83 research outputs found
People on Drugs: Credibility of User Statements in Health Communities
Online health communities are a valuable source of information for patients and physicians. However, such user-generated resources are often plagued by inaccuracies and misinformation. In this work we propose a method for automatically establishing the credibility of user-generated medical statements and the trustworthiness of their authors by exploiting linguistic cues and distant supervision from expert sources. To this end we introduce a probabilistic graphical model that jointly learns user trustworthiness, statement credibility, and language objectivity. We apply this methodology to the task of extracting rare or unknown side-effects of medical drugs --- this being one of the problems where large scale non-expert data has the potential to complement expert medical knowledge. We show that our method can reliably extract side-effects and filter out false statements, while identifying trustworthy users that are likely to contribute valuable medical information
Cascades: A view from Audience
Cascades on online networks have been a popular subject of study in the past
decade, and there is a considerable literature on phenomena such as diffusion
mechanisms, virality, cascade prediction, and peer network effects. However, a
basic question has received comparatively little attention: how desirable are
cascades on a social media platform from the point of view of users? While
versions of this question have been considered from the perspective of the
producers of cascades, any answer to this question must also take into account
the effect of cascades on their audience. In this work, we seek to fill this
gap by providing a consumer perspective of cascade.
Users on online networks play the dual role of producers and consumers.
First, we perform an empirical study of the interaction of Twitter users with
retweet cascades. We measure how often users observe retweets in their home
timeline, and observe a phenomenon that we term the "Impressions Paradox": the
share of impressions for cascades of size k decays much slower than frequency
of cascades of size k. Thus, the audience for cascades can be quite large even
for rare large cascades. We also measure audience engagement with retweet
cascades in comparison to non-retweeted content. Our results show that cascades
often rival or exceed organic content in engagement received per impression.
This result is perhaps surprising in that consumers didn't opt in to see tweets
from these authors. Furthermore, although cascading content is widely popular,
one would expect it to eventually reach parts of the audience that may not be
interested in the content. Motivated by our findings, we posit a theoretical
model that focuses on the effect of cascades on the audience. Our results on
this model highlight the balance between retweeting as a high-quality content
selection mechanism and the role of network users in filtering irrelevant
content
All Who Wander: On the Prevalence and Characteristics of Multi-community Engagement
Although analyzing user behavior within individual communities is an active
and rich research domain, people usually interact with multiple communities
both on- and off-line. How do users act in such multi-community environments?
Although there are a host of intriguing aspects to this question, it has
received much less attention in the research community in comparison to the
intra-community case. In this paper, we examine three aspects of
multi-community engagement: the sequence of communities that users post to, the
language that users employ in those communities, and the feedback that users
receive, using longitudinal posting behavior on Reddit as our main data source,
and DBLP for auxiliary experiments. We also demonstrate the effectiveness of
features drawn from these aspects in predicting users' future level of
activity.
One might expect that a user's trajectory mimics the "settling-down" process
in real life: an initial exploration of sub-communities before settling down
into a few niches. However, we find that the users in our data continually post
in new communities; moreover, as time goes on, they post increasingly evenly
among a more diverse set of smaller communities. Interestingly, it seems that
users that eventually leave the community are "destined" to do so from the very
beginning, in the sense of showing significantly different "wandering" patterns
very early on in their trajectories; this finding has potentially important
design implications for community maintainers. Our multi-community perspective
also allows us to investigate the "situation vs. personality" debate from
language usage across different communities.Comment: 11 pages, data available at
https://chenhaot.com/pages/multi-community.html, Proceedings of WWW 2015
(updated references
Competition and Selection Among Conventions
In many domains, a latent competition among different conventions determines
which one will come to dominate. One sees such effects in the success of
community jargon, of competing frames in political rhetoric, or of terminology
in technical contexts. These effects have become widespread in the online
domain, where the data offers the potential to study competition among
conventions at a fine-grained level.
In analyzing the dynamics of conventions over time, however, even with
detailed on-line data, one encounters two significant challenges. First, as
conventions evolve, the underlying substance of their meaning tends to change
as well; and such substantive changes confound investigations of social
effects. Second, the selection of a convention takes place through the complex
interactions of individuals within a community, and contention between the
users of competing conventions plays a key role in the convention's evolution.
Any analysis must take place in the presence of these two issues.
