1,060 research outputs found
Statistical Mechanics of Low-Density Parity Check Error-Correcting Codes over Galois Fields
A variation of low density parity check (LDPC) error correcting codes defined
over Galois fields () is investigated using statistical physics. A code
of this type is characterised by a sparse random parity check matrix composed
of nonzero elements per column. We examine the dependence of the code
performance on the value of , for finite and infinite values, both in
terms of the thermodynamical transition point and the practical decoding phase
characterised by the existence of a unique (ferromagnetic) solution. We find
different -dependencies in the cases of C=2 and ; the analytical
solutions are in agreement with simulation results, providing a quantitative
measure to the improvement in performance obtained using non-binary alphabets.Comment: 7 pages, 1 figur
A solution for secure use of Kibana and Elasticsearch in multi-user environment
Monitoring is indispensable to check status, activities, or resource usage of
IT services. A combination of Kibana and Elasticsearch is used for monitoring
in many places such as KEK, CC-IN2P3, CERN, and also non-HEP communities.
Kibana provides a web interface for rich visualization, and Elasticsearch is a
scalable distributed search engine. However, these tools do not support
authentication and authorization features by default. In the case of single
Kibana and Elasticsearch services shared among many users, any user who can
access Kibana can retrieve other's information from Elasticsearch. In
multi-user environment, in order to protect own data from others or share part
of data among a group, fine-grained access control is necessary.
The CERN cloud service group had provided cloud utilization dashboard to each
user by Elasticsearch and Kibana. They had deployed a homemade Elasticsearch
plugin to restrict data access based on a user authenticated by the CERN Single
Sign On system. It enabled each user to have a separated Kibana dashboard for
cloud usage, and the user could not access to other's one. Based on the
solution, we propose an alternative one which enables user/group based
Elasticsearch access control and Kibana objects separation. It is more flexible
and can be applied to not only the cloud service but also the other various
situations. We confirmed our solution works fine in CC-IN2P3. Moreover, a
pre-production platform for CC-IN2P3 has been under construction.
We will describe our solution for the secure use of Kibana and Elasticsearch
including integration of Kerberos authentication, development of a Kibana
plugin which allows Kibana objects to be separated based on user/group, and
contribution to Search Guard which is an Elasticsearch plugin enabling
user/group based access control. We will also describe the effect on
performance from using Search Guard.Comment: International Symposium on Grids and Clouds 2017 (ISGC 2017
Identifying Subclasses of Long Gamma-Ray Bursts with Cumulative Light Curve Morphology of Prompt Emissions
We argue a new classification scheme of long gamma-ray bursts (LGRBs) using
the morphology of the cumulative light curve of the prompt emission. We
parametrize the morphology by the absolute deviation from their constant
luminosity () and derive the value for 36 LGRBs which have spectropic
redshifts, spectral parameters determined by the Band model, 1-second peak
fluxes, fluences, and 64-msec resolution light curves whose peak counts are 10
times larger than background fluctuations. Then we devide the sample according
to the value of ADCL into two groups () and, for
each group, derive the spectral peak energy - peak luminosity
correlation and the Fundamental Plane of LGRBs, which is a
correlation between the spectral peak energy , the luminosity time
( where is isotropic
energy) and the peak luminosity . We find that both of the
correlations for both groups are statistically more significant compared with
ones derived from all samples. The Fundamental Planes with small and large ADCL
are given by with
and with , respectively. This fact implies the
existence of subclasses of LGRBs characterized by the value of . Also
there is a hint for the existence of the intermediate- class which
deviates from both fundamental planes. Both relations are so tight that our
result provides a new accurate distance measurement scheme up to the high
redshift universe.Comment: 10 pages, 8 figures, 2 tables. Submitted to PAS
Dispersal of Phraortes illepidus (Phasmida: Phasmatidae) Eggs by Workers of the Queenless Ant, Pristomyrmex punctatus (Hymenoptera: Formicidae)
Eggs of some stick insects bear external appendages called capitula. Foraging worker ants attracted by capitula disperse eggs in a response similar to the responses of workers to elaiosome-bearing seeds of many plants. For this study, we conducted rearing experiments in the laboratory to elucidate the interspecific relation between the queenless ant, Pristomyrmex punctatus Smith, and the stick insect, Phraortes illepidus (Brunner von Wattenwyl) of which eggs bear capitula. Eggs of P. illepidus were proposed to P. punctatus in the laboratory. Capitula were removed from most of the eggs not only when ants were starved but also when ants were well-fed. In large rearing containers, eggs were transported by ants from their place of origin. Many eggs were transferred horizontally on the surface. Although some eggs were found in the artificial ant nests, it is likely that stick insects are not in active ant nests at the time of hatching in nature because of P. punctatus nest-moving habits. The percentage of eggs buried in the sand was small. Furthermore, most of the buried eggs were found at less than 3 cm depth. Results show that many P. illepidus hatchlings can reach host plants safely without being attacked by ant workers. These results suggest that P. punctatus can be a good partner of P. illepidus. Ants disperse eggs of slow-moving stink insects in exchange for some nutrition from capitula
Use of Wavelet Techniques in the Study of Seawater Flux Dynamics in Coastal Lakes
Lakes Shinji and Nakaumi form a coupled brackish lake system on the Japan Sea coast of Japan, and seawater frequently intrudes into these lakes. The study analyzed the influence of river discharge, tide level, and meteorological forcing on seawater flux at Nakaura Watergate. Continuous wavelet transform (CWT), wavelet coherence (WTC), cross-wavelet transform (XWT), and partial wavelet coherence (PWC) were used to analyze seawater intrusion. CWT reveals the characteristics of seawater flux, river discharge, tide level, and meteorological forcing. WTC and XWT showed the correlation between forcing variables and seawater flux. PWC analyzed the impact of river discharge, tide level, and meteorological forcing variables on seawater flux after controlling the effect of all other forcing variables. The results showed that tide level has an impact on seawater flux over 0.5-day and 1-day cycle throughout the analysis period, suggesting that astronomical tides play an important role in the salinity intrusion processes. The river discharge characteristics and its influence on seawater flux were clearly revealed especially during high river flows. Sometimes, atmospheric pressure and wind velocity affect tide level, thereby driving salinity transport. The study reveals the power of wavelet analysis in examining nonlinear time series such as salinity intrusion processes
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