Amperometric immunosensor for the detection of Vibrio cholerae O1 using disposable screen-printed electrodes.

A disposable amperometric immunosensor was studied for the rapid detection of Vibrio cholerae (V. cholerae), the causative agent of cholera, employing an indirect sandwich enzyme linked immunosorbent assay (ELISA) principle. Screen-printed electrodes (SPEs) were fabricated (by using commercial and homemade carbon inks), electrochemically characterized and the assay conditions were optimized for capturing antibodies and antigen. Whole cell lysate (WCL) of V. cholerae was used to raise antibodies in rabbits and mice. The antibodies raised against WCL of V. cholerae were found to be specific, and no cross reactivity was observed with other enteric bacteria. 1-Naphthyl phosphate was used as a substrate with the amperometric detection of its enzymatic hydrolysis product 1-naphthol at a potential of +400 mV vs. Ag/AgCl reference electrode. A comparison between the amperometric detection technique and the standard ELISA was made in terms of the total assay time, the amount of biological materials used and the sensitivity of detection. The minimum detection limit of the amperometric immunosensor for V. cholerae was found to be 10(5) cells/ml in 55 min, while ELISA detected 10(6) cells/ml in 4 h.     

A Class of stochastic programs with decision dependent uncertainty

We address a class of problems where decisions have to be optimized over a time horizon given that the future is uncertain and that the optimization decisions influence the time of information discovery for a subset of the uncertain parameters. The standard approach to formulate stochastic programs is based on the assumption that the stochastic process is independent of the optimization decisions, which is not true for the class of problems under consideration. We present a hybrid mixed-integer disjunctive programming formulation for the stochastic program corresponding to this class of problems and hence extend the stochastic programming framework. A set of theoretical properties that lead to reduction in the size of the model is identified. A Lagrangean duality based branch and bound algorithm is also presented. Financial support from the ExxonMobil Upstream Research Company is gratefully acknowledged.     

Using diversification,communication and parallelism to solve mixed-integer linear programs

Performance variability of modern mixed-integer programming solvers and possible ways of exploiting this phenomenon present an interesting opportunity in the development of algorithms to solve mixed-integer linear programs (MILPs). We propose a framework using multiple branch-and-bound trees to solve MILPs while allowing them to share information in a parallel execution. We present computational results on instances from MIPLIB 2010 illustrating the benefits of this framework.     

Nonnegative matrices having same nonnegative moore-penrose and group inverses

Nonnegative matrices A whose Moore-Penrose generalized inverse A⁺ is nonnegative and has any one of the three equivalent properties (i) AA⁺ = A⁺A (ii) A⁺ = A, the group inverse, (iii) A⁺ = p(A), some polynomial in A with scalar coefficients, are characterized. This characterization generalizes known results on nonnegative matrices Awhose Moore-Penrose generalized inverse is equal to some power of A.     

Conditions Implying Closedness (Openness) and Perfectness of Maps

Analogues, generalizations and simplifications of theorems of Arkhangelski [1], Bourbaki [3] and Fuller [6] are given.     

Nuclear capture of Σ− hyperons

The capture at rest of Σ^? hyperons in emulsion nuclei is studied through Monte-Carlo simulation. The Λ^o trapping probability following Σ^? capture is estimated and compared with the corresponding probability following K^? capture. The difference in the two probabilities is explained in terms of the dissimilar energy distributions of the Λ^o hyperons produced from the captures of Σ^? hyperons and K^? mesons. Information obtained on the features of the Σ^? capture star and on the characteristics of the hyperfragments produced from Σ^? captures is presented.     

Electroproduction of neutral pions at energies above the resonance region

The reaction e p→e'pπ⁰ has been measured at W=2.55 GeV a fixed electron scattering angle of 10.3°. Two magnetic spectrometers and a lead glass hodoscope were used to detect all four final state particles. Electroproduction cross sections in the t range ?0.15 to ?1.4 (GeV/c)² at q² = ?0.22, ?0.55 and ?0.85 (GeV/c)² are presented. Above |t|=0.6 (GeV/c)² the cross sections are considerably smaller than those for photoproduction.     

An improved synthesis of anticancer benzothiopyranoindazoles. An efficient large-scale β-aminoethylation procedure

Improved processes for the synthesis of bulk quantities of the benzothiopyranoindazole clinical agent CI-958 and A-ring congeners is reported. The process chosen for scale-up operations achieves β-aminoethylation of an anilino precursor via a three-step sequence (acylation, reduction, deprotection) starting from N-(trityl)glycine. Detailed analytical data are reported for the target compounds and most intermediates, and detailed spectroscopy is given for CI-958.