Qualitative Properties of Magnetic Fields in Scalar Field Cosmology

We study the qualitative properties of the class of spatially homogeneous Bianchi VI_o cosmological models containing a perfect fluid with a linear equation of state, a scalar field with an exponential potential and a uniform cosmic magnetic field, using dynamical systems techniques. We find that all models evolve away from an expanding massless scalar field model in which the matter and the magnetic field are negligible dynamically. We also find that for a particular range of parameter values the models evolve towards the usual power-law inflationary model (with no magnetic field) and, furthermore, we conclude that inflation is not fundamentally affected by the presence of a uniform primordial magnetic field. We investigate the physical properties of the Bianchi I magnetic field models in some detail.Comment: 12 pages, 2 figures in REVTeX format. to appear in Phys. Rev.

(An)Isotropic models in scalar and scalar-tensor cosmologies

We study how the constants $G$ and $\Lambda$ may vary in different theoretical models (general relativity with a perfect fluid, scalar cosmological models (\textquotedblleft quintessence\textquotedblright) with and without interacting scalar and matter fields and a scalar-tensor model with a dynamical $\Lambda$) in order to explain some observational results. We apply the program outlined in section II to study three different geometries which generalize the FRW ones, which are Bianchi \textrm{V}, \textrm{VII}$_{0}$ and \textrm{IX}, under the self-similarity hypothesis. We put special emphasis on calculating exact power-law solutions which allow us to compare the different models. In all the studied cases we arrive to the conclusion that the solutions are isotropic and noninflationary while the cosmological constant behaves as a positive decreasing time function (in agreement with the current observations) and the gravitational constant behaves as a growing time function

Magnetism, Critical Fluctuations and Susceptibility Renormalization in Pd

Some of the most popular ways to treat quantum critical materials, that is, materials close to a magnetic instability, are based on the Landau functional. The central quantity of such approaches is the average magnitude of spin fluctuations, which is very difficult to measure experimentally or compute directly from the first principles. We calculate the parameters of the Landau functional for Pd and use these to connect the critical fluctuations beyond the local-density approximation and the band structure.Comment: Replaced with the revised version accepted for publication. References updated, errors corrected, other change

Comparing LDA with pLSI as a Dimensionality Reduction Method in Document Clustering

In this paper, we compare latent Dirichlet allocation (LDA) with probabilistic latent semantic indexing (pLSI) as a dimensionality reduction method and investigate their effectiveness in document clustering by using real-world document sets. For clustering of documents, we use a method based on multinomial mixture, which is known as an efficient framework for text mining. Clustering results are evaluated by F-measure, i.e., harmonic mean of precision and recall. We use Japanese and Korean Web articles for evaluation and regard the category assigned to each Web article as the ground truth for the evaluation of clustering results. Our experiment shows that the dimensionality reduction via LDA and pLSI results in document clusters of almost the same quality as those obtained by using original feature vectors. Therefore, we can reduce the vector dimension without degrading cluster quality. Further, both LDA and pLSI are more effective than random projection, the baseline method in our experiment. However, our experiment provides no meaningful difference between LDA and pLSI. This result suggests that LDA does not replace pLSI at least for dimensionality reduction in document clustering.The original publication is available at www.springerlink.comLarge-scale Knowledge Resources: Construction and Application - Third International Conference on Large-scale Knowledge Resources, Lkr 2008, Tokyo, Japan, March 3-5, 2008, Proceeding

Thermostatistics of deformed bosons and fermions

Based on the q-deformed oscillator algebra, we study the behavior of the mean occupation number and its analogies with intermediate statistics and we obtain an expression in terms of an infinite continued fraction, thus clarifying successive approximations. In this framework, we study the thermostatistics of q-deformed bosons and fermions and show that thermodynamics can be built on the formalism of q-calculus. The entire structure of thermodynamics is preserved if ordinary derivatives are replaced by the use of an appropriate Jackson derivative and q-integral. Moreover, we derive the most important thermodynamic functions and we study the q-boson and q-fermion ideal gas in the thermodynamic limit.Comment: 14 pages, 2 figure

Flux Phase as a Dynamic Jahn-Teller Phase: Berryonic Matter in the Cuprates?

