bluuebunny/crossref_metadata_2025 huggingface dataset:
Syntheses, Structures and Photoluminescence Properties of Ag(I), Cu(II), Zn(II) and Mn(II) Complexes with N,N′-Bis(3-pyridylmethyl)-1,4-benzenedimethyleneimine
Authors: Zhu Hui-Fang , Li Ling , Okamura Taka-aki , Zhao Wei , Sun Wei-Yin , Ueyama Norikazu
Published: April 2003

Four novel coordination complexes, [Ag(bpb)]NO3·2H2O (1), [Cu2(CH3COO)4(bpb)] (2), [ZnCl2(bpb)2] (3) and [MnCl2(bpb)2] (4) [bpb = N,N′-bis(3-pyridylmethyl)-1,4-benzenedimethyleneimine], with one-dimensional chain structures were synthesized and their structures were determined by X-ray crystallography. A structure analysis revealed that the bpb acts as a bridging ligand using two pyridyl N atoms to link two metal atoms, while the two imine N atoms do not participate in the coordination with the metal atoms. The photoluminescence properties of the title complexes were also studied. Although Cu(II) (2) and Zn(II) (3) complexes show intense violet-blue photoluminescence, no clear photoluminescence was observed for the Ag(I) (1) and Mn(II) (4) complexes.
Preparation and Characterization of Lamellar Vanadyl Alkylphosphates as Catalyst Precursors for the Selective Oxidation of Butane
Authors: Kamiya Yuichi , Nishikawa Eiichiro , Satsuma Atsushi , Okuhara Toshio
Published: April 2003

Vanadyl alkylphosphates consisting of V4+ and P5+ were synthesized by the reaction of a solid mixture of V2O5 and V4O9 (2:3 in mol) with P2O5 in primary aliphatic (from C1 to C8), secondary aliphatic (C3 and C4), and alicyclic (C5) alcohols, and were characterized by means of elemental analysis, thermogravimetric analysis, X-ray diffraction, IR spectroscopy, and magnetic susceptibility. The chemical formulae of the products were determined to be VO(RO)x(HO)1−xPO3·(ROH)y (x = 0.5–0.7, y = 0.3–0.5 for primary aliphatic alcohols; x = 0.1–0.2, y = 0.4–0.9 for secondary aliphatic and alicyclic alcohols; and R = organic group). X-ray diffraction revealed that the compounds had a lamellar structure, where the organic groups existed as double layers with a tilt of about 56° against the basal plane. Magnetism and IR spectroscopy demonstrated that the construction of the basal planes in the vanadyl alkylphosphates was similar to that of VOHPO4·0.5H2O, which consists of V4+ dimers linked with PO4, except for vanadyl sec-butylphosphate, consisting of isolated V4+ monomers. Calcination of vanadyl methylphosphate and vanadyl cyclopentylphosphate brought about crystallites of (VO)2P2O7. These (VO)2P2O7 exhibited high selectivities to maleic anhydride (65–68%) for the selective oxidation of butane under a high concentration of butane (5.0%).
In utero transmission of Encephalitozoon cuniculi strain type I in rabbits
Authors: Baneux P. J. R. , Pognan F.
Published: April 2003

Pregnant rabbits were serologically diagnosed as having been infected with Encephalitozoon cuniculi. At necropsy at 28 days of gestation, does, placentas and fetuses were found to be infected with E. cuniculi strain type I as evidenced by using the nested-polymerase chain reaction (PCR) technique, thereby confirming vertical transplacental transmission.
A long-term porcine model for measurement of gastrointestinal motility
Authors: Schnoor Joerg , Bartz Stefanie , Klosterhalfen Bernd , Kuepper Werner , Rossaint Rolf , Unger Juliane K.
Published: April 2003

Animal models have become an essential tool in the investigations of gut motility under experimental conditions. To determine the influence of various anaesthetic drugs on the motility pattern of the gastroduodenal tract, a new long-term model has had to be developed for allowing measurements in conscious and unrestrained as well as in sedated and analgosedated pigs. Since mechanical ventilation influences gut motility, it was necessary that this animal model enabled the investigation of the effect of drugs causing sedation and analgosedation during spontaneous breathing. Seven male, castrated pigs, German landrace, 32–40 kg bodyweight (BW) were investigated in this study. After habituation of the pigs to local housing conditions over 5 days, the animals were trained over 4 days to prepare for experimental situations and investigators. Pigs were inserted with a central venous catheter and with percutaneous enterogastrostomy (PEG) under general anaesthesia. Intestinal motility was measured by intraluminal impedancometry. The catheter was introduced over the PEG into the stomach and positioned into the duodenum by duodenoscopy. Measurements were done in conscious, unrestrained pigs and with sedated, and analgosedated animals on subsequent days. The habituation and training of the pigs to the investigators and for the laboratory conditions took between 7 and 9 days. The initial anaesthesia protocol for the instrumentation using remifentanil/propofol led to pyloric spasm and was thus unsuitable for duodenal intubation with an endoscope. In contrast, a combination of ketamine/propofol enabled this procedure. It was practicable to measure gut motility in conscious, unrestrained pigs. Spontaneous breathing was sufficient under propofol sedation and analgosedation using fentanyl-propofol. Systematically local application of polividon iodine in the area of the subcutaneous catheters avoided the necessity of using systemic prophylactic antibiotics. In conclusion, the habituation and training for 9 days enabled the measurement of gut motility by intraluminal impedancometry in conscious pigs. The insertion of the catheter was done during general anaesthesia using a combination of propofol and ketamine. For the future determination of gut motility performed under general anaesthesia, each sedation and analgosedation concept has to be evaluated to see whether it allows spontaneous breathing or whether mechanical ventilation is necessary.
Effects of the anaesthetic/tranquillizer treatments on selected plasma biochemical parameters in NZW rabbits
Authors: González Gil A. , Illera J. C. , Silván G. , Illera M.
Published: April 2003

