10,026 research outputs found
DSIF station schedules
System manages Deep Space Instrumentation Facilities /DSIF/ equipment construction and modification planning. Versatile program applies to such tasks as employee time and task schedules, pay schedules, operations schedules, and plant and equipment procurement, construction, modification or service
A Comparison of the Effect of Single-Sex Versus Mixed-Sex Classes on Middle School Student Achievement
The purpose of this study was to compare the effect of single-sex versus mixedsex classes on middle school student achievement. It was a case study of Stonewall Jackson Middle School in Charleston, West Virginia, an inner-city school with approximately 600 students, of which 30% were minority (mostly black), 30% were special needs, and 70% were classified low socio-economic status (SES). Student WESTEST (West Virginia Educational Standards Test) scores in reading/language arts and math were collected and compared from the school years 2003-2004 and 2004-2005. Each student’s scores from the first year were compared to that same student’s scores from the second year. Each student in the first year (2003-2004) was in mixed-sex classes and each student in the second year (2004-2005) was in single-sex classes. Two hundred seventy nine matched pairs of scores were compared. An alpha level of .05 was set as the criterion for the level of significance. A paired-samples T-test was used to determine whether the difference between the means was statistically significant. Student groups studied were male/female; black/white; low/high SES; and general education/special education. An analysis of variance (ANOVA) was used to determine whether there were differences between groups. A .01 level of significance was found for both reading/language arts and math between mixed-sex and single-sex classes. No significance was found for the between group improvement scores. Results of this study provide support for using single-sex classes to improve the academic achievement of middle school students
Drinking in pregnancy: shifting towards the 'precautionary' principle
Debate rages both in academic circles and in the media over communicating messages to the public regarding alcohol consumption during pregnancy. This chapter considers how research-based evidence is translated into risk communications through three key mechanisms: ‘official’ publications and guidance issued by government departments or health authorities; websites run by advocacy groups; and midwives at the front line in delivering advice to women. The focus is on the UK, and, to a lesser extent, other countries (USA, Australia, New Zealand), where the ‘risk narrative’ around drinking in pregnancy and pressures towards adopting the ‘precautionary principle’ have emerged and strengthened over recent decades
Breeding for improved responsiveness to arbuscular mycorrhizal fungi in onion
Arbuscular mycorrhizal fungi (AMF) play an important role in the uptake of nutrients and water from soil. Onions, Allium cepa L., are plants with a shallow root system. As a result, onion plants need a lot of fertiziler for their growth. Furthermore, onion plants are sensitive to drought. The aim of the current research project is to study the beneficial effect of mycorrhizal fungi on the growth and development of Allium species and to determine whether it is possible to improve onions for mycorrhizal responsiveness by means of breeding. Variation among Allium species and segregation observed in a interspecific tri-hybrid population indicate that selection and thus breeding for high responsiveness to AMF is possible
Calm Down About Common Ownership
Proponents of additional antitrust intervention to police common ownership simply have not made their case. Their theory as to why current levels of intra-industry diversification would cause consumer harm is implausible and the empirical evidence they say demonstrates such harm is both scant and methodologically suspect. The policy solutions they have proposed for dealing with the purported problem would radically rework an industry that has provided substantial benefits to investors, raising the costs of portfolio diversification and enhancing agency costs at public companies. Courts and antitrust enforcers should reject their calls for additional antitrust intervention to police common ownership
The Use of CIR and Airborne Multispectral Scanner Techniques for Wetland Soils Mapping of Highway Corridors
This paper summarizes the results of an investigation aimed at evaluating the potential advantages of state-of-the-art airborne remote sensing for highway siting and planning tasks, specifically in wetlands areas.
The basic objectives of the study were to develop methodologies using remotely sensed data for mapping wetlands soils and drainage, to evaluate the relative merits and usefulness of the various methods developed, to generate a selection of output products from the remote sensor data for display to highway planners and photo-interpreters, and to provide recommendations for implementation of remote sensing techniques in the highway planning and siting process. To accomplish these objectives, remote sensor and ground truth data were acquired for selected test sites in Florida, Michigan, and Minnesota. One of several test sites in Michigan has been selected as representative of the study objectives and methodology
Phosphorus Soil Test Change Following the Addition of Phosphorus Fertilizer to 16 Kentucky Soils
When applying phosphorus to soils it is important to know how much the soil test P changes with the addition of various rates. Soils are different in how they respond to varying rates of application, and only limited information is available for Kentucky soils
Gas Condensation in the Galactic Halo
Using adaptive mesh refinement (AMR) hydrodynamic simulations of vertically
stratified hot halo gas, we examine the conditions under which clouds can form
and condense out of the hot halo medium to potentially fuel star formation in
the gaseous disk. We find that halo clouds do not develop from linear isobaric
perturbations. This is a regime where the cooling time is longer than the
Brunt-Vaisala time, confirming previous linear analysis. We extend the analysis
into the nonlinear regime by considering mildly or strongly nonlinear
perturbations with overdensities up to 100, also varying the initial height,
the cloud size, and the metallicity of the gas. Here, the result depends on the
ratio of cooling time to the time required to accelerate the cloud to the sound
speed (similar to the dynamical time). If the ratio exceeds a critical value
near unity, the cloud is accelerated without further cooling and gets disrupted
by Kelvin-Helmholtz and/or Rayleigh-Taylor instabilities. If it is less than
the critical value, the cloud cools and condenses before disruption. Accreting
gas with overdensities of 10-20 is expected to be marginally unstable; the
cooling fraction will depend on the metallicity, the size of the incoming
cloud, and the distance to the galaxy. Locally enhanced overdensities within
cold streams have a higher likelihood of cooling out. Our results have
implications on the evolution of clouds seeded by cold accretion that are
barely resolved in current cosmological hydrodynamic simulations and absorption
line systems detected in galaxy halos.Comment: 13 pages, 8 figures, submitted to Ap
Reproductive success through high pollinator visitation rates despite self incompatibility in an endangered wallflower
PREMISE OF THE STUDY: Self incompatibility (SI) in rare plants presents a unique challenge—SI protects plants from inbreeding depression, but requires a sufficient number of mates and xenogamous pollination. Does SI persist in an endangered polyploid? Is pollinator visitation sufficient to ensure reproductive success? Is there evidence of inbreeding/outbreeding depression? We characterized the mating system, primary pollinators, pollen limitation, and inbreeding/outbreeding depression in Erysimum teretifolium to guide conservation efforts. METHODS: We compared seed production following self pollination and within- and between-population crosses. Pollen tubes were visualized after self pollinations and between-population pollinations. Pollen limitation was tested in the field. Pollinator observations were quantified using digital video. Inbreeding/outbreeding depression was assessed in progeny from self and outcross pollinations at early and later developmental stages. KEY RESULTS: Self-pollination reduced seed set by 6.5× and quadrupled reproductive failure compared with outcross pollination. Pollen tubes of some self pollinations were arrested at the stigmatic surface. Seed-set data indicated strong SI, and fruit-set data suggested partial SI. Pollinator diversity and visitation rates were high, and there was no evidence of pollen limitation. Inbreeding depression (δ) was weak for early developmental stages and strong for later developmental stages, with no evidence of outbreeding depression. CONCLUSIONS: The rare hexaploid E. teretifolium is largely self incompatible and suffers from late-acting inbreeding depression. Reproductive success in natural populations was accomplished through high pollinator visitation rates consistent with a lack of pollen limitation. Future reproductive health for this species will require large population sizes with sufficient mates and a robust pollinator community
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