Showing papers by "Ohio State University published in 1996"

Power analysis and determination of sample size for covariance structure modeling.

Abstract: A framework for hypothesis testing and power analysis in the assessment of fit of covariance structure models is presented. We emphasize the value of confidence intervals for fit indices, and we stress the relationship of confidence intervals to a framework for hypothesis testing. The approach allows for testing null hypotheses of not-good fit, reversing the role of the null hypothesis in conventional tests of model fit, so that a significant result provides strong support for good fit. The approach also allows for direct estimation of power, where effect size is defined in terms of a null and alternative value of the root-mean-square error of approximation fit index proposed by J. H. Steiger and J. M. Lind (1980). It is also feasible to determine minimum sample size required to achieve a given level of power for any test of fit in this framework. Computer programs and examples are provided for power analyses and calculation of minimum sample sizes.

Who is this "We"? Levels of collective identity and self representations.

Abstract: Cross-cultural perspectives have brought renewed interest in the social aspects of the self and the extent to which individuals define themselves in terms of their relationships to others and to social groups. This article provides a conceptual review of research and theory of the social self, arguing that the personal, relational, and collective levels of self-definition represent distinct forms of selfrepresentation with different origins, sources of self-worth, and social motivations. A set of 3 experiments illustrates haw priming of the interpersonal or collective "we" can alter spontaneous judgments of similarity and self-descriptions. Until recently, social psychological theories of the self focused on the individuated self-concept—the person's sense of unique identity differentiated from others. Cross-cultural perspectives, however, have brought a renewed interest in the social aspects of the self and the extent to which individuals define themselves in terms of their relationships to others and to social groups (Markus & Kitayama, 1991; Triandis, Bontempo, Villareal, Asai, & Lucca, 1988). Central to this new perspective is the idea that connectedness and belonging are not merely affiliations or alliances between the self and others but entail fundamental differences in the way the self is construed (Brewer, 1991; Markus & Kitayama, 1991; Singelis, 1994; Trafimow, Triandis, & Goto, 1991; Triandis, 1989; Turner, Oakes, Haslam, & McGarty, 1994). Some of these theories of the social self focus on cross-cultural differences in whether the self is typically construed as individuated or interpersonal. However, all recognize that these different self-construals may also coexist within the same individual, available to be activated at different times or in different contexts. Furthermore, in several theories, achieving an extended sense of self has the status of a fundamental human motivation (Baumeister & Leary, 1995; Brewer, 1991). In other words, individuals seek to define themselves in terms of their immersion in relationships with others and with larger collectives and derive much of their self-evaluation from such social identities (Breckler & Greenwald, 1986; Greenwald & Breckler, 1985). The motivational properties of collective identities are systematically documented in Baumeister and Leary's (1995) comprehensive review of the evidence in support of a fundamental "need to belong" as an innate feature of human nature. All of the theories mentioned above draw some kind of distinction between the individuated or personal self (those aspects of the self-concept that differentiate the self from all others) and a relational or social self (those aspects of the self-concept that

The relationship between social support and physiological processes: a review with emphasis on underlying mechanisms and implications for health.

Abstract: In this review, the authors examine the evidence linking social support to physiological processes and characterize the potential mechanisms responsible for these covariations. A review of 81 studies revealed that social support was reliably related to beneficial effects on aspects of the cardiovascular, endocrine, and immune systems. An analysis of potential mechanisms underlying these associations revealed that (a) potential health-related behaviors do not appear to be responsible for these associations; (b) stress-buffering effects operate in some studies; (c) familial sources of support may be important; and (d) emotional support appears to be at least 1 important dimension of social support. Recommendations and directions for future research include the importance of conceptualizing social support as a multidimensional construct, examination of potential mechanisms across levels of analyses, and attention to the physiological process of interest.

