240 research outputs found
Hybrid poplar plantation establishment in Saskatchewan: first year results
Non-Peer ReviewedThe production of Short-Rotation Woody Crops (SRWC) has been growing steadily throughout
North America. In Saskatchewan, interest is focused on developing hybrid poplar (var.
âWalkerâ) plantations for an expanding fibre industry, and as a means to diversify farm income
and possibly to increase sequestered carbon. Preliminary results from a small 6 year-old
plantation suggest that there is good potential for operational-scale hybrid poplar production over
a 15 to 20 year rotation period. Larger-scale field trials were established in the spring of 2002 on
two sites in the Meadow Lake region, to assess and compare select silvicultural practices that are
regarded to enhance the growth of hybrid poplars. After one growing season, both types of
rooted stock (cuttings and plugs) showed superior survivability (~92 %) compared to non-rooted
cuttings (~40 %), underscoring the reduced risk in planting rooted stock, especially during dry
years. Measurements of tree growth (tree height, stem volume, total plant biomass and root
production) all indicated a noticeable advantage of rooted versus non-rooted stock.
Observational data pointed to the necessity of thorough site preparation, adherence to proper
planting techniques, and mechanical or chemical weed control for successful plantation
establishment
Adenylate effects on protein phosphorylation in the interenvelope lumen of pea chloroplasts
A 64-kilodalton (kDa) protein, situated in the lumen between the inner and outer envelopes of pea (Pisum sativum L.) chloroplasts (Soll and Bennett 1988, Eur. J. Biochem., 175, 301â307) is shown to undergo reversible phosphorylation in isolated mixed envelope vesicles. It is the most conspicuously labelled protein after incubation of envelopes with 33 nmol·1-1 [-32P]ATP whereas incubation with 50 mol·1-1 [-32P]ATP labels most prominently two outer envelope proteins (86 and 23 kDa). Half-maximum velocity for phosphorylation of the 64-kDa protein occurs with 200 nmol·1-1 ATP, and around 40 mol·1-1 ATP for phosphorylation of the 86- and 23-kDa proteins, indicating the operation of two distinct kinases. GGuanosine-, uridine-, cytidine 5-triphosphate and AMP are poor inhibitors of the labelling of the 64-kDa protein with [-32P]ATP. On the other hand, ADP has a potent influence on the extent of labelling (half-maximal inhibition at 1â5 mol·1-1). The ADP-dependent appearance of 32P in ATP indicates that ADP acts by reversal of kinase activity and not as a competitive inhibitor. However, the most rapid loss of 32P from pre-labelled 64-kDa protein occurs when envelope vesicles are incubated with ATP t1/2=15 s at 20 molsd1-1 ATP). This induced turnover of phosphate appears to be responsible for the rapid phosphoryl turnover seen in situ
Spatially-resolved potential measurement with ion crystals
We present a method to measure potentials over an extended region using
one-dimensional ion crystals in a radio frequency (RF) ion trap. The
equilibrium spacings of the ions within the crystal allow the determination of
the external forces acting at each point. From this the overall potential, and
also potentials due to specific trap features, are calculated. The method can
be used to probe potentials near proximal objects in real time, and can be
generalized to higher dimensions.Comment: 7 pages (double spaced), 3 figure
Coupled Dipole Method Determination of the Electromagnetic Force on a Particle over a Flat Dielectric Substrate
We present a theory to compute the force due to light upon a particle on a
dielectric plane by the Coupled Dipole Method (CDM). We show that, with this
procedure, two equivalent ways of analysis are possible, both based on
Maxwell's stress tensor. The interest in using this method is that the nature
and size or shape of the object, can be arbitrary. Even more, the presence of a
substrate can be incorporated. To validate our theory, we present an analytical
expression of the force due to the light acting on a particle either in
presence, or not, of a surface. The plane wave illuminating the sphere can be
either propagating or evanescent. Both two and three dimensional calculations
are studied.Comment: 10 pages, 8 figures and 3 table
Long-Wavelength Instability in Surface-Tension-Driven Benard Convection
Laboratory studies reveal a deformational instability that leads to a drained
region (dry spot) in an initially flat liquid layer (with a free upper surface)
heated uniformly from below. This long-wavelength instability supplants
hexagonal convection cells as the primary instability in viscous liquid layers
that are sufficiently thin or are in microgravity. The instability occurs at a
temperature gradient 34% smaller than predicted by linear stability theory.
Numerical simulations show a drained region qualitatively similar to that seen
in the experiment.Comment: 4 pages. The RevTeX file has a macro allowing various styles. The
appropriate style is "mypprint" which is the defaul
Hard diffractive quarkonium hadroproduction at high energies
We present a study of heavy quarkonium production in hard diffractive process
by the Pomeron exchange for Tevatron and LHC energies. The numerical results
are computed using recent experimental determination of the diffractive parton
density functions in Pomeron and are corrected by unitarity corrections through
gap survival probability factor. We give predictions for single as well as
central diffractive ratios. These processes are sensitive to the gluon content
of the Pomeron at small Bjorken-x and may be particularly useful in studying
the small-x physics. They may also be a good place to test the different
available mechanisms for quarkonium production at hadron colliders.Comment: 7 pages, 3 figures, 1 table. Final version to be published in
European Physical Journal
Limiting fragmentation in hadron-hadron collisions at high energies
Limiting fragmentation in proton-proton, deuteron-nucleus and nucleus-nucleus
collisions is analyzed in the framework of the Balitsky-Kovchegov equation in
high energy QCD. Good agreement with experimental data is obtained for a wide
range of energies. Further detailed tests of limiting fragmentation at RHIC and
the LHC will provide insight into the evolution equations for high energy QCD.Comment: 28 pages, 10 figures (2 new figures, text slightly expanded, and some
additional references
Study of the decay mode D^0 -> K-K-K+pi+
Using data from the FOCUS (E831) experiment at Fermilab, we present a new
measurement of the branching ratio for the Cabibbo-favored decay mode . From a sample of fully reconstructed events, we measure .
A coherent amplitude analysis has been performed to determine the resonant
substructure of this decay mode. This analysis reveals a dominant contribution
from and states.Comment: 15 pages, 4 figures, to be submitted to Physics Letters
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