Patterns of brain growth in one FGFR2 mouse model for Apert Syndrome

Apert syndrome is a disorder associated with craniosynostosis resulting from one of two mutations in Fibroblast Growth Factor Receptor 2 (FGFR2). Individuals with Apert syndrome demonstrate brain dysmorphology, often associated with cognitive deficits. In this study, micro magnetic resonance images of the brain of FGFR2+/P253R mice and their wildtype littermates were acquired at two ages, P0 (newborn) and P2 (two days old). Fifteen landmarks on the brain surface were collected to compare growth patterns in the morphological phenotypes of the brain."Work supported by NIDCR R01 DE018500

Experimentation and modelling of near field explosions

Repeatable experimental results and numerical work has shown that using the Jones-Wilkins-Lee (JWL) equation of state (EOS) will give very accurate results of peak pressures and impulse delivered to a rigid target at large scaled distances. However, recent experiments/numerical modelling at small scaled distances show that the JWL will overpredict peak pressures and impulse due to the assumption of (near) instantaneous energy release from detonation. The results of this experimental/numerical study are presented herein. In the experimental work PE4 spheres at two different scaled distances have been tested using an array of Hopkinson Pressure Bars (HPB) at specific points on a rigid target to measure the local pressure-time histories. From the HPB measurements, it appears that below certain scaled distances there are chemical-physical mechanisms that do not have sufficient time to contribute to the energy driving the loading mechanisms, explaining the over-prediction of the JWL. Importantly though, the experimental results show that at very small scaled distances (0.172 m/kg1/3) the test to test percentage variation is very low (5.1%); whilst at larger scaled distances (0.819 m/kg1/3) it is much higher (23.1%). This paper presents a model which describes the process by which experimental results move from repeatable to variable to repeatable as scaled distance increases from the extreme near field to far field

Reflected pressures from explosives buried in idealised cohesive soils

Recent work has concentrated on the characterisation of the temporal and spatial impulse distribution of blast form buried charges. A new soil container preparation methodology has been created to allow for the generation of highly repeatable, tightly controlled clay beds which will allow clays of different undrained strengths to be generated. Tests using these well controlled beds has allowed for an improved understanding into which geotechnical parameters govern the impulse delivered by a buried charge. Namely in the current programme of work this is an investigation into the ‘undrained strength’ of a cohesive material as an indicator of potential impulse output. Initial results are compared against previously published work on cohesionless soils (sands) to try to establish the full range of loading which can be generated by a buried charge

Influence of particle size distribution on the blast pressure profile from explosives buried in saturated soils

The spatial and temporal distribution of pressure and impulse from explosives buried in saturated cohesive and cohesionless soils has been measured experimentally for the first time. Ten experiments have been conducted at quarter-scale, where localised pressure loading was measured using an array of 17 Hopkinson pressure bars. The blast pressure measurements are used in conjunction with high-speed video filmed at 100,000 fps to investigate in detail the physical processes occurring at the loaded face. Two coarse cohesionless soils and one fine cohesive soil were tested: a relatively uniform sand, a well-graded sandy-gravel, and a fine-grained clay. The results show that there is a single fundamental loading mechanism when explosives are detonated in saturated soil, invariant of particle size and soil cohesion. It is also shown that variability in localised loading is intrinsically linked to the particle size distribution of the surrounding soil

Localised variations in reflected pressure from explosives buried in uniform and well-graded soils

Recent experiments into characterisation of the loading resulting from detonation of a shallow buried explosive have highlighted the complex underlying physical mechanisms present at the face of a target situated above the soil surface. This paper presents the results from such experiments, where the localised blast pressure and impulse is measured using an array of Hopkinson pressure bars at specific points on the target surface. Two different soil types are tested; a relatively uniform sand, and well-graded sandy-gravel. It is observed that the variability in localised loading is intrinsically linked to the particle size distribution of the soil medium; the uniform soil produces repeatable data with little variation whereas the well-graded soil demonstrates considerable spread. The cause of this spread is quantified and discussed with reference to the distinct loading mechanisms acting on the target as seen in the experimental data

Photodiodes based in La0.7Sr0.3MnO3/single layer MoS2 hybrid vertical heterostructures

