1,720,975 research outputs found
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
Variations 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
Bilateral asymmetry of cerebral blood velocity in cluster headache.
No full textIn this study, 69 episodic cluster headache (CH) patients (40 in the active phase, 29 in remission period) underwent a complete TCD examination in order to verify the relationship between cerebral blood velocities (CBVs) and the clinical profile of the disease. Fifteen patients were examined during both phases, while 7 were monitored during a spontaneous attack. Sixty-three healthy sex and age-matched controls were also studied. We measured widespread, asymmetric CBV activation during the active phase, bilaterally in the anterior circulation and also in the posterior circulation. A relative reduction of CBV on the anterior cerebral artery pain side, also during remission, suggests a relationship between local vasodilation and the autonomic symptoms ipsilateral to pain during CH attacks
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
Intracerebral vascular changes induced by cold pressor test: a model of sympathetic activation.
No full textCerebral vascular changes seem to play a fundamental role in the pathogenesis of various functional disturbances, (i.e. those suggested for migraine pathogenesis). However the exact role of single regulatory aspects (metabolic-neuronal-mechanic) are not completely understood and easily investigated in man. In particular, the role of autonomic nervous system is widely debated and recently the stimulation of tegmental noradrenergic nuclei (locus coeruleus in particular) has proved capable of inducing, in the animal, both the reduction and the increase of extracerebral blood flow. In order to evaluate the vascular effect of locus coeruleus stimulation in man, we investigated intracerebral vascular changes induced by the cold pressor test (CPT) (a well standardized method for activating both nociceptive and sympathetic pathways) by means of transcranial Doppler sonography. The examinations were performed in 14 healthy controls. CPT induced a constant and evident reduction in mean arterial velocity of the middle cerebral artery. The response was triggered during the first minute following hand immersion in ice water and reached its maximum level by the 3rd minute. Pretreatment with the alfa2-agonist clonidine caused a marked reduction of the cerebrovascular response. These data suggest that: a) intracerebral vascular response induced by CPT may be attributed to a central noradrenergic mechanism (possibly modulated at the locus coeruleus level) and b) transcranial Doppler monitoring of CPT effect is a potential tool for investigating peculiar patterns of functional disturbances of cerebral circulation
Imbalance of heart rate regulation in cluster headache as based on continuous 24-h recordings.
No full textAn altered autonomic balance is considered to be a pathogenetic factor in cluster headache syndrome, although there is varying data on sympathetic and/or parasympathetic activation during attacks and/or attack-free intervals. The aim of the present study was to evaluate the day/night pattern of heart rate during the active and remission phases of cluster headache. In addition, the relationship between heart rate changes and the site of pain was investigated to determine if an autonomic imbalance was related to the lateralization of pain. Thirty-nine patients (34 with primary episodic cluster headache and five with primary chronic cluster headache and 30 healthy controls underwent 24-h Holter ECG recording. Nine cluster headache patients were monitored during both phases of the disease. The data obtained confirmed the existence of a disordered chrono-organization in cluster headache (phase-shift of approximately 1 h of heart rate rhythm during the cluster period) together with a low heart rate variability and a higher occurrence of arrhythmias in cluster headache patients with right-sided pain. Differences were also observed in the cluster headache patients when headache free, excluding the pain itself as a reason for the abnormality. The chronobiological data point out a transient rhythmic dysfunction, while heart rate variability changes, mostly related either to the phase of the disease or to the site of pain, probably reflects a central, site-related, dysfunction of the autonomic nervous system in cluster headache
Internal carotid occlusion associated with migraine syndrome: a case study of a 22-year-old female.
No full textMigraine and migraine-like headaches are sometimes associated with acquired types of carotid artery disease. We examined a 22-year-old female suffering from periodic migraine, sometimes with "atypical" features. Color Flow Duplex Sonography revealed an occlusion of the right internal carotid artery (ICA) and a possible severe stenosis of the cervical segment of the left ICA. Digital Subtraction Angiography combined with Angio-Magnetic Resonance Imaging and Echographic Imaging suggested the possibility of a fibromuscular dysplasia involving both ICAs. It is suggested that some atypical features of headache could represent symptoms of a carotid pathology
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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