In this work we study a setting in which we can cleanly track the competition
among conventions. Our analysis is based on the spread of low-level authoring
conventions in the eprint arXiv over 24 years: by tracking the spread of macros
and other author-defined conventions, we are able to study conventions that
vary even as the underlying meaning remains constant. We find that the
interaction among co-authors over time plays a crucial role in the selection of
them; the distinction between more and less experienced members of the
community, and the distinction between conventions with visible versus
invisible effects, are both central to the underlying processes. Through our
analysis we make predictions at the population level about the ultimate success
of different synonymous conventions over time--and at the individual level
about the outcome of "fights" between people over convention choices.Comment: To appear in Proceedings of WWW 2017, data at
https://github.com/CornellNLP/Macro
High Levels of Education Are Associated With an Increased Risk of Latent Autoimmune Diabetes in Adults: Results from the Nord-Trøndelag Health Study
Although autoimmune diabetes in adults is a common form of diabetes, knowledge on risk factors and long term consequences of the disease is limited. The aims of this thesis were to investigate the influence of socioeconomic factors (education and occupation), sleep disturbances and psychological well-being on the risk of developing autoimmune diabetes in adults, to investigate whether genetic variation in the melatonin receptor 1B (MTNR1B) contributes to the association between poor sleep and type 2 diabetes which has been previously suggested, and finally to investigate the risk of mortality from all causes, cardiovascular disease and ischemic heart disease in adult-onset autoimmune diabetes, with consideration of the possible influence of metabolic risk factors, glycaemic control, lifestyle factors and socioeconomic position.
These studies are based on data from the Norwegian HUNT Study, to date the largest population-based study where incident cases of autoimmune diabetes in adults can be separated from cases of type 2 diabetes. The HUNT Study consists of three separate surveys performed on three occasions in 1984-2008 and contains information from questionnaires, clinical examinations and blood samples. Information on mortality was obtained by linkage to the national Cause of Death Registry. Individuals who were positive for antibodies against glutamic acid decarboxylase and with onset of diabetes at ≥35 years were classified as having autoimmune diabetes in adults.
The main finding of Study I was that high educational levels (university versus primary school) were associated with an increased risk of autoimmune diabetes in adults (HR 1.98, 95% CI 1.21-3.26) after adjustment for BMI, physical activity, smoking, alcohol consumption, and family history of diabetes, whereas type 2 diabetes was more common in those with low education. An increased risk of autoimmune diabetes in adults was also seen in individuals who reported having sleep disturbances and low psychological well-being (HR 1.84, 95% CI 1.10-3.09), a risk similar to that seen in type 2 diabetes (HR 1.31, 95% CI 1.13-1.50) (Study II). The results from Study III indicated that there was no influence of the MTNR1B genetic variant on the association between poor sleep and type 2 diabetes. The association remained after adjustment for genotype and was seen in non-carriers as well as in carriers of the risk allele. Mortality from all causes (HR 1.55, 95% CI 1.25-1.92), cardiovascular disease (HR 1.87, 95% CI 1.40-2.48) and ischemic heart disease (HR 2.39, 95% CI 1.57-3.64) was increased in autoimmune diabetes in adults compared to individuals without diabetes. Importantly, mortality risk was as high as in type 2 diabetes, despite a more favourable metabolic risk profile in patients with autoimmune diabetes. In these patients, excess mortality appeared to be primarily associated with poor glycaemic control.
These findings suggest, for the first time, that socioeconomic and psychosocial factors contribute to the development of autoimmune diabetes in adults. The results are in line with previous data indicating that the aetiology of autoimmune diabetes is partly similar to that of type 2 diabetes but suggest, also, that there are other, currently unidentified, environmental risk factors for autoimmune diabetes that remain to be explored. Finally, the results indicate that survival in individuals with autoimmune diabetes with adult onset would be improved by a more effective treatment
A large topographic feature on the surface of the trans-Neptunian object (307261) 2002 MS measured from stellar occultations
This work aims at constraining the size, shape, and geometric albedo of the
dwarf planet candidate 2002 MS4 through the analysis of nine stellar
occultation events. Using multichord detection, we also studied the object's
topography by analyzing the obtained limb and the residuals between observed
chords and the best-fitted ellipse. We predicted and organized the
observational campaigns of nine stellar occultations by 2002 MS4 between 2019
and 2022, resulting in two single-chord events, four double-chord detections,
and three events with three to up to sixty-one positive chords. Using 13
selected chords from the 8 August 2020 event, we determined the global
elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the
object's rotational information from the literature, constrains the object's
size, shape, and albedo. Additionally, we developed a new method to
characterize topography features on the object's limb. The global limb has a
semi-major axis of 412 10 km, a semi-minor axis of 385 17 km, and
the position angle of the minor axis is 121 16. From
this instantaneous limb, we obtained 2002 MS4's geometric albedo and the
projected area-equivalent diameter. Significant deviations from the fitted
ellipse in the northernmost limb are detected from multiple sites highlighting
three distinct topographic features: one 11 km depth depression followed by a
25 km height elevation next to a crater-like depression with an
extension of 322 39 km and 45.1 1.5 km deep. Our results present an
object that is 138 km smaller in diameter than derived from thermal
data, possibly indicating the presence of a so-far unknown satellite. However,
within the error bars, the geometric albedo in the V-band agrees with the
results published in the literature, even with the radiometric-derived albedo
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