Showing papers by "Northern Illinois University published in 1999"
01 Jun 1999
TL;DR: The basic adaptive algorithm for ANC is developed and analyzed based on single-channel broad-band feedforward control, then modified for narrow-bandFeedforward and adaptive feedback control, which are expanded to multiple-channel cases.
Abstract: Active noise control (ANC) is achieved by introducing a cancelling "antinoise" wave through an appropriate array of secondary sources. These secondary sources are interconnected through an electronic system using a specific signal processing algorithm for the particular cancellation scheme. ANC has application to a wide variety of problems in manufacturing, industrial operations, and consumer products. The emphasis of this paper is on the practical aspects of ANC systems in terms of adaptive signal processing and digital signal processing (DSP) implementation for real-world applications. In this paper, the basic adaptive algorithm for ANC is developed and analyzed based on single-channel broad-band feedforward control. This algorithm is then modified for narrow-band feedforward and adaptive feedback control. In turn, these single-channel ANC algorithms are expanded to multiple-channel cases. Various online secondary-path modeling techniques and special adaptive algorithms, such as lattice, frequency-domain, subband, and recursive-least-squares, are also introduced. Applications of these techniques to actual problems are highlighted by several examples.
1,254 citations
TL;DR: Earlier findings suggesting that CFS is a syndrome primarily affecting white, middle-class patients were not supported, and the highest levels of CFS were consistently found among women, minority groups, and persons with lower levels of education and occupational status.
Abstract: Background: Most previous estimates of the prevalence of chronic fatigue syndrome (CFS) have derived largely from treated populations, and have been biased by differential access to health care treatment linked with sex, ethnic identification, and socioeconomic status. Objective: To assess the point prevalence of CFS in an ethnically diverse random community sample. Design and Participants: A sample of 28 673 adults in Chicago, Ill, was screened by telephone, and those with CFS-like symptoms were medically evaluated. Main Outcome Measures and Analyses: Selfreport questionnaires, psychiatric evaluations, and complete medical examinations with laboratory testing were used to diagnose patients with CFS. Univariate and multivariate statistical techniques were used to delineate the overall rate of CFS in this population, and its relative prevalence was subcategorized by sex, ethnic identification, age, and socioeconomic status. Results: There was a 65.1% completion rate for the telephone interviews during the first phase of the study. Findings indicated that CFS occurs in about 0.42% (95% confidence interval, 0.29%-0.56%) of this random community-based sample. The highest levels of CFS were consistently found among women, minority groups, and persons with lower levels of education and occupational status.
740 citations
TL;DR: In this paper, an extended generalised linear model is introduced for joint modelling of the vectors of predictors for the mean and covariance subsuming the joint modelling strategy for mean and variance heterogeneity, Gabriel's antedependence models, Dempster's covariance selection models and the class of graphical models.
Abstract: SUMMARY We provide unconstrained parameterisation for and model a covariance using covariates. The Cholesky decomposition of the inverse of a covariance matrix is used to associate a unique unit lower triangular and a unique diagonal matrix with each covariance matrix. The entries of the lower triangular and the log of the diagonal matrix are unconstrained and have meaning as regression coefficients and prediction variances when regressing a measurement on its predecessors. An extended generalised linear model is introduced for joint modelling of the vectors of predictors for the mean and covariance subsuming the joint modelling strategy for mean and variance heterogeneity, Gabriel's antedependence models, Dempster's covariance selection models and the class of graphical models. The likelihood function and maximum likelihood estimators of the covariance and the mean parameters are studied when the observations are normally distributed. Applications to modelling nonstationary dependence structures and multivariate data are discussed and illustrated using real data. A graphical method, similar to that based on the correlogram in time series, is developed and used to identify parametric models for nonstationary covariances.
597 citations
TL;DR: The validity of using measures of general cognitive ability, job-specific skills, and personality traits jointly at both the individual level and the group level to predict the performance of 79 four-person, human resource work teams was evaluated.
