The component structure of dense random subgraphs of the hypercube

Given $p \in (0,1)$, we let $Q_p= Q_p^d$ be the random subgraph of the $d$-dimensional hypercube $Q^d$ where edges are present independently with probability $p$. It is well known that, as $d \rightarrow \infty$, if $p>\frac12$ then with high probability $Q_p$ is connected; and if $p<\frac12$ then with high probability $Q_p$ consists of one giant component together with many smaller components which form the `fragment'. Here we fix $p \in (0,\frac12)$, and investigate the fragment, and how it sits inside the hypercube. In particular we give asymptotic estimates for the mean numbers of components in the fragment of each size, and describe their asymptotic distributions and indeed their joint distribution, much extending earlier work of Weber

SciTokens: Capability-Based Secure Access to Remote Scientific Data

The management of security credentials (e.g., passwords, secret keys) for computational science workflows is a burden for scientists and information security officers. Problems with credentials (e.g., expiration, privilege mismatch) cause workflows to fail to fetch needed input data or store valuable scientific results, distracting scientists from their research by requiring them to diagnose the problems, re-run their computations, and wait longer for their results. In this paper, we introduce SciTokens, open source software to help scientists manage their security credentials more reliably and securely. We describe the SciTokens system architecture, design, and implementation addressing use cases from the Laser Interferometer Gravitational-Wave Observatory (LIGO) Scientific Collaboration and the Large Synoptic Survey Telescope (LSST) projects. We also present our integration with widely-used software that supports distributed scientific computing, including HTCondor, CVMFS, and XrootD. SciTokens uses IETF-standard OAuth tokens for capability-based secure access to remote scientific data. The access tokens convey the specific authorizations needed by the workflows, rather than general-purpose authentication impersonation credentials, to address the risks of scientific workflows running on distributed infrastructure including NSF resources (e.g., LIGO Data Grid, Open Science Grid, XSEDE) and public clouds (e.g., Amazon Web Services, Google Cloud, Microsoft Azure). By improving the interoperability and security of scientific workflows, SciTokens 1) enables use of distributed computing for scientific domains that require greater data protection and 2) enables use of more widely distributed computing resources by reducing the risk of credential abuse on remote systems.Comment: 8 pages, 6 figures, PEARC '18: Practice and Experience in Advanced Research Computing, July 22--26, 2018, Pittsburgh, PA, US

Towards in-process x-ray CT for dimensional metrology

X-ray computed tomography (CT) offers significant potential as a metrological tool, given the wealth of internal and external data that can be captured, much of which is inaccessible to conventional optical and tactile coordinate measurement machines (CMM). Typical lab-based CT can take upwards of 30 min to produce a 3D model of an object, making it unsuitable for volume production inspection applications. Recently a new generation of real time tomography (RTT) x-ray CT has been developed for airport baggage inspections, utilising novel electronically switched x-ray sources instead of a rotating gantry. This enables bags to be scanned in a few seconds and 3D volume images produced in almost real time for qualitative assessment to identify potential threats. Such systems are able to scan objects as large as 600 mm in diameter at 500 mm s−1. The current voxel size of such a system is approximately 1 mm—much larger than lab-based CT, but with significantly faster scan times is an attractive prospect to explore. This paper will examine the potential of such systems for real time metrological inspection of additively manufactured parts. The measurement accuracy of the Rapiscan RTT110, an RTT airport baggage scanner, is evaluated by comparison to measurements from a metrologically confirmed CMM and those achieved by conventional lab-CT. It was found to produce an average absolute error of 0.18 mm that may already have some applications in the manufacturing line. While this is expectedly a greater error than lab-based CT, a number of adjustments are suggested that could improve resolution, making the technology viable for a broader range of in-line quality inspection applications, including cast and additively manufactured parts

Changes in physical activity following total hip or knee arthroplasty: a matched case-control study from the EPIC-Norfolk cohort

