Incommensurate--commensurate transitions in the mono-axial chiral helimagnet driven by the magnetic field

The zero temperature phase diagram of the mono-axial chiral helimagnet in the magnetic field plane formed by the components parallel and perpendicular to the helical axis is thoroughly analyzed. The nature of the transition to the commensurate state depends on the angle between the field and the helical axis. For field directions close to the directions parallel or perpendicular to the helical axis the transition is continuous, while for intermediate angles the transition is discontinuous and the incommensurate and commensurate states coexist on the transition line. The continuous and discontinuous transition lines are separated by two tricritical points with specific singular behaviour. The location of the continuous and discontinuous lines and of the tricritical points depend strongly on the easy-plane anisotropy, the effect of which is analyzed. For large anisotropy the conical approximation locates the transition line very accurately, although it does not predict the continuous transitions nor the tricitical behaviour. It is shown that for large anisotropy, as in CrNb3S6, the form of the transition line is universal, that is, independent of the sample, and obeys a simple equation. The position of the tricritical points, which is not universal, is theoretically estimated for a sample of CrNb3S6Comment: 10 pages, 9 figure

Mechanisms of Volatile Anesthetic-Induced Myocardial Protection

Volatile anesthetics protect myocardium against reversible and irreversible ischemic injury. Experimental evidence from several in vitro and in vivo animal models demonstrates that volatile agents enhance the recovery of stunned myocardium and reduce the size of myocardial infarction after brief or prolonged coronary artery occlusion and reperfusion, respectively. This protective effect persists after the anesthetic has been discontinued, a phenomenon known as anesthetic-induced preconditioning (APC). Recent clinical data also demonstrates evidence of APC in patients during cardiac surgery. Thus, administration of volatile anesthetics may represent a novel therapeutic approach that reduces morbidity and mortality associated with perioperative myocardial ischemia and infarction. The mechanisms responsible for APC appear to be similar to those implicated in ischemic preconditioning, but nonetheless have subtle differences. Accumulating evidence indicates that APC is characterized by complex signal transduction pathways that may include adenosine receptors, G proteins, protein kinase C, reactive oxygen species, and sarcolemmal or mitochondrial KATP channels. Opioid analgesics may further enhance APC as well. This article will review recent advances in the understanding of mechanisms responsible for volatile anesthetic-induced myocardial protection

Effective Monopole Action at Finite Temperature in SU(2) Gluodynamics

Effective monopole action at finite temperature in SU(2) gluodynamics is studied on anisotropic lattices. Using an inverse Monte-Carlo method and the blockspin transformation for space directions, we determine 4-dimensional effective monopole action at finite temperature. We get an almost perfect action in the continuum limit under the assumption that the action is composed of two-point interactions alone. It depends on a physical scale $b_s$ and the temperature $T$. The temperature-dependence appears with respect to the spacelike monopole couplings in the deconfinement phase, whereas the timelike monopole couplings do not show any appreciable temperature-dependence. The dimensional reduction of the 4-dimensional SU(2) gluodynamics ((SU(2))$_{4D}$) at high temperature is the 3-dimensional Georgi-Glashow model ($(GG)_{3D}$). The latter is studied at the parameter region obtained from the dimensional red uction. We compare the effective instanton action of $(GG)_{3D}$ with the timelike monopole action obtained from (SU(2))$_{4D}$. We find that both agree very well for $T \ge 2.4T_c$ at large $b$ region. The dimensional reduction works well also for the effective action.Comment: 34 pages, 23 figure

On the singular homology of one class of simply-connected cell-like spaces

In our earlier papers we constructed examples of 2-dimensional nonaspherical simply-connected cell-like Peano continua, called {\sl Snake space}. In the sequel we introduced the functor $SC(-,-)$ defined on the category of all spaces with base points and continuous mappings. For the circle $S^1$, the space $SC(S^1, \ast)$ is a Snake space. In the present paper we study the higher-dimensional homology and homotopy properties of the spaces $SC(Z, \ast)$ for any path-connected compact spaces $Z$

Stomagen positively regulates stomatal density in Arabidopsis.

