1,721,899 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
Entrevista a Josep M. Sala-Valldaura
No full textJosep M Sala-Valldaura (Gironella, 1947) és poeta, assagista, crític literari i traductor. Té una extensa bibliografia i ha estat guardonat amb diversos premis. Doctor per la Universitat de Barcelona, ha estat professor i catedràtic a la Universitat de Lleida
Cannabinoid-induced working memory impairment is reversed by a second generation cholinesterase inhibitor in rats
No full textCannabinoids which impair rat working memory appear to inhibit hippocampal extracellular acetylcholine (Ach) release and reduce choline uptake through an interaction with CBI cannabinoid receptors. Here we report that CP 55,940, a potent bicyclic synthetic cannabinoid analog, dose-dependently impaired rat performance, when given i.p. 20 min before an eight-arm radial maze test. The selective CB1 cannabinoid receptor antagonist SR 141716A, given i.p. 20 min earlier, significantly reduced the memory deficit. Pretreatment with eptastigmine, a second generation cholinesterase inhibitor, given orally 100 min before the cannabinoid agonist, relieved the memory impairment without affecting CP 55,940-induced behavioural alterations such as reduced spontaneous motor activity, analgesia and hind limb splaying. These data suggest that cannabinoid-induced working memory impairment is mediated through a central cholinergic blockade
Eptastigmine : ten years of pharmacology, toxicology, pharmacokinetic, and clinical studies
No full textEptastigmine (heptyl-physostigmine tartrate) is a carbamate derivative of physostigmine in which the carbamoylmethyl group in position 5 of the side chain has been substituted with a carbamoylheptyl group. In vitro and ex vivo results suggest that eptastigmine has a long-lasting reversible brain cholinesterase (i.e., acetylcholinesterase and butyryl-cholinesterase) inhibitory effect. When administered in vivo to rodents by various routes, eptastigmine inhibits cerebral acetylcholinesterases (AChE) and increases acetylcholine (Ach) brain levels by 2500-3000%, depending on the dose. This effect leads to an improvement in the cerebral blood flow in the ischemic brain, excitatory and inhibitory effects on the gastrointestinal tract and to a protection from acute soman and diisopropylfluorophosphate intoxication. Eptastigmine, by either acute or chronic administration, has been found to have memory enhancing effects in different species of normal, aged and lesioned animals. It also restored to normal the age-related increase of EEG power without affecting spontaneous motor activity. Clinical investigations on more than 1500 patients with Alzheimer's disease demonstrated that eptastigmine significantly improved cognitive performance (as assessed by the cognitive subscale of the Alzheimer's Disease Assessment Scale) as compared with placebo. This improvement was most evident in patients with more severe cognitive impairment at the baseline. The relationship between patient performance and average steady-state AChE inhibition was described by an inverted U-shaped dose-response curve. Pharmacokinetic studies have revealed that after oral administration eptastigmine is rapidly distributed to the tissues and readily enters the CNS, where it can be expected to inhibit AChE for a prolonged period. Eptastigmine is generally well tolerated and the majority of adverse events (cholinergic) were mild to moderate in intensity. However, the adverse hematologic (granulocytopenia) effects reported in two studies have resulted in the suspension of further clinical trials
Endocannabinoids and 3,4-methylenedioxymethamphetamine (MDMA) interaction
No full textCannabis and MDMA are two of the most widely used recreational drugs. This review considered their neuropsychological
effects, when taken singly or in combination,
in humans or animals. In humans, prolonged use of MDMA and cannabis together is associated with a variety of psychological problems, including elevated impulsiveness,
anxiety, somatic complaints, obsessive–compulsive patterns,and psychotic behavior. It is not clear to what extent the combination of MDMA and cannabis contributes to fatal motor vehicles accidents though an additive adverse effect on visual perception in MDMA/D9-THC users has been reported. Neurocognitive deficits (memory, learning, word fluency, speed of processing, and manual dexterity) in several brain areas (hippocampus, frontal lobe) have been
reported in those taking both drugs. Endocrine abnormalities in MDMA users have been closely related to their use of
cannabis too. A recent study investigated whether coadministered cannabinoids and MDMA in rats affected the long-term neurotoxic properties of MDMA through a hypothermic action, an antioxidant action, or both. Very
few studies have set out to clarify the consequences of chronic exposure to concomitant cannabinoids and MDMA
for their abuse liability in animals. MDMA showed some cross-discriminative stimulus effects with cannabinoids (delta9-THC), and it has been demonstrated in rats that the
endocannabinoid system is involved in MDMA selfadministration.However, these findings have not been confirmed by microdialysis studies in mesolimbic structures
which might further clarify this interaction.
These findings may help explain the use of marijuana and MDMA together by polydrug users in order to overcome the unpleasant effect which often arise as the
initial euphoria dissipates. It has recently been confirmed,using a CPP task, that the endocannabinoid system is involved when the reinforcing properties of MDMA, given
centrally, were blocked by pretreatment with SR 141716
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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