bluuebunny/crossref_metadata_2025_split huggingface dataset:
Massively Categorical Variables: Revealing the Information in Zip Codes
Authors: Steenburgh Thomas J. , Ainslie Andrew , Engebretson Peder Hans 
Published: December 2003

We introduce the idea of a massively categorical variable, a variable such as zip code that takes on too many values to treat in the standard manner. We show how to use a massively categorical variable directly as an explanatory variable.As an application of this concept, we explore several of the issues that analysts confront when trying to develop a direct marketing campaign. We begin by pointing out that the data contained in many of the common sources are masked through aggregation in order to protect consumer privacy. This creates some difficulty when trying to construct models of individual level behavior.We show how to take full advantage of such data through a hierarchical Bayesian variance components (HBVC) model. The flexibility of our approach allows us to combine several sources of information, some of which may not be aggregated, in a coherent manner. We show that the conventional modeling practice understates the uncertainty with regard to its parameter values.We explore an array of financial considerations, including ones in which the marginal benefit is non-linear, to make robust model comparisons. To implement the decision rules that determine the optimal number of prospects to contact, we develop an algorithm based on the Monte Carlo Markov chain output from parameter estimation. We conclude the analysis by demonstrating how to determine an organization's willingness to pay for additional data.
Price Uncertainty and Consumer Search: A Structural Model of Consideration Set Formation
Authors: Mehta Nitin , Rajiv Surendra , Srinivasan Kannan 
Published: December 2003

We offer an econometric framework that models consumer's consideration set formation as an outcome of her costly information search behavior. Because frequently purchased products are characterized by frequent price promotions of varying depths of discounts, a consumer faces significant uncertainty about the prices of the brands. The consumers engage in a fixed-sample search strategy that results in their discovering the posted prices of a subset of the available brands. This subset is referred to as the consumer's “consideration set.” The proposed model is estimated using the scanner data set for liquid detergents. Our key empirical results are: (i) consumers zincur significant search costs to discover the posted prices of the brands; (ii) whereas in-store displays and feature ads do not influence consumers' quality perceptions of the brands, they significantly reduce search costs for observing the prices of the brands; (iii) per capita income of consumer's household significantly increases her search costs; and (iv) the consumers' price sensitivity is seriously underestimated if we were to assume that consumers get to know all the posted prices at zero cost. The proposed model is also estimated for the ketchup category to enable us to do cross-category comparisons of consumers' price search behavior
Editorial: Compartmentalized Reviews and Other Initiatives: Should Marketing Scientists Review Manuscripts in Consumer Behavior?
Authors: Shugan Steven M. 
Published: December 2003

Effectively solving problems requires proper organization. Like other academic disciplines, our discipline must organize around our fundamental problems rather than around our procedures (i.e., tools, approaches, methods). Only that organization ensures healthy debate and constructive communication on relevant research questions. Three initiatives might help foster a transition from a procedure-based to a problem-based organization. One initiative is compartmentalized reviews. Rather than only assigning reviews based on the technical procedures used in a manuscript (e.g., experiments), we assign at least one reviewer, whose expertise is in the problem domain (e.g., advertising), to review only that part of the manuscript (e.g., relevancy to advertisers). Another initiative is to avoid dichotomous certification (i.e., correct or incorrect) for procedures. All procedures yield evidence that forms a multidimensional continuum from circumstantial to overwhelming. Sometimes, precision in stating the conclusion is more important than precision in the procedure. Finally, research streams on marketing questions are essential—no one article is definitive. To foster these streams,Marketing Sciencemust encourage (to some degree) articles that expand on research previously published inMarketing Science. WhenMarketing Sciencepublishes an article, it has some obligation to give some priority to manuscripts that build on the same topic (i.e., not to label them as “incremental”).
The International Takeoff of New Products: The Role of Economics, Culture, and Country Innovativeness
Authors: Tellis Gerard J. , Stremersch Stefan , Yin Eden 
Published: December 2003

