[1] We propose an approach for estimating the polytropic index in the solar wind. This is an artificially introduced parameter simplifying essentially the gasdynamic or magnetogasdynamic modeling of the interplanetary plasma. The problem in the straightforward utilization of the polytropic equation is to find sufficient homogeneous fragments of the solar wind flow, observed by single spacecraft only, where the application of this polytropic equation is correct. We propose an algorithm for following the plasma data time series to ensure the separation of data segments that belong, with high probability, to the same plasma flow flux tube. A linear regression model between logarithms of plasma density and temperature within such a segment provides an estimate for the polytropic index. Some preliminary applications of the algorithm to real data from spacecraft crossings of different solar wind structures are performed for the Bastille event of 14-16 July 2000.Citation: Kartalev, M., M. Dryer, K. Grigorov, and E. Stoimenova (2006), Solar wind polytropic index estimates based on single spacecraft plasma and interplanetary magnetic field measurements,

SU MMARYThe effects of various gibberellin-insensitive semi-dwarfing (Rht) alleles and background genotypes on the growth response of wheat seedlings to simulated low water potential were investigated. Four sets of near-isogenic lines, each consisting of six members (Rht-B1a+Rht-D1a (rht), Rht-B1b, RhtB1c, Rht-D1b, Rht-B1b+Rht-D1b and Rht-B1c+Rht-D1b), and one set of five members (rht, RhtB1b, Rht-B1c, Rht-B1d and Rht-D1b) were germinated in the presence of polyethylene glycol (PEG). The growth responses were assessed by measuring the lengths of the longest root, coleoptile and longest leaf (shoot) and calculating the root length :shoot length ratio and a tolerance index (TI). Seedling growth was significantly affected by the allelic status at the Rht loci, background genes and the water potential. The PEG treatment had major effects on root and shoot growth. Coleoptile growth was mainly affected by the Rht alleles. There were significant interactions of the Rht allele and variety on the growth response to low water potential. Genotypes with longer roots, coleoptiles and shoots when grown in water, as determined by the Rht allelic status (rht, Rht-B1b and Rht-D1b) and varietal background, had the highest TI and maintained this advantage under stress, while genotypes with smaller seedlings (Rht-B1c and Rht-B1c+Rht-D1b) when grown in water were more strongly affected.

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