18,497 research outputs found

    Rich-club vs rich-multipolarization phenomena in weighted networks

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    Large scale hierarchies characterize complex networks in different domains. Elements at their top, usually the most central or influential, may show multipolarization or tend to club forming tightly interconnected communities. The rich-club phenomenon quantified this tendency based on unweighted network representations. Here, we define this metric for weighted networks and discuss the appropriate normalization which preserves nodes' strengths and discounts structural strength-strength correlations if present. We find that in some real networks the results given by the weighted rich-club coefficient can be in sharp contrast to the ones in the unweighted approach. We also discuss that the scanning of the weighted subgraphs formed by the high-strength hubs is able to unveil features contrary to the average: the formation of local alliances in rich-multipolarized environments, or a lack of cohesion even in the presence of rich-club ordering. Beyond structure, this analysis matters for understanding correctly functionalities and dynamical processes relying on hub interconnectedness.Comment: 12 pages, 2 figure

    Cluster of galaxies around seven radio-loud QSOs at 1<z<1.6: K-band images

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    We have conducted a NIR study of the environments of seven radio-loud quasars at redshifts 1<z<1.6. In present paper we describe deep KK band images obtained for the fields of ~6X6 arcmin around the quasars with 3σ\sigma limiting magnitudes of K~20.5. These fields were previously studied using deep B and R band images (Sanchez & Gonzalez-Serrano 1999). Using together optical and NIR data, it has been found a significant excess of galaxies which optical-NIR colours, luminosity, spatial scale, and number of galaxies are compatible with clusters at the redshift of the quasar. We have selected a sample of cluster candidates analyzing the R-K vs. K diagram. A ~25% of the candidates present red optical-NIR colours and an ultraviolet excess. This population has been also found in clusters around quasars at the same redshifts (Tanaka et al. 2000; Haines et al. 2001). These galaxies seem to follow a mixed evolution: a main passive evolution plus late starformation processes. The quasars do not inhabit the core of the clusters, being found in the outer regions. This result agrees with the hypothesis that the origin/feeding mechanism of the nuclear activity were merging processes. The quasars inhabit the region were a collision is most probably to produce a merger.Comment: 15 pages. A&A, accepted for publishin

    Transition matrices for symmetric and quasisymmetric Hall-Littlewood polynomials

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    We introduce explicit combinatorial interpretations for the coefficients in some of the transition matrices relating to skew Hall-Littlewood polynomials P_lambda/mu(x;t) and Hivert's quasisymmetric Hall-Littlewood polynomials G_gamma(x;t). More specifically, we provide: 1) the G-expansions of the Hall-Littlewood polynomials P_lambda, the monomial quasisymmetric polynomials M_alpha, the quasisymmetric Schur polynomials S_alpha, and the peak quasisymmetric functions K_alpha; 2) an expansion of P_lambda/mu in terms of the F_alpha's. The F-expansion of P_lambda/mu is facilitated by introducing starred tableaux.Comment: 28 pages; added brief discussion of the Hall-Littlewood Q', typos corrected, added references in response to referee suggestion

    Vacuum decay in an interacting multiverse

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    We examine a new multiverse scenario in which the component universes interact. We focus our attention to the process of "true" vacuum nucleation in the false vacuum within one single element of the multiverse. It is shown that the interactions lead to a collective behaviour that might lead, under specific conditions, to a pre-inflationary phase and ensued distinguishable imprints in the comic microwave background radiation.Comment: 9 pages, 5 figure

    Towards wafer scale inductive determination of magnetostatic and dynamic parameters of magnetic thin films and multilayers

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    We investigate an inductive probe head suitable for non-invasive characterization of the magnetostatic and dynamic parameters of magnetic thin films and multilayers on the wafer scale. The probe is based on a planar waveguide with rearward high frequency connectors that can be brought in close contact to the wafer surface. Inductive characterization of the magnetic material is carried out by vector network analyzer ferromagnetic resonance. Analysis of the field dispersion of the resonance allows the determination of key material parameters such as the saturation magnetization MS or the effective damping parameter Meff. Three waveguide designs are tested. The broadband frequency response is characterized and the suitability for inductive determination of MS and Meff is compared. Integration of such probes in a wafer prober could in the future allow wafer scale in-line testing of magnetostatic and dynamic key material parameters of magnetic thin films and multilayers

    Lagrangian Volume Deformations around Simulated Galaxies

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    We present a detailed analysis of the local evolution of 206 Lagrangian Volumes (LVs) selected at high redshift around galaxy seeds, identified in a large-volume Λ\Lambda cold dark matter (Λ\LambdaCDM) hydrodynamical simulation. The LVs have a mass range of 1−1500×1010M⊙1 - 1500 \times 10^{10} M_\odot. We follow the dynamical evolution of the density field inside these initially spherical LVs from z=10z=10 up to zlow=0.05z_{\rm low} = 0.05, witnessing highly non-linear, anisotropic mass rearrangements within them, leading to the emergence of the local cosmic web (CW). These mass arrangements have been analysed in terms of the reduced inertia tensor IijrI_{ij}^r, focusing on the evolution of the principal axes of inertia and their corresponding eigendirections, and paying particular attention to the times when the evolution of these two structural elements declines. In addition, mass and component effects along this process have also been investigated. We have found that deformations are led by dark matter dynamics and they transform most of the initially spherical LVs into prolate shapes, i.e. filamentary structures. An analysis of the individual freezing-out time distributions for shapes and eigendirections shows that first most of the LVs fix their three axes of symmetry (like a skeleton) early on, while accretion flows towards them still continue. Very remarkably, we have found that more massive LVs fix their skeleton earlier on than less massive ones. We briefly discuss the astrophysical implications our findings could have, including the galaxy mass-morphology relation and the effects on the galaxy-galaxy merger parameter space, among others.Comment: 23 pages, 20 figures. Minor editorial improvement
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