Approximate analytical calculations of photon geodesics in the Schwarzschild metric

We develop a method for deriving approximate analytical formulae to integrate photon geodesics in a Schwarzschild spacetime. Based on this, we derive the approximate equations for light bending and propagation delay that have been introduced empirically. We then derive for the first time an approximate analytical equation for the solid angle. We discuss the accuracy and range of applicability of the new equations and present a few simple applications of them to known astrophysical problems.Comment: 8 pages, 10 Figures; Received: 08 June 2016 / Accepted: 04 August 2016and accepted from A&

A double nellix and chimney covered stents: challenging treatment of pararenal aortic aneurysm

A 77-year-old male patient presented with a symptomatic, 66-mm pararenal aortic aneurysm. The patient was classified as unsuitable for open surgery due to significant comorbidities. Fenestrated or branched endografts were contraindicated due to the poor iliac access (6 mm diameter). A double Nellix with chimney endovascular aneurysm sealing (ChEVAS) technique was selected to exclude the pararenal aortic aneurysm and to preserve renal arteries and the superior mesenteric artery. Technical preplanning considered the ideal proximal landing zone to be close to the origin of the almost occluded celiac trunk and the distal common iliac arteries as the ideal distal landing zone. The total length of the aorta to cover was estimated as >180 mm, requiring 2 aortic EVAS systems, bilaterally overlapped. Technical success was achieved, and the patient was discharged on postoperative day 8 in good general condition. Successful aneurysm exclusion and target vessel patency without endoleak or stent-graft kinking or migration were confirmed at angio-computed tomography at 6 months

Neutron Star Radius-to-mass Ratio from Partial Accretion Disc Occultation as Measured through Fe Kα\alpha Line Profiles

We present a new method to measure the radius-to-mass ratio (R/M) of weakly magnetic, disc-accreting neutron stars by exploiting the occultation of parts of the inner disc by the star itself. This occultation imprints characteristic features on the X-ray line profile that are unique and are expected to be present in low mass X-ray binary systems seen under inclinations higher than ~65 degrees. We analyse a NuSTAR observation of a good candidate system, 4U 1636-53, and find that X-ray spectra from current instrumentation are unlikely to single out the occultation features owing to insufficient signal-to-noise. Based on an extensive set of simulations we show that large-area X-ray detectors of the future generation could measure R/M to ~2{\div}3% precision over a range of inclinations. Such is the precision in radius determination required to derive tight constraints on the equation of state of ultradense matter and it represents the goal that other methods too aim to achieve in the future.Comment: 17 pages, 8 figures; this is a pre-print edition of an article that has been accepted for publication in the Astrophysical Journa

Tension pneumomediastinum in patients with COVID-19

open5nonot presentopenCampisi A.; Poletti V.; Ciarrocchi A.P.; Salvi M.; Stella F.Campisi A.; Poletti V.; Ciarrocchi A.P.; Salvi M.; Stella F

Rupture of Splenic Artery Aneurysm in Patient with ACTN2 Mutation

Here, we report a case of splenic artery aneurysm rupture in a patient with known heterozygosity mutation of the ACTN2 gene (variant c.971G > A p.Arg324Gln). The patient came to our emergency department with epigastric pain radiating to the lumbar area, with an absence of peritonism signs. An abdominal computed tomography angiography showed a ruptured huge (5 cm) splenic artery aneurysm. Therefore, the patient underwent emergency endovascular coil embolization with complete aneurysm exclusion. The postoperative course was uneventful, until postoperative day five when the patient developed a symptomatic supraventricular tachycardia in the absence of echocardiographic alterations. The signs and symptoms disappeared after three days of medical management. The patient was discharged on the 14th postoperative day in good clinical condition under verapamil and anti-platelet therapy. Although ACTN2 mutation was associated with cardiac and peripheral vascular disease occurrence, to the best of our knowledge, the present case is the first report of a visceral (splenic) aneurysm directly linked with this rare mutation

Double-inlet single left ventricle: Echocardiographic anatomy with emphasis on the morphology of the atrioventricular valves and ventricular septal defect

