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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Effect of adolescent Δ 9-THC pretreatment in the dose-response relationship of heroin self-administration in Lewis and Fischer rats
No full textVariations on the Author
Get PDF“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
Effect of adolescent Δ9-THC pretreatment in dose–response relationship during heroin self-administration in a genetic animal model of opiate vulnerability
No full textAdolescent exposure to Δ9-THC in Lewis and Fischer 344 adolescent rats influences heroin self-administration in adulthood
No full textLewis (LEW) and Fischer (F344) inbred rat strains show several neurochemical and behavioral differences regarding the reinforcing properties of drug of abuse, and represent an important animal model to study the genetic components involved in different stages of drug addiction. The aim of this study was to evaluate the influence of early pre-exposure to Δ9-THC on heroin self-administration (SA) in adulthood, under Fixed Ratio followed by Progressive Ratio (PR) schedule of operant responding.
On the 6th postnatal (PN) week rats were administered twice daily with increasing doses of Δ9-THC (2,4,8 mg/kg, i.p.) for three consecutive days. In adulthood (10th PN week) LEW and F344 rats were trained to acquire heroin SA, at the dose of 0.25 mg/kg, 48 μl/4-s, under FR-1 schedule of responding, then increased to FR-3 and FR-5 protocols in 1-h daily sessions. Starting from the 30th session each group was allowed to self-administer heroin under PR3-4 schedule of responding, in order to evaluate the reinforcing efficacy of heroin over 4-h daily sessions in which response requirement progressively increase. After three week off active heroin response-contingent administration, rats underwent to the extinction phase, during which drug was substituted by sterile saline.
LEW rats showed higher operant responding activity and faster acquisition of opiate-reinforced behavior as compared to F344 rats. Moreover, adolescent exposure of LEW rats to Δ9-THC induced a faster increase of responding when switching ratio schedule from FR-1 to FR-3 and to FR-5 compared to control LEW rats as well as to F344 groups. On the other hand no differences between F344 pre-treated and F344 control were found either in the nose poking activity or heroin intake during each FR sessions. Furthermore LEW pre-treated rats readily acquire PR schedule and showed greater nose poking behavior and heroin intake, as well as higher breaking point (BP) values compared to the control LEW rats and both F344 experimental groups. During extinction both strains showed rapid fall of responding activity and quickly extinguished operant behavior.
These results strongly suggest that adolescent Δ9-THC pre-exposure can affect heroin reinforcing properties in adulthood, depending on strain-related background, strengthen the importance of genetic factors in the development of drug addiction phenomenon and validate this strain related model for the study of the individual genetic vulnerability to reinforcing properties of drugs of abuse
Influence of Δ9-THC exposure in Lewis and Fischer 344 adolescent rats on heroin self-administration in adulthood
No full textLewis (LEW) and Fischer (F344) inbred strains show several neurochemical and behavioral differences relevant for drug addiction. Thus LEW are more impulsive and have a lower D2 receptor binding in striatal areas than F344. The aim of this study was to evaluate the influence of early pre-exposure to Δ9-THC on heroin self-administration (SA) and reinstatement in adulthood.
On the 6th postnatal (PN) week rats were administered twice a day with increasing doses of Δ9-THC (2,4,8 mg/kg, i.p.) for three consecutive days. In adulthood (10th PN week), LEW and F344 rats were trained to acquire heroin SA under Fixed Ratio (FR) schedule of responding. In Exp-I, after FR sessions rats underwent extinction and reinstatement phases, while in Exp-II, after acquisition, they were allowed to self-administer heroin under Progressive Ratio (PR) schedule.
In both experiments LEW rats showed higher responding and faster acquisition of heroin self-administration as compared to F344 rats. Moreover, adolescent exposure of LEW rats to Δ9-THC resulted in a faster increase of responding when switching ratio schedule from FR-1 to FR-3 and FR-5, and greater responding on the active hole during reinstatement, compared to control LEW rats as well as to F344 (Exp-I). These results suggest that adolescent Δ9-THC pre-exposure differentially affects heroin reinforcement in adulthood in a strain-related way
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Delta9-THC and heroin exposure in adolescence differently affect heroin self-administration in adulthood
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