1,721,260 research outputs found
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
Epidemiology of Multiple Sclerosis
No full textMultiple sclerosis (MS) is a chronic disabling disease of the central nervous
system commonly affecting young adults. Pathologically, there are patches
of inflammation (plaques) with demyelination of axons and associated loss
of oligodendrocytes. Genome-wide association studies have identified over
105 loci of susceptibility, but the total number of possible contributory loci
may be considerably higher.
Family recurrence risks are available for several northern hemisphere
countries, but there are few data for the southern hemisphere and regions
at lower latitude such as Australia. The published family data could provide
useful recurrence risks if appropriately analysed. Segregation analysis can
be used to model the genetic architecture of MS.
There is a global latitude gradient in MS prevalence, and the incidence
of MS is increasing (particularly in females). These changes suggest a major
role for environmental factors in the causation of disease.
In the last 20 years there has been increasing evidence for the role of smoking in the aetiology of multiple sclerosis. Cigarette smoking is also
associated with increased risk of developing the progressive form of MS.
This risk factor has not previously been analysed in Queensland. Furthermore,
cigarette smoking represents a possible cause of the changing prevalence of
MS over time.
Methods
The family risks in Australia were measured in three regions at different
latitudes. Immediate and extended family pedigrees were collected for three
cohorts of MS patients in Queensland, Victoria and Tasmania. Age of onset
data from Queensland were utilised to estimate age-adjusted recurrence
rates.
Meta-analysis of all available family recurrence risk data was performed
to define risks to relatives. Standard methods of meta-analysis were combined
with novel approaches to age adjustment to provide directly comparable
estimates of lifetime risk. Segregation analysis was used to estimate the
proportion of the overall genetic risk that can be attributed to identified
susceptibility genes.
To evaluate risks from smoking in Queensland, a large case-control study
was performed, comparing risk of MS (by smoking habit) using regression
modelling.
The risk of developing progressive disease was measured in a cohort
from an MS clinic in Queensland, followed from first clinic attendance until
the onset of clinically determined progressive disease. Risk of progression was analysed with gender, age, age of onset, exposure to disease modifying
therapy, and smoking status as covariates in a Cox proportional hazards
analysis.
Finally, a comprehensive meta-analysis was performed of eligible casecontrol
and cohort studies that evaluated the risk of MS in smokers and exsmokers.
The influence of study design, gender, latitude and year of study
were explored with regression modelling.
Results
Recurrence risks in Australia were significantly lower than in studies from
northern hemisphere populations. The age-adjusted risk for siblings across
Australia was 2.1% compared with 3.5% for the northern hemisphere. A
similar pattern was seen for other relatives. The risks to relatives were
proportional to the population risks for each site, and hence the relative
risk for siblings (lS) was similar across all sites.
From the meta-analysis of family recurrence risks, the overall recurrence
risk for monozygotic twins was 18.2% and for siblings 2.7%. The recurrence
risk for dizygotic twins was significantly higher than for siblings. The overall
estimate of sibling relative risk (lS) was 16.8. Risks for older relatives
(parents, siblings, aunts, uncles and cousins) show a latitudinal gradient, in
line with population risk. No latitudinal gradient for lS was seen. Segregation
analysis supports a multiplicative model of one locus of moderate effect with
many loci of small effect. The estimated contribution of the known MS loci is 18–24% of lS.
The case-control study in Queensland confirmed an association between
increased risk of MS and smoking. The overall adjusted odds ratio was
1.9 (95% confidence interval, CI 1.5–2.5) for ever smokers. There was no
statistically significant difference in the risks for males and females.
In the progression study, there were significantly higher risks of secondary
progressive disease in males (Hazard Ratio, HR 1.83, 95% CI 1.3–2.7) and
in ever smokers (HR 1.4, 95% CI 1.0–2.0). Progressive disease occurred
approximately 4 years earlier in ever smokers. Smoking did not affect age
of onset of primary progressive disease.
The meta-analysis of smoking risk included 26 studies representing 8615
cases and 392,352 controls and an additional 792 cases included from a
total cohort population of 601,492 individuals, representing more than 9
million person-years. There was a consistent association between smoking
and MS with an odds ratio of approximately 1.5, with males at higher risk.
This finding was independent of study design. However, latitude and year
of study may have unexpected influence. Smoking appeared to confer a
greater risk to females living closer to the equator than to females at higher
latitudes. Additionally, the effect of cigarette smoke exposure on MS risk
may not be fixed over time, but could be increasing.
Discussion
The familial recurrence risk of MS in Australia is lower than in previously
reported studies. This is directly related to the lower population prevalence
of MS. The overall genetic susceptibility in Australia as measured by the lS is similar to that seen in the northern hemisphere, suggesting that the
difference in population risk is explained largely by environmental factors
rather than by genetic admixture.
The meta-analysis of family data supports the notion of MS risk being
derived from multiple susceptibility genes and environmental factors. Genetic
susceptibility appears to be independent of latitude, and the latitudinal
gradient of MS prevalence is likely due to environmental factors.
The results of the case-control study in Queensland replicate existing
work that has shown cigarette smoking increases the risk of MS. Cigarette
smoking represents an important modifiable risk factor for the development
of MS.
Cigarette smoking was also associated with earlier onset of progressive
disease in the large clinical cohort studied in Queensland. For patients with
relapsing-remitting disease, smoking cessation should be encouraged.
The results of the meta-analysis of smoking studies suggest a threshold
model of MS risk that includes a fairly constant genetic risk (for Caucasian
populations) together with variable environmental risks which are dominated
by vitamin D deficiency at higher latitudes and are more significant in women who have an intrinsically lower threshold for development of disease.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School of MedicineGriffith HealthFull Tex
Brain health: time matters in multiple sclerosis
Full text linkIntroduction We present international consensus recommendations for improving diagnosis, management and treatment access in multiple sclerosis (MS). Our vision is that these will be used widely among those committed to creating a better future for people with MS and their families. Methods Structured discussions and literature searches conducted in 2015 examined the personal and economic impact of MS, current practice in diagnosis, treatment and management, definitions of disease activity and barriers to accessing disease-modifying therapies (DMTs). Results Delays often occur before a person with symptoms suggestive of MS sees a neurologist. Campaigns to raise awareness of MS are needed, as are initiatives to improve access to MS healthcare professionals and services. We recommend a clear treatment goal: to maximize neurological reserve, cognitive function and physical function by reducing disease activity. Treatment should start early, with DMT and lifestyle measures. All parameters that predict relapses and disability progression should be included in the definition of disease activity and monitored regularly when practical. On suboptimal control of disease activity, switching to a DMT with a different mechanism of action should be considered. A shared decision-making process that embodies dialogue and considers all appropriate DMTs should be implemented. Monitoring data should be recorded formally in registries to generate real-world evidence. In many jurisdictions, access to DMTs is limited. To improve treatment access the relevant bodies should consider all costs to all parties when conducting economic evaluations and encourage the continuing investigation, development and use of cost-effective therapeutic strategies and alternative financing models. Conclusions The consensus findings of an international author group recommend a therapeutic strategy based on proactive monitoring and shared decision-making in MS. Early diagnosis and improved treatment access are also key components
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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