12,220 research outputs found
Mutual-Excitation of Cryptocurrency Market Returns and Social Media Topics
Cryptocurrencies have recently experienced a new wave of price volatility and
interest; activity within social media communities relating to cryptocurrencies
has increased significantly. There is currently limited documented knowledge of
factors which could indicate future price movements. This paper aims to
decipher relationships between cryptocurrency price changes and topic
discussion on social media to provide, among other things, an understanding of
which topics are indicative of future price movements. To achieve this a
well-known dynamic topic modelling approach is applied to social media
communication to retrieve information about the temporal occurrence of various
topics. A Hawkes model is then applied to find interactions between topics and
cryptocurrency prices. The results show particular topics tend to precede
certain types of price movements, for example the discussion of 'risk and
investment vs trading' being indicative of price falls, the discussion of
'substantial price movements' being indicative of volatility, and the
discussion of 'fundamental cryptocurrency value' by technical communities being
indicative of price rises. The knowledge of topic relationships gained here
could be built into a real-time system, providing trading or alerting signals.Comment: 3rd International Conference on Knowledge Engineering and
Applications (ICKEA 2018) - Moscow, Russia (June 25-27 2018
A Review of Peer Relationships and Friendships in Youth With ADHD
Objective: The purpose of this essay is to examine peer relationships in youth with ADHD and to review current peer functioning interventions.
Method: The studies included in this review were identified using the following search terms: “attention-deficit/hyperactivity disorder,” “ADHD,” “peer relationships,” “friendships,” “social skills,” “intervention,” and “treatment.” Other than a few seminal studies published prior to 2000, studies included were published between 2000 and 2012.
Results/Discussion: Background information regarding peer relationship difficulties and specific social skills deficits of youth with ADHD is reviewed and current social skills and friendship intervention programs are examined. Future directions also are provided
The Jets of AGN as giant co-axial cables
The currents carried by the jets of active galactic nuclei (AGNs) can be
probed using maps of the Faraday rotation measure (RM), since a jet current
will be accompanied by a toroidal magnetic (B) field, which will give rise to a
systematic change in the RM across the jet. The aim of this study is to
identify new AGNs displaying statistically significant transverse RM gradients
across their parsec-scale jets, and to look for overall patterns in the implied
directions for the toroidal B-field components and jet currents. We have
carried out new analyses of Faraday RM maps derived from previously published
8.1, 8.4, 12.1 and 15.3 GHz data obtained in 2006 on the NRAO VLBA. In a number
of important ways, our procedures were identical to those of the original
authors, but several other key aspects of the new imaging and analysis differ
from the original methods. Our new analysis has substantially increased the
number of AGNs known to display transverse RM gradients. The collected data on
parsec and kiloparsec scales indicate that the current typically flows inward
along the jet axis and outward in a more extended region surrounding the jet,
typical to the current structure of a coaxial cable, accompanied by a
self-consistent system of nested helical B fields, whose toroidal components
give rise to the observed transverse RM gradients. These new results make it
possible for the first time to conclusively demonstrate the existence of a
preferred direction for the toroidal B-field components - and therefore of the
currents - of AGN jets. Discerning the origin of this current-field system is
of cardinal importance for understanding the physical mechanisms leading to the
formation of the intrinsic jet B field, which likely plays an important role in
the propagation and collimation of the jets; one possibility is the action of a
"cosmic battery".Comment: 12 pages, 2 figures, 3 tables; accepted for publication in Astronomy
& Astrophysic
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