An almost para-CR structure on a manifold M is given by a distribution HM ⊂ TM together with a field K ∈ Γ(End(HM)) of involutive endomorphisms of HM . If K satisfies an integrability condition, then (HM,K) is called a para-CR structure. The notion of maximally homogeneous para-CR structure of a semisimple type is given. A classification of such maximally homogeneous para-CR structures is given...

background: polymer gel dosimetry is still the only dosimetry method for direct measuring of threedimensional dose distributions. mri polymer gel dosimeters are tissue equivalent and can act as a phantom material. in this study the obtained isodose maps with pagat polymer gel dosimeter were compared to those calculated with egsnrs for singleshot irradiations of 8 and 18 mm collimators of gamma ...

In this paper, we study the distribution of integral points on parametric families of affine homogeneous varieties. By the work of Borel and Harish-Chandra, the set of integral points on each such variety consists of finitely many orbits of arithmetic groups, and we establish an asymptotic formula (on average) for the number of the orbits indexed by their Siegel weights. Our arguments use the e...

wind erosion climatic factor is a measure of climatic factors explaining the wind erosion erosivity. humidity and wind speed are climatic characteristics that must be considered as the erosion parameters. in this study, linear moment analysis (l-moments) and wind erosion climatic factor were used to evaluate the regional climate’s tendency effect on wind erosion in yazd province. wind erosion c...

iran is facing dust storms every year and frequently. this phenomenon has affected, especially in recent years, various aspects of people's lives. the aim of this research is iran’s seasonal clustering in terms of dust storms frequency with visibility less than 1000 and 500 m for the period of 1987–2008. for this purpose, we used the data of 87 synoptic stations that had suitable spatial d...

Closed form expressions for the maximum likelihood estimates MLE of the parameters in a multivariate normal distribution in which the variances are homogeneous and the corre lations are equal is well known However when the correlations are equal but the variances are not homogeneous no closed form expressions are available We provide two iterative procedures that converge rapidly One procedure ...