Extreme Walrasian Dynamics: The Gale Example in the Lab

We study the classic Gale (1963) economy using laboratory markets. Tatonnement theory predicts prices will diverge from an equitable interior equilibrium towards infinity or zero depending only on initial prices. The inequitable equilibria determined by these dynamics give all gains from exchange to one side of the market. Our results show surprisingly strong support for these predictions. In most sessions one side of the market eventually outgains the other by more than twenty times, leaving the disadvantaged side to trade for mere pennies. We also find preliminary evidence that these dynamics are sticky, resisting exogenous interventions designed to reverse their trajectories

A two-component transport model for solar wind fluctuations: Waves plus quasi-2D turbulence

We present a model for the transport of solar wind fluctuations, based on the assumption that they can be well-represented using two distinct components: a quasi-2D turbulence piece and a wave-like piece. For each component, coupled transport equations for its energy, cross helicity, and characteristic lengthscale(s) are derived, along with an equation for the proton temperature. This energy-containing “two-component” model includes the effects of solar wind expansion and advection, driving by stream shear and pickup ions, and nonlinear cascades. Nonlinear effects are modeled using a recently developed one-point phenomenology for such a two-component model of homogeneous MHD turbulence [1]. Heating due to these nonlinear effects is included in the temperature equation. Numerical solutions are discussed and compared with observation

Aircraft Heads Up Display design and optimization as applied to the AV-8B Harrier

Though the advent of the Heads Up Display (HUD) has dramatically changed the way information is presented to aircrew during flight, the requirement to select and discern the pertinent information applicable to the task at hand has not. Much like the proliferation of gauges and switches in a 60\u27s and 70\u27s era military cockpit interfered with a quick and efficient scan of the instruments, so to do the number of pieces of information being presented in a HUD. With the selection of the AV-8B to be the lead platform in implementation of the Open System Core Avionics Requirement (OSCAR), a rehosting of the Operational Flight Program (OFF), has come the opportunity to optimize the HUD design of the AV-8B. This thesis focuses on an attempt to simplify and standardize the current HUD displays and improve the tailoring of reject sub-modes that are designed to decrease the amount of data being displayed. The potential benefits of HUD modes that could be instructor configured and selectable in-flight to facilitate the development of the proper scan and reduce the time required for pilots to gain proficiency are also addressed

The Development of Ecological Functions in Created Forested Wetlands

Wetland mitigation has become a 2.4 billion dollar per year industry in the U.S. and in Virginia it leads to the replacement of 77 ha of palustrine forested wetlands (PFWs) per year with mitigation wetlands, including created forested wetlands (CFWs). Mitigation hinges on the idea that compensation wetlands lead to “no net loss of wetland function” when compared to impacted wetlands. We assessed the functions of provision of habitat and biogeochemical functions associated with production of biomass, the retention and removal of nutrients and the accumulation of soil C over 8 years in seven CFWs of approximately 11 and 20 years and compared them to natural reference wetlands (NRWs). CFW plant communities were similar to NRWs in all measured parameters in the herbaceous and shrub/sapling strata and in all strata combined. However, non-native dominance showed a significant positive linear relationship with CFW age. In the tree strata, 11 year old (yo) CFWs had lower richness than NRWs and both age classes of CFWs had lower FQI than NRWs. NRWs held 10 to 20 times more carbon in woody biomass than CFWs. Tree species composition was significantly different between CFWs and NRWs, however NRW trees were similar to CFW saplings. 11 yo CFWs held lower percentages of C, N and P and had higher Db than NRWs in both the 0-10 and 10-20 cm depth. 20 yo CFWs developed similar levels of %C, %P, bulk density (Db), and nutrient ratios in the surface and displayed rapid increases in %C and %N over 8 years. However, CFWs offered 45% lower soil total soil C storage and 50% lower %N. Furthermore, all CFWs stored lower nutrient levels than NRWs in the 10-20 cm soil depth. We found that FQI correlated positively with total C accumulation rates in woody biomass and soil C, indicating that biogeochemical function and the provision of habitat can be complimentary in CFWs. Finally, 11 and 20 yo CFWs adhered to the regulatory performance standards established for Virginia in terms of stems per ha and wetland indicator status, but all wetlands (including NRWs) failed to achieve \u3c5% non-native species cover

Saltwater Intrusion and Vegetation Shifts Drive Changes in Carbon Storage in Coastal Wetlands

