A note on the growth factor in Gaussian elimination for generalized Higham matrices

The Higham matrix is a complex symmetric matrix A=B+iC, where both B and C are real, symmetric and positive definite and $\mathrm{i}=\sqrt{-1}$ is the imaginary unit. For any Higham matrix A, Ikramov et al. showed that the growth factor in Gaussian elimination is less than 3. In this paper, based on the previous results, a new bound of the growth factor is obtained by using the maximum of the condition numbers of matrixes B and C for the generalized Higham matrix A, which strengthens this bound to 2 and proves the Higham's conjecture.Comment: 8 pages, 2 figures; Submitted to MOC on Dec. 22 201

2,2-Dibromo-N-(4-fluoro­phen­yl)acetamide

In the crystal structure of the title compound, C8H6Br2FNO, C—H⋯O and N—H⋯O hydrogen bonding results in six-membered rings and links the mol­ecules into chains running parallel to the c axis. The dihedral angle between the fluoro­phenyl ring and the acetamide group is 29.5 (5)°

Tetra-μ-benzoato-bis­[(3,5-dimethyl­pyridine)­copper(II)]

In the centrosymmetric binuclear title compound, [Cu2(C7H5O2)4(C7H9N)2], the CuII atom is coordinated by four O atoms from benzoate anions and one N atom from a dimethyl­pyridine ligand. A paddle-wheel-like dimer is formed by two CuII ions and four benzoate anions with two 3,5-dimethyl­pyridine ligands at the axial position of the CuII ions. The dihedral angle between the two unique benzene rings is 84.26 (16)°. The dihedral angles between the pyridine ring and the benzene rings are 61.67 (15) and 34.27 (14)°. There is π–π stacking of inversion-related pyridine rings, with a centroid–centroid distance of 3.833 (2) Å

Highly efficient in vitro adventitious shoot regeneration of Adenosma glutinosum (Linn.) Druce using leaf explants

Adenosma glutinosum (Linn.) Druce is an important aromatic plant, but no information is available regarding its regeneration, callus induction and proliferation from leaf explants. In this study, an in vitro shoot regeneration procedure was developed for native A. glutinosum using leaf explants. Callus induction and shoots regeneration from leaf explants was evaluated on Murashige and Skoog (MS) media supplemented with combinations of 6-benzylaminopurine (6-BA) and α-naphthaleneacetic acid (NAA). Callus induction in all 16 treatments exceeded 95%, and the highest adventitious shoot number per callus (7.22 shoots per explant) was obtained when leaf explants were cultured on MS medium supplemented with 0.5 mg• L-1 6-BA, 0.1 mg• L-1 NAA, 3% sucrose and 0.72% agar. The highest shoots strengthening were obtained when adventitious buds were cultured on half-strength MS medium supplemented with 0.3 mg• L-1 NAA, 3% sucrose, 1.0 g• L-1 active carbon and 0.72% agar. The highest total root number (45.2) and root length (43.3 cm) were obtained when adventitious buds were cultured on half-strength MS medium supplemented with 0.0 mg• L-1 NAA, 3% sucrose, 1.0 g L−1 active carbon and 0.72% agar, while the highest total root surface area (4.1 cm2) and total root volume (114.1 mm3) were obtained when adventitious buds were cultured on half-strength MS medium supplemented with 0.5 mg• L-1 NAA, 3% sucrose, 1.0 g• L-1 active carbon and 0.72% agar. The efficient plant regeneration system developed here will be helpful for rapid micropropagation and further genetic improvement in A. glutinosum. Keywords: Adenoma glutinous, plant growth regulator, plant regenerationAfrican Journal of Biotechnology Vol. 11(29), pp. 7542-7548, 10 April, 201

Stability analysis and evaluation of Zengziyan in Jinfo Mountain under seismic (vibration) action

The dynamics analysis of dangerous rock mass simplified into improved shear-beam model is progressed based on the engineering example of Zenziyan in Jinfo Mountain, and the definite problem of seismic response on stratified rock mass is solved to obtain the maximum response rules of absolute acceleration, shear stress and relative displacement of rock strata, then the practical monitoring data are taken to make contrastive analysis of the above calculation results and verify the rationality of stability evaluation using this analytic method which can complement the quantitative calculation means of dangerous rock mass and provide reference for the similar engineering construction designs