bluuebunny/crossref_metadata_2025 huggingface dataset:
Defining and using quality of life: a survey of health care professionals
Authors: McKevitt C , Redfern J , La-Placa V , Wolfe C DA
Published: January 2004

Objective: ‘Quality of life’ is an important but poorly defined outcome in health and health care research. We sought to identify stroke professionals' definitions of quality of life and views of the purpose of its assessment.

Design: Using issues identified during in-depth interviews with stroke care professionals, we designed a postal survey questionnaire. Participants were asked to define quality of life, identify the purposes of assessing it and report experiences of measuring patient quality of life. Comparisons between professional groups were analysed using chi-squared tests of significance.

Subjects: Care of the elderly physicians, physiotherapists and occupational therapists in the UK.

Results: Of 2793 questionnaires distributed, 1572 were returned (56% response rate). Quality of life was defined in terms of ‘happiness’ by 72%; 25% included social well-being; 25% included physical abilities. Most (91%) identified ‘asking patients’ as an effective way to assess quality of life; 40% using standardized measures. Half those who reported using quality of life measures experienced difficulties, including being unsure about which measure to use and concerns about validity.

Conclusions: The idea of quality of life as happiness dominated responders' definitions. We argue that the term may be used in both a technical sense (an outcome) and in a broad colloquial sense, without necessarily distinguishing between the two. Clarification of the concept and its uses is required if recent calls to introduce quality of life assessment in clinical care are to be feasible.
Muscle strength in patients with chronic pain
Authors: Van Wilgen C P , Akkerman L , Wieringa J , Dijkstra P U
Published: January 2004

Objective: To analyse the in‘uence of chronic pain on muscle strength.

Design: Muscle strength of patients with unilateral nonspecific chronic pain, in an upper or lower limb, were measured according to a standardized protocol using a hand-held dynamometer. Before and after muscle strength measurement, a visual analogue scale for pain intensity was assessed.

Results: Forty patients were measured and the muscle strength of the painful side was 20–30% less than that of the nonpainful side. Strength reduction was seen in the whole limb. A significant correlation between pain intensity and reduced muscle strength in the painful limb existed for hip ‘exion, knee ‘exion, knee extension and three-point grip.

Conclusions: A strength reduction of 20–30% in a painful limb seems to be ‘normal’ in chronic pain patients.
Falls in community-dwelling older persons following hip fracture: impact on self-efficacy, balance and handicap
Authors: Whitehead Craig , Miller Michelle , Crotty Maria
Published: January 2004

Objective: To compare the four-month outcomes of fallers and nonfallers as well as those with slow gait speed in patients with hip fracture successfully discharged back to the community.

Design: Prospective study with four-month follow-up data.

Setting: Community sample of survivors of hip fracture who have completed their rehabilitation programme.

Subjects: A consecutive sample of 73 community-dwelling, cognitively intact older adults admitted to hospital following a fall-related hip fracture and available to complete a follow-up assessment at four months.

Main outcome measures: At baseline, data collection consisted of the Modified Barthel Index (MBI), Mini Mental State Examination (MMSE), sociodemographics and medical history. At four months follow-up, data collection consisted of the MBI, London Handicap Scale (LHS), Berg Balance Scale (BBS), a 10-metre timed walk test, Falls Efficacy Scale (FES) and the Activities Balance Confidence (ABC) scale. Participants were also asked to recall if they had fallen in the four months since their fracture.

Results: Seventy-three participants had complete data for evaluation. There was minimal disability with a mean MBI of 91.2 but there was some residual handicap with a mean LHS of 0.67. Those who had fallen had lower selfefficacy (FES) and greater handicap (LHS). Those with slower gait speed were more handicapped (LHS), had lower self-efficacy (FES and ABC) and lower balance scores (BBS).

Conclusions: Measuring ADL disability alone loses valuable information in community-dwelling survivors of hip fracture. Falls after hip fracture should be a target for treatment and our data give some weight to the idea of a fall fracture cycle. Gait speed, which may re‘ect lower limb strength, is also a target for therapeutic interventions. These measures should be included in clinical practice.
The ACR nomenclature for CNS lupus revisited
Authors: Nived O , Sturfelt G , Liang M H , De Pablo P
Published: January 2004

Neuropsychiatric systemic lupus erythematosus (NPSLE) involves a wide range of peripheral and central nervous system manifestations. These manifestations are complex and their pathophysiology is poorly understood. NPSLE can precede the onset of lupus or occur at any time during its course. The American College of Rheumatology (ACR) developed a standardized nomenclature system providing case definitions for the neuropsychiatricsyndromes of systemic lupus erythematosus(SLE) to facilitate and enhance patient classification and reporting requirements in clinical research. Estimates of NPSLE prevalencehave ranged widely and most are based on research conducted before the introduction of ACR case definitions. This paper reviews the early experience with the ACR nomenclature use and possible future directions for its improvement. The identification and categorization of the major neuropsychiatricsyndromes in SLE using ACR case definitions seems to be adequate, however the mildest and most subjective of the syndromes are the most problematic. Even if the definitions in their present form might have drawbacks the only way forward is further use of ACR nomenclature, pooling data from different populations, and collection of experienceas a basis for improvement. The acquisitionof normative data for ethnic, age and sex stratification would extend their usefulness.
Cognitive dysfunction and antiphospholipid antibodies in systemic lupus erythematosus
Authors: Denburg S D , Denburg J A
Published: January 2004

