547 research outputs found

    Oxygen Abundances in Two Metal-Poor Subgiants from the Analysis of the 6300 A Forbidden O I Line

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    Recent LTE analyses (Israelian et al. 1998 and Bosegaard et al. 1999) of the OH bands in the optical-ultraviolet spectra of nearby metal-poor subdwarfs indicate that oxygen abundances are generally higher than those previously determined. The difference increases with decreasing metallicity and reaches delta([O/Fe]) ~ +0.6 dex as [Fe/H] approaches -3.0. Employing high resolution (R = 50000), high S/N (~ 250) echelle spectra of the two stars found by Israelian et al. (1998) to have the highest [O/Fe]-ratios, viz, BD +23 3130 and BD +37 1458, we conducted abundance analyses based on about 60 Fe I and 7-9 Fe II lines. We determined from Kurucz LTE models the values of the stellar parameters, as well as abundances of Na, Ni, and the traditional alpha-elements, independent of the calibration of color vs TeffT_{eff} scales. We determined oxygen abundances from spectral synthesis of the stronger line (6300 A) of the [O I] doublet. The syntheses of the [O I] line lead to smaller values of [O/Fe], consistent with those found earlier among halo field and globular cluster giants. We obtain [O/Fe] = +0.35 +/- 0.2 for BD +23 3130 and +0.50 +/- 0.2 for BD +37 1458. In the former, the [O I] line is very weak (~ 1 mA), so that the quoted [O/Fe] value may in reality be an upper limit. Therefore in these two stars a discrepancy exists between the [O/Fe]- ratios derived from [O I] and the OH feature, and the origin of this difference remains unclear. Until the matter is clarified, we suggest it is premature to conclude that the ab initio oxygen abundances of old, metal-poor stars need to be revised drastically upward.Comment: 38 pages, 5 tables, 14 figures To appear in July 1999 AJ Updated April 16, 1999. Fixed typo

    Preparing an Election Petition in Missouri

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    Initiative and referendum petitions provide citizens with the power to make and overturn existing laws. Through the initiative petition, the people can compel an election on the question of enacting an amendment to the Missouri Constitution or enacting a proposed law. Through the referendum petition, the people can compel an election to decide whether an existing law should be retained. The procedure to be followed in drafting these petitions is specified in the Constitution and Statutes of Missouri.Reviewed October 1993

    The North Wyke Farm Platform: Methodologies Used in the Remote Sensing of the Quantity and Quality of Drainage Water

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    The North Wyke Farm Platform(NWFP) for agri-environmental research in temperate grassland was established in the UK in 2010 (Orr et al. 2011). Here we describe the instrumentation and methodologies used to monitor the quantity and quality of drainage water at a total of 15 H-flumes draining 5 sub-catchments within three farmlets. Each of 15 flume laboratories is supplied with 3 kW of mains power and connected to both fibre optic and UHF (Ultra High Frequency) radio networks for data exchange. The radio data network also provides telemetry for rain gauges and soil temperature/moisture probes located away from the flumes and within the catchment blocks. Water flow is measured using bubbler flow meters and when flow is above a defined threshold level, water is pumped into bespoke 13-litre stainless steel bypass cells on a 15-minute cycle using bi-directional peristaltic pumps. A range of sensors located within the bypass cells measure the following water quality parameters: nitrate, ammonium, dissolved organic carbon, temperature, conductivity, turbidity, pH and dissolved oxygen. Total phosphorus and ortho phosphorus are measured at one flume in each farmlet. Networked auto-samplers are also provided at each flume site for the measurement of other wa-ter quality parameters as required. All data are logged and sent to a dedicated server at a 15 min resolution while a web front end allows advanced visualization capabilities and remote control of the entire system. The system is configured to allow for flexibility and future expansion to a wider range of parameters

    The North Wyke Farm Platform: A New UK National Capability for Research into Sustainability of Agricultural Temperate Grassland Management

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    The North Wyke Farm Platform is a new UK National Capability that will enable studies that can be closely monitored and controlled under different land-use options at the farm-scale. As a Biotechnology and Biological Sciences Research Council-funded National Capability, the Farm Platform provides centralised scientific facilities including core data (field and water chemistry, water flow rates, greenhouse gas emissions from soils, livestock and agronomic data, and farm management records). Access to the Farm Platform for experimental work or to data will be available to other research users and collaborators. This shared approach will enhance the depth and breadth of information gained for the benefit of the wider community

    TID Tolerance of Popular CubeSat Components

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    In this paper we report total dose test results of COTS components commonly used on CubeSats. We investigate a variety of analog integrated circuits, a popular microcontroller (PIC24) as well as SD memory card
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