Halpha emission-line stars in molecular clouds. II. The M42 region

We present a deep survey of Halpha emission-line stars in the M42 region using wide-field objective prism films. A total of 1699 Halpha emission-line stars were identified, of which 1025 were previously unknown, within an area of 5.5 x 5.5 degrees centred on the Trapezium Cluster. We present Halpha strength estimates, positions, and JHKs photometry extracted from 2MASS, and comparisons to previous surveys. The spatial distribution of the bulk of the stars follows the molecular cloud as seen in CO and these stars are likely to belong to the very young population of stars associated with the Orion Nebula Cluster. Additionally, there is a scattered population of Halpha emission-line stars distributed all over the region surveyed, which may consist partly of foreground stars associated with the young NGC 1980 cluster, as well as some foreground and background dMe or Be stars. The present catalogue adds a large number of candidate low-mass young stars belonging to the Orion population, selected independently of their infrared excess or X-ray emission.Comment: 38 pages, 18 figures. Published in Astronomy & Astrophysics v3: chart for ESO-HA 1639 corrected. Typos in Table 2 corrected. Photometry for ESO-HA 1639 in Table 2 correcte

An Emergence Trap for Aquatic Insects

Excerpt: The identification of organisms is a prerequisite to developing water quality criteria for aquatic life. Identification is necessary because differences in water quality requirements are specific and may be different for closely allied species. The taxonomy of various species, particularly those associated with the aquatic environment, is much more detailed and better known for adults than for immature instars. To facilitate correlation of adult and larval forms, a trap was needed to collect the emerging adults from the various streams

Assessing alternative competitive balance measures for sports leagues: a theoretical examination of standard deviations, gini coefficients, & the index of dissimilarity

This note provides a theoretical analysis of the use of standard deviations, Gini coefficients, and the Index of Dissimilarity to assess competitive balance in sports leagues. Limitations are identified for all three techniques. Each of these techniques is found to be affected by the introduction of more teams, unbalanced schedules, and inter-league play.

Electric Market Restructuring: Environmental Considerations

In the past few years,Maine\u27s electric utilities have begun to face the forces of competition.Maineis experiencing the effects of a national trend, a shift from a traditional and regulated system to a more innovative and competitive one. Armond Cohen explores the environmental impacts that are at stake in restructuring and offers some possible solutions. This article is taken from the author’s presentation at a December 1994 conference entitled ”Retail Wheeling,” sponsored by the Margaret Chase Smith Center for Public Policy\u27s Project for the Study of Regulation and the Environment

Ammonia Oxygen Demand Determination for the Design of an Oxygenation System in a Water Supply Reservoir

The Occoquan Reservoir is a eutrophic reservoir that is part of an indirect potable reuse system. To protect the reservoir water quality, a high quality nitrified product water from a water reclamation facility and an oxygenation system are used during periods of thermal stratification to prevent the onset of anaerobic conditions above the sediments. During the stratified warmest months of the year, oxygen depletion rates exceed nitrate and artificial oxygen supply rates near the dam resulting in ammonia accumulation in the water column. Field observations and laboratory experiments revealed that sediment ammonia release rates ranged from 170-542 mg/m2∙day. At such rates, ammonia concentrations above the sediments reach values as high as 5.6 mg-N/L in the absence of nitrate and oxygen, and values as high as 2 mg-N/L when the oxygenation system is operational. A thorough analysis on ammonia cycling revealed that for the years studied, hypolimnetic ammonia oxygen demand may reach values as high as 77 metric tons of oxygen during a stratification period of 140 days. Furthermore, ammonia oxygen demand represented 20-100%, and in some cases more than 100% of the hypolimnetic oxygen demand estimated from oxygen depletion curves, which are commonly used to design oxygenation systems. Finally, it was determined that to satisfy ammonia oxygen demand in the reservoir, it is necessary to provide three times the oxygen demand estimated from the oxygen depletion curves. These results highlight the importance of estimating benthic fluxes of reduced substances into the water column (e.g. ammonia) when designing oxygenation systems

Advanced Conducting Project

Contents include: A Childhood Hymn by David Holsinger All the Pretty Horses (Mtv. 2 from Three Folk Song Settings for Band ) ; arranged by Andrew Boysen, Jr. As the Robin to the Meadow by Todd Stalter Chesford Portrait by James Swearinger Go Galop by Dr. Nicholas J. Contorno Greek Folk Song Suite (Movements II & III) by Franco Cesarini Groove Music by Brian Balmages In Heaven\u27s Air by Samuel R. Hazo Nemesis by Gary D. Ziek Shockwave by Gary D. Ziek Variations on a Korean Folk Song by John Barnes Chance