Synthetic aperture interferometry: in-process measurement of aspheric optics

A scanning probe consisting of a source and receive fiber pair is used to measure the phase difference between wave fronts scattered from the front and rear surfaces of an aspheric optic. This system can be thought of as a classical interferometer with an aperture synthesized from the data collected along the path of the probe. If the form of either surface is known, the other can be deduced. In contrast with classical interferometers, the method does not need test or null plates and has the potential to be integrated into the manufacturing process.     

Monte Carlo and discrete-ordinate simulations of irradiances in the coupled atmosphere-ocean system

We compare Monte Carlo (MC) and discrete-ordinate radiative-transfer (DISORT) simulations of irradiances in a one-dimensional coupled atmosphere-ocean (CAO) system consisting of horizontal plane-parallel layers. The two models have precisely the same physical basis, including coupling between the atmosphere and the ocean, and we use precisely the same atmospheric and oceanic input parameters for both codes. For a plane atmosphere-ocean interface we find agreement between irradiances obtained with the two codes to within 1%, both in the atmosphere and the ocean. Our tests cover case 1 water, scattering by density fluctuations both in the atmosphere and in the ocean, and scattering by particulate matter represented by a one-parameter Henyey-Greenstein (HG) scattering phase function. The CAO-MC code has an advantage over the CAO-DISORT code in that it can handle surface waves on the atmosphere-ocean interface, but the CAO-DISORT code is computationally much faster. Therefore we use CAO-MC simulations to study the influence of ocean surface waves and propose a way to correct the results of the CAO-DISORT code so as to obtain fast and accurate underwater irradiances in the presence of surface waves.     

Analysis of protein adsorption and binding at biosensor polymer interfaces using X-ray photon spectroscopy and scanning electrochemical microscopy

We describe a method, based on X-ray photoelectron spectroscopy (XPS) measurements, to assess the extent of protein adsorption or binding on a variety of different muTAS and biosensor interfaces. Underpinning this method is the labeling of protein molecules with either iodine- or bromine-containing motifs by using protocols previously developed for radiotracer studies. Using this method, we have examined the adsorption and binding properties of a variety of modified electrodeposited polymer interfaces as well as other materials used in muTAS device fabrication. Using polymer interfaces modified with poly(propylene glycol) (PPG) chains, our results indicate that a chain of at least approximately 30 monomer units is required to inhibit nonspecific adsorption from concentrated protein solutions. The XPS methodology was also used to probe specific binding of avidins and enzyme conjugates thereof to biotinylated and mixed biotin/PPG-modified polymer interfaces. In one example, using competitive binding, it was established that the mode of binding of a peroxidase-streptavidin conjugate to a biotinylated modified polymer interface was primarily via the streptavidin moiety (as opposed to nonspecific binding via the enzyme conjugate). XPS evaluation of nonspecific and specific peroxidase-streptavidin immobilization on various functionalized polymers has guided the design and fabrication of functionalized interdigitated electrodes in a biosensing muTAS device. Subsequent characterization of this device using scanning electrochemical microscopy (SECM) corroborated the adsorption and binding previously inferred from XPS measurements on macroscale electrodes.     

Principal Rings and their Invariant Factors

In this article we put forward a new look at the theory of principal and Invariant-Factor rings, with a view toward facilitating the formalization, automation, and archiving of results and their proofs. We take an elementary and constructive approach: standard techniques such as prime ideals and factorization of elements are avoided, and determinant constructions are minimized. Using such computationally friendly methods, the main existence and uniqueness results on invariant factors for a f.g. torsion module are derived, and several new algebraic constructions and results are found. The lattice of principal integral ideals for any commutative Bézoutian ring is explicitly constructed based on a first-order proof overlooked in the literature, together with a proof that this lattice is distributive. A Lagrange quotient theorem for finitely generated modules over any principal ring is stated for the first time. A very constructive new proof is given that a principal ring has the Hermite property, so is also an Invariant-Factor ring. A calculus that is needed in the ideal lattice, naturally yields a number of formulas valid for a function lattice.     

Microwave Initiated Self-Propagating High-Temperature Synthesis of SiC

The use of microwave energy to initiate self-propagating, high-temperature synthesis (SHS) of Si + graphite mixtures has been investigated. The results indicate that, unlike with conventional ignition techniques, green densities in excess of 80% of theoretical can be ignited and the combustion wavefront can be crudely controlled. It was found that the induction time for ignition increased with increasing green density and that a higher microwave power level was required with the denser green pellets to achieve the same ignition time. Combustion front velocity increased with green density. The degree of densification was found to decrease with increasing green density. For a given green density, the degree of densification increased with increasing microwave power. The product contained a significant proportion of ultrafine (36–72 nm diameter) SiC whiskers; despite this, final densities as high as 83.6% of theoretical could be obtained without the use of applied pressure. This compares with the 50% densities obtained via conventional ignition techniques.     

In situ column generation for a cutting-stock problem

Working with an integer bilinear programming formulation of a one-dimensional cutting-stock problem, we develop an ILP-based local-search heuristic. The ILPs holistically integrate the master and subproblem of the usual price driven pattern-generation paradigm, resulting in a unified model that generates new patterns in situ. We work harder to generate new columns, but we are guaranteed that new columns give us an integer linear-programming improvement (rather then the continuous linear-programming improvement sought by the usual price driven column generation). The method is well suited to practical restrictions such as when a limited number of cutting patterns should be employed, and our goal is to generate a profile of solutions trading off trim loss against the number of patterns utilized. We describe our implementation and results of computational experiments on instances from a chemical-fiber company.     

A randomized controlled trial of goal choice interventions for alcohol use disorders among men who have sex with men.

This study tested the efficacy of behavioral treatments for alcohol use disorders (AUD) among men who have sex with men (MSM) and who are at risk for HIV transmission. HIV-negative MSM with current AUD (N = 198) were recruited, offered treatment focused on reducing drinking and HIV risk, and followed during treatment and 12 months posttreatment. Participants (n = 89) accepted treatment and were randomized to either 4 sessions of motivational interviewing (MI) or 12 sessions of combined MI and coping skills training (MI + CBT). Other participants (n = 109) declined treatment but were followed, forming a non-help-seeking group (NHS). MI yielded significantly better drinking outcomes during the 12-week treatment period than MI + CBT, but posttreatment outcomes were equivalent. NHS participants significantly reduced their drinking as well. Service delivery and treatment research implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)