A centrality measure for communication ability in weighted network

This paper proposes a new node centrality measurement in a weighted network, the communication centrality, which is inspired by Hirsch’s h$h$-index. We investigated the properties of the communication centrality, and proved that the distribution of the communication centrality has the power-law upper tail in weighted scale-free networks. Relevant measures for node and network are discussed as extensions. A case study of a scientific collaboration network indicates that the communication centrality is different from other common centrality measures and other h$h$-type indexes. Communication centrality displays moderate correlation with other indexes, and contains a well-balanced mix of other centrality measures and cannot be replaced by any of them.     

Measurements of magnetostriction of paramagnetic Fe–Mo–Cu–B metallic glasses

Magnetostriction of amorphous Fe₇₉Mo₈Cu₁B₁₂, (Fe₁₂Co₁)₇₉Mo₈Cu₁B₁₂ and (Fe₉Co₁)₇₉Mo₈Cu₁B₁₂ prepared by planar flow casting was measured using a direct method. The results indicate that magnetostriction in parallel (_λ∥)$({\lambda }_{\parallel })$ and perpendicular (_λ⊥)$({\lambda }_{\perp })$ directions of applied magnetic field is linearly dependent on magnetic field. In order to determine the influences of chemical composition and the conditions of sample preparation the magnetostriction of pure BCC-Fe, Cu and Mo were also measured. Samples containing Co with Curie temperatures slightly above room temperatures were shown to exhibit a hybrid magnetostriction behaviour with both ferromagnetic and paramagnetic features.     

Exact solution of the XXX Gaudin model with generic open boundaries

The XXX Gaudin model with generic integrable open boundaries specified by the most general non-diagonal reflecting matrices is studied. Besides the inhomogeneous parameters, the associated Gaudin operators have six free parameters which break the U(1)$U\left(1\right)$-symmetry. With the help of the off-diagonal Bethe ansatz, we successfully obtained the eigenvalues of these Gaudin operators and the corresponding Bethe ansatz equations.     

Superconnections and index theory

We investigate index theory in the context of Dirac operators coupled to superconnections. In particular, we prove a local index theorem for such operators, and for families of such operators. We investigate η$\eta$-invariants and prove an APS theorem, and construct a geometric determinant line bundle for families of such operators, computing its curvature and holonomy in terms of familiar index theoretic quantities.     

The method of increments—a wavefunction-based ab initio correlation method for solids

An overview of wavefunction-based correlation methods generalised for the application to solids is presented. Those methods based on a preceding Hartree–Fock treatment explicitly calculate the many-body wavefunction in contrast to the density-functional theory which relies on the ground-state density of the system. This review focus on the so-called method of increments where the correlation energy of the solid is expanded in terms of localised orbitals or of a group of localised orbitals. The method of increments is applied to a great variety of materials, from covalent semiconductors to ionic insulators, from large band-gap materials like diamond to the half-metal α$\alpha$-tin, from large molecules like fullerenes over polymers, graphite to three-dimensional solids. Rare-gas crystals where the binding is van der Waals like are treated as well as solid mercury, where the metallic binding is entirely due to correlation. Strongly correlated systems are examined and the correlation driven metal–insulator transition is described at an ab initio level.     

Graphite C-axis thermal conductivity

This paper models the c$c$-axis thermal conductivity of thin graphite layers taking into account phonon confinement. A Debye model is used to calculate graphite c$c$-axis thermal conductivity, which is found to be 4 orders of magnitude smaller than in the graphite basal plane. This reduced thermal conductivity is promising for devices with improved thermoelectric figure of merit, ZT$ZT$, and thermal conduction along graphite c$c$-axis. Results of graphite thermal conductivity in the basal plane are also presented and discussed. These calculations have been done for ideal graphite structures that are a few monolayers thick, free of defects, and free of boundary scattering processes. To achieve the low calculated values of thermal conductivity, it will be necessary to fabricate high-quality graphite structures; this will pose significant fabrication challenges.     

Anisotropy and magnetization process in soft magnets: Principles,experiments, applications

Understanding and controlling the anisotropy energy and its effects has proved vital to the development of soft magnetic materials and their applications. Indeed, acting on composition and structure and working out specific annealing treatments, a large variety of anisotropy-governed behaviors under DC and AC excitation can be obtained. These are discussed in the present paper, together with special problems arising in the characterization of anisotropic soft magnets and a few significant applications. It is stressed how features like J$J$–H$H$ loop shape, energy losses, and magnetoresistance effects can be controlled, in crystalline and amorphous materials, by the methods of induced anisotropy. The high-frequency behavior of these materials can be strongly affected by the anisotropy field via resonant absorption of energy. This calls for tradeoff between the values of permeability and resonance frequency.     

Ranking the spreading influence in complex networks

Identifying the node spreading influence in networks is an important task to optimally use the network structure and ensure the more efficient spreading in information. In this paper, by taking into account the shortest distance between a target node and the node set with the highest k$k$-core value, we present an improved method to generate the ranking list to evaluate the node spreading influence. Comparing with the epidemic process results for four real networks and the Barabási–Albert network, the parameterless method could identify the node spreading influence more accurately than the ones generated by the degree k$k$, closeness centrality, k$k$-shell and mixed degree decomposition methods. This work would be helpful for deeply understanding the node importance of a network.     