Abstract: On the basis of job analysis results, the validity of using measures of general cognitive ability, job-specific skills, and personality traits jointly at both the individual level and the group level to predict the performance of 79 four-person, human resource work teams was evaluated. Team member trait and job skill scores were aggregated with a conjunctive model of task performance. At the individual level of analysis, measures of personality (i.e., Agreeableness and Conscientiousness) predicted peer ratings of team member performance beyond measures of job-specific skills and general cognitive ability. Similarly, at the group level of analysis, both Agreeableness and Conscientiousness predicted supervisor ratings of work team performance, objective measures of work team accuracy, and work completed. At both the individual and group levels, the trait of Agreeableness predicted Interpersonal Skills.
489 citations
TL;DR: In this article, the authors report the results of two studies designed to investigate the efficacy of two proposed indices of interrater agreement based on average deviations from the mean of the mean a
Abstract: In this investigation, the authors report the results of two studies designed to investigate the efficacy of two proposed indices of interrater agreement based on average deviations from the mean a...
437 citations
TL;DR: In this article, the authors investigated the relationship between work team effectiveness and two distinct aspects of the personality composition of teams: (a) the average level of a given trait within a team, referred to as team personality elevation (TPE); and (b) the variability or differences in personality traits found within team, or team personality diversity (TPD).
Abstract: In this study, the authors investigated the relationship between work team effectiveness and two distinct aspects of the personality composition of teams: (a) the average level of a given trait within a team, referred to as team personality elevation (TPE); and (b) the variability or differences in personality traits found within a team, or team personality diversity (TPD). Retail assistants (N = 328) working in 82 teams were assessed on a broad range of traits organized around the framework of the Big Five personality factors. Across the set of Big Five traits, TPE and TPD predicted unique variance in ratings of team job performance. For each specific trait of the Big Five, either TPE or TPD predicted team performance. For the traits of conscientiousness, agreeableness, and openness to experience, TPE was positively related to team performance; TPD of extraversion and emotional stability was positively related to team performance.
399 citations
TL;DR: This article found that reading to explain led to better memory, but only when reading silently, and that strategic control comes at some cost in that it limits the resources devoted to other inferences.
Abstract: This study addresses 3 questions: How flexible are readers when reading strategically? How is strategic processing affected by properties of the text? and Do some strategies lead to better text retention than others? Participants read short narratives and thought aloud with an instruction to either explain, predict, associate, or understand. The think-aloud protocols were used to predict sentence reading times for other participants who read silently with the same strategies. The results indicated that readers are capable of strategically controlling the inferences that they generate. However, strategic control comes at some cost in that it limits the resources devoted to other inferences. Furthermore, strategic processing is heavily constrained by a text. Text-based explanations occurred when there was an identifiable causal antecedent in the prior text. Knowledge-based inferences occurred when there were no antecedents and when new characters and objects were introduced. These effects occurred across reading strategies. Reading to explain led to better memory, but only when reading silently.
259 citations
TL;DR: This report presents a description of newly diagnosed childhood‐onset epilepsy, with a special emphasis on epilepsy syndromes, in a large, prospectively ascertained community‐based cohort evaluated and diagnosed in the mid‐1990s.
Abstract: Summary: Purpose: The current understanding of epilepsy has changed significantly in the past 2 decades This report presents a description of newly diagnosed childhood-onset epilepsy, with a special emphasis on epilepsy syndromes, in a large, prospectively ascertained community-based cohort evaluated and diagnosed in the mid-1990s
Methods: Children, aged 0 through 15 years at the time of the first seizure, were prospectively identified at the time of diagnosis of epilepsy through the practices of 16 of the 17 child neurologists in Connecticut as well as five adult neurologists and seven pediatricians from January 1993 through December 1997 Parents were interviewed, and all relevant medical records were reviewed Classification of seizures and of epilepsy syndromes was done for each child by each of three pediatric neurologists, Discrepancies were resolved in conference
Results: A total of 613 children was recruited into the study The median age at time of the first seizure was 53 years Half the cohort was boys Eighteen percent had a remote symptomatic etiology Epilepsy syndromes were classifiable in all but four children, although some syndromes are, by definition, relatively nonspecific In this childhood-onset cohort, 586% of the syndromes were localization related, 290% generalized, and 124% undetermined as to whether focal or generalized Benign rolandic epilepsy occurred in 10% of the cohort Primarily generalized syndromes accounted for 206%, with childhood absence being the single most common syndrome in this subgroup (121% of the cohort) Secondarily generalized syndromes accounted for 85% of the total, with infantile spasms being the most common in this grouping (39% of the cohort)
Conclusions: This study presents a description of childhood-and adolescent-onset epilepsy as it is diagnosed and evaluated in the 1990s in one state in the United State and based on current classification guidelines The results should be generalizable to the rest of the country The prognostic value of early identification of epilepsy syndromes will be determined through subsequent follow-up of this cohort
251 citations
TL;DR: For instance, this paper found that women exposed to sexist ads judged their current body size as larger and revealed a larger discrepancy between their actual and ideal body sizes (preferring a thinner body) than women who were exposed to the non-sexist or no ad condition.
