bluuebunny/crossref_metadata_2025 huggingface dataset:
Gemcitabine and Docetaxel in Patients With Unresectable Leiomyosarcoma: Results of a Phase II Trial
Authors: Hensley Martee L. , Maki Robert , Venkatraman E. , Geller Gennifer , Lovegren Meghan , Aghajanian Carol , Sabbatini Paul , Tong William , Barakat Richard , Spriggs David R.
Published: October 2002

PURPOSE: Few chemotherapy agents are active in leiomyosarcoma (LMS), particularly LMS that has progressed after doxorubicin treatment. We sought to determine the response to gemcitabine plus docetaxel among patients with LMS.

PATIENTS AND METHODS: Patients with unresectable LMS of uterine (n = 29) or other (n = 5) primary sites who did not respond to zero to two prior chemotherapy regimens were enrolled onto a phase II study of gemcitabine 900 mg/m2 intravenously (IV) on days 1 and 8 plus docetaxel 100 mg/m2 IV on day 8 with granulocyte colony-stimulating factor given subcutaneously on days 9 to 15, delivered every 21 days. Patients with prior pelvic radiation received 25% lower doses of both agents. Gemcitabine was delivered over 30 or 90 minutes in cycles 1 and 2 and by 90-minute infusion in all subsequent cycles. Pharmacokinetic studies assessed in vivo differences in gemcitabine concentrations with different rates of infusion.

RESULTS: Thirty-four patients (median age, 55 years; range, 32 to 74 years) have enrolled. Fourteen had received prior pelvic radiation. Sixteen of 34 patients had progressed after doxorubicin-based therapy; 18 had no prior chemotherapy. Among 34 patients, complete response was observed in three patients and partial response in 15, for an overall response rate of 53% (95% confidence interval, 35% to 70%). Seven patients had stable disease. Fifty percent of patients previously treated with doxorubicin responded. Hematologic toxicity was common (neutropenia: grade 3, 15%; grade 4, 6%; thrombocytopenia: grade 3, 26%; grade 4, 3%), but neutropenic fever (6%) and bleeding events (0%) were rare. The median time to progression was 5.6 months (range, 4 to 10 months).

CONCLUSION: Gemcitabine plus docetaxel is tolerable and highly active in treated and untreated patients with LMS.
Characterization of two isomeric β-D-glucosiduronic acids derived from 1,2-diethyl-3-hydroxypyridin-4-one (CP94) in rat liver homogenate incubates
Authors: Liu D Y , Liu Z D , Piyamongkol S , Lu S L , Hider R C
Published: October 2002

1,2-Diethyl-3-hydroxypyridin-4-one (CP94) is an orally active iron chelator with potential for use in photodynamic therapy. This investigation reports the formation and characterization of two isomeric glucuronides of CP94 in rat liver homogenate incubates. To assign the glucuronidation sites in the CP94 molecule, two O-methylated derivatives of CP94 have been synthesized. By comparing the spectral characteristics of the CP94 3-O- and 4-O-methyl derivatives with CP94 and the CP94 glucuronides formed during incubation, evidence was obtained which enabled the assignment of these two isomeric glucuronides to the 3-O-glucuronide and 4-O-glucuronide of CP94. It was found that the 3-O-glucuronide was the dominant CP94 metabolite under in-vitro conditions. In an attempt to understand the potential influence of structural variation on the glucuronidation of CP94 analogues, the 1-and 2-monoethyl derivatives of CP94 were investigated. The 2-monoethyl derivative of CP94 yielded only the 3-O-glucuronide in rat liver homogenate incubate, while no glucuronide was formed from the 1-monoethyl derivative. In addition, no glucuronide from the 3-O-methyl or 4-O-methyl derivatives of CP94 could be detected. The relevance of these findings to the development of new 3-hydroxypyridin-4-one iron chelators is discussed.
On the optimal stopping values induced by general dependence structures
Authors: Müller Alfred , Rüschendorf Ludger
Published: October 2002

The optimal stopping value of random variables X1,…,Xn depends on the joint distribution function of the random variables and hence on their marginals as well as on their dependence structure. The maximal and minimal values of the optimal stopping problem is determined within the class of all joint distributions with fixed marginals F1,…,Fn. They correspond to some sort of strong negative or positive dependence of the random variables. Any value inbetween these two extremes is attained for some dependence structures. The determination of the minimal value is based on some new ordering results for probability measures, in particular on lattice properties of stochastic orderings. We also identify properties of dependence structures leading to the minimal optimal stopping value. In the proofs we need an extension of Strassen's theorem on representation of the convex order which reveals that convex ordered distributions can be coupled by a two-step martingale (X,Y) with the additional property that Y is stochastically increasing in X.
The quasistationary distribution of the stochastic logistic model
Authors: Ovaskainen Otso
Published: October 2002

