169 results on '"Sergio Callegari"'
Search Results
52. Embeddable ADC-based true random number generator for cryptographic applications exploiting nonlinear signal processing and chaos.
- Author
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Sergio Callegari, Riccardo Rovatti, and Gianluca Setti
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- 2005
- Full Text
- View/download PDF
53. Statistical modeling of discrete-time chaotic processes-basic finite-dimensional tools and applications.
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Gianluca Setti, Gianluca Mazzini, Riccardo Rovatti, and Sergio Callegari
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- 2002
- Full Text
- View/download PDF
54. Generation of band-pass constant-envelope signals with a pre-assigned spectrum: a synthesis procedure.
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Sergio Callegari
- Published
- 2002
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- View/download PDF
55. Coding of Stereo Signals by a Single Digital ΔΣ Modulator.
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Sergio Callegari
- Published
- 2014
56. Mapping duality as a means to allow finite βF compensation in bipolar log filters.
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Sergio Callegari and Gianluca Setti
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- 2000
- Full Text
- View/download PDF
57. Should ΔΣ Modulators Used in AC Motor Drives be Adapted to the Mechanical Load of the Motor?
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Sergio Callegari and Federico Bizzarri
- Published
- 2013
58. A CMOS Tailed Tent Map for the Generation of Uniformly Distributed Chaotic Sequences
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Sergio Callegari, Gianluca Setti, and Peter J. Langlois
- Published
- 2013
59. Clinicopathological Bird's-Eye View of Left Atrial Myocardial Fibrosis in 121 Patients With Persistent Atrial Fibrillation: Developing Architecture and Main Cellular Players
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Francesca Rocchio, Valentina Garrapa, Domenico Corradi, Emilio Macchi, Gabriella Becchi, Ottavio Alfieri, Maria Nicastro, Sergio Callegari, Matteo Goldoni, Stefania Croci, Stefano Benussi, Rodolfo Monaco, Emilia Corradini, Luca Magnani, Roberto Sala, David Ferrara, Antonio Banchini, and Alessandro Tafuni
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Adult ,Male ,medicine.medical_specialty ,Biopsy ,myofibroblasts ,Left ,atrial fibrillation ,connexin 43 ,fibrosis ,heart atria ,pathology ,Aged ,Aged, 80 and over ,Atrial Fibrillation ,Atrial Function, Left ,Atrial Remodeling ,Collagen Type I ,Connexin 43 ,Female ,Fibrosis ,Heart Atria ,Heart Valve Diseases ,Humans ,Middle Aged ,Myocardium ,Retrospective Studies ,Rheumatic Heart Disease ,030204 cardiovascular system & hematology ,03 medical and health sciences ,0302 clinical medicine ,Left atrial ,Physiology (medical) ,Internal medicine ,80 and over ,medicine ,030304 developmental biology ,0303 health sciences ,business.industry ,Retrospective cohort study ,Atrial fibrillation ,Atrial Function ,medicine.disease ,Atrial fibrosis ,Persistent atrial fibrillation ,Cardiology ,Myocardial fibrosis ,Cardiology and Cardiovascular Medicine ,business - Abstract
Background: Scientific research on atrial fibrosis in atrial fibrillation (AF) has mainly focused on quantitative or molecular features. The purpose of this study was to perform a clinicoarchitectural/structural investigation of fibrosis to provide one key to understanding the electrophysiological/clinical aspects of AF. Methods: We characterized the fibrosis (amount, architecture, cellular components, and ultrastructure) in left atrial biopsies from 121 patients with persistent/long-lasting persistent AF (group 1; 59 males; 60±11 years; 91 mitral disease–related AF, 30 nonmitral disease–related AF) and from 39 patients in sinus rhythm with mitral valve regurgitation (group 2; 32 males; 59±12 years). Ten autopsy hearts served as controls. Results: Qualitatively, the fibrosis exhibited the same characteristics in all cases and displayed particular architectural scenarios (which we arbitrarily subdivided into 4 stages) ranging from isolated foci to confluent sclerotic areas. The percentage of fibrosis was larger and at a more advanced stage in group 1 versus group 2 and, within group 1, in patients with rheumatic disease versus nonrheumatic cases. In patients with AF with mitral disease and no rheumatic disease, the percentage of fibrosis and the fibrosis stages correlated with both left atrial volume index and AF duration. The fibrotic areas mainly consisted of type I collagen with only a minor cellular component (especially fibroblasts/myofibroblasts; average value range 69–150 cells/mm 2 , depending on the areas in AF biopsies). A few fibrocytes—circulating and bone marrow-derived mesenchymal cells—were also detectable. The fibrosis-entrapped cardiomyocytes showed sarcolemmal damage and connexin 43 redistribution/internalization. Conclusions: Atrial fibrosis is an evolving and inhomogeneous histological/architectural change that progresses through different stages ranging from isolated foci to confluent sclerotic zones which—seemingly—constrain impulse conduction across restricted regions of electrotonically coupled cardiomyocytes. The fibrotic areas mainly consist of type I collagen extracellular matrix and, only to a lesser extent, mesenchymal cells.
- Published
- 2020
60. Compressed Sensing of $\Delta\Sigma$ Streams
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Riccardo Rovatti, Gianluca Setti, Mauro Mangia, and Sergio Callegari
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Decimation ,Basis (linear algebra) ,Computer science ,020206 networking & telecommunications ,Data_CODINGANDINFORMATIONTHEORY ,02 engineering and technology ,computer.file_format ,Delta-sigma modulation ,Data conversion ,Matrix (mathematics) ,Data acquisition ,Compressed sensing ,Hardware_GENERAL ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Nyquist rate ,computer ,Algorithm - Abstract
Compressed sensing (CS) is often applied at the digital level. We consider the case where CS follows a $\Delta \Sigma$ data converter and we show that CS can be practiced directly on the $\Delta \Sigma$ stream. In the proposed scheme, an appropriate sensing matrix incorporates the ability to get rid of the quantization noise from the $\Delta \Sigma$ modulator. We also show that a suitable sparsity basis enables the CS information recovery to be practiced directly at the Nyquist rate and that decimation, which is typically inherent in $\Delta \Sigma$ data acquisition, is not needed. Furthermore, the low depth of $\Delta \Sigma$ streams allows CS measures to be taken without multipliers, streamlining arithmetic blocks. A test case based on electrocardiograms is used to validate the approach.
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- 2019
61. Optimal Coefficient Quantization in Optimal-NTF <tex-math notation='LaTeX'>$\Delta \!\Sigma $ </tex-math> Modulators
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Federico Bizzarri, Sergio Callegari, and Angelo Brambilla
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Discrete mathematics ,Physics ,0209 industrial biotechnology ,Sigma ,020206 networking & telecommunications ,Data_CODINGANDINFORMATIONTHEORY ,02 engineering and technology ,Delta-sigma modulation ,Noise shaping ,Phase-locked loop ,020901 industrial engineering & automation ,Hardware_GENERAL ,Modulation (music) ,0202 electrical engineering, electronic engineering, information engineering ,Embedding ,Electrical and Electronic Engineering ,Wideband ,Phase frequency detector - Abstract
Strategies for the adaptation of $\Delta \!\Sigma $ modulators ( $\Delta \!\Sigma $ Ms) to the embedding environment with respect to the ability of the latter to remove quantization noise have recently been introduced. They rely on formal optimization techniques to deliver finely tuned values for the coefficients of the $\Delta \!\Sigma \text{M}$ internal filters. However, in digital $\Delta \!\Sigma $ Ms, coefficients will necessarily be quantized to short wordlengths, the shorter the better, cost-wise. Unfortunately, this can severely hinder optimality. In this brief, a strategy is proposed to re-use the very optimization framework to minimize the effects of coefficient quantization. The technique is discussed by a practical design example based on a $\Delta \!\Sigma \text{M}$ for a wideband fractional- ${N}$ phase locked loop (PLL).
- Published
- 2018
62. Inherited Structural Heart Diseases With Potential Atrial Fibrillation Occurrence
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Domenico Corradi, Sergio Callegari, and Roberta Manuguerra
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medicine.medical_specialty ,business.industry ,Fairly Often ,Amyloidosis ,Hypertrophic cardiomyopathy ,Atrial fibrillation ,030204 cardiovascular system & hematology ,medicine.disease ,Structural remodeling ,03 medical and health sciences ,0302 clinical medicine ,Clinical history ,Physiology (medical) ,Internal medicine ,Heart failure ,cardiovascular system ,Cardiology ,Medicine ,cardiovascular diseases ,Cardiology and Cardiovascular Medicine ,business ,030217 neurology & neurosurgery - Abstract
Inherited cardiac diseases inducing structural remodeling of the myocardium sometimes develop arrhythmias of various kinds. Among these rhythm disturbances, atrial fibrillation is well known to frequently worsen the prognosis of the primary disorder by increasing morbidity and mortality, especially because of a higher rate of heart failure. In this manuscript, we have reviewed the literature on the most important inherited structural cardiac diseases in whose clinical history atrial fibrillation may occur fairly often.
