Infeasible/feasible search trajectories and directional rounding in integer programming

The notion that strategies in non-linear and combinatorial optimization can benefit by purposefully and systematically navigating between feasible and infeasible space has been around for many years, but still is sometimes dismissed as having little relevance for creating more effective methods. To reinforce the case on behalf of approaches that endorse infeasible/feasible search trajectories, it is possible to formulate simple theorems disclosing useful properties of such trajectories in the context of integer programming. These results motivate a closer examination of integer programming search processes based on directional rounding processes, including a special variant called conditional directional rounding. From these foundations a variety of new strategies emerge for exploiting connections between feasible and infeasible space.     

Evidence for proton ground state correlations in48Ca

In a high resolution⁴⁸Ca(d,³He) experiment at 80 MeV evidence has been found for a 7/2^? state at 1.97 MeV in⁴⁷K with a spectroscopic factor of C²S=0.08 corresponding to a ~4% admixture of πf²(s,d)^?2 configurations in the ground state of Ca.     

Isatin (indole-2,3-dione) in urine and tissues. Detection and determination by gas chromatography-mass spectrometry

A simple procedure based upon capillary column gas chromatography-mass spectrometry (GC-MS) is described for the detection and determination of isatin (indole-2,3-dione) in body fluids and tissues. After addition of 5-methylisatin as internal standard to urine or tissue homogenates, organic extracts are dried and derivatized successively with hydroxylamine hydrochloride and the reagent N-tert.-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA). The tert.-butyldimethylsilyl derivatives obtained show good GC-MS properties and allow quantification by selected-ion monitoring of m/z 333 (isatin) and m/z 347 (internal standard). Adult and newborn human urine output values lie in the ranges 0.4-3.2 mg/mmol of creatinine (5-30 mg per 24 h) and 0.002-0.518 mg/mmol of creatinine, respectively. There is a discontinuous regional distribution in rat tissues. The GC-MS properties of a number of derivatives formed by successive reaction of isatin with hydroxylamine hydrochloride (or methoxyaminehydrochloride or ethoxyamine hydrochloride) and MTBSTFA, bis(trimethylsiyl)trifluoroacetamide, pentafluoropropionic anhydride or pentafluorobenzyl bromide are also described.     

A novel high temperature 1H NMR imaging probe for combustion studies: the behaviour of both a lit and unlit methane gas jet

The design of a NMR probe suitable for very high temperature samples is described. The loop gap resonator is water cooled and tuned to 100 MHz for use in a 2.4 T horizontal bore magnet. The probe has been specifically designed for imaging of the combustion process. An experiment is described in this paper which shows the behaviour of a methane gas jet when both lit and unlit. The jet of gas may be observed in its unlit state flowing at up to 2 ms(-1) from a 1 mm diameter orifice using a Single Point Imaging technique. Images of the lit gas show loss of nuclear polarisation within 3 mm of the orifice. A residual amount of un-decomposed gas is visible in the first few millimetres of the flame neck. A computational fluid dynamics model is used to verify the distribution of molecular methane, as well as the temperature of the flame.     

Double folding model analysis of 7Li scattering

Elastic scattering angular distributions have been measured for the scattering of ⁷Li by ⁴⁴Ca, ⁵⁶Fe and ^{58, 60}Ni at $\text{E(}{}^7\text{Li}\text{) = 34}\text{MeV}$. These data are well described by the optical model using volume Woods-Saxon potentials. These and previously measured ⁷Li scattering data also have been analyzed with a double-folding real potential which employs the nucleon-nucleon potential of Bertsch et al. The overall best fit to the experimental data down to σ/σ_R ~ 10^?3 is obtained when the DF potential is multiplied by approximately 0.6. However, the best fit for the peripheral data alone (σ/σ_R ～ 10^?1 is obtained without any renonnalization.     

Oxidative reactions of azines

Oxidative coupling of 1-alkyl(benzyl)-4-(γ-pyridyl)-1,2,5,6-tetrahydropyridines with acetone in the presence of KMnO₄ follows two pathways and yields both 1-R-2-(acetylmethylene)tetrahydropyridines and 1-R-3,4-dihydroxypiperidin-2-ones. When acetonitrile is used instead of acetone, the reaction under similar conditions occurs as selective ketodihydroxylation of the starting piperideines yielding 1-R-3,4-dihydroxy-4-(γ-pyridyl)piperidin-2-ones. The molecular and crystal structures of one of these products (R=Et) was studied by X-ray diffraction analysis. For part 4, see Ref. 1 Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2020–2023, November, 1997.     

Integrating modeling,algorithm design,and computational implementation to solve a large-scale non-linear mixed integer programming problem

This paper describes the formulation of a nonlinear mixed integer programming model for a large-scale product development and distribution problem and the design and computational implementation of a special purpose algorithm to solve the model. The results described demonstrate that integrating the art of modeling with the sciences of solution methodology and computer implementation provides a powerful approach for attacking difficult problems. The efforts described here were successful because they capitalized on the wealth of existing modeling technology and algorithm technology, the availability of efficient and reliable optimization, matrix generation and graphics software, and the speed of large-scale computer hardware. The model permitted the combined use of decomposition, general linear programming and network optimization within a branch and bound algorithm to overcome mathematical complexity. The computer system reliably found solutions with considerably better objective function values 30 to 50 times faster than had been achieved using general purpose optimization software alone. Throughout twenty months of daily use, the system was credited with providing insights and suggesting strategies that led to very large dollar savings.This research was supported in part by the Office of Naval Research Contract N00014-78-C-0222, by the Center for Business Decision Analysis, by the University of Texas at Austin, and by the David Bruton, Jr., Centennial Chair in Business Decision Support Systems. Reproduction in whole or in part is permitted for any purpose of the U.S. Government.Center for Business Decision Analysis, Graduate School of Business — GSB 3.126, University of Texas, Austin, Texas 78712, USA.     

On the Farrell cohomology of mapping class groups

Oblatum 31-X-1991 & 24-II-1992     

Logical testing for rule-base management

We present a procedure to logically reduce simple implications that comprise the rule-base of an expert system. Our method uses topological sorting on a digraph representation that detects logical inconsistency and circular reasoning in linear-time. Then, the sort order provides an efficient method to detect and eliminate forced values and redundant rules. We consider additional diagnostic aids for the rule-base manager, notably how to range the number of propositions that could be true and how to consolodate the rule-base. We than show how the simple case may be extended to logically test a general rule-base with a decomposition principle.