Statistical ensemble of scale-free random graphs

A thorough discussion of the statistical ensemble of scale-free connected random tree graphs is presented. Methods borrowed from field theory are used to define the ensemble and to study analytically its properties. The ensemble is characterized by two global parameters, the fractal and the spectral dimensions, which are explicitly calculated. It is discussed in detail how the geometry of the graphs varies when the weights of the nodes are modified. The stability of the scale-free regime is also considered: when it breaks down, either a scale is spontaneously generated or else, a "singular" node appears and the graphs become crumpled. A new computer algorithm to generate these random graphs is proposed. Possible generalizations are also discussed. In particular, more general ensembles are defined along the same lines and the computer algorithm is extended to arbitrary (degenerate) scale-free random graphs.Comment: 10 pages, 6 eps figures, 2-column revtex format, minor correction

Generating and transferring grassroots innovations in a multi-actor participatory process

Peer reviewe

Assessment of chemical hazards in insect meal production for aquaculture feeds

Abstract of communication presented at the 74th EAAP International Congress on Animal Science. Lyon, France, 26 August-1 September 2023N/

Professions, governance and citizenship through the global looking glass

The state-professions relationship and the role of professionalism as facilitator of public sector services are key issues of the professions studies. This makes the study of professions an important source of understanding how to create a “better world,” with more efficient public sectors and accessible services for all citizens. Currently, the relationships between professions and the state face a number of fundamental transformations involving different governance reforms, stakeholders, and professional groups. First, state regulation expands towards “governance” with plural actors and market logics; second, globalization and new economies add new forms of “state” and “citizenship”; and third, austerity politics curb prospering markets and public funding for professional services.info:eu-repo/semantics/publishedVersio

Instantons and Killing spinors

We investigate instantons on manifolds with Killing spinors and their cones. Examples of manifolds with Killing spinors include nearly Kaehler 6-manifolds, nearly parallel G_2-manifolds in dimension 7, Sasaki-Einstein manifolds, and 3-Sasakian manifolds. We construct a connection on the tangent bundle over these manifolds which solves the instanton equation, and also show that the instanton equation implies the Yang-Mills equation, despite the presence of torsion. We then construct instantons on the cones over these manifolds, and lift them to solutions of heterotic supergravity. Amongst our solutions are new instantons on even-dimensional Euclidean spaces, as well as the well-known BPST, quaternionic and octonionic instantons.Comment: 40 pages, 2 figures v2: author email addresses and affiliations adde

Whole-genome analysis uncovers loss of blaZ associated with carriage isolates belonging to methicillin-resistant Staphylococcus aureus (MRSA) clone ST5-VI in Cape Verde

Objectives: Surveillance studies for Staphylococcus aureus carriage are a primary tool to survey the prevalence of methicillin-resistant S. aureus (MRSA) in the general population, patients and healthcare workers. We have previously reported S. aureus carriage in various African countries, including Cape Verde. Methods: Whole-genome sequences of 106 S. aureus isolates from Cape Verde were determined. Results: Staphylococcus aureus carriage isolates in Cape Verde show high genetic variability, with the detection of 27 sequence types (STs) and three primary genetic clusters associated with ST152, ST15 and ST5. One transmission event with less than eight core-genome single nucleotide polymorphisms (cgSNP) differences was detected among the ST5-VI MRSA lineage. Genetic analysis confirmed the phenotypic resistance and allowed the identification of six independent events of plasmid or transposon loss associated with the deletion of blaZ in nine isolates. In the four ST5 MRSA isolates, loss of the blaZ plasmid coincided with the acquisition of SCCmec type VI and an unusual penicillin phenotype with a minimum inhibitory concentration (MIC) at the breakpoint, indicating an adaptation trend in this endemic lineage. Similar events of blaZ plasmid loss, with concomitant acquisition SCCmec elements, were detected among ST5 isolates from different geographical origins. Conclusion: Overall, the genome data allowed to place isolates in a phylogenetic context and to identify different blaZ gene deletions associated with plasmid or transposon loss. Genomic analysis unveiled adaptation and evolution trends, namely among emerging MRSA lineages in the country, which deserve additional consideration in the design of future infection control protocols

