1,721,009 research outputs found
Dalla ricerca al mercato - Trasformare il risultato della ricerca in un prodotto
No full textVolume contenente i contributi della Scuola Annuale di Bioingegneria del 2012 sul trasferimento tecnologico
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
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
Quantitative assessment of fetal well-being through CTG recordings: a new parameter based on Phase Rectified Signal Average
No full textCardiotocography (CTG) represents a standard approach to monitor fetal well being during pregnancy. It is based on the simultaneous recording of the fetal heart rate (FHR) signal and uterine contractions. The necessity to reduce inter- and intra-observer variability in the interpretation of CTG tracings has brought researchers to define new parameters to reliably quantify FHR variability. In this paper, a new parameter based on the Phase Rectified Signal Average (PRSA) curve is introduced. The parameter is defined as the slope of the PRSA curve, namely Acceleration Phase Rectified Slope (APRS) or Deceleration Phase Rectified Slope (DPRS), depending on the sign of the slope. The parameter was applied to FHR time series acquired from healthy and IUGR fetuses during a CTG non-stress test. The performance of APRS and DPRS was compared with the performance of other parameters extracted from the PRSA curve already existing in literature, and with other clinical indices that are provided by computerized cardiotocographic systems. The APRS and DPRS performed better than any other parameter considered in this study to distinguish between healthy and IUGR fetuses. We believe that this new index might be useful to improve the quality of fetus early diagnosis
A model of two nonlinear coupled oscillators for the study of heartbeat dynamics
No full textThe cardiac conduction system may be assumed to be a network of self-excitatory pacemakers, with the SinoAtrial (SA) node having the highest intrinsic rate. Subsidiary pacemakers with slower firing frequencies are located in the AtrioVentricular (AV) node and the His-Purkinje system. Under physiological conditions, the SA node is the dominant pace-maker and impulses travel from this node to the ventricle through the AV junction, which is traditionally regarded as a passive conduit. We consider the AV node as an active pace-maker and develop a model of two nonlinear coupled oscillators in order to describe the interaction between the SA and the AV node. These two nonlinear oscillators are based on a modification of the van der Pol oscillator, so that the generated waveforms resemble the action potentials of cells in the SA and the AV node respectively. A bifurcation analysis of this model is performed and the pathophysiological meaning of each bifurcation is explained. We show how it is possible to simulate and classify different kinds of heartbeat pathologies (1 degrees, 2 degrees (both Wenckebach and non-Wenckebach) and 3 degrees AV blocks, sinus arrest, atrial bigeminy, etc.). This simple nonlinear model helps to improve the understanding of the complex phenomena involved in heart rhythm generation as well as of heart rate control and function
New Indices Extracted from Fetal Heart Rate Signal for the Assessment of Fetal Well-Being
No full textIn this paper, new parameters based on the Phase Rectified Signal Average (PRSA) of the Fetal Heart Rate (FHR) signal are introduced to assess fetal wellbeing. They are defined as the positive and negative slopes of the PRSA curve, namely Acceleration Phase Rectified Slope (APRS) and Deceleration Phase Rectified Slope (DPRS), depending on the sign of the slope. The parameters were computed on FHR time series recorded from 59 healthy and 61 Intra Uterine Growth Restricted (IUGR) fetuses, during CTG non-stress tests. The performance of APRS and DPRS was compared with the performance of other parameters extracted from the PRSA curve already existing in literature, and with other clinical indices that are provided by computerized cardiotocographic systems. The APRS and DPRS performed better than any other parameter considered in this study to distinguish between healthy and IUGR fetuses. We believe that these new indices might provide useful improvements of the quality of fetus early diagnosis. © Springer International Publishing Switzerland 2014
Simulation of heartbeat dynamics: A nonlinear model
No full textThe mathematical modeling of biological systems has proven to be a valuable tool by allowing experiments which would otherwise be unfeasible in a real situation. In this work we propose a system of nonlinear differential equations describing the macroscopic behavior of the cardiac conduction system. The model describes the interaction between the SinoAtrial and AtrioVentricular node. Its very simple structure consists of two nonlinear oscillators resistively coupled. The numerical analysis detects different kinds of bifurcations whose pathophysiological meanings are discussed. Moreover, the model is able to classify different pathologies, such as several classes of arrhythmic events, as well as to suggest hypothesis on the mechanisms that induce them. These results also show that the mechanisms generating the heartbeat obey complex laws. The model provides a quite complete description of different pathological phenomena and its simplicity can be exploited for further studies on the control of cardiac dynamics
Telefetalcare: a first prototype of a wearable fetal electrocardiograph
No full textFetal heart rate monitoring is fundamental to infer information about fetal health state during pregnancy. The cardiotocography (CTG) is the most common antepartum monitoring technique. Abdominal ECG recording represents the most valuable alternative to cardiotocography, as it allows passive, non invasive and long term fetal monitoring. Unluckily fetal ECG has low SNR and needs to be extracted from abdominal recordings using ad hoc algorithms. This work describes a prototype of a wearable fetal ECG electrocardiograph. The system has flat band frequency response between 1-60 Hz and guarantees good signal quality. It was tested on pregnant women between the 30(th) and 34(th) gestational week. Several electrodes configurations were tested, in order to identify the best solution. Implementation of a simple algorithm for FECG extraction permitted the reliable detection of maternal and fetal QRS complexes. The system will allow continuative and deep screening of fetal heart rate, introducing the possibility of home fetal monitoring
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