1,720,975 research outputs found
Wireless ECG and cardiac monitoring systems: State of the art, available commercial devices and useful electronic components
No full textWireless ElectroCardioGram (ECG) systems are employed in manifold application fields: tele-monitoring, sport applications, support to ageing people at home, fetal ECG, wearable devices and ambulatory monitoring. The presence of cables often hinders user’s free movements, alongside clinicians’ routine operations. Therefore, wireless ECG systems are desirable. This paper aims at reviewing the solutions described in the literature, besides commercially available devices and electronic components useful to setup laboratory prototypes. Several systems have been developed, different in terms of the adopted technology; when approaching the development of a wireless ECG system, some important aspects should be considered: electrodes (disposable, wet/dry, without contact, insulated), analog front-end, data acquisition systems (including amplifiers, multiplexer), wireless transmission technology (e.g. WiFi, Bluetooth) and power consumption (battery lifetime, miniaturization purposes). Technological advancements and continuous research have already brought to miniaturized and comfortable devices, but there is still room for improvement on multiple sides
A Preliminary Study on Arterial Stiffness Assessment Using Photoplethysmographic Sensors
Full text linkCardiovascular diseases represent the cause of 31% of all global deaths. Unfortunately, there are many difficulties in diagnosing them in a preventive, non-invasive and inexpensive way. However, there are important risk markers, including arterial stiffness. The current reference technique for assessing aortic stiffness is the measurement of Pulse Wave Velocity, and a commonly used mathematical model is the Moens–Korteweg equation, which relates Pulse Wave Velocity to arterial stiffness. A pair of photoplethysmographic sensors was used in this study to estimate Pulse Wave Velocity and, consequently, arterial stiffness on silicone phantom models with different geometric and mechanical properties. These models were placed in an experimental in vitro system that simulated the physiological conditions of a cardiovascular apparatus. The PPG sensors were positioned at three specific distances to determine a possible optimal distance for the estimation of arterial stiffness. The purpose of this study is to enhance the use of PPG sensors for monitoring the mechanical properties of blood vessels and, thus, to prevent potential cardiovascular pathologies
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
STUDIO E VALIDAZIONE DI SISTEMI PER L’IDENTIFICAZIONE E IL MONITORAGGIO DI PARAMETRI BIOMEDICI ATTI ALLA PREVENZIONE DI EVENTI INDESIDERATI E ALL’ASSISTENZA DI INDIVIDUI CON DIVERSE TIPOLOGIE DI RISCHIO SANITARIO
Full text linkL’aumento delle patologie cronico-degenerative nella popolazione mondiale ha comportato un numero sempre maggiore di individui richiedenti assistenza sanitaria, generando, nell’ambito delle realtà ospedaliere, diverse problematiche relative al miglioramento della qualità di vita dei pazienti, ai costi e alla gestione di un numero sempre crescente di soggetti ammalati.
Il trattamento sanitario e la ricerca di base si sono pertanto orientati verso la prevenzione delle condizioni che predispongono i soggetti ai peggioramenti clinici e ai ricoveri ospedalieri, puntando sia su nuovi sistemi indossabili di monitoraggio per individuare precocemente i segni di peggioramento, sia su sistemi che possano “prevedere” l’efficacia di una terapia, prima che venga messa in atto.
Sulla base di queste premesse, l’attività di ricerca che verrà presentata si è incentrata su due studi differenti ma con lo stesso obiettivo, ovvero quello di migliorare l’acquisizione di parametri caratteristici dell’apparato cardiocircolatorio per aumentare l’efficacia dei trattamenti clinici.
Nella prima parte verrà presentato uno studio fluidodinamico applicato su modelli di aorta di pazienti portatori di sistemi di assistenza ventricolare a flusso continuo, che spesso vanno incontro a problemi legati all’assenza di pulsatilità. Attraverso analisi in silico, esperimenti in vitro su modelli ricreati da immagini reali di risonanza e l’utilizzo di tecniche di quantificazione di flusso ECO e PIV, si è riusciti a delineare un parametro predittivo sul rischio di complicazioni basato su determinati parametri morfologici di alcuni tratti aortici. Il sistema potrebbe fornire un parametro di rischio per ciascun soggetto candidato all’impianto, mettendo a disposizione dei clinici un database dei pazienti più a rischio ai quali destinare maggiore attenzione e controlli.
La seconda parte dello studio ha visto lo sviluppo di una nuova tecnologia, integrabile in bracciali da polso, in grado di misurare la pressione arteriosa mediante l’utilizzo di sensori fotopletismografici (PPG), già largamente diffusi in diversi prodotti commerciali ad uso clinico e sportivo (e.g. smartwatch, pulsossimetri) e in atto usati per misurare la frequenza cardiaca e l’ossigenazione del sangue.
Tale tecnologia è stata validata per mezzo di una sperimentazione in vivo che ha visto il coinvolgimento di 25 soggetti e i cui esiti sono stati in linea con le aspettative e hanno permesso di ottimizzare il successivo prototipo.
La metodologia di misura della pressione con questa nuova tecnologia si è dimostrata affidabile, evidenziando, nelle prime prove sperimentali, un errore intorno all’ 8 % nell’individuazione della finestra temporale in cui si è raggiunta la pressione sistolica del soggetto all’interno del braccialetto gonfiabile in una specifica sede di misura. Si candida pertanto ad un potenziale utilizzo clinico, domestico e sportivo, in soggetti che necessitino di un monitoraggio continuo della pressione per controllare il proprio stato di salute o individuare possibili peggioramenti
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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