In order to assess the response of plasma biochemical parameters to anaesthesia, 40 New Zealand White (NZW) rabbits were assigned to four treatment groups ( n = 10): control (1 ml i.v. saline solution), fentanyl-droperidol (FD) (0.4 ml/kg s.c. of 'thalamonal' solution; 2.5 mg/ml droperidol, 0.05 mg/ml fentanyl), ketamine (K) (10 mg/kg i.v.) with either xylazine (X) (3 mg/kg i.v.) or diazepam (D) (2 mg/kg i.v.). Blood samples were obtained from the central ear artery at six time points: before injection, and at 10, 30, 60, 120 min and 24 h after injection of the anaesthetics/saline. Plasma ALT, AST, ALP, GGT, BUN, creatinine, phosphate and potassium levels were measured by the Hitachi 747 autoanalyser. The administration of K-X increased ( P < 0.05) plasma ALT (from 11.4 ± 0.9 to 20.2 ± 1.7 IU/l, at 10 min), AST (from 10.5 ± 3.3 to 34 ± 2.1 IU/l, at 120 min), BUN (from 17.2 ± 0.9 to 25.8 ± 1.8 mg/dl, at 60 min) and creatinine concentrations (from 1 ± 0.1 to 1.6 ± 0.2 mg/dl, at 10 min). After K-D administration, we observed an increase ( P < 0.05) in plasma ALT (from 11.4 ± 0.9 to 20.2 ± 1.1 IU/l, at 10 min), AST (from 11.4 ± 1.6 to 28 ± 3.7 IU/l, at 10 min), BUN (from 15.8 ± 0.8 to 30 ± 1.5 mg/dl, at 10 min) and creatinine levels (from 1 ± 0.08 to 2.2 ± 0.2 mg/dl, at 120 min). No significant changes were seen in the FD group. We conclude that K-X and K-D may affect plasma concentration of select serum enzymes and biochemical parameters. These results should be taken into account when blood samples are evaluated in treated rabbits.
Assessing the Construct Validity of Risk Attitude
Authors: Pennings Joost M.E. , Smidts Ale
Published: April 2003

Two major approaches to measuring risk attitude are compared. One, based on the expected utility model is derived from responses to lotteries and direct scaling. The other measure is a psychometric approach based on Likert statements that produces a unidimensional risk attitude scale. The data are from computer-assisted interviews of 346 Dutch owner-managers of hog farms, who made decisions about their own businesses. While the measures demonstrate some degree of convergent validity, those measures based on lotteries were better predictors of actual market behavior. In contrast the psychometric scale showed more agreement to selfreported measures of innovativeness, market orientation, and the intention to reduce risk. In light of the higher predictive validity of lottery-based measurements, werecommend elicitation methods based on the expected utility paradigm.
Efficient Supply Contracts for Fashion Goods with Forecast Updating and Two Production Modes
Authors: Donohue Karen L.
Published: April 2003

We examine the problem of developing supply contracts that encourage proper coordination of forecast information and production decisions between a manufacturer and distributor of high fashion, seasonal products operating in a two-mode production environment. The first production mode is relatively cheap but requires a long lead time while the second is expensive but offers quick turnaround. We focus on contracts of the form (w1, w2, b) where wi is the wholesale price offered for production mode i and b is a return price offered for items left over at the end of the season. We find that such a contract can coordinate the manufacturer and distributor to act in the best interest of the channel. The pricing conditions needed to ensure an efficient solution vary depending on the degree of demand forecast improvement between periods and the manufacturer's access to forecast information. We also examine whether these conditions ensure a Pareto optimal solution with respect to two traditional production settings.
Inducing Performance in a Queue via Prices: The Case of a Riverine Port
Authors: Dasgupta Ani , Ghosh Madhubani
Published: April 2003

To optimize large-scale queuing systems configurations, OR professionals typically use discrete event simulation packages to examine in detail the movement of entities through such systems, assuming stochastic but fixed arrival patterns. Demand aspects are, however, routinely ignored as few attempts are made to capture the feedback effect of queue performance on the arrival process. Econometricians, on the other hand, use a simultaneous equations estimation approach relying on past data, but they typically disregard the technological insights provided by simulation. This paper combines both tools to study the ailing port system of Calcutta, India, and concludes that raising prices will improve both economic and engineering performances. Microeconomic models of shipowner behavior are constructed to explain the nature of the empirical findings. Finally, full-equilibrium demand elasticities are calculated using the dual prices from an appropriate nonlinear program, which are then compared to the benchmark value expected of profit-maximizing behavior.
Information and Incentive Effects of Inventory in JIT Production
Authors: Alles Michael , Amershi Amin , Datar Srikant , Sarkar Ratna
Published: April 2003

This paper provides an economic rationale for modern manufacturing control practices such as the minimal inventories in Just in Time (JIT)systems, zero-defect policies, and continuous improvement. The popular and academic literature contains descriptive studies on the mechanics of these systems and their perceived benefits. We use a model of production to analyze both informational and incentive rationales for reduced inventories. A JIT-like environment of low inventory levels is optimal in our model because it helps workers to better observe and understand the production process and to think and act creatively to improve operational reliability and yields. Empirical evidence using data obtained from 116 plants worldwide supports our conclusions about the effect of reduced inventories on process reliability, product quality, and cost.
Optimal Models for Meal-Break and Start-Time Flexibility in Continuous Tour Scheduling
Authors: Brusco Michael J. , Jacobs Larry W.
Published: April 2003

This paper presents a compact integer-programming model for large-scale continuous tour scheduling problems that incorporate meal-break window, start-time band, and start-time interval policies. For practical scheduling environments, generalized set-covering formulations (GSCFs) of such problems often contain hundreds of millions of integer decision variables, usually precluding identification of optimal solutions. As an alternative, we present an implicit integer-programming model that frequently has fewer than 1,500 variables and can be formulated and solved using PC-based hardware and software platforms. An empirical study using labor-requirement distributions for customer service representatives at a Motorola, Inc. call center was used to demonstrate the importance of having a model that can evaluate tradeoffs among the various scheduling policies.
Stock Replenishment and Shipment Scheduling for Vendor-Managed Inventory Systems
Authors: Çetinkaya Sila , Lee Chung-Yee
Published: April 2003

Vendor-managed inventory (VMI) is a supply-chain initiative where the supplier is authorized to manage inventories of agreed-upon stock-keeping units at retail locations. The benefits of VMI are well recognized by successful retail businesses such as Wal-Mart. In VMI, distortion of demand information (known as bullwhip effect) transferred from the downstream supply-chain member (e.g., retailer) to the upstream member (e.g., supplier) is minimized, stockout situations are less frequent, and inventory-carrying costs are reduced. Furthermore, a VMI supplier has the liberty of controlling the downstream resupply decisions rather than filling orders as they are placed. Thus, the approach offers a framework for synchronizing inventory and transportation decisions.

In this paper, we present an analytical model for coordinating inventory and transportation decisions in VMI systems. Although the coordination of inventory and transportation has been addressed in the literature, our particular problem has not been explored previously. Specifically, we consider a vendor realizing a sequence of random demands from a group of retailers located in a given geographical region. Ideally, these demands should be shipped immediately. However, the vendor has the autonomy of holding small orders until an agreeable dispatch time with the expectation that an economical consolidated dispatch quantity accumulates. As a result, the actual inventory requirements at the vendor are partly dictated by the parameters of the shipment-release policy in use. We compute the optimum replenishment quantity and dispatch frequency simultaneously. We develop a renewaltheoretic model for the case of Poisson demands, and present analytical results.
Preference Factoring for Stochastic Trees
Authors: Hazen Gordon
Published: April 2003

Stochastic trees are extensions of decision trees that facilitate the modeling of temporal uncertainties. Their primary application has been to medical treatment decisions. It is often convenient to present stochastic trees in factored form, allowing loosely coupled pieces of the model to be formulated and presented separately. In this paper, we show how the notion of factoring can be extended as well to preference components of the stochastic model. We examine updateable-state utility, a flexible class of expected utility models that permit stochastic trees to be rolled back much in the manner of decision trees. We show that preference summaries for updateable-state utility can be factored out of the stochastic tree. In addition, we examine utility decompositions which can arise when factors in a stochastic tree are treated as attributes in a multiattribute utility function.
A Decomposition-Based Pricing Procedure for Large-Scale Linear Programs: An Application to the Linear Multicommodity Flow Problem
Authors: Mamer John W. , McBride Richard D.
Published: April 2003

We propose and test a new pricing procedure for solving large-scale structured linear programs. The procedure interactively solves a relaxed subproblem to identify potential entering basic columns. The subproblem is chosen to exploit special structure, rendering it easy to solve. The effect of the procedure is the reduction of the number of pivots needed to solve the problem. Our approach is motivated by the column-generation approach of Dantzig-Wolfe decomposition. We test our procedure on two sets of multicommodity flow problems. One group of test problems arises in routing telecommunications traffic and the second group is a set of logistics problem which have been widely used to test multicommodity flow algorithms.
A Note on Assemble-to-Order Systems with Batch Ordering
Authors: Song Jing-Sheng
Published: April 2003

