Rhythmic Motion of a Droplet under a DC Electric Field

The effect of a stationary electric field on a water droplet with a diameter of several tens micrometers in oil was examined. Such a droplet exhibits repetitive translational motion between the electrodes in a spontaneous manner. The state diagram of this oscillatory motion was deduced; at 0-20 V the droplet is fixed at the surface of the electrode, at 20-70 V the droplet exhibits small-amplitude oscillatory motion between the electrodes, and at 70-100 V the droplet shows large-amplitude periodic motion between the electrodes. The observed rhythmic motion is explained in a semi-quantitative manner by using differential equations, which includes the effect of charging the droplet under an electric field. We also found that twin droplets exhibit synchronized rhythmic motion between the electrodes

Confirming the Detection of an Intergalactic X-ray Absorber Toward PKS 2155-304

We present new observations on PKS 2155-304 with the Chandra Low Energy Transmission Grating Spectrometer (LETG), using the Advanced CCD Imaging Spectrometer (ACIS). We confirm the detection of an absorption line plausibly identified as OVIII Ly-alpha from the warm-hot intergalactic medium associated with a small group of galaxies along the line of sight, as originally reported by Fang et al. 2002 (here after FANG02). Combining the previous observations in FANG02 and five new, long observations on the same target, we increase the total exposure time by a factor of three, and the total counts per resolution element by a factor of five. The measured line equivalent width is smaller than that observed in FANG02, but still consistent at 90% confidence. We also analyze the XMM-Newton observations on the same target, as well as observations using the Chandra LETG and the High Resolution Camera (HRC) combination. These observations have been used to challenge our reported detection. While no line is seen in either the XMM-Newton and the Chandra LETG+HRC data, we find that our result is consistent with the upper limits from both data sets. We attribute the non-detection to (1) higher quality of the Chandra LETG+ACIS spectrum, and (2) the rather extended wings of the line spread functions of both the XMM RGS and the Chandra LETG+HRC. We discuss the implication of our observation on the temperature and density of the absorber. We also confirm the detection of z ~ 0 OVII absorption and, comparing with previous Chandra analysis, we obtain much tighter constraints on the line properties.Comment: 10 pages, 8 figures, accepted for publication in Ap

Microwave Processing of Metallic Materials

学術論文(Ariticle)journal articl

Diamond chains with multiple-spin exchange interactions

We study the phase diagram of a symmetric spin-1/2 Heisenberg diamond chain with additional cyclic four-spin exchange interactions. The presented analysis supplemented by numerical exact-diagonalization results for finite periodic clusters implies a rich phase diagram containing, apart from standard magnetic and spin-liquid phases, two different tetramer-dimer phases as well as an exotic four-fold degenerate dimerized phase. The characteristics of the established spin phases as well as the nature of quantum phase transitions are discussed, as well.Comment: 6 PRB pages, Added reference

Exact static solutions for discrete ϕ4\phi^4 models free of the Peierls-Nabarro barrier: Discretized first integral approach

We propose a generalization of the discrete Klein-Gordon models free of the Peierls-Nabarro barrier derived in Nonlinearity {\bf 12}, 1373 (1999) and Phys. Rev. E {\bf 72}, 035602(R) (2005), such that they support not only kinks but a one-parameter set of exact static solutions. These solutions can be obtained iteratively from a two-point nonlinear map whose role is played by the discretized first integral of the static Klein-Gordon field, as suggested in J. Phys. A {\bf 38}, 7617 (2005). We then discuss some discrete $\phi^4$ models free of the Peierls-Nabarro barrier and identify for them the full space of available static solutions, including those derived recently in Phys. Rev. E {\bf 72} 036605 (2005) but not limited to them. These findings are also relevant to standing wave solutions of discrete nonlinear Schr{\"o}dinger models. We also study stability of the obtained solutions. As an interesting aside, we derive the list of solutions to the continuum $\phi^4$ equation that fill the entire two-dimensional space of parameters obtained as the continuum limit of the corresponding space of the discrete models.Comment: Accepted for publication in PRE; the M/S has been revised in line with the referee repor

Physical Properties, Star Formation, and Active Galactic Nucleus Activity in Balmer Break Galaxies at 0 < z < 1

