno will sample prior to arrival at Jupiter, it presents both engineering and scientific opportunities. One of the scientific opportunities is to make observations in the inner magnetosphere at the same time as the twin Van Allen Probes and Cluster. During the Juno flyby, which is on the dusk side at closest approach, the Van Allen Probes' apoapsis is also in the dusk sector. The Cluster orbits favor comparisons on the nightside after Juno's closest approach. Models of the radiation belts suggest that Juno will traverse both the inner and outer belts, albeit at higher latitudes than the low-inclination Van Allen Probes while the Cluster spacecraft are in a rather high inclination orbit. The Waves instrument on Juno utilizes a single electric dipole antenna and a single search coil sensor for measurements of the electric and magnetic components of plasma waves, consequently it will provide wave spectra and brief bursts of waveforms. The Waves instrument on Van Allen Probes, on the other hand makes triaxial electric and magnetic measurements of plasma waves, hence, can determine the propagation characteristics of waves such as the wave-normal angle, Poynting flux, and polarization characteristics of the waves. The Wideband Instrument on Cluster can be configured to capture single axis (electric or magnetic) waveforms at selected times to coincide with Juno and Van Allen Probes burst observations. We will compare observations of whistler-mode emissions and electron cyclotron harmonic emissions in and near the radiation belts from the vantage points of these spacecraft.

  18. LoCuSS: A Comparison of Sunyaev-Zel'dovich Effect and Gravitational Lensing Measurements of Galaxy Clusters

    Marrone, Daniel P; Richard, Johan; Joy, Marshall; Bonamente, Massimiliano; Hasler, Nicole; Hamilton-Morris, Victoria; Kneib, Jean-Paul; Culverhouse, Thomas; Carlstrom, John E; Greer, Christopher; Hawkins, David; Hennessy, Ryan; Lamb, James W; Leitch, Erik M; Loh, Michael; Miller, Amber; Mroczkowski, Tony; Muchovej, Stephen; Pryke, Clem; Sharp, Matthew K; Woody, David

    2009-01-01

    We present the first measurement of the relationship between the Sunyaev-Zel'dovich effect signal and the mass of galaxy clusters that uses gravitational lensing to measure cluster mass, based on 14 X-ray luminous clusters at z~0.2 from the Local Cluster Substructure Survey. We measure the integrated Compton y-parameter, Y, and total projected mass of the clusters (M_GL) within a projected clustercentric radius of 350 kpc, corresponding to mean overdensities of 4000-8000 relative to the critical density. We find self-similar scaling between M_GL and Y, with a scatter in mass at fixed Y of 32%. This scatter exceeds that predicted from numerical cluster simulations, however, it is smaller than comparable measurements of the scatter in mass at fixed T_X. We also find no evidence of segregation in Y between disturbed and undisturbed clusters, as had been seen with T_X on the same physical scales. We compare our scaling relation to the Bonamente et al. relation based on mass measurements that assume hydrostatic eq...

  19. A new experimental setup for high-pressure catalytic activity measurements on surface deposited mass-selected Pt clusters

    A new experimental setup to study catalytic and electronic properties of size-selected clusters on metal oxide substrates from the viewpoint of cluster-support interaction and to formulate a method for the development of heterogeneous catalysts such as automotive exhaust catalysts has been developed. The apparatus consists of a size-selected cluster source, a photoemission spectrometer, a scanning tunneling microscope (STM), and a high-pressure reaction cell. The high-pressure reaction cell measurements provided information on catalytic properties in conditions close to practical use. The authors investigated size-selected platinum clusters deposited on a TiO2(110) surface using a reaction cell and STM. Catalytic activity measurements showed that the catalytic activities have a cluster-size dependency.

  20. First Measurement of the Clustering Evolution of Photometrically-Classified Quasars

    Myers, A D; Richards, G T; Nichol, R C; Schneider, D P; Vanden Berk, Daniel E; Scranton, R; Gray, A G; Brinkmann, J; Myers, Adam D.; Brunner, Robert J.; Richards, Gordon T.; Nichol, Robert C.; Schneider, Donald P.; Berk, Daniel E. Vanden; Scranton, Ryan; Gray, Alexander G.; Brinkmann, Jon

    2006-01-01

    We present new measurements of the quasar autocorrelation from a sample of \\~80,000 photometrically-classified quasars taken from SDSS DR1. We find a best-fit model of $\\omega(\\theta) = (0.066\\pm^{0.026}_{0.024})\\theta^{-(0.98\\pm0.15)}$ for the angular autocorrelation, consistent with estimates from spectroscopic quasar surveys. We show that only models with little or no evolution in the clustering of quasars in comoving coordinates since z~1.4 can recover a scale-length consistent with local galaxies and Active Galactic Nuclei (AGNs). A model with little evolution of quasar clustering in comoving coordinates is best explained in the current cosmological paradigm by rapid evolution in quasar bias. We show that quasar biasing must have changed from b_Q~3 at a (photometric) redshift of z=2.2 to b_Q~1.2-1.3 by z=0.75. Such a rapid increase with redshift in biasing implies that quasars at z~2 cannot be the progenitors of modern L* objects, rather they must now reside in dense environments, such as clusters. Simil...

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

    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...

  2. New Neutron-capture Measurements in 23 Open Clusters. I. The r-Process

    Overbeek, Jamie C.; Friel, Eileen D.; Jacobson, Heather R.

    2016-06-01

    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 are 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 homogeneous 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, and Nd) have insignificant trends consistent with zero. Pr, Nd, Eu, Gd, and Dy have similar, slight (although mostly statistically significant) gradients of ˜0.04 dex kpc‑1. The mixed elements also appear to have nonlinear relationships with R GC.

  3. New Neutron-capture Measurements in 23 Open Clusters. I. The r-Process

    Overbeek, Jamie C.; Friel, Eileen D.; Jacobson, Heather R.

    2016-06-01

    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 are 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 homogeneous 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, and Nd) have insignificant trends consistent with zero. Pr, Nd, Eu, Gd, and Dy have similar, slight (although mostly statistically significant) gradients of ∼0.04 dex kpc‑1. The mixed elements also appear to have nonlinear relationships with R GC.

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

    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

  5. A Monte Carlo investigation of two distance measures between statistical populations and their application to cluster analysis

    Rossa, Agnieszka

    1997-01-01

    The paper deals with a simulation study of one of the well-known hierarchical cluster analysis methods applied to classifying the statistical populations. In particular, the problem of clustering the univariate normal populations is studied. Two measures of the distance between statistical populations are considered: the Mahalanobis distance measure which is defined for normally distributed populations under assumption that the covariance matrices are equal and the Kullback-Lei...

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

    Jokinen, T; Sipilä, M.; Junninen, H.; M. Ehn; Lönn, G.; Hakala, J.; T. Petäjä; Mauldin, R. L.; M. Kulmala; Worsnop, D.R.

    2012-01-01

    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 f...

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

    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.

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

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

    Ms K.Santhisree

    2011-09-01

    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.

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

    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.

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

    Veropalumbo, A.; Marulli, F.; Moscardini, L.; Moresco, M.; Cimatti, A.

    2016-05-01

    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, 0.3 and 0.5. The number of objects is 12 910, 42 215 and 11 816, respectively. We detect the peak of baryon acoustic oscillations for all the three samples. The derived distance constraints are rs/DV(z = 0.2) = 0.18 ± 0.01, rs/DV(z = 0.3) = 0.124 ± 0.004 and rs/DV(z = 0.5) = 0.080 ± 0.002. Combining these measurements with the sound horizon scale measured from the cosmic microwave background, we obtain robust constraints on cosmological parameters. Our results are in agreement with the standard Λ cold dark matter (ΛCDM) model. Specifically, we constrain the Hubble constant in a ΛCDM model, H_0 = 64_{-8}^{+17} km s^{-1} Mpc^{-1} , the density of curvature energy, in the oΛCDM context, Ω _K = -0.01_{-0.33}^{+0.34}, and finally the parameter of the dark energy equation of state in the wCDM case, w = -1.06_{-0.52}^{+0.49}. This is the first time the distance-redshift relation has been constrained using only the peak of baryon acoustic oscillations of galaxy clusters.

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

    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.

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

    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.

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

    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}_...

  15. Acoustic emission measurement in a 20MJ superconducting magnet system of the cluster test coil

    This paper describes acoustic emission (AE) results which were measured during the second major experiment on the Cluster Test Coil at JAERI. This is the largest superconducting magnet system to date on which acoustic emission measurement has been carried out. The amplitudes and the counting rates of AE are shown as functions of coil operating current on three full current excursions. The amplitude results show the on-going process of emission and reduction during successive runs. A strong tendency of the AE counting rate to increase was observed at high currents after successive runs. The phenomenon of amplitude reduction and counting rate increase is attributed to an energy release change from larger single events to numerous smaller events. (author)

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

    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.

  17. Measuring the luminosity and virial black hole mass dependence of quasar-galaxy clustering at z ~ 0.8

    Krolewski, Alex G

    2015-01-01

    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 WISE about z $\\sim$ 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 $\\sim$ 0.8 quasars at 0.2--6.4 h$^{-1}$ 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 $\\pm$ 0.06 (1 $\\sigma$ errorbar). We also fail to find a significant relationship between clustering ampli...

  18. Cluster boundary layer measurements and optical observations at magnetically conjugate sites

    J. Moen

    Full Text Available The Cluster spacecraft experienced several boundary layer encounters when flying outbound from the magnetosphere to the magnetosheath in the dusk sector on 14 January 2001. The dayside boundary layer was populated by magnetosheath electrons, but not with quite as high densities as in the magnetosheath itself. The Cluster ground track was calculated using the Tsyganenko-96 model which appears to be a strong tool for combining high-altitude satellite and ground observations, given that the solar wind conditions are known. This paper focuses on identifying auroral responses corresponding to boundary layer dynamics observed by Cluster. The first boundary layer encounter studied was a brief visit into a closed LLBL, most likely due to a boundary wave that travelled tailward over the spacecraft. A corresponding equatorward and eastward movement was seen in the post-noon aurora between Greenland and Svalbard. The second boundary encounter was in a high-latitude cusp, and occurred as a consequence of a transient reconfiguration of the cusp. The cusp expanded duskward over the spacecraft into the late post-noon sector. NOAA-12 probed the 16:30 MLT sector of this auroral activity, and measured a 1.4 keV electron beam located poleward of the 30 keV electron-trapping boundary. A sequence of three moving auroral forms emanating from this active region are likely candidates for flux transfer events. The auroral signatures are discussed in relation to earlier observations, and appear to be an example of accelerated electrons/discrete post-noon aurora on open magnetic field lines.

    Key words. Ionosphere (particle precipitation Magnetospheric physics (auroral phenomena; magnetopause, cusp and boundary layers

  19. Blue emitting undecaplatinum clusters

    Chakraborty, Indranath; Bhuin, Radha Gobinda; Bhat, Shridevi; Pradeep, T.

    2014-07-01

    A blue luminescent 11-atom platinum cluster showing step-like optical features and the absence of plasmon absorption was synthesized. The cluster was purified using high performance liquid chromatography (HPLC). Electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) suggest a composition, Pt11(BBS)8, which was confirmed by a range of other experimental tools. The cluster is highly stable and compatible with many organic solvents.A blue luminescent 11-atom platinum cluster showing step-like optical features and the absence of plasmon absorption was synthesized. The cluster was purified using high performance liquid chromatography (HPLC). Electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) suggest a composition, Pt11(BBS)8, which was confirmed by a range of other experimental tools. The cluster is highly stable and compatible with many organic solvents. Electronic supplementary information (ESI) available: Details of experimental procedures, instrumentation, chromatogram of the crude cluster; SEM/EDAX, DLS, PXRD, TEM, FT-IR, and XPS of the isolated Pt11 cluster; UV/Vis, MALDI MS and SEM/EDAX of isolated 2 and 3; and 195Pt NMR of the K2PtCl6 standard. See DOI: 10.1039/c4nr02778g

  20. Spatially Constrained Geospatial Data Clustering for Multilayer Sensor-Based Measurements

    Dhawale, N. M.; Adamchuk, V. I.; Prasher, S. O.; Dutilleul, P. R. L.; Ferguson, R. B.

    2014-11-01

    One of the most popular approaches to process high-density proximal soil sensing data is to aggregate similar measurements representing unique field conditions. An innovative constraint-based spatial clustering algorithm has been developed. The algorithm seeks to minimize the mean squared error during the interactive grouping of spatially adjacent measurements similar to each other and different from the other parts of the field. After successful implementation of a one soil property scenario, this research was to accommodate multiple layers of soil properties representing the same area under investigation. Six agricultural fields across Nebraska, USA, were chosen to illustrate the algorithm performance. The three layers considered were field elevation and apparent soil electrical conductivity representing both deep and shallow layers of the soil profile. The algorithm was implemented in MATLAB, R2013b. Prior to the process of interactive grouping, geographic coordinates were projected and erroneous data were filtered out. Additional data pre-processing included bringing each data layer to a 20 × 20 m raster to facilitate multi-layer computations. An interactive grouping starts with a new "nest" search to initiate the first group of measurements that are most different from the rest of the field. This group is grown using a neighbourhood search approach and once growing the group fails to reduce the overall mean squared error, the algorithm seeks to locate a new "nest", which will grow into another group. This process continues until there is no benefit from separating out an additional part of the field. Results of the six-field trial showed that each case generated a reasonable number of groups which corresponded to agronomic knowledge of the fields. The unique feature of this approach is spatial continuity of each group and capability to process multiple data layers. Further development will involve comparison with a more traditional k-means clustering approach

  1. COSMOS: STOCHASTIC BIAS FROM MEASUREMENTS OF WEAK LENSING AND GALAXY CLUSTERING

    In the theory of structure formation, galaxies are biased tracers of the underlying matter density field. The statistical relation between galaxy and matter density field is commonly referred to as galaxy bias. In this paper, we test the linear bias model with weak-lensing and galaxy clustering measurements in the 2 deg2 COSMOS field. We estimate the bias of galaxies between redshifts z = 0.2 and z = 1 and over correlation scales between R = 0.2 h–1 Mpc and R = 15 h–1 Mpc. We focus on three galaxy samples, selected in flux (simultaneous cuts I814W s 9 * 10 h–2 M☉ and 1010 * 11 h–2 M☉). At scales R > 2 h–1 Mpc, our measurements support a model of bias increasing with redshift. The Tinker et al. fitting function provides a good fit to the data. We find the best-fit mass of the galaxy halos to be log (M200/h–1 M☉) = 11.7+0.6–1.3 and log (M200/h–1 M☉) = 12.4+0.2–2.9, respectively, for the low and high stellar-mass samples. In the halo model framework, bias is scale dependent with a change of slope at the transition scale between the one and the two halo terms. We detect a scale dependence of bias with a turndown at scale R = 2.3 ± 1.5 h–1 Mpc, in agreement with previous galaxy clustering studies. We find no significant amount of stochasticity, suggesting that a linear bias model is sufficient to describe our data. We use N-body simulations to quantify both the amount of cosmic variance and systematic errors in the measurement.

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

    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.

  3. Measuring incident light on grape clusters using photosensitive paper and image analysis

    Digital imaging and analysis was used to quantify and characterize the light exposure patterns of photosensitive paper tubes placed in representative cluster positions in two grape (Vitis vinifera L.) canopies: a minimally pruned and a vertically trained canopy. Blue pixel values of the captured images had a negative correlation with the log of irradiance from an integrating quantum sensor (r2 = 0.9308). The spectral response of the photosensitive paper was not measured. Histograms of incident light distribution on individual paper tubes were developed using imaging software. Histograms were able to quantify the distribution of incident light on individual tubes and were clearly related to the tube's exposure in the canopy. Average population curves of pixel light distribution of 20 tubes in each canopy were able to differentiate the typical cluster light environment in the two canopies. Tubes in the minimally pruned canopy had a larger proportion of their surface exposed to irradiances > 50 micromoles.s-1 m-2 and 65% higher average irradiance than the vertical canopy. Image analysis of photosensitive paper appears to be a workable method to record the distribution of incident light in plant canopies and may have utility in a range of ecological studies

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

    Sengupta, Debarka; Aich, Indranil; Bandyopadhyay, Sanghamitra

    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. PMID:26564974

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

    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.

  6. Still Red and Dead? Measuring feedback and star-formation in clusters at z > 1

    Khullar, Gourav; McDonald, Michael; Bleem, Lindsey; Benson, Bradford; Gladders, Michael; South Pole Telescope (SPT) Collaboration

    2016-06-01

    Optical and infrared (IR) surveys have discovered that galaxy clusters at z 2 and underwent passive evolution thereafter without dominant star formation, some samples indicate that an era of star formation and AGN activity is seen in cluster galaxies at z > 1. Only recently have large samples of z > 1 clusters been identified, mostly through IR and Sunyaev-Zel’dovich (SZ) surveys, which indicate an increase in SFR in clusters at high redshifts and incomplete quenching. Moreover, a robust cluster sample in-hand allows us to understand how galaxy clusters become "red and dead", and the role of astrophysical feedback in this process. The South Pole Telescope (SPT) collaboration has produced mass-limited redshift-independent catalog of 516 clusters from 0.0 1.0, with three newly found systems having a zphot > 1.5. In this work, we focus on a sub-sample of SPT-SZ selected clusters at z > 1.2 with multi-wavelength observations in X-ray (Chandra), infrared (Herschel, Spitzer), optical (Magellan - imaging and spectroscopy), and mm-wavelength (SPT) bands. These observations enable constraints on cluster stellar, baryonic, and total mass, in addition to a host of other information, including the star-formation rate, level of AGN activity, cluster dynamical state, and signatures of astrophysical feedback in the intra-cluster gas. We will describe the overall observing program, early results, and future directions.

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

    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

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

    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

  9. Direct measurement of dark matter halo ellipticity from two-dimensional lensing shear maps of 25 massive clusters

    Oguri, Masamune; Okabe, Nobuhiro; Smith, Graham P

    2010-01-01

    We present new measurements of dark matter distributions in 25 X-ray luminous clusters by making a full use of the two-dimensional (2D) weak lensing signals obtained from high-quality Subaru/Suprime-Cam imaging data. Our approach to directly compare the measured lensing shear pattern with elliptical model predictions allows us to extract new information on the mass distributions of individual clusters, such as the halo ellipticity and mass centroid. We find that these parameters on the cluster shape are little degenerate with cluster mass and concentration parameters. By combining the 2D fitting results for a subsample of 18 clusters, the elliptical shape of dark matter haloes is detected at 7\\sigma significance level. The mean ellipticity is found to be e = 0.46 \\pm 0.04 (1\\sigma), which is in excellent agreement with the standard collisionless CDM model prediction. The mass centroid can be constrained with a typical accuracy of ~20" (~50 kpc/h) in radius for each cluster with some significant outliers, enab...

  10. Strategies for measurement-based quantum computation with cluster states transformed by stochastic local operations and classical communication

    D'Souza, Adam G

    2011-01-01

    We examine cluster states transformed by stochastic local operations and classical communication, as a resource for deterministic universal computation driven strictly by projective measurements. We identify circumstances under which such states in one dimension constitute resources for random length single-qubit rotations, in one case quasi-deterministically (N-U-N states) and in another probabilistically (B-U-B states). In contrast to the cluster states, the N-U-N states exhibit spin correlation functions that decay exponentially with distance, while the B-U-B states can be arbitrarily locally pure. A two-dimensional square N-U-N lattice is a universal resource for quasideterministic measurement-based quantum computation. Measurements on cubic B-U-B states yield two-dimensional cluster states with bond defects, whose connectivity exceeds the percolation threshold for a critical value of the local purity.

  11. Measurement of the Sunyaev-Zel'dovich Increment in Massive Galaxy Clusters

    Zemcov, M; Borys, C; Chapman, S; Holland, W; Pierpaoli, E; Scott, D; Borys, Colin; Chapman, Scott; Halpern, Mark; Holland, Wayne; Pierpaoli, Elena; Scott, Douglas; Zemcov, Michael

    2003-01-01

    We have detected the Sunyaev-Zel'dovich (SZ) increment at 850 microns in two galaxy clusters (Cl 0016+16 and MS 1054.4-0321) using SCUBA (Sub-millimetre Common User Bolometer Array) on the James Clerk Maxwell Telescope. Fits to the isothermal $beta$ model imply a peak 850 micron flux of I_{0} = 2.1 pm 0.5 mJy per beam in Cl 0016, which can be combined with decrement measurements to infer v_{pec} = 300 pm 2500 km/s. In MS 1054 we find y = (2.0 pm 1.0) X 10^{-4}, implying a peak 850 micron flux of I_{0} = 2.0 pm 1.0 mJy per beam. These measurements require large chop throws and non-standard data analysis techniques. In particular, the 450 micron data are used to remove atmospheric variations in the 850 micron data. An explicit annular model is fit to the SCUBA difference data in order to extract the radial profile, and separately fit to the model differences to minimize the effect of correlations induced by our scanning strategy. We have demonstrated that with sufficient care, SCUBA can be used to measure the S...

  12. Cluster-randomized trial of a German leisure-based alcohol peer education measure.

    Bühler, Anneke; Thrul, Johannes; Strüber, Evelin; Orth, Boris

    2016-06-01

    Because of scarce research, the effectiveness of substance abuse prevention in leisure settings remains unclear. In this study, we evaluated the effectiveness of a peer-led educational prevention measure with adolescent groups in unstructured leisure settings, which is a component of the complex German nationwide 'Na Toll!' campaign. Using a cluster-randomized two-group post-test-only design, we tested whether the measure influenced component-specific goals, namely risk and protective factors of alcohol use such as risk perception, group communication and resistance self-efficacy. The sample consisted of 738 adolescents aged 12-20 years who were recruited at recreational locations and completed an online questionnaire 1 week after the peer education or recruitment event. Sixty-three percent of the sample participated in the 3-month follow-up assessment. Data analysis revealed post-test effects on risk perception, perceived norm of alcohol communication in the peer group and resistance self-efficacy. Follow-up effects were not observed, with the exception of a significant effect on risk perception. In conclusion, the peer-led education measure in leisure settings might have supported the adolescents in this study to perceive alcohol-related risks, to feel accepted to talk about alcohol problems with their friends and to be more assertive in resisting alcohol use in the short term. PMID:25732606

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

    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.

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

    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.

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

    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 (∼4 M ☉). 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.

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

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

    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.

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

    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...

  19. Younger and brighter New distances to globular clusters based on Hipparcos parallax measurements of local subdwarfs

    Reid, I N

    1997-01-01

    We have used new parallax measurements, obtained by the Hipparcos satellite, of fifteen nearby, metal-poor stars to re-define the subdwarf main-sequence. All of these stars have parallaxes determined to an accuracy of at least 12 %. Comparing these measurements against previous ground-based data for nine stars reveals a systematic offset of 5 %, in the sense that the Hipparcos parallaxes are smaller (i.e. the inferred distances are larger). The availability of the Hipparcos observations expands the local subdwarf sample to the extent that we can separate the stars by abundance into intermediate ([Fe/H] ~ -1.4) and extreme ([Fe/H] ~ -2) subsets. Main-sequence fitting techniques are then used to match stars of the appropriate abundance range to the colour-magnitude diagrams of the seven globular clusters M5, NGC 6752, M13, M15, M92, M30 and M68. We derive respective distance moduli of 14.45, 13.17, 14.48, 15.38, 14.93, 14.95 and 15.29 magnitudes, with formal uncertainties of +/- 0.1 magnitude. The metal-poor sy...

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

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

    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.

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

    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 ...

  3. Familial Clustering and DRD4 Effects on Electroencephalogram Measures in Multiplex Families with Attention Deficit/Hyperactivity Disorder

    Loo, Sandra K.; Hale, T. Sigi; Hanada, Grant; Macion, James; Shrestha, Anshu; McGough, James J.; McCracken, James T.; Nelson, Stanley; Smalley, Susan L.

    2010-01-01

    Objective: The current study tests electroencephalogram (EEG) measures as a potential endophenotype for attention deficit/hyperactivity disorder (ADHD) by examining sibling and parent-offspring similarity, familial clustering with the disorder, and association with the dopamine receptor D4 (DRD4) candidate gene. Method: The sample consists of 531…

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

    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

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

    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.

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

    Haaland, S.; Paschmann, G.; Förster, M.; Quinn, J.; Torbert, R.; Vaith, H.; Puhl-Quinn, P.; Kletzing, C.

    2008-08-01

    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.

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

    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

  8. Kondo Physics and Unconventional Superconductivity in the U Intermetallic U2PtC2 Revealed by NMR

    The set of slides begins by discussing the topic NMR of heavy fermion superconductors under the topics heavy fermion materials, superconductivity, and nuclear magnetic resonance. The history of these phenomena is sketched, with particular mention made of CeCu2Si2, UPt3, and UBe13. Unconventional superconductivity, which is non-phonon mediated superconductivity, presents a high Tc (up to ~150 K), and involves a more complicated spin/orbital wave function. The presentation then goes on to give experimental NMR results for U2PtC2 and Pu-115's.

