Comparison of the generic neuronal differentiation and neuron subtype specification functions of mammalian achaete-scute and atonal homologs in cultured neural progenitor cells

In the vertebrate peripheral nervous system, the proneural genes neurogenin 1 and neurogenin 2 (Ngn1 and Ngn2), and Mash1 are required for sensory and autonomic neurogenesis, respectively. In cultures of neural tube-derived, primitive PNS progenitors NGNs promote expression of sensory markers and MASH1 that of autonomic markers. These effects do not simply reflect enhanced neuronal differentiation, suggesting that both bHLH factors also specify neuronal identity like their Drosophila counterparts. At high concentrations of BMP2 or in neural crest stem cells (NCSCs), however, NGNs like MASH1 promote only autonomic marker expression. These data suggest that that the identity specification function of NGNs is more sensitive to context than is that of MASH1. In NCSCs, MASH1 is more sensitive to Notch-mediated inhibition of neurogenesis and cell cycle arrest, than are the NGNs. Thus, the two proneural genes differ in other functional properties besides the neuron subtype identities they can promote. These properties may explain cellular differences between MASH1- and NGN-dependent lineages in the timing of neuronal differentiation and cell cycle exit

The simulated cooling of the hot-rolled structural steel sections

AbstractTemperature models based on the finite difference, ADI and Runge-Kutta methods have been written in order to establish the most efficient algorithm when simulating the cooling of newly hot-rolled steel sections under a variety of cooling conditions. For air-cooling, the most efficient results were obtained using extended-stability Runge-Kutta methods, together with adaptive step-size control procedures. CPU time-savings of around 85% were achieved when an existing finite difference based section air-cooling model was modified to run using a specially developed, highly stable, second-order Runge-Kutta formula with the method of lines. The ADI approach gave the most efficient results for water spray cooling, producing accurate results in approximately half the CPU time required by the finite difference method

A method for solving systems of non-linear differential equations with moving singularities

We present a method for solving a class of initial valued, coupled, non-linear differential equations with `moving singularities' subject to some subsidiary conditions. We show that this type of singularities can be adequately treated by establishing certain `moving' jump conditions across them. We show how a first integral of the differential equations, if available, can also be used for checking the accuracy of the numerical solution.Comment: 9 pages, 7 eps figures, to appear in Comput. Phys. Co

The potential of geospatial tools for enhancing community engagement in the post-disaster reconstruction of Christchurch, New Zealand

AbstractThe Christchurch, New Zealand, earthquakes of 2010 and 2011 provide ample opportunities to trial new geospatial technologies in the reconstruction of the city. These earthquakes, measuring magnitudes 7.1 and 6.3, resulted in severe damage to housing and building stock. An estimated 75% of residential buildings suffered some form of damage, with 7.5% collapsed or requiring demolition. These impacts were felt most severely in mid-suburban areas closest to the sea and in commercial buildings located in the CBD, where 90% of buildings have now been demolished. The severe damage in these areas has put pressure on housing, retail, and commercial premises throughout the city. Additionally, therehas been great pressure on the below ground infrastructure, transport networks, and social services and amenities; all of which have had to change due to large population and activity movements. This has extenuated longer-term socio-demographic trends in housing and building demands. As a response, a major reconstruction effort is underway. This research looks for ways to integrate new geospatial technologies to promote better community engagement in the decision-making process. The geospatial planning tools being trialled, Envision and ESP (Envision Scenario Planning), assess optimal redevelopment opportunities, identify suitable redevelopment areas, model different scenarios as variables and 3D visualisations, and assess different precinct style design typologies. The tools, developed by “Greening the Greyfields” research teams at Swinburne University of Technology (Melbourne, Victoria, Australia) and Curtin University (Perth, Western Australia, Australia), were utilised in the regeneration of mid-suburban areas in Australian cities, and now the implementation has been extended to post-disaster Christchurch. It is anticipatedthat this will improve communication within communities and enhance development outcomes through greater consensus between residents, developers, planners, and other stakeholders

The proof of concept of a fused radiometric and optical stereoscopic imaging system