We study an assemble-to-order inventory system. The stocks are held for components, with final products assembled only when customer orders are realized. Customer orders form a multivariate compound Poisson process, component replenishment leadtimes are constant, and demands in excess of inventory on hand are backlogged. The component inventories are controlled by (R, nQ) policies. We show that under certain general conditions the inventory position vector has a uniform equilibrium distribution. This result generalizes the corresponding single-item theory considerably. It allows us to express the key performance measures of the system, such as order fill rates and average order-based backorders, as the averages of their counterparts in the base-stock systems.
Convex Input and Output Projections of Nonconvex Production Possibility Sets
Authors: Bogetoft Peter , Tama Joseph M. , Tind Jørgen
Published: April 2003

In this paper we characterize the smallest production possibility set that contains a specified set of (input, output) combinations. In accordance with neoclassical production economics, this possibility set has convex projections into the input and output spaces (convex isoquants), and it satisfies the assumption of free disposability. We obtain it by means of a possibly infinite recursion which builds the possibility set as an ever larger union of convex sets. We remark on the nature of the approximations obtained by truncating the recursion, and we obtain a necessary and sufficient condition, checkable in one iteration for the recursion to stop in the next. For the case in which the recursion stops, we provide a succinct characterization of the dominance relations among the constituent sets produced by the procedure. Finally, we present examples of both finite and infinite cases. The example for the finite case illustrates the construction of the possibility set along with its associated production and consumption sets.
A New Algebraic Geometry Algorithm for Integer Programming
Authors: Bertsimas Dimitris , Perakis Georgia , Tayur Sridhar
Published: April 2003

We propose a new algorithm for solving integer programming (IP) problems that is based on ideas from algebraic geometry. The method provides a natural generalization of the Farkas lemma for IP, leads to a way of performing sensitivity analysis, offers a systematic enumeration of all feasible solutions, and gives structural information of the feasible set of a given IP. We provide several examples that offer insights on the algorithm and its properties.
Decentralizing Cross-Functional Decisions: Coordination Through Internal Markets
Authors: Kouvelis Panagiotis , Lariviere Martin A.
Published: April 2003

A firm faces many problems that are inherently cross-functional. To solve them successfully requires the coordinated actions of many functional representatives acting in a decentralized setting. Functional managers, however, respond to their own individual incentives and may consequently fail to maximize the overall profits of the firm. We examine this issue in a setting in which the output of early actions limits the range of later actions, and we propose an incentive scheme that allows the system to be successfully decentralized. Our mechanism is based on linear transfer prices for the intermediate output that are implemented through an internal market; a market maker buys the output from one function and sells it to another. She is not obliged to sell at the same price at which she bought and may set prices solely to provide incentives. We illustrate the flexibility of the scheme by applying it to several models in the operations management literature.
Generic Convergence of Descent Methods in Banach Spaces
Authors: Reich Simeon , Zaslavski Alexander J.
Published: April 2003

Given a continuous convex function f on a Banach space X, we consider a complete metric space of vector fields V on X with the topology of uniform convergence on bounded subsets. With each such vector field we associate two iterative processes. We show that for a generic V the values of the function f tend to its infimum for both processes.
Multimodularity, Convexity, and Optimization Properties
Authors: Altman Eitan , Gaujal Bruno , Hordijk Arie
Published: April 2003

In this paper we investigate the properties of multimodular functions. In doing so we give elementary proofs for properties already established by Hajek and we generalize some of his results. In particular, we extend the relation between convexity and multimodularity to some convex subsets of ℤm. We also obtain general optimization results for average costs related to a sequence of multimodular functions rather than to a single function. Under this general context, we show that the expected average cost problem is optimized by using regular sequences. We finally illustrate the usefulness of this theory in admission control into a D/D/1 queue with fixed batch arrivals, with no state information. We show that the regular policy minimizes the average queue length for the case of an infinite queue, but not for the case of a finite queue. When further adding a constraint on the losses, it is shown that a regular policy is also optimal for the finite queue case.
Nonsymmetric Values of Nonatomic and Mixed Games
Authors: Haimanko Ori
Published: April 2003

This paper presents a new unifying approach to the study of nonsymmetric (or quasi-) values of nonatomic and mixed games. A family of path values is defined, using an appropriate generalization of Mertens diagonal formula. A path value possesses the following intuitive description: consider a function (path) γ attaching to each player a distribution function on [0, 1]. We think of players as arriving randomly and independently to a meeting when the arrival time of a player is distributed according to γ. Each player's payoff is defined as his marginal contribution to the coalition of players that have arrived earlier.

