38,394 research outputs found
The statistical mechanics of the two-dimensional hydrogen-bonding self-avoiding walk including solvent effects
A two-dimensional square-lattice model for the formation of secondary
structures in proteins, the hydrogen-bonding model, is extended to include the
effects of solvent quality. This is achieved by allowing
configuration-dependent nearest-neighbour interactions. The phase diagram is
presented, and found to have a much richer variety of phases than either the
pure hydrogen-bonding self-avoiding walk model or the standard -point
model.Comment: 23 pages 15 figure
Fast Ridge Regression with Randomized Principal Component Analysis and Gradient Descent
We propose a new two stage algorithm LING for large scale regression
problems. LING has the same risk as the well known Ridge Regression under the
fixed design setting and can be computed much faster. Our experiments have
shown that LING performs well in terms of both prediction accuracy and
computational efficiency compared with other large scale regression algorithms
like Gradient Descent, Stochastic Gradient Descent and Principal Component
Regression on both simulated and real datasets
Universality of collapsing two-dimensional self-avoiding trails
Results of a numerically exact transfer matrix calculation for the model of
Interacting Self-Avoiding Trails are presented. The results lead to the
conclusion that, at the collapse transition, Self-Avoiding Trails are in the
same universality class as the O(n=0) model of Blote and Nienhuis (or
vertex-interacting self-avoiding walk), which has thermal exponent ,
contrary to previous conjectures.Comment: Final version, accepted for publication in Journal of Physics A; 9
pages; 3 figure
Expert perspectives on the future of the organic food market: results of a Pan-European Delphi study
A Delphi Inquiry was carried out to assess the prospect and conditions affecting the overall growth in the European Market for organic products in the coming decade, and to provide support for research. Countries were classified as established, growing and emerging, according to the state of development of their organic market. The survey confirmed the importance of factors influencing the development of the organic food market: the supply base, the role of supermarkets as sales channels and of government support. Organic Producer Initiatives were seen as important in securing a fair deal for organic producers but managerial capacity and professionalism are key challenges for such organizations
The drag of a body moving transversely in a confined stratified fluid
The slow motion of a body through a stratified fluid bounded laterally by insulating walls is studied for both large and small Peclet number. The Taylor column and its associated boundary and shear layers are very different from the analogous problem in a rotating fluid. In particular, the large Peclet number problem is non-linear and exhibits mixing of statically unstable fluid layers, and hence the drag is order one; whereas the small Peclet number flow is everywhere stable, and the drag is of the order of the Peclet number
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