202 research outputs found
Electro-optic architecture for servicing sensors and actuators in advanced aircraft propulsion systems
A detailed design of a fiber optic propulsion control system, integrating favored sensors and electro-optics architecture is presented. Layouts, schematics, and sensor lists describe an advanced fighter engine system model. Components and attributes of candidate fiber optic sensors are identified, and evaluation criteria are used in a trade study resulting in favored sensors for each measurand. System architectural ground rules were applied to accomplish an electro-optics architecture for the favored sensors. A key result was a considerable reduction in signal conductors. Drawings, schematics, specifications, and printed circuit board layouts describe the detailed system design, including application of a planar optical waveguide interface
Fiber optic control system integration
A total fiber optic, integrated propulsion/flight control system concept for advanced fighter aircraft is presented. Fiber optic technology pertaining to this system is identified and evaluated for application readiness. A fiber optic sensor vendor survey was completed, and the results are reported. The advantages of centralized/direct architecture are reviewed, and the concept of the protocol branch is explained. Preliminary protocol branch selections are made based on the F-18/F404 application. Concepts for new optical tools are described. Development plans for the optical technology and the described system are included
HI vinculado con regiones HII
Se están analizando observaciones de HI en las regiones Scorpios-Ophiuchus y Perseus donde Sivan (1974) observara en HI regiones HII de gran extensión angular.Asociación Argentina de Astronomí
A high sensitivity HI survey of the sky at delta < -25 deg Final data release
We present the final data release of the high sensitivity lambda 21-cm
neutral hydrogen survey of the sky south of delta < -25 degr. A total of 50980
positions lying on a galactic coordinate grid with points spaced by (Delta l,
Delta b) = ((0.5 deg)/cos b, 0.5 deg) were observed with the 30-m dish of the
Instituto Argentino de Radioastronomia (IAR). The angular resolution of the
survey is HPBW = 0.5 deg and the velocity coverage spans the interval -450 km/s
to +400 km/s (LSR). The velocity resolution is 1.27 km/s and the final rms
noise of the entire database is 0.07 K. The data are corrected for stray
radiation and converted to brightness temperatures.Comment: 10 pages, 10 figures, accepted for publication by Astronomy &
Astrophysic
OB Stars in the Solar Neighborhood I: Analysis of their Spatial Distribution
We present a newly-developed, three-dimensional spatial classification
method, designed to analyze the spatial distribution of early type stars within
the 1 kpc sphere around the Sun. We propose a distribution model formed by two
intersecting disks -the Gould Belt (GB) and the Local Galactic Disk (LGD)-
defined by their fundamental geometric parameters. Then, using a sample of
about 550 stars of spectral types earlier than B6 and luminosity classes
between III and V, with precise photometric distances of less than 1 kpc, we
estimate for some spectral groups the parameters of our model, as well as
single membership probabilities of GB and LGD stars, thus drawing a picture of
the spatial distribution of young stars in the vicinity of the Sun.Comment: 28 pages including 9 Postscript figures, one of them in color.
Accepted for publication in The Astronomical Journal, 30 January 200
Weight gain, overweight, and obesity: determinants and health outcomes from the Australian Longitudinal Study on Women’s Health
Recent estimates suggest that 35.3\ua0% of adult Australians are overweight and a further 27.5\ua0% are obese. The Australian Longitudinal Study on Women's Health (ALSWH) is a prospective study of women's health that commenced in Australia in 1996. The study recruited approximately 40,000 women in three birth cohorts, 1973-1978, 1946-1951 and 1921-1926, who have since been followed up approximately every three years using self-report surveys. Six surveys have been completed to date. This review aims to describe the changes in weight and weight status over time in the three ALSWH cohorts, and to review and summarise the published findings to date relating to the determinants and health consequences of weight gain, overweight and obesity. Future plans for the ALSWH include on-going surveys for all cohorts, with a seventh survey in 2013-2015, and establishment of a new cohort of women born in 1990-1995, which is currently being recruited
Hubble Space Telescope imaging of a peculiar stellar complex in NGC 6946
The stellar populations in a stellar complex in NGC 6946 are analyzed on
images taken with the Wide Field Planetary Camera 2 on board the Hubble Space
Telescope. The complex is peculiar by its very high density of stars and
clusters and semicircular shape. Its physical dimensions are about the same as
for the local Gould Belt, but the stellar density is 1 - 2 orders of magnitude
higher. In addition to an extremely luminous, 15 Myr old cluster discussed in
an earlier paper, accounting for about 17% of the integrated V-band light, we
identify 18 stellar clusters within the complex with luminosities similar to
the brightest open clusters in the Milky Way. The color-magnitude diagram of
individual stars in the complex shows a paucity of red supergiants compared to
model predictions in the 10-20 Myr age range for a uniform star formation rate.