  9. Influence of embedding Cu nano-particles into a Cu/SiO2/Pt structure on its resistive switching

    LIU, CHIH-YI; Huang, Jyun-Jie; Lai, Chun-Hung; Lin, Chao-Han

    2013-01-01

    Cu nano-particles (Cu-NPs) were embedded into the SiO2 layer of a Cu/SiO2/Pt structure to examine their influence on resistive switching characteristics. The device showed a reversible resistive switching behavior, which was due to the formation and rupture of a Cu-conducting filament with an electrochemical reaction. The Cu-NPs enhanced the local electric field within the SiO2 layer, which caused a decrease in the forming voltage. During successive switching processes, the Cu-NP was partiall...

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

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

    2005-01-01

    A conducting bridge of a single hydrogen molecule between Pt electrodes is formed in a break junction experiment. It has a conductance near the quantum unit, G(0)=2e(2)/h, carried by a single channel. Using point-contact spectroscopy three vibration modes are observed and their variation upon...... 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...

  11. Ruling the Universe: An Improved Method for Measuring H_0 with Galaxy Clusters

    Hallman, E J; Motl, P M; Norman, M L; Hallman, Eric J.; Burns, Jack O.; Motl, Patrick M.; Norman, Michael L.

    2005-01-01

    We present a new method of calculating the value of the Hubble constant from combined X-ray/SZE observations of clusters of galaxies. Values of H_0 reported from cluster observations are systematically low compared to other methods. We show using a large sample of numerically simulated clusters at a variety of redshifts that the typically used method of calculating H_0, which assumes the cluster gas to be isothermal, results in a 20-30% underestimate of the value of H_0. The new method, which assumes the cluster gas temperature has a radial dependence described by a universal temperature profile, results in a value much closer to the true value of H_0, the mean is a 3-8% overestimate. The new method also has greatly reduced scatter about the mean for all the clusters in the simulated catalog compared to the isothermal method. Additionally, we show that a variation on this technique shows promise in reliably determining the 3-D radial temperature profile of the cluster gas. Our new method requires no additiona...

  12. Ruling the Universe: An Improved Method for Measuring the Hubble Constant with Galaxy Clusters

    Hallman, E. J.; Burns, J. O.; Motl, P. M.; Norman, M. L.

    2005-12-01

    We present a new method of calculating the value of the Hubble constant (H0) from X-ray/SZE observations of clusters of galaxies. Values of H0 reported from cluster observations are systematically low compared to other methods. We show using a large sample of numerically simulated clusters placed at a variety of redshifts that the typically used method of calculating H0, which assumes the cluster gas to be isothermal, results in a 20-30% underestimate of the mean value. This new method, which assumes the cluster gas temperature has a radial dependence described by a universal temperature profile (UTP), results in a value much closer to the true value of H0, the mean is a 3-8% overestimate. The new method also has greatly reduced scatter about the mean for all the clusters in the simulated catalog compared to the isothermal method. Our new method requires no additional observational effort compared to the traditional technique. This simple change in the analysis of the cluster data results in values of H0 which are consistent with other observations.

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

    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...

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

    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.

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

    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.

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

    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).

  17. Weak-Lensing Mass Measurements of Five Galaxy Clusters in the South Pole Telescope Survey Using Magellan/Megacam

    High, F W; Leethochawalit, N; de Haan, T; Abramson, L; Aird, K A; Armstrong, R; Ashby, M L N; Bautz, M; Bayliss, M; Bazin, G; Benson, B A; Bleem, L E; Brodwin, M; Carlstrom, J E; Chang, C L; Cho, H M; Clocchiatti, A; Conroy, M; Crawford, T M; Crites, A T; Desai, S; Dobbs, M A; Dudley, J P; Foley, R J; Forman, W R; George, E M; Gladders, M D; Gonzalez, A H; Halverson, N W; Harrington, N L; Holder, G P; Holzapfel, W L; Hoover, S; Hrubes, J D; Jones, C; Joy, M; Keisler, R; 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; Mehl, J; Meyer, S S; Mocanu, L; Mohr, J J; Montroy, T E; Murray, S S; Natoli, T; Nurgaliev, D; Padin, S; Plagge, T; Pryke, C; Reichardt, C L; Rest, A; Ruel, J; Ruhl, J E; Saliwanchik, B R; Saro, A; Sayre, J T; Schaffer, K K; Shaw, L; Schrabback, T; Shirokoff, E; Song, J; Spieler, H G; Stalder, B; Staniszewski, Z; Stark, A A; Story, K; Stubbs, C W; Suhada, R; Tokarz, S; van Engelen, A; Vanderlinde, K; Vieira, J D; Vikhlinin, A; Williamson, R; Zahn, O; Zenteno, A

    2012-01-01

    We use weak gravitational lensing to measure the masses of five galaxy clusters selected from the South Pole Telescope (SPT) survey, with the primary goal of comparing these with the SPT Sunyaev-Zel'dovich (SZ) and X-ray based mass estimates. The clusters span redshifts 0.28 2x10^14 h^-1 M_sun, and three of the five clusters were discovered by the SPT survey. We observed the clusters in the gri passbands with the Megacam imager on the Magellan Clay 6.5m telescope. We measure a mean ratio of weak lensing aperture masses to inferred aperture masses from the SZ data, both within an aperture of R_500,SZ derived from the SZ mass, of 1.12 +/- 0.15. We measure a mean ratio of spherical weak lensing masses evaluated at R_500,SZ to spherical SZ masses of 1.06 +/- 0.18, and a mean ratio of spherical weak lensing masses evaluated at R_500,WL to spherical SZ masses of 1.09 +/- 0.23. We verify in mock catalogs based on N-body simulations that all three mass ratio tests are unbiased to the 2% level under simple assumption...

  18. Measurement of sub-2 nm clusters of pristine and composite metal oxides during nanomaterial synthesis in flame aerosol reactors.

    Fang, Jiaxi; Wang, Yang; Attoui, Michel; Chadha, Tandeep S; Ray, Jessica R; Wang, Wei-Ning; Jun, Young-Shin; Biswas, Pratim

    2014-08-01

    Measuring stable clusters to understand particle inception will aid the synthesis of well-controlled nanoparticles via gas-phase aerosol routes. Using a Half Mini differential mobility analyzer, the presence of monomers, dimers, trimers, and tetramers was detected for the first time in a flame aerosol reactor during the synthesis of pristine TiO2 and TiO2/SiO2 nanocomposites. Atomic force microscopy confirmed the presence and the size of sub-2 nm clusters. The detection of these clusters elucidated the initial stages of particle formation during combustion synthesis and supported previous hypotheses that collisional growth from stable monomers of metal oxides is the first step of particle growth. PMID:24968004

  19. Tourism Cluster Competitiveness and Sustainability: Proposal for a Systemic Model to Measure the Impact of Tourism on Local Development

    Sieglinde Kindl da Cunha

    2005-07-01

    Full Text Available This article proposes a model to measure tourism cluster impact on local development with a view to assessing tourism cluster interaction, competitiveness and sustainability impacts on the economy, society and the environment. The theoretical basis for this model is founded on cluster concept and typology adapting and integrating the systemic competitiveness and sustainability concepts within economic, social, cultural, environmental and political dimensions. The proposed model shows a holistic, multidisciplinary and multi-sector view of local development brought back through a systemic approach to the concepts of competitiveness, social equity and sustainability. Its results make possible strategic guidance to agents responsible for public sector tourism policies, as well as the strategies for competitiveness, competition, cooperation and sustainability in private companies and institutions.

  20. Measuring age differences among globular clusters having similar metallicities - A new method and first results

    A color-difference technique for estimating the relative ages of globular clusters with similar chemical compositions on the basis of their CM diagrams is described and demonstrated. The theoretical basis and implementation of the procedure are explained, and results for groups of globular clusters with m/H = about -2, -1.6, and -1.3, and for two special cases (Palomar 12 and NGC 5139) are presented in extensive tables and graphs and discussed in detail. It is found that the more metal-deficient globular clusters are nearly coeval (differences less than 0.5 Gyr), whereas the most metal-rich globular clusters exhibit significant age differences (about 2 Gyr). This result is shown to contradict Galactic evolution models postulating halo collapse in less than a few times 100 Myr. 77 refs

  1. Cluster cross sections from pickup measurements: Are the established methods consistent?

    Fedor, J.; Poterya, Viktoriya; Pysanenko, Andriy; Fárník, Michal

    2011-01-01

    Roč. 135, č. 10 (2011), s. 104305. ISSN 0021-9606 R&D Projects: GA ČR GA203/09/0422; GA ČR GAP208/11/0161; GA AV ČR KJB400400902 Institutional research plan: CEZ:AV0Z40400503 Keywords : liquid- helium clusters * water clusters * molecular-beam Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.333, year: 2011

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

    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, ...

  3. Analysis on the Filament Structure Evolution in Reset Transition of Cu/HfO2/Pt RRAM Device.

    Zhang, Meiyun; Long, Shibing; Li, Yang; Liu, Qi; Lv, Hangbing; Miranda, Enrique; Suñé, Jordi; Liu, Ming

    2016-12-01

    The resistive switching (RS) process of resistive random access memory (RRAM) is dynamically correlated with the evolution process of conductive path or conductive filament (CF) during its breakdown (rupture) and recovery (reformation). In this study, a statistical evaluation method is developed to analyze the filament structure evolution process in the reset operation of Cu/HfO2/Pt RRAM device. This method is based on a specific functional relationship between the Weibull slopes of reset parameters' distributions and the CF resistance (R on). The CF of the Cu/HfO2/Pt device is demonstrated to be ruptured abruptly, and the CF structure of the device has completely degraded in the reset point. Since no intermediate states are generated in the abrupt reset process, it is quite favorable for the reliable and stable one-bit operation in RRAM device. Finally, on the basis of the cell-based analytical thermal dissolution model, a Monte Carlo (MC) simulation is implemented to further verify the experimental results. This work provides inspiration for RRAM reliability and performance design to put RRAM into practical application. PMID:27389343

  4. Analysis on the Filament Structure Evolution in Reset Transition of Cu/HfO2/Pt RRAM Device

    Zhang, Meiyun; Long, Shibing; Li, Yang; Liu, Qi; Lv, Hangbing; Miranda, Enrique; Suñé, Jordi; Liu, Ming

    2016-05-01

    The resistive switching (RS) process of resistive random access memory (RRAM) is dynamically correlated with the evolution process of conductive path or conductive filament (CF) during its breakdown (rupture) and recovery (reformation). In this study, a statistical evaluation method is developed to analyze the filament structure evolution process in the reset operation of Cu/HfO2/Pt RRAM device. This method is based on a specific functional relationship between the Weibull slopes of reset parameters' distributions and the CF resistance ( R on). The CF of the Cu/HfO2/Pt device is demonstrated to be ruptured abruptly, and the CF structure of the device has completely degraded in the reset point. Since no intermediate states are generated in the abrupt reset process, it is quite favorable for the reliable and stable one-bit operation in RRAM device. Finally, on the basis of the cell-based analytical thermal dissolution model, a Monte Carlo (MC) simulation is implemented to further verify the experimental results. This work provides inspiration for RRAM reliability and performance design to put RRAM into practical application.

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

    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.

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

    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...

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

    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.

  8. Prospects for measuring the relative velocities of galaxy clusters in photometric surveys using the kinetic Sunyaev-Zel'dovich Effect

    Keisler, Ryan

    2012-01-01

    We consider the prospects for measuring the pairwise kinetic Sunyaev-Zel'dovich (kSZ) signal from galaxy clusters discovered in large photometric surveys such as the Dark Energy Survey (DES). We project that the DES cluster sample will, in conjunction with existing mm-wave data from the South Pole Telescope (SPT), yield a detection of the pairwise kSZ signal at the 8-13 sigma level, with sensitivity peaking for clusters separated by ~100 Mpc distances. A next-generation version of SPT would allow for a 18-30 sigma detection and would be limited by variance from the kSZ signal itself and residual thermal Sunyaev-Zel'dovich (tSZ) signal. Throughout our analysis we assume photometric redshift errors, which wash out the signal for clusters separated by <~50 Mpc; a spectroscopic survey of the DES sample would recover this signal and allow for a 26-43 sigma detection, and would again be limited by kSZ/tSZ variance. Assuming a standard model of structure formation, these high-precision measurements of the pairwis...

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

    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...

  10. A measurement of large-scale peculiar velocities of clusters of galaxies: technical details

    Kashlinsky, A; Kocevski, D; Ebeling, H

    2008-01-01

    This paper presents detailed analysis of large-scale peculiar motions derived from a sample of ~ 700 X-ray clusters and cosmic microwave background (CMB) data obtained with WMAP. We use the kinematic Sunyaev-Zeldovich (KSZ) effect combining it into a cumulative statistic which preserves the bulk motion component with the noise integrated down. Such statistic is the dipole of CMB temperature fluctuations evaluated over the pixels of the cluster catalog (Kashlinsky & Atrio-Barandela 2000). To remove the cosmological CMB fluctuations the maps are Wiener-filtered in each of the eight WMAP channels (Q, V, W) which have negligible foreground component. Our findings are as follows: The thermal SZ (TSZ) component of the clusters is described well by the Navarro-Frenk-White profile expected if the hot gas traces the dark matter in the cluster potential wells. Such gas has X-ray temperature decreasing rapidly towards the cluster outskirts, which we demonstrate results in the decrease of the TSZ component as the ape...

  11. Measuring the dynamical state of Planck SZ-selected clusters: X-ray peak - BCG offset

    Rossetti, M; Ferioli, G; Bersanelli, M; De Grandi, S; Eckert, D; Ghizzardi, S; Maino, D; Molendi, S

    2015-01-01

    We want to characterize the dynamical state of galaxy clusters detected with the Sunyaev-Zeldovich (SZ) effect by Planck and compare them with the dynamical state of clusters selected in X-rays survey. We analyzed a representative subsample of the Planck SZ catalogue, containing the 132 clusters with the highest signal to noise ratio and characterize their dynamical state using as indicator the projected offset between the peak of the X-ray emission and the position of the Brightest cluster galaxy. We study the distribution of our indicator in our sample and compare it to its distribution in X-ray selected samples (HIFLUGCS, MACS and REXCESS). The distributions are significantly different and the fraction of relaxed objects is smaller in the Planck sample ($52 \\pm 4 \\%$) than in X-ray samples ($\\simeq 74\\%$) We interpret this result as an indication of different selection effects affecting X-rays (e.g. "cool core bias") and SZ surveys of galaxy clusters.

  12. Measuring the dynamical state of Planck SZ-selected clusters: X-ray peak - BCG offset

    Rossetti, M.; Gastaldello, F.; Ferioli, G.; Bersanelli, M.; De Grandi, S.; Eckert, D.; Ghizzardi, S.; Maino, D.; Molendi, S.

    2016-04-01

    We want to characterize the dynamical state of galaxy clusters detected with the Sunyaev-Zeldovich (SZ) effect by Planck and compare them with the dynamical state of clusters selected in X-rays survey. We analysed a representative subsample of the Planck SZ catalogue, containing the 132 clusters with the highest signal to noise ratio and characterize their dynamical state using as an indicator the projected offset between the peak of the X-ray emission and the position of the Brightest cluster galaxy. We compare the distribution of this indicator for the Planck SZ-selected sample and three X-ray-selected samples (HIFLUGCS, MACS and REXCESS). The distributions are significantly different and the fraction of relaxed objects is smaller in the Planck sample (52 ± 4 per cent) than in X-ray samples (≃74 per cent) We interpret this result as an indication of different selection effects affecting X-rays (e.g. `cool core bias') and SZ surveys of galaxy clusters.

  13. Data Clustering

    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

  14. Cluster Bulleticity

    Massey, Richard; Kitching, Thomas D.; Nagai, Daisuke

    2010-01-01

    The unique properties of dark matter are revealed during collisions between clusters of galaxies, like the bullet cluster (1E 0657-56) and baby bullet (MACSJ0025-12). These systems provide evidence for an additional, invisible mass in the separation between the distribution of their total mass, measured via gravitational lensing, and their ordinary 'baryonic' matter, measured via its X-ray emission. Unfortunately, the information available from these systems is limited by th...

  15. Cluster Bulleticity

    Massey, R; Kitching, T.; Nagai, D.

    2010-01-01

    The unique properties of dark matter are revealed during collisions between clusters of galaxies, such as the bullet cluster (1E 0657−56) and baby bullet (MACS J0025−12). These systems provide evidence for an additional, invisible mass in the separation between the distributions of their total mass, measured via gravitational lensing, and their ordinary ‘baryonic’ matter, measured via its X-ray emission. Unfortunately, the information available from these systems is limited by their rarity. C...

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

    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.

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

    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

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

    Muramatsu, Chisako; Li Qiang; Schmidt, Robert; Shiraishi, Junji; Doi, Kunio [Department of Radiology, University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois 60637 (United States) and Department of Intelligent Image Information, Gifu University, 1-1 Yanagido, Gifu (Japan); Department of Radiology, Duke Advanced Imaging Labs, Duke University, 2424 Erwin Road, Suite 302, Durham, North Carolina 27705 (United States); Department of Radiology, University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois 60637 (United States)

    2008-12-15

    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

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

    Ichiki, Kiyotomo; Yoo, Chul-Moon; 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...

  20. Response function for the measurement of (n, γ) reactions with the ANNRI-cluster Ge detectors at J-PARC

    For a new experimental setup, response functions of cluster-Ge detectors were measured with standard γ-ray sources, γ-rays of the 24Na β-decay, and prompt γ-rays of the 35Cl(n, γ)36Cl reaction in ANNRI at J-PARC/MLF. The experimental data and calculation with the EGS5 code are compared. (author)

  1. Supported heteronuclear noble metal cluster catalysts and method for preparing same

    New heteronuclear noble metal cluster complexes have been discovered and synthesized for the first time. These complexes are (pyridine)2Pt(Ir2(CO)15), (pyridine)2 Pt(Ir2(CO)7), (Pyridine)3Pt(Ru3(CO)12), ((C6H5)3P)2Pt(Ir(CO)3(P6H5)3)2, ((C6H5)3P)2Rh(CO)(IR(CO)4), and (pyridine)2Pt(Rh(CO)2(P(C6H5)3)3)2. These new heteronuclear noble metal cluster complexes are useful as supported mixed noble metal catalyst precursors. These new cluster complexes, of known stoichiometry, are deposited on anhydrous refractory inorganic oxide or carbon supports and then reduced resulting in the formation of a supported heteronuclear noble metal catalyst having the same metals stoichiometry as the starting cluster complexes. In this way, precise control can be exercised over the ratio and distribution of multiple metal components in a mixed noble metal catalyst. The usage of preformed heteronuclear noble metal cluster complexes as supported mixed metal catalyst precursors maximizes surface alloy formation and also yields unique mixed-metal cluster structures on the support surface

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

    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

  3. Measurements of Burnout Conditions for Flow of Boiling Water in Vertical 3-Rod and 7-Rod Clusters

    The present report deals with measurements of burnout conditions for flow of boiling water in vertical 3-rod and 7-rod clusters. Data were obtained,in respect of heating the rods only, as well as for simultaneous uniform and non-uniform heating of the rods and the shroud. Totally, 520 runs were performed. In the case of equal heat fluxes on all surfaces of the channels, burnout always occurred on the rods, and the data were low by a factor of about 1.3 compared with round duct data. When only the rods were heated, the data showed very low burnout values in comparison with the results for total uniform heating and round ducts. This disagreement was explained by considering the climbing film flow model and the fact that only a fraction of the channel perimeter was heated. For simultaneous and non-uniform heating of the rods and the shroud it was found that the shroud could be overloaded up to 50 per cent without reducing the margin of safety in respect of burnout for the rod cluster. Finally, a correlation for predicting burnout conditions in round ducts, annuli and rod clusters has been presented. This correlation predicts the burnout heat fluxes for the present measurements and previously obtained annuli measurements within ± 5 per cent

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

    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.

  5. Relationship between the CMB, Sunyaev-Zel'dovich cluster counts, and local Hubble parameter measurements in a simple void model

    Ichiki, Kiyotomo; Yoo, Chul-Moon; Oguri, Masamune

    2016-01-01

    The discrepancy between the amplitudes of matter fluctuations inferred from Sunyaev-Zel'dovich (SZ) cluster number counts and the measurement of temperature and polarization anisotropies of the cosmic microwave background (CMB) measured by the Planck satellite can be reconciled if the local universe is embedded in an underdense 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 underdense region needs to be to resolve this discrepancy. Such local void, if it 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 Hloc=70.1 ±0.34 km s-1 Mpc-1 is in better agreement with direct local Hubble parameter measurements, indicating that the local void model may provide provide a consistent solution to the cluster number counts and Hubble parameter discrepancies.

  6. Statistics of whistler mode waves in the outer radiation belt: Cluster STAFF-SA measurements

    ELF/VLF waves play a crucial role in the dynamics of the radiation belts and are partly responsible for the main losses and the acceleration of energetic electrons. Modeling wave-particle interactions requires detailed information of wave amplitudes and wave normal distribution over L-shells and over magnetic latitudes for different geomagnetic activity conditions. We performed a statistical study of ELF/VLF emissions using wave measurements in the whistler frequency range for 10 years (2001-2010) aboard Cluster spacecraft. We utilized data from the STAFF-SA experiment, which spans the frequency range from 8 Hz to 4 kHz. We present distributions of wave magnetic and electric field amplitudes and wave normal directions as functions of magnetic latitude, magnetic local time, L-shell, and geomagnetic activity. We show that wave normals are directed approximately along the background magnetic field (with the mean value of θ the angle between the wave normal and the background magnetic field, about 10-15 degrees) in the vicinity of the geomagnetic equator. The distribution changes with magnetic latitude: Plasma spheric hiss normal angles increase with latitude to quasi-perpendicular direction at 35-40 degrees where hiss can be reflected; lower band chorus are observed as two wave populations: One population of wave normals tends toward the resonance cone and at latitudes of around 35-45 degrees wave normals become nearly perpendicular to the magnetic field; the other part remains quasi-parallel at latitudes up to 30 degrees. The observed angular distribution is significantly different from Gaussian, and the width of the distribution increases with latitude. Due to the rapid increase of θ the wave mode becomes quasi-electrostatic, and the corresponding electric field increases with latitude and has a maximum near 30 degrees. The magnetic field amplitude of the chorus in the day sector has a minimum at the magnetic equator but increases rapidly with latitude with a

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

    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.

  8. Cortical and subcortical hyperfusion during migraine and cluster headache measured by Xe CT-CBF

    High-resolution, color-coded images of local cerebral blood flow (LCBF) were made utilizing stable xenon-enhanced computed tomography among patients with common migraine (n=18), classic migraine (n=12) and cluster headache (n=5). During spontaneously occurring headache in common and classic migraine patients, LCBF values for cerebral cortex and subcortical gray and white matter were diffusely increased by 20-40% with the exception of the occipital lobes. LCBF increases involved both hemispheres whether the head pain was unilateral or bilateral. No significant differences were noted in the degree or pattern of LCBF increases during headaches of common and classic migraineurs. Similar cerebral hyperperfusion of greater magnitude was observed during cluster headaches but was more prominent on the side of the head pain. Present observations do not support the hypothesis of spreading cortical depression as a cause of classic migraine. From a hemodynamic viewpoint, LCBF increases during headaches of common or classic migraine or cluster appear similar. Evidence is adduced that sympathetic hypofunction with denervation hypersensitivity of cerebral vessels plays a role in the cerebral hyperperfusion of migraine headaches. More pronounced unilateral autonomic derangements appear to account for the symptoms and cerebral hyperperfusion associated with cluster headaches. (orig.)

  9. Measurements of the gas temperature and iron abundance distribution in the Coma Cluster

    The medium energy X-ray detectors onboard the EXOSAT Observatory have been used to determine the gas temperature at several positions in the Coma Cluster of galaxies. Evidence is found at greater than 95 percent confidence for a higher temperature in the center of the cluster than in a position approximately 45 arcmin off-center. No difference in iron abundance is observed between the center and off-center regions and the equilibrium model for the distribution of elements in the Coma Cluster of Abramopoulos, Chanan, and Ku can be rejected with greater than 99.5 percent confidence, in favor of a model with more uniform composition. A phenomenological model is presented of the Coma Cluster, which is consistent with the data presented here, as well as the imaging data from the Einstein Observatory and the Tenma X-ray spectrum. The model has a central isothermal region of temperature about 9 keV extending to about 25 arcmin (about 1 Mpc). Beyond this radius the temperature falls as a polytrope with index about 1.6. 36 references

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

    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…

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

    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

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

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

    2013-01-01

    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 and White (GNFW) model for the cluster gas press...

  13. Measuring group synchrony: a cluster-phase method for analyzing multivariate movement time-series

    MichaelRichardson; RandiLGarcia; MadisonGregor

    2012-01-01

    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...