AbstractThe echocardiographic anatomy of double inlet single left ventricle was studied in 57 patients, aged 1 day to 27 years (mean 6 years); the variables examined included morphology, size and function of the atrioventricular AV) valves and ventricular septal defect and their relation to pulmonary stenosis, aortic stenosis and aortic arch obstruction. The visceroatrial situs was solitus and the heart was in the left side of the chest in all 57 patients. A d-loop ventricle was present in 21 patients and an l-loop ventricle in 36. The great arteries were normally related (Holmes heart) in 8 patients and transposed in 49.In all hearts, the right AV valve was anterior to the left AV valve. In 53 patients, the tricuspid valve (right valve in d-loop and left valve in l-loop) was closer to and had attachments on the septum. The tricuspid valve straddled the outflow chamber in eight patients. No significant difference was noted in the mean AV valve diameter when comparing mitral and tricuspid valves within the same group or between the groups with a d- or l-loop ventricle. The right AV valve diameter had a significant direct correlation with the aortic valve diameter and the size or (he ventricular septal defect regardless of ventricular loop. Both AV valves were functionally normal in 34 patients. Among patients with AV valve dysfunction, the tricuspid valve tended to be stenotic in patients with an l-loop ventricle and regurgitant in patients with a d-loop ventricle. Mitral valve dysfunction was uncommon.The ventricular septal defect (46 patients) was separated from the semilunar valves in 24 patients (muscular defect) and adjacent to the anterior semilunar valve as a result of hypoplasia or malalignment, or both, of the infundibular septum (subaortic defect) in 19 patients. Multiple defects were present in three patients. The difect was unrestrictive in 26 patients, restrictive in 23 and could not be evaluated in 8. Pulmonary artery banding had been performed in 8 of the 26 patients with an unrestrictive defect and in 10 of the 23 patients with a restrictive defect. Only 4 of 19 subaortic defects compared with 16 of 24 muscular defects were restrictive. The size of the defect was significantly correlated with the measured pressure gradient. Among patients with transposition, only 2 of 13 with pulmonary stenosis had a restrictive ventricular septal defect compared with 15 of 30 without pulmonary stenosis. In patients with transposition, the defect size was significantly smaller when coarctation was present

Citrate Anticoagulation for Continuous Renal Replacement Therapy in Critically Ill Patients: Success and Limits

Citrate anticoagulation has risen in interest so it is now a real alternative to heparin in the ICUs practice. Citrate provides a regional anticoagulation virtually restricted to extracorporeal circuit, where it acts by chelating ionized calcium. This issue is particularly true in patients ongoing CRRT, when the “continuous” systemic anticoagulation treatment is per se a relevant risk of bleeding. When compared with heparin most of studies with citrate reported a longer circuit survival, a lower rate of bleeding complications, and transfused packed red cell requirements. As anticoagulant for CRRT, the infusion of citrate is prolonged and it could potentially have some adverse effects. When citrate is metabolized to bicarbonate, metabolic alkalosis may occur, or for impaired metabolism citrate accumulation leads to acidosis. However, large studies with dedicated machines have indeed demonstrated that citrate anticoagulation is well tolerated, safe, and an easy to handle even in septic shock critically ill patients

The three-dimensional general relativistic Poynting-Robertson effect I: radial radiation field

In this paper we investigate the three-dimensional (3D) motion of a test particle in a stationary, axially symmetric spacetime around a central compact object, under the influence of a radiation field. To this aim we extend the two-dimensional (2D) version of the Poynting-Robertson effect in General Relativity (GR) that was developed in previous studies. The radiation flux is modeled by photons which travel along null geodesics in the 3D space of a Kerr background and are purely radial with respect to the zero angular momentum observer (ZAMO) frames. The 3D general relativistic equations of motion that we derive are consistent with the classical (i.e. non-GR) description of the Poynting-Robertson effect in 3D. The resulting dynamical system admits a critical hypersurface, on which radiation force balances gravity. Selected test particle orbits are calculated and displayed, and their properties described. It is found that test particles approaching the critical hypersurface at a finite latitude and with non-zero angular moment are subject to a latitudinal drift and asymptotically reach a circular orbit on the equator of the critical hypersurface, where they remain at rest with respect to the ZAMO. On the contrary, test particles that have lost all their angular momentum by the time they reach the critical hypersurface do not experience this latitudinal drift and stay at rest with respects to the ZAMO at fixed non-zero latitude.Comment: 17 pages, 19 figures, accepted for publication on Physical Review D the 3rd of January 201

Synchronous Lung Cancers: When Same Histological Types Feature Different Molecular Profiles and Response Phenotypes

We discuss the case of synchronous bilateral lung cancers which feature the same histological phenotype and a different EGFR mutational profile. Both histological and molecular characterizations were performed on specimens derived thorough CT-guided fine needle aspiration. A first-line chemotherapy was unsuccessful. Subsequent objective response to the EGFR inhibitor Erlotinib was clearly coherent with the sequencing data and the mutated nodule was effectively reduced (> 50%) after therapy, while the lesion assessed as EGFR wild type featured a slight response. This report has two relevant implications. It points out that in case of multiple malignant lesions at time of diagnosis, molecular profiling should be as extensive as possible and it might contribute to clarify the association between the lesions found. Besides the molecular analysis on cytology specimens could identify an accurate and safe diagnostic approach for clinical use