57 research outputs found

    Gut microbiota composition is associated with environmental landscape in honey bees.

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    There is growing recognition that the gut microbial community regulates a wide variety of important functions in its animal hosts, including host health. However, the complex interactions between gut microbes and environment are still unclear. Honey bees are ecologically and economically important pollinators that host a core gut microbial community that is thought to be constant across populations. Here, we examined whether the composition of the gut microbial community of honey bees is affected by the environmental landscape the bees are exposed to. We placed honey bee colonies reared under identical conditions in two main landscape types for 6 weeks: either oilseed rape farmland or agricultural farmland distant to fields of flowering oilseed rape. The gut bacterial communities of adult bees from the colonies were then characterized and compared based on amplicon sequencing of the 16S rRNA gene. While previous studies have delineated a characteristic core set of bacteria inhabiting the honey bee gut, our results suggest that the broad environment that bees are exposed to has some influence on the relative abundance of some members of that microbial community. This includes known dominant taxa thought to have functions in nutrition and health. Our results provide evidence for an influence of landscape exposure on honey bee microbial community and highlight the potential effect of exposure to different environmental parameters, such as forage type and neonicotinoid pesticides, on key honey bee gut bacteria. This work emphasizes the complexity of the relationship between the host, its gut bacteria, and the environment and identifies target microbial taxa for functional analyses

    Block-Transitive Designs in Affine Spaces

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    This paper deals with block-transitive tt-(v,k,λ)(v,k,\lambda) designs in affine spaces for large tt, with a focus on the important index λ=1\lambda=1 case. We prove that there are no non-trivial 5-(v,k,1)(v,k,1) designs admitting a block-transitive group of automorphisms that is of affine type. Moreover, we show that the corresponding non-existence result holds for 4-(v,k,1)(v,k,1) designs, except possibly when the group is one-dimensional affine. Our approach involves a consideration of the finite 2-homogeneous affine permutation groups.Comment: 10 pages; to appear in: "Designs, Codes and Cryptography

    Safety and efficacy of diaphragm pacing in patients with respiratory insufficiency due to amyotrophic lateral sclerosis (DiPALS): a multicentre, open-label, randomised controlled trial

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    Background: Non-invasive ventilation is part of the standard of care for treatment of respiratory failure in patients with amyotrophic lateral sclerosis (ALS). The NeuRx RA/4 Diaphragm Pacing System has received Humanitarian Device Exemption approval from the US Food and Drug Administration for treatment of respiratory failure in patients with ALS. We aimed to establish the safety and efficacy of diaphragm pacing with this system in patients with respiratory muscle weakness due to ALS. Methods: We undertook a multicentre, open-label, randomised controlled trial at seven specialist ALS and respiratory centres in the UK. Eligible participants were aged 18 years or older with laboratory supported probable, clinically probable, or clinically definite ALS; stable riluzole treatment for at least 30 days; and respiratory insufficiency. We randomly assigned participants (1:1), via a centralised web-based randomisation system with minimisation that balanced patients for age, sex, forced vital capacity, and bulbar function, to receive either non-invasive ventilation plus pacing with the NeuRx RA/4 Diaphragm Pacing System or non-invasive ventilation alone. Patients, carers, and outcome assessors were not masked to treatment allocation. The primary outcome was overall survival, defined as the time from randomisation to death from any cause. Analysis was by intention to treat. This trial is registered, ISRCTN number 53817913. Findings: Between Dec 5, 2011, and Dec 18, 2013, we randomly assigned 74 participants to receive either non-invasive ventilation alone (n=37) or non-invasive ventilation plus diaphragm pacing (n=37). On Dec 18, 2013, the Data Monitoring and Ethics Committee (DMEC) recommended suspension of recruitment on the basis of overall survival figures. Randomly assigned participants continued as per the study protocol until June 23, 2014, when the DMEC advised discontinuation of pacing in all patients. Follow-up assessments continued until the planned end of the study in December, 2014. Survival was shorter in the non-invasive ventilation plus pacing group than in the non-invasive ventilation alone group (median 11·0 months [95% CI 8·3-13·6] vs 22·5 months [13·6-not reached]; adjusted hazard ratio 2·27, 95% CI 1·22-4·25; p=0·009). 28 (76%) patients died in the pacing group and 19 (51%) patients died in the non-invasive ventilation alone group. We recorded 162 adverse events (5·9 events per person-year) in the pacing group, of which 46 events were serious, compared with 81 events (2·5 events per person-year) in the non-invasive ventilation alone group, of which 31 events were serious. Interpretation: Addition of diaphragm pacing to standard care with non-invasive ventilation was associated with decreased survival in patients with ALS. Our results suggest that diaphragmatic pacing should not be used as a routine treatment for patients with ALS in respiratory failure

    An infinite class of 5-designs

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    Intelligent system for vibroacoustic and shock environment predictions

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    High intensity noise generation for extremely large reverberant room test applications

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    A recent operational need for the development of a large (101,000 ft 3) reverberant acoustic chamber at the Space Power Facility of NASA Glenn Research Center's Plum Brook Station with the requirement of generating sound pressure levels (SPL) as high as 163 dB has resulted in the need to re-examine the generation of noise in reverberant rooms. Early in the design stage, it was realized that the acoustic power level capability (10-30 kW) of conventional electrodynamic air modulators, such as those supplied by the Wyle Corporation, would be required in unprecedented numbers to meet the test spectra requirements. The design team then turned to a lesser known modulator, the hydraulically driven air modulator supplied by the Team Corporation, which has 150-200 kW acoustic power capability. The advantage to the project was a significant reduction in the number of modulators required to meet the requirements. However, since only limited characterization of Team modulator's performance has been reported, a test program was required in order to mitigate the risk of the design of the RATF. Aiolos Corporation, which is responsible for the acoustic design of the RATF, and the Institute of Aerospace Research (IAR) of the National Research Council of Canada (NRC), entered into a collaborative agreement with the objective of characterizing, optimizing and investigating the controllability of the Team modulators. The test program was performed at the NRC-IAR reverberant chamber, a 19,000 ft 3 facility located in Ottawa, Ontario, Canada. The current paper provides details of the principle of operation of the Team modulators, including their servo control loops and provides of a summary of the characterization and controllability test program.Peer reviewed: YesNRC publication: Ye
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