Media Influence on Youth: Scientific Evidence, Policy Considerations, and the History of Media Self-Regulation

This invited commentary reviews the survey research described in "Examining the Relationship between Media use and Aggression, Sexuality, and Body Image" and situates this research within the recent history of entertainment media regulation.

Techniques to accelerate convergence of stress-controlled molecular dynamics simulations of dislocation motion

Dislocation mobility —the relation between applied stress and dislocation velocity—is an important property to model the mechanical behavior of structural materials. These mobilities reflect the interaction between the dislocation core and the host lattice and, thus, atomistic resolution is required to capture its details. Because the mobility function is multiparametric, its computation is often highly demanding in terms of computational requirements. Optimizing how tractions are applied can be greatly advantageous in accelerating convergence and reducing the overall computational cost of the simulations. In this paper we perform molecular dynamics simulations of ½ 〈1 1 1〉 screw dislocation motion in tungsten using step and linear time functions for applying external stress. We find that linear functions over time scales of the order of 10–20 ps reduce fluctuations and speed up convergence to the steady-state velocity value by up to a factor of two.

Convergence of two repressors through heterodimer formation of androgen receptor and testicular orphan receptor-4: A unique signaling pathway in the steroid receptor superfamily

The androgen receptor (AR) binds to androgen response elements and regulates target genes via a mechanism involving coregulators. Here we demonstrate that the AR can interact with the testicular orphan receptor-4 (TR4) and function as a repressor to down-regulate the TR4 target genes by preventing the TR4 binding to its target DNA. Interestingly, the heterodimerization of AR and TR4 also allows TR4 to repress AR target gene expression. Simultaneous exposure to both receptors therefore could result in bidirectional suppression of their target genes. Together, these data demonstrate that the coupling of two different receptors, through the heterodimerization of AR and TR4, is a unique signaling pathway in the steroid receptor superfamily, which may facilitate further understanding of the complicated androgen action in prostate cancer or libido.

Activity-dependent CREB phosphorylation: Convergence of a fast, sensitive calmodulin kinase pathway and a slow, less sensitive mitogen-activated protein kinase pathway

The cAMP-responsive element binding protein (CREB), a key regulator of gene expression, is activated by phosphorylation on Ser-133. Several different protein kinases possess the capability of driving this phosphorylation, making it a point of potential convergence for multiple intracellular signaling cascades. Previous work in neurons has indicated that physiologic synaptic stimulation recruits a fast calmodulin kinase IV (CaMKIV)-dependent pathway that dominates early signaling to CREB. Here we show in hippocampal neurons that the fast, CaMK-dependent pathway can be followed by a slower pathway that depends on Ras/mitogen-activated protein kinase (MAPK), along with CaMK. This pathway was blocked by dominant-negative Ras and was specifically recruited by depolarizations that produced strong intracellular Ca2+ transients. When both pathways were recruited, phosphorylated CREB (pCREB) formation was overwhelmingly dominated by the CaMK pathway between 0 and 10 min, and by the MAPK pathway at 60 min, whereas the two pathways acted in concert at 30 min. The Ca2+ signals that produced only rapid CaMK signaling to pCREB or both rapid CaMK and slow MAPK signaling deviated significantly for only ≈1 min, yet their differential impact on pCREB extended over a much longer period, between 20 and 60 min and beyond, which is of likely significance for gene expression. The CaMK-dependent MAPK pathway may inform the nucleus about stimulus amplitude. In contrast, the CaMKIV pathway may be well suited to conveying information on the precise timing of localized synaptic stimuli, befitting its greater speed and sensitivity, whereas the previously described calcineurin pathway may carry information about stimulus duration.

Proceedings of the Conference on the Challenge of Load Management : a convergence of diverse interests, June 11-12, 1975 /

Cover title: Load management

Stability and convergence of general multistep and multivalue methods with variable step size.

Thesis--University of Illinois.

A study of the non-uniform convergence of the inverse of a doubly-infinite matrix associated with a boundary value problem in a waveguide /

"Contract AF33(616)-6079 Project No. 9-(13-6278), Task No. 40572. Sponsored by: Aeronautical Systems Division"

Stability and convergence of variable order multistep methods,

Includes bibliographical references.

On the convergence of reinforcement procedures in simple perceptors (Project Para)

Mode of access: Internet.