1,721,218 research outputs found
The structure of stepped surfaces. On the investigation of the atomic structure of (stepped) copper surfaces with Low Energy Ion Scattering
Full text linkIn een vaste stof bevinden zich ongeveer 10 2 3 atomen per kubieke centimeter, en aan het oppervlak ongeveer 10 1 5 per vierkante centimeter. Aangezien dit laatste getal te verwaarlozen is ten opzichte van het eerste, zou men kunnen denken dat de invloed van het oppervlak op de eigenschappen van de materie te verwaarlozen is. Echter, omdat de wisselwerking van een stukje materie met zijn omgeving noodzakelijkerwijs altijd plaatsvindt via het oppervlak ervan, is voor diverse andere eigenschappen de aard van het oppervlak van groot belang. Bij sommige van deze eigenschappen zijn de aanwezige vrije electronen van belang, en bij andere meer de positie van de atomen zelf. Over deze laatste karakteristiek van de materie, de positie van atomen aan het oppervlak, handelt dit proefschrift. ...
Zie: Inleiding en samenvatting
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
Prothrombotic gene variation and cerebral ischaemia of arterial origin
No full textStroke is the second most common cause of death and a leading cause of adult disability worldwide. Ischaemia is the cause in about 80% of all strokes. Atherosclerotic lesions in the cerebropetal and intracranial arteries lead to cerebral ischaemia of arterial origin. Cerebral ischaemia and atherosclerosis have a genetic basis. Genetic factors may help to identify stroke patients at high risk for new events. We studied associations between prothrombotic gene variation and cerebral ischaemia of arterial origin. Chapter 3 is a cohort study among 887 patients with cerebral ischaemia. During a 4.6-year mean follow-up period new vascular events occurred in 135 patients. None of 22 selected prothrombotic variants was associated with the occurrence of new vascular events. This study does not support the use of prothrombotic gene variants to identify stroke patients at increased risk for new vascular events. Chapter 4 is a case-control study in 316 long-term survivors (cases) and 887 patients with recent cerebral ischaemia (controls). Only two of 23 prothrombotic variants were associated with reduced survival after stroke. These variants do not appear to play an important role in survival after cerebral ischemia. In Chapter 5 we studied the effect of prothrombotic gene variation on atherosclerosis in 689 patients with nondisabling cerebral ischaemia. None of 22 prothrombotic variants was associated with carotid intima-media thickness or age. Only one variant was associated with symptomatic carotid stenosis. Prothrombotic gene variation does not seem to affect the pathogenesis of atherosclerosis. In Chapter 6 we compared genotype frequencies between 621 stroke patients with large vessel disease (LVD) and 266 patients with small vessel disease (SVD). Only one of 22 variants was not equally prevalent among LVD and SVD patients. Prothrombotic gene variants may not be specific for one stroke subtype. Claims about genetic associations with specific subtypes should be interpreted with caution. In Chapter 7 we found the carotid intima-media thickness to be larger in patients with LVD than in those with SVD. Carotid intima-media thickness is an established marker of artherosclerosis. This supports the hypothesis that LVD and SVD have a different pathogenesis. Chapter 8 is a case-control study among 190 young women with ischaemic stroke and 767 women without cardiovascular disease. The Phenylalanine allele of the Tyr204Phe variant conferred a 9-fold increased risk of stroke. The combination of oral contraceptive use and carriership of the 204Phe allele led to a 20-fold increase in stroke risk. TheTyr204Phe variant of the coagulation factor XIII subunit A gene constitutes a strong and common genetic factor for ischaemic stroke in young women. Genetic screening preceding oral contraceptive use is not warranted because of the low incidence of ischaemic stroke among young women. Chapter 9 is a nested case-control study in patients with cerebral ischaemia on oral anticoagulant treatment. A variant in the alpha fibrinogen gene was associated with a decreased anticoagulant-related bleeding risk and factor V Leiden conferred an increased bleeding risk. If replicated, these findings may have implications for the future selection of patients for oral anticoagulant treatment
ESPRIT (European/Australasian Stroke Prevention in Reversible Ischaemia Trial) and related studies
No full text1. We compared 120 patients who had had a large subcortical infarct with 324 who had had a small deep infarct and with 211 who had had a cortical infarct from the same cohort. We found no differences in risk factor profiles between the three groups, nor a difference in stroke recurrence rate. 2. We demonstrated, by means of a questionnaire filled in by 29 neurologists with special interest in stroke, that there is very little agreement on the classification of cause of death in patients who die after a stroke in the setting of a clinical trial. We developed guidelines for the classification of the cause of death after stroke, with the criteria ‘interval between stroke and death’ (cutoff point at 1 month) and ‘best Rankin grade after stroke’ (cutoff at 3). 3. The results of the first part of the European/Australasian Stroke Prevention in Reversible Ischaemia Trial (ESPRIT) are described, in which patients who suffered a Transient Ischaemic Attack (TIA) or non disabling ischaemic stroke of presumed arterial origin were randomized between the combination therapy of aspirin plus dipyridamole (n=1363) and aspirin alone (n=1376). Less patients assigned to the combination therapy (173, 13%) than to aspirin alone (216, 16%) suffered the primary outcome event, which was the composite of death from all vascular causes, non-fatal stroke, non-fatal myocardial infarction, or major bleeding complication, whichever happened first. The corresponding hazard ratio was 0.80 (95% confidence interval 0.66-0.98). 4. The results of the second, prematurely halted, part of ESPRIT are presented. In this part a comparison was made between medium intensity oral anticoagulants (aimed international normalized ratio (INR) 2.0-3.0) and aspirin in the secondary prevention after TIA or non disabling ischaemic stroke of arterial origin. There was no difference in the incidence of the primary outcome event (99 of 536 patients, 19% versus 98 of 532, 18%). There were, however, more major bleeding complications in patients assigned to anticoagulation (45 vs. 18, hazard ratio 2.56 (95% confidence interval 1.48-4.43). 5. The results of an individual patient data based meta-analysis of all trials that compared the combination therapy of aspirin plus dipyridamole with aspirin alone in the secondary prevention after TIA or stroke of arterial origin are presented. Data from 7612 patients (3800 allocated to aspirin plus dipyridamole and 3812 to aspirin alone) were available for this analysis. The hazard ratio for the composite event of vascular death, non-fatal myocardial infarction and non-fatal stroke was 0.82 (95% CI 0.72-0.92). Hazard ratios did not differ in subgroup analyses based on patient characteristics, nor across baseline risk strata as assessed with two different risk scores. 6. We did an exploratory analysis on data from ESPRIT and from the Second European Stroke Prevention Study (ESPS 2), with the aim to identify risk factors for the development of headache during treatment with dipyridamole. The factors we found to be associated with discontinuation of dipyridamole because of headache were female sex, no (relevant) ischemic lesion on brain imaging and not smoking
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
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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