Scalable Spin Amplification with a Gain over a Hundred

We propose a scalable and practical implementation of spin amplification which does not require individual addressing nor a specially tailored spin network. We have demonstrated a gain of 140 in a solid-state nuclear spin system of which the spin polarization has been increased to 0.12 using dynamic nuclear polarization with photoexcited triplet electron spins. Spin amplification scalable to a higher gain opens the door to the single spin measurement for a readout of quantum computers as well as practical applications of nuclear magnetic resonance (NMR) spectroscopy to infinitesimal samples which have been concealed by thermal noise.Comment: 6 pages, 7 figure

H2-decoupling-accelerated H1 spin diffusion in dynamic nuclear polarization with photoexcited triplet electrons

In dynamic nuclear polarization (DNP) experiments applied to organic solids for creating nonequilibrium, high H1 spin polarization, an efficient buildup of H1 polarization is attained by partially deuterating the material of interest with an appropriate H1 concentration. In such a dilute H1 spin system, it is shown that the H1 spin diffusion rate and thereby the buildup efficiency of H1 polarization can further be enhanced by continually applying radiofrequency irradiation for deuterium decoupling during the DNP process. As experimentally confirmed in this work, the electron spin polarization of the photoexcited triplet state is mainly transferred only to those H1 spins, which are in the vicinity of the electron spins, and H1 spin diffusion transports the localized H1 polarization over the whole sample volume. The H1 spin diffusion coefficients are estimated from DNP repetition interval dependence of the initial buildup rate of H1 polarization, and the result indicates that the spin diffusion coefficient is enhanced by a factor of 2 compared to that without H2 decoupling.This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in M. Negoro, K. Nakayama, K. Tateishi, A. Kagawa, K. Takeda, and M. Kitagawa, J. Chem. Phys. 133, 154504 (2010) and may be found at https://doi.org/10.1063/1.3493453

Shimanto geosyncline and Kuroshio paleoland

The late Mesozoic to early Neogene geosyncline in the Outer zone of Southwest Japan has been studied in detail in the Kii Peninsula by the Research Group for the Shimanto Geosyncline. The existence of the Kuroshio Paleoland to the south of the geosyncline was inferred by various sedimentologic evidences. The Shimanto belt in the Kii Peninsula is divided from north to south into three zones of Cretaceous, Eocene and Oligocene to lower Miocene. In these belts thick geosynclinal sediments were accumulated showing coarsening upward. The southward migration of the basin occurred in Cretaceous/Eocene, Eocene/Oligocene, and in early Miocene. In the present paper the reconstruction of paleogeography of the Shimanto geosyncline was attempted and the Kuroshio Paleoland was discussed in relation to the geohistory of the Philippine Sea. In spite of the detailed geologic survey in the Kii Peninsula there is no evidence of large exotic blocks nor tectonic mélanges, and this does not support the plate tectonic model ofthe Pacific-type orogeny for the Shimanto belt.ArticleJournal of Physics of the Earth. 26(suppl):357-366 (1978)journal articl

Interplay between particle trapping and heterogeneity in anomalous diffusion

Heterogeneous media diffusion is often described using position-dependent diffusion coefficients and estimated indirectly through mean squared displacement in experiments. This approach may overlook other mechanisms and their interaction with position-dependent diffusion, potentially leading to erroneous conclusions. Here, we introduce a hybrid diffusion model that merges a position-dependent diffusion coefficient with the trapping mechanism of the comb model. We derive exact solutions for position distributions and mean squared displacements, validated through simulations of Langevin equations. Our model shows that the trapping mechanism attenuates the impact of media heterogeneity. Superdiffusion occurs when the position-dependent coefficient increases superlinearly, while subdiffusion occurs for sublinear and inverse power-law relations. This nontrivial interplay between heterogeneity and state-independent mechanisms also leads to anomalous yet Brownian and non-Brownian yet Gaussian regimes. These findings emphasize the need for cautious interpretations of experiments and highlight the limitations of relying solely on mean squared displacements or position distributions for diffusion characterization.Comment: 13 two-column pages, 6 figures; accepted for publication in Communications Physic

Histone Demethylase JHDM2A Is Involved in Male Infertility and Obesity

Recent studies indicate that histone lysine methylation is subject to enzyme-catalyzed reversion, and jumonji C (JmjC) domain–containing proteins have been identified as one of the members of histone demethylases. Although an increasing number of histone demethylases have been identified and biochemically characterized, their biological functions are poorly characterized. To elucidate the physiological functions, we generated the knockout mouse model of dimethylated or monomethylated histone 3 lysine 9 (H3K9me2/1)–specific JmjC domain–containing histone demethylase 2A (JHDM2A; also known as JMJD1A and KDM3A) and showed that JHDM2A is essential for spermatogenesis. Jhdm2a-deficient mice exhibited impaired postmeiotic chromatin condensation, which caused infertility, even though the hormonal levels were maintained. Further molecular and biochemical analysis revealed that JHDM2A directly bound to the core promoter regions of transition nuclear protein 1 (Tnp1) and protamine 1 (Prm1) genes, and it induced the transcriptional activation of these genes by removing H3K9 methylation, which is known as a silencing marker of gene transcription. This work uncovered a role for JHDM2A in spermatogenesis and identified 2 downstream genes that are critical for sperm nuclear condensation. In addition, we also showed that JHDM2A plays a role in regulating fat metabolic gene expression in muscle and brown fat tissue, and the knockout mice exhibited obesity and hyperlipidemia. Thus, JHDM2A possesses organ/tissue-specific target genes, and impairment of this molecule cannot be compensated by other JmjC-containing histone demethylases, suggesting the importance of this molecule in vivo

Universal patterns in sound amplitudes of songs and music genres

We report a statistical analysis over more than eight thousand songs. Specifically, we investigate the probability distribution of the normalized sound amplitudes. Our findings seems to suggest a universal form of distribution which presents a good agreement with a one-parameter stretched Gaussian. We also argue that this parameter can give information on music complexity, and consequently it goes towards classifying songs as well as music genres. Additionally, we present statistical evidences that correlation aspects of the songs are directly related with the non-Gaussian nature of their sound amplitude distributions.Comment: Accepted for publication as a Brief Report in Physical Review