A network model for field and quenched disorder effects in artificial spin ice

We have performed a systematic study of the effects of field strength and quenched disorder on the driven dynamics of square artificial spin ice. We construct a network representation of the configurational phase space, where nodes represent the microscopic configurations and a directed link between node i and node j means that the field may induce a transition between the corresponding configurations. In this way, we are able to quantitatively describe how the field and the disorder affect the connectedness of states and the reversibility of dynamics. In particular, we have shown that for optimal field strengths, a substantial fraction of all states can be accessed using external driving fields, and this fraction is increased by disorder. We discuss how this relates to control and potential information storage applications for artificial spin ices

Special section dedicated to The Sixth q-bio Conference : meeting report and preface

This special section consists of ten original research reports that elaborate on work presented at The Sixth q-bio Conference, which took place on 8-12 August 2012 on the campus of St John's College in Santa Fe, NM, USA. The q-bio community is a vibrant group of researchers that develop and promote integrated modeling, theoretical and quantitative experimental approaches aimed at understanding cellular information processing and other related complex biological phenomena with the quantitative rigor of the physical sciences. This community is transforming the way research in biology is done, making it more quantitative, and using the power of mathematics to discover and systematize biological knowledge in a way that has long eluded the field. The q-bio Conference is our annual flagship conference, held every August in Santa Fe, NM, USA. It is a major system biology forum for exchanging results and ideas, networking and continued education in q-bio. Since its beginning in 2007, the conference has emphasized studies of cellular regulation, and it was originally called The q-bio Conference on Cellular Information Processing. To more effectively serve the community and impact other fields of biology, we later decided that the conference should broaden to include ecological and evolutionary contexts, and bridge into other areas in systems biology, cell biology, physical chemistry, bioengineering and biophysics. The scope of the conference has gradually expanded, and thus, since 2012, the conference has become known simply as The q-bio Conference. Even with its expanded scope, a majority of contributions to the conference continue to focus on cellular information processing and decision-making. In a field that spans a diverse array of biological systems and emphasizes multidisciplinary approaches, a unifying conference that brings together all of its constitutive groups (researchers from the life, physical and engineering sciences) continues to be as crucial as ever. With The q-bio Conference, we have aimed at creating a dynamic atmosphere where junior researchers can meet and interact with senior investigators in an intimate setting and also present their work in posters and talks. There is ample time for impromptu discussions and opportunities for interactions amongst attendees, which is not always the case at larger meetings. The q-bio Conference features a single-track programme, which unfolds over four days. The meeting continues its tradition of being hosted at the campus of St John's College in Santa Fe, NM, USA. This unique location in the foothills of the Sangre de Cristo Mountains has allowed the conference to capitalize, on the one hand, on the solitude of the campus, where most of the attendees sleep and eat on site, promoting spontaneous informal meetings and discussions, and, on the other hand, on the relative closeness to arts, culture and outdoors of Santa Fe, which provide participants and their families with recreational opportunities. The size of the conference (about 200-50 attendees) is aimed to be large enough to sustain a diverse field, and yet small enough to foster intimate interactions. The Sixth q-bio Conference included (see http://q-bio.org/wiki/2012_schedule for the detailed program): 21 invited talks (including four special talks), 27 contributed talks, 17 short poster spotlight talks and 131 poster presentations. The emphasis on contributed talks and posters places the focus of the conference on junior investigators, and, indeed, more than half of the attendees in 2012 were graduate students and postdoctoral scientists. Contributed and invited talks were anchored by four special presentations and events. For 2012, these included the following