Peer Effects in Sexual Initiation: Separating Social Norms and Partner Supply

Sexual activity among adolescents is associated with risks such as pregnancy and STDs, and there is substantial policy interest in how peers influence the timing of sexual initiation. This paper measures separate effects for two social mechanisms--peer-group norms and partner availability--using a national sample of high school students. I develop and estimate an equilibrium search and matching model for first sexual encounters that specifies distinct roles for the two mechanisms. Norms are defined based on the share of nonvirgins among same-gender peers, which influences whether an individual searches for a sexual partner. Supply is modeled with an arrival rate for partners, which depends on the search behavior among the opposite gender. The model produces a discrete-time duration to first sex which I estimate with quarterly data on individual virginity status constructed from the Add Health study. The endogeneity of peer behavior with respect to individual behavior is addressed with a combination of strategies. First, I use standard instrumental variables methods to estimate linear regressions for virginity status at the end of each grade. Instruments for group nonvirginity rates are person-specific characteristics such as sibling structure and age of menarche, and the regressions include school-by-grade fixed effects. This analysis demonstrates that school-based social interactions have a large effect on sexual initiation. Second, I estimate the search and matching model via simulated maximum likelihood, in order to decompose this composite effect into separate effects of peer norms and partner availability. Here I control for the endogeneity of peer behavior by (a) defining the norm effect as a function of lagged peer outcomes, (b) including a random effect that is correlated within schools, and (c) using exogenous peer characteristics as supply shifters. I find that peer-group norms have a large effect on the timing of sexual initiation: removing the peer influence on search decisions, 42% fewer boys and 22% fewer girls become sexually active in ninth or tenth grade. Changes in the availability of partners at school (i.e., changes in opposite-gender search behavior) also have a large impact on initiation rates for boys, although not for girls

Project Tech Top study of lunar, planetary and solar topography Final report

Data acquisition techniques for information on lunar, planetary, and solar topograph

Alien Registration- Richards, Grace O. (Strong, Franklin County)

https://digitalmaine.com/alien_docs/19297/thumbnail.jp

Strategies to Strengthen Youth Leadership and Youth Participation Opportunities in Central Appalachia

The purpose of this study was to assess opportunities for strengthening youth leadership and participation in the Central Appalachian region. In particular, authors Rebecca O’Doherty, Ada Smith, Ben Spangler, Elandria Williams, and Katie Richards-Schuster sought to understand and document the range of activities and strategies in the region as well as understand the nuances involved in promoting and sustaining youth leadership opportunities. Through interviews with key leaders in the region, they explored critical themes for strengthening youth leadership. To highlight the potential and opportunities for future development, they share a case study of an innovative approach to nurturing and sustaining youth leadership. They conclude with a set of recommendations for consideration by policy makers and stakeholders interested in developing sustainable youth leadership practices in Central Appalachia

The effect of parallel static and microwave electric fields on excited hydrogen atoms

Motivated by recent experiments we analyse the classical dynamics of a hydrogen atom in parallel static and microwave electric fields. Using an appropriate representation and averaging approximations we show that resonant ionisation is controlled by a separatrix, and provide necessary conditions for a dynamical resonance to affect the ionisation probability. The position of the dynamical resonance is computed using a high-order perturbation series, and estimate its radius of convergence. We show that the position of the dynamical resonance does not coincide precisely with the ionisation maxima, and that the field switch-on time can dramatically affect the ionisation signal which, for long switch times, reflects the shape of an incipient homoclinic. Similarly, the resonance ionisation time can reflect the time-scale of the separatrix motion, which is therefore longer than conventional static field Stark ionisation. We explain why these effects should be observed in the quantum dynamics. PACs: 32.80.Rm, 33.40.+f, 34.10.+x, 05.45.Ac, 05.45.MtComment: 47 pages, 20 figure

Endurance Evaluation of Sintered, Porous, Strut-Supported Turbine Blades made by Federal-Mogul-Bower-Bearings, Incorporated, under Bureau of Aeronautics Contract NOas 55-124-C

Four strut-supported, transpiration-cooled turbine blades were investigated experimentally in a turbojet engine. The blade shells were fabricated by the mold-sintering method with spherical stainless-steel powder. Two blades were investigated in order to evolve suitable capping methods for the blade tip. Two other blades were used to evaluate the durability of the porous-shell material. The blades were investigated at a turbine-tip speed of 1305 feet per second, an average turbine-inlet temperature of about 1670 F, and at a porous-shell temperature limited to a maximum of approximately 1040 F

The social experiences and sense of belonging in adolescent females with autism in mainstream school

This is the author accepted manuscript. The final version is available from the British Psychological Society via the link in this recordAim(s) This qualitative study explored the social experiences and sense of belonging of adolescent females with autism in mainstream schooling. Method/Rationale The research explored the views of eight adolescent females with autism. Semi-structured interviews were used to explore the ways in which they experience a sense of belonging and exclusion in school, and what they feel would support them socially. Findings The findings suggest that key friendships, understanding and perceived social competence are important for adolescent females with autism in developing a sense of belonging in mainstream school. Adolescent females with autism are motivated to form a sense of belonging in school, but experience pressure to adapt their behaviour and minimise their differences in order to gain acceptance. Limitations This study represents a small sample of adolescent females with autism. Further replication is needed before the findings can be generalised to other females with autism in mainstream school. Conclusions The current study addressed an identified gap in the literature by seeking the first-hand views and experiences of adolescent females with autism in mainstream school. Consistent with prior research, the findings suggest that adolescent females with autism are motivated to seek social contact and form friendships in the same way as females without a diagnosis of autism. The findings also highlight the specific social difficulties experienced by females with autism and the way in which this can add to their feelings of exclusion in the school environment

A Monte Carlo Study of Efficiency Estimates from Frontier Models

Parametric stochastic frontier models yield firm-level conditional distributions of inefficiency that are truncated normal. Given these distributions, how should one assess and rank firm-level efficiency? This study compares the techniques of estimated (a) the conditional means of inefficiency and (b) probabilities that firms are most or least efficient. Monte Carlo experiments suggest that the efficiency probabilities are more reliable in terms of mean absolute percent error when inefficiency has large variation across firms. Along the way we tackle some interesting problems associated with simulating and assessing estimator performance in the stochastic frontier environment