Equilibrium and pre-equilibrium emissions in proton-induced reactions on <Superscript>203,205</Superscript>Tl

In this study, the excitation functions for the reactions ²⁰³Tl(p, n)²⁰³Pb, ²⁰⁵Tl(p, 3n)²⁰³Pb, ²⁰³Tl(p, 2n)²⁰²Pb, ²⁰⁵Tl(p, 4n)²⁰²Pb, ²⁰³Tl(p, 3n)²⁰¹Pb, ²⁰⁵Tl(p, 5n)²⁰¹Pb, ²⁰³Tl(p, 4n)²⁰⁰Pb and ²⁰⁵Tl(p, 6n)²⁰⁰Pb have been calculated using pre-equilibrium and equilibrium reaction mechanisms. Calculated results based on hybrid model, geometry-dependent hybrid model and cascade-exciton model have been compared with the experimental data.      

Optical switching between bistable soliton states: a theoretical review

In this paper we summarize what is currently known about optical switching between bright bistable soliton states in one and higher dimensions. A guideline to selecting media with appropriate intensity-dependent refractive indices to support bistable solitary waves is presented. The stability criterion for robustness of the solitary waves is discussed. Finally, some methods and numerical examples of optical switching are presented.     

Synthesis and characterization of polymers produced by horseradish peroxidase in dioxane

Polymers were synthesized from substituted phenolic and aromatic amine compounds with hydrogen peroxide as the source of an oxidizing agent and horseradish peroxidase enzyme as the catalyst. The polymerization reaction was carried out in a monophasic organic solvent with small amounts of water at room temperature. Conditions for the synthesis of polymers with respect to reaction time and yield were studied with a number of monomers at different concentrations and in solvents with different buffers with pH range of 5.0–7.5. Physical and chemical properties of these homo-and copolymers were determined with respect to melting point, solubility, elemental analysis, molecular weight distribution, infrared absorption (including FTIR), solid-state ¹³C nuclear magnetic resonance, thermal gravimetric analysis, and differential scanning calorimetry. The enzyme catalyzed reactions produced polymers of molecular weight greater than 400,000 which were further fractionated by differential solubility in solvent mixtures and the molecular weight distribution of the polymer fractions were determined. In general, the polymers synthesized have low solubilities, high melting points, and some degree of branching.     

Sideward flow in Au+Au collisions between 2A and 8A GeV

Using the large acceptance Time Projection Chamber of experiment E895 at Brookhaven, measurements of collective sideward flow in Au+Au collisions at beam energies of 2A, 4A, 6A, and 8A GeV are presented in the form of in-plane transverse momentum and the first Fourier coefficient of azimuthal anisotropy v(1). These measurements indicate a smooth variation of sideward flow as a function of beam energy. The data are compared with four nuclear transport models which have an orientation towards this energy range. All four exhibit some qualitative trends similar to those found in the data, although none show a consistent pattern of agreement within experimental uncertainties.     

Phycobiliproteins encapsulated in sol-gel glass

Light transducing phycobiliproteins are encapsulated in optically transparent sol-gel matrices. Absorption and fluorescence spectroscopies are used to characterize the effect of the sol-gel encapsulation on the conformation and aggregation states of the three major phycobiliproteins present in phycobilisomes: phycoerythrin, phycocyanin, and allophycocyanin. It is found that the effects of sol-gel entrapment on the spectroscopic properties are significantly different for the three phycobiliproteins. The results indicate that phycoerythrin undergoes only minor change in its native structure when entrapped in sol-gel. However, significant changes in conformation and aggregation state occur when phycocyanin and allophycocyanin are entrapped in sol-gel matrices. A thin film of sol-gel encapsulated phycoerythrin is also coated on an optical fiber surface and strong fluorescence from the evanescent wave excitation is detected. The potential applications of sol-gel encapsulated phycobiliproteins in biosensors are discussed.     

A New Algorithm for Solving the Word Problem in Braid Groups

One of the most interesting questions about a group is whether its word problem can be solved and how. The word problem in the braid group is of particular interest to topologists, algebraists, and geometers, and is the target of intensive current research. We look at the braid group from a topological point of view (rather than a geometric one). The braid group is defined by the action of diffeomorphisms on the fundamental group of a punctured disk. We exploit the topological definition in order to give a new approach for solving its word problem. Our algorithm, although not better in complexity, is faster in comparison with known algorithms for short braid words, and it is almost independent of the number of strings in the braids. Moreover, the algorithm is based on a new computer presentation of the elements of the fundamental group of a punctured disk. This presentation can be used also for other algorithms.     

μ+SR frequency shifts in the van‐Vleck paramagnet PrIn3

As part of an ongoing μ⁺SR study on cubic van‐Vleck paramagnets of the PrM₃ series ( M\ =\ In,Pb,Tl,Sn), in which the CEF level scheme varies systematically, we present preliminary static μ⁺SR results on a single crystal of PrIn₃. From the angular dependence and from the appearance of the μSR spectra, we could determine that stopped μ⁺ occupy octahedral sites of the (1/2, 0, 0) type, i.e. sites with 2 Pr and 4 In atoms as neighbors. The spectral frequency shifts can be accounted for by assigning to the Pr sites essentially unperturbed 4f dipole moment values, as derived from bulk magnetization measurements. The temperature dependence of the shifts scales to a good accuracy with the bulk susceptibility. It is concluded that unlike previous observations with PrNi₅, the local perturbations induced by an interstitial μ⁺ on the CEF levels of neighboring Pr in the PrIn₃ system are small compared with the unperturbed level splitting itself. This revised version was published online in July 2006 with corrections to the Cover Date.