836 research outputs found
Seasonal Variation in the Capacity for Plant Trait Measures to Predict Grassland Carbon and Water Fluxes
Full text linkThere is a need for accurate predictions of ecosystem carbon (C) and water fluxes in field conditions. Previous research has shown that ecosystem properties can be predicted from community abundance-weighted means (CWM) of plant functional traits and measures of trait variability within a community (FDvar). The capacity for traits to predict carbon (C) and water fluxes, and the seasonal dependency of these trait-function relationships has not been fully explored. Here we measured daytime C and water fluxes over four seasons in grasslands of a range of successional ages in southern England. In a model selection procedure, we related these fluxes to environmental covariates and plant biomass measures before adding CWM and FDvar plant trait measures that were scaled up from measures of individual plants grown in greenhouse conditions. Models describing fluxes in periods of low biological activity contained few predictors, which were usually abiotic factors. In more biologically active periods, models contained more predictors, including plant trait measures. Field-based plant biomass measures were generally better predictors of fluxes than CWM and FDvar traits. However, when these measures were used in combination traits accounted for additional variation. Where traits were significant predictors their identity often reflected seasonal vegetation dynamics. These results suggest that database derived trait measures can improve the prediction of ecosystem C and water fluxes. Controlled studies and those involving more detailed flux measurements are required to validate and explore these findings, a worthwhile effort given the potential for using simple vegetation measures to help predict landscape-scale fluxes
Early Feeding In Lake Trout Fry (salvelinus Namaycush) As A Mechanism For Ameliorating Thiamine Deficiency Complex
No full textRecruitment failure of lake trout (Salvelinus namaycush) in the Great Lakes has been attributed in part to the consumption of alewife (Alosa pseudoharengus) by adult lake trout, leading to Thiamine Deficiency Complex (TDC) and early mortality in fry. The current understanding of thiamine deficiency in lake trout fry is based on information from culture and hatchery settings, which do not represent conditions fry experience in the wