A Generalization of a Theorem of Dehon for Simple t-Designs

A generalization of a theorem of Dehon for simple t-designs is proved. Several new families of 4- and 5-designs having certain additional property regarding their block intersection numbers are obtained by applying this result.The author acknowledges the support of SFB Forschungsschwerpunkt-Geometrie Grant, University of Heidelberg.     

Van der Pol oscillator under parametric and forced excitations

We study a van der Pol oscillator under parametric and forced excitations. The case where a system contains a small parameter and is quasilinear and the general case (without the assumption of the smallness of nonlinear terms and perturbations) are studied. In the first case, equations of the first approximation are obtained by the Krylov-Bogolyubov-Mitropol’skii technique, their averaging is performed, frequency-amplitude and resonance curves are studied, and the stability of the given system is considered. In the second case, the possibility of chaotic behavior in a deterministic system of oscillator type is shown. Published in Ukrains’kyi Matematychnyi Zhurnal, Vol. 59, No. 2, pp. 206–216, February, 2007.     

Versatile preparation of poly(1,4‐phenylenevinylene‐co‐1,4‐phenylene‐1,2‐ethanediyl) by CVD polymerization of p‐(methoxymethyl)benzyl chloride

It was demonstrated that a series of copolymers consisting of 1,4‐phenylenevinylene (PV) and 1,4‐phenylene‐1,2‐ethanediyl (PE) units could be prepared from a single monomer, p‐(methoxymethyl)benzyl chloride, via the chemical vapor deposition polymerization (CVDP) method. The composition of the copolymers could be varied simply by altering the monomer activation temperature. The higher the temperature, the lower the content of the PV unit. The photo (PL)‐ and electroluminescence (EL) properties of the copolymers that revealed a blueshift when compared with PPV strongly depend on the amount of the PE units incorporated. The external quantum efficiencies of the electroluminescence devices having the configuration of ITO/PEDOT‐PSS/copolymer/Al‐Li were higher than that of PPV, which can be ascribed to the improved confinement of excitons. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 742–751, 2005     

Regio- and stereoisomeric composition of the product mixture in the Diels–Alder reaction of dicyclopentadiene with bicyclononadiene: a NMR and DFT quantum chemical investigation

The regio- and stereoisomeric composition of the product mixture in the Diels–Alder reaction between dicyclopentadiene and bicyclononadiene is determined by 2D ¹H–¹³C HMQC and HMBC and ¹H 2D DQF COSY and NOESY NMR techniques. The absence in the experimental mixture of one of the expected products is explained by high-level quantum chemical density functional theory calculations.     

Leading baryon spectrum in high-energy nuclear collisions

We compute the leading baryon spectrum in high-energy nuclear collisions in the framework of the Dual parton model. Nucleus-nucleus collisions are treated in full detail. The average rapidity shift of the leading baryon (nuclear stopping power) is studied as a function of the degree of centrality of the collision and the cross-section of the selected events is given. Important differences are found here between proton-nucleus and nucleus-nucleus interactions. The agreement with existing data on proton-nucleus and α?α collisions is quite good.