- Published
- 2015
63. On the Benefit of Adopting Saturable Inductors in Switching-Mode Power-Supplies: A Case Study
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Angelo Brambilla, Lorenzo Codecasa, Sergio Callegari, Federico Bizzarri, Bizzarri, Federico, Brambilla, Angelo, Codecasa, Lorenzo, and Callegari, Sergio
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010302 applied physics ,Computer science ,020208 electrical & electronic engineering ,Mode (statistics) ,02 engineering and technology ,Inductor ,01 natural sciences ,Power (physics) ,Hysteresis ,Hardware_GENERAL ,Electromagnetic coil ,0103 physical sciences ,Hardware_INTEGRATEDCIRCUITS ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Digital control ,Electrical and Electronic Engineering ,Constant (mathematics) ,Voltage - Abstract
We follow up with recent proposals of using inductors working in weak and deep-saturation region to improve the features of switching mode power supplies. To this aim, we use a constant on-time (COT) converter including a saturable inductor as a test vehicle. The inductor model takes into account both hysteresis and dependence on the working temperature of the core and windings. The digital controller of the COT converter is considered too. Electro-thermal simulations are performed to analyse the performances of the overall analog mixed-signal circuit. It is shown that using a proper saturable inductor positively impacts on the design of the converter by mitigating its main drawback of having a working frequency largely dependent on the load conditions and input supply voltage. Some weak points of proposed design are also identified.
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- 2018
64. Lymphatic network distribution and function in the rat heart
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Marcozzi, Cristiana, Solari, Eleonora, Reguzzoni, Marcella, Domenico, Corradi, Sergio, Callegari, Emilio, Macchi, Moriondo, Andrea, and Negrini, Daniela
- Published
- 2018
65. Efficient and Reliable Small-Signal Estimate of Quantization Noise Contribution to Phase Noise in ΔΣ Fractional- N PLL
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Angelo Brambilla, Sergio Callegari, Federico Bizzarri, Bizzarri, Federico, Brambilla, Angelo, and Callegari, Sergio
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Dynamical systems theory ,hybrid dynamical system ,020208 electrical & electronic engineering ,quantization noise ,Spectral density ,Phase Locked Loop ,020206 networking & telecommunications ,02 engineering and technology ,Topology ,Delta-sigma modulation ,discontinuity mapping ,Noise (electronics) ,Phase-locked loop ,Discontinuity (linguistics) ,ΔΣ modulator ,fractional phase locked loop ,Electrical and Electronic Engineering ,Control theory ,Phase noise ,0202 electrical engineering, electronic engineering, information engineering ,Delta Sigma Modulation ,Time domain ,Mathematics - Abstract
The effect of the quantization noise introduced by $\Delta \Sigma $ modulators in fractional- $N$ phase locked loop is studied in the time domain through a variational model of the corresponding analog mixed signal circuits. The latter can be interpreted as hybrid dynamical systems involving discontinuity boundaries and switching in the vector field. Discontinuity mapping is used to define an accurate high order model to propagate perturbations at discontinuity boundaries. This novel approach is more efficient than computing power spectral density of large-signal waveforms from long lasting time domain simulations. Furthermore, with respect to established macro-modeling techniques, it provides a better understanding of how electric elements influence the noise performance. The inherent features of the circuit components turn out to be directly embedded both in the system fundamental matrix and in the discontinuity mapping involved in its dynamical evolution. The validity of the approach is verified through numerical simulations.
- Published
- 2017
66. On the multistage design of optimal-NTF ΔΣ modulators-The case of fractional synthesizers
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Federico Bizzarri, Sergio Callegari, Angelo Brambilla, Callegari, Sergio, Bizzarri, Federico, and Brambilla, Angelo
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Engineering ,Convex Optimization ,02 engineering and technology ,Transfer function ,Noise shaping ,Differentiator ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,Electronic engineering ,Electronic ,Optical and Magnetic Materials ,Electrical and Electronic Engineering ,Semidefinite Programming ,business.industry ,020208 electrical & electronic engineering ,020206 networking & telecommunications ,Delta sigma modulator ,Noise transfer function ,Power (physics) ,Phase-locked loop ,Noise ,Hardware and Architecture ,Electronic, Optical and Magnetic Materials ,fractional frequency synthesizer ,Modulation ,Multistage noise shaping ,business ,Phase frequency detector - Abstract
Digital ΔΣ modulators can be conveniently implemented as multi-stage noise shaping (MASH) architectures whenever some power of the first-difference differentiator is acceptable as the noise transfer function (NTF). Yet, other types of NTF can be more performant in some applications. In fact, strategies for a full adaptation of the NTF to the modulator environment have recently been studied. In this work, the possibility of implementing such optimized NTFs with MASH setups is considered. Although stability cannot be guaranteed as in conventional MASH designs, splitting the modulator in stages can still provide advantages. The case of fractional frequency synthesizers is taken as an example. Through the discussion, an empirical invariant on the overall number of output levels required for stable operation is identified.
- Published
- 2017
67. Morphology and pathophysiology of target anatomical sites for ablation procedures in patients with atrial fibrillation
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Sandro Gelsomino, Emilio Macchi, Domenico Corradi, Sergio Callegari, and Roberto Lorusso
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business.industry ,medicine.medical_treatment ,Atrial fibrillation ,Anatomy ,medicine.disease ,Ablation ,Pathophysiology ,Catheter ,medicine.anatomical_structure ,Anatomical sites ,Functional morphology ,cardiovascular system ,Ligament ,medicine ,In patient ,Cardiology and Cardiovascular Medicine ,business - Abstract
The inadequate long-term efficacy of anti-arrhythmic therapy has been one of the main reasons for the development of non-pharmacological interventions for patients with atrial fibrillation such as catheter and surgical ablation. This has greatly increased interest in the functional morphology and electrophysiological properties of the atria and related anatomical structures. This article is the second of a two-part review that aims to provide anatomical and functional details concerning some of the principal anatomical sites commonly targeted by ablative procedures for treating atrial fibrillation, and covers pulmonary veins, ganglionated plexi, caval veins, and the ligament of Marshall. It also provides some general information about site-specific ablation procedures.
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- 2013
68. Anatomical basis of minimally invasive epicardial ablation of atrial fibrillation
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Sandro Gelsomino, Jos G. Maessen, Roberto Lorusso, Emilio Macchi, Mark La Meir, Sergio Callegari, Domenico Corradi, Orlando Parise, CTC, MUMC+: MA Med Staf Spec CTC (9), MUMC+: MA Cardiothoracale Chirurgie (3), and RS: CARIM School for Cardiovascular Diseases
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Pulmonary and Respiratory Medicine ,medicine.medical_specialty ,medicine.medical_treatment ,Catheter ablation ,Ablation ,Internal medicine ,medicine ,Humans ,Minimally Invasive Surgical Procedures ,cardiovascular diseases ,Atrium (heart) ,Phrenic nerve ,business.industry ,Pericardial cavity ,Cardiac arrhythmia ,Atrial fibrillation ,General Medicine ,medicine.disease ,medicine.anatomical_structure ,Paranasal sinuses ,Pulmonary Veins ,cardiovascular system ,Cardiology ,Catheter Ablation ,Surgery ,Anatomy ,Cardiology and Cardiovascular Medicine ,business - Abstract
Minimally invasive atrial fibrillation surgery (MIAFS) has become a well established and increasingly used option for managing patients with stand-alone arrhythmia. Pulmonary veins (PVs) isolation continues to be the cornerstone of ablation strategies. Indeed, in most cases, atrial fibrillation (AF) is triggered in or near the PVs. Nevertheless, ectopic beats initiating AF may occasionally arise from non-PV foci. The knowledge of the anatomy and underlying morphology of PVs and non-PV foci is essential for cardiac surgeons treating AF patients with epicardial minimally invasive procedures. The anatomical structures relevant to the pathogenesis and the epicardial treatment of AF include the PVs, the pericardial space, the pericardial sinuses, the phrenic nerve, the left atrium, the retro-atrial and caval ganglionated plexuses, the ligament of Marshall, the caval veins and the left atrial appendage. In this review, we briefly describe the basic anatomy of these structures and discuss their specific correlations for cardiac surgeons interested in performing MIAFS.
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- 2013
69. Ultrasonic Nondestructive Evaluation Systems : Industrial Application Issues
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Pietro Burrascano, Sergio Callegari, Augusto Montisci, Marco Ricci, Mario Versaci, Pietro Burrascano, Sergio Callegari, Augusto Montisci, Marco Ricci, and Mario Versaci
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- Ultrasonic waves--Industrial applications, Ultrasonic testing--Equipment and supplies, Nondestructive testing
- Abstract
This book deals with a number of fundamental issues related to the practical implementation of ultrasonic NDT techniques in an industrial environment. The book discusses advanced academic research results and their application to industrial procedures. The text covers the choice and generation of the signals energizing the system to probe position optimization, from quality assessment evaluation to tomographic inversion. With a focus to deepen a number of fundamental aspects involved in the specific objective of designing and developing an ultrasonic imaging system for nondestructive testing, aimed to automatically classify the entire production of an industrial production line, targeted to the field of precision mechanics. The contents of this book is the result of the common effort of six University Research Groups that focused their research activities for two years on this specific objective, working in direct conjunction with primary industrial firms, in a research project funded by the Italian government as a Strategic Research Project.
