High-order accurate difference schemes for the Hodgkin-Huxley equations

A novel approach for simulating potential propagation in neuronal branches with high accuracy is developed. The method relies on high-order accurate difference schemes using the Summation-By-Parts operators with weak boundary and interface conditions applied to the Hodgkin-Huxley equations. This work is the first demonstrating high accuracy for that equation. Several boundary conditions are considered including the non-standard one accounting for the soma presence, which is characterized by its own partial differential equation. Well-posedness for the continuous problem as well as stability of the discrete approximation is proved for all the boundary conditions. Gains in terms of CPU times are observed when high-order operators are used, demonstrating the advantage of the high-order schemes for simulating potential propagation in large neuronal trees

Effects of Economic Policies Aimed at Encouraging a Healthier Grain Consumption

In this paper, we evaluate the effects of policy reforms aimed at achieving two policy objectives for grain consumption; (a) to double the intake of bread and breakfast cereals and (b) to ensure that half of the bread and breakfast cereals consumed are whole grain products. The overall aim of these policy objectives are to increase the dietary fibre intake from grain consumption so as to significantly contribute to the general recommended (minimum) increase of the fibre intake. Based on parameter estimates from a demand system we simulate the resulting changes in volumes purchased and fibre intake from two policy reforms entailing differentiated VAT on grain products. In the first reform we remove the VAT on "keyhole labelled" bread and breakfast cereals, in the second reform we consider a more extensive policy package of subsidizing the keyhole labelled bread and breakfast cereals by 20 percent while removing the VAT on all other grain products. Our results indicate that both reforms are likely to be successful in ensuring that the consumers attain the nutrition recommendations that half of the bread and breakfast cereals consumed are whole grain products, but that additional policy instruments are needed to reach the recommendation that the intake of bread and breakfast cereals should be doubled.Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety,

Discretization of the Superparticle Path Integral

Requiring that the path integral has the global symmetries of the classical action and obeys the natural composition property of path integrals, and also that the discretized action has the correct naive continuum limit, we find a viable discretization of the (D=3,N=2) superparticle action.Comment: 10 page

The Relaxed Edge-Coloring Game and \u3cem\u3ek\u3c/em\u3e-Degenerate Graphs

The (r, d)-relaxed edge-coloring game is a two-player game using r colors played on the edge set of a graph G. We consider this game on forests and more generally, on k-degenerate graphs. If F is a forest with ∆(F) = ∆, then the first player, Alice, has a winning strategy for this game with r = ∆ − j and d ≥ 2j + 2 for 0 ≤ j ≤ ∆ − 1. This both improves and generalizes the result for trees in [10]. More broadly, we generalize the main result in [10] by showing that if G is k-degenerate with ∆(G) = ∆ and j ∈ [∆ + k − 1], then there exists a function h(k, j) such that Alice has a winning strategy for this game with r = ∆ + k − j and d ≥ h(k, j)

Giving top quark effective operators a boost

We investigate the prospects to systematically improve generic effective field theory-based searches for new physics in the top sector during LHC run 2 as well as the high luminosity phase. In particular, we assess the benefits of high momentum transfer final states on top EFT-fit as a function of systematic uncertainties in comparison with sensitivity expected from fully-resolved analyses focusing on $t\bar t$ production. We find that constraints are typically driven by fully-resolved selections, while boosted top quarks can serve to break degeneracies in the global fit. This demystifies and clarifies the importance of high momentum transfer final states for global fits to new interactions in the top sector from direct measurements.Comment: Published versio

A Microstructural View of Burrowing with RoboClam

RoboClam is a burrowing technology inspired by Ensis directus, the Atlantic razor clam. Atlantic razor clams should only be strong enough to dig a few centimeters into the soil, yet they burrow to over 70 cm. The animal uses a clever trick to achieve this: by contracting its body, it agitates and locally fluidizes the soil, reducing the drag and energetic cost of burrowing. RoboClam technology, which is based on the digging mechanics of razor clams, may be valuable for subsea applications that could benefit from efficient burrowing, such as anchoring, mine detonation, and cable laying. We directly visualize the movement of soil grains during the contraction of RoboClam, using a novel index-matching technique along with particle tracking. We show that the size of the failure zone around contracting RoboClam, can be theoretically predicted from the substrate and pore fluid properties, provided that the timescale of contraction is sufficiently large. We also show that the nonaffine motions of the grains are a small fraction of the motion within the fluidized zone, affirming the relevance of a continuum model for this system, even though the grain size is comparable to the size of RoboClam