1,720,984 research outputs found
The fast Fourier transform in the anlysis of the normal phonocardiogram
No full textThe present study is focused on spectrum analysis as a useful method of processing the PCG in order to obtain the frequency spectral distribution of normal heart sounds. Thirty normal subjects aged from 17 to 34 were studied. PCG was recorded on the fourth intercostal space at the left sternal border using a sound level meter coupled with a standard 6 ml cavity. The microphone had a linear response from 0.2 to 8,000 Hz. The signal was filtered with the standard B network according to the ANSI specifications and was registered on a four track FM tape recorder. A four channel analyzer with a microprocessor for off-line elaborations was used with 10 KHz sampling frequency. The PCG signal was triggered by a QRS detector on the R wave of the simultaneously recorded ECG. Fast Fourier transform was performed employing either a four channel analyzer with a microprocessor, or an A/D converter with a computer. Finally the results of the analysis were statistically elaborated. The described procedures permit to obtain a direct and exact tracing of the acoustic features of the heart, thus representing an attempt to come closer to the standardization and automatic analysis of the phonocardiographic technique
Logarithmic display of auditory evoked potentials
No full textAuditory evoked potentials (AEP) can be simultaneously recorded on-line as a succession of 11 waves, through a single input channel of a mini-computer. Since the response waves differ widely in frequency, a computing routine has been developed to display the whole response pattern in a single picture. Based upon a non-linear samples reduction of the digitized response, this routine allows a logarithmic transformation of the time axis. The method improves the identification of the AEP components and provides an objective estimate of the central auditory pathway for both neurophysiological and neuroclinical studies
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
Accordo di ricerca AIA-SNPA per la raccolta e l’analisi di livelli sonori monitorati durante l’emergenza COVID-19
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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
Occupational noise exposure for call-center workers
No full textFor communication personnel, the occupational noise has to be determined in the ear canal as effect of sound immission from sources placed closed to the ear. This measurement could be carried out directly using miniature or probe microphones, or indirectly using a manikin equipped with ear simulators including microphones. In both cases, special care should be addressed to experimental determination of the frequency-dependent transformation based on the gain exerted by the ear at different frequencies. The investigation dealt with both measuring techniques. It has been undertaken in 74 different work stations (7 call centers) on 83 different types of receivers (supra-aural earphone, insert earphones, telephone handsets) for a 30 hour total monitoring time. Results show that the noise exposure levels are extremely variable: from a minimum value of 50 dB(A) to a maximum value of 87 dB(A). Moreover, the level of 80 dB(A) is exceeded in 23% of cases. By these data we can conclude that the risk of hearing loss could exist for some workers in certain conditions, as previously reported also by other researchers
Technical and methodological aspects concerning the application of Fourier's analysis to phonocardiography (author's transl)
No full textThe frequency spectrum analysis (Fourier's analysis) has recently been applied to phonocardiography. Using this mathematical approach instead of the current empirical analysis, it is possible to obtain -- on a less subjective basis -- more precise pathophysiological and diagnostic information from the acoustic cardiac phenomena. On the other hand, this refinement of the method of analysis stresses the need for better technical and methodological solutions, in order to reach the standardization of both the transduction and the recording of the acoustic signal at higher level of sensibility, fidelity and reproducibility. With this in mind, and on the basis of their experience, the Authors suggest the adoption of devices with specific technical characteristics, and propose a suitable method of application of Fourier's analysis to the phonocardiogram
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