bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation and Reactivity of 2-Substituted Adamantenes
Authors: Okazaki Takao , Tokunaga Kazuhiko , Kitagawa Toshikazu , Takeuchi Ken’ichi
Published: December 2003

The title bridgehead olefins, generated by the dehalogenation of 1,2-dihalo-2-R-adamantanes (R = Me, Et, Ph, p-CF3C6H4) with excess t-BuLi, yielded 2-t-butyl-2-R-adamantanes (15), 1-t-butyl-2-R-adamantanes (16), and dimeric products. The ratios of the yields (%) of 16 to 15 were 20 : 3 (R = Me), 32 :< 1 (R = Et), 4 : 60 (R = Ph), and 5 : 57 (R = p-CF3C6H4). 2-Alkyladamantenes predominantly yielded the products t-butylated at C(1), whereas 2-aryladamantenes gave the products t-butylated at C(2). The total yields of the dimers decreased with the bulkiness of substituents at position C(2). The dimerization of 2-methyladamantene gave a head-to-head dimer, 1-(2-methyl-1-adamantyl)-2-methyleneadamantane, as well as a head-to-tail dimer, 1-(2-methyl-2-adamantyl)-2-methyleneadamantane. The [4+2] cycloaddition between two molecules of 2-phenyladamantene, in which the phenyl group participates as a part of the diene, yielded a dimer of the head-to-tail type.

These results suggest that: i) a substituent at position C(2) can kinetically stabilize 2-R-adamantene and suppress the dimerization, ii) 2-alkyladamantenes might have a biradical nature, and iii) the regioselective [4+2] cycloaddition and t-BuLi addition of 2-phenyladamantene in THF can be explained by assuming a certain contribution of zwitterionic nature in the double bond that may be dependent on the media and nucleophiles.
Syntheses, Structures, and Redox Properties of 1,4-Bis(dimesitylphosphino)-2,3,5,6-tetrafluorobenzene and the Corresponding Bis(phosphoryl) and Bis(phosphonio) Derivatives
Authors: Sasaki Shigeru , Tanabe Yoshihiro , Yoshifuji Masaaki
Published: December 2003

Sterically hindered 1,4-bis(dimesitylphosphino)-2,3,5,6-tetrafluorobenzene (1) was synthesized by the aromatic nucleophilic substitution of lithium dimesitylphosphide with hexafluorobenzene. Two phosphorus atoms of 1 were oxidized and methylated to give the corresponding bis(phosphoryl)benzene 2 and bis(phosphonio)benzene 32+·2TfO− (TfO− = trifluoromethanesulfonyl), respectively. On the other hand, reaction of 1 with butyllithium and phenyllithium gave more crowded 2,5-dibutyl-1,4-bis(dimesitylphosphino)-3,6-difluorobenzene (4) and 1,4-bis(dimesitylphosphino)-2,5-difluoro-3,6-diphenylbenzene (5), respectively. Structures of 1, 2, 32+·2TfO−, 4, and 5 were confirmed by conventional spectroscopic methods; particularly 19F NMR spectroscopy reflected their crowded structures. Molecular structures of 1, 2, and 32+·2TfO−, were further investigated by X-ray crystallography, where unusually large bond angles around phosphorus atoms were observed. Electrochemical measurements were carried out to investigate redox properties of 1, 32+·2TfO−, 4, and 5. Although the cyclic voltammogram of diphosphine 1 showed irreversible oxidation waves above 0.8 V, in spite of substitution at all the ortho positions to the phosphorus atoms in 1, displacement of the two fluorine atoms of 1 by the butyl or the phenyl groups lowered the oxidation potential and improved the stability of the corresponding radical cations. Particularly, 5 clearly showed two-step oxidation waves. On the other hand, bis(phosphonium salt) 32+·2TfO− showed two steps of quasi-reversible redox waves, which suggested reduction to the cation radical and the neutral species, although their stability was limited.
Substituent Effects on the Solvolysis Rates and Gas Phase Stabilities of 1,2,2-Trimethyl-1-phenylpropyl and 1,2,2-Trimethyl-1-(2-methylphenyl)propyl Systems
Authors: Nakata Kazuhide , Fujio Mizue , Mishima Masaaki , Nomura Hideyuki , Tsuno Yuho , Nishimoto Kichisuke
Published: December 2003

Substituent effects on the solvolysis rates of 1,2,2-trimethyl-1-phenylpropyl chlorides in 80% (v/v) aq acetone at 45 °C and 1,2,2-trimethyl-1-(2-methylphenyl)propyl p-nitrobenzoates in 50% (v/v) aq ethanol at 75 °C were correlated with the Yukawa–Tsuno equation to give ρ = −4.28 and r = 0.91, and ρ = −2.78 and r = 0.70, respectively. The reduction in r values from r = 1.00 for full conjugation is ascribed to deviation from coplanarity of the carbocationic center and the benzylic π-system in the transition state. Substituent effects on the gas phase stabilities of 1,2,2-trimethyl-1-phenylpropyl cations and 1,2,2-trimethyl-1-(2-methylphenyl)propyl cations were correlated to give ρ = −9.1 and r = 0.89, and ρ = −6.6 and r = 0.70, respectively. The identical r values were obtained for the transition states and for the intermediates. The experimentally obtained torsion angles for twisting estimated from the relationship r/rmax = cos2  θ are in good agreement with theoretically calculated dihedral angles of the corresponding Becke3LYP/6-31G* optimized carbenium ions. This identity provides convincing evidence for occurrence of steric inhibition of resonance through loss of coplanarity and provides strong support for our characterization of the r value as a resonance demand parameter.
Phosphorescence of Benzophenone in Sol–Gel Silica
Authors: Matsui Kazunori , Nozawa Kazuhiro , Yoshida Tsutomu
Published: December 2003