The Length of the Cervix and the Risk of Spontaneous Premature Delivery

Abstract: Background The role of the cervix in the pathogenesis of premature delivery is controversial. In a prospective, multicenter study of pregnant women, we used vaginal ultrasonography to measure the length of the cervix; we also documented the incidence of spontaneous delivery before 35 weeks' gestation. Methods At 10 university-affiliated prenatal clinics, we performed vaginal ultrasonography at approximately 24 and 28 weeks of gestation in women with singleton pregnancies. We then assessed the relation between the length of the cervix and the risk of spontaneous preterm delivery. Results We examined 2915 women at approximately 24 weeks of gestation and 2531 of these women again at approximately 28 weeks. Spontaneous preterm delivery (at less than 35 weeks) occurred in 126 of the women (4.3 percent) examined at 24 weeks. The length of the cervix was normally distributed at 24 and 28 weeks (mean [+/- SD], 35.2 +/- 8.3 mm and 33.7 +/- 8.5 mm, respectively). The relative risk of preterm delivery increased as the length of the cervix decreased. When women with shorter cervixes at 24 weeks were compared with women with values above the 75th percentile, the relative risks of preterm delivery among the women with shorter cervixes were as follows: 1.98 for cervical lengths at or below the 75th percentile (40 mm), 2.35 for lengths at or below the 50th percentile (35 mm), 3.79 for lengths at or below the 25th percentile (30 mm), 6.19 for lengths at or below the 10th percentile (26 mm), 9.49 for lengths at or below the 5th percentile (22 mm), and 13.99 for lengths at or below the 1st percentile (13 mm) (P Conclusions The risk of spontaneous preterm delivery is increased in women who are found to have a short cervix by vaginal ultrasonography during pregnancy.

Intraperitoneal cisplatin plus intravenous cyclophosphamide versus intravenous cisplatin plus intravenous cyclophosphamide for stage III ovarian cancer

Abstract: Background Intravenous platinum-based chemotherapy is the standard primary therapy for advanced ovarian cancer. We conducted a phase 3 trial to compare the effects of intraperitoneal and intravenous cisplatin on the survival of women with previously untreated, stage III, epithelial ovarian cancer. Methods The patients underwent an initial exploratory laparotomy and resection of all tumor masses larger than 2 cm. Within four weeks after surgery, six courses of intravenous cyclophosphamide (600 mg per square meter of body-surface area per course) plus either intraperitoneal cisplatin (100 mg per square meter) or intravenous cisplatin (100 mg per square meter) were administered at three-week intervals. Results Of 654 randomized patients, 546 were eligible for the study. The estimated median survival was significantly longer in the group receiving intraperitoneal cisplatin (49 months; 95 percent confidence interval, 42 to 56) than in the group receiving intravenous cisplatin (41 months; 95 percent confidence ...

Teachers’ Professional Community in Restructuring Schools

Abstract: Professional community among teachers, the subject of a number of recent major studies, is regarded as an ingredient that may contribute to the improvement of schools. The research reported in this article is grounded in the assumption that how teachers interact with each other outside of their classrooms may be critical to the effects of restructuring on students. The analysis focuses on the type of professional community that occurs within a school and investigates both the organizational factors that facilitate its development and its consequences for teachers’ sense of responsibility for student learning. The findings suggest that wide variation in professional community exists between schools, much of which is attributable to both structural features and human resources characteristics, as well as school level. Implications for current school reform efforts are discussed.

Evaluation of a Short Form of the Career Decision-Making Self-Efficacy Scale:

Abstract: This study describes the development and evaluation of a short form of the widely used Career Decision-Making Self-Efficacy Scale (CDMSE; Taylor & Betz, 1983). The psychometric characteristics and ...

Extremely Disadvantaged Neighborhoods and Urban Crime

Abstract: Drawing on Wilson (1987), this article assesses two hypotheses concerning the relationship between neighborhood disadvantage and crime : (1) extremely disadvantaged neighborhoods have unusually high rates of crime; and (2) local structural disadvantage is equally important in influencing crime in black and white neighborhoods. Hence, racial differences in structural disadvantage account for black-white differences in crime across communities. To test these hypotheses, the authors examine 1990 census and crime data for local areas in the city of Columbus, Ohio. The analysis lends substantial support for both arguments, particularly for the influence of structural disadvantage on violent crime

Five Versus More Than Five Years of Tamoxifen Therapy for Breast Cancer Patients With Negative Lymph Nodes and Estrogen Receptor-Positive Tumors

