2,860 research outputs found
S. Miceli, Il Demiurgo trasgressivo
No full textSeveri Carlo. S. Miceli, Il Demiurgo trasgressivo. In: L'Homme, 1987, tome 27 n°103. p. 131
1164. S. Severi, Abrincensis episcopi, Rotomagam translatio
No full text1164. S. Severi, Abrincensis episcopi, Rotomagam translatio. In: Molinier Auguste. Les Sources de l'histoire de France - Des origines aux guerres d'Italie (1494). II. Époque féodale, les Capétiens jusqu'en 1180. Paris : A. Picard et fils, 1902. p. 52
Gruzinski, S. et al. — Visions indiennes, visions baroques. Les métissages de l'inconscient.
No full textSeveri Carlo. Gruzinski, S. et al. — Visions indiennes, visions baroques. Les métissages de l'inconscient.. In: Journal de la Société des Américanistes. Tome 80, 1994. pp. 302-304
Rate-adapted dynamic-clamp of the funny current in sinoatrial pacemaker cells
No full textA typical feature of sinoatrial node (SAN) pacemaker cells is the presence of an ionic current, named 'funny current', If, that activates upon hyperpolarization. We aimed to: 1) test the impact of different mathematical models of If (Maltsev-Lakatta and Severi-DiFrancesco) in real cells by using the Dynamic Clamp (DC) technique; 2) adapt the DC protocol to adequately simulate a shift of the If activation curve. Two different protocols were implemented: i) the If was selectively blocked by Ivabradine and substituted with a "synthetic" If dynamically reconstructed from the experimentally recorded action potentials of a single isolated rabbit SAN cell according to the mathematical models; ii) virtual negative shift of the If activation curve by the injection of a compensatory current using DC. The Severi-DiFrancesco model allowed the restoration of control pacemaking rate while the MaltsevLakatta model did not. The compensatory current used to reproduce the negative shift of the activation curve did not yield the expected results; we therefore adapted the Dynamic Clamp to the single-cell specific behavior by scaling the estimated If current based on the spontaneous firing rate. This adaptation protocol succeeded in reproducing the effects of a negative activation shift. The Ivabradine protocol was then repeated with this adjustment and the results were fully consistent with those previously obtained
Electrolyte and pH dependence of heart rate during hemodialysis: A computer model analysis
No full textThe influence of hemodialysis-induced modifications in extracellular fluid characteristics on heart rate was investigated by using a detailed computer model of sinus-node electrical activity. Changes similar to those occurring in the course of hemodialysis in extracellular concentrations of sodium (from 138 to 140 mM), potassium (from 6 to 3.3 mM), and calcium (from 1.2 to 1.5 mM) ions as well as in pH (from 7.31 to 7.4) and intracellular volume were simulated. The model predicted that such changes may largely influence the rhythm of the sinoatrial node pacemaker, causing the heart rate to range from 69 to 86 bpm. Heart rate increases after removing potassium (up to 7 bpm) and also after calcium perfusion (up to 11 bpm) whereas restoring pH slows heart beat (up to 6 bpm). Extracellular sodium has no significant influence, but the heart rate strictly depends on intracellular sodium concentration (5 bpm/mM). A complex dependence of heart rate on electrolytes and pH was also recognized. Providing extracellular potassium concentration is maintained above 5 mM, heart rate exhibits low sensitivity to changes in calcium and potassium. When potassium concentration is reduced below 4.5 mM, heart rate sensitivity to calcium and potassium increases significantly to 10 and 30 bpm/mM, respectively. A sustained increase in heart rate always corresponds to an increase in intracellular sodium concentration
"S'ei piace ei lice": If it's pleasant it's possible:Tasso's pleasure and Shakespeare's probable borrowings
No full textIl saggio considera la comunanza tra alcune fonti di Torquato Tasso e di William Shakespeare e il linguaggio di alcuni personaggi shakespeariani che, sorprendentemente, riportano versi "tradotti" dell'Aminta o del Torrismondo
Cell-specific dynamic clamp analysis of the role of funny If current in cardiac pacemaking
