1,992 research outputs found
Circular Dichroism of RbHe and RbN Molecules
We present measurements of the circular dichroism of optically pumped Rb
vapor near the D1 resonance line. Collisions with the buffer gases He and
N reduce the transparency of the vapor, even when fully polarized. We use
two methods to measure this effect, show that the He results can be understood
from RbHe potential curves, and show how this effect conspires with the
spectral profile of the optical pumping light to increase the laser power
demands for optical pumping of very optically thick samples
An analysis of pilot error-related aircraft accidents
A multidisciplinary team approach to pilot error-related U.S. air carrier jet aircraft accident investigation records successfully reclaimed hidden human error information not shown in statistical studies. New analytic techniques were developed and applied to the data to discover and identify multiple elements of commonality and shared characteristics within this group of accidents. Three techniques of analysis were used: Critical element analysis, which demonstrated the importance of a subjective qualitative approach to raw accident data and surfaced information heretofore unavailable. Cluster analysis, which was an exploratory research tool that will lead to increased understanding and improved organization of facts, the discovery of new meaning in large data sets, and the generation of explanatory hypotheses. Pattern recognition, by which accidents can be categorized by pattern conformity after critical element identification by cluster analysis
Buffalo National River Ecosystems - Part II
The priorities were established for the Buffalo National River Ecosystem Studies through meetings and correspondence with Mr. Roland Wauer and other personnel of the Office of Natural Sciences, Southwest Region of the National Park Service. These priorities were set forth in the appendix of contract no. CX 700050443 dated May 21, 1975
Thermal/structural analysis of a transpiration cooled nozzle
The 8-foot High Temperature Tunnel (HTT) at LaRC is a combustion driven, high enthalpy blow down wind tunnel. In Mar. 1991, during check out of the transpiration cooled nozzle, pieces of platelets were found in the tunnel test section. It was determined that incorrect tolerancing between the platelets and the housing was the primary cause of the platelet failure. An analysis was performed to determine the tolerance layout between the platelets and the housing to meet the structural and performance criteria under a range of thermal, pressure, and bolt preload conditions. Three recommendations resulted as a product of this analysis
Breakdown of Angular Momentum Selection Rules in High Pressure Optical Pumping Experiments
We present measurements, using two complementary methods, of the breakdown of
atomic angular momentum selection rules in He-broadened Rb vapor. Atomic dark
states are rendered weakly absorbing due to fine-structure mixing during Rb-He
collisions. The effect substantially increases the photon demand for optical
pumping of dense vapors
Evidence of clonal budding in a radial cluster of Paraconularia crustula (White) (Pennsylvanian: ?Cnidaria)
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73153/1/j.1502-3931.1992.tb01645.x.pd
Buffalo National River Ecosystem - Part III
Samples for water quality analyses and phycological studies were taken from the nine standard sampling locations on the Buffalo River nine times during the period from March 1976 through February 1977. The April-June 1976 samples represent nearly identical conditions throughout the spring period; therefore, emphasis was placed on taxonomic research. As the early January sample was considered sufficient~y reflective of stable winter conditions, the December and February periods were. used for detailed microscopic examination of the rich and diverse diatom flora that was found in the river this year. A total of 273 taxa of diatoms were identified from the 75 samples collected, including 123 new additions to the diatom flora of the Buffalo River. Details of this study, including the breakdown of many species into varieties, will be presented in a separate paper. A list of the new species found and a general discussion are included in this report
Classification and Ranking of Selectd Arkansas Lakes
Trophic-state related problems associated with waters in the United States have generated tremendous public interest and concern, particularly during the past decade. These interests and concerns led to Public Law 92-500, the mandate by Congress known as the Federal Water Pollution Control Act. Various sections of PL 92-500 directly address the need for trophic-state analyses, particularly Section 314 referred to as the Clean Lakes Program which assigns states the responsibility for classifying their lakes according to water quality, identifying methods of pollution control and restoring those lakes which have become degraded
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