The stochastic logistic model has been studied in various contexts, including epidemiology, population biology, chemistry and sociology. Among the model predictions, the quasistationary distribution and the mean time to extinction are of major interest for most applications, and a number of approximation formulae for these quantities have been derived. In this paper, previous approximation formulae are improved for two mathematically tractable cases: at the limit of the number of individuals N → ∞ (with relative error of the approximations of the order 𝒪(1/N)), and at the limit of the basic reproduction ratio R0 → ∞ (with relative error of the approximations of the order 𝒪(1/R0)). The mathematically rigorous formulae are then extended heuristically for other values of N and R0 > 1.
Convergence of simulated annealing using Foster-Lyapunov criteria
Authors: Andrieu Christophe , Breyer Laird A. , Doucet Arnaud
Published: October 2002

Simulated annealing is a popular and much studied method for maximizing functions on finite or compact spaces. For noncompact state spaces, the method is still sound, but convergence results are scarce. We show here how to prove convergence in such cases, for Markov chains satisfying suitable drift and minorization conditions.
A note on convergence of probability measures
Authors: Grey D. R.
Published: October 2002

We present, discuss and prove an apparently unfamiliar result in the convergence of probability measures.
Optimal stopping with discount and observation costs
Authors: Kühne Robert , Rüschendorf Ludger
Published: October 2002

For i.i.d. random variables in the domain of attraction of a max-stable distribution with discount and observation costs we determine asymptotic approximations of the optimal stopping values and asymptotically optimal stopping times. The results are based on Poisson approximation of related embedded planar point processes. The optimal stopping problem for the limiting Poisson point processes can be reduced to differential equations for the boundaries. In several cases we obtain numerical solutions of the differential equations. In some cases the analysis allows us to obtain explicit optimal stopping values. This approach thus leads to approximate solutions of the optimal stopping problem of discrete time sequences.
Use of an hourglass model in neuronal coding
Authors: Cottrell M. , Turova T. S.
Published: October 2002

We study a system of interacting renewal processes which is a model for neuronal activity. We show that the system possesses an exponentially large number (with respect to the number of neurons in the network) of limiting configurations of the ‘firing neurons’. These we call patterns. Furthermore, under certain conditions of symmetry we find an algorithm to control limiting patterns by means of the connection parameters.
Moments based approximation for the stationary distribution of a random walk in Z+ with an application to the M/GI/1/n queueing system
Authors: Simonot F.
Published: October 2002

In this paper we consider an irreducible random walk in Z+ defined by X(m+1) = max(0, X(m) + A(m+1)) with E{A} < 0 and for an s ≥ 0 where a+ = max(0,a). Let π be the stationary distribution of X. We show that one can find probability distributions πn supported by {0,n} such that ||πn - π||1 ≤ Cn-s, where the constant C is computable in terms of the moments of A, and also that ||πn - π||1 = o(n-s). Moreover, this upper bound reveals exact for s ≥ 1, in the sense that, for any positive ε, we can find a random walk fulfilling the above assumptions and for which the relation ||πn - π||1 = o(n-s-ε) does not hold. This result is used to derive the exact convergence rate of the time stationary distribution of an M/GI/1/n queueing system to the time stationary distribution of the corresponding M/GI/1 queueing system when n tends to infinity.
Weak approximation for a class of Gaussian processes
Authors: Delgado Rosario , Jolis Maria
Published: October 2002

We prove that, under rather general conditions, the law of a continuous Gaussian process represented by a stochastic integral of a deterministic kernel, with respect to a standard Wiener process, can be weakly approximated by the law of some processes constructed from a standard Poisson process. An example of a Gaussian process to which this result applies is the fractional Brownian motion with any Hurst parameter.
On some waiting time problems
Authors: Stefanov Valeri T.
Published: October 2002

A unifying technology is introduced for finding explicit closed form expressions for joint moment generating functions of various random quantities associated with some waiting time problems.Soonerandlaterwaiting times are covered for general discrete- and continuous-time models. The models are either Markov chains or semi-Markov processes with a finite number of states. Waiting times associated with generalized phase-type distributions, that are of interest in survival analysis and other areas, are also covered.
Asymptotic distribution for the sum and maximum of Gaussian processes
Authors: McCormick W. P. , Qi Y.
Published: October 2002

Previous work on the joint asymptotic distribution of the sum and maxima of Gaussian processes is extended here. In particular, it is shown that for a stationary sequence of standard normal random variables with correlation function r, the condition r(n)ln n = o(1) as n → ∞ suffices to establish the asymptotic independence of the sum and maximum.
Sharp results on convergence rates for the distribution of GI/M/1/K queues as K tends to infinity
Authors: Choi Bong Dae , Kim Bara
Published: October 2002

In this paper, we investigate how fast the stationary distribution π(K) of an embedded Markov chain (time-stationary distribution q(K) of the GI/M/1/K queue converges to the stationary distribution π of the embedded Markov chain (time-stationary distribution q) of the GI/M/1 queue as K tends to infinity. Simonot (1997) proved certain equalities. We obtain sharper results than these by finding limit values limK→∞σ-K||π(K) - π|| and limK→∞σ-K||q(K) - q|| explicitly.
Bias optimal admission control policies for a multiclass nonstationary queueing system
Authors: Lewis Mark E. , Ayhan Hayriye , Foley Robert D.
Published: October 2002

