1,878 research outputs found
Interstellar H-Alpha Line Profiles toward HD 93521 and the Lockman Window
We have used the Wisconsin H-Alpha Mapper (WHAM) facility to measure the
interstellar H-Alpha emission toward the high Galactic latitude O star HD 93521
(l = 183.1, b = +62.2). Three emission components were detected having radial
velocities of -10 km s^{-1}, -51 km s^{-1}, and -90 km s^{-1} with respect to
the local standard of rest (LSR) and H-Alpha intensities of 0.20 R, 0.15 R, and
0.023 R, respectively, corresponding to emission measures of 0.55 cm^{-6} pc,
0.42 cm^{-6} pc, and 0.06 cm^{-6} pc. We have also detected an H-Alpha emission
component at -1 km s^{-1} (LSR) with an intensity of 0.20 R (0.55 cm^{-6} pc)
toward the direction l = 148.5, b = +53.0, which lies in the region of
exceptionally low H I column density known as the Lockman Window. In addition,
we studied the direction l = 163.5, b = +53.5. Upper limits on the possible
intensity of Galactic emission toward this direction are 0.11 R at the LSR and
0.06 R at -50 km s^{-1}. We also detected and characterized twelve faint
(~0.03-0.15 R), unidentified atmospheric lines present in WHAM H-Alpha spectra.
Lastly, we have used WHAM to obtain [O I] 6300 spectra along the line of sight
toward HD 93521. We place an upper limit of 0.060 R on the [O I] intensity of
the -51 km s^{-1} component. If the temperature of the gas is 10,000 K within
the H-Alpha emitting region, the hydrogen ionization fraction n(H+)/n(H_total)
> 0.6.Comment: 23 pages, 4 figures. Acccepted for publication in the 1 Feb issue of
The Astronomical Journa
Numerical Model of a Variable-Combined-Cycle Engine for Dual Subsonic and Supersonic Cruise
Efficient high speed propulsion requires exploiting the cooling capability of the cryogenic fuel in the propulsion cycle. This paper presents the numerical model of a combined cycle engine while in air turbo-rocket configuration. Specific models of the various heat exchanger modules and the turbomachinery elements were developed to represent the physical behavior at off-design operation. The dynamic nature of the model allows the introduction of the engine control logic that limits the operation of certain subcomponents and extends the overall engine operational envelope. The specific impulse and uninstalled thrust are detailed while flying a determined trajectory between Mach 2.5 and 5 for varying throttling levels throughout the operational envelope
The distribution of burden of dental caries in schoolchildren: a critique of the high-risk caries prevention strategy for populations
BACKGROUND: The 'high-risk approach' is a commonly adopted strategy recommended for the prevention of dental caries in populations. The scientific basis for the strategy has been questioned. The objective of this study is to assess the contribution that children identified at 'high-risk' made towards the total of new caries lesions over a 4-year period, by analysing the distribution of new lesions per 100 children. METHODS: Data are from the National Preventive Dentistry Demonstration Programme (NPDDP) in the United States. The analyses identified the distribution of new carious lesions over a 4-year period in four groups of 7 year-old children who received differing preventive regimes. RESULTS: The majority of new lesions occurred in those children classified at lowest caries risk at baseline. Irrespective of the preventive regime adopted and the initial caries levels, children classified as 'highest risk' contributed less than 6% of the total number of new lesions developing over 4 years. CONCLUSION: These findings challenge the basis for the adoption of a high-risk strategy
An extremal effective survey about extremal effective cycles in moduli spaces of curves
We survey recent developments and open problems about extremal effective
divisors and higher codimension cycles in moduli spaces of curves.Comment: Submitted to the Proceedings of the Abel Symposium 2017. Comments are
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Exact equivalence at cyclic steady state between isothermal diffusion and linear driving force models for linear adsorption systems
Birational geometry of hypersurfaces in products of projective spaces
We study the birational properties of hypersurfaces in products of projective spaces. In the case of hypersurfaces in Pm x Pn, we describe their nef, movable and e ective cones and determine when they are Mori dream spaces. Using this, we give new simple examples of non-Mori dream spaces and analogues of Mumford's example of a strictly nef line bundle which is not ample.This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s00209-015-1415-
The multifractal fly: a dynamically multilayered visual system
We dynamically analyze our experimental results on the motion sensitive
spiking H1 neuron of the fly's visual system. We find that the fly uses an
alphabet composed of a few letters to encode the information contained in the
stimulus. The {\em alphabet dynamics} is multifractal both with and without
stimulus, though the multifractality increases with the stimulus entropy. This
is in sharp contrast to models generating independent spike-intervals, whose
dynamics is monofractal.Comment: 4 pages, 5 figure
TOPical Imiquimod treatment of high-grade Cervical intraepithelial neoplasia (TOPIC trial): study protocol for a randomized controlled trial
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