Nonextensive Pesin identity. Exact renormalization group analytical results for the dynamics at the edge of chaos of the logistic map

We show that the dynamical and entropic properties at the chaos threshold of the logistic map are naturally linked through the nonextensive expressions for the sensitivity to initial conditions and for the entropy. We corroborate analytically, with the use of the Feigenbaum renormalization group(RG) transformation, the equality between the generalized Lyapunov coefficient $\lambda_{q}$ and the rate of entropy production $K_{q}$ given by the nonextensive statistical mechanics. Our results advocate the validity of the $q$-generalized Pesin identity at critical points of one-dimensional nonlinear dissipative maps.Comment: Revtex, 5 pages, 3 figure

Acceleration with Self-Injection for an All-Optical Radiation Source at LNF

We discuss a new compact gamma-ray source aiming at high spectral density, up to two orders of magnitude higher than currently available bremsstrahlung sources, and conceptually similar to Compton Sources based on conventional linear accelerators. This new source exploits electron bunches from laser-driven electron acceleration in the so-called self-injection scheme and uses a counter-propagating laser pulse to obtain X and gamma-ray emission via Thomson/Compton scattering. The proposed experimental configuration inherently provides a unique test-bed for studies of fundamental open issues of electrodynamics. In view of this, a preliminary discussion of recent results on self-injection with the FLAME laser is also given.Comment: 8 pages, 10 figures, 44 references - Channeling 2012 conferenc

The First Results for a New Layout of the Stay Cables for Great Span Bridges

AbstractThe air-elastic vibrations of structures induce fluctuating stresses that lead to fatigue damage accumulation and may determine structural failure without exceeding ultimate strength This paper proposes a new layout of stay cables to be used in the construction or the retrofitting of long span bridges, capable of mitigating the air-elastic problems due to environmental vibrations such as the rain-wind excitations. The structural scheme adopted was derived from the critical conditions in terms of stability obtained by referring to lateral suspension cables stayed bridge with two planes of fan pattern stay cables. The new layout consists in implementing an additional plane of cable stays placed symmetrically just under the deck bridge. The final layout of the cable stays was identified as “duplex”. The numerical investigation was carried out in the frequency domain. The results obtained show a sensible increasing of stiffness, as well as a reduction of the natural period of vibrations. In the analysis the deck was considered as thin and very light. The Duplex layout had, also, permitted to mitigate the wind effects, because the presence of the inferior stay cables simulate the viscous dampers

Late Epiphrenic-Retroperitoneal Fistula of an Esophageal Diverticulum Ten Years after Surgical Excision: Report of the First Case

Background: Esophageal fistula is a rare complication of an epiphrenic diverticulum and represents a difficult diagnostic challenge. In the majority of cases in the English literature, the fistula is secondary to the spontaneous perforation of the epiphrenic diverticulum and in only one case an esophagobronchial fistula occurs after resection of an epiphrenic diverticulum. No case of esophageal fistula communicating with the retroperitoneum tissues was found. Case Report: We present a case of 84 years old male admitted in 2017 in our Hospital for the appearance of epigastralgia and cough with traces of blood to sputum, asthenia and night sweats. Ten years before he underwent to a hiatal hernia plastic sec. Nissen and subsequently was reoperated for exeresis of diverticulum of the distal third of the esophagus by thoracotomy. In August 2008, because of esophageal substenosis an operation of posterior gastropexy sec. Hill with the demolition of the previous hiatoplasty was performed. In 2017, a computerized tomography shows a voluminous abscess in the right paravertebral region with development along the muscular plane of the ipsilateral psoas and a fistular path of about 4 cm between the posterior wall of the esophagus and the retroperitoneal collection of the abdomen. Conclusions: Esophageal fistula represents a complex problem of epiphrenic diverticulum and rarely a hidden complication of surgery. Surgery is the treatment of choice in suitable patients

Micro-Fragmented Adipose Tissue: A New Minimally Invasive Method for Treatment of Anal Fistula? A Pilot Study