The phosphorescence spectra of benzophenone (BP) were studied in tetramethoxysilane (TMOS) sol–gel systems at 77 K. The phosphorescence spectra ascribed to solvent-free benzophenone (f-BP), aggregated benzophenone (a-BP), and a benzophenone–water complex (w-BP) were observed in these systems. The results showed that the spectra varied with the BP concentration and sol–gel conditions, such as the water/TMOS ratios, catalyst, and the various sol–gel reaction stages. The w-BP phosphorescence lifetimes showed a single-exponential decay of 8 ms in sol systems and a double-exponential decay of 8—12 ms and 31 ms in xerogel systems. The longer lifetime component corresponds to a w-BP complex hydrogen bonded with silanol groups. These changes are discussed in terms of the sol–gel structure and surface adsorption effects.
Asymmetric Catalysis of New Generation Chiral Metallosalen Complexes
Authors: Ito Yoshio N , Katsuki Tsutomu
Published: December 2003

Chiral metallosalen complexes have been recognized as one of the most promising catalysts for various asymmetric reactions. The studies on asymmetric epoxidation catalyzed by chiral (salen)manganese complexes will be reviewed at first. The enantioselectivities have reached to the level as high as 90—99% ee for the epoxidation of conjugated cis-di- and trisubstituted olefins by developing the second generation of chiral salen ligands. Although it has been proven by Freichtinger and Plattner that epoxidation proceeds through an oxo species, the mechanism of asymmetric induction is still surrounded by controversy. However, our recent studies have clarified that the conformation of the salen ligand in oxo(salen)manganese(V) species plays a very important role in determining the direction of the olefin’s access to the oxo species. This study led to the new finding that an achiral (salen)metal complex can be used as a chiral catalyst by regulating the conformation of achiral ligand. The appropriately modified (salen)manganese(III) complexes can also be applicable for asymmetric oxidation of enol ether derivatives, kinetic resolution of racemic allenes, enantioselective benzylic C–H oxidation, asymmetric desymmetrization of meso-heterocycles, and asymmetric oxidation of alkyl aryl sulfides. In the asymmetric aziridination of styrene derivatives by using PhI=NTs as a terminal oxidant, high enantioselectivity of up to 94% has been achieved by the further modification of the chiral (salen)manganese(III) complex. The chiral (salen)cobalt(III) complex is a good catalyst for asymmetric cyclopropanation of styrene derivatives and asymmetric S-ylide formation from allyl aryl sulfides, in which the resulting S-ylides undergo [2,3]-Wittig rearrangement in situ to produce chiral 2-(phenylthio)pentanoate derivatives.
Pd L3-Edge XANES Spectra of Supported Pd Particles Induced by the Adsorption and the Absorption of Hydrogen
Authors: Kubota Takeshi , Kitajima Yoshinori , Asakura Kiyotaka , Iwasawa Yasuhiro
Published: December 2003

We measured Pd L3-edge X-ray absorption near-edge structure (XANES) spectra for small Pd particles dispersed on inorganic oxide supports (SiO2 and Al2O3) and the spectra changes induced by the adsorption and the absorption of hydrogen. When the XANES spectra were measured under the atmosphere of H2, a new peak appeared at about 8 eV above the inflection point of the absorption edge. The peak position was invariant but its intensity decreased with the decrease of Pd particle size. This peak is caused by hydrogen absorption in the Pd particles. Hydrogen at the subsurface region little affected the Pd L3-edge XANES spectra. A new peak also appeared for the Pd sample accompanied with hydrogen adsorbed on the surface. The peak energy relative to the edge was independent of the Pd particle size and the peak intensity increased with the amount of adsorbed hydrogen. The XANES spectra can quantify the adsorbed and absorbed hydrogen atoms. We presented a model of Pd particles composed of surface, subsurface and bulk atoms.
Crystal Structures and Magnetic Properties of d-pπ Organic Conductors, (EDT-TTF)4CoCl4(1,1,2-TCE)x and Related Materials
Authors: Mori Hatsumi , Sakurai Naoki , Tanaka Shoji , Moriyama Hiroshi
Published: December 2003

A new series of d-pπ organic conductors ((EDT-TTF)4CoX4(solvent)x [EDT–TTF = ethylenedithiotetrathiafulvalene; X = Cl, Br; solvent = 1,1,2–TCE (trichloroethane), CH2Cl2]) consists of anions including 3d localized spins and donors containing itinerant pπ electrons. The crystal and band structure analyses show that these salts have face-to-face regular donor stacking, the so-called β-type donor arrangement, and that the calculated Fermi surfaces are closed due to relatively large interchain interactions. Resistivity measurements show the metallic behaviors down to 80 K [(EDT-TTF)4CoCl4(1,1,2-TCE)x], 235 K [(EDT-TTF)4CoCl4(CH2Cl2)x], 110 K [(EDT-TTF)4CoBr4(1,1,2-TCE)x], and 190 K [(EDT-TTF)4CoBr4(CH2Cl2)x], respectively. Especially, for (EDT-TTF)4CoCl4(1,1,2-TCE)x, the ESR measurements indicate that the linewidth attributed to EDT-TTF+ increases and that the g-value decreases rapidly when the resistivity starts increasing below 80 K, owing to substantially the dipole–dipole interaction between pπ (EDT-TTF+)-3d (Co2+) spins. At around 33 and 20 K, the anomalies of the ESR linewidth have been observed, suggesting the instability of the pπ part.
The B1u and B2u Vibrational Modes Causing a D6h to D3h Transition in Benzene and in [18]- and [30]Annulenes
Authors: Yoshizawa Kazunari , Tachibana Masamitsu , Yamabe Tokio
Published: December 2003

