787 research outputs found
Notes on the Personal Archive: A Response to Giorgia Piffaretti
No full textAs a response to Giorgia Piffaretti, Floris Paalman elaborates on her model of the newsstand in relationship to personal archives and archival value
Notes on the Personal Archive: A Response to Giorgia Piffaretti
No full textAs a response to Giorgia Piffaretti, Floris Paalman elaborates on her model of the newsstand in relationship to personal archives and archival value
Notes on the Personal Archive: A Response to Giorgia Piffaretti
No full textAs a response to Giorgia Piffaretti, Floris Paalman elaborates on her model of the newsstand in relationship to personal archives and archival value
Notes on the Personal Archive: A Response to Giorgia Piffaretti
No full textAs a response to Giorgia Piffaretti, Floris Paalman elaborates on her model of the newsstand in relationship to personal archives and archival value
Total mass biases in X-ray galaxy clusters
No full textContext: The exploitation of clusters of galaxies as cosmological probes relies on accurate measurements of their total gravitating mass. X-ray observations provide a powerful means of probing the total mass distribution in galaxy clusters, but might be affected by observational biases and rely on simplistic assumptions originating from our limited understanding of the intracluster medium physics.
Aims: This paper is aimed at elucidating the reliability of X-ray total mass estimates in clusters of galaxies by properly disentangling various biases of both observational and physical origin.
Methods: We use N-body/SPH simulation of a large sample of ~100 galaxy clusters and investigate total mass biases by comparing the mass reconstructed adopting an observational-like approach with the true mass in the simulations. X-ray surface brightness and temperature profiles extracted from the simulations are fitted with different models and adopting different radial fitting ranges in order to investigate modeling and extrapolation biases. Different theoretical definitions of gas temperature are used to investigate the effect of spectroscopic temperatures and a power ratio analysis of the surface brightness maps allows us to assess the dependence of the mass bias on cluster dynamical state. Moreover, we perform a study on the reliability of hydrostatic and hydrodynamical equilibrium mass estimates using the full three-dimensional information in the simulation.
Results: A model with a low degree of sophistication such as the polytropic β-model can introduce, in comparison with a more adequate model, an additional mass underestimate of the order of ~10% at r500 and ~15% at r200. Underestimates due to extrapolation alone are at most of the order of ~10% on average, but can be as large as ~50% for individual objects. Masses are on average biased lower for disturbed clusters than for relaxed ones and the scatter of the bias rapidly increases with increasingly disturbed dynamical state. The bias originating from spectroscopic temperatures alone is of the order of 10% at all radii for the whole numerical sample, but strongly depends on both dynamical state and cluster mass. From the full three dimensional information in the simulations we find that the hydrostatic equilibrium assumption yields masses underestimated by ~10-15% and that masses computed by means of the hydrodynamical estimator are unbiased. Finally, we show that there is excellent agreement between our findings, results from similar analyses based on both Eulerian and Lagrangian simulations, and recent observational work based on the comparison between X-ray and gravitational lensing mass estimates
A ‘semi-custom’ unibody single-branch endograft to preserve the left subclavian artery during thoracic endovascular aortic repair in zone 2: the answer to any question?
No full textDevelopment of an Innovative Pupillometer Able to Selectively Stimulate the Eye’s Fundus Photoreceptor Cells
No full textRecent advancements in clinical research have identified the need to combine pupillometry with a selective stimulation of the eye's photoreceptor cell types to broaden retinal and neuroretinal health assessment opportunities. Our thorough analysis of the literature revealed the technological gaps that currently restrict and hinder the effective utilization of a method acknowledged to hold great potential. The available devices do not adequately stimulate the photoreceptor types with enough contrast and do not guarantee seamless device function integration, which would enable advanced data analysis. RetinaWISE is an advanced silencing pupillometry device that addresses these deficiencies. It combines a Maxwellian optical arrangement with advanced retinal stimulation, allowing for calibrated standard measurements to generate advanced and consistent results across multiple sites. The device holds a Class 1 CE marking under EU regulation 2017/745, thus facilitating clinical research progress
Fusion of CT Angiography or MR Angiography with Unenhanced CBCT and Fluoroscopy Guidance in Endovascular Treatments of Aorto-Iliac Steno-Occlusion : Technical Note on a Preliminary Experience
No full textAim: To evaluate the feasibility of image fusion (IF) of pre-procedural arterial-phase CT angiography or MR angiography with intra-procedural fluoroscopy for road-mapping in endovascular treatment of aorto-iliac steno-occlusive disease. Materials and Methods: Between September and November, 2014, we prospectively evaluated 5 patients with chronic aorto-iliac steno-occlusive disease, who underwent endovascular treatment in the angiography suite. Fusion image road-mapping was performed using angiographic phase CT images or MR images acquired before and intra-procedural unenhanced cone-beam CT. Radiation dose of the procedure, volume of intra-procedural iodinated contrast medium, fluoroscopy time, and overall procedural time were recorded. Reasons for potential fusion imaging inaccuracies were also evaluated. Results: Image co-registration and fusion guidance were feasible in all procedures. Mean radiation dose of the procedure was 60.21 Gycm2 (range 55.02–63.75 Gycm2). The mean total procedure time was 32.2 min (range 27–38 min). The mean fluoroscopy time was 12 min and 3 s. The mean procedural iodinated contrast material dose was 24 mL (range 20–40 mL). Conclusions: IF gives Interventional Radiologists the opportunity to use new technologies in order to improve outcomes with a significant reduction of contrast media administration
A Matched Case-Control Study on Open and Endovascular Treatment of Popliteal Artery Aneurysms
No full textTo compare early and late results of open and endovascular management of popliteal artery aneurysm in a retrospective single-center matched case-control study Methods: From 1981 to 2015, 309 consecutive interventions for popliteal artery aneurysm were performed in our institution, in 59 cases with endovascular repair and in 250 cases with open repair. Endovascular repair was preferred in older asymptomatic patients, while open repair was offered more frequently to patients with a thrombosed popliteal artery aneurysm and a poor run-off status. A one-to-one coarsened exact matching on the basis of the baseline demographic, clinical, and anatomical covariates significantly different between the two treatment options was performed and two equivalent groups of 56 endovascular repairs and open repairs were generated. The two groups were compared in terms of perioperative results with χ2test and of follow-up outcomes with the Kaplan-Meier curves and log-rank test
Endovascular retreatment of a splenic artery aneurysm refilled by collateral branches of the left gastric artery : a case report
No full textIntroduction: A rare case of a splenic artery aneurysm refilled by a hypertrophic branch originating from the left gastric artery retreated with an endovascular approach is reported. To the best of our knowledge, this is the first such case reported in the literature. Case presentation: A hilum splenic artery aneurysm of a 43-year-old Caucasian woman was treated with endovascular ligature. Contrast-enhanced computed tomography performed after 1 month revealed reperfusion of the aneurysm and a new angiogram demonstrated a hypertrophic vessel from her left gastric artery supplying the sac of the aneurysm. It was catheterized by splenic hilum branches and it was embolized with coil and glue. Contrast-enhanced computed tomography performed after 3 months confirmed complete exclusion of the sac of the aneurysm. Conclusions: Our patient represents the first rare case of a splenic artery aneurysm refilled from a branch of her left gastric artery not visible at first at angiography or at contrast-enhanced computed tomography performed after1 month; it was revealed at the second angiography and it was definitively embolized. These eventualities and possibilities of treatment, although rare, should be kept in mind for each patient with similar presentation
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