1,721,009 research outputs found
Antiepileptic drugs as a possible neuroprotective strategy in brain ischemia
No full textSeveral new antiepileptic drugs (AEDs) have been introduced for clinical use recently. These new AEDs, as did the classic AEDs, target multiple cellular sites both pre- and postsynaptically. The major common goal of the pharmacological treatment using AEDs is to counteract abnormal brain excitability by either decreasing excitatory transmission or enhancing neuronal inhibition. Interestingly, an excessive release of excitatory amino acids and a reduced neuronal inhibition also occur in brain ischemia. Thus, recently, the use of AEDs as a possible neuroprotective strategy in brain ischemia is receiving increasing attention, and many AEDs have been tested in animal models of stroke, providing encouraging results. Experimental studies utilizing global or focal ischemia in rodents have provided insights into the possible neuroprotective action of the various AEDs. However, the implication of these studies in the treatment of acute stroke in humans is not always direct. In fact, various clinical studies with drugs targeting the same voltage- and ligand-gated channels modulated by most of the AEDs failed to show neuroprotection. The differential mechanisms that underlie the development of focal ischemic injury in experimental animal models versus human stroke require further investigation to open a new therapeutic perspective for neuroprotection that might be applicable in the future
Ultrasonographic evaluation of carotid atherosclerosis in postmenopausal women with stroke
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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
Involvement of the healthy hemisphere in recovery from aphasia and motor deficit in patients with cortical ischemic infarction: a transcranial Doppler study
No full textActivation of areas of the health hemisphere seems to play a role in functional recovery from stroke. We studied cerebral blood flow changes during motor and mental activity in patients with cortical ischemic lesions. We simultaneously measured blood flow velocity in the two middle cerebral arteries of 45 patients with single cortical ischemic lesions and good functional recovery and of 16 healthy controls by means of bilateral transcranial Doppler ultrasonography during a 2-minute sequential thumb-to-finger opposition task, alternately performed with the right and left hands, and during a 1-minute word-fluency task. Twenty-five patients had left cortical lesions, 12 with previous motor deficit alone and 13 with associated motor deficit and Broca's aphasia. Twenty patients had right cortical lesions with previous motor deficit. With respect to baseline values, the increase of flow velocity in the middle cerebral artery contralateral to the hand performing the motor task was comparable in controls and patients, regardless of the side of the lesion and the hand (normal or recovered) involved in the task. During movement of the recovered hand, the increase of flow velocity in the ipsilateral middle cerebral artery was significantly greater (p < 0.001, two-way ANOVA) than the increase during movement of the normal hand in both controls and patients. During performance of the word-fluency task, the increase of flow velocity in the left middle cerebral artery was comparable in controls and patients.(ABSTRACT TRUNCATED AT 250 WORDS
Transcranial doppler assessment of cerebral flow velocity during perception and recognition of melodies
No full textThe role of each cerebral hemisphere in the perception and recognition of musical information is not yet well understood. We studied cerebral blood flow changes during a melody perception task and a melody recognition task. Blood flow velocity in the two middle cerebral arteries of twenty right-handed musically naif volunteers were simultaneously measured by means of bilateral transcranial Doppler ultrasonography during two minutes of passive melody listening and two minutes of a melody recognition task. With respect to baseline values, a bilateral increase of flow velocity occurred in the middle cerebral arteries with a non-significant trend for the right artery during the melody perception task. During the melody recognition task, a significant increase in flow velocity was recorded on the right side with respect to the left side, where a slight simultaneous decrease was found. Our data suggest that melody perception requires bilateral activation of hemispheres and melody recognition mainly an activation of the right hemisphere. This study confirms the ability of transcranial Doppler ultrasonography to correlate artery flow dynamics with selective cerebral activation
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
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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