9,007 research outputs found
Cleaning up Eta Carinae: Detection of Ammonia in the Homunculus
We report the first detection of ammonia in the Homunculus nebula around eta
Carinae, which is also the first detection of emission from a polyatomic
molecule in this or any other luminous blue variable (LBV) nebula. Observations
of the NH3 (J,K)=(3,3) inversion transition made with the Australia Telescope
Compact Array reveal emission at locations where infrared H2 emission had been
detected previously, near the strongest dust emission in the core of the
Homunculus. We also detect ammonia emission from the so-called ``strontium
filament'' in the equatorial disk. The presence of NH3 around eta Car hints
that molecular shells around some Wolf-Rayet stars could have originated in
prior LBV eruptions, rather than in cool red supergiant winds or the ambient
interstellar medium. Combined with the lack of any CO detection, NH3 seems to
suggest that the Homunculus is nitrogen rich like the ionized ejecta around eta
Car. It also indicates that the Homunculus is a unique laboratory in which to
study unusual molecule and dust chemistry, as well as their rapid formation in
a nitrogen-rich environment around a hot star. We encourage future observations
of other transitions like NH3 (1,1) and (2,2), related molecules like N2H+, and
renewed attempts to detect CO.Comment: 4 pages, accepted to ApJ letter
Simulation analysis of energy production in the B. C. pulp and paper industry
ABSTRACT
This paper describes a dynamic simulation model of energy production
and use by pulp and paper mills. The model can be used to assess the costs
and benefits of the use of different proportions of wood waste (referred
to as 'hog fuel') and fossil fuels to generate process steam and electricity,
with the costs and benefits measured from several points of view, principally
those of the mill management and of the economy as a whole. Using either
point of view, the model has been fitted to the eighteen major pulp and paper
mills in British Columbia, and used to assess the consequences of the size and
nature of optimal hog fuel projects. Some results are reported in this
paper and references are given to other papers containing more complete
results of various aspects of the research project.
INTRODUCTION
Whenever there are big changes in technology or relative prices, many
of the standard rules of thumb for optimal choices fall apart, and many
new alternatives have to be considered in a systematic way. This offers
great scope for the design and use of simulation models that capture the
key elements of an industrial process and expose the key alternatives for
This paper was presented to the conference on Simulation Modelling
and Decision in Energy Systems, held in Montreal in June, 1978 and
sponsored by the International Association of Science and Technology
for Development. It represents early results of work also reported in
[1], [2], [3] and [4]. While Helliwell is a continuing member of U.B.C.'s
Department of Economics, Cox is currently at M.I.T.'s Energy Laboratory
Cambridge, Mass
Tracking and Testing Of US and Canadian Cattle Herds for BSE: A Risk Management Dilemma
Livestock Production/Industries,
Music Score Approval Plans in Research Libraries: A Survey of Librarian Satisfaction With and Without Approval Plans
In this study, the researchers submitted a music score approval plan survey to all ARL libraries. Two surveys were created, one for libraries with music score approval plans, one for those without. Forty-four surveys were returned. The authorsâ purpose was to analyze and discuss the survey results, incorporating elements of the scholarly work preceding this study. Discussions, roundtables, and listservs participated in by music librarians over the years formed the basis of the topic at hand. The goal was to ascertain whether these discussions and underlying assumptions of approval plans held true to the real world
Nystagmus during an acute MĂ©niĂšre's attack: From prodrome to recovery
OBJECTIVE: We are currently undertaking a clinical investigation to evaluate the diagnostic capability of a system for detecting periods of pathological dizziness. This article presents an analysis of the data captured during an acute attack of MĂ©niĂšre's disease. DESIGN: The Continuous Ambulatory Vestibular Assessment (CAVA) device is worn by patients in the community, and continuously records eye and head movement data (vestibular telemetry). STUDY SAMPLE: A 53-year-old lady with a fifteen-year history of left-sided unilateral MĂ©niĂšre's disease. RESULTS: The patient wore the device nearly continuously for thirty days. The data revealed a three-hour long attack of vertigo consisting of four separate phases of nystagmus. The duration, beat-direction and slow phase velocity of the nystagmus evolved through time. The first phase contained isolated nystagmus beats which preceded the patient's record of the vertigo attack onset but coincided with anticipation of an impending vertigo attack. CONCLUSIONS: CAVA provides a unique insight into the physiological parameters present during episodes of dizziness. Here, it has provided the first full example of an acute MĂ©niĂšre's attack, including a period of prodrome. These findings have implications for the prediction of vertigo attack onset, for the diagnosis of MĂ©niĂšre's disease and other diseases resulting in dizziness
Substantial Red Wolf Genetic Ancestry Persists in Wild Canids of Southwestern Louisiana
Concerns over red wolf (Canis rufus) extinction caused by hybridization with coyotes (C. latrans) led to the capture and removal of remnant wild wolves from southwestern Louisiana and southeastern Texas, United States, during the 1970s. Here we show that despite decades of unmitigated hybridization, and declaration of endangered red wolves as functionally extinct in the wild, red wolf mitochondrial or nuclear DNA ancestry persists in âŒ55% of contemporary wild canids sampled in southwestern Louisiana. Surprisingly, one individual had 78â100% red wolf ancestry, which is within the range for 75% red wolf, red wolf backcross, or putative red wolf, depending on estimation method. Our findings bolster support for designation of red wolves as a distinct species, demonstrate a critical need for the United States Government to consider adopting an existing but unimplemented hybrid policy, and suggest that immediate reassessment of canid management and taxonomic designation in southwestern Louisiana may be warranted
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