Showing papers by "Pennsylvania State University published in 1998"

Social Capital and Value Creation: The Role of Intrafirm Networks

Abstract: Using data collected from multiple respondents in all the business units of a large multinational electronics company, we examined the relationships both among the structural, relational, and cogni...

Development of eating behaviors among children and adolescents.

Abstract: The prevalence of obesity among children is high and is increasing. We know that obesity runs in families, with children of obese parents at greater risk of developing obesity than children of thin parents. Research on genetic factors in obesity has provided us with estimates of the proportion of the variance in a population accounted for by genetic factors. However, this research does not provide information regarding individual development. To design effective preventive interventions, research is needed to delineate how genetics and environmental factors interact in the etiology of childhood obesity. Addressing this question is especially challenging because parents provide both genes and environment for children. An enormous amount of learning about food and eating occurs during the transition from the exclusive milk diet of infancy to the omnivore's diet consumed by early childhood. This early learning is constrained by children's genetic predispositions, which include the unlearned preference for sweet tastes, salty tastes, and the rejection of sour and bitter tastes. Children also are predisposed to reject new foods and to learn associations between foods' flavors and the postingestive consequences of eating. Evidence suggests that children can respond to the energy density of the diet and that although intake at individual meals is erratic, 24-hour energy intake is relatively well regulated. There are individual differences in the regulation of energy intake as early as the preschool period. These individual differences in self-regulation are associated with differences in child-feeding practices and with children's adiposity. This suggests that child-feeding practices have the potential to affect children's energy balance via altering patterns of intake. Initial evidence indicates that imposition of stringent parental controls can potentiate preferences for high-fat, energy-dense foods, limit children's acceptance of a variety of foods, and disrupt children's regulation of energy intake by altering children's responsiveness to internal cues of hunger and satiety. This can occur when well-intended but concerned parents assume that children need help in determining what, when, and how much to eat and when parents impose child-feeding practices that provide children with few opportunities for self-control. Implications of these findings for preventive interventions are discussed.

A molecular timescale for vertebrate evolution

Abstract: A timescale is necessary for estimating rates of molecular and morphological change in organisms and for interpreting patterns of macroevolution and biogeography. Traditionally, these times have been obtained from the fossil record, where the earliest representatives of two lineages establish a minimum time of divergence of these lineages. The clock-like accumulation of sequence differences in some genes provides an alternative method by which the mean divergence time can be estimated. Estimates from single genes may have large statistical errors, but multiple genes can be studied to obtain a more reliable estimate of divergence time. However, until recently, the number of genes available for estimation of divergence time has been limited. Here we present divergence-time estimates for mammalian orders and major lineages of vertebrates, from an analysis of 658 nuclear genes. The molecular times agree with most early (Palaeozoic) and late (Cenozoic) fossil-based times, but indicate major gaps in the Mesozoic fossil record. At least five lineages of placental mammals arose more than 100 million years ago, and most of the modern orders seem to have diversified before the Cretaceous/Tertiary extinction of the dinosaurs.

The Sloan Digital Sky Survey Photometric Camera

Abstract: We have constructed a large-format mosaic CCD camera for the Sloan Digital Sky Survey. The camera consists of two arrays, a photometric array that uses 30 2048 × 2048 SITe/Tektronix CCDs (24 μm pixels) with an effective imaging area of 720 cm2 and an astrometric array that uses 24 400 × 2048 CCDs with the same pixel size, which will allow us to tie bright astrometric standard stars to the objects imaged in the photometric camera. The instrument will be used to carry out photometry essentially simultaneously in five color bands spanning the range accessible to silicon detectors on the ground in the time-delay–and–integrate (TDI) scanning mode. The photometric detectors are arrayed in the focal plane in six columns of five chips each such that two scans cover a filled stripe 25 wide. This paper presents engineering and technical details of the camera.

