Vehicle and mission design of a future small payload launcher

This paper presents the conceptual design and performance analysis of a partially reusable space launch vehicle for small payloads. The system uses a multi-stage vehicle with rocket engines, with a reusable first stage capable of glided or powered flight, and expendable upper stage(s) to inject a 500 kg payload in different low Earth orbits. The space access vehicle is designed to be air-launched from a modified aircraft carrier. The aim of the system design is to develop a commercially viable launch system for near-term operation, thus emphasis is placed on the efficient use of high TRL technologies. The vehicle design are analysed using a multi-disciplinary design optimisation approach to evaluate the performance, operational capabilities and design trade-offs

Are the Mascarene frog (Ptychadena mascareniensis) and Brahminy blind snake (Indotyphlops braminus) really alien species in the Seychelles?

This is an accepted manuscript of an article published by the British Herpetological Society in the Herpetological Bulletin on 30/09/2020. The accepted version of the publication may differ from the final published version

Endemic, endangered, and evolutionarily significant: Cryptic lineages in Seychelles’ frogs

Cryptic diversity that corresponds with island origin has been previously reported in the endemic, geographically restricted sooglossid frogs of the Seychelles archipelago. The evolutionary pattern has not been fully explored, and given current amphibian declines and the increased extinction risk faced by island species, we sought to identify evolutionarily significant units (ESUs) to address conservation concerns for these highly threatened anurans. We obtained genetic data for two mitochondrial (mtDNA) and four nuclear (nuDNA) genes from all known populations of sooglossid frog (the islands of Mahé, Praslin, and Silhouette) to perform phylogenetic analyses and construct nuDNA haplotype networks. Bayesian and maximum likelihood analyses of mtDNA support monophyly and molecular differentiation of populations in all species that occur on multiple islands. Haplotype networks using statistical parsimony revealed multiple high-frequency haplotypes shared between islands and taxa, in addition to numerous geographically distinct (island-specific) haplotypes for each species. We consider each island-specific population of sooglossid frog as an ESU and advise conservation managers to do likewise. Furthermore, our results identify each island lineage as a candidate species, evidence for which is supported by Bayesian Poisson Tree Processes analyses of mtDNA, and independent analyses of mtDNA and nuDNA using the multispecies coalescent. Our findings add to the growing understanding of the biogeography and hidden diversity within this globally important region

Robust multi-objective optimisation of a descent guidance strategy for a TSTO spaceplane

This paper presents a novel method for multi-objective optimisation under uncertainty developed to study a range of mission trade-offs, and the impact of uncertainties on the evaluation of launch system mission designs. A memetic multi-objective optimisation algorithm, MODHOC, which combines the Direct Finite Elements transcription method with Multi Agent Collaborative Search, is extended to account for model uncertainties. An Unscented Transformation is used to capture the first two statistical moments of the quantities of interest. A quantification model of the uncertainty was developed for the atmospheric model parameters. An optimisation under uncertainty was run for the design of descent trajectories for the Orbital-500R, a commercial semi-reusable, two-stage launch system under development by Orbital Access Lt

Rumors, False Flags, and Digital Vigilantes: Misinformation on Twitter after the 2013 Boston Marathon Bombing

The Boston Marathon bombing story unfolded on every possible carrier of information available in the spring of 2013, including Twitter. As information spread, it was filled with rumors (unsubstantiated information), and many of these rumors contained misinformation. Earlier studies have suggested that crowdsourced information flows can correct misinformation, and our research investigates this proposition. This exploratory research examines three rumors, later demonstrated to be false, that circulated on Twitter in the aftermath of the bombings. Our findings suggest that corrections to the misinformation emerge but are muted compared with the propagation of the misinformation. The similarities and differences we observe in the patterns of the misinformation and corrections contained within the stream over the days that followed the attacks suggest directions for possible research strategies to automatically detect misinformation.publishedye

Aerodynamic Database Development for a Future Reusable Space Launch Vehicle, The Orbital 500R

No abstract available

Robust Multi-object Optimisation of a Descent Guidance Strategy for a TSTO Spaceplane

No abstract available

Rural libraries implementing walking groups or walking groups plus civic engagement for walkability in rural communities: a comparative effectiveness trial study protocol

