pax1-1 partially suppresses gain-of-function mutations in Arabidopsis AXR3/IAA17

Background: The plant hormone auxin exerts many of its effects on growth and development by controlling transcription of downstream genes. The Arabidopsis gene AXR3/IAA17 encodes a member of the Aux/IAA family of auxin responsive transcriptional repressors. Semi-dominant mutations in AXR3 result in an increased amplitude of auxin responses due to hyperstabilisation of the encoded protein. The aim of this study was to identify novel genes involved in auxin signal transduction by screening for second site mutations that modify the axr3-1 gain-of-function phenotype. Results: We present the isolation of the partial suppressor of axr3-1 (pax1-1) mutant, which partially suppresses almost every aspect of the axr3-1 phenotype, and that of the weaker axr3-3 allele. axr3-1 protein turnover does not appear to be altered by pax1-1. However, expression of an AXR3:: GUS reporter is reduced in a pax1-1 background, suggesting that PAX1 positively regulates AXR3 transcription. The pax1-1 mutation also affects the phenotypes conferred by stabilising mutations in other Aux/IAA proteins; however, the interactions are more complex than with axr3-1. Conclusion: We propose that PAX1 influences auxin response via its effects on AXR3 expression and that it regulates other Aux/IAAs secondarily

Seasonal cycles of ozone and oxidized nitrogen species in northeast Asia - 2:A model analysis of the roles of chemistry and transport

[1] The dominant factors controlling the seasonal variations of ozone (O-3) and three major oxidized nitrogen species, peroxyacetyl nitrate (PAN), nitrogen oxides (NOx), and nitric acid (HNO3), in northeast Asia are investigated by using a three-dimensional global chemical transport model to analyze surface observations made at Rishiri Island, a remote island in northern Japan. The model was evaluated by comparing with observed seasonal variations, and with the relationships between O-3, CO, and PAN. We show that the model reproduces the chemical environment at Rishiri Island reasonably well, and that the seasonal cycles of O-3, CO, NOy species, and VOCs are well predicted. The impact of local emissions on some of these constituents is significant, but is not the dominant factor affecting the seasonal cycles. The seasonal roles of chemistry and transport in controlling O-3 and PAN are revealed by examining production/ destruction and import/ export/deposition fluxes in the boundary layer over the Rishiri region. For O-3, transport plays a key role throughout the year, and the regional photochemical contribution is at most 10% in summer. For PAN, in contrast, transport dominates in winter, while in-situ chemistry contributes as much as 75% in summer. It is suggested that the relative contribution of transport and in-situ chemistry is significantly different for O-3 and PAN, but that the wintertime dominance of transport due to the long chemical lifetimes of these species is sufficient to drive the seasonal cycles of springtime maximum and summertime minimum characteristic of remote sites

Principal series of finite subgroups of SU(3)

We attempt to give a complete description of the "exceptional" finite subgroups Sigma(36x3), Sigma(72x3) and Sigma(216x3) of SU(3), with the aim to make them amenable to model building for fermion masses and mixing. The information on these groups which we derive contains conjugacy classes, proper normal subgroups, irreducible representations, character tables and tensor products of their three-dimensional irreducible representations. We show that, for these three exceptional groups, usage of their principal series, i.e. ascending chains of normal subgroups, greatly facilitates the computations and illuminates the relationship between the groups. As a preparation and testing ground for the usage of principal series, we study first the dihedral-like groups Delta(27) and Delta(54) because both are members of the principal series of the three groups discussed in the paper.Comment: 43 pages, no figures; typos corrected, clarifications and references added, version matches publication in J. Phys.

Phenomenological Bounds on B to Light Semileptonic Form Factors

The form factors for the weak currents between B and light mesons are studied by relating them to the corresponding D form factors at q^2_{max} according to HQET, by evaluating them at q^2=0 by QCD sum rules, and by assuming a polar q^2 dependence. The results found are consistent with the information obtained from exclusive non-leptonic two-body decays and, with the only exception of A_1, with lattice calculations.Comment: 8 LaTeX pages + 2 figures. Will appear in Mod. Phys. Lett.

Is CP Violation Observable in Long Baseline Neutrino Oscillation Experiments ?

We have studied CP violation originated by the phase of the neutrino mixing matrix in the long baseline neutrino oscillation experiments. The direct measurements of CP violation is the difference of the transition probabilities between CP-conjugate channels. In those experiments, the CP violating effect is not suppressed if the highest neutrino mass scale is taken to be 1\sim 5 \eV, which is appropriate for the cosmological hot dark matter. Assuming the hierarchy for the neutrino masses, the upper bounds of CP violation have been caluculated for three cases, in which mixings are constrained by the recent short baseline ones. The calculated upper bounds are larger than $10^{-2}$, which will be observable in the long baseline accelerator experiments. The matter effect, which is not CP invariant, has been also estimated in those experiments.Comment: 28 pages, LaTex file, 6 figures included using epsfig Matter effect is estimated(Figs.3(a) (b)). Physical parameters are change

