1,721,014 research outputs found
Ultrasound evaluation of pupil: secrets of the “black hole” unveiled
No full textThis Letter to the Editor is in response to Stevens and colleagues, who presented a study about pupillometry in patients with traumatic brain injury. They did not find any correlation between pupil diameter and intracranial pressure. We agree with the clinical importance of pupil assessment and we would like to suggest the application of transorbital ultrasound for this evaluation. This approach has been proposed in the past and, with our work, we show the possible quantification of symmetry of pupil diameter variation in response to a stimulus. This approach may represent a proficient and safe method for patients’ supervision
Functional overlap between hand and forearm motor cortical representations during motor cognitive tasks
No full textThe aim of this study was to verify whether motor imagery (MI) and observation of a movement (MO) enhanced cortical representations of the hand/forearm muscles not primarily involved in the task. We also explored the existence of functional overlaps in the upper-limb cortical representations during the aforementioned tasks
Breakdown of inhibitory effects induced by foot motor imagery on hand motor area in lower-limb amputees
No full textObjective:Amputation of a limb induces plastic changes in motor cortex that modify the relationships between the missing limb and theremaining body part representations. We used motor imagery to explore the interactions between a missing lower limb and the hand/forearm cortical representations.Methods:Eight right leg amputees and nine healthy subjects participated in the study. Focal transcranial magnetic stimulation was usedto map out the hand/forearm muscle maps at rest and during imagined ankle dorsiflexion and plantarflexion.Results:In healthy subjects, both motor imagery tasks strongly inhibited the map volume and contracted the map area of the hand mus-cles. By contrast, in amputees, imagined dorsiflexion and plantarflexion enhanced the map area and volume of the hand muscles. In theforearm muscle maps, both groups displayed a similar pattern of isodirectional coupling during both motor imagery tasks. Imagineddorsiflexion facilitated MEP amplitudes of the extensor and inhibited the flexor muscles of the upper limb. This pattern was reversedduring imagined plantarflexion.Conclusions:We argue that there exists an inhibitory relationship between the foot and hand motor cortices that ceases to exist after legamputation.Significance:The understanding of these functional mechanisms may shed light on the motor network underlying interlimbcoordinatio
Functional overlap between hand and forearm motor cortical representations during motor cognitive tasks
No full textObjective:The aim of this study was to verify whether motor imagery (MI) and observation of a movement (MO) enhanced corticalrepresentations of the hand/forearm muscles not primarily involved in the task. We also explored the existence of functional overlapsin the upper-limb cortical representations during the aforementioned tasks.Methods:Focal transcranial magnetic stimulation (TMS) was used to map out the cortical representation of the opponens pollicis (OP,target muscle) and other hand and forearm muscles at rest and during MI and MO.Results:The MI and MO tasks induced similar changes in the area and volume of both the OP and synergic muscles. No significantchanges were observed in the cortical excitability of the remaining muscles. The superimposition of different muscle maps revealed exten-sive functional overlaps in the hand/forearm cortical territories.Conclusions:This study demonstrates that neither the MI nor MO changes single muscle motor responses and that the hand/forearmmuscle maps extensively overlap during motor cognitive tasks.Significance:The data reported in this study support the notion that the basic unit of cortical output is not the mere activation of a givenmuscle. This flexible organization may have important implications in motor learning and plasticit
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
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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