Alternation of long and short carbon–carbon bonds in large cyclic polyenes are investigated from the point of view of vibrational analyses. [6(2n + 1)]Annulenes, where n is 0, 1, 2,···, are cyclic polyenes that can have planar bond-delocalized D6h or bond-localized D3h structures without severe nonbonded interactions. The B1u and B2u modes of vibration that potentially cause a D6h to D3h transition in benzene, [18]annulene, and [30]annulene are specifically discussed. The delocalized D6h structure is stable in benzene and [18]annulene, but not in [30]annulene. The D6h structure of [30]annulene has an imaginary B2u mode of 416i cm−1 that has relevance to the so-called Kekulé B2u mode of benzene. The D6h structure of [30]annulene is confirmed to be a transition state that leads to the equivalent D3h global minimum in both the forward and reverse directions.
Determination of Total Arsenic in Environmental and Geological Samples by Electrothermal Atomic Absorption Spectrometry Using a Tungsten Furnace after Solvent Extraction and Cobalt(III) Oxide Collection
Authors: Narukawa Tomohiro , Yoshimura Wataru , Uzawa Atsushi
Published: December 2003

A separation method, using solvent extraction and cobalt(III) oxide collection, has been studied for determining the total arsenic in environmental and geological samples by electrothermal atomic absorption spectrometry (ETAAS) using a tungsten furnace. After arsenic iodide was extracted into benzene, cobalt(III) oxide powder was added to the benzene solution to collect the extracted arsenic. The cobalt(III) oxide was separated from benzene by vacuum filtration and then suspended in 5 cm3 of water. The slurry was introduced into the tungsten furnace and the determination of arsenic was performed. The relative standard deviation of the proposed method at the 0.20 mg dm−3 arsenic level was 2.4% (n = 10). The calibration curve obtained with the proposed method was linear up to 0.50 mg dm−3 (5.00 ng/10 mm3), and the detection limit (3σ) was 12 μg dm−3 (0.12 ng/10 mm3). The present method was applied to the analysis of some environmental and geological standard reference materials, and the concentrations of total arsenic obtained by the present method were in good agreement with the certified values or the reference values of those samples.
Hydroxylation of Aliphatic Hydrocarbons with m-Chloroperbenzoic Acid Catalyzed by Electron-Deficient Iron(III) Porphyrin Complexes
Authors: Lim Mi Hee , Lee Yoon Jung , Goh Yeong Mee , Nam Wonwoo , Kim Cheal
Published: December 2003

The catalytic hydroxylation of aliphatic hydrocarbons by m-chloroperbenzoic acid (MCPBA) has been studied in the presence of elecrtron-deficient iron(III) porphyrin complexes. High yields of alcohol products were obtained with small amounts of ketone formation under mild reaction conditions. The stereospecificity and regioselectivity of the iron porphyrin complexes have been investigated in hydroxylation reactions as well. The hydroxylation of alkanes has been performed in the presence of isotopically 18O-labeled water, H218O, in order to understand the effects of the electronic nature of iron porphyrin complexes, the concentration of H218O, the C–H bond strength of alkanes, and the reaction temperature on the 18O-incorporation from the labeled water into alcohols. We found that the amounts of 18O incorporated into the alcohol products varied in the reactions; these results were interpreted with that the reaction of oxygen atom transfer from a high-valent iron oxoporphyrin complex to alkanes competes with that of oxygen atom exchange between the intermediate and labeled water that leads to 18O-incorporation from H218O into the alcohol products. Deuterium kinetic isotope effects (KIEs) in the alkane hydroxylations by the iron porphyrin complexes and MCPBA have been studied with a mixture of cyclohexane and cyclohexane-d12. The KIE values obtained in the reactions were found to depend significantly on the nature to the iron porphyrin complexes. The temperature dependence of kH/kD was also studied from −40 to 25 °C and the parameters of Arrhenius equation (i.e., the pre-exponential factor ratio, AH/AD, and the isotopic difference of C–H and C–D bond activation energies, Ea(D)–Ea(H)) were determined.
Synthesis and Photochemical Properties of Ruthenium–Cobalt and Ruthenium–Nickel Dinuclear Complexes
Authors: Komatsuzaki Nobuko , Himeda Yuichiro , Hirose Takuji , Sugihara Hideki , Kasuga Kazuyuki
Published: December 2003