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- 2015
70. Effect of anisotropy on ventricular vulnerability to unidirectional block and reentry by single premature stimulation during normal sinus rhythm in rat heart
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Philip R. Ershler, Michele Miragoli, Andrea Buccarello, Domenico Corradi, Sergio Callegari, Robert L. Lux, Emilio Macchi, Luca Carnevali, Andrea Sgoifo, Stefano Rossi, and Ezio Musso
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0301 basic medicine ,Epicardial Mapping ,Refractory Period, Electrophysiological ,Physiology ,Heart Ventricles ,Tachycardia, Sinoatrial Nodal Reentry ,Stimulation ,030204 cardiovascular system & hematology ,Ventricular Function, Left ,03 medical and health sciences ,0302 clinical medicine ,Heart Conduction System ,Physiology (medical) ,Heart Septum ,Medicine ,Animals ,Sinus rhythm ,Arrhythmia, Sinus ,Normal Sinus Rhythm ,Stimulus strength ,Electrodes ,business.industry ,Reentry ,Rat heart ,Electric Stimulation ,Rats ,030104 developmental biology ,Heart Block ,Anesthesia ,Point stimulation ,cardiovascular system ,Tachycardia, Ventricular ,Anisotropy ,Cardiology and Cardiovascular Medicine ,business - Abstract
Single high-intensity premature stimuli when applied to the ventricles during ventricular drive of an ectopic site, as in Winfree's “pinwheel experiment,” usually induce reentry arrhythmias in the normal heart, while single low-intensity stimuli barely do. Yet ventricular arrhythmia vulnerability during normal sinus rhythm remains largely unexplored. With a view to define the role of anisotropy on ventricular vulnerability to unidirectional conduction block and reentry, we revisited the pinwheel experiment with reduced constraints in the in situ rat heart. New features included single premature stimulation during normal sinus rhythm, stimulation and unipolar potential mapping from the same high-resolution epicardial electrode array, and progressive increase in stimulation strength and prematurity from diastolic threshold until arrhythmia induction. Measurements were performed with 1-ms cathodal stimuli at multiple test sites ( n = 26) in seven rats. Stimulus-induced virtual electrode polarization during sinus beat recovery phase influenced premature ventricular responses. Specifically, gradual increase in stimulus strength and prematurity progressively induced make, break, and graded-response stimulation mechanisms. Hence unidirectional conduction block occurred as follows: 1) along fiber direction, on right and left ventricular free walls ( n = 23), initiating figure-eight reentry ( n = 17) and tachycardia ( n = 12), and 2) across fiber direction, on lower interventricular septum ( n = 3), initiating spiral wave reentry ( n = 2) and tachycardia ( n = 1). Critical time window (55.1 ± 4.7 ms, 68.2 ± 6.0 ms) and stimulus strength lower limit (4.9 ± 0.6 mA) defined vulnerability to reentry. A novel finding of this study was that ventricular tachycardia evolves and is maintained by episodes of scroll-like wave and focal activation couplets. We also found that single low-intensity premature stimuli can induce repetitive ventricular response ( n = 13) characterized by focal activations. NEW & NOTEWORTHY We performed ventricular cathodal point stimulation during sinus rhythm by progressively increasing stimulus strength and prematurity. Virtual electrode polarization and recovery gradient progressively induced make, break, and graded-response stimulation mechanisms. Unidirectional conduction block occurred along or across fiber direction, initiating figure-eight or spiral wave reentry, respectively, and tachycardia sustained by scroll wave and focal activations.
- Published
- 2016
71. Does the Pathogenesis of AF Vary in Inherited Structural Heart Disease and Nonhereditary Cardiac Disease?
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Sergio, Callegari and Domenico, Corradi
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Heart Diseases ,Atrial Fibrillation ,Humans - Published
- 2016
72. Very low cost chaos-based entropy source for the retrofit or design augmentation of networked devices
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Sergio Callegari, Ahmad Beirami, Mattia Fabbri, Callegari, Sergio, Fabbri, Mattia, and Beirami, Ahmad
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Microcontroller ,Exploit ,Serial communication ,Computer science ,Chaotic ,Surfaces, Coatings and Film ,02 engineering and technology ,03 medical and health sciences ,0302 clinical medicine ,Software ,True-RNG ,0202 electrical engineering, electronic engineering, information engineering ,Number generator ,business.industry ,020208 electrical & electronic engineering ,Hidden Markov proce ,Analog to digital converter (ADC) ,Cryptographic protocol ,Converters ,Surfaces, Coatings and Films ,Chaotic map ,Hardware and Architecture ,Embedded system ,Signal Processing ,business ,030217 neurology & neurosurgery ,Computer hardware - Abstract
Modern cryptographic protocols require good entropy sources. Unfortunately, many networked devices lack subsystems dedicated to this task, being potentially susceptible to random number generator (RNG) attacks. Yet, most of these systems allow software upgrades and host communication ports, providing the option of a retrofit. This work illustrates how chaotic dynamics can be used to design a sub-10$ entropy source capable of an over 48kbit/s rate and offering multiple serial communication abilities. Operation is based on a standard microcontroller and exploits a loop built around one of its analog to digital converters (ADCs). The design offers self-testing features and enables an experimental validation of some recent results on the choice of the best state quantization function to employ when using chaotic maps as RNGs.
- Published
- 2016
73. Current And Emergent Topics
- Author
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Joseph Chang, Sameer Sonkusale, Mustak Yalcin, Tokunbo Ogunfunmi, Joos Vanderwalle, Wei-Ping Zhu, Zicheng Liu, Robert Chen-Hao Chang, Elisabetta Chicca, Sergio Callegari, Chia-Chi Chu, Piotr Dudek, Gwo Giun (Chris) Lee, Masud Chowdhury, Franco Maloberti, and Davies, Anthony C.
- Published
- 2016
74. On the usage of resonate and fire dynamics in the complex oscillation-based test approach
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Mani Soma, Sergio Callegari, Fabio Pareschi, and Gianluca Setti
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Artificial neural network ,Basis (linear algebra) ,Computer science ,Oscillation ,Applied Mathematics ,Chaotic ,Analog signal processing ,Computer Science Applications ,Electronic, Optical and Magnetic Materials ,Analogue filter ,Electronic engineering ,Electrical and Electronic Engineering ,Parametric statistics ,Block (data storage) - Abstract
Resonate and Fire (R+F) models were introduced to account for many phenomena occurring in biological neurons showing sub-threshold oscillations of the membrane potential. In information technology, they are at the basis of Chaotic Spiking Oscillators (CSOs), exploitable in Pulse Coupled Neural Networks (PCNNs). This paper illustrates how the R + F paradigm can also be used for the testing of analog signal processing structures (and specifically filters), extending the Oscillation Based Test (OBT) framework. The rich dynamics of the R + F model is used to encode the block under test features and faults into pulse trains directly processable at the digital level. Means to achieve a precise characterization of firing times are provided and used for parametric testing. Considerations about the trade-off between testing times and accuracy are provided together with a practical example and simulation data. Copyright © 2012 John Wiley & Sons, Ltd.
- Published
- 2012
75. On the Approximate Solution of a Class of Large Discrete Quadratic Programming Problems by $\Delta\Sigma$ Modulation: The Case of Circulant Quadratic Forms
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Gianluca Setti, Sergio Callegari, Federico Bizzarri, Riccardo Rovatti, S. Callegari, F. Bizzarri, R. Rovatti, and G. Setti
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Mathematical optimization ,Optimization problem ,sezele ,CIRCULANT MATRIX ,Heuristic (computer science) ,UNCONSTRAINED BINARY QUADRATIC PROGRAMMING ,delta-sigma modulation ,Delta-sigma modulation ,DELTA-SIGMA MODULATOR ,Delta modulation ,Quadratic form ,Signal Processing ,Approximation ,integer programming ,optimization ,Quadratic programming ,Electrical and Electronic Engineering ,Integer programming ,Circulant matrix ,Mathematics - Abstract
We show that ΔΣ modulators can be interpreted as heuristic solvers for a particular class of optimization problems. Then, we exploit this theoretical result to propose a novel technique to deal with very large unconstrained discrete quadratic programming (UDQP) problems characterized by quadratic forms entailing a circulant matrix. The result is a circuit-based optimization approach involving a recast of the original problem into signal processing specifications, then tackled by the systematic design of an electronic system. This is reminiscent of analog computing, where untreatable differential equations were solved by designing electronic circuits analog to them. The approach can return high quality suboptimal solutions even when many hundreds of variables are considered and proved faster than conventional empirical optimization techniques. Detailed examples taken from two different domains illustrate that the range of manageable problems is large enough to cover practical applications.
