Elementi strutturali in calcestruzzo armati con barre in GFRP

Sono riportati alcuni risultati sperimentali, ottenuti dagli autori, riguardanti: - caratterizzazione meccanica a trazione di barre GFRP, anche di elevato diametro; - valutazione dell’aderenza tra barre in GFRP e calcestruzzo; - vita a fatica di solette da ponte rinforzati con barre in GFRP; - comportamento statico di elementi in calcestruzzo rinforzati con barre in GFRP soggetti ad elevate variazioni di temperatura

Comparison between a diagrammatic theory for the BCS-BEC crossover and Quantum Monte Carlo results

Predictions for the chemical potential and the excitation gap recently obtained by our diagrammatic theory for the BCS-BEC crossover in the superfluid phase are compared with novel Quantum Monte Carlo results at zero temperature now available in the literature. A remarkable agreement is found between the results obtained by the two approachesComment: 3 pages, 2 figure

Critical current throughout the BCS-BEC crossover with the inclusion of pairing fluctuations

The present work aims at providing a systematic analysis of the current density versus momentum characteristics for a fermionic superfluid throughout the BCS-BEC crossover, even in the fully homogeneous case. At low temperatures, where pairing fluctuations are not strong enough to invalidate a quasiparticle approach, a sharp threshold for the inception of a back-flow current is found, which sets the onset of dissipation and identifies the critical momentum according to Landau. This momentum is seen to smoothly evolve from the BCS to the BEC regimes, whereby a single expression for the single-particle current density that includes pairing fluctuations enables us to incorporate on equal footing two quite distinct dissipative mechanisms, namely, pair breaking and phonon excitations in the two sides of the BCS-BEC crossover, respectively. At finite temperature, where thermal fluctuations broaden the excitation spectrum and make the dissipative (kinetic and thermal) mechanisms intertwined with each other, an alternative criterion due to Bardeen is instead employed to signal the loss of superfluid behavior. In this way, detailed comparison with available experimental data in linear and annular geometries is significantly improved with respect to previous approaches, thereby demonstrating the crucial role played by quantum fluctuations in renormalizing the single-particle excitation spectrum

On the thermal and double episode emissions in GRB 970828

Following the recent theoretical interpretation of GRB 090618 and GRB 101023, we here interpret GRB 970828 in terms of a double episode emission: the first episode, observed in the first 40 s of the emission, is interpreted as the proto-black-hole emission; the second episode, observed after t$_0$+50 s, as a canonical gamma ray burst. The transition between the two episodes marks the black hole formation. The characteristics of the real GRB, in the second episode, are an energy of $E_{tot}^{e^+e^-} = 1.60 \times 10^{53}$ erg, a baryon load of $B = 7 \times 10^{-3}$ and a bulk Lorentz factor at transparency of $\Gamma = 142.5$. The clear analogy with GRB 090618 would require also in GRB 970828 the presence of a possible supernova. We also infer that the GRB exploded in an environment with a large average particle density $\, \approx 10^3$ part/cm$^3$ and dense clouds characterized by typical dimensions of $(4 - 8) \times 10^{14}$ cm and $\delta n/n \propto 10$. Such an environment is in line with the observed large column density absorption, which might have darkened both the supernova emission and the GRB optical afterglow.Comment: 7 pages, 10 figures, submitted to Ap

A common behavior in the late X-ray afterglow of energetic GRB-SN systems

The possibility to divide GRBs in different subclasses allow to understand better the physics underlying their emission mechanisms and progenitors. The induced gravitational collapse scenario proposes a binary progenitor to explain the time-sequence in GRBs-SNe. We show the existence of a common behavior of the late decay of the X-ray afterglow emission of this subclass of GRBs, pointing to a common physical mechanism of their late emission, consistent with the IGC picture.Comment: 3 pages, to appear in the proceedings of the Gamma-Ray Burst Symposium 2012 - IAA-CSIC - Marbella, editors: Castro-Tirado, A. J., Gorosabel, J. and Park, I.

Effectiveness of extracorporeal shock wave therapy in bone marrow edema syndrome of the hip

There is no gold standard for treatment of bone marrow edema syndrome of the hip (BMESH). Usually, treatment is conservative, owing to the favorable and self-limiting prognosis. In musculoskeletal disorders, the effectiveness of extracorporeal shock wave therapy (ESWT) has been widely recognized and recent research supports its use in the treatment of the first stages of avascular osteonecrosis of the proximal femur and in other conditions where bone marrow edema is present. On this basis, we performed a prospective study to evaluate the effectiveness of ESWT in normalizing the symptoms and imaging features of BMESH. Twenty consecutive symptomatic patients underwent two treatments of high-energy ESWT and were followed-up at 2, 3 and 6 months, with a final clinical follow-up at mean 15.52 +/- A 1.91 months. Patients underwent magnetic resonance imaging of the hip and were evaluated according to the Harris hip score. The mean improvement in HHS over the course of the study was of 58.5 +/- A 14.9 points (p < 0.0001), and the mean edema area reduced from 981.9 +/- A 453.2 mm(2) pre-treatment to 107.8 +/- A 248.1 mm(2) at 6 months. ESWT seems to be a powerful, non-pharmacological tool that produces rapid pain relief and functional improvement and aids the normalization of the vascular and metabolic impairments which characterize BMESH

Renormalization on noncommutative torus

We study a self-interacting scalar φ4 theory on the d-dimensional noncommutative torus. We determine, for the particular cases d= 2 and d= 4 , the counterterms required by one-loop renormalization. We discuss higher loops in two dimensions and two-loop contributions to the self-energy in four dimensions. Our analysis points toward the absence of any problems related to the ultraviolet/infrared mixing and thus to renormalizability of the theory. However, we find another potentially troubling phenomenon which is a wild behavior of the two-point amplitude as a function of the noncommutativity matrix θ.Instituto de Física La Plat

GRB 081024B and GRB 140402A: two additional short GRBs from binary neutron star mergers

Theoretical and observational evidences have been recently gained for a two-fold classification of short bursts: 1) short gamma-ray flashes (S-GRFs), with isotropic energy $E_{iso}<10^{52}$~erg and no BH formation, and 2) the authentic short gamma-ray bursts (S-GRBs), with isotropic energy $E_{iso}>10^{52}$~erg evidencing a BH formation in the binary neutron star merging process. The signature for the BH formation consists in the on-set of the high energy ($0.1$--$100$~GeV) emission, coeval to the prompt emission, in all S-GRBs. No GeV emission is expected nor observed in the S-GRFs. In this paper we present two additional S-GRBs, GRB 081024B and GRB 140402A, following the already identified S-GRBs, i.e., GRB 090227B, GRB 090510 and GRB 140619B. We also return on the absence of the GeV emission of the S-GRB 090227B, at an angle of $71^{\rm{o}}$ from the \textit{Fermi}-LAT boresight. All the correctly identified S-GRBs correlate to the high energy emission, implying no significant presence of beaming in the GeV emission. The existence of a common power-law behavior in the GeV luminosities, following the BH formation, when measured in the source rest-frame, points to a commonality in the mass and spin of the newly-formed BH in all S-GRBs.Comment: 16 pages, submitted to ApJ, second version addressing the comments by the refere