On the measurement of leptonic CP violation

We show that the simultaneous determination of the leptonic CP-odd phase $\delta$ and the angle $\theta_{13}$ from the subleading transitions $\nu_e\to\nu_\mu$ and ${\bar\nu}_e\to{\bar\nu}_\mu$ results generically, at fixed neutrino energy and baseline, in two degenerate solutions. In light of this, we refine a previous analysis of the sensitivity to leptonic CP violation at a neutrino factory, in the LMA-MSW scenario, by exploring the full range of $\delta$ and $\theta_{13}$. Furthermore, we take into account the expected uncertainties on the solar and atmospheric oscillation parameters and in the average Earth matter density along the neutrino path. An intermediate baseline of O(3000) km is still the best option to tackle CP violation, although a combination of two baselines turns out to be very important in resolving degeneracies.Comment: 19 pages, 14 figures, uses epsfi

Neutrino masses and mixings in a seesaw framework

Assuming the seesaw mechanism for hierarchical neutrino masses, we calculate the heavy neutrino masses under the hypotheses that the mixing in the Dirac leptonic sector is similar to the quark mixing ($V_D \sim V_{CKM}$) and that $M_{\nu} \sim M_u$ or $M_e$, where $M_{\nu}$ is the Dirac mass matrix of neutrinos. As a result we find that for $M_{\nu} \sim M_u$ the vacuum oscillation solution of the solar neutrino problem leads to a scale for the heavy neutrino mass well above the unification scale, while for the MSW solutions there is agreement with this scale. For $M_{\nu} \sim M_e$ the vacuum solution is consistent with the unification scale, and the MSW solutions with an intermediate scale. The mass of the lightest heavy neutrino can be as small as $10^5$ GeV.Comment: 13 pages RevTex, no figures. Revised versio

Natural Neutrino Mass Matrix

Naturalness of the neutrino mass hierarchy and mixing is studied. First we select among 12 neutrino mixing patterns a few patterns, which could form the natural neutrino mass matrix. Further we show that if the Dirac neutrino mass matrix is taken as the natural one in the quark sector, then only two mixing patterns without the large mixing lead to the natural right-handed Majorana mass matrix. The rest of the chosen patterns with three degenerate mass solution lead to the unnatural right-handed Majorana mass matrix in the see-saw mechanism. Notice however, that for the chosen two natural patterns there could be a huge mass hierarchy such as ${\cal O}(10^{4\sim 6})$ in order to reproduce the inverse mass hierarchy of the light neutrinos.Comment: 31 pages, LaTex file, no figures, arguments made more clear, main conclusions unchanged, version accepted for publication in PRD Reort-no: Lund-Mph-97/14 Revise

Long-term changes in lower tropospheric baseline ozone concentrations at northern mid-latitudes

Changes in baseline (here understood as representative of continental to hemispheric scales) tropospheric O<sub>3</sub> concentrations that have occurred at northern mid-latitudes over the past six decades are quantified from available measurement records with the goal of providing benchmarks to which retrospective model calculations of the global O<sub>3</sub> distribution can be compared. Eleven data sets (ten ground-based and one airborne) including six European (beginning in the 1950's and before), three North American (beginning in 1984) and two Asian (beginning in 1991) are analyzed. When the full time periods of the data records are considered a consistent picture emerges; O<sub>3</sub> has increased at all sites in all seasons at approximately 1% yr<sup>−1</sup> relative to the site's 2000 yr mixing ratio in each season. For perspective, this rate of increase sustained from 1950 to 2000 corresponds to an approximate doubling. There is little if any evidence for statistically significant differences in average rates of increase among the sites, regardless of varying length of data records. At most sites (most definitively at the European sites) the rate of increase has slowed over the last decade (possibly longer), to the extent that at present O<sub>3</sub> is decreasing at some sites in some seasons, particularly in summer. The average rate of increase before 2000 shows significant seasonal differences (1.08 ± 0.09, 0.89 ± 0.10, 0.85 ± 0.11 and 1.21 ± 0.12% yr<sup>−1</sup> in spring, summer, autumn and winter, respectively, over North America and Europe)

From parameter space constraints to the precision determination of the leptonic Dirac CP phase

We discuss the precision determination of the leptonic Dirac CP phase $\delta_{CP}$ in neutrino oscillation experiments, where we apply the concept of ``CP coverage''. We demonstrate that this approach carries more information than a conventional CP violation measurement, since it also describes the exclusion of parameter regions. This will be very useful for next-generation long baseline experiments where for sizable $\sin^2 2 \theta_{13}$ first constraints on $\delta_{CP}$ can be obtained. As the most sophisticated experimental setup, we analyze neutrino factories, where we illustrate the major difficulties in their analysis. In addition, we compare their potential to the one of superbeam upgrades and next-generation experiments, which also includes a discussion of synergy effects. We find a strong dependence on the yet unknown true values of $\sin^2 2 \theta_{13}$ and $\delta_{CP}$, as well as a strong, non-Gaussian dependence on the confidence level. A systematic understanding of the complicated parameter dependence will be given. In addition, it is shown that comparisons of experiments and synergy discussions do in general not allow for an unbiased judgment if they are only performed at selected points in parameter space. Therefore, we present our results in dependence of the yet unknown true values of $\sin^2 2 \theta_{13}$ and $\delta_{CP}$. Finally we show that for $\delta_{CP}$ precision measurements there exist simple strategies including superbeams, reactor experiments, superbeam upgrades, and neutrino factories, where the crucial discriminator is $\sin^2 2 \theta_{13} \sim 10^{-2}$.Comment: 32 pages, 9 figure