Abstract: BACKGROUND In 1982, the National Surgical Adjuvant Breast and Bowel Project initiated a randomized, double-blinded, placebo-controlled trial (B-14) to determine the effectiveness of adjuvant tamoxifen therapy in patients with primary operable breast cancer who had estrogen receptor-positive tumors and no axillary lymph node involvement. The findings indicated that tamoxifen therapy provided substantial benefit to patients with early stage disease. However, questions arose about how long the observed benefit would persist, about the duration of therapy necessary to maintain maximum benefit, and about the nature and severity of adverse effects from prolonged treatment. PURPOSE We evaluated the outcome of patients in the B-14 trial through 10 years of follow-up. In addition, the effects of 5 years versus more than 5 years of tamoxifen therapy were compared. METHODS In the trial, patients were initially assigned to receive either tamoxifen at 20 mg/day (n = 1404) or placebo (n = 1414). Tamoxifen-treated patients who remained disease free after 5 years of therapy were then reassigned to receive either another 5 years of tamoxifen (n = 322) or 5 years of placebo (n = 321). After the study began, another group of patients who met the same protocol eligibility requirements as the randomly assigned patients were registered to receive tamoxifen (n = 1211). Registered patients who were disease free after 5 years of treatment were also randomly assigned to another 5 years of tamoxifen (n = 261) or to 5 years of placebo (n = 249). To compare 5 years with more than 5 years of tamoxifen therapy, data relating to all patients reassigned to an additional 5 years of the drug were combined. Patients who were not reassigned to either tamoxifen or placebo continued to be followed in the study. Survival, disease-free survival, and distant disease-free survival (relating to failure at distant sites) were estimated by use of the Kaplan-Meier method; differences between the treatment groups were assessed by use of the logrank test. The relative risks of failure (with 95% confidence intervals [CIs]) were determined by use of the Cox proportional hazards model. Reported P values are two-sided. RESULTS Through 10 years of follow-up, a significant advantage in disease-free survival (69% versus 57%, P < .0001; relative risk = 0.66; 95% CI = 0.58-0.74), distant disease-free survival (76% versus 67%, P < .0001; relative risk = 0.70; 95% CI = 0.61-0.81), and survival (80% versus 76%, P = .02; relative risk = 0.84; 95% CI = 0.71-0.99) was found for patients in the group first assigned to receive tamoxifen. The survival benefit extended to those 49 years of age or younger and to those 50 years of age or older. Tamoxifen therapy was associated with a 37% reduction in the incidence of contralateral (opposite) breast cancer (P = .007). Through 4 years after the reassignment of tamoxifen-treated patients to either continued-therapy or placebo groups, advantages in disease-free survival (92% versus 86%, P = .003) and distant disease-free survival (96% versus 90%, P = .01) were found for those who discontinued tamoxifen treatment. Survival was 96% for those who discontinued tamoxifen compared with 94% for those who continued tamoxifen treatment (P = .08). A higher incidence of thromboembolic events was seen in tamoxifen-treated patients (through 5 years, 1.7% versus 0.4%). Except for endometrial cancer, the incidence of second cancers was not increased with tamoxifen therapy. CONCLUSIONS AND IMPLICATIONS The benefit from 5 years of tamoxifen therapy persists through 10 years of follow-up. No additional advantage is obtained from continuing tamoxifen therapy for more than 5 years.

Foci And Bases Of Employee Commitment: Implications For Job Performance

Abstract: Previous research has found that employee commitment and job performance are largely unrelated. However, prior work has not distinguished among individual foci (targets) and bases (motives) of commitment. We found, as expected, that commitment to supervisors was positively related to performance and was more strongly associated with performance than was commitment to organizations. Further, internalization of supervisors' and organizations' values was associated with performance but identification with these foci was not.

Integral sliding mode in systems operating under uncertainty conditions

Abstract: The paper generalized a new sliding mode design concept, namely integral sliding mode (ISM). The order of the motion equation in ISM is equal to the order of the original system, rather than reduced by the number of dimension of the control input. As the result, robustness of the system can be guaranteed throughout an entire response of the system starting from the initial time instance. Uniform formulations of the ISM design principle are developed in the paper. It is shown through examples that our generalized ISM scheme enables a wide scope of application areas. In the case that the given control matrix can not be used directly for generating the sliding mode, the associated decoupling problem was also discussed based on the concept of sliding mode transformation. To alleviate chattering, we remove the discontinuous control action from the real control path and insert it to an internal dynamic process for generating the sliding mode.