Under certain conditions on a path, different subspaces of mixed games (pNA, pM, bv′FL) are shown to be in the domain of the path value. The family of path values turns out to be very wide—we show that on pNA, pM and their subspaces the path values are essentially the basic construction blocks (extreme points) of quasi-values.
Periodic Orbits in a Class of Re-Entrant Manufacturing Systems
Authors: Diaz-Rivera Ivonne , Armbruster Dieter , Taylor Tom
Published: April 2003

Queue changes associated with each step of a manufacturing system are modeled by constant vector fields (fluid model of a queueing network). Observing these vector fields at fixed events reduces them to a set of piecewise linear maps. It is proved that these maps show only periodic or eventually periodic orbits. An algorithm to determine the period of the orbits is presented. The dependence of the period on the processing rates is shown for a 3(4)-step, 2-machine problem.
On Dantzig-Wolfe Decomposition in Integer Programming and ways to Perform Branching in a Branch-and-Price Algorithm
Authors: Vanderbeck François
Published: April 2003

Dantzig-Wolfe decomposition as applied to an integer program is a specific form of problem reformulation that aims at providing a tighter linear programming relaxation bound. The reformulation gives rise to an integer master problem, whose typically large number of variables is dealt with implicitly by using an integer programming column generation procedure, also known as branch-and-price algorithm. There is a large class of integer programs that are well suited for this solution technique. In this paper, we propose to base the Dantzig-Wolfe decomposition of an integer program on the discretization of the integer polyhedron associated with a subsystem of constraints (as opposed to its convexification). This allows us to formulate the integrality restriction directly on the master variables and sets a theoretical framework for dealing with specific issues such as branching or the introduction of cutting planes in the master. We discuss specific branching schemes and their effect on the structure of the column generation subproblem. We give theoretical bounds on the complexity of the separation process and the extent of the modifications to the column generation subproblem. Our computational tests on the cutting stock problem and a generalisation—the cutting strip problem—show that, in practice, all fractional solutions can be eliminated using branching rules that preserve the tractability of the subproblem, but there is a trade-off between branching efficiency and subproblem tractability.
Finite Horizon Stochastic Knapsacks with Applications to Yield Management
Authors: Van Slyke Richard , Young Yi
Published: April 2003

The finite horizon stochastic knapsack combines a secretary problem with an integer knapsack problem. It is useful for optimizing sales of perishable commodities with low marginal costs to impatient customers. Applications include yield management for airlines, hotels/motels, broadcasting advertisements, and car rentals. In these problems, K types of customers arrive stochastically. Customer type, k, has an integer weight wk, a value bk, and an arrival rate λk(t) (which depends on time). We consider arrivals over a continuous time horizon [0; T] to a “knapsack” with capacity W. For each arrival that fits in the remaining knapsack capacity, we may (1) accept it, receiving bk, while giving up capacity wk; or (2) reject it, forgoing the value and not losing capacity. The choice must be immediate; a customer not accepted on arrival is lost. We model the problem using continuous time, discrete state, finite horizon, dynamic programming. We characterize the optimal return function and the optimal acceptance strategy for this problem, and we give solution methods. We generalize to multidimensional knapsack problems. We also consider the special case where wk= 1 for all k. This is the classic airline yield problem. Finally, we formulate and solve a new version of the secretary problem.
Separability in Optimal Allocation
Authors: Fox Bennet L.
Published: April 2003

The optimal allocation for stratification, parameterized by the respective sampling strategy to use in each stratum, is derived directly from the notion of efficiency. Especially with simulation, there are often opportunities to maximize efficiency (myopically) within each stratum. To maximize efficiency globally, first maximize the efficiency of the sampling strategy for each stratum separately and then use the optimal allocation given these respective maximizers. Given any other allocation, maximizing the efficiency of the sampling strategy in each stratum separately does not give the highest efficiency attainable with that allocation except in degenerate cases. Given a class 𝒞 of deterministic rounding strategies, the rounding of the (continuous) optimal allocation over 𝒞, which maximizes efficiency, cannot be improved by a strategy that randomizes over 𝒞.
Minimizing Cycle Time in a Blocking Flowshop
Authors: Abadi I.N. Kamal , Hall Nicholas G. , Sriskandarajah Chelliah
Published: April 2003

We consider a blocking (i.e., bufferless) flowshop that repetitively processes a minimal part set to minimize its cycle time, or equivalently to maximize its throughput rate. The best previous heuristic procedure solves instances with 9 machines and 25 jobs, with relative errors averaging about 3% but sometimes as much as 10%. The idea of deliberately slowing down the processing of operations (i.e., increasing their processing times) establishes a precise mathematical connection between this problem and a no-wait flowshop. This enables a very effective heuristic for the no-wait flowshop to be adapted as a heuristic for the blocking flowshop. Our computational results show relative errors that average less than 2% for instances with 20 machines and 250 jobs.
Lagrangian Solution Techniques and Bounds for Loosely Coupled Mixed-Integer Stochastic Programs
Authors: Takriti Samer , Birge John R.
Published: April 2003

Many production problems involve facility setups that lead to integer variables, production decisions that are continuous, and demands that are likely to be random. While these problems can be quite difficult to solve, we propose a model and an efficient solution technique for this basic class of stochastic mixed-integer programs. We use a set of scenarios to reflect uncertainty. The resulting mathematical model is solved using Lagrangian relaxation. We show that the duality gap of our relaxation is bounded above by a constant that depends on the cost function and the number of branching points in the scenario tree. We apply our technique to the problem of generating electric power. Numerical results indicate significant savings when the stochastic model is used instead of a deterministic one.
Time-Cost Trade-Offs in Overlapped Product Development
Authors: Roemer Thomas A. , Ahmadi Reza , Wang Robert H.
Published: April 2003

Increasingly shorter product life cycles impel firms to design, develop, and market more products in less time than ever before. Overlapping of design and development stages is commonly regarded as the most promising strategy to reduce product development times. However, overlapping typically requires additional resources and can be costly.