Abstract Background Rural residents generally lack adequate physical activity to benefit health and reduce disparities in chronic diseases, such as cardiovascular disease and certain cancers. The Socioecological Model describes physical activity as involving a dynamic and reciprocal interaction between individual, social, and community factors. Community group-based walking programs and civic engagement interventions aimed at enhancing physical activity have been successful in rural communities but have not targeted all three socioecological levels. Public libraries can act as innovative public health partners in rural communities. However, challenges remain because rural libraries often lack the capacity to implement evidence-based health promotion programming. The goals of this study are (1) build the capacity for rural libraries to implement evidence-based health promotion programs, (2) compare changes in physical activity between a group-based walking program and a combined group-based walking and civic engagement program with rural residents, and (3) conduct an implementation evaluation. Methods We will conduct a comparative effectiveness study of a group-based walking (standard approach) versus a group-based walking plus civic engagement program (combined approach) aimed at enhancing walkability to increase physical activity among rural adults. Key mediators between the program effects and change in outcomes will also be identified. Finally, we will evaluate program implementation, conduct a cost effectiveness evaluation, and use a positive deviance analysis to understand experiences of high and low changers on key outcomes. Twenty towns will be matched and randomized to one of the two conditions and our aim is to enroll a total of 350–400 rural residents (15–20 per town). Study outcomes will be assessed at baseline, and 6, 12, and 24 months. Discussion This study will build the capacity of rural libraries to implement evidence-based walking programs as well as other health promotion programs in their communities. The study results will answer questions regarding the relative effectiveness and cost effectiveness of two multilevel physical activity interventions targeting rural communities. We will learn what works and how these multilevel interventions can be implemented in rural populations. Trial Registration ClinicalTrials.gov Identifier: NCT05677906

Molecular phylogenetics of sub-Saharan African natricine snakes, and the biogeographic origins of the Seychelles endemic Lycognathophis seychellensis

This is an accepted manuscript of an article published by Elsevier in Molecular Phylogenetics and Evolution, available online: https://doi.org/10.1016/j.ympev.2021.107152 The accepted version of the publication may differ from the final published version.Phylogenetic relationships of sub-Saharan African natricine snakes are understudied and poorly understood, which in turn has precluded analyses of the historical biogeography of the Seychelles endemic Lycognathophis seychellensis. We inferred the phylogenetic relationships of Seychelles and mainland sub-Saharan natricines by analysing a multilocus DNA sequence dataset for three mitochondrial (mt) and four nuclear (nu) genes. The mainland sub-Saharan natricines and L. seychellensis comprise a well-supported clade. Two maximally supported sets of relationships within this clade are (Limnophis,Natriciteres) and (Afronatrix,(Hydraethiops,Helophis)). The relationships of L. seychellensis with respect to these two lineages are not clearly resolved by analysing concatenated mt and nu data. Analysed separately, nu data best support a sister relationship of L. seychellensis with (Afronatrix,(Hydraethiops,Helophis)) and mt data best support a sister relationship with all mainland sub-Saharan natricines. Methods designed to cope with incomplete lineage sorting strongly favour the former hypothesis. Genetic variation among up to 33 L. seychellensis from five Seychelles islands is low. Fossil calibrated divergence time estimates support an overseas dispersal of the L. seychellensis lineage to the Seychelles from mainland Africa ca. 43–25 Ma, rather than this taxon being a Gondwanan relic.VD was funded by EU Marie Skłodowska-Curie Fellowship 751567. STM was funded by an NHM-UCL IMPACT PhD studentship. STM and JL each received awards from the Systematics Research Fund of the Systematics Association and Linnean Society of London, and the Mohammed bin Zayed Conservation Fund (Projects 172515128 and 162513749). Seychelles research was also funded by the BBSRC’s SynTax scheme (awarded to M. Wilkinson, JJD and DJG). VG was supported by the IVB CAS institutional support (RVO: 68081766), and the Ministry of Culture of the Czech Republic (DKRVO 2019–2023/6.VII.c, National Museum, 00023272). TDB’s fieldwork was funded by the Royal Geographical Society, and Golder Associates. RGK received EU Marie Skłodowska-Curie Fellowship (PIIF-GA-2013-625870). This work was also supported by Darwin Initiative grant 19-002 (to J.J. Groombridge and colleagues).Published versio