Nervous system involvement in systemic lupus erythematosus (SLE) is typically diagnosed on the basis of clinical psychiatric and/or neurologic syndromes (NPSLE). Neuropsychologicaltests can be used to assess nervous system integrityeven in the absence of major NP syndromes. Their application has uncovered significant cognitive dysfunction, ranging from mild to severe, in a sizeable proportion of SLE patients irrespective of clinical NP status. Cognitive dysfunction has now been accepted as a bona fide manifestation of NPSLE. The heterogeneityof clinical NPSLE manifestations is paralleled by the diversity of cognitive deficits reported in different studies and within different patients. The success of attempts to explain these deficits on the basis of potentialpathogeneticmechanisms, such as antibrain antibodies and proinflammatory cytokines, has been uneven. To date, the most robust findings have emerged in relation to antiphospholipid antibodies, which carry with them important therapeutic implications.
Headache and systemic lupus erythematosus
Authors: Cuadrado M J , Sanna G
Published: January 2004

Headache is a common feature in patients with systemic lupus erythematosus (SLE) and represents a significant source of patient discomfort. The exact prevalence of headache in SLE is unknown. The results of different studies widely vary, most likely due to the use of different classification for headache and the lack of controls in most studies. The relationshipbetween headache and SLE is also unclear since it is difficult to determine which degree and type of headaches can be explained on the basis of chronic illness, or as part of the disease spectrum of SLE. No pathogenic mechanism has so far been described that can fully explain headache induced by SLE. The role of circulating cytokines, vascular injury, neuronal damage or antiphospholipid antibodies (aPL) in the development of headache in SLE patients is also a matter of debate. Other concomitant causes such as infection or hypertension should be excluded before assuming that headache is a feature of SLE activity. Therapeutic approach of headache SLE-related remains empirical and based on clinical experience.
An Intercultural Nursing Perspective on Autonomy
Authors: Hanssen Ingrid
Published: January 2004

This article is based on an empirical study regarding ethical challenges in intercultural nursing. The focus is on autonomy and disclosure. Autonomy is a human capacity that has become an important ethical principle in nursing. Although the relationship between autonomy and patients’ possibly harmful choices is discussed, the focus is on ‘forced’ autonomy. Nurses seem to equate respect with autonomy; it seems to be hard to cope with the fact that there are patients who voluntarily undergo treatment but who actively participate neither in the treatment offered nor in making choices regarding that treatment. Nurses’ demand for patients to be autonomous may in some cases jeopardize the respect, integrity and human worth that the ethical principle of autonomy is meant to ensure. Even though respect for a person’s autonomy is also respect for the person, one’s respect for the person in question should not depend on his or her capacity or aptitude to act autonomously.

Is autonomy necessarily a universal ethical principle? This article negates this question and, through the issues of culture, individualism versus collectivism, first- and second- order autonomy, communication and the use of family interpreters, and respect, an attempt is made to explain why.
Caring About - Caring For: moral obligations and work responsibilities in intensive care nursing
Authors: Cronqvist Agneta , Theorell Töres , Burns Tom , Lützén Kim
Published: January 2004

The aim of this study was to analyse experiences of moral concerns in intensive care nursing. The theoretical perspective of the study is based on relational ethics, also referred to as ethics of care. The participants were 36 intensive care nurses from 10 general, neonatal and thoracic intensive care units. The structural characteristics of the units were similar: a high working pace, advanced technology, budget restrictions, recent reorganization, and shortage of experienced nurses. The data consisted of the participants’ examples of ethical situations they had experienced in their intensive care unit. A qualitative content analysis identified five themes: believing in a good death; knowing the course of events; feelings of distress; reasoning about physicians’ ‘doings’ and tensions in expressing moral awareness. A main theme was formulated as caring about - caring for: moral obligations and work responsibilities. Moral obligations and work responsibilities are assumed to be complementary dimensions in nursing, yet they were found not to be in balance for intensive care nurses. In conclusion there is a need to support nurses in difficult intensive care situations, for example, by mentoring, as a step towards developing moral action knowledge in the context of intensive care nursing.
The Concept of Futility in Health Care Decision Making
Authors: Bailey Susan
Published: January 2004

