Geometric realizations of generalized algebraic curvature operators

We study the 8 natural GL equivariant geometric realization questions for the space of generalized algebraic curvature tensors. All but one of them is solvable; a non-zero projectively flat Ricci antisymmetric generalized algebraic curvature is not geometrically realizable by a projectively flat Ricci antisymmetric torsion free connection

Simple method for the characterization of intense Laguerre-Gauss vector vortex beams

We report on a method for the characterization of intense, structured optical fields through the analysis of the size and surface structures formed inside the annular ablation crater created on the target surface. In particular, we apply the technique to laser ablation of crystalline silicon induced by femtosecond vector vortex beams. We show that a rapid direct estimate of the beam waist parameter is obtained through a measure of the crater radii. The variation of the internal and external radii of the annular crater as a function of the laser pulse energy, at fixed number of pulses, provides another way to evaluate the beam spot size through numerical fitting of the obtained experimental data points. A reliable estimate of the spot size is of paramount importance to investigate pulsed laser-induced effects on the target material. Our experimental findings offer a facile way to characterize focused, high intensity complex optical vector beams which are more and more applied in laser-matter interaction experiments

Alterations in the Phosphorus Metabolism During Seed Germination of Simarouba glauca

Phosphorus (P) is the second most important macronutrient for plant growth and is responsible for plant metabolism. Phosphorus is an important component of nucleic acid and also a component of phospholipids as a basic requirement for cellular organization and function as a membrane building block. Plants respond to Plant Growth Regulators (PGRs) in phosphorus content in a variety of ways. A study was conducted to assess the activities of acid and alkaline phosphatases on seed germination and seedling growth in response to various PGRs of S. glauca at different time intervals. Seeds were subjected to 100 ppm solutions of various PGRs, which include GA, 6-BA, CCC, SA, Cysteine, and Methionine. The activity of the enzymes ATPase, acid phosphatase, and alkaline phosphatase increases in response to the most of PGRs