We consider a finite-capacity queueing system where arriving customers offer rewards which are paid upon acceptance into the system. The gatekeeper, whose objective is to ‘maximize’ rewards, decides if the reward offered is sufficient to accept or reject the arriving customer. Suppose the arrival rates, service rates, and system capacity are changing over time in a known manner. We show that all bias optimal (a refinement of long-run average reward optimal) policies are of threshold form. Furthermore, we give sufficient conditions for the bias optimal policy to be monotonic in time. We show, via a counterexample, that if these conditions are violated, the optimal policy may not be monotonic in time or of threshold form.
On explicit and Fréchet-optimal lower bounds
Authors: Seneta Eugene , Chen John Tuhao
Published: October 2002

Ease of computation of Fréchet-optimal lower bounds, given numerical values of the binomial moments Sij, i, j = 1, 2, is demonstrated. A sufficient condition is given for an explicit bivariate bound of Dawson-Sankoff structure to be Fréchet optimal. An example demonstrates that in the bivariate case even the multiplicative structure of the Sij does not guarantee a Dawson-Sankoff structure for Fréchet-optimal bounds. A final section is used to illuminate the nature of Fréchet optimality by using generalized explicit bounds. This note is a sequel to both Chen and Seneta (1995) and Chen (1998).
Multifractal spectra of branching measure on a Galton-Watson tree
Authors: Shieh Narn-Rueih , Taylor S. James
Published: October 2002

If Z is the branching mechanism for a supercritical Galton-Watson tree with a single progenitor and E[ZlogZ] < ∞, then there is a branching measure μ defined on ∂Γ, the set of all paths ξ which have a unique node ξ|n at each generation n. We use the natural metric ρ(ξ,η) = e−n, where n = max{k : ξ|k = η|k}, and observe that the local dimension index is d(μ,ξ) = limn→∞ log(μB(ξ|n))/(-n) = α = logm, for μ-almost every ξ. Our objective is to consider the exceptional points where the above display may fail. There is a nontrivial ‘thin’ spectrum for ̄d(μ,ξ) when p1 = P{Z = 1} > 0 and Z has finite moments of all positive orders. Because ̱d(μ,ξ) = a for all ξ, we obtain a ‘thick’ spectrum by introducing the ‘right’ power of a logarithm. In both cases, we find the Hausdorff dimension of the exceptional sets.
Rate of convergence to equilibrium of marked Hawkes processes
Authors: Brémaud P. , Nappo G. , Torrisi G. L.
Published: October 2002

In this article we obtain rates of convergence to equilibrium of marked Hawkes processes in two situations. Firstly, the stationary process is the empty process, in which case we speak of the rate of extinction. Secondly, the stationary process is the unique stationary and nontrivial marked Hawkes process, in which case we speak of the rate of installation. The first situation modelssmall epidemics, whereas the results in the second case are useful in deriving stopping rules for simulation algorithms of Hawkes processes with random marks.
Computing limiting stationary distributions of small noisy networks
Authors: Richman Fred , Winkowska-Nowak Katarzyna
Published: October 2002

The dynamics of opinion transformation is modeled by a neural network with a nonnegative matrix of connections. Noise is introduced at each site, and the limit of the stationary distributions of the resulting Markov chains as the noise goes to zero is taken as an indication of what configurations will be seen. An algorithm for computing this limit is given, and a number of examples are worked out. Some of the mathematical ideas developed, such as visible states, time scales, and a calculus of indexed probabilities, are of independent interest.
Remarks on the absolute maximum of a Lévy process
Authors: Bratiychuk Mykola
Published: October 2002

Asymptotic behaviour of the distribution of the absolute maximum of a process with independent increments is studied depending on the properties of the Lévy measure of the process. Some applications to the risk process are also considered.
The structured coalescent process with weak migration
Authors: Notohara Morihiro
Published: October 2002

The aim of this paper is to study genealogical processes in a geographically structured population with weak migration. The coalescence time for sampled genes from different colonies diverges to infinity as the migration rates among colonies are close to zero. We investigate the moment generating functions of the coalescence time, the number of segregating sites and the number of allele types in sampled genes when there is low migration. Employing a perturbation method, we obtain a system of recurrence relations for the approximate solutions of these moment generating functions and solve them in some cases.
Epidemiological evidence that maternal diabetes does not appear to increase the risk for Down syndrome
Authors: Martínez‐Frías M. L. , Rodríguez‐Pinilla E. , Bermejo E. , Prieto L.
Published: October 2002

In 1997, Narchi and Kulaylat, studying the incidence of Down syndrome in infants of gestational diabetic mothers, concluded that maternal diabetes increases the risk for Down syndrome, but failed to control the maternal age in their analysis. Using data from the Spanish Collaborative Study of Congenital Malformations (ECEMC), we analyzed the relationship between Down syndrome and maternal diabetes mellitus, and maternal gestational diabetes, controlling the maternal age through the pair‐matching analysis, stratifying by maternal age and logistic regression analysis. The analyses show that maternal age is related either to Down syndrome as well as to both types of maternal diabetes. Thus, the overall analysis could be confounded by maternal age. Once we controlled the maternal age, the risk of maternal diabetes mellitus for Down syndrome is: odds ratio (OR) = 0.92 (0.41–2.07); P = 0.83. Controlling maternal age in gestational diabetes, the risk is OR = 1.18 (0.61–2.35); P > 0.70. Based on our results, we conclude that Down syndrome is related to maternal age, but does not seem to be related to any type of maternal diabetes. © 2002 Wiley‐Liss, Inc.
Dextromethorphan for the reduction of immediate and late postoperative pain and morphine consumption in orthopedic oncology patients
Authors: Weinbroum Avi A. , Gorodetzky Alexander , Nirkin Alexander , Kollender Yehuda , Bickels Jacob , Marouani Nissim , Rudick Valery , Meller Isaac
Published: October 2002

BACKGROUND

Postoperative pain is mediated centrally by N‐methyl‐D‐aspartate (NMDA) receptors. The beneficial effects of preincision oral dextromethorphan (DM), which is an NMDA antagonist, on postoperative pain and intravenous patient‐controlled analgesia (IV‐PCA) morphine (MO) consumption have been examined in patients undergoing surgery. The authors investigated 75 patients who underwent surgery for bone and soft tissue malignancies, in whom postoperative pain is more severe compared with patients who undergo general surgery.

METHODS

Patients received placebo, DM 60 mg, or DM 90 mg (25 patients per group) before surgery and on each of the two following days in a randomized, double‐blind, placebo‐controlled manner. Postoperative IV‐PCA MO was started when subjective pain intensity was ≥ 4/10 (visual score) and lasted for 72 hours. Rescue drugs on demand were oral paracetamol or dipyrone.

RESULTS

The patients in the DM60 and DM90 groups similarly experienced 50–80% less pain (P < 0.01) compared with patients in the placebo group, both immediately and up to 3 days postoperatively, as well as a 50% reduction in the estimated overall maximal pain intensity (P < 0.01). Both DM groups consumed 50–70% less MO than the nonmedicated individuals in the placebo group (P < 0.01), and their demand for rescue drugs on the first postoperative day also was significantly lower (P < 0.01). Patients in the DM groups also were sedated less (≈ 70%; P < 0.01). There were no differences among the groups in terms of when the patients left their beds, when they were discharged home, or the number of overall side effects.

CONCLUSIONS

DM is associated with reduced pain intensity, sedation, and analgesic requirements, even in patients undergoing surgery for bone and soft tissue malignancies. A 3‐day DM administration neither increased the incidence of side effects nor accelerated ambulation and discharge home. Cancer 2002;95:1164–70. © 2002 American Cancer Society.

DOI 10.1002/cncr.10784
Survey of oncologists' perceptions of barriers to accrual of older patients with breast carcinoma to clinical trials
Authors: Kornblith Alice B. , Kemeny Margaret , Peterson Bercedis L. , Wheeler Judith , Crawford Jeffrey , Bartlett Nancy , Fleming Gini , Graziano Stephen , Muss Hyman , Cohen Harvey Jay ,   Cancer and Leukemia Group B
Published: October 2002

BACKGROUND

Prior research has documented the under‐representation in clinical trials of older patients with cancer. In part of a larger study to test the magnitude of these barriers to entering eligible older patients with carcinoma of the breast into clinical trials (Cancer and Leukemia Group B [CALGB] trial 9670), barriers to accruing eligible older patients to clinical trials were obtained from the physician's perspective.

METHODS

One hundred fifty‐six physicians (85% oncologists) who treated patients with breast carcinoma at 10 CALGB institutions completed a questionnaire concerning what they perceived as barriers to enrolling older patients with breast carcinoma on clinical trials and possible interventions that may improve accrual.

RESULTS

Physicians' perceptions of the most important barriers to accrual of older patients were: 1) elderly patients have significant comorbid conditions that are not excluded by the protocol but that may affect how they would respond to treatment (16%); elderly patients have difficulty understanding what is required in a complicated treatment trial, resulting in poor compliance (16%); treatment toxicity (14%); and elderly patients often do not meet the eligibility criteria (15%). Oncologists most frequently suggested that the most effective interventions for improving the accrual of elderly patients to trials included making personnel available in the clinic to explain clinical trials to older patients and their families (25%) and providing physicians with educational materials concerning treatment toxicity in the elderly (18%).

CONCLUSIONS

Physicians viewed barriers to accruing older patients with breast carcinoma to clinical trials as multidimensional, with the most important involving protocol requirements, treatment specific issues, and older patients' medical and cognitive characteristics. Thus, a variety of interventions would be needed to improve accrual of older patients to clinical trials, including increasing physicians' knowledge concerning treatment toxicity in the elderly, simplifying protocol requirements, and reducing treatment toxicity. Cancer 2002;95:989–96. © 2002 American Cancer Society.