Life saving or life sustaining treatment may not be instigated in the clinical setting when such treatment is deemed to be futile and therefore not in the patient’s best interests. The concept of futility, however, is related to many assumptions about quality and quantity of life, and may be relied upon in a manner that is ethically unjustifiable. It is argued that the concept of futility will remain of limited practical use in making decisions based on the best interests principle because it places such high demands on the individual responsible for decision making. This article provides a critical analysis of futility (in the context of the best interests decision-making principle), and proposes an ethically defensible notion of futility.
Frequency of Incomplete Abdominal Aorta Visualization by Emergency Department Bedside Ultrasound
Authors: Blaivas Michael , Theodoro Daniel
Published: January 2004

Objectives: To determine how often emergency physicians (EPs) scanning the abdominal aorta (AA) of nonfasted emergency department (ED) patients are able to visualize the entire AA. Methods: The authors performed a retrospective study of patients receiving ultrasound (US) by EPs to rule out abdominal aortic aneurysm (AAA) at a suburban Level I ED. For patients being evaluated for possible AAA, EPs evaluated the entire length of the AA with US in short axis, making standard proximal, middle, and distal measurements. AAA was defined as dilation of the AA to >3 cm. Video of each US and data sheets were evaluated by a hospital‐credentialed sonologist for visualization of the AA. Any portions of the AA not visualized were noted. If one third or more of the length of the AA was not seen, the examination was considered inadequate, allowing for potentially missing an AAA. Statistical analysis included descriptive statistics. Results: Ultrasounds of 207 patients were completed. In 35 patients (17%), a portion of the AA less than one third its length was not seen. In 17 patients (8%), a significant portion of the AA (at least one third its length) could not be visualized and therefore could have potentially concealed an AAA. In four patients, the AA could not be seen at all. There were 29 AAAs discovered (14%), and none were missed. Conclusions: Significant portions of AA (at least one third of its length) were not visualized on bedside US in 8% of nonfasted patients; this rate is higher than radiology studies of fasted patients receiving US for evaluation of their aortas.
Predictors of Emergency Department Patient Satisfaction: Stability over 17 Months
Authors: Boudreaux Edwin D. , D'Autremont Sarah , Wood Karen , Jones Glenn N.
Published: January 2004

Objectives: The contradictory findings reported in the emergency department (ED) patient satisfaction literature may be due to methodologic differences between studies, as well as actual differences in predictors. The authors examined the stability of predictors of ED patient satisfaction across multiple assessments over 17 months. Methods: All patients who presented for emergency care to the authors' hospital during four designated time periods spanning 17 months were eligible. The participants were contacted by telephone and the following were assessed: demographics, visit characteristics, perceived waiting times, subjective quality of care indicators, and overall satisfaction. The authors computed logistic regressions to predict overall satisfaction for each of the four periods. They compared the results across the assessments, both visually and using an aggregated logistic regression, to determine the consistency of the final equations. Interpretations based on traditional p‐value cut‐offs and odds ratios (ORs) were compared. Results: When using a p‐value cut‐off strategy of p < 0.05, notable discrepancies in the predictors of overall satisfaction were common. Six indicators, including age, perceived wait before bed placement, perceived wait before physician evaluation, physician care, discharge instructions, and waiting time satisfaction, were statistically associated with satisfaction for only one of the four assessments. In contrast, examining the size of the ORs associated with each predictor showed far fewer discrepancies. Only physician care appeared to have large differences in the strength of its relation to overall satisfaction. This trend was confirmed by the aggregated logistic regression analysis. Conclusions: Using p‐value cut‐offs as the sole criterion for interpreting which variables are most important in determining ED patient satisfaction is ill‐advised, and may lead to spurious conclusions of discrepant findings. Nevertheless, some determinants of ED satisfaction likely differ meaningfully based on the cohort that is being examined. Overgeneralizing conclusions derived from a single ED patient satisfaction study should be avoided, especially those studies that are cross‐sectional and use a single site.
Performance of a Novel Clinical Score, the Pediatric Asthma Severity Score (PASS), in the Evaluation of Acute Asthma
Authors: Gorelick Marc H. , Stevens Molly W. , Schultz Theresa R. , Scribano Philip V.
Published: January 2004

Objectives: To evaluate the reliability, validity, and responsiveness of a new clinical asthma score, the Pediatric Asthma Severity Score (PASS), in children aged 1 through 18 years in an acute clinical setting. Methods: This was a prospective cohort study of children treated for acute asthma at two urban pediatric emergency departments (EDs). A total of 852 patients were enrolled at one site and 369 at the second site. Clinical findings were assessed at the start of the ED visit, after one hour of treatment, and at the time of disposition. Peak expiratory flow rate (PEFR) (for patients aged 6 years and older) and pulse oximetry were also measured. Results: Composite scores including three, four, or five clinical findings were evaluated, and the three‐item score (wheezing, prolonged expiration, and work of breathing) was selected as the PASS. Interobserver reliability for the PASS was good to excellent (kappa = 0.72 to 0.83). There was a significant correlation between PASS and PEFR (r= 0.27 to 0.37) and pulse oximetry (r= 0.29 to 0.41) at various time points. The PASS was able to discriminate between those patients who did and did not require hospitalization, with area under the receiver operating characteristic curve of 0.82. Finally, the PASS was shown to be responsive, with a 48% relative increase in score from start to end of treatment and an overall effect size of 0.62, indicating a moderate to large effect. Conclusions: This clinical score, the PASS, based on three clinical findings, is a reliable and valid measure of asthma severity in children and shows both discriminative and responsive properties. The PASS may be a useful tool to assess acute asthma severity for clinical and research purposes.
End‐of‐life Models and Emergency Department Care
Authors: Chan Garrett K.
Published: January 2004