Three dinuclear colmplexes, two Ru(II)–Co(III) and one Ru(II)–Ni(II) polypyridyl complexes, were prepared by the use of ethylene- and pentamethylene-linked bisphenanthroline as the bridging ligands. Their photochemical and electrochemical properties were examined. Each metal complex component was shown to be electronically insulated. Since the roles of the Ru(II) as a photosensitizer and the Co(III) or Ni(II) moiety as an electron acceptor were expected, a photocatalytic CO2 reduction experiment was carried out. The catalytic ability of the Ru(II)–Co(III) system was shown to be almost the same as the corresponding intermolecular systems with the improved CO/H2 selectivity, showing that the Co(III) polypyridyl complex was as effecticve as the Co(II) species for a catalytic center.
Solvent-Dependent Conformations of Cyclic Tetrapeptide. II
Authors: Tamaki Makoto , Yabu Mikihiro , Saeki Tomomi , Kaneko Ayako , Akabori Sadatoshi , Muramatsu Ichiro
Published: December 2003

The solvent-dependent conformations of cyclo(–δ-Ava–l-Pro–)2 were characterized by means of the 1H and 13H NMR, CD, and IR spectra. CD results in CH2Cl2, CH3CN, CH3OH, and H2O indicated that the change in polarity of the solvent induces a reversible change in the conformation of cyclo(–δ-Ava–l-Pro–)2, revealed by the decrease of the negative peak near to 230 nm and then by the gradual appearance of a negative trough near to 210 nm. The NMR data in CD3Cl, CD2Cl2, CD3CN, and CD3OH confirmed that cyclo(–δ-Ava–l-Pro–)2 has a C2 symmetric conformation consisting of all-trans peptide-bond backbones in all solvents, and that the change in polarity of the solvent induces a difference in the rotational states of the Pro αC–C=O single bond.
Glycosylation Using 2-Azido-3,4,6-tri-O-benzyl-2-deoxy-d-glucose, -galactose, and -mannose with the Aid of p-Nitrobenzenesulfonyl Chloride–Silver Trifluoromethanesulfonate–Triethylamine System
Authors: Koto Shinkiti , Asami Kazuyasu , Hirooka Motoko , Nagura Kazuo , Takizawa Mizue , Yamamoto Satoko , Okamoto Nami , Sato Mitsuko , Tajima Hiromi , Yoshida Toyosaku , Nonaka Nobuo , Sato Tadaaki , Zen Shonosuke , Yago Kazuo , Tomonaga Fumiya
Published: December 2003

This report describes a simple synthesis of 2-azido-3,4,6-tri-O-benzyl-2-deoxy-d-glucopyranose. Glycosylation using this as well as 2-azido-3,4,6-tri-O-benzyl-2-deoxy-d-galactopyranose and -mannopyranose was achieved with the aid of a reagent system consisting of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine, and its modifications. O-(2-Acetamido-2-deoxy-β-d-glucopyranosyl)-(1→4)-O-α-d-mannopyranosyl-(1→4)-α-d-mannopyranose, the repeating unit of the main chain of the O-specific cell wall polysaccharide of E. coli 058 was synthesized.
Oxidative Addition of Aryl and Benzyl Trifluoroacetates to Zerovalent Palladium Complexes with Two Modes of C–O Bond Cleavage Processes
Authors: Nagayama Kazuhiro , Shimizu Isao , Yamamoto Akio
Published: December 2003

The aryl trifluoroacetates oxidatively added to a zerovalent palladium complex 2a with acyl-O bond cleavage under mild conditions to give the corresponding trans-(aryloxo)(trifluoroacetyl)palladium complexes 3a—3c. But 4-nitrophenyl trifluoroacetate reacted with 2a to yield cis-[Pd(OC6H4-4-NO2)2(PMe3)2] 3d, which was produced with C–O bond activation followed by disproportionation reaction. In contrast, benzyl trifluoroacetates reacted with the Pd(0) complex with benzyl–O bond fission to form benzyl(trifluoroacetato)palladium complexes 4a—4d. Complexes 4a—4d are in equilibrium in solutions between trans and cis isomers, with the proportion of the cis isomer increasing in polar solvents. Palladium-catalyzed carbonylation of benzyl trifluoroacetate has been achieved in the presence of benzyl alcohol and triethylamine to yield benzyl phenylacetate.
A Facile Synthesis of Trifluoromethyl- and 3,3,3-Trifluoropropenyl-Substituted Aromatic Compounds by the Oxidative Desulfurization-Fluorination of the Corresponding Carbodithioates
Authors: Furuta Satoru , Kuroboshi Manabu , Hiyama Tamejiro
Published: December 2003

Trifluoromethyl-substituted aromatic compounds were easily synthesized by the oxidative desulfurization-fluorination reaction of readily accessible methyl arenecarbodithioates using [n-Bu4N]H2F3 and 1,3-dibromo-5,5-dimethylhydantoin (DBH) under extremely mild conditions. Use of N-bromosuccinimide or N-iodosuccinimide instead of DBH afforded difluoro(methylthio)methyl-substituted aromatics. In a similar way, 3,3,3-trifluoropropenyl-substituted aromatic compounds were readily prepared from the corresponding α,β-unsaturated carbodithioates.
Synthesis and Properties of Extremely Stable Tris(6-methoxy-1-azulenyl)methyl Cation and a Series of Di(1-azulenyl)phenylmethyl and (1-Azulenyl)diphenylmethyl Cations Stabilized by Methoxy Substituents
Authors: Ito Shunji , Kikuchi Shigeru , Morita Noboru , Asao Toyonobu
Published: December 2003

