Solid friction between soft filaments

Any macroscopic deformation of a filamentous bundle is necessarily accompanied by local sliding and/or stretching of the constituent filaments. Yet the nature of the sliding friction between two aligned filaments interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin filaments, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the filaments' overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes' drag, can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in filamentous microtubules and bacterial flagella. Our findings demonstrate how altering a filament's elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the properties of fibrous composite materials

Pseudo-Nilus’s Narrationes: a product of Julian’s edict against Christian teachers?

This paper suggests that the Narrationes, which have been attributed to Nilus of Ancyra or an unknown Sinai monk, was composed as a result of the Emperor Julian’s Edict prohibiting Christians from teaching pagan literature. This article begins by describing the Narrationes and how scholarship has identified its author and composition date. It then presents the evidence of the Sinai monastic communities as described in the Narrationes as indicative of a fourth century date

Global Title X Series \u2710: Global Maritime Partnerships Game

During the period 3–8 October 2010, the United States Naval War College in Newport, Rhode Island hosted the Navy Title 10 Global Maritime Partnerships Game (GMPG, also Global ̳10), on a truly international scale (83 participants from 46 countries). The overarching purpose of the GMPG was to help the Navy better understand the complexity of the problems that it could face throughout the maritime environment by identifying the catalysts to instability at the national, regional and cross-regional levels and the impediments to forming effective regional and global partnerships in the maritime domain from both United States and international perspectives. This game could help the Navy better define the approaches necessary to establish maritime partnerships to address maritime security issues

Introduction to the Special Issue on Surf Therapy Around the Globe

This Special Issue on Surf Therapy Around the Globe in the Global Journal of Community Psychology Practice is devoted to advancing the science and practice of surf therapy for diverse populations around the world. This introductory article provides a framework for this Special Issue. Surf therapy’s beginnings as a small group intervention that served a variety of marginalized populations over the past fifteen years is outlined. Next, a description of how surf therapy programs utilize four community psychology practice competencies – empowerment, mentorship, community inclusion and partnership, and health promotion – in the delivery of surf therapy is detailed. A brief overview of each article in this Special Issue is provided, linked to three practice competency categories – collaboration and coalition development, participatory research, and program evaluation. Finally, videos ancillary to three of the articles are introduced and a fourth video without an accompanying article is also outlined

Surf Therapy Practice, Research, and Coalition Building: Future Directions

Articles in this Special Issue of the Global Journal of Community Psychology Practice on Surf Therapy Around the Globe have focused on theory development, practice considerations, empirical research, and coalition building in order to advance the field of surf therapy. In this concluding article, the Guest Editors highlight the ways in which the collective work in this Special Issue expands on the current literature in terms of theory, as well as processes and outcomes for different programs across a variety of populations across the globe. Suggestions for conducting future studies on surf therapy are provided in order to build an even stronger knowledge base in this area. Finally, initiatives set forth by the International Surf Therapy Organization are presented in order to foster coalition building, participant inclusion, social justice, research and evaluation, and public advocacy. Collectively, this article aims to summarize the work highlighted in this Special Issue and pave a path for surf therapy practice and research going forward

Introduction to the Special Issue on Surf Therapy Around the Globe

This Special Issue on Surf Therapy Around the Globe in the Global Journal of Community Psychology Practice is devoted to advancing the science and practice of surf therapy for diverse populations around the world. This introductory article provides a framework for this Special Issue. Surf therapy’s beginnings as a small group intervention that served a variety of marginalized populations over the past fifteen years is outlined. Next, a description of how surf therapy programs utilize four community psychology practice competencies – empowerment, mentorship, community inclusion and partnership, and health promotion – in the delivery of surf therapy is detailed. A brief overview of each article in this Special Issue is provided, linked to three practice competency categories – collaboration and coalition development, participatory research, and program evaluation. Finally, videos ancillary to three of the articles are introduced and a fourth video without an accompanying article is also outlined