Many people die in emergency departments (EDs) across the United States from sudden illnesses or injuries, an exacerbation of a chronic disease, or a terminal illness. Frequently, patients and families come to the ED seeking lifesaving or life‐prolonging treatment. In addition, the ED is a place of transition—patients usually are transferred to an inpatient unit, transferred to another hospital, or discharged home. Rarely are patients supposed to remain in the ED. Currently, there is an increasing amount of literature related to end‐of‐life care. However, these end‐of‐life care models are based on chronic disease trajectories and have difficulty accommodating sudden‐death trajectories common in the ED. There is very little information about end‐of‐life care in the ED. This article explores ED culture and characteristics, and examines the applicability of current end‐of‐life care models.
Trauma Team Activation Criteria as Predictors of Patient Disposition from the Emergency Department
Authors: Kohn Michael A. , Hammel Jean M. , Bretz Stephen W. , Stangby Ann
Published: January 2004

Many trauma centers use mainly physiologic, first‐tier criteria and mechanism‐related, second‐tier criteria to determine whether and at what level to activate a multidisciplinary trauma team in response to an out‐of‐hospital call. Some of these criteria result in a large number of unnecessary team activations while identifying only a few additional patients who require immediate operative intervention. Objectives: To separately evaluate the incremental predictive value of individual first‐tier and second‐tier trauma team activation criteria for severe injury as reflected by patient disposition from the emergency department (ED). Methods: This was a prospective cohort study in which activation criteria were collected prospectively on all adult patients for whom the trauma team was activated during a five‐month period at an urban, Level 1 trauma center. Severe injury disposition (“appropriate” team activation) was defined as immediate operative intervention, admission to the intensive care unit (ICU), or death in the ED. Data analysis consisted of recursive partitioning and multiple logistic regression. Results: Of the 305 activations for the mainly physiologic first‐tier criteria, 157 (51.5%) resulted in severe injury disposition. The first‐tier criterion that caused the greatest increase in “inappropriate” activations for the lowest increase in “appropriate” activations was “age > 65.” Of the 34 additional activations due to this criterion, seven (20.6%) resulted in severe injury disposition. Of the 700 activations for second‐tier, mechanism‐related criteria, 54 (7.7%) resulted in ICU or operating room admissions, and none resulted in ED death. The four least predictive second‐tier criteria were “motorcycle crash with separation of rider,”“pedestrian hit by motor vehicle,”“motor vehicle crash with rollover,” and “motor vehicle crash with death of occupant.” Of the 452 activations for these four criteria, only 18 (4.0%) resulted in ICU or operating room admission. Conclusions: The four least predictive second‐tier, mechanism‐related criteria added little sensitivity to the trauma team activation rule at the cost of substantially decreased specificity, and they should be modified or eliminated. The first‐tier, mainly physiologic criteria were all useful in predicting the need for an immediate multidisciplinary response. If increased specificity of the first‐tier criteria is desired, the first criterion to eliminate is “age > 65.”
Out‐of‐hospital Care of Critical Drug Overdoses Involving Cardiac Arrest
Authors: Paredes Valentine L. , Rea Thomas D. , Eisenberg Mickey S. , Cobb Leonard A. , Copass Michael K. , Cagle Anthony , Martin Thomas G.
Published: January 2004

Objectives: Death from acute drug poisoning, also termed drug overdose, is a substantial public health problem. Little is known regarding the role of emergency medical services (EMS) in critical drug poisonings. This study investigates the involvement and potential mortality benefit of EMS for critical drug poisonings, characterized by cardiovascular collapse requiring cardiopulmonary resuscitation (CPR). Methods: The study population was composed of death events caused by acute drug poisoning, defined as poisoning deaths and deaths averted (persons successfully resuscitated from out‐of‐hospital cardiac arrest by EMS) in King County, Washington, during the year 2000. Results: Eleven persons were successfully resuscitated and 234 persons died from cardiac arrest caused by acute drug poisoning, for a total of 245 cardiac events. The EMS responded to 79.6% (195/245), attempted resuscitation in 34.7% (85/245), and successfully resuscitated 4.5% (11/245) of all events. Among the 85 persons for whom EMS attempted resuscitation, opioids, cocaine, and alcohol were the predominant drugs involved, although over half involved multiple drug classes. Among the 11 persons successfully resuscitated, return of circulation was achieved in six following EMS cardiopulmonary resuscitation alone, in one following CPR and defibrillation, and in the remaining four after additional advanced life support. Conclusions: In this community, EMS was involved in the majority of acute drug poisonings characterized by cardiovascular collapse and may potentially lower total mortality by approximately 4.5%. The results show that, in some survivors, return of spontaneous circulation may be achieved with CPR alone, suggesting a different pathophysiology in drug poisoning compared with cardiac arrest due to heart disease.
Advanced Statistics: Linear Regression, Part II: Multiple Linear Regression
Authors: Marill Keith A.
Published: January 2004