Extremely stable carbocations, tris(6-methoxy-1-azulenyl)methyl (8), bis(6-methoxy-1-azulenyl)(4-methoxyphenyl)methyl (9a), and (6-methoxy-1-azulenyl)bis(4-methoxyphenyl)methyl (10a) cations and a series of di(1-azulenyl)phenylmethyl and (1-azulenyl)diphenylmethyl cations having methoxy substituents on each phenyl group, i.e., di(1-azulenyl)(4-methoxyphenyl)methyl (9b) and (1-azulenyl)bis(4-methoxyphenyl)methyl (10b) cations and 3-methyl-1-azulenyl (9cand 10c) and 3,6-di-t-butyl-1-azulenyl (9d and 10d) analogues, were synthesized by hydride abstraction from the corresponding methane derivatives and their properties were fully characterized. The pKR+ values of 8 and 9a were well beyond 14.0. The value of 10a was determined as 13.2, which is higher by 10.2 pK units than that of (1-azulenyl)diphenylmethyl cation. The value also considerably increased by the methoxy substitution on each phenyl group. The values of 9b—d (pKR+ 11.7—13.4) and 10b—d (pKR+ 5.2—7.0) are higher by 1.0—1.4 and 2.2—2.4 pK units than those of the corresponding analogous benzyl and diphenylmethyl cations. The electrochemical reduction of 8, 9a—d, and 10a—d showed a wave at −0.88, −0.71 — −0.83, and −0.56 — −0.71 V (V vs. Ag/Ag+), respectively, upon cyclic voltammetry (CV). The relatively high reduction potentials also exhibited the stabilization of the methyl cations by the methoxy substituents. The oxidation of 8 in acetonitrile exhibited barely separated two-step, one-electron oxidation waves at a potential range of +0.90 — +0.98 V upon CV, although 9a—d and 10a—d did not show two similar waves at a narrow potential range. The wave is ascribed to the oxidation of two azulene rings to generate a trication species.
New Ionic Liquid Crystal Compounds Having a 1,3-Oxathiane or 1,3-Dioxane Ring
Authors: Haramoto Yuichiro , Akiyama Yoshiharu , Segawa Ryouichi , Nanasawa Masato , Ujiie Seiji , Holmes Andrew B
Published: December 2003

New pyridinium type thermotropic ionic liquid crystal materials bearing a 1,3-oxathiane ring in their central core: N-substituted 4-(5-alkyl-1,3-oxathian-2-yl)pyridinium bromides (8) and corresponding 1,3-dioxane analogs (10) were synthesized. And the mesomorphic behaviors of these two systems are compared. The principal feature of these compounds is to exhibit a smectic A phase over a very wide temperature range including room temperature [for example 8-4: G −7 SmA 166 I; 10-4: G −24 SmA 152 I (°C)].
A Survey of Algorithms for Convex Multicommodity Flow Problems
Authors: Ouorou A. , Mahey P. , Vial J.-Ph.
Published: December 2003

Routing problems appear frequently when dealing with the operation of communication or transportation networks. Among them, the message routing problem plays a determinant role in the optimization of network performance. Much of the motivation for this work comes from this problem which is shown to belong to the class of nonlinear convex multicommodity flow problems. This paper emphasizes the message routing problem in data networks, but it includes a broader literature overview of convex multicommodity flow problems. We present and discuss the main solution techniques proposed for solving this class of large-scale convex optimization problems. We conduct some numerical experiments on the message routing problem with four different techniques.
Three Scheduling Algorithms Applied to the Earth Observing Systems Domain
Authors: Wolfe William J. , Sorensen Stephen E.
Published: December 2003

This paper describes three approaches to assigning tasks to earth observing satellites (EOS). A fast and simple priority dispatch method is described and shown to produce acceptable schedules most of the time. A look ahead algorithm is then introduced that outperforms the dispatcher by about 12% with only a small increase in run time. These algorithms set the stage for the introduction of a genetic algorithm that uses job permutations as the population. The genetic approach presented here is novel in that it uses two additional binary variables, one to allow the dispatcher to occasionally skip a job in the queue and another to allow the dispatcher to occasionally allocate the worst position to the job. These variables are included in the recombination step in a natural way. The resulting schedules improve on the look ahead by as much as 15% at times and 3% on average. We define and use the “window-constrained packing” problem to model the bare bones of the EOS scheduling problem.
Shifts of Reference Points for Framing of Strategic Decisions and Changing Risk-Return Associations
Authors: Lehner Johannes M.
Published: December 2003

Previous results on nonlinear risk-return associations, predicted by prospect theory, are replicated with mean quadratic differences instead of variance as a measure of risk. In contrast to assumptions of these studies, results with a sample from the COMPUSTAT-database provide evidence that at least a minority of firms shift to individual reference levels, which are represented here through levels of minimal risk. Further, changes of environmental conditions as an alternative explanation for switching risk-return relationships are tested against prospect theory predictions. It is shown that risk-return relationships remain stable as long as the relative position to the individual reference level is stable. This explains switching risk-return relationships better than changing environmental conditions.
Attribute Conflict and Preference Uncertainty: Effects on Judgment Time and Error
Authors: Fischer Gregory W. , Luce Mary Frances , Jia Jianmin
Published: December 2003

