364 research outputs found
Theory, models and biology
Theoretical ideas have a rich history in many areas of biology, and new theories and mathematical models have much to offer in the future
An Effective Membrane Model of the Immunological Synapse
The immunological synapse is a patterned collection of different types of
receptors and ligands that forms in the intercellular junction between T Cells
and antigen presenting cells (APCs) during recognition. The synapse is
implicated in information transfer between cells, and is characterized by
different spatial patterns of receptors at different stages in the life cycle
of T cells. We obtain a minimalist model that captures this experimentally
observed phenomenology. A functional RG analysis provides further insights.Comment: 6 pages, 3 figures, submitted for publicatio
Evidence of a compensated semimetal with electronic correlations at the CNP of twisted double bilayer graphene
Recently, magic-angle twisted bilayer graphene (MATBLG) has shown the
emergence of various interaction-driven novel quantum phases at the
commensurate fillings of the moir'e superlattice, while the charge neutrality
point (CNP) remains mostly a vanilla insulator. Here, we show an emerging phase
of nearly compensated semimetallicity at the CNP of twisted double bilayer
graphene (TDBLG), a close cousin of MATBLG, with signatures of electronic
correlation. Using electrical and thermal transport, we find almost two orders
of magnitude enhancement of the thermopower in magnetic fields much smaller
than the extreme quantum limit, accompanied by a large magnetoresistance() at CNP. This provides indisputable experimental evidence that TDBLG
near CNP is a compensated semimetal. Moreover, at low temperatures, we observe
an unusual sublinear temperature dependence of resistance. A recent theory
predicts the formation of an excitonic metal near CNP, where small electron and
hole pockets coexist. We understand the sublinear temperature dependence in
terms of critical fluctuations in this theory
Networking Cities after Paris: Weighing the Ambition of Urban Climate Change Experimentation
Over the past few decades, cities have repeatedly demonstrated high levels of ambition with regard to climate action. Global environmental governance has been marked by a proliferation of policy actions taken by local governments around the world to demonstrate their potential to advance climate change mitigation and adaptation. Leading ‘by example’ and demonstrating the extent of action that it is possible to deliver, cities have aspired to raise the ambition of national and international climate governance and put action into practice via a growing number of ‘climate change experiments’ delivered on the ground. Yet accounts of the potential of cities in global environmental governance have often stopped short of a systematic valuation of the nature and impact of the networked dimension of this action. This article addresses this by assessing the nature, and challenges faced by, urban climate governance in the post-Paris era, focusing on the ‘experimentation’ undertaken in cities and the city networks shaping this type of governance. First, we unpack the concept of ‘urban climate change experimentation’, the ways in which it is networked, and the forces driving it. In the second and third parts of the article, we discuss two main pitfalls of networked urban experimentation in its current form, focusing on issues of scaling experiments and the nature of experimentation. We call for increased attention to ‘scaling up’ experiments beyond urban levels of governance, and to transformative experimentation with governance and politics by and in cities. Finally, we consider how these pitfalls allow us to weigh the potential of urban climate ambition, and consider the pathways available for supporting urban climate change experimentation
Collective modes of a quasi two-dimensional Bose condensate in large gas parameter regime
We have theoretically studied the collective modes of a quasi two-dimensional
(Q2D) Bose condensate in the large gas parameter regime by using a formalism
which treats the interaction energy beyond the mean-field approximation. In the
calculation we use the perturbative expansion for the interaction energy by
incorporating the Lee, Huang and Yang (LHY) correction term. The results show
that incorporation of this higher order term leads to detectable modifications
in the mode frequencies.Comment: 10 pages, 2 figure
Water management at BedZED - Some lessons
Copyright © 2008 ICE Publishing Ltd. Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.The Beddington zero fossil energy development (BedZED) in London, UK, is something of a modern icon in terms of assembling simultaneously on the same site new construction methods, the best of available ‘green’ technology and social engineering combined with new peri-urban lifestyles. The development also includes a number of ‘alternative’ water systems. As with many innovative and exploratory departures, however, not everything went according to plan. This paper describes the bold vision, highlights some of the issues and seeks to learn and disseminate lessons for the future, with special reference to the integrated water and wastewater services
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