Our research addresses the trade-off between product development time and costs and introduces an algorithm to determine an appropriate overlapping strategy under different scenarios. The methodology developed was successfully employed at Rocketdyne Division of Rockwell International.
Several Results on the Design of Queueing Systems
Authors: Chao Xiuli , Scott Carlton
Published: April 2003

Given that the total service effort in a multiple-server environment is fixed, it is generally known that the single-server system yields the minimum time a customer spends in the system. However, in many manufacturing as well as service applications the waiting time in the queue is more significant than total time in the system. We consider several such queueing design problems and show that the results for minimizing the waiting time in the queue are markedly different from those for minimizing total time in the system.
Balancing Act: Learning from Organizing Practices in Cultural Industries
Authors: Lampel Joseph , Lant Theresa , Shamsie Jamal
Published: April 2003

The dilemmas experienced by managers in cultural industries are also to be found in a growing number of other industries where knowledge and creativity are key to sustaining competitive advantage. Firms that compete in cultural industries must deal with a combination of ambiguity and dynamism, both of which are intrinsic to goods that serve an aesthetic or expressive rather than a utilitarian purpose. Managers involved with the creation, production, marketing, and distribution of cultural goods must navigate tensions that arise from opposing imperatives that result from these industry characteristics. In this paper we outline five polarities that are shaping organizational practices in cultural industries. First, managers must reconcile expression of artistic values with the economics of mass entertainment. Second, they must seek novelty that differentiates their products without making them fundamentally different in nature from others in the same category. Third, they must analyse and address existing demand while at the same time using their imagination to extend and transform the market. Fourth, they must balance the advantages of vertically integrating diverse activities under one roof against the need to maintain creative vitality through flexible specialization. And finally, they must build creative systems to support and market cultural products but not allow the system to suppress individual inspiration, which is ultimately at the root of creating value in cultural industries.
Dyadic Communication Relationships in Organizations: An Attribution/Expectancy Approach
Authors: Barry Bruce , Crant J. Michael
Published: April 2003

Research in organizational communication has examined the structure and content of interaction, but has paid little attention to research traditions outside the organizational sciences that explore the social-psychological interconnections between relationship development and interaction. In this paper we draw upon and extend those traditions to develop a model of how communication relationships develop within organizational dyads. The proposed model examines organization-based communication relationships through a synthesis of theoretical perspectives on communication richness, relational communication, interpersonal attribution, and social expectancy. We also call upon precepts of structuration theory to embed these microlevel processes in an organizational context.

The relational outcome in the model is “interactional richness,” a dyad-level construct that assesses the extent to which communication within the dyad is high in shared meaning. Model antecedents are aspects of interaction through which communicators reciprocally define their relationships, including relational message properties, message patterns that emerge over time, and relational perceptions. We propose that these communication properties and behaviors give rise to relationship attributions. We then incorporate processes of expectancy confirmation and violation to explain how specific communication encounters lead individuals to reformulate attributions regarding the status of a given relationship. Research propositions articulate how attribution/expectancy processes mediate between relational communication behavior and relationship development outcomes. We also develop propositions addressing how relational communication behavior is influenced by macrolevel factors, including hierarchy, structure, and culture.

In a concluding section we discuss the model's potential contribution to research and practice, address its limitations, and offer recommendations for future research aimed at testing its embedded hypotheses.
Screening and Management of Adult Hearing Loss in Primary Care
Authors: Yueh Bevan , Shapiro Nina , MacLean Catherine H. , Shekelle Paul G.
Published: April 2003

Context

Hearing loss is the third most prevalent chronic condition in olderadults and has important effects on their physical and mental health. Despitethese effects, most older patients are not assessed or treated for hearingloss.

Objective

To review the evidence on screening and management of hearing loss ofolder adults in the primary care setting.

Data Sources and Study Selection

We performed a search from 1985 to 2001 using MEDLINE, HealthSTAR, EMBASE,Ageline, and the National Guideline Clearinghouse for articles and practiceguidelines about screening and management of hearing loss in older adults,as well as reviewed references in these articles and those suggested by expertsin hearing impairment.

Data Extraction

We reviewed articles for the most clinically important information,emphasizing randomized clinical trials, where available, and identified 1595articles.

Data Synthesis

Screening tests that reliably detect hearing loss are use of an audioscope,a hand-held combination otoscope and audiometer, and a self-administered questionnaire,the Hearing Handicap Inventory for the Elderly-Screening version. The valueof routine screening for improving patient outcomes has not been evaluatedin a randomized clinical trial. Screening is endorsed by most professionalorganizations, including the US Preventive Services Task Force. While mosthearing loss in older adults is sensorineural and due to presbycusis, cerumenimpaction and chronic otitis media may be present in up to 30% of elderlypatients with hearing loss and can be treated by the primary care clinician.In randomized trials, hearing aids have been demonstrated to improve outcomesfor patients with sensorineural hearing loss. Nonadherence to use of hearingaids is high. Prompt recognition of potentially reversible causes of hearingloss, such as sudden sensorineural hearing loss, is important to maximizethe possibility of functional recovery.