The applications of simple linear regression in medical research are limited, because in most situations, there are multiple relevant predictor variables. Univariate statistical techniques such as simple linear regression use a single predictor variable, and they often may be mathematically correct but clinically misleading. Multiple linear regression is a mathematical technique used to model the relationship between multiple independent predictor variables and a single dependent outcome variable. It is used in medical research to model observational data, as well as in diagnostic and therapeutic studies in which the outcome is dependent on more than one factor. Although the technique generally is limited to data that can be expressed with a linear function, it benefits from a well‐developed mathematical framework that yields unique solutions and exact confidence intervals for regression coefficients. Building on Part I of this series, this article acquaints the reader with some of the important concepts in multiple regression analysis. These include multicollinearity, interaction effects, and an expansion of the discussion of inference testing, leverage, and variable transformations to multivariate models. Examples from the first article in this series are expanded on using a primarily graphic, rather than mathematical, approach. The importance of the relationships among the predictor variables and the dependence of the multivariate model coefficients on the choice of these variables are stressed. Finally, concepts in regression model building are discussed.
A Monomeric, Donor-free Lithium Complex with a New Overcrowded β-Diketiminato Ligand
Authors: Takeda Nobuhiro , Hamaki Hirofumi , Tokitoh Norihiro
Published: January 2004

A monomeric, donor-free complex of lithium with a new overcrowded β-diketiminato ligand, [Li{TbtNC(Me)CHC(Me)NMes}] (Tbt = 2,4,6-[CH(SiMe3)2]3C6H2, Mes = mesityl), was synthesized and isolated as colorless crystals. Its unique structure was revealed by X-ray structural analysis to be compared with those of donor-coordinated lithium β-diketiminates.
Synthesis of the Boron Complex Composed of the Noncyclic Ligands Having Plural Hydroxy Groups and the Binding Ability Toward Lanthanoid Ions
Authors: Kameta Naohiro , Hiratani Kazuhisa , Houjou Hirohiko , Kanesato Masatoshi
Published: January 2004

The boron complex composed of the noncyclic ligand having plural hydroxy groups behaves as a complex ligand and a forms hetero-binuclear complex with a lanthanoid ion.
A Low-temperature Coreduction Route to Boron Nitride Flakes and Hollow Spheres
Authors: Chen Luyang , Gu Yunle , Shi Liang , Yang Zeheng , Ma Jianhua , Qian Yitai
Published: January 2004

Boron nitride flakes and hollow spheres were synthesized by coreduction of NH4Cl and BBr3 using sodium as reductant. X-ray powder diffraction (XRD) pattern could be indexed as hexagonal BN. The X-ray photoelectron spectra (XPS) were used to determine the composition ratio, which is B:N = 1:1.05. The transmission electron microscopy (TEM) images showed flake-like and hollow spherical morphology.
A Reactive Variable Neighborhood Search for the Vehicle-Routing Problem with Time Windows
Authors: Bräysy Olli
Published: January 2004

The purpose of this paper is to present a new deterministic metaheuristic based on a modification of the variable neighborhood search of Mladenovic and Hansen (1997) for solving the vehicle-routing problem with time windows. Results are reported for the standard 100, 200, and 400 customer data sets by Solomon (1987) and Gehring and Homberger (1999), and two real-life problems by Russell (1995). The findings indicate that the proposed procedure outperforms other recent local searches and metaheuristics. In addition, four new best-known solutions were obtained. The proposed procedure is based on a new four-phase approach. In this approach an initial solution is first created using new route-construction heuristics followed by a route-elimination procedure to improve the solutions regarding the number of vehicles. In the third phase the solutions are improved in terms of total traveled distance using four new local-search procedures proposed in this paper. Finally, in phase four, the best solution obtained is improved by modifying the objective function to escape from a local minimum.
K-Cuts: A Variation of Gomory Mixed Integer Cuts from the LP Tableau
Authors: Cornuéjols Gérard , Li Yanjun , Vandenbussche Dieter
Published: January 2004

For an integer program, a k-cutis a cutting plane generated by the Gomory mixed integer procedure from a row of the LP tableau after multiplying it by a positive integer k. With this terminology, Gomory mixed integer cuts are just 1-cuts. In this paper, we compare the k-cuts (k= 2) with Gomory mixed integer cuts. In particular, we prove in the pure case that with exactly 50% probability the k-cuts perform better variable-wise than the Gomory mixed integer cuts. Some computational experiments on knapsack problems are reported to illustrate this property.
The Use of Eigenvalues for Finding Equilibrium Probabilities of Certain Markovian Two-Dimensional Queueing Problems
Authors: Grassmann Winfried K.
Published: January 2004

