9,525 research outputs found
Effects of vine rootstocks on chloride concentration in Sultana scions
Sultana vines in the field grafted on any one of a number of rootstocks being tested for compatibility showed substantially reduced petiole chloride as compared with ungrafted sultanas. Self grafted sultanas did not differ from ungrafted in chloride status. There were significant differences between the various effective rootstocks - the degree of reduction of chloride concentration was better than 50 per cent for Dogridge and 1613 stocks, but about 75 per cent for Salt Creek and 101-14
Betaine, organic acids and inulin do not affect ileal and total tract nutrient digestibility or microbial fermentation in piglets
The study was conducted to investigate the effects of betaine alone or combined with organic acids and inulin on ileal and total tract nutrient digestibilities and intestinal microbial fermentation characteristics in piglets. In total, 24 four-week-old barrows with an average initial body weight of 6.7 kg were used in two consecutive experiments with 12 piglets each. Betaine, organic acids and inulin at a level of 0.2, 0.4 and 0.2%, respectively, or combinations of these supplements were added to the basal diet. The supplementation of betaine, organic acids and inulin or any of their combinations did not affect ileal and total tract nutrient digestibilities. The microbial fermentation products both at the ileal and faecal level were not affected by any of the treatments. In conclusion, combining betaine with organic acids and inulin did not have any associated effects on the variables that were measured
Integrable lattices and their sublattices II. From the B-quadrilateral lattice to the self-adjoint schemes on the triangular and the honeycomb lattices
An integrable self-adjoint 7-point scheme on the triangular lattice and an
integrable self-adjoint scheme on the honeycomb lattice are studied using the
sublattice approach. The star-triangle relation between these systems is
introduced, and the Darboux transformations for both linear problems from the
Moutard transformation of the B-(Moutard) quadrilateral lattice are obtained. A
geometric interpretation of the Laplace transformations of the self-adjoint
7-point scheme is given and the corresponding novel integrable discrete 3D
system is constructed.Comment: 15 pages, 6 figures; references added, some typos correcte
Vibrational branching ratios and hyperfine structure of BH and its suitability for laser cooling
The simple structure of the BH molecule makes it an excellent candidate for
direct laser cooling. We measure the branching ratios for the decay of the
state to vibrational levels of the ground state, , and find that they are exceedingly favourable for laser
cooling. We verify that the branching ratio for the spin-forbidden transition
to the intermediate state is inconsequentially small. We
measure the frequency of the lowest rotational transition of the X state, and
the hyperfine structure in the relevant levels of both the X and A states, and
determine the nuclear electric quadrupole and magnetic dipole coupling
constants. Our results show that, with a relatively simple laser cooling
scheme, a Zeeman slower and magneto-optical trap can be used to cool, slow and
trap BH molecules.Comment: 7 pages, 5 figures. Updated analysis of A state hyperfine structure
and other minor revision
Prospects for measuring the electric dipole moment of the electron using electrically trapped polar molecules
Heavy polar molecules can be used to measure the electric dipole moment of
the electron, which is a sensitive probe of physics beyond the Standard Model.
The value is determined by measuring the precession of the molecule's spin in a
plane perpendicular to an applied electric field. The longer this precession
evolves coherently, the higher the precision of the measurement. For molecules
in a trap, this coherence time could be very long indeed. We evaluate the
sensitivity of an experiment where neutral molecules are trapped electrically,
and compare this to an equivalent measurement in a molecular beam. We consider
the use of a Stark decelerator to load the trap from a supersonic source, and
calculate the deceleration efficiency for YbF molecules in both strong-field
seeking and weak-field seeking states. With a 1s holding time in the trap, the
statistical sensitivity could be ten times higher than it is in the beam
experiment, and this could improve by a further factor of five if the trap can
be loaded from a source of larger emittance. We study some effects due to field
inhomogeneity in the trap and find that rotation of the electric field
direction, leading to an inhomogeneous geometric phase shift, is the primary
obstacle to a sensitive trap-based measurement.Comment: 22 pages, 7 figures, prepared for Faraday Discussion 14
Characterization of a cryogenic beam source for atoms and molecules
We present a combined experimental and theoretical study of beam formation
from a cryogenic buffer gas cell. Atoms and molecules are loaded into the cell
by laser ablation of a target, and are cooled and swept out of the cell by a
flow of cold helium. We study the thermalization and flow dynamics inside the
cell and measure how the speed, temperature, divergence and extraction
efficiency of the beam are influenced by the helium flow. We use a finite
element model to simulate the flow dynamics and use the predictions of this
model to interpret our experimental results.Comment: 10 pages, 14 figure
Stochastic multi-channel lock-in detection
High-precision measurements benefit from lock-in detection of small signals.
Here we discuss the extension of lock-in detection to many channels, using
mutually orthogonal modulation waveforms, and show how the the choice of
waveforms affects the information content of the signal. We also consider how
well the detection scheme rejects noise, both random and correlated. We address
the particular difficulty of rejecting a background drift that makes a
reproducible offset in the output signal and we show how a systematic error can
be avoided by changing the waveforms between runs and averaging over many runs.
These advances made possible a recent measurement of the electron's electric
dipole moment.Comment: 11 pages, 3 figure
A robust floating nanoammeter
A circuit capable of measuring nanoampere currents while floating at voltages
up to at least 25kV is described. The circuit relays its output to ground
potential via an optical fiber. We particularly emphasize the design and
construction techniques which allow robust operation in the presence of high
voltage spikes and discharges.Comment: 5 pages, 2 figure
Franck-Condon Factors and Radiative Lifetime of the A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} Transition of Ytterbium Monoflouride, YbF
The fluorescence spectrum resulting from laser excitation of the
A^{2}\Pi_{1/2} - X^{2}\Sigma^{+} (0,0) band of ytterbium monofluoride, YbF, has
been recorded and analyzed to determine the Franck-Condon factors. The measured
values are compared with those predicted from Rydberg-Klein-Rees (RKR)
potential energy curves. From the fluorescence decay curve the radiative
lifetime of the A^{2}\Pi_{1/2} state is measured to be 28\pm2 ns, and the
corresponding transition dipole moment is 4.39\pm0.16 D. The implications for
laser cooling YbF are discussed.Comment: 5 pages, 5 figure
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