5,832 research outputs found
The Cardigan Pluton of the Kinsman Quartz Monzonite
Guidebook for field trips in central New Hampshire and contiguous areas: 63rd annual meeting October 2 and 3, 1971 Concord, New Hampshire: Trip A-
Robust designs for Poisson regression models
We consider the problem of how to construct robust designs for Poisson regression models. An analytical expression is derived for robust designs for first-order Poisson regression models where uncertainty exists in the prior parameter estimates. Given certain constraints in the methodology, it may be necessary to extend the robust designs for implementation in practical experiments. With these extensions, our methodology constructs designs which perform similarly, in terms of estimation, to current techniques, and offers the solution in a more timely manner. We further apply this analytic result to cases where uncertainty exists in the linear predictor. The application of this methodology to practical design problems such as screening experiments is explored. Given the minimal prior knowledge that is usually available when conducting such experiments, it is recommended to derive designs robust across a variety of systems. However, incorporating such uncertainty into the design process can be a computationally intense exercise. Hence, our analytic approach is explored as an alternative
High-Speed Tests of Radial-Engine Cowlings
The drag characteristics of eight radial-engine cowlings have been determined over a wide speed range in the N.A.C.A. 8-foot high-speed wind tunnel. The pressure distribution over all cowlings was measured, to and above the speed of the compressibility burble, as an aid in interpreting the force tests. One-fifth-scale models of radial-engine cowlings on a wing-nacelle combination mere used in the tests
High-Speed Tests of Conventional Radial-Engine Cowlings
The drag characteristics of eight radial-engine cowlings have been determined over a wide speed range in the NACA 8-foot high-speed wind tunnel. The pressure distribution over all cowlings was measured, to and above the speed of the compressibility burble, as an aid in interpreting the force tests. One-fifth-scale models of radial-engine cowlings on a wing-nacelle combination were used in the tests
Ionization-induced asymmetric self-phase modulation and universal modulational instability in gas-filled hollow-core photonic crystal fibers
We study theoretically the propagation of relatively long pulses with
ionizing intensities in a hollow-core photonic crystal fiber filled with a
Raman-inactive gas. Due to photoionization, previously unknown types of
asymmetric self-phase modulation and `universal' modulational instabilities
existing in both normal and anomalous dispersion regions appear. We also show
that it is possible to spontaneously generate a plasma-induced continuum of
blueshifting solitons, opening up new possibilities for pushing supercontinuum
generation towards shorter and shorter wavelengths.Comment: 5 pages, 4 figure
Direct characterisation of tuneable few-femtosecond dispersive-wave pulses in the deep UV
Dispersive wave emission (DWE) in gas-filled hollow-core dielectric
waveguides is a promising source of tuneable coherent and broadband radiation,
but so far the generation of few-femtosecond pulses using this technique has
not been demonstrated. Using in-vacuum frequency-resolved optical gating, we
directly characterise tuneable 3fs pulses in the deep ultraviolet generated via
DWE. Through numerical simulations, we identify that the use of a pressure
gradient in the waveguide is critical for the generation of short pulses.Comment: 5 pages, 4 figure
An Economic Comparison Of Year Round vs Conventional Grazing Systems In Iowa
Year round grazing systems that utilize stockpiled forage and/or crop residue are often promoted as a way for Northern and Western cow-calf producers to reduce winter feeding costs and improve overall profitability. This study compared the profitability of a conventional spring calving/summer grazing- winter drylot herd to a year round system that utilized both spring- and fall-calving herds with weaned calves retained as stockers. Forage supplies in the year round system were derived from stockpiled forage and corn crop residues. We developed a model that randomly generated production values with parameters based on the results of a 3-year study conducted at the Iowa State University McNay Research and Demonstration farm near Chariton, Iowa. The simulated production values were combined with livestock and forage prices prevailing from 1993-2001 to estimate income per head generated by each system. Average income over the nine- year period was equal. However, the year round system was economically superior in 3 years, equivalent in 1 year, and inferior in 5 years.
The impact of targeting all elderly persons in England and Wales for yearly influenza vaccination: excess mortality due to pneumonia or influenza and time trend study.
OBJECTIVE: To investigate the impact on mortality due to pneumonia or influenza of the change from risk-based to age group-based targeting of the elderly for yearly influenza vaccination in England and Wales. DESIGN: Excess mortality estimated using time series of deaths registered to pneumonia or influenza, accounting for seasonality, trend and artefacts. Non-excess mortality plotted as proxy for long-term trend in mortality. SETTING: England and Wales. PARTICIPANTS: Persons aged 65-74 and 75+ years whose deaths were registered to underlying pneumonia or influenza between 1975/1976 and 2004/2005. OUTCOME MEASURES: Multiplicative effect on average excess pneumonia and influenza deaths each winter in the 4-6 winters since age group-based targeting of vaccination was introduced (in persons aged 75+ years from 1998/1999; in persons aged 65+ years from 2000/2001), estimated using multivariable regression adjusted for temperature, antigenic drift and vaccine mismatch, and stratified by dominant circulating influenza subtype. Trend in baseline weekly pneumonia and influenza death rates. RESULTS: There is a suggestion of lower average excess mortality in the six winters after age group-based targeting began compared to before, but the CI for the 65-74 years age group includes no difference. Trend in baseline pneumonia and influenza mortality shows an apparent downward turning point around 2000 for the 65-74 years age group and from the mid-1990s in the 75+ years age group. CONCLUSIONS: There is weakly supportive evidence that the marked increases in vaccine coverage accompanying the switch from risk-based to age group-based targeting of the elderly for yearly influenza vaccination in England and Wales were associated with lower levels of pneumonia and influenza mortality in older people in the first 6 years after age group-based targeting began. The possible impact of these policy changes is observed as weak evidence for lower average excess mortality as well as a turning point in baseline mortality coincident with the changes
A Sr-Rich Star on the Main Sequence of Omega Centauri
Abundance ratios relative to iron for carbon, nitrogen, strontium and barium
are presented for a metal-rich main sequence star ([Fe/H]=--0.74) in the
globular cluster omega Centauri. This star, designated 2015448, shows depleted
carbon and solar nitrogen, but more interestingly, shows an enhanced abundance
ratio of strontium [Sr/Fe] ~ 1.6 dex, while the barium abundance ratio is
[Ba/Fe]<0.6 dex. At this metallicity one usually sees strontium and barium
abundance ratios that are roughly equal. Possible formation scenarios of this
peculiar object are considered.Comment: 13 pages, 3 figures. Accepted to ApJ
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