Abstract: This study examined whether exposure to TV ads that portray women as sex objects causes increased body dissatisfaction among women and men. Participants were exposed to 15 sexist and 5 nonsexist ads, 20 nonsexist ads, or a no ad control condition. Results revealed that women exposed to sexist ads judged their current body size as larger and revealed a larger discrepancy between their actual and ideal body sizes (preferring a thinner body) than women exposed to the nonsexist or no ad condition. Men exposed to the sexist ads judged their current body size as thinner, revealed a larger discrepancy between their actual and ideal body size (preferring a larger body), and revealed a larger discrepancy between their own ideal body size and their perceptions of others’ male body size preferences (believing that others preferred a larger ideal) than men exposed to the nonsexist or no ad condition. Discussion focuses on the cognitive, attitudinal, and behavioral consequences of exposure to gender stereotypic televi...
248 citations
TL;DR: In this paper, the extent of stock market integration may depend upon certain macroeconomic variables that characterize and influence the degree of economic integration between two countries, and the authors empirically investigate this hypothesis by employing a two-step procedure to explore first, how the degreeof co-movement for a given pair of markets varies over time and second, why this interdependence varies in time.
245 citations
TL;DR: Experimental results show statistically significant differences in the mean route distance for the routing policies, storage policies, and their interactions and indicates that the choice of certain routing and storage policies in combination can result in increased picking efficiency.
Abstract: Order picking, the assembly of a customer's order from items in storage, is an essential link in the supply chain and is the major cost component of warehousing. The critical issue is to simultaneously reduce the cost and increase the speed of the order picking activity. This study departs from the limited prior research that focused on either routing of workers or storage of warehoused items. The main objectives are to (1) evaluate various routing heuristics versus an optimal routine in a volume-based storage environment, (2) propose several methods of implementing volume-based storage, and (3) examine the interaction of the routing and storage policies under different operating conditions of pick list size and demand skewness. The experimental results show statistically significant differences in the mean route distance for the routing policies, storage policies, and their interactions. Further testing indicates that the choice of certain routing and storage policies in combination can result in increased picking efficiency.
TL;DR: The role of peer relationships in supporting or hindering adolescents' talent development has received little research attention, despite the importance of peers in adolescents' lives as discussed by the authors, and the role of peers typically played a positive function in supporting the continued involvement of talented adolescents in their talent activities, while females mentioned receiving negative peer attention more frequently than males and more often cited social dissatisfaction as a significant contributor to decreased involvement or quitting.
Abstract: The role of peer relationships in supporting or hindering adolescents' talent development has received little research attention, despite the importance of peers in adolescents' lives. We conducted semi-structured in-depth interviews with 41 adolescents talented in sports or the arts, and their parents, to investigate (a) the role of peer relationships in adolescents' continued involvement in their talent activities, (b) possible differences in this role by activity domain, and (c) possible gender differences. Thematic analysis indicated that peers typically played a positive function in supporting the continued involvement of talented adolescents in their talent activities. There were differences in opportunities for peer relationships and social satisfaction between in-school and out-of school activities, but not between activity domains. Both males and females mentioned equally social benefits of such involvement. However, females mentioned receiving negative peer attention more frequently than males, and more often cited social dissatisfaction as a significant contributor to decreased involvement or quitting.
TL;DR: New accelerator mass spectrometry radiocarbon dates taken directly on human remains from the Late Pleistocene sites of Vindija and Velika Pecina in the Hrvatsko Zagorje of Croatia raise the question of when early modern humans first dispersed into Europe and have implications for the nature and geographic patterning of biological and cultural interactions between these populations and the Neandertals.