Objective: To assess self-reported physical activity changes pre- compared to post-operatively in patients undergoing total hip or knee arthroplasty, and to compare this to an age- and gender-matched cohort of people who have not undergone arthroplasty.  Design: Population-based prospective cohort study.  Setting: Norfolk, UK  Subjects: People who had undergone hip or knee arthroplasty, compared to an age- and gender-matched non-arthroplasty cohort.  Intervention: Primary total hip or knee arthroplasty.  Main measures: Physical activity, measured using the EPIC Physical Activity Questionnaire (EPAQ2).  Results: 400 people from the EPIC-Norfolk community cohort were identified who had undergone hip or knee arthroplasty. 767 people were identified to form an age- and gender-matched non-arthroplasty cohort. Mean post-operative follow-up was 43 months post-total hip and 41 months post-total knee arthroplasty. There was a statistically significant reduction from pre- to post-arthroplasty in the number of flights of stairs climbed weekly (hip: mean difference (MD): 6.8; p<0.01; knee: MD: 10.2; p<0.01); duration of walking (hip: MD: 1.4 hours/week; p=0.02; knee: MD: 2.2 hours/week; p<0.01) and duration of total recreational activity (hip: MD: 1.1 hours/week; p=0.02). Compared to the non-arthroplasty cohort, duration of physical activity was lower post-total hip arthroplasty (MD: 1.8 hours/week; p=0.01). The number of flights of stairs climbed weekly (MD: 12.0; p<0.01), total recreational activity (MD: 1.7 hours/week; p=0.04) and physical activity energy expenditure (MD: 5.7 Mets-hours/week; p=0.05) was lower for people post-total knee arthroplasty compared to the matched controls.  Conclusions: Physical activity did not increase, and in instances decreased, following total hip or knee arthroplasty

Fab@Home Model 3: A More Robust, Cost Effective and Accessible Open Hardware Fabrication Platform

Solid Freeform Fabrication is transitioning from an industrial process and research endeavor towards a ubiquitous technology in the lives of every designer and innovator. In order to speed this transition Fab@Home Model 3 was created with the goal of expanding the user base of SFF technology by lowering the skill and price barriers to entry while enabling technology developers to leverage their core competencies more efficiently. The result is a device, which is modular with respect to tool heads, fabrication processes, and electronics controls, costs under $1000, and requires only a simple tool set to assemble.Mechanical Engineerin

Development of a thermal excitation source used in an active thermographic UAV platform

This work aims to address the effectiveness and challenges of using active infrared thermography (IRT) onboard an unmanned aerial vehicle (UAV) platform. The work seeks to assess the performance of small low-powered forms of excitation which are suitable for active thermography and the ability to locate subsurface defects on composites. An excitation source in multiple 250 W lamps is mounted onto a UAV and is solely battery powered with a remote trigger to power cycle them. Multiple experiments address the interference from the UAV whilst performing an active IRT inspection. The optimal distances and time required for a UAV inspection using IRT are calculated. Multiple signal processing techniques are used to analyse the composites which help locate the sub-surface defects. It was observed that a UAV can successfully carry the required sensors and equipment for an Active thermographic NDT inspection which can provide access to difficult areas. Most active thermographic inspection equipment is large, heavy, and expensive. Furthermore, using such equipment for the inspection of complex structures is time-consuming. For example, a cherry picker would be required to inspect the tail of an aircraft. This solution looks to assist engineers in inspecting complex composite structures and could potentially significantly reduce the time and cost of a routine inspection.Engineering and Physical Sciences Research Council (EPSRC): EP/N509450/1 and Innovate UK: 105625

Safety and Immunogenicity of an AMA-1 Malaria Vaccine in Malian Adults: Results of a Phase 1 Randomized Controlled Trial

The objective was to evaluate the safety, reactogenicity and immunogenicity of the AMA-1-based blood-stage malaria vaccine FMP2.1/AS02A in adults exposed to seasonal malaria.A phase 1 double blind randomized controlled dose escalation trial was conducted in Bandiagara, Mali, West Africa, a rural town with intense seasonal transmission of Plasmodium falciparum malaria. The malaria vaccine FMP2.1/AS02A is a recombinant protein (FMP2.1) based on apical membrane antigen-1 (AMA-1) from the 3D7 clone of P. falciparum, adjuvanted with AS02A. The comparator vaccine was a cell-culture rabies virus vaccine (RabAvert). Sixty healthy, malaria-experienced adults aged 18-55 y were recruited into 2 cohorts and randomized to receive either a half dose or full dose of the malaria vaccine (FMP2.1 25 microg/AS02A 0.25 mL or FMP2.1 50 microg/AS02A 0.5 mL) or rabies vaccine given in 3 doses at 0, 1 and 2 mo, and were followed for 1 y. Solicited symptoms were assessed for 7 d and unsolicited symptoms for 30 d after each vaccination. Serious adverse events were assessed throughout the study. Titers of anti-AMA-1 antibodies were measured by ELISA and P. falciparum growth inhibition assays were performed on sera collected at pre- and post-vaccination time points. Transient local pain and swelling were common and more frequent in both malaria vaccine dosage groups than in the comparator group. Anti-AMA-1 antibodies increased significantly in both malaria vaccine groups, peaking at nearly 5-fold and more than 6-fold higher than baseline in the half-dose and full-dose groups, respectively.The FMP2.1/AS02A vaccine had a good safety profile, was well-tolerated, and was highly immunogenic in malaria-exposed adults. This malaria vaccine is being evaluated in Phase 1 and 2 trials in children at this site