Giant Electrostriction and Relaxor Ferroelectric Behavior in Electron-Irradiated Poly(vinylidene fluoride-trifluoroethylene) Copolymer

Abstract: An exceptionally high electrostrictive response ( approximately 4 percent) was observed in electron-irradiated poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer. The material exhibits typical relaxor ferroelectric behavior, suggesting that the electron irradiation breaks up the coherent polarization domain (all-trans chains) in normal ferroelectric P(VDF-TrFE) copolymer into nanopolar regions (nanometer-size, all-trans chains interrupted by trans and gauche bonds) that transform the material into a relaxor ferroelectric. The expanding and contracting of these polar regions under external fields, coupled with a large difference in the lattice strain between the polar and nonpolar phases, generate an ultrahigh strain response.

The interaction of race, gender, and age in criminal sentencing: The punishment cost of being young, black, and male

Abstract: Prior theory and research on sentencing oversimplify the role of race, gender and age in judicial decision making. In this article we present a “focal concerns” theory of judicial decision making to frame hypotheses regarding the effects on sentencing of these social statuses, both singly and in combination. Analyzing statewide sentencing outcomes in Pennsylvania for 1989–1992, we find that, net of controls: (1) young black males are sentenced more harshly than any other group, (2) race is most influential in the sentencing of younger rather than older males, (3) the influence of offender's age on sentencing is greater among males than females, and (4) the main effects of race, gender, and age are more modest compared to the very large differences in sentencing outcomes across certain age-race-gender combinations. These findings demonstrate the importance of considering the joint effects of race, gender, and age on sentencing, and of using interactive rather than additive models.

Manufacturing Firms in Developing Countries: How Well Do They Do, and Why?

Abstract: Competition among manufacturers in developing countries is remarkably vigorous. Nonetheless, markets are imperfect, so the general trend toward trade liberalization has yielded benefits beyond the traditional gains from specialization. Manufacturing firms in developing countries have traditionally been relatively protected. They have also been subject to heavy regulation, much of it biased in favor of large enterprises. Accordingly, it is often argued that manufacturers in these countries perform poorly in several respects: - Markets tolerate inefficient firms, so cross-firm productivity dispersion is high. - Small groups of entrenched oligopolists exploit monopoly power in product markets. - Many small firms are unable or unwilling to grow, so important economies of scale go unexploited. Tybout assesses each of these conjectures, drawing on plant - and firm - level studies of manufacturers in developing countries. He finds systematic support for none of them. Turnover is substantial, exploited scale economies are modest, and convincing demonstrations of monopoly rents are generally lacking. Overprotection and overregulation are probably less a problem in developing countries than are uncertainty about policies and demand, poor rule of law, and corruption. Tybout does find some evidence that protection increases firms' price-cost margins and reduces average efficiency levels at the margin. And although the econometric evidence on technology diffusion in developing countries is limited, it does suggest that protecting learning industries is unlikely to foster productivity growth. All of which suggests that the general trend toward trade liberalization has yielded greater benefits than the traditional gains from trade. This paper - a product of Trade, Development Research Group - is part of a larger effort in the group to link firm-level performance with commerical policy.

The High-Z Supernova Search: Measuring Cosmic Deceleration and Global Curvature of the Universe Using Type Ia Supernovae*

Abstract: The High-Z Supernova Search is an international collaboration to discover and monitor Type Ia supernovae (SNe Ia) at z > 0.2 with the aim of measuring cosmic deceleration and global curvature. Our collaboration has pursued a basic understanding of supernovae in the nearby universe, discovering and observing a large sample of objects and developing methods to measure accurate distances with SNe Ia. This paper describes the extension of this program to z ≥ 0.2, outlining our search techniques and follow-up program. We have devised high-throughput filters that provide accurate two-color rest frame B and V light curves of SNe Ia, enabling us to produce precise, extinction-corrected luminosity distances in the range 0.25 M=-0.2 -->−0.8+1.0 if ΩΛ = 0. For a spatially flat universe composed of normal matter and a cosmological constant, we find Ω -->M=0.4 -->−0.4+0.5, Ω${Λ}$ -->=0.6 -->−0.5+0.4. We demonstrate that with a sample of ~30 objects, we should be able to determine relative luminosity distances over the range 0 < z < 0.5 with sufficient precision to measure ΩM with an uncertainty of ±0.2.