Abstract: New accelerator mass spectrometry radiocarbon dates taken directly on human remains from the Late Pleistocene sites of Vindija and Velika Pecina in the Hrvatsko Zagorje of Croatia are presented Hominid specimens from both sites have played critical roles in the development of current perspectives on modern human evolutionary emergence in Europe Dates of ≈28 thousand years (ka) before the present (BP) and ≈29 ka BP for two specimens from Vindija G1 establish them as the most recent dated Neandertals in the Eurasian range of these archaic humans The human frontal bone from Velika Pecina, generally considered one of the earliest representatives of modern humans in Europe, dated to ≈5 ka BP, rendering it no longer pertinent to discussions of modern human origins Apart from invalidating the only radiometrically based example of temporal overlap between late Neandertal and early modern human fossil remains from within any region of Europe, these dates raise the question of when early modern humans first dispersed into Europe and have implications for the nature and geographic patterning of biological and cultural interactions between these populations and the Neandertals
TL;DR: Despite ethnic group differences in the prevalence of victimization, the predictors of rape did not differ significantly across ethnic groups.
Abstract: To examine effects of childhood abuse on adult rape, 1,887 female Navy recruits were surveyed. Overall 35% of recruits had been raped and 57% had experienced childhood physical abuse (CPA) and/or childhood sexual abuse (CSA). Controlling for CPA, rape was significantly (4.8 times) more likely among women who had experienced CSA than among women who had not. In contrast, CPA (controlling for CSA) was unrelated to likelihood of adult rape. Alcohol problems and number of sex partners were examined as mediators. Although both variables predicted rape, their effects were independent of the effects of CSA. Finally, despite ethnic group differences in the prevalence of victimization, the predictors of rape did not differ significantly across ethnic groups.
TL;DR: The authors investigated the effects of school mobility on reading and math achievement for 1,087 low-income Black children in the Chicago Longitudinal Study and found that it is frequent, rather than occasional, mobility that significantly increases the risk of underachievement.
TL;DR: In this article, a learning-based approach for developing executive competencies is presented. But given future business needs, particularly in industries experiencing turbulent change, still another approach is needed, one that is learning based.
TL;DR: In this article, the authors define phonological awareness and discuss historic and contemporary research findings regarding its relation to early reading, and discuss common misconceptions about phonology awareness, including the importance of phonology in early reading.
Abstract: This article defines phonological awareness and discusses historic and contemporary research findings regarding its relation to early reading. Common misconceptions about phonological awareness are...
TL;DR: The Parent Behavior Inventory (PBI) as discussed by the authors is a brief measure of parenting behavior for use with the parents of preschool-age and young school-age children, which may be used as a parent self-report measure, a report measure for others familiar with the parent, or as an observational rating scale.
Abstract: The Parent Behavior Inventory (PBI) is a brief measure of parenting behavior for use with the parents of preschool-age and young school-age children. It may be used as a parent self-report measure, a report measure for others familiar with the parent, or as an observational rating scale. Its parallel forms offer clinicians and researchers a single measure capable of multimethod, multi-informant, and multisetting assessment. The PBI's two independent scales, Supportive/Engaged and Hostile/Coercive, have sufficient content validity, show adequate internal consistency and test-retest reliability, and relate to measures of parental affect, parental stress, and child behavior problems. Evidence for its usefulness as a rating scale is presented. The results provide support for the reliability and construct validity of the PBI and demonstrate its versatility as a measure of parenting behavior.
TL;DR: In this article, the effects of different intervention approaches designed to promote peer-related social competence of young children with disabilities were compared and found that the peer mediated condition had the greatest and most sustained effect on children's participation in social interaction and on the quality of interaction, with the child-specific condition also having a strong effect.
