A Remark on Real Parameter Global Bifurcation

We study the nonlinear eigenvalue problem F(x,) = L()x +R(x,) = 0 where F : X × R X with X a Hilbert space. IfL() is a polynomial in , then it is shown that 0> 0 is a global bifurcation point of the eigenvalue problem provided astandard transversality condition is satisfied, the dimension of the nullspace of L(0) is an odd number and L() is composed of asequence of positive operators on the finite dimensional null space ofL(0).     

Reference Bands for Nonparametrically Estimated Link Functions

Abstract

We explore the shape of the link function in a generalized linear model by estimating the link nonparametrically. We consider the problem of comparing the nonparametrically estimated link with a particular link function. Using reference bands that consist of pointwise confidence intervals for the nonparametrically estimated link centered at the hypothesized parametric link, simple graphical methods are obtained for comparing the two link functions. The resulting diagnostic plots are demonstrated with both artificial and real examples.     

Micro-electro-mechanical deformable mirrors for aberration control in optical systems

Controlling optical aberrations is one of the enduring problems in optics. Recent advances in adaptive optics for astronomical applications have shown the promise of adaptive optics technology for controlling aberrations. Micro-electro-mechanical deformable mirrors (MEM-DMs) offer an alternative to conventional adaptive optics which, due to the inexpensive nature of MEM-DM technology, will enable a wide range of commercial and scientific applications for optical wave front control. In this paper we describe MEM-DMs, present results of modelling the performance of an MEM-DM for optical aberration control, and present results of experiments to verify that MEM-DMs can control optical aberrations.     

AM1 molecular orbital studies of the structures,conformations, protonation energies,and electronic properties of triazine dihydrofolate reductase inhibitors

The structural, conformational, and electronic properties of three triazine antifolates were determined by AM1 molecular orbital calculations, and the results were compared with other theoretical studies and with X-ray crystallographic studies of these and similar triazines both in the crystalline state and as complexes bound to dihydrofolate reductase. Calculated protonation energies confirm crystal structure data indicating N-protonation analogous to that reported for MTX in similar environments. Overall, the calculated structural and conformational properties are in good agreement with X-ray crystallographic results for these and similar triazines as found in the crystalline state and in enzymebound ternary complexes. However, for one triazine AM1 predicts a conformation with the bulky aromatic substituent twisted about 60° away from coplanarity with the triazine ring, in contrast to the nearly coplanar conformation found in the crystalline state. Intermolecular interactions favoring the coplanar conformation may thus be operative in the crystalline environment. The unique conformational preferences and greater conformation flexibility of triazines in general and of this triazine in particular may provide a key to understanding their biological activity.     

Flow-resonant sound interaction in a duct containing a plate,part I: Semi-circular leading edge

The interaction between flow and flow-induced acoustic resonances near rigid plates with semi-circular leading edges located in a hard-walled duct is described. These plates generate acoustic resonances over flow velocity ranges depending on thickness, chord and trailing edge geometry, together with rigidity, internal dimensions, length of the working section and shape of the terminations of the working section. A potential flow model for the plate with a smooth leading edge is developed, and the acoustic power generated by vortices growing and shedding from the trailing edge is calculated. The rate of growth of the vortices is determined by an instantaneous Kutta condition applied over part of the cycle. This technique simulates the influence of the sound field on vortex growth.     

Determination of uranium metal concentration in irradiated fuel storage basin sludge using selective dissolution

Irradiated uranium metal fuel was stored underwater in the K East and K West storage basins at the US Department of Energy Hanford Site. The uranium metal under damaged cladding reacted with water to generate hydrogen gas, uranium oxides, and spalled uranium metal particles which intermingled with other particulates to form sludge. While the fuel has been removed, uranium metal in the sludge remains hazardous. An expeditious routine method to analyze 0.03 wt% uranium metal in the presence of >30 wt% total uranium was needed to support safe sludge management and processing. A selective dissolution method was designed based on the rapid uranium oxide dissolution but very low uranium metal corrosion rates in hot concentrated phosphoric acid. The uranium metal-bearing heel from the phosphoric acid step then is rinsed before the uranium metal is dissolved in hot concentrated nitric acid for analysis. Technical underpinnings of the selective dissolution method, including the influence of sludge components, were investigated to design the steps and define the reagents, quantities, concentrations, temperatures, and times within the selective dissolution analysis. Tests with simulant sludge proved the technique feasible. Tests with genuine sludge showed a 0.0028 ± 0.0037 wt% (at one standard deviation) uranium metal analytical background, a 0.011 wt% detection limit, and a 0.030 wt% quantitation limit in settled (wet) sludge. In tests using genuine K Basin sludge spiked with uranium metal at concentrations above the 0.030 wt% ± 25 % (relative) quantitation limit, uranium metal recoveries averaged 99.5 % with a relative standard deviation of 3.5 %.