DOI 10.1002/cncr.10792
Does HER2/neu expression provide prognostic information in patients with advanced urothelial carcinoma?
Authors: Gandour‐Edwards Regina , Lara Primo N. , Folkins Ann K. , LaSalle Janine M. , Beckett Laurel , Li Yueju , Meyers Frederick J. , DeVere‐White Ralph
Published: October 2002

BACKGROUND

Muscle‐invasive urothelial carcinoma of the bladder is a highly lethal malignancy, particularly in the setting of locally advanced or metastatic disease. Prior reports of HER2/neu (c‐erbB‐2 or HER2) expression in bladder carcinoma have been mixed; therefore, its value in predicting metastasis or response to therapy has not been established in this tumor type. Thus, the authors evaluated a possible correlation between HER2 expression in patients with high‐grade, muscle‐invasive urothelial carcinoma of the bladder and outcome in patients who received paclitaxel‐based chemotherapy.

METHODS

Archival tumor tissues from patients with advanced urothelial carcinoma who were enrolled on two clinical trials of paclitaxel‐based chemotherapy regimens were analyzed for HER2/neu expression by immunohistochemistry (IHC). The authors correlated HER2 expression by IHC with clinical outcomes, such as response rate, progression free survival, and overall survival, using univariate analysis.

RESULTS

Thirty‐nine tumor specimens were assessed for HER2 expression, most of which (70%) were collected from patients with metastatic disease. All were high‐grade urothelial carcinomas (transitional cell carcinomas, Grade 3). Strong HER2 expression (2+/3+) was seen in 28 patients (71%). Patients with responding disease had an HER2 expression rate of 78%, similar to the rate seen in patients with stable disease (75%). In contrast, patients with progressive disease had an HER2 expression rate of 50%, although this difference did not reach statistical significance. However, univariate analysis showed that increased HER2 expression predicted an improvement in progression free and overall survival. When HER2 status was used as a dichotomous variable, tumors with positive HER2 expression did not have any association with response or with progression free survival; however, positive HER2 status was associated significantly with a decreased risk of death (P = 0.03).

CONCLUSIONS

This study of HER2 expression in bladder carcinoma focused on patients who were treated prospectively in a standardized fashion, unlike prior studies that have evaluated banked, archival specimens. The authors confirmed the findings of others that high‐grade, muscle‐invasive urothelial carcinoma of the bladder has a significant rate of HER2 expression (71%). However, contrary to other reports, the current study found that HER2 expression in the context of paclitaxel‐based chemotherapy decreased the risk of death significantly. Further research is warranted on the possible association of HER2 expression with chemosensitivitiy in urothelial carcinoma as well as the efficacy of HER2‐targeted therapies (such as trastuzumab) for patients with high‐grade, muscle‐invasive urothelial carcinoma of the bladder. Cancer 2002;95:1009–15. © 2002 American Cancer Society.

DOI 10.1002/cncr.10808
Human antibody response to Toscana virus glycoproteins expressed by recombinant baculovirus
Authors: Di Bonito Paola , Bosco Simona , Mochi Stefania , Accardi Luisa , Ciufolini Maria G. , Nicoletti Loredana , Giorgi Colomba
Published: October 2002

The arthropod‐borne Toscana virus has been associated with acute neurological disease in humans. In this study, the viral envelope glycoproteins were expressed in soluble form in a baculovirus system. The recombinant sGN and sGC proteins were used as viral antigens in a Western blot assay to analyze the specific immune response in sera from patients with recognized virus‐associated aseptic meningitis. The anti‐glycoprotein and the anti‐nucleoprotein N IgG responses were compared by an immunoassay based on the recombinant proteins. In this system, all the sera showed a high reactivity to the N protein, but they differed in the response to the glycoproteins. J. Med. Virol. 68:615–619, 2002. © 2002 Wiley‐Liss, Inc.
Heuristic policies for inventory ordering problems with long and randomly varying lead times
Authors: Foote Bob , Kebriaei Naghi , Kumin Hillel
Published: October 2002

In most inventory models, lead time is an insignificant factor in inventory modeling and implementation. There are situations, however, in private industry and governmental procurement in which this is not the case. For example, orders for castings and forgings with a low order size may have lead times of from 12 to 36 months. The actual lead time is random and depends on economic factors that determine the load at the foundry.

A model developed by Liberatore in 1977 [1] was the first approach to incorporate random lead time and yet had a feasible solution approach for a multi‐period problem. However, this approach requires significant development time for implementation on a digital computer by a technically skilled analyst.

Our sensitivity analysis of this model indicates that a solution of the model for every specific case may not be necessary. In fact, some heuristic policies are revealed that offer a manager a finite set of alternatives to consider with some assurance that the policy selected will be close to optimum.

