bluuebunny/crossref_metadata_2025 huggingface dataset:
Price Protection in the Personal Computer Industry
Authors: Lee Hau L. , Padmanabhan V. , Taylor Terry A. , Whang Seungjin
Published: April 2003

Price protection is a commonly used practice between manufacturers and retailers in the personal computer (PC) industry, motivated by drastic declines of product values during the product life cycle. It is a form of rebate given by the manufacturer to the retailer for units unsold at the retailer when the price drops during the product life cycle. It is a controversial policy in the PC industry because it is not clear how such a policy benefits the supply chain and its participants. We show that price protection is an instrument for channel coordination. For products with long manufacturing lead times, so the retailer has a single buying opportunity, a properly chosen price protection credit coordinates the channel. For products with shorter manufacturing lead times, so the retailer has two buying opportunities, price protection alone cannot guarantee channel coordination when wholesale prices are exogenous. However, when the price protection credit is set endogenously together with the wholesale prices, channel coordination is restored. In the two-buying-opportunity setting with fixed wholesale prices, we show that price protection has two primary impacts: (1) shifting sales forward in time and (2) increasing total sales. Finally, we present a simple numerical example that suggests, given the current economics of the PC industry, that price protection under fixed wholesale prices may benefit the total chain and the retailer but hurt the manufacturer.
Information Technology and Productivity: Evidence from Country-Level Data
Authors: Dewan Sanjeev , Kraemer Kenneth L.
Published: April 2003

This paper studies a key driver of the demand for the products and services of the global IT industry—returns from IT investments. We estimate an intercountry production function relating IT and non-IT inputs to GDP output, on panel data from 36 countries over the 1985–1993 period. We find significant differences between developed and developing countries with respect to their structure of returns from capital investments. For the developed countries in the sample, returns from IT capital investments are estimated to be positive and significant, while returns from non-IT capital investments are not commensurate with relative factor shares. The situation is reversed for the developing countries subsample, where returns from non-IT capital are quite substantial, but those from IT capital investments are not statistically significant. We estimate output growth contributions of IT and non-IT capital and discuss the contrasting policy implications for capital investment by developed and developing economies.
The Value of Information Sharing in a Two-Level Supply Chain
Authors: Lee Hau L. , So Kut C. , Tang Christopher S.
Published: April 2003

Many companies have embarked on initiatives that enable more demand information sharing between retailers and their upstream suppliers. While the literature on such initiatives in the business press is proliferating, it is not clear how one can quantify the benefits of these initiatives and how one can identify the drivers of the magnitudes of these benefits. Using analytical models, this paper aims at addressing these questions for a simple two-level supply chain with nonstationary end demands. Our analysis suggests that the value of demand information sharing can be quite high, especially when demands are significantly correlated over time.
An Empirical Analysis of Productivity and Quality in Software Products
Authors: Krishnan M. S. , Kriebel C. H. , Kekre Sunder , Mukhopadhyay Tridas
Published: April 2003

We examine the relationship between life-cycle productivity and conformance quality in software products. The effects of product size, personnel capability, software process, usage of tools, and higher front-end investments on productivity and conformance quality were analyzed to derive managerial implications based on primary data collected on commercial software projects from a leading vendor. Our key findings are as follows. First, our results provide evidence for significant increases in life-cycle productivity from improved conformance quality in software products shipped to the customers. Given that the expenditure on computer software has been growing over the last few decades, empirical evidence for cost savings through quality improvement is a significant contribution to the literature. Second, our study identifies several quality drivers in software products. Our findings indicate that higher personnel capability, deployment of resources in initial stages of product development (especially design) and improvements in software development process factors are associated with higher quality products.
Modeling the Impact of an Outcome-Oriented Reimbursement Policy on Clinic, Patients, and Pharmaceutical Firms
Authors: So Kut C. , Tang Christopher S.
Published: April 2003

Tackling the steep increase in drug costs is an especially important issue among many health care providers and insurers. To entice the clinics to become more cost efficient, the U.S. federal government, as well as many HMOs, have developed various cost containment initiatives recently. However, the impact of these initiatives on the patients' well-being, the clinic's profitability, and the pharmaceutical firm's profitability has not been formally analyzed. In this paper we develop a mathematical model that is intended to examine the impact of a reimbursement policy for drug usage. Despite the simplistic structure of our model, the analysis enhances our understanding of the joint impact of the reimbursement policy on the patients, the clinic, and the pharmaceutical firm. Thus, our analysis can provide valuable information for evaluating the effectiveness of implementing such a reimbursement policy. In addition, we utilize the data gathered from a clinic to help support the assumptions and results of the underlying model.
Perishable Asset Revenue Management with Markovian Time Dependent Demand Intensities
Authors: Feng Youyi , Gallego Guillermo
Published: April 2003

