1,720,966 research outputs found
Exploring the brain mechanisms of breathlessness through the study of neurological patients
Get PDFIntroduction: There has been a long standing clinical need to offer safer and more efficacious treatment options for individuals with refractory breathlessness. This thesis explores the role of several regions of the brain which have been implicated to have a role in breathlessness perception either from brain imaging studies, or anecdotal evidence from neurological and neurosurgical patients. This thesis explores the neurophysiology of breathlessness with an emphasis on air hunger (AH) in the hope to provide new targets for its symptomatic relief.
Methods: Experimentally-induced hypercapnic AH tests, involving raising inspired CO2 and constrained ventilation, were conducted in neurosurgical patients with; (a) thalamic deep brain stimulation (DBS) ON and OFF as treatment for tremor, (b) DBS of the sub thalamic nucleus (STN) ON and OFF as treatment for Parkinson’s disease, and (c) patients with low-grade glioma affecting the insular cortex.
Results: Group a (n=16): Thalamic DBS produced significant relief of steady-state AH (p=0.002) with a mean±sd reduction of -14.4±15.5% on a visual analogue scale (VAS), exceeding the minimal clinically important difference of 10% for VAS ratings of AH. Group b (n=18): STN DBS, in contrast, generated a trend towards a heightened AH of 8.7±11.9%VAS in six patients. There was no effect of DBS on lung function or hypercapnic ventilatory response. Group c (n=3): Pre-operatively, AH sensitivities in the patients were strikingly lower compared to 11 healthy controls (2.8±2 versus 11±4%VAS/mmHg; p=0.004). Surgical resection of the glioma had varying effects on AH sensitivity.
Conclusion: 1) DBS of closely connected sites activated in previous brain imaging studies of breathlessness have opposing effects on AH sensitivity with a suggestion that thalamic activity modulates AH perception. 2) Insular glioma substantially degrades the ability to perceive breathlessness. The use of Diffuse tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) will help to further decipher network wide effects on AH modulation by neurological stimulation and damage. This thesis provides evidence implicating the thalamus, sub thalamus and insular cortex in the perception of breathlessness while further revealing the neural mechanisms of dyspnoea. These findings propose the possibility of the thalamus, and in particular the insular cortex, to be future targets for non-invasive neuromodulation in the hope to relieve refractory dyspnoe
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
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
Low-level carbon monoxide exposure affects BOLD fMRI response.
Get PDFBlood oxygen level dependent (BOLD) fMRI is a common technique for measuring brain activation that could be affected by low-level carbon monoxide (CO) exposure from, e.g. smoking. This study aimed to probe the vulnerability of BOLD fMRI to CO and determine whether it may constitute a significant neuroimaging confound. Low-level (6 ppm exhaled) CO effects on BOLD response were assessed in 12 healthy never-smokers on two separate experimental days (CO and air control). fMRI tasks were breath-holds (hypercapnia), visual stimulation and fingertapping. BOLD fMRI response was lower during breath holds, visual stimulation and fingertapping in the CO protocol compared to the air control protocol. Behavioural and physiological measures remained unchanged. We conclude that BOLD fMRI might be vulnerable to changes in baseline CO, and suggest exercising caution when imaging populations exposed to elevated CO levels. Further work is required to fully elucidate the impact on CO on fMRI and its underlying mechanisms
Low-level carbon monoxide exposure affects BOLD fMRI signal
Get PDFBlood Oxygen Level Dependent (BOLD) fMRI is a common technique for measuring brain
activation that could be affected by low-level carbon monoxide (CO) exposure from e.g. smoking.
This study aimed to probe the vulnerability of BOLD fMRI to CO and determine whether it may
constitute a significant neuroimaging confound. Low-level (6ppm exhaled) CO effects on BOLD
response were assessed in 12 healthy never-smokers on two separate experimental days (CO
and air control). fMRI tasks were breath-holds (hypercapnia), visual stimulation and fingertapping.
BOLD fMRI response was lower during breath holds, visual stimulation and fingertapping in the
CO protocol compared to the air control protocol. Behavioural and physiological measures
remained unchanged. We conclude that BOLD fMRI might be vulnerable to changes in baseline
CO, and suggest exercising caution when imaging populations exposed to elevated CO levels.
Further work is required to fully elucidate the impact on CO on fMRI and its underlying
mechanisms
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
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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