Our conclusions are: 1) Consider 1,2 or 3 orders per year with the order sizes roughly equal. 2) The time of the first order should be approximately E (lead time) + 1.25σLT prior to the first demand point. 3) Large increases in σLT will not affect these policies.
A dynamic programming approach to work force scheduling with time‐dependent performance measures
Authors: Davis Samuel G. , Reutzel Edward T.
Published: October 2002

An implicit enumeration algorithm is defined to obtain solutions to the commercial bank check processing encoder scheduling problem. The specific application is of particular interest because a significant factor in determining optimality is the float costs associated with checks which are unprocessed and unavailable for presentation at check clearing deadlines, thereby making the timing of the activity of crucial importance. A one day time horizon is employed to reflect those situations where banks have the scheduling flexibility afforded by part‐time and/or temporary help in additon to a complement of full‐time operators. Comparisons are made with other suggested approaches to daily encoder scheduling. Results indicate that dynamic programming can be an attractive methodology to attack this complex problem.
Operations change interactions in a service environment: Attitudes, behaviors, and profitability
Authors: Adam Everett E.
Published: October 2002

An attitudinal and behavioral change program was developed and implemented in a service operations function. Changes were (1) stabilizing operations management (reducing turnover) and (2) improving attitudes and behaviors of employees with strong union affiliations in a common carrier trucking terminal when compared to similar employees in a control terminal undergoing no planned change. Management turnover was reduced. Other results from the eighteen‐month longitudinal study indicated that employee attitudes in both groups remained negative toward work, management, and the company throughout the study period. Behaviors relating to attitudes — particularly turnover, absenteeism, and accident rates—improved at the experimental terminal, even though expressed attitudes remained negative. Operating efficiencies and profitability improved at the experimental terminal. It was found that these employees, pick‐up and delivery drivers, retain positive attitudes toward customers and customers the same toward them, in spite of the drivers' negative attitudes toward the company. The operative service employee appeared to discriminate between attitudes toward the company and the customer; the drivers' negative attiudes toward most everything (except the customer) not affecting the customer's perceptions of the driver or the company.
Priority dispatching with operation due dates in a job shop
Authors: Kanet John J. , Hayya Jack C.
Published: October 2002

This paper investigates the effects on job shop performance of setting and attempting to enforce operation due dates for jobs. It does so by comparing via simulation the performance of priority dispatching rules when employed to enforce operation due dates versus job due dates. The results indicate that operation due dates improve every conventional measure of job shop performance.
Some observations on the advantages and implementation issues of just‐in‐time production systems
Authors: Schonberger Richard J.
Published: October 2002

U.S. industry has been bombarded with prescriptions for catching up with the Japanese. Surprisingly absent from many lists of these prescriptions is the Japanese just‐in‐time (JIT) production system. The JIT approaches are simple and generally require little use of computers, and they appear to provide far tighter controls on inventory than are attainable via U.S. computer‐based approaches. More importantly, Japanese JIT tends to promote major improvements in quality and productivity, as well as increased worker responsibility and commitment. JIT applications and benefits apply not only to the shop floor but also to the distribution and the purchasing ends of the business.

In the article, JIT is contrasted with MRP, and the JIT production system is explained with reference to a graphical cause‐effect model. The necessity, under the JIT system, of revising traditional assumptions with regard to cycle stock and buffer inventories is explained. The author's views on how JIT affects plant configurations are presented, along with personal observations on how one Japanese subsidiary in the U.S. has been reconfiguring its plant in the process of adopting a JIT production system.
Quality circles and production/operations management: Concerns and caveats
Authors: Blair John D. , Ramsing Kenneth D.
Published: October 2002

There has been a growing interest by American production and manufacturing organizations in the concepts and techniques being used by Japanese managers. In particular, quality circles have been found to be valuable in some companies and have thus been seen by many as being the answer to the declining productivity in companies in the United States. However, there is considerable concern by these authors that an indiscriminate acceptance of the quality circle concept may result in a series of problems for many organizations attempting its use.

Although quality circles did not appear in the United States until implemented by Lockheed Missile and Space Company in 1974, their growth has been extremely rapid. It was estimated in 1980 by I.A.Q.C., that the number had grown to over 3,000 circles in U.S. companies. This widespread interest in quality circles comes, in part, from the almost deceptively simple concept of organizational intervention with the primary objective to increase productivity and quality of the production/ manufacturing sector through direct employee participation. Within this context, QCs appear to succeed in tapping into several dimensions of organizational behavior which are potentially related to improved organizational functioning: individual motivation, group process, and managerial decision‐making.

However, a number of questions do exist about the use of quality circles in the production of goods and services in this nation. Some of these concerns are described under the headings of: Cultural Considerations; White Collar Effectiveness; Motivational Forces; Effectiveness of Quality Circles; Introduction of Quality Circles; and Quality Circle Longevity.

This paper presents some implications and caveats for the use of quality circles as a basis for improving quality and productivity:

A diagnosis of the organization to ensure that an organizational development intervention is appropriate.

A realistic expectation of what QCs can do and how quickly.

Quality circles should not be introduced into organizations under extreme stress.