The treatment of Anal fistula continues to be one of the most challenging clinical problems in anorectal surgery. Many sphincter-preserving procedures for the treatment of anal fistula have been recently introduced with the common goal of minimising the injury to the anal sphincters and preserving optimal function. Micro-fragmented adipose tissue injection associated closure of the internal opening with Lipogems® technique is one of them. The properties of autologous adipose-derived stem cells for regenerating tissues and suppressing inflammatory response must be better investigated on anal fistulae, and studies remain in progress. The aim of the present article is to evaluate the safety and efficacy of autologous, micro-fragmented and minimally manipulated adipose tissue injection associated with closure of the internal opening in promoting anal fistula healing

Pepper-pot emittance measurement of laser-plasma wakefield accelerated electrons

The transverse emittance is an important parameter governing the brightness of an electron beam. Here we present the first pepper-pot measurement of the transverse emittance for a mono-energetic electron beam from a laser-plasma wakefield accelerator, carried out on the Advanced Laser-Plasma High Energy Accelerators towards X-Rays (ALPHA-X) beam line. Mono-energetic electrons are passed through an array of 52 mu m diameter holes in a tungsten mask. The pepper-pot results set an upper limit for the normalised emittance at 5.5 +/- 1 pi mm mrad for an 82 MeV beam

Sensitivity to initial conditions at bifurcations in one-dimensional nonlinear maps: rigorous nonextensive solutions

Using the Feigenbaum renormalization group (RG) transformation we work out exactly the dynamics and the sensitivity to initial conditions for unimodal maps of nonlinearity $\zeta >1$ at both their pitchfork and tangent bifurcations. These functions have the form of $q$-exponentials as proposed in Tsallis' generalization of statistical mechanics. We determine the $q$-indices that characterize these universality classes and perform for the first time the calculation of the $q$-generalized Lyapunov coefficient $\lambda_{q}$. The pitchfork and the left-hand side of the tangent bifurcations display weak insensitivity to initial conditions, while the right-hand side of the tangent bifurcations presents a `super-strong' (faster than exponential) sensitivity to initial conditions. We corroborate our analytical results with {\em a priori} numerical calculations.Comment: latex, 4 figures. Updated references and some general presentation improvements. To appear published in Europhysics Letter

Characterization of self-injected electron beams from LWFA experiments at SPARC_LAB

The plasma-based acceleration is an encouraging technique to overcome the limits of the accelerating gradient in the conventional RF acceleration. A plasma accelerator is able to provide accelerating fields up to hundreds of $GeV/m$, paving the way to accelerate particles to several MeV over a short distance (below the millimetre range). Here the characteristics of preliminary electron beams obtained with the self-injection mechanism produced with the FLAME high-power laser at the SPARC_LAB test facility are shown. In detail, with an energy laser on focus of $1.5\ J$ and a pulse temporal length (FWHM) of $40\ fs$, we obtained an electron plasma density due to laser ionization of about $6 \times 10^{18}\ cm^{-3}$, electron energy up to $350\ MeV$ and beam charge in the range $(50 - 100)\ pC$.Comment: 6 pages, 11 figures, conference EAAC201

Near-threshold electron injection in the laser-plasma wakefield accelerator leading to femtosecond bunches

We gratefully acknowledge the support of the UK EPSRC (grant no. EP/J018171/1), the EU FP7 programmes: the Extreme Light Infrastructure (ELI) project, the Laserlab-Europe (no. 284464), and the EUCARD-2 project (no. 312453).The laser-plasma wakefield accelerator is a compact source of high brightness, ultra-short duration electron bunches. Self-injection occurs when electrons from the background plasma gain sufficient momentum at the back of the bubble-shaped accelerating structure to experience sustained acceleration. The shortest duration and highest brightness electron bunches result from self-injection close to the threshold for injection. Here we show that in this case injection is due to the localized charge density build-up in the sheath crossing region at the rear of the bubble, which has the effect of increasing the accelerating potential to above a critical value. Bunch duration is determined by the dwell time above this critical value, which explains why single or multiple ultra-short electron bunches with little dark current are formed in the first bubble. We confirm experimentally, using coherent optical transition radiation measurements, that single or multiple bunches with femtosecond duration and peak currents of several kiloAmpere, and femtosecond intervals between bunches, emerge from the accelerator.Publisher PDFPeer reviewe