Aviation Automation: The Search for A Human-centered Approach

Abstract: This volume offers eloquent and carefully reasoned arguments for a human-centered approach to the development and implementation of new technology in aviation. Part I is an overview of automation in aviation and explains both the application of automation and the concept of human-centered automation. Part II traces the evolution and course of aviation automation. This covers air traffic control and management, as well as aircraft automation. Part III discusses the role of human operators in the aviation system and human-machine integration in the future system. Part IV looks to the future; it expands on novel concepts and discusses requirements for aviation automation and its certification.

A Survey of Machine Scheduling Problems with Blocking and No-Wait in Process

Abstract: An important class of machine scheduling problems is characterized by a no-wait or blocking production environment, where there is no intermediate buffer between machines. In a no-wait environment, a job must be processed from start to completion, without any interruption either on or between machines. Blocking occurs when a job, having completed processing on a machine, remains on the machine until a downstream machine becomes available for processing. A no-wait or blocking production environment typically arises from characteristics of the processing technology itself, or from the absence of storage capacity between operations of a job. In this review paper, we describe several well-documented applications of no-wait and blocking scheduling models and illustrate some ways in which the increasing use of modern manufacturing methods gives rise to other applications. We review the computational complexity of a wide variety of no-wait and blocking scheduling problems and describe several problems which remain open as to complexity. We study several deterministic flowshop, jobshop, and openshop problems and describe efficient and enumerative algorithms, as well as heuristics and results about their performance. The literature on stochastic no-wait and blocking scheduling problems is also reviewed. Finally, we provide some suggestions for future research directions.

Education, age, and the cumulative advantage in health

Abstract: The positive association between educational attainment and health is well established, but the way in which the education-based gap in health varies with age is not. Do the health advantages of high educational attainment and disadvantages of low educational attainment diverge or converge with age? The cumulative advantage perspective predicts a diverging SES gap in health with age, but past evidence does not allow us to accept or reject the hypothesis. We address this issue in two samples, cross-sectionally and over time, with three health measures. The first data set consists of a 1990 telephone interview of a national probability sample of U.S. households. There are 2,031 respondents, aged 18 to 90. The second is a national probability sample of U.S. households in which 2,436 respondents aged 20 to 64 were interviewed by telephone in 1979 and reinterviewed in 1980. We find that the gap in self-reported health, in physical functioning, and in physical well-being among people with high and low educational attainment increases with age. The health advantage of the well educated is larger in older age groups than in younger. Health advantages of high income and disadvantages of low income also diverge with age, but household income does not explain education's positive effect.

The Value of Purchase History Data in Target Marketing

Abstract: An important aspect of marketing practice is the targeting of consumer segments for differential promotional activity. The premise of this activity is that there exist distinct segments of homogeneous consumers who can be identified by readily available demographic information. The increased availability of individual consumer panel data open the possibility of direct targeting of individual households. The goal of this paper is to assess the information content of various information sets available for direct marketing purposes. Information on the consumer is obtained from the current and past purchase history as well as demographic characteristics. We consider the situation in which the marketer may have access to a reasonably long purchase history which includes both the products purchased and information on the causal environment. Short of this complete purchase history, we also consider more limited information sets which consist of only the current purchase occasion or only information on past product choice without causal variables. Proper evaluation of this information requires a flexible model of heterogeneity which can accommodate observable and unobservable heterogeneity as well as produce household level inferences for targeting purposes. We develop new econometric methods to implement a random coefficient choice model in which the heterogeneity distribution is related to observable demographics. We couple this approach to modeling heterogeneity with a target couponing problem in which coupons are customized to specific households on the basis of various information sets. The couponing problem allows us to place a monetary value on the information sets. Our results indicate there exists a tremendous potential for improving the profitability of direct marketing efforts by more fully utilizing household purchase histories. Even rather short purchase histories can produce a net gain in revenue from target couponing which is 2.5 times the gain from blanket couponing. The most popular current electronic couponing trigger strategy uses only one observation to customize the delivery of coupons. Surprisingly, even the information contained in observing one purchase occasion boasts net couponing revenue by 50% more than that which would be gained by the blanket strategy. This result, coupled with increased competitive pressures, will force targeted marketing strategies to become much more prevalent in the future than they are today.