QCs should not be forced into an organization.

Program costs must be considered.

Management should not expect completely perfect results but that there will be failures and some circles will not have a long life.

This article attempts to provide an objective analysis of the quality circle concept as a method for improving productivity and quality. The concept of quality circles is sound with real successes evident. It is necessary for a company attempting to use quality circles to have a strong degree of commitment by management to respond to the involvement of their employees.
Scheduling independent jobs on nonuniform, unequal processors
Authors: Bernardo John J. , Lin Kun‐Si
Published: October 2002

The problem of scheduling n independent jobs on a single processor to minimize the total tardiness of the assignment has attracted much attention. Solution algorithms, both exact and approximate, have been reported, but no polynomial time exact algorithm has yet been found, nor has the problem been proven NP‐complete.

In this paper we consider the more general case of scheduling n independent jobs on m unequal processors to minimize total tardiness. Since this problem is more complex than the corresponding single‐processor problem, no polynomial‐time algorithm is in sight. For problems of this nature, approximate algorithms may be more valuable than exact algorithms in terms of applications. A heuristic algorithm is developed to solve the multiple‐processor problem. Computational experiments show that the heuristic algorithm is efficient, fast, and easy to implement.
Assemble‐to‐order manufacturing: Implications for materials management
Authors: Wemmerlöv Urban
Published: October 2002

A company's manufacturing is often characterized as either make‐to‐stock (MTS), make‐to‐order (MTO), or assemble‐to‐order (ATO). This classification relates to the degree of interaction between the technological core and the market, with MTS involving the least amount of interaction and MTO the highest degree of contact. ATO represents a hybrid manufacturing strategy for which parts and subassemblies are made according to forecasts while the final assembly of the products is delayed until customer orders have been received. It is evident that each manufacturing philosophy has strategic as well as operational implications.

This paper focuses on ATO manufacturing and, in particular, on the design and operation of the manufacturing planning and control system. The relative differences between MTO, ATO, and MTS strategies, and the reasons why a company may decide to be an ATO manufacturer, are discussed first. Several problem areas, which must be addressed by a company that chooses this form of manufacturing, are then identified. It is found that the ATO philosophy requires special system design considerations, particularly in the areas of master scheduling, bills of material structuring, order entry/order promising, final assembly scheduling, and buffering against demand uncertainty. Examples of important issues discussed are the selection of appropriate master schedule units and the associated consequences for the structuring of the bills of material; the choice of efficient procedures for reliable order booking using the combined information from forecasts, confirmed orders, and the master schedule; the relationship between the final assembly schedule and the master schedule; and various techniques that can be used to counter the effects of forecast errors related to the demand for customer options.

Following the discussion of all the issues raised above and the presentation of some common solutions, actual industry applications taken from several companies are used to illustrate various aspects of ATO manufacturing. These case illustrations complement the other material since many of them were chosen to reflect alternative procedural approaches to some ATO‐related problems. Finally, areas for future research into the design and operation of ATO manufacturing systems are suggested. It is particularly noted that few normative models for systems design exist in this area.
An efficient implementation of the Wagner‐Whitin algorithm for dynamic lot‐sizing
Authors: Evans James R
Published: October 2002

We consider an N‐period planning horizon with known demands Dt ordering cost At, procurement cost, Ct and holding cost Ht in period t. The dynamic lot‐sizing problem is one of scheduling procurement Qt in each period in order to meet demand and minimize cost.

The Wagner‐Whitin algorithm for dynamic lot sizing has often been misunderstood as requiring inordinate computational time and storage requirements. We present an efficient computer implementation of the algorithm which requires low core storage, thus enabling it to be potentially useful on microcomputers.

The recursive computations can be stated as follows:
urn:x-wiley:02726963:joom229:equation:joom229-math-0001

where Mjk is the cost incurred by procuring in period j for all periods j through k, and Fk is the minimal cost for periods 1 through k. Our implementation relies on the following observations regarding these computations:
urn:x-wiley:02726963:joom229:equation:joom229-math-0002

Using this recursive relationship, the number of computations can be greatly reduced. Specifically, additions and multiplications are required. This is insensitive to the data.

A FORTRAN implementation on an Amdahl 470 yielded computation times (in 10−3 seconds) of T = −.249 + .0239N + .00446N2. Problems with N = 500 were solved in under two seconds.
Comparison of exact and approximate methods of solving the uncapacitated plant location problem
Authors: Thizy Jean‐Michel , van Wassenhove Luk N. , Khumawala Basheer M.
Published: October 2002

This study was prompted by a recently published article in this journal on facility location by D. R. Sule. We show that the claim made by Sule of a novel and extremely simple algorithm yielding optimum solutions is not true. Otherwise, the algorithm would represent a breakthrough in decision‐making for which a number of notoriously hard problems could be efficiently recast as location problems and easily solved.

