24 results on '"Fabio Baruffa"'
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2. Honing and proofing Astrophysical codes on the road to Exascale. Experiences from code modernization on many-core systems.
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Salvatore Cielo, Luigi Iapichino, Fabio Baruffa, Matteo Bugli, and Christoph Federrath
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- 2020
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3. Performance Optimisation of Smoothed Particle Hydrodynamics Algorithms for Multi/Many-Core Architectures.
- Author
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Fabio Baruffa, Luigi Iapichino, Nicolay J. Hammer, and Vasileios Karakasis
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- 2017
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4. Intel Quantum Simulator: A cloud-ready high-performance simulator of quantum circuits.
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Gian Giacomo Guerreschi, Justin Hogaboam, Fabio Baruffa, and Nicolas P. D. Sawaya
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- 2020
5. A hybrid classical-quantum workflow for natural language processing.
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Lee J. O'Riordan, Myles Doyle, Fabio Baruffa, and Venkatesh Kannan
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- 2020
6. BioEM: GPU-accelerated computing of Bayesian inference of electron microscopy images.
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Pilar Cossio, David Rohr, Fabio Baruffa, Markus Rampp, Volker Lindenstruth, and Gerhard Hummer
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- 2017
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7. Speeding simulation analysis up with yt and Intel Distribution for Python.
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Salvatore Cielo, Luigi Iapichino, and Fabio Baruffa
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- 2019
8. A hybrid classical-quantum workflow for natural language processing.
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Lee J. O'Riordan, Myles Doyle, Fabio Baruffa, and Venkatesh Kannan
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- 2021
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9. ECHO-3DHPC: Advance the performance of astrophysics simulations with code modernization.
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Matteo Bugli, Luigi Iapichino, and Fabio Baruffa
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- 2018
10. Life history and ancestry of the late Upper Palaeolithic infant from Grotta delle Mura, Italy
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Owen Alexander Higgins, Alessandra Modi, Costanza Cannariato, Maria Angela Diroma, Federico Lugli, Stefano Ricci, Valentina Zaro, Stefania Vai, Antonino Vazzana, Matteo Romandini, He Yu, Francesco Boschin, Luigi Magnone, Matteo Rossini, Giovanni Di Domenico, Fabio Baruffaldi, Gregorio Oxilia, Eugenio Bortolini, Elena Dellù, Adriana Moroni, Annamaria Ronchitelli, Sahra Talamo, Wolfgang Müller, Mauro Calattini, Alessia Nava, Cosimo Posth, Martina Lari, Luca Bondioli, Stefano Benazzi, and David Caramelli
- Subjects
Science - Abstract
Abstract The biological aspects of infancy within late Upper Palaeolithic populations and the role of southern refugia at the end of the Last Glacial Maximum are not yet fully understood. This study presents a multidisciplinary, high temporal resolution investigation of an Upper Palaeolithic infant from Grotta delle Mura (Apulia, southern Italy) combining palaeogenomics, dental palaeohistology, spatially-resolved geochemical analyses, direct radiocarbon dating, and traditional anthropological studies. The skeletal remains of the infant – Le Mura 1 – were directly dated to 17,320-16,910 cal BP. The results portray a biological history of the infant’s development, early life, health and death (estimated at ~72 weeks). They identify, several phenotypic traits and a potential congenital disease in the infant, the mother’s low mobility during gestation, and a high level of endogamy. Furthermore, the genomic data indicates an early spread of the Villabruna-like components along the Italian peninsula, confirming a population turnover around the time of the Last Glacial Maximum, and highlighting a general reduction in genetic variability from northern to southern Italy. Overall, Le Mura 1 contributes to our better understanding of the early stages of life and the genetic puzzle in the Italian peninsula at the end of the Last Glacial Maximum.
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- 2024
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11. Performance Optimisation of Smoothed Particle Hydrodynamics Algorithms for Multi/Many-Core Architectures.
