1,720,967 research outputs found
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
Monitoring olfactory reception in blowfly pupae
No full textCardiac activity changes in response to external
sensory stimulation have been described as a sensitive
mean for testing the responsiveness of several species
of adult insects. In the present research study we have
examined if cardiac responses to odour delivery could
be detected in blowfly pupae as well, thus helping in
evaluating their responsiveness to the chemical
properties of the external environment. To this end we
studied the regular activity of heart pupae and its
variations following odour delivery.
Electrocardiograms were recorded on Protophormia
terraenovae blowflies, 48 to 24 hours before adult
emergence. Effects of odour application were tested by
delivering air-containing vapours of ammonia or 1-
hexanol on single pupae by means of a standard
olfactometer.
Regular heart activity consisted of the alternation
of two phases of activity, easily distinguishable on the
basis of opposite polarity and different amplitude and
frequency of electric signals. Odour delivery induced a
constant pattern of heart activity changes, consisting
of an immediate arrest of the phase at a higher signal
frequency, the Fast phase, and a premature setting in
of the phase at a lower signal frequency, the Slow
phase. Odour delivery was ineffective on the activity
pattern of specimens on which functional ablation had
been performed of olfactory organs, i.e. the antennae
and maxillary palps. Results show that the cardiac
response is an effective indicator of olfactory reception
in blowfly pupae, thus representing a useful tool for
testing the biological importance of the chemical
environment during insect development
Implementation of RNAi-based arthropod pest control: environmental risks, potential for resistance and regulatory considerations
No full textJust over 20 years since the RNA interference (RNAi) mechanism was unraveled in the nematode Caenorhabditis elegans, the first RNAi-based pest control applications are close to commercialization. One of the most alluring aspects of this technology is its predicted minimal impact on the environment, due to high target selectivity and the short persistence of the active molecules in the environment. However, gaps of knowledge on the RNAi mechanism in many species and their implications for biosafety still exist. In this review, we present a comprehensive overview of the research conducted in this field. We discuss potential in planta and topical application methods in the field and their consequences regarding potential exposure in different non-target organisms (NTOs). While RNAi is assumed to be highly species selective, due to its sequence-guided mode of action, dsRNA design will determine how selective a product is. We also discuss molecular and cellular mechanisms affecting RNAi efficacy and how these could become a basis for the emergence of resistance against RNAi-based control products and highlight the need for resistance management. Finally, we briefly discuss recommendations for environmental risk assessment (ERA), such as the value of bioinformatics and the development of properly designed bioassays to predict effects in NTOs or to select NTOs for informing ERA
Distinct phases of memory for habituation to different training patters of olfactory stimulation in the blowfly
No full textVariations 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
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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