Many industries face the problem of selling a fixed stock of items over a finite horizon. These industries include airlines selling seats before planes depart, hotels renting rooms before midnight, theaters selling seats before curtain time, and retailers selling seasonal items with long procurement lead times. Given a sunk investment in seats, rooms, or winter coats, the objective for these industries is to maximize revenues in excess of salvage value. When demand is price sensitive and stochastic, pricing is an effective tool to maximize expected revenues. In this paper we address the problem of deciding the optimal timing of price changes within a given menu of allowable, possibly time dependent, price paths each of which is associated with a general Poisson process with Markovian, time dependent, predictable intensities. We show that a set of variational inequalities characterize the value functions and the optimal (possibly random) time changes. In addition, we develop an efficient algorithm to compute the optimal value functions and the optimal pricing policy.
Portfolio Optimization Under a Minimax Rule
Authors: Cai Xiaoqiang , Teo Kok-Lay , Yang Xiaoqi , Zhou Xun Yu
Published: April 2003

This paper provides a new portfolio selection rule. The objective is to minimize the maximum individual risk and we use an l∞ function as the risk measure. We provide an explicit analytical solution for the model and are thus able to plot the entire efficient frontier. Our selection rule is very conservative. One of the features of the solution is that it does not explicitly involve the covariance of the asset returns.
Methadone Maintenance and HIV Prevention: A Cost-Effectiveness Analysis
Authors: Zaric Gregory S. , Brandeau Margaret L. , Barnett Paul G.
Published: April 2003

We assess the cost-effectiveness of maintenance treatment for heroin addiction, with emphasis on its role in preventing HIV infection. The analysis is based on a dynamic compartmental model of the HIV epidemic among a population of adults, ages 18 to 44. The population is divided into nine compartments according to infection status and risk group. The model takes into account disease transmission from drug injection and sexual contacts. The health benefits of methadone maintenance and the resulting HIV infections averted are measured in terms of life years gained and quality-adjusted life years gained. Costs considered include all health-care costs (including cost of HIV care and other health care) and the cost of methadone maintenance. The analysis shows that expanding existing methadone maintenance programs is a cost-effective health-care intervention that can play an important role in slowing the spread of HIV and improving the length and quality of life for injection drug users (IDUs), and that such expansion is cost-effective even in populations with low HIV prevalence among IDUs. Incremental expansion of methadone maintenance programs was found to have a cost-effectiveness ratio of between $9,700 and $17,200 per life year gained, and between $6,300 and $10,900 per quality-adjusted life year gained. Although methadone maintenance treatment is provided to IDUs, the analysis shows that significant benefits accrue to non-IDU members of the population. Sensitivity analysis shows that new methadone maintenance treatment slots will be cost-effective even if they are twice as expensive and half as effective in reducing risky behavior as current methadone maintenance programs.
Majorization of Weighted Trees: A New Tool to Study Correlated Stochastic Systems
Authors: Xu Susan H. , Li Haijun
Published: April 2003

Stochastic models with simultaneous arrivals arise naturally in the areas such as synchronized communication networks, flexible manufacturing systems, production/inventory systems, reliability modeling in random environment, etc., with a wide variety of interpretations. Simultaneous arrivals introduce dependence among various components of the system and make the explicit solutions of joint system performance measures either computationally intensive or intractable. This calls for structural analysis of dependence natures of such systems so that the insight gained from the analysis can suggest plausible approaches to develop tight bounds and efficient approximations to key system performance measures.

The usual majorization order on a totally ordered index set and Schur convexity are powerful tools for establishing inequalities, in particular, for stochastic systems. However, the investigation on stochastic systems with simultaneous arrivals leads naturally to the comparison of distributions of parameter values on a tree-structured index set. In this paper, we introduce the notion of majorization with respect to weighted trees. The fundamental strength of tree majorization lies in its ability to make versatile comparisons over two parameter sets defined on a partially ordered index set. We identify several classes of transformations that provide simple characterizations of tree majorization orders. Finally, we apply the new notion to an assemble-to-order system and to a shock model with simultaneous subsystem failures and study the dependence structure of these systems. Our results show that tree majorization and its interplay with various notions of stochastic orders are useful tools to study the dependency of stochastic systems with multivariate, synchronized input processes.
Diffusion Approximations for Some Multiclass Queueing Networks with FIFO Service Disciplines
Authors: Chen Hong , Zhang Hanqin
Published: April 2003

The diffusion approximation is proved for a class of multiclass queueing networks under FIFO service disciplines. In addition to the usual assumptions for a heavy traffic limit theorem, a key condition that characterizes this class is that a J × J matrix G, known as the workload contents matrix, has a spectral radius less than unity, where J represents the number of service stations. The (j, 𝓁)th component of matrix Gcan be interpreted as the long-run average amount of future work for station j that is embodied in a unit of immediate work at station 𝓁. This class includes, as a special case, the feedforward multiclass queueing network and the Rybko-Stolyar network under FIFO service discipline.