A number of papers have appeared recently using eigenvalues for solving steady-state queueing problems. In this paper, we analyze Markovian systems with two state variables, the level X1 and the phase X2, X1 ≤ 0, 0 ≤ X2 ≤ N. Except for some boundary levels, the rates of the events are independent of the level, and no event can change X1, X2, or X1 + X2 by more than 1. In this case, the eigenvectors are essentially Sturm sequences, which implies that all eigenvalues are real. The properties of the Sturm sequences allow us to design an extension of the binary search to find all eigenvalues. As it turns out, once the interval containing an eigenvalue is narrowed down sufficiently, it is preferable to use Newton's method. A computational-complexity study indicates that the resulting algorithm should be signicantly faster than matrix-iterative methods. Two numerical examples are discussed involving servers with breakdowns, and in both cases, our method yields highly accurate results. Tentative reasons why this is to be expected are provided.
Synthesis and Decomposition of Processes in Organizations
Authors: Basu Amit , Blanning Robert W.
Published: January 2004

Organizations today face increasing pressures to integrate their processes across disparate divisions and functional units, in order to remove inefficiencies as well as to enhance manageability. Process integration involves two major types of changes to process structure: (1) synthesizing processes from separate but interdependent subprocesses, and (2) decomposing aggregate processes into distinct subprocesses that are more manageable. We present an approach to facilitate this type of synthesis and decomposition through formal analysis of process structure using a mathematical structure called a metagraph.
A Research Note Regarding the Development of the Consensus on Appropriation Scale
Authors: Allport Christopher D. , Kerler William A.
Published: January 2004

Measurement is perhaps the most difficult aspect of behavioral research. In a recent edition ofISR, a scale for consensus on appropriation was developed. Consensus on appropriation is one of three global constructs incorporated in adaptive structuration theory (Poole and DeSanctis 1990). The principal components analysis on the initial questionnaire revealed two factors with eigenvalues greater than one. While the methods used to develop the scale were thorough, the weaker factor was excluded from the rest of the analysis with little justification. We suggest that this finding has two possible explanations, multidimensionality or response bias. This research note suggests that in addition to the convergent and discriminant validity that Salisbury et al. (2002) provided for the consensus on appropriation scale, we may have an opportunity to further refine the measurement of this construct. By further exploring this principal component finding, consensus on appropriation may be better understood and measured.
Consumer Sequential Search: Not Enough or Too Much?
Authors: Zwick Rami , Rapoport Amnon , Lo Alison King Chung , Muthukrishnan A. V.
Published: January 2004

We study sequential search behavior in a generalized "secretary problem" in which a single object is to be selected from a set ofnalternatives. Alternatives are inspected in a random order, one at a time, and only the rank order of the current alternative relative to the ones that have already been observed can be ascertained. At each period, the consumer may either accept the current alternative, continue to search and pay a fixed cost, or recall an alternative that has already been inspected. A recalled alternative is assumed to be available with a known probability. The consumer's goal is to select the overall best alternative from the fixed set.

We describe the results of an experiment designed to test the optimal model and compare it to a behavioral decision model that incorporates local patterns of the observed sequence. Both set size and search cost are manipulated experimentally in a 2x2 factorial design. Our results show that cost and set size affect the amount of search in the predicted direction. However, in the two no-cost conditions subjects search too little in comparison to the optimal model, whereas in the two cost conditions they search too much. The behavioral decision rule that we propose provides a possible account for the observed pattern of the behavioral regularities.
Modeling the Clickstream: Implications for Web-Based Advertising Efforts
Authors: Chatterjee Patrali , Hoffman Donna L. , Novak Thomas P.
Published: January 2004

In this paper, we develop an analytical approach to modeling consumer response to banner ad exposures at a sponsored content Web site that reveals significant heterogeneity in (unobservable) click proneness across consumers. The effect of repeated exposures to banner ads is negative and nonlinear, and the differential effect of each successive ad exposure is initially negative, though nonlinear, and levels off at higher levels of passive ad exposures. Further, significant correlations between session and consumer click proneness and banner exposure sensitivity suggest gains from repeated banner exposures when consumers are less click prone. For a particular number of sessions, more clicks are generated from consumers who revisit over a longer period of time, than for those with the same number of sessions in a relatively shorter timeframe. We also find that consumers are equally likely to click on banner ads placed early or late in navigation path and that exposures have a positive cumulative effect in inducing click-through in future sessions. Our results have implications for online advertising response measurement and dynamic ad placement, and may help guide advertising media placement decisions.
Commissioned Paper: Capacity Management, Investment, and Hedging: Review and Recent Developments
Authors: Van Mieghem Jan A.
Published: January 2004

