Gravitational wave recoils in non-axisymmetric Robinson-Trautman spacetimes

We examine the gravitational wave recoil waves and the associated net kick velocities in non-axisymmetric Robinson-Trautman spacetimes. We use characteristic initial data for the dynamics corresponding to non-head-on collisions of black holes. We make a parameter study of the kick distributions, corresponding to an extended range of the incidence angle $\rho_0$ in the initial data. For the range of $\rho_0$ examined ($3^{\circ} \leq \rho_0 \leq 110^{\circ}$) the kick distributions as a function of the symmetric mass parameter $\eta$ satisfy a law obtained from an empirical modification of the Fitchett law, with a parameter $C$ that accounts for the non-zero net gravitational momentum wave fluxes for the equal mass case. The law fits accurately the kick distributions for the range of $\rho_0$ examined, with a rms normalized error of the order of $5 \%$. For the equal mass case the nonzero net gravitational wave momentum flux increases as $\rho_0$ increases, up to $\rho_0 \simeq 55^{\circ}$ beyond which it decreases. The maximum net kick velocity is about $190 {\rm km/s}$ for for the boost parameter considered. For $\rho_0 \geq 50^{\circ}$ the distribution is a monotonous function of $\eta$. The angular patterns of the gravitational waves emitted are examined. Our analysis includes the two polarization modes present in wave zone curvature.Comment: 10 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1403.4581, arXiv:1202.1271, arXiv:1111.122

Early diagnosis of pancreatic cancer: What strategies to avoid a foretold catastrophe

While great strides in improving survival rates have been made for most cancers in recent years, pancreatic ductal adenocarcinoma (PDAC) remains one of the solid tumors with the worst prognosis. PDAC mortality often overlaps with incidence. Surgical resection is the only potentially curative treatment, but it can be performed in a very limited number of cases. In order to improve the prognosis of PDAC, there are ideally two possible ways: the discovery of new strategies or drugs that will make it possible to treat the tumor more successfully or an earlier diagnosis that will allow patients to be operated on at a less advanced stage. The aim of this review was to summarize all the possible strategies available today for the early diagnosis of PDAC and the paths that research needs to take to make this goal ever closer. All the most recent studies on risk factors and screening modalities, new laboratory tests including liquid biopsy, new imaging methods and possible applications of artificial intelligence and machine learning were reviewed and commented on. Unfortunately, in 2022 the results for this type of cancer still remain discouraging, while a catastrophic increase in cases is expected in the coming years. The article was also written with the aim of highlighting the urgency of devoting more attention and resources to this pathology in order to reach a solution that seems more and more unreachable every day

Emergency endoscopy during the SARS-CoV-2 pandemic in the north of Italy. Experience from St. Orsola University Hospital—Bologna

No abstract availabl

Effect of antithrombotic therapy on postoperative outcome of 538 consecutive emergency laparoscopic cholecystectomies for acute cholecystitis. Two Italian center’s study

The risk of developing hemorrhagic complications during or after emergency cholecystectomy (EC) for acute cholecystitis (AC) in patients with antithrombotic therapy (ATT) remains uncertain. In this double-center study, we evaluated post-operative outcomes in patients with ATT undergoing EC. We retrospectively evaluated 538 patients who underwent laparoscopic EC for AC between May 2015 and December 2019 at two referral centers. 89 of them (17%) were on ATT. We defined postoperative complication rates, including bleeding, as our primary outcome. Mortality was higher in the ATT group. Morbidity was higher in the ATT group as well; however, the difference was not statistically significant. 12 patients (2%) experienced intraoperative blood loss over 500 ml and ten (2%) had postoperative bleeding complications. Two patients (< 1%) experienced both intraoperative and postoperative bleeding. On multivariate analysis, ATT was not significantly associated with worse postoperative outcomes. Antithrombotic therapy is not an independently associated factor of severe postoperative complications (including bleeding) or mortality. However, these patients still represent a challenging group and must be carefully managed to avoid postoperative bleeding complications

The low dimensional dynamical system approach in General Relativity: an example

In this paper we explore one of the most important features of the Galerkin method, which is to achieve high accuracy with a relatively modest computational effort, in the dynamics of Robinson-Trautman spacetimes.Comment: 7 pages, 5 figure

New magnetron configurations for sputtered Nb onto Cu

Abstract Niobium sputtered film microstructure and morphology and consequently its superconducting properties, strongly depend on target-substrate deposition angle. In order to improve the Nb film quality for 1.5 GHz cavity coatings, we investigated the application of three main ideas to the sputtering process: (i) making niobium atoms impinging perpendicularly the substrate surface, (ii) promoting the effect of plasma bombardment of the growing film, and (iii) increasing the sputtering rate. Therefore, several different sputtering configurations are under development. The effect of Nb atoms arriving perpendicular to the substrate is explored either by using a cathode that follows the cavity shape or by increasing the plasma confinement efficiency by means of a target parallel to the magnetic field lines. The removal of adsorbed impurities from the film surface and the increase of the film density are investigated by a biased third electrode that promotes the positive ions bombardment of the growing film. A mixed bias-magnetron has been built using a positively charged metal grid positioned all around the cathode