- Published
- 2010
76. From Chirps to Random-FM Excitations in Pulse Compression Ultrasound Systems
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Sergio Callegari, Marcello Monticelli, Gianluca Setti, Luca Senni, Pietro Burrascano, Marco Ricci, Massimiliano Eroli, Riccardo Rovatti, Salvatore Caporale, Sergio Callegari, Marco Ricci, Salvatore Caporale, Marcello Monticelli, Massimiliano Eroli, Luca Senni, Riccardo Rovatti, Gianluca Setti, and Pietro Burrascano
- Subjects
Physics - Instrumentation and Detectors ,Ultrasonic NDT ,Pseudo-orthogonal codes ,business.industry ,Computer science ,pulse-compression ,Multi-Input Multi-Output system ,Acoustics ,Ultrasound ,FOS: Physical sciences ,Instrumentation and Detectors (physics.ins-det) ,Transducer ,Pulse compression ,Nondestructive testing ,NONDESTRUCTIVE TESTING ,Chirp ,Constant envelope ,ComputerSystemsOrganization_SPECIAL-PURPOSEANDAPPLICATION-BASEDSYSTEMS ,business ,ULTRASOUND ,Excitation - Abstract
Pulse compression is often practiced in ultrasound Non Destructive Testing (NDT) systems using chirps. However, chirps are inadequate for setups where multiple probes need to operate concurrently in Multiple Input Multiple Output (MIMO) arrangements. Conversely, many coded excitation systems designed for MIMO miss some chirp advantages (constant envelope excitation, easiness of bandwidth control, etc.) and may not be easily implemented on hardware originally conceived for chirp excitations. Here, we propose a system based on random-FM excitations, capable of enabling MIMO with minimal changes with respect to a chirp-based setup. Following recent results, we show that random-FM excitations retain many advantages of chirps and provide the ability to frequency-shape the excitations matching the transducers features., 4 pages, 4 figures. Post-print from conference proceedings. Note that paper in conference proceedings at http://dx.doi.org/10.1109/ULTSYM.2012.0117 has some rendering issues
- Published
- 2013
77. Constant envelope pseudo orthogonal excitations for ultrasound testing
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Sergio Callegari, Salvatore Caporale, Pietro Burrascano, Marco Ricci, Salvatore Caporale, Sergio Callegari, Marco Ricci, and Pietro Burrascano
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Ultrasonic NDT ,business.industry ,Computer science ,MIMO ,Electrical engineering ,Power (physics) ,Constraint (information theory) ,Pulse compression ,Nondestructive testing ,Chirp ,Electronic engineering ,Waveform ,Ultrasonic sensor ,business ,Pulse Compression - Abstract
Various techniques to generate pseudo-orthogonal excitations for Ultrasonic Non Destructive Testing (UT-NDT) are discussed, with the constraint that they deliver constant-envelope waveforms and they are FM based. Pseudo-orthogonal excitations enable multiple Tx probes to be operated simultaneously so that many measurements can be taken at once. The constraints assure minimal disruption of conventional hardware arrangements and guarantee a good exploitation of the power conversion abilities of the Tx probes. The goal is to seek a progressive management of the trade-ofl' between contrasting merit factors.
- Published
- 2013
78. Output Filter Aware Optimization of the Noise Shaping Properties of Delta-Sigma Modulators Via Semi-Definite Programming
- Author
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Sergio Callegari, Federico Bizzarri, Sergio Callegari, and Federico Bizzarri
- Subjects
Optimal design ,Semidefinite programming ,SEMIDEFINITE PROGRAMMING ,sezele ,Computer science ,Computer Science - Information Theory ,Filter (signal processing) ,Reconstruction filter ,Delta-sigma modulation ,Transfer function ,Noise shaping ,Noise ,Computer Science::Systems and Control ,Electronic engineering ,Electrical and Electronic Engineering ,OPTIMIZATION ,DELTA-SIGMA MODULATION - Abstract
The Noise Transfer Function (NTF) of {\Delta}{\Sigma} modulators is typically designed after the features of the input signal. We suggest that in many applications, and notably those involving D/D and D/A conversion or actuation, the NTF should instead be shaped after the properties of the output/reconstruction filter. To this aim, we propose a framework for optimal design based on the Kalman-Yakubovich-Popov (KYP) lemma and semi-definite programming. Some examples illustrate how in practical cases the proposed strategy can outperform more standard approaches., Comment: 14 pages, 18 figures, journal. Code accompanying the paper is available at http://pydsm.googlecode.com
- Published
- 2013
79. Noise Weighting in the Design of Delta-Sigma Modulators (With a Psychoacoustic Coder as an Example)
- Author
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Sergio Callegari, Federico Bizzarri, Sergio Callegari, and Federico Bizzarri
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PSYCHOACOUSTICS ,Finite impulse response ,sezele ,Computer science ,Computer Science - Information Theory ,Quantization (signal processing) ,Design flow ,Noise weighting ,Reconstruction filter ,Delta-sigma modulation ,Transfer function ,Weighting ,Electronic engineering ,NOISE SHAPING ,Electrical and Electronic Engineering ,OPTIMIZATION ,DELTA-SIGMA MODULATION - Abstract
A design flow for {\Delta}{\Sigma} modulators is illustrated, allowing quantization noise to be shaped according to an arbitrary weighting profile. Being based on FIR NTFs, possibly with high order, the flow is best suited for digital architectures. The work builds on a recent proposal where the modulator is matched to the reconstruction filter, showing that this type of optimization can benefit a wide range of applications where noise (including in-band noise) is known to have a different impact at different frequencies. The design of a multiband modulator, a modulator avoiding DC noise, and an audio modulator capable of distributing quantization artifacts according to a psychoacoustic model are discussed as examples. A software toolbox is provided as a general design aid and to replicate the proposed results., Comment: 5 pages, 18 figures, journal. Code accompanying the paper is available at http://pydsm.googlecode.com
- Published
- 2013
80. Antidepressant-like activity and cardioprotective effects of fatty acid amide hydrolase inhibitor URB694 in socially stressed Wistar Kyoto rats
- Author
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Luca Carnevali, Federica Vacondio, Gilberto Spadoni, Andrea Sgoifo, Sergio Callegari, Stefano Rossi, Marco Mor, Annalida Bedini, Silvia Rivara, and Emilio Macchi
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Male ,Anhedonia ,Choice Behavior ,Rats, Inbred WKY ,chemistry.chemical_compound ,Corticosterone ,Fatty acid amide hydrolase ,Dietary Sucrose ,Heart Rate ,Pharmacology (medical) ,Depression (differential diagnoses) ,Depression ,Anandamide ,Endocannabinoid system ,Antidepressive Agents ,Biphenyl compound ,Psychiatry and Mental health ,Neurology ,Psychology ,Arrhythmia ,medicine.medical_specialty ,Cardiotonic Agents ,Heart rate variability ,Stress ,Amidohydrolases ,Cellular and Molecular Neuroscience ,Food Preferences ,Internal medicine ,Heart rate ,medicine ,Animals ,Adverse effect ,Biological Psychiatry ,Pharmacology ,Social stress ,Depressive Disorder ,Endocrine and Autonomic Systems ,business.industry ,Biphenyl Compounds ,Body Weight ,Arrhythmias, Cardiac ,Disease Models, Animal ,Endocrinology ,chemistry ,Neurology (clinical) ,Carbamates ,business ,Stress, Psychological ,Behavioural despair test - Abstract
In humans, depression is often triggered by prolonged exposure to psychosocial stressors and is often associated with cardiovascular comorbidity. Mounting evidence suggests a role for endocannabinoid signaling in the regulation of both emotional behavior and cardiovascular function. Here, we examined cardiac activity in a rodent model of social stress-induced depression and investigated whether pharmacological inhibition of the enzyme fatty acid amide hydrolase (FAAH), which terminates signaling of the endocannabinoid anandamide, exerts antidepressant-like and cardioprotective effects. Male Wistar Kyoto rats were exposed to five weeks of repeated social stress or control procedure. Starting from the third week, they received daily administration of the selective FAAH inhibitor URB694 (0.1 mg/kg, i.p.) or vehicle. Cardiac electrical activity was recorded by radiotelemetry. Repeated social stress triggered biological and behavioral changes that mirror symptoms of human depression, such as (i) reductions in body weight gain and sucrose solution preference, (ii) hyperactivity of the hypothalamic-pituitary-adrenocortical axis, and (iii) increased immobility in the forced swim test. Moreover, stressed rats showed (i) alterations in heart rate daily rhythm and cardiac autonomic neural regulation, (ii) a larger incidence of spontaneous arrhythmias, and (iii) signs of cardiac hypertrophy. Daily treatment with URB694 (i) increased central and peripheral anandamide levels, (ii) corrected stress-induced alterations of biological and behavioral parameters, and (iii) protected the heart against the adverse effects of social stress. Repeated social stress in Wistar Kyoto rats reproduces aspects of human depression/cardiovascular comorbidity. Pharmacological enhancement of anandamide signaling might be a promising strategy for the treatment of these comorbid conditions.
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- 2015
81. Industrial applications of noncontact ultrasonics techniques
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Luca Senni, Luigi Battaglini, Stefano Laureti, David A. Hutchins, Salvatore Caporale, L.A.J. Davis, Sergio Callegari, Burrascano, Pietro, Callegari, Sergio, Montisci, Augusto, Ricci, Marco, Versaci, Mario, Battaglini, Luigi, Caporale, Salvatore, Davis, Lee Andrew John, Laureti, Stefano, Senni, Luca, and Hutchins, David Arthur
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Coupling ,Engineering ,Signal processing ,business.industry ,Engineering (all) ,Computer Science (all) ,Physics and Astronomy (all) ,Mechanical engineering ,Nondestructive evaluation ,Context (language use) ,Transducer ,Nondestructive testing ,Chirp ,business ,Acoustic impedance ,Energy (signal processing) ,Ultrasonic testing - Abstract
In many application environments, it is not possible to practice nondestructive evaluation (NDE) by physically contacting the material under test with probes. Examples include the evaluation of objects that are moving (e.g., on an assembly line), hot materials, materials that cannot risk contamination, and more. Lack of contact means that, typically, the coupling material is air. This poses specific requirements, due to the acoustic impedance mismatch that an air layer can provoke and the consequent energy losses. In this chapter, some examples of setups, transducer arrangements, and signal processing strategies capable of addressing such requirements are illustrated, showing how concepts presented in the previous chapters can be deployed in this particular context. Furthermore, some typical achievable results are illustrated, with respect to a few different testing scenarios, such as the testing of composite materials, the inspection of concrete, imaging of surfaces or thin materials, and food inspection.
