BEAMS Lab at MIT: Status report

The Biological Engineering Accelerator Mass Spectrometry (BEAMS) Lab at the Massachusetts Institute of Technology is a facility dedicated to incorporating AMS into life sciences research. As such, it is focused exclusively on radiocarbon and tritium AMS and makes use of a particularly compact instrument of a size compatible with most laboratory space. Recent developments at the BEAMS Lab were aimed to improve different stages of the measurement process, such as the carbon sample injection interface, the simultaneous detection of tritium and hydrogen and finally, the overall operation of the system. Upgrades and results of those efforts are presented here.United States. National Institutes of Health (grant P30-ES02109)United States. National Institutes of Health (grant R42-CA084688)National Institutes of Health. National Center for Research Resources (grant UL1 RR 025005)GlaxoSmithKlin

Nest-defense Behavior of Mississippi Kites in Urban and Exurban Areas

Mississippi kites (Ictinia mississippiensis) have become an abundant raptor in many urban and exurban areas throughout the Southern Great Plains of the United States. Unfortunately, human–wildlife conflicts have resulted from this juxtaposition of suitable breeding areas for kites and areas that humans frequent, with some kites responding aggressively to humans near nests. To date, there are no data describing the prevalence of aggressive nest defense in the species, making informed management of human and kite conflicts difficult. We assessed and compared the prevalence of aggressive nest-defense by Mississippi kites in an urban area and an exurban area by simulating nest disturbance with a trial pedestrian. Additionally, we examine the relationships between physical features of the nest tree where aggressive behaviors were and were not recorded. Individual kites breeding in the exurban area responded to the trial pedestrian by taking flight from the nesting area, circling overhead, swooping at the pedestrian, or remaining on the nest. In the urban area, kites displayed a more limited suit of responses and either remained on the nest or swooped at the pedestrian. Additionally, kites breeding in the exurban area appeared to respond to experimental disturbance at a greater distance than did urban breeding kites, but not with more attacks on pedestrians. Physical characteristics of the nest tree did not explain aggressive behaviors, thereby suggesting that aggression in Mississippi kites is caused by factors other than nesting location features

Characterisation of the artist John Opie’s pigments, dated 1806

This paper discusses the contents of an artist’s paint box currently in the possession of St. Agnes Museum, Cornwall, UK, containing a selection of historic pigments. On its lid is a metal plaque that reads ‘John Opie 1806’. Very little is known about this paint box, so this piece of research aims to uncover some of the hidden information stored within it through identification of some of the pigments it contains. The main body of this research shows the first results obtained by the identification of a selection of the pigments from the paint box, using Fourier Transform Infra Red spectroscopy (FTIR) and optical microscopy techniques. These findings will be considered in relation to what this tells us about the artist John Opie, the authenticity of the pigments within the paint box, and the use of pigments in the early nineteenth century

Shape analysis of railway ballast stones : curvature-based calculation of particle angularity

Particle shape analysis is conducted, to compare two types of railway ballast: Calcite and Kieselkalk. Focus lies on the characterisation of particle angularity using 3D scanner data. In the literature, angularity is often characterised using 2D data, as these types of data are easier to collect. 3D scanner data contain a vast amount of information (e.g. curvatures) which can be used for shape analysis and angularity characterisation. Literature approaches that use 3D data are often not thoroughly tested, due to a lack of test cases. In this work, two new curvature-based angularity indices are introduced and compared to one from the literature. Analytical test bodies with shapes ranging from spherical towards cubic are used for a first plausibility test. Then, 3D scans of ballast stones are compared to artificially rounded meshes. Only one out of three evaluated angularity indices seem to be suited to characterise angularity correctly in all of the above tests: the newly introduced scaled Willmore energy. A complete shape analysis of the scanned ballast stones is conducted and no difference between the two types of ballast can be seen regarding form, angularity, roughness, sphericity or convexity index. These findings of shape analysis are set in the context of previous works, where experimental results and DEM simulations of uniaxial compression tests and direct shear tests were presented for the same ballast types

Particle characterisation of rail sands for understanding tribological behaviour

Low adhesion between a train’s wheel and the rail can cause performance and safety issues, costing the UK rail industry ~£345 m/annum. Sand is applied to the wheel/rail interface to increase traction when low adhesion conditions are present. In order to improve performance, an understanding of how particles are entrained into and act within the interface is needed. This paper outlines a particle characterisation framework and applies it to sands used in the rail industry: Leighton Buzzard (LB), Central European (CE), and Derbyshire Youlgreave (DY) sand. The largest difference found in this framework was between the sand’s particle size, LB being largest, then CE, then DY. A high pressure torsion rig measured traction when the sands were applied to dry, wet, and leaf extract contaminated conditions, the latter two representing low adhesion conditions. All sands had no impact on wheel/rail adhesion in dry conditions; in low adhesion conditions DY had little influence, whereas LB and CE were found to increase traction. Particles in dry conditions had no effect on test specimen surface roughness, whereas roughness increased when sand was applied in low adhesion conditions. The developed characterisation framework provides a platform for assessing prospective adhesion enhancing particles

Characterisation and Tribological Testing of Recycled Crushed Glass as an Alternative Rail Sand

In the UK Network Rail Environmental Sustainability Strategy 2020–2050, minimal waste and the sustainable use of materials are highlighted as core priorities. The ambition is to reuse, repurpose or redeploy all resources. In low adhesion conditions, sand particles are used to enhance traction throughout the network. However, sand is in danger of becoming scarce as many applications demand it. In this study, an alternative adhesion enhancing particle system made of recycled crushed glass is examined in terms of density, size, shape distribution, mineralogy, mechanical properties, and bulk behaviour to better understand their characteristics in comparison with the typical Great British rail sand currently in use and reported in the literature. Their effects on tribological behaviour and surface damage are also investigated using the High-Pressure Torsion test in dry, wet, and leaf-contaminated conditions. Both particle characterisation and tribological testing show promising results. Recycled glass particles provide an acceptable level of traction with a similar level of rail damage as typical rail sand. It is suggested to perform full-scale laboratory and field tests to further confirm the suitability of this material