Conclusion

While untested in a clinical trial, older adults can be screened forhearing loss using simple methods, and effective treatments exist and areavailable for many forms of hearing loss.
Influence of some anthropometric parameters on the risk of development of distal complications after mastectomy carried out because of breast carcinoma
Authors: Kopanski Zbigniew , Wojewoda Tomasz , Wojewoda Aleksandra , Schlegel‐Zawadzka Malgorzata , Wozniacka Renata , Suder Agnieszka , Kosciuk Tomasz
Published: April 2003

The analysis included 46 women after radical breast amputation because of cancer with which lymphoedema occurred in the upper limb, as well as 51 women in whom no lymphoedema occurred during the period of the observation. Both groups were subjected to a comparative analysis as for height, body mass, and weight–height indexes: BMI, Quetelet, Rohrer, and Pignet–Verwaeck. The results show that women with high body mass, obesity (BMI > 30.0), and high values of the Quetelet (>370), Rohrer (>1.59), and Pignet–Verwaeck (>93.1) indexes are threatened to a significant degree with lymphoedema of the upper limbs after cancer‐related mastectomy. On the other hand, slim body build and low index values appear to be a factor protecting from the occurrence of lymphoedema of the upper limb. Am. J. Hum. Biol. 15:433–439, 2003. © 2003 Wiley‐Liss, Inc.
Participation of women in Human Biology, 1975–2001
Authors: Stinson Sara
Published: April 2003

This study examines trends in women's participation in human biology as indicated by women's membership in the Human Biology Council/Association, first authorship of articles in the Human Biology Council/Association journal, and the extent to which women have been the subjects of research published in the organization's journal. Gender of members was determined from seven membership lists published in the organization's journal from 1977 to 1998, and the gender of the first authors was determined for 1,616 articles published in Human Biology or the American Journal of Human Biology from 1975 to 2001. Each journal article was also coded as to the first author's country and whether the subjects of the research were only females, only males, or both males and females. From the late 1970s to the late 1990s, the percent of women members of the Human Biology Council/Association increased from under 25% to over 40%. Women were the first authors of fewer than 20% of articles in the organization's journal in the late 1970s; by the late 1990s over 30% of articles had a female first author. The clearest increase in female authorship through time is seen for articles with a first author from the U.S. Even when women were not well represented as human biologists, a substantial proportion of human biology research published in the organization's journal dealt with females, and over the last 15 years there have been more research articles having only females as research subjects than articles having only males as research subjects. Am. J. Hum. Biol. 15:440–445, 2003. © 2003 Wiley‐Liss, Inc.
Redox recipes. X. A recipe with ferric versenate, sodium dithionite, and hydroperoxide as activating system (veroxathionite recipe)
Authors: Kolthoff I. M. , Meehan E. J.
Published: April 2003

A new initiating system, named the Veroxathionite system, for the copolymerization of butadiene (75)‐styrene (25) is described. At 0°C., with the recipe: butadiene, 75 parts; styrene, 25 parts; water, 180 parts; potassium myristate, 5 parts; potassium pyrophosphate, 1 part; sulfole mercaptan, 0.3 part; 0.66 mmole of phenylcyclohexane hydroperoxide, 0.001 M ferric versenate, and 0.1 part of sodium dithionite, conversions of 45, 87, and 100% were reached in 1, 2, and 3 hours, respectively. The rate can be varied within wide limits by changing the concentration of iron. With only 10−4 M ferric versenate and 0.06 part of dithionite, 71% conversion is attained in 12 hours. The amount of dithionite must be adjusted to the amount of hydroperoxide and, to a lesser extent, to the amount of iron. With much more than one mole of dithionite per mole of hydroperoxide, dead‐stops occur at low conversion due to exhaustion of hydroperoxide. The rate is determined by the concentration of ferric versenate, and an excess of versene over ferric iron has no effect. The addition of potassium pyrophosphate yields a latex which is of normal fluidity and free of precoagulation up to 80% conversion. The effects of polymerization variables are described. With methanol as antifreeze, a recipe is described which yields 75% conversion in 8 hours at −20°C. The reaction mechanism is very involved. It is concluded that an induced reaction between hydroperoxide and dithionite is responsible for the low efficiency of the radicals produced in this recipe.
Dynamics of loosely crosslinked polymer networks
Authors: Bueche F.
Published: April 2003

An ideal crosslinked rubber will reach an equilibrium elongation soon after a constant tensile stress has been applied to it. Actual materials never reach an equilibrium strain in many cases. This fact is clarified by studying the creep curves for molten polyethyl methacrylate crosslinked with varying amounts of ethylene dimethacrylate. A quantitative theory for the observed effects is presented. It shows that the slope of the long time portion of the creep curve is dependent primarily on a parameter which characterizes the number of effective chains emanating from a network branch point. Reasonable agreement between theory and experiment is found.
The reaction of sulfur and sulfur compounds with olefinic substances. Part XII. Effects of vulcanizing additives on the reaction of sulfur with 2,6‐dimethylocta‐2,6‐diene, and their bearing on the mechanism of sulfur vulcanization of natural rubber
Authors: Bateman L. , Glazebrook R. W. , Moore C. G.
Published: April 2003

