59,201 research outputs found
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
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