Sales takeoff is vitally important for the management of new products. Limited prior research on this phenomenon covers only the United States. This study addresses the following questions about takeoff in Europe: 1) Does takeoff occur as distinctly in other countries, as it does in the United States? 2) Do different categories and countries have consistently different times-to-takeoff? 3) What economic and cultural factors explain the intercountry differences? 4) Should managers use a sprinkler or waterfall strategy for the introduction of new products across countries? We gathered data on 137 new products across 10 categories and 16 European countries. We adapted the threshold rule for identifying takeoff (Golder and Tellis 1997) to this multinational context. We specify a parametric hazard model to answer the questions above. The major results are as follows: 1) Sales of most new products display a distinct takeoff in various European countries, at an average of six years after introduction. 2) The time-to-takeoff varies substantially across countries and categories. It is four times shorter for entertainment products than for kitchen and laundry appliances. It is almost half as long in Scandinavian countries as in Mediterranean countries. 3) While culture partially explains intercountry differences in time-to-takeoff, economic factors are neither strong nor robust explanatory factors. 4) These results suggest distinct advantages to a waterfall strategy for introducing products in international markets.
Fast Polyhedral Adaptive Conjoint Estimation
Authors: Toubia Olivier , Simester Duncan I. , Hauser John R. , Dahan Ely 
Published: December 2003

We propose and test new adaptive question design and estimation algorithms for partial profile conjoint analysis. Polyhedral question design focuses questions to reduce a feasible set of parameters as rapidly as possible. Analytic center estimation uses a centrality criterion based on consistency with respondents' answers. Both algorithms run with no noticeable delay between questions. We evaluate the proposed methods relative to established benchmarks for question design (random selection, D-efficient designs, adaptive conjoint analysis) and estimation (hierarchical Bayes). Monte Carlo simulations vary respondent heterogeneity and response errors. For low numbers of questions, polyhedral question design does best (or is tied for best) for all tested domains. For high numbers of questions, efficient fixed designs do better in some domains. Analytic center estimation shows promise for high heterogeneity and for low response errors; hierarchical Bayes for low heterogeneity and high response errors. Other simulations evaluate hybrid methods, which include self-explicated data. A field test (330 respondents) compared methods on both internal validity (holdout tasks) and external validity (actual choice of a laptop bag worth approximately $100). The field test is consistent with the simulation results and offers strong support for polyhedral question design. In addition, marketplace sales were consistent with conjoint-analysis predictions.
The Isoinversion Principle—a General Model of Chemical Selectivity
Authors: Buschmann Helmut , Scharf Hans‐Dieter , Hoffmann Norbert , Esser Peter 
Published: December 2003

AbstractA large number of successful methods for chirality transfer, using either stoichiometric or catalytic chiral auxiliaries, are in use today. However, there is a lack of practical and dynamic selectivity models, i.e. models which take into account the entire reaction sequence, and which allow simple and reliable assessment, optimization and prediction of selectivity in asymmetric syntheses. The models that are available are either too strongly biased to the steric requirement of the particular molecules reacting, but do not go beyond classical considerations of static facial differentiation, or they take a demanding, theoretical approach, which because of its inherent limitations and the great theoretical effort required has not yet found its way into the practical world of the synthetic chemist. The “Isoinversion Principle”, developed on the basis of Eyring's theory, closes this gap. With its aid, the synthetic chemist can determine the characteristic isoinversion temperature Ti for the reaction type of interest from a few temperature‐dependent measurements of selectivity parameters. Ti then affords information on interesting questions such as optimization etc. The advantage of this method is that it is useful not only for stereoselectivity, but for any kind of process where selectivity in general (regio‐,chemo‐, etc) is generated at two or more stages of a reaction sequence, regardless of whether these reactions involve the ground state or a diabatic photoprocess. The present review will demonstrate that this generation of selectivity at two or more stages of a reaction sequence occurs more commonly than is generally thought.
Strained‐Ring and Double‐Bond Systems Consisting of the Group 14 Elements Si, Ge, and Sn
Authors: Tsumuraya Takeshi , Batcheller Scott A. , Masamune Satoru 
Published: December 2003

AbstractThe organometallic chemistry of the Group 14 elements E = Si, Ge, Sn in the 1980's is highlighted by the successful construction and characterization of three systems previously thought to be too reactive to exists: (1) three‐membered ring compounds including cyclotrisilane, cyclotrigermane, and cyclotristannane, (2) molecules containing EE double bonds including disilene, digermene, and distannene, and (3) strained polycycles containing a skeleton of Group 14 elements, such as bicyclo[1.1.0]tetrasilane, hexagemaprismane, and octasilacubane. The majority of these numerous compounds now available are fully substituted with bulky ligands to suppress the reactivity intrinsic to the systems. These compounds permit examinations of (1) the variation of physical and chemical properties of a system with these elements and also with the ligands and (2) how two systems are interrelated thermally and photochemically with the intermediacy of the divalent (carbene‐like) species. Theoretical calculations on virtually all of the parent compounds discussed in this review are evaluated alongside the experimental results. Some polycycles may constitute a stepping‐stone on the way to compounds with a triple bond.
Cyclopentadienyl—Actinide Complexes: Bonding and Electronic Structure
Authors: Bursten Bruce E. , Strittmatter Richard J. 
Published: December 2003

AbstractShortly after the discovery of ferrocene, Reynolds and Wilkinson demonstrated that actinide elements are capable of forming organometallic compounds containing the cyclopentadienyl (Cp) ligand. The compound they reported, [Cp3UCl], was the first of a host of organoactinide complexes that contain Cp and substituted Cp ligands. In 1968, Streitwieser and Müller‐Westerhoff synthesized uranocene, [(C8H8)2U], a molecule whose existence had been predicted five years earlier by R. D. Fischer. Because uranocene has no analogue in transition‐metal chemistry, its synthesis stimulated new interest in organoactinide chemistry and in comparisons with organotransition‐metal chemistry. Since that time, Cp and substituted Cp ligands, such as pentamethylcyclopentadienyl (Cp*), have become the most important and flexible ligands in actinide organometallic chemistry. In the past 15 years especially, the bonding of Cp ligands to actinide elements has been extensively probed by both experiment and theory. There are both significant similarities and equally significant differences in the bonding of the Cp ligand to the f‐element metals compared to the d‐element metals.
Lipoxins and Related Eicosanoids: Biosynthesis, Biological Properties, and Chemical Synthesis
Authors: Nicolaou K. C. , Ramphal John Y. , Petasis Nicos A. , Serhan Charles N. 
Published: December 2003

AbstractAmong the various enzymes found in human tissues that act on arachidonic acid, there are three major types of lipoxygenases (LO), operating at the 5‐, 12‐, and 15‐positions. The 5‐LO is a key enzyme and plays a central role in the biosynthesis of leukotrienes, which are potent arachidonate‐derived mediators of allergy and inflammation. Because of the importance of the 5‐LO‐derived products in human pathophysiology, studies were initiated to examine the consequences of initial lipoxygenation at C15 of arachidonic acid as well as to probe interactions between the major LO pathways. These studies led to the identification of a new series of biologically active tetraene‐containing eicosanoids termed lipoxins. This article summarizes the isolation, biosynthesis, and chemical synthesis of lipoxins and related systems, and reviews recent results concerning their formation and biological activities. The total synthesis of these molecules based on a new and general synthetic strategy involving palladium catalysis is reviewed. This synthetic approach has allowed the preparation of several types of acyclic eicosanoids in their naturally occurring forms which, in turn, allowed comparisons with naturally derived materials and enabled detailed studies of the biological actions of these biomolecules. Structure–activity relationships were also derived by combining chemical synthesis and biological investigations.
Alkynyl‐ and Alkenyl(phenyl)iodonium Compounds. New Synthetic Methods (86)
Authors: Stang Peter J. 
Published: December 2003