We present a spectroscopic study with the derivation of the physical properties of 37 Balmer break galaxies, which have the necessary lines to locate them in star-forming-AGN diagnostic diagrams. These galaxies span a redshift range from 0.045 to 0.93 and are somewhat less massive than similar samples of previous works. The studied sample has multiwavelength photometric data coverage from the ultraviolet to MIR Spitzer bands. We investigate the connection between star formation and AGN activity via optical, mass-excitation (MEx) and MIR diagnostic diagrams. Through optical diagrams, 31 (84%) star-forming galaxies, 2 (5%) composite galaxies and 3 (8%) AGNs were classified, whereas from the MEx diagram only one galaxy was classified as AGN. A total of 19 galaxies have photometry available in all the IRAC/Spitzer bands. Of these, 3 AGN candidates were not classified as AGN in the optical diagrams, suggesting they are dusty/obscured AGNs, or that nuclear star formation has diluted their contributions. Furthermore, the relationship between SFR surface density (\Sigma_{SFR}) and stellar mass surface density per time unit (\Sigma_{M_{\ast}/\tau}) as a function of redshift was investigated using the [OII] \lambda3727, 3729, H\alpha \lambda6563 luminosities, which revealed that both quantities are larger for higher redshift galaxies. We also studied the SFR and SSFR versus stellar mass and color relations, with the more massive galaxies having higher SFR values but lower SSFR values than less massive galaxies. These results are consistent with previous ones showing that, at a given mass, high-redshift galaxies have on average larger SFR and SSFR values than low-redshift galaxies. Finally, bluer galaxies have larger SSFR values than redder galaxies and for a given color the SSFR is larger for higher redshift galaxies.Comment: preprint version, 36 pages, 17 figures, 3 tables, accepted for publication in the Astrophysical Journa

Transient expression of the coat protein of Apple chlorotic leaf spot virus inhibits the viral RNA accumulation in Nicotiana occidentalis

The coat protein of Apple chlorotic leaf spot virus (ACLSV-CP) plays a crucial role in infectivity and efficient viral RNA accumulation in host cells (J. Gen. Virol, 88, 2007). In this study, the effect of ACLSV-CP on viral RNA accumulation in Nicotiana occidentalis was investigated. The CP, CPm40 (an amino acid (aa) substitution of Ala to Ser at aa position 40), CPm75 (a substitution of Phe to Tyr at aa position 75), and CPm40m75 (two aa substitutions at positions 40 and 75) of ACLSV (P205) were transiently expressed in N. occidentalis leaves by agroinfiltration. Immunoblot analysis showed that CP and CPm40m75 accumulated in infiltrated tissues, in contrast to CPm40 and CPm75 which were not detected, suggesting that the stable accumulation of CP is important for effective viral RNA accumulation. However, co-agroinfiltration of an infectious ACLSV cDNA clone (pBICLSF) or pBICLSF-based CP mutants (pBICLCPm40, pBICLCPm75, and pBICLCPm40m75) with a vector expressing CP (pBE2113-CP) showed no viral genomic RNA accumulations were found in any leaves infiltrated with these constructs. The inhibition of ACLSV-RNA accumulation was found only in leaves co-expressed with CP protein, but not with a frame-shift mutant of CP, a movement protein (P50), and a frame-shift mutant of P50. Keywords: Apple chlorotic leaf spot virus, coat protein, protein stability, coat protein mediated resistance (CP-MR), agroinfiltratio

Highly efficient inoculation method of apple viruses to apple seedlings

Virus inoculation to original plants is an important step in research for many reasons. For example, it is used to satisfy Koch’s postulates, to test resistance to viruses in breeding programs, and to analyze gene function by virus vectors etc. However, it is generally difficult to inoculate viruses to woody fruit trees like apple, and an efficient inoculation method has not been developed thus far. In this study, we showed that a biolistic inoculation of total RNAs from infected tissues or virus RNAs resulted in a high infection rate in apple seedlings. Total RNAs extracted from Chenopodium quinoa leaves infected with Apple latent spherical virus (ALSV) or Apple chlorotic leaf spot virus (ACLSV) and ALSV- RNAs from purified virus were biolistically inoculated to the cotyledons of apple seedlings by a Helios Gene Gun system (BIO-RAD) or a PDS-1000/He Particle Delivery System (BIO-RAD). Analysis of true leaves 2-4 weeks after inoculation by Northern blot hybridization, RT-PCR, or ELISA showed that 36 out of 38 plants (95%) inoculated with total RNAs from ALSV-infected tissues, 39 out of 41 plants (95%) inoculated with ALSV-RNAs, and 6 out of 7 plants (86%) inoculated with total RNAs from ACLSV-infected tissues were infected with each virus. Thus, the biolistic inoculation of total RNAs from infected tissues or virus RNAs from purified virus to apple seedlings is found to be an efficient inoculation method of apple viruses. We think that the method can be applied to other virus-fruit tree combinations.Keywords: ALSV, ACLSV, biolistic inoculation, apple, cotyledo

On polymorphic logical gates in sub-excitable chemical medium

In a sub-excitable light-sensitive Belousov-Zhabotinsky chemical medium an asymmetric disturbance causes the formation of localized traveling wave-fragments. Under the right conditions these wave-fragment can conserve their shape and velocity vectors for extended time periods. The size and life span of a fragment depend on the illumination level of the medium. When two or more wave-fragments collide they annihilate or merge into a new wave-fragment. In computer simulations based on the Oregonator model we demonstrate that the outcomes of inter-fragment collisions can be controlled by varying the illumination level applied to the medium. We interpret these wave-fragments as values of Boolean variables and design collision-based polymorphic logical gates. The gate implements operation XNOR for low illumination, and it acts as NOR gate for high illumination. As a NOR gate is a universal gate then we are able to demonstrate that a simulated light sensitive BZ medium exhibits computational universality