On classes of non-Gaussian asymptotic minimizers in entropic uncertainty principles

In this paper we revisit the Bialynicki-Birula and Mycielski uncertainty principle and its cases of equality. This Shannon entropic version of the well-known Heisenberg uncertainty principle can be used when dealing with variables that admit no variance. In this paper, we extend this uncertainty principle to Rényi entropies. We recall that in both Shannon and Rényi cases, and for a given dimension n$n$, the only case of equality occurs for Gaussian random vectors. We show that as n$n$ grows, however, the bound is also asymptotically attained in the cases of n$n$-dimensional Student-t$t$ and Student-r$r$ distributions. A complete analytical study is performed in a special case of a Student-t$t$ distribution. We also show numerically that this effect exists for the particular case of a n$n$-dimensional Cauchy variable, whatever the Rényi entropy considered, extending the results of Abe and illustrating the analytical asymptotic study of the Student-t$t$ case. In the Student-r$r$ case, we show numerically that the same behavior occurs for uniformly distributed vectors. These particular cases and other ones investigated in this paper are interesting since they show that this asymptotic behavior cannot be considered as a “Gaussianization” of the vector when the dimension increases.     

Ferrimagnetic properties of Co/(Gd–Co) multilayers

Co/(Gd–Co) multilayers have been prepared by rf-sputtering and investigated by means of Transverse Magnetooptic Kerr Effect (TMOKE), SQUID and VSM magnetometry. The composition of amorphous _Gd0.36Co0.64${\mathrm{Gd}}_{0.36}{\mathrm{Co}}_{0.64}$ layers was chosen so that their saturation magnetization was dominated by Gd moments in all the temperature range. Co and Gd–Co layers formed a macroscopic ferrimagnetically coupled system displaying a compensation temperature. Complete magnetic moment compensation was found at such point. An inversion of TMOKE hysteresis loops and a divergent behaviour of coercivity were also observed. By changing the layers thickness it has been possible to control the magnetic characteristics of the Co/(Gd–Co) structures, in particular the compensation takes place at different temperatures.     

The phenomenology of Dvali–Gabadadze–Porrati cosmologies

Cosmologists today are confronted with the perplexing reality that the universe is currently accelerating in its expansion. Nevertheless, the nature of the fuel that drives today's cosmic acceleration is an open and tantalizing mystery. There exists the intriguing possibility that the acceleration is not the manifestation of yet another mysterious ingredient in the cosmic gas tank (dark energy), but rather our first real lack of understanding of gravity itself, and even possibly a signal that there might exist dimensions beyond that which we can currently observe. The braneworld model of Dvali, Gabadadze and Porrati (DGP) is a theory where gravity is altered at immense distances by the excruciatingly slow leakage of gravity off our three-dimensional Universe and, as a modified-gravity theory, has pioneered this line of investigation. I review the underlying structure of DGP gravity and those phenomenological developments relevant to cosmologists interested in a pedagogical treatment of this intriguing model.     

Enhanced nonlinear optical responses of materials: Composite effects

We review recent theoretical progress in understanding physical processes of composite effects on enhanced third-order nonlinear optical responses of various kinds of the recently-proposed nonlinear optical materials, namely, colloidal nanocrystals with inhomogeneous metallodielectric particles or a graded-index host, metallic films with inhomogeneous microstructures adjusted by ion doping or temperature gradient, composites with compositional gradation or graded particles, and magneto-controlled ferrofluid-based nonlinear optical materials.     

Theory of extreme correlations using canonical Fermions and path integrals

The  t$t$–J$J$  model is studied using a novel and rigorous mapping of the Gutzwiller projected electrons, in terms of canonical electrons. The mapping has considerable similarity to the Dyson–Maleev transformation relating spin operators to canonical Bosons. This representation gives rise to a non Hermitian quantum theory, characterized by minimal redundancies. A path integral representation of the canonical theory is given. Using it, the salient results of the extremely correlated Fermi liquid (ECFL) theory, including the previously found Schwinger equations of motion, are easily rederived. Further, a transparent physical interpretation of the previously introduced auxiliary Greens function and the ‘caparison factor’, is obtained.     

Needle-like domain structure in Co films deposited on Mo (1 1 0)

Magnetization reversal processes and domain structures have been studied in Mo(1 1 0)/Co(0 0 0 1)/Au(1 1 1) structures grown by molecular beam epitaxy on monocrystalline (11–20) sapphire substrates. Wedge-shaped samples with different Co thickness gradients relative to the Mo [0 0 1] direction were fabricated. Observation of the domain structure was performed at room temperature using Kerr microscopy in a Co thickness range varying from 5 to 50 nm, where the magnetization is oriented in the plane of the sample. A Co thickness-dependent coercivity field was determined through analysis of the domain wall position during the reversal process. A preferential orientation of magnetic domain walls was found, with the domains being needle-like. The orientation, as well as the size of the needles, depends on the Co thickness and the orientation of the magnetic field applied in the sample plane.     

Maximum entropy production principle in physics,chemistry and biology

The tendency of the entropy to a maximum as an isolated system is relaxed to the equilibrium (the second law of thermodynamics) has been known since the mid-19th century. However, independent theoretical and applied studies, which suggested the maximization of the entropy production during nonequilibrium processes (the so-called maximum entropy production principle, MEPP), appeared in the 20th century. Publications on this topic were fragmented and different research teams, which were concerned with this principle, were unaware of studies performed by other scientists. As a result, the recognition and the use of MEPP by a wider circle of researchers were considerably delayed. The objectives of the present review consist in summation and analysis of studies dealing with MEPP. The first part of the review is concerned with the thermodynamic and statistical basis of the principle (including the relationship of MEPP with the second law of thermodynamics and Prigogine's principle). Various existing applications of the principle to analysis of nonequilibrium systems will be discussed in the second part.