17,972 research outputs found
An experimental evaluation of the relative effectiveness of two methods of composition assignments in stimulating ideas
Thesis (Ed.M.)--Boston University, 1947. This item was digitized by the Internet Archive
Harmonic vs. subharmonic patterns in a spatially forced oscillating chemical reaction
The effects of a spatially periodic forcing on an oscillating chemical
reaction as described by the Lengyel-Epstein model are investigated. We find a
surprising competition between two oscillating patterns, where one is harmonic
and the other subharmonic with respect to the spatially periodic forcing. The
occurrence of a subharmonic pattern is remarkable as well as its preference up
to rather large values of the modulation amplitude. For small modulation
amplitudes we derive from the model system a generic equation for the envelope
of the oscillating reaction that includes an additional forcing contribution,
compared to the amplitude equations known from previous studies in other
systems. The analysis of this amplitude equation allows the derivation of
analytical expressions even for the forcing corrections to the threshold and to
the oscillation frequency, which are in a wide range of parameters in good
agreement with the numerical analysis of the complete reaction equations. In
the nonlinear regime beyond threshold, the subharmonic solutions exist in a
finite range of the control parameter that has been determined by solving the
reaction equations numerically for various sets of parameters.Comment: 14 pages, 11 figure
Fourier-Stieltjes algebras of locally compact groupoids
This paper gives a first step toward extending the theory of
Fourier-Stieltjes algebras from groups to groupoids. If G is a locally compact
(second countable) groupoid, we show that B(G), the linear span of the Borel
positive definite functions on G, is a Banach algebra when represented as an
algebra of completely bounded maps on a C^*-algebra associated with G. This
necessarily involves identifying equivalent elements of B(G). An example shows
that the linear span of the continuous positive definite functions need not be
complete. For groups, B(G) is isometric to the Banach space dual of C^*(G). For
groupoids, the best analog of that fact is to be found in a representation of
B(G) as a Banach space of completely bounded maps from a C^*-algebra associated
with G to a C^*-algebra associated with the equivalence relation induced by G.
This paper adds weight to the clues in the earlier study of Fourier-Stieltjes
algebras that there is a much more general kind of duality for Banach algebras
waiting to be explored.Comment: 34 page
Quantum corrections to dynamical holographic thermalization: entanglement entropy and other non-local observables
We investigate the thermalization time scale in the planar limit of the SU(N)
N=4 SYM plasma at strong yet finite 't Hooft coupling by considering its
supergravity dual description, including the full O(alpha'^3) type IIB string
theory corrections. We also discuss on the effects of the leading non-planar
corrections. We use extended geometric probes in the bulk which are dual to
different non-local observables in the N=4 SYM theory. This is carried out
within the framework of dynamical holographic thermalization.Comment: 19 pages, 4 figures. V2: References added, 1 figure added, 1 figure
corrected, enlarged discussions about extended probes, typos corrected.
Published versio
Criteria for beach nourishment: biological guidelines for sabellariid worm reef
It has been the purpose of this project to provide the basic biological and geological data together with summary guidelines which will allow the Florida Dept. of Environmental Regulation and project engineers to make the necessary permitting and design decisions for beach nourishment project in worm reef areas. The present work
seeks to determine the tolerance of P. lapidosa to
sediment burial, the tolerance of these organisms to exposure to hydrogen sulfide, the tolerances of these organisms to heavy silt loads in the water, etc. (37pp.
Characterization of Translocation Contact Sites Involved in the Import of Mitochondrial Proteins
Import of proteins into the mitochondrial matrix requires translocation across two membranes. Translocational intermediates of mitochondrial proteins, which span the outer and inner membrane simultaneously and thus suggest that translocation occurs in one step, have recently been described (Schleyer, M., and W. Neupert, 1985, Cell, 43:339-350). In this study we present evidence that distinct membrane areas are involved in the translocation process. Mitochondria that had lost most of their outer membrane by digitonin treatment (mitoplasts) still had the ability to import proteins. Import depended on proteinaceous structures of the residual outer membrane and on a factor that is located between the outer and inner membranes and that could be extracted with detergent plus salt. Translocational intermediates, which had been preformed before fractionation, remained with the mitoplasts under conditions where most of the outer membrane was subsequently removed. Submitochondrial vesicles were isolated in which translocational intermediates were enriched. Immunocytochemical studies also suggested that the translocational intermediates are located in areas where outer and inner membranes are in close proximity. We conclude that the membrane-potential-dependent import of precursor proteins involves translocation contact sites where the two membranes are closely apposed and are linked in a stable manner
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