11,799 research outputs found
An investigation of the role of current and future remote sensing data systems in numerical meteorology
A flexible system for performing observing system simulation experiments which made contributions to meteorology across all elements of the observing system simulation experiment (OSSE) components was developed. Future work will seek better understanding of the links between satellite-measured radiation and radiative transfer in the clear, cloudy and precipitating atmosphere and investigate how that understanding might be applied to improve the depiction of the initial state and the treatment of physical processes in forecast models of the atmosphere
Transport pathways of polychlorinated biphenyls in Atlantic water
The distribution of polychlorinated biphenyls (PCBs) in the surface waters of the Atlantic shows concentration maxima in latitudes of high net precipitation and a minimum in the midlatitudes. Very low PCB concentrations are found in the South Atlantic. Since the nonvolatile inorganic radionuclide distribution in the Atlantic shows no dependence on precipitation patterns, codistillation with evaporating water must be a major factor in determining the distribution of PCBs...
Sociologic factors in the spread of epidemic hepatitis in a rural school district
An epidemic of epidemic hepatitis occurred in the district of a rural Central School in Yates and Ontario Counties of Central New York. The epidemic comprised 176 cases of which 135 were jaundiced, and extended from September 1949 to May 1950, with most cases in March 1950. No common source could be demonstrated and the transmission was believed to be due to human contact alone. The overall morbidity rate was about 5%, attack rate among school children 22%, and among the adults and pre-school family contacts of infected school children the attack rate was 18%, with no significant age difference in attack rate. Differences in attack rate in the various school grades were explained by higher number of siblings of children in certain grades. Household attack rates among non-school persons were related to number of sick school children, family size, and hygienic standard of the home. The first of these factors seemed most important. More jaundiced cases occurred in families where the exposure was heavies
An Evolutionary Game Theory Explanation of ARCH Effects
While ARCH/GARCH equations have been widely used to model financial market data, formal explanations for the sources of conditional volatility are scarce. This paper presents a model with the property that standard econometric tests detect ARCH/GARCH effects similar to those found in asset returns. We use evolutionary game theory to describe how agents endogenously switch among different forecasting strategies. The agents evaluate past forecast errors in the context of an optimizing model of asset pricing given heterogeneous agents. We show that the prospects for divergent expectations depend on the relative variances of fundamental and extraneous variables and on how aggressively agents are pursuing the optimal forecast. Divergent expectations are the driving force leading to the appearance of ARCH/GARCH in the data. JEL Classification: C22, C73, G12, D84 Keywords:ARCH, autoregressive conditional heteroskedasticity, evolutionary game theory, rational expectations
NSF-style peer review for teaching undergraduate grant-writing
The Biology Department at Jacksonville State University (JSU) in Alabama has incorporated an undergraduate research experience (URE) into its curriculum for both BA and BS degree programs . This experience involves the following semester courses: • BY 370 (Introduction to Research in Biology): two semester credits, sophomore level • BY 327 (Directed Studies in Biology) or BY 427 (Independent Study in Biology): variable credits, junior year • BY 496 (Senior Seminar) two credits, senior level The Department has recognized the need for both substantive coursework and an undergraduate research experience in its biology curriculum . The JSU URE is the outcome of curricular revision over the past 14 years . BY 370 and BY 496 are required courses, whereas independent research involves optional courses intended to interest students in research. BY 327 and BY 427 had been in the curriculum for some time, available for student research projects under the tutelage of a faculty mentor . BY 370 was initiated in 1991 to introduce majors to the science and art of biological research and grant-writing in an effort to strengthen the outcome of BY 327 and BY 427 . This course is now offered with multiple sections and instructors both semesters every year . Today, BY 327 and BY 427 enable students to conduct original field and/or laboratory research, educational research in biology, or substantive library-based research of an approved biological topic . BY 496, a required course since 2002, involves both a senior thesis and an oral presentation, the latter given in a department-wide symposium format . BY 496 is the Biology Department’s capstone course for all matriculating biology majors . The overall URE Experience has enabled the Department to integrate “communication across its curriculum” in a way that was never possible before . This paper concerns a modification to BY 370 . In this course, students now actively participate in an NSF-style peer review of their own undergraduate research proposals in biology
Investigation of Ceramic, Graphite, and Chrome-plated Graphite Nozzles on Rocket Engine
The use of ceramic material for rocket nozzles and the effectiveness of preventing oxidation and erosion of graphite nozzles by chrome-plating the internal surface were investigated. A supported ceramic nozzle, cracked by initial operation, was operated a second time without further cracking or damage. Chrome-plating the internal surface of graphite nozzles effectively prevented oxidation and erosion that occurred during operation with unprotected graphite
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