Evaluation of a pilot describing function method applied to the manual control analysis of a large flexible booster

Evaluation of pilot describing function method applied to manual control analysis of large flexible booster in Saturn 5 launch vehicle simulato

Metagenetic analysis of patterns of distribution and diversity of marine meiobenthic eukaryotes

AimMeiofaunal communities that inhabit the marine benthos offer unique opportunities to simultaneously study the macroecology of numerous phyla that exhibit different life-history strategies. Here, we ask: (1) if the macroecology of meiobenthic communities is explained mainly by dispersal constraints or by environmental conditions; and (2) if levels of meiofaunal diversity surpass existing estimates based on morphological taxonomy. LocationUK and mainland European coast. MethodsNext-generation sequencing techniques (NGS; Roche 454 FLX platform) using 18S nuclear small subunit ribosomal DNA (rDNA) gene. Pyrosequences were analysed using AmpliconNoise followed by chimera removal using Perseus. ResultsRarefaction curves revealed that sampling saturation was only reached at 15% of sites, highlighting that the bulk of meiofaunal diversity is yet to be discovered. Overall, 1353 OTUs were recovered and assigned to 23 different phyla. The majority of sampled sites had c. 60-70 unique operational taxonomic units (OTUs) per site, indicating high levels of beta diversity. The environmental parameters that best explained community structure were seawater temperature, geographical distance and sediment size, but most of the variability (R-2=70%-80%) remains unexplained. Main conclusionsHigh percentages of endemic OTUs suggest that meiobenthic community composition is partly niche-driven, as observed in larger organisms, but also shares macroecological features of microorganisms by showing high levels of cosmopolitanism (albeit on a much smaller scale). Meiobenthic communities exhibited patterns of isolation by distance as well as associations between niche, latitude and temperature, indicating that meiobenthic communities result from a combination of niche assembly and dispersal processes. Conversely, isolation-by-distance patterns were not identified in the featured protists, suggesting that animals and protists adhere to radically different macroecological processes, linked to life-history strategies.Natural Environment Research Council (NERC) [NE/E001505/1, NE/F001266/1, MGF-167]; Portuguese Foundation for Science and Technology (FCT) [SFRH/BD/27413/2006, SFRH/BPD/80447/2014]; EPSRC [EP/H003851/1]; BBSRC CASE studentship; Unilever; Biotechnology and Biological Sciences Research Council [987347]; Engineering and Physical Sciences Research Council [EP/H003851/1]; Natural Environment Research Council [NE/F001290/1, NE/F001266/1, NE/E001505/1, NBAF010002]info:eu-repo/semantics/publishedVersio

Jellyfish on the menu: mtDNA assay reveals scyphozoan predation in the Irish Sea

Localized outbreaks of jellyfish, known as blooms, cause a variety of adverse ecological and economic effects. However, fundamental aspects of their ecology remain unknown. Notably, there is scant information on the role jellyfish occupy in food webs: in many ecosystems, few or no predators are known. To identify jellyfish consumers in the Irish Sea, we conducted a molecular gut content assessment of 50 potential predators using cnidarian-specific mtDNA primers and sequencing. We show that jellyfish predation may be more common than previously acknowledged: uncovering many previously unknown jellyfish predators. A substantial proportion of herring and whiting were found to have consumed jellyfish. Rare ingestion was also detected in a variety of other species. Given the phenology of jellyfish in the region, we suggest that the predation was probably targeting juvenile stages of the jellyfish life cycle

How quantitative is metabarcoding: a meta-analytical approach

Metabarcoding has been used in a range of ecological applications such as taxonomic assignment, dietary analysis, and the analysis of environmental DNA. However, after a decade of use in these applications there is little consensus on the extent to which proportions of reads generated corresponds to the original proportions of species in a community. To quantify our current understanding we conducted a structured review and meta‐analysis. The analysis suggests that a weak quantitative relationship may exist between the biomass and sequences produced (slope = 0.52 ±0.34, p<0.01), albeit it with a large degree of uncertainty. None of the tested moderators: sequencing platform type, the number of species used in a trial, or the source of DNA were able to explain the variance. Our current understanding of the factors affecting the quantitative performance of metabarcoding is still limited: additional research is required before metabarcoding can be confidently utilised for quantitative applications. Until then, we advocate the inclusion of mock communities when metabarcoding as this facilitates direct assessment of the quantitative ability of any given study

A Pilot Opinion Study of Lateral Control Requirements for Fighter-Type Aircraft

As part of a continuing NASA program of research on airplane handling qualities, a pilot opinion investigation has been made on the lateral control requirements of fighter aircraft flying in their combat speed range. The investigation was carried out using a stationary flight simulator and a moving flight simulator, and the flight simulator results were supplemented by research tests in actual flight. The flight simulator study was based on the presumption that the pilot rates the roll control of an airplane primarily on a single-degree-of-freedom basis; that is, control of angle of roll about the aircraft body axis being of first importance. From the assumption of a single degree of freedom system it follows that there are two fundamental parameters which govern the airplane roll response, namely the roll damping expressed as a time constant and roll control power in terms of roll acceleration. The simulator study resulted in a criterion in terms of these two parameters which defines satisfactory, unsatisfactory, and unacceptable roll performance from a pilot opinion standpoint. The moving simulator results were substantiated by the in-flight investigation. The derived criterion was compared with the roll performance criterion based upon wing tip helix angle and also with other roll performance concepts which currently influence the roll performance design of military fighter aircraft flying in their combat speed range

