Notes on Iowa Diatoms IV. : The Diatoms in a Northwest Iowa Fen

The physical features of a fen are discussed including chemical and physical analyses of the water. Diatom samples were taken during the summer of 1962 and a list of 48 species distributed among 20 genera was compiled. A series of photomicrographs of some of the species is presented. Ecological and floristic differences between cold and warm pools are discussed and a comparison with the diatom flora of the Cabin Creek Raised Bog in Indiana (published by C. W. Reimer) is made

Variable‐Threshold Behavior in Rivers Arising From Hillslope‐Derived Blocks

Geomorphologists often rely on simple models of river channel incision for predicting rates of landscape evolution and channel response to perturbations, as well as extracting climatic and tectonic signals from river longitudinal profiles. Recent work has shown that large, hillslope‐derived blocks delivered to rivers may noticeably alter the form and evolution of river profiles from the behavior predicted by the most common models. Here we use a 1‐D model of river reach erosion and hillslope block delivery to explore the conditions under which block delivery strongly influences channel evolution. We use global sensitivity analysis to understand which model parameters most strongly affect the channel longitudinal profile. We explore the effects of blocks on the relationship between erosion rate and channel gradient, and on the erosion rate‐channel steepness exponent ϕ, and find that block effects result in highly variable slope and ϕ over the range of erosion rates and climatic conditions (discharge mean and variability) tested. The influence of blocks on erosion rate‐slope scaling may be approximated by a piecewise model: The erosion threshold imposed by blocks scales linearly with erosion rate when blocks are infrequently mobile and remains constant when blocks are frequently mobile. We explore the implications of this variable‐threshold model for the erosion rate‐channel steepness relationship and find that erosion rate‐dependent thresholds imposed by hillslope‐derived blocks cause significant departures from previous models but may be consistent with existing field data sets. Our work has implications for landscape evolution modeling and the inversion of channel profiles for forcing information

Subliminal versus supraliminal stimuli activate neural responses in anterior cingulate cortex, fusiform gyrus and insula:a meta-analysis of fMRI studies

Background: Non-conscious neural activation may underlie various psychological functions in health and disorder. However, the neural substrates of non-conscious processing have not been entirely elucidated. Examining the differential effects of arousing stimuli that are consciously, versus unconsciously perceived will improve our knowledge of neural circuitry involved in non-conscious perception. Here we conduct preliminary analyses of neural activation in studies that have used both subliminal and supraliminal presentation of the same stimulus. Methods: We use Activation Likelihood Estimation (ALE) to examine functional Magnetic Resonance Imaging (fMRI) studies that uniquely present the same stimuli subliminally and supraliminally to healthy participants during functional magnetic resonance imaging (fMRI). We included a total of 193 foci from 9 studies representing subliminal stimulation and 315 foci from 10 studies representing supraliminal stimulation. Results: The anterior cingulate cortex is significantly activated during both subliminal and supraliminal stimulus presentation. Subliminal stimuli are linked to significantly increased activation in the right fusiform gyrus and right insula. Supraliminal stimuli show significantly increased activation in the left rostral anterior cingulate. Conclusions: Non-conscious processing of arousing stimuli may involve primary visual areas and may also recruit the insula, a brain area involved in eventual interoceptive awareness. The anterior cingulate is perhaps a key brain region for the integration of conscious and non-conscious processing. These preliminary data provide candidate brain regions for further study in to the neural correlates of conscious experience

Price discovery in emissions permit auctions

Objective - This chapter examines the performance of the market to discover efficient equilibrium under alternative auction designs. Background - Auctions are increasingly being used to allocate emissions allowances ("permits") for cap and trade and common-pool resource management programs. These auctions create thick markets that can provide important information about changes in current market conditions. Methodology - This chapter uses experimental methods to examine the extent to which the predicted increase in the Walrasian price due to a shift in willingness to pay (perhaps due to a shift in costs of pollution abatement) is reflected in observed sales prices under alternative auction formats. Results - Price tracking is comparably good for uniform-price sealed-bid auctions and for multi-round clock auctions, with or without end-of-round information about excess demand. More price inertia is observed for "pay as bid" (discriminatory) auctions, especially for a continuous discriminatory format in which bids could be changed at will, in part because "sniping" in the final moments blocked the full effect of the demand shock. Conclusion - Uniform-price auctions (clock and sealed-bid uniform-price, and continuous uniform-price) generate changes in purchase prices that are reasonably close to predicted changes. There is some evidence of tacit collusion causing prices to be too low relative to predictions in most cases. The worst price tracking was observed for discriminatory auctions. Application - Uniform-price auctions appear to perform at least as well as other auction designs with respect to discovery of efficient market prices when there are unexpected and unannounced changes in willingness to pay for permits