Data-driven model of the hippocampus using the HBP Brain Simulation Platform

The hippocampus is one of four brain regions being modeled in the ramp-up phase of the Human Brain Project (HBP), testing and guiding the development of the HBP Brain Simulation Platform (BSP) to be released in March 2016. Using preliminary versions of BSP applications developed at the Blue Brain Project, a first draft data-driven model of hippocampus was assembled, integrating data available from HBP and community sources. In brief, the building process started by populating the hippocampal volume, defined by the Allen Brain Atlas, with a series of reconstructions of well-characterized cell types according to experimentally observed densities and proportions. A connectome was generated as previously described [1], constrained by biological values for bouton density and synapses per connection. Single cell electrical models and synapse physiology were constrained by electrophysiological recordings and publicly available data. Further datasets not used as input during model building were used to validate the model. This first draft of the circuit model and the pipeline to build it are to be released with the HBP-BSP in March 2016, and they will be periodically updated. The model represents a resource for the community to integrate data, perform in silico experiments, and test hypotheses. Establishing a community process for the continued refinement of the model is planned for the next phase of the HBP. [1] Reimann, M. et al. An algorithm to predict the connectome of neural microcircuits. Front. Comput. Neurosci. (2015). http://dx.doi.org/10.3389/fncom.2015.0012

Selective Growth of Low Stored Energy Grains During δ Sub-solvus Annealing in the Inconel 718 Nickel-Based Superalloy

The microstructure stability during δ sub-solvus annealing in Inconel 718 was investigated, focusing on the conditions that may lead to the development of very large grains (about 100 μm) in a recrystallized fine grained matrix (4 to 5 μm) despite the presence of second-phase particles. Microstructure evolution was analyzed by EBSD (grain size, intragranular misorientation) and SEM (δ phase particles). Results confirm that, in the absence of stored energy, the grain structure is controlled by the δ phase particles, as predicted by the Smith–Zener equation. If the initial microstructure is strained (ε < 0.1) before annealing, then low stored energy grains grow to a large extent, despite the Zener pinning forces exerted by the second-phase particles on the grain boundaries. Those selectively growing grains could be those of the initial microstructure that were the least deformed, or they could result from a nucleation process. The balance of three forces acting on boundary migration controls the growth process: if the sum of capillarity and stored energy driving forces exceeds the Zener pinning force, then selective grain growth occurs. Such phenomenon could be simulated, using a level set approach in a finite element context, by taking into account the three forces acting on boundary migration and by considering a realistic strain energy distribution (estimated from EBSD measurements). © 2015, The Minerals, Metals & Materials Society and ASM International

Design of the LINAC4 Transfer Line Quadrupole Electromagnets

Beam focusing in the various segments of the Linac4 Transfer Line is provided by quadrupole electromagnets. In total seventeen pulsed, air-cooled quadrupole electromagnets are required. They are made of laminated electrical steel yokes and coils wound from solid copper wire. All magnets have an aperture radius of 50 mm and are required to provide an integrated field gradient of 1.8 T over a magnetic length of 300 mm. This design report summarizes the main magnetic, electrical and mechanical design parameters of the Linac4 Transfer Line Quadrupole Magnets. The effect of the vacuum chamber on the magnetic field quality and the field delay is studied

Design of Corrector Magnets for PSB Injection

Two types of combined horizontal and vertical plane corrector magnets are required for PSB beam injection. The first type requires a free aperture of 150 mm × 150 mm and an integrated field strength of 0.0130 Tm, while the second type requires an aperture of 70 mm × 70 mm and an integrated field strength of 0.0160 Tm. In order to reduce the costs and the number of spare magnets, a common design is proposed, satisfying the most stringent requirements for both magnet types. This report summarizes the magnet design

On Fan Raspaud conjecture

A conjecture of Fan and Raspaud [3] asserts that every bridgeless cubic graph contains three perfect matchings with empty intersection. Kaiser and Raspaud [6] suggested a possible approach to this problem based on the concept of a balanced join in an embedded graph. We give here some new results concerning this conjecture and prove that a minimum counterexample must have at least 32 vertices. Key words: Cubic graph; Edge-partition;

Kaiser-Raspaud Conjecture on Cubic Graphs

A conjecture of Kaiser and Raspaud [6] asserts (in a special form due to Mácajová and Skoviera) that every bridgeless cubic graph has two perfect matchings whose intersection does not contain any odd edge cut. We prove this conjecture for graphs with few vertices and we give a stronger result for traceable graphs