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Sediment accumulation within weathering pits on Dance Hall Rock, Grand Staircase-Escalante National Monument, Utah
The purpose of this paper was to examine if the depth and degree of circularity of weathering pits affects the accumulation of sediment. Thirty pits were surveyed over two one-week periods on Dance Hall Rock. Weathering pits were measured to determine their maximum width, minimum width, vertical depth, and depth of pit-floor sediment. Additional descriptions of sediment texture, topographic position, orientation, weathering debris, evidence of particle movement by wind, and vegetation were also completed in situ. Stepwise multiple regression was performed using SPSS version 10. Vertical pit depth and an index of circularity were selected as the independent variables with sediment depth functioning as the dependent variable. Initial evaluation of the variables indicated that they were not normally distributed, therefore two regression models were developed to assess how the raw data and transformed data affected the model's explanatory ability. Although both models indicated that the depth and degree of circularity of a pit made significant contributions in explaining the variation in sediment depth, the residuals displayed sufficient non-normality to suggest that neither model was a "good fit". Field observations and statistical analysis indicate that these two measures of pit shape, alone, cannot account for all the variation in sediment depth. Rather that the accumulation and deflation of sediment is a complex process involving the interaction of numerous physical and biological factors
Quantitative analysis of MicroRNAs in vaccinia virus infection reveals diversity in their susceptibility to modification and suppression
Vaccinia virus (VACV) is a large cytoplasmic DNA virus that causes dramatic alterations to many cellular pathways including microRNA biogenesis. The virus encodes a poly(A) polymerase which was previously shown to add poly(A) tails to the 3' end of cellular miRNAs, resulting in their degradation by 24 hours post infection (hpi). Here we used small RNA sequencing to quantify the impact of VACV infection on cellular miRNAs in human cells at both early (6 h) and late (24 h) times post infection. A detailed quantitative analysis of individual miRNAs revealed marked diversity in the extent of their modification and relative change in abundance during infection. Some miRNAs became highly modified (e.g. miR-29a-3p, miR-27b-3p) whereas others appeared resistant (e.g. miR-16-5p). Furthermore, miRNAs that were highly tailed at 6 hpi were not necessarily among the most reduced at 24 hpi. These results suggest that intrinsic features of human cellular miRNAs cause them to be differentially polyadenylated and altered in abundance during VACV infection. We also demonstrate that intermediate and late VACV gene expression are required for optimal repression of some miRNAs including miR-27-3p. Overall this work reveals complex and varied consequences of VACV infection on host miRNAs and identifies miRNAs which are largely resistant to VACV-induced polyadenylation and are therefore present at functional levels during the initial stages of infection and replication
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