The N = 2 supersymmetry in quantum mechanics involving twocomponent eigenfunction is investigated. PACS numbers: 11.30.Pb, 03.65.Fd, 11.10.Ef ∗Permanent address: Departamento de Ciências Exatas e da Natureza, Universidade Federal da Paráıba, Cajazeiras PB, 58.900-000 Brazil. E-mail to RLR is [email protected] or [email protected] and E-mail to ANV is [email protected].

The oxy-myoglobin (Mb-O2) structure was probed by QM/MM (hybrid quantum mechanical/ molecular mechanical) calculations using DFT/MM to elucidate the effect of the heme propionates and the protein matrix on the chemistry of heme Fe-O2 moiety. On this line, we have probed the role of His97 in various protonation states of the heme propionate-6.

Spectral properties of sign symmetric matrices are studied. A criterion for sign symmetry of shifted basic circulant permutation matrices is proven, and is then used to answer the question which complex numbers can serve as eigenvalues of sign symmetric 3 × 3 matrices. The results are applied in the discussion of the eigenvalues of QM -matrices. In particular, it is shown that for every positiv...

We consider classes of models related to those introduced by Lehmann in 1953 and Sklar in 1959. Recently developed algorithms for finding profile NP likelihood procedures are discussed, extended and implemented for such models by combining them with the MM algorithm. In particular we consider statistical procedures for a regression model with proportional expected hazard rates, and for transfor...

Gravity models are widely used to explain patterns of trade. However, two stylized features of trade data, sample selection and heteroskedasticity, challenge the estimation of gravity models. We propose a Two-Step Method of Moments (TS-MM) estimator that deals with both issues. The Monte-Carlo experiments show that the TS-MM estimates are resistant to various combinations of sample selection an...