1,721,023 research outputs found
Test ergometrico precoce e riabilitazione dopo infarto miocardico in età giovanile: risultati e significato prognostico
No full textAttenuation of lung protein synthesis in patients with chronic heart failure on beta-blocker therapy
No full textExtracting features from poincaré plots to distinguish congestive heart failure patients according to nyha classes
No full textHeart-rate variability has proved a valid tool in prognosis definition of patients with congestive heart failure (CHF). Previous research has documented Poincaré plot analysis as a valuable approach to study heart-rate variability performance among different subjects. In this paper, we explored the possibility to feed machine-learning (ML) algorithms using unconventional quantitative parameters extracted from Poincaré plots (generated from 24-h electrocardiogram recordings) to classify patients with CHF belonging to different New York Heart Association (NYHA) classes. We performed in sequence the following investigations: first, a statistical analysis was carried out on 9 morphological parameters, automatically measured from Poincaré plots. Subsequently, a feature selection through a wrapper with a 10-fold cross-validation method was performed to find the best subset of features which maximized the classification accuracy for each considered ML algorithm. Finally, patient classification was assessed through a ML analysis using AdaBoost of Decision Tree, k-Nearest Neighbors and Naive Bayes algorithms. A univariate statistical analysis proved 5 out of 9 parameters presented statistically significant differences among patients of distinct NYHA classes; similarly, a multivariate logistic regression confirmed the importance of the parameter ρy in the separability between low-risk and high-risk classes. The ML analysis achieved promising results in terms of evaluation metrics (especially the Naive Bayes algorithm), with accuracies greater than 80% and Area Under the Receiver Operating Curve indices greater than 0.7 for the overall three algorithms. The study indicates the proposed features have a predictive power to discriminate the NYHA classes, to which the features seem evenly correlated. Despite the NYHA classification being subjective and easily recognized by cardiologists, the potential relevance in the clinical cardiology of the proposed features and the promising ML results implies the methodology could be a valuable approach to automatically classify CHF. Future investigations on enriched datasets may further confirm the presented evidence
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Altered amino acid metabolism in patients with cardiorenal syndrome type 2: Is it a problem for protein and exercise prescriptions?
No full textThe goal of this retrospective study was to document any alterations in plasma amino acids (AAs) in subjects with cardiorenal syndrome type 2 (CRS 2). We analyzed data from sixteen patients with CRS 2 and eight healthy subjects (control group, C), whose plasma arterial (A) and venous (V) AA concentrations had been measured. Compared to C, the group of CRS 2 patients showed significant reductions by more than 90% in A (p < 0.01) and V (p < 0.01) individual AAs, whereas negative A-V differences that indicated a net muscle AA release (muscle hypercatabolism) were found in 59% of CRS 2 patients (p < 0.03). No significant differences in plasma A and V AA concentrations nor in A-V differences were found between patients with mild kidney damage (N = 5; estimated glomerular filtration rate, eGFR ≥ 60 mL/min/1.73 m2 ) and patients with moderate-severe kidney damage (N = 11; eGFR < 60 mL/min/1.73 m2 ). Several plasma arterial AAs correlated with hemodynamic variables, but not with GFR. The study showed that patients with CRS 2 had very low concentrations of circulating AAs, independent of the degree of GFR damage
Neurohormonal and functional correlates of linear and poincarè plot indexes of heart rate variability in heart failure patients
No full textTemporal relationship between arousals and Cheyne-Stokes respiration with central sleep apnea in heart failure patients
No full textObjective: The interplay between arousals and respiratory events during Cheyne-Stokes respiration (CSR) with central sleep apnea (CSA) in heart failure (HF) patients is still not fully understood. We investigated the temporal relationship between arousals and CSR-CSA. Methods: Episodes of CSR-CSA during sleep stages N1-N2 were analyzed in 22 HF patients with an apnea-hypopnea index ≥15/h, dominant CSA and central apnea index ≥5/h. For each CSR-CSA cycle (apnea + hyperpnea), we determined the onset (ARonset, relative to hyperpnea onset) and duration of detected arousals. Results: Arousals (N = 2348) mostly occurred within the first half of the hyperpneic phase (42.6%, ARonset = 10.6 ± 2.1 s; duration = 10.6 ± 5.2 s) or close to hyperpnea onset (21.5%, ARonset = −0.1 ± 0.6 s; duration = 13.9 ± 5.4 s). Within-apnea arousals were less frequent (12.4%, ARonset = −16.0 ± 4.7 s; duration = 3.8 ± 1.4 s). The proportion of CSR-CSA cycles without any hyperpnea-related arousal was 27.5 ± 18.2%. Hyperpnea-related arousability (total number of hyperpneic arousals/total duration of hyperpneas) and apnea-related arousability were 63.4 ± 21.0/h and 23.8 ± 16.9/h, respectively (p < 0.0001). Conclusion: During CSR-CSA, a significant proportion of arousals occur at hyperpnea onset, indicating a low arousal threshold. Hyperpneic arousals are not essential for CSR-CSA. Arousability markedly increases during hyperpneas, likely due to the concurrent increase in chemoreceptor stimulation. Significance: This study extends current knowledge on the interplay between sleep instability and respiratory events during CSR-CSA
Variations on the Author
Get PDF“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
Get PDFWe 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
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