Current-feedback-stabilized laser system for quantum simulation experiments using Yb clock transition at 578 nm

We developed a laser system for the spectroscopy of the clock transition in ytterbium (Yb) atoms at 578 nm based on an interference-filter stabilized external-cavity diode laser (IFDL) emitting at 1156 nm. Owing to the improved frequency-to-current response of the laser-diode chip and the less sensitivity of the IFDL to mechanical perturbations, we succeeded in stabilizing the frequency to a high-finesse ultra-low-expansion glass cavity with a simple current feedback system. Using this laser system, we performed high-resolution clock spectroscopy of Yb and found that the linewidth of the stabilized laser was less than 320 Hz.Comment: 5 pages, 7 figure

Reducing Resonant Vibration of a Rotor by Tuning the Gap between a Superconducting Bulk and a Permanent Magnet

AbstractThis study investigated passing through a critical speed of a rotor supported by a superconductor with an electromagnet. Here we adopted the idea that the gap between the superconductor and the rotor can be tuned variably by using electromagnetic force of the electromagnet so that the natural frequency or the stiffness can be changed. By using this method, it can be expected that resonant vibration be reduced. We developed an analytical model and then carried out numerical simulation. Numerical results show that considerable reduction of the resonant amplitude can be achieved by proper tuning of switching the electromagnet

Fusion cross section and total kinetic energy of fission fragments by the dynamical dissipative surface-friction model

The capture cross section, the fusion cross section, and the quasi-fission yield producing symmetric fragments ($A_{CN}/2\pm20u$) in the $^{48}$Ca+$^{238}$U reaction are analyzed by the multidimensional Langevin equation taking account of the surface friction effect. From the experimental data, the strength of the tangential friction has been determined. It is presented that tangential friction increases in proportional to the power of the relative velocity of the projectile and the target.Comment: 12 pages, 8 figure

Are both agricultural intensification and farmland abandonment threats to biodiversity? A test with bird communities in paddy-dominated landscapes

Land-use changes, including agricultural intensification and farmland abandonment, influence biodiversity in agricultural landscapes. However, few studies have focused on how the two major land-use changes affect different types of species at landscape scales. This study examined the relationships between the richness and abundance of five bird groups (agricultural wetland species, agricultural land species, grassland species, edge species, and woodland species) as well as the total species richness and abundance, and intensification or abandonment in 28 square, 100-ha grid cells in paddy-dominated landscapes in the Tone River basin of central Japan. Rice-field intensification and abandonment were not completely segregated spatially: intensification occurred in both plain and hilly areas surrounded by forests, while abandonment tended to occur in hilly areas. The effects of intensification and abandonment differed among species groups and between seasons. The richness or abundance of agricultural wetland species in summer were negatively associated with both intensification and abandonment. While the abundance of agricultural land species in winter and grassland species in both seasons were positively associated with intensification and abandonment, respectively. The total species richness and abundance did not show clear association with intensification and abandonment due to a variety of responses of the five bird groups. Based on prefectural Red Data Books, agricultural wetland species, followed by grassland species, were more threatened than other three groups in both summer and winter. This study found that (1) the diversity of habitats (including consolidated and abandoned farmlands) provides buffer areas for the different bird groups on different times of the year and (2) agricultural wetland species that use flooded rice fields in summer, such as egrets and shorebirds, are particularly threatened by both intensification and abandonment.We thank Yoshinori Tokuoka, Susumu Yamada, Eun-Young Kim, and Shori Yamamoto for providing land-use data. We also appreciate two anonymous reviewers for their constructive comments and suggestions. This study was conducted as part of the research project “Developing management techniques for agricultural and aquatic ecosystems in river basins in pursuit of coexistence with nature,” funded by the Agriculture, Forestry and Fisheries Research Council of Japan. N.K. and T.O. were also financially supported by JSPS (Japan Society for the Promotion of Science) KAKENHI Grant Numbers 25830154 and 24710038, respectively. T.A. was supported by the European Commission’s Marie Curie International Incoming Fellowship Programme (PIIFGA-2011-303221).This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.agee.2015.08.01

VEGF(164)-mediated inflammation is required for pathological, but not physiological, ischemia-induced retinal neovascularization

Hypoxia-induced VEGF governs both physiological retinal vascular development and pathological retinal neovascularization. In the current paper, the mechanisms of physiological and pathological neovascularization are compared and contrasted. During pathological neovascularization, both the absolute and relative expression levels for VEGF(164) increased to a greater degree than during physiological neovascularization. Furthermore, extensive leukocyte adhesion was observed at the leading edge of pathological, but not physiological, neovascularization. When a VEGF(164)-specific neutralizing aptamer was administered, it potently suppressed the leukocyte adhesion and pathological neovascularization, whereas it had little or no effect on physiological neovascularization. In parallel experiments, genetically altered VEGF(164)-deficient (VEGF(120/188)) mice exhibited no difference in physiological neovascularization when compared with wild-type (VEGF(+/+)) controls. In contrast, administration of a VEGFk-1/Fc fusion protein, which blocks all VEGF isoforms, led to significant suppression of both pathological and physiological neovascularization. In addition, the targeted inactivation of monocyte lineage cells with clodronate-liposomes led to the suppression of pathological neovascularization. Conversely, the blockade of T lymphocyte-mediated immune responses with an anti-CD2 antibody exacerbated pathological neovascularization. These data highlight important molecular and cellular differences between physiological and pathological retinal neovascularization. During pathological neovascularization, VEGF(164) selectively induces inflammation and cellular immunity. These processes provide positive and negative angiogenic regulation, respectively. Together, new therapeutic approaches for selectively targeting pathological, but not physiological, retinal neovascularization are outlined

Relativistic Electron Shock Drift Acceleration in Low Mach Number Galaxy Cluster Shocks

An extreme case of electron shock drift acceleration in low Mach number collisionless shocks is investigated as a plausible mechanism of initial acceleration of relativistic electrons in large-scale shocks in galaxy clusters where upstream plasma temperature is of the order of 10 keV and a degree of magnetization is not too small. One-dimensional electromagnetic full particle simulations reveal that, even though a shock is rather moderate, a part of thermal incoming electrons are accelerated and reflected through relativistic shock drift acceleration and form a local nonthermal population just upstream of the shock. The accelerated electrons can self-generate local coherent waves and further be back-scattered toward the shock by those waves. This may be a scenario for the first stage of the electron shock acceleration occurring at the large-scale shocks in galaxy clusters such as CIZA J2242.8+5301 which has well defined radio relics.Comment: 26 pages, 10 figures, accepted for publication in Ap