45 research outputs found
Cytogenetics of Vitis IV: Backcross derivatives of V. vinifera L. x V. rotundifolia MICHX.
Diploid ibackcross :progeny of (V. vinifera L. x V. rotundifolia MICHX.) x V. vinifera L. were studied in the present investigation.In the diploid backcross (BC1) progeny a range from completely sterile seedlings to others as fertile as standard V. vinifera varietes was obtained.Average bivalent formation at MI in the diploid BC1 progeny varied from 7.9 to 16.1. There was a relation in BC1 hyibrids between chromosomal pairing at MI and fertility of the seedlings.BC1 seedlings ,segregated for some V. rotundifolia characters (fruit quality, flavor, type of bark, tendrils, diaphragm, size of flower clusters, shape of the leaves, etc.). Wood type was the only characteristic of V. rotundifolia. which was found in all BC1 seedlings.Crossability pattern of the BC1 progeny to V. vinifera and V. rotundifolia was the same as that of F1 VR hybrids; namely, only as a female parent to V. rotundifolia and female or male to V. vinifera
Cytogenetics of Vitis V. Allotetraploids of V. vinifera L. x V. rotundifolia MICHX.
The allotetraploid hybrids obtained by colchicine treatment of the completely sterile F1 diploid hybrids revealed very low and erratic fertility. A great variation in the fertility between seedlings was the rule.There is no apparent relation between chromosome pairing at MI and fertility of the allotetraploid vines. Average bivalent formation in the allotetraploids varied between 25.0 and 31.1 per cell compared to the expected 39 if complete pairing occurred.In all of the allotetraploid seedlings dominance of V. rotundifolia morphological characters was evident, although several exceptions were noted.Autotetraploid clones of the two species could be hybridized only by using V. vinifera as a female and V. rotundifolia as a male parent.Crossing behaviour of the allotetraploid F1 hybrids is identical to diploid VR hybrids. Hybrids are crossable among themselves; they can be crossed successfully only as female parents to V. rotundifolia and as female or male parent to V. vinifera.A chromosomal ratio hypothesis is proposed to explain the unilateral crossability pattern between the two species and their hybrid derivaties. The alternative breeding procedures are given for testing this hypothesis
Trapped-Ion Quantum Simulator: Experimental Application to Nonlinear Interferometers
We show how an experimentally realized set of operations on a single trapped
ion is sufficient to simulate a wide class of Hamiltonians of a spin-1/2
particle in an external potential. This system is also able to simulate other
physical dynamics. As a demonstration, we simulate the action of an -th
order nonlinear optical beamsplitter. Two of these beamsplitters can be used to
construct an interferometer sensitive to phase shifts in one of the
interferometer beam paths. The sensitivity in determining these phase shifts
increases linearly with , and the simulation demonstrates that the use of
nonlinear beamsplitters (=2,3) enhances this sensitivity compared to the
standard quantum limit imposed by a linear beamsplitter (=1)
Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H
A model of the collisional kinetics of energetic hydrogen atoms, molecules,
and ions in pure H discharges is used to predict H emission
profiles and spatial distributions of emission from the cathode regions of
low-pressure, weakly-ionized discharges for comparison with a wide variety of
experiments. Positive and negative ion energy distributions are also predicted.
The model developed for spatially uniform electric fields and current densities
less than A/m is extended to non-uniform electric fields, current
densities of A/m, and electric field to gas density ratios MTd at 0.002 to 5 Torr pressure. (1 Td = V m and 1 Torr =
133 Pa) The observed far-wing Doppler broadening and spatial distribution of
the H emission is consistent with reactions among H, H,
H, and H ions, fast H atoms, and fast H molecules, and with
reflection, excitation, and attachment to fast H atoms at surfaces. The
H excitation and H formation occur principally by collisions of
fast H, fast H, and H with H. Simplifications include using a
one-dimensional geometry, a multi-beam transport model, and the average
cathode-fall electric field. The H emission is linear with current
density over eight orders of magnitude. The calculated ion energy distributions
agree satisfactorily with experiment for H and H, but are only in
qualitative agreement for H and H. The experiments successfully modeled
range from short-gap, parallel-plane glow discharges to beam-like,
electrostatic-confinement discharges.Comment: Submitted to Plasmas Sources Science and Technology 8/18/201
Uniform approximation of the distribution for the number of retransmissions of bounded documents
Fluid Models of Many-server Queues with Abandonment
We study many-server queues with abandonment in which customers have general
service and patience time distributions. The dynamics of the system are modeled
using measure- valued processes, to keep track of the residual service and
patience times of each customer. Deterministic fluid models are established to
provide first-order approximation for this model. The fluid model solution,
which is proved to uniquely exists, serves as the fluid limit of the
many-server queue, as the number of servers becomes large. Based on the fluid
model solution, first-order approximations for various performance quantities
are proposed
Production of Slow Protonium in Vacuum
We describe how protonium, the quasi-stable antiproton-proton bound system,
has been synthesized following the interaction of antiprotons with the
molecular ion H in a nested Penning trap environment. From a careful
analysis of the spatial distributions of antiproton annihilation events in the
ATHENA experiment, evidence is presented for protonium production with sub-eV
kinetic energies in states around = 70, with low angular momenta. This work
provides a new 2-body system for study using laser spectroscopic techniques.Comment: 9 pages with 5 figures and 1 table. Proceedings of the 4th
International Conference on Trapped Charged Particles and Fundamental Physics
(TCP 06), published in Hyperfine Interaction