As microelectronic parts trend smaller so do their solder joints. The surface finish on a copper pad is expected to become a significant part of the total solder joint volume and therefore affect mechanical properties of the smaller solder joints. Two sample geometries and four different surface finishes for tin-silver-copper...
The purpose of this study was to address the implementation fidelity of one part of a professional development model developed by the Northwest Regional Educational Laboratory (NWREL). Specifically, this research investigates middle school teachers’ use of a formative feedback guide developed by NWREL staff, examining the reliability with which teachers...
The lentil strain of pea seedborne mosaic virus, PSbMV-L, was
distinguished from the standard isolates of PSbMV by a natural inoculum
reservoir in lentil seed and by separate resistance genes in Pisum
and Lens. PSbMV-L was intermediate in symptom severity between the
standard and New Zealand isolates of PSbMV.
Seed...
An experiment was conducted to evaluate the influence of forest fuels reduction on diet quality, botanical composition, relative preference, and foraging efficiency of beef cattle grazing at different stocking rates. A split plot factorial design was used, with whole plots (3 ha) being fuel reduced or no treatment (control), and...
Hybrids with abnormal development were obtained when particular
genotypes of Phaseolus vulgaris L. were crossed. The phenotypic
aberrations of the F₁s included retarded growth, chlorosis of the
trifoliate leaves and the formation of adventitious roots on the
hypocotyls. The expression of the abnormalities was dependent on the
temperature. At high...
The purpose of this article is to explore student reasoning with regard to problems in logic, particularly those related to the Principle of Mathematical Induction (PMI). The five case studies presented build off of work done by other researchers, most notably Dubinsky and Harel, who both looked at how students'...
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Thomas P. Dick
The purpose of this article is to explore student reasoning with regard to
Responses of biological indicators of soil quality to winter cover cropping were measured on soil samples collected from 6 commercial growers' fields and two experiment research stations in the Willamette Valley of Oregon. The research stations were the North Willamette Research and Extension Center (Aurora, OR), and the Oregon State...
The purpose of this study was to investigate teaching models that may aid in
improving student's understanding of how to interpret graphs of kinematic variables.
The teaching models that were considered incorporated the use of cooperative groups
and calculator-based laboratory instruments, alone and in concert. The subjects used in
this...