Goal‐Directed Correlates and Neurobiological Underpinnings of Adolescent Identity: A Multimethod Multisample Longitudinal Approach

This multimethod multisample longitudinal study examined how neurological substrates associated with goal directedness and information seeking are related to adolescents’ identity. Self‐reported data on goal‐directedness were collected across three biannual waves in Study 1. Identity was measured one wave later. Study 1 design and measurements were repeated in Study 2 and extended with structural brain data (nucleus accumbens [NAcc] and prefrontal cortex gray matter volume [PFC]), collected across three biannual waves. Study 1 included 497 adolescents (M_{age T1} = 13.03 years) and Study 2 included 131 adolescents (M_{age T1} = 14.69 years). Using latent growth curve models, goal directedness, NAcc, and PFC volume predicted a stronger identity one wave later. These findings provide crucial new insights in the underlying neurobiological architecture of identity.     

A New Method for Assessing the Statistical Significance in the Differential Functioning of Items and Tests (DFIT) Framework

A new item parameter replication method is proposed for assessing the statistical significance of the noncompensatory differential item functioning (NCDIF) index associated with the differential functioning of items and tests framework. In this new method, a cutoff score for each item is determined by obtaining a (1 −α) percentile rank score from a frequency distribution of NCDIF values under the no-DIF condition by generating a large number of item parameters based on the item parameter estimates and their variance-covariance structures from a computer program such as BIILOG-MG3. This cutoff for each item can be used as the basis for determining whether a given NCDIF index is significantly different from zero. This new method has definite advantages over the current method and yields cutoff values that are tailored to a particular data set and a particular item. A Monte Carlo assessment of this new method is presented and discussed.     

The DT-Polynomial Approach to Discrete Time-Varying Network Flow Problems

This paper introduces a polynomial operator called the DT-polynomial as a novel approach to network flow problems. The class of networks dealt with is time-varying in the sense that the capacity, cost, and travel-time of each edge may vary in discrete time. The Dt-polynomial is a polynomial in two operators, D (delay) and T (time), which is used for describing the time-varying transmission characteristics. The paper starts with the mathematics involving the DT-polynomials. A new shortest arrival route algorithm is presented, and its computational complexity is found to be favorable in comparison with others such as Dijkstra's method and the potential method derived from Ford-Fulkerson's technique. Furthermore, a dynamic flow problem is formulated and analyzed in terms of DT-polynomials, and a latest-departure earliest-arrival schedule is given. Finally, a modified DT-polynomial is applied to digital filter networks.     

汽车传动轴零件的标准化设计

传动轴是汽车传动系中传递动力的重要部件,汽车传动轴产品的标准化对于汽车传动轴制造企业有较强的实用性.本文就传动轴标准化设计的必要性和可行性发表一些看法.     

Video Production Technology in Australian Higher Education

The paper describes the present state of the art of video programme production in Australian tertiary education, discusses the identity of the decision‐makers in the production sequence, and assesses the importance of video aesthetics. Against the background of some Australian media departments' production and hardware philosophy, the author describes four series of programmes produced at the ACUE.     

Effects of a prenatal care intervention on the self-concept and self-efficacy of adolescent mothers

The objective of this study was to examine changes in self-concept and self-efficacy during the childbearing year among adolescent mothers (defined as young mothers up to age 20) who were involved in a behavioral intervention. Subjects included a sample of 282 urban, pregnant adolescents (94% African American, 4% white, 2% other). The Tennessee Self-Concept Scale (TSCS) was used to measure self-concept. A scale to measure the self-efficacy of the adolescent mother during the childbearing year was developed and evaluated. Questionnaires were administered during intake for prenatal care and in the postpartum period. In the larger study, the intervention was a peer-centered, mastery modeling intervention designed to increase self-efficacy, improve self-concept, and improve long- and short-term perinatal outcomes. The results in this portion of the data showed that self-concept increased significantly for young women in the experimental group but did not change significantly for young women in the control group. Changes were noted in the TSCS for overall self-concept as well as for several subscores, including identity, self-satisfaction, behavior, the personal self, the family self, and the social self. However, differences between groups did not reach significance once age, parity, site, and time were accounted for, except on TSCS subscales of identity and personal self. Between intake for prenatal care and postpartum, self-efficacy changed significantly for both the experimental and the control groups. Both groups increased in self-efficacy for labor and delivery and decreased in self-efficacy for infant care. In this group of mostly African American teens, peer support and small group care demonstrated positive effects on self-concept. Professional and peer interactions were equally associated in intervention and nonintervention groups with regard to self-efficacy.