1-(2,4,6-Triisopropyl­phen­yl)ethanone

The title compound, C17H26O, is a di-ortho-alkyl substituted phenyl ethanone that exhibits a significant twisting of the ketone fragment relative to the aromatic ring [O—C—C—C torsion angle = 89.32 (17)°] due to steric pressure from the ortho-isopropyl groups. One ortho- and the para-isopropyl group exhibit orientational disorder with a refined site occupancy factor of 0.562 (3):0.438 (3)

1,3-Bis(2,6-diisopropyl­phen­yl)-4,5-dihydro-1H-imidazol-3-ium triiodide

In the crystal structure of the title compound, C27H39N2 +·I3 −, the imidazolidinium ring is perpendicular to a mirror plane which bis­ects the cation. The dihedral angle between the imidazolidinium ring and the benzene ring is 89.0 (2)°. The triiodide anion also lies on a mirror plane and is almost linear with an I—I—I bond angle of 178.309 (18)°

Linear position-sensitive x-ray detector incorporating a self-scanning photodiode array

A linear position-sensitive x-ray detector for x-ray spectroscopy and diffraction applications has been tested which can provide excellent spatial resolution, wide dynamic range and good sensitivity. The heart of the system is a self-scanning, photosensitive silicon diode array. It is interfaced via fiber optics to a thin layer of ZnS which fluoresces visible light upon absorption of x-radiation. The conversion to visible light and optical coupling provide several-fold gain in the efficiency of detection as compared to the direct detection of x-ray by the diode array. Equally important is that the array is protected from irreversible damage by high energy radiation, a limitation which previously hindered this application of silicon diode technology

Mission to a comet - Preliminary scientific objectives and experiments for use in advanced mission studies

Scientific objectives and experiments for comet missio

Long-Term Population Variability in the Palila, An Endangered Hawaiian Honeycreeper

Annual surveys of the entire range of the endangered Palila (Loxioides bailleui Oustalet) on Mauna Kea, Hawai'i, were conducted during 1980-1995. The majority of the Palila population was found on the southwestern slope of Mauna Kea near Pu'u La'au, and the range of Palila has not changed since 1975. The Palila population was highly variable. Mean population size during 1980-1995 was 3390 ± 333 SE, but the population ranged from 1584 ± 324 in 1985 to 5685 ± 535 in 1981. Population size outside the population center near Pu'u La'au has decreased significantly since 1980

Complexity Characterization in a Probabilistic Approach to Dynamical Systems Through Information Geometry and Inductive Inference

Information geometric techniques and inductive inference methods hold great promise for solving computational problems of interest in classical and quantum physics, especially with regard to complexity characterization of dynamical systems in terms of their probabilistic description on curved statistical manifolds. In this article, we investigate the possibility of describing the macroscopic behavior of complex systems in terms of the underlying statistical structure of their microscopic degrees of freedom by use of statistical inductive inference and information geometry. We review the Maximum Relative Entropy (MrE) formalism and the theoretical structure of the information geometrodynamical approach to chaos (IGAC) on statistical manifolds. Special focus is devoted to the description of the roles played by the sectional curvature, the Jacobi field intensity and the information geometrodynamical entropy (IGE). These quantities serve as powerful information geometric complexity measures of information-constrained dynamics associated with arbitrary chaotic and regular systems defined on the statistical manifold. Finally, the application of such information geometric techniques to several theoretical models are presented.Comment: 29 page