Study of the growth parameters involved in synthesizing boron carbide filaments Second quarterly report

Growth parameters in synthesis of boron carbide whisker

Adverse effects of differential parental attention

In two independent parent training projects (Kansas and Mississippi), mothers of deviant young children were observed to follow almost all child behaviors with attention. The mothers were then trained to use differential attention procedures to increase their child's appropriate behaviors and to decrease deviant behaviors. Contrary to expectations, the differential attention procedure produced substantial increases in deviant behavior for four of the children. This adverse effect was maintained over many sessions and was replicated in single organism, reversal designs. A fifth child showed no change. A sixth child showed some improvement. However, this effect was not recovered in a second application of differential attention, and the child became worse. The results underline the importance of subject generality in applied behavior analysis and strongly suggest that service programs using operant techniques must carefully evaluate their effects on behavior

Evaluating ice-rafted debris as a proxy for glacier calving in Upernavik Isfjord, NW Greenland

International audienceRecords of ice‐rafted debris (IRD) in sediments are commonly used as a proxy for iceberg production and to reconstruct past changes of glacier stability. However, the interpretation of IRD is complex as multiple processes modulate its variability. This study investigates the relationship between IRD variability and glaciological change by measuring IRD records from Upernavik Fjord and comparing these to frontal positions of Upernavik Isstrøm during the past century. Results show that the spatial variability of IRD deposition throughout the fjord is high, indicating that randomness inherent to IRD distorts the calving signal. However, we investigate whether IRD records can be combined to improve the reconstruction, as previously suggested, and show the importance of core site selection and number of cores on this approach. The outer‐fjord core compares relatively well to the observed front positions and this is reflected in the composite record: increased IRD deposition in 1937–1946, 1968–1980, and 1996–1999 occurred during periods of faster retreat. Comparison with climatic records shows that the calving episodes in the late ‘30 s/early ‘40 s and late ‘90 s are related to warm ocean and air temperatures, whereas intensified retreat and calving during the ‘70 s reflects partly an internal glacier response to the fjord geometry