Coastal wetlands protect coastlines through efficient storage of organic carbon (OC) that decreases wetland vulnerability to sea level rise (SLR). Accelerated SLR is driving saltwater intrusion and altering vegetation communities and biogeochemical conditions in coastal wetlands with uncertain implications. We quantified changes in OC stocks and fluxes driven by 1) saltwater and phosphorous intrusion on freshwater and brackish marshes, 2) vegetation along an experimental saltmarsh to mangrove gradient, 3) saltwater intrusion and vegetation change across a marsh to mangrove ecotone, and 4) vegetation change and mangrove forest development along a marsh to mangrove ecotone. Increasing salinity in freshwater marshes decreased root biomass and soil elevation within one year. In brackish marshes, increased salinity decreased root productivity and biomass and increased root breakdown rate (k), while added salinity did not increase elevation loss. In our experimental marsh-mangrove ecotone, mangrove vegetation promoted higher organic carbon (OC) storage by increasing above and belowground biomass and reducing organic matter k. However, mangroves also increased belowground k, and decreased allochthonous marine subsidies, indicating the potential for OC storage trade-offs. In the Southeast Everglades, we identified strong interior-coastal gradients in soil stoichiometry and mangrove cover. Interior freshwater soil conditions increased k, while total soil OC stocks decreased toward the coast indicating that saltwater intrusion is driving large scale soil OC loss. In the southeast Everglades, mangrove expansion increased root biomass and root productivity, but did not mitigate the overall loss of OC stocks toward the coast. Similarly, in the southwest Everglades, saltwater intrusion drove a decrease in soil OC. However, mangrove encroachment drove a rapid recovery and increased OC stocks. Mangrove encroachment doubled aboveground biomass within the last ten years, increased it 30 times in the last 30 years, and doubled belowground biomass after 20 years. Our research shows that 1) moderate saltwater intrusion without mangrove encroachment will lead to a loss in OC stocks and potentially lead to wetland elevation loss and submergence, 2) in the absence of a change in saltwater intrusion, mangrove expansion can enhance OC storage 3) mangrove expansion can mitigate OC loss during saltwater intrusion, but this pattern depends on mangrove recruitment and ecosystem productivity

Flow Cytometric Enumeration of the Blood Cells of Rainbow Trout (Oncorhynchus mykiss) and New Zealand Freshwater Crayfish (Paranephrops planifrons)

The aim of this study was to develop flow cytometric (FC) methods to enumerate rainbow trout (Oncorhynchus mykiss) whole blood cells and New Zealand freshwater crayfish (Paranephrops planifrons) haemocytes as non-lethal endpoints in the evaluation of physiological status. In the FC method development for rainbow trout, heparin was found to be superior to neutralised EDTA as a blood anticoagulant, because the use of EDTA resulted in significant lysis and shrinkage of erythrocytes. Leishman's-Giemsa and May Grunwald-Giemsa yielded comparable differential staining of leukocytes, and were superior to Wright-Giemsa staining. Morphological ambiguity between thrombocytes and lymphocytes in smears could not be resolved using Romanowsky or cytochemical staining. Use of FC was demonstrated to be a rapid, more accurate alternative to manual total cell counting procedures. Phosphate-buffered saline (PBS) was found to be superior to IsoTon II as a FC sheath fluid; IsoTon II induced lysis of erythrocytes. Characterisation of fish blood cell types and differentiation of leukocytes using FC could be achieved using 50 nM concentrations of the fluorescent lipophilic dye dihexyloxacarbocyanine iodide (DiOC6(3)), but inconsistent fluorescent behaviour exhibited by thrombocytes between specimens prevented clear resolution of these cells from erythrocytes and lymphocytes. Higher concentrations of DiOC6(3) did not enhance resolution and became cytotoxic, particularly to leukocytes. Resolution between thrombocytes and lymphocytes could only be achieved with a fluorescent-labelled thrombocyte monoclonal antibody (mAb). The results suggest that the application of FC and mAb to fish blood cells is the most accurate approach to differential counting of leukocytes. The second FC method objectively characterised and enumerated New Zealand freshwater crayfish haemocytes. Haemocyte populations were isolated by FC sorting based on differential light scatter properties, followed by morphological characterisation by light microscopy and software image analysis. Cells were identified as hyaline, semi-granular and granular haemocytes based on established invertebrate haemocyte classification. A characteristic decrease in nuclear size and increase in granularity between the hyaline and granular cells, and the eccentric location of nuclei in granular cells were also observed. The granulocyte subpopulations were observed to possess varying degrees of granularity. The developed methodology was used to perform total and differential haemocyte counts from three lake crayfish populations and between wild and captive specimens. Differences in total and differential haemocyte counts were not observed between wild populations. However, specimens held in captivity for 14 d exhibited a significant 63% reduction in total haemocyte count, while the relative haemocyte proportions remained the same. These results demonstrate the utility of this method for the investigation of sub-acute stressor effects in selected decapod crustacea