13,534 research outputs found
Genetic mapping of natural variation in potassium concentrations in shoots of Arabidopsis thaliana
Naturally-occurring variation in K+ concentrations between plant genotypes is potentially exploitable in a number of ways, including altering the relationship between K+ accumulation and growth, enhancing salinity resistance, or improving forage quality. However, achieving these requires greater insight into the genetic basis of the variation in tissue K+ concentrations. To this end, K+ concentrations were measured in the shoots of 70 Arabidopsis thaliana accessions and a Cape Verdi Island/Landsberg erecta recombinant inbred line (RIL) population. The shoot K+ concentrations expressed on the basis of fresh matter (KFM) or dry matter (KDM) were both broadly and normally distributed as was the shoot dry matter content per unit fresh weight (DMC). Using the data from the RILs, four quantitative trait loci (QTL) were identified for KFM and three for KDM. These were located on chromosomes 2, 3, 4, and 5. Two of the QTLs for KFM overlapped with those for KDM. None of these QTLs overlapped with those for fresh weight or dry weight, but the QTL for KDM located on chromosome 3 overlapped with one for DMC. In silico analysis was used to identify known or putative K+ and cation transporter genes whose loci overlapped with the QTLs. In most cases, multiple genes were identified and the possible role of their gene products in determining shoot K+ concentrations is discussed.Hisatomi Harada and Roger A. Leig
Pigmented coating resists thermal shock
Coating pigment composed of zinc oxide and potassium silicate resists the effects of thermal shock and long exposure to direct sunlight
Heavy-light meson in anisotropic lattice QCD
We examine whether the improved quark action on anisotropic lattices
can be used as a framework for the heavy quark, which enables precision
computation of matrix elements of heavy-light mesons. To this end, it is
crucial to verify that a mass independent and nonperturbative tuning of the
parameters is possible. As a first step, we observe the dispersion relation of
heavy-light mesons on a quenched lattice using the action which is
nonperturbatively tuned only for the leading terms. On a lattice with the
spatial cutoff 1.6 GeV and the anisotropy , the
relativity relation holds within 2% accuracy in the quark mass region with the bare anisotropy parameter tuned for the massless quark.
We also apply the action to a calculation of heavy-light decay constants in the
charm quark mass region.Comment: Lattice2002(heavyquark), 3 pages, 2 figure
Study of Light Scalar Meson Structure in decay
We study the quark structure of the sigma meson through the decay of
meson by constructing an effective Lagrangian for charmed mesons
interacting with light mesons based on the chiral symmetry and heavy quark
symmetry. Within the linear realization of the chiral symmetry, we include the
P-wave charmed mesons (, ) as the chiral partners of
(, ), and the light scalar mesons as the chiral partner of the
pseudoscalar mesons. In the light meson sector, both the and
states are incorporated respecting their different U(1)
transformation properties. We predict the decay width with
two pions in the channel, which can be tested in the future
experiment. We find that the width increases with the percentage of the
content in the sigma meson.Comment: 5 pages, 2 figures, Contribution to KMI Inauguration Conference
"Quest for the Origin of Particles and the Universe" (KMIIN), 24-26 Nov.
2011, KMI, Nagoya Universit
Plasma-sprayed self-lubricating coatings
One of the most important criterion for acceptable commercial application of a multiple phase composition is uniformity and reproducibility. This means that the performance characteristics of the coat - e.g., its lubricating properties, bond strength to the substrate, and thermal properties - can be readily predicted to give a desired performance. The improvement of uniformity and reproducibility of the coats, the oxidation behavior at three temperature ranges, the effect of bond coat and the effect of preheat treatment as measured by adhesive strength tests, coating examination procedures, and physical property measurements were studied. The following modifications improved the uniformity and reproducibility: (1) changes and closer control in the particle size range of the raw materials used, (2) increasing the binder content from 3.2% to 4.1% (dried weight), and (3) analytical processing procedures using step by step checking to assure consistency
A Parametric Study of the Acoustic Mechanism for Core-Collapse Supernovae
We investigate the criterion for the acoustic mechanism to work successfully
in core-collapse supernovae. The acoustic mechanism is an alternative to the
neutrino-heating mechanism. It was proposed by Burrows et al., who claimed that
acoustic waves emitted by -mode oscillations in proto-neutron stars (PNS)
energize a stalled shock wave and eventually induce an explosion. Previous
works mainly studied to which extent the -modes are excited in the PNS. In
this paper, on the other hand, we investigate how strong the acoustic wave
needs to be if it were to revive a stalled shock wave. By adding the acoustic
power as a new axis, we draw a critical surface, an extension of the critical
curve commonly employed in the context of neutrino heating. We perform both 1D
and 2D parametrized simulations, in which we inject acoustic waves from the
inner boundary. In order to quantify the power of acoustic waves, we use the
extended Myers theory to take neutrino reactions into proper account. We find
for the 1D simulations that rather large acoustic powers are required to
relaunch the shock wave, since the additional heating provided by the secondary
shocks developed from acoustic waves is partially canceled by the neutrino
cooling that is also enhanced. In 2D, the required acoustic powers are
consistent with those of Burrows et al. Our results seem to imply, however,
that it is the sum of neutrino heating and acoustic powers that matters for
shock revival.Comment: 20 pages, 19 figures, accepted by Ap
Nontriviality of Gauge-Higgs-Yukawa System and Renormalizability of Gauged NJL Model
In the leading order of a modified 1/Nc expansion, we show that a class of
gauge-Higgs-Yukawa systems in four dimensions give non-trivial and well-defined
theories in the continuum limit. The renormalized Yukawa coupling y and the
quartic scalar coupling \lambda have to lie on a certain line in the
(y,\lambda) plane and the line terminates at an upper bound. The gauged
Nambu--Jona-Lasinio (NJL) model in the limit of its ultraviolet cutoff going to
infinity, is shown to become equivalent to the gauge-Higgs-Yukawa system with
the coupling constants just on that terminating point. This proves the
renormalizability of the gauged NJL model in four dimensions. The effective
potential for the gauged NJL model is calculated by using renormalization group
technique and confirmed to be consistent with the previous result by Kondo,
Tanabashi and Yamawaki obtained by the ladder Schwinger-Dyson equation.Comment: 32 pages, LaTeX, 3 Postscript Figures are included as uuencoded files
(need `epsf.tex'), KUNS-1278, HE(TH) 94/10 / NIIG-DP-94-2. (Several
corrections in the introduction and references.
Scaling Behavior in Soliton Models
In the framework of chiral soliton models we study the behavior of static
nucleon properties under rescaling of the parameters describing the effective
meson theory. In particular we investigate the question of whether the
Brown--Rho scaling laws are general features of such models. When going beyond
the simple Skyrme model we find that restrictive constraints need to be imposed
on the mesonic parameters in order to maintain these scaling laws. Furthermore,
in the case when vector mesons are included in the model it turns out that the
isoscalar form factor no longer scales according to these laws. Finally we note
that, in addition to the exact scaling laws of the model, one may construct
approximate {\it local scaling laws}, which depend of the particular choice of
Lagrangian parameters.Comment: 10 pages Latex, figures added using epsfi
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