There is considerable evidence for some form of charge ordering on the hole-doped stripes in the cuprates, mainly associated with the low-temperature tetragonal phase, but with some evidence for either charge density waves or a flux phase, which is a form of dynamic charge-density wave. These three states form a pseudospin triplet, demonstrating a close connection with the E X e dynamic Jahn-Teller effect, suggesting that the cuprates constitute a form of Berryonic matter. This in turn suggests a new model for the dynamic Jahn-Teller effect as a form of flux phase. A simple model of the Cu-O bond stretching phonons allows an estimate of electron-phonon coupling for these modes, explaining why the half breathing mode softens so much more than the full oxygen breathing mode. The anomalous properties of $O^{2-}$ provide a coupling (correlated hopping) which acts to stabilize density wave phases.Comment: Major Revisions: includes comparisons with specific cuprate phonon modes, 16 eps figures, revte

Enabling an Equitable Energy Transition Through Inclusive Research

Comprehensive and meaningful inclusion of marginalized communities within the research enterprise will be critical to ensuring an equitable, technology-informed, clean energy transition. We provide five key action items for government agencies and philanthropic institutions to operationalize the commitment to an equitable energy transition

Motivation and Knowledge Sharing through Social Media within Danish Organizations

Part 3: Creating Value through ApplicationsInternational audienceBased on an empirical quantitative study, this article investigates employee motivation in Danish companies and aims at determining which factors affect employees’ knowledge sharing through social media in a working environment. Our findings pinpoint towards the potential social media have for enhancing internal communication, knowledge sharing and collaboration in organizations, but the adoption is low, at this point, due to mainly organizational and individual factors. Technological factors do not seem to affect employees’ motivation for knowledge sharing as much as previous research has found, but it is the influence from the combination of individual and organizational factors, which affect the adoption of the platforms. A key finding in the study is that knowledge sharing is not a ‘social dilemma’ as previous studies have found. The study shows a positive development in employees’ willingness to share knowledge, because knowledge sharing is considered more beneficial than to hoard it

Photocatalytic fabrics based on reduced graphene oxide and TiO2 coatings

Supplementary data associated with this article can be found, in the online version, at: http://dx.doi.org/10.1016/j.mseb.2015.04.013The purpose of this work is to obtain photocatalytic fabrics based on reduced graphene oxide (RGO) and TiO2 coatings on polyester fabrics. The influence of the applied number of RGO coatings on properties such as light absorption, conductivity, electroactivity and photocatalytic properties of the fabrics was established. An improvement of these properties with the number of RGO coatings applied was obtained. FESEM, EDX, XPS and FTIR-ATR showed the incorporation of the TiO2 nanoparticles on the fabrics. FTIR-ATR showed the formation of a bidentate carboxylic ligand with titanium atoms. The photocatalytic properties of the fabrics were tested with Rhodamine B dye solutions. Photocatalytic efficiency increased with the number of RGO coatings, due to the increased light absorption, and better electrical properties. The charge transfer resistance (Rct) and its time constant (τ) decreased, indicating a better electron transfer which helps to increase the lifetime of the pair electron/hole.Authors wish to thank to the Spanish Ministerio de Ciencia e Innovación (contract CTM2011-23583) for the financial sup port. J. Molina is grateful to the Conselleria d’Educació, Formació i Ocupació (Generalitat Valenciana) for the Programa VALi+D Postdoctoral Fellowship. Electron Microscopy Service of the UPV (Universitat Politècnica de València) is gratefully acknowledged for help with FESEM and EDX characterization. Timothy Vickers is gratefully acknowledged for help with English revision.info:eu-repo/semantics/publishedVersio

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters