1,508 research outputs found
Sugarcane Production, Processing and Marketing in Tanzania
Sugarcane is one of the important food and commercial crops of Tanzania. Its production is concentrated mainly in three regions, Morogoro, Kagera and Kilimanjaro. Most of the sugar produced in the country is for home consumption and only a small proportion is exported to service foreign debts. This paper briefly reviews the agronomic, production and marketing aspects of sugarcane in Tanzania, with special emphasis on the factors associated with variation in production during the past ten years. During the 1983/84 season, the country produced slightly over 130, 000 tons of processed sugar, but 1988/89 production had dropped to just about 96, 000 tons. During the 1990's (1991/92-1993/94), production increased in response to the trade liberalization policy of the country. To increase and sustain the country's future sugar pruduction, improved soil management of sugarcane fields, irrigation technology and the use of improved clones need to be introduced. The current marketing and handling structure in the sugar industry requires reform in order to increase efficiency and reduce storage overheads paid by the consumers
Interfacial-Redox-Induced Tuning of Superconductivity in YBa2Cu3O7-δ.
Solid-state ionic approaches for modifying ion distributions in getter/oxide heterostructures offer exciting potentials to control material properties. Here, we report a simple, scalable approach allowing for manipulation of the superconducting transition in optimally doped YBa2Cu3O7-δ (YBCO) films via a chemically driven ionic migration mechanism. Using a thin Gd capping layer of up to 20 nm deposited onto 100 nm thick epitaxial YBCO films, oxygen is found to leach from deep within the YBCO. Progressive reduction of the superconducting transition is observed, with complete suppression possible for a sufficiently thick Gd layer. These effects arise from the combined impact of redox-driven electron doping and modification of the YBCO microstructure due to oxygen migration and depletion. This work demonstrates an effective step toward total ionic tuning of superconductivity in oxides, an interface-induced effect that goes well into the quasi-bulk regime, opening-up possibilities for electric field manipulation
Ionic Tuning of Cobaltites at the Nanoscale
Control of materials through custom design of ionic distributions represents
a powerful new approach to develop future technologies ranging from spintronic
logic and memory devices to energy storage. Perovskites have shown particular
promise for ionic devices due to their high ion mobility and sensitivity to
chemical stoichiometry. In this work, we demonstrate a solid-state approach to
control of ionic distributions in (La,Sr)CoO thin films. Depositing a Gd
capping layer on the perovskite film, oxygen is controllably extracted from the
structure, up-to 0.5 O/u.c. throughout the entire 36 nm thickness. Commensurate
with the oxygen extraction, the Co valence state and saturation magnetization
show a smooth continuous variation. In contrast, magnetoresistance measurements
show no-change in the magnetic anisotropy and a rapid increase in the
resistivity over the same range of oxygen stoichiometry. These results suggest
significant phase separation, with metallic ferromagnetic regions and
oxygen-deficient, insulating, non-ferromagnetic regions, forming percolated
networks. Indeed, X-ray diffraction identifies oxygen-vacancy ordering,
including transformation to a brownmillerite crystal structure. The unexpected
transformation to the brownmillerite phase at ambient temperature is further
confirmed by high-resolution scanning transmission electron microscopy which
shows significant structural - and correspondingly chemical - phase separation.
This work demonstrates room-temperature ionic control of magnetism, electrical
resistivity, and crystalline structure in a 36 nm thick film, presenting new
opportunities for ionic devices that leverage multiple material
functionalities
Large Non-perturbative Effects of Small \Delta m^2_{21}/\Delta m^2_{31} and \sin \theta_{13} on Neutrino Oscillation and CP Violation in Matter
In the framework of three generations, we consider the CP violation in
neutrino oscillation with matter effects. At first, we show that the
non-perturbative effects of two small parameters, \Delta m_{21}^2/\Delta
m_{31}^2 and \sin \theta_{13}, become more than 50% in certain ranges of energy
and baseline length. This means that the non-perturbative effects should be
considered in detailed analysis in the long baseline experiments. Next, we
propose a method to include these effects in approximate formulas for
oscillation probabilities. Assuming the two natural conditions,
\theta_{23}=45^\circ and the fact that the matter density is symmetric, a set
of approximate formulas, which involve the non-perturbative effects, has been
derived in all channels.Comment: 25 pages, 4 figures, version to appear in JHE
Strain-dependent magnetic configurations in manganite-titanate heterostructures probed with soft X-ray techniques
We present a detailed study on the strain-induced magnetic domain structure of a (La,Sr)MnO3 thin film epitaxially grown on a BaTiO3 substrate through the use of polarization-dependent X-ray photoemission electron microscopy and X-ray absorption spectroscopy. Angular-dependent measurements allow us to detect vector magnetization on a single-domain scale, and we relate the strain-induced changes in magnetic anisotropy of the ferromagnetic film to the ferroelectric domain structure of the underlying substrate using X-ray magnetic circular and linear dichroism spectro-microscopy. Comparisons to measurements on a nearly strain free film of (La,Sr)MnO3 grown on a (La,Sr)(Al,Ta)O3 substrate illustrate that the BaTiO3 ferroelectric domain structure imprints specific domain sizes and wall orientations in the (La,Sr)MnO3/BaTiO3 artificial multiferroic heterostructure. Furthermore, a change of the BaTiO3 ferroelectric domain structure either with temperature or with applied electric field results in a corresponding change in the (La,Sr)MnO3 ferromagnetic domain structure, thus showing a possible route to obtain room-temperature electric field control of magnetic anisotropy at the nanoscal
Braid Structure and Raising-Lowering Operator Formalism in Sutherland Model
We algebraically construct the Fock space of the Sutherland model in terms of
the eigenstates of the pseudomomenta as basis vectors. For this purpose, we
derive the raising and lowering operators which increase and decrease
eigenvalues of pseudomomenta. The operators exchanging eigenvalues of two
pseudomomenta have been known. All the eigenstates are systematically produced
by starting from the ground state and multiplying these operators to it.Comment: 11 pages, Latex, no figure
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