A new approach is taken in establishing the diffusion limit theorem. The traditional approach is based on an oblique reflection mapping, but such a mapping is not well defined for the network under consideration. Our approach takes two steps: Arst establishing the C-tightness of the scaled queueing processes, and then completing the proof for the convergence of the scaled queueing processes by invoking the weak uniqueness for the limiting processes, which are semimartingale reflecting Brownian motions.
Management of Multi-Item Retail Inventory Systems with Demand Substitution
Authors: Smith Stephen A. , Agrawal Narendra
Published: April 2003

Customers for retail merchandise can often be satisfied with one of several items. Accounting for demand substitution in defining customer service influences the choice of items to stock and the optimal inventory level for each item stocked. Further, when certain items are not stocked, the resulting substitutions increase the demand for other items, which also affects the optimal stock levels. In this paper, we develop a probabilistic demand model for items in an assortment that captures the effects of substitution and a methodology for selecting item inventory levels so as to maximize total expected profit, subject to given resource constraints. Illustrative examples are solved to provide insights concerning the behavior of the optimal inventory policies, using the negative binomial demand distribution, which has performed well in fitting retail sales data.
Restless Bandits, Linear Programming Relaxations, and a Primal-Dual Index Heuristic
Authors: Bertsimas Dimitris , Niño-Mora José
Published: April 2003

We develop a mathematical programming approach for the classical PSPACE-hard restless bandit problem in stochastic optimization. We introduce a hierarchy of N (where N is the number of bandits) increasingly stronger linear programming relaxations, the last of which is exact and corresponds to the (exponential size) formulation of the problem as a Markov decision chain, while the other relaxations provide bounds and are efficiently computed. We also propose a priority-index heuristic scheduling policy from the solution to the firstorder relaxation, where the indices are defined in terms of optimal dual variables. In this way we propose a policy and a suboptimality guarantee. We report results of computational experiments that suggest that the proposed heuristic policy is nearly optimal. Moreover, the second-order relaxation is found to provide strong bounds on the optimal value.
The Three-Dimensional Bin Packing Problem
Authors: Martello Silvano , Pisinger David , Vigo Daniele
Published: April 2003

The problem addressed in this paper is that of orthogonally packing a given set of rectangular-shaped items into the minimum number of three-dimensional rectangular bins. The problem is strongly NP-hard and extremely difficult to solve in practice. Lower bounds are discussed, and it is proved that the asymptotic worst-case performance ratio of the continuous lower bound is 1/8. An exact algorithm for filling a single bin is developed, leading to the definition of an exact branch-and-bound algorithm for the three-dimensional bin packing problem, which also incorporates original approximation algorithms. Extensive computational results, involving instances with up to 90 items, are presented: It is shown that many instances can be solved to optimality within a reasonable time limit.
Close-Point Spatial Tests and Their Application to Random Number Generators
Authors: L'Écuyer Pierre , Cordeau Jean-François , Simard Richard
Published: April 2003

We study statistical tests of uniformity based on the Lp-distances between the m nearest pairs of points, for n points generated uniformly over the k-dimensional unit hypercube or unit torus. The number of distinct pairs at distance no more than t, for t ≥ 0, is a stochastic process whose initial part, after an appropriate transformation and as n → ∞, is asymptotically a Poisson process with unit rate. Convergence to this asymptotic is slow in the hypercube as soon as k exceeds 2 or 3, due to edge effects, but is reasonably fast in the torus. We look at the quality of approximation of the exact distributions of the tests statistics by their asymptotic distributions, discuss computational issues, and apply the tests to random number generators. Linear congruential generators fail decisively certain variants of the tests as soon as n approaches the square root of the period length.
Railroad Blocking: A Network Design Application
Authors: Barnhart Cynthia , Jin Hong , Vance Pamela H.
Published: April 2003

In this study, we formulate the railroad blocking problems as a network design problem with maximum degree and flow constraints on the nodes and propose a heuristic Lagrangian relaxation approach to solve the problem. The newapproach decomposes the complicated mixed integer programming problem into two simple subproblems so that the storage requirement and computational effort are greatly reduced. A set of inequalities are added to one subproblem to tighten the lower bounds and facilitate generating feasible solutions. Subgradient optimization is used to solve the Lagrangian dual. An advanced dual feasible solution is generated to speed up the convergence of the subgradient method. The model is tested on blocking problems from a major railroad, and the results show that the blocking plans generated have the potential to reduce the railroad's operating costs by millions of dollars annually.
Reducing Labor Costs in an LTL Crossdocking Terminal
Authors: Bartholdi John J. , Gue Kevin R.
Published: April 2003