- Author
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Fabio Baruffa, Luigi Iapichino, Nicolay J. Hammer, and Vasileios Karakasis
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- 2016
12. Honing and proofing Astrophysical codes on the road to Exascale. Experiences from code modernization on many-core systems
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Fabio Baruffa, Luigi Iapichino, Christoph Federrath, Matteo Bugli, and Salvatore Cielo
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FOS: Computer and information sciences ,J.2 ,Computer Networks and Communications ,Computer science ,J.0 ,FOS: Physical sciences ,02 engineering and technology ,Modernization theory ,0202 electrical engineering, electronic engineering, information engineering ,Code (cryptography) ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,C.0 ,D.4.8 ,Computer Science - Performance ,Xeon ,Node (networking) ,Degree of parallelism ,020206 networking & telecommunications ,Computational Physics (physics.comp-ph) ,Program optimization ,Visualization ,Performance (cs.PF) ,Computer Science - Distributed, Parallel, and Cluster Computing ,Computer architecture ,Hardware and Architecture ,020201 artificial intelligence & image processing ,Distributed, Parallel, and Cluster Computing (cs.DC) ,Astrophysics - Instrumentation and Methods for Astrophysics ,Physics - Computational Physics ,Software - Abstract
The complexity of modern and upcoming computing architectures poses severe challenges for code developers and application specialists, and forces them to expose the highest possible degree of parallelism, in order to make the best use of the available hardware. The Intel$^{(R)}$ Xeon Phi$^{(TM)}$ of second generation (code-named Knights Landing, henceforth KNL) is the latest many-core system, which implements several interesting hardware features like for example a large number of cores per node (up to 72), the 512 bits-wide vector registers and the high-bandwidth memory. The unique features of KNL make this platform a powerful testbed for modern HPC applications. The performance of codes on KNL is therefore a useful proxy of their readiness for future architectures. In this work we describe the lessons learnt during the optimisation of the widely used codes for computational astrophysics P-Gadget-3, Flash and Echo. Moreover, we present results for the visualisation and analysis tools VisIt and yt. These examples show that modern architectures benefit from code optimisation at different levels, even more than traditional multi-core systems. However, the level of modernisation of typical community codes still needs improvements, for them to fully utilise resources of novel architectures., Comment: 16 pages, 10 figures, 4 tables. To be published in Future Generation of Computer Systems (FGCS), Special Issue on "On The Road to Exascale II: Advances in High Performance Computing and Simulations"
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- 2020
13. Deploying AI Frameworks on Secure HPC Systems with Containers
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Sofia Vallecorsa, Fabio Baruffa, Atanas Atanasov, Walter Riviera, and David Brayford
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FOS: Computer and information sciences ,Computer science ,Computer Science - Artificial Intelligence ,Distributed computing ,Scale (chemistry) ,020206 networking & telecommunications ,02 engineering and technology ,Open source software ,Supercomputer ,computer.software_genre ,Artificial Intelligence (cs.AI) ,Computer Science - Distributed, Parallel, and Cluster Computing ,Software deployment ,Scripting language ,Research community ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Distributed, Parallel, and Cluster Computing (cs.DC) ,computer - Abstract
The increasing interest in the usage of Artificial Intelligence techniques (AI) from the research community and industry to tackle "real world" problems, requires High Performance Computing (HPC) resources to efficiently compute and scale complex algorithms across thousands of nodes. Unfortunately, typical data scientists are not familiar with the unique requirements and characteristics of HPC environments. They usually develop their applications with high-level scripting languages or frameworks such as TensorFlow and the installation process often requires connection to external systems to download open source software during the build. HPC environments, on the other hand, are often based on closed source applications that incorporate parallel and distributed computing API's such as MPI and OpenMP, while users have restricted administrator privileges, and face security restrictions such as not allowing access to external systems. In this paper we discuss the issues associated with the deployment of AI frameworks in a secure HPC environment and how we successfully deploy AI frameworks on SuperMUC-NG with Charliecloud., 6 pages, 2 figures, 2019 IEEE High Performance Extreme Computing Conference
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- 2019
14. A hybrid classical-quantum workflow for natural language processing
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Venkatesh Kannan, Fabio Baruffa, L. ORiordan, and Myles Doyle
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FOS: Computer and information sciences ,Computer Science - Machine Learning ,Computer science ,FOS: Physical sciences ,computer.software_genre ,Machine Learning (cs.LG) ,Quantum circuit ,Artificial Intelligence ,Quantum ,Quantum computer ,Structure (mathematical logic) ,Quantum Physics ,Computer Science - Computation and Language ,business.industry ,Suite ,Scale (chemistry) ,Human-Computer Interaction ,Workflow ,Artificial intelligence ,Quantum Physics (quant-ph) ,business ,Computation and Language (cs.CL) ,computer ,Software ,Natural language processing ,Sentence - Abstract
Natural language processing (NLP) problems are ubiquitous in classical computing, where they often require significant computational resources to infer sentence meanings. With the appearance of quantum computing hardware and simulators, it is worth developing methods to examine such problems on these platforms. In this manuscript we demonstrate the use of quantum computing models to perform NLP tasks, where we represent corpus meanings, and perform comparisons between sentences of a given structure. We develop a hybrid workflow for representing small and large scale corpus data sets to be encoded, processed, and decoded using a quantum circuit model. In addition, we provide our results showing the efficacy of the method, and release our developed toolkit as an open software suite., For associated code, see https://github.com/ICHEC/QNLP
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- 2020
15. Performance Optimisation of Smoothed Particle Hydrodynamics Algorithms for Multi/Many-Core Architectures
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Nicolay Hammer, Luigi Iapichino, Vasileios Karakasis, and Fabio Baruffa
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FOS: Computer and information sciences ,Xeon ,Computer science ,FOS: Physical sciences ,010103 numerical & computational mathematics ,Ivy Bridge ,Computational Physics (physics.comp-ph) ,01 natural sciences ,Smoothed-particle hydrodynamics ,Software portability ,Computer Science - Distributed, Parallel, and Cluster Computing ,0103 physical sciences ,Scalability ,Code (cryptography) ,Distributed, Parallel, and Cluster Computing (cs.DC) ,0101 mathematics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Physics - Computational Physics ,010303 astronomy & astrophysics ,Algorithm ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Xeon Phi - Abstract
We describe a strategy for code modernisation of Gadget, a widely used community code for computational astrophysics. The focus of this work is on node-level performance optimisation, targeting current multi/many-core IntelR architectures. We identify and isolate a sample code kernel, which is representative of a typical Smoothed Particle Hydrodynamics (SPH) algorithm. The code modifications include threading parallelism optimisation, change of the data layout into Structure of Arrays (SoA), auto-vectorisation and algorithmic improvements in the particle sorting. We obtain shorter execution time and improved threading scalability both on Intel XeonR ($2.6 \times$ on Ivy Bridge) and Xeon PhiTM ($13.7 \times$ on Knights Corner) systems. First few tests of the optimised code result in $19.1 \times$ faster execution on second generation Xeon Phi (Knights Landing), thus demonstrating the portability of the devised optimisation solutions to upcoming architectures., Comment: 8 pages, 2 columns, 4 figures, accepted as paper at HPCS Proceedings 2017, IEEE XPLORE
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- 2016
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16. An infant burial from Arma Veirana in northwestern Italy provides insights into funerary practices and female personhood in early Mesolithic Europe
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Jamie Hodgkins, Caley M. Orr, Claudine Gravel-Miguel, Julien Riel-Salvatore, Christopher E. Miller, Luca Bondioli, Alessia Nava, Federico Lugli, Sahra Talamo, Mateja Hajdinjak, Emanuela Cristiani, Matteo Romandini, Dominique Meyer, Danylo Drohobytsky, Falko Kuester, Geneviève Pothier-Bouchard, Michael Buckley, Lucia Mancini, Fabio Baruffaldi, Sara Silvestrini, Simona Arrighi, Hannah M. Keller, Rocío Belén Griggs, Marco Peresani, David S. Strait, Stefano Benazzi, and Fabio Negrino
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Medicine ,Science - Abstract
