Investigations of excitation energy transfer and intramolecular interactions in a nitrogen corded distrylbenzene dendrimer system.

The photophysics of an amino-styrylbenzene dendrimer (A-DSB) system is probed by time-resolved and steady state luminescence spectroscopy. For two different generations of this dendrimer, steady state absorption, emission, and photoluminescence excitation spectra are reported and show that the efficiency of energy transfer from the dendrons to the core is very close to 100%. Ultrafast time-resolved fluorescence measurements at a range of excitation and detection wavelengths suggest rapid (and hence efficient) energy transfer from the dendron to the core. Ultrafast fluorescence anisotropy decay for different dendrimer generations is described in order to probe the energy migration processes. A femtosecond time-scale fluorescence depolarization was observed with the zero and second generation dendrimers. Energy transfer process from the dendrons to the core can be described by a Förster mechanism (hopping dynamics) while the interbranch interaction in A-DSB core was found to be very strong indicating the crossover to exciton dynamics

The diaphoric structure and unity of William Faulkner\u27s Go Down Moses

I have always been fascinated with Faulkner. But I was forever intimidated by his complex artistry and sweeping vision, and my first reading of “The Bear” was a frustrating experience. This oddly disjunct work simply did not make sense to the young undergraduate who then preferred the lucidity of Ernest Hemingway and the grey gloom of Graham Greene. Continued exposure to Faulkner, however, began to transform frustration into cryptic delight until it finally occurred to me that his greatest works were indeed among the greatest works America has ever produced. Nothing would suffice but a major study. But intensive studies of Faulkner\u27s major works abound, and many of them are profoundly insightful and forbiddingly exhaustive works in their own right. So I turned to the neglected area of Faulkner\u27s short fiction where criticism, for some obscure reason, has feared heavily to tread. And there, almost immediately, I discovered Go Down, Moses–to me, a brilliant and uniquely formed novel. There, of course, was “The Bear” once again; but having struggled with the complexities and convolutions of Light in August, The Sound and the Fury, and Absalom, Absalom! in the interim, I found that “The Bear” was no longer quite so prohibiting. I was soon surprised to discover, however, that very few intensive studies of Go Down, Moses exist. Furthermore, very few of those which do exist successfully grapple with all of the “stories” in the “collection,” and even fewer adequately or convincingly explain the unity of the book. And so a dissertation was born. I was immediately compelled to study the original versions of each story included in Go Down, Moses in order to discover if Faulkner reworked those stories for inclusion in Go Down, Moses, and if so, precisely how and why he revised his original materials. To my delight, this study proved singularly worthwhile in that it offered invaluable evidence of Faulkner\u27s aesthetic intentions in Go Down, Moses and firmly substantiated my notion of the book\u27s unity and form

Enhanced heat capacity and a new temperature instability in superfluid He-4 in the presence of a constant heat flux near T-lambda

We present the first experimental evidence that the heat capacity of superfluid 4He, at temperatures very close to the lambda point Tλ, is enhanced by a constant heat flux Q. The heat capacity at constant Q, CQ, is predicted to diverge at a temperature Tc(Q)<Tλ at which superflow becomes unstable. In agreement with previous measurements, we find that dissipation enters our cell at a temperature, TDAS(Q), below the theoretical value, Tc(Q). We argue that TDAS(Q) can be accounted for by a temperature instability at the cell wall, and is therefore distinct from Tc(Q). The excess heat capacity we measure has the predicted scaling behavior as a function of T and Q, but it is much larger than predicted by current theory