263 research outputs found
Aerodynamic preliminary analysis system 2. Part 2: User's manual
An aerodynamic analysis system based on potential theory at subsonic and/or supersonic speeds and impact type finite element solutions at hypersonic conditions is described. Three dimensional configurations have multiple nonplanar surfaces of arbitrary planforms and bodies of noncircular contour may be analyzed. Static, rotary, and control longitudinal and lateral-directional characteristics may be generated. The analysis was implemented on a time sharing system in conjunction with an input tablet digitizer and an interactive graphics input/output display and editing terminal to maximize its responsiveness to the preliminary analysis. Computation times on an IBM 3081 are typically less than one minute of CPU/Mach number at subsonic, supersonic, or hypersonic speeds. This is a user manual for the computer programming
Enhancing the Critical Current of a Superconducting Film in a Wide Range of Magnetic Fields with a Conformal Array of Nanoscale Holes
The maximum current (critical current) a type-II superconductor can transmit
without energy loss is limited by the motion of the quantized magnetic flux
penetrating into a superconductor. Introducing nanoscale holes into a
superconducting film has been long pursued as a promising way to increase the
critical current. So far the critical current enhancement was found to be
mostly limited to low magnetic fields. Here we experimentally investigate the
critical currents of superconducting films with a conformal array of nanoscale
holes that have non-uniform density while preserving the local ordering. We
find that the conformal array of nanoscle holes provides a more significant
critical current enhancement at high magnetic fields. The better performance
can be attributed to its arching effect that not only gives rise to the
gradient in hole-density for pinning vortices with a wide range of densities
but also prevent vortex channeling occurring in samples with a regular lattice
of holes.Comment: 5 pages, 3 figure
Fundamental Parameters of He-Weak and He-Strong Stars
We carried out low resolution spectroscopic observations in the wavelength
range 3400-4700 A of 20 He-weak and 8 He-strong stars to determine their
fundamental parameters by means of the Divan-Chalonge-Barbier (BCD)
spectrophotometric system. For a few He-weak stars we also estimate the
effective temperatures and the angular diameters by integrating absolute fluxes
observed over a wide spectral range. Non-LTE model calculations are carried out
to study the influence of the He/H abundance ratio on the emergent radiation of
He-strong stars and on their Teff determination. We find that the effective
temperatures, surface gravities and bolometric absolute magnitudes of He-weak
stars estimated with the BCD system and the integrated flux method are in good
agreement between each other, and they also agree with previous determinations
based on several different methods. The mean discrepancy between the visual
absolute magnitudes derived using the Hipparcos parallaxes and the BCD values
is on average 0.3 mag for He-weak stars, while it is 0.5 mag for He-strong
stars. For He-strong stars, we note that the BCD calibration, based on stars in
the solar environment, leads to overestimated values of Teff. By means of model
atmosphere calculations with enhanced He/H abundance ratios we show that larger
He/H ratios produce smaller BD which naturally explains the Teff
overestimation. We take advantage of these calculations to introduce a method
to estimate the He/H abundance ratio in He-strong stars. The BD of HD 37479
suggests that the Teff of this star remains fairly constant as the star
spectrum undergoes changes in the intensity of H and He absorption lines. Data
for the He-strong star HD 66765 are reported for the first time.Comment: Accepted for publication in A&
Reddening law and interstellar dust properties along Magellanic sight-lines
This study establishes that SMC, LMC and Milky Way extinction curves obey the
same extinction law which depends on the 2200A bump size and one parameter, and
generalizes the Cardelli, Clayton and Mathis (1989) relationship. This suggests
that extinction in all three galaxies is of the same nature. The role of linear
reddening laws over all the visible/UV wavelength range, particularly important
in the SMC but also present in the LMC and in the Milky Way, is also
highlighted and discussed.Comment: accepted for publication in Astrophysics and Space Science. 16 pages,
12 figures. Some figures are colour plot
Physical parameters of IPHAS-selected classical Be stars. (I. Determination procedure and evaluation of the results.)
Reproduced with permission from Astronomy & Astrophysics, © 2016 ESOWe present a semi-automatic procedure to obtain fundamental physical parameters and distances of classical Be (CBe) stars, based on the Barbier-Chalonge-Divan (BCD) spectrophotometric system. Our aim is to apply this procedure to a large sample of CBe stars detected by the IPHAS photometric survey, to determine their fundamental physical parameters and to explore their suitability as galactic structure tracers. In this paper we describe the methodology used and the validation of the procedure by comparing our results with those obtained from different independent astrophysical techniques for subsamples of stars in common with other studies. We also present a test case study of the galactic structure in the direction of the Perseus Galactic Arm, in order to compare our results with others recently obtained with different techniques and the same sample of stars. We did not find any significant clustering of stars at the expected positions of the Perseus and Outer Galactic Arms, in agreement with previous studies in the same area that we used for verification.Peer reviewedFinal Published versio
A Murine Model of Lyme Disease Demonstrates That Borrelia burgdorferi Colonizes the Dura Mater and Induces Inflammation in the Central Nervous System
Lyme disease, which is caused by infection with Borrelia burgdorferi and related species, can lead to inflammatory pathologies affecting the joints, heart, and nervous systems including the central nervous system (CNS). Inbred laboratory mice are effective models for characterizing B. burgdorferi infection kinetics and host immune responses in joints and heart tissues; however, similar studies are lacking in the CNS of these animals. Here we characterize the kinetics of B. burgdorferi colonization and associated immune responses in the CNS of infected C3H mice during early and subacute infection. B. burgdorferi colonized the dura mater following needle or tick challenge, and induced expression of inflammatory cytokines and a robust IFN response as well as histopathological changes. A sterile IFN response in the absence of B. burgdorferi or inflammatory cytokines was unique to the brain parenchyma, and could provide insights into the mechanism of inflammatory CNS pathology associated with this important pathogen
How do research-intensive universities portray employability strategies? A review of their websites
© Australian Council for Educational Research 2017. Employability development is a strategic priority for universities across advanced western economies. Despite this, there is no systematic study of employability development approaches internationally. In this study, we considered how universities portray employability on the public pages of their websites. We undertook website content analysis of 107 research-intensive universities in Australia, Canada, the United Kingdom and the United States. Following Farenga and Quinlan, we classified these strategies as Portfolio, Hands-off, Award and Non-embedded. Portfolio or Award strategies were the most common across all four locations; Hands-off and Non-embedded strategies were more common to US universities; and Award was more common in the United Kingdom. Universities focused on either possessional or positional approaches to employability. We advocate for a pedagogical shift towards processual approaches in which responsibility for employability development is shared
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