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- 2015
82. Ultrasonic Nondestructive Evaluation Systems: Industrial Application Issues
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Mario Versaci, Marco Ricci, Pietro Burrascano, Augusto Montisci, Sergio Callegari, Burrascano, Pietro, Callegari, Sergio, Montisci, Augusto, Ricci, Marco, and Versaci, Mario
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Engineering ,Research groups ,ultrasonics ,Quality assessment ,business.industry ,Industrial production ,Mechanical engineering ,non-destructive testing ,Inversion (meteorology) ,non-destructive evaluation, non-destructive testing, ultrasonics, signal processing, wave propagation ,wave propagation ,Precision mechanics ,Ultrasonic inspection ,Construction engineering ,Nondestructive evaluation system ,Nondestructive testing ,Sensing ,non-destructive evaluation ,Ultrasonic nondestructive evaluation ,business ,signal processing ,Ultrasonic ndt - Abstract
This book deals with a number of fundamental issues related to the practical implementation of ultrasonic NDT techniques in an industrial environment. The book discusses advanced academic research results and their application to industrial procedures. The text covers the choice and generation of the signals energizing the system to probe position optimization, from quality assessment evaluation to tomographic inversion. With a focus to deepen a number of fundamental aspects involved in the specific objective of designing and developing an ultrasonic imaging system for nondestructive testing, aimed to automatically classify the entire production of an industrial production line, targeted to the field of precision mechanics. The contents of this book is the result of the common effort of six University Research Groups that focused their research activities for two years on this specific objective, working in direct conjunction with primary industrial firms, in a research project funded by the Italian government as a Strategic Research Project.
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- 2015
83. Excitations and signal processing for multiprobe setups
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Marco Ricci, Sergio Callegari, Salvatore Caporale, Pietro Burrascano, Burrascano, Pietro, Callegari, Sergio, Montisci, Augusto, Ricci, Marco, Versaci, Mario, and Caporale, Salvatore
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Signal processing ,Tessellation ,business.industry ,Computer science ,Partial permutation ,MIMO ,Probabilistic logic ,Telecommunications network ,Transducer ,Nondestructive testing ,Electronic engineering ,business ,signal processing ,Ultrasonic testing - Abstract
The possibility of taking advantage of multiprobe setups for ultrasound non-destructive testing (NDT) is introduced with reference to its physical and signal processing aspects. Preliminarily, a major distinction is made between phased-arrays and actual multi-transducer configurations. Then, most of the chapter is devoted to the latter type of setup. In this framework, the previously introduced channel model developed for single-probe operation, is extended to setups featuring multiple transmitting transducers (TXs) and receiving transducers (RXs) meant to be employed simultaneously in a so-called multiple input, multiple output (MIMO) configuration. It is also illustrated how this configuration relates to multi-user communication networks. Proper merit factors suitable for characterizing the performances of multiprobe systems are presented by taking advantage of the probabilistic system view introduced for single-probe systems. Finally, various classes of signals that can be adopted in MIMO NDT systems are described. These excitations may be designed according to random or deterministic approaches. In better detail, special techniques based on tessellation of the time-frequency (TF) plane are developed to design excitation signals capable of joining assuring contextually the good degree of appropriateness for MIMO setups and the good signal-to-noise (SNR) and resolution properties of chirps.
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- 2015
84. Excitation and deconvolution in ultrasound nondestructive testing systems
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Pietro Burrascano, Sergio Callegari, Marco Ricci, Salvatore Caporale, David A. Hutchins, Stefano Laureti, Burrascano, Pietro, Callegari, Sergio, Montisci, Augusto, Ricci, Marco, Versaci, Mario, Caporale, Salvatore, Hutchins, David Arthur, and Laureti, Stefano
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Signal processing ,Computer science ,business.industry ,Matched filter ,Analytical chemistry ,Nondestructive testing ,Electronic engineering ,Waveform ,Deconvolution ,Sensitivity (control systems) ,spread spectrum ,ultrasonic testing ,business ,Energy (signal processing) ,Impulse response - Abstract
The pulse-echo (PuE) model based on short pulses is introduced as a starting point. Its limits in terms of signal-to-noise ratio (SNR) are reviewed, together with the tradeoff between the excitation energy and the time resolution. It is shown how signal processing can improve the overall performance in terms of system sensitivity and resolution as long as the exciting waveform is chosen taking into account the system characteristics and is in agreement with the adopted processing techniques. The degrees of freedom on which one can operate are the time evolution law of the excitation signal and the processing technique adopted on the receiving end. In their exploitation, the designer should consider the physical characteristics of the hardware devices being employed in order to optimize the overall performance. The importance of introducing merit factors is discussed. By offering a quantitative measure of system performance, they are indispensable tools to drive formal optimization strategies and for comparing different approaches. Application-related merit factors are introduced for trying to overcome some current limitations and to prepare the ground for the extension of ultrasonic techniques to multiple input, multiple output (MIMO) systems, which are considered in the following chapter.
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- 2015
85. Optimal design of the noise transfer function of ΔΣ modulators: IIR strategies, FIR strategies, FIR strategies with preassigned poles
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Sergio, Callegari and Bizzarri, Federico
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sezele - Published
- 2015
86. Atrial fibrillation management: a prospective survey in ESC Member Countries
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Baciarello, Giacinto, Cicconetti, Paolo, Grigoryan, Armenia: S. V., Apetyan, I., Aroyan, S., Azarapetyan, L., Austria: Anahit Anvari, Michael Gottsauner Wolf, Stefan, Pfaffenberger, Kurt, Huber, Kadriye, Aydinkoc, Karim, Kalla, Martina, Penka, Heinz, Drexel, Peter, Langer, Pierard, Belgium: Luc A., Victor, Legrand, Dominique, Blommaert, Schroeder, E., Isabelle, Mancini, William, Wijns, Geelen, P., Brugada, P., Marc De Zutter, Christiaan, Vrints, Marc, Vercammen, Marielle, Morissens, Bulgaria: Borislav Boyanov Borisov, Valentin Asenov Petrov, Maria Marinova Alexandrova, Assen Rachev Goudev, Vera, Sirakova, Yavor, Peychev, Vassil, Stoyanovsky, Evgeni, Stoynev, Croatia: Stjepan Kranjcevic, Cyprus: Joseph Moutiris, Marios Ioannides, Switzerland: Dominique Evequoz, Czech Republic: Jaroslava Spacilova, Roman, Cerbak, Miroslav, Novak, Martin, Eisenberger, Jolana, Mullerova, Josef, Kautzner, Lucie, Riedlbauchova, Jan, Petru`, Milos, Taborsky, Denmark: Per Thayssen, Helle Cappelen, Sharaf, Egypt: Yasser A., Ibrahim, B. S. S., Khalid, Tammam, Aly, Saad, Helmy, Elghawaby, Hamed Zaky Sherif, Heba, Farouk, Andresen, Germany: D., Arlett, Mielke, Gunter, Breithardt, Markus, Engelen, Paulus, Kirchhof, Pia, Zimmermann, Fernandez Aviles, Spain: F., Jeronimo, Rubio, Malpartida, F., Corona, M., Luis Tercedor Sanchez, Jose Miguel Lozano Herrera, Aurelio, Quesada, Munoz Garcia, Antonio J., Carlos Sanchez Gonzalez, Soledad Alcasena Juango, M., Jesus Berjon Reyero, Alegret, Josep M., Cruz Fernandez, J. M., Cesar Carrascosa Rosillo, Antonio Fernandez Romero, Miguel Gonza´lez Lara, Lopez Sendon, Jose´ L., Jose´ Juan Gomez de Diego, Luis Sosa Martin, Maria, Irurita, Norbero Herrera Guttierez, Juan Ramon Siles Rubio, Isabel, Antorrena, Alicia Bautista Paves, Antonio, Salvador, Maria Dolores Orriach, Alonso Garcia, A., Francisco, Epelde, Vicente Bertomeu Martinez, Antonio Berruezo Sanchez, Carlos Pinero Galvez, Rafael Fernandez Rivero, Antonio Hernandez Madrid, Gonzalo Baron