5,009 research outputs found
Applying Abstract Argumentation Theory to Cooperative Game Theory
We apply ideas from abstract argumentation theory to study cooperative game
theory. Building on Dung's results in his seminal paper, we further the
correspondence between Dung's four argumentation semantics and solution
concepts in cooperative game theory by showing that complete extensions (the
grounded extension) correspond to Roth's subsolutions (respectively, the
supercore). We then investigate the relationship between well-founded
argumentation frameworks and convex games, where in each case the semantics
(respectively, solution concepts) coincide; we prove that three-player convex
games do not in general have well-founded argumentation frameworks.Comment: 15 pages, 1 tabl
Validity of self-reported smoking status: comparison of patients admitted to hospital with acute coronary syndrome and the general population
Many studies rely on self-reported smoking status. We hypothesized that patients with acute coronary syndrome (ACS), a smoking-related condition, would be more prone to misclassify themselves as ex-smokers, because of pressure to quit. We compared patients admitted with ACS with a general population survey conducted in the same country at a similar time. We determined whether ACS patients who classified themselves as ex-smokers (n = 635) were more likely to have cotinine levels suggestive of smoking deception than self-reported ex-smokers in the general population (n = 289). On univariate analysis, the percentage of smoking deceivers was similar among ACS patients and the general population (11% vs. 12%, p = .530). Following adjustment for age, sex and exposure to environmental tobacco smoke, ACS patients were significantly more likely to misclassify themselves (adjusted OR = 14.06, 95% CI 2.13-93.01, p = .006). There was an interaction with age whereby the probability of misclassification fell significantly with increasing age in the ACS group (adjusted OR = 0.95, 95% CI 0.93-0.97, p<.001), but not in the general population. Overall, smoking deception was more common among ACS patients than the general population. Studies comparing patients with cardiovascular disease and healthy individuals risk introducing bias if they rely solely on self-reported smoking status. Biochemical confirmation should be undertaken in such studies
A Graph-Based Context-Aware Model to Understand Online Conversations
Online forums that allow for participatory engagement between users have been
transformative for the public discussion of many important issues. However,
such conversations can sometimes escalate into full-blown exchanges of hate and
misinformation. Existing approaches in natural language processing (NLP), such
as deep learning models for classification tasks, use as inputs only a single
comment or a pair of comments depending upon whether the task concerns the
inference of properties of the individual comments or the replies between pairs
of comments, respectively. But in online conversations, comments and replies
may be based on external context beyond the immediately relevant information
that is input to the model. Therefore, being aware of the conversations'
surrounding contexts should improve the model's performance for the inference
task at hand.
We propose GraphNLI, a novel graph-based deep learning architecture that uses
graph walks to incorporate the wider context of a conversation in a principled
manner. Specifically, a graph walk starts from a given comment and samples
"nearby" comments in the same or parallel conversation threads, which results
in additional embeddings that are aggregated together with the initial
comment's embedding. We then use these enriched embeddings for downstream NLP
prediction tasks that are important for online conversations. We evaluate
GraphNLI on two such tasks - polarity prediction and misogynistic hate speech
detection - and found that our model consistently outperforms all relevant
baselines for both tasks. Specifically, GraphNLI with a biased root-seeking
random walk performs with a macro-F1 score of 3 and 6 percentage points better
than the best-performing BERT-based baselines for the polarity prediction and
hate speech detection tasks, respectively.Comment: 25 pages, 9 figures. arXiv admin note: text overlap with
arXiv:2202.0817
Biochemical and Structural Characterization of a Schiff Base in the Radical-Mediated Biosynthesis of 4-Demethylwyosine by TYW1
TYW1 is a radical S-adenosyl-l-methionine (SAM) enzyme that catalyzes the condensation of pyruvate and N-methylguanosine to form the posttranscriptional modification, 4-demethylwyosine, in situ on transfer RNA (tRNA). Two mechanisms have been proposed for this transformation, with one of the possible mechanisms invoking a Schiff base intermediate formed between a conserved lysine residue and pyruvate. Utilizing a combination of mass spectrometry and X-ray crystallography, we have obtained evidence to support the formation of a Schiff base lysine adduct in TYW1. When 13 C labeled pyruvate is used, the mass shift of the adduct matches that of the labeled pyruvate, indicating that pyruvate is the source of the adduct. Furthermore, a crystal structure of TYW1 provides visualization of the Schiff base lysine-pyruvate adduct, which is positioned directly adjacent to the auxiliary [4Fe-4S] cluster. The adduct coordinates the unique iron of the auxiliary cluster through the lysine nitrogen and a carboxylate oxygen, reminiscent of how the radical SAM [4Fe-4S] cluster is coordinated by SAM. The structure provides insight into the binding site for tRNA and further suggests how radical SAM chemistry can be combined with Schiff base chemistry for RNA modification.National Science Foundation (U.S.) (Grant 1122374
Who has the last word? Understanding How to Sample Online Discussions
In online debates individual arguments support or attack each other, leading
to some subset of arguments being considered more relevant than others.
However, in large discussions readers are often forced to sample a subset of
the arguments being put forth. Since such sampling is rarely done in a
principled manner, users may not read all the relevant arguments to get a full
picture of the debate. This paper is interested in answering the question of
how users should sample online conversations to selectively favour the
currently justified or accepted positions in the debate. We apply techniques
from argumentation theory and complex networks to build a model that predicts
the probabilities of the normatively justified arguments given their location
in online discussions. Our model shows that the proportion of replies that are
supportive, the number of replies that comments receive, and the locations of
un-replied comments all determine the probability that a comment is a justified
argument. We show that when the degree distribution of the number of replies is
homogeneous along the discussion, for acrimonious discussions, the distribution
of justified arguments depends on the parity of the graph level. In supportive
discussions the probability of having justified comments increases as one moves
away from the root. For discussion trees that have a non-homogeneous in-degree
distribution, for supportive discussions we observe the same behaviour as
before, while for acrimonious discussions we cannot observe the same
parity-based distribution. This is verified with data obtained from the online
debating platform Kialo. By predicting the locations of the justified arguments
in reply trees, we can suggest which arguments readers should sample to grasp
the currently accepted opinions in such discussions. Our models have important
implications for the design of future online debating platforms
‘Dominant ethnicity’ and the ‘ethnic-civic’ dichotomy in the work of A. D. Smith
This article considers the way in which the work of Anthony Smith has helped to structure debates surrounding the role of ethnicity in present-day nations. Two major lines of enquiry are evident here. First, the contemporary role of dominant ethnic groups within 'their' nations and second, the interplay between ethnic and civic elements in nationalist argument. The two processes are related, but maintain elements of distinctiveness. Smith's major contribution to the dominant ethnicity debate has been to disembed ethnicity from the ideologically-charged and/or anglo-centric discourse of ethnic relations and to place it in historical context, thereby opening up space for dominant group ethnicity to be considered as a distinct phenomenon. This said, Smith's work does not adequately account for the vicissitudes of dominant ethnicity in the contemporary West. Building on the classical works of Hans Kohn and Friedrich Meinecke, Anthony Smith has also made a seminal contribution to the debate on civic and ethnic forms of national identity and nationalist ideology. As well as freeing this debate from the strong normative overtones which it has often carried, he has continued to insist that the terms civic and ethnic should be treated as an ideal-typical distinction rather than a scheme of classification
Vailulu’u Seamount
Author Posting. © Oceanography Society, 2010. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 23, 1 (2010): 164-165.Vailulu’u seamount is an active underwater
volcano that marks the end of
the Samoan hotspot trail
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