Abstract The evolution and development of human mortuary behaviors is of enormous cultural significance. Here we report a richly-decorated young infant burial (AVH-1) from Arma Veirana (Liguria, northwestern Italy) that is directly dated to 10,211–9910 cal BP (95.4% probability), placing it within the early Holocene and therefore attributable to the early Mesolithic, a cultural period from which well-documented burials are exceedingly rare. Virtual dental histology, proteomics, and aDNA indicate that the infant was a 40–50 days old female. Associated artifacts indicate significant material and emotional investment in the child’s interment. The detailed biological profile of AVH-1 establishes the child as the earliest European near-neonate documented to be female. The Arma Veirana burial thus provides insight into sex/gender-based social status, funerary treatment, and the attribution of personhood to the youngest individuals among prehistoric hunter-gatherer groups and adds substantially to the scant data on mortuary practices from an important period in prehistory shortly following the end of the last Ice Age.
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- 2021
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17. Theory of Spin Relaxation in Two-Electron Lateral Coupled Quantum Dots
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Fabio Baruffa, Martin Raith, Peter Stano, and Jaroslav Fabian
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Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Spins ,Condensed matter physics ,ddc:530 ,Relaxation (NMR) ,Spin–lattice relaxation ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,530 Physik ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,01 natural sciences ,Magnetic field ,Magnetic anisotropy ,Quantum dot ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Spin echo ,010306 general physics ,0210 nano-technology ,Anisotropy - Abstract
A global quantitative picture of the phonon-induced two-electron spin relaxation in GaAs double quantum dots is presented using highly accurate numerical calculations. Wide regimes of interdot coupling, magnetic field magnitude and orientation, and detuning are explored in the presence of a nuclear bath. Most important, the unusually strong magnetic anisotropy of the singlet-triplet relaxation can be controlled by detuning switching the principal anisotropy axes: a protected state becomes unprotected upon detuning, and vice versa. It is also established that nuclear spins can dominate spin relaxation for unpolarized triplets even at high magnetic fields, contrary to common belief. These findings are central to designing quantum dots geometries for spin-based quantum information processing with minimal environmental impact., Comment: 8 pages, 8 figures
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- 2012
18. Spin-orbit coupling and anisotropic exchange in two-electron double quantum dots
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Jaroslav Fabian, Peter Stano, and Fabio Baruffa
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FOS: Physical sciences ,02 engineering and technology ,Electron ,01 natural sciences ,symbols.namesake ,Quantum mechanics ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,010306 general physics ,Anisotropy ,Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,ddc:530 ,Spin–orbit interaction ,530 Physik ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,3. Good health ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Quantum dot ,Qubit ,Excited state ,symbols ,0210 nano-technology ,Hamiltonian (quantum mechanics) - Abstract
The influence of the spin-orbit interactions on the energy spectrum of two-electron laterally coupled quantum dots is investigated. The effective Hamiltonian for a spin qubit pair proposed in F. Baruffa et al., Phys. Rev. Lett. 104, 126401 (2010) is confronted with exact numerical results in single and double quantum dots in zero and finite magnetic field. The anisotropic exchange Hamiltonian is found quantitatively reliable in double dots in general. There are two findings of particular practical importance: i) The model stays valid even for maximal possible interdot coupling (a single dot), due to the absence of a coupling to the nearest excited level, a fact following from the dot symmetry. ii) In a weak coupling regime, the Heitler-London approximation gives quantitatively correct anisotropic exchange parameters even in a finite magnetic field, although this method is known to fail for the isotropic exchange. The small discrepancy between the analytical model (which employes the linear Dresselhaus and Bychkov-Rashba spin-orbit terms) and the numerical data for GaAs quantum dots is found to be mostly due to the cubic Dresselhaus term., Comment: 15 pages, 11 figures
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- 2010
19. Theory of Anisotropic Exchange in Laterally Coupled Quantum Dots
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Jaroslav Fabian, Fabio Baruffa, and Peter Stano