  14. Clustering analysis

    Cluster analysis is the name of group of multivariate techniques whose principal purpose is to distinguish similar entities from the characteristics they process.To study this analysis, there are several algorithms that can be used. Therefore, this topic focuses to discuss the algorithms, such as, similarity measures, and hierarchical clustering which includes single linkage, complete linkage and average linkage method. also, non-hierarchical clustering method, which is popular name K-mean method' will be discussed. Finally, this paper will be described the advantages and disadvantages of every methods

  15. Defect chemistry of ''BaCuO2''. Pt. 2. Transport properties and nature of defects

    The charge transport properties of ''BaCuO2'' with 88:90 (Ba:Cu) cation ratio were characterized by thermopower, electrical conductivity and ionic transport number measurements in a wide range of temperature and oxygen partial pressure conditions. The nature of carriers is always represented by small polarons due to self-trapping of the electronic holes generated by the oxygen non-stoichiometry equilibrium. Some anomalies in carrier mobility as a function of temperature are shown not to be related to incomplete ionization of oxygen atoms on interstitial sites (orig.)

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

    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...

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

    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_\

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

    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 ...

  19. Cluster Bulleticity

    Massey, Richard; Nagai, Daisuke

    2010-01-01

    The unique properties of dark matter are revealed during collisions between clusters of galaxies, like the bullet cluster (1E 0657-56) and baby bullet (MACSJ0025-12). These systems provide evidence for an additional, invisible mass in the separation between the distribution of their total mass, measured via gravitational lensing, and their ordinary 'baryonic' matter, measured via its X-ray emission. Unfortunately, the information available from these systems is limited by their rarity. Constraints on the properties of dark matter, such as its interaction cross-section, are therefore restricted by uncertainties in the individual systems' impact velocity, impact parameter and orientation with respect to the line of sight. Here we develop a complementary, statistical measurement in which every piece of substructure falling into every massive cluster is treated as a bullet. We define 'bulleticity' as the mean separation between dark matter and ordinary matter, and we measure a positive signal in hydrodynamical si...

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

    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.

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

    Kurtén, T.; T. Petäjä; Smith,J; Ortega, I.K.; Sipilä, M.; Junninen, H.; M. Ehn; Vehkamäki, H.; Mauldin, L.; Worsnop, D.R.; M. Kulmala

    2011-01-01

    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 i...

  2. Increasing objectively measured sedentary time increases clustered cardiometabolic risk: a 6 year analysis of the ProActive study

    Wijndaele, Katrien; Orrow, Gillian; Ekelund, Ulf; Sharp, Stephen J.; Brage, Søren; Simon J Griffin; Simmons, Rebecca K

    2013-01-01

    Aims/hypothesis We aimed to quantify the associations between change in objectively measured sedentary and moderate-to-vigorous physical activity (MVPA) times and self-reported television viewing over 6 years and change in a clustered cardiometabolic risk score (CCMR), including and excluding waist circumference (CCMR without adiposity component, CCMR no adip ), and its individual components, among the adult children of people with type 2 diabetes. Methods In 171 adults (mean ± SD age 42.52 ±...

  3. Testing X-ray Measurements of Galaxy Cluster Gas Mass Fraction Using the Cosmic Distance-Duality Relation

    Wang, Xin; Meng, Xiao-Lei; Huang, Y. F.; Zhang, Tong-Jie

    2013-01-01

    We propose a consistency test of some recent X-ray gas mass fraction ($f_{\\rm{gas}}$) measurements in galaxy clusters, using the cosmic distance-duality relation, $\\eta_{\\rm{theory}}=\\dl(1+z)^{-2}/\\da$, with luminosity distance ($\\dl$) data from the Union2 compilation of type Ia supernovae. We set $\\eta_{\\rm{theory}}\\equiv1$, instead of assigning any redshift parameterizations to it, and constrain the cosmological information preferred by $f_{\\rm{gas}}$ data along with supernova observations....

  4. Heat transfer and fluid flow measurements near the exit of a 36 pin simulated CAGR fuel cluster

    This work was carried out as part of the instrumented fuel stringer programme in Civil Advanced Gas-cooled Reactors. The overall aim of the project was to assess the coolant temperature distribution in the CAGR fuel cluster on the basis of thermocouple measurements in the coolant downstream of the fuel exit. This was achieved by use of an air rig simulating an AGR channel and the subsequent development of a model was based on a diffusivity analysis. This paper describes points of general interest arising from this work. (author)

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

    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.

  6. Weak Lensing Mass Measurements of Substructures in COMA Cluster with Subaru/Suprime-Cam

    Okabe, Nobuhiro; Futamase, Toshifumi

    2010-01-01

    We obtain the projected mass distributions for two Subaru/Suprime-Cam fields in the southwest region (r\\simlt 60') of the Coma cluster (z=0.0236) by weak lensing analysis and detect eight subclump candidates. We quantify the contribution of background large-scale structure (LSS) on the projected mass distributions using SDSS multi-bands and photometric data, under the assumption of mass-to-light ratio for field galaxies. We find that one of eight subclump candidates, which is not associated with any member galaxies, is significantly affected by LSS lensing. The mean projected mass for seven subclumps extracted from the main cluster potential is = (5.06\\pm1.30)10^12h^-1 M_sun after a LSS correction. A tangential distortion profile over an ensemble of subclumps is well described by a truncated singular-isothermal sphere model and a truncated NFW model. A typical truncated radius of subclumps, r_t\\simeq 35 h^-1 kpc, is derived without assuming any relations between mass and light for member galaxies. The radius...

  7. Observing Oxygen Vacancy Driven Electroforming in Pt-TiO2-Pt Device via Strong Metal Support Interaction.

    Jang, Moon Hyung; Agarwal, Rahul; Nukala, Pavan; Choi, Dooho; Johnson, A T Charlie; Chen, I-Wei; Agarwal, Ritesh

    2016-04-13

    Oxygen vacancy formation, migration, and subsequent agglomeration into conductive filaments in transition metal oxides under applied electric field is widely believed to be responsible for electroforming in resistive memory devices, although direct evidence of such a pathway is lacking. Here, by utilizing strong metal-support interaction (SMSI) between Pt and TiO2, we observe via transmission electron microscopy the electroforming event in lateral Pt/TiO2/Pt devices where the atomic Pt from the electrode itself acts as a tracer for the propagating oxygen vacancy front. SMSI, which originates from the d-orbital overlap between Pt atom and the reduced cation of the insulating oxide in the vicinity of oxygen vacancies, was optimized by fabricating nanoscale devices causing Pt atom migration tracking the moving oxygen vacancy front from the anode to cathode during electroforming. Experiments performed in different oxidizing and reducing conditions, which tune SMSI in the Pt-TiO2 system, further confirmed the role of oxygen vacancies during electroforming. These observations also demonstrate that the noble metal electrode may not be as inert as previously assumed. PMID:26982325

  8. Investigation on the RESET switching mechanism of bipolar Cu/HfO2/Pt RRAM devices with a statistical methodology

    The RESET switching of bipolar Cu/HfO2/Pt resistance random access memory (RRAM) is investigated. With a statistical methodology, we systematically analyze the RESET voltage (VRESET) and RESET current (IRESET). VRESET shows a U-shape distribution as a function of RON according to the scatter plot of the raw experimental data. After data correction by a series resistance (RS), VRESET is nearly constant, while IRESET decreases linearly with RCF. These behaviours are consistent with the thermal dissolution model of RESET. Moreover, the IRESET and VRESET distributions are strongly affected by the RON distribution. Using a ‘resistance screening’ method, the IRESET and VRESET distributions are found to be compatible with the Weibull distribution model. The Weibull slopes of the VRESET and IRESET distributions are independent of RCF, indicating that the RESET point corresponds to the initial phase of conductive filament (CF) dissolution, according to our cell-based model for the unipolar RESET of RRAM devices. The scale factor of the VRESET distributions is roughly constant, while that of the IRESET distributions scale with 1/RCF. Accordingly, the RESET switching of the HfO2-based solid electrolyte memory is compatible with the thermal dissolution mechanism, improving our understanding on the physics of resistive switching of RRAM devices. (paper)

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

    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.

  10. Clustering of local group distances: publication bias or correlated measurements? I. The large Magellanic cloud

    De Grijs, Richard [Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871 (China); Wicker, James E. [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Bono, Giuseppe [Dipartimento di Fisica, Università di Roma Tor Vergata, via Della Ricerca Scientifica 1, I-00133 Roma (Italy)

    2014-05-01

    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){sub 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 to the tightly clustered distances is based on highly non-independent tracer samples and analysis methods, hence leading to significant correlations among the LMC distances reported in subsequent articles. Based on a careful, weighted combination, in a statistical sense, of the main stellar population tracers, we recommend that a slightly adjusted canonical distance modulus of (m – M){sub 0} = 18.49 ± 0.09 mag be used for all practical purposes that require a general distance scale without the need for accuracies of better than a few percent.

  11. Magnetospheric convection from Cluster EDI measurements compared with the ground-based ionospheric convection model IZMEM

    Förster, M.; Feldstein, Y. I.; Haaland, S. E.; Dremukhina, L. A.; Gromova, L. I.; Levitin, A. E.

    2009-08-01

    Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for more than seven and a half years (2001-2008) have been used to derive a statistical model of the high-latitude electric potential distribution for summer conditions. Based on potential pattern for different orientations of the interplanetary magnetic field (IMF) in the GSM y-z-plane, basic convection pattern (BCP) were derived, that represent the main characteristics of the electric potential distribution in dependence on the IMF. The BCPs comprise the IMF-independent potential distribution as well as patterns, which describe the dependence on positive and negative IMFBz and IMFBy variations. The full set of BCPs allows to describe the spatial and temporal variation of the high-latitude electric potential (ionospheric convection) for any solar wind IMF condition near the Earth's magnetopause within reasonable ranges. The comparison of the Cluster/EDI model with the IZMEM ionospheric convection model, which was derived from ground-based magnetometer observations, shows a good agreement of the basic patterns and its variation with the IMF. According to the statistical models, there is a two-cell antisunward convection within the polar cap for northward IMFBz+≤2 nT, while for increasing northward IMFBz+ there appears a region of sunward convection within the high-latitude daytime sector, which assumes the form of two additional cells with sunward convection between them for IMFBz+≍4-5 nT. This results in a four-cell convection pattern of the high-latitude convection. In dependence of the ±IMFBy contribution during sufficiently strong northward IMFBz conditions, a transformation to three-cell convection patterns takes place.

  12. Spitzer Clusters

    Krick, Kessica

    This proposal is a specific response to the strategic goal of NASA's research program to "discover how the universe works and explore how the universe evolved into its present form." Towards this goal, we propose to mine the Spitzer archive for all observations of galaxy groups and clusters for the purpose of studying galaxy evolution in clusters, contamination rates for Sunyaev Zeldovich cluster surveys, and to provide a database of Spitzer observed clusters to the broader community. Funding from this proposal will go towards two years of support for a Postdoc to do this work. After searching the Spitzer Heritage Archive, we have found 194 unique galaxy groups and clusters that have data from both the Infrared array camera (IRAC; Fazio et al. 2004) at 3.6 - 8 microns and the multiband imaging photometer for Spitzer (MIPS; Rieke et al. 2004) at 24microns. This large sample will add value beyond the individual datasets because it will be a larger sample of IR clusters than ever before and will have sufficient diversity in mass, redshift, and dynamical state to allow us to differentiate amongst the effects of these cluster properties. An infrared sample is important because it is unaffected by dust extinction while at the same time is an excellent measure of both stellar mass (IRAC wavelengths) and star formation rate (MIPS wavelengths). Additionally, IRAC can be used to differentiate star forming galaxies (SFG) from active galactic nuclei (AGN), due to their different spectral shapes in this wavelength regime. Specifically, we intend to identify SFG and AGN in galaxy groups and clusters. Groups and clusters differ from the field because the galaxy densities are higher, there is a large potential well due mainly to the mass of the dark matter, and there is hot X-ray gas (the intracluster medium; ICM). We will examine the impact of these differences in environment on galaxy formation by comparing cluster properties of AGN and SFG to those in the field. Also, we will

  13. Subaru weak-lensing measurement of a z = 0.81 cluster discovered by the Atacama Cosmology Telescope Survey

    Miyatake, Hironao; Takada, Masahiro; Mandelbaum, Rachel; Mineo, Sogo; Aihara, Hiroaki; Spergel, David N; Bickerton, Steven J; Bond, J Richard; Hajian, Amir; Hilton, Matt; Hincks, Adam D; Hughes, John P; Infante, Leopoldo; Lin, Yen-Ting; Lupton, Robert H; Marriage, Tobias A; Marsden, Danica; Menanteau, Felipe; Miyazaki, Satoshi; Moodley, Kavilan; Niemack, Michael D; Oguri, Masamune; Price, Paul A; Reese, Erik D; Sifon, Cristobal; Wollack, Edward J; Yasuda, Naoki

    2013-01-01

    We present a Subaru weak lensing measurement of ACT-CL J0022.2-0036, one of the most luminous, high-redshift (z=0.81) Sunyaev-Zel'dovich (SZ) clusters discovered in the 268 deg^2 equatorial region survey of the Atacama Cosmology Telescope. For the weak lensing analysis using i'-band images, we use a model-fitting (Gauss-Laguerre shapelet) method to measure shapes of galaxy images, where we fit galaxy images in different exposures simultaneously to obtain best-fit ellipticities taking into account the different PSFs in each exposure. We also take into account the astrometric distortion effect on galaxy images by performing the model fitting in the world coordinate system. To select background galaxies behind the cluster at z=0.81, we use photometric redshift (photo-z) estimates for every galaxy derived from the co-added images of multi-passband Br'i'z'Y, with PSF matching/homogenization. After a photo-z cut for background galaxy selection, we detect the tangential weak lensing distortion signal with a total si...

  14. Magnetospheric convection from Cluster EDI measurements compared with the ground-based ionospheric convection model IZMEM

    M. Förster

    2009-08-01

    Full Text Available Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for more than seven and a half years (2001–2008 have been used to derive a statistical model of the high-latitude electric potential distribution for summer conditions. Based on potential pattern for different orientations of the interplanetary magnetic field (IMF in the GSM y-z-plane, basic convection pattern (BCP were derived, that represent the main characteristics of the electric potential distribution in dependence on the IMF. The BCPs comprise the IMF-independent potential distribution as well as patterns, which describe the dependence on positive and negative IMFBz and IMFBy variations. The full set of BCPs allows to describe the spatial and temporal variation of the high-latitude electric potential (ionospheric convection for any solar wind IMF condition near the Earth's magnetopause within reasonable ranges. The comparison of the Cluster/EDI model with the IZMEM ionospheric convection model, which was derived from ground-based magnetometer observations, shows a good agreement of the basic patterns and its variation with the IMF. According to the statistical models, there is a two-cell antisunward convection within the polar cap for northward IMFBz+≤2 nT, while for increasing northward IMFBz+ there appears a region of sunward convection within the high-latitude daytime sector, which assumes the form of two additional cells with sunward convection between them for IMFBz+≈4–5 nT. This results in a four-cell convection pattern of the high-latitude convection. In dependence of the ±IMFBy contribution during sufficiently strong northward IMFBz conditions, a transformation to three-cell convection patterns takes place.

  15. Combining Clustering techniques and Formal Concept Analysis to characterize Interestingness Measures

    Grissa, Dhouha; Guillaume, Sylvie; Nguifo, Engelbert Mephu

    2010-01-01

    Formal Concept Analysis "FCA" is a data analysis method which enables to discover hidden knowledge existing in data. A kind of hidden knowledge extracted from data is association rules. Different quality measures were reported in the literature to extract only relevant association rules. Given a dataset, the choice of a good quality measure remains a challenging task for a user. Given a quality measures evaluation matrix according to semantic properties, this paper describes how FCA can highl...

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

    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

  17. Complexes of platinum(II) containing neutral and deprotonated 9-methyladenine. Synthesis, x-ray structures, and NMR studies on the cyclic trimer cis-[L2Pt[9-MeAd([bond]H)

    Longato, Bruno; Pasquato, Lucia; Mucci, Adele; Schenetti, Luisa; Zangrando, Ennio

    2003-12-01

    The dinuclear hydroxo complex cis-[L(2)Pt(mu-OH)](2)(NO(3))(2) (L = PMePh(2), 1), in CH(2)Cl(2), CH(3)CN, or DMF solution, deprotonates the NH(2) group of 9-methyladenine (9-MeAd) to give the complex cis-[L(2)Pt[9-MeAd(-H)

  18. KINETIC PLASMA TURBULENCE IN THE FAST SOLAR WIND MEASURED BY CLUSTER

    The k-filtering technique and wave polarization analysis are applied to Cluster magnetic field data to study plasma turbulence at the scale of the ion gyroradius in the fast solar wind. Waves are found propagating in directions nearly perpendicular to the background magnetic field at such scales. The frequencies of these waves in the solar wind frame are much smaller than the proton gyrofrequency. After the wavevector k is determined at each spacecraft frequency fsc, wave polarization property is analyzed in the plane perpendicular to k. Magnetic fluctuations have δB > δB∥ (here the ∥ and refer to the background magnetic field B0). The wave magnetic field has right-handed polarization at propagation angles θkB 90°. The magnetic field in the plane perpendicular to B0, however, has no clear sense of a dominant polarization but local rotations. We discuss the merits and limitations of linear kinetic Alfvén waves (KAWs) and coherent Alfvén vortices in the interpretation of the data. We suggest that the fast solar wind turbulence may be populated with KAWs, small-scale current sheets, and Alfvén vortices at ion kinetic scales.

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

    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 ...

  20. Dissipation of Turbulence in the Solar Wind as Measured by Cluster

    Goldstein, Melvyn

    2012-01-01

    Turbulence in fluids and plasmas is a scale-dependent process that generates fluctuations towards ever-smaller scales until dissipation occurs. Recent Cluster observations in the solar wind demonstrate the existence of a cascade of magnetic energy from the scale of the proton Larmor radius, where kinetic properties of ions invalidate fluid approximations, down to the electron Larmor radius, where electrons become demagnetized. The cascade is quasi-two-dimensional and has been interpreted as consisting of highly oblique kinetic Alfvenic fluctuations that dissipate near at the electron gyroradius scale via proton and electron Landau damping. Here we investigate for the first time the spatial properties of the turbulence at these scales. We report the presence of thin current sheets and discontinuities with spatial sizes greater than or approximately equal to the proton Larmor radius. These isolated structures may be manifestations of intermittency, and such would localize sites of turbulent dissipation. Studying the relationship between turbulent dissipation, reconnection and intermittency is crucial for understanding the dynamics of laboratory and astrophysical plasmas.

  1. KINETIC PLASMA TURBULENCE IN THE FAST SOLAR WIND MEASURED BY CLUSTER

    Roberts, O. W.; Li, X. [Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth, Ceredigion SY23 3BZ (United Kingdom); Li, B., E-mail: xxl@aber.ac.uk [School of Space Science and Physics, Shandong University, Weihai 246209 (China)

    2013-05-20

    The k-filtering technique and wave polarization analysis are applied to Cluster magnetic field data to study plasma turbulence at the scale of the ion gyroradius in the fast solar wind. Waves are found propagating in directions nearly perpendicular to the background magnetic field at such scales. The frequencies of these waves in the solar wind frame are much smaller than the proton gyrofrequency. After the wavevector k is determined at each spacecraft frequency f{sub sc}, wave polarization property is analyzed in the plane perpendicular to k. Magnetic fluctuations have {delta}B > {delta}B{sub Parallel-To} (here the Parallel-To and refer to the background magnetic field B{sub 0}). The wave magnetic field has right-handed polarization at propagation angles {theta}{sub kB} < 90 Degree-Sign and >90 Degree-Sign . The magnetic field in the plane perpendicular to B{sub 0}, however, has no clear sense of a dominant polarization but local rotations. We discuss the merits and limitations of linear kinetic Alfven waves (KAWs) and coherent Alfven vortices in the interpretation of the data. We suggest that the fast solar wind turbulence may be populated with KAWs, small-scale current sheets, and Alfven vortices at ion kinetic scales.

  2. Kinetic plasma turbulence in the fast solar wind measured by Cluster

    Roberts, Owen W; Li, Bo

    2013-01-01

    The k-filtering technique and wave polarization analysis are applied to Cluster magnetic field data to study plasma turbulence at the scale of the ion gyroradius in the fast solar wind. Waves are found propagating in directions nearly perpendicular to the background magnetic field at such scales. The frequencies of these waves in the solar wind frame are much smaller than the proton gyro-frequency. After the wave vector ${\\bf k}$ is determined at each spacecraft frequency $f_{sc}$, wave polarization property is analyzed in the plane perpendicular to ${\\bf k}$. Magnetic fluctuations have $\\delta B_\\perp>\\delta B_\\parallel$ (here the $\\parallel$ and $\\perp$ refer to the background magnetic field ${\\bf B}_0$). The wave magnetic field has right-handed polarization at propagation angles $\\theta_{\\bf kB}90^\\circ$. The magnetic field in the plane perpendicular to ${\\bf B}_0$ however has no clear sense of a dominant polarization but local rotations. We discuss the merits and limitations of linear kinetic Aflv\\'en wav...

  3. The mathematical principles and design of the NAIS - a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

    Mirme, S.; Mirme, A.

    2013-04-01

    The paper describes the Neutral cluster and Air Ion Spectrometer (NAIS) - a multichannel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions) of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V-1 s-1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

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

    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...

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

    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.

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

    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.

  7. Clustering of children's activity behaviour: the use of self-report versus direct measures

    Tremblay Mark S

    2011-05-01

    Full Text Available Abstract While we concur with the objectives of the recent International Journal of Behavioural Nutrition and Physical Activity paper published by Jago and colleagues titled "Physical activity and sedentary behaviour typologies of 10-11 year olds", we feel that the results as currently presented do not support their conclusions. Though the authors created groups of children with dramatically different patterns of self-reported physical activity and sedentary behaviour, an inspection of the objectively measured accelerometry data shows little difference between the groups. Further, in at least one instance the difference between groups was of the opposite direction when using objective measures, as opposed to the self-report measures used in the published analysis. Thus, we caution the authors from making conclusions based on their self-report data, and propose that they re-analyze their data using their objectively measured data instead.

  8. Reading Profiles for Adults with Low-Literacy: Cluster Analysis with Power and Speeded Measures

    Mellard, Daryl F.; Fall, Emily; Mark, Caroline

    2009-01-01

    The United States' National Institute for Literacy's (NIFL) review of adult literacy instruction research recommended adult education (AE) programs assess underlying reading abilities in order to plan appropriate instruction for low-literacy learners. This study developed adult reading ability groups using measures from power tests and speeded…

  9. Wave Analysis of the Charge Density Wave Dynamics in the Molecular Conductor (Perylene)2Pt(mnt)2 (mnt=maleonitriledithiolate)

    Dumas, J; Thirion, N.; Almeida, M.; Lopes, E.; Matos, M.; Henriques, R.

    1995-01-01

    A new method based on the wavelet analysis of the voltage oscillations generated above threshold electric field for depinning of the charge density wave (CDW) in the molecular conductor (Perylene)2Pt(mnt)2 (mnt=maleonitriledithiolate) has been developed. This analysis method permits a better time resolution of the frequencies and phases involved in the CDW motion than that allowed by conventional Fourier analysis. The results are discussed in relation with current models for CDW deformations.

  10. Mixed valence and metamagnetism in a metal flux grown compound Eu{sub 2}Pt{sub 3}Si{sub 5}

    Sarkar, Sumanta; Subbarao, Udumula [New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064 (India); Joseph, Boby [Elettra–Sincrotrone Trieste SCpA, SS14 Km 163.5, 34149 Basovizza, Trieste (Italy); Peter, Sebastian C., E-mail: sebastiancp@jncasr.ac.in [New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064 (India)

    2015-05-15

    A new compound Eu{sub 2}Pt{sub 3}Si{sub 5} with plate shaped morphology has been grown from excess In flux. The compound crystallizes in the orthorhombic U{sub 2}Co{sub 3}Si{sub 5} structure type, Ibam space group and the lattice parameters are a=10.007(2) Å, b=11.666(2) Å and c=6.0011(12) Å. The crystal structure of this compound can be conceived as inter-twinned chains of [Pt{sub 2}Si{sub 2}] and [PtSi{sub 3}] tetrahedra connected along [100] direction to give rise to a complex three dimensional [Pt{sub 3}Si{sub 5}] network. Temperature dependent magnetic susceptibility data suggests that Eu{sub 2}Pt{sub 3}Si{sub 5} undergoes a strong antiferromagnetic ordering (T{sub N}=19 K) followed by a weak ferromagnetic transition (T{sub C}=5.5 K). The effective magnetic moment/Eu obtained from susceptibility data is 6.78 μ{sub B} accounts mixed valent Eu with almost 85% divalent Eu, which is supported by X-ray absorption near edge spectroscopy. The compound undergoes a metamagnetic transition under applied magnetic field through a probable spin flop mechanism. - Graphical abstract: Eu{sub 2}Pt{sub 3}Si{sub 5}, a new member in the U{sub 2}Co{sub 3}Si{sub 5} (Ibam) family undergoes metamagnetic transition at high magnetic field and Eu is in mixed valence state. - Highlights: • A new compound Eu{sub 2}Pt{sub 3}Si{sub 5} has been synthesized using indium as an inactive metal flux. • The compound undergoes metamagnetic transition at higher field. • Eu in this compound resides in a mixed valence state.