The proof of concept of a fused radiometric and optical stereoscopic imaging device is presented. The project was in collaboration with the National Nuclear Laboratory and the Nuclear Decommissioning Authority with the aim of developing a sensor that can be deployed in a nuclear decommissioning environment. The radiometric system was a Compton camera comprised of two HPGe planar detectors and presents a significant improvement in efficiency and dynamic range over coded aperture systems currently used in industry. The optical stereoscopic camera is the proprietary Bumblebee XB3 system that provides 3D physical information of the surroundings. Two main experiments are presented; the first investigated the disparity between true source location and reconstructed image position. This disparity was proven and methods for accounting for and correcting it were developed, whereby the image position accuracy was improved by a factor of 26.7. The second experiment imaged 20 MBq $^{137}$Cs sources at distances of 80 - 150 cm with both radiometric and optical stereoscopic systems simultaneously. The first fused images were produced using this data, with the radiometric sources and surroundings clearly visible. A GUI was developed in Matlab to process and fuse the data. Alongside both experiments image optimisation techniques were investigated. Pulse shape analysis was implemented and shown to improve image resolution by 30\% on average at the expense of efficiency. Fold 2 event imaging was conversely shown to improve efficiency at the expense of image resolution. This work provides the basis to develop the project towards a complete system. The steps that must be taken to realise this are outlined and recommendations for overcoming potential challenges are discussed

Neural crest stem cells undergo multilineage differentiation in developing peripheral nerves to generate endoneurial fibroblasts in addition to Schwann cells

Neural crest stem cells (NCSCs) persist in peripheral nerves throughout late gestation but their function is unknown. Current models of nerve development only consider the generation of Schwann cells from neural crest, but the presence of NCSCs raises the possibility of multilineage differentiation. We performed Cre-recombinase fate mapping to determine which nerve cells are neural crest derived. Endoneurial fibroblasts, in addition to myelinating and non-myelinating Schwann cells, were neural crest derived, whereas perineurial cells, pericytes and endothelial cells were not. This identified endoneurial fibroblasts as a novel neural crest derivative, and demonstrated that trunk neural crest does give rise to fibroblasts in vivo, consistent with previous studies of trunk NCSCs in culture. The multilineage differentiation of NCSCs into glial and non-glial derivatives in the developing nerve appears to be regulated by neuregulin, notch ligands, and bone morphogenic proteins, as these factors are expressed in the developing nerve, and cause nerve NCSCs to generate Schwann cells and fibroblasts, but not neurons, in culture. Nerve development is thus more complex than was previously thought, involving NCSC self-renewal, lineage commitment and multilineage differentiation

Quantum Control of Interacting Bosons in Periodic Optical Lattice

We study the avoided crossings in the dynamics of quantum controlled excitations for an interacting two-boson system in an optical lattice. Specifically, we perform numerical simulations of quantum control in this system where driving pulses connect the undriven stationary states in a manner characteristic of Stimulated Raman Adiabatic Passage (STIRAP). We demonstrate that the dynamics of such a transition is affected by chaos induced avoided crossings, resulting in a loss in coherence of the final outcome in the adiabatic limit.Comment: Accepted for publication in Physica E. Typo corrections to final versio

Solving Langevin equation with the bicolour rooted tree method

Stochastic differential equations, especially the one called Langevin equation, play an important role in many fields of modern science. In this paper, we use the bicolour rooted tree method, which is based on the stochastic Taylor expansion, to get the systematic pattern of the high order algorithm for Langevin equation. We propose a popular test problem, which is related to the energy relaxation in the double well, to test the validity of our algorithm and compare our algorithm with other usually used algorithms in simulations. And we also consider the time-dependent Langevin equation with the Ornstein-Uhlenbeck noise as our second example to demonstrate the versatility of our method

Integrating rotation from angular velocity

Abstract\ud The integration of the rotation from a given angular velocity is often required in practice. The present paper explores how the choice of the parametrization of rotation, when employed in conjuction with different numerical time-integration schemes, effects the accuracy and the computational efficiency. Three rotation parametrizations – the rotational vector, the Argyris tangential vector and the rotational quaternion – are combined with three different numerical time-integration schemes, including classical explicit Runge–Kutta method and the novel midpoint rule proposed here. The key result of the study is the assessment of the integration errors of various parametrization–integration method combinations. In order to assess the errors, we choose a time-dependent function corresponding to a rotational vector, and derive the related exact time-dependent angular velocity. This is then employed in the numerical solution as the data. The resulting numerically integrated approximate rotations are compared with the analytical solution. A novel global solution error norm for discrete solutions given by a set of values at chosen time-points is employed. Several characteristic angular velocity functions, resulting in small, finite and fast oscillating rotations are studied