4,923 research outputs found
Solar array electrical performance assessment for Space Station Freedom
Electrical power for Space Station Freedom will be generated by large Photovoltaic arrays with a beginning of life power requirement of 30.8 kW per array. The solar arrays will operate in a Low Earth Orbit (LEO) over a design life of fifteen years. This paper provides an analysis of the predicted solar array electrical performance over the design life and presents a summary of supporting analysis and test data for the assigned model parameters and performance loss factors. Each model parameter and loss factor is assessed based upon program requirements, component analysis, and test data to date. A description of the LMSC performance model, future test plans, and predicted performance ranges are also given
Soft-Shell Clam (Mya Arenaria) Distribution & Abundance at Selected Sites in the Great Bay Estuary
Previous surveys (1996 to 2002) provided distribution and abundance data for soft-shell clam (Mya arenaria) populations in ten areas of the Great Bay and Piscataqua River estuaries identified as potentially good clam habitat. The present study was designed to complete the overall survey by sampling six remaining areas: Weeks Point, Brackett\u27s Point, Squamscott River mouth, Moody Point, Herods Cove, and Upper Little Bay (western shore). The objectives of the present project were to: (1) visually inspect the six study areas for the general distribution of sediment types and soft-shell clams, (2) quantitatively sample the six areas to determine densities of soft-shell clams, (3) produce GIS maps based on the survey data, and (4) assess clam distributions considering data from the present study and previous research. At each of the six sampling areas, the approximate boundary of potential clam habitat (=intertidal soft sediments) was determined by visual inspection at low tide. Notes were made on changes in major sediment types, the presence of clam siphon holes, and empty clam shells. At each site, nine to fourteen 0.125 m2 quadrats were haphazardly tossed onto the sediment surface, excavated to at least 20 cm depth using clam rakes, and all excavated sediments washed through a 5 mm mesh sieve. All clams retained on the sieve were measured (shell length to nearest mm with calipers), counted, and returned to the general area. A sample of the upper 5 cm of sediment was collected from each quadrat and stored at Jackson Estuarine Laboratory. Quadrat locations were geo-referenced using DGPS.The general environmental conditions in all six areas appeared suitable as soft-shell clam habitat. However, very few live clams were collected and very few empty shells were observed. From a total of 65 excavated quadrats, only 8 live clams were collected with mean densities ranging from 0.0 to 3.1/m2 at the six sites. It was concluded that none of the six areas were productive clam flats at the time of sampling, and they probably had not been in the recent past. Previous research and the present study indicate that many of the expansive intertidal flats in the Great Bay/Piscataqua River system have not been productive clam habitat for decades, probably since at least the 1940s in some areas. However, moderate to high densities of clams have been reported in some areas, particularly in sandy sediments. Previous research also showed high densities of early post-set clams in some areas, suggesting that spat mortality (probably predation effects) may be an important cause of low densities of larger clams in these areas. Future research should focus on sandy sediments and mixed soft sediments with cobble to better characterize the distribution and abundance of clams in the Great Bay/Piscataqua River system. Future research also should assess the role of predation on newly set spat in controlling clam populations
Guidelines for Selecting Professional Development for Early Childhood Teachers
Engaging teachers of young children in effective in-service professional development is a critical component of establishing high quality early childhood education. However, not all professional development offerings are effective in imparting new knowledge, enhancing teacher practice, or improving child outcomes, making it difficult for teachers and directors to select professional development that will benefit their centers. This paper critically reviews the research literature on professional development for early childhood education to identify what features of professional development make a difference for teacher interactions and children’s learning and development. Guidance is provided for selecting professional development opportunities which meet the needs of children and teachers. Recommendations for how to create an ongoing professional development program within an early childhood center by creating a professional learning community are also made. Such an approach supports the center to become a place that values learning and continued education for all professionals
Fostering Student Agency to Build a Whole Child, Whole School, Whole Community Approach