AbstractCompounds with highly coordinated, polyvalent main‐group elements represent an interesting alternative to the many well‐known transition‐metal complexes. Among the oldest and best known stable examples of such organic molecules are the iodine(III) compounds. Diaryliodonium species, Ar2IX, for example, have been known for over a hundred years and play an important role in lithography. Likewise, acetylenes and olefins are among the oldest, most important, and most valuable compounds in chemistry. Besides simple hydrocarbon alkenes and alkynes, numerous functionalized derivatives are also known and widely employed in organic chemistry. Despite the ubiquity and prominance of both IIII species and olefins and acetylenes, the combination of these two types of functional groups in a single molecular unit, namely compounds with polyvalent iodine and at least one alkyne or olefin residue, was unknown until recently. The successful preparations of simple alkynyl‐ and alkenyl‐(phenyl)iodonium species during the 1980s has resulted in a renaissance in both acetylene and IIII chemistry. These alkynyliodonium compounds readily undergo nucleophilic substitution on the alkyne moiety (SN‐A reactions) which are difficult with other substrates. The application of a wide variety of nucleophiles in this reaction resulted in diverse functionalized alkynes including previously unknown acetylenic carboxylates, sulfonates, and phosphates. These are excellent substrates for cycloaddition reactions as well as numerous other interesting chemical transformations.
Natural Products as Probes of Cellular Function: Studies of Immunophilins
Authors: Rosen Michael K. , Schreiber Stuart L. 
Published: December 2003

AbstractOne of the great mysteries of cell biology remains the mechanism of information transfer, or signaling, through the cytoplasm of the cell. Natural products that inhibit this process offer a unique window into fundamental aspects of cytoplasmic signal transduction, the means by which extracellular molecules influence intracellular events. Thus, natural products chemistry, including organic synthesis, conformational analysis, and methods of structure elucidation, is a powerful tool in the study of cell function. This article traces our understanding of a group of natural products from the finding that they inhibit cytoplasmic signaling to their current recognition as mediators of the interaction between widely distributed protein targets. The emphasis of the discussion is primarily structural. The interactions between the natural‐product ligands and their protein receptors are analyzed at a molecular level in order to shed light on the molecular mechanisms of the biological functions of these compounds. In the process we hope to illustrate the power of chemical analysis as applied to biological systems. Through chemistry we can understand the molecular basis of biological phenomena.
The Enchanting Alkaloids of Yuzuriha
Authors: Heathcock Clayton H. 
Published: December 2003

AbstractThe oriental plant Yuzuriha (Daphniphyllum macropodum) elaborates a fascinating family of polycyclic, squalene‐derived alkaloids that provide a test for state‐of‐the‐art methods of organic synthesis. The intriguing structures of these natural products have inspired us to design and explore two rather different approaches for their laboratory synthesis. This article recounts and contrasts these two different syntheses. The first approach was based on a method of synthetic design that emphasizes efficient construction of the polycyclic skeleton of the molecule (Corey's “network analysis”). A strategic bond was identified and the synthesis planned around the late formation of this bond. The synthesis that was designed by this approach proceeded smoothly until the point where it was necessary to remove functional groups that had been incorporated solely for the purpose of forming the strategic bond. Although the problems were eventually overcome, the resulting synthesis was too long and did not control the configuration of one of the stereocenters. The second approach was based on a possible biosynthesis of one of the alkaloids and provided surprisingly easy access to the simpler members of the family. The success of this synthesis led to a concrete proposal about the biosynthesis of the alkaloids and to the discovery of the astonishing transformation depicted in Scheme 27. In this marvelous reaction, an acyclic squalene derivative is converted by successive treatment with ordinary commodity chemicals into a pentacyclic alkaloid. The transformation involves the formation of four carbon–carbon bonds, two carbon‐nitrogen bonds, and one carbon‐hydrogen bond!
Nitrido Complexes of Transition Metals
Authors: Dehnicke Kurt , Strähle Joachim 
Published: December 2003

