Special Semaphore Scheme for UHF Spacecraft Communications

A semaphore scheme has been devised to satisfy a requirement to enable ultrahigh- frequency (UHF) radio communication between a spacecraft descending from orbit to a landing on Mars and a spacecraft, in orbit about Mars, that relays communications between Earth and the lander spacecraft. There are also two subsidiary requirements: (1) to use UHF transceivers, built and qualified for operation aboard the spacecraft that operate with residual-carrier binary phase-shift-keying (BPSK) modulation at a selectable data rate of 8, 32, 128, or 256 kb/s; and (2) to enable low-rate signaling even when received signals become so weak as to prevent communication at the minimum BPSK rate of 8 kHz. The scheme involves exploitation of Manchester encoding, which is used in conjunction with residual-carrier modulation to aid the carrier-tracking loop. By choosing various sequences of 1s, 0s, or 1s alternating with 0s to be fed to the residual-carrier modulator, one would cause the modulator to generate sidebands at a fundamental frequency of 4 or 8 kHz and harmonics thereof. These sidebands would constitute the desired semaphores. In reception, the semaphores would be detected by a software demodulator

2H and 27Al Solid-State NMR Study of the Local Environments in Al-Doped 2-Line Ferrihydrite, Goethite, and Lepidocrocite.

Although substitution of aluminum into iron oxides and oxyhydroxides has been extensively studied, it is difficult to obtain accurate incorporation levels. Assessing the distribution of dopants within these materials has proven especially challenging because bulk analytical techniques cannot typically determine whether dopants are substituted directly into the bulk iron oxide or oxyhydroxide phase or if they form separate, minor phase impurities. These differences have important implications for the chemistry of these iron-containing materials, which are ubiquitous in the environment. In this work, 27Al and 2H NMR experiments are performed on series of Al-substituted goethite, lepidocrocite, and 2-line ferrihydrite in order to develop an NMR method to track Al substitution. The extent of Al substitution into the structural frameworks of each compound is quantified by comparing quantitative 27Al MAS NMR results with those from elemental analysis. Magnetic measurements are performed for the goethite series to compare with NMR measurements. Static 27Al spin-echo mapping experiments are used to probe the local environments around the Al substituents, providing clear evidence that they are incorporated into the bulk iron phases. Predictions of the 2H and 27Al NMR hyperfine contact shifts in Al-doped goethite and lepidocrocite, obtained from a combined first-principles and empirical magnetic scaling approach, give further insight into the distribution of the dopants within these phases.J.K., A.J.I., D.M. and N.P. were supported by an NSF grant collaborative research grant in chemistry CHE0714183. An allocation of time upon the NANO computer cluster at the Center for Functional Nanomaterials, Brookhaven National Laboratory, U.S.A., which is supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886 is also acknowledged. D.S.M. and C.P.G. thank the EPSRC and the EU-ERC for support.This is the final version of the article. It first appeared from the American Chemical Society via http://dx.doi.org/10.1021/acs.chemmater.5b0085

Cosmogenic dating of fluvial terraces in the Sorbas Basin, SE Spain

Long term fluvial incision spanning the Late Cenozoic is recorded in many fluvial systems around the world by terrace landform sequences. The incision manifests itself as inset sequences of river terraces which form terrace staircases. The timing of the onset of incision and the rate incision then proceeds at is poorly constrained due to the difficulties in dating river terraces. This study applies the technique of cosmogenic exposure dating to a fluvial staircase, for the first time, in the Sorbas Basin, SE Spain. Cosmogenic exposure dating allows the timing of abandonment of the fluvial terraces to be calculated therefore recording periods of incision. Cosmogenic exposure dating and the profile method offer a viable way to date Early and Middle Pleistocene terrace deposits. Combined exposure and burial age’s approaches using paired isotopes allow for insights into terrace aggradation and fluvial incision timing. The fluvial deposits in the Sorbas Basin record 1.0 Ma of incision by the Río Aguas. The timing of aggradation and incision in the Sorbas basin has been linked to both tectonics and climate cycles. Terrace aggradation took place in glacial and interglacial periods. The abandonment of terrace surfaces occurred both at warming transitions and in interglacial periods. New uplift rates calculated for the Pleistocene fluvial system suggest that tectonic activity in the Sorbas Basin has been episodic. The south margin and centre of the Sorbas Basin has uplifted at a faster rate than the northern margin impacting on the rates of incision taking place in the fluvial systems. Overall tectonic uplift has increased the fluvial system sensitivity to climatic variations.NER

Defining the microbial transcriptional response to colitis through integrated host and microbiome profiling

The gut microbiome is significantly altered in inflammatory bowel diseases, but the basis of these changes is not well understood. We have combined metagenomic and metatranscriptomic profiling of the gut microbiome to assess modifications to both bacterial community structure and transcriptional activity in a mouse model of colitis. By using transcriptomic analysis of colonic tissue and luminal RNA derived from the host, we have also characterised how host transcription relates to the microbial transcriptional response in inflammation. In colitis, increased abundance and transcription of diverse microbial gene families involved in responses to nutrient deprivation, antimicrobial peptide production and oxidative stress support an adaptation of multiple commensal genera to withstand a diverse set of environmental stressors in the inflammatory environment. These data are supported by a transcriptional signature of activated macrophages and granulocytes in the gut lumen during colitis, a signature that includes the transcription of the key antimicrobial genes S100a8 and S100a9 (calprotectin). Genes involved in microbial resistance to oxidative stress, including Dps/ferritin, Fe-dependent peroxidase and glutathione S-transferase were identified as changing to a greater extent at the level of transcription than would be predicted by DNA abundance changes, implicating a role for increased oxygen tension and/or host-derived reactive oxygen species in driving transcriptional changes in commensal microbes