The effects of zinc oxide, of zinc oxide and stearic acid, and of zinc oxide, stearic acid, and 2‐mercaptobenzothiazole on the products of interaction of sulfur with the diisoprene, 2,6‐dimethylocta‐2,6‐diene at 140°C. have been investigated in detail. Zinc oxide alone produces little change in the composition of the complex product mixture, but in the presence of stearic acid, and more so when the thiazole is also present, significant changes are produced in the distribution of combined sulfur which reflect more efficient use of the sulfur in crosslinking reactions, and which can be related rationally to important effects exerted by these additives on the sulfur‐vulcanization of natural rubber. It has recently been advanced that sulfur‐olefin interaction proceeds by a polar mechanism in which the dominant feature is the additive reactivity of persulfenium ionic species (T) towards double bonds. Evidence is now presented that the chemical and technological effects of soluble zinc salts and of thiazole accelerators stem from their action in enhancing the role of reactions promoted by the complementary persulfenyl anionic species (T) which involve the displacement of hydrogen from, and the addition of sulfur to, carbon atoms adjacent to double bonds. Essentially similar mechanistic considerations appear to apply to systems accelerated by amines and by metal dithiocarbamates and xanthates.
Latex thickening: Interactions between aqueous polymeric dispersions and solutions
Authors: Brown George L. , Garrett B. S.
Published: April 2003

Latex thickening—the process of increasing the viscosity of a polymer emulsion by addition of a water‐soluble polymer —has been studied by rheological measurements and by the examination of other colloidal properties. For the systems studied, which represent a range of polymers in both the dispersion and solution phases, the flow curves were represented over a wide range of shear rate by the equation, S = K(τ − τ0)2, where S is shear stress, τ is shear rate, and K and τ0 are constants, of which the latter is considered to be a yield stress. Aside from the generality of the mathematical function, the behavior of various latex‐thickener pairs is extremely specific to the pair involved. Additional data on latex creaming and on the influence of the thickener and latex concentrations confirms the specificity. The available data indicate that latex thickening is not simply an enhancement of the viscosity of the aqueous phase by the thickener, but that in addition to this the ability of the thickener to flocculate or deflocculate the latex is an important part of the mechanism of thickening. These colloidal interactions change, often precipitously, with minor changes in the polymers, the latex emulsifier, and the concentrations of the components.
The stability of fluorine‐containing polymers to amines
Authors: Bro M. I.
Published: April 2003

The reactivity of hydrofluorocarbon polymers toward organic amines increases, generally, with increasing fluorine content and with increasing basicity of the amine. The position of fluorine in the molecule with respect to hydrogen strongly affects the electrophylic character of the hydrogen atom. A discussion of the effects of neighboring groups on this reactivity is presented.
Diffusion of small molecules in semicrystalline polymers: Water in polyethylene
Authors: Klute C. H.
Published: April 2003

Published data on the solubility properties and diffusion coefficients for water in polyethylene are critically examined and related to the permeability coefficients analyzed in a previous paper. The data examined in the present article are even more variable than the permeability data, the measured diffusion coefficients varying over a fourteenfold range. Solubilities vary less from specimen to specimen but do so in an order opposite to that of the diffusion coefficients. Accordingly the permeability coefficients vary much less than do the diffusion coefficients. In an examination of the permeation process, as it must occur through semicrystalline polymer films, it is demonstrated that a systematic error is introduced if permeation through such films is described by means of equations developed for homogeneous materials. The error has been evaluated by means of an electrical analog and equations describing diffusion in semicrystalline polymers are derived which complement those already in existence for diffusion in homogeneous polymers. By means of these equations it is shown that the variations in permeability and diffusion coefficients cannot be explained on the basis of reasonable variations in the amount of crystallinity between otherwise comparable polymers or by reasonable variations in the way in which the crystalline regions occur in the amorphous matrix. The conclusion previously reached to the effect that variations in the structure of the amorphous phase from specimen to specimen are responsible for irreproducible transport properties still appears valid.
Transition behavior of polychloroprene and polychloroprene/styrene‐butadiene blends
Authors: Kell R. M. , Bennett Bailey , Stickney P. B.
Published: April 2003

Dilatometric studies have been carried out to determine crystallization and glass transition data for various unvulcanized and vulcanized polychloroprenes and polychloroprene/styrene‐butadiene blends. The maximum rate of crystallization of both unvulcanized polychloroprene and the blends occurred near −5°C. Melting temperatures of the polychloroprenes ranged from 36 to 43°C. The glass transition temperature of all polychloroprenes studied was near −45°C., and this was lowered to −50°C. with the addition of 30 pph of SBR‐1500. The added SBR polymer retarded the rate and ultimate degree of crystallization somewhat.