Comparing collaborative problem solving in virtual reality and desktop computer display environments

https://www.ester.ee/record=b5160211*es

Refining Pedogenic Carbonate Proxies for Improved Reconstructions of Past Terrestrial Environmental Conditions.

Continental paleoclimate records provide a means to assess regional climate variability through time and assess how the evolution of the terrestrial biosphere has driven and responded to environmental change. Fossil soils (paleosols) are a particularly useful paleoclimate archive, because they are widely distributed throughout the geologic record. Carbonate clumped isotope paleothermometry is an exciting new proxy for paleosols, as it has the potential to assess temperature seasonality. Yet the processes underlying soil carbonate formation and clumped isotope temperature resetting must be further understood before this proxy can be effectively applied. My dissertation centers on improving understanding of the processes controlling soil carbonate formation and critically evaluating the potential resetting of clumped isotope carbonate data from terrestrial deposits. In Chapter 2, I use modern samples to explore seasonal biases associated with the clumped isotope composition of soil carbonate. The results demonstrate that soil carbonate can form at or below mean annual temperatures. The cold nature of these results is explained by the annual timing of soil water depletion, which is driven by patterns of seasonal precipitation and evapotranspiration. In Chapter 3, modern soil environmental data are compiled to examine how soil temperatures relate to surface air temperatures and to quantify systematic biases that will affect paleosol proxies. Seasonal fluctuations in soil moisture are used to predict the seasonal timing of pedogenic carbonate formation. Soil temperature data indicate that pedogenic carbonate is more likely to record warm season bias relative to mean annual air temperature. In Chapter 4, I use clumped isotope and organic biomarker analyses on the 1.1 Ga Nonesuch Formation to explore how easily the clumped isotope thermometer can be reset on geologic samples and to evaluate the performance of new solid-state reordering models. Using a solid-state reordering model, I illustrate that the synsedimentary and early-diagenetic calcite were partially reset to elevated temperatures. Taken together, these results illustrate factors that must be considered when producing environmental reconstructions from pedogenic carbonate and other terrestrial archives. These findings provide guidance on how to extract accurate paleoclimate information from paleosol carbonate and highlight the need for a process-based understanding of pedogenic carbonate formation.PHDGeologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/135835/1/tgallag_1.pd

Identification of atropine-and P2X1 receptor antagonist-reistant, neurogenic contractions of the urinary bladder

Acetylcholine and ATP are excitatory cotransmitters in parasympathetic nerves. We used P2X1 receptor antagonists to further characterize the purinergic component of neurotransmission in isolated detrusor muscle of guinea pig urinary bladder. In the presence of atropine (1 μm) and prazosin (100 nm), pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS) (0.1–100 μm) and suramin (1–300 μm) inhibited contractions evoked by 4 Hz nerve stimulation in a concentration-dependent manner (IC50 of 6.9 and 13.4 μm, respectively). Maximum inhibition was 50–60%, which was unaffected by coadministration of the ectonucleotidase inhibitor ARL67156 (6-N,N-diethyl-d-β,γ-dibromomethyleneATP) (100 μm). The remaining responses were abolished by tetrodotoxin (1 μm). PPADS and suramin also reduced contractions to exogenous ATP (300 μm) by 40–50%, but abolished those to the P2X1 agonist α,β-methyleneATP (α,β-meATP) (1 μm). The P2X1 antagonists reactive blue 2, NF279 (8,8′-[carbonylbis(imino-4,1-phenylenecarbonylimino-4,1-phenylenecarbonylimino)] bis-1,3,5-naphthalenetrisulfonic acid), MRS2159 (pyridoxal-α5-phosphate-6-phenylazo-4′-carboxylic acid) (100 μm), and NF449 [4,4′,4,4-(carbonylbis(imino-5,1,3-benzenetriylbis(carbonylimino)))tetrakis-benzene-1,3-disulfonic acid] (3 μm) abolished contractions to α,β-meATP (1 μm; n = 4–5), but only reduced contractions evoked by 4 Hz nerve stimulation by ∼40–60% (n = 4–6) and ATP by 30–60% (n = 4–7). However, prolonged exposure to α,β-meATP (50 μm) abolished contractions evoked by all three stimuli (n = 5–12). PPADS (100 μm) and suramin (300 μm) reduced the peak neurogenic contraction of the mouse urinary bladder to 30–40% of control. At the same concentrations, the P2X1 antagonists abolished the nonadrenergic, purinergic component of neurogenic contractions in the guinea pig vas deferens (n = 4–5). Thus, P2X1 receptor antagonists inhibit, but do not abolish, the noncholinergic component of neurogenic contractions of guinea pig and mouse urinary bladder, indicating a second mode of action of neuronally released ATP. This has important implications for treatment of dysfunctional urinary bladder, for which this atropine- and P2X1 antagonist-resistant site represents a novel therapeutic target