This paper reviews the literature on strategic capacity management concerned with determining the sizes, types, and timing of capacity investments and adjustments under uncertainty. Specific attention is given to recent developments to incorporate multiple decision makers, multiple capacity types, hedging, and risk aversion. Capacity is a measure of processing abilities and limitations and is represented as a vector of stocks of various processing resources, while investment is the change of capacity and includes expansion and contraction. After discussing general issues in capacity investment problems, the paper reviews models of capacity investment under uncertainty in three settings:

The first reviews optimal capacity investment by single and multiple risk-neutral decision makers in a stationary environment where capacity remains constant. Allowing for multiple capacity types, the associated optimal capacity portfolio specifies the amounts and locations of safety capacity in a processing network. Its key feature is that it is unbalanced; i.e., regardless of how uncertainties are realized, one typically will never fully utilize all capacities. The second setting reviews the adjustment of capacity over time and the structure of optimal investment dynamics. The paper ends by reviewing how to incorporate risk aversion in capacity investment and contrasts hedging strategies involving financial versus operational means.
Matching Demand and Supply to Maximize Profits from Remanufacturing
Authors: Guide V. Daniel R. , Teunter Ruud H. , Van Wassenhove Luk N.
Published: January 2004

The profitability of remanufacturing depends on the quantity and quality of product returns and on the demand for remanufactured products. The quantity and quality of product returns can be influenced by varying quality-dependent acquisition prices, i.e., by using product acquisition management. Demand can be influenced by varying the selling price. We develop a simple framework for determining the optimal prices and the corresponding profitability. We motivate and illustrate our framework using an application from the cellular telephone industry.
Capacity Investments in Supply Chains: Sharing the Gain Rather Than Sharing the Pain
Authors: Tomlin Brian
Published: January 2004

In this paper, we investigate price-only contracts in supply chain capacity procurement games. For a two-party supply chain, comprising a manufacturer and a supplier that both invest in capacity, we prove the existence of a class of coordinating price-only contracts that arbitrarily allocate the supply chain profit. Moreover, if the supplier's reservation profit is below a certain threshold, the manufacturer's optimal contract is a quantity-premium price-only schedule, that is, the average wholesale price per unit increases in the order size. We prove that the manufacturer prefers simple piecewise-linear quantity-premium contracts to linear contracts and show numerically that such contracts are highly efficient. We extend our results for piecewise-linear price schedules to N-supplier assembly systems. We also enrich the voluntary compliance regime of Cachon and Lariviere (2001). With this enrichment, we prove that share-the-pain contracts, such as firm commitment and options contracts, increase supplier capacity in the full information case, a result that contrasts with that of Cachon and Lariviere. Finally, we investigate when a manufacturer prefers single-breakpoint quantity premiums to firm commitments.
Interactive Multicriteria Optimization for Multiple-Response Product and Process Design
Authors: Köksalan Murat , Plante Robert D.
Published: January 2004

We consider product and process design problems (hereafter collectively called process design problems) that address issues associated with the assessment of optimum levels for process inputs that influence multiple-process performance measures. While this problem context encompasses many possible applications, we focus primarily on multiple-response design problems that have been widely studied in the quality improvement and quality management literature. For such problems, several optimization criteria have been proposed, including maximization of process yield, maximization of process capability, minimization of process costs, etc. In this research, we propose a method that accounts for many of these criteria via a procedure that interacts with and relies on the preferences of a decision maker (DM). The interactive procedure evolves from the convergence of three areas of research: notably, the research in multiple-response design, the research in multicriteria optimization, and recent developments in global optimization. The proposed interactive method is illustrated and comparatively assessed via two well-known problems in multiple-response design. Although the interactive procedure is developed for application in multiple-response design, it is not limited to this problem context. The concepts and methods developed in this research have applicability to problems that can be characterized by process inputs and process performance, such as supply chain management and multidisciplinary design optimization.
Erratum to Bounds in “Serial Production/Distribution Systems Under Service Constraints”
Authors: Boyaci Tamer , Gallego Guillermo , Shang Kevin H. , Song Jing-Sheng
Published: January 2004

We noticed an error in the upper bound on the optimal system stock in Boyaci and Gallego (2001). We provide a procedure to compute the correct bound.
The Linear Programming Approach to Approximate Dynamic Programming
Authors: de Farias D. P. , Van Roy B.
Published: January 2004

The curse of dimensionality gives rise to prohibitive computational requirements that render infeasible the exact solution of large-scale stochastic control problems. We study an efficient method based on linear programming for approximating solutions to such problems. The approach “fits” a linear combination of pre-selected basis functions to the dynamic programming cost-to-go function. We develop error bounds that offer performance guarantees and also guide the selection of both basis functions and “state-relevance weights” that influence quality of the approximation. Experimental results in the domain of queueing network control provide empirical support for the methodology.
Diffusion of Innovations Under Supply Constraints
Authors: Kumar Sunil , Swaminathan Jayashankar M.
Published: January 2004

