Weedy adaptation in Setaria spp.: IX. Effects of salinity, temperature, light and seed dormancy on Setaria faberi seed germination

Life in salty habitats is a function of tolerance to those chemicals at all critical phases of a plant's life history. The ability to withstand salt as an established plant may require different mechanisms and plant traits than those needed to germinate in salty soils. Seeds establishing themselves in high salt content may respond differently depending on the light conditions and seed germinability at the time of salty water imbibition. S. faberi seed (and S. viridis and S. pumila) plants were discovered thriving along the seacoasts of Southern Japan. These plants possess the ability to after-ripen, germinate, emerge and establish themselves, grow and reproduce in the salty soils and salt-laden atmospheres present in these windy habitats. The objectives of this paper are to determine the effect of salt (NaCl) in water imbibed by S. faberi seed during after-ripening and germination, as well temperature and light. Observations made also provide insights on the possible relationship between salt and drought tolerance. Seed germination of all phenotypes inhibited by two percent or more of NaCl. The effects of lesser amounts of NaCl on each of the three phenotypes was highly dependent on the specific temperature and light conditions. The three test phenotypes provided a good range to detect responses to salinity, allowing the observation of both stimulatory and inhibitory responses.Comment: 11 pages, 1 tabl

Effects of Fermion Flavor on Exciton Condensation in Double Layer Systems

We use fermionic path integral quantum Monte Carlo to study the effects of fermion flavor on the physical properties of dipolar exciton condensates in double layer systems. We find that by including spin in the system weakens the effective interlayer interaction strength, yet this has very little effect on the Kosterlitz-Thouless transition temperature. We further find that, to obtain the correct description of screening, it is necessary to account for correlation in both the interlayer and intralayer interactions. We show that while the excitonic binding cannot completely surpress screening by additional fermion flavors, their screening effectiveness is reduced leading to a much higher transition temperatures than predicted with large-N analysis.Comment: 4 pages, 3 figure

Modelling alternative strategies for delivering hepatitis B vaccine in prisons : the impact on the vaccination coverage of the injecting drug user population

Since 2001 hepatitis B vaccination has been offered to prisoners on reception into prisons in England and Wales. However, short campaigns of vaccinating the entire population of individual prisons have achieved high vaccination coverage for limited periods, suggesting that short campaigns may be a preferable way of vaccinating prisoners. A model is used that describes the flow of prisoners through prisons stratified by injecting status to compare a range of vaccination scenarios that describe vaccination on prison reception or via regular short campaigns. Model results suggest that vaccinating on prison reception can capture a greater proportion of the injecting drug user (IDU) population than the comparable campaign scenarios (63% vs. 55 . 6% respectively). Vaccination on prison reception is also more efficient at capturing IDUs for vaccination than vaccination via a campaign, although vaccination via campaigns may have a role with some infections for overall control

On the parametric dependences of a class of non-linear singular maps

We discuss a two-parameter family of maps that generalize piecewise linear, expanding maps of the circle. One parameter measures the effect of a non-linearity which bends the branches of the linear map. The second parameter rotates points by a fixed angle. For small values of the nonlinearity parameter, we compute the invariant measure and show that it has a singular density to first order in the nonlinearity parameter. Its Fourier modes have forms similar to the Weierstrass function. We discuss the consequences of this singularity on the Lyapunov exponents and on the transport properties of the corresponding multibaker map. For larger non-linearities, the map becomes non-hyperbolic and exhibits a series of period-adding bifurcations.Comment: 17 pages, 13 figures, to appear in Discrete and Continuous Dynamical Systems, series B Higher resolution versions of Figures 5 downloadable at http://www.glue.umd.edu/~jrd