Integrated Use of Farmyard Manure and NP fertilizers for Maize on Farmers’ Fields

A study was initiated in 1997 to introduce the culture of supplementing low rates of NP fertilizers with farmyard manure (FYM) in the maize based farming system of western Oromia. The treatments were 0/0, 20/20, 40/25 and 60/30 kg N/P ha−1 and 0, 4, 8, and 12 t FYM ha−1 in factorial arrangement in a randomized complete block design with three replications. The experiment was conducted at Laga Kalla, Walda, Shoboka, Harato, and Bako Research Center using BH-660 hybrid maize. The FYM used for the experiment was well decomposed under shade and spot applied together with the P fertilizer at planting; N was applied in split form. The residual effects of FYM were investigated for Laga Kalla, Walda and Shoboka during the 1998 cropping season. Statistical analysis revealed that the N/P fertilizers and FYM significantly (p 0.05) increased grain yield in all locations except for Walda in 1997. Interactions of FYM and NP fertilizer rates were significant (p ≤ 0.05) at all locations except for Shoboka. The application of FYM alone at rates of 4, 8, and 12 t ha−1 produced average grain yields of 5.76, 5.61 and 5.93 t ha−1, respectively, compared to 3.53 t ha−1 for the control treatment in 1997. There were significant residual effects of FYM and NP fertilizers applied in 1997 on maize grain yields in 1998. Laboratory analysis confirmed that considerable amounts of macronutrients and small amounts of micronutrients were supplied by FYM. Based on the results of this study, the integrated use of properly managed FYM and low rates NP fertilizers could be used for maize production in the areas under consideration. Moreover, sole applications of FYM on relatively fertile soils like Walda and Harato are useful in maintaining soil fertility and are encouraging for resource poor farmers

Spin exchange in quantum rings and wires in the Wigner-crystal limit

We present a controlled method for computing the exchange coupling in strongly correlated one-dimensional electron systems. It is based on the asymptotically exact relation between the exchange constant and the pair-correlation function of spinless electrons. Explicit results are obtained for thin quantum rings with realistic Coulomb interactions, by calculating this function via a many-body instanton approach.Comment: 7 pages, 2 figures. Changes in the text and figures to improve readability; added reference

Second Harmonic Coherent Driving of a Spin Qubit in a Si/SiGe Quantum Dot

We demonstrate coherent driving of a single electron spin using second harmonic excitation in a Si/SiGe quantum dot. Our estimates suggest that the anharmonic dot confining potential combined with a gradient in the transverse magnetic field dominates the second harmonic response. As expected, the Rabi frequency depends quadratically on the driving amplitude and the periodicity with respect to the phase of the drive is twice that of the fundamental harmonic. The maximum Rabi frequency observed for the second harmonic is just a factor of two lower than that achieved for the first harmonic when driving at the same power. Combined with the lower demands on microwave circuitry when operating at half the qubit frequency, these observations indicate that second harmonic driving can be a useful technique for future quantum computation architectures.Comment: 9 pages, 9 figure

Cooling of cryogenic electron bilayers via the Coulomb interaction

Heat dissipation in current-carrying cryogenic nanostructures is problematic because the phonon density of states decreases strongly as energy decreases. We show that the Coulomb interaction can prove a valuable resource for carrier cooling via coupling to a nearby, cold electron reservoir. Specifically, we consider the geometry of an electron bilayer in a silicon-based heterostructure, and analyze the power transfer. We show that across a range of temperatures, separations, and sheet densities, the electron-electron interaction dominates the phonon heat-dissipation modes as the main cooling mechanism. Coulomb cooling is most effective at low densities, when phonon cooling is least effective in silicon, making it especially relevant for experiments attempting to perform coherent manipulations of single spins.Comment: 9 pages, 5 figure

The use of growth models to evaluate the changing response to digestible lysine in high-lean growth gilts

Conventional response criteria for amino acid research include mean live weight gain and tissue accretion rates over a given weight interval. However, these methods fail to characterize the changing response of tissue accretion to dietary amino acids as body weight increases. For this reason, growth modeling was used to characterize the response to digestible lysine in two experiments (114 gilts each) from 80 to 160 lb and 160 to 300 lb, respectively. Corn-soybean meal diets were formulated to assure that lysine (.54 to 1.04% and .54 to .94% digestible lysine for Exp 1 and 2, respectively) was the first limiting amino acid. Analysis of variance was used to test linear and quadratic responses in cumulative weight gain on test as digestible lysine increased. A time by digestible lysine interaction was detected, indicating that a separate regression equation for each lysine level was necessary. In Exp. 1, ADG and carcass CP accretion were maximized for gilts fed 1.04, .94, and .84% digestible lysine from 80 to 100 lb, 100 to 120 lb, and 120 to 160 lb, respectively. Lipid accretion .74 to .84% digestible lysine. In Exp. 2, ADG was maximized by feeding .84% from 160 to 205 lb and .74% from 205 to 300 lb. Carcass CP accretion was maximized by feeding .94% digestible lysine, and lipid accretion was minimized for gilts fed .84% digestible lysine from 160 to 300 lb. If feeding graded levels of digestible lysine resulted in parallel lines for carcass protein accretion, mean values would result in accurate data evaluation. However, responses to digestible lysine changed over the feeding period. Therefore, the use of BW and compositional growth curves offers an innovative approach to more accurately characterize the growing pig\u27s response to increased digestible lysine.; Swine Day, Manhattan, KS, November 17, 199

Gate fidelity and coherence of an electron spin in a Si/SiGe quantum dot with micromagnet

The gate fidelity and the coherence time of a qubit are important benchmarks for quantum computation. We construct a qubit using a single electron spin in a Si/SiGe quantum dot and control it electrically via an artificial spin-orbit field from a micromagnet. We measure an average single-qubit gate fidelity of $\approx$ 99$\%$ using randomized benchmarking, which is consistent with dephasing from the slowly evolving nuclear spins in substrate. The coherence time measured using dynamical decoupling extends up to $\approx$ 400 $\mu$s for 128 decoupling pulses, with no sign of saturation. We find evidence that the coherence time is limited by noise in the 10 kHz $-$ 1 MHz range, possibly because charge noise affecting the spin via the micromagnet gradient. This work shows that an electron spin in a Si/SiGe quantum dot is a good candidate for quantum information processing as well as for a quantum memory, even without isotopic purification