Using global student rating items for summative evaluation.

Research has established the multidimensional nature of student ratings of teaching, but debate continues concerning the use of multiple- vs single-item ratings for summative evaluation. In this study, the usefulness of global items in predicting weighted-composite evaluations of teaching was evaluated with a sample of 17,183 classes from 105 institutions. In separate regression analyses containing 2 global items—one concerning the instructor, the other concerning the course—each global item accounted for more than 50% of the variance in the weighted-composite criterion measure. Student, class, and method items generally added much less variance. Results suggested that, because global items accounted for a substantial amount of the variance, a short and economical form could capture much of the information needed for summative evaluation and longer diagnostic forms could be reserved for teaching improvement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional modulation of visual processes in motion perception.

Examined the effects of spatially directed attention on the temporal characteristics of information transmission in the visual system. A 2-stimulus, 2-flash, long-range motion display was used. The results showed that attending to 1 of the 2 stimuli altered the perceived direction of motion, the pattern of motion and no-motion responses, and ratings of motion quality. The results were compared with predictions derived from 2 conceptual frameworks of attention: a temporal-profile model and an additive account. The results support the temporal-profile model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Utilization of digital image processing to study dynein arms (ATPase) in normal and immotile cilia

Tracheal ciliary cross sections were examined with scanning transmission electron microscopy and the resultant images were digitized for image enhancement. A gray-scale histogram of each ciliary image was produced and manipulated to enhance the image for dynein arms. Tracheal epithelial tissue from the pig, rabbit, and dog, including dogs with immotile cilia syndrome, was examined by using this technique. Tissue from each animal was fixed with each of three different fixatives and sections were evaluated for preservation of dynein arms. The same fixative did not consistently provide optimal fixation for ciliary dynein arms in all three species examined. Each species, therefore, must be evaluated to determine the optimal fixative for preservation of normal ciliary ultrastructure. Digital image processing provides a mechanism for enhancing dynein arms in situ without the need for addition of special stains or the use of techniques such as image summation. With this technique it has been shown that about two-thirds of outer dynein arms are partially or completely missing on cilia from dogs with immotile cilia syndrome.     

Electrical switching in the three terminal double heterostructure opto-electronic switching device—Active layer contact

Electrical switching times in the three terminal double heterostructure opto-electronic switch are measured and analyzed. For a discrete device with a large parasitic input-output capacitance a switch-on time of 4 ns and a switch-off time of 26 ns were obtained. It is shown that the speed was limited by the time constant determined by the relatively large device capacitance of the discrete device and the 50 Ω measurement impedance of a matched system. Both of these parameters would be considerably reduced by device integration.     

The programming language standards scene, ten years on Paper 4: Cobol

This paper, one of a simultaneously published set on ten years of activity in programming language standards, describes the developments in standardization of the programming language Cobol which have taken place in the period 1983–1993.     

Structural effects on equilibria and rates of metal extraction

The correlations by linear free energy relationships (LFER) of published equilibrium and rate data on metal extraction by organic compounds are discussed. The extraction equilibria concerning one metal and a series of structurally related extractants can be successfully correlated by the Hammett or Taft equations. For rate data, the correlation with partition coefficients of the extractants between organic phase and water, estimated from structural fragments, seems to be possible. The requirements on the quality of rate data are discussed. The approach is promising with respect to the prediction of extractant performance.     

Efficiency and equity considerations in financing agricultural research and extension

Benefits resulting from agricultural research and extension activities conducted in one region may affect producers and consumers throughout the country. Measurement of these benefit spillovers is required to equitably and efficiently finance these activities. Spillover benefit ratios per dollar of internal benefits for all farm production regions in the United States are calculated using an economic surplus framework to account for the effects of research and extension on both producers and consumers. In nine out of ten regions, the spillover ratios are greater than one, indicating that benefits accruing outside the region conducting research and extension activities are greater than the benefits accruing internally to the region. The average spillover ratio, which is 3.71 for all regions, is greater than the ratio of federal expenditures to regional expenditures. The implication of these ratios being unequal is that the federal contribution would need to be increased in order for regional costs to match regional benefits.