1,721,094 research outputs found
Activity-rest stimulation protocol improves cardiac assistance in dynamic cardiomyoplasty
No full textEur J Cardiothorac Surg. 2002 Mar;21(3):478-82.
Activity-rest stimulation protocol improves cardiac assistance in dynamic cardiomyoplasty.
Rigatelli G, Carraro U, Barbiero M, Zanchetta M, Dimopoulos K, Cobelli F, Riccardi R, Rigatelli G.
Source
Department of Cardiology, Interventional Cardiology Lab and Cardiomyoplasty Project Unit, Legnago General Hospital, Verona, Italy. [email protected]
Abstract
OBJECTIVE:
No data have ever been published regarding cardiac assistance in demand dynamic cardiomyoplasty (DDCMP). We tested the efficacy of the Doppler flow wire in measuring beat-to-beat aortic flow velocity and evaluating cardiac assistance in demand cardiomyoplasty patients.
METHODS:
The technique was tested in seven patients (M/F=6/1; age=57.1+/-6.2 years; atrial fibrillation/sinus rhythm=1/6; NYHA=1.4+/-0.5). Measurements were done using a 0.018inch peripheral Doppler flow wire advanced through a 5F arterial femoral sheath. Three 1-min periods with the stimulator off and three 1-min periods with clinical stimulation were recorded. We measured peak aortic flow velocity in all beats. Latissimus dorsi (LD) mechanogram was simultaneously recorded.
RESULTS:
Comparison between pre-operative and follow-up data showed significantly higher values of tetanic fusion frequency (TFF) and ejection fraction at follow-up, whereas mean NYHA class was significantly lower. Statistical analysis showed an increase in aortic flow velocity not only in assisted versus rest period, but also in assisted versus unassisted beats (8.42+/-6.98% and 7.55+/-3.07%). A linear correlation was found between the increase in flow velocity and LD wrap TFF (r(2)=0.53).
CONCLUSIONS:
In DDCMP, systolic assistance is significant and correlated to LD speed of contraction; demand stimulation protocol maintains muscle properties and increases muscle performance.
PMID:
11888767
[PubMed - indexed for MEDLINE
Exploring a black box: cross-national study of visit effects on visitors to large physics research centers in Europe
No full textResults from a cross-national quantitative study of 3,301 visitors to four large physics research centers in Europe focus on short-term learning and motivational effects. The authors collected data from these visitors before and after visiting the centers as part of a research project funded by the European Union. Overall, visitors' knowledge of the research centers increased. However, effects on learning of scientific concepts are not so clear. The visits mostly seem to reaffirm visitors' prior attitudes and images related to the centers. The findings imply that these visits offer some learning potential and, for school students, increased motivation to enter a scientific profession, but in terms of altering visitors' images they seem rather ineffective. Nevertheless, because of their uniqueness in allowing different publics an authentic glimpse of the production of scientific knowledge, visits to research centers remain an important public communication activity
Cardiovascular and ventilatory control during exercise in chronic heart failure: role of muscle reflexes
No full textDuring exercise nervous signals are generated by stimulation of mechanically (muscle mechanoreflex) and chemically (muscle metaboreflex) sensitive skeletal muscle receptors. These receptors and their associated afferent fibres are sensitive to muscle work and reflexively adjust the haemodynamic, ventilatory and circulatory responses during physical effort. Thus the muscle reflex is essential in achieving normal responses to exercise in healthy subjects. In chronic heart failure, characterised by exercise intolerance with early occurrence of dyspnea or fatigue, peripheral muscle abnormalities (i.e. muscle atrophy, decreased peripheral blood flow, fibre-type transformation, and reduced oxidative capacity) trigger an exaggerated muscle reflex. This abnormality has recently been implicated in the genesis of the disabling symptoms. We review the role of the muscle reflex in regulating the cardiovascular and the ventilatory systems during exercise in both healthy and diseased condition
New advances in dynamic cardiomyoplasty: Doppler flow wire shows improved cardiac assistance in demand protocol
No full textASAIO J. 2002 Jan-Feb;48(1):119-23.
New advances in dynamic cardiomyoplasty: Doppler flow wire shows improved cardiac assistance in demand protocol.
Rigatelli G, Carraro U, Barbiero M, Zanchetta M, Pedon L, Dimopoulos K, Rigatelli G, Maiolino P, Cobelli F, Riccardi R, Volta SD.
Source
Department of Cardiology, Legnago General Hospital, Verona, Italy.
Abstract
No data have been published on real cardiac assistance with demand dynamic cardiomyoplasty. We tested the utility of a Doppler flow wire in measuring beat by beat aortic flow velocity and evaluating cardiac assistance in demand cardiomyoplasty patients. The technique was tested in seven patients (M/W = 6/1; age, 57.1+/-6.2 years; atrial fibrillation/ sinus rhythm = 1/6; New York Heart Association [NYHA] classification = 1.4+/-0.5). Measurements were done using a 0.018 inch peripheral Doppler flow wire advanced through a 5 French arterial femoral sheath. Three 1 minute periods with the stimulator off, and three 1 minute periods with clinical stimulation were recorded. We measured peak aortic flow velocity in all beats. Latissimus dorsi mechanogram was simultaneously recorded. Comparison between preoperative and follow-up data showed significantly higher values of tetanic fusion frequency and ejection fraction at follow-up, whereas mean NYHA class was significantly lower. Statistical analysis showed an increase in aortic flow velocity not only in the assisted versus rest period, but also in assisted versus unassisted beats (8.42+/-6.98% and 7.55+/-3.07%). A linear correlation was found between increase in flow velocity and latissimus dorsi wrap tetanic fusion frequency (r2 = 0.53). In demand dynamic cardiomyoplasty, systolic assistance is significant and correlated to the latissimus dorsi speed of contraction; a demand stimulation protocol maintains muscle properties and increases muscle performance.
PMID:
11814090
[PubMed - indexed for MEDLINE
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
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