Esquivias, Rafael, Peinado, Jose´ Antonio Gomez Guindal, Tomas Ripoll Vera, Emilio Luengo Fernandez, Ricardo, Gayan, Javier, Garcia, Andres, Bodegas, Jesus Toril Lopez, Julio Martinez Florez, Cristobal Lozano Cabezas, Eduardo Vazquez Ruiz de Castroviejo, Juan Munoz Bellido, Maria Eugenia Ruiz, Finland: Seppo Lehto, Kirsti, Savolainen, Markku, Nieminen, Lauri, Toivonen, Mikko, Syvanne, Mervi, Pietila, France: Daniel Galley, Christine, Beltra, Samuel, Le´vy, Alain, Gay, Daubert, J. C., Guillaume, Lecocq, Christine, Poulain, Cleland, United Kingdom: J. G. F. C., Rhidian, Shelton, Lip, G. Y. H., Choudhury, A., Georgia: Gulnara Abuladze, Irina Jashi, Cokkinos, Greece: Dennis V., Anastasia, Tsiavou, Giamouzis, G., Dagres, N., Kostopoulou, A., Domproglou, Tsoutsanis, Stefanadis, C. h., George, Latsios, Ioannis, Vogiatzis, Alexandros, Gotsis, Paraskevi, Bozia, Maria, Karakiriou, Spyridon, Koulouris, John, Parissis, George, Kostakis, Nikos, Kouris, Dimitra, Kontogianni, Koutroubas, Athanasios, Alexandros, Douras, Themistoklis, Tsanakis, Panos, Vardas, Mary, Marketou, Nikolaos, Patsourakos, Hungary: Laszlo Czopf, Robert, Halmosi, Istvan, Pre´da, Eva, Csoti, Andrea, Badics, Israel: Boris Strasberg, Freedberg, Nahum A., Amos, Katz, Eli, Zalzstein, Aviva, Grosbard, Goldhammer, E., Menachem, Nahir, Menashe, Epstein, Ida, Vider, David, Luria, Lori, Mandelzweig, Italy: Bruno Aloisi, Alfio, Cavallaro, Emanuele, Antonielli, Baldassarre, Doronzo, Diego, Pancaldo, Carlo, Mazzola, Liliana, Buontempi, Valeria, Calvi, Giuseppe, Giuffrida, Antonino, Figlia, Francesco, Ippolito, Gian Paolo Gelmini, Gaibazzi, N., Virgilio, Ziacchi, Francesco De Tommasi, Federico, Lombardi, Cesare, Fiorentini, Paolo, Terranova, Pietro, Maiolino, Muhamad, Albunni, Plinio Pinna Pintor, Stefano, Fumagalli, Guilio, Masotti, Lorenzo, Boncinelli, Domenico, Rossi, Giovanni Maria Santoro, Massimo, Fioranelli, Franco, Naccarella, Stefano Sdringola Maranga, Giovannina, Lepera, Barbara, Bresciani, Elena, Seragnoli, Mara Cantelli Forti, Valentina, Cortina, Giacinto, Baciarello, Paolo, Cicconetti, Antonio, Lax, Federica, Vitali, Diran, Igidbashian, Luisa, Scarpino, Sergio, Terrazzino, Luigi, Tavazzi, Francesco, Cantu, Francesco, Pentimalli, Salvatore, Novo, Giuseppe, Coppola, Gianluca, Zingarini, Giuseppe, Ambrozio, Paolo, Moruzzi, Sergio, Callegari, Gabriele, Saccomanno, Paolo, Russo, Emanuele, Carbonieri, Anna, Paino, Marco, Zanetta, Enzo, Barducci, Roberto, Cemin, Werner, Rauhe, Walter, Pitscheider, Marina, Meloni, Sergio Mariano Marchi, Marco Di Gennaro, Sergio, Calcagno, Paola, Squaratti, Francesco, Quartili, Patrizia, Bertocchi, Mario De Martini, Giuseppe, Mantovani, Roman, Komorovsky, Alessandro, Desideri, Leopoldo, Celegon, Luigi, Tarantini, Giuseppe, Catania, Donata, Lucci, Francesca, Bianchini, Lithuania: Aras Puodziukynas, Ausra, Kavoliuniene, Vilija, Barauskiene, Audrius, Aidietis, Jurate, Barysiene, Vitas, Vysniauskas, Irena, Zukauskiene, Nijole, Kazakeviciene, Macedonia: Ljubica Georgievska Ismail, Lidija Poposka, Moldova: Eleonora Vataman, Aurel A. Grosu, The Netherlands: Wilma Scholte op Reimer, Esther de Swart, Mattie, Lenzen, Jaap, Deckers, Chris, Jansen, Ritzo, Brons, Henriette, Tebbe, van Hoogenhuyze, D. C. A., Veerhoek, M. J., Maria, Kamps, Haan, D., Nitolanda van Rijn, Annette, Bootsma, Leo, Baur, Adrie van den Dool, Harry, Crijns, Robby, Nieuwlaat, Heidi, Fransen, Luc, Eurlings, Joan, Meeder, De Boer, M. J., Jobst, Winter, Herman, Broers, Chris, Werter, Bijl, M., Saskia, Versluis, Poland: Malgorzata Milkowska, Beata Wozakowska Kaplon, Marianna, Janion, Lidia, Lepska, Grazyna, Swiatecka, Piotr, Kokowicz, Jacek, Cybulski, Aleksandr, Gorecki, Marcin, Szulc, Jerzy, Rekosz, Rafal, Manczak, Anna Maria Wnuk Wojnar, Trusz Gluza, M., Anna Rybicka Musialik, Jaroslaw, Myszor, Michal, Szpajer, Krzysztof, Cymerman, Jerzy, Sadowski, Maria Sniezek Maciejewska, Mariola Ciesla Dul, Izabela Gorkiewicz Kot, Tomasz, Grodzicki, Krzysztof, Rewiuk, Leszek, Kubik, Jacek, Lewit, Portugal: Joao Manuel Frazao Rodrigues de Sousa, Rafael, Ferreira, Antonio, Freitas, Joao Carlos Araujo Morais, Rui, Pires, Veloso Gomes, M. J., Paula, Gago, Candeias, Rui Alexandre C., Luis, Nunes, Joao Vitor Miranda Sa, Miguel, Ventura, Mario de Oliveira, Luis Brandao Alves, Romania: Ioan Bostaca, Olariu, Codin T., Dan, G. A., Anca, Dan, Cristian, Podoleanu, Attila, Frigy, Georgescu, George I. M., Catalina, Arsenescu, Cristian, Statescu, Radu, Sascau, Dimitrascu, Dan L., Raluca, Rancea, Shubik, Russian Federation: Yuri V., Dmitry, Duplyakov, Marina, Shalak, Vyacheslav, Mareev, Marine, Danielyan, Albert, Galyavich, Venera, Zakirova, Slovakia: Robert Hatala, Gabriela, Kaliska, Jan, Kmec, Slovenia: Igor Zupan, Jerneja, Tasie`, Damijan, Vokac, org at Arcuri DFM 96 on April 27, Sweden: Nils 2432 R. Nieuwlaat Downloaded from e. u. r. h. e. a. r. t. j. o. x. f. o. r. d. j. o. u. r. n. a. l. s., 2010, Edvardsson, Dritan, Poci, Tunisia: Habib Gamra, Hichem Denguir, Turkey: Tugrul Okay, Ahmet, Sepetoglu, Alev Arat Ozkan, Ukraine: Mariya Orynchak, Elena, Paliy, Vakalyuk, I., Oleg, Sychov, David, Malidze, Rostyslav, Prog, Myckola Ivanovich Yabluchansky, Nataliya Volodimirovna Makienko, Serbia, Montenegro: Tatjana Potpara, Sofija, Knezevic, and Miomir, Randjelovic
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medicine.medical_specialty ,Heart disease ,business.industry ,MEDLINE ,Atrial fibrillation ,Rhythm control ,medicine.disease ,Asymptomatic ,Heart failure ,Internal medicine ,Concomitant ,medicine ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,Intensive care medicine ,business ,Prospective cohort study - Abstract
Aims To describe atrial fibrillation (AF) management in member countries of the European Society of Cardiology (ESC) and to verify cardiology practices against guidelines. Methods and results Among 182 hospitals in 35 countries, 5333 ambulant and hospitalized AF patients were enrolled, in 2003 and 2004. AF was primary or secondary diagnosis, and was confirmed on ECG in the preceding 12 months. Clinical type of AF was reported to be first detected in 978, paroxysmal in 1517, persistent in 1167, and permanent in 1547 patients. Concomitant diseases were present in 90% of all patients, causing risk factors for stroke to be also highly prevalent (86%). As many as 69% of patients were symptomatic at the time of the survey; among asymptomatic patients, 54% were previously experienced symptoms. Oral anticoagulation was prescribed in 67 and 49% of eligible and ineligible patients, respectively. A rhythm control strategy was applied in 67% of currently symptomatic patients and in 44% of patients who never experienced symptoms. Conclusion This survey provides a unique snapshot of current AF management in ESC member countries. Discordance between guidelines and practice was found regarding several issues on stroke prevention and antiarrhythmic therapy.
- Published
- 2005
87. First direct implementation of a true random source on programmable hardware
- Author
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Gianluca Setti, Sergio Callegari, and Riccardo Rovatti
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Rapid prototyping ,Exploit ,Markov chain ,business.industry ,Computer science ,Applied Mathematics ,Chaotic ,Computer Science Applications ,Electronic, Optical and Magnetic Materials ,Computer engineering ,Robustness (computer science) ,Embedded system ,Field-programmable analog array ,sort ,Electrical and Electronic Engineering ,Field-programmable gate array ,business - Abstract
True random sources are not implementable in digital hardware, so that many practical applications have historically relied on pseudo-random generators in order to avoid the potentially long prototyping times and the costs of dedicated analog design. However, pseudo-random sources have liabilities that make them hardly suitable for some tasks (notably security related ones). Previous attempts to conciliate security, cost-effectiveness, and rapid development included the exploitation of the analog accessory parts often present on programmable devices. In these designs some analog blocks are used for their side effects (noise amplification) rather than for their originally intended behaviour. Conversely, here we report a direct implementation of a true random source on programmable, low-cost, general-purpose hardware, where all blocks are used only for their nominal function. To the best of the authors' knowledge, this is the first proposal of this sort. The design exploits an FPAA, and is based on a non-linear system exhibiting chaotic behaviour. Measures confirm the correct operation, high throughput, and robustness of the system. Copyright © 2005 John Wiley & Sons, Ltd.
