29,384 research outputs found
Twitter in Academic Conferences: Usage, Networking and Participation over Time
Twitter is often referred to as a backchannel for conferences. While the main
conference takes place in a physical setting, attendees and virtual attendees
socialize, introduce new ideas or broadcast information by microblogging on
Twitter. In this paper we analyze the scholars' Twitter use in 16 Computer
Science conferences over a timespan of five years. Our primary finding is that
over the years there are increasing differences with respect to conversation
use and information use in Twitter. We studied the interaction network between
users to understand whether assumptions about the structure of the
conversations hold over time and between different types of interactions, such
as retweets, replies, and mentions. While `people come and people go', we want
to understand what keeps people stay with the conference on Twitter. By casting
the problem to a classification task, we find different factors that contribute
to the continuing participation of users to the online Twitter conference
activity. These results have implications for research communities to implement
strategies for continuous and active participation among members
Measurement of air and nitrogen fluorescence light yields induced by electron beam for UHECR experiments
Most of the Ultra High Energy Cosmic Ray (UHECR) experiments and projects
(HiRes, AUGER, TA, EUSO, TUS,...) use air fluorescence to detect and measure
extensive air showers (EAS). The precise knowledge of the Fluorescence Light
Yield (FLY) is of paramount importance for the reconstruction of UHECR. The
MACFLY - Measurement of Air Cherenkov and Fluorescence Light Yield - experiment
has been designed to perform such FLY measurements. In this paper we will
present the results of FLY in the 290-440 nm wavelength range for dry air and
pure nitrogen, both excited by electrons with energy of 1.5 MeV, 20 GeV and 50
GeV. The experiment uses a 90Sr radioactive source for low energy measurement
and a CERN SPS electron beam for high energy. We find that the FLY is
proportional to the deposited energy (E_d) in the gas and we show that the air
fluorescence properties remain constant independently of the electron energy.
At the reference point: atmospheric dry air at 1013 hPa and 23C, the ratio
FLY/E_d=17.6 photon/MeV with a systematic error of 13.2%.Comment: 19 pages, 8 figures. Accepted for publication in Astroparticle
Physic
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