We thus find tentative evidence for a gap in the dispersed star formation
history, with a concentration of star formation into a young globular cluster
during this gap. Confirmation of this result must, however, await a better
understanding of the late evolution of stars in the corresponding mass range (>
12 Msun). A reddening map based on individual reddenings for 373 early-type
stars is presented, showing significant variations in the absorption across the
complex. These may be responsible for some of the arc-like structures
previously identified on ground-based images. We finally discuss various
formation scenarios for the complex and the star clusters within it.Comment: 51 pages, including 19 figures and 4 tables. Accepted for publication
in Ap
CaII K interstellar observations towards early disc and halostars - Paper II; distances to IVCs and HVCs
We compare existing high spectral resolution (R=40,000) CaII K observations
towards 88 mainly B-type stars, and new observations at R=10,000 towards 3
stars, with 21-cm HI emission-line profiles, in order to search for optical
absorption towards known intermediate and high velocity cloud complexes. Given
certain assumptions, limits to the gas phase abundance of CaII are estimated
for the cloud components. We use the data to derive the following distances
from the Galactic plane (z); 1) Tentative lower z-height limits of 2800 pc and
4100 pc towards Complex C using lack of absorption in the spectra of HD 341617
and PG 0855+294. 2) A weak lower z-height of 1400 pc towards Complex WA-WB
using lack of absorption in EC 09470-1433 and weak lower limit of 2470 pc with
EC 09452-1403. 3) An upper z-height of 2470 pc towards a southern intermediate
velocity cloud (IVC) with v_LSR=-55 km/s using PG 2351+198. 4) Detection of a
possible IVC in CaK absorption at v_LSR=+52 km/s using EC 20104-2944. No
associated HI in emission is detected. At this position, normal Galactic
rotation predicts velocities of up to +25 km/s. The detection puts an upper
z-height of 1860 pc to the cloud. 5) Tentative HI and CaK detections towards an
IVC at +70 km/s in the direction of HVC Complex WE, sightline EC 06387-8045,
indicating that the IVC may be at a z-height lower than 1770 pc. 6) Detection
of CaK absorption in the spectrum of PG 0855+294 in the direction of IV20,
indicating that this IVC has a z-height smaller than 4100 pc. 7) A weak lower
z-height of 4300 pc towards a small HVC with v_LSR=+115 km/s at l,b=200,+52,
using lack of absorption in the CaK spectrum of PG 0955+291.Comment: 13 pages, 5 figures. Accepted for publication in MNRAS, May 13 200
Urbanization and mortality in Britain, c. 1800-50.
In the long-running debate over standards of living during the industrial revolution, pessimists have identified deteriorating health conditions in towns as undermining the positive effects of rising real incomes on the 'biological standard of living'. This article reviews long-run historical relationships between urbanization and epidemiological trends in England, and then addresses the specific question: did mortality rise especially in rapidly growing industrial and manufacturing towns in the period c. 1830-50? Using comparative data for British, European, and American cities and selected rural populations, this study finds good evidence for widespread increases in mortality in the second quarter of the nineteenth century. However, this phenomenon was not confined to 'new' or industrial towns. Instead, mortality rose in the 1830s especially among young children (aged one to four years) in a wide range of populations and environments. This pattern of heightened mortality extended between c. 1830 and c. 1870, and coincided with a well-established rise and decline in scarlet fever virulence and mortality. The evidence presented here therefore supports claims that mortality worsened for young children in the middle decades of the nineteenth century, but also indicates that this phenomenon was more geographically ubiquitous, less severe, and less chronologically concentrated than previously argued.Leverhulme Trust (award RPG-2012-803)
Wellcome Trust (award no. 103322
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