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Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Spin polarization ,ddc:530 ,FOS: Physical sciences ,General Physics and Astronomy ,Spin engineering ,02 engineering and technology ,530 Physik ,021001 nanoscience & nanotechnology ,Quantum number ,01 natural sciences ,Spin quantum number ,Electron magnetic dipole moment ,Spin magnetic moment ,Quantum spin Hall effect ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,Spin Hall effect ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,0210 nano-technology - Abstract
The effects of spin-orbit coupling on the two-electron spectra in lateral coupled quantum dots are investigated analytically and numerically. It is demonstrated that in the absence of magnetic field the exchange interaction is practically unaffected by spin-orbit coupling, for any interdot coupling, boosting prospects for spin-based quantum computing. The anisotropic exchange appears at finite magnetic fields. A numerically accurate effective spin Hamiltonian for modeling spin-orbit-induced two-electron spin dynamics in the presence of magnetic field is proposed., Comment: 4 pages, 3 figures; paper rewritten
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- 2010
20. The 3D MHD code GOEMHD3 for astrophysical plasmas with large Reynolds numbers
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Fabio Baruffa, Markus Rampp, Johannes Buchner, and Jan Skala
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Physics ,Computer simulation ,Turbulence ,Reynolds number ,Astronomy and Astrophysics ,Astrophysics ,Dissipation ,7. Clean energy ,01 natural sciences ,010305 fluids & plasmas ,Computational science ,symbols.namesake ,Space and Planetary Science ,0103 physical sciences ,symbols ,Astrophysical plasma ,Induction equation ,Magnetohydrodynamics ,010303 astronomy & astrophysics ,Massively parallel - Abstract
Context. The numerical simulation of turbulence and flows in almost ideal astrophysical plasmas with large Reynolds numbers motivates the implementation of magnetohydrodynamical (MHD) computer codes with low resistivity. They need to be computationally efficient and scale well with large numbers of CPU cores, allow obtaining a high grid resolution over large simulation domains, and be easily and modularly extensible, for instance, to new initial and boundary conditions. Aims. Our aims are the implementation, optimization, and verification of a computationally efficient, highly scalable, and easily extensible low-dissipative MHD simulation code for the numerical investigation of the dynamics of astrophysical plasmas with large Reynolds numbers in three dimensions (3D). Methods. The new GOEMHD3 code discretizes the ideal part of the MHD equations using a fast and efficient leap-frog scheme that is second-order accurate in space and time and whose initial and boundary conditions can easily be modified. For the investigation of diffusive and dissipative processes the corresponding terms are discretized by a DuFort-Frankel scheme. To always fulfill the Courant-Friedrichs-Lewy stability criterion, the time step of the code is adapted dynamically. Numerically induced local oscillations are suppressed by explicit, externally controlled diffusion terms. Non-equidistant grids are implemented, which enhance the spatial resolution, where needed. GOEMHD3 is parallelized based on the hybrid MPI-OpenMP programing paradigm, adopting a standard two-dimensional domain-decomposition approach. Results. The ideal part of the equation solver is verified by performing numerical tests of the evolution of the well-understood Kelvin-Helmholtz instability and of Orszag-Tang vortices. The accuracy of solving the (resistive) induction equation is tested by simulating the decay of a cylindrical current column. Furthermore, we show that the computational performance of the code scales very efficiently with the number of processors up to tens of thousands of CPU cores. This excellent scalability of the code was obtained by simulating the 3D evolution of the solar corona above an active region (NOAA AR1249) for which GOEMHD3 revealed the energy distribution in the solar atmosphere in response to the energy influx from the chromosphere through the transition region, taking into account the weak Joule current dissipation and viscosity in the almost dissipationless solar corona.Conclusions. The new massively parallel simulation code GOEMHD3 enables efficient and fast simulations of almost ideal astrophysical plasma flows with large Reynolds numbers well resolved and on huge grids covering large domains. Its abilities are verified by comprehensive set of tests of ideal and weakly dissipative plasma phenomena. The high-resolution (20483 grid points) simulation of a large part of the solar corona above an observed active region proves the excellent parallel scalability of the code up to more than 30 000 processor cores.