This research investigates preference uncertainty generated as a function of specific alternative characteristics during multiattribute evaluative judgments. We propose that preference uncertainty has at least two behavioral manifestations: longer judgment times and greater response error in expressed preferences. We investigate two hypotheses regarding stimulus-based causes of preference uncertainty. As predicted by our attribute conflict hypothesis, greater within-alternative conflict (discrepancy among the attributes of an evaluative alternative) led to longer judgment times and greater response error. As predicted by our attribute extremity hypothesis, greater attribute extremity (very high or low attribute values) resulted in shorter judgment times and less response error. We also found that judgment times and response errors were strongly positively correlated at the item level, consistent with our assumption that preference uncertainty generated by stimulus characteristics is manifested in judgment time and error. Finally, we found that the item-level preference uncertainty effects proposed here operate in parallel with strategy-level, effort-accuracy tradeoffs observable across participants. These findings are consistent with the RandMAU random multiattribute utility model developed in a companion article by Fischer et al. (2000).
Variance Reduction via Lattice Rules
Authors: L'Ecuyer Pierre , Lemieux Christiane
Published: December 2003

This is a review article on lattice methods for multiple integration over the unit hypercube, with a variance-reduction viewpoint. It also contains some new results and ideas. The aim is to examine the basic principles supporting these methods and how they can be used effectively for the simulation models that are typically encountered in the area of management science. These models can usually be reformulated as integration problems over the unit hypercube with a large (sometimes infinite) number of dimensions. We examine selection criteria for the lattice rules and suggest criteria which take into account the quality of the projections of the lattices over selected low-dimensional subspaces. The criteria are strongly related to those used for selecting linear congruential and multiple recursive random number generators. Numerical examples illustrate the effectiveness of the approach.
A Heavy Traffic Approximation for Workload Processes with Heavy Tailed Service Requirements
Authors: Resnick Sidney , Samorodnitsky Gennady
Published: December 2003

A system with heavy tailed service requirements under heavy load having a single server has an equilibrium waiting time distribution which is approximated by the Mittag-Leffler distribution. This fact is understood by a direct analysis of the weak convergence of a sequence of negative drift random walks with heavy right tail and the associated all time maxima of these random walks. This approach complements the recent transform view of Boxma and Cohen (1997).
Product Differentiation and Commonality in Design: Balancing Revenue and Cost Drivers
Authors: Desai Preyas , Kekre Sunder , Radhakrishnan Suresh , Srinivasan Kannan
Published: December 2003

Product design decisions substantially affect the cost and revenue drivers. A design configuration with commonality can lower manufacturing cost. However, such a design may hinder the ability to extract price premiums through product differentiation. We explicitly investigate the marketing-manufacturing trade-off and derive analytical implications for three possible design configurations: unique, premium-common, and basic-common. Our model considers two distinct segments of consumers. Some of the implications of our analysis are not readily apparent. For example, when the high-quality component is made common, the average quality of the products offered to the two segments increases. One may infer that with higher average quality, higher prices or higher total revenues might ensue. However, this may not be the case, as detailed in the paper. Finally, our analysis provides a useful framework to develop an index that can rank order components in terms of their attractiveness for commonality.
Appropriateness and Impact of Platform-Based Product Development
Authors: Krishnan V. , Gupta Saurabh
Published: December 2003

In their quest to manage the complexity of offering greater product variety, firms in many industries are considering platform-based product development. Product platforms, which are component and subsystem assets shared across a product-family, enable a firm to better leverage investments in product design and development. While the platform approach offers a number of benefits, it also imposes certain additional costs that have not received adequate research attention. In this paper, we use an industrial example both to illustrate some of the costs and benefits of platform-based product development and to motivate the development of a mathematical model. The model is formulated to better understand the appropriateness of product platforms and their impact on product-planning decisions. Our results indicate that platforms are not appropriate for extreme levels of market diversity or high levels of nonplatform scale economies. Also, a firm's product positioning and introduction sequence decisions made during the product-planning phase are significantly impacted by the presence of platforms. Specifically, a platform increases the separation among products and offers a multitude of product introduction strategies. We translate our model findings into a managerial framework.
The Effect of Collaborative Forecasting on Supply Chain Performance
Authors: Aviv Yossi
Published: December 2003

We consider a cooperative, two-stage supply chain consisting of two members: a retailer and a supplier. In our first model, called local forecasting, each member updates the forecasts of future demands periodically, and is able to integrate the adjusted forecasts into his replenishment process. Forecast adjustments made at both levels of the supply chain can be correlated. The supply chain has a decentralized information structure, so that day-to-day inventory and forecast information are known locally only. In our second model, named collaborative forecasting, the supply chain members jointly maintain and update a single forecasting process in the system. Hence, forecasting information becomes centralized. Finally, we consider as a benchmark the special case in which forecasts are not integrated into the replenishment processes at all. We propose a unified framework that allows us to study and compare the three types of settings. This study comes at a time when various types of collaborative forecasting partnerships are being experimented within industry, and when the drivers for success or failure of such initiatives are not yet fully understood. In addition to providing some managerial insights into questions that arise in this context, our set of models is tailored to serve as building blocks for future work in this emerging area of research.
Server Assignment Policies for Maximizing the Steady-State Throughput of Finite Queueing Systems
Authors: Andradóttir Sigrún , Ayhan Hayriye , Down Douglas G.
Published: December 2003

For a system of finite queues, we study how servers should be assigned dynamically to stations in order to obtain optimal (or near-optimal) long-run average throughput. We assume that travel times between different service facilities are negligible, that each server can work on only one job at a time, and that several servers can work together on one job. We show that when the service rates depend only on either the server or the station (and not both), then all nonidling server assignment policies are optimal. Moreover, for a Markovian system with two stations in tandem and two servers, we show that the optimal policy assigns one server to each station unless that station is blocked or starved (in which case the server helps at the other station), and we specify the criterion used for assigning servers to stations. Finally, we propose a simple server assignment policy for tandem systems in which the number of stations equals the number of servers, and we present numerical results that show that our policy appears to yield near-optimal throughput under general conditions.
Bayesian Models for Early Warning of Bank Failures
Authors: Sarkar Sumit , Sriram Ram S.
Published: December 2003

