1,721,349 research outputs found
Riduzione di volume polmonare: tecniche chirurgiche
No full textLa BPCO rappresenta una grave piaga sociale, per prevalenza, impatto sul sistema sanitario e sui tassi di mortalità. L'enfisema polmonare è, con la bronchite cronica, una delle forme di BPCO. E' una malattia cronica, progressiva e irreversibile, caratterizzata dalla perdita di ritorno elastico del tessuto polmonare che, a seguito di ostruzione bronchiale, causa una grave iperinflazione del polmone, alterando la meccanica respiratoria. Con il progredire della malattia, il trattamento farmacologico diviene insufficiente e l'unico presidio medico efficace risulta essere l'ossigenoterapia. Molti interventi chirurgici sono stati proposti per migliorare la funzionalità respiratoria di questi pazienti, ma solo il trapianto di polmone e la riduzione di volume polmonare hanno raggiunto effettiva validità terapeutica
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
Poly(DL-proline), a synthetic polypeptide behaving as an ion channel across membranes: conformational studies on ion complexes of the tetramer Boc(D-Pro-L-Pro)2OCH3
No full textTheoretical and experimental conformational analyses by circular dichroism and NMR spectroscopy of poly(DL-proline)
and its tetrameric derivative are reported. The tetramer Boc(D-Pro-L-Pro)zOCH, conformations were investigated in different solvents and in the presence of Ba2+ and Ca2+ ions to explain the ability of poly(m-proline) to increase the ion permeability across bilayer membranes. Both theoretical and experimental data indicate the formation of dimeric and monomeric complexes between tetramer and cations in solution when the tetramer is in the all-trans conformation of the peptide bonds. The results of this analysis allow confirmation of the channel model, previously proposed on the basis of the phenomenological behavior of poly(DL-proline) in membranes
Lobectomia polmonare inferiore destra uniportale sottoxifoidea per voluminosa massa
No full textIl trattamento del tumore polmonare prevede oggi un approccio miniinvasvo video-assistito (video-assisted thoracic surgery, VATS) laddove possibile. Dimensioni della neoplasia superiori ai 7 cm sono generalmente considerate controindicazioni alla VATS. Presentiamo qui il video di una lobectomia inferiore destra per voluminosa neoplasia effettuata mediante accesso uniportale sottoxifoideo
Channel structures in synthetic polypeptides with alternating configurations. Conformational analysis of poly(DL-proline).
No full textTheoretical conformational analysis of L,D alternating sequences of poly alpha-amino acids is reported in connection with the ability of naturally occurring peptide and depsipeptide having alternating configurations to increase selectively the ion permeability across membranes. The most stable structures of poly(DL-proline), of which the conformational variability is practically limited to the choice between cis and trans conformations of the peptide bonds, were characterized. The all-trans conformation results in a flat helical structure possessing the main features for acting as an ion channel across membranes as actually found experimentally. Random cis-trans conformational sequences provide an alternative mechanism of ion transport intermediate between the ion channel and the ion carrier
Toracotomia posterolaterale con risparmio muscolare versus toracotomia posterolaterale standard
No full textStructure and stability of the Boc(D-Pro-L-Pro)2OCH3 Na+ complex: a model of poly(D,L-proline), an alkali ion channel across membranes.
No full textIn order to elucidate the molecular mechanisms of alkali ions conduction of poly(D,L-proline), which shows the typical behavior of an ion channel across membranes, conformations of the tetrameric derivative Boc(D-Pro-L-Pro)2OCH3 in solution, in the presence of the Na+ ion, were investigated by CD and nmr spectroscopy. Both theoretical and experimental data indicate the formation in solution of a monomeric complex between the tetramer, in the all-trans conformation, and the cation. The results allow to confirm the channel model, previously proposed on the phenomenological behavior of poly(D,L-proline) in membranes
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