Overproduction of indole-3-acetic acid in free-living rhizobia induces transcriptional changes resembling those occurring in nodule bacteroids.

Free-living bacteria grown under aerobic conditions were used to investigate, by next-generation RNA sequencing analysis, the transcriptional profiles of Sinorhizobium meliloti wild-type 1021 and its derivative, RD64, overproducing the main auxin indole-3-acetic acid (IAA). Among the upregulated genes in RD64 cells, we detected the main nitrogen-fixation regulator fixJ, the two intermediate regulators fixK and nifA, and several other genes known to be FixJ targets.

Numerical issues in computing the antitriangular factorization of symmetric indefinite matrices

An algorithm for computing the antitriangular factorization of symmetric matrices, relying only on orthogonal transformations, was recently proposed. The computed antitriangular form straightforwardly reveals the inertia of the matrix. A block version of the latter algorithm was described in a different paper, where it was noticed that the algorithm sometimes fails to compute the correct inertia of the matrix.In this paper we analyze a possible cause of the failure of detecting the inertia and propose a procedure to recover it.

Rank-revealing decomposition of symmetric indefinite matrices via block anti-triangular factorization

We present an algorithm for computing a symmetric rank revealing decomposition of a symmetric n x n matrix A, as defined in the work of Hansen & Yalamov [9]: we factorize the original matrix into a product A = QMQ(T), with Q orthogonal and M symmetric and in block form, with one of the blocks containing the dominant information of A, such as its largest eigenvalues.

Tuning of level-set speed function for speckled image segmentation

The segmentation of speckled images, as the synthetic aperture radar (SAR) images, is usually recognized as a very complex problem, because of the speckle, multiplicative noise, which produces granular images. In segmentation problems, based on level set method, the evolution of the curve is determined by a speed function, which is fundamental to achieve a good segmentation. In this paper we propose a study of the new speed function obtained by the linear combination of image average intensity and image gradient speed functions.

Quantitative morphotectonics of the Pliocene to Quaternary Auletta basin, southern Italy

The geomorphological evolution of the Pliocene-Quaternary Auletta basin, a wide fault-bounded depression of the southern Apennines axial zone, Italy, was reconstructed using both DEM-based morphometric analysis and classical morphotectonic investigations. Morphotectonic analyses have been integrated with geological, structural and paleomagnetic data in order to reconstruct the Quaternary evolution of the area. The Auletta basin coincides with the lower valley of the Tanagro River and is filled by Pliocene to Pleistocene marine and continental sediments.

A MATHEMATICAL MODEL FOR THE ENHANCED CYTOPLASMIC TRANSPORT How to Get (Faster) to the Nucleus

We consider a simple model for signal transport in the cytoplasm. Following some recent experimental evidences, the standard diffusion model is supplemented by advection operated through an attachement/detachement mechanism along microtubules. This model is given by a system of partial differential equations which are cast in different dimensions and connected by suitable exchange rules. A numerical scheme is introduced and some simulations are presented and discussed to show the performances of our model.

Weitzenböck's torsion, Fermi coordinates, and adapted frames

We study Weitzenböck's torsion and discuss its properties. Specifically, we calculate the measured components of Weitzenböck's torsion tensor for a frame field adapted to static observers in a Fermi normal coordinate system that we establish along the world line of an arbitrary accelerated observer in general relativity. A similar calculation is carried out in the standard Schwarzschild-like coordinates for static observers in the exterior Kerr spacetime; we then compare our results with the corresponding curvature components.