The focus of this research is to demonstrate how probabilistic models may be used to provide early warnings for bank failures. While prior research in the auditing literature has recognized the applicability of a Bayesian belief revision framework for many audit tasks, empirical evidence has suggested that auditors' cognitive decision processes often violate probability axioms. We believe that some of the well-documented cognitive limitations of a human auditor can be compensated by an automated system. In particular, we demonstrate that a formal belief revision scheme can be incorporated into an automated system to provide reliable probability estimates for early warning of bank failures. The automated system examines financial ratios as predictors of a bank's performance and assesses the posterior probability of a banks financial health (alternatively, financial distress). We examine two different probabilistic models, one that is simpler and makes more assumptions, while the other that is somewhat more complex but makes fewer assumptions. We find that both models are able to make accurate predictions with the help of historical data to estimate the required probabilities. In particular, the more complex model is found to be very well calibrated in its probability estimates. We posit that such a model can serve as a useful decision aid to an auditor's judgment process.
Making Descriptive Use of Prospect Theory to Improve the Prescriptive Use of Expected Utility
Authors: Bleichrodt Han , Pinto Jose Luis , Wakker Peter P.
Published: December 2003

This paper proposes a quantitative modification of standard utility elicitation procedures, such as the probability and certainty equivalence methods, to correct for commonly observed violations of expected utility. Traditionally, decision analysis assumes expected utility not only for the prescriptive purpose of calculating optimal decisions but also for the descriptive purpose of eliciting utilities. However, descriptive violations of expected utility bias utility elicitations. That such biases are effective became clear when systematic discrepancies were found between different utility elicitation methods that, under expected utility, should have yielded identical utilities. As it is not clear how to correct for these biases without further knowledge of their size or nature, most utility elicitations still calculate utilities by means of the expected utility formula. This paper speculates on the biases and their sizes by using the quantitative assessments of probability transformation and loss aversion suggested by prospect theory. It presents quantitative corrections for the probability and certainty equivalence methods. If interactive sessions to correct for biases are not possible, then the authors propose to use the corrected utilities rather than the uncorrected ones in prescriptions of optimal decisions. In an experiment, the discrepancies between the probability and certainty equivalence methods are removed by the authors' proposal.
A Theory of Finitely Durable Goods Monopoly with Used-Goods Market and Transaction Costs
Authors: Huang S. , Yang Y. , Anderson K.
Published: December 2003

We construct a dynamic game to model a monopoly of finitely durable goods. The solution concept is Markov-perfect equilibria with general equilibria embedded in every time period. Our model is flexible enough to simultaneously explain or accommodate many commonly observed phenomena or stylized facts, such as concurrent leasing and selling, active secondary markets for used goods, heterogeneous consumers, endogenous consumption patterns, depreciation, an infinite time horizon, and nontrivial transaction costs. Within our model, consumers have incentives to segment themselves into various consumption classes according to their willingness to pay, and nontrivial transaction costs to sell used goods put strong constraints on consumers' consumption sequences in time. As a direct consequence of the finite durability, the market power of the monopolist remains intact. Leasing manifests itself as a facilitator of price discrimination by debundling the durable good into new and used portions that are naturally bundled together under outright sales. The concurrent leasing and selling reflects the degree of the comparative advantage the monopolist has over consumers in disposing used goods. This comparative advantage, which is partially exploited by the monopolist and partially shared by the consumers, provides a sufficient mechanism to gain Pareto improvement on the market.
Project Contracts and Payment Schedules: The Client's Problem
Authors: Dayanand Nalini , Padman Rema
Published: December 2003

Contractual agreements have assumed significant complexity in recent times because of the emergence of strategies like outsourcing and partnering in the successful completion of large software development, manufacturing, and construction projects. A client and contractor enter into an agreement for a project either by bidding or negotiation. Effective and efficient bidding, negotiation, and subsequent monitoring are hindered by the lack of appropriate decision support tools for the management of project finances. Progress payments to the contractor are an important issue in project management because of their potential impact on project finances and activity schedules. In this paper, we consider the problem of simultaneously determining the amount, location, and timing of progress payments in projects from a client's perspective. We develop three mixed-integer linear programming models, based on some practical methods of determining payment schedules from different types of project contracts. We discuss properties of the models and draw insights about the characteristics of optimal payment schedules obtained with each model by an experimental study on a sample of 10 small projects. Our analysis shows that, contrary to current practice, the client obtains the greatest benefit by scheduling the project for early completion such that the payments are not made at regular intervals. It is also cost effective for the client to make payments either in the early stages of the project or toward the end, even though this causes considerable variation in the time gap between payments. We also evaluate the impact of the client's preferred payment schedules on the contractor's finances and activity schedules, and draw some conclusions on the interdependence of payment and project parameters on the objectives of both parties entering the contractual agreement.
An Optimization Framework for Product Design
Authors: Shi Leyuan , Ólafsson Sigurdur , Chen Qun
Published: December 2003

