Illuminating Leonardo offers new contributions from major scholars of Leonardo da Vinci covering all aspects of his genius, including his manuscripts and their aftermath, and the various fields of ...art and science.
Dual mode imaging in the mid infrared band, a joint use of thermography and quasi-thermal reflectography, was recently proposed as a full field diagnostic tool in cultural heritage. Here we discuss ...for the first time, to the best of our knowledge, a detailed application of such non destructive technique to the diagnostics of frescoes, with an emphasis on the location of detachments. We also investigate the use of a thermographic method based on TSR (thermal signal reconstruction), in a long pulse stimulus scheme, as well as the spatial registration of thermal images after post-processing analysis to their visible counterpart, so as to obtain a fine resolution diagnostic map. As an exemplar case study, we report about the application of dual mode imaging with a 500 Formula: see text pixel size at object plane on the "Monocromo", a fresco by Leonardo da Vinci located in the Sforza Castle (Milan, Italy). Our technique was used to guide the conservators during the restoration works, opening new perspectives in artwork diagnostics.
This article presents an overview of the dynamics of the human heart and the main goal is the discussion of its fluid mechanic features. We will see, however, that the flow in the heart can not be ...fully described without considering its electrophysiology and elastomechanics as well as the interaction with the systemic and pulmonary circulations with which it is strongly connected. Biologically, the human heart is similar to that of all warm-blooded mammals and it satisfies the same allometric laws. Since the Paleolithic Age, however, humans have improved their living conditions, have modified the environment to satisfy their needs and, more recently, have developed advanced medical knowledge which has allowed triple the number of heartbeats with respect to other mammals. In the last century, effective diagnostic tools, reliable surgical procedures and prosthetic devices have been developed and refined leading to substantial progress in cardiology and heart surgery with routine clinical practice which nowadays cures many disorders, once lethal. Pulse duplicators have been built to reproduce the pulsatile flow and ‘blood analogues’, have been realized. Heart phantoms, can attain deformations similar to the real heart although the active contraction and the tissue anisotropy still can not be replicated. Numerical models have also become a viable alternative for cardiovascular research: they do not suffer from limitations of material properties and device technologies, thus making possible the realization of truly digital twins. Unfortunately, a high-fidelity model for the whole heart consists of a system of coupled, nonlinear partial differential equations with a number of degrees of freedom of the order of a billion and computational costs become the bottleneck. An additional challenge comes from the inherent human variability and the uncertainty of the heart parameters whose statistical assessment requires a campaign of simulations rather than a single deterministic calculation; reduced and surrogate models can be employed to alleviate the huge computational burden and all possibilities are currently being pursued. In the era of big data and artificial intelligence, cardiovascular research is also advancing by exploiting the latest technologies: equation-based augmented reality, virtual surgery and computational prediction of disease progression are just a few examples among many that will become standard practice in the forthcoming years.
Prin toate compartimentele sale, dicţionarul se adresează unui public larg, compus din elevi, studenţi, traducători, cadre didactice, jurnalişti, cercetători, scriitori, cititori interesaţi de ...utilizarea corectă a limbii române şi de corespondenţele care se stabilesc între limba maghiară şi limba română. Numele autorului reprezintă prin el însuşi un garant al calităţii şi al utilităţii lucrării, ştiute fiind colaborările apropiate ale profesorului cu îndelungată experienţă cu şcolile cu predare în limba română din Ungaria, cu cele de limbă maghiară din România şi aplecarea de care dă dovadă faţă de nevoile reale ale elevilor şi studenţilor în ceea ce priveşte învăţarea limbii române, dar nu numai. În concluzie, Farkas Jeno nu propune o simplă carte care să servească drept suport pentru praf într-o bibliotecă, cum, din păcate, ajung atâtea altele, ci oferă un instrument de lucru util în cel mai înalt nivel cu putinţă, care depăşeşte cu mult limitele necesităţilor didactice.
This paper accounts for the diagnostic campaign aimed at understanding the phenomenon of black stains appeared on the passepartout close to the margins of Folio 843 of Leonardo da Vinci's Codex ...Atlanticus. Previous studies excluded microbiological deterioration processes. The study is based on a multi-analytical approach, including non-invasive imaging measurements of the folio, micro-imaging and synchrotron spectroscopy investigations of passepartout fragments at different magnifications and spectral ranges. Photoluminescence hyperspectral and lifetime imaging highlighted that black stains are not composed of fluorescent materials. μATR-FTIR imaging of fragments from the passepartout revealed the presence of a mixture of starch and PVAc glues localized only in the stained areas close to the margin of the folio. FE-SEM observations showed that the dark stains are localized inside cavities formed among cellulose fibers, where an accumulation of inorganic roundish particles (∅100-200 nm in diameter size), composed of Hg and S, was detected. Finally, by employing synchrotron μXRF, μXANES and HR-XRD analyses it was possible to identify these particles as metacinnabar (β-HgS). Further research is needed to assess the chemical process leading to the metacinnabar formation in the controlled conservation condition of Leonardo's Codex.
We propose four novel mathematical models, describing the microscopic mechanisms of force generation in the cardiac muscle tissue, which are suitable for multiscale numerical simulations of cardiac ...electromechanics. Such models are based on a biophysically accurate representation of the regulatory and contractile proteins in the sarcomeres. Our models, unlike most of the sarcomere dynamics models that are available in the literature and that feature a comparable richness of detail, do not require the time-consuming Monte Carlo method for their numerical approximation. Conversely, the models that we propose only require the solution of a system of PDEs and/or ODEs (the most reduced of the four only involving 20 ODEs), thus entailing a significant computational efficiency. By focusing on the two models that feature the best trade-off between detail of description and identifiability of parameters, we propose a pipeline to calibrate such parameters starting from experimental measurements available in literature. Thanks to this pipeline, we calibrate these models for room-temperature rat and for body-temperature human cells. We show, by means of numerical simulations, that the proposed models correctly predict the main features of force generation, including the steady-state force-calcium and force-length relationships, the length-dependent prolongation of twitches and increase of peak force, the force-velocity relationship. Moreover, they correctly reproduce the Frank-Starling effect, when employed in multiscale 3D numerical simulation of cardiac electromechanics.
In his manuscripts, Leonardo Da Vinci left many clues, rules and knowledge about the consequences of friction and the methods to reduce it. The Italian polymath studied and demonstrated aspects ...related to wear, lubrication and contact mechanics, which are the basis of modern tribology. All this knowledge could almost be considered intuitive in the sense that it led him to obtain solutions, concepts and definitions without being mediated by complex processes of reasoning. Through his sketches and extensive reflections, Da Vinci enhanced his knowledge. Present work analyses shows the evidence of knowledge about the origin, factors and the consequences of the relative movement between the bodies, as reported by Leonardo da Vinci and the importance in present day tribology.
•Leonardo da Vinci left clues, rules and knowledge about the consequences of friction and methods to reduce it.•Leonardo's intuitive ideas have been useful to formulate theories, practices and methods, still valid in modern tribology.•The similarities between devices draw by the polymath and modern practices are described.•Four-ball machine proposed by Leonardo is the origin of the standardized method test for lubricants and lubrication systems.
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