Variation in C - reactive protein response according to host and mycobacterial characteristics in active tuberculosis

BACKGROUND: The C - reactive protein (CRP) response is often measured in patients with active tuberculosis (TB) yet little is known about its relationship to clinical features in TB, or whether responses differ between ethnic groups or with different Mycobacterium tuberculosis (M.tb) strain types. We report the relationship between baseline serum CRP prior to treatment and disease characteristics in a metropolitan population with TB resident in a low TB incidence region. METHODS: People treated for TB at four London, UK sites between 2003 and 2014 were assessed and data collected on the following characteristics: baseline CRP level; demographics (ethnicity, gender and age); HIV status; site of TB disease; sputum smear (in pulmonary cases) and culture results. The effect of TB strain-type was also assessed in culture-positive pulmonary cases using VNTR typing data. RESULTS: Three thousands two hundred twenty-two patients were included in the analysis of which 72 % had a baseline CRP at or within 4 weeks prior to starting TB treatment. CRP results were significantly higher in culture positive cases compared to culture negative cases: median 49 mg/L (16-103 mg/L) vs 19 mg/L (IQR 5-72 mg/L), p = <0.001. In those with pulmonary disease, smear positive cases had a higher CRP than smear negative cases: 67 mg/L (31-122 mg/L) vs 24 mg/L (7-72 mg/L), p < 0.001. HIV positive cases had higher baseline CRPs than HIV negative cases: 75 mg/L (26-136 mg/L) vs 37 mg/L (10-88 mg/L), p <0.001. Differing sites of disease were associated with differences in baseline CRP: locations that might be expected to have a high mycobacterial load (e.g. pulmonary disease and disseminated disease) had a significantly higher CRP than those such as skin, lymph node or CNS disease, where the mycobacterial load is typically low in HIV negative subjects. In a multivariable log-scale linear regression model adjusting for host characteristics and M.tb strain type, infection with the East African Indian strain was associated with significantly lower baseline-CRP (fold-change in CRP 0.51 (0.34-0.77), p < 0.01). CONCLUSIONS: Host and mycobacterial factors are strongly associated with baseline CRP response in tuberculosis. This analysis suggests that there are important differences in innate immune response according to ethnicity, Mtb strain type and site of disease. This may reflect differing mycobacterial loads or host immune responses

Sample richness and genetic diversity as drivers of chimera formation in nSSU metagenetic analyses

Eukaryotic diversity in environmental samples is often assessed via PCR-based amplification of nSSU genes. However, estimates of diversity derived from pyrosequencing environmental data sets are often inflated, mainly because of the formation of chimeric sequences during PCR amplification. Chimeras are hybrid products composed of distinct parental sequences that can lead to the misinterpretation of diversity estimates. We have analyzed the effect of sample richness, evenness and phylogenetic diversity on the formation of chimeras using a nSSU data set derived from 454 Roche pyrosequencing of replicated, large control pools of closely and distantly related nematode mock communities, of known intragenomic identity and richness. To further investigate how chimeric molecules are formed, the nSSU gene secondary structure was analyzed in several individuals. For the first time in eukaryotes, chimera formation proved to be higher in both richer and more genetically diverse samples, thus providing a novel perspective of chimera formation in pyrosequenced environmental data sets. Findings contribute to a better understanding of the nature and mechanisms involved in chimera formation during PCR amplification of environmentally derived DNA. Moreover, given the similarities between biodiversity analyses using amplicon sequencing and those used to assess genomic variation, our findings have potential broad application for identifying genetic variation in homologous loci or multigene families in general

Long term drought and warming alter soil bacterial and fungal communities in an upland heathland

The response of soil microbial communities to a changing climate will impact global biogeochemical cycles, potentially leading to positive and negative feedbacks. However, our understanding of how soil microbial communities respond to climate change and the implications of these changes for future soil function is limited. Here, we assess the response of soil bacterial and fungal communities to long-term experimental climate change in a heathland organo-mineral soil. We analysed microbial communities using Illumina sequencing of the 16S rRNA gene and ITS2 region at two depths, from plots undergoing 4 and 18 years of in situ summer drought or warming. We also assessed the colonisation of Calluna vulgaris roots by ericoid and dark septate endophytic (DSE) fungi using microscopy after 16 years of climate treatment. We found significant changes in both the bacterial and fungal communities in response to drought and warming, likely mediated by changes in soil pH and electrical conductivity. Changes in the microbial communities were more pronounced after a longer period of climate manipulation. Additionally, the subsoil communities of the long-term warmed plots became similar to the topsoil. Ericoid mycorrhizal colonisation decreased with depth while DSEs increased; however, these trends with depth were removed by warming. We largely ascribe the observed changes in microbial communities to shifts in plant cover and subsequent feedback on soil physicochemical properties, especially pH. Our results demonstrate the importance of considering changes in soil microbial responses to climate change across different soil depths and after extended periods of time