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Search Results: 1 - 10 of 3689 matches for " Pecchia Leandro "
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Nonlinear Heart Rate Variability features for real-life stress detection. Case study: students under stress due to university examination
Paolo Melillo, Marcello Bracale, Leandro Pecchia
BioMedical Engineering OnLine , 2011, DOI: 10.1186/1475-925x-10-96
Abstract: 42 students volunteered to participate to the study about HRV and stress. For each student, two recordings were performed: one during an on-going university examination, assumed as a real-life stressor, and one after holidays. Nonlinear analysis of HRV was performed by using Poincaré Plot, Approximate Entropy, Correlation dimension, Detrended Fluctuation Analysis, Recurrence Plot. For statistical comparison, we adopted the Wilcoxon Signed Rank test and for development of a classifier we adopted the Linear Discriminant Analysis (LDA).Almost all HRV features measuring heart rate complexity were significantly decreased in the stress session. LDA generated a simple classifier based on the two Poincaré Plot parameters and Approximate Entropy, which enables stress detection with a total classification accuracy, a sensitivity and a specificity rate of 90%, 86%, and 95% respectively.The results of the current study suggest that nonlinear HRV analysis using short term ECG recording could be effective in automatically detecting real-life stress condition, such as a university examination.Stress has been investigated as a risk factor for cardiovascular disease [1] and for reduced human performances, which in some situation, such as dangerous works or driving a car, may results in negative consequences. Stress influences the balance of Autonomous Nervous System (ANS)[2].HRV is a non-invasive measure reflecting the variation over time of the period between consecutive heartbeats (RR intervals) [3] and has been proved to be a reliable marker of ANS activity [3].For this reason, several studies investigated cardiovascular reaction induced by stress using Heart Rate Variability (HRV) focussing on acute, laboratory stressors: cognitive (e.g., mental arithmetic) [4-6], psychomotor (e.g., mirror tracing) [4] challenges and physical stressors[7-9]. Moreover, as standard laboratory stressors do not always engage subjects' affective response, real life stressors (e.g. precompetitive anxi
Heart rate variability and target organ damage in hypertensive patients
Melillo Paolo,Izzo Raffaele,De Luca Nicola,Pecchia Leandro
BMC Cardiovascular Disorders , 2012, DOI: 10.1186/1471-2261-12-105
Abstract: Background We evaluated the association between linear standard Heart Rate Variability (HRV) measures and vascular, renal and cardiac target organ damage (TOD). Methods A retrospective analysis was performed including 200 patients registered in the Regione Campania network (aged 62.4 ± 12, male 64%). HRV analysis was performed by 24-h holter ECG. Renal damage was assessed by estimated glomerular filtration rate (eGFR), vascular damage by carotid intima-media thickness (IMT), and cardiac damage by left ventricular mass index. Results Significantly lower values of the ratio of low to high frequency power (LF/HF) were found in the patients with moderate or severe eGFR (p-value < 0.001). Similarly, depressed values of indexes of the overall autonomic modulation on heart were found in patients with plaque compared to those with a normal IMT (p-value <0.05). These associations remained significant after adjustment for other factors known to contribute to the development of target organ damage, such as age. Moreover, depressed LF/HF was found also in patients with left ventricular hypertrophy but this association was not significant after adjustment for other factors. Conclusions Depressed HRV appeared to be associated with vascular and renal TOD, suggesting the involvement of autonomic imbalance in the TOD. However, as the mechanisms by which abnormal autonomic balance may lead to TOD, and, particularly, to renal organ damage are not clearly known, further prospective studies with longitudinal design are needed to determine the association between HRV and the development of TOD.
Pupillometric analysis for assessment of gene therapy in Leber Congenital Amaurosis patients
Melillo Paolo,Pecchia Leandro,Testa Francesco,Rossi Settimio
BioMedical Engineering OnLine , 2012, DOI: 10.1186/1475-925x-11-40
Abstract: Background Objective techniques to assess the amelioration of vision in patients with impaired visual function are needed to standardize efficacy assessment in gene therapy trials for ocular diseases. Pupillometry has been investigated in several diseases in order to provide objective information about the visual reflex pathway and has been adopted to quantify visual impairment in patients with Leber Congenital Amaurosis (LCA). In this paper, we describe detailed methods of pupillometric analysis and a case study on three Italian patients affected by Leber Congenital Amaurosis (LCA) involved in a gene therapy clinical trial at two follow-up time-points: 1 year and 3 years after therapy administration. Methods Pupillary light reflexes (PLR) were measured in patients who had received a unilateral subretinal injection in a clinical gene therapy trial. Pupil images were recorded simultaneously in both eyes with a commercial pupillometer and related software. A program was generated with MATLAB software in order to enable enhanced pupil detection with revision of the acquired images (correcting aberrations due to the inability of these severely visually impaired patients to fixate), and computation of the pupillometric parameters for each stimulus. Pupil detection was performed through Hough Transform and a non-parametric paired statistical test was adopted for comparison. Results The developed program provided correct pupil detection also for frames in which the pupil is not totally visible. Moreover, it provided an automatic computation of the pupillometric parameters for each stimulus and enabled semi-automatic revision of computerized detection, eliminating the need for the user to manually check frame by frame. With reference to the case study, the amplitude of pupillary constriction and the constriction velocity were increased in the right (treated eye) compared to the left (untreated) eye at both follow-up time-points, showing stability of the improved PLR in the treated eye. Conclusions Our method streamlined the pupillometric analyses and allowed rapid statistical analysis of a range of parameters associated with PLR. The results confirm that pupillometry is a useful objective measure for the assessment of therapeutic effect of gene therapy in patients with LCA. Trial registration ClinicalTrials.gov NCT00516477
User needs elicitation via analytic hierarchy process (AHP). A case study on a Computed Tomography (CT) scanner
Pecchia Leandro,Martin Jennifer L,Ragozzino Angela,Vanzanella Carmela
BMC Medical Informatics and Decision Making , 2013, DOI: 10.1186/1472-6947-13-2
Abstract: Background The rigorous elicitation of user needs is a crucial step for both medical device design and purchasing. However, user needs elicitation is often based on qualitative methods whose findings can be difficult to integrate into medical decision-making. This paper describes the application of AHP to elicit user needs for a new CT scanner for use in a public hospital. Methods AHP was used to design a hierarchy of 12 needs for a new CT scanner, grouped into 4 homogenous categories, and to prepare a paper questionnaire to investigate the relative priorities of these. The questionnaire was completed by 5 senior clinicians working in a variety of clinical specialisations and departments in the same Italian public hospital. Results Although safety and performance were considered the most important issues, user needs changed according to clinical scenario. For elective surgery, the five most important needs were: spatial resolution, processing software, radiation dose, patient monitoring, and contrast medium. For emergency, the top five most important needs were: patient monitoring, radiation dose, contrast medium control, speed run, spatial resolution. Conclusions AHP effectively supported user need elicitation, helping to develop an analytic and intelligible framework of decision-making. User needs varied according to working scenario (elective versus emergency medicine) more than clinical specialization. This method should be considered by practitioners involved in decisions about new medical technology, whether that be during device design or before deciding whether to allocate budgets for new medical devices according to clinical functions or according to hospital department.
