Reactions of stereochemically rigid diisocyanides with manganese carbonyl derivatives

The reactions of BrMn(CO)₅ with the non-chelating stereochemically rigid bidentate ligands (L-L) 1,3-, and 1,4-diisocyanobenzene, 4,4′-diisocyanobiphenyl, and 4,4′-diisocyanodiphenylmethane afford well characterized complexes of the types BrMn(CO)₄(L-L), BrMn(CO)₃(L-L)₂, and [BrMn(CO)₄]₂(L-L). Similar reactions with [RC₅H₄Mn(CO)₂NO]⁺PF₆⁻ gave mixtures of oligomers of the type [(RC₅H₄MnNO)_n(L-L)_n+1]ⁿ⁺[PF₆⁻]_n.     

Monetary aspects of acquiring technology for price discrimination of a perishable storable product

The remaining shelf-life of perishable storable products can become an additional source of volatility among consumers and a matter for price discrimination. Two models are presented. Both models assume the retailer has the information about consumers’ sensitivity to the remaining shelf-life (eg, their purchasing history). Only the first assumes the retailer has also the technology for price discrimination. An optimal solution for each model is analytically obtained and a numerical example that illustrates the significance is introduced. Numerical illustration indicates that a policy of identical prices for all based on accurate information about consumer sensitivity to remaining shelf-life results in a profit that is just slightly smaller per unit of time compared with the price discrimination policy. Opposing, the numerical illustration also indicates significant difference between the models with respect to their impact on consumers. Following these results, the regulator may consider suggesting the retailer monetary incentives in order to utilize price discrimination.     

A measuring argument for finite permutation groups

LetG be a finite transitive permutation group on a finite setS. LetA be a nonempty subset ofS and denote the pointwise stabilizer ofA inG byC _G (A). Our main result is the following inequality: [G :C _G (A)]≥|G|^|A|/|S|. This paper is a part of the author’s Ph.D. thesis research, carried out at Tel Aviv University under the supervision of Professor Marcel Herzog.     

Simple route to strong-field coherent control

Coherent-control schemes to manipulate weak-field interactions are generally invalid at stronger fields, since strong-field interactions are accompanied by level power broadenings and level shifts that usually elude simple analytical treatments. Here we show that a broad subgroup of weak-field solutions (those with real fields, i.e., fields with only one quadrature in the complex plane) can be extended to the strong-field regime while retaining their properties. The salient feature of these fields is a symmetry that cancels out power broadening effects. Such fields can be generated from ultrashort coherent pulses or from incoherent broadband down-converted light. Weak-field coherent-control approaches based on these solutions can therefore be extended to the strong-field regime as we demonstrate in a two-photon absorption experiment in atomic cesium.     

Geometrical phase image encryption obtained with space-variant subwavelength gratings

An optical encryption method based on a geometrical phase produced by space-variant polarization manipulation is presented. The decrypted picture is retrieved either by a polarization measurement of the beam emerging from the encrypted element or by a single intensity measurement of the beam transmitted through the encrypted element followed by an optical key element. Both elements are realized by use of computer-generated space-variant subwavelength dielectric gratings. Theoretical analyses of the optical concept are presented along with experimental results.     

Space-variant polarization manipulation for far-field polarimetry by use of subwavelength dielectric gratings

A method for polarimetric measurement that uses a discrete space-variant subwavelength dielectric grating is presented. One retrieves the polarization state by measuring the far-field intensity of a beam emerging from the grating followed by a polarizer. The analysis for a partially polarized, quasi-monochromatic beam is performed by use of the beam coherence polarization matrix along with an extended van Cittert-Zernike theorem. We experimentally demonstrate polarization measurements of both fully and partially polarized light.     

Discrete multi-armed bandits and multi-parameter processes

Summary The general multi-armed bandit problem is reformulated and solved as a control problem over a partially ordered set. The approach taken provides a technically convenient framework for bandit-like problems. It also adds insight to the structure of strategies over partially ordered sets.     

Optimal Configurations of General Job Shops

In this paper we study the problem of minimizing the expected number of jobs in a single class general open queueing network model of a job shop. This problem was originally posed by Buzacott and Shanthikumar [2] and solved by them for a special case. We extend their work in this paper. We derive feasibility conditions that simplify the analysis of the problem. We show that the optimal configuration can be completely characterized when both the utilizations of the machine centers are high and there are a large number of servers at each machine center. We also derive conditions under which the optimization problem reduces to solving a concave or a convex program and provide conditions under which the uniform flow line and the symmetric job shop (or variants of these) are optimal configurations for the job shop.     

Fabrication of coaxial nanowire heterostructures: SiO x nanowires with conformal TiO2 coatings

Silica nanowires, grown via the active oxidation of a silicon substrate, have been coated with TiO₂ using two coating methods: solution-based deposition of Ti-alkoxides and atomic layer deposition. Analysis of as-deposited and annealed films shows that it is possible to produce stable conformal coatings of either the anatase or rutile phases of TiO₂ on nanowires with diameters greater than 100 nm when annealed between 500–600°C and 800–900°C, respectively, with annealing at higher temperatures (1050°C) producing coatings with a highly facetted rutile morphology. The efficacy of the process is shown to depend on nanowire diameter, with nanowires having diameters less than about 100 nm fusing together during solution-based coating and decomposing during TiO₂ atomic layer deposition. The use of a suitable buffer layer is shown to be an effective means of minimizing nanowire decomposition. Finally, annealing coated nanowires under active oxidation conditions (1100°C) is shown to be an effective technique for depositing additional conformal SiO _x coatings, thereby providing a means of fabricating multi-layered coaxial nanostructures.