515 research outputs found

    Stationary concepts for experimental 2x2-games

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    Five stationary concepts for completely mixed 2 x 2-games are experimentally compared: Nash equilibrium, quantal response equilibrium, action-sampling equilibrium, payoff-sampling equilibrium (Martin J. Osborne and Ariel Rubinstein 1998), and impulse balance equilibrium. Experiments on 12 games, 6 constant sum games, and 6 nonconstant sum games were run with 12 independent subject groups for each constant sum game and 6 independent subject groups for each nonconstant sum game. Each independent subject group consisted of four players 1 and four players 2, interacting anonymously over 200 periods with random matching. The comparison of the five theories shows that the order of performance from best to worst is as follows: impulse balance equilibrium, payoff-sampling equilibrium, action-sampling equilibrium, quantal response equilibrium, Nash equilibrium

    Atmospheric concentrations of carbon dioxide and its isotopic composition in southern Poland: comparison of high-altitude mountain site and a near-by urban environment

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    International audienceThe results of regular observations of atmospheric CO2 mixing ratios and its carbon isotope composition (?13C, ?14C), carried out at two continental sites located in central Europe are presented and discussed. The sites (Kasprowy Wierch, 49°14' N, 19°59' E, 1989 m a.s.l.; Krakow, 50°04' N, 19°55' E, 220 m a.s.l.), are located in two contrasting environments: (i) high-altitude mountaneous area, relatively free of anthropogenic influences, and (ii) typical urban environment with numerous local sources of carbon dioxide. Despite of relative proximity of those sites (ca. 100 km), substantial differences in both the recorded CO2 levels and their isotopic composition were detected. The CO2 mixing ratios measured in the urban atmosphere revealed quasi-permanent excess concentration of this gas when compared with near-by background atmosphere. The annual mean CO2 concentration recorded in Krakow in 2004 was almost 10% higher than that recorded at high-altitude mountain site (Kasprowy Wierch). Such effect is occuring probably in all urban centers. Carbon isotopic composition of atmospheric CO2 proved to be efficient tool for identification the surface CO2 fluxes into the atmosphere related to fossil fuel burning and their influence on the recorded levels of this gas in the local atmosphere. The available records of ?14C for Krakow and Kasprowy Wierch suggest gradual reduction of 14C-free CO2 fluxes into the urban atmosphere of Krakow in the past several years

    A Geochemical Record of Late- Holocene Hurricane Events From the Florida Everglades

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    A 5.25- m sediment core SRM- 1 and 45 surface samples from mangrove forests at the Shark River Estuary in the Everglades National Park, Florida, were examined by using X- ray fluorescence and carbon isotopic analyses to study the history of intense hurricane landfall during the Late- Holocene. Significance testing of the surface samples in relation to storm deposits from Hurricane Wilma suggests that elemental concentration of Sr and Cl and the ratio of Cl/Br are the most sensitive indicators for major hurricane events in our study area. The geochemical data sets of core SRM- 1 identified five active periods of intense hurricane activities during the last 3,500 years at ~3,400- 3,000, ~2,200- 1,500, ~1,000- 800, ~600- 300, and ~150 calibrated years before present to present. This is the longest paleohurricane record to date from South Florida. Our results are consistent with the view that intense hurricane activities in South Florida were modulated by Intertropical Convergence Zone (ITCZ) movements, El Niño/Southern Oscillation (ENSO) activities, and North Atlantic Oscillation (NAO) strength. This study contributes to the methodological advancement in paleotempestological studies by demonstrating that geochemical signals, particularly signals of saltwater intrusions, can be preserved in the sediment profiles on millennial time- scale and measured by X- ray fluorescence techniques, thereby enabling more storm records to be produced from otherwise suboptimal sand- limited coastal systems such as the Florida Everglades. More work needs to be done to explore the use of geochemical and stable isotopic analyses in detecting storm signals from sand- limited coastal environments.Plain Language SummaryThis study uses geochemical analyses to detect intense hurricanes that made landfall near the southwest coast of the Florida Everglades from sediment profiles. The geochemical data sets identified five active periods of intense hurricane activities during the last 3,500 years at ~3,400- 3,000, ~2,200- 1,500, ~1,000- 800, ~600- 300, and ~150 years ago. Results from this study agree with previous studies that intense hurricane activities in the western Atlantic Basin were controlled by the position of ITCZ, ENSO activities, and NAO strength.Key PointsThis study demonstrates the use of XRF analysis in detecting major hurricane events in sand- limited coastal systemsFive active hurricane periods were identified at ~3,400- 3,000, ~2,200- 1,500, ~1,000- 800, ~600- 300, and ~150 cal yr BP to presentThis study suggests that intense hurricane activities in the western Atlantic Basin were modulated by ITCZ, ENSO, and NAO activitiesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156482/2/wrcr24787_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156482/1/wrcr24787.pd