Abstract: This study compared the effects of different intervention approaches designed to promote peer-related social competence of young children with disabilities. Preschool-age children with disabilities who were enrolled in classes in Tennessee and Minnesota participated in four intervention conditions (environmental arrangements, child specific, peer mediated, and comprehensive) and a control (no intervention) condition. A performance-based assessment of social competence, which consisted of observational, teacher rating, and peer rating measures, was collected before and after the interventions and again the following school year. Analyses revealed that the peer-mediated condition had the greatest and most sustained effect on children's participation in social interaction and on the quality of interaction, with the child-specific condition also having a strong effect. The environmental arrangements condition had the strongest effect on peer ratings. These findings indicate that there are effective interventi...
TL;DR: This paper investigated whether there were gender differences in associations between males' and females' mastery and extrinsic goal orientations and measures of self-regulated learning (selfefficacy, cognitive, and regulatory strategies) and performance.
TL;DR: The experimental results show the solution gap between routing heuristics and optimal routing is highly dependent on the travel speed and picking rate, the storage policy, and the size of the pick list.
Abstract: Order picking, the activity by which a number of goods are retrieved from a warehousing system to satisfy a number of customer orders, is an essential link in the supply chain and is the major cost component of warehousing. The critical issue is to simultaneously reduce the cost and increase the speed of the order picking activity. The main objectives of this paper are: evaluate various routing heuristics and an optimal routine in a volume‐based and random storage environment; compare the performance of volume‐based storage to random storage; and examine the impact of travel speed and picking rates on routing and storage policy performance. The experimental results show the solution gap between routing heuristics and optimal routing is highly dependent on the travel speed and picking rate, the storage policy, and the size of the pick list. In addition, volume‐based storage produced significant savings over random storage, but again these savings are dependent on the travel speed and picking rate.
TL;DR: Articulated digital reconstructions of two diplodocid sauropods revealed cervical poses and feeding envelopes that suggest that these sauroPods were adapted to ground feeding or low browsing, contrary to the view that diplodytids were high browsers.
Abstract: Articulated digital reconstructions of two diplodocid sauropods revealed cervical poses and feeding envelopes. The necks of Diplodocus and Apatosaurus were nearly straight but gently declined such that the heads, which were themselves angled downward relative to the neck, were close to ground level in their neutral, undeflected posture. Both necks were less flexible than conventionally depicted, and Diplodocus was less capable of lateral and dorsal curvature than Apatosaurus. The results suggest that these sauropods were adapted to ground feeding or low browsing, contrary to the view that diplodocid sauropods were high browsers.
TL;DR: The earliest mammalian lower molars of the Triposphenida have been found in the Middle Jurassic (Bathonian, ∼167 ± 2 Myr) sediments of northwest Madagascar.
Abstract: The lower molars of tribosphenic mammals (marsupials, placentals and their extinct allies) are marked, primitively, by a basined heel (talonid) acting as the mortar to the pestle of a large inner cusp (protocone) on the opposing upper teeth. Here we report the earliest tribosphenic mammal found so far, three lower teeth in a jaw fragment from Middle Jurassic (Bathonian, ∼167 ± 2 Myr)1 sediments of northwest Madagascar. This specimen extends the stratigraphic range of the Tribosphenida by some 25 million years, more than doubling the age of the oldest mammal known from Madagascar2, and representing only the second pre-Plio/Pleistocene terrestrial mammal known from the island. Although it indicates a more ancient diversification of the Triposphenida than previously thought, this find fails to confirm molecular-clock-based models proposing a Middle Jurassic divergence of marsupials and placentals3. In addition, it offers a glimpse of mammal evolution on the southern continents during the Middle through Late Jurassic, countering the prevailing view4 of a northern origin for tribosphenic mammals.
TL;DR: In this article, the authors constructed a phase diagram that describes the magnetic, transport, and structural properties and the relationships among them as a function of composition (0.1l~xl~0.2) and temperature (10-340 K).