An important problem in the product design and development process is to use the part-worths preferences of potential customers to design a new product such that market share is maximized. The authors present a new optimization framework for this problem, the nested partitions (NP) method. This method is globally convergent and may utilize existing heuristic methods to speed its convergence. We incorporate several known heuristics into this framework and demonstrate through numerical experiments that using the NP method results in superior product designs. Our numerical results suggest that the new framework is particularly useful for designing complex products with many attributes.
Exploiting a Cost Advantage and Coping with a Cost Disadvantage
Authors: Besanko David , Dranove David , Shanley Mark
Published: December 2003

This paper provides an empirical investigation of how firms with cost advantages (cost disadvantages) exploit (cope with) their advantages (disadvantages) through their pricing behavior. Guided by microeconomic theory and insights from the industrial organization literature, we develop testable implications about the effect of industry structure and firm-specific characteristics on the pass-through elasticity: The rate at which changes in a firm's cost relative to competitors translates into changes in the firm's price relative to competitors. We test these implications using data from the PIMS Competitive Strategy database. The results indicate that a firm's pass-through elasticity systematically depends on whether the firm operates in a commodity or noncommodity industry, the firm's capacity utilization, and its cost and quality position in its industry. The pass-through elasticity is also shown to depend in a nonlinear way on market concentration.
Scheduling and Reliable Lead-Time Quotation for Orders with Availability Intervals and Lead-Time Sensitive Revenues
Authors: Keskinocak Pinar , Ravi R. , Tayur Sridhar
Published: December 2003

Motivated by applications in the manufacturing and service industries, we consider two models for coordinating scheduling with lead-time quotation: a basic model with a single customer type, and an enhanced model where an additional second customer type expects immediate service or production. In both models, revenues obtained from the customers are sensitive to the lead time, there is a threshold of lead time above which the customer does not place an order, and the quoted lead times are 100% reliable. These models are related to well-known scheduling problems, which have been studied in both offline and online settings.

We introduce the immediate quotation case and study it with the (traditional) online version. We provide complexity results for the offline case, and perform competitive analysis for the online cases. A natural question of bridging the gap between the online and quotation models leads us to the delayed quotation model, which we study briefly. The analysis of these models provides useful qualitative insights as well.
Efficient Timing of Communication in Multiperiod Agencies
Authors: Christensen Peter O. , Feltham Gerald A.
Published: December 2003

This paper examines communication in a two-period principal/agent model in which the agent receives a private signal about the second outcome before the first outcome is realized. No communication is compared with communication at three possible dates: before the first outcome (early), at the first outcome/consumption date (normal), and between the initial consumption date and the second outcome (delayed). Delayed communication is shown to have no value if the agent's information is perfect, but can have value if it is imperfect. Early and normal communication can be used to “smooth” compensation across periods and, hence, generally have incremental value over delayed communication if the agent cannot borrow or save. However, the “smoothing” benefits disappear if he can borrow and save. Early and normal communication are equivalent if the agent has domain-additive exponential preferences and the private signal is uninformative about the first outcome. If the private signal is informative about the first outcome, the incremental value of early compared with normal communication attains its maximum for “medium” informativeness. A unifying example is used throughout.
A Periodic Review Inventory System with Emergency Replenishments
Authors: Tagaras George , Vlachos Dimitrios
Published: December 2003

This paper proposes and analyzes a periodic review inventory system with two replenishment modes. Regular orders are placed periodically following a base stock policy on inventory position, and arrive at the stocking location after a deterministic lead time. The location also has the option of placing emergency orders, characterized by a shorter lead time but higher acquisition cost, in case of imminent stockouts. Thus, at some appropriate time in the replenishment cycle, the necessity and size of an emergency order is determined according to a base stock policy on net stock. The timing of the emergency order is such that this order arrives and can be used to satisfy the demand in the time period just before the arrival of a regular order, when the likelihood of a stockout is highest. An approximate cost model is developed which can easily be optimized with respect to the order-up-to parameters. This model is used as the basis for a heuristic algorithm, which leads to solutions that are very close to the exact optimal solutions determined through simulation. It is shown that the proposed system offers substantial cost savings relative to a system without the emergency replenishment option.
Learning and Forgetting: Modeling Optimal Product Sampling Over Time
Authors: Heiman Amir , McWilliams Bruce , Shen Zhihua , Zilberman David
Published: December 2003

Firms use samples to increase the sales of almost all consumable goods, including food, health, and cleaning products. Despite its importance, sampling remains one of the most under-researched areas. There are no theoretical quantitative models of sampling behavior other than the pioneering work of Jain et al. (1995), who modeled sampling as an important factor in the diffusion of new products.

In this paper we characterize sampling as having two effects. The first is the change in the probability of a consumer purchasing a product immediately after having sampled the product. The second is an increase in the consumer's cumulative goodwill formation, which results from sampling the product. This distinction differentiates our model from other models of goodwill, in which firm sales are only a function of the existing goodwill level.

We determine the optimal dynamic sampling effort of a firm and examine the factors that affect the sampling decision. We find that although the sampling effort will decline over a product's life cycle, it may continue in mature products. Another finding is that when we have a positive change in the factors that increase sampling productivity, steady-state goodwill stock and sales will increase, but equilibrium sampling can either increase or decrease. The change in the sampling level is indeterminate because, while increased sampling productivity means that firms have incentives to increase sampling, the increase in the equilibrium goodwill level indirectly reduces the marginal productivity of sampling, thus reducing the incentives to sample. We discuss managerial implications, and how the model can be used to address various circumstances.