3,078 research outputs found
Efficient Boron-Carbon-Nitrogen Nanotube Formation Via Combined Laser-Gas Flow Levitation
A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula BxCyNz. The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula BxCyNz
One-way diffraction grating
Matthew J. Lockyear, Alastair P. Hibbins, Kevin R. White, and J. Roy Sambles, Physical Review E, Vol. 74, article 056611 (2006). "Copyright © 2006 by the American Physical Society."Diffraction gratings are elementary tools for much of optics and spectroscopy. Here, at microwave frequencies, we provide a new perspective on these fundamental structures. A transmission diffraction grating is presented that has diffracted beams emanating from one surface only. It can thus function either as a transmission grating with no reflected orders (other than zero) or, in the reverse configuration, as a partially transmitting structure with diffracted orders in reflection only
Updating the Kentucky Contract Time Determination System
The Federal Highway Administration requires State Transportation Agencies to have a formal method to estimate contract time for highway construction projects. To meet this requirement many states use an integrated scheduling system to estimate project durations based on assumed productivity rates and generic job logic. The current work investigated the accuracy of two of these systems found that both systems accuracy in predicting the duration of Kentucky Transportation Cabinet projects was greater than +200%. In response to this poor accuracy, a parametric project duration estimating tool was developed based on a multivariate regression analysis of bid item quantities and engineering and construction estimate. Five regression models were develop to estimate contract time for large projects (great than 1,000,000) as it appears that the duration of small projects is determined by factors outside of bid item quantities
The Einstein static universe in Loop Quantum Cosmology
Loop Quantum Cosmology strongly modifies the high-energy dynamics of
Friedman-Robertson-Walker models and removes the big-bang singularity. We
investigate how LQC corrections affect the stability properties of the Einstein
static universe. In General Relativity, the Einstein static model with positive
cosmological constant Lambda is unstable to homogeneous perturbations. We show
that LQC modifications can lead to a centre of stability for a large enough
positive value of Lambda.Comment: 12 pages, 7 figures; v2: minor changes to match published version in
Classical and Quantum Gravit
Deconvolution of Images from BLAST 2005: Insight into the K3-50 and IC 5146 Star-Forming Regions
We present an implementation of the iterative flux-conserving Lucy-Richardson
(L-R) deconvolution method of image restoration for maps produced by the
Balloon-borne Large Aperture Submillimeter Telescope (BLAST). We have analyzed
its performance and convergence extensively through simulations and
cross-correlations of the deconvolved images with available highresolution
maps. We present new science results from two BLAST surveys, in the Galactic
regions K3-50 and IC 5146, further demonstrating the benefits of performing
this deconvolution.
We have resolved three clumps within a radius of 4.'5 inside the star-forming
molecular cloud containing K3-50. Combining the well-resolved dust emission map
with available multi-wavelength data, we have constrained the Spectral Energy
Distributions (SEDs) of five clumps to obtain masses (M), bolometric
luminosities (L), and dust temperatures (T). The L-M diagram has been used as a
diagnostic tool to estimate the evolutionary stages of the clumps. There are
close relationships between dust continuum emission and both 21-cm radio
continuum and 12CO molecular line emission.