Testosterone and dominance in men.

Abstract: In men, high levels of endogenous testosterone (T) seem to encourage behavior intended to dominate - to enhance one's status over - other people. Sometimes dominant behavior is aggressive, its apparent intent being to inflict harm on another person, but often dominance is expressed nonaggressively. Sometimes dominant behavior takes the form of antisocial behavior, including rebellion against authority and law breaking. Measurement of T at a single point in time, presumably indicative of a man's basal T level, predicts many of these dominant or antisocial behaviors. T not only affects behavior but also responds to it. The act of competing for dominant status affects male T levels in two ways. First, T rises in the face of a challenge, as if it were an anticipatory response to impending competition. Second, after the competition, T rises in winners and declines in losers. Thus, there is a reciprocity between T and dominance behavior, each affecting the other. We contrast a reciprocal model, in which T level is variable, acting as both a cause and effect of behavior, with a basal model, in which T level is assumed to be a persistent trait that influences behavior. An unusual data set on Air Force veterans, in which data were collected four times over a decade, enables us to compare the basal and reciprocal models as explanations for the relationship between T and divorce. We discuss sociological implications of these models.

Effects of age on sleep apnea in men: I. Prevalence and severity.

Abstract: The effects of age on the prevalence of sleep apnea in the general population remain unclear, because previous studies have focused on specific populations. The effects of age on the severity of apnea are unknown. This study was based on a two-stage general random sample of men (aged 20 to 100 yr), consisting of a telephone survey (n = 4,364) and a sleep laboratory evaluation of a survey subsample (n = 741). Obstructive sleep apnea (OSA), based on both sleep laboratory and clinical criteria (apnea/hypopnea index [AHI] > or = 10 and the presence of daytime symptoms) was found in 3.3% of the sample, with its maximum prevalence in the middle age group (45 to 64 yr). Also, based solely on laboratory criteria, the prevalence of OSA (obstructive AHI > or = 20) showed an age distribution similar to that of OSA diagnosed by laboratory and clinical criteria. The prevalence of any type of sleep apnea (central and obstructive) increased monotonically with age. However, central apnea appeared to account for this monotonic relationship with age. Severity of sleep apnea, as indicated by both number of events and minimum oxygen saturation, decreased with age when any sleep apnea criteria were used and when controlling for body mass index (BMI). The study shows that the prevalence of sleep apnea tends to increase with age but that the clinical significance (severity) of apnea decreases. On the basis of these findings, the sleep laboratory criteria used for diagnosis of sleep apnea should be adjusted for age.

Neural apoptosis in the retina during experimental and human diabetes. Early onset and effect of insulin.

Abstract: This study determined whether retinal degeneration during diabetes includes retinal neural cell apoptosis. Image analysis of retinal sections from streptozotocin (STZ) diabetic rats after 7.5 months of STZ diabetes identified 22% and 14% reductions in the thickness of the inner plexiform and inner nuclear layers, respectively (P < 0. 001). The number of surviving ganglion cells was also reduced by 10% compared to controls (P < 0.001). In situ end labeling of DNA terminal dUTP nick end labeling (TUNEL) identified a 10-fold increase in the frequency of retinal apoptosis in whole-mounted rat retinas after 1, 3, 6, and 12 months of diabetes (P < 0.001, P < 0. 001, P < 0.01, and P < 0.01, respectively). Most TUNEL-positive cells were not associated with blood vessels and did not colocalize with the endothelial cell-specific antigen, von Willebrand factor. Insulin implants significantly reduced the number of TUNEL-positive cells (P < 0.05). The number of TUNEL-positive cells was also increased in retinas from humans with diabetes. These data indicate that retinal neural cell death occurs early in diabetes. This is the first quantitative report of an increase in neural cell apoptosis in the retina during diabetes, and indicates that neurodegeneration is an important component of diabetic retinopathy.

