40,806 research outputs found
Factors influencing the long-term competitiveness of commercial milk producers: evidence from panel data in East Griqualand, South Africa
This study investigates factors influencing the long-term competitiveness of 11 commercial milk producers from East Griqualand (EG), South Africa using unbalanced panel data for the period 1990 to 2006. Results of a ridge regression analysis show that dairy herd size, the level of farm debt, annual production per cow, technology and policy changes over time, and the ratio of trading income to total milk income influence the long-term competitiveness of these milk producers. To enhance their competitiveness in a deregulated dairy market, relatively small and profitable EG milk producers should consider increasing their herd sizes, as the importance of herd size in explaining competitiveness suggests that size economies exist. All EG milk producers should consider utilising more pasture- and forage-based production systems to lower feed costs and select dairy cattle of superior genetic merit to improve milk yields on pasture.Commercial milk production, competitiveness, panel data, Production Economics,
Sustainable leaching process of phosphates from animal bones to alleviate the world phosphate crisis
Lack of available phosphorus (P) minerals and their very localized regional distribution threatens world food production. Traditional farming methods that recycle various biological wastes and manure for localized fertilization of farmland are our role model, but come with risks such as hygiene, water toxification and passed-on diseases. Here, we present a bran-new hydrothermal process which turns animal bones of kitchen wastes into secondary P sources for fertilization, showing that this hydrothermal humification (HTH) process under 200 °C for 24 h completely disintegrates chemical structure of the biomass, while the simultaneously in-situ prepared artificial humic acid (A-HA) etches even macroscopic bones. Notably, A-HA can solubilize the insoluble P existing in animal bones partly as directly dissolved phosphorus (DP), accounting for 6.36 % of total phosphorus (TP) in the bone wastes. Characterization methods indicate that oxygen-containing functional groups (i.e., -COOH and phenolic-OH) of A-HA can help to corrode bones, causing Ca5(PO4)3(OH) to be decomposed into a large number of more active P minerals, furthermore, leading to high DP (96.79 mg/L) content and the formation of new P-based species. Pot planting experiments show that the resulting liquids were applied as a fertilizer and lead to a significant promotion of the growth of seedlings
Metal-Insulator-Like Behavior in Semimetallic Bismuth and Graphite
When high quality bismuth or graphite crystals are placed in a magnetic field
directed along the c-axis (trigonal axis for bismuth) and the temperature is
lowered, the resistance increases as it does in an insulator but then
saturates. We show that the combination of unusual features specific to
semimetals, i.e., low carrier density, small effective mass, high purity, and
an equal number of electrons and holes (compensation), gives rise to a unique
ordering and spacing of three characteristic energy scales, which not only is
specific to semimetals but which concomitantly provides a wide window for the
observation of apparent field induced metal-insulator behavior. Using
magnetotransport and Hall measurements, the details of this unusual behavior
are captured with a conventional multi-band model, thus confirming the
occupation by semimetals of a unique niche between conventional metals and
semiconductors.Comment: 4 pages, 4 figs, data and discussion on bismuth added, final
published versio
Experimentally obtaining the Likeness of Two Unknown Quantum States on an NMR Quantum Information Processor
Recently quantum states discrimination has been frequently studied. In this
paper we study them from the other way round, the likeness of two quantum
states. The fidelity is used to describe the likeness of two quantum states.
Then we presented a scheme to obtain the fidelity of two unknown qubits
directly from the integral area of the spectra of the assistant qubit(spin) on
an NMR Quantum Information Processor. Finally we demonstrated the scheme on a
three-qubit quantum information processor. The experimental data are consistent
with the theoretical expectation with an average error of 0.05, which confirms
the scheme.Comment: 3 pages, 4 figure
The vortex dynamics of a Ginzburg-Landau system under pinning effect
It is proved that the vortices are attracted by impurities or inhomogeities
in the superconducting materials. The strong H^1-convergence for the
corresponding Ginzburg-Landau system is also proved.Comment: 23page
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