Radial velocity eclipse mapping of exoplanets

Planetary rotation rates and obliquities provide information regarding the history of planet formation, but have not yet been measured for evolved extrasolar planets. Here we investigate the theoretical and observational perspective of the Rossiter-McLauglin effect during secondary eclipse (RMse) ingress and egress for transiting exoplanets. Near secondary eclipse, when the planet passes behind the parent star, the star sequentially obscures light from the approaching and receding parts of the rotating planetary surface. The temporal block of light emerging from the approaching (blue-shifted) or receding (red-shifted) parts of the planet causes a temporal distortion in the planet's spectral line profiles resulting in an anomaly in the planet's radial velocity curve. We demonstrate that the shape and the ratio of the ingress-to-egress radial velocity amplitudes depends on the planetary rotational rate, axial tilt and impact factor (i.e. sky-projected planet spin-orbital alignment). In addition, line asymmetries originating from different layers in the atmosphere of the planet could provide information regarding zonal atmospheric winds and constraints on the hot spot shape for giant irradiated exoplanets. The effect is expected to be most-pronounced at near-infrared wavelengths, where the planet-to-star contrasts are large. We create synthetic near-infrared, high-dispersion spectroscopic data and demonstrate how the sky-projected spin axis orientation and equatorial velocity of the planet can be estimated. We conclude that the RMse effect could be a powerful method to measure exoplanet spins.Comment: 7 pages, 3 figures, 1 table, accepted for publication in ApJ on 2015 June 1

On a class of 4D Kahler bases and AdS_5 supersymmetric Black Holes

We construct a class of toric Kahler manifolds, M_4, of real dimension four, a subset of which corresponds to the Kahler bases of all known 5D asymptotically AdS_5 supersymmetric black-holes. In a certain limit, these Kahler spaces take the form of cones over Sasaki spaces, which, in turn, are fibrations over toric manifolds of real dimension two. The metric on M_4 is completely determined by a single function H(x), which is the conformal factor of the two dimensional space. We study the solutions of minimal five dimensional gauged supergravity having this class of Kahler spaces as base and show that in order to generate a five dimensional solution H(x) must obey a simple sixth order differential equation. We discuss the solutions in detail, which include all known asymptotically AdS_5 black holes as well as other spacetimes with non-compact horizons. Moreover we find an infinite number of supersymmetric deformations of these spacetimes with less spatial isometries than the base space. These deformations vanish at the horizon, but become relevant asymptotically.Comment: 34 pages, 3 figures. v2: formula (8.35) and other minor typos corrected; references added; accepted for publication in JHE

Amazonian plant crude extract screening for activity against multidrug-resistant bacteria.

Antimicrobial resistance is a subject of great concern in public health and also in the designing of strategies for current therapeutic protocols all over the world. New drugs, including those necessary for a reserve armamentarium and exhibiting less side effects deserve special attention. In rural areas, particularly in Brazil, a huge number of natural products, in different artisanal preparations, mainly from plants, have been used by traditional populations to cure diseases. Despite some of these plants have been studied, many of them are awaiting to have their compounds chemically characterized and investigated their pharmacodynamics properties. Further, as well known, the environment plays a crucial role in the metabolism of these plants, yielding different and varied molecular complexes depending on the period of collection, climate conditions, kind of soil and also the plant speciation. In this report, ethanol crude extract of 10 different botanical specimens from the Amazon region of Brazil, in the Amapa State, were screened for antibacterial activity of 7 clinical resistant microorganisms utilizing as control ATCC bacterial species by the Kirby-Bauer method. Plant extracts of Geissospermum argenteum, Uncaria guianensis, Brosimum acutifolium, Copaifera reticulate, Licania macrophylla, Ptycopetalum olacoides and Dalbergia subcymosa yielded activity against Staphylococcus aureus and Pseudomonas aeruginosa, both multidrug resistant, and Staphylococcus aureus ATCC strain.Disponivel também on line