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

    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.

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

    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.

  13. A computational linguistic measure of clustering behavior on semantic verbal fluency task predicts risk of future dementia in the nun study.

    Pakhomov, Serguei V S; Hemmy, Laura S

    2014-06-01

    Generative semantic verbal fluency (SVF) tests show early and disproportionate decline relative to other abilities in individuals developing Alzheimer's disease. Optimal performance on SVF tests depends on the efficiency of using clustered organization of semantically related items and the ability to switch between clusters. Traditional approaches to clustering and switching have relied on manual determination of clusters. We evaluated a novel automated computational linguistic approach for quantifying clustering behavior. Our approach is based on Latent Semantic Analysis (LSA) for computing strength of semantic relatedness between pairs of words produced in response to SVF test. The mean size of semantic clusters (MCS) and semantic chains (MChS) are calculated based on pairwise relatedness values between words. We evaluated the predictive validity of these measures on a set of 239 participants in the Nun Study, a longitudinal study of aging. All were cognitively intact at baseline assessment, measured with the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) battery, and were followed in 18-month waves for up to 20 years. The onset of either dementia or memory impairment were used as outcomes in Cox proportional hazards models adjusted for age and education and censored at follow-up waves 5 (6.3 years) and 13 (16.96 years). Higher MCS was associated with 38% reduction in dementia risk at wave 5 and 26% reduction at wave 13, but not with the onset of memory impairment. Higher [+1 standard deviation (SD)] MChS was associated with 39% dementia risk reduction at wave 5 but not wave 13, and association with memory impairment was not significant. Higher traditional SVF scores were associated with 22-29% memory impairment and 35-40% dementia risk reduction. SVF scores were not correlated with either MCS or MChS. Our study suggests that an automated approach to measuring clustering behavior can be used to estimate dementia risk in cognitively normal

  14. The Rarity of Star Formation in Brightest Cluster Galaxies as Measured by WISE

    Fraser-McKelvie, Amelia; Pimbblet, Kevin A

    2014-01-01

    We present the mid-infrared (IR) star formation rates of 245 X-ray selected, nearby (z 1x10^44 erg/s. The Wide-Field Infrared Survey Explorer (WISE) AllWISE Data Release provides the first measurement of the 12 micron star formation indicator for all BCGs in the nearby Universe. Perseus A and Cygnus A are the only galaxies in our sample to have star formation rates of > 40 M_sol/yr, indicating that these two galaxies are highly unusual at current times. Stellar populations of 99 +/- 0.6 % of local BCGs are (approximately) passively evolving, with star formation rates of <10 M_sol/yr. We find that in general, star formation produces only modest BCG growth at the current epoch.

  15. Melting of clusters

    Haberland, H. [Freiburg Univ., Facultat fur Physik (Germany)

    2001-07-01

    An experiment is described which allows to measure the caloric curve of size selected sodium cluster ions. This allows to determine rather easily the melting temperatures, and latent heats in the size range between 55 and 340 atoms per cluster. A more detailed analysis is necessary to show that the cluster Na{sub 147}{sup +} has a negative microcanonical heat capacity, and how to determine the entropy of the cluster from the data. (authors)

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

    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 PVI) and we discuss the results of such comparison.

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

    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...

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

    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.

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

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

    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).

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

    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.

  2. Cluster Automorphisms

    Assem, Ibrahim; Schiffler, Ralf; Shramchenko, Vasilisa

    2010-01-01

    In this article, we introduce the notion of cluster automorphism of a given cluster algebra as a $\\ZZ$-automorphism of the cluster algebra that sends a cluster to another and commutes with mutations. We study the group of cluster automorphisms in detail for acyclic cluster algebras and cluster algebras from surfaces, and we compute this group explicitly for the Dynkin types and the Euclidean types.

  3. Introduction to Clustering Algorithms and Applications

    Yang, Sibei; Tao, Liangde; Gong, Bingchen

    2014-01-01

    Data clustering is the process of identifying natural groupings or clusters within multidimensional data based on some similarity measure. Clustering is a fundamental process in many different disciplines. Hence, researchers from different fields are actively working on the clustering problem. This paper provides an overview of the different representative clustering methods. In addition, application of clustering in different field is briefly introduced.

  4. Testing X-ray measurements of galaxy cluster gas mass fraction using the cosmic distance-duality relation

    We propose a consistency test for some recent X-ray gas mass fraction (fgas) measurements in galaxy clusters, using the cosmic distance-duality relation, ηtheory = DL(1 + z)−2/DA, with luminosity distance (DL) data from the Union2 compilation of type Ia supernovae. We set ηtheory ≡ 1, instead of assigning any redshift parameterizations to it, and constrain the cosmological information preferred by fgas data along with supernova observations. We adopt a new binning method in the reduction of the Union2 data, in order to minimize the statistical errors. Four data sets of X-ray gas mass fraction, which are reported by Allen et al. (two samples), LaRoque et al. and Ettori et al., are analyzed in detail in the context of two theoretical models of fgas. The results from the analysis of Allen et al.'s samples demonstrate the feasibility of our method. It is found that the preferred cosmology by LaRoque et al.'s sample is consistent with its reference cosmology within the 1σ confidence level. However, for Ettori et al.'s fgas sample, the inconsistency can reach more than a 3σ confidence level and this dataset shows special preference to an ΩΛ = 0 cosmology

  5. Testing X-ray Measurements of Galaxy Cluster Gas Mass Fraction Using the Cosmic Distance-Duality Relation

    Wang, Xin; Huang, Y F; Zhang, Tong-Jie

    2013-01-01

    We propose a consistency test of some recent X-ray gas mass fraction ($f_{\\rm{gas}}$) measurements in galaxy clusters, using the cosmic distance-duality relation, $\\eta_{\\rm{theory}}=\\dl(1+z)^{-2}/\\da$, with luminosity distance ($\\dl$) data from the Union2 compilation of type Ia supernovae. We set $\\eta_{\\rm{theory}}\\equiv1$, instead of assigning any redshift parameterizations to it, and constrain the cosmological information preferred by $f_{\\rm{gas}}$ data along with supernova observations. We adopt a new binning method in the reduction of the Union2 data, in order to minimize the statistical errors. Four data sets of X-ray gas mass fraction, which are reported by Allen et al. (2 samples), LaRoque et al. and Ettori et al., are detailedly analyzed against two theoretical modelings of $f_{\\rm{gas}}$. The results from the analysis of Allen et al.'s samples prove the feasibility of our method. It is found that the preferred cosmology by LaRoque et al.'s sample is consistent with its reference cosmology within 1...

  6. The mathematical principles and design of the NAIS – a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

    S. Mirme

    2013-04-01

    Full Text Available The paper describes the Neutral cluster and Air Ion Spectrometer (NAIS – a multichannel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V−1 s−1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

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

    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

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

    2011-01-01

    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 human rights violations in

  9. A comprehensive approach to mode clustering

    Chen, Yen-Chi; Genovese, Christopher R.; Wasserman, Larry

    2016-01-01

    Mode clustering is a nonparametric method for clustering that defines clusters using the basins of attraction of a density estimator’s modes. We provide several enhancements to mode clustering: (i) a soft variant of cluster assignment, (ii) a measure of connectivity between clusters, (iii) a technique for choosing the bandwidth, (iv) a method for denoising small clusters, and (v) an approach to visualizing the clusters. Combining all these enhancements gives us a complete procedure for cluste...

  10. LoCuSS: A COMPARISON OF CLUSTER MASS MEASUREMENTS FROM XMM-NEWTON AND SUBARU-TESTING DEVIATION FROM HYDROSTATIC EQUILIBRIUM AND NON-THERMAL PRESSURE SUPPORT

    We compare X-ray hydrostatic and weak-lensing mass estimates for a sample of 12 clusters that have been observed with both XMM-Newton and Subaru. At an over-density of Δ = 500, we obtain 1 - M X/M WL = 0.01 ± 0.07 for the whole sample. We also divided the sample into undisturbed and disturbed sub-samples based on quantitative X-ray morphologies using asymmetry and fluctuation parameters, obtaining 1 - M X/M WL = 0.09 ± 0.06 and -0.06 ± 0.12 for the undisturbed and disturbed clusters, respectively. In addition to non-thermal pressure support, there may be a competing effect associated with adiabatic compression and/or shock heating which leads to overestimate of X-ray hydrostatic masses for disturbed clusters, for example, in the famous merging cluster A1914. Despite the modest statistical significance of the mass discrepancy, on average, in the undisturbed clusters, we detect a clear trend of improving agreement between M X and M WL as a function of increasing over-density, MX/MWL=(0.908±0.004)+(0.187±0.010)· log10(Δ/500). We also examine the gas mass fractions, fgas = M gas/M WL, finding that they are an increasing function of cluster radius, with no dependence on dynamical state, in agreement with predictions from numerical simulations. Overall, our results demonstrate that XMM-Newton and Subaru are a powerful combination for calibrating systematic uncertainties in cluster mass measurements.

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

    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 ~...

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

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

    2016-07-28

    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. PMID:27475371

  13. Cluster Evaluation of Density Based Subspace Clustering

    Sembiring, Rahmat Widia

    2010-01-01

    Clustering real world data often faced with curse of dimensionality, where real world data often consist of many dimensions. Multidimensional data clustering evaluation can be done through a density-based approach. Density approaches based on the paradigm introduced by DBSCAN clustering. In this approach, density of each object neighbours with MinPoints will be calculated. Cluster change will occur in accordance with changes in density of each object neighbours. The neighbours of each object typically determined using a distance function, for example the Euclidean distance. In this paper SUBCLU, FIRES and INSCY methods will be applied to clustering 6x1595 dimension synthetic datasets. IO Entropy, F1 Measure, coverage, accurate and time consumption used as evaluation performance parameters. Evaluation results showed SUBCLU method requires considerable time to process subspace clustering; however, its value coverage is better. Meanwhile INSCY method is better for accuracy comparing with two other methods, altho...

  14. Cluster analysis for applications

    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

  15. THREE-DIMENSIONAL STELLAR KINEMATICS AT THE GALACTIC CENTER: MEASURING THE NUCLEAR STAR CLUSTER SPATIAL DENSITY PROFILE, BLACK HOLE MASS, AND DISTANCE

    We present three-dimensional (3D) kinematic observations of stars within the central 0.5 pc of the Milky Way (MW) nuclear star cluster (NSC) 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 3D 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 BH), and distance to the Galactic center (R 0) simultaneously. We find that the inner stellar density profile of the late-type stars, ρ(r)∝r –γ, have a power law slope γ=0.05−0.60+0.29, much more shallow than the frequently assumed Bahcall-Wolf slope of γ = 7/4. The measured slope will significantly affect dynamical predictions involving the cluster, such as the dynamical friction time scale. The cluster core must be larger than 0.5 pc, which disfavors some scenarios for its origin. Our measurement of MBH=5.76−1.26+1.76×106 M ☉ and R0=8.92−0.55+0.58 kpc is consistent with that derived from stellar orbits within 1'' of Sgr A*. When combined with the orbit of S0-2, the uncertainty on R 0 is reduced by 30% (8.46−0.38+0.42 kpc). We suggest that the MW NSC can be used in the future in combination with stellar orbits to significantly improve constraints on R 0

  16. The VIMOS Public Extragalactic Redshift Survey (VIPERS). Ωm0 from the galaxy clustering ratio measured at z ~ 1

    Bel, J.; Marinoni, C.; Granett, B. R.; Guzzo, L.; Peacock, J. A.; Branchini, E.; Cucciati, O.; de la Torre, S.; Iovino, A.; Percival, W. J.; Steigerwald, H.; Abbas, U.; Adami, C.; Arnouts, S.; Bolzonella, M.; Bottini, D.; Cappi, A.; Coupon, J.; Davidzon, I.; De Lucia, G.; Fritz, A.; Franzetti, P.; Fumana, M.; Garilli, B.; Ilbert, O.; Krywult, J.; Le Brun, V.; Le Fèvre, O.; Maccagni, D.; Małek, K.; Marulli, F.; McCracken, H. J.; Paioro, L.; Polletta, M.; Pollo, A.; Schlagenhaufer, H.; Scodeggio, M.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Mellier, Y.; Moscardini, L.; Nichol, R. C.; Phleps, S.; Wolk, M.; Zamorani, G.

    2014-03-01

    We use a sample of about 22 000 galaxies at 0.65 measurement of the galaxy clustering ratio ηg,R. This statistic has favourable properties, which is defined as the ratio of two quantities characterizing the smoothed density field in spheres of a given radius R: the value of its correlation function on a multiple of this scale, ξ(nR), and its variance σ2(R). For sufficiently large values of R, this is a universal number, which captures 2-point clustering information independently of the linear bias and linear redshift-space distortions of the specific galaxy tracers. In this paper, we discuss how to extend the application of ηg,R to quasi-linear scales and how to control and remove observational selection effects, which are typical of redshift surveys as VIPERS, in detail. We verify the accuracy and efficiency of these procedures using mock catalogues that match the survey selection process. These results show the robustness of ηg,R to non-linearities and observational effects, which is related to its very definition as a ratio of quantities that are similarly affected. At an effective redshift z = 0.93, we measured the value ηg,R(15) = 0.141 ± 0.013 at R = 5h-1 Mpc. Within a flat ΛCDM cosmology and by including the best available priors on H0, ns and baryon density, we obtain a matter density parameter at the current epoch Ωm,0 = 0.270-0.025+0.029. In addition to the great precision achieved on our estimation of Ωm using VIPERS PDR-1, this result is remarkable because it appears to be in good agreement with a recent estimate at z ≃ 0.3, which was obtained by applying the same technique to the SDSS-LRG catalogue. It, therefore, supports the robustness of the present analysis. Moreover, the combination of these two measurements at z ~ 0.3 and z ~ 0.9 provides us with a very precise estimate of Ωm,0 = 0.274 ± 0.017, which highlights the great consistency between our estimation and other cosmological probes, such as baryonic acoustic oscillations, cosmic

  17. Measuring the thermal Sunyaev-Zel'dovich effect through the cross correlation of Planck and WMAP maps with ROSAT galaxy cluster catalogs

    Hajian, Amir; Bond, J. Richard [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8 (Canada); Battaglia, Nicholas [McWilliams Center for Cosmology, Wean Hall, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213 (United States); Spergel, David N. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Pfrommer, Christoph [Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Sievers, Jonathan L., E-mail: ahajian@cita.utoronto.ca, E-mail: nbattaglia@cmu.edu, E-mail: dns@astro.princeton.edu, E-mail: bond@cita.utoronto.ca, E-mail: christoph.pfrommer@h-its.org, E-mail: sievers@cita.utoronto.ca [Astrophysics and Cosmology Research Unit, University of Kwazulu-Natal, Westville, Durban 4000 (South Africa)

    2013-11-01

    We measure a significant correlation between the thermal Sunyaev-Zel'dovich effect in the Planck and WMAP maps and an X-ray cluster map based on ROSAT. We use the 100, 143 and 343 GHz Planck maps and the WMAP 94 GHz map to obtain this cluster cross spectrum. We check our measurements for contamination from dusty galaxies using the cross correlations with the 217, 545 and 857 GHz maps from Planck. Our measurement yields a direct characterization of the cluster power spectrum over a wide range of angular scales that is consistent with large cosmological simulations. The amplitude of this signal depends on cosmological parameters that determine the growth of structure (σ{sub 8} and Ω M) and scales as σ{sub 8}{sup 7.4} and Ω M{sup 1.9} around the multipole (ℓ) ∼ 1000. We constrain σ{sub 8} and Ω M from the cross-power spectrum to be σ{sub 8}(Ω M/0.30){sup 0.26} = 0.8±0.02. Since this cross spectrum produces a tight constraint in the σ{sub 8} and Ω M plane the errors on a σ{sub 8} constraint will be mostly limited by the uncertainties from external constraints. Future cluster catalogs, like those from eRosita and LSST, and pointed multi-wavelength observations of clusters will improve the constraining power of this cross spectrum measurement. In principle this analysis can be extended beyond σ{sub 8} and Ω M to constrain dark energy or the sum of the neutrino masses.

  18. Cross section measurements of the processes occurring in the fragmentation of Hn+ (3 ≤ n ≤ 35) hydrogen clusters induced by high speed (60 keV/u) collisions on helium atoms

    Different processes involved in the fragmentation of ionised hydrogen clusters H3 + (H2)(n-3)/2 (n = 5-35) have been studied in the same experiment: the fragmentation of the cluster is induced by the collision with an helium atom at high velocity (≅ c/100). The collision is realised in reversed kinematic - clusters are accelerated - which allows the detection of neutral and charged fragments. The different channels of fragmentation are identified by using coincidence techniques. For all the cluster sizes studied the capture cross sections of one electron of the target by the cluster is equal to the capture cross section of the H3+ ion. In the same way, the dissociation cross section of the H3+ core of the cluster does not depend on cluster size. These fragmentation processes are due to the interaction of H3+ core of the cluster and the helium atom without ionization of another component of the cluster. On the contrary, the cross sections of loss of one, two and three molecules by the cluster and the dissociation cross section of the cluster in all its molecular components depends strongly on the cluster size. This dependence is different from the one measured for the metastable decay of the cluster. Thus, the process of loss of molecules induced by a collision should correspond to a different dissociation mechanism. In regard of the singularities observed for the size dependence, the H9+, H15+, H19+ and H29+ clusters could be the 'core' of the biggest clusters. These observation are in agreement with the size effects of smaller magnitude observed for the dissociation cross section (all the processes). The values of the cross section for the process of at least one ionization of the cluster indicate that about 80% of the fragmentation events result from this process. (author)

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

    Tojeiro, R.; Ross, A. J.; Burden, A; Samushia, L.; Manera, M; Percival, W J; Beutler, F.; Brinkmann, J.; Brownstein, J. R.; Cuesta, A. J.; Dawson, K.; Eisenstein, D. J.; Ho, S.; Howlett, C.; Mcbride, C. K.

    2014-01-01

    RT is thankful for support from the European Research Council and the Science & Technology Facilities Council. We present the distance measurement to z = 0.32 using the eleventh data release (DR) of the Sloan Digital Sky Survey-III Baryon Acoustic Oscillation Survey (BOSS). We use 313 780 galaxies of the low-redshift (LOWZ) sample over 7341 square degrees to compute DV=(1264 ± 25)(rd/rd,fid}) - a sub 2 per cent measurement - using the baryon acoustic feature measured in the galaxy two-poin...

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

    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...

  1. Chandra Measurements of a Complete Sample of X-ray Luminous Galaxy Clusters: The Luminosity-Mass Relation

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

    2015-01-01

    We present the results of work involving a statistically complete sample of 34 galaxy clusters, in the redshift range 0.15$\\le$z$\\le$0.3 observed with Chandra. We present the calibration of the Mass-Temperature (MT) relation using hydrostatic mass estimates for the most dynamically relaxed clusters, and use this relation as a mass proxy for the full cluster sample. We find that the slope of the MT relation follows the self-similar expectation, and is consistent with previously published relations. We investigate the luminosity-Mass (LM) relation for the cluster sample, utilising a method to fully account for selection biases. We find that the difference in normalisation of the LM relation with and without accounting for selection effects is $\\approx$2. For a cluster of luminosity 10$^{45}$ erg s$^{-1}$, we find that the mass estimated from the LM relation when we account for selection effects is $\\approx$40% higher compared to the sample LM relation (not accounting for selection effects).

  2. Interface engineering for improving reliability of resistance switching in Cu/HfO2/TiO2/Pt structure

    Wei Zhou, Li; Long Shao, Xing; Yuan Li, Xiang; Jiang, Hao; Chen, Ran; Jean Yoon, Kyung; Jin Kim, Hae; Zhang, Kailiang; Zhao, Jinshi; Seong Hwang, Cheol

    2015-08-01

    Reliability and uniformity in resistance switching behaviours in top electrode Cu-sputtered TiO2-bottom electrode Pt memory structure were greatly improved by inserting an interface layer of 5 nm-thick HfO2 between Cu and 50 nm-thick TiO2. The thin HfO2 layer, with much smaller cluster size than TiO2, limited the Cu migration appropriately and induced more uniform Cu conducting filament distribution. The repeated rejuvenation and rupture of Cu filament was limited within the HfO2 layer, thereby improving the switching reliability and uniformity. This also greatly decreased operation power compared to a memory cell without the thin HfO2 layer.

  3. Magnetic properties of copper cluster-spins in BaCuO2+x (x = 0 and 0.14), investigated by magnetization and nuclear magnetic resonance measurements

    To clarify the combined magnetic behaviour of BaCuO2+x, which contains in the body-centred-cubic unit cell two Cu18O24 spherical clusters, eight Cu6O12 ring clusters, and six CuO4 lone units, we made measurements of magnetization, 63,65Cu nuclear magnetic resonance (NMR) near 6 T, and pure quadrupole resonance (PQR) in zero field on samples with well-defined oxygen contents x = 0 and 0.14. Quantitative analyses of Curie-Weiss-like susceptibility data for BaCuO2.00 indicate that Cu spins within the Cu6 clusters go into a ferromagnetically (FM) ordered ground state with a maximum spin Sr = 3 below ∼ 100 K, and those within the Cu18 clusters into an FM-like ground state below ∼ 20 K with net spin Ss ∼ 5 that is less than the maximum possible spin Ss = 9. For BaCuO2.14 the Cu spins within the Cu6 clusters go into an FM ordered ground state at a lower temperature of ∼ 30 K, and these clusters exhibit no signature of long-range magnetic ordering down to 2 K. The NMR spectra for BaCuO2.00 observed below ∼ 12 K have a trapezoidal structure that is known to be a characteristic of long-range magnetic ordering, and is consistent with the antiferromagnetic ordering of the Cu6 clusters below TN = 15 K predicted previously. On the other hand, the spectrum for BaCuO2.14 observed in a temperature range between 1.2 and ∼ 50 K has an electric quadrupole-split powder pattern structure. This provides microscopic evidence that there is no long-range magnetic ordering in BaCuO2.14. The addition of 0.14 moles of oxygen atoms results in a large suppression of some magnetic entities. We find, however, some anomalies in the NMR and PQR data for BaCuO2.14 near ∼ 10 K, which could be associated with short-range ordering of the paramagnetic Cu18 clusters

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

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

    2011-01-01

    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...... 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 in the interpretation of atmospheric measurement data obtained using chemical ionization methods. The purpose of this study is not to criticize the CIMS method, but to help understand the implications of the measured results....

  5. Cluster Symmetries and Dynamics

    Freer Martin

    2016-01-01

    Full Text Available Many light nuclei display behaviour that indicates that rather than behaving as an A-body systems, the protons and neutrons condense into clusters. The α-particle is the most obvious example of such clustering. This contribution examines the role of such α-clustering on the structure, symmetries and dynamics of the nuclei 8Be, 12C and 16O, recent experimental measurements and future perspectives.

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

    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...

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

    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

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

    Förster, M.; Haaland, S. E.; Paschmann, G.; Quinn, J. M.; Torbert, R. B.; Vaith, H.; Kletzing, C. A.

    2008-09-01

    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 other intensifies and merges with the

  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

    Battaglia, N. [Department of Physics, McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213 (United States); Bond, J. R. [Canadian Institute for Theoretical Astrophysics, 60 St George, Toronto ON, M5S 3H8 (Canada); Pfrommer, C. [Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Sievers, J. L., E-mail: christoph.pfrommer@h-its.org [Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544 (United States)

    2013-11-10

    Gas masses tightly correlate with the virial masses of galaxy clusters, allowing for a precise determination of cosmological parameters by means of X-ray surveys. However, the gas mass fractions (f{sub gas}) at the virial radius (R{sub 200}) derived from recent Suzaku observations are considerably larger than the cosmic mean, calling into question the accuracy of cosmological parameters. Here, we use a large suite of cosmological hydrodynamical simulations to study measurement biases of f{sub gas}. We employ different variants of simulated physics, including radiative gas physics, star formation, and thermal feedback by active galactic nuclei, which we show is able to arrest overcooling and to result in constant stellar mass fractions for redshifts z < 1. Computing the mass profiles in 48 angular cones, we find anisotropic gas and total mass distributions that imply an angular variance of f{sub gas} at the level of 30%. This anisotropy originates from the recent formation epoch of clusters and from the strong internal baryon-to-dark-matter density bias. In the most extreme cones, f{sub gas} can be biased high by a factor of two at R{sub 200} in massive clusters (M{sub 200} ∼ 10{sup 15} M{sub ☉}), thereby providing an explanation for high f{sub gas} measurements by Suzaku. While projection lowers this factor, there are other measurement biases that may (partially) compensate. At R{sub 200}, f{sub gas} is biased high by 20% when assuming hydrostatic equilibrium masses, i.e., neglecting the kinetic pressure, and by another ∼10%-20% due to the presence of density clumping. At larger radii, both measurement biases increase dramatically. While the cluster sample variance of the true f{sub gas} decreases to a level of 5% at R{sub 200}, the sample variance that includes both measurement biases remains fairly constant at the level of 10%-20%. The constant redshift evolution of f{sub gas} within R{sub 500} for massive clusters is encouraging for using gas masses to

  10. Predicting restrictive pulmonary function impairment from areas of clusters with similar density in pulmonary parenchyma measured by chest computed tomography

    Area of clusters with similar density in pulmonary parenchyma was calculated from attenuation value of computed tomography. The value was found to be the most significant predictor of restrictive pulmonary function impairment among reported densitometric parameters, whereas it has the lowest relation with obstructive pulmonary function impairment. The novel predictor extends the availability of computed tomography data set to redeem pulmonary function test. (author)

  11. Estimation of the location of the source region of the equatorial noise emissions from the Cluster measurements

    Hrbáčková, Zuzana; Santolík, Ondřej; Pickett, J. S.; Gurnett, D. A.

    Athens : National Observatory Of Athens, 2014. s. 140-140. [Geospace revisited: a Cluster/MAARBLE/Van Allen Probes. 15.09.2014-20.09.2014, Rhodes] Institutional support: RVO:68378289 http://geospacerev.space.noa.gr/images/BookofAbstracts.pdf

  12. Weighted Clustering

    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...

  13. Cluster Headache

    Frederick G Freitag

    1985-01-01

    Learning Objectives: Review the current understanding of the pathophysiology of cluster headache Be able to recognize the clinical features of cluster headache Be able to develop a strategy for treatment of cluster headache Cluster headache is divided into multiple subtypes under the IHC classification criteria. The vast majority of patients present with episodic cluster headache (3.1.1). This will be the focus of the presentation. The syndrome is characterized by repeated at...

  14. Epitaxial crystals of Bi{sub 2}Pt{sub 2}O{sub 7} pyrochlore through the transformation of δ–Bi{sub 2}O{sub 3} fluorite

    Gutiérrez–Llorente, Araceli, E-mail: araceli.gutierrez@urjc.es; Holtz, Megan E.; Muller, David A. [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Joress, Howie [Cornell High Energy Synchrotron Source, Cornell University, Ithaca, New York 14853 (United States); Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Woll, Arthur; Ward, Matthew J. [Cornell High Energy Synchrotron Source, Cornell University, Ithaca, New York 14853 (United States); Sullivan, Matthew C. [Department of Physics and Astronomy, Ithaca College, Ithaca, New York 14850 (United States); Brock, Joel D. [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Cornell High Energy Synchrotron Source, Cornell University, Ithaca, New York 14853 (United States)

    2015-03-01

    Bi{sub 2}Pt{sub 2}O{sub 7} pyrochlore is thought to be one of the most promising oxide catalysts for application in fuel cell technology. Unfortunately, direct film growth of Bi{sub 2}Pt{sub 2}O{sub 7} has not yet been achieved, owing to the difficulty of oxidizing platinum metal in the precursor material to Pt{sup 4+}. In this work, in order to induce oxidation of the platinum, we annealed pulsed laser deposited films consisting of epitaxial δ–Bi{sub 2}O{sub 3} 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 Bi{sub 2}Pt{sub 2}O{sub 7}. 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–Bi{sub 2}O{sub 3} and Bi{sub 2}Pt{sub 2}O{sub 7} structures appears to facilitate the pyrochlore formation. These results provide the only route to date for the formation of epitaxial Bi{sub 2}Pt{sub 2}O{sub 7}.

  15. Clustering of resting state networks.

    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.

  16. Etude d'une cellule photovoltaïque à jonction liquide : la cellule GaAs-n/(Se2-/Sen2-)/Pt

    Bourrasse, A.; Cachet, H.; Horowitz, G.; Le Crom, S.

    1982-01-01

    Une étude de la cellule GaAs-n/(Se2- /Sen2- )/Pt, où l'électrode de GaAs est protégée contre la photo-décomposition par le couple redox séléniure/polyséléniure, est présentée. Un rendement énergétique de 11 % sous éclairement par une lampe à arc xénon a été atteint. La cellule a pu fonctionner pendant huit jours sous illumination solaire sans que l'on observe de baisse de ses performances. La faible décomposition de la photoanode est attribuée à la dégradation de l'électrolyte, provoquée par ...

  17. Age and helium content of the open cluster NGC 6791 from multiple eclipsing binary members. I. Measurements, methods, and first results

    Brogaard, K; Grundahl, F; Clausen, J V; Frandsen, S; VandenBerg, D A; Bedin, L R

    2010-01-01

    Earlier measurements of the masses and radii of the detached eclipsing binary V20 in the open cluster NGC 6791 were accurate enough to demonstrate that there are significant differences between current stellar models. Here we improve on those results and add measurements of two additional detached eclipsing binaries, the cluster members V18 and V80. The enlarged sample sets much tighter constraints on the properties of stellar models than has hitherto been possible, thereby improving both the accuracy and precision of the cluster age. We employed (i) high-resolution UVES spectroscopy of V18, V20 and V80 to determine their spectroscopic effective temperatures, [Fe/H] values, and spectroscopic orbital elements, and (ii) time-series photometry from the Nordic Optical Telescope to obtain the photometric elements. The masses and radii of the V18 and V20 components are found to high accuracy, with errors on the masses in the range 0.27-0.36% and errors on the radii in the range 0.61-0.92%. V80 is found to be magnet...

  18. Surface decorated platinum carbonyl clusters

    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

  19. Exploring the origin of magnetic fields in massive stars: II. New magnetic field measurements in cluster and field stars

    Hubrig, S; Ilyin, I; Kharchenko, N V; Oskinova, L M; Langer, N; Gonzalez, J F; Kholtygin, A F; Briquet, M

    2013-01-01

    Theories on the origin of magnetic fields in massive stars remain poorly developed, because the properties of their magnetic field as function of stellar parameters could not yet be investigated. To investigate whether magnetic fields in massive stars are ubiquitous or appear only in stars with a specific spectral classification, certain ages, or in a special environment, we acquired 67 new spectropolarimetric observations for 30 massive stars. Among the observed sample, roughly one third of the stars are probable members of clusters at different ages, whereas the remaining stars are field stars not known to belong to any cluster or association. Spectropolarimetric observations were obtained during four different nights using the low-resolution spectropolarimetric mode of FORS2 (FOcal Reducer low dispersion Spectrograph) mounted on the 8-m Antu telescope of the VLT. Furthermore, we present a number of follow-up observations carried out with the high-resolution spectropolarimeters SOFIN mounted at the Nordic O...

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

    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.

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

    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.

  2. Why Are Rapidly Rotating M Dwarfs in the Pleiades so (Infra)red? New Period Measurements Confirm Rotation-dependent Color Offsets From the Cluster Sequence

    Covey, Kevin R.; Agüeros, Marcel A.; Law, Nicholas M.; Liu, Jiyu; Ahmadi, Aida; Laher, Russ; Levitan, David; Sesar, Branimir; Surace, Jason

    2016-05-01

    Stellar rotation periods (P rot) 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 P rot measurements have been obtained for hundreds of solar-mass members of the Pleiades, measurements exist for only a few low-mass (theory. To fill this gap, we report P rot for 132 low-mass Pleiades members (including nearly 100 with M ≤ 0.45 M ⊙), 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 P rot with precise BVIJHK photometry reported by Stauffer et al. and Kamai et al., we investigate known anomalies in the photometric properties of K and M Pleiades members. We confirm the correlation detected by Kamai et al. between a star's P rot and position relative to the main sequence in the cluster's color–magnitude diagram. We find that rapid rotators have redder (V ‑ K) colors than slower rotators at the same V, indicating that rapid and slow rotators have different binary frequencies and/or photospheric properties. We find no difference in the photometric amplitudes of rapid and slow rotators, indicating that asymmetries in the longitudinal distribution of starspots do not scale grossly with rotation rate.

  3. Cluster headache

    Histamine headache; Headache - histamine; Migrainous neuralgia; Headache - cluster; Horton's headache ... Doctors do not know exactly what causes cluster headaches. They ... (chemical in the body released during an allergic response) or ...

  4. Isotopic clusters

    Spectra of isotopically mixed clusters (dimers of SF6) are calculated as well as transition frequencies. The result leads to speculations about the suitability of the laser-cluster fragmentation process for isotope separation. (Auth.)

  5. On TPC cluster reconstruction

    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.

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

    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...

  7. Weighted Clustering

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

    2012-01-01

    We investigate a natural generalization of the classical clusteringproblem, considering clustering tasks in which differentinstances may have different weights.We conduct the firstextensive theoretical analysis on the influence of weighteddata on standard clustering algorithms in both the partitionaland hierarchical settings, characterizing the conditions underwhich algorithms react to weights. Extending a recent frameworkfor clustering algorithm selection, we propose intuitiveproperties that...

  8. Meaningful Clusters

    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.

  9. 集束干预措施对非计划性拔管率的影响%Impact of Cluster Intervention Measures on Incidence of Unplanned Extubation

    唐小平; 许叶华

    2013-01-01

    Objective To explore safe and individualized pipelines care cluster intervention measures in reducing the inci-dence of unplanned extubation (UEX ) in critical patients .Methods According to the risk factors of UEX in critical pa-tients ,safe and individualized pipelines care cluster intervention measures were formulated ,then the incidences of UEX be-fore and after the implementation were compared .Results The incidence of UEX decreased from 3 .2% to 1 .2% ,which had statistically significant difference (P<0 .05) .Conclusion After applying safe and individualized pipelines care cluster inter-vention measures to the EICU patients ,the incidence of UEX is reduced ,which provides a guarantee for pipeline care in critical patients .%  目的探讨管道个性化安全护理集束干预措施对危重患者非计划性拔管(UEX)发生率的影响。方法针对危重患者发生UEX的风险因素,制定管道个性化安全护理集束干预措施,比较分析实施前后的UEX发生情况。结果危重患者UEX的发生率由3.2%降至1.2%,有显著性差异(P<0.05)。结论管道个性化安全护理集束干预措施可以降低UEX发生率,保障患者管道护理安全。

  10. Coma cluster of galaxies

    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).

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

    Worsnop, D.R.; Mauldin, L.; Vehkamäki, H.; M. Ehn; Junninen, H.; Sipilä, M.; Ortega, I.K.; Smith,J; T. Petäjä; Kurtén, T.; M. Kulmala

    2011-01-01

    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 concen...

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

    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

  13. The clustering of galaxies in the SDSS-III DR10 Baryon Oscillation Spectroscopic Survey: no detectable colour dependence of distance scale or growth rate measurements

    Ross, Ashley J.; Samushia, Lado; 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, Sebastián E.; Sánchez, Ariel G.; Schneider, Donald P.; Skibba, Ramin A.; Sobreira, Flávia; Streblyanska, Alina; Swanson, Molly E. C.; Thomas, Daniel; Tinker, Jeremy L.; Wake, David A.; Zehavi, Idit; Zhao, Gong-bo

    2014-01-01

    We study the clustering of galaxies, as a function of their colour, from Data Release Ten (DR10) of the Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey. DR10 contains 540 505 galaxies with 0.43 comb = 0.443 ± 0.055. This result compares favourably to that of the full 0.43 tests on mock samples, which predict that any colour-dependent systematic uncertainty on the measured BAO position is less than 0.5 per cent.

  14. The mathematical principles and design of the NAIS – a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

    S. Mirme

    2011-12-01

    Full Text Available The paper describes the Nanometer aerosol and Air Ion Spectrometer (NAIS – a multi-channel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V−1 s−1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

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

    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 177Lu-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 18FDG 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 %, χ2 = 27.4; p = 1.2 x 10-7) 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 < 0.004) for predicting

  16. Cluster Lenses

    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...

  17. Measurements of the Effects of Spacers on the Burnout Conditions for Flow of Boiling Water in a Vertical Annulus and a Vertical 7-Rod Cluster

    The present report deals with measurements of the effects of spacers on the burnout conditions in a vertical annulus and a vertical 7-rod cluster. The following ranges of variables were studied and 162 burnout measurements were obtained. Pressure p = 31 kg/cm; Inlet sub-cooling 35 sub 2; Mass velocity 94 2/s; Burnout steam quality 0.10 BO < 0.56. The experimental results showed that the type of spacers employed during the present investigation had negligible effects on the burnout conditions and that the measured burnout heat fluxes could be predicted within ± 5 per cent by means of the correlation by Becker et al for flow in smooth channels

  18. Resampling methods for document clustering

    Volk, D.; Stepanov, M. G.

    2001-01-01

    We compare the performance of different clustering algorithms applied to the task of unsupervised text categorization. We consider agglomerative clustering algorithms, principal direction divisive partitioning and (for the first time) superparamagnetic clustering with several distance measures. The algorithms have been applied to test databases extracted from the Reuters-21578 text categorization test database. We find that simple application of the different clustering algorithms yields clus...

  19. A CLUE for CLUster Ensembles

    Kurt Hornik

    2005-01-01

    Cluster ensembles are collections of individual solutions to a given clustering problem which are useful or necessary to consider in a wide range of applications. The R package clue provides an extensible computational environment for creating and analyzing cluster ensembles, with basic data structures for representing partitions and hierarchies, and facilities for computing on these, including methods for measuring proximity and obtaining consensus and "secondary" clusterings....

  20. A Selective Fuzzy Clustering Ensemble Algorithm

    Kai Li; Peng Li

    2013-01-01

    To improve the performance of clustering ensemble method, a selective fuzzy clustering ensemble algorithm is proposed. It mainly includes selection of clustering ensemble members and combination of clustering results. In the process of member selection, measure method is defined to select the better clustering members. Then some selected clustering members are viewed as hyper-graph in order to select the more influential hyper-edges (or features) and to weight the selected features. For proce...

  1. Cluster ion beam evaporation

    Cluster ions can be made by the supercooling due to adiabatic expansion of substances to be vaporized which are ejected from a nozzle. This paper is described on the recent progress of studies concerning the cluster beam. The technique of cluster ion beam has been applied for the studies of thermonuclear plasma, the fabrication of thin films, crystal growth and electronic devices. The density of cluster ion beam is larger than that of atomic ion beam, and the formation of thin films can be easily done in high vacuum. This method is also useful for epitaxial growth. Metallic vapour cluster beam was made by the help of jetting rare gas beam. Various beam sources were developed. The characteristics of these sources were measured and analyzed. (Kato, T.)

  2. Signature of cluster disruption within magnetic fluid samples: The key information provided by low frequency alternating current susceptibility measurements

    Du, Zhongzhou; Liu, Wenzhong; Zhong, Jing; Zhou, Ming; Zhang, Pu; Cesar Morais, Paulo

    2014-05-01

    This paper is focused on the signature of thermal-assisted cluster disruption while analyzing the inverse alternating current (AC) susceptibility (1/χ) versus temperature (T) curves recorded at lower AC frequencies (f), below 300 Hz. A commercial oil-based magnetic fluid (MF) sample was used in the experiments to investigate the critical temperature (T*) that characterizes the thermal disruption of aggregates suspended within the MF sample. T* was found to reduce as f increased within the frequency range of our investigation (63-263 Hz). Furthermore, T* was found to scale with the square of the applied AC frequency. Both theoretical and experimental evidences support that the excitation field frequency (f) dependence of the critical temperature (T*) is well described by T*(f)=T*(0)-Af/21+Bf2. The model is based on energy absorption of magnetic nanoparticles in an AC magnetic field.

  3. A 2.5% measurement of the growth rate from small-scale redshift space clustering of SDSS-III CMASS galaxies

    Reid, Beth A; Leauthaud, Alexie; Tinker, Jeremy L; White, Martin

    2014-01-01

    We perform the first fit to the anisotropic clustering of SDSS-III CMASS DR10 galaxies on scales of ~ 0.8 - 32 Mpc/h. A standard halo occupation distribution model evaluated near the best fit Planck LCDM cosmology provides a good fit to the observed anisotropic clustering, and implies a normalization for the peculiar velocity field of M ~ 2 x 10^13 Msun/h halos of f*sigma8(z=0.57) = 0.450 +/- 0.011. Since this constraint includes both quasi-linear and non-linear scales, it should severely constrain modified gravity models that enhance pairwise infall velocities on these scales. Though model dependent, our measurement represents a factor of 2.5 improvement in precision over the analysis of DR11 on large scales, f*sigma8(z=0.57) = 0.447 +/- 0.028, and is the tightest single constraint on the growth rate of cosmic structure to date. Our measurement is consistent with the Planck LCDM prediction of 0.480 +/- 0.010 at the ~1.9 sigma level. Assuming a halo mass function evaluated at the best fit Planck cosmology, we...

  4. Brightest Cluster Galaxy Identification

    Leisman, Luke; Haarsma, D. B.; Sebald, D. A.; ACCEPT Team

    2011-01-01

    Brightest cluster galaxies (BCGs) play an important role in several fields of astronomical research. The literature includes many different methods and criteria for identifying the BCG in the cluster, such as choosing the brightest galaxy, the galaxy nearest the X-ray peak, or the galaxy with the most extended profile. Here we examine a sample of 75 clusters from the Archive of Chandra Cluster Entropy Profile Tables (ACCEPT) and the Sloan Digital Sky Survey (SDSS), measuring masked magnitudes and profiles for BCG candidates in each cluster. We first identified galaxies by hand; in 15% of clusters at least one team member selected a different galaxy than the others.We also applied 6 other identification methods to the ACCEPT sample; in 30% of clusters at least one of these methods selected a different galaxy than the other methods. We then developed an algorithm that weighs brightness, profile, and proximity to the X-ray peak and centroid. This algorithm incorporates the advantages of by-hand identification (weighing multiple properties) and automated selection (repeatable and consistent). The BCG population chosen by the algorithm is more uniform in its properties than populations selected by other methods, particularly in the relation between absolute magnitude (a proxy for galaxy mass) and average gas temperature (a proxy for cluster mass). This work supported by a Barry M. Goldwater Scholarship and a Sid Jansma Summer Research Fellowship.

  5. 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

    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...

  6. Cluster Chemistry

    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.

  7. Measuring the stellar luminosity function and spatial density profile of the inner 0.5 pc of the Milky Way nuclear star cluster

    Do, Tuan; Ghez, Andrea; Lu, Jessica R.; Morris, Mark R.; Yelda, Sylvana; Martinez, Gregory D.; Peter, Annika H. G.; Wright, Shelley; Bullock, James; Kaplinghat, Manoj; Matthews, K.

    2012-07-01

    We report on measurements of the luminosity function of early (young) and late-type (old) stars in the central 0.5 pc of the Milky Way nuclear star cluster as well as the density profiles of both components. The young (~ 6 Myr) and old stars (> 1 Gyr) in this region provide different physical probes of the environment around a supermassive black hole; the luminosity function of the young stars offers us a way to measure the initial mass function from star formation in an extreme environment, while the density profile of the old stars offers us a probe of the dynamical interaction of a star cluster with a massive black hole. The two stellar populations are separated through a near-infrared spectroscopic survey using the integral-field spectrograph OSIRIS on Keck II behind the laser guide star adaptive optics system. This spectroscopic survey is able to separate early-type (young) and late-type (old) stars with a completeness of 50% at K' = 15.5. We describe our method of completeness correction using a combination of star planting simulations and Bayesian inference. The completeness corrected luminosity function of the early-type stars contains significantly more young stars at faint magnitudes compared to previous surveys with similar depth. In addition, by using proper motion and radial velocity measurements along with anisotropic spherical Jeans modeling of the cluster, it is possible to measure the spatial density profile of the old stars, which has been difficult to constrain with number counts alone. The most probable model shows that the spatial density profile, n(r) propto r-γ, to be shallow with γ = 0.4 ± 0.2, which is much flatter than the dynamically relaxed case of γ = 3/2 to 7/4, but does rule out a 'hole' in the distribution of old stars. We show, for the first time, that the spatial density profile, the black hole mass, and velocity anisotropy can be fit simultaneously to obtain a black hole mass that is consistent with that derived from

  8. Friction measurements of nanometer-thick lubricant films using ultra-smooth sliding pins treated with gas cluster ion beam

    Friction properties of nanometer-thick lubricant films confined between two ultra-smooth solid surfaces are crucial to the practical performance of technologically advanced mechanical devices such as micro-electro-mechanical systems and hard disk drives. In this work, we applied argon gas cluster ion beam (Ar-GCIB) treatments to obtain ultra-smooth sliding pins for pin-on-disk tests of nanometer-thick perfluoropolyether (PFPE) lubricant films coated on magnetic disk surfaces. The GCIB treatments effectively smoothed the pin surfaces, and increases in the Ar dose decreased surface roughness. An ultra-smooth surface with a maximum peak height (Rp) less the monolayer lubricant film thickness was achieved when the Ar dose was increased to 8 × 1016 ions/cm2. We observed that both surface roughness and film thickness affected the friction coefficients of the PFPE films. To quantitatively describe the interplay of surface roughness and film thickness, we introduced two roughness characteristics: the ratio of film thickness to the surface’s root-mean-square roughness (h/σ), and a surface-pattern parameter (γ), defined as the ratio of correlation lengths in two orthogonal directions. We infer that a fixed γ and higher h/σlead to lower friction coefficients, while a fixed h/σand higher γ induce higher friction coefficients.

  9. Friction measurements of nanometer-thick lubricant films using ultra-smooth sliding pins treated with gas cluster ion beam

    Lu, Renguo [Graduate School of Information Science, Nagoya University, Nagoya 464-8601 (Japan); Zhang, Hedong, E-mail: zhang@is.nagoya-u.ac.jp [Graduate School of Information Science, Nagoya University, Nagoya 464-8601 (Japan); Mitsuya, Yasunaga [Nagoya Industrial Science Research Institute, Nagoya 464-0035 (Japan); Fukuzawa, Kenji; Itoh, Shintaro [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan)

    2013-09-01

    Friction properties of nanometer-thick lubricant films confined between two ultra-smooth solid surfaces are crucial to the practical performance of technologically advanced mechanical devices such as micro-electro-mechanical systems and hard disk drives. In this work, we applied argon gas cluster ion beam (Ar-GCIB) treatments to obtain ultra-smooth sliding pins for pin-on-disk tests of nanometer-thick perfluoropolyether (PFPE) lubricant films coated on magnetic disk surfaces. The GCIB treatments effectively smoothed the pin surfaces, and increases in the Ar dose decreased surface roughness. An ultra-smooth surface with a maximum peak height (R{sub p}) less the monolayer lubricant film thickness was achieved when the Ar dose was increased to 8 × 10{sup 16} ions/cm{sup 2}. We observed that both surface roughness and film thickness affected the friction coefficients of the PFPE films. To quantitatively describe the interplay of surface roughness and film thickness, we introduced two roughness characteristics: the ratio of film thickness to the surface’s root-mean-square roughness (h/σ), and a surface-pattern parameter (γ), defined as the ratio of correlation lengths in two orthogonal directions. We infer that a fixed γ and higher h/σlead to lower friction coefficients, while a fixed h/σand higher γ induce higher friction coefficients.

  10. Friction measurements of nanometer-thick lubricant films using ultra-smooth sliding pins treated with gas cluster ion beam

    Lu, Renguo; Zhang, Hedong; Mitsuya, Yasunaga; Fukuzawa, Kenji; Itoh, Shintaro

    2013-09-01

    Friction properties of nanometer-thick lubricant films confined between two ultra-smooth solid surfaces are crucial to the practical performance of technologically advanced mechanical devices such as micro-electro-mechanical systems and hard disk drives. In this work, we applied argon gas cluster ion beam (Ar-GCIB) treatments to obtain ultra-smooth sliding pins for pin-on-disk tests of nanometer-thick perfluoropolyether (PFPE) lubricant films coated on magnetic disk surfaces. The GCIB treatments effectively smoothed the pin surfaces, and increases in the Ar dose decreased surface roughness. An ultra-smooth surface with a maximum peak height (Rp) less the monolayer lubricant film thickness was achieved when the Ar dose was increased to 8 × 1016 ions/cm2. We observed that both surface roughness and film thickness affected the friction coefficients of the PFPE films. To quantitatively describe the interplay of surface roughness and film thickness, we introduced two roughness characteristics: the ratio of film thickness to the surface’s root-mean-square roughness (h/σ), and a surface-pattern parameter (γ), defined as the ratio of correlation lengths in two orthogonal directions. We infer that a fixed γ and higher h/σlead to lower friction coefficients, while a fixed h/σand higher γ induce higher friction coefficients.

  11. Cancer Clusters

    ... of cancer. Cancer clusters can help scientists identify cancer-causing substances in the environment. For example, in the early 1970s, a cluster ... the area and time period over which the cancers were diagnosed. They also ask about specific environmental hazards or concerns in the affected area. If ...

  12. Cluster AAR Campaign Summary Plots

    Fazakerley, A. N.; Walsh, A. P.; Garza, K. J.; Christopher, I.; Sadeghi, S.; Lindqvist, P.; Mihaljcic, B.; Forsyth, C.; Pickett, J. S.; Marklund, G. T.; Lucek, E. A.; Dandouras, I. S.

