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Biomedical subjects

R Roeser

Publications and source records attributed to R Roeser.

11 recordsLinked to original sources
PubMed1998

The Development and Validation of Scales Assessing Students' Achievement Goal Orientations

Achievement goal theory has emerged as a major new direction in motivational research. A distinction is made among conceptually different achievement goal orientations including the goal to develop ability (task goal orientation), the goal to demonstrate ability (ability-approach goal orientation), and the goal to avoid the demonstration of lack of ability (ability-avoid goal orientation). Scales assessing each of these goal orientations were developed over an eight year period by a group of researchers at the University of Michigan. The results of studies conducted with seven different samples of elementary and middle school students are used to describe the internal consistency, stability, and construct validity of the scales. Comparisons of these scales with those developed by Nicholls and his colleagues provide evidence of convergent validity. Confirmatory factor analysis attests to the discriminant validity of the scales. Copyright 1998 Academic Press.

Journal Article↗
PubMed1996

Schools, families, and early adolescents: what are we doing wrong and what can we do instead?

Although most individuals pass through adolescence without excessively high levels of "storm and stress," many individuals experience difficulty during this period. Why? Is there something unique about this developmental period that puts individuals at greater risk for difficulty? This paper focuses on these questions and advances the hypothesis that some of the "negative" psychological and behavioral changes associated with adolescent development result from a mismatch between the needs of developing adolescents and their experiences at school and at home. It provides theoretical and empirical examples of how this mismatch develops, how it is linked to negative age-related changes in early adolescents' motivation, self-perceptions, self-evaluations, and psychological competence, and how we could provide more developmentally appropriate social environments, particularly at school.

Adolescent↗
PubMed1992

Effect of substrate structure on the activity of Man9-mannosidase from pig liver involved in N-linked oligosaccharide processing.

Man9-mannosidase, an alpha 1,2-specific enzyme located in the endoplasmic reticulum and involved in N-linked-oligosaccharide processing, has been isolated from crude pig-liver microsomes and its substrate specificity studied using a variety of free and peptide-bound high-mannose oligosaccharide derivatives. The purified enzyme displays no activity towards synthetic alpha-mannosides, but removes three alpha 1,2-mannose residues from the natural Man9-(GlcNAc)2 substrate (M9). The alpha 1,2-mannosidic linkage remaining in the M6 intermediate is cleaved about 40-fold more slowly. Similar kinetics of hydrolysis were determined with Man9-(GlcNAc)2 N-glycosidically attached to the hexapeptide Tyr-Asn-Lys-Thr-Ser-Val (GP-M9), indicating that the specificity of the enzyme is not influenced by the peptide moiety of the substrate. The alpha 1,2-mannose residue which is largely resistant to hydrolysis, was found to be attached in both the M6 and GP-M6 intermediate to the alpha 1,3-mannose of the peripheral alpha 1,3/alpha 1,6-branch of the glycan chain. Studies with glycopeptides varying in the size and branching pattern of the sugar chains, revealed that the relative rates at which the various alpha 1,2-mannosidic linkages were cleaved, differed depending on their structural complexity. This suggests that distinct sugar residues in the aglycon moiety may be functional in substrate recognition and binding. Reduction or removal of the terminal GlcNAc residue of the chitobiose unit in M9 increased the hydrolytic susceptibility of the fourth (previously resistant) alpha 1,2-mannosidic linkage significantly. We conclude from this observation that, in addition to peripheral mannose residues, the intact chitobiose core represents a structural element affecting Man9-mannosidase specificity. A possible biological role of the enzyme during N-linked-oligosaccharide processing is discussed.

Amino Acid Sequence↗
PubMed1985

Selection, follow-up, and analysis in the Health Insurance Plan Study: a randomized trial with breast cancer screening.

Critical decisions made 20 years ago by those who planned the randomized trial at the Health Insurance Plan (HIP) of Greater New York to determine the efficacy of periodic screening for breast cancer are detailed. These decisions affected the age group to be screened, screening modalities, frequency of screening, sample size, primary measures for testing efficacy, and period of follow-up (long term). Results of follow-up, 16 years after entry, indicate that mortality due to breast cancer continues to be lower among study women than controls. Numerically, the differential has been stable; relatively, it has decreased. It is estimated that the study group would have experienced about a 30% reduction in breast cancer mortality if screening had been maintained. Relative case survival rates over a 14-year period after diagnosis show changes in contours of trend lines that result from screening. The study group's trend is slightly concave in contrast to the usual convex curve for the controls. The contour of the curve is more decidedly concave among subjects detected through mammography alone than for other subgroups detected through screening, although the relative survival rate remains highest in the mammography only group. Uncertainty persists about effects of screening in the HIP study on breast cancer mortality among women aged 40-49 years at entry.

