Sheet-beam geometry for in vivo fluorescent x-ray computed tomography: proof-of-concept experiment in molecular imaging

We propose a fluorescent x-ray computed tomography method using an array of detectors with an incident sheet beam, aimed at providing molecular imaging with high sensitivity and good spatial resolution. In this study, we prove the feasibility of this concept and investigate its imaging properties, including spatial and contrast resolutions and quantitativeness, by imaging an acrylic phantom and a normal mouse brain using a preliminary imaging system with monochromatic synchrotron x rays.     

DNA microarray technology used for studying foodborne pathogens and microbial habitats: minireview

Microarray analysis is an emerging technology that has the potential to become a leading trend in bacterial identification in food and feed improvement. The technology uses fluorescent-labeled probes amplified from bacterial samples that are then hybridized to thousands of DNA sequences immobilized on chemically modified glass slides. The whole gene or open reading frame(s) is represented by a polymerase chain reaction fragment of double-strand DNA, approximately 1000 base pair (bp) or 20-70 bp single-strand oligonucleotides. The technology can be used to identity bacteria and to study gene expression in complex microbial populations, such as those found in food and gastrointestinal tracts. Data generated by microarray analysis can be potentially used to improve the safety of our food supply as well as ensure the efficiency of animal feed conversion to human food, e.g., in meat and milk production by ruminants. This minireview addresses the use of microarray technology in bacterial identification and gene expression in different microbial systems and in habitats containing mixed populations of bacteria.     

Stabilization of nonlinear systems with a dither control

In this paper a new approach is taken to analyze stabilization of a general nonlinear system with a dither input. Given the original system with a control, an autonomous relaxed system is constructed. It is shown that if the relaxed system is stable, then the original system with dither control would be stable in the finite time. An algorithm is given for constructing the dither control. The technique used here is general and does not have the limitations of the Dual Input Describing Function technique. Furthermore, in many cases it is possible to guarantee global contractive stability as well. Two examples are solved in detail using computer simulations for demonstration of the technique.     

Managing Stochastic,Finite Capacity,Multi-Project Systems through the Cross-Entropy Methodology

This paper addresses the problem of loading a finite capacity, stochastic (random) and dynamic multi-project system. The system is controlled by keeping a constant number of projects concurrently in the system. A new approach, based on the Cross-Entropy (CE) method, is proposed to determine optimal loading of the system. Through numerical experiments, we demonstrate the CE method performance and show new insights into its behavior in a noisy system. Particularly, we suggest a trade-off between the convergence time, the number of iterations and the noise level. This research was partially supported by the Inga and Hal Marcus Research Fund     

Nitrogen fixation: Part I. Electrochemical reduction of titanium compounds in the presence of catechol and N2 in MeOH or THF

The cyclic voltammetry of Cp₂TiCl₂ was studied in both MeOH and THF, at either glassy carbon or platinum electrodes. The effect of catechol added, as a complexation agent, on the shape of the voltammograms is also described. Controlled potential electrolysis (CPE) was employed to reduce CP₂TiCl₂ under an N₂ atmosphere in the presence of catechol. Ammonia was formed in low chemical yields (up to 0.11%), but selectively. The reduction was also investigated in the presence of a base (MeONa) and divalent cation (Mg²⁺). The ammonia yield increased to 0.65% and 1.45%, respectively. Other titanium compounds ((acac)₂TiCl₂, (i-PrO)₄Ti, TiCl₄, TiCl₃) were reduced under similar conditions and found to be less efficient for N₂ reduction than Cp₂TiCl₂.     

Scattering from non-overlapping potentials. I. General formulation

The problem of scattering from an assembly of non-overlapping spherical potentials is solved in partial-wave basis for each of the constituent potentials. The resulting scattering operator is a quotient of two infinite matrices and depends on “on-shell” partial wave amplitudes of the individual potentials. It suggests in general a truncation scheme which essentially considers only those partial waves effective for each collision at the given energy. The multiple-scattering series is recovered and limiting cases of low energy and high energy are considered. Applications to high-energy scattering of elementary particles on nuclei are briefly discussed.     

Scattering from nonoverlapping potentials. III. Pion elastic scattering on 4He in the 3,3 region

The $\text{π}{}^{\mathrm{?}}{}^4\text{He}$ elastic scattering in the 3,3 resonance region is discussed in the framework of the nonoverlapping potentials model. Single and double scattering terms are considered together with their modification by reflection terms, which allow the projectile to oscillate back and forth an arbitrary number of times within a pair of nucleons. Reflections and spin and isospin flips are found to constitute a determining factor in a qualitative reproduction of the correct shape of observed angular distributions, in particular for backward scattering angles. Reflections are probably unimportant in πd scattering.