03-06 "Free Trade, Corn, and the Environment: Environmental Impacts of US – Mexico Corn Trade Under NAFTA"

The North American Free Trade Agreement (NAFTA) had a profound impact on corn trade between the United States and Mexico. Negotiated tariff reductions and the Mexican government’s decision not to charge some tariffs to which it was entitled resulted in a doubling of US corn exports to Mexico. This paper examines the environmental implications of this change on both sides of the border.

Prize Volatility and Presence or Absence of Anticipatory Sitmulus Signally Reward as Predictors of Electronic Game Machine Behaviour of Gamblers

This study investigated the effect of changes in prize volatility and presence or absence of an anticipatory stimulus signally reward on verbal ratings, playing behaviour, and biometric responses in casual and frequent electronic gaming machine (EGM) players. Biometric measurements of 129 participants were recorded while they played an actual EGM with money provided by the experimenters. However, only the data from 95 participants were analysed. Participants were first connected to biometric sensors to record their heart rate and galvanic skin responses, and completed a demographic questionnaire. All participants then played an EGM game for 10 minutes. After playing the EGM game, they either played the same EGM game or a different EGM game for another 10 minutes in accord with their experimental condition. The second game was characterized by one of four conditions, (a) low volatility, absence of anticipatory stimulus, (b) low volatility, presence of anticipatory stimulus, (c) high volatility, absence of anticipatory stimulus, and (d) high volatility, presence of anticipatory stimulus. After 20 minutes of EGM play, participants completed the Canadian Problem Gambling Index (CPGI; Ferris & Wynne, 2001). Statistical results revealed that the volatility condition had a significant effect on how quickly a player would bet. That is, players bet later in conditions with higher volatility. Furthermore, frequent players bet later than casual players. There was a significant interaction between volatility and player type, but the anticipatory stimulus condition was not found to have a significant effect on playing behaviour

Origin of Jurassic Carbonate Nodules in Southeastern Wyoming

The Morrison Formation of the Western United States is famous for the dinosaurs and other fossils that have been excavated from its beds. It was deposited during the Late Jurassic in a semi-arid, savannah-like environment. The Morrison Formation is remarkably extensive, with outcrops across eight states; however attempts to correlate between Wyoming and the Colorado Plateau have proven difficult. The goal of this research is to determine the origin of carbonate rocks from the Morrison Formation beds exposed on the Spring Creek Preserve in southeastern Wyoming, and to assess their potential for lithostratigphic correlations. A wide range of research techniques were employed, ranging from macroscopic observations in the field to geochemical and isotopic analyses. Field relationships and macro- and microtextures of nodular and calcareous units are consistent with carbonate mineral deposition of freshwater lacustrine muds and the development of palustrine limestones, nodules and calcrete as the micritic muds were exposed and desiccated. Strontium isotope data suggest that the nodules developed from alteration of nearby lacustrine carbonates with little exogenous input. The thickness and level of development of the nodular carbonate units below the mid-Morrison unconformity at 42 m and observed in nearby localities suggests an extended period of subaerial exposure and desiccation in the study area during middle Morrison time. If the presence of these palustrine carbonates found throughout Wyoming is the result of a synchronous regional lake-level lowstand, it is plausible that this nodular horizon correlates to the Mid-Morrison paleosol unconformity identified Utah and Colorado. The strontium isotope composition of a belemnite from the underlying Sundance Formation corresponds to a Late Jurassic Oxfordian age (161-157 million years ago) for this unit and places a maximum age for the Morrison Formation in the Spring Creek Reserve study area