Sodium Reduction and Weight Loss in the Treatment of Hypertension in Older Persons: A Randomized Controlled Trial of Nonpharmacologic Interventions in the Elderly (TONE)

Abstract: Context.—Nonpharmacologic interventions are frequently recommended for treatment of hypertension in the elderly, but there is a paucity of evidence from randomized controlled trials in support of this recommendation.Objective.—To determine whether weight loss or reduced sodium intake is effective in the treatment of older persons with hypertension.Design.—Randomized controlled trial.Participants.—A total of 875 men and women aged 60 to 80 years with systolic blood pressure lower than 145 mm Hg and diastolic blood pressure lower than 85 mm Hg while receiving treatment with a single antihypertensive medication.Setting.—Four academic health centers.Intervention.—The 585 obese participants were randomized to reduced sodium intake, weight loss, both, or usual care, and the 390 nonobese participants were randomized to reduced sodium intake or usual care. Withdrawal of antihypertensive medication was attempted after 3 months of intervention.Main Outcome Measure.—Diagnosis of high blood pressure at 1 or more follow-up visits, or treatment with antihypertensive medication, or a cardiovascular event during follow-up (range, 15-36 months; median, 29 months).Results.—The combined outcome measure was less frequent among those assigned vs not assigned to reduced sodium intake (relative hazard ratio, 0.69; 95% confidence interval [CI], 0.59-0.81; P<.001) and, in obese participants, among those assigned vs not assigned to weight loss (relative hazard ratio, 0.70; 95% CI, 0.57-0.87; P<.001). Relative to usual care, hazard ratios among the obese participants were 0.60 (95% CI, 0.45-0.80; P<.001) for reduced sodium intake alone, 0.64 (95% CI, 0.49-0.85; P=.002) for weight loss alone, and 0.47 (95% CI, 0.35-0.64; P<.001) for reduced sodium intake and weight loss combined. The frequency of cardiovascular events during follow-up was similar in each of the 6 treatment groups.Conclusion.—Reduced sodium intake and weight loss constitute a feasible, effective, and safe nonpharmacologic therapy of hypertension in older persons.

The Asymmetric Impact of Negative and Positive Attribute-Level Performance on Overall Satisfaction and Repurchase Intentions

Abstract: The relationship between attribute-level performance, overall satisfaction, and repurchase intentions is of critical importance to managers and generally has been conceptualized as linear and symmetric. The authors investigate the asymmetric and nonlinear nature of the relationship among these constructs. Predictions are developed and tested empirically using survey data from two different contexts: a service (health care, n=4517) and a product (automobile, n=9359 and n=13,759). Results show that (1) negative performance on an attribute has a greater impact on overall satisfaction and repurchase intentions than positive performance has on that same attribute, and (2) overall satisfaction displays diminishing sensitivity to attribute-level performance. Surprisingly, results show that attribute performance has a direct impact on repurchase intentions in addition to its effect through satisfaction.

Quantum geometry and black hole entropy

Abstract: A ``black hole sector'' of nonperturbative canonical quantum gravity is introduced. The quantum black hole degrees of freedom are shown to be described by a Chern-Simons field theory on the horizon. It is shown that the entropy of a large nonrotating black hole is proportional to its horizon area. The constant of proportionality depends upon the Immirzi parameter, which fixes the spectrum of the area operator in loop quantum gravity; an appropriate choice of this parameter gives the Bekenstein-Hawking formula $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}A/4{\ensuremath{\ell}}_{P}^{2}$. With the same choice of the Immirzi parameter, this result also holds for black holes carrying electric or dilatonic charge, which are not necessarily near extremal.

