Limits and Possible Consequences of the Development of Agricultural Production: Modeling Agricultural Situations in the Stavropol Territory, USSR

The Food and Agriculture Program at IIASA focuses its research activities on understanding the nature and dimension of the world's food situation and problems, on exploring possible alternative policies which could improve the present situation in the short and long term, and on investigating the consequences of such policies at various levels - global, national and regional -- and in various time horizons. One part of the research activities focussed on investigations of alternative paths of technology transformation in agriculture with respect to resource limitations and environmental consequences in the long term. The general approach and methodology developed for this investigation is being applied in several case studies on the regional level. The reason for the studies is not only to validate the general methodology but also to develop an applicable tool for detailed investigations for a particular region which could then be applied on a number of similar regions. Furthermore, some specific aspects are being addressed in all these case studies which has been initiated within the IIASA's Food and Agriculture Program. This will allow the behavior of various systems to be compared, according to the selected aspects, and analyzed (in different social, economic and natural resource conditions) according to the selected aspects. One of these case studies is of Stavropol, USSR, and covers the whole of this region. This paper describes the first phase of the study, the problems in this region, the aims for solving them, and the first draft of the methodology which is based on the general framework developed at IIASA

Mechanism of Oxygen Redistribution During Ultra-shallow Junction Formation in Silicon

The transport of dissolved oxygen in the Czochralski silicon towards the arsenic-doped ultra-shallow junction was investigated. Ultra-shallow junction was formed by low-energy As+ ion implantation with the subsequent furnace annealing at 750 C-950 C temperatures for the dopant activation. Oxygen and arse-nic redistributions were investigated by secondary ion mass spectrometry (SIMS) technique. The peculiari-ties of defect creation and transformation were studied by the X-ray diffuse scattering technique (XDS). It was found that oxygen concentration in the arsenic redistribution region is increased a few times already after 1 minute of annealing. Increase of annealing time leads to decrease of oxygen accumulation as a re-sult of oxygen transportation to the SiO2/Si interface. As a result the thickness of screen silicon oxide is in-creased by 0.5 nm. This effect is related with the oxygen gettering from the wafer bulk. A physical mecha-nism of the oxygen transfer is discussed. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3527

The Measurement of the Asymmetry of Tensor-Polarized Deuteron Electrodisintegration at 180 MeV Electron Energy

The nucleon emission asymmetry in d(e, pn)e' reaction was measured using the tensor-polarized deuterium jet target in the VEPP-2 electron storage ring. At the present experimental accuracy, the results for the proton energy interval Ep= 12-100 MeV do not contradict the nonrelativistic calculations.

Quantum effects in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with ⁴He

The radial thermal expansion αr of bundles of single-walled carbon nanotubes saturated with ⁴He impurities to the molar concentration 9.4% has been investigated in the interval 2.5–9.5 K using the dilatometric method. In the interval 2.1–3.7 K α r is negative and is several times higher than the negative αr for pure nanotube bundles. This most likely points to ⁴He atom tunneling between different positions in the nanotube bundle system. The excess expansion was reduced with decreasing ⁴He concentration

Negative-Index Metamaterials: Second-Harmonic Generation, Manley-Rowe Relations and Parametric Amplification

Second harmonic generation and optical parametric amplification in negative-index metamaterials (NIMs) are studied. The opposite directions of the wave vector and the Poynting vector in NIMs results in a "backward" phase-matching condition, causing significant changes in the Manley-Rowe relations and spatial distributions of the coupled field intensities. It is shown that absorption in NIMs can be compensated by backward optical parametric amplification. The possibility of distributed-feedback parametric oscillation with no cavity has been demonstrated. The feasibility of the generation of entangled pairs of left- and right-handed counter-propagating photons is discussed.Comment: 7 pages, 6 figure

The effect of O₂ impurities on the low-temperature radial thermal expansion of bundles of closed single-walled carbon nanotubes

The effect of oxygen impurities upon the radial thermal expansion αr of bundles of closed single-walled carbon nanotubes has been investigated in the temperature interval 2.2–48 K by the dilatometric method. Saturation of bundles of nanotubes with oxygen caused an increase in the positive αr-values in the whole interval of temperatures used. Also, several peaks appeared in the temperature dependence αr(T) above 20 K. The low temperature desorption of oxygen from powders consisting of bundles of single-walled nanotubes with open and closed ends has been investigated

Quantum phenomena in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with ³He. A giant isotope effect

The radial thermal expansion αr of bundles of single-walled carbon nanotubes saturated with ³He up to the molar concentration 9.4% has been investigated in the temperature interval 2.1–9.5 K by high-sensitivity capacitance dilatometry. In the interval 2.1–7 K a negative αr was observed, with a magnitude which exceeded the largest negative αr values of pure and ⁴He-saturated nanotubes by three and two orders of magnitude, respectively. The contributions of the two He isotope impurities to the negative thermal expansion of the nanotube bundles are most likely connected with the spatial redistribution of ⁴He and ³He atoms by tunneling at the surface and inside nanotube bundles. The isotope effect turned out to be huge, probably owing to the higher tunneling probability of ³He atoms

The low-temperature radial thermal expansion of single-walled carbon nanotube bundles saturated with nitrogen

The effect of a N₂ impurity on the radial thermal expansion coefficient αr of single-walled carbon nanotube bundles has been investigated in the temperature interval 2.2–43K by the dilatometric method. Saturation of nanotube bundles with N₂ caused a sharp increase in the positive magnitudes of αr in the whole temperature range used and a very high and wide maximum in the thermal expansion coefficient αr(T) at T~28 K. The lowtemperature desorption of the impurity from the N₂-saturated powder of bundles of single-walled carbon nanotubes with open and closed ends has been investigated

Radial thermal expansion of single-walled carbon nanotube bundles at low temperatures

For the first time the linear coefficient of the radial thermal expansion has been measured on a system of SWNT bundles at low temperatures (2.2–120 K). The measurements were performed using a dilatometer with a sensitivity of 2·10⁻⁹ cm. The cylindrical sample 7 mm high and 10 mm in diameter was obtained by compressing powder. The resulting bundles of the nanotubes were oriented perpendicular to the sample axis. The starting powder contained over 90% of SWNTs with the outer diameter 1.1 nm, the length varying within 5–30 μm. The change of sign of the radial thermal expansion coefficient at 5.5 K was observed

Radial thermal expansion of pure and Xe-saturated bundles of single-walled carbon nanotubes at low temperatures

The radial thermal expansion coefficient ar of pure and Xe-saturated bundles of single-walled carbon nanotubes (CNT) has been measured in the interval 2.2-120 K. The coefficient is positive above T = 5.5 K and negative at lower temperatures. The experiment was made using a low-temperature capacitance dilatometer with a sensitivity of 2·10⁻⁹ cm and the sample was prepared by compacting a CNT powder such that the pressure applied oriented the nanotube axes perpendicular to the axis of the cylindrical sample. The data show that individual nanotubes have a negative thermal expansion while the solid compacted material has a positive expansion coefficient due to expansion of the intertube volume in the bundles. Doping the nanotubes with Xe caused a sharp increase in the magnitude of ar in the whole range of temperatures used, and a peak in the dependence ar(T) in the interval 50-65 K. A subsequent decrease in the Xe concentration lowered the peak considerably but had little effect on the thermal expansion coefficient of the sample outside the region of the peak. The features revealed have been explained qualitatively