Extending the GGobi pipeline from R

This paper describes progress towards developing a platform for rapid prototyping of interactive data visualizations, using R, GGobi, rggobi and RGtk2. GGobi is a software tool for multivariate interactive graphics. At the core of GGobi is a data pipeline that incrementally transforms data through a series of stages into a plot and maps user interaction with the plot back to the data. The GGobi pipeline is extensible and mutable at runtime. The rggobi package, an interface from the R language to GGobi, has been augmented with a low-level interface that supports the customization of interactive data visualizations through the extension and manipulation of the GGobi pipeline. The large size of the GGobi API has motivated the use of the RGtk2 code generation system to create the low-level interface between R and GGobi. The software is demonstrated through an application to interactive network visualization.     

High‐temperature shock tube study of the reactions CH3 + OH → products and CH3OH + Ar → products

The reaction between methyl and hydroxyl radicals has been studied in reflected shock wave experiments using narrow‐linewidth OH laser absorption. OH radicals were generated by the rapid thermal decomposition of tert‐butyl hydroperoxide. Two different species were used as CH₃ radical precursors, azomethane and methyl iodide. The overall rate coefficient of the CH₃ + OH reaction was determined in the temperature range 1081–1426 K under conditions of chemical isolation. The experimental data are in good agreement with a recent theoretical study of the reaction. The decomposition of methanol to methyl and OH radicals was also investigated behind reflected shock waves. The current measurements are in good agreement with a recent experimental study and a master equation simulation. © 2008 Wiley Periodicals, Inc. 40: 488–495, 2008     

Ein Verfahren zur Bestimmung der Harns?ure

Ohne Zusammenfassung     

Synthesis,photopolymerization, and adhesive properties of new bisphosphonic acid monomers for dental application

Four new monomers, 3‐(N‐methylacrylamido)propylidenebisphosphonic acid, 3‐(N‐propyl‐acrylamido)propylidenebisphosphonic acid, 3‐(N‐hexylacrylamido)propylidenebisphosphonic acid, and 3‐(N‐octylacrylamido)propylidenebisphosphonic acid, have been synthesized in good yields and fully characterized by ¹H, ¹³C, ³¹P NMR, and HRMS. The copolymerization of these monomers with N,N′‐diethyl‐1,3‐bis(acrylamido)propane (DEBAAP) has been investigated with differential scanning calorimetry. These mixtures show a higher reactivity than DEBAAP. New self‐etch dental primers, based on these acrylamide monomers, have been formulated. Dentin shear bond strength measurements have shown that primers based on these bisphosphonic acids assure a strong bond between the tooth substance and a dental composite. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5258–5271, 2009     

Algebraic thinking with and without algebraic representation: a three-year longitudinal study

An Algebraic Thinking Test was given to 116 students aged 12–14, at the end of each of three years. This age span crosses two levels of school in New Zealand. This test assessed their ability to represent compensation in the four arithmetic operations both numerically and with letters for variables. The analyses of these results, together with the results from separate interviews designed to report individual progress of students in the New Zealand Numeracy Project, showed that students who had developed advanced mental strategies for dealing with additive, multiplicative and proportional operations, were the students who were capable of making full use of the alphanumeric symbols of algebra. These results, taken together with earlier studies by the authors, led to a proposal for a “pathway for algebraic thinking” accessible to all students.     

Cutting-plane proofs in polynomial space

Following Chvátal, cutting planes may be viewed as a proof system for establishing that a given system of linear inequalities has no integral solution. We show that such proofs may be carried out in polynomial workspace.Research supported by Sonderforschungsbereich 303 (DFG), Institut für Operations Research, Universität Bonn, FR Germany and by NSF grant ECS-8611841.     

A facile approach toward multicomponent supramolecular structures: selective self-assembly via charge separation

A novel approach toward the construction of multicomponent two-dimensional (2-D) and three-dimensional (3-D) metallosupramolecules is reported. Simply by mixing carboxylate and pyridyl ligands with cis-Pt(PEt(3))(2)(OTf)(2) in a proper ratio, coordination-driven self-assembly occurs, allowing for the selective generation of discrete multicomponent structures via charge separation on the metal centers. Using this method, a variety of 2-D rectangles and 3-D prisms were prepared under mild conditions. Moreover, multicomponent self-assembly can also be achieved by supramolecule-to-supramolecule transformations. The products were characterized by (31)P and (1)H multinuclear NMR spectroscopy, electrospray ionization mass spectrometry, and pulsed-field-gradient spin echo NMR techniques together with computational simulations.     

A simple, sensitive and selective quantum-dot-based western blot method for the simultaneous detection of multiple targets from cell lysates

Quantum dots (Qdots) are fluorescent nanoparticles that have great potential as detection agents in biological applications. Their optical properties, including photostability and narrow, symmetrical emission bands with large Stokes shifts, and the potential for multiplexing of many different colours, give them significant advantages over traditionally used fluorescent dyes. Here, we report the straightforward generation of stable, covalent quantum dot–protein A/G bioconjugates that will be able to bind to almost any IgG antibody, and therefore can be used in many applications. An additional advantage is that the requirement for a secondary antibody is removed, simplifying experimental design. To demonstrate their use, we show their application in multiplexed western blotting. The sensitivity of Qdot conjugates is found to be superior to fluorescent dyes, and comparable to, or potentially better than, enhanced chemiluminescence. We show a true biological validation using a four-colour multiplexed western blot against a complex cell lysate background, and have significantly improved previously reported non-specific binding of the Qdots to cellular proteins.     

In-gel protein N- and C-termini identification and its application for transgenic protein characterization

A new method for the determination of N- and C-termini of a protein isolated in a polyacrylamide gel is introduced. In-gel partial protein hydrolysis by hydrochloric acid is used to generate N- and C-terminal peptides for identification. This new method is complementary to existing techniques. The application of the in-gel protein termini identification technique to the characterization of the transgenic protein diacylglycerol acyltransferase (UrDGAT2A) purified from soybean seeds is also reported here. Both N- and C-termini of UrDGAT2A were successfully identified and the N-terminus was found to be blocked by acetylation. The analysis results of UrDGAT2A and two commercial proteins (bovine serum albumin (BSA) and alcohol dehydrogenase) are used to demonstrate the effectiveness of the method in identifying actual N- and C-termini, terminal truncation and blocking.