Exploring factors that influence the spread and sustainability of a dysphagia innovation: an instrumental case study

Background: Swallowing difficulties challenge patient safety due to the increased risk of malnutrition, dehydration and aspiration pneumonia. A theoretically driven study was undertaken to examine the spread and sustainability of a locally developed innovation that involved using the Inter-Professional Dysphagia Framework to structure education for the workforce. A conceptual framework with 3 spread strategies (hierarchical control, participatory adaptation and facilitated evolution) was blended with a processual approach to sustaining organisational change. The aim was to understand the processes, mechanism and outcomes associated with the spread and sustainability of this safety initiative. Methods: An instrumental case study, prospectively tracked a dysphagia innovation for 34 months (April 2011 to January 2014) in a large health care organisation in England. A train-the-trainer intervention (as participatory adaptation) was deployed on care pathways for stroke and fractured neck of femur. Data were collected at the organisational and clinical level through interviews (n = 30) and document review. The coding frame combined the processual approach with the spread mechanisms. Pre-determined outcomes included the number of staff trained about dysphagia and impact related to changes in practice. Results: The features and processes associated with hierarchical control and participatory adaptation were identified. Leadership, critical junctures, temporality and making the innovation routine were aspects of hierarchical control. Participatory adaptation was evident on the care pathways through stakeholder responses, workload and resource pressures. Six of the 25 ward based trainers cascaded the dysphagia training. The expected outcomes were achieved when the top-down mandate (hierarchical control) was supplemented by local engagement and support (participatory adaptation). Conclusions: Frameworks for spread and sustainability were combined to create a ‘small theory’ that described the interventions, the processes and desired outcomes a priori. This novel methodological approach confirmed what is known about spread and sustainability, highlighted the particularity of change and offered new insights into the factors associated with hierarchical control and participatory adaptation. The findings illustrate the dualities of organisational change as universal and context specific; as particular and amendable to theoretical generalisation. Appreciating these dualities may contribute to understanding why many innovations fail to become routine

Motion in the solid state studied by NMR and extended time scale MD simulation

The ability to characterise dynamic processes in the solid state is crucial to our understanding of many important materials. Nuclear magnetic resonance (NMR) and molecular dynamics (MD) simulations are two, highly complementary techniques that can be used in this pursuit, with NMR providing robust measurements of kinetic parameters across a large range of time-scales while MD can give insight into the form that the motion takes. The aim of the work presented in this thesis has been to demonstrate the extent of this complementarity by combining both techniques to investigate interesting systems, and also to expand upon it by implementing extended time scale MD methods that allow slower dynamic processes to be accurately simulated. Atomistic simulations of a urea inclusion compound and of octafluoronaphthalene (OFN), a molecular solid, illustrate the dynamic range and complicated nature of motions that can be present in solid phases of matter, and the inherent difficulty of modeling them without explicit knowledge of their form. Whilst the MD simulation can provide this information, there are computational limits to the range of time-scales it can conventionally access. The OFN system provides an example of this limit, as slow molecular motions observed by NMR experiments are shown to be inaccessible to long, ambient temperature simulations. To combat this deficiency, the metadynamics extended time scale technique has been implemented, allowing rare dynamic events to be observed in very short simulations, and the effects of complex correlated motions to be explored

Host pathogen interactions in relation to management of light leaf spot disease (caused by Pyrenopeziza brassicae) on Brassica species

Light leaf spot, caused by Pyrenopeziza brassicae, is currently the most damaging disease problem in oilseed rape in the UK. According to recent survey data, the severity of epidemics has increased progressively across the UK, with current yield losses of up to £160M per annum in England and more severe epidemics in Scotland. Light leaf spot is a polycyclic disease with primary inoculum consisting of air-borne ascospores produced on diseased debris from the previous cropping season. Splash-dispersed conidia produced on diseased leaves are the main component of the secondary inoculum. P. brassicae is also able to infect and cause considerable yield losses on vegetable brassicas, especially Brussels sprouts. There may be spread of light leaf spot among different brassica species. Since they have a wide host range, Pyrenopeziza brassicae populations are likely to have considerable genetic diversity and there is evidence suggesting population variations between different regions, which need further study. Available disease-management tools are not sufficient to provide adequate control of the disease. There is a need to identify new sources of resistance, which can be integrated with fungicide applications to achieve sustainable management of light leaf spot. Several major resistance genes and quantitative trait loci have been identified in previous studies, but rapid improvements in the understanding of molecular mechanisms underpinning B. napus – P. brassicae interactions can be expected through exploitation of novel genetic and genomic information for brassicas and extracellular fungal pathogens.Peer reviewe

The Longitudinal Characteristics of Three Slender "Mild Ogee" Wings at Mach Numbers from 0.4 to 2.0

Wind tunnel measurements of lift, pitching moment and drag on one plane and two cambered wings of "mild ogee" planfom (p = 8/15) are reported. These measurements are supplemented by vapour screen and oil flow observations. The wings were designed by slender wing theory for attached flow along the leading-edge at particular values of lift and pitching moment. The design and measured attachment conditions agreed fairly well. The non-linear lift developed could be related with the type of vortex development above the attachment incidence