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- 2015
21. Dual-Energy Computed Tomography Applications to Reduce Metal Artifacts in Hip Prostheses: A Phantom Study
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Daniele Conti, Fabio Baruffaldi, Paolo Erani, Anna Festa, Stefano Durante, and Miriam Santoro
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arthroplasty ,diagnostic imaging ,dual-energy computed tomography ,hip prosthesis ,metal artifact reduction ,spectral imaging CT ,Medicine (General) ,R5-920 - Abstract
Metal components of hip prostheses cause severe artifacts in CT images, influencing diagnostic accuracy. Metal artifact reduction (MAR) software and virtual monoenergetic reconstructions on dual-energy CT (DECT) systems are possible solutions that should be considered. In this study, we created a customized adjustable phantom to quantify the severity of artifacts on periprosthetic tissues (cortical and spongious bone, soft tissues) for hip prostheses. The severity of artifacts was classified by different thresholds of deviation from the CT numbers for reference objects not affected by artifacts. The in vitro setup was applied on four unilateral and three bilateral configurations of hip prostheses (made of titanium, cobalt, and stainless steel alloys) with a DECT system, changing the energy of virtual monoenergetic reconstructions, with and without MAR. The impact of these tools on the severity of artifacts was scored, looking for the best scan conditions for the different configurations. For titanium prostheses, the reconstruction at 110 keV, without MAR, always minimized the artifacts. For cobalt and stainless-steel prostheses, MAR should always be applied, while monoenergetic reconstruction alone did not show clear advantages. The available tools for reducing metal artifacts must therefore be applied depending on the examined prosthetic configuration.
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- 2022
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22. A Cationic Contrast Agent in X-ray Imaging of Articular Cartilage: Pre-Clinical Evaluation of Diffusion and Attenuation Properties
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Simone Fantoni, Ilenia Gabucci, Paolo Cardarelli, Gianfranco Paternò, Angelo Taibi, Virginia Cristofori, Claudio Trapella, Armando Bazzani, Marta Assenza, Alice Zanna Bonacorsi, Daniele Conti, and Fabio Baruffaldi
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X-ray imaging ,articular cartilage ,contrast agent ,contrast-enhanced computed tomography ,proteoglycans ,post-traumatic osteoarthritis ,Medicine (General) ,R5-920 - Abstract
The aim of this study was the preliminary assessment of a new cationic contrast agent, the CA4+, via the analysis of spatial distribution in cartilage of ex vivo bovine samples, at micrometer and millimeter scale. Osteochondral plugs (n = 18) extracted from bovine stifle joints (n = 2) were immersed in CA4+ solution up to 26 h. Planar images were acquired at different time points, using a microCT apparatus. The CA4+ distribution in cartilage and saturation time were evaluated. Tibial plates from bovine stifle joints (n = 3) were imaged with CT, before and after 24 h-CA4+ bath immersion, at different concentrations. Afterward, potential CA4+ washout from cartilage was investigated. From microCT acquisitions, the CA4+ distribution differentiated into three distinct layers inside the cartilage, reflecting the spatial distribution of proteoglycans. After 24 h of diffusion, the iodine concentration reached in cartilage was approximately seven times that of the CA4+ bath. The resulting saturation time was 1.9 ± 0.9 h and 2.6 ± 2.9 h for femoral and tibial samples, respectively. Analysis of clinical CT acquisitions confirmed overall contrast enhancement of cartilage after 24 h immersion, observed for each CA4+ concentration. Distinct contrast enhancement was reached in different cartilage regions, depending on tissue’s local features. Incomplete but remarkable washout of cartilage was observed. CA4+ significantly improved cartilage visualization and its qualitative analysis.