Reconceptualizing the Knowledge-Base of Language Teacher Education

Abstract: Moving beyond the historical and theoretical traditions that have defined teacher education in TESOL over the last quarter century, in this introductory piece we argue for a reconceptualization of the knowledge-base of ESOL teacher education. Essential to this reconceptualization is the premise that the institutional forms and processes of teacher education frame how the profession responds to the basic sociocultural processes of learning to teach. As such, our teacher education practices constitute our professional self-definition. We argue that the core of the new knowledge-base must focus on the activity of teaching itself; it should center on the teacher who does it, the contexts in which it is done, and the pedagogy by which it is done. Moreover, this knowledge-base should include forms of knowledge representation that document teacher learning within the social, cultural, and institutional contexts in which it occurs. Finally, we believe the knowledge-base of language teacher education needs to account for the teacher as a learner of teaching, the social context of schools and schooling within which teacher-learning and teaching occur, and the activities of both language teaching and language learning. This tripartite framework calls for a broader epistemological view of ESOL teacher education, one that accounts for teaching as it is learned and as it is practiced; we argue that it will ultimately redefine how we as teacher educators create professionals in TESOL.

Toward a Unifying Framework for Exploring Fit and Flexibility in Strategic Human Resource Management

Abstract: In this article we present a framework for studying the concepts of fit and flexibility in the field of strategic human resource management (HRM), focusing on HRM practices, employee skills, and employee behaviors, and review past conceptual and empirical work within that framework. We present a model of strategic HRM and use this model to explore the concepts of fit and flexibility as they apply to strategic HRM. After applying the concepts of resource and coordination flexibility to strategic HRM, we discuss the implications of the framework for both the practice of and research on strategic HRM.

Multi-angle Imaging SpectroRadiometer (MISR) instrument description and experiment overview

Abstract: The Multi-angle Imaging SpectroRadiometer (MISR) instrument is scheduled for launch aboard the first of the Earth Observing System (EOS) spacecraft, EOS-AM1. MISR will provide global, radiometrically calibrated, georectified, and spatially coregistered imagery at nine discrete viewing angles and four visible/near-infrared spectral bands. Algorithms specifically developed to capitalize on this measurement strategy will be used to retrieve geophysical products for studies of clouds, aerosols, and surface radiation. This paper provides an overview of the as-built instrument characteristics and the application of MISR to remote sensing of the Earth.

Relationships and Unethical Behavior: A Social Network Perspective

Abstract: Recent models of unethical behavior have begun to examine the combination of characteristics of individuals, issues, and organizations. We extend this examination by addressing a largely ignored perspective that focuses on the relationships among actors. Drawing on social network analysis, we generate propositions concerning types of relationships (strength, multiplexity, asymmetry, and status) and the structure of relationships (structural holes, centrality, and density). We also consider the combination of the type and structure of relationships and how this embeddedness perspective relates to social contagion and conspiracies.

Combinatorial Electrochemistry: A Highly Parallel, Optical Screening Method for Discovery of Better Electrocatalysts

Abstract: Combinatorial screening of electrochemical catalysts by current-voltage methods can be unwieldy for large sample sizes. By converting the ions generated in an electrochemical half-cell reaction to a fluorescence signal, the most active compositions in a large electrode array have been identified. A fluorescent acid-base indicator was used to image high concentrations of hydrogen ions, which were generated in the electrooxidation of methanol. A 645-member electrode array containing five elements (platinum, ruthenium, osmium, iridium, and rhodium), 80 binary, 280 ternary, and 280 quaternary combinations was screened to identify the most active regions of phase space. Subsequent “zoom” screens pinpointed several very active compositions, some in ternary and quaternary regions that were bounded by rather inactive binaries. The best catalyst, platinum(44)/ruthenium(41)/osmium(10)/iridium(5) (numbers in parentheses are atomic percent), was significantly more active than platinum(50)/ruthenium(50) in a direct methanol fuel cell operating at 60°C, even though the latter catalyst had about twice the surface area of the former.

