Evolved polygenic herbicide resistance in Lolium rigidum by low-dose herbicide selection within standing genetic variation

The interaction between environment and genetic traits under selection is the basis of evolution. In this study, we have investigated the genetic basis of herbicide resistance in a highly characterized initially herbicide-susceptible Lolium rigidum population recurrently selected with low (below recommended label) doses of the herbicide diclofop-methyl. We report the variability in herbicide resistance levels observed in F1 families and the segregation of resistance observed in F2 and back-cross (BC) families. The selected herbicide resistance phenotypic trait(s) appear to be under complex polygenic control. The estimation of the effective minimum number of genes (NE), depending on the herbicide dose used, reveals at least three resistance genes had been enriched. A joint scaling test indicates that an additive-dominance model best explains gene interactions in parental, F1, F2 and BC families. The Mendelian study of six F2 and two BC segregating families confirmed involvement of more than one resistance gene. Cross-pollinated L. rigidum under selection at low herbicide dose can rapidly evolve polygenic broad-spectrum herbicide resistance by quantitative accumulation of additive genes of small effect. This can be minimized by using herbicides at the recommended dose which causes high mortality acting outside the normal range of phenotypic variation for herbicide susceptibility

Violation of Equivalence Principle and Solar Neutrinos

We have updated the analysis for the solution to the solar neutrino problem by the long-wavelength neutrino oscillations induced by a tiny breakdown of the weak equivalence principle of general relativity, and obtained a very good fit to all the solar neutrino data.Comment: 3 pages, 5 figures, uses espcrc2.sty, Talk presented by H. Nunokawa at Europhysics Neutrino Oscillation Workshop (NOW2000), Otranto, Italy, September 9-16, 200

The Solar Neutrino Problem in the Light of a Violation of the Equivalence Principle

We have found that long-wavelength neutrino oscillations induced by a tiny breakdown of the weak equivalence principle of general relativity can provide a viable solution to the solar neutrino problem.Comment: 3 pages, 1 eps figure, Talk given by R. Zukanovich Funchal at the VIth International Workshop on ``Topics in Astroparticle and Underground Physics'' (TAUP99), Sep. 6-10, 1999, College de France, Paris - Franc

Very Long Baseline Neutrino Oscillation Experiment for Precise Measurements of Mixing Parameters and CP Violating Effects

We analyze the prospects of a feasible, Brookhaven National Laboratory based, very long baseline (BVLB) neutrino oscillation experiment consisting of a conventional horn produced low energy wide band beam and a detector of 500 kT fiducial mass with modest requirements on event recognition and resolution. Such an experiment is intended primarily to determine CP violating effects in the neutrino sector for 3-generation mixing. We analyze the sensitivity of such an experiment. We conclude that this experiment will allow determination of the CP phase $\delta_{CP}$ and the currently unknown mixing parameter $\theta_{13}$, if $\sin ^2 2 \theta_{13} \geq 0.01$, a value $\sim 15$ times lower than the present experimental upper limit. In addition to $\theta_{13}$ and $\delta_{CP}$, the experiment has great potential for precise measurements of most other parameters in the neutrino mixing matrix including $\Delta m^2_{32}$, $\sin^2 2\theta_{23}$, $\Delta m^2_{21}\times \sin 2 \theta_{12}$, and the mass ordering of neutrinos through the observation of the matter effect in the $\nu_\mu \to \nu_e$ appearance channel.Comment: 12 pages, 10 figure

Parameter Degeneracies in Neutrino Oscillation Measurement of Leptonic CP and T Violation

The measurement of the mixing angle \theta_{13}, sign of \Delta m^2_{13} and the CP or T violating phase \delta is fraught with ambiguities in neutrino oscillation. In this paper we give an analytic treatment of the paramater degeneracies associated with measuring the \nu_\mu -> \nu_e probability and its CP and/or T conjugates. For CP violation, we give explicit solutions to allow us to obtain the regions where there exist two-fold and four-fold degeneracies. We calculate the fractional differences, \Delta \theta / \bar{\theta}, between the allowed solutions which may be used to compare with the expected sensitivities of the experiments. For T violation we show that there is always a complete degeneracy between solutions with positive and negative \Delta m^2_{13} which arises due to a symmetry and cannot be removed by observing one neutrino oscillation probability and its T conjugate. Thus, there is always a four fold parameter degeneracy apart from exceptional points. Explicit solutions are also given and the fractional differences are computed. The bi-probability CP/T trajectory diagrams are extensively used to illuminate the nature of the degeneracies.Comment: 35 pages, Latex, 11 postscript figures, minor correction

Evolutionary trajectories in rugged fitness landscapes

We consider the evolutionary trajectories traced out by an infinite population undergoing mutation-selection dynamics in static, uncorrelated random fitness landscapes. Starting from the population that consists of a single genotype, the most populated genotype \textit{jumps} from a local fitness maximum to another and eventually reaches the global maximum. We use a strong selection limit, which reduces the dynamics beyond the first time step to the competition between independent mutant subpopulations, to study the dynamics of this model and of a simpler one-dimensional model which ignores the geometry of the sequence space. We find that the fit genotypes that appear along a trajectory are a subset of suitably defined fitness \textit{records}, and exploit several results from the record theory for non-identically distributed random variables. The genotypes that contribute to the trajectory are those records that are not \textit{bypassed} by superior records arising further away from the initial population. Several conjectures concerning the statistics of bypassing are extracted from numerical simulations. In particular, for the one-dimensional model, we propose a simple relation between the bypassing probability and the dynamic exponent which describes the scaling of the typical evolution time with genome size. The latter can be determined exactly in terms of the extremal properties of the fitness distribution.Comment: Figures in color; minor revisions in tex

Quantum Interference: From Kaons to Neutrinos (with Quantum Beats in between)

Using the vehicle of resolving an apparent paradox, a discussion of quantum interference is presented. The understanding of a number of different physical phenomena can be unified, in this context. These range from the neutral kaon system to massive neutrinos, not to mention quantum beats, Rydberg wave packets, and neutron gravity.Comment: 12 pages, LaTeX, 3 figure

Development and application of C - scan ultrasonic facility

This paper presents the in-house development and application of a C-scan ultrasonic facility ULTIMA 200M2 at the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, carried out in collaboration with the Electronics Division, Bhabha Atomic Research Centre (BARC), Mumbai. The paper describes various constituents of the system developed and also highlights the typical results obtained using this system, including bond integrity assessment of explosive welds and imaging of fuel sub-assembly heads of the Fast Breeder Test Reactor. The system has also been used for imaging both the sides of a one rupee Indian coin. All the finer details of the coin could be extracted, demonstrating the resolution capabilities of the system

Twenty Years of Galactic Observations in Searching for Bursts of Collapse Neutrinos with the Baksan Underground Scintillation Telescope

The results of twenty-year-long Galactic observations in neutrino radiation are summarized. Except for the recording of a neutrino signal from the supernova SN 1987A, no Galactic bursts of collapse neutrinos have been detected. An upper bound on the mean frequency of gravitational collapses in our Galaxy was obtained, $f_{collapse} (90$.Comment: latex, 7 pages, 2 eps figure