Handling freight in a crossdocking terminal is labor intensive and therefore costly because workers must unload, sort, and transfer a wide variety of freight from incoming to outgoing trailers. The efficiency of workers depends in large part on how trailers are assigned to doors around the dock; that is, on its layout. A good layout reduces travel distances without creating congestion, but until now no tools have been available to construct such layouts. We describe models of travel cost and three types of congestion typically experienced in crossdocking terminals, and we use them to construct layouts that minimize the labor cost of transferring freight. We report on the use of our models in the less-than-truckload trucking industry, including an implementation at a terminal in Stockton, California that improved productivity by more than 11%.
Performance Analysis and Best Implementations of Old and New Algorithms for the Open-Pit Mining Problem
Authors: Hochbaum Dorit S. , Chen Anna
Published: April 2003

The open-pit mining problem is to determine the contours of a mine, based on economic data and engineering feasibility requirements, to yield maximum possible net income. This practical problem needs to be solved for very large data sets. In practice, moreover, it is necessary to test multiple scenarios, taking into account a variety of realizations of geological predictions and forecasts of ore value.

The industry is experiencing computational difficulties in solving the problem. Yet, the problem is known to be equivalent to the minimum cut or maximum flow problem. For the maximum flow problem there are a number of very efficient algorithms that have been developed over the last decade. On the other hand, the algorithm that is most commonly used by the mining industry has been devised by Lerchs and Grossmann (LG). This algorithm is used in most commercial software packages for open-pit mining.

This paper describes a detailed study of the LG algorithm as compared to the maximum flow “push-relabel” algorithm. We propose here an efficient implementation of the push-relabel algorithm adapted to the features of the open-pit mining problem. We study issues such as the properties of the mine and ore distribution and how they affect the running time of the algorithm. We also study some features that improve the performance of the LG algorithm. The proposed implementations offer significant improvements compared to existing algorithms and make the related sensitivity analysis problem practically solvable.
Trapped in Your Own Net? Network Cohesion, Structural Holes, and the Adaptation of Social Capital
Authors: Gargiulo Martin , Benassi Mario
Published: April 2003

This paper explores the tension between two opposite views on how networks create social capital. Network closure (Coleman 1988) stresses the role of cohesive ties in fostering a normative environment that facilitates cooperation. Structural hole theory (Burt 1992) sees cohesive ties as a source of rigidity that hinders the coordination of complex organizational tasks. The two theories lead to opposite predictions on how the structure of an actor's network may affect his ability to adapt that network to a significant change in task environment. Using data from a newly created special unit within the Italian subsidiary of a multinational computer manufacturer, we show that managers with cohesive communication networks were less likely to adapt these networks to the change in coordination requirements prompted by their new assignments, which in turn jeopardized their role as facilitators of horizontal cooperation within a newly created business unit structure. We conclude with a discussion of the trade-off between the safety of cooperation within cohesive networks and the flexibility provided by networks rich in structural holes.
When Cymbals Become Symbols: Conflict Over Organizational Identity Within a Symphony Orchestra
Authors: Glynn Mary Ann
Published: April 2003

In this qualitative field study, I explore how the construction of a cultural institution's identity is related to the construction of strategic capabilities and resources. I investigated the 1996 musicians’ strike at the Atlanta Symphony Orchestra (ASO), which revealed embedded and latent identity conflicts. The multifaceted and specialized identity of the ASO was reinforced by different professional groups in the organization: the ideologies of musicians and administrators emphasized institutional resource allocations consistent with the legitimating values of their professions, i.e., artistic excellence versus economic utility. These identity claims, made under organizational crisis, accounted for variations in the construction of core competencies. I propose a model that explicates how the construction of core capabilities lies at the intersection of identification and interpretive processes in organizations. Implications are discussed for defining firm capabilities in cultural institutions and for managing organizational forms characterized by competing claims over institutional identity, resources, and core capabilities.
Beyond Networks and Hierarchies: Latent Organizations in the U.K. Television Industry
Authors: Starkey Ken , Barnatt Christopher , Tempest Sue
Published: April 2003

Since the mid 1980s, organization theorists have highlighted the emergence of the networked model of organization as a response to global competition and pressures for increased market flexibility. Cultural industries have not been immune from this development. In this paper, we examine the shift from hierarchy to network in the U.K. television industry. We argue that an important result of this disaggregation is the emergence of latent organization, groupings of individuals and teams of individuals that persist through time and are periodically drawn together for recurrent projects by network brokers who either buy in programmes for publisher-broadcasters or who draw together those artists and technicians who actually produce them. In conclusion, we note how latent organizations may become increasingly important for effective cultural industry production, and in particular how they may provide stable points of reference and recurring work projects for those many individuals now working outside of large, vertically integrated producer-broadcasters.
Linking Organizational Values to Relationships with External Constituents: A Study of Nonprofit Professional Theatres
Authors: Voss Glenn B. , Cable Daniel M. , Voss Zannie Giraud
Published: April 2003

