76 research outputs found
Magnetic phase diagram in three-dimensional triangular-lattice antiferromagnet SrCoTaO with small easy-axis anisotropy
We report the results of low-temperature magnetization and specific heat
measurements of SrCoTaO powder, in which Co ions with
effective spin-1/2 form a uniform triangular lattice in the plane. It was
found that SrCoTaO undergoes successive antiferromagnetic
transitions at and at zero magnetic field. As the magnetic field increases, both
and decrease monotonically. The obtained magnetic field vs
temperature phase diagram together with a sharp magnetization anomaly at a
saturation field of indicates that
SrCoTaO is described as a spin-1/2 three-dimensional
triangular-lattice antiferromagnet with a weak easy-axis anisotropy. We discuss
the characteristics of the magnetic phase diagram, which approximates the phase
diagram for the magnetic field perpendicular to the axis.Comment: 12 pages, 11 figures, accepted for publication in Phys. Rev.
Investigating accuracy of pitch-accent annotations in neural network-based speech synthesis and denoising effects
We investigated the impact of noisy linguistic features on the performance of
a Japanese speech synthesis system based on neural network that uses WaveNet
vocoder. We compared an ideal system that uses manually corrected linguistic
features including phoneme and prosodic information in training and test sets
against a few other systems that use corrupted linguistic features. Both
subjective and objective results demonstrate that corrupted linguistic
features, especially those in the test set, affected the ideal system's
performance significantly in a statistical sense due to a mismatched condition
between the training and test sets. Interestingly, while an utterance-level
Turing test showed that listeners had a difficult time differentiating
synthetic speech from natural speech, it further indicated that adding noise to
the linguistic features in the training set can partially reduce the effect of
the mismatch, regularize the model, and help the system perform better when
linguistic features of the test set are noisy.Comment: Accepted for Interspeech 201
フォルマントの高精度推定に基づく高品質かつ柔軟な音声合成
University of Tokyo (東京大学
Training Multi-Speaker Neural Text-to-Speech Systems using Speaker-Imbalanced Speech Corpora
When the available data of a target speaker is insufficient to train a high
quality speaker-dependent neural text-to-speech (TTS) system, we can combine
data from multiple speakers and train a multi-speaker TTS model instead. Many
studies have shown that neural multi-speaker TTS model trained with a small
amount data from multiple speakers combined can generate synthetic speech with
better quality and stability than a speaker-dependent one. However when the
amount of data from each speaker is highly unbalanced, the best approach to
make use of the excessive data remains unknown. Our experiments showed that
simply combining all available data from every speaker to train a multi-speaker
model produces better than or at least similar performance to its
speaker-dependent counterpart. Moreover by using an ensemble multi-speaker
model, in which each subsystem is trained on a subset of available data, we can
further improve the quality of the synthetic speech especially for
underrepresented speakers whose training data is limited.Comment: Submitted to Interspeech 2019, Graz, Austri
The Japanese space gravitational wave antenna; DECIGO
DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future
Japanese space gravitational wave antenna. DECIGO is expected to open a new window of
observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing
various mysteries of the universe such as dark energy, formation mechanism of supermassive
black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of
three drag-free spacecraft, whose relative displacements are measured by a differential Fabry–
Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre-
DECIGO first and finally DECIGO in 2024
DECIGO pathfinder
DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected to provide us fruitful insights into the universe, in particular about dark energy, a formation mechanism of supermassive black holes, and the inflation of the universe. Since DECIGO will be an extremely large mission which will formed by three drag-free spacecraft with 1000m separation, it is significant to gain the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. The conceptual design and current status of the first milestone mission, DPF, are reviewed in this article
Identification of novel SNPs of ABCD1, ABCD2, ABCD3, and ABCD4 genes in patients with X-linked adrenoleukodystrophy (ALD) based on comprehensive resequencing and association studies with ALD phenotypes
Adrenoleukodystrophy (ALD) is an X-linked disorder affecting primarily the white matter of the central nervous system occasionally accompanied by adrenal insufficiency. Despite the discovery of the causative gene, ABCD1, no clear genotype–phenotype correlations have been established. Association studies based on single nucleotide polymorphisms (SNPs) identified by comprehensive resequencing of genes related to ABCD1 may reveal genes modifying ALD phenotypes. We analyzed 40 Japanese patients with ALD. ABCD1 and ABCD2 were analyzed using a newly developed microarray-based resequencing system. ABCD3 and ABCD4 were analyzed by direct nucleotide sequence analysis. Replication studies were conducted on an independent French ALD cohort with extreme phenotypes. All the mutations of ABCD1 were identified, and there was no correlation between the genotypes and phenotypes of ALD. SNPs identified by the comprehensive resequencing of ABCD2, ABCD3, and ABCD4 were used for association studies. There were no significant associations between these SNPs and ALD phenotypes, except for the five SNPs of ABCD4, which are in complete disequilibrium in the Japanese population. These five SNPs were significantly less frequently represented in patients with adrenomyeloneuropathy (AMN) than in controls in the Japanese population (p = 0.0468), whereas there were no significant differences in patients with childhood cerebral ALD (CCALD). The replication study employing these five SNPs on an independent French ALD cohort, however, showed no significant associations with CCALD or pure AMN. This study showed that ABCD2, ABCD3, and ABCD4 are less likely the disease-modifying genes, necessitating further studies to identify genes modifying ALD phenotypes
Current status of space gravitational wave antenna DECIGO and B-DECIGO
Deci-hertz Interferometer Gravitational Wave Observatory (DECIGO) is the
future Japanese space mission with a frequency band of 0.1 Hz to 10 Hz. DECIGO
aims at the detection of primordial gravitational waves, which could be
produced during the inflationary period right after the birth of the universe.
There are many other scientific objectives of DECIGO, including the direct
measurement of the acceleration of the expansion of the universe, and reliable
and accurate predictions of the timing and locations of neutron star/black hole
binary coalescences. DECIGO consists of four clusters of observatories placed
in the heliocentric orbit. Each cluster consists of three spacecraft, which
form three Fabry-Perot Michelson interferometers with an arm length of 1,000
km. Three clusters of DECIGO will be placed far from each other, and the fourth
cluster will be placed in the same position as one of the three clusters to
obtain the correlation signals for the detection of the primordial
gravitational waves. We plan to launch B-DECIGO, which is a scientific
pathfinder of DECIGO, before DECIGO in the 2030s to demonstrate the
technologies required for DECIGO, as well as to obtain fruitful scientific
results to further expand the multi-messenger astronomy.Comment: 10 pages, 3 figure
Recent Results from LHD Experiment with Emphasis on Relation to Theory from Experimentalist’s View
he Large Helical Device (LHD) has been extending an operational regime of net-current free plasmas towardsthe fusion relevant condition with taking advantage of a net current-free heliotron concept and employing a superconducting coil system. Heating capability has exceeded 10 MW and the central ion and electron temperatureshave reached 7 and 10 keV, respectively. The maximum value of β and pulse length have been extended to 3.2% and 150 s, respectively. Many encouraging physical findings have been obtained. Topics from recent experiments, which should be emphasized from the aspect of theoretical approaches, are reviewed. Those are (1) Prominent features in the inward shifted configuration, i.e., mitigation of an ideal interchange mode in the configuration with magnetic hill, and confinement improvement due to suppression of both anomalous and neoclassical transport, (2) Demonstration ofbifurcation of radial electric field and associated formation of an internal transport barrier, and (3) Dynamics of magnetic islands and clarification of the role of separatrix
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