3,179 research outputs found
Analysis and design of a high tip speed, low noise aircraft fan incorporating swept leading edge rotor and stator blades
Genetic analysis and prevalence studies of the brp exopolysaccharide locus of Vibrio vulnificus
Phase variation in the Gram-negative human pathogen Vibrio vulnificus involves three colonial morphotypes- smooth opaque colonies due to production of capsular polysaccharide (CPS), smooth translucent colonies as the result of little or no CPS expression, and rugose colonies due to production of a separate extracellular polysaccharide (EPS), which greatly enhances biofilm formation. Previously, it was shown that the brp locus, which consists of nine genes arranged as an operon, is up-regulated in rugose strains in a c-di-GMP-dependent manner, and that plasmid insertions into the locus resulted in loss of rugosity and efficient biofilm production. Here, we have used non-polar mutagenesis to assess the involvement of individual brp genes in production of EPS and related phenotypes. Inactivation of genes predicted to be involved in various stages of EPS biosynthesis eliminated both the rugose colonial appearance and production of EPS, while knockout of a predicted flippase function involved in EPS transport resulted in a dry, lightly striated phenotype, which was associated with a reduction of brp-encoded EPS on the cell surface. All brp mutants retained the reduced motility characteristic of rugose strains. Lastly, we provide evidence that the brp locus is highly prevalent among strains of V. vulnificus. © 2014 Garrison-Schilling et al
Accuracy and Precision of Tidal Wetland Soil Carbon Mapping in the Conterminous United States
Tidal wetlands produce long-term soil organic carbon (C) stocks. Thus for carbon accounting purposes, we need accurate and precise information on the magnitude and spatial distribution of those stocks. We assembled and analyzed an unprecedented soil core dataset, and tested three strategies for mapping carbon stocks: applying the average value from the synthesis to mapped tidal wetlands, applying models fit using empirical data and applied using soil, vegetation and salinity maps, and relying on independently generated soil carbon maps. Soil carbon stocks were far lower on average and varied less spatially and with depth than stocks calculated from available soils maps. Further, variation in carbon density was not well-predicted based on climate, salinity, vegetation, or soil classes. Instead, the assembled dataset showed that carbon density across the conterminous united states (CONUS) was normally distributed, with a predictable range of observations. We identified the simplest strategy, applying mean carbon density (27.0âkg C mâ3), as the best performing strategy, and conservatively estimated that the top meter of CONUS tidal wetland soil contains 0.72 petagrams C. This strategy could provide standardization in CONUS tidal carbon accounting until such a time as modeling and mapping advancements can quantitatively improve accuracy and precision
Creative and Stylistic Devices Employed by Children During a Storybook Narrative Task: A Cross-Cultural Study
Purpose: The purpose of this study was to analyze the effects of culture on the creative and stylistic features children employ when producing narratives based on wordless picture books.
Method: Participants included 60 first- and second-grade African American, Latino American, and Caucasian children. A subset of narratives based on wordless picture books collected as part of a larger study was coded and analyzed for the following creative and stylistic conventions: organizational style (topic centered, linear, cyclical), dialogue (direct, indirect), reference to character relationships (nature, naming, conduct), embellishment (fantasy, suspense, conflict), and paralinguistic devices (expressive sounds, exclamatory utterances).
Results: Many similarities and differences between ethnic groups were found. No significant differences were found between ethnic groups in organizational style or use of paralinguistic devices. African American children included more fantasy in their stories, Latino children named their characters more often, and Caucasian children made more references to the nature of character relationships.