Chronic stress alters the immune response to influenza virus vaccine in older adults

Abstract: To determine whether a chronic stressor (caregiving for a spouse with a progressive dementia) is associated with an impaired immune response to influenza virus vaccination, we compared 32 caregivers' vaccine responses with those of 32 sex-, age-, and socioeconomically matched control subjects. Caregivers showed a poorer antibody response following vaccination relative to control subjects as assessed by two independent methods, ELISA and hemagglutination inhibition. Caregivers also had lower levels of in vitro virus-specific-induced interleukin 2 levels and interleukin 1beta; interleukin 6 did not differ between groups. These data demonstrate that down-regulation of the immune response to influenza virus vaccination is associated with a chronic stressor in the elderly. These results could have implications for vulnerability to infection among older adults.

Treatment of human immunodeficiency virus infection with saquinavir, zidovudine, and zalcitabine. AIDS Clinical Trials Group.

Abstract: Background In patients with human immunodeficiency virus (HIV) infection, combined treatment with several agents may increase the effectiveness of antiviral therapy. We studied the safety and efficacy of saquinavir, an HIV-protease inhibitor, given with one or two nucleoside antiretroviral agents, as compared with the safety and efficacy of a combination of two nucleosides alone. Methods In this double-blind trial, patients with HIV infection were randomly assigned to receive either saquinavir (1800 mg per day) plus both zidovudine (600 mg per day) and zalcitabine (2.25 mg per day) or zidovudine plus either saquinavir or zalcitabine. The 302 patients enrolled had CD4+ counts of 50 to 300 cells per cubic millimeter and had previously received zidovudine for a median of 27 months. The study lasted 24 weeks, with an optional double-blind extension period of an additional 12 to 32 weeks. Results Ninety-six percent of the patients completed the 24-week study. In all three treatment groups, CD4+ cell counts ros...

Novel B219/OB receptor isoforms: Possible role of leptin in hematopoiesis and reproduction

Abstract: Hematopoietic development is a complex process that involves a large number of growth factors and cytokines. Many cytokines are known to act on more mature, lineage–restricted cells of the hematopoietic system1,2. However, no specific factors have yet been identified that induce the expansion of the most primitive hematopoietic cells without also inducing differentiation. To search for such factors, we isolated novel cell lines from the yolk sac in order to identify genes important in early hematopoietic and endothelial development. This approach led to the discovery of B219, a sequence that is expressed in at least four isoforms in very primitive hematopoietic cell populations and which may represent a novel hemopoietin receptor. The recently published receptor3 for the obesity (ob) gene product (leptin)4 is an isoform of B219 with a nearly identical ligand binding domain. B219/obr is expressed in the yolk sac, early fetal liver, enriched hematopoietic stem cells and in a variety of lymphohematopoietic cell lines. B2T9/obr is also expressed at high levels in adult reproductive organs. B219/obr maps to human chromosome 1p32, a region syntenic with the recently reported location of obr on murine chromosome 4 (ref. 5).

Signal design for transmitter diversity wireless communication systems over Rayleigh fading channels

Abstract: Transmitter diversity wireless communication systems over Rayleigh fading channels using pilot symbol assisted modulation (PSAM) are studied. Unlike conventional transmitter diversity systems with PSAM that estimate the superimposed fading process, we are able to estimate each individual fading process corresponding to the multiple transmitters by using appropriately designed pilot symbol sequences. With such sequences, special coded modulation schemes can then be designed to access the diversity provided by the multiple transmitters without having to use an interleaver or expand the signal bandwidth. The code matrix notion is introduced for the coded modulation scheme, and its design criteria are also established. In addition to the reduction in receiver complexity, simulation results are compared to, and shown to be superior to, that of an intentional frequency offset system over a wide range of system parameters.