This study explores the organizational values that characterize firms in the nonprofit professional theatre industry, and examines the links between firms' organizational values and their relationships with external constituents. Using grounded research methods, we uncover five value dimensions that are relevant to arts organizations: prosocial, artistic, financial, market, and achievement. Using a sample of 97 nonprofit theatres, we extend our qualitative inquiry with an empirical investigation of how firms enact their organizational values to build and maintain relationships with external constituents. Results from a two-wave survey design indicate consistent patterns of association between organizational values and (1) perceptions of values congruence with external constituents, (2) human resource allocation and programming decisions that firms make to support relationships with external constituents, and (3) the level of financial resources that firms obtain from their relationships with different external constituents. Interestingly, results from both investigations hint at underlying tensions between competing values in cultural firms, such as pressures to be both artistic- and market-oriented.
The Entrepreneurial M-Form: Strategic Integration in Global Media Firms
Authors: Eisenmann Thomas R. , Bower Joseph L.
Published: April 2003

Many researchers believe that bounded rationality prevents CEOs in large, complex, multidivisional (“M-form”) corporations from personally formulating division-level strategies. Instead, CEOs are seen as guiding a “bottom-up” process whereby division managers propose strategies for review and approval by the corporate office. Contrary to this view, we argue that CEOs in global media firms frequently drive strategy in a “top-down” manner, especially when their firms seek to expand by integrating the activities of two or more existing divisions. We refer to such firms as “Entrepreneurial M-forms,” and maintain that their reliance on an activist CEO offers benefits: (1) in turbulent environments, when the use of slow, bottom-up planning processes risks forfeiting first-mover advantages; and (2) when expansion entails major capital commitments, and division managers may be reluctant to accept the career risks associated with sponsorship of “bet-the-company” projects.
Organizational Learning and the Transfer of Knowledge: An Investigation of Quality Improvement
Authors: Levin Daniel Z.
Published: April 2003

Whereas most prior research on the learning curve has focused on improvements in efficiency, this paper deals with the impact of learning on product quality. The key data are measures of automobile reliability published in Consumer Reports. Analysis yields three findings: (1) Quality improves over the production life of a car model with the same kind of regularity as an efficiency learning curve. Thus, there is a quality learning curve. (2) Unlike in the efficiency domain, however, learning in the domain of product reliability is primarily a function of time, and not of how many cars have gone down the assembly line. Thus, quality depends not on the accumulation of production experience per se, but on the intensity of “off-line”quality improvement activities and on the transfer of knowledge from the general environment over time. (3) In contrast to the traditional injunction, “do not buy a new car in its first year of production,”the opposite advice actually seems to apply: In any given year, the newest car models have the best quality. That is, new car-model designs typically include significant quality improvements that are more than enough to outweigh any disruption created in manufacturing by the new model's introduction and that even surpass the incremental improvements made to older, existing car models.
Dealing with Time in Social Inquiry: A Tension Between Method and Lived Experience
Authors: Avital Michel
Published: April 2003

In a series of interviews, organizational researchers acknowledged the key role of time in social inquiry, and their tendency to exclude it in practice. The discrepancy between what researchers think about the incorporation of temporal factors in their research and what they actually do was explained by various pragmatic, methodological, and normative grounds, but they were not aware of other epistemological and ontological barriers related to their choice. The interviews also drew attention to a paradox that stemmed from an experience of ongoing tension between the methodologically prescribed sense of time and the experientially lived impression of time. Further analysis suggests that incorporation of time factors may significantly improve social process research. The study demonstrates that temporal elements do not merely change one's perception of a situation, but also provide a space for a richer and more meaningful interpretation by enabling an improved association of a particular event with one's personal frame of reference and lived experience. In addition, the study suggests that an awareness of the various approaches to time and the application of a consistent ontological framework to the analysis of social phenomena are likely to increase the coherence and congruity of the analysis. No particular perception of time is prescribed here. The emphasis is on self-awareness of the implications of temporalities on social phenomena and on ontological consistency in our research.
Taking Science out of Organization Science: How Would Postmodernism Reconstruct the Analysis of Organizations?
Authors: Weiss Richard M.
Published: April 2003

Postmodernism, an intellectual movement that originated in the humanities, has received considerable attention in the organization theory literature. Because many scholars remain uncertain as to just what this controversial perspective is, the present article offers a straightforward explanation of postmodernism's basic themes. Additionally, the author attempts to provide some balance to the overwhelmingly sympathetic presentations of postmodernism in the organization theory literature by offering a critical assessment of how it would redirect the study of organizations. Consistent with an intellectual divide dating to the Enlightenment, while those engaged in “normal science” are concerned with the question of what is true, it appears that those who sympathize with postmodernism are addressing the question of what is good. Postmodernists, it is argued here, wish to engage in advocacy for values and preferences that they view as putting them in radical opposition to the status quo. To facilitate such advocacy they call for the repudiation of “modernism,” in particular the key modernist notion that there is an objective truth that can be sought out rationally and systematically. Postmodernists adopt, instead, a relativist philosophy, which contends that “truth” must be considered merely subjective, such that one's view of truth is only relative to one's circumstances. Although taking the position that no one can say what is or is not “true” puts them in opposition to mainstream science, it supports their ability to discredit views they oppose, and simultaneously provides a defense against those who would claim that the postmodernist's view is not “true.” Whether the postmodernist approach has the potential to enhance our understanding of organizations is addressed here by examining its philosophical and historical roots, the research and theory that it has so far inspired, and the critical commentary on our field that its adherents have offered.
Social background and age at menarche in Portuguese university students: A note on the secular changes in Portugal
Authors: Padez C.
Published: April 2003

