[1] We report the results of a hydrographic survey conducted in November, 2002, in the Uzbekistan part of the western basin of the dying Aral Sea. There were very few hydrographic measurements in this region since at least early 1990s. The salinity in the western deep basin of the Aral Sea varied from about 82 psu at the surface to over 94 psu at the bottom. The absolute lake surface level was about 30.5 m. Hence, the observed salinity values were much higher, and the level much lower, than expected according to earlier predictions. The density in the western basin exhibited an extremely strong stratification of $11 kg/m 3 per $20 m in the bottom layer. The picnocline was accompanied by a temperature inversion whose magnitude was $4°C. The observed density stratification effectively isolating the lower part of the water column from surface exchanges may be responsible for the increase of summer SSTs and evaporation rates reported in previous studies. We discovered the hydrogen sulphide contamination in the bottom layer whose upper limit was at the depth of approximately 22 m. Estimates suggest that the western basin salinization occurs not only because of the local evaporation, but also because of the assimilation of the saltier eastern basin water in the course of the interbasin exchange through the connecting channel. The satellite imagery analysis, in particular the Maximum CrossCorrelation method, suggests that the circulation pattern in the Aral Sea in its present limits is cyclonic under the eastern winds that are predominant in the region throughout the year.
Methods. The study of a set of measures for the involvement of fallow lands in active agricultural circulation was carried out in the south of the foreststeppe of the Non-chernozem zone in the Republic of Mordovia. The object of study was arable land that has not been cultivated for more than 14 years. In the experiment various forecrop of winter wheat, the methods of the main tillage separately and in combination with the herbicide roundup were studied. Evaluation of the effectiveness of measures was carried out on the output of grain units in a crop rotation.Results. The use of roundup in the development of the deposit contributed to a decrease in the abundance of perennial weeds in winter wheat crops from 40 to 60%, depending on the forecrop. The greater effect of the herbicide was noted on the options with soil cultivation by disk harrow. The reduction in weediness was here from 45 to 68%. The cultivation of the soil with a disk harrow together with the herbicide contributed to the better cutting and mixing of the plant residues of the sod and grinding of the rhizomes of the Elytrigia repens. The determination of the productivity of winter wheat in the crop rotation link revealed that the introduction of a continuous action herbicide roundup increased the collection of grain units for all forecrop. The maximum increase was during processing with a disc harrow for occupied fallow and barley — 0.95 and 1.44 t of grain units/ha, respectively. The profitability level for these options was also maximum and amounted to 41–42%, the conditional net income — 7842 and 8268 rubles/ha, respectively.
An acoustooptic generator based on the effect of optical heterodyning is investigated theoretically and experimentally. The condition for self-excitation of oscillations in this system is determined, its dependence on parameters of acoustooptic interaction and feedback circuit is analysed. The possibility of single-mode and multimode regimes of operation is shown. Preliminary results of experimental investigations of the generator with a paratellurite acoustooptic cell are presented. Experiments on active mode locking by means of an external harmonic signal are described as well.
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