- Published
- 2005
88. Regional left atrial interstitial remodeling in patients with chronic atrial fibrillation undergoing mitral-valve surgery
- Author
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Carlo Pappone, Sergio Callegari, Domenico Corradi, Paolo Pastori, Simone Calvi, Simona Nascimbene, Stefano Benussi, Roberta Maestri, Ottavio Alfieri, Ettore Astorri, Corradi, D, Callegari, S, Benussi, S, Nascimbene, S, Pastori, P, Calvi, S, Maestri, R, Astorri, E, Pappone, C, and Alfieri, Ottavio
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Adult ,Male ,medicine.medical_specialty ,Heart disease ,Radiofrequency ablation ,medicine.medical_treatment ,Heart Valve Diseases ,Pathology and Forensic Medicine ,Pulmonary vein ,law.invention ,Fibrosis ,law ,Internal medicine ,Mitral valve ,Atrial Fibrillation ,medicine ,Humans ,Atrial Appendage ,Sinus rhythm ,Molecular Biology ,Aged ,Aged, 80 and over ,business.industry ,Myocardium ,Atrial fibrillation ,Cell Biology ,General Medicine ,Middle Aged ,Ablation ,medicine.disease ,medicine.anatomical_structure ,Chronic Disease ,cardiovascular system ,Cardiology ,Mitral Valve ,Female ,business - Abstract
Ablation of the left atrial free wall around the pulmonary vein ostia (LAFW) may be effective in the treatment of chronic atrial fibrillation associated with mitral disease (CAF-MVD). Using light and conventional electron microscopy analyses, we wanted to evaluate, in CAF-MVD, the interstitial remodeling in the LAFW as well as in a more remote region, such as the left atrial appendage (LAA). LAFW and LAA samples were obtained from 33 CAF-MVD patients during combined mitral surgery and radiofrequency ablation and from 16 autoptic controls. Interstitial fibrosis (IF) and perivascular fibrosis (PF), capillary densities and the maximal oxygen diffusion distance were morphometrically determined. In CAF-MVD patients, the LAFW, compared with the LAA, showed a higher percentage of IF (7.16+/-3.23% versus 2.51+/-1.40%, respectively), a lower myocardial capillary density per mm(2) (830+/-106 versus 989+/-173) and an increased oxygen maximal diffusion distance (19.70+/-1.27 microm versus 18.13+/-1.58 microm). All these values were also significantly different than controls. No differences were found in evaluating PF. At variance with the LAA, in CAF-MVD patients, the LAFW around the pulmonary vein ostia is a region characterized by a marked interstitial remodeling such that it may be morphologically indicated as an appropriate target for ablation treatment aimed at sinus rhythm restoration.
- Published
- 2004
89. Circadian distribution of acute myocardial infarction by anatomic location and coronary artery involvement
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P. Moruzzi, Sergio Callegari, Giancarlo Marenzi, and Mauro Contini
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Adult ,Male ,medicine.medical_specialty ,Sympathetic Nervous System ,Myocardial Infarction ,Infarction ,Coronary Angiography ,Risk Factors ,Coronary Circulation ,Internal medicine ,medicine ,Humans ,cardiovascular diseases ,Myocardial infarction ,Circadian rhythm ,Anatomic Location ,Mathematical Computing ,General Nursing ,Aged ,Retrospective Studies ,Morning ,Aged, 80 and over ,business.industry ,Coronary Thrombosis ,Coronary Stenosis ,Electrocardiography in myocardial infarction ,General Medicine ,Middle Aged ,medicine.disease ,Circadian Rhythm ,Coronary arteries ,medicine.anatomical_structure ,Italy ,cardiovascular system ,Cardiology ,Regression Analysis ,Female ,Cardiology and Cardiovascular Medicine ,business ,Artery - Abstract
Acute myocardial infarction follows a circadian pattern, with a morning peak ascribed to sympathetic activation. However, about 20% of myocardial infarctions occur between midnight and 6 AM; these events may have different characteristics.We studied 1571 patients with acute myocardial infarction (866 anterior and 705 inferior myocardial infarctions) who were admitted to our coronary care units from January 1997 to February 2001. We noted the time of the infarction, its anatomic location, and the involved coronary arteries.Inferior myocardial infarctions were more frequent during the night (midnight to 6 AM) than during other periods of the day (n = 238, 34% of all inferior infarctions, P0.01). When coronary angiography was performed (795 patients), 92% (127/138) of inferior infarctions were due to right coronary artery occlusion, whereas only 54% (130/242) of the remaining inferior infarctions involved that artery.Inferior myocardial infarctions occur disproportionately at night, usually due to right coronary artery occlusion. This suggests that a protective role for sleep may be limited to left coronary artery-related events.
- Published
- 2004
90. Chaos-based FM signals: application and implementation issues
- Author
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Riccardo Rovatti, Sergio Callegari, and Gianluca Setti
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Spread spectrum ,Synchronization of chaos ,Electronic engineering ,Degrees of freedom (statistics) ,Chaotic ,Electrical and Electronic Engineering ,Wideband ,Focus (optics) ,Frequency modulation ,Mixing (physics) ,Mathematics - Abstract
Constant-envelope wideband signals are useful excitations in many engineering tasks. Here, we consider their hardware-based generation, reviewing recent results and adding new ones. We focus on a synthesis technique based on FM modulators and discrete-time chaotic sources. The degrees of freedom offered by this approach are discussed and managed to satisfy common requirements. We show that good rate-of-mixing chaotic sources are highly desirable; then, given that most current-generation chaotic sources do not provide adequate values, we illustrate how their designs can be improved. We conclude by suggesting possible developments regarding weakly mixing chaotic sources.
- Published
- 2003
91. Limit properties of folded sums of chaotic trajectories
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Sergio Callegari, Gianluca Setti, and Riccardo Rovatti
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Discrete mathematics ,Multidimensional signal processing ,Computer simulation ,Stochastic process ,Trajectory ,Chaotic ,Statistical physics ,Limit (mathematics) ,Electrical and Electronic Engineering ,Multidimensional systems ,Domain (mathematical analysis) ,Mathematics - Abstract
We investigate the statistical properties of a process defined by summing the subsequent values assumed by the state of a chaotic map, and by constraining the result within a finite domain by means of a folding operation. It is found that the limit distribution is always uniform regardless of the chaotic map, that the folded sums tend to be independent of the future evolution of the chaotic trajectory, and that, whenever the map state is multidimensional, the folded sum vectors tend to be made of independent components. Numerical simulations are employed to show that practical finite-time behaviors are correctly approximated by the limit results herein provided. Finally, the theory is applied to give a formal ground to some key steps in the derivation of the spectrum of signals that are chaotically frequency modulated.
- Published
- 2002
92. Fundamental performance limits of chaotic-map random number generators
- Author
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Sergio Callegari, Ahmad Beirami, Hamid Nejati, Beirami, Ahmad, Nejati, Hamid, and Callegari, Sergio
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Conditional entropy ,Discrete mathematics ,Information theory ,Metric entropy ,Random number generation ,Chao ,Truly random number generator (TRNG) ,Computer Science Applications ,Entropy power inequality ,Binary entropy function ,Computer Networks and Communication ,Map ,Maximum entropy probability distribution ,Hidden Markov process (HMP) ,Entropy (information theory) ,Algorithm ,Lyapunov exponent ,Mathematics - Abstract
A chaotic-map random number generator (RNG) is defined using a chaotic map and a bit-generation function. When the map function is exactly known, for a given bit-generation function, the entropy-rate of the generated output bit sequence is asymptotically the highest rate at which truly random bits can be generated from the map. The supremum of the entropy-rate amongst all bit-generation functions is called the binary metric entropy, which is the highest rate at which information can be extracted from any given map using the optimal bit-generation function. In this paper, we provide converse and achievable bounds on the binary metric entropy. The achievability is based on a sequence of universal bit-generation functions in the sense that the bit-generation function is not dependent on the specific map. The proposed sequence of bit-generation functions offers a fairly simple implementation which can easily be realized on hardware for practical purposes.
- Published
- 2014
93. Arrhythmia susceptibility in senescent rat hearts
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Michele Miragoli, Sergio Callegari, Luca Carnevali, Emilio Macchi, Domenico Corradi, Andrea Sgoifo, S. Baruffi, Stefano Rossi, and Ezio Musso
- Subjects
medicine.medical_specialty ,Cardiac electrophysiology ,business.industry ,Biochemistry (medical) ,Stimulation ,Plant Science ,Reentry ,Arrhythmogenic substrate ,General Biochemistry, Genetics and Molecular Biology ,Nerve conduction velocity ,Electrophysiology ,lcsh:Biology (General) ,In vivo ,Internal medicine ,aged heart, arrhythmia, epicardial mapping ,cardiovascular system ,medicine ,Cardiology ,Sinus rhythm ,business ,lcsh:QH301-705.5 - Abstract
Cardiovascular disease increases with age as well as alterations of cardiac electrophysiological properties, but a detailed knowledge about changes in cardiac electrophysiology relevant to arrhythmogenesis in the elderly is relatively lacking. The aim of this study was to determine specific age-related changes in electrophysiological properties of the ventricles which can be related to a structural-functional arrhythmogenic substrate. Multiple epicardial electrograms were recorded on the ventricular surface of in vivo control and aged rats, while arrhythmia vulnerability was investigated by premature stimulation protocols. Single or multiple ectopic beats and sustained ventricular arrhythmias were frequently induced in aged but not in control hearts. Abnormal ventricular activation patterns during sinus rhythm and unchanged conduction velocity during point stimulation in aged hearts suggest the occurrence of impaired impulse conduction through the distal Purkinje system that might create a potential reentry substrate.