Menarcheal age of a sample of Portuguese university students (n = 3,366), born between 1972 and 1983, age 18–23 years, was analyzed. The influence of parents' educational level and occupation, family size, birth order, and degree of urbanization of girl's locality of residence during childhood and adolescence were analyzed as well as secular trend in the Portuguese population. Mean age at menarche for girls born in 1983 was 12.32 years. Parents' educational level and occupation did not show any significant influence on mean age at menarche. Place of residence during childhood years and adolescence showed a significant effect on mean age at menarche, with girls from rural places with a later age at menarche than those who spent their childhood or adolescence in urban areas (P ≤ 0.01 and P ≤ 0.05 for childhood and adolescence, respectively). Family size and birth order showed the highest effect. Girls born in small families, with one child, matured earlier (12.32 years) than those born in large families with four or more children (12.67 years), (P ≤ 0.01). Also, girls that were first‐born had an earlier menarche (12.41 years) than those who were third or later (12.58 years, P ≤ 0.01). Regression analysis selected family size and place of residence in childhood as the most important determinants of mean age at menarche in our university students. In this sample, from 1972 to 1983, mean age at menarche remained stable. When we considered published data from all the Portuguese population we found a decrease in mean age at menarche from 15 years for girls born in 1880 to 12.44 for those born in the 1980s. This decrease was the result of great improvements in the social and economic living conditions that occurred in Portugal especially after the 1970s concerning nutrition and health care, among many other environmental factors. Am. J. Hum. Biol. 15:415–427, 2003. ©2003 Wiley‐Liss, Inc.
Waist‐to‐hip ratio and adipose tissue distribution: Contribution of subcutaneous adiposity
Authors: Daniel Mark , Martin Alan D. , Drinkwater Donald T. , Clarys Jan P. , Marfell‐Jones Michael J.
Published: April 2003

The waist‐to‐hip ratio (WHR) reflects the relative distribution of adipose tissue in the human body. However, whether this is due to the musculoskeletal structures of the waist and hip or the overlying subcutaneous adipose tissue has been disputed. We measured waist and hip girths in 11 male and 11 female cadavers, aged 55–94 years, before and after complete removal of skin and subcutaneous adipose tissue. Girths measured following removal of subcutaneous adipose tissue were termed “waist gx” and “hip gx”, and their ratio “WHRx”. Masses of regional adipose tissue segments were obtained by complete dissection, and the adipose mass ratios “trunk/arm‐plus‐leg”, “trunk/leg”, “internal/arm‐plus‐leg”, and “internal/leg” were derived. As assessed by analysis of variance, WHR accounted for significant (P < 0.05) portions of the variance in all adipose mass ratios; adjustment for internal adipose mass increased the significance of all these relationships (P < 0.005). The ratio WHRx was not related to any ratio of regional adipose masses. Waist girth was related to trunk (P < 0.001) and internal (P < 0.05) adipose masses, and hip girth was related to arm‐plus‐leg adipose mass (P < 0.0001) and leg adipose mass (P < 0.0001), but waist gx and hip gx were not related to dependent variables. The results indicate that the ability of WHR and waist and hip girths to reflect the regional distribution of adipose tissue in the body is dependent upon the subcutaneous adipose tissue mass of the waist hip area, not its musculoskeletal constituency. Am. J. Hum. Biol. 15:428−432, 2003. © 2003 Wiley‐Liss, Inc.
Workplace health and safety regulations: Impact of enforcement and consultation on workers' compensation claims rates in Washington State
Authors: Baggs James , Silverstein Barbara , Foley Michael
Published: April 2003

Background

There has been considerable debate in the public policy arena about the appropriate mix of regulatory enforcement and consultation in achieving desired health and safety behavior across industries. Recently there has been a shift in federal policy toward voluntary approaches and constraining the scope of enforcement programs, although there is little evidence that this might improve health and safety outcomes. To address this, we examined changes in lost time workers compensation claims rates for Washington State employers who had (1) no OSHA State Plan (WISHA) activity, (2) enforcement, (3) consultation, and (4) both types of visits.

Methods

Compensable claims rates, hours, and WISHA activity were determined for each employer account with a single business location that had payroll hours reported for every quarter from 1997–2000 and more than 10 employees. We used a generalized estimating equations (GEE) approach to Poisson regression to model the association between WISHA activity and claims rate controlling for other external factors.

