An Anglo-Saxon execution cemetery at Walkington Wold, Yorkshire

This paper presents a re-evaluation of a cemetery excavated over 30 years ago at Walkington Wold in east Yorkshire. The cemetery is characterized by careless burial on diverse alignments, and by the fact that most of the skeletons did not have associated crania. The cemetery has been variously described as being the result of an early post-Roman massacre, as providing evidence for a ‘Celtic’ head cult or as an Anglo-Saxon execution cemetery. In order to resolve the matter, radiocarbon dates were acquired and a re-examination of the skeletal remains was undertaken. It was confirmed that the cemetery was an Anglo-Saxon execution cemetery, the only known example from northern England, and the site is set into its wider context in the paper

Modelling the effect of L/S ratio and granule moisture content on the compaction properties in continuous manufacturing

The pharmaceutical field is currently moving towards continuous manufacturing pursuing reduced waste, consistency, and automation. During continuous manufacturing, it is important to understand how both operating conditions and material properties throughout the process affect the final properties of the product to optimise and control production. In this study of a continuous wet granulation line, the liquid to solid ratio (L/S) and drying times were varied to investigate the effect of the final granule moisture content and the liquid to solid ratio on the properties of the granules during tabletting and the final tensile strength of the tablets. Both variables (L/S and granule moisture) affected the tablet tensile strength with the moisture content having a larger impact. Further analysis using a compaction model, showed that the compactability of the granules was largely unaffected by both L/S and moisture content while the compressibility was influenced by these variables, leading to a difference in the final tablet strength and porosity. The granule porosity was linked to the L/S ratio and used instead for the model fitting. The effect of moisture content and granule porosity was added to the model using a 3d plane relationship between the compressibility constant, the moisture content and porosity of the granules. The tablet tensile strength model, considering the effect of moisture and granule porosity, performed well averaging a root mean squared error across the different conditions of 0.17 MPa

Multidimensional relativistic MHD simulations of Pulsar Wind Nebulae: dynamics and emission

Pulsar Wind Nebulae, and the Crab nebula in particular, are the best cosmic laboratories to investigate the dynamics of magnetized relativistic outflows and particle acceleration up to PeV energies. Multidimensional MHD modeling by means of numerical simulations has been very successful at reproducing, to the very finest details, the innermost structure of these synchrotron emitting nebulae, as observed in the X-rays. Therefore, the comparison between the simulated source and observations can be used as a powerful diagnostic tool to probe the physical conditions in pulsar winds, like their composition, magnetization, and degree of anisotropy. However, in spite of the wealth of observations and of the accuracy of current MHD models, the precise mechanisms for magnetic field dissipation and for the acceleration of the non-thermal emitting particles are mysteries still puzzling theorists to date. Here we review the methodologies of the computational approach to the modeling of Pulsar Wind Nebulae, discussing the most relevant results and the recent progresses achieved in this fascinating field of high-energy astrophysics.Comment: 29 pages review, preliminary version. To appear in the book "Modelling Nebulae" edited by D. Torres for Springer, based on the invited contributions to the workshop held in Sant Cugat (Barcelona), June 14-17, 201

Random close packing of granular matter

We propose an interpretation of the random close packing of granular materials as a phase transition, and discuss the possibility of experimental verification.Comment: 6 page

Theory, Design, and Characterization of Nanoelectromechanical Relays for Stiction-Based Non-Volatile Memory

Diverse areas such as the Internet of Things (IoT), aerospace and industrial electronics increasingly require non-volatile memory to work under high-temperature, radiation-hard conditions, with zero standby power. Nanoelectromechanical (NEM) relays uniquely have the potential to work at 300°C and absorb high levels of radiation, with zero leakage current across the entire operational range. While NEM relays that utilise stiction for non-volatile operation have been demonstrated, it is not clear how to design a relay to reliably achieve given programming and reprogramming voltages, an essential requirement in producing a memory. Here, we develop an analytical, first-principle physics-based model of rotational NEM relays to provide detailed understanding of how the programming and reprogramming voltages vary based on the device dimensions and surface adhesion force. We then carry out an experimental parametric study of relays with a critical dimension of ≈80 nm to characterise the surface adhesion force, and derive guidelines for how a NEM relay should be dimensioned for a given contact surface force, feature size constraints and operating requirements. We carry out a scaling study to show that voltages of ≈1 V and a footprint under ≈2 μm² can be achieved with a critical dimension of ≈10 nm, with this device architecture. [2021-0138] IEE

Increasing Men's Engagement in HIV Testing and Treatment Programs through Crowdsourcing: A Mixed-Methods Analysis in Eswatini

Background Sub-Saharan African HIV programs have had limited success in engaging men. Crowdsourcing contests may be a useful method to spur men's engagement in HIV services. We evaluated contributions and social media response to a crowdsourcing contest focused on increasing men's engagement in Eswatini HIV services. Methods We conducted a crowdsourcing contest to gain insight from the public on how HIV campaigns can more effectively engage young (20-40 years old) men in HIV services. Eligible submissions included images, songs, videos, and Internet memes. We used standard qualitative methods to examine textual themes from submissions. We examined social media response using Facebook analytics, comparing the number of people reached through crowdsourced HIV messages and the number of people reached through conventional HIV messages. Results We received 144 submissions from 83 participants. They represented 55 towns and all 4 regions of Eswatini. The contest page gained 461 followers on Facebook. Emergent themes included appealing to men's roles as protectors by suggesting that they need to take care of their own health to continue safeguarding their families. Crowdsourced messages reached a mean of 88 individuals across 4 posts; conventional messages reached a mean of 75 individuals across 4 posts. Conclusions Crowdsourcing contest submissions provided insight on how to encourage men to engage in Eswatini HIV services. Crowdsourcing contests can be effective in collecting messages from men to create more locally relevant communication materials for HIV programs

How does flow in a pipe become turbulent?

The transition to turbulence in pipe flow does not follow the scenario familiar from Rayleigh-Benard or Taylor-Couette flow since the laminar profile is stable against infinitesimal perturbations for all Reynolds numbers. Moreover, even when the flow speed is high enough and the perturbation sufficiently strong such that turbulent flow is established, it can return to the laminar state without any indication of the imminent decay. In this parameter range, the lifetimes of perturbations show a sensitive dependence on initial conditions and an exponential distribution. The turbulence seems to be supported by three-dimensional travelling waves which appear transiently in the flow field. The boundary between laminar and turbulent dynamics is formed by the stable manifold of an invariant chaotic state. We will also discuss the relation between observations in short, periodically continued domains, and the dynamics in fully extended puffs.Comment: for the proceedings of statphys 2

Magnetic fields in supernova remnants and pulsar-wind nebulae

We review the observations of supernova remnants (SNRs) and pulsar-wind nebulae (PWNe) that give information on the strength and orientation of magnetic fields. Radio polarimetry gives the degree of order of magnetic fields, and the orientation of the ordered component. Many young shell supernova remnants show evidence for synchrotron X-ray emission. The spatial analysis of this emission suggests that magnetic fields are amplified by one to two orders of magnitude in strong shocks. Detection of several remnants in TeV gamma rays implies a lower limit on the magnetic-field strength (or a measurement, if the emission process is inverse-Compton upscattering of cosmic microwave background photons). Upper limits to GeV emission similarly provide lower limits on magnetic-field strengths. In the historical shell remnants, lower limits on B range from 25 to 1000 microGauss. Two remnants show variability of synchrotron X-ray emission with a timescale of years. If this timescale is the electron-acceleration or radiative loss timescale, magnetic fields of order 1 mG are also implied. In pulsar-wind nebulae, equipartition arguments and dynamical modeling can be used to infer magnetic-field strengths anywhere from about 5 microGauss to 1 mG. Polarized fractions are considerably higher than in SNRs, ranging to 50 or 60% in some cases; magnetic-field geometries often suggest a toroidal structure around the pulsar, but this is not universal. Viewing-angle effects undoubtedly play a role. MHD models of radio emission in shell SNRs show that different orientations of upstream magnetic field, and different assumptions about electron acceleration, predict different radio morphology. In the remnant of SN 1006, such comparisons imply a magnetic-field orientation connecting the bright limbs, with a non-negligible gradient of its strength across the remnant.Comment: 20 pages, 24 figures; to be published in SpSciRev. Minor wording change in Abstrac