In this paper we present a canonical setting that illustrates the need for explicitly modeling interactions between manufacturing and marketing/sales decisions in a firm. We consider a firm that sells an innovative product with a given market potential. The firm may not be able to meet demand due to capacity constraints. For such firms, we present a new model of demand, modified from the original model of Bass, to capture the effect of unmet past demand on future demand. We use this model to find production and sales plans that maximize profit during the lifetime of the product in a firm with a fixed production capacity. We conduct an extensive numerical study to establish that the trivial, myopic sales plan that sells the maximal amount possible at each time instant is not necessarily optimal. We show that a heuristic “build-up” policy, in which the firm does not sell at all for a period of time and builds up enough inventory to never lose sales once it begins selling, is a robust approximation to the optimal policy. Specializing to a lost-sales setting, we prove that the optimal sales plan is indeed of the “build-up” type. We explicitly characterize the optimal build-up period and analytically derive the optimal initial inventory and roll-out delay. Finally, we show that the insights obtained in the fixed capacity case continue to hold when the firm is able to dynamically change capacity.
Commitment of Electric Power Generators Under Stochastic Market Prices
Authors: Valenzuela Jorge , Mazumdar Mainak
Published: January 2004

A formulation for the commitment of electric power generators under a deregulated electricity market is proposed. The problem is expressed as a stochastic optimization problem in which expected profits are maximized while meeting demand and standard operating constraints. Under an assumption of perfect competition, when an electric power producer has the option of trading electricity at market prices, a unit commitment schedule can be obtained by optimizing the self-commitment of each unit separately subject to stochastic prices. Three certainty-equivalent formulations of the stochastic self-commitment problem are provided. The procedures involve application of dynamic programming, statistical analysis, and asymptotic probability computations. The price of electricity is represented by a stochastic model depending on demand, generating unit reliabilities, and temperature fluctuations. We use several approximation methods (normal, Edgeworth series expansion, and Monte Carlo simulation) for computing the required probability distributions. Numerical examples are provided for a market consisting of 150 generating units.
Genetically Engineered Decision Trees: Population Diversity Produces Smarter Trees
Authors: Fu Zhiwei , Golden Bruce , Lele Shreevardhan , Raghavan S. , Wasil Edward
Published: January 2004

When considering a decision tree for the purpose of classification, accuracy is usually the sole performance measure used in the construction process. In this paper, we introduce the idea of combining a decision tree's expected value and variance in a new probabilistic measure for assessing the performance of a tree. We develop a genetic algorithm for constructing a tree using our new measure and conduct computational experiments that show the advantages of our approach. Further, we investigate the effect of introducing diversity into the population used by our genetic algorithm. We allow the genetic algorithm to simultaneously focus on two distinct probabilistic measures—one that is risk averse and one that is risk seeking. Our bivariate genetic algorithm for constructing a decision tree performs very well, scales up quite nicely to handle data sets with hundreds of thousands of points, and requires only a small percent of the data to generate a high-quality decision tree. We demonstrate the effectiveness of our algorithm on three large data sets.
Resource Allocation Among Simulation Time Steps
Authors: Glasserman Paul , Staum Jeremy
Published: January 2004

Motivated by the problem of efficient estimation of expected cumulative rewards or cashflows, this paper proposes and analyzes a variance reduction technique for estimating the expectation of the sum of sequentially simulated random variables. In some applications, simulation effort is of greater value when applied to early time steps rather than shared equally among all time steps; this occurs, for example, when discounting renders immediate rewards or cashflows more important than those in the future. This suggests that deliberately stopping some paths early may improve efficiency. We formulate and solve the problem of optimal allocation of resources to time horizons with the objective of minimizing variance subject to a cost constraint. The solution has a simple characterization in terms of the convex hull of points defined by the covariance matrix of the cashflows. We also develop two ways to enhance variance reduction through early stopping. One takes advantage of the statistical theory of missing data. The other redistributes the cumulative sum to make optimal use of early stopping.
From a Firm-Based to a Community-Based Model of Knowledge Creation: The Case of the Linux Kernel Development
Authors: Lee Gwendolyn K. , Cole Robert E.
Published: January 2004

We propose a new model of knowledge creation in purposeful, loosely coordinated, distributed systems, as an alternative to a firm-based one. Specifically, using the case of the Linux kernel development project, we build a model of community-based, evolutionary knowledge creation to study how thousands of talented volunteers, dispersed across organizational and geographical boundaries, collaborate via the Internet to produce a knowledge-intensive, innovative product of high quality. By comparing and contrasting the Linux model with the traditional/commercial model of software development and firmbased knowledge creation efforts, we show how the proposed model of knowledge creation expands beyond the boundary of the firm. Our model suggests that the product development process can be effectively organized as an evolutionary process of learning driven by criticism and error correction. We conclude by offering some theoretical implications of our community-based model of knowledge creation for the literature of organizational learning, community life, and the uses of knowledge in society.