Adult↗
PubMed1982

Prospects for eliminating racial differences in breast cancer survival rates.

Results from the randomized trial underway in the Health Insurance Plan of Greater New York to determine the efficacy of periodic screening with mammography and palpation of the breast have been examined to determine the effect of screening on racial differences in breast cancer survival rates. Consistent with experience in general populations, the control group showed a lower five-year survival rate among non-White women with breast cancer than among White women. In the study group, 65 per cent of whom participated in the screening program, there was no differential in the survival rates of the two racial groups. The elimination of the unfavorable status among non-Whites through screening does not appear to be explained by various artifacts explored. Secondary prevention measures may offer the possibility of reducing or closing the gap in breast cancer survival rates between White and non-White women.

Adult↗
PubMed1982

Ten- to fourteen-year effect of screening on breast cancer mortality.

Results from the randomized trial conducted by the Health Insurance Plan (HIP) to determine the efficacy of breast cancer screening with mammography and palpation are reported for longer periods than previously available. By the end of 10 years after entry, the study group's mortality due to breast cancer was about 30% below the control group's. Arithmetic gains due to screening were maintained through year 14; relative gains declined. With increases in the period of follow-up, cumulative survival rates among cases detected by mammography alone (palpation negative during screening), decreased more rapidly than rates among other subgroups, but survival rates for mammography cases remained relatively high. Study women aged 40-49 years at entry began to show lower breast cancer mortality than those in the control group as duration of follow-up increased. Reservations are advanced about the acceptance of this finding as evidence of the efficacy of screening under age 50 under the conditions of the HIP study. The reservations are based on the observation that the decrease of mortality among the study group aged 45-49 at entry is concentrated entirely among cases diagnosed after they reached 50 years of age.

Adult↗
PubMedDate not supplied

Self-schemas and possible selves as predictors and outcomes of risky behaviors in adolescents.

BACKGROUND: Although there is extensive evidence that the self-concept changes in many important ways during the adolescent years and that these changes influence behavioral choices, the majority of studies completed to date have been based on a static model in which the self-concept is viewed solely as an antecedent of the risky behaviors. OBJECTIVES: To investigate the pattern of relationships between three components of the self-concept--the popular, the conventional, and the deviant selves--and risky behaviors in a sample of middle adolescents during their transition from junior high to high school. METHODS: A sample of 160 adolescents completed questionnaires measuring the content of their self-schemas and possible selves and involvement in four risky behaviors (tobacco and alcohol use, sexual intercourse, poor school performance) during the winter of eighth and ninth grades. RESULTS: Popular self-schema score in the eighth grade positively predicted ninth grade risky behaviors. Risky behavior involvement in the eighth grade predicted ninth-grade deviant self-schema and possible self-scores. CONCLUSIONS: These findings suggest that the self-concept may not only play a role in the early stages of engagement in the risky behaviors but may also be one means through which the behaviors become structuralized into potentially enduring aspects of the self.

Adolescent↗
PubMedDate not supplied

Effects of news events on response to a breast cancer screening program.

An opportunity to examine the effects of significant, widely reported events on participation in a breast cancer screening program was presented when countrywide public attention was called to breast cancer by reports of the breast surgery of the wives of President and Vice President of United States. These events occurred in September and October 1974 while a breast cancer screening program was underway in the health Insurance Plan of Greater New York. The research design of this program permitted measurements to be made of the participation of the plan's members in the screening before, during, and after these famous mastectomies and of the participants' characteristics during different periods of the research program. In late 1974, when there was great mass media emphasis on breast cancer, participation rates in the breast cancer screening program increased significantly. In the study periods immediately following, however, participation rates declined to previous levels. The increase in Participation rates in late 1974 was fairly uniform among all demographic groups, whether classified by age, education, income, race, or religion. In addition to increases in the participation rate associated with the events of late 1974, there was also an increased tendency among women who were screened to respond readily to mailed invitations to appear for screenings. This increase insensitivity to efforts to win their participation was more pronounced among those groups that this study and other studies have shown are more likely to participate in preventive health programs and to respond more readily to request to participate.

Age Factors↗