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- 2022
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23. Classification Scheme of Heating Risk during MRI Scans on Patients with Orthopaedic Prostheses
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Valeria Clementi, Umberto Zanovello, Alessandro Arduino, Cristina Ancarani, Fabio Baruffaldi, Barbara Bordini, Mario Chiampi, Luca Zilberti, and Oriano Bottauscio
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MRI heating risk ,MRI safety ,orthopaedic implants ,radiofrequency-induced heating ,gradient-induced heating ,Medicine (General) ,R5-920 - Abstract
Due to the large variety of possible clinical scenarios, a reliable heating-risk assessment is not straightforward when patients with arthroplasty undergo MRI scans. This paper proposes a simple procedure to estimate the thermal effects induced in patients with hip, knee, or shoulder arthroplasty during MRI exams. The most representative clinical scenarios were identified by a preliminary frequency analysis, based on clinical service databases, collecting MRI exams of 11,658 implant carrier patients. The thermal effects produced by radiofrequency and switching gradient fields were investigated through 588 numerical simulations performed on an ASTM-like phantom, considering four prostheses, two static field values, seven MR sequences, and seven regions of imaging. The risk assessment was inspired by standards for radiofrequency fields and by scientific studies for gradient fields. Three risk tiers were defined for the radiofrequency, in terms of whole-body and local SAR averages, and for GC fields, in terms of temperature elevation. Only 50 out of 588 scenarios require some caution to be managed. Results showed that the whole-body SAR is not a self-reliant safety parameter for patients with metallic implants. The proposed numerical procedure can be easily extended to any other scenario, including the use of detailed anatomical models.
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- 2022
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24. Characterization of Structural Bone Properties through Portable Single-Sided NMR Devices: State of the Art and Future Perspectives
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Marco Barbieri, Paola Fantazzini, Claudia Testa, Villiam Bortolotti, Fabio Baruffaldi, Feliks Kogan, and Leonardo Brizi
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bone ,single-sided NMR ,NMR relaxometry ,osteoporosis ,structural parameters ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Nuclear Magnetic Resonance (NMR) is a well-suited methodology to study bone composition and structural properties. This is because the NMR parameters, such as the T2 relaxation time, are sensitive to the chemical and physical environment of the 1H nuclei. Although magnetic resonance imaging (MRI) allows bone structure assessment in vivo, its cost limits the suitability of conventional MRI for routine bone screening. With difficulty accessing clinically suitable exams, the diagnosis of bone diseases, such as osteoporosis, and the associated fracture risk estimation is based on the assessment of bone mineral density (BMD), obtained by the dual-energy X-ray absorptiometry (DXA). However, integrating the information about the structure of the bone with the bone mineral density has been shown to improve fracture risk estimation related to osteoporosis. Portable NMR, based on low-field single-sided NMR devices, is a promising and appealing approach to assess NMR properties of biological tissues with the aim of medical applications. Since these scanners detect the signal from a sensitive volume external to the magnet, they can be used to perform NMR measurement without the need to fit a sample inside a bore of a magnet, allowing, in principle, in vivo application. Techniques based on NMR single-sided devices have the potential to provide a high impact on the clinical routine because of low purchasing and running costs and low maintenance of such scanners. In this review, the development of new methodologies to investigate structural properties of trabecular bone exploiting single-sided NMR devices is reviewed, and current limitations and future perspectives are discussed.
- Published
- 2021
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