The fabrication of artificial materials by stacking of individual two-dimensional (2D) materials is amongst one of the most promising research avenues in the field of 2D materials. Moreover, this strategy to fabricate new man-made materials can be further extended by fabricating hybrid stacks between 2D materials and other functional materials with different dimensionality making the potential number of combinations almost infinite. Among all these possible combinations, mixing 2D materials with transition metal oxides can result especially useful because of the large amount of interesting physical phenomena displayed separately by these two material families. We present a hybrid device based on the stacking of a single layer MoS2 onto a lanthanum strontium manganite (La0.7Sr0.3MnO3) thin film, creating an atomically thin device. It shows a rectifying electrical transport with a ratio of 103, and a photovoltaic effect with Voc up to 0.4 V. The photodiode behaviour arises as a consequence of the different doping character of these two materials. This result paves the way towards combining the efforts of these two large materials science communities.Comment: 1 table, 4 figures (+9 supp. info. figures

Influence of particle size distribution on the blast pressure profile from explosives buried in saturated soils

The spatial and temporal distribution of pressure and impulse from explosives buried in saturated cohesive and cohesionless soils has been measured experimentally for the first time. Ten experiments have been conducted at quarter-scale, where localised pressure loading was measured using an array of 17 Hopkinson pressure bars. The blast pressure measurements are used in conjunction with high-speed video filmed at 100,000 fps to investigate in detail the physical processes occurring at the loaded face. Two coarse cohesionless soils and one fine cohesive soil were tested: a relatively uniform sand, a well-graded sandy-gravel, and a fine-grained clay. The results show that there is a single fundamental loading mechanism when explosives are detonated in saturated soil, invariant of particle size and soil cohesion. It is also shown that variability in localised loading is intrinsically linked to the particle size distribution of the surrounding soil

Finite element simulation of plates under non-uniform blast loads using a point-load method: Buried explosives

There are two primary challenges associated with assessing the adequacy of a protective structure to resist explosive events: firstly the spatial variation of load acting on a target must be predicted to a sufficient level of accuracy; secondly, the response of the target to this load must also be quantified. When a high explosive is shallowly buried in soil, the added confinement given by the geotechnical material results in a blast which is predominantly directed vertically. This imparts an extremely high magnitude, spatially non-uniform load on the target structure. A recently commissioned experimental rig designed by the authors has enabled direct measurements of the blast load resulting from buried explosive events. These direct measurements have been processed using an in-house interpolation routine which evaluates the load acting over a regular grid of points. These loads can then be applied as the nodal-point loads in a finite element model. This paper presents results from a series of experiments where a free-flying plate was suspended above a shallow buried explosive. Dynamic and residual deformations are compared with finite element simulations of plates using the experimentally recorded, and interpolated, nodal point-loads. The results show very good agreement and highlight the use of this method for evaluating the efficacy of targets subjected to non-uniform blast loads

Morphological Description of Telaepolella tubasferens n. g., n. sp., Isolate ATCC© 50593™, a Filose Amoeba in the Gracilipodida, Amoebozoa

We describe the amoeboid isolate ATCC© 50593™ as a new taxon, Telaepolella tubasferens n. gen. n. sp. This multinucleated amoeba has filose pseudopods and is superficially similar to members of the vampyrellids (Rhizaria) such as Arachnula impatiens Cienkowski, 1876, which was the original identification upon deposition. However, previous multigene analyses place this taxon within the Gracilipodida Lahr and Katz 2011 in the Amoebozoa. Here, we document the morphology of this organism at multiple life history stages and describe data underlying the description as a new taxon. We demonstrate that T. tubaspherens is distinct from Arachnula and other rhizarians (Theratromyxa, Leptophrys) in a suite of morphological characters such as general body shape, relative size of pseudopods, distinction of ecto- and endoplasmic regions, and visibility of nuclei in non-stained cells (an important diagnostic character). Although Amoebozoa taxa generally have lobose pseudopods, genera in Gracilipodida such as Flamella and Filamoeba as well as several organisms previously classified as protosteloid amoebae (e.g. schizoplasmodiis, cavosteliids and Stemonitales) present filose pseudopodia. Thus, classification of amoeboid organisms merely by filose-lobose distinction must be reconsidered