1,721,072 research outputs found
Recovery of cerebral autoregulation during the first three months after acute ischaemic stroke
No full textRecovery of cerebral autoregulation during the first three months after acute ischaemic stroke - A longitudinal study using transcranial Doppler ultrasonography by Dr Joseph Shiu Kwong Kwan Cerebral autoregulation (CA) is a mechanism that maintains a constant cerebral blood flow over wide ranges of blood pressure (BP). CA is impaired after stroke and changes in cerebral blood flow may become passive to changes in BP. Manipulation of BP after stroke may worsen regional cerebral blood flow with possible clinical implications. However, little is known about the recovery of CA soon after stroke. In this study, we used transcranial Doppler (TCD) to examine the recovery of CA after ischaemic stroke. We studied ten stroke patients and eleven controls. Each patient was examined within seven days, at six weeks, and at three months. For each examination, cerebral blood flow velocity (CBFV) and BP were continuously recorded by bilateral TCD and Finapres, respectively. We examined the relationship between spontaneous oscillations of BP and CBFV, and between induced BP oscillations (by rhythmic handgrip) and CBFV, using cross-spectral transfer function analysis (calculation of phase, gain, and coherence). We demonstrated that, using rhythmic handgrip, CA changes over the first three months after stroke, although no difference was found between patients and controls. Moreover, these changes appear to affect the hemisphere contralateral to the ischaemia, which suggests that disturbances in cerebral haemodynamics after stroke may be global in nature. We also found that the competence of CA was dependent on the frequency of BP oscillations. This indicates that CA behaves as a high-pass filter system, even after ischaemic stroke. The combination of TCD and rhythmic handgrip appear to be a useful non-invasive method of assessing CA after stroke. This technique may become a useful clinical tool in the future.</p
Antiepileptic drugs for the primary and secondary prevention of seizures after subarachnoid haemorrhage
No full textBackground: subarachnoid haemorrhage may result in seizures both acutely and in the longer term. The use of antiepileptic drugs (AEDs) in the primary and secondary prevention of seizures after subarachnoid haemorrhage is uncertain, and there is currently no consensus on treatment.Objectives: to assess the effects of AEDs for the primary and secondary prevention of seizures after subarachnoid haemorrhage.Search methods: we searched the Cochrane Epilepsy Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 1) in The Cochrane Library, and MEDLINE (1946 to 12th March 2013). We checked the reference lists of articles retrieved from these searches.Selection criteria: we considered all randomised and quasi-randomised controlled trials in which patients were assigned to a treatment (one or more AEDs) or placebo.Data collection and analysis: two review authors (RM and JK) independently screened and assessed the methodological quality of the studies. If studies were included, one author extracted the data and the other checked it.Main results: no relevant studies were found.Authors' conclusions: there was no evidence to support or refute the use of antiepileptic drugs for the primary or secondary prevention of seizures related to subarachnoid haemorrhage. Well-designed randomised controlled trials are urgently needed to guide clinical practice
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
Do we really understand the pathophysiology and clinical impact of poststroke infection?
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koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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