The restored extended large scale structures in the Northern Streamer of IC
5146 have a strong spatial correlation with both SCUBA and high resolution
extinction images. A dust temperature of 12 K has been obtained for the central
filament. We report physical properties of ten compact sources, including six
associated protostars, by fitting SEDs to multi-wavelength data. All of these
compact sources are still quite cold (typical temperature below ~ 16 K) and are
above the critical Bonner-Ebert mass. They have associated low-power Young
Stellar Objects (YSOs). Further evidence for starless clumps has also been
found in the IC 5146 region.Comment: 13 pages, 12 Figures, 3 Table
Recommended from our members
The Development of New User Research Capabilities in Environmental Molecular Science: Workshop Report
On August 1, and 2, 2006, 104 scientists representing 40 institutions including 24 Universities and 5 National Laboratories gathered at the W.R. Wiley Environmental Molecular Sciences Laboratory, a National scientific user facility, to outline important science challenges for the next decade and identify major capabilities needed to pursue advanced research in the environmental molecular sciences. EMSL’s four science themes served as the framework for the workshop. The four science themes are 1) Biological Interactions and Interfaces, 2) Geochemistry/Biogeochemistry and Surface Science, 3) Atmospheric Aerosol Chemistry, and 4) Science of Interfacial Phenomena
Recruitment of MLL1 complex is essential for SETBP1 to induce myeloid transformation
Abnormal activation of SETBP1 due to overexpression or missense mutations occurs frequently in various myeloid neoplasms and associates with poor prognosis. Direct activation of Hoxa9/Hoxa10/Myb transcription by SETBP1 and its missense mutants is essential for their transforming capability; however, the underlying epigenetic mechanisms remain elusive. We found that both SETBP1 and its missense mutant SETBP1(D/N) directly interact with histone methyltransferase MLL1. Using a combination of ChIP-seq and RNA-seq analysis in primary hematopoietic stem and progenitor cells, we uncovered extensive overlap in their genomic occupancy and their cooperation in activating many oncogenic transcription factor genes including Hoxa9/Hoxa10/Myb and a large group of ribosomal protein genes. Genetic ablation of Mll1 as well as treatment with an inhibitor of the MLL1 complex OICR-9429 abrogated Setbp1/Setbp1(D/N)- induced transcriptional activation and transformation. Thus, the MLL1 complex plays a critical role in Setbp1-induced transcriptional activation and transformation and represents a promising target for treating myeloid neoplasms with SETBP1 activation
Functional outcome of rotating platform total knee arthroplasty - A prospective observational study
Introduction: Rotating platform (RP) is a form of mobile-bearing design for total knee arthroplasty (TKA). This reduces the polyethylene contact stresses and the forces acting on tibial component and bone cement interfaces. It increases the femoral roll-back and flexion. The objective was to assess the functional outcome of rotating platform design in primary TKA, in patients with osteoarthritis of knee and the association of age and gender with the outcome.
Materials and methods: A prospective observational study was done on 42 patients who underwent primary TKA with RP design and followed-up for one year. The outcome was assessed with the Knee Society Score at one year. Data analysis was done using statistical package SPSS V-27.0.
Results: The mean age was 64.33(±6.12). The mean pre-op knee clinical score was 30(±6.409), which improved to mean post–op score of 92.17(±5.53). 37(88.1%) had excellent and 5(11.9%) had good results. 7(70%) patients in the age group <60 years, 24(96%) cases of 60–69 years and 6(85.7%) cases of ≥70 years had excellent results. 23(95.8%) females and 14(77.8%) males had excellent knee clinical scores. The mean pre-op knee functional score was 33.81(±9.988), which improved to a mean post–op score of 82.38(±6.917). 36 cases (85.7%) had excellent and 6(14.3%) had good results. 7(70%) patients <60 years, 22(88%) of 60- 69 years and 7(100%) of ≥70 years had excellent results. 21(87.5%) females and 15(83.3%) males had excellent knee functional scores.
Conclusion: Total knee arthroplasty with rotating platform design has shown excellent clinical and functional outcome without any serious complications at one year follow-up
Flight controller alertness and performance during MOD shiftwork operations
Decreased alertness and performance associated with fatigue, sleep loss, and circadian disruption are issues faced by a diverse range of shiftwork operations. During STS operations, MOD personnel provide 24 hr. coverage of critical tasks. A joint JSC and ARC project was undertaken to examine these issues in flight controllers during MOD shiftwork operations. An initial operational test of procedures and measures was conducted during STS-53 in Dec. 1992. The study measures included a background questionnaire, a subjective daily logbook completed on a 24 hr. basis (to report sleep patterns, work periods, etc.), and an 8 minute performance and mood test battery administered at the beginning, middle, and end of each shift period. Seventeen Flight controllers representing the 3 Orbit shifts participated. The initial results clearly support further data collection during other STS missions to document baseline levels of alertness and performance during MOD shiftwork operations. These issues are especially pertinent for the night shift operations and the acute phase advance required for the transition of day shift personnel into the night for shuttle launch. Implementation and evaluation of the countermeasure strategies to maximize alertness and performance is planned. As STS missions extend to further extended duration orbiters, timelines and planning for 24 circadian disruption will remain highly relevant in the MOD environment
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