Results

Controlling for previous claims rate and average size, claims rates for employers with WISHA enforcement activity declined 22.5% in fixed site industry SIC codes compared to 7% among employers with no WISHA activity (P < 0.05), and in non‐fixed site SICs (e.g., construction) claims rates declined 12.8% for employers with enforcement activity compared to a 7.4% decline for those with no WISHA activity (P > 0.10). WISHA consultation activity was not associated with a greater decline in compensable claims rates (−2.3% for fixed sites and +3.5% for non‐fixed sites). WISHA activity did not adversely affect worksite survivability through the study period.

Conclusions

Enforcement inspections are significantly associated with decreasing compensable workers compensation claims rates especially for fixed site employers. We were unable to identify an association between consultation activities and decreasing claims rates. Am. J. Ind. Med. 43:483–494, 2003. © 2003 Wiley‐Liss, Inc.
Dying for work: The magnitude of US mortality from selected causes of death associated with occupation
Authors: Steenland Kyle , Burnett Carol , Lalich Nina , Ward Elizabeth , Hurrell Joseph
Published: April 2003

Background

Deaths due to occupational disease and injury place a heavy burden on society in terms of economic costs and human suffering.

Methods

We estimate the annual deaths due to selected diseases for which an occupational association is reasonably well established and quantifiable, by calculation of attributable fractions (AFs), with full documentation; the deaths due to occupational injury are then added to derive an estimated number of annual deaths due to occupation.

Results

Using 1997 US mortality data, the estimated annual burden of occupational disease mortality resulting from selected respiratory diseases, cancers, cardiovascular disease, chronic renal failure, and hepatitis is 49,000, with a range from 26,000 to 72,000. The Bureau of Labor Statistics estimates there are about 6,200 work‐related injury deaths annually. Adding disease and injury data, we estimate that there are a total of 55,200 US deaths annually resulting from occupational disease or injury (range 32,200–78,200).

Conclusions

Our estimate is in the range reported by previous investigators, although we have restricted ourselves more than others to only those diseases with well‐established occupational etiology, biasing our estimates conservatively. The underlying assumptions and data used to generate the estimates are well documented, so our estimates may be updated as new data emerges on occupational risks and exposed populations, providing an advantage over previous studies. We estimate that occupational deaths are the 8th leading cause of death in the US, after diabetes (64,751) but ahead of suicide (30,575), and greater than the annual number of motor vehicle deaths per year (43,501). Am. J. Ind. Med. 43:461–482, 2003. © 2003 Wiley‐Liss, Inc.
Electrical properties of epoxy resins during polymerization
Authors: Delmonte John
Published: April 2003

Variations in electrical properties of epoxies during polymerization permit interpretation of molecular changes occuring. Three liquid epoxy resins selected for test were of different molecular weights, varying from 6,400 to 26,800 cycles/sec. Curing agents selected included triethylene tetramine, m‐phenylenediamine, and phthalic anhydride. Test specimens were cast between glass plates containing thin foil electrodes which permitted observations of electrical properties during cure. Test results disclose that for each of the resin systems, dissipation factors fell sharply as cure commenced and then at the onset of gelation, values rose again to a peak value, falling with continued cure and hardening of the product. These measurements were conducted over a range of frequencies, the higher the frequency the higher the peak value of dissipation factor and the sooner it occurs. The disclosures of peak values of dissipation factor during cure are unique and appeared to be correlated to the mechanical changes occuring in the polymer. Measurements of other electrical parameters were made during polymerization, such as dielectric constant and volume resistivity, and while data were carefully noted and plotted in the charts, the most revealing was dissipation factor. The influence of heat and other factors upon results is explored.
The development of molecular orientation during formation of cellulose film from viscose
Authors: Haskell V. C. , Owens D. K.
Published: April 2003

The distribution of molecular orientation in cellophane and its correlation with processing conditions have been studied by means of optical retardation measurements. With thin sections of cellophane cut with a standard microtome edge views were obtained, and it was possible to measure optical retardation profiles of the sections. This yielded information about the variation of molecular orientation in different layers of the film. In lanes near the edge of the machine‐cast sheet the machine direction orientation was higher than in center lanes. In layers near the surface, machine direction orientation was higher, and transverse direction orientation was lower than in center layers. Studies of shear induced orientation in viscose indicated that this did not persist long enough to contribute to the structure of cellophane. The distribution of molecular orientation in cellophane was explained in terms of the forces acting on the web during and after coagulation and regeneration. These include the viscous drag of the treatment baths, the internal friction as the viscose is drawn outside the extrusion die, the tendency of the film to shrink during its formation and drying, and the tentering action of machine rolls.
The relative inhibitory effect of various compounds on the rate of polymerization of vinyl acetate
Authors: Georgieff K. K. , Shaw G. S.
Published: April 2003

