Interpretation of experiments on resonance γ-ray scattering in crystal sources

It has been shown that the yield of resonance -quanta scattered from a monocrystal can be calculated from the Vineyard model using a Born-Mayer potential function with constants determined from the lattice parameters. The calculated results proved to be in good agreement with experimental data. An anisotropy appeared here, the yield depending on the orientation of the initial pulse with respect to the principal crystallographic axes. It was found necessary to take account of the many-particle interactions experienced by the recoil atoms during movement through the crystal.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, No. 7, pp. 78–82, July, 1971.The authors wish to take the opportunity of thanking V. A. Botvin for a fruitful discussion of the results obtained here, and Yu. M. Nikitushev for aid in carrying out the calculations on the computer.     

Detecting outlying samples in a parallel factor analysis model

To explore multi-way data, different methods have been proposed. Here, we study the popular PARAFAC (Parallel factor analysis) model, which expresses multi-way data in a more compact way, without ignoring the underlying complex structure. To estimate the score and loading matrices, an alternating least squares procedure is typically used. It is however well known that least squares techniques suffer from outlying observations, making the models useless when outliers are present in the data. In this paper, we present a robust PARAFAC method. Essentially, it searches for an outlier-free subset of the data, on which we can then perform the classical PARAFAC algorithm. An outlier map is constructed to identify outliers. Simulations and examples show the robustness of our approach.     

Kindergartners’ Spontaneous Focusing on Numerosity in Relation to Their Number-Related Utterances During Numerical Picture Book Reading

This study investigated the relationship between kindergartners’ Spontaneous Focusing on Numerosity (SFON) and their number-related utterances during numerical picture book reading. Forty-eight 4- to 5-year-olds were individually interviewed via a SFON Imitation Task and a numerical picture book reading activity. We expected differences in the frequency of number-related utterances during picture book reading between children with a higher SFON score, providing more number-related utterances, and children with a lower SFON score. Our results showed large inter-individual differences in both kindergartners’ SFON and the frequency of their number-related utterances during picture book reading, yet SFON was not related to the frequency of number-related utterances. This unexpected result is discussed in terms of its scientific, methodological, and educational implications.     

Flame dynamics and consideration of deflagration-to-detonation transition in central gravitational field

Expanding reaction fronts are central to many terrestrial processes as well as such cosmic phenomena as the thermonuclear combustion in supernovae. While in terrestrial conditions the effect of intrinsic flamefront instabilities is generally believed to be supplementary to, say, external turbulence and chamber dynamics, at the astrophysical scale the role of flamefront instabilities in the flame acceleration is presumably dominant. Moreover, while in terrestrial systems we focus mainly on the hydrodynamic, Darrieus–Landau (DL) instability, the Rayleigh–Taylor (RT), body-force instability could be a key issue for astrophysical flames because of the enormous gravity and the associated large scales. Consequently, if RT effects dominate over DL effects, the globally-spherical flamefront can be replaced by an expanding bubble with a non-spherical shape, possibly that of digit “8”. In the present work we have developed a self-similar formulation describing a globally-spherical expanding flamefront corrugated due to the DL instability in a central gravitation field. The associated scenario of the flame acceleration, the evolution of the upstream flow, and the instant when a gas parcel ahead of the flamefront first explodes, hence initiating the deflagration-to-detonation transition (DDT), as well as the radial coordinate of this parcel, are determined. We have also compared the effects of DL and RT instabilities, estimating whether a globally-spherical, DL-corrugated flamefront is subsequently terminated by the formation of RT bubbles. It is shown how the instant of such a transition and the relevant global flame radius are coupled to various flame and flow parameters.     

Sector spin coating for fast preparation of polymer libraries

The feasibility of sector spin coating (or combinatorial spin-coating) is demonstrated (i.e., spin coating of various samples onto one single substrate using a metal template to divide the substrate into sectors). Film thickness increases in an angular direction against the sense of rotation. In the radial direction, the film thickness is constant within 2%. A library of 8 poly(methyl methacrylate)/polystyrene-blends with varying composition was spin coated and subsequently analyzed using automated atomic force microscopy: 24 measurements could be performed within 72 min. The contact angles of a library of 16 polyoxazoline diblock copolymers were measured using one substrate with 16 spin-coated sectors. Forty-eight measurements could be performed within 50 min. On the basis of the surface energies calculated using the Owens-Wendt-Rath-Kaeble method, the library can be divided into three groups of polymers: those containing a dispersive nonyloxazoline block, those containing a polar phenyloxazoline block, and those containing neither.     

Synthesis of Fluorinated Dienes by Palladium‐Catalyzed Coupling Reactions

The synthesis of partly fluorinated 1,3‐ and 1,4‐dienes by palladium‐catalyzed coupling makes these compounds available on the laboratory scale. Several catalyst systems were tested to maximize the yields and minimize the by‐products. The molecular structures of 1,1,2,4,4‐pentafluorobutadiene, chloro(N,N′‐tetramethylethylenediamine)(trifluorovinyl)zinc, PCy₂R, and P(O)Cy₂R (Cy=cyclohexyl, R=2‐(1‐naphthyl)phenyl) were elucidated by X‐ray crystallography.