1,225 research outputs found

    Rotor blade construction for circulation control aircraft

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    A circulation control aircraft rotor blade having a spanwise Coanda surface 16 and a plurality of spanwise extending flexible composite material panels 18 cooperating with the surface to define slots for the discharge of compressed air from within the blade with each panel having first flexure means 60 associated with screw adjustments 36 for establishing a slot opening preload and second flexure means 62 associated with screw adjustments 38 for establishing a slot maximum opening

    On Reflection Subgroups of Finite Coxeter Groups

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    Let WW be a finite Coxeter group. We classify the reflection subgroups of WW up to conjugacy and give necessary and sufficient conditions for the map that assigns to a reflection subgroup RR of WW the conjugacy class of its Coxeter elements to be injective, up to conjugacy.Comment: 17 pages; final version, to appear in Comm. Algebr

    Periosteal Osteosarcoma: A Review of 17 Cases with Mean Follow-up of 52 Months

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    Purpose: Periosteal osteosarcomas are rare cartilage-rich bone tumours characterized by a juxtacortical eccentric position and are normally regarded oncologically as of intermediate to high grade.Their low incidence is mirrored by a small number of reported cases in the world literature. While there is general agreement that wide surgical excision is required, there is a paucity of evidence regarding adjuvant therapy. Previous reports have not indicated any consistent approach to this to allow appraisal

    Enhancement of anti-DIII antibodies by the C3d derivative P28 results in lower viral titers and augments protection in mice

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    Antibodies generated against West Nile virus (WNV) during infection are essential for controlling dissemination. Recent studies have demonstrated that epitopes in all three domains of the flavivirus envelope protein (E) are targets for neutralizing antibodies, with determinants in domain III (DIII) eliciting antibodies with strong inhibitory properties. In order to increase the magnitude and quality of the antibody response against the WNV E protein, DNA vaccines with derivatives of the WNV E gene (full length E, truncated E, or DIII region, some in the context of the pre-membrane [prM] gene) were conjugated to the molecular adjuvant P28. The P28 region of the complement protein C3d is the minimum CR2-binding domain necessary for the adjuvant activity of C3d. Delivery of DNA-based vaccines by gene gun and intramuscular routes stimulated production of IgG antibodies against the WNV DIII region of the E protein. With the exception of the vaccine expressing prM/E given intramuscularly, only mice that received DNA vaccines by gene gun produced protective neutralizing antibody titers (FRNT80 titer >1/40). Correspondingly, mice vaccinated by the gene gun route were protected to a greater level from lethal WNV challenge. In general, mice vaccinated with P28-adjuvated vaccines produced higher IgG titers than mice vaccinated with non-adjuvanted vaccines

    Anti-CRISPR-mediated control of gene editing and synthetic circuits in eukaryotic cells.

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    Repurposed CRISPR-Cas molecules provide a useful tool set for broad applications of genomic editing and regulation of gene expression in prokaryotes and eukaryotes. Recent discovery of phage-derived proteins, anti-CRISPRs, which serve to abrogate natural CRISPR anti-phage activity, potentially expands the ability to build synthetic CRISPR-mediated circuits. Here, we characterize a panel of anti-CRISPR molecules for expanded applications to counteract CRISPR-mediated gene activation and repression of reporter and endogenous genes in various cell types. We demonstrate that cells pre-engineered with anti-CRISPR molecules become resistant to gene editing, thus providing a means to generate "write-protected" cells that prevent future gene editing. We further show that anti-CRISPRs can be used to control CRISPR-based gene regulation circuits, including implementation of a pulse generator circuit in mammalian cells. Our work suggests that anti-CRISPR proteins should serve as widely applicable tools for synthetic systems regulating the behavior of eukaryotic cells

    A Prograde, Low-Inclination Orbit for the Very Hot Jupiter WASP-3b

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    We present new spectroscopic and photometric observations of the transiting exoplanetary system WASP-3. Spectra obtained during two separate transits exhibit the Rossiter-McLaughlin (RM) effect and allow us to estimate the sky-projected angle between the planetary orbital axis and the stellar rotation axis, lambda = 3.3^{+2.5}_{-4.4} degrees. This alignment between the axes suggests that WASP-3b has a low orbital inclination relative to the equatorial plane of its parent star. During our first night of spectroscopic measurements, we observed an unexpected redshift briefly exceeding the expected sum of the orbital and RM velocities by 140 m/s. This anomaly could represent the occultation of material erupting from the stellar photosphere, although it is more likely to be an artifact caused by moonlight scattered into the spectrograph.Comment: 23 pages, 4 figures, Accepted for publication in The Astrophysical Journal, Replacement includes revised citation

    Field Experiments and Meta-analysis Reveal Wetland Vegetation as a Crucial Element in the Coastal Protection Paradigm

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    Increasing rates of sea-level rise and wave actionthreaten coastal populations. Defense of shorelinesby protection and restoration of wetlands has beeninvoked as a win-win strategy for humans and na-ture, yet evidence from field experiments supportingthe wetland protection function is uncommon, as isthe understanding of its context dependency. Herewe provide evidence from field manipulationsshowing that the loss of wetland vegetation, regard-less of disturbance size, increases the rate oferosion on wave-stressed shorelines. Vegetationremoval (simulated disturbance) along the edge ofsalt marshes reveals that loss of wetland plants ele-vates the rate of lateral erosion and that extensiveroot systems, rather than aboveground biomass,are primarily responsible for protection againstedge erosion in marshes. Meta-analysis furthershows that disturbances that generate plant die-off on salt marsh edges generally hasten edgeerosion in coastal marshes and that the erosion pro-tection function of wetlands relates more to lateralthan vertical edge-erosional processes and ispositively correlated with the amount of below-ground plant biomass lost. Collectively, our findingssubstantiate a coastal protection paradigm thatincorporates preservation of shoreline vegetation,illuminate key context dependencies in this theory,and highlight local disturbances (e.g., oil spills)that kill wetland plants as agents that can acceleratecoastal erosion
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