Issue Frames and Group-Centrism in American Public Opinion

Abstract: Public opinion on government policy is group-centric: that is, strongly influenced by the attitudes citizens possess toward the social groups perceived as the beneficiaries of the policy. Though common-place, this mode of political thinking is not inevitable. In four experiments, we show that group-centrism hinges in part on how issues are framed in public debate. When issues are framed in ways that draw attention to a policy's beneficiaries, group-centrism increases; when issues are framed in ways that deflect attention away from the beneficiaries, group-centrism declines. We conclude by drawing out the implications of these findings for the concept of frame, considered both as a rhetorical weapon in elites' hands and as a cognitive structure in citizens' minds.

Analyzing regression test selection techniques

Abstract: Regression testing is a necessary but expensive maintenance activity aimed at showing that code has not been adversely affected by changes. Regression test selection techniques reuse tests from an existing test suite to test a modified program. Many regression test selection techniques have been proposed, however, it is difficult to compare and evaluate these techniques because they have different goals. This paper outlines the issues relevant to regression test selection techniques, and uses these issues as the basis for a framework within which to evaluate the techniques. The paper illustrates the application of the framework by using it to evaluate existing regression test selection techniques. The evaluation reveals the strengths and weaknesses of existing techniques, and highlights some problems that future work in this area should address.

Developing and Implementing Supply Chain Partnerships

Abstract: Many executives are developing supply chain partnerships in an attempt to reduce costs, improve service and gain competitive advantage. While partnerships can be beneficial, they are not appropriate in all situations. This article provides a model which can be used to determine whether a partnership is warranted, and if so, how close of a partnership is warranted.

Double-Blind, Placebo-Controlled Study of the Effects of Carvedilol in Patients With Moderate to Severe Heart Failure The PRECISE Trial

Abstract: Background Carvedilol has improved the symptomatic status of patients with moderate to severe heart failure in single-center studies, but its clinical effects have not been evaluated in large, multicenter trials. Methods and Results We enrolled 278 patients with moderate to severe heart failure (6-minute walk distance, 150 to 450 m) and a left ventricular ejection fraction ≤0.35 at 31 centers. After an open-label, run-in period, each patient was randomly assigned (double-blind) to either placebo (n=145) or carvedilol (n=133; target dose, 25 to 50 mg BID) for 6 months, while background therapy with digoxin, diuretics, and an ACE inhibitor remained constant. Compared with placebo, patients in the carvedilol group had a greater frequency of symptomatic improvement and lower risk of clinical deterioration, as evaluated by changes in the NYHA functional class (P=.014) or by a global assessment of progress judged either by the patient (P=.002) or by the physician (P<.001). In addition, treatment with carvedilol...

Stable adaptive control using fuzzy systems and neural networks

Abstract: Stable direct and indirect adaptive controllers are presented, which use Takagi-Sugeno fuzzy systems, conventional fuzzy systems, or a class of neural networks to provide asymptotic tracking of a reference signal for a class of continuous-time nonlinear plants with poorly understood dynamics The indirect adaptive scheme allows for the inclusion of a priori knowledge about the plant dynamics in terms of exact mathematical equations or linguistics while the direct adaptive scheme allows for the incorporation of such a priori knowledge in specifying the controller We prove that with or without such knowledge both adaptive schemes can "learn" how to control the plant, provide for bounded internal signals, and achieve asymptotically stable tracking of a reference input In addition, for the direct adaptive scheme a technique is presented in which linguistic knowledge of the inverse dynamics of the plant may be used to accelerate adaptation The performance of the indirect and direct adaptive schemes is demonstrated through the longitudinal control of an automobile within an automated lane

Attitudes on Residential Integration: Perceived Status Differences, Mere In-Group Preference, or Racial Prejudice?

Abstract: Les AA. examinent les attitudes manifestees aux Etats-Unis sur le plan de l'integration residentielle. Ils estiment que les mecanismes de perception interviennent dans les processus d'integration et de segregation. Ils presentent un certain nombre de donnees collectees a Los Angeles en 1992 concernant ce type d'attitude. Ils s'efforcent d'evaluer le role de certains facteurs socio-economiques, celui de l'ethnocentrisme. Ils tentent, de meme, de savoir si une attitude hostile manifestee a l'encontre d'un groupe determine les vues sur l'integration residentielle. Ils estiment que ce dernier facteur est le plus significatif en cette affaire