    2010-12-01

    Since late 2008 the Cluster spacecraft have been making the first four-point measurements of the Auroral Acceleration Region, opening up an exciting new opportunity for the auroral science, Cluster and wider magnetospheric physics communities. In order to stimulate auroral research with Cluster and aid in event selection, we have produced a set of summary plots for those Cluster perigee passes best suited for addressing open questions in auroral physics. The plots incorporate data from WBD, FGM, EFW, PEACE and CIS and are available from the Cluster PEACE website.

  13. Silicon clusters: Chemistry and structure

    Jarrold, M.F.; Ray, U.; Ijiri, Y. (AT and T Bell Labs., Murray Hill, NJ (USA))

    1991-01-01

    The chemical reactions of size selected silicon cluster ions (containing up to 70 atoms) have been studied with a number of different reagents using injected ion drift tube techniques. Both kinetic and equilibrium measurements have been performed as a function of temperature, and the influence of cluster annealing on chemical reactivity explored. Unlike metal clusters, where bulk behavior appears to be approached with around 30 atoms, large silicon clusters (n up to 70) are much less reactive than bulk silicon surfaces. These results suggest that the clusters in the size range examined here are not small crystals of bulk silicon, but have compact, high coordination number structures with few dangling bonds. (orig.).

  14. Clustering processes

    Ryabko, Daniil

    2010-01-01

    The problem of clustering is considered, for the case when each data point is a sample generated by a stationary ergodic process. We propose a very natural asymptotic notion of consistency, and show that simple consistent algorithms exist, under most general non-parametric assumptions. The notion of consistency is as follows: two samples should be put into the same cluster if and only if they were generated by the same distribution. With this notion of consistency, clustering generalizes such classical statistical problems as homogeneity testing and process classification. We show that, for the case of a known number of clusters, consistency can be achieved under the only assumption that the joint distribution of the data is stationary ergodic (no parametric or Markovian assumptions, no assumptions of independence, neither between nor within the samples). If the number of clusters is unknown, consistency can be achieved under appropriate assumptions on the mixing rates of the processes. (again, no parametric ...

  15. 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

    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

  16. 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

    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

  17. Buckling and reaction rate measurements in graphite moderated lattices fuelled with plutonium-uranium oxide clusters at temperatures up to 400 deg. C

    The Report describes a series of experiments carried out in SCORPIO I and II on sub-critical graphite moderated lattices fuelled with 21-rod clusters of PuO2/UO2 fuel. Three fuel batches with nominal plutonium: uranium ratios of 0.25%, 0.8% and 1.2% were investigated at temperatures between 20 deg. C and 400 deg. C. Because of the limited amounts of the three fuels, exponential measurements were made in 2-zone stacks, the outer regions of which were loaded with suitably matched 'reference fuel'. Fine structure distributions in the lattice cell were obtained with manganese and indium foils. Pu239/U235 fission ratios were determined both by fission chambers and by fission-product counting techniques. (author)

  18. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: measuring structure growth using passive galaxies

    Tojeiro, Rita; Percival, Will J.; Brinkmann, Jon; Brownstein, Joel R.; Eisenstein, Daniel J.; Manera, Marc; Maraston, Claudia; McBride, Cameron K.; Muna, Demitri; Reid, Beth; Ross, Ashley J.; Ross, Nicholas P.; Samushia, Lado; Padmanabhan, Nikhil; Schneider, Donald P.

    2012-01-01

    We explore the benefits of using a passively evolving population of galaxies to measure the evolution of the rate of structure growth between z=0.25 and z=0.65 by combining data from the SDSS-I/II and SDSS-III surveys. The large-scale linear bias of a population of dynamically passive galaxies, which we select from both surveys, is easily modeled. Knowing the bias evolution breaks degeneracies inherent to other methodologies, and decreases the uncertainty in measurements of the rate of struct...

  19. Source-receptor relationships for airborne measurements of CO2, CO and O3 above Siberia: a cluster-based approach

    M. Yu. Arshinov

    2010-02-01

    Full Text Available We analysed results of three intensive aircraft campaigns above Siberia (April and September 2006, August 2007 with a total of ~70 h of continuous CO2, CO and O3 measurements. The flight route consists of consecutive ascents and descents between Novosibirsk (55° N, 82° E and Yakutsk (62° N, 129° E. We performed retroplume calculations with the Lagrangian particle dispersion model FLEXPART for many short segments along the flight tracks. To reduce the extremely rich information on source regions provided by the model calculation into a small number of distinct cases, we performed a statistical clustering – to our knowledge for the first time – into potential source regions of the footprint emission sensitivities obtained from the model calculations. This technique not only worked well to separate source region influences but also resulted in clearly distinct tracer concentrations for the various clusters obtained. High CO and O3 concentrations were found associated with agricultural fire plumes originating from Kazakhstan in September 2006. A statistical analysis indicates that summer uptake of CO2 is largely explained (~50% of variance by air mass exposure to uptake by Siberian and sub-arctic ecosystems. This resulted in an average 5 to 10 ppm difference with overlaying air masses. Stratosphere-troposphere exchange is found to strongly influence the observed O3 mixing ratios in spring, but not in summer. European emissions contributed to high O3 concentrations above Siberia in April 2006 and August 2007, while emissions from North Eastern China also contributed to higher O3 mixing ratios in summer, but tend to lower mixing ratios in spring, when the airmass aerosol burden is important. In the lower troposphere, large-scale deposition processes in the boreal and sub-arctic boundary layer is a large O3 sink, resulting in a ~20 ppb difference with overlaying air masses. Lagrangian footprint clustering is very promising and could also be

  20. IMF Dependence of High-Latitude Thermospheric Wind Pattern Derived from CHAMP Cross-Track Accelerometer Data and the Corresponding Magnetospheric Convection from Cluster EDI Measurements

    Foerster, Matthias; Haaland, Stein E.; Rentz, Stefanie; Liu, Huixin

    Neutral thermospheric wind pattern at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both North and South polar regions are statistically analyzed in their dependence on the Interplanetary Magnetic Field (IMF) direction in the GSM y-z plane (clock angle). We compare this dependency with magnetospheric convection pattern using 1-min-averages of Cluster/EDI electric drift observations and the same IMF and solar wind sorting conditions. The spatially distributed Cluster/EDI measurements are mapped to a the common reference level at ionospheric F-region heights in a magnetic latitude/MLT grid. We obtained both regular thermospheric wind and plasma drift pattern according to the various IMF conditions. The IMF-dependency shows some similarity with the corresponding high-latitude plasma convection insofar that the larger-scale convection cells, in particular the round-shaped dusk cell for IMF By+ (By-) conditions at the Northern (Southern) Hemisphere, leave their marks on the dominant general transpolar wind circulation from the dayside to the nightside. The direction of the transpolar circulation is generally deflected toward a duskward flow, in particular in the evening to nighttime sector. The degree of deflection correlates with the IMF clock angle. It is larger for IMF By+ than for Byand is systematically larger (about 5 deg) and appear less structured at the Southern Hemisphere compared with the Northern. Thermospheric cross-polar wind amplitudes are largest for IMF Bz-/Byconditions (corresponding to sector 5) at the Northern Hemisphere, but for IMF Bz-/By+ conditions (sector 3) at the Southern because the magnetospheric convection is in favour of largest wind accelerations over the polar cap under these conditions. The overall variance of the thermospheric wind magnitude at Southern high latitudes is larger than for the Northern. This is probably due to a larger "stirring effect" at the Southern Hemisphere because

  1. Cluster editing

    Böcker, S.; Baumbach, Jan

    2013-01-01

    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. The...... algorithms for biological problems. © 2013 Springer-Verlag....... 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 of these...

  2. Cluster analysis

    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

  3. Cluster Radioactivity in 127I

    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.

  4. Predicting drug-target interaction for new drugs using enhanced similarity measures and super-target clustering.

    Shi, Jian-Yu; Yiu, Siu-Ming; Li, Yiming; Leung, Henry C M; Chin, Francis Y L

    2015-07-15

    Predicting drug-target interaction using computational approaches is an important step in drug discovery and repositioning. To predict whether there will be an interaction between a drug and a target, most existing methods identify similar drugs and targets in the database. The prediction is then made based on the known interactions of these drugs and targets. This idea is promising. However, there are two shortcomings that have not yet been addressed appropriately. Firstly, most of the methods only use 2D chemical structures and protein sequences to measure the similarity of drugs and targets respectively. However, this information may not fully capture the characteristics determining whether a drug will interact with a target. Secondly, there are very few known interactions, i.e. many interactions are "missing" in the database. Existing approaches are biased towards known interactions and have no good solutions to handle possibly missing interactions which affect the accuracy of the prediction. In this paper, we enhance the similarity measures to include non-structural (and non-sequence-based) information and introduce the concept of a "super-target" to handle the problem of possibly missing interactions. Based on evaluations on real data, we show that our similarity measure is better than the existing measures and our approach is able to achieve higher accuracy than the two best existing algorithms, WNN-GIP and KBMF2K. Our approach is available at http://web.hku.hk/∼liym1018/projects/drug/drug.html or http://www.bmlnwpu.org/us/tools/PredictingDTI_S2/METHODS.html. PMID:25957673

  5. Measurement of the Radius of Neutron Stars with High S/N Quiescent Low-mass X-ray Binaries in Globular Clusters

    Guillot, Sebastien; Webb, Natalie A; Rutledge, Robert E

    2013-01-01

    This paper presents the measurement of the neutron star (NS) radius using the thermal spectra from quiescent low-mass X-ray binaries (qLMXBs) inside globular clusters (GCs). Recent observations of NSs have presented evidence that cold ultra dense matter -- present in the core of NSs -- is best described by "normal matter" equations of state (EoSs). Such EoSs predict that the radii of NSs, Rns, are quasi-constant (within measurement errors, of ~10%) for astrophysically relevant masses (Mns > 0.5 Msun). The present work adopts this theoretical prediction as an assumption, and uses it to constrain a single Rns value from five qLMXB targets with available high signal-to-noise X-ray spectroscopic data. Employing a Markov-Chain Monte-Carlo approach, we produce the marginalized posterior distribution for Rns, constrained to be the same value for all five NSs in the sample. An effort was made to include all quantifiable sources of uncertainty into the uncertainty of the quoted radius measurement. These include the un...

  6. Cluster generator

    Donchev, Todor I.; Petrov, Ivan G.

    2011-05-31

    Described herein is an apparatus and a method for producing atom clusters based on a gas discharge within a hollow cathode. The hollow cathode includes one or more walls. The one or more walls define a sputtering chamber within the hollow cathode and include a material to be sputtered. A hollow anode is positioned at an end of the sputtering chamber, and atom clusters are formed when a gas discharge is generated between the hollow anode and the hollow cathode.

  7. The HST/ACS Coma Cluster Survey IV. Intergalactic Globular Clusters and the Massive Globular Cluster System at the Core of the Coma Galaxy Cluster

    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.

    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 is one of the nearest truly massive galaxy clusters, and is host to a correspondingly large system of globular clusters (GCs). We use imaging from the HST/ACS Coma Cluster Survey to present the first definitive detection of a large population of intracluster GCs (IGC...

  8. MEASURING DETAILED CHEMICAL ABUNDANCES FROM CO-ADDED MEDIUM-RESOLUTION SPECTRA. I. TESTS USING MILKY WAY DWARF SPHEROIDAL GALAXIES AND GLOBULAR CLUSTERS

    The ability to measure metallicities and α-element abundances in individual red giant branch (RGB) stars using medium-resolution spectra (R ≈ 6000) is a valuable tool for deciphering the nature of Milky Way dwarf satellites and the history of the Galactic halo. Extending such studies to more distant systems like Andromeda is beyond the ability of the current generation of telescopes, but by co-adding the spectra of similar stars, we can attain the necessary signal-to-noise ratio (S/N) to make detailed abundance measurements. In this paper, we present a method to determine metallicities and α-element abundances using the co-addition of medium-resolution spectra. We test the method of spectral co-addition using high-S/N spectra of more than 1300 RGB stars from Milky Way globular clusters and dwarf spheroidal galaxies obtained with the Keck II telescope/DEIMOS spectrograph. We group similar stars using photometric criteria and compare the weighted ensemble average abundances ([Fe/H], [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe]) of individual stars in each group with the measurements made on the corresponding co-added spectrum. We find a high level of agreement between the two methods, which permits us to apply this co-added spectra technique to more distant RGB stars, like stars in the M31 satellite galaxies. This paper outlines our spectral co-addition and abundance measurement methodology and describes the potential biases in making these measurements.

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

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

    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.

  11. Melting and boiling of clusters

    Clusters properties depends on their size, the transition from the atom / molecule to the bulk is often smooth and the asymptotic behaviour well understood, but for cluster melting is not the case, where irregular fluctuations are found even for clusters containing more than hundred atoms. A method to measure caloric curves for size selected cluster ions is provided. A plot of the cluster energy as a function of cluster temperature gives the caloric curve and contains all its basic thermodynamic properties. The method consists of two steps: in the first, sodium clusters ions are produced and thermalized. The heat bath was a helium gas of known temperature T, where clusters make so many collisions that they reach thermal equilibrium. Then, the thermalized clusters are extracted, transferred to high vacuum, and mass analysed. In the second step, the internal dominantly vibrational energy E of the cluster is measured by a photofragmentation technique, knowing E and T, the caloric curve E= E(T) can be plotted. As an example the Na 139+ and Na+n study is presented. (nevyjel)

  12. Cluster beam investigation with MCPs

    High intensity cluster-jet beams produced in Laval nozzles represent a very attractive and extremely interesting tool for studies at storage ring experiments, such as PANDA, or for laser-induced particle acceleration. Since the cluster properties vary with increasing number of constituents, it is essential to perform systematic measurements on the target thickness and especially on the cluster masses. For this purpose a monitoring system based on Micro Channel Plates (MCPs) combined with a phosphor screen has been developed and installed at the beam dump of the PANDA prototype cluster-jet target in Muenster. It could be shown that this MCP system allows for a direct observation of an ionised cluster beam. In addition, with this setup the possibility to visualise the vertex zone at the ANKE cluster-jet target at COSY was succesfully demonstrated, where a proton beam with a momentum of 2.09 GeV/c interacted with a hydrogen cluster-jet beam. Furthermore, cluster mass investigations can be performed in conjunction with a retardation field. In this presentation an overview of the MCP detection system, images of the cluster-jet beam and the vertex zone as well as the results of the current cluster mass measurements are presented and discussed.

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

    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.

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

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

    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...

  16. Denominators of cluster variables

    Buan, Aslak Bakke; Marsh, Robert J.; Reiten, Idun

    2007-01-01

    Associated to any acyclic cluster algebra is a corresponding triangulated category known as the cluster category. It is known that there is a one-to-one correspondence between cluster variables in the cluster algebra and exceptional indecomposable objects in the cluster category inducing a correspondence between clusters and cluster-tilting objects. Fix a cluster-tilting object T and a corresponding initial cluster. By the Laurent phenomenon, every cluster variable can be written as a Laurent...

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

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

    2016-05-01

    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 zlowz = 0.32, and the CMASS sample 777 202 galaxies with an effective redshift of zcmass = 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 σ8 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 fσ8, 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). We find f(zlowz)σ8(zlowz) = 0.394 ± 0.062, DA(zlowz)/rs(zd) = 6.35 ± 0.19, H(zlowz)rs(zd) = (11.41 ± 0.56) 103kms-1 for the LOWZ sample, and f(zcmass)σ8(zcmass) = 0.444 ± 0.038, DA(zcmass)/rs(zd) = 9.42 ± 0.15, H(z_cmass)r_s(z_d)=(13.92 ± 0.44) {10^3km}s^{-1} for the CMASS sample. We find general agreement with previous BOSS DR11 measurements. Assuming the Hubble parameter and angular distance parameter are fixed at fiducial ΛCDM values, we find f(zlowz)σ8(zlowz) = 0.485 ± 0.044 and f(zcmass)σ8(zcmass) = 0.436 ± 0.022 for the LOWZ and CMASS samples, respectively.

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

    Gil-Marín, Héctor; Percival, Will J.; 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

    2016-08-01

    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. The LOWZ sample contains 361 762 galaxies with an effective redshift of zlowz = 0.32, and the CMASS sample 777 202 galaxies with an effective redshift of zcmass = 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 σ8 by modelling the redshift-space distortion signal. When the geometrical Alcock-Paczynski effect is also constrained from the same data, we find joint constraints on fσ8, 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). We find f(zlowz)σ8(zlowz) = 0.394 ± 0.062, DA(zlowz)/rs(zd) = 6.35 ± 0.19, H(zlowz)rs(zd) = (11.41 ± 0.56) 103 km s- 1 for the LOWZ sample, and f(zcmass)σ8(zcmass) = 0.444 ± 0.038, DA(zcmass)/rs(zd) = 9.42 ± 0.15, H(zcmass)rs(zd) = (13.92 ± 0.44) 103 km s- 1 for the CMASS sample. We find general agreement with previous BOSS DR11 measurements. Assuming the Hubble parameter and angular distance parameter are fixed at fiducial Λcold dark matter values, we find f(zlowz)σ8(zlowz) = 0.485 ± 0.044 and f(zcmass)σ8(zcmass) = 0.436 ± 0.022 for the LOWZ and CMASS samples, respectively.

  19. Ion-irradiation-induced clustering in W–Re and W–Re–Os alloys: A comparative study using atom probe tomography and nanoindentation measurements

    This study examines clustering and hardening in W–2 at.% Re and W–1 at.% Re–1 at.% Os alloys induced by 2 MeV W+ ion irradiation at 573 and 773 K. Such clusters are known precursors to the formation of embrittling precipitates, a potentially life-limiting phenomenon in the operation of fusion reactor components. Increases in hardness were studied using nanoindentation. The presence of osmium significantly increased post-irradiation hardening. Atom probe tomography analysis revealed clustering in both alloys, with the size and number densities strongly dependent on alloy composition and irradiation temperature. The highest cluster number density was found in the ternary alloy irradiated at 773 K. In the ternary alloy, Os was found to cluster preferentially compared to Re. The implications of this result for the structural integrity of fusion reactor components are discussed

  20. Graph partitioning advance clustering technique

    Madhulatha, T Soni

    2012-01-01

    Clustering is a common technique for statistical data analysis, Clustering is the process of grouping the data into classes or clusters so that objects within a cluster have high similarity in comparison to one another, but are very dissimilar to objects in other clusters. Dissimilarities are assessed based on the attribute values describing the objects. Often, distance measures are used. Clustering is an unsupervised learning technique, where interesting patterns and structures can be found directly from very large data sets with little or none of the background knowledge. This paper also considers the partitioning of m-dimensional lattice graphs using Fiedler's approach, which requires the determination of the eigenvector belonging to the second smallest Eigenvalue of the Laplacian with K-means partitioning algorithm.

  1. Fuzzy Clustering

    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...

  2. Cluster's last stand?

    Lockwood, Mike

    1997-01-01

    On 4 June last year the first attempt to make three-dimensional measurements in space was lost when the Ariane 5 rocket veered off course and self-destructed, 39 s into its maiden flight. On board were four identical spacecraft which made up Cluster,a mission that the European Space Agency called a “cornerstone” of its Horizon 2000 scientific programme. A full description of the Cluster satellites is given in a special issue of Space Science Reviews (Escoubet et al. 1997). Their loss de...

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

    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 ...

  4. Detailed neutron activation measurements in lattices with 31-element PuOsub(2)-UOsub(2) clusters of simulated burned-up natural uranium fuel in heavy water moderator

    Low power experiments have been performed in the ZED-2 reactor to determine detailed neutron activation distributions in the central cell of lattices containing 31-element clusters of PuOsub(2)-UOsub(2), simulated burned-up natural uranium oxide fuel in heavy water moderator. The measurements included Mn and Cu activity distributions, Lu/Mn and in/Mn activity ratios, and Pu/U fission rate ratios over a range of three lattice pitches with air, Hsub(2)O and HB-40 coolants. Relative total neutron densities, and the Westcott spectral parameters r√Tsub(n)/Tsub(o) and Tn were inferred from the experimental results. The results indicate that the neutron density gradient across a lattice cell is larger for Hsub(2)O and HB-40 coolants, and increases with increasing Pu-239 enrichment. The spectral parameters increase (harden) with decreasing pitch and coolant moderator power (Hsub(2)O yields HB-40 yields Air), and with increasing Pu-239 content, as expected

  5. Quotients of cluster categories

    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...

  6. Regional Innovation Clusters

    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,...

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

    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. PMID:27019380

  8. Polyhedral Platinaborane Chemistry. Interaction of PMe2Ph with [((PMePh)-Ph-2)(2)PtB10H12

    Bould, Jonathan; Císařová, I.; Kennedy, J.D.

    2012-01-01

    Roč. 31, č. 7 (2012), s. 2691-2696. ISSN 0276-7333 R&D Projects: GA ČR(CZ) GAP207/11/1577; GA ČR(CZ) GAP207/11/0705 Institutional research plan: CEZ:AV0Z40320502 Keywords : NUCLEAR-MAGNETIC-RESONANCE * OXIDATIVE-INSERTION REACTIONS * CLUSTER CHEMISTRY * METALLAHETEROBORANE CHEMISTRY Subject RIV: CA - Inorganic Chemistry Impact factor: 4.145, year: 2012

  9. Magnetic Bubbles in Galaxy Clusters

    McNamara, B. R.

    2003-01-01

    I discuss Chandra X-ray Observatory measurements of cavities in galaxy clusters and their implications for heating the intracluster gas. The emerging paradigm for cooling flows has important implications for understanding self-regulated galaxy formation.

  10. Redshift-space distortions of galaxies, clusters and AGN: testing how the accuracy of growth rate measurements depends on scales and sample selections

    Marulli, Federico; Veropalumbo, Alfonso; Moscardini, Lauro; Cimatti, Andrea; Dolag, Klaus

    2015-01-01

    Redshift-space clustering anisotropies caused by cosmic peculiar velocities provide a powerful probe to test the gravity theory on large scales. However, to extract unbiased physical constraints, the clustering pattern has to be modelled accurately, taking into account the effects of non-linear dynamics at small scales, and properly describing the link between the selected cosmic tracers and the underlying dark matter field. We use a large hydrodynamic simulation to investigate how the system...

  11. Constrained Clustering With Imperfect Oracles.

    Zhu, Xiatian; Loy, Chen Change; Gong, Shaogang

    2016-06-01

    While clustering is usually an unsupervised operation, there are circumstances where we have access to prior belief that pairs of samples should (or should not) be assigned with the same cluster. Constrained clustering aims to exploit this prior belief as constraint (or weak supervision) to influence the cluster formation so as to obtain a data structure more closely resembling human perception. Two important issues remain open: 1) how to exploit sparse constraints effectively and 2) how to handle ill-conditioned/noisy constraints generated by imperfect oracles. In this paper, we present a novel pairwise similarity measure framework to address the above issues. Specifically, in contrast to existing constrained clustering approaches that blindly rely on all features for constraint propagation, our approach searches for neighborhoods driven by discriminative feature selection for more effective constraint diffusion. Crucially, we formulate a novel approach to handling the noisy constraint problem, which has been unrealistically ignored in the constrained clustering literature. Extensive comparative results show that our method is superior to the state-of-the-art constrained clustering approaches and can generally benefit existing pairwise similarity-based data clustering algorithms, such as spectral clustering and affinity propagation. PMID:25622327

  12. Clustering experiments

    Wang, Zhengwei; Tan, Ken; Di, Zengru; Roehner, Bertrand M

    2011-01-01

    It is well known that bees cluster together in cold weather, in the process of swarming (when the ``old'' queen leaves with part of the colony) or absconding (when the queen leaves with all the colony) and in defense against intruders such as wasps or hornets. In this paper we describe a fairly different clustering process which occurs at any temperature and independently of any special stimulus or circumstance. As a matter of fact, this process is about four times faster at 28 degree Celsius than at 15 degrees. Because of its simplicity and low level of ``noise'' we think that this phenomenon can provide a means for exploring the strength of inter-individual attraction between bees or other living organisms. For instance, and at first sight fairly surprisingly, our observations showed that this attraction does also exist between bees belonging to different colonies. As this study is aimed at providing a comparative perspective, we also describe a similar clustering experiment for red fire ants.

  13. Factor PD-Clustering

    Gettler Summa, Mireille; Palumbo, Francesco; Tortora, Cristina

    2012-01-01

    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. Factor PD-clustering make a linear transformation of original variables into a reduced numb...

  14. 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

    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.

  15. Spectral Active Clustering of Remote Sensing Images

    Wang, Zifeng; Xia, Gui-Song; Xiong, Caiming; Zhang, Liangpei

    2014-01-01

    Mining useful information from remote sensing images is a longstanding and challenging problem in earth observation, among which images clustering is used to discover meaningful scene information, by grouping similar image pixels into clusters. The main difficulty of image clustering, however, lies in the fact that imperfect similarity measure between images usually leads to bad clustering results. Supervised classification with labeled training samples can partially solve this problem, but t...

  16. Perfect Cluster States from Imperfect Global Entanglement

    Garrett, Michael C.; Feder, David L.

