A fractal model for the lightning induced current on a transmission line

This article presents a model of a tortuous lightning channel, and a study of the consequent electromagnetic coupling to a transmission line. We analyse the fractal dimension of the induced current on the line, compared with the fractal dimension of the lightning channel and the impinging electromagnetic field on the line. This comparison confirms our previous studies pointing out that the channel fractal dimension and the electromagnetic field fractal dimension are related (in particular, for typical lightning parameters they are the same). A comparison of simulated fields and line currents with experimental measurements is also attempte

The Conformal Window of deformed CFT's in the planar limit

We discuss in the planar approximation the effect of double-trace deformations on CFT's. We show that this large class of models posses a conformal window describing a non-trivial flow between two fixed points of the renormalization group, and reveal the presence of a resonance which we associate to the remnant of a dilaton pole. As the conformal window shrinks to zero measure the theory undergoes a conformal phase transition separating a symmetric from a nonsymmetric phase. The recently conjectured strongly coupled branch of non-supersymmetric, non-abelian gauge theories with a large number of flavors is analyzed in light of these results, and a model for the strong branch is proposed. Some phenomenological implications in the context of unparticle physics are also emphasized.Comment: 15 pages PRD class, 2 figures, to be published in PR

Evaluation of innovative thermal insulation systems for a sustainable envelope

La memoria presenta i risultati ottenuti su sistemi di isolamento termico per l\u2019involucro edilizio. Si presentano i risultati ottenuti tramite simulazioni informatiche che hanno consentito di verificare e ottimizzare la trasmissione del calore attraverso un sistema sottovuoto in vetro per le facciate trasparenti. Inoltre la possibilit\ue0 offerta dal riciclo del materiale di scarto della potatura dell\u2019Opunthia Ficus Indica (fichi d\u2019india) che,opportunamente trattato ha permesso di ottenere un materiale isolante (Brevetto n. 1402131), in forma di pannello o in grani sfusi, (valori di coibenza termica 0.071\uad0.057 W/mK).The paper presents the results of the research on thermal insulation systems for the building casing. We present the results of computer simulations that have enabled us to verify and optimize the transmission of heat through several innovative insulation systems, such as vacuum solutions for transparent fa\ue7ades, or the possibilities offered by the recycling of waste material of Opunthia Ficus Indica (prickly pear) pruning, which, properly treated, allowed to obtain an insulating material (Patent n. 1402131), in the form of panels or bulk grains (thermal coefficient values 0.0710.057 W/mK)

Durabilit\ue0 del legno lamellare rinforzato: un prodotto innovativo

La ricerca sviluppata nell\u2019ultimo decennio in edilizia si \ue8 orientata sempre pi\uf9 verso quei materiali, cosiddetti ecocompatibili o ecosostenibili, tali da dissipare il meno possibile le risorse naturali. In questo senso il legno, ed in particolare quello lamellare, \ue8 divenuto una valida alternativa alle tecnologie pi\uf9 usuali e tradizionali del cemento armato e del ferro, anche perch\ue9 rappresenta una delle poche materie prime rinnovabili. Il legno lamellare \ue8 un prodotto evoluto, un prodotto industriale che supera i difetti propri del legno massello con caratteristiche di resistenza meccanica e di durabilit\ue0 superiori, cos\uec da poter ottenere qualunque forma e dimensione. Presenta per\uf2 una rigidezza limitata rispetto ad altre tecnologie, aspetto quest\u2019ultimo, che ha determinato un vasto campo di ricerca basato sulla possibilit\ue0 di inserire elementi irrigidenti all\u2019interno della sezione resistente. La memoria presenta i risultati raggiunti nell\u2019ambito di un progetto di innovazione PIA che ha avuto l\u2019obbiettivo di sperimentare un prodotto innovativo che possa avere una maggiore rigidezza, e quindi maggiori prestazioni a parit\ue0 di costi. L\u2019impiego di materiali originali ha richiesto la verifica delle prestazioni attraverso test ciclici di prove integrate di resistenza meccanica e di invecchiamento accelerato che sono state svolte, rispettivamente, dal Dipartimento di Ingegneria Strutturale e Geotecnica e dal Dipartimento di Progetto e Costruzione Edilizia entrambi dell\u2019Universit\ue0 di Palermo. Nel seguito si illustrano le prove di invecchiamento artificiale eseguite per verificare la durabilit\ue0 dei prototipi innovativi da sperimentare

Birds, Ilha Grande, state of Rio de Janeiro, Southeastern Brazil

We provide a list of bird species from our primary surveys and secondary data for an island (Ilha Grande) insoutheastern Brazil. The information derives mainly from primary data collected since 1995, particularly in the oceanicside of the island. The methodologies included capture-mark-recapture studies using mist nets, transects (visual andvocal records) and supplementary observations. Our total species list from primary data is 175 species (127 captured)and 47 species were added from secondary data. This represents 222 species from 58 families. Of this total, 44 areendemic to Atlantic forest and nine are threatened with extinction. Our results are discussed comparing our study areawith another large island included in the Serra do Mar corridor (Ilha de São Sebastião), and also a nearby continentalarea (Paraty). The results indicate the importance of Ilha Grande as a reservoir of bird species of Atlantic forest

PIXE and ToF-SIMS analysis of streaker samplers filters

This paper presents methodological innovations introduced in the characterisation of urban aerosol collected in Italy in a recent campaign. Two complementary ion beam analysis (IBA) techniques were used to analyse Nuclepore filters used in continuous streaker samplers to collect airborne particles in four Italian towns. Na to Pb elemental concentrations were obtained by particle induced X-ray emission (PIXE), while time of flight secondary ion mass spectrometry (ToF-SIMS) produced, on the same samples, time trends for several elements and molecular fragments. In addition, light attenuation measurements were used as a tracer for black carbon. The data produced by these three techniques was merged into a unique data set to address the characterisation of particulate matter sources. Correlations between elemental concentration trends (PIXE) and relative trends for molecular fragments (ToF-SIMS) and black carbon (light attenuation) have been studied by cluster and principal component analysis

Multitrace deformations, Gamow states, and Stability of AdS/CFT

We analyze the effect of multitrace deformations in conformal field theories at leading order in a large N approximation. These theories admit a description in terms of a weakly coupled gravity dual. We show how the deformations can be mapped into boundary terms of the gravity theory and how to reproduce the RG equations found in field theory. In the case of doubletrace deformations, and for bulk scalars with masses in the range $-d^2/4<m^2<-d^2/4+1$, the deformed theory flows between two fixed points of the renormalization group, manifesting a resonant behavior at the scale characterizing the transition between the two CFT's. On the gravity side the resonance is mapped into an IR non-normalizable mode (Gamow state) whose overlap with the UV region increases as the dual operator approaches the free field limit. We argue that this resonant behavior is a generic property of large N theories in the conformal window, and associate it to a remnant of the Nambu-Goldstone mode of dilatation invariance. We emphasize the role of nonminimal couplings to gravity and establish a stability theorem for scalar/gravity systems with AdS boundary conditions in the presence of arbitrary boundary potentials and nonminimal coupling.Comment: 14 pages, references added, introduction change