6,518 research outputs found
ECUT: Energy Conversion and Utilization Technologies program. Industry, university and research interest in the US Department of Energy ECUT biocatalysis research activity
The results of a Research Opportunity Notice (RON) disseminated by the Jet Propulsion Laboratory for the U.S. Department of Energy Conversion and Utilization Technologies (ECUT) Program's Biocatalysis Research Activity are presented. The RON was issued in late April of 1983 and solicited expressions of interest from petrochemical and chemical companies, bioengineering firms, biochemical engineering consultants, private research laboratories, and universities for participating in a federal research program to investigate potential applications of biotechnology in producing chemicals. The RON results indicate that broad interest exists within the nation's industry, universities, and research institutes for the Activity and its planned research and development program
ECUT: Energy Conversion and Utilization Technologies program. Chemical Processes project report, FY 1982
Planned research efforts and reorganization of the Project as the Biocatalysis Research Activity are described, including the following topics: electrocatalysts, fluid extraction, ammonia synthesis, biocatalysis, membrane fouling, energy and economic analysis, decarboxylation, microscopic reaction models, plasmid monitoring, and reaction kinetics
Upper-division Student Understanding of Coulomb's Law: Difficulties with Continuous Charge Distributions
Utilizing the integral expression of Coulomb's Law to determine the electric
potential from a continuous charge distribution is a canonical exercise in
Electricity and Magnetism (E&M). In this study, we use both think-aloud
interviews and responses to traditional exam questions to investigate student
difficulties with this topic at the upper-division level. Leveraging a
theoretical framework for the use of mathematics in physics, we discuss how
students activate, construct, execute and reflect on the integral form of
Coulomb's Law when solving problems with continuous charge distributions. We
present evidence that junior-level E&M students have difficulty mapping
physical systems onto the mathematical expression for the Coulomb potential.
Common challenges include difficulty expressing the difference vector in
appropriate coordinates as well as determining expressions for the differential
charge element and limits of integration for a specific charge distribution. We
discuss possible implications of these findings for future research directions
and instructional strategies.Comment: 5 pages, 1 figure, 2 tables, accepted to 2012 PERC Proceeding
Cost Metrics for Unmanned Aerial Vehicles
This paper aims to enhance the understanding of UAV cost metrics and their uses. The
paper is organized into three main areas: (1) overview of current approaches for aircraft, (2)
life cycle issues with UAV cost estimation, and (3) cost metrics and model approach as
applied to UAVs. As a result of this work we hope to provide a better understanding of the
cost factors influencing the recently publicized scrutiny of UAV cost overruns. More
importantly, we hope to begin the foundation for the development of Cost Estimating
Relationships (CERs) that can potentially lead to the development of a parametric cost
model for UAVs
ACER: A Framework on the Use of Mathematics in Upper-division Physics
At the University of Colorado Boulder, as part of our broader efforts to
transform middle- and upper-division physics courses, we research students'
difficulties with particular concepts, methods, and tools in classical
mechanics, electromagnetism, and quantum mechanics. Unsurprisingly, a number of
difficulties are related to students' use of mathematical tools (e.g.,
approximation methods). Previous work has documented a number of challenges
that students must overcome to use mathematical tools fluently in introductory
physics (e.g., mapping meaning onto mathematical symbols). We have developed a
theoretical framework to facilitate connecting students' difficulties to
challenges with specific mathematical and physical concepts. In this paper, we
motivate the need for this framework and demonstrate its utility for both
researchers and course instructors by applying it to frame results from
interview data on students' use of Taylor approximations.Comment: 10 pages, 1 figures, 2 tables, accepted to the 2012 PERC Proceeding
Systematic review of antimicrobial drug prescribing in hospitals.
Prudent antibiotic prescribing to hospital inpatients has the potential to reduce the incidences of antimicrobial resistance and healthcare-associated infection. We reviewed the literature from January 1980 to November 2003 to identify rigorous evaluations of interventions to improve hospital antibiotic prescribing. We identified 66 studies with interpretable data of which 16 reported 20 microbiological outcomes: Gram negative resistant bacteria (GNRB), 10 studies; Clostridium difficile associated diarrhoea (CDAD), 5 studies; vancomycin resistant enterococci (VRE), 3 studies and methicillin resistant Staphylococcus aureus (MRSA), 2 studies. Four studies provide good evidence that the intervention changed microbial outcomes with low risk of alternative explanations, eight studies provide less convincing evidence and four studies were negative. The strongest and most consistent evidence was for CDAD but we were able to analyse only the immediate impact of interventions because of nonstandardised durations of follow up. The ability to compare results of studies could be substantially improved by standardising methodology and reporting
Study of the relationship between solar activity and terrestrial weather
Evidence for some connection between weather and solar related phenomena is presented. Historical data of world wide temperature variations with relationship to change in solar luminosity are examined. Several test methods for estimating the statistical significance of such phenomena are discussed in detail
Hot Stars and Cool Clouds: The Photodissociation Region M16
We present high-resolution spectroscopy and images of a photodissociation
region (PDR) in M16 obtained during commissioning of NIRSPEC on the Keck II
telescope. PDRs play a significant role in regulating star formation, and M16
offers the opportunity to examine the physical processes of a PDR in detail. We
simultaneously observe both the molecular and ionized phases of the PDR and
resolve the spatial and kinematic differences between them. The most prominent
regions of the PDR are viewed edge-on. Fluorescent emission from nearby stars
is the primary excitation source, although collisions also preferentially
populate the lowest vibrational levels of H2. Variations in density-sensitive
emission line ratios demonstrate that the molecular cloud is clumpy, with an
average density n = 3x10^5 cm^(-3). We measure the kinetic temperature of the
molecular region directly and find T_H2 = 930 K. The observed density,
temperature, and UV flux imply a photoelectric heating efficiency of 4%. In the
ionized region, n_i=5x10^3 cm^(-3) and T_HII = 9500 K. In the brightest regions
of the PDR, the recombination line widths include a non-thermal component,
which we attribute to viewing geometry.Comment: 5 pages including 2 Postscript figures. To appear in ApJ Letters,
April 200
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