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Abstrac

Estimation of fluence rate and absorbed dose rate due to gas bremsstrahlung from electron storage rings

Abstract Bremsstrahlung produced in electron storage rings by interactions with residual gas has been studied in the energy range 100–1000 MeV using the PLUKA code. Photon spectra and quantitative estimates of fluence rate and tissue absorbed dose rate are given. Simple equations are proposed for the fluence rate and the absorbed dose rate according to the results obtained

Symmetrization Techniques in Image Deblurring

This paper presents a couple of preconditioning techniques that can be used to enhance the performance of iterative regularization methods applied to image deblurring problems with a variety of point spread functions (PSFs) and boundary conditions. More precisely, we first consider the anti-identity preconditioner, which symmetrizes the coefficient matrix associated to problems with zero boundary conditions, allowing the use of MINRES as a regularization method. When considering more sophisticated boundary conditions and strongly nonsymmetric PSFs, the anti-identity preconditioner improves the performance of GMRES. We then consider both stationary and iteration-dependent regularizing circulant preconditioners that, applied in connection with the anti-identity matrix and both standard and flexible Krylov subspaces, speed up the iterations. A theoretical result about the clustering of the eigenvalues of the preconditioned matrices is proved in a special case. The results of many numerical experiments are reported to show the effectiveness of the new preconditioning techniques, including when considering the deblurring of sparse images

Symbol Based Convergence Analysis in Block Multigrid Methods with applications for Stokes problems

The main focus of this paper is the study of efficient multigrid methods for large linear system with a particular saddle-point structure. In particular, we propose a symbol based convergence analysis for problems that have a hidden block Toeplitz structure. Then, they can be investigated focusing on the properties of the associated generating function $\mathbf{f}$, which consequently is a matrix-valued function with dimension depending on the block of the problem. As numerical tests we focus on the matrix sequence stemming from the finite element approximation of the Stokes equation. We show the efficiency of the methods studying the hidden $9\times 9$ block structure of the obtained matrix sequence proposing an efficient algebraic multigrid method with convergence rate independent of the matrix size. Moreover, we present several numerical tests comparing the results with different known strategies

Intermuscular pocket for subcutaneous implantable cardioverter defibrillator: Single-center experience

AbstractThe subcutaneous implantable cardioverter defibrillator (S-ICD) is a novel device now accepted in clinical practice for treating ventricular arrhythmias. In 14 consecutive patients, S-ICD devices were placed in the virtual space between the anterior surface of the serratus anterior muscle and the posterior surface of the latissimus dorsi muscle. During a mean follow up of 9 months, no dislocations, infections, hematoma formations, or skin erosions were observed. Intermuscular implantation of the S-ICD could be a reliable, safe, and appealing alternative to the standard subcutaneous placement

The Rare Book Collection of the Library of the Italian National Institute of Health: from the past to the present

The Library of the Istituto Superiore di Sanità (ISS), the Italian National Institute of Health, is the main library for public health and biomedical research in Italy and holds a small but valuable special collection of ancient books. Known as the Rare Book Collection, this fund consists of over 1200 scientific printed volumes published between the XVI and the XIX century. The purpose of this paper is to illustrate the challenges and the process undertaken by the Library to share and digitalize this Collection

Preliminary Report on the Study of Beam-Induced Background Effects at a Muon Collider

Physics at a multi-TeV muon collider needs a change of perspective for the detector design due to the large amount of background induced by muon beam decays. Preliminary studies, based on simulated data, on the composition and the characteristics of the particles originated from the muon decays and reaching the detectors are presented here. The reconstruction performance of the physics processes $H\to b\bar b$ and $Z\to b\bar b$ has been investigated for the time being without the effect of the machine induced background. A preliminary study of the environment hazard due to the radiation induced by neutrino interactions with the matter is presented using the FLUKA simulation program