A feasibility study for the provision of electronic healthcare tools and services in areas of Greece, Cyprus and Italy
Stavroula G Mougiakakou, Efthyvoulos Kyriacou, Kostas Perakis, Homer Papadopoulos, Aggelos Androulidakis, Georgios Konnis, Riccardo Tranfaglia, Leandro Pecchia, Umberto Bracale, Constantinos Pattichis, Dimitrios Koutsouris
BioMedical Engineering OnLine , 2011, DOI: 10.1186/1475-925x-10-49
Abstract: The support of primary healthcare, home care and the continuous education of physicians are the three major issues that the proposed platform is trying to facilitate. The proposed system is based on state-of-the-art telemedicine systems and is able to provide the following healthcare services: i) Telecollaboration and teleconsultation services between remotely located healthcare providers, ii) telemedicine services in emergencies, iii) home telecare services for "at risk" citizens such as the elderly and patients with chronic diseases, and iv) eLearning services for the continuous training through seminars of both healthcare personnel (physicians, nurses etc) and persons supporting "at risk" citizens.These systems support data transmission over simple phone lines, internet connections, integrated services digital network/digital subscriber lines, satellite links, mobile networks (GPRS/3G), and wireless local area networks. The data corresponds, among others, to voice, vital biosignals, still medical images, video, and data used by eLearning applications. The proposed platform comprises several systems, each supporting different services. These were integrated using a common data storage and exchange scheme in order to achieve system interoperability in terms of software, language and national characteristics.The platform has been installed and evaluated in different rural and urban sites in Greece, Cyprus and Italy. The evaluation was mainly related to technical issues and user satisfaction. The selected sites are, among others, rural health centers, ambulances, homes of "at-risk" citizens, and a ferry.The results proved the functionality and utilization of the platform in various rural places in Greece, Cyprus and Italy. However, further actions are needed to enable the local healthcare systems and the different population groups to be familiarized with, and use in their everyday lives, mature technological solutions for the provision of healthcare services.The sou
How to reconcile Information theory and Gibbs-Herz entropy for inverted populated systems
Alessio Gagliardi,Alessandro Pecchia
Physics , 2015,
Abstract: In this paper we discuss about the validity of the Shannon entropy functional in connection with the correct Gibbs-Hertz probability distribution function. We show that there is no contradiction in using the Shannon-Gibbs functional and restate the validity of information theory applied to equilibrium statistical mechanics. We show that under these assumptions, entropy is always a monotone function of energy, irrespective to the shape of the density of states, leading always to positive temperatures even in the case of inverted population systems. In the second part we assume the validity of the Shannon entropy and thermodynamic temperature, T=dE/dS, extended to systems under non-equilibrium steady state. Contrary to equilibrium, we discuss the possibility and meaning of a negative temperature in this case. Finally we discuss on Carnot cycles operating with a non-equilibrium bath possessing a negative temperature and leading to apparent efficiencies larger than one, due to a wrong accounting af all the energy and entropy fluxes present in the system, including the external driving forces.
Stable Panoramic Views Facilitate Snap-Shot Like Memories for Spatial Reorientation in Homing Pigeons
Tommaso Pecchia, Anna Gagliardo, Giorgio Vallortigara
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0022657
Abstract: Following spatial disorientation, animals can reorient themselves by relying on geometric cues (metric and sense) specified both by the macroscopic surface layout of an enclosed space and prominent visual landmarks in arrays. Whether spatial reorientation in arrays of landmarks is based on explicit representation of the geometric cues is a matter of debate. Here we trained homing pigeons (Columba livia) to locate a food-reward in a rectangular array of four identical or differently coloured pipes provided with four openings, only one of which allowed the birds to have access to the reward. Pigeons were trained either with a stable or a variable position of the opening on pipes, so that they could view the array either from the same or a variable perspective. Explicit mapping of configural geometry would predict successful reorientation irrespective of access condition. In contrast, we found that a stable view of the array facilitated spatial learning in homing pigeons, likely through the formation of snapshot-like memories.
