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

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

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

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

Reliability of Mainstream Tablets for 2D Analysis of a Drop Jump Landing

Please refer to the pdf version of the abstract located adjacent to the title

Devices for Screening and Monitoring of Tumors Based on Chemoresistive Sensors

Abstract In this work two devices are presented, named SCENT A1 (A1) and SCENT B1 (B1), composed of chemoresistive sensors. Such devices are capable of discriminating the different compositions of gas mixtures emitted by stools, for colorectal cancer screening (A1), and by blood, for tumors monitoring (B1), according to defined sampling protocols. Results have been acquired by a LabView® software and statistically treated (e.g. quadratic discriminant analysis, QDA) and show to be encouraging with an error of 5% for SCENT A1. Preliminary results of SCENT B1 proved to be promising. Further studies will be carried out for clinically validating the two devices

An ultrashort pulse ultra-violet radiation undulator source driven by a laser plasma wakefield accelerator

Narrow band undulator radiation tuneable over the wavelength range of 150–260 nm has been produced by short electron bunches from a 2 mm long laser plasma wakefield accelerator based on a 20 TW femtosecond laser system. The number of photons measured is up to 9 × 106 per shot for a 100 period undulator, with a mean peak brilliance of 1 × 1018 photons/s/mrad2/mm2/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has energy of 120–130 MeV with the radiation pulse duration in the range of 50–100 fs

Pancreaticoduodenal Artery Aneurysm Ruptured into Duodenum, Associated with Celiac Trunk Stenosis. Case Report and Review of Literature

Pancreaticoduodenal artery (PDA) aneurysm associated with a celiac artery (CA) occlusion or stenosis is an uncommon event. We report the case of a 63-years old man who presented with acute abdominal pain radiating to the back. During the hospital stay, the patient had an episode of severe hematemesis. He had a gastroscopy and then a surgical exploration. However only with arteriography we found a PDA, which had ruptured into duodenum. The aneurysm was associated with a stenosis of the celiac trunk and was supplied by a dense network of collateral vessels from the SMA. The patient was successfully treated with embolization and was discharged on the 64th postoperative day. Short term and mid term follow-up was uneventful. This case shows the difficulty in diagnosing these rare events in time, indicating that angiography is indispensable to establish a diagnosis and enable nonsurgical treatment