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Cardiac responses to external sensory stimuli: a precious tool for testing insect responsiveness
No full textThat the insect heart represents an experimental model
with interesting biological properties having close
ultrastructural and functional similarities with the
mammalian myocardium has been known since time.
More recently, further elements of interest have
emerged from the results of genetic and
pharmacological research, on the basis of which the
insect myocardium has been proposed as an
experimental model with unique biological
characteristics.
This article describes how, in analogy with responses
of the vegetative type typical of more evolved animal
species, cardiac responses to stimulation of external
sensory receptors occur in insects as well. The
experiments described herein were performed on
Phormia regina, Calliphora vomitoria, Protophormia
terraenovae blowflies (Diptera: Calliphoridae), and on
Heliothis virescens, Lymantria dispar, Bombyx mori
and Spodoptera littoralis moths (Lepidoptera:
Noctuidae). Regular cardiac activity and sensoryinduced
variations were continuously monitored in
restrained and intact specimens by means
of electrocardiography (ECG). At the same time,
sensory activity induced by olfactory or taste
stimulation was electrophysiologically monitored on
antennal (EAG) or labellar (tip-recording technique)
sensilla. Short latencies and low threshold ranges of
cardiac responses to sensory stimulation were measured,
thus proving that prompt and efficient adjustments
of the insect cardiocirculatory function take place in
response to changes in the external environment.
Although the physiological significance of these
phenomena remains to be established, it may be
hypothesized that they play an important role in
adaptation of internal milieu conditions of the insect to
chemical-physical changes in the external environment
A portable computerized system for long-term electrocardiogram monitoring in marine environments
No full textA digital Holter recorder was modified and assembled with a dedicated portable, water- and
pressure-proof, hydrodynamic protective case to detect
electrocardiograms (ECGs) in marine water on free swimming dolphins (Tursiops truncatus) and human divers using a self-contained underwater breathing
apparatus (SCUBA). Employment of a non-invasive appliance leaves subjects awake and not annoyed by the presence of the instrument. Recordings with a good signal-to-noise ratio were obtained, thus revealing electric events throughout the heart cycle of subjects diving at the water surface level and at depth. Results demonstrate that while dolphins show the already known apnoea diving bradycardia, normoxic-air
breathing subjects display noteworthy increases in heart
rate and atrium ventricular conduction velocity which
likely represent functional adjustments to the
performing of swimming and diving physical exercise.
The instrument appears as a promising diagnostic tool
for future studies in the fields of scuba and apnoea
diving sports, occupational medicine and veterinary
science
Cardiac responses to sucrose reception and intake in the adult blowfly Protophormia terraenovae
No full textCardiac activity of intact Protophormia terraenovae [Phormia terraenovae] flies and its taste- and feeding-induced variations were analysed by electrocardiogram recording either simultaneously with nervous spike discharge from stimulated labellar taste sensilla, or during feeding. Results indicate that the cardiac response to taste stimulation consists of the inhibition of fast beating activity and the premature setting in of tachycardic slow beating activity. Although the response was evoked by taste stimulation with solutions of sucrose or NaCl, the former were far more effective than the latter. During feeding, variations in cardiac activity consisted of a sharp reduction in the duration of periods of fast and slow activity, that continued for 20 minutes after the end of feeding. Variations in haemolymphatic circulatory dynamics which, in all likelihood, are consequent to taste- and feeding-induced cardiac changes may influence haemolymphatic volume and pressure in extracardiac compartments. The hypothesis is advanced that the biological meaning of variations in cardiac activity and thus in haemolymphatic pressure, is that of creating conditions favourable to the behaviour the insect has to manifest, in particular as concerns the ingestion of food
Variations of sinusal rhythm induced by taste stimulations with opposite hedonic dimension
No full text
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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