Conclusion: Even within the context of a highly structured narrative task based on wordless picture books, culture influences childrenâs production of narratives. Enhanced understanding of narrative structure, creativity, and style is necessary to provide ecologically valid narrative assessment and intervention for children from diverse cultural backgrounds
High intensity X/ Îł photon beams for nuclear physics and photonics
In this manuscript we review the challenges of Compton back-scattering sources in advancing photon beam performances in the1â20MeVenergy range, underlining the design criteria bringing tomaximum spectral luminosity and briefly describing the main achieve-ments in conceiving and developing new devices (multi-bunch RF cav-ities and Laser recirculators) for the case of ELI-NP Gamma BeamSystem (ELI-NP-GBS)
Conceptual design of a nonscaling fixed field alternating gradient accelerator for protons and carbon ions for charged particle therapy
Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articleâs title, journal citation, and DOI.The conceptual design for a nonscaling fixed field alternating gradient accelerator suitable for charged particle therapy (the use of protons and other light ions to treat some forms of cancer) is described.EPSR
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The use of an intermediate wavelength laser for alignment to inertial confinement fusion targets
The conceptual design of the National Ignition Facility (NIF) 192 beam laser incorporates a low-power alignment beam injected in the pinhole plane of the final spatial filter with a wave length intermediate between the 1053 mn laser output and the 351 mn frequency-converted beam that illuminates the target Choosing the specific wavelength for which the spatial filter plane is reimaged in the same target chamber plane as the frequency-converted main laser pulse, achieves optimum accuracy without the need for additional means to insure precise overlap between the two beams. Insertion of the alignment beam after the last laser amplifier also allows alignment to the target while the amplifiers are still cooling from a previous shot
TPOAb and thyroid function are not associated with breast cancer outcome: evidence from a large-scale study using data from the Taxotere as Adjuvant Chemotherapy Trial (TACT, CRUK01/001)
Background: Small-scale studies correlated the presence of thyroid autoimmunity with both improved or worsened breast cancer outcome. Objectives: We aimed to clarify this association in a large cohort using the phase III, randomized, controlled Taxotere as Adjuvant Chemotherapy Trial (TACT, CRUK01/001). Methods: TACT women >18 years old with node-positive or high-risk node-negative early breast cancer (pT1â3a, pN0â1, M0), with stored plasma (n = 1,974), taken 15.5 (median; IQR 7.0â24.0) months after breast surgery were studied. Patients had also received chemotherapy (100%), radiotherapy (1,745/1,974; 88.4%), hormonal therapy (1,378/ 1,974; 69.8%), or trastuzumab (48/1,974; 2.4%). History of thyroid diseases and/or related treatments was not available. The prognostic significance of autoantibodies to thyroid peroxidase (TPOAb; positive â„6 kIU/L), free-thyroxine and thyrotropin (combined: euthyroid, hypothyroid, hyperthyroid) was evaluated for disease-free survival (DFS), overall-survival (OS), and time-to-recurrence (TTR), with Cox regression models in univariate and multivariable analyses. The extended median follow-up was 97.5 months. Results: No difference in DFS was found by TPOAb status (unadjusted hazard ratio [HR]: 0.97, 95%CI: 0.78â1.19; p = 0.75) and/or thyroid function (unadjusted HR [hypothyroid vs. euthyroid]: 1.15, 95% CI: 0.79â1.68; p = 0.46; unadjusted HR [hyperthyroid vs. euthyroid]: 1.14, 95% CI: 0.82â1.61; p = 0.44). Similar results were obtained for OS, TTR, multivariable analyses, when TPOAb titre by tertiles was considered, and in a subgroup of 123 patients with plasma collected before adjuvant treatments. Conclusions: No evidence for a prognostic role of TPOAb and/or thyroid function in moderate-to-high-risk early breast cancer was found in the largest and longest observational study to date
SU(3) lattice gauge theory with a mixed fundamental and adjoint plaquette action: Lattice artefacts
We study the four-dimensional SU(3) gauge model with a fundamental and an
adjoint plaquette term in the action. We investigate whether corrections to
scaling can be reduced by using a negative value of the adjoint coupling. To
this end, we have studied the finite temperature phase transition, the static
potential and the mass of the 0^{++} glueball. In order to compute these
quantities we have implemented variance reduced estimators that have been
proposed recently. Corrections to scaling are analysed in dimensionless
combinations such as T_c/\sqrt{\sigma} and m_{0^{++}}/T_c. We find that indeed
the lattice artefacts in e.g. m_{0^{++}}/T_c can be reduced considerably
compared with the pure Wilson (fundamental) gauge action at the same lattice
spacing.Comment: 36 pages, 12 figure
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