Radiation effects in crystalline ceramics for the immobilization of high-level nuclear waste and plutonium

Abstract: This review provides a comprehensive evaluation of the state-of-knowledge of radiation effects in crystalline ceramics that may be used for the immobilization of high-level nuclear waste and plutonium. The current understanding of radiation damage processes, defect generation, microstructure development, theoretical methods, and experimental methods are reviewed. Fundamental scientific and technological issues that offer opportunities for research are identified. The most important issue is the need for an understanding of the radiation-induced structural changes at the atomic, microscopic, and macroscopic levels, and the effect of these changes on the release rates of radionuclides during corrosion.

Changes in agonist-antagonist EMG, muscle CSA, and force during strength training in middle-aged and older people

Abstract: Effects of 6 mo of heavy-resistance training combined with explosive exercises on neural activation of the agonist and antagonist leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris, as well as maximal and explosive strength were examined in 10 middle-aged men (M40; 42 ± 2 yr), 11 middle-aged women (W40; 39 ± 3 yr), 11 elderly men (M70; 72 ± 3 yr) and 10 elderly women (W70; 67 ± 3 yr). Maximal and explosive strength remained unaltered during a 1-mo control period with no strength training. After the 6 mo of training, maximal isometric and dynamic leg-extension strength increased by 36 ± 4 and 22 ± 2% (P < 0.001) in M40, by 36 ± 3 and 21 ± 3% (P < 0.001) in M70, by 66 ± 9 and 34 ± 4% (P < 0.001) in W40, and by 57 ± 10 and 30 ± 3% (P < 0.001) in W70, respectively. All groups showed large increases (P< 0.05–0.001) in the maximum integrated EMGs (iEMGs) of the agonist vastus lateralis and medialis. Significant (P < 0.05–0.001) increases occurred in the maximal rate of isometric force pr...

Temperature-independent transport in high-mobility pentacene transistors

Abstract: The charge-carrier transport mechanism in the organic semiconductor pentacene is explored using thin-film transistor structures. The variation of the field-effect mobility with temperature differs from sample to sample, ranging from thermally activated to temperature-independent behavior. This result excludes thermally activated hopping as the fundamental transport mechanism in pentacene thin films, and suggests that traps and/or contact effects may strongly influence the observed characteristics. These results also indicate that field-effect transistors may not be appropriate vehicles for illuminating basic transport mechanisms in organic materials.

A computer program for aligning a cDNA sequence with a genomic DNA sequence.

Abstract: We address the problem of efficiently aligning a transcribed and spliced DNA sequence with a genomic sequence containing that gene, allowing for introns in the genomic sequence and a relatively small number of sequencing errors. A freely available computer program, described herein, solves the problem for a 100-kb genomic sequence in a few seconds on a workstation.

How white attitudes vary with the racial composition of local populations : Numbers count

Abstract: This research focuses on the white people's reactions to the racial composition of the local population. Multilevel modeling is applied to a micro/macro data file that links 1990 General Social Survey responses to census information about respondents' localities. On summary scales representing traditional prejudice, opposition to race-targeting, and policy-related beliefs, white negativity swells as the local black population share expands. Among non-Southern white, a 10-point rise in the local percentage of black brings an increase in traditional prejudice greater than the decrease in prejudice that comes with three additional years of education. South/non-South differences in the white people's views about black are generally reduced to about one-half of their original size and fall short of statistical significance when local racial composition is controlled. Interestingly, concentrations of local Asian American and Latino populations do not engender white antipathy toward these groups. If the white people's reactions to the presence of black is a threat response, the specific dynamics of this threat await description

Worry: A cognitive phenomenon intimately linked to affective, physiological, and interpersonal behavioral processes.