    2006-01-01

    The cluster state, the highly entangled state that is the central resource for one-way quantum computing, can be efficiently generated in a variety of physical implementations via global nearest-neighbor interactions. In practice, a systematic phase error is expected in the entangling process, resulting in imperfect cluster states. We present a stochastic measurement technique to generate large perfect cluster states and other graph states with high probability from imperfect cluster states e...

  17. Faraday rotation in clusters of galaxies

    Faraday rotation in the clusters of galaxies are estimated systematically from the rotation measures of radio sources in or behind the clusters of galaxies. A cross-correlation of the Abell catalogue of rich clusters of galaxies with the catalogue of linear polarization of radio sources resulted in the identification of 10 clusters of galaxies. The average value of the rotation measures in the clusters of galaxies is about 20 rad m-2 and correspond to the well ordered magnetic field with the value of 2 x 10-7 gauss, if the electron densities is 10-4 cm-3. (author)

  18. BRIGHTEST CLUSTER GALAXIES AND CORE GAS DENSITY IN REXCESS CLUSTERS

    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 LBCG ∝ M 0.18±0.07cl, consistent with previous work. We found that 90% of the BCGs are located within 0.035 r500 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 ∝ L 2.7±0.4BCG (where ne is measured at 0.008 r500). 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.

  19. Panchromatic Hubble Andromeda Treasury XVI. Star Cluster Formation Efficiency and the Clustered Fraction of Young Stars

    Johnson, L. Clifton; Seth, Anil C.; 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 y...

  20. Finding gene clusters for a replicated time course study

    Qin, Li-Xuan; Breeden, Linda; Self, Steven G.

    2014-01-01

    Background Finding genes that share similar expression patterns across samples is an important question that is frequently asked in high-throughput microarray studies. Traditional clustering algorithms such as K-means clustering and hierarchical clustering base gene clustering directly on the observed measurements and do not take into account the specific experimental design under which the microarray data were collected. A new model-based clustering method, the clustering of regression model...

  1. Applications of Cluster Analysis to the Creation of Perfectionism Profiles: A Comparison of two Clustering Approaches

    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.

  2. Seven poor clusters of galaxies

    Beers, T. C.; Geller, M. J.; Huchra, J. P.; Latham, D. W.; Davis, R. J.

    1984-01-01

    The measurement of 83 new redshifts from galaxies in the region of seven of the poor clusters of galaxies identified by Morgan et al (1975) and Albert et al (1977) has been followed by an estimation of cluster masses through the application of both the virial theorem and the projected mas method. For each system, these two estimates are consistent. For the two clusters with highest X-ray luminosities, the line-of-sight velocity dispersions are about 700 km/sec, while for the five other clusters, the dispersions are of the order of less than about 370 km/sec. The D or cD galaxy in each poor cluster is at the kinematic center of each system.

  3. Cluster automorphisms and compatibility of cluster variables

    Assem, Ibrahim; Schiffler, Ralf; Shramchenko, Vasilisa

    2013-01-01

    In this paper, we introduce a notion of unistructural cluster algebras, for which the set of cluster variables uniquely determines the clusters. We prove that cluster algebras of Dynkin type and cluster algebras of rank 2 are unistructural, then prove that if $\\mathcal{A}$ is unistructural or of Euclidean type, then $f: \\mathcal{A}\\to \\mathcal{A}$ is a cluster automorphism if and only if $f$ is an automorphism of the ambient field which restricts to a permutation of the cluster variables. In ...

  4. Globular Cluster Formation in the Virgo Cluster

    Moran, C Corbett; Lake, G

    2014-01-01

    Metal poor globular clusters (MPGCs) are a unique probe of the early universe, in particular the reionization era. Systems of globular clusters in galaxy clusters are particularly interesting as it is in the progenitors of galaxy clusters that the earliest reionizing sources first formed. Although the exact physical origin of globular clusters is still debated, it is generally admitted that globular clusters form in early, rare dark matter peaks (Moore et al. 2006; Boley et al. 2009). We provide a fully numerical analysis of the Virgo cluster globular cluster system by identifying the present day globular cluster system with exactly such early, rare dark matter peaks. A popular hypothesis is that that the observed truncation of blue metal poor globular cluster formation is due to reionization (Spitler et al. 2012; Boley et al. 2009; Brodie & Strader 2006); adopting this view, constraining the formation epoch of MPGCs provides a complementary constraint on the epoch of reionization. By analyzing both the l...

  5. Synthesis and Crystal Structure of Nido 11-Vertex Platinaborane[(PPh3)2PtB10H10-9,10-(H0.7Cl0.3)2

    NIE Yong; CHEN Hai-Yan; MIAO Jin-Ling; WANG Da-Qi; SUN Guo-Xin; DOU Jian-Min

    2009-01-01

    The reaction of PtCl2(PPh3)2 with closo-[B10H10]2- in t-BuOH under reflux(70 h) unexpectedly afforded the nido 11-vertex platinaborane[(PPh3)2PtB 10H10-9,10-(H0.7Cl0.3)2]1,which Was characterized by single-crystal X-ray diffraction study.Crystallographic data for 1:C36H41.40B10Cl0.60P2Pt,Mr=860.49,triclinic system,space group P-1,a=11.255(2),b=11.623(2),c=17.148(3)(A),α=81.012(2),β=88.115(3),γ=64.322(2)°,V=1995.4(7)(A)3,Z=2,Dc=1.432g/cm3,μ(MoKa)=3.662 mm-1,F(000)=851,R=0.0358 and wR=0.0951.Compound 1 has a nido11-vertex(PtBtol polyhedral skeleton with the Pt atom lying in the open PtB4 face and further ligating to two PPh3 ligands.1 is partially chlorinated at positions B(9)and B(10),and for each chloriRe atom an occupancy factor of 0.3 is given by crystallography.

  6. Application of cluster analysis to surface ozone, NO₂ and SO₂ daily patterns in an industrial area in Central-Southern Spain measured with a DOAS system.

    Adame, J A; Notario, A; Villanueva, F; Albaladejo, J

    2012-07-01

    The daily variations of surface ozone, NO₂ and SO₂ have been investigated in a heavily industrialised area in the centre of the Iberian Peninsula (Puertollano) using hourly values recorded during two years (2008-2009) with an active LP-DOAS system. The meteorological conditions and air masses have been studied using the HYSPLIT model. The maximum hourly levels of these air pollutants exceeded 100 ppb for ozone, 150 ppb for SO₂ and 210 ppb for NO₂. However, mean values for ozone, NO₂ and SO₂ were of 49, 10 and 3 ppb respectively. Daily-monthly evolutions (defined as daily evolutions for different months) have been analysed in order to know the general daily behaviour of these species. Air pollution problems have been identified using the thresholds defined in the European Directive 2008. The limits to protect human health (human health protection limitations) have been exceeded during the study period. In order to find a set of representative daily cycles for each pollutant at different air quality regimes, a K-mean cluster technique has been applied. Five and four optimal cluster numbers have been obtained for the daily patterns of ozone and SO₂ respectively. In addition, we studied the daily variation of the temperature, relative and specific humidity and wind speed associated with each air pollutant daily pattern. Ozone daily patterns showed typical daily variations with one exception of a cluster which presents a peak in the early morning. For SO₂, the first two clusters present a low mixing ratio, however cluster 3 and 4 are less frequent but with higher levels. The more frequent air pollutant daily patterns do not exceed the threshold defined in the Directive. Nevertheless, clusters with lower frequency (representing between 5 and 7% of days) exceed the thresholds and could be considered as air pollution events. PMID:22591990

  7. Measurement of performance of the pixel neural network clustering algorithm of the ATLAS experiment at $\\sqrt{s}$ = 13 TeV

    The ATLAS collaboration

    2015-01-01

    The properties of pixel clusters in dense environments are studied with $\\sqrt{s}$ = 13 TeV proton-proton collisions from the LHC, recorded by ATLAS from June to July 2015. A novel method to evaluate the performance of the artificial neural network used for identifying pixel clusters created by multiple particles is presented. Using this method, the results in data and Monte Carlo simulation are compared. The neural network, as part of the track reconstruction, shows the expected response when used on collimated tracks.

  8. Fuzzy clustering of mechanisms

    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.

  9. Healthy together Victoria and childhood obesity—a methodology for measuring changes in childhood obesity in response to a community-based, whole of system cluster randomized control trial

    Strugnell, Claudia; Millar, Lynne; Churchill, Andrew; Jacka, Felice; Bell, Colin; Malakellis, Mary; Swinburn, Boyd; Allender, Steve

    2016-01-01

    Background Healthy Together Victoria (HTV) - a complex ‘whole of system’ intervention, including an embedded cluster randomized control trial, to reduce chronic disease by addressing risk factors (physical inactivity, poor diet quality, smoking and harmful alcohol use) among children and adults in selected communities in Victoria, Australia (Healthy Together Communities). Objectives To describe the methodology for: 1) assessing changes in the prevalence of measured childhood obesity and assoc...

  10. The Sloan Nearby Cluster Weak Lensing Survey

    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.

  11. Adaptive Evolutionary Clustering

    Xu, Kevin S.; Kliger, Mark; Hero III, Alfred O.

    2011-01-01

    In many practical applications of clustering, the objects to be clustered evolve over time, and a clustering result is desired at each time step. In such applications, evolutionary clustering typically outperforms traditional static clustering by producing clustering results that reflect long-term trends while being robust to short-term variations. Several evolutionary clustering algorithms have recently been proposed, often by adding a temporal smoothness penalty to the cost function of a st...

  12. Relational visual cluster validity

    Ding, Y.; Harrison, R F

    2007-01-01

    The assessment of cluster validity plays a very important role in cluster analysis. Most commonly used cluster validity methods are based on statistical hypothesis testing or finding the best clustering scheme by computing a number of different cluster validity indices. A number of visual methods of cluster validity have been produced to display directly the validity of clusters by mapping data into two- or three-dimensional space. However, these methods may lose too much information to corre...

  13. CONSIDERATIONS REGARDING THE FACTORS THAT INFLUENCE THE PERFORMANCE OF CLUSTER

    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.

  14. Large scale clustering of protein sequences with FORCE -A layout based heuristic for weighted cluster editing

    Baumbach Jan

    2007-10-01

    Full Text Available Abstract Background Detecting groups of functionally related proteins from their amino acid sequence alone has been a long-standing challenge in computational genome research. Several clustering approaches, following different strategies, have been published to attack this problem. Today, new sequencing technologies provide huge amounts of sequence data that has to be efficiently clustered with constant or increased accuracy, at increased speed. Results We advocate that the model of weighted cluster editing, also known as transitive graph projection is well-suited to protein clustering. We present the FORCE heuristic that is based on transitive graph projection and clusters arbitrary sets of objects, given pairwise similarity measures. In particular, we apply FORCE to the problem of protein clustering and show that it outperforms the most popular existing clustering tools (Spectral clustering, TribeMCL, GeneRAGE, Hierarchical clustering, and Affinity Propagation. Furthermore, we show that FORCE is able to handle huge datasets by calculating clusters for all 192 187 prokaryotic protein sequences (66 organisms obtained from the COG database. Finally, FORCE is integrated into the corynebacterial reference database CoryneRegNet. Conclusion FORCE is an applicable alternative to existing clustering algorithms. Its theoretical foundation, weighted cluster editing, can outperform other clustering paradigms on protein homology clustering. FORCE is open source and implemented in Java. The software, including the source code, the clustering results for COG and CoryneRegNet, and all evaluation datasets are available at http://gi.cebitec.uni-bielefeld.de/comet/force/.

  15. LoCuSS: A Comparison of Cluster Mass Measurements from XMM-Newton and Subaru - Testing Deviation from Hydrostatic Equilibrium and Non-Thermal Pressure Support

    Zhang, Yu-Ying; Finoguenov, Alexis; Smith, Graham P; Piffaretti, Rocco; Valdarnini, Riccardo; Babul, Arif; Evrard, August E; Mazzotta, Pasquale; Sanderson, Alastair J R; Marrone, Daniel P

    2010-01-01

    We compare X-ray hydrostatic and weak-lensing mass estimates for a sample of 12 clusters that have been observed with both XMM-Newton and Subaru. At Delta=500 we obtain 1-M^X/M^{WL}=0.01+/-0.07 for the whole sample. We also divided the sample into relaxed and unrelaxed sub-samples based on the X-ray morphology, obtaining 1-M^X/M^{WL}=0.09+/-0.06 and -0.06+/-0.12 for the relaxed and unrelaxed clusters, respectively. Despite the modest statistical significance of the mass discrepancy, on average, in the relaxed clusters, we detect a clear trend of improving agreement between M^X and M^{WL} as a function of increasing over-density, M^X/M^{WL}=(0.908+/-0.004)+(0.187+/-0.010)*lg(Delta/500). We also examine the gas mass fractions, f_{gas}=M^{gas}/M^{WL}, finding that they are an increasing function of cluster radius, with no dependence on dynamical state, in agreement with predictions from numerical simulations. Overall, our results demonstrate that XMM-Newton and Subaru are a powerful combination for calibrating s...

  16. Measurements of whistler-mode waves in the outer Van Allen belt: systematic analysis of 11 years of multicomponent data from the Cluster STAFF-SA instrument

    Santolík, Ondřej; Macúšová, Eva; Kolmašová, Ivana; Cornilleau-Wehrlin, N.

    2013. [Radiation Belts Workshop: Comprehending, Specifying and Forecasting their Dynamics. 30.06.2013-03.07.2013, Santorini] Grant ostatní: FP7-MAARBLE(XE) 284520 Source of funding: R - rámcový projekt EK Institutional support: RVO:68378289 Keywords : whistler-mode waves * Cluster http://space-env.esa.int/indico/conferenceDisplay.py/abstractBook?confId=20

  17. Measurable Relationship Between Bright Galaxies and Their Faint Companions in WHL J085910.0+294957, a Galaxy Cluster at z = 0.30: Vestiges of Infallen Groups?

    Lee, Joon Hyeop; Kim, Minjin; Seon, Kwang-Il; Kim, Sang Chul; Yang, Soung-Chul; Ree, Chang Hee; Lee, Jong Chul; Jeong, Hyunjin; Ko, Jongwan; Choi, Changsu

    2014-01-01

    The properties of satellite galaxies are closely related to their host galaxies in galaxy groups. In cluster environments, on the other hand, the interaction between close neighbors is known to be limited. Our goal is to examine the relationships between host and satellite galaxies in the harsh environment of a galaxy cluster. To achieve this goal, we study a galaxy cluster WHL J085910.0+294957 at z = 0.30 using deep images obtained with CQUEAN CCD camera mounted on the 2.1-m Otto Struve telescope. After member selection based on the scaling relations of photometric and structural parameters, we investigate the relationship between bright (M_i < -18) galaxies and their faint (-18 < M_i < -15) companions. The weighted mean color of faint companion galaxies shows no significant dependence (< 1 sigma to Bootstrap uncertainties) on cluster-centric distance and local luminosity density as well as the luminosity and concentration of an adjacent bright galaxy. However, the weighted mean color shows margi...

  18. Measurement of 2l-nl' x-ray transitions from ≅1 μm Kr clusters irradiated by high-intensity femtosecond laser pulses

    X-ray line emission from 2l-nl' transitions in Ne-like Kr and nearby ions has been observed from ≅1 μm Kr clusters irradiated by fs-scale laser pulses at the JAERI facility in Kyoto, Japan. The incident laser intensity reached 1019 W/cm2, with pulse energies from 50 to 300 mJ and pulse durations from 30 to 500 fs. The dependence of the x-ray spectral features and intensity on the incident laser intensity is rather weak, indicating that the 1-2 ps cluster lifetimes limit the number of ions beyond Ne-like Kr that can be produced by collisional ionization. Lines from F- to Al-like Kr emitted from the cluster plasmas have been identified using data from the relativistic multiconfiguration flexible atomic code. A collisional-radiative model based on these data has been constructed and used to determine that the cluster plasma has electron densities near 1022 cm-3, temperatures of a few hundred eV, and hot electron fractions of a few percent

  19. Measurable relationship between bright galaxies and their faint companions in WHL J085910.0+294957, a galaxy cluster at z = 0.30: vestiges of infallen groups?

    Lee, Joon Hyeop; Lee, Hye-Ran; Kim, Minjin; Seon, Kwang-Il; Kim, Sang Chul; Yang, Soung-Chul; Ree, Chang Hee; Lee, Jong Chul; Jeong, Hyunjin; Ko, Jongwan [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of); Choi, Changsu, E-mail: jhl@kasi.re.kr [CEOU/Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2014-08-20

    The properties of satellite galaxies are closely related to their host galaxies in galaxy groups. In cluster environments, on the other hand, the interaction between close neighbors is known to be limited. Our goal is to examine the relationships between host and satellite galaxies in the harsh environment of a galaxy cluster. To achieve this goal, we study a galaxy cluster WHL J085910.0+294957 at z = 0.30 using deep images obtained with CQUEAN CCD camera mounted on the 2.1 m Otto Struve Telescope. After member selection based on the scaling relations of photometric and structural parameters, we investigate the relationship between bright (M{sub i} ≤ –18) galaxies and their faint (–18 < M{sub i} ≤ –15) companions. The weighted mean color of faint companion galaxies shows no significant dependence (<1σ to bootstrap uncertainties) on cluster-centric distance and local luminosity density as well as the luminosity and concentration of an adjacent bright galaxy. However, the weighted mean color shows marginal dependence (∼2.2σ) on the color of an adjacent bright galaxy when the sample is limited to bright galaxies with at least two faint companions. By using a permutation test, we confirm that the correlation in color between bright galaxies and their faint companions in this cluster is statistically significant with a confidence level of 98.7%. The statistical significance increases if we additionally remove non-members using the Sloan Digital Sky Survey photometric redshift information (∼2.6σ and 99.3%). Our results suggest three possible scenarios: (1) vestiges of infallen groups, (2) dwarf capturing, and (3) tidal tearing of bright galaxies.

  20. Measurable relationship between bright galaxies and their faint companions in WHL J085910.0+294957, a galaxy cluster at z = 0.30: vestiges of infallen groups?

    The properties of satellite galaxies are closely related to their host galaxies in galaxy groups. In cluster environments, on the other hand, the interaction between close neighbors is known to be limited. Our goal is to examine the relationships between host and satellite galaxies in the harsh environment of a galaxy cluster. To achieve this goal, we study a galaxy cluster WHL J085910.0+294957 at z = 0.30 using deep images obtained with CQUEAN CCD camera mounted on the 2.1 m Otto Struve Telescope. After member selection based on the scaling relations of photometric and structural parameters, we investigate the relationship between bright (Mi ≤ –18) galaxies and their faint (–18 < Mi ≤ –15) companions. The weighted mean color of faint companion galaxies shows no significant dependence (<1σ to bootstrap uncertainties) on cluster-centric distance and local luminosity density as well as the luminosity and concentration of an adjacent bright galaxy. However, the weighted mean color shows marginal dependence (∼2.2σ) on the color of an adjacent bright galaxy when the sample is limited to bright galaxies with at least two faint companions. By using a permutation test, we confirm that the correlation in color between bright galaxies and their faint companions in this cluster is statistically significant with a confidence level of 98.7%. The statistical significance increases if we additionally remove non-members using the Sloan Digital Sky Survey photometric redshift information (∼2.6σ and 99.3%). Our results suggest three possible scenarios: (1) vestiges of infallen groups, (2) dwarf capturing, and (3) tidal tearing of bright galaxies.

  1. Clustering in Complex Directed Networks

    Fagiolo, Giorgio

    2006-01-01

    Many empirical networks display an inherent tendency to cluster, i.e. to form circles of connected nodes. This feature is typically measured by the clustering coefficient (CC). The CC, originally introduced for binary, undirected graphs, has been recently generalized to weighted, undirected networks. Here we extend the CC to the case of (binary and weighted) directed networks and we compute its expected value for random graphs. We distinguish between CCs that count all directed triangles in t...

  2. Polarizability effect in metallic clusters

    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.

  3. Likelihood Functions for Galaxy Cluster Surveys

    Holder, G

    2006-01-01

    Galaxy cluster surveys offer great promise for measuring cosmological parameters, but survey analysis methods have not been widely studied. Using methods developed decades ago for galaxy clustering studies, it is shown that nearly exact likelihood functions can be written down for galaxy cluster surveys. The sparse sampling of the density field by galaxy clusters allows simplifications that are not possible for galaxy surveys. An application to counts in cells is explicitly tested using cluster catalogs from numerical simulations and it is found that the calculated probability distributions are very accurate at masses above several times 10^{14}h^{-1} solar masses at z=0 and lower masses at higher redshift.

  4. Principal Cluster Axes: A Projection Pursuit Index for the Preservation of Cluster Structures in the Presence of Data Reduction

    Steinley, Douglas; Brusco, Michael J.; Henson, Robert

    2012-01-01

    A measure of "clusterability" serves as the basis of a new methodology designed to preserve cluster structure in a reduced dimensional space. Similar to principal component analysis, which finds the direction of maximal variance in multivariate space, principal cluster axes find the direction of maximum clusterability in multivariate space.…

  5. Using PEACE Data from the four CLUSTER Spacecraft to Measure Compressibility, Vorticity, and the Taylor Microscale in the Magnetosheath and Plasma Sheet

    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.

  6. Integrative clustering of high-dimensional data with joint and individual clusters.

    Hellton, Kristoffer H; Thoresen, Magne

    2016-07-01

    When measuring a range of genomic, epigenomic, and transcriptomic variables for the same tissue sample, an integrative approach to analysis can strengthen inference and lead to new insights. This is also the case when clustering patient samples, and several integrative cluster procedures have been proposed. Common for these methodologies is the restriction to a joint cluster structure, equal in all data layers. We instead present a clustering extension of the Joint and Individual Variance Explained algorithm (JIVE), Joint and Individual Clustering (JIC), enabling the construction of both joint and data type-specific clusters simultaneously. The procedure builds on the connection between k-means clustering and principal component analysis, and hence, the number of clusters can be determined by the number of relevant principal components. The proposed procedure is compared with iCluster, a method restricted to only joint clusters, and simulations show that JIC is clearly advantageous when both individual and joint clusters are present. The procedure is illustrated using gene expression and miRNA levels measured in breast cancer tissue from The Cancer Genome Atlas. The analysis suggests a division into three joint clusters common for both data types and two expression-specific clusters. PMID:26917056

  7. Raman scattering and photoemission from Bi clusters

    This paper reports on Raman scattering measurements of Bi clusters which formed on disordered C films at 110K exhibit a phase transformation from nanocrystalline rhombohedral structure to a suggested disordered phase. XPS measurements on this phase indicate core level shifts attributed to intrinsic, initial state effects on cluster electronic states

  8. Partitional clustering algorithms

    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...

  9. Improvements on GPS Location Cluster Analysis for the Prediction of Large Carnivore Feeding Activities: Ground-Truth Detection Probability and Inclusion of Activity Sensor Measures.

    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.

  10. M/L, Hα Rotation Curves, and H I Gas Measurements for 329 Nearby Cluster and Field Spirals. III. Evolution in Fundamental Galaxy Parameters

    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.

  11. Cluster Evaluation of Density Based Subspace Clustering

    Sembiring, Rahmat Widia; Zain, Jasni Mohamad

    2010-01-01

    Clustering real world data often faced with curse of dimensionality, where real world data often consist of many dimensions. Multidimensional data clustering evaluation can be done through a density-based approach. Density approaches based on the paradigm introduced by DBSCAN clustering. In this approach, density of each object neighbours with MinPoints will be calculated. Cluster change will occur in accordance with changes in density of each object neighbours. The neighbours of each object ...

  12. Clustering with Spectral Methods

    Gaertler, Marco

    2002-01-01

    Grouping and sorting are problems with a great tradition in the history of mankind. Clustering and cluster analysis is a small aspect in the wide spectrum. But these topics have applications in most scientific disciplines. Graph clustering is again a little fragment in the clustering area. Nevertheless it has the potential for new pioneering and innovative methods. One such method is the Markov Clustering presented by van Dongen in 'Graph Clustering by Flow Simulation'. We investigated the qu...

  13. Sparse Convex Clustering

    Wang, Binhuan; Zhang, Yilong; Sun, Wei; Fang, Yixin

    2016-01-01

    Convex clustering, a convex relaxation of k-means clustering and hierarchical clustering, has drawn recent attentions since it nicely addresses the instability issue of traditional nonconvex clustering methods. Although its computational and statistical properties have been recently studied, the performance of convex clustering has not yet been investigated in the high-dimensional clustering scenario, where the data contains a large number of features and many of them carry no information abo...

  14. IMPROVED TEXT CLUSTERING WITH NEIGHBORS

    Sri Lalitha Y

    2015-03-01

    Full Text Available With ever increasing number of documents on web and other repositories, the task of organizing and categorizing these documents to the diverse need of the user by manual means is a complicated job, hence a machine learning technique named clustering is very useful. Text documents are clustered by pair wise similarity of documents with similarity measures like Cosine, Jaccard or Pearson. Best clustering results are seen when overlapping of terms in documents is less, that is, when clusters are distinguishable. Hence for this problem, to find document similarity we apply link and neighbor introduced in ROCK. Link specifies number of shared neighbors of a pair of documents. Significantly similar documents are called as neighbors. This work applies links and neighbors to Bisecting K-means clustering in identifying seed documents in the dataset, as a heuristic measure in choosing a cluster to be partitioned and as a means to find the number of partitions possible in the dataset. Our experiments on real-time datasets showed a significant improvement in terms of accuracy with minimum time.