No full textWe used the Dynamic Clamp technique for i) comparative validation of conflicting computational models of the hyperpolarization-activated funny current, If, and ii) quantification of the role of If in mediating autonomic modulation of heart rate. Experimental protocols based on the injection of a real-time recalculated synthetic If current in sinoatrial rabbit cells were developed. Preliminary results of experiments mimicking the autonomic modulation of If demonstrated the need for a customization procedure to compensate for cellular heterogeneity. For this reason, we used a cell-specific approach, scaling the maximal conductance of the injected current based on the cell's spontaneous firing rate. The pacemaking rate, which was significantly reduced after application of Ivabradine, was restored by the injection of synthetic current based on the Severi-DiFrancesco formulation, while the injection of synthetic current based on the Maltsev-Lakatta formulation did not produce any significant variation. A positive virtual shift of the If activation curve, mimicking the Isoprenaline effects, led to a significant increase in pacemaking rate (+17.3 ± 6.7%, p < 0.01), although of lower magnitude than that induced by real Isoprenaline (+45.0 ± 26.1%). Similarly, a negative virtual shift of the activation curve significantly lowered the pacemaking rate (-11.8 ± 1.9%, p < 0.001), as did the application of real Acetylcholine (-20.5 ± 5.1%). The Dynamic Clamp approach, applied to the If study in cardiomyocytes for the first time and rate-adapted to manage intercellular variability, indicated that: i) the quantitative description of the If current in the Severi-DiFrancesco model accurately reproduces the effects of the real current on rabbit sinoatrial cell pacemaking rate and ii) a significant portion (50-60%) of the physiological autonomic rate modulation is due to the shift of the If activation curve
Evolution of the Seminal O'Hara Rudy Model to More Accurately Simulate the Electrophysiology of Human Ventricular Cardiomyocytes
No full textThe aim of our work consists in developing a new model of the human ventricular cardiomyocyte, based on the O'Hara-Rudy model (ORd), to improve, in particular, the action potential duration (APD) dependence on the extracellular Ca2+ concentration (Cao). Moreover, the new model reproduces all the available experimental data on APD rate dependence, APD restitution, drug block effects, etc., when the experimental extracellular ionic concentrations are carefully reproduced in simulationsThe main differences between our and the ORd model are: a novel Markovian formulation for the L-type Ca2+ current; the Markovian rapid delayed rectifier K+ current formulation published by Li et al.; a new formulation of the Ca2+ release from the sarcoplasmic reticulum. Several model parameters were modifiedOur BS (Bartolucci-Severi) model successfully improved the ORd, one of the most detailed, used and influent models in computational cardiology, by reproducing the APD-Cao relationship while keeping all the original model features tested in the appropriate experimentally-matched conditions. Furthermore, the BS was suitability as baseline for the generation of in silico populations of models and for reproducing cardiac abnormalities such as early afterdepolarizations
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Rational embeddings of the Severi Brauer variety
No full texttextIn an attempt to prove Amitsur's Conjecture for cyclic subgroups of the Brauer group, we look at rational embeddings of the Severi Brauer variety of an algebra into its norm hypersurface. We enlarge the collection of such embeddings, and generalize them to embeddings of generalized Severi Brauer varieties into determinantal varieties.Mathematic
Start-up companies for accessible medical devices: two case studies
No full textLow - resource and emergency settings are the new challenge for companies
in the healthcare sector. In the world, there is a huge health gap, and the companies
must contribute to reducing it.
In addition, the COVID - 19 case shows that global healthcare is highly interconnected.
Companies are called to follow the Sustainable Development Goals (SDGs) by redefining, i.e. by innovating, their strategies and business models, measuring the economic, social, and environmental impacts.
Whenever the market, or the society, calls for innovation from the companies the fastest and most effective answer comes from startups and small and medium - sized enterprises (SMEs). The research for accessible medical devices is no exception. A lot of startups and SMEs around the world are addressing this issue, trying to make an impact and eventually a sustainable business model.
IBD srl and Bioverse srl are two examples of companies, which develop medical devices specifically designed for low resource settings. Their products come from the concept of Reverse and Frugal Innovation, starting from the real needs and accurate analysis of the local resources.
‘Reverse innovation’, a well - established principle in the business world, describes the flow of ideas from emerging to more developed economies. There is strong and growing interest in applying this concept to health care [11]. Portability, user - friendliness, affordability, few disposables, low maintenance needed, and robustness are essential features for Low - Middle Income Countries (LMICs) but also attractive to High-Income Countries (HICs).
Below Bioverse and IBD’s products together with their Business Models will be presented
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