Abstract: Research on worry during the past 15 years has revealed a remarkable amount of knowledge about this pervasive human phenomenon. Worry involves a predominance of verbal thought activity, functions as a type of cognitive avoidance, and inhibits emotional processing. Worry also produces not only anxious experience but depressive affect as well. Recent evidence suggests that the very private experience of worry is developmentally connected to enmeshed childhood relationships with the primary caregiver and is currently associated with significant interpersonal problems, especially those involving tendency to be overly nurturing to others. At the physiological level, worry is characterized peripherally by parasympathetic deficiency and autonomic rigidity and centrally by left-frontal activation.

Positive Darwinian selection after gene duplication in primate ribonuclease genes

Abstract: Evolutionary mechanisms of origins of new gene function have been a subject of long-standing debate. Here we report a convincing case in which positive Darwinian selection operated at the molecular level during the evolution of novel function by gene duplication. The genes for eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) in primates belong to the ribonuclease gene family, and the ECP gene, whose product has an anti-pathogen function not displayed by EDN, was generated by duplication of the EDN gene about 31 million years ago. Using inferred nucleotide sequences of ancestral organisms, we showed that the rate of nonsynonymous nucleotide substitution was significantly higher than that of synonymous substitution for the ECP gene. This strongly suggests that positive Darwinian selection operated in the early stage of evolution of the ECP gene. It was also found that the number of arginine residues increased substantially in a short period of evolutionary time after gene duplication, and these amino acid changes probably produced the novel anti-pathogen function of ECP.

A fasting glucose to insulin ratio is a useful measure of insulin sensitivity in women with polycystic ovary syndrome.

Abstract: Women with polycystic ovary syndrome (PCOS) are profoundly insulin resistant, and the resultant hyperinsulinemia exacerbates the reproductive abnormalities of the syndrome. Agents that ameliorate insulin resistance and reduce circulating insulin levels could provide a new therapeutic modality for PCOS. Identifying the subset of PCOS women who are most insulin resistant may therefore be useful for selecting women who will respond to this therapy. We examined the correlation of basal and oral glucose-stimulated glucose and insulin levels and fasting and stimulated glucose/insulin (G:I) ratios with parameters of insulin sensitivity obtained by frequently sampled i.v. glucose tolerance test (FSIGT) to assess whether there is a simple screening test for insulin resistance in PCOS. Forty PCOS women (aged 18-40 yr; body mass index, >26 kg/m2) and 15 control women matched for age, weight, and ethnicity underwent both a 75-g oral glucose tolerance test (OGTT) and a FSIGT. The insulin sensitivity index (S(I)) was calculated by application of the minimal model of glucose kinetics to the dynamics of plasma glucose and insulin levels during the FSIGT. The best correlation in PCOS between S(I) and a fasting level was found with fasting G:I ratios (r = 0.73; P < 0.0001). A less substantial, but significant, correlation was found with fasting insulin levels (r = 0.50; P < 0.001), and no significant correlation was found with fasting glucose levels (r = 0.24; P = NS). The fasting G:I was more strongly correlated with S(I) than with integrated glucose and insulin responses during the OGTT. The only stronger correlation was with the OGTT 2 h G:I ratio (r = 0.74; P < 0.001). Stepwise regression analysis with S(I) as the dependent variable and fasting glucose and insulin levels, area under the curve for glucose and insulin, and a fasting G:I ratio showed that only the fasting G:I ratio was significantly predictive of S(I) in the model (F to remove value = 38.1; P < 0.001). When viewed as a screening test for insulin resistance in PCOS, setting a value of the fasting G:I ratio of less than 4.5 as abnormal (using an S(I) value below the 10th percentile of our control population as evidence for insulin resistance), the sensitivity of a fasting G:I ratio was 95%, the specificity was 84%, the positive predictive value was 87%, and the negative predictive value was 94%. Receiver operator curve analysis showed that this fasting G:I ratio was the single best screening measure for detecting insulin resistance. We conclude that a fasting G:I ratio may be useful as a screening test for insulin resistance in obese non-Hispanic white PCOS women. This may be a clinically useful parameter for selecting PCOS women most likely to respond to therapeutic interventions that improve insulin sensitivity.