In addition, several variants of common location problems addressed by Sule are reviewed. In the last twenty years, many methods of accurately solving these problems have been proposed. In spite of their increased sophistication and efficiency, none of them claims to be a panacea. Therefore, researchers have concurrently developed a battery of fast but approximate solution techniques. Sule's method was essentially proposed by Kuehn and Hamburger in 1963, and has been adapted many times since.

We exhibit several examples (including the one employed by Sule) in which Sule's algorithms lead to nonoptimal solutions. We present computational results on problems of size even greater than those utilized by Sule, and show that a method devised by Erlenkotter is both faster and yields better results.

In a cost‐benefit analysis of exact and approximate methods, we conclude that planning consists of generating an array of corporate scenarios, submitting them to the “optimizing black box,” and evaluating their respective merits. Therefore, much is to be gained by eliminating the vagaries of the black box—that is, by using an exact method—even if the data collection and the model representation introduce sizable inaccuracies. Ironically, large problems (those that typically require most attention) cannot be solved exactly in acceptable computational times. Pending the imminent design of a new generation of exact algorithms, the best heuristics are those that guarantee a certain degree of accuracy of their solutions.
Getting from “just‐in‐case” to “just‐in‐time”: Insights from a simple model
Authors: Suri Rajan , De Treville Suzanne
Published: October 2002

Many factory managers are hesitant about implementing a just‐in‐time system due to concern about the dip in productivity that occurs. Here, a simple analytic model is used to study the trade‐off between disruption and learning/improvement on a production line. While simple, the model is shown to capture many of the effects of just‐in‐time mentioned in the literature.

Using insights from the model, an attempt is made to identify those factors to which successful implementation of just‐in‐time is most sensitive.
Production scheduling with capacity‐constrained transportation activities
Authors: Truscott William G.
Published: October 2002

This article presents a model for scheduling activities that are required to manufacture a product batch in a multistage process. The activities include setups, operations, and load movements between operations. In this model, setups may or may not require a unit from the preceding operation; each operation must be performed continuously on the batch once it has started, and capacity constraints apply to transportation activities. Within this context, two productivity‐related objectives are sought. The primary objective is to minimize the total production time for the batch; the secondary is to minimize the number of load movements.

Considering the capacity constraints, a maximum number of units per load is specified for each “vehicle” and one vehicle is dedicated to each transportation activity. The simplicity of the vehicle restriction facilitates the examination of scheduling interactions among activities, and the results of the research into this model may serve as a foundation for treating more general representations of capacity constraints.

The model is used to investigate the scheduling implications of capacity‐constrained load movements. It brings into focus interactions between these movements and the other activities in the process. After each operation, units must be grouped and moved in the fewest loads that permit the succeeding operation to begin as soon as possible, while observing setup and continuity requirements for this operation. Further, the departure times of loads depend on the availability of units and the vehicle. The formation of loads that must conform with the vehicle's capacity limit affects the times at which the loads are ready for movement, while the scheduling of previous movements from the operation affects the times at which the vehicle is available.

A procedure is developed for scheduling activities that have this complex set of interactions. Computational requirements on test problems indicate that practical‐sized applications can be handled with this procedure. These applications would be designed to assist in making production planning decisions by experimenting with factors such as vehicle capacity limits and sequencing of operations to determine their effect on production time requirements and numbers of load movements.

The article develops a branch‐and‐bound routine to solve subproblems of scheduling transportation activities. The efficiency of this routine that results from exploiting the specific structure of the subproblems is critical for the success of the overall procedure. While the subproblems can be solved as zero‐one mixed‐integer programs, this approach is too computationally burdensome for all but the smallest of problems.
The content of manufacturing strategy: An empirical study
Authors: Schroeder Roger G. , Anderson John C. , Cleveland Gary
Published: October 2002

While there has been an extensive literature written on manufacturing strategy since the 1960s, little empirical research has been done. This article reports on a study of manufacturing strategy in thirty‐nine companies based on questionnaire responses received from manufacturing managers.

The study indicates that things are not as bleak as the literature might suggest. About one‐third of the companies appear to have a well‐developed manufacturing strategy. In those cases where the manufacturing strategy exists it is consistent with the business strategy and internally consistent among mission, objectives, policies, and distinctive competence.

The term “manufacturing strategy” is not well understood by the managers surveyed. When asked to state their manufacturing strategy, they gave statements about what manufacturing should be, what it should do, how it should do it, and why it should do it. Apparently, the terminology itself is confusing. Frameworks for stating both business strategies and the elements of manufacturing strategy need to be strengthened and some specific suggestions are given in the article for doing so.

Even though two‐thirds of the companies did not have well‐developed manufacturing strategies, 80% of the managers felt that manufacturing had lent competitive strength to the business. This was being done through the development of a distinctive competence in manufacturing that provided competitive advantage.

Manufacturing strategies seemed to follow from business strategy. This is contrary to the literature, which indicates that manufacturing strategy is missing, or, at the very least inconsistent with business strategy and marketing strategy. Perhaps a stronger relationship exists than was previously thought. This article provides some evidence for establishing this premise and also provides data on the general status of strategy in manufacturing today.