- Published
- 2014
94. Can a single low-intensity premature stimulus induce ventricular arrhythmias in the normal heart?
- Author
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Sergio Callegari, Luca Carnevali, S. Baruffi, Ezio Musso, Domenico Corradi, Mimosa Trombini, Emilio Macchi, Michele Miragoli, Andrea Sgoifo, and Stefano Rossi
- Subjects
medicine.medical_specialty ,business.industry ,Biochemistry (medical) ,Beat (acoustics) ,Plant Science ,Reentry ,Stimulus (physiology) ,medicine.disease ,premature stimulation, conduction block, reentry circuit, arrhythmia ,General Biochemistry, Genetics and Molecular Biology ,Ventricular myocardium ,lcsh:Biology (General) ,Bigeminy ,Internal medicine ,Anesthesia ,Cardiology ,cardiovascular system ,Medicine ,Repolarization ,business ,Pace mapping ,lcsh:QH301-705.5 ,Normal heart - Abstract
Previously, we observed that a single low-intensity premature ventricular stimulation could occasionally induce spontaneous ectopic beats in normal rat hearts. Possible hypothesis for the arrhythmia is that a premature beat can encounter a zone of conduction block to initiate reentry. However, enhanced dispersion of repolarization, a necessary condition for initiation of reentry, is unlikely to be present in normal myocardium. Thus, the main objective of the present study was to perform detailed pace mapping measurements in normal ventricular myocardium with a view to identify pacing sites and critical coupling intervals which could induce spontaneous ectopic beats and to characterize the reentrant circuits.
- Published
- 2014
95. Very Low Cost Entropy Source Based on Chaotic Dynamics Retrofittable on Networked Devices to Prevent RNG Attacks
- Author
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Sergio Callegari, Mattia Fabbri, Fabbri, Mattia, and Callegari, Sergio
- Subjects
FOS: Computer and information sciences ,Universal asynchronous receiver/transmitter ,Computer Science - Cryptography and Security ,Serial communication ,Firmware ,business.industry ,Computer science ,Chaotic ,Analog-to-digital converter ,Cryptographic protocol ,USB ,computer.software_genre ,Chao ,law.invention ,Microcontroller ,law ,Embedded system ,Hardware Architecture (cs.AR) ,True random number generation ,Microcontrollers ,business ,Computer Science - Hardware Architecture ,computer ,Cryptography and Security (cs.CR) - Abstract
Good quality entropy sources are indispensable in most modern cryptographic protocols. Unfortunately, many currently deployed networked devices do not include them and may be vulnerable to Random Number Generator (RNG) attacks. Since most of these systems allow firmware upgrades and have serial communication facilities, the potential for retrofitting them with secure hardware-based entropy sources exists. To this aim, very low-cost, robust, easy to deploy solutions are required. Here, a retrofittable, sub 10$ entropy source based on chaotic dynamics is illustrated, capable of a 32 kbit/s rate or more and offering multiple serial communication options including USB, I2C, SPI or USART. Operation is based on a loop built around the Analog to Digital Converter (ADC) hosted on a standard microcontroller., Comment: 4 pages, 6 figures. Pre-print from conference proceedings; IEEE 21th International Conference on Electronics, Circuits, and Systems (ICECS 2014), pp. 175-178, Dec. 2014
- Published
- 2014
- Full Text
- View/download PDF
96. Persistent lone atrial fibrillation: Clinicopathologic study of 19 cases
- Author
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Matteo Goldoni, Domenico Corradi, Sergio Callegari, Paola Mozzoni, Gabriella Becchi, David Ferrara, Antonio Mutti, Roberta Andreoli, Ottavio Alfieri, Jeffrey E. Saffitz, Alberto Pozzoli, Silvana Pinelli, Laura Manotti, Angeliki Asimaki, Stefano Benussi, Rossella Alinovi, Corradi, D, Callegari, S, Manotti, L, Ferrara, D, Goldoni, M, Alinovi, R, Pinelli, S, Mozzoni, P, Andreoli, R, Asimaki, A, Pozzoli, A, Becchi, G, Mutti, A, Benussi, S, Saffitz, Je, and Alfieri, Ottavio
- Subjects
Adult ,Male ,medicine.medical_specialty ,Heart disease ,Autopsy ,Periodic acid–Schiff stain ,Interstitial fibrosis ,medicine.disease_cause ,Physiology (medical) ,Internal medicine ,Atrial Fibrillation ,medicine ,Humans ,Sinus rhythm ,Heart Atria ,Aged ,Inflammation ,business.industry ,Myocardium ,Atrial fibrillation ,Atrial Remodeling ,Middle Aged ,medicine.disease ,Oxidative Stress ,Cardiology ,Lone atrial fibrillation ,Female ,Cardiology and Cardiovascular Medicine ,business ,Oxidative stress ,Biomarkers - Abstract
BACKGROUND The extent to which atrial myocardium is remodeled in patients with persistent lone atrial fibrillation (LAF) is largely unknown. OBJECTIVE The purpose of this study was to perform a clinicopathologic investigation in patients with persistent LAF. METHODS We characterized structural and molecular remodeling in atrial biopsies from 19 patients (17 males, mean age 49 years) with persistent (> 7 days; n = 8) or long-lasting persistent (> 1 year; n = 11) LAF who underwent surgical ablation. Atrial tissue from 15 autopsy samples without clinicopathologic evidence of heart disease served as controls. RESULTS Morphometric analysis showed cardiomyocyte hypertrophy and greater amounts of myolytic damage and interstitial fibrosis in persistent LAF patients compared to controls (P
- Published
- 2014
97. Mapping duality as a means to allow finite?F compensation in bipolar log filters
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Sergio Callegari and Gianluca Setti
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Signal processing ,Engineering ,business.industry ,Applied Mathematics ,Duality (optimization) ,Current source ,Analog signal processing ,Computer Science Applications ,Electronic, Optical and Magnetic Materials ,Compensation (engineering) ,law.invention ,Capacitor ,Analog signal ,Band-pass filter ,law ,Electronic engineering ,Electrical and Electronic Engineering ,business - Abstract
Log-domain filters are a promising design paradigm for analog signal processing. They achieve tunability and operation up to high frequencies, with voltage and power requirements typically better than those of conventional filtering architectures. Implementation can be based only on capacitors, current sources and an exponential, differential V/I converter referred to as the E-cell. Non-idealities in the E-cell, like the presence of non-negligible input currents due to finite βF, can reduce system performance. The aim of this paper is to investigate E-cell-based design strategies and to introduce a duality principle whose exploitation can allow finite βF compensation. As a validation, HSPICE simulation results are illustrated for a second-order bandpass filter. Copyright © 2000 John Wiley & Sons, Ltd.
- Published
- 2000
98. Morphology and pathophysiology of target anatomical sites for ablation procedures in patients with atrial fibrillation: part II: pulmonary veins, caval veins, ganglionated plexi, and ligament of Marshall
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Domenico, Corradi, Sergio, Callegari, Sandro, Gelsomino, Roberto, Lorusso, and Emilio, Macchi
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Electrocardiography ,Ganglia, Sympathetic ,Heart Conduction System ,Pulmonary Veins ,Atrial Fibrillation ,Catheter Ablation ,Humans ,Heart Atria ,Venae Cavae - Abstract
The inadequate long-term efficacy of anti-arrhythmic therapy has been one of the main reasons for the development of non-pharmacological interventions for patients with atrial fibrillation such as catheter and surgical ablation. This has greatly increased interest in the functional morphology and electrophysiological properties of the atria and related anatomical structures. This article is the second of a two-part review that aims to provide anatomical and functional details concerning some of the principal anatomical sites commonly targeted by ablative procedures for treating atrial fibrillation, and covers pulmonary veins, ganglionated plexi, caval veins, and the ligament of Marshall. It also provides some general information about site-specific ablation procedures.
- Published
- 2013
99. On the usage of resonate and fire dynamics in the complex oscillation-based test approach
- Author
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Sergio, Callegari, Pareschi, Fabio, Setti, Gianluca, and Mani, Soma
- Published
- 2013
100. Should ΔΣ modulators used in AC motor drives be adapted to the mechanical load of the motor?
- Author
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Federico Bizzarri and Sergio Callegari
- Subjects
Physics ,Signal-to-noise ratio ,Mechanical load ,Control theory ,Sigma ,Order (ring theory) ,Delta-sigma modulation ,AC motor ,Noise (electronics) ,Pulse-width modulation - Abstract
We consider the use of {\Delta}{\Sigma} modulators in ac motor drives, focusing on the many additional degrees of freedom that this option offers over Pulse Width Modulation (PWM). Following some recent results, we show that it is possible to fully adapt the {\Delta}{\Sigma} modulator Noise Transfer Function (NTF) to the rest of the drive chain and that the approach can be pushed even to a fine adaptation of the NTF to the specific motor loading condition. We investigate whether and to what extent the adaptation should be pursued. Using a representative test case and extensive simulation, we conclude that a mild adaptation can be beneficial, leading to Signal to Noise Ratio (SNR) improvements in the order a few dB, while the advantage pushing the adaptation to the load tracking is likely to be minimal.
- Published
- 2012
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