Asymptotic results for weighted means of linear combinations of independent Poisson random variables

ABSTRACT

In this paper we prove the large deviation principle for a class of weighted means of linear combinations of independent Poisson distributed random variables, which converge weakly to a normal distribution. The interest in these linear combinations is motivated by the diffusion approximation in Lansky [On approximations of Stein's neuronal model, J. Theoret. Biol. 107 (1984), pp. 631–647] of the Stein's neuronal model (see Stein [A theoretical analysis of neuronal variability, Biophys. J. 5 (1965), pp. 173–194]). We also prove an analogue result for sequences of multivariate random variables based on the diffusion approximation in Tamborrino, Sacerdote, and Jacobsen [Weak convergence of marked point processes generated by crossings of multivariate jump processes. Applications to neural network modeling, Phys. D 288 (2014), pp. 45–52]. The weighted means studied in this paper generalize the logarithmic means. We also investigate moderate deviations.     

Isolation of Bisphenol A-Tolerating/degrading Shewanella haliotis Strain MH137742 from an Estuarine Environment

Applied Biochemistry and Biotechnology - The human exposure to bisphenol A (BPA) occurs frequently. Once, this compound was one of the highest volume chemicals produced worldwide and used as a...     

Reactions with a Metalloid Tin Cluster {Sn10[Si(SiMe3)3]4}2−: Ligand Elimination versus Coordination Chemistry

Chemistry that uses metalloid tin clusters as a starting material is of fundamental interest towards understanding the reactivity of such compounds. Since we identified {Sn₁₀[Si(SiMe₃)₃]₄}^2? 7 as an ideal candidate for such reactions, we present a further step in the understanding of metalloid tin cluster chemistry. In contrast to germanium chemistry, ligand elimination seems to be a major reaction channel, which leads to the more open metalloid cluster {Sn₁₀[Si(SiMe₃)₃]₃}^? 9 , in which the Sn core is only shielded by three Si(SiMe₃)₃ ligands. Compound 9 is obtained through different routes and is crystallised together with two different countercations. Besides the structural characterisation of this novel metalloid tin cluster, the electronic structure is analysed by ¹¹⁹Sn Mössbauer spectroscopy. Additionally, possible reaction pathways are discussed. The presented first step into the chemistry of metalloid tin clusters thus indicates that, with respect to metalloid germanium clusters, more reaction channels are accessible, thereby leading to a more complex reaction system.     

Crystallization of the mesomorphic form and control of the molecular structure for tailoring the mechanical properties of isotactic polypropylene

The combination of the control of the concentration of stereodefects in isotactic polypropylene using metallocene catalysts and the crystallization via the mesophase is a strategy to tailor the mechanical properties. Stiff materials, flexible materials, and thermoplastic elastomers can be produced depending only on the concentration of rr stereodefects. Modulus, ductility, and strength can be modulated through the crystallization of α and γ forms or of the mesophase. Different morphologies are observed depending on the stereoregularity and conditions of crystallization. Crystals of the mesomorphic form always exhibit a nodular morphology, accounting for the similar good deformability of all quenched samples, whatever the concentration of stereodefects. The mesophase transforms by thermal treatments into the α form preserving the nodular morphology, with increase of strength while maintaining the ductility typical of the mesophase. Annealing of the mesophase permits a precise adjustment of crystallinity and size of nodular crystals offering additional options to modify the mechanical properties. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 677–699     

Unraveling the Degradation Mechanism of Purine Nucleotides Photosensitized by Pterins: The Role of Charge‐Transfer Steps

Photosensitized reactions contribute to the development of skin cancer and are used in many applications. Photosensitizers can act through different mechanisms. It is currently accepted that if the photosensitizer generates singlet molecular oxygen (¹O₂) upon irradiation, the target molecule can undergo oxidation by this reactive oxygen species and the reaction needs dissolved O₂ to proceed, therefore the reaction is classified as ¹O₂‐mediated oxidation (type II mechanism). However, this assumption is not always correct, and as an example, a study on the degradation of 2′‐deoxyguanosine 5′‐monophosphate photosensitized by pterin is presented. A general mechanism is proposed to explain how the degradation of biological targets, such as nucleotides, photosensitized by pterins, naturally occurring ¹O₂ photosensitizers, takes place through an electron‐transfer‐initiated process (type I mechanism), whereas the contribution of the ¹O₂‐mediated oxidation is almost negligible.