葉の気孔の数を増加させる因子の発見～CO2削減や食糧増産へ向けて～. 京都大学プレスリリース. 2009-12-10.Stomata in the epidermal tissues of leaves are valves through which passes CO(2), and as such they influence the global carbon cycle. The two-dimensional pattern and density of stomata in the leaf epidermis are genetically and environmentally regulated to optimize gas exchange. Two putative intercellular signalling factors, EPF1 and EPF2, function as negative regulators of stomatal development in Arabidopsis, possibly by interacting with the receptor-like protein TMM. One or more positive intercellular signalling factors are assumed to be involved in stomatal development, but their identities are unknown. Here we show that a novel secretory peptide, which we designate as stomagen, is a positive intercellular signalling factor that is conserved among vascular plants. Stomagen is a 45-amino--rich peptide that is generated from a 102-amino-acid precursor protein designated as STOMAGEN. Both an in planta analysis and a semi-in-vitro analysis with recombinant and chemically synthesized stomagen peptides showed that stomagen has stomata-inducing activity in a dose-dependent manner. A genetic analysis showed that TMM is epistatic to STOMAGEN (At4g12970), suggesting that stomatal development is finely regulated by competitive binding of positive and negative regulators to the same receptor. Notably, STOMAGEN is expressed in inner tissues (the mesophyll) of immature leaves but not in the epidermal tissues where stomata develop. This study provides evidence of a mesophyll-derived positive regulator of stomatal density. Our findings provide a conceptual advancement in understanding stomatal development: inner photosynthetic tissues optimize their function by regulating stomatal density in the epidermis for efficient uptake of CO(2)

Vacuum type of SU(2) gluodynamics in maximally Abelian and Landau gauges

The vacuum type of SU(2) gluodynamics is studied using Monte-Carlo simulations in maximally Abelian (MA) gauge and in Landau (LA) gauge, where the dual Meissner effect is observed to work. The dual Meissner effect is characterized by the coherence and the penetration lengths. Correlations between Wilson loops and electric fields are evaluated in order to measure the penetration length in both gauges. The coherence length is shown to be fixed in the MA gauge from measurements of the monopole density around the static quark-antiquark pair. It is also shown numerically that a dimension 2 gluon operator A^+A^-(s) and the monopole density has a strong correlation as suggested theoretically. Such a correlation is observed also between the monopole density and A^2(s)= A^+A^-(s) + A^3A^3(s) condensate if the remaining U(1) gauge degree of freedom is fixed to U(1) Landau gauge (U1LA). The coherence length is determined numerically also from correlations between Wilson loops and A^+A^-(s) and A^2(s) in MA + U1LA gauge. Assuming that the same physics works in the LA gauge, we determine the coherence length from correlations between Wilson loops and A^2(s). Penetration lengths and coherence lengths in the two gauges are almost the same. The vacuum type of the confinement phase in both gauges is near to the border between the type 1 and the type 2 dual superconductors.Comment: 13 pages, 22 figures, RevTeX 4 styl

A list of all integrable 2D homogeneous polynomial potentials with a polynomial integral of order at most 4 in the momenta

We searched integrable 2D homogeneous polynomial potential with a polynomial first integral by using the so-called direct method of searching for first integrals. We proved that there exist no polynomial first integrals which are genuinely cubic or quartic in the momenta if the degree of homogeneous polynomial potentials is greater than 4.Comment: 22 pages, no figures, to appear in J. Phys. A: Math. Ge

Semi-Static Hedging Based on a Generalized Reflection Principle on a Multi Dimensional Brownian Motion

On a multi-assets Black-Scholes economy, we introduce a class of barrier options. In this model we apply a generalized reflection principle in a context of the finite reflection group acting on a Euclidean space to give a valuation formula and the semi-static hedge.Comment: Asia-Pacific Financial Markets, online firs

Chemical Enrichment in Damped Lyman Alpha Systems From Hierarchical Galaxy Formation Models

We investigate chemical enrichment in Damped Lyman alpha (DLA) systems in the hierarchical structure formation scenario using a semi-analytic model of galaxy formation. The model developed by Nagashima, Totani, Gouda and Yoshii takes into account various selection effects on high-redshift galaxies and can show fundamental observational properties of galaxies, such as luminosity functions and number-magnitude/redshift relations. DLA systems offer the possibilities of measuring metal abundance more accurately than faint galaxies. For example, recent measurements of zinc abundance can provide good evidence for understanding the processes of metal pollution and star formation in DLA systems because zinc is virtually unaffected by dust depletion. Here we focus on this advantage for observation in order to explore the metallicity evolution in DLA systems at high redshifts. We can consistently show the metallicity evolution for reasonable models which also reproduce fundamental properties of local galaxy population. This result suggests that the chemical evolution of DLA systems can be consistently reconciled with the observational features of typical galaxies. We also investigate other properties of DLA systems (column density distribution and mass density of cold gas), and find that star formation in massive galaxies should be more active than that in low-mass ones. This is consistent with the results by Nagashima et al. and Cole et al. in which the star formation timescale is set by reproducing cold gas mass fraction in local spiral galaxies. Finally we discuss host galaxies associated with DLA systems. We conclude that they primarily consist of sub-L* and/or dwarf galaxies from the observations.Comment: 16 pages, 11 figures, Accepted for publication in Astrophsical Journa