The relative inhibitory effects of acetaldehyde, acetone, 1‐acetoxy‐1,3‐butadiene, benzene, 1,3‐butadienylacetylene, carbon disulfide, crotonaldehyde, diacetyl, diacetylene, divinylacetylene, divinyl sulfide, 1,3,5‐hexatriene, monovinylacetylene, thiophene, and toluene on the bulk polymerization of vinyl acetate were measured. Two polymerization tests utilizing different concentrations of benzoyl peroxide catalyst were used. Experimental details of the tests, inhibition factors and curves, and general conclusions regarding the magnitude of the inhibition caused by various organic functional groups are given.
Effects of by‐products, trace components, and similar compounds in viscose on ripening
Authors: Easterwood Marie , Mueller W. A.
Published: April 2003

The effects on viscose ripening of a variety of materials are reported. (1) Normal constituents (Na2CO3, Na2CS3, NaCl) appeared not to affect ripening; however, Na2S retarded ripening. By‐product removal appeared to retard ripening. (2) Oxidizing agents (H2O2, Na2Sx) accelerated ripening; reducing agent (Na2SO3) retarded ripening; this is suggestive of possible addition product formation. (3) Na2SO4, (CH3)2SO, KClO3, Na2BH4 showed no effect on ripening. (4) Salts which precipitated as hydroxides or carbonates did not appear to affect ripening. (5) Salts which formed insoluble sulfides resulted in an initial increase in ripening rates. In later stages, ripening proceeded normally, probably after the salts were removed from solution as insoluble sulfides. (6) FeCl3, BiCl3 and Na3AsO3 appeared to retard ripening. (7) A comparison of the effect on ripening of the trivalent state of elements in group V of the periodic table showed that the rate of ripening decreased with the oxidation potential of the element. (8) The addition of sodium zincate retarded ripening and suggested possible cross‐linking of xanthate and by‐product sulfur, or of two xanthate groups. (9) Addition of tin and chromium salts at the 0.5% level resulted in gelation of the viscose within 30 min. after the addition.
Aliphatic polyureas: Melting points versus intrinsic viscosities
Authors: Boenig Herman V. , Walker Norman , Myers Elliot H.
Published: April 2003

An homologous series of aliphatic polyureas of the type where the x = 2, 3, 4, 5, 6, 7, 8, 9, and 12, was prepared from hexamethylene diisocyanate and diamines. The polymers were obtained in powder form with the use of acetone as the solvent. The intrinsic viscosities of the phenolic solutions of these polyureas were found to decrease with increasing polymerization temperature. When the melting points of the polymers were plotted against the intrinsic viscosities within each species of polymer, these melting points were found to increase with the intrinsic viscosity. The curves so formed appeared to approach an asymptote.
The relative thermal stability of polymer model compounds
Authors: Sheehan Desmond , Bentz Alan P. , Petropoulos John C.
Published: April 2003

The thermal stability of a variety of derivatives of s‐triazine, benzene, and borazine was determined with an isoteniscope. For the s‐triazines the order of stability was found to be aryl triazines > aryl melamines and benzoguanamines > methyl melamines > higher alkyl melamines > aryl cyanurates and thiocyanurates (with the exception of fluoroalkyl cyanurates). The borazines were poorer than the melamines but better than the cyanurates. Several diand trifunctional linking groups were used to connect biphenyl groups which were known to be stable (from previous studies of p‐quaterphenyl and polyphenyl ethers). The order of stability was found to be phosphate ≅ phosphine oxide ≅ ether > ester > amide > carbonate.
Thermal degradation of epoxide polymers
Authors: Anderson Hugh C.
Published: April 2003

The thermal degradation of five crosslinked epoxide polymers were studied in vacuo by differential thermogravimetry. Three of the polymers were prepared by reacting methyl nadic anhydride, maleic anhydride, and m‐phenylenediamine with diglycidyl ether of bisphenol‐A; the other two were obtained by reacting methyl nadic anhydride and m‐phenylenediamine with resorcinol diglycidyl ether. Tenmilligram powdered samples were heated over the temperature range from 25° to 925°C. at a rate of 5°C./min. Differential thermogravimetric curves showed that the polymers incorporating methyl nadic anhydride decomposed in two distinct stages, whereas those based on m‐phenylenediamine or maleic anhydride degraded in only one stage. This difference in mechanism of decomposition is attributed to decarboxylation of ester groups having the methyl nadicdicarboxylic structure in the polymers. Substitution of a 2,2‐diphenylpropyl group for a phenyl group in resorcinol diglycidyl ether, to give diglycidyl ether of bisphenol‐A, influenced appreciably the maximum rates of decomposition of the corresponding polymers. In the case of the polymer based on m‐phenylenediamine, the rate was increased by this substitution, but for the polymer derived from methylnadic anhydride the rate was decreased.