  15. Breaking the hierarchy - a new cluster selection mechanism for hierarchical clustering methods

    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

  16. Distant Massive Clusters and Cosmology

    Donahue, Megan

    1999-01-01

    We present a status report of our X-ray study and analysis of a complete sample of distant (z=0.5-0.8), X-ray luminous clusters of galaxies. We have obtained ASCA and ROSAT observations of the five brightest Extended Medium Sensitivity (EMSS) clusters with z > 0.5. We have constructed an observed temperature function for these clusters, and measured iron abundances for all of these clusters. We have developed an analytic expression for the behavior of the mass-temperature relation in a low-density universe. We use this mass-temperature relation together with a Press-Schechter-based model to derive the expected temperature function for different values of Omega-M. We combine this analysis with the observed temperature functions at redshifts from 0 - 0.8 to derive maximum likelihood estimates for the value of Omega-M. We report preliminary results of this analysis.

  17. A Selective Fuzzy Clustering Ensemble Algorithm

    Kai Li

    2013-12-01

    Full Text Available To improve the performance of clustering ensemble method, a selective fuzzy clustering ensemble algorithm is proposed. It mainly includes selection of clustering ensemble members and combination of clustering results. In the process of member selection, measure method is defined to select the better clustering members. Then some selected clustering members are viewed as hyper-graph in order to select the more influential hyper-edges (or features and to weight the selected features. For processing hyper-edges with fuzzy membership, CSPA and MCLA consensus function are generalized. In the experiments, some UCI data sets are chosen to test the presented algorithm’s performance. From the experimental results, it can be seen that the proposed ensemble method can get better clustering ensemble result.

  18. Rotation and flattening of globular clusters

    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.

  19. Cluster categories and cluster-tilted algebras

    Torkildsen, Hermund Andre

    2006-01-01

    We have given an introduction to the theory of cluster categories and cluster-tilted algebras, and this was one of our main objectives in this thesis. We have seen that cluster-tilted algebras are relation-extension algebras, and this gave us a way of constructing the quiver of a cluster-tilted algebra from a tilted algebra. A cluster-tilted algebra of finite representation type is determined by its quiver, and this raised questions about the generality of this result. We defined a new class...

  20. Dietary iron-loaded rat liver haemosiderin and ferritin: in situ measurement of iron core nanoparticle size and cluster structure using anomalous small-angle x-ray scattering

    Bovell, Eliza; Buckley, Craig E.; Chua-anusorn, Wanida; Cookson, David; Kirby, Nigel; Saunders, Martin; St. Pierre, Timothy G. ((UWA)); ((Curtin U.)); ((ASRP))

    2009-03-16

    The morphology, particle size distribution and cluster structure of the hydrated iron(III) oxyhydroxide particles associated with haemosiderin and ferritin in dietary iron-loaded rat liver tissue have been investigated using transmission electron microscopy (TEM) and anomalous small-angle x-ray scattering (ASAXS). Rat liver tissue was removed from a series of female Porton rats which had been fed an iron-rich diet until sacrifice at various ages from 2-24 months. Hepatic iron concentrations ranged from 1 to 65 mg Fe g{sup -1} dry tissue. TEM studies showed both dispersed and clustered iron-containing nanoparticles. The dispersed particles were found to have mean sizes ({+-}standard deviation) of 54 {+-} 8 {angstrom} for the iron-loaded animals and 55 {+-} 7 {angstrom} for the controls. Superposition of particles in TEM images prevented direct measurement of nanoparticulate size in the clusters. The ASAXS data were modelled to provide a quantitative estimate of both the size and spacing of iron oxyhydroxide particles in the bulk samples. The modelling yielded close-packed particles with sizes of 60 to 78 {angstrom} which when corrected for anomalous scattering suggests sizes from 54 to 70 {angstrom}. Particle size distributions are of particular importance since they determine the surface iron to core iron ratios, which in turn are expected to be related to the molar toxicity of iron deposits in cells.

  1. Improving Quality of Clustering using Cellular Automata for Information retrieval

    Sree, Pokkuluri Kiran; Babu, Inampudi Ramesh

    2014-01-01

    Clustering has been widely applied to Information Retrieval (IR) on the grounds of its potential improved effectiveness over inverted file search. Clustering is a mostly unsupervised procedure and the majority of the clustering algorithms depend on certain assumptions in order to define the subgroups present in a data set .A clustering quality measure is a function that, given a data set and its partition into clusters, returns a non-negative real number representing the quality of that clust...

  2. K-Means Clustering For Segment Web Search Results

    Hasitha Indika Arumawadu; R. M. Kapila Tharanga Rathnayaka; S. K. Illangarathne

    2015-01-01

    Clustering is the power full technique for segment relevant data into different levels. This study has proposed K-means clustering method for cluster web search results for search engines. For represent documents we used vector space model and use cosine similarity method for measure similarity between user query and the search results. As an improvement of K-means clustering we used distortion curve method for identify optimal initial number of clusters.

  3. Detecting Galaxy Clusters in the DLS and CARS: a Bayesian Cluster Finder

    Ascaso, Begoña; Benítez, Narciso

    2010-01-01

    The detection of galaxy clusters in present and future surveys enables measuring mass-to-light ratios, clustering properties or galaxy cluster abundances and therefore, constraining cosmological parameters. We present a new technique for detecting galaxy clusters, which is based on the Matched Filter Algorithm from a Bayesian point of view. The method is able to determine the position, redshift and richness of the cluster through the maximization of a filter depending on galaxy luminosity, density and photometric redshift combined with a galaxy cluster prior. We tested the algorithm through realistic mock galaxy catalogs, revealing that the detections are 100% complete and 80% pure for clusters up to z 25 (Abell Richness > 0). We applied the algorithm to the CFHTLS Archive Research Survey (CARS) data, recovering similar detections as previously published using the same data plus additional clusters that are very probably real. We also applied this algorithm to the Deep Lens Survey (DLS), obtaining the first ...

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

    Gaztanaga, Enrique; Cabre, Anna; Hui, Lam

    2008-01-01

    We study the clustering of LRG galaxies in the latest spectroscopic SDSS data releases, DR6 and DR7, which sample over 1 Gpc^3/h^3 to z=0.47. The 2-point correlation function $\\xisp$ is estimated as a function of perpendicular $\\sigma$ and line-of-sight $\\pi$ (radial) directions. We find a significant detection of a peak at $r\\simeq 110$Mpc/h, which shows as a circular ring in the $\\sigma-\\pi$ plane. There is also significant evidence for a peak along the radial direction whose shape is consi...

  5. PHAT Stellar Cluster Survey. II. Andromeda Project Cluster Catalog

    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...

  6. Multilevel Techniques for the Clustering Problem

    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.

  7. Learning predictive clustering rules

    Ženko, Bernard; Džeroski, Sašo; Struyf, Jan

    2005-01-01

    The two most commonly addressed data mining tasks are predictive modelling and clustering. Here we address the task of predictive clustering, which contains elements of both and generalizes them to some extent. We propose a novel approach to predictive clustering called predictive clustering rules, present an initial implementation and its preliminary experimental evaluation.

  8. Clustering of correlated networks

    Dorogovtsev, S. N.

    2003-01-01

    We obtain the clustering coefficient, the degree-dependent local clustering, and the mean clustering of networks with arbitrary correlations between the degrees of the nearest-neighbor vertices. The resulting formulas allow one to determine the nature of the clustering of a network.

  9. Structures of Mn clusters

    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.

  10. Foodservice Occupations Cluster Guide.

    Oregon State Dept. of Education, Salem.

    Intended to assist vocational teachers in developing and implementing a cluster program in food service occupations, this guide contains sections on cluster organization and implementation and instructional emphasis areas. The cluster organization and implementation section covers goal-based planning and includes a proposed cluster curriculum, a…

  11. The Northern Sky Optical Cluster Survey II An Objective Cluster Catalog for 5800 Square Degrees

    Gal, R R; Lopes, P A A; Djorgovski, S G; Brunner, R J; Mahabal, A A; Odewahn, S C

    2003-01-01

    We present a new, objectively defined catalog of candidate galaxy clusters based on the galaxy catalogs from the Digitized Second Palomar Observatory Sky Survey (DPOSS). This cluster catalog, derived from the best calibrated plates in the high latitude (|b|>30) Northern Galactic Cap region, covers 5,800 square degrees, and contains 8,155 candidate clusters. A simple adaptive kernel density mapping technique, combined with the SExtractor object detection algorithm, is used to detect galaxy overdensities, which we identify as clusters. Simulations of the background galaxy distribution and clusters of varying richnesses and redshifts allow us to optimize detection parameters, and measure the completeness and contamination rates for our catalog. Cluster richnesses and photometric redshifts are measured, using integrated colors and magnitudes for each cluster. An extensive spectroscopic survey is used to confirm the photometric results. This catalog, with well-characterized sample properties, provides a sound basi...

  12. Vacancy-indium clusters in implanted germanium

    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.

  13. Voting-based consensus clustering for combining multiple clusterings of chemical structures

    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.

  14. Relevant Subspace Clustering

    Müller, Emmanuel; Assent, Ira; Günnemann, Stephan; Krieger, Ralph; Seidl, Thomas

    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...... clusters. Their results are typically highly redundant, i.e. many clusters are detected multiple times in several projections. In this work, we propose a novel model for relevant subspace clustering (RESCU). We present a global optimization which detects the most interesting non-redundant subspace clusters...... achieves top clustering quality while competing approaches show greatly varying performance....

  15. Tilting theory and cluster algebras

    Reiten, Idun

    2010-01-01

    We give an introduction to the theory of cluster categories and cluster tilted algebras. We include some background on the theory of cluster algebras, and discuss the interplay with cluster categories and cluster tilted algebras.

  16. IntroductionThe Cluster mission

    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. Parallel Local Graph Clustering

    Shun, Julian; Roosta-Khorasani, Farbod; Fountoulakis, Kimon; Mahoney, Michael W.

    2016-01-01

    Graph clustering has many important applications in computing, but due to growing sizes of graph, even traditionally fast clustering methods such as spectral partitioning can be computationally expensive for real-world graphs of interest. Motivated partly by this, so-called local algorithms for graph clustering have received significant interest due to the fact that they can find good clusters in a graph with work proportional to the size of the cluster rather than that of the entire graph. T...

  18. Clustering and classification

    Arabie, Phipps

    1996-01-01

    At a moderately advanced level, this book seeks to cover the areas of clustering and related methods of data analysis where major advances are being made. Topics include: hierarchical clustering, variable selection and weighting, additive trees and other network models, relevance of neural network models to clustering, the role of computational complexity in cluster analysis, latent class approaches to cluster analysis, theory and method with applications of a hierarchical classes model in psychology and psychopathology, combinatorial data analysis, clusterwise aggregation of relations, review

  19. Cluster ion beam facilities

    A brief state-of-the-art review in the field of cluster-surface interactions is presented. Ionised cluster beams could become a powerful and versatile tool for the modification and processing of surfaces as an alternative to ion implantation and ion assisted deposition. The main effects of cluster-surface collisions and possible applications of cluster ion beams are discussed. The outlooks of the Cluster Implantation and Deposition Apparatus (CIDA) being developed in Guteborg University are shown

  20. Graded cluster algebras

    Grabowski, Jan

    2015-01-01

    In the cluster algebra literature, the notion of a graded cluster algebra has been implicit since the origin of the subject. In this work, we wish to bring this aspect of cluster algebra theory to the foreground and promote its study. We transfer a definition of Gekhtman, Shapiro and Vainshtein to the algebraic setting, yielding the notion of a multi-graded cluster algebra. We then study gradings for finite type cluster algebras without coefficients, giving a full classification. Translating ...

  1. Numerical Modeling of Gamma Radiation from Galaxy Clusters

    Miniati, F

    2003-01-01

    We investigate the spatial and spectral properties of non-thermal emission from clusters of galaxies at The importance of such measurements in advancing our understanding of non-thermal processes in the intra-cluster medium is discussed.

  2. Two-plasmon decay instability’s signature in spectral lines and spectroscopic measurements of charge exchange rate in a femtosecond laser-driven cluster-based plasma

    We present the first study of two kinds of dips (L-dips and X-dips) in spectral lines from femtosecond laser-driven cluster-based plasma. We found that the observed L-dips are caused by Langmuir waves resulting from the two-plasmon decay instability and our experiment constitutes the first observation of the signature of this instability in spectral line profiles. We also observed an X-dip caused by charge exchange and used it for the experimental determination of the rate of charge exchange between the hydrogenic oxygen and fully-stripped helium—an important fundamental reference data virtually inaccessible by other experimental methods. (fast track communication)

  3. Media Clusters and Media Cluster Policies

    Karlsson, Charlie; Picard, Robert

    2011-01-01

    Large media clusters have emerged in a limited number of large cities, characterizing the geographical concentration of the global media industry. This paper explores the reasons behind the localization patterns of media industries, the effect of the rapid advancement of Information and Communication Technologies (ICT) on media clusters and the role of media cluster policies. One might draw the conclusion that with the developments of the ICT sector and the fact that there are no raw material...

  4. Testing chameleon gravity with the Coma cluster

    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...

  5. Cluster selection in divisive clustering algorithms

    Savaresi, Sergio,; Boley, Daniel L.; Bittanti, Sergio; Gazzaniga, Giovanna

    2002-01-01

    This paper deals with the problem of clustering a data-set. In particular, the bisecting divisive approach is here considered. This approach can be naturally divided into two sub-problems: the problem of choosing which cluster must be divided, and the problem of splitting the selected cluster. The focus here is on the first problem. The contribution of this work is to propose a new technique for the selection of the cluster to split. This technique is based upon the shape of...

  6. Size Determination of Argon Clusters from a Rayleigh Scattering Experiment

    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.

  7. Synthesis of the RGO/TiO2/Pt Electrocatalytic Nanocomposites and Its Performance in Fuel Cells%石墨烯基电催化剂的合成与燃料电池性能研究

    孟礼荣; 高猛; 项阳; 刘旭阳; 刘景翠; 石建军

    2015-01-01

    In order to meet the people's demands for green energy, bio ethanol and clean energy conversion e-quipment, such as direct alcohol fuel cell ( DAFCs) has attracted the attention of more and more people, espe-cially in the design and development of effective anode catalytic materials.The RGO/TiO2 and RGO/TiO2/Pt electrocatalytic nanocomposites were prepared by solvothermal reduction and UV photoreduction technique, re-spectively.The morphologies and structures of the as-prepared nanocomposites were extensively investigated by scanning electron microscopy ( SEM) , X-ray diffraction ( XRD) and FT-IR.The characterization of morphol-ogy and nanostructure shows that the graphene oxide has been reduced to graphene and Pt nanoparticles were well dispersed in the interface between graphene and TiO2 .Cyclic voltammetric ( CV) and chronoamperometric ex-periments indicate that RGO/TiO2/Pt electrocatalysts have much higher activity and stability compared to con-ventional graphene supported Pt electrocatalysts.The results showed that RGO/TiO2/Pt electrocatalysts are promising for use in direct alcohol fuel cells ( DAFCs) .%为了满足人们对绿色能源的迫切需求,生物乙醇及其清洁能源转换设备,如直接醇类燃料电池( DAFCs)吸引了越来越多人的关注,尤其是在设计和开发有效的阳极催化材料方面。采用溶剂热和紫外光还原法制备了石墨烯/二氧化钛/铂( RGO/TiO2/Pt)复合电催化材料。产物的形貌和结构分别采用扫描电子显微镜( SEM)、X-射线粉末衍射( XRD)、傅里叶变换红外光谱仪( FT-IR)等手段进行表征。形貌和结构分析结果表明,氧化石墨烯已被还原成石墨烯,铂纳米粒子均匀分散在石墨烯/二氧化钛界面。进一步研究了这种复合物的电催化性能;循环伏安等电化学研究表明:与铂和石墨烯/铂相比,石墨烯/二氧化钛/铂复合材料具有更高的催化活性和稳

  8. Comparison of Hierarchical Agglomerative Algorithms for Clustering Medical Documents

    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.

  9. Clustering environments of BL Lac objects

    Wurtz, Ronald; Ellingson, Erica; Stocke, John T.; Yee, H. K. C.

    1993-01-01

    We report measurements of the amplitude of the BL Lac galaxy spatial covariance function, B(gb), for the fields of five BL Lacertae objects. We present evidence for rich clusters around MS 1207+39 and MS 1407+59, and confirm high richness for the cluster containing H0414+009. We discuss the ease of 3C 66 A and find evidence for a poor cluster based on an uncertain redshift of z = 0.444. These data suggest that at least some BL Lac objects are consistent with being FR 1 radio galaxies in rich clusters.

  10. Young massive star clusters

    Zwart, Simon Portegies; Gieles, Mark

    2010-01-01

    Young massive clusters are dense aggregates of young stars that form the fundamental building blocks of galaxies. Several examples exist in the Milky Way Galaxy and the Local Group, but they are particularly abundant in starburst and interacting galaxies. The few young massive clusters that are close enough to resolve are of prime interest for studying the stellar mass function and the ecological interplay between stellar evolution and stellar dynamics. The distant unresolved clusters may be effectively used to study the star-cluster mass function, and they provide excellent constraints on the formation mechanisms of young cluster populations. Young massive clusters are expected to be the nurseries for many unusual objects, including a wide range of exotic stars and binaries. So far only a few such objects have been found in young massive clusters, although their older cousins, the globular clusters, are unusually rich in stellar exotica. In this review we focus on star clusters younger than $\\sim100$\\,Myr, m...

  11. Clustering problems for geochemical data

    The Union Carbide Corporation, Nuclear Division, Uranium Resource Evaluation Project uses a two-stage sampling program to identify potential uranium districts. Cluster analysis techniques are used in locating high density sampling areas as well as in identifying potential uranium districts. Problems are considered involving the analysis of multivariate censored data, laboratory measurement error, and data standardization

  12. Star Formation and Substructure in Galaxy Clusters

    Cohen, Seth A; Wegner, Gary A; Einasto, Maret; Vennik, Jaan

    2014-01-01

    We investigate the relationship between star formation (SF) and substructure in a sample of 107 nearby galaxy clusters using data from the Sloan Digital Sky Survey (SDSS). Several past studies of individual galaxy clusters have suggested that cluster mergers enhance cluster SF, while others find no such relationship. The SF fraction in multi-component clusters (0.228 +/- 0.007) is higher than that in single-component clusters (0.175 +/- 0.016) for galaxies with M^0.1_r < -20.5. In both single- and multi-component clusters, the fraction of star-forming galaxies increases with clustercentric distance and decreases with local galaxy number density, and multi-component clusters show a higher SF fraction than single-component clusters at almost all clustercentric distances and local densities. Comparing the SF fraction in individual clusters to several statistical measures of substructure, we find weak, but in most cases significant at greater than 2 sigma, correlations between substructure and SF fraction. The...

  13. Cluster automorphism groups of cluster algebras with coefficients

    Chang, Wen; Zhu, Bin

    2015-01-01

    We study the cluster automorphism group of a skew-symmetric cluster algebra with geometric coefficients. For this, we introduce the notion of gluing free cluster algebra, and show that under a weak condition the cluster automorphism group of a gluing free cluster algebra is a subgroup of the cluster automorphism group of its principal part cluster algebra (i.e. the corresponding cluster algebra without coefficients). We show that several classes of cluster algebras with coefficients are gluin...

  14. Nature of multiple-nucleus cluster galaxies

    Merritt, D.

    1984-05-01

    In models for the evolution of galaxy clusters which include dynamical friction with the dark binding matter, the distribution of galaxies becomes more concentrated to the cluster center with time. In a cluster like Coma, this evolution could increase by a factor of approximately 3 the probability of finding a galaxy very close to the cluster center, without decreasing the typical velocity of such a galaxy significantly below the cluster mean. Such an enhancement is roughly what is needed to explain the large number of first-ranked cluster galaxies which are observed to have extra ''nuclei''; it is also consistent with the high velocities typically measured for these ''nuclei.'' Unlike the cannibalism model, this model predicts that the majority of multiple-nucleus systems are transient phenomena, and not galaxies in the process of merging.

  15. Data clustering theory, algorithms, and applications

    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.

  16. What Makes Clusters Decline?

    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...

  17. Conceptual design of a He-cooled divertor with integrated flow and heat transfer Promoters (PPCS subtask TW3-TRP-001-D2). Pt. 2. Detailed version

    Norajitra, P. (ed.); Kruessmann, R. (comp.)

    2004-04-01

    This report represents a summary of our knowledge after little more than one year of development of a helium-cooled divertor. The design goal is to reach at least 10 MW/m{sup 2} at a reasonable pumping power for a fusion power plant operating under DEMO conditions. In the first part, design requirements for the divertor are given and the current design using low-activation materials is described. In the second part, materials choice and promising tungsten alloy materials are pointed out. In view of the operation temperature window defined, materials choice for the divertor components is limited, i.e. tungsten for the thermal shield in the form of small tiles, W-1%La{sub 2}O{sub 3} for the thimble, and high-temperature ODS for the back bone structure. To broaden the operating temperature window of the divertor for obtaining a larger safety margin in the design, further development of tungsten alloys as thimble material is required. Promising methods (EDM, ECM and PIM) are identified for the fabrication of pin and slot arrays from tungsten, which need to be further developed. In the third part, computational fluid dynamics (CFD) analyses and thermomechanical finite element (FE) simulation calculations are covered. Comparisons of the pressure loss calculated by the CFD programs with first results of the pressure loss measurement performed at EFREMOV are made, the results are discussed. FE simulations revealed opportunities for the improvement of the design. The last part deals with the planning of experimental devices to confirm the theoretical findings. To validate the CFD programs, helium experiments are planned to be performed in the helium blanket test loop HEBLO at FZK/IMF III in the middle of 2004 using a single finger test mock-up of 10:1 in scale. For the high-heat-flux tests, a large helium loop is planned to be constructed at the EFREMOV Institute in St. Petersburg, Russia. Planning and specification of the experiment programmes are under way. The overall

  18. Laser-Cluster interaction in Mid-IR range

    Park, Hyunwook; Wang, Zhou; Agostini, Pierre; Dimauro, Louis

    2015-05-01

    We report an experimental study on high harmonic generation (HHG) from inert gas clusters in direct comparison with atomic gases. In the experiment, noble gas clusters, which are produced by a supersonic pulsed jet, interact with infrared lasers at moderate intensity and generate high-order harmonics. Harmonic yields are recorded as a function of cluster size in an optical spectrometer, and group delay measurements are conducted with RABBITT method. In the HHG amplitude measurements, we observed a fast increase of the yield with the size of the clusters, and slowdown when clusters are larger than a critical size. In the HHG phase measurements, we observed almost identical group delay of harmonics from the cluster comparing with the monomer, which supports three step model in harmonic generation from noble gas clusters. A 1D Lewenstein's model in a cluster is constructed with an assumption of partially delocalized electron behavior. Army Res Office.

  19. THE SIZE SCALE OF STAR CLUSTERS

    Direct N-body simulations of star clusters in a realistic Milky-Way-like potential are carried out using the code NBODY6. Based on these simulations, a new relationship between scale size and galactocentric distance is derived: the scale size of star clusters is proportional to the hyperbolic tangent of the galactocentric distance. The half-mass radius of star clusters increases systematically with galactocentric distance but levels off when star clusters orbit the galaxy beyond ∼40 kpc. These simulations show that the half-mass radius of individual star clusters varies significantly as they evolve over a Hubble time, more so for clusters with shorter relaxation times, and remains constant through several relaxation times only in certain situations when expansion driven by the internal dynamics of the star cluster and the influence of the host galaxy tidal field balance each other. Indeed, the radius of a star cluster evolving within the inner 20 kpc of a realistic galactic gravitational potential is severely truncated by tidal interactions and does not remain constant over a Hubble time. Furthermore, the half-mass radius of star clusters measured with present-day observations bears no memory of the original cluster size. Stellar evolution and tidal stripping are the two competing physical mechanisms that determine the present-day size of globular clusters. These simulations also show that extended star clusters can form at large galactocentric distances while remaining fully bound to the host galaxy. There is thus no need to invoke accretion from an external galaxy to explain the presence of extended clusters at large galactocentric distances in a Milky-Way-type galaxy.

  20. Analysis of Various Clustering Algorithms

    Asst Prof. Sunila Godara,; Ms. Amita Verma,

    2013-01-01

    Data clustering is a process of putting similar data into groups. A clustering algorithm partitions a data set into several groups such that the similarity within a group is larger than among groups. This paper reviews four types of clustering techniques- k-Means Clustering, Farther first clustering, Density Based Clustering, Filtered clusterer. These clustering techniques are implemented and analyzed using a clustering tool WEKA. Performance of the 4 techniques are presented and compared.