60,414 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
SOTXTSTREAM: Density-based self-organizing clustering of text streams
A streaming data clustering algorithm is presented building upon the density-based selforganizing stream clustering algorithm SOSTREAM. Many density-based clustering algorithms are limited by their inability to identify clusters with heterogeneous density. SOSTREAM addresses this limitation through the use of local (nearest neighbor-based) density determinations. Additionally, many stream clustering algorithms use a two-phase clustering approach. In the first phase, a micro-clustering solution is maintained online, while in the second phase, the micro-clustering solution is clustered offline to produce a macro solution. By performing self-organization techniques on micro-clusters in the online phase, SOSTREAM is able to maintain a macro clustering solution in a single phase. Leveraging concepts from SOSTREAM, a new density-based self-organizing text stream clustering algorithm, SOTXTSTREAM, is presented that addresses several shortcomings of SOSTREAM. Gains in clustering performance of this new algorithm are demonstrated on several real-world text stream datasets
FPGA Based Data Read-Out System of the Belle 2 Pixel Detector
The upgrades of the Belle experiment and the KEKB accelerator aim to increase
the data set of the experiment by the factor 50. This will be achieved by
increasing the luminosity of the accelerator which requires a significant
upgrade of the detector. A new pixel detector based on DEPFET technology will
be installed to handle the increased reaction rate and provide better vertex
resolution. One of the features of the DEPFET detector is a long integration
time of 20 {\mu}s, which increases detector occupancy up to 3 %. The detector
will generate about 2 GB/s of data. An FPGA-based two-level read-out system,
the Data Handling Hybrid, was developed for the Belle 2 pixel detector. The
system consists of 40 read-out and 8 controller modules. All modules are built
in {\mu}TCA form factor using Xilinx Virtex-6 FPGA and can utilize up to 4 GB
DDR3 RAM. The system was successfully tested in the beam test at DESY in
January 2014. The functionality and the architecture of the Belle 2 Data
Handling Hybrid system as well as the performance of the system during the beam
test are presented in the paper.Comment: Transactions on Nuclear Science, Proceedings of the 19th Real Time
Conference, Preprin
In a search for a shape maximizing packing fraction for two-dimensional random sequential adsorption
Random sequential adsorption (RSA) of various two dimensional objects is
studied in order to find a shape which maximizes the saturated packing
fraction. This investigation was begun in our previous paper [Cie\'sla et al.,
Phys. Chem. Chem. Phys. 17, 24376 (2015)], where the densest packing was
studied for smoothed dimers. Here this shape is compared with a smoothed
-mers, spherocylinders and ellipses. It is found that the highest packing
fraction out of the studied shapes is and is obtained for
ellipses having long-to-short axis ratio of , which is also the largest
anisotropy among the investigated shapes.Comment: 14 pages, 7 fiure
Microscopic basis for pattern formation and anomalous transport in two-dimensional active gels
Active gels are a class of biologically-relevant material containing embedded
agents that spontaneously generate forces acting on a sparse filament network.
In vitro experiments of protein filaments and molecular motors have revealed a
range of non- equilibrium pattern formation resulting from motor motion along
filament tracks, and there are a number of hydrodynamic models purporting to
describe such systems. Here we present results of extensive simulations
designed to elucidate the microscopic basis underpinning macroscopic flow in
active gels. Our numerical scheme includes thermal fluctuations in filament
positions, excluded volume interactions, and filament elasticity in the form of
bending and stretching modes. Motors are represented individually as bipolar
springs governed by rate-based rules for attachment, detachment and
unidirectional motion of motor heads along the filament contour. We
systematically vary motor density and speed, and uncover parameter regions
corresponding to unusual statics and dynamics which overlap but do not
coincide. The anomalous statics arise at high motor densities and take the form
of end-bound localized filament bundles for rapid motors, and extended clusters
exhibiting enhanced small-wavenumber density fluctuations and power-law
cluster-size distributions for slow, processive motors. Anomalous dynamics
arise for slow, processive motors over a range of motor densities, and are most
evident as superdiffusive mass transport, which we argue is the consequence of
a form of effective self-propulsion resulting from the polar coupling between
motors and filaments.Comment: 14 pages, 17 figures. Minor clarifications and updated/additional
references. To appear in Soft Matte
Health Figures: An Open Source JavaScript Library for Health Data Visualization
The way we look at data has a great impact on how we can understand it,
particularly when the data is related to health and wellness. Due to the
increased use of self-tracking devices and the ongoing shift towards preventive
medicine, better understanding of our health data is an important part of
improving the general welfare of the citizens. Electronic Health Records,
self-tracking devices and mobile applications provide a rich variety of data
but it often becomes difficult to understand. We implemented the hFigures
library inspired on the hGraph visualization with additional improvements. The
purpose of the library is to provide a visual representation of the evolution
of health measurements in a complete and useful manner. We researched the
usefulness and usability of the library by building an application for health
data visualization in a health coaching program. We performed a user evaluation
with Heuristic Evaluation, Controlled User Testing and Usability
Questionnaires. In the Heuristics Evaluation the average response was 6.3 out
of 7 points and the Cognitive Walkthrough done by usability experts indicated
no design or mismatch errors. In the CSUQ usability test the system obtained an
average score of 6.13 out of 7, and in the ASQ usability test the overall
satisfaction score was 6.64 out of 7. We developed hFigures, an open source
library for visualizing a complete, accurate and normalized graphical
representation of health data. The idea is based on the concept of the hGraph
but it provides additional key features, including a comparison of multiple
health measurements over time. We conducted a usability evaluation of the
library as a key component of an application for health and wellness
monitoring. The results indicate that the data visualization library was
helpful in assisting users in understanding health data and its evolution over
time.Comment: BMC Medical Informatics and Decision Making 16.1 (2016
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