224 research outputs found
Complex Correlation Approach for High Frequency Financial Data
We propose a novel approach that allows to calculate Hilbert transform based
complex correlation for unevenly spaced data. This method is especially
suitable for high frequency trading data, which are of a particular interest in
finance. Its most important feature is the ability to take into account
lead-lag relations on different scales, without knowing them in advance. We
also present results obtained with this approach while working on Tokyo Stock
Exchange intraday quotations. We show that individual sectors and subsectors
tend to form important market components which may follow each other with small
but significant delays. These components may be recognized by analysing
eigenvectors of complex correlation matrix for Nikkei 225 stocks.
Interestingly, sectorial components are also found in eigenvectors
corresponding to the bulk eigenvalues, traditionally treated as noise
Structure and temporal change of the credit network between banks and large firms in Japan
We present a new approach to understanding credit relationships between
commercial banks and quoted firms, and with this approach, examine the temporal
change in the structure of the Japanese credit network from 1980 to 2005. At
each year, the credit network is regarded as a weighted bipartite graph where
edges correspond to the relationships and weights refer to the amounts of
loans. Reduction in the supply of credit affects firms as debtor, and failure
of a firm influences banks as creditor. To quantify the dependency and
influence between banks and firms, we propose a set of scores of banks and
firms, which can be calculated by solving an eigenvalue problem determined by
the weight of the credit network. We found that a few largest eigenvalues and
corresponding eigenvectors are significant by using a null hypothesis of random
bipartite graphs, and that the scores can quantitatively describe the stability
or fragility of the credit network during the 25 years
Stellar Initial Mass Function (IMF) Probed with Supernova Rates and Neutrino Background: Cosmic Average IMF Slope is Similar to the Salpeter IMF
The stellar initial mass function (IMF) is expressed by with the slope , and known as the poorly-constrained but
very important function in studies of star and galaxy formation. There are no
sensible observational constraints on the IMF slopes beyond Milky Way and
nearby galaxies. Here we combine two sets of observational results, 1) cosmic
densities of core-collapse supernova explosion (CCSNe) rates and 2) cosmic far
ultraviolet radiation (and infrared re-radiation) densities, which are
sensitive to massive () and moderately massive
() stars, respectively, and constrain the IMF
slope at with a freedom of redshift evolution. Although no
redshift evolution is identified beyond the uncertainties, we find that the
cosmic average IMF slope at is at the 95 % confidence
level that is comparable with the Salpeter IMF, , which marks the
first constraint on the cosmic average IMF. We show a forecast for the Nancy
Grace Roman Space Telescope supernova survey that will provide significantly
strong constraints on the IMF slope with over
. Moreover, as for an independent IMF probe instead of 1), we suggest to
use diffuse supernovae neutrino background (DSNB), relic neutrinos from CCSNe.
We expect that the Hyper-Kamiokande neutrino observations over 20 years will
improve the constraints on the IMF slope and the redshift evolution
significantly better than those obtained today, if the systematic uncertainties
of DSNB production physics are reduced in the future numerical simulations.Comment: 7 pages, 6 figures, ApJ in pres
JARE Syowa Station 11-m Antenna, Antarctica
In 2012, the 52nd and the 53rd Japanese Antarctic Research Expeditions (hereinafter, referred to as JARE-52 and JARE-53, respectively) participated in five OHIG sessions - OHIG76, 78, 79, 80, and 81. These data were recorded on hard disks through the K5 terminal. Only the hard disks for the OHIG76 session have been brought back from Syowa Station to Japan, in April 2012, by the icebreaker, Shirase, while those of the other four sessions are scheduled to arrive in April 2013. The data obtained from the OHIG73, 74, 75, and 76 sessions by JARE-52 and JARE-53 have been transferred to the Bonn Correlator via the servers of National Institute of Information and Communications Technology (NICT). At Syowa Station, JARE-53 and JARE-54 will participate in six OHIG sessions in 2013
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