12 research outputs found
Modeling the structure and evolution of discussion cascades
We analyze the structure and evolution of discussion cascades in four popular
websites: Slashdot, Barrapunto, Meneame and Wikipedia. Despite the big
heterogeneities between these sites, a preferential attachment (PA) model with
bias to the root can capture the temporal evolution of the observed trees and
many of their statistical properties, namely, probability distributions of the
branching factors (degrees), subtree sizes and certain correlations. The
parameters of the model are learned efficiently using a novel maximum
likelihood estimation scheme for PA and provide a figurative interpretation
about the communication habits and the resulting discussion cascades on the
four different websites.Comment: 10 pages, 11 figure
A Preferential Attachment Model for the Stellar Initial Mass Function
Accurate specification of a likelihood function is becoming increasingly
difficult in many inference problems in astronomy. As sample sizes resulting
from astronomical surveys continue to grow, deficiencies in the likelihood
function lead to larger biases in key parameter estimates. These deficiencies
result from the oversimplification of the physical processes that generated the
data, and from the failure to account for observational limitations.
Unfortunately, realistic models often do not yield an analytical form for the
likelihood. The estimation of a stellar initial mass function (IMF) is an
important example. The stellar IMF is the mass distribution of stars initially
formed in a given cluster of stars, a population which is not directly
observable due to stellar evolution and other disruptions and observational
limitations of the cluster. There are several difficulties with specifying a
likelihood in this setting since the physical processes and observational
challenges result in measurable masses that cannot legitimately be considered
independent draws from an IMF. This work improves inference of the IMF by using
an approximate Bayesian computation approach that both accounts for
observational and astrophysical effects and incorporates a physically-motivated
model for star cluster formation. The methodology is illustrated via a
simulation study, demonstrating that the proposed approach can recover the true
posterior in realistic situations, and applied to observations from
astrophysical simulation data
Analysis of interaction and co-editing patterns amongst OpenStreetMap contributors
OpenStreetMap (OSM) is a very well known and popular Volunteered Geographic Information (VGI) project on the Internet. In January 2013 OSM gained its one millionth registered member. Several studies have shown that only a small percentage of these registered members carry out the large majority of the mapping and map editing work. In this article we discuss results from a social-network based analysis of seven major cities in OSM in an effort to understand if there is quantitative evidence of interaction and collaboration between OSM members in these areas. Are OSM contributors working on their own to build OSM databases in these cities or is there evidence of collaboration between OSM contributors? We find that in many cases high frequent contributors (“senior mappers”) perform very large amounts of mapping work on their own but do interact (edit/update) contributions from lower frequency contributors
Handbook of Technical Communication
International audienceThe handbook "Technical Communication" brings together a variety of topics which range from the role of technical media in human communication to the linguistic, multimodal enhancement of present-day technologies. It covers the area of computer-mediated text, voice and multimedia communication as well as of technical documentation. In doing so, the handbook takes professional and private communication into account. Special emphasis is put on technical communication based on digital technologies and its standardization in system development. In summary, the handbook deals with theoretical issues of technical communication and its practical impact on the development and usage of text and speech technologies