AbstractIn the past decade new syntheses and numerous structural determinations have enlivened studies in the still relatively young field of nitrido‐transition‐metal complexes. Aside from the terminal function of the nitrido ligand MN:, this group also occurs as linear μ2‐bridging ligand in symmetric and asymmetric coordination; examples are known with almost right‐angled bridge function; and, finally, it also functions as μ3‐bridging ligand. Accordingly, the fresh impulses given to synthetic chemistry by nitrido complexes are also many‐sided: such complexes are used, inter alia, for the preparation of phosphaniminato and thionitrosyl complexes as well as for the synthesis of metallaheterocycles of the type MN3S2 and MN3P2 with delocalized π‐systems. In technetium chemistry complexes with terminal nitrido group are employed as radiopharmaceuticals, and, owing to the strong trans influence of the MN: group, nitrido complexes of molybdenum are suitable as catalysts in olefin metathesis. Finally, nitrido complexes are also of wide interest in theoretical studies.
Scanning Tunneling Microscopy and Atomic Force Microscopy in Organic Chemistry
Authors: Frommer Jane 
Published: December 2003

AbstractWhen Kekulé awoke from dreams of snakes biting their own tails, he didn't have the benefit of a scanning tunneling microscope (STM) image to confirm that his vision of benzene as a cyclic molecule was accurate. References to STM in the chemical literature increase steadily, although the technique was perhaps oversold in its early days of the 1980s, with such promises as DNA sequencing and tailored bi‐molecular chemical reactions (literally, two molecules). Publications alternate between attempting to explain the process by which images of traditional insulators are obtained and simply presenting the end images themselves as stunning views of atoms and molecules. While imaging mechanisms are still being debated, these instruments' ability to “see” single molecules has been established, albeit at the fringes of our expectations. For example, whereas STM studies at present might not be able to answer the question of why adsorption of CO doubles the density of platinum atoms on the surface of a single crystal of the metal, the images go far in illustrating that this is a process which platinum undergoes. As with any emerging analytical tool, these scanning, very localized microscopic methods are undergoing the growing pains of irreproducible results and mis‐marketed artifacts. Nonetheless, we assemble here, primarily for the uninitiated, a collection of careful and credible studies to mark the progress of scanning tunneling microscopy and atomic force microscopy into chemistry, and to encourage a healthy blend of idealism and skepticism toward future work.
The Photochemistry of Stilbenoid Compounds and Their Role in Materials Technology
Authors: Meier Herbert 
Published: December 2003

AbstractStilbenes and compounds containing stilbene units in their structures form the material basis for numerous research projects in photophysics and photochemistry. Moreover, because these compounds are easy to synthesize and are thermally and chemically stable, they are taking on an increasingly prominent role in the area of materials science investigations into optical, electrical, and optoelectronic properties. In accordance with the interdisciplinary nature of such studies, this article aims to provide a bridge extending from molecular theory and photophysical measurements, through preparative applications, to material effects and their potential technical applications.
Cubanes: Starting Materials for the Chemistry of the 1990s and the New Century
Authors: Eaton Philip E. 
Published: December 2003

AbstractThe study of non‐natural products has led to a broad understanding of bonding and reactivity in organic chemistry. Many times, compounds thought impossible have been realized in the course of such studies. Cubane, a landmark in the world of “impossible” compounds, has been found to have a rich chemistry, full of the unexpected. The recent renaissance of cubane chemistry, triggered by potential applications of the system to the production of high‐energy fuels and the like, has led to many discoveries including the first methods for systematic substitution on strained, saturated systems and a new process for the metalation of arenes, ortho magnesiation. Reactive intermediates with exceptional bonding parameters have been uncovered and characterized including 1(9)‐homocubene, the most twisted olefin; cubene, the most pyramidalized olefin; cubyl cation, once the “least likely” cation; cubylmethyl radical, a saturated radical that rearranges on the picosecond timescale; and many other extraordinary species. There is certainly good reason to believe that future work in the cubane arena will be at least as productive (probably more so), and that it will help develop a deeper understanding of chemistry.