    Global-change effects on early-stage decomposition processes in tidal wetlands – implications from a global survey using standardized litter

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    Tidal wetlands, such as tidal marshes and mangroves, are hotspots for carbon sequestration. The preservation of organic matter (OM) is a critical process by which tidal wetlands exert influence over the global carbon cycle and at the same time gain elevation to keep pace with sea-level rise (SLR). The present study assessed the effects of temperature and relative sea level on the decomposition rate and stabilization of OM in tidal wetlands worldwide, utilizing commercially available standardized litter. While effects on decomposition rate per se were minor, we show strong negative effects of temperature and relative sea level on stabilization, as based on the fraction of labile, rapidly hydrolyzable OM that becomes stabilized during deployment. Across study sites, OM stabilization was 29 % lower in low, more frequently flooded vs. high, less frequently flooded zones. Stabilization declined by ∼ 75 % over the studied temperature gradient from 10.9 to 28.5 ∘C. Additionally, data from the Plum Island long-term ecological research site in Massachusetts, USA, show a pronounced reduction in OM stabilization by > 70 % in response to simulated coastal eutrophication, confirming the potentially high sensitivity of OM stabilization to global change. We therefore provide evidence that rising temperature, accelerated SLR, and coastal eutrophication may decrease the future capacity of tidal wetlands to sequester carbon by affecting the initial transformations of recent OM inputs to soil OM

    Moderators, Mediators, and Other Predictors of Risperidone Response in Children with Autistic Disorder and Irritability

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    Objective/Background: The National Institute of Mental Health (NIMH) Research Units on Pediatric Psychopharmacology (RUPP) Autism Network found an effect size of d = 1.2 in favor of risperidone on the main outcome measure in an 8-week double-blind, placebo-controlled trial for irritabilityin autistic disorder. This paper explores moderators and mediators of this effect. Method: Intention-to-treat (ITT) analyses were conducted with suspected moderators and mediators entered into the regression equations. MacArthur Foundation Network subgroup guidelines were followed in the evaluation of the results. Results: Only baseline severity moderated treatment response: Higher severity showed greater improvement for risperidone but not for placebo. Weight gain mediated treatment response negatively: Those who gained more weight improved less with risperidone and more with placebo. Compliance correlated with outcome for risperidone but not placebo. Higher dose correlated with worse outcome for placebo, but not risperidone. Of nonspecific predictors, parent education, family income, and low baseline prolactin positively predicted outcome; anxiety, bipolar symptoms, oppositional-defiant symptoms, stereotypy, and hyperactivity negatively predicted outcome. Risperidone moderated the effect of change in 5'-nucleotidase, a marker of zinc status, for which decrease was associated with improvement only with risperidone, not with placebo. Conclusion: The benefit–risk ratio of risperidone is better with greater symptom severity. Risperidone can be individually titrated to optimal dosage for excellent response in the majority of children. Weight gain is not necessary for risperidone benefit and may even detract from it. Socioeconomic advantage, low prolactin, and absence of co-morbid problems non-specifically predict better outcome. Mineral interactions with risperidone deserve further study
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