DFT modelling of bulk-modulated carbon nanotube field-effect transistors
L. Latessa,A. Pecchia,A. Di Carlo
Physics , 2005,
Abstract: We report density-functional theory (DFT), atomistic simulations of the non-equilibrium transport properties of carbon nanotube (CNT) field-effect transistors (FETs). Results have been obtained within a self-consistent approach based on the non-equilibrium Green's functions (NEGF) scheme. Our attention has been focused on a new kind of devices, the so called bulk-modulated CNTFETs. Recent experimental realizations \cite{Chen,Lin_condMat} have shown that such devices can exhibit excellent performances, even better than state-of-the-art Schottky barrier (SB)-modulated transistors. Our calculations have been intended to explore, at an atomistic level, the physical mechanisms governing the transport in these new devices. We emphasize the role that one-dimensional screening has on gate- and drain-induced current modulation mechanisms, pointing out, at the same time, the importance of a correct evaluation of the nanotube quantum capacitance. The operative regimes and the performance limits of the device are analysed, pointing out, at the same time, the role played by the quasi-one-dimensional, short channel effects.
Kinetic and thermodynamic temperatures in quantum systems
Alessio Gagliardi,Alessandro Pecchia,Aldo Di Carlo
Physics , 2013,
Abstract: In this work we present a formalism to describe non equilibrium conditions in systems with a discretized energy spectrum, such as quantum systems. We develop a formalism based on a combination of Gibbs-Shannon entropy and information thermodynamics that arrives to a generalization of the De-Brujin identity applicable to discrete and non-symmetric distributions. This allows to define the concept of a thermodynamic temperature with a different, albeit complementary meaning to the equilibrium kinetic temperature of a system. The theory is applied to Bosonic and Fermionic cases represented by an harmonic oscillator and a single energy state, respectively. We show that the formalism correctly recovers known results at equilibrium, then we demonstrate an application to a genuine non equilibrium state: a coherent quantum oscillator.
Development and Application of MCNP5 and KENO-VI Monte Carlo Models for the Atucha-2 PHWR Analysis
M. Pecchia,C. Parisi,F. D'Auria,O. Mazzantini
Science and Technology of Nuclear Installations , 2011, DOI: 10.1155/2011/683147
Abstract: The geometrical complexity and the peculiarities of Atucha-2 PHWR require the adoption of advanced Monte Carlo codes for performing realistic neutronic simulations. Core models of Atucha-2 PHWR were developed using both MCNP5 and KENO-VI codes. The developed models were applied for calculating reactor criticality states at beginning of life, reactor cell constants, and control rods volumes. The last two applications were relevant for performing successive three dimensional neutron kinetic analyses since it was necessary to correctly evaluate the effect of each oblique control rod in each cell discretizing the reactor. These corrective factors were then applied to the cell cross sections calculated by the two-dimensional deterministic lattice physics code HELIOS. These results were implemented in the RELAP-3D model to perform safety analyses for the licensing process. 1. Introduction In the framework of the agreement NA-SA-University of Pisa no. 2”, several technical and research activities are being performed at the GRNSPG of the University of Pisa, in order to analyze the main characteristics of the plant and its behavior during normal and accidental conditions. In this paper, we present the activities performed using the Monte Carlo MCNP5 and KENO-VI codes, or the Atucha-2 full-core model development, some criticality calculations, its use for the RELAP5-3D three-dimensional neutron kinetics model development and validation, and then a result of a transient calculation using the validated RELAP5-3D model. Atucha-2 is a 693?MWe Siemens designed PHWR under construction in the Republic of Argentina (see Figure 1). Its core is composed by 451 fuel bundles placed in vertical Fuel Channels which are arranged in a triangular lattice inside a large PWR-type reactor pressure vessel (RPV). A 6-meter in diameter moderator tank is located inside the RPV, containing the moderator at the full operating pressure (11.5?MPa). Power control is achieved by changing the moderator temperature by an external cooling circuit, and by the use of 12 of the 18 oblique control rods. Reactor shutdown is obtained by all the 18 oblique CRs and by an ad hoc system (the KBC system) that allows to dose a uniform Boron concentration into the moderator and coolant. Instead, during some accidental conditions, a fully independent shut-down system (the JDJ) allows the fast injection of a highly concentrated Boron solution in the moderator tank [1]. Figure 1: Atucha-2 NPP layout. After the definition of a relevant core status with fuel at the burnup equilibrium, a set of neutron cross
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