Abstract: By combining the results of magnetization, resistivity, and neutron powder-diffraction data for stoichiometric ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3},$ we have constructed a phase diagram that describes the magnetic, transport, and structural properties and the relationships among them as a function of composition $(0.1l~xl~0.2)$ and temperature (10--340 K). We show that, with increasing Sr content, the Curie temperature increases linearly, while the temperature of an orbital ordering transition to a state with a large coherent Jahn-Teller (JT) distortion decreases. These two phase-transition lines cross at $x=0.145$ and $T=210\mathrm{K}.$ When the transition to the ferromagnetic state occurs in a phase that has a large coherent JT distortion $(xl0.145),$ a strong magnetolattice coupling is observed; the coherent JT distortion is dramatically reduced and the incoherent distortion is enhanced in the ferromagnetic phase. For $xg0.145,$ where the coherent JT distortion is small above Curie temperature, magnetolattice coupling reduces the incoherent distortion at ${T}_{C}$ and strongly suppresses the transition to a phase with a large coherent JT distortion. These observations are consistent with a competition between ferromagnetism and JT distortion that is mediated by a colossal spin-charge-lattice coupling. A metallic state occurs below the Curie temperature when both coherent and incoherent JT distortions are suppressed.
TL;DR: In this article, the authors determine whether stock returns in foreign markets are associated with both local and US monetary environments and find that foreign stock returns are generally higher in expansive US and local monetary environments than they are in restrictive environments.
Abstract: Previous research documents that US stock returns are related to the US monetary environment. The focus of this paper is to determine whether stock returns in foreign markets are associated with both local and US monetary environments. Consistent with the US market results, we find that foreign stock returns are generally higher in expansive US and local monetary environments than they are in restrictive environments. Further, these higher returns are generally not accompanied by increases in risk. Interestingly, several of the stock markets are more strongly related to the US monetary environment than to local monetary conditions. For seven of the 15 foreign countries examined, the local and US monetary environment explain 4% or more of the variation in monthly stock returns.
TL;DR: In this paper, new oscillation criteria are established for the equation ( py ∞ + qy ∞+ qy ǫ = 0 that are different from most known ones in the sense that they are based on the information only on a sequence of subintervals of [ t 0, ∞], rather than on the whole half-line.
TL;DR: The authors found that high authoritarians perceived the threat message as stronger in argument quality than the reward message, and low authority-wary voters perceived the reward messages as stronger and more persuasive than the threat messages.
Abstract: The authors examined whether the influence of persuasive messages emphasizing reward versus threat was moderated by authoritarianism. Five days before the 1996 presidential election, participants (N = 86) received either a reward-related message (emphasizing the positive benefits of voting) or a threatrelated message (emphasizing the negative consequences of failing to vote) recommending that they vote in the election. We found that high authoritarians perceived the threat message as stronger in argument quality than the reward message, and low authoritarians perceived the reward message as stronger in argument quality than the threat message. In turn, subjective perceptions of message quality exerted a direct influence on participants’ postmessage attitudes toward voting in the election. Finally, behavioral intentions mediated the influence of voting attitudes on actual voting behavior. Discussion focuses on the implications of the message frame and authoritarianism.
TL;DR: In this article, the role of variance and entropy in ordering distributions and random prospects is examined and the results are conveniently tabulated in terms of distribution parameters, which do not disturb the agreement between these rankings.
TL;DR: In this article, tax and spending limits on local governments are only partially effective in reducing revenues because political agents bypass limitations by transferring revenue reliance to unconstrained revenue sources or taking on additional revenue responsibilities.
Abstract: This paper uses comprehensive data on state and local tax and spending limitations for forty-nine states between 1976 and 1990 to estimate the effects of these limits on the fiscal relationships between state and local government. Results indicate that tax and spending limits on local governments are only partially effective in reducing revenues because political agents bypass limitations by transferring revenue reliance to unconstrained revenue sources, or because unconstrained levels of government take on additional revenue responsibilities. In particular, the empirical analysis demonstrates that binding local government fiscal constraints are associated with reductions in local revenues and increases in state aid to local governments. In contrast, state government limitations are related to reductions in both state and local own source revenues.
TL;DR: In this paper, a new growth mechanism was proposed on the basis of microstructure and different morphologies of the nanowires observed, which is based on the decomposition of semiconductor suboxides and defect structures.
Abstract: Highly pure, ultralong, and uniform-sized semiconductor nanowires in bulk quantity were synthesized by thermal evaporation or laser ablation of semiconductor powders mixed with oxides. Transmission electron microscopy study shows that decomposition of semiconductor suboxides and defect structures play important roles in enhancing the formation and growth of high-quality nanowires. A new growth mechanism is proposed on the basis of microstructure and different morphologies of the nanowires observed.