U(1) symmetry breaking in one-dimensional Mott insulator studied by the Density Matrix Renormalization Group method

A new type of external fields violating the particle number preservation is studied in one-dimensional strongly correlated systems by the Density Matrix Renormalization Group method. Due to the U(1) symmetry breaking, the ground state has fluctuation of the total particle number, which implies injection of electrons and holes from out of the chain. This charge fluctuation can be relevant even at half-filling because the particle-hole symmetry is preserved with the finite effective field. In addition, we discuss a quantum phase transition obtained by considering the symmetry-breaking fields as a mean field of interchain-hopping.Comment: 7 pages, 4 figure

Measurements of Stellar Inclinations for Kepler Planet Candidates II: Candidate Spin-Orbit Misalignments in Single and Multiple-Transiting Systems

We present a test for spin-orbit alignment for the host stars of 25 candidate planetary systems detected by the {\it Kepler} spacecraft. The inclination angle of each star's rotation axis was estimated from its rotation period, rotational line broadening, and radius. The rotation periods were determined using the {\it Kepler} photometric time series. The rotational line broadening was determined from high-resolution optical spectra with Subaru/HDS. Those same spectra were used to determine the star's photospheric parameters (effective temperature, surface gravity, metallicity) which were then interpreted with stellar-evolutionary models to determine stellar radii. We combine the new sample with the 7 stars from our previous work on this subject, finding that the stars show a statistical tendency to have inclinations near 90$^\circ$, in alignment with the planetary orbits. Possible spin-orbit misalignments are seen in several systems, including three multiple-planet systems (KOI-304, 988, 2261). Ideally these systems should be scrutinized with complementary techniques---such as the Rossiter-McLaughlin effect, starspot-crossing anomalies or asteroseismology---but the measurements will be difficult owing to the relatively faint apparent magnitudes and small transit signals in these systems.Comment: 11 pages, 9 figures, accepted for publication in Ap

Josephson pi-state in a ferromagnetic insulator

We predict anomalous atomic-scale 0-pi transitions in a Josephson junction with a ferromagnetic-insulator (FI) barrier. The ground state of such junction alternates between 0- and pi-states when thickness of FI is increasing by a single atomic layer. We find that the mechanism of the 0-pi transition can be attributed to thickness-dependent phase-shifts between the wave numbers of electrons and holes in FI. Based on these results, we show that stable pi-state can be realized in junctions based on high-Tc superconductors with La$_2$BaCuO$_5$ barrier.Comment: 4 pages, 3 figures, Phys. Rev. Lett. (2010) in pres

Numerical study of pi-junction using spin filtering barriers

We numerically investigate the Josephson transport through ferromagnetic insulators (FIs) by taking into account its band structure. By use of the recursive Green's function method, we found the formation of the pi junction in the case of the fully spin-polarized FI (FPFI), e.g., La$_2$BaCuO$_5$. Moreover, the 0-pi transition is induced by increasing the thickness of FPFI. On the other hand, Josephson current through the Eu chalcogenides shows the pi junction behavior in the case of the strong d-f hybridization between the conduction d and the localized f electrons of Eu. Such FI-based Josephson junctions may become a element in the architecture of future quantum information devices.Comment: 9 pages, 5 figure

Nonequilibrium Kondo Effect in a Quantum Dot Coupled to Ferromagnetic Leads

We study the Kondo effect in the electron transport through a quantum dot coupled to ferromagnetic leads, using a real-time diagrammatic technique which provides a systematic description of the nonequilibrium dynamics of a system with strong local electron correlations. We evaluate the theory in an extension of the `resonant tunneling approximation', introduced earlier, by introducing the self-energy of the off-diagonal component of the reduced propagator in spin space. In this way we develop a charge and spin conserving approximation that accounts not only for Kondo correlations but also for the spin splitting and spin accumulation out of equilibrium. We show that the Kondo resonances, split by the applied bias voltage, may be spin polarized. A left-right asymmetry in the coupling strength and/or spin polarization of the electrodes significantly affects both the spin accumulation and the weight of the split Kondo resonances out of equilibrium. The effects are observable in the nonlinear differential conductance. We also discuss the influence of decoherence on the Kondo resonance in the frame of the real-time formulation.Comment: 13 pages, 13 figure

AnkyrinG is required for maintenance of the axon initial segment and neuronal polarity

The axon initial segment (AIS) functions as both a physiological and physical bridge between somatodendritic and axonal domains. Given its unique molecular composition, location, and physiology, the AIS is thought to maintain neuronal polarity. To identify the molecular basis of this AIS property, we used adenovirus-mediated RNA interference to silence AIS protein expression in polarized neurons. Some AIS proteins are remarkably stable with half-lives of at least 2 wk. However, silencing the expression of the cytoskeletal scaffold ankyrinG (ankG) dismantles the AIS and causes axons to acquire the molecular characteristics of dendrites. Both cytoplasmic- and membrane-associated proteins, which are normally restricted to somatodendritic domains, redistribute into the former axon. Furthermore, spines and postsynaptic densities of excitatory synapses assemble on former axons. Our results demonstrate that the loss of ankG causes axons to acquire the molecular characteristics of dendrites; thus, ankG is required for the maintenance of neuronal polarity and molecular organization of the AIS

Rescue with an anti-inflammatory peptide of chickens infected H5N1 avian flu

Chickens suffering from avian flu caused by H5N1 influenza virus are destined to die within 2 days due to a systemic inflammatory response. Since HVJ infection (1,2) and influenza virus infection (3,4) cause infected cells to activate homologous serum complement, the systemic inflammatory response elicited could be attributed to the unlimited generation of C5a anaphylatoxin of the complement system, which is a causative peptide of serious inflammation. In monkeys inoculated with a lethal dose of LPS (4 mg/kg body weight), inhibition of C5a by an inhibitory peptide termed AcPepA (5) rescued these animals from serious septic shock which would have resulted in death within a day (6). Therefore, we tested whether AcPepA could also have a beneficial effect on chickens with bird flu. On another front, enhanced production of endothelin-1 (ET-1) and the activation of mast cells (MCs) have been implicated in granulocyte sequestration (7). An endothelin receptor derived antisense homology box peptide (8) designated ETR-P1/fl was shown to antagonize endothelin A receptor (ET-A receptor) (9) and reduce such inflammatory responses as endotoxin-shock (10) and hemorrhagic shock (11), thereby suppressing histamine release in the circulation (12). Thus, we also administered ETR-P1/fl to bird flu chickens expecting suppression of a systemic inflammatory response

Measurement of the Rossiter--McLaughlin Effect in the Transiting Exoplanetary System TrES-1

We report a measurement of the Rossiter--McLaughlin effect in the transiting extrasolar planetary system TrES-1, via simultaneous spectroscopic and photometric observations with the Subaru and MAGNUM telescopes. By modeling the radial velocity anomaly that was observed during a transit, we determine the sky-projected angle between the stellar spin axis and the planetary orbital axis to be $\lambda = 30 \pm 21$ [deg]. This is the third case for which $\lambda$ has been measured in a transiting exoplanetary system, and the first demonstration that such measurements are possible for relatively faint host stars ($V \sim 12$, as compared to $V \sim 8$ for the other systems). We also derive a time of mid-transit, constraints on the eccentricity of the TrES-1b orbit ($e = 0.048 \pm 0.025$), and upper limits on the mass of the Trojan companions ($\lesssim$14 $M_{\oplus}$) at the 3$\sigma$ level.Comment: 8 pages, 5 figures, 2 tables. Published in PASJ. Corrected typo

Large-scale Filamentary Structure around the Protocluster at Redshift z=3.1

We report the discovery of a large-scale coherent filamentary structure of Lyman alpha emitters in a redshift space at z=3.1. We carried out spectroscopic observations to map the three dimensional structure of the belt-like feature of the Lyman alpha emitters discovered by our previous narrow-band imaging observations centered on the protocluster at z=3.1. The feature was found to consist of at least three physical filaments connecting with each other. The result is in qualitative agreement with the prediction of the 'biased' galaxy-formation theories that galaxies preferentially formed in large-scale filamentary or sheet-like mass overdensities in the early Universe. We also found that the two known giant Lyman alpha emission-line nebulae showing high star-formation activities are located near the intersection of these filaments, which presumably evolves into a massive cluster of galaxies in the local Universe. This may suggest that massive galaxy formation occurs at the characteristic place in the surrounding large-scale structure at high redshift.Comment: 11 pages, 3 figures, accepted for publication in ApJ Letter

The Rossiter-McLaughlin effect and analytic radial velocity curves for transiting extrasolar planetary systems

A transiting extrasolar planet sequentially blocks off the light coming from the different parts of the disk of the host star in a time dependent manner. Due to the spin of the star, this produces an asymmetric distortion in the line profiles of the stellar spectrum, leading to an apparent anomaly of the radial velocity curves, known as the Rossiter - McLaughlin effect. Here, we derive approximate but accurate analytic formulae for the anomaly of radial velocity curves taking account of the stellar limb darkening. The formulae are particularly useful in extracting information of the projected angle between the planetary orbit axis and the stellar spin axis, \lambda, and the projected stellar spin velocity, V sin I_s. We create mock samples for the radial curves for the transiting extrasolar system HD209458, and demonstrate that constraints on the spin parameters (V sin I_s, \lambda) may be significantly improved by combining our analytic template formulae and the precision velocity curves from high-resolution spectroscopic observations with 8-10 m class telescopes. Thus future observational exploration of transiting systems using the Rossiter - McLaughlin effect is one of the most important probes to better understanding of the origin of extrasolar planetary systems, especially the origin of their angular momentum.Comment: 39 pages, 16 figures, Accepted to ApJ. To match the published version (ApJ 623, April 10 issue