In this practitioner perspective, we explore the concept of student agency through the implementation of a student government association in a laboratory middle school. Interviews with a social studies teacher and her students offer perspectives of the impact of student voice and choice for student experiences. We describe three major lessons learned through this implementation process: students learn to have healthy conflict and cooperative skills; students learn the appropriate processes to enact change in a democratic society; and students learn to conduct service for their peers, school, and community
Trade and Integration of the US and China’s Cotton Markets
The cotton market in China is highly interactive with international markets, especially, the US market. The prices in these two markets can reveal important market relations. Investigating the data of futures prices from the New York Board of Trade (NYBOT) and the Zhengzhou Commodity Exchange (CZCE) using several time series methods, we find a long-run cointegration relationship between these I(1) series. Furthermore, a bi-directional Granger Causality between these two futures markets is detected with Generalized Autoregressive Conditional Heteroskedasticity (GARCH) error specifications. We also find the relationship is impacted by the Chinese exchange rate policy change in the 2005.cotton futures prices, cointegration, granger causality test, AR-GARCH, Agricultural Finance, Demand and Price Analysis, International Relations/Trade,
Implication of Cotton Price Behavior on Market Integration
The cotton market in China is highly interactive with international markets, especially, the US market. The prices in these two markets can reveal important market relations. Investigating the data of futures prices from the New York Board of Trade (NYBOT) and the Zhengzhou Commodity Exchange (CZCE) using several time series methods, we find a long-run cointegration relationship between these I(1) series. Furthermore, a bi-directional Granger Causality between these two futures markets is detected with Generalized Autoregressive Conditional Heteroskedasticity (GARCH) error specifications. We also find the relationship is impacted by the Chinese exchange rate policy change in the 2005.cotton futures prices, cointegration, granger causality test, AR-GARCH., Agricultural Finance,
Personality sex-roles and family variables : a comparison of bulimics and binge-eaters in a college population
Structure from Nothing and Claims for Free: Using a Whole-System View of the Patent System to Improve Notice and Predictability for Software Patents
No uniform or customary method of disclosure for software patents is currently employed by inventors. This Note examines the issues that develop from software patent claims disclosed at various levels of abstraction, and the difficulties encountered by courts and the public when investigating the contours of the software patent space. While the courts have placed some restrictions on the manner in which software inventions are claimed, they are easily bypassed by clever patent applicants who desire to claim the maximum scope of their inventions. In the long run, however, a large “patent thicket” of overlapping and potentially overbroad inventions will work against the interests of inventors who desire to enforce their temporary technological monopolies. A confused field of inventions, when combined with a variety of abstracted disclosures, will result in unpredictable litigation and potentially invalidation of software as a patentable subject completely. Software patentees, like all patent holders, benefit greatly from robust and fair patent protection. In order to achieve the goal of a patent system that effectively balances the rights of the inventor with the right of the public in the interest of progress, however, this Note argues that patentees must recognize their critical role in the patent system and disclose the invention in code or pseudo-code at a level of abstraction that will allow the software community to effectively recreate the invention
EVALUATING SAMPLING STRATEGIES FOR RAINFALL SIMULATION STUDIES AND SURFACE TRANSPORT OF ANTIBIOTICS FROM SWINE MANURE APPLIED TO FESCUE PLOTS
Antibiotics are commonly used in animal agriculture to treat and prevent diseases and promote growth. Unfortunately, large amounts of antibiotics are not metabolized, but instead are excreted in urine and feces. Rainfall simulation studies were used to investigate the transport of the antibiotic oxytetracycline and various constituents in runoff and the ability of alum to reduce pollutant transport. Runoff samples were collected at several points during the simulated storm event from each of four treatments: control (C), manure only (M), manure and antibiotics (MA), and manure, antibiotics and alum (MAA). Flow-weighted composite samples were created and compared to the flow weighted mean concentration (FWMC). Constituents with concentrations well-above the detection limits (E. coli, NH4-N, turbidity, TSS, TOC, and EC) showed a strong correlation between flow-weighted composite samples and FWMC. When constituent concentrations were at or near the detection limits, errors associated with the composite samples were magnified. Oxytetracycline concentrations had the strong correlation to E. coli, Cl, TOC, TSS, and turbidity suggesting that a BMP effective at trapping sediment or particulates may work best for reducing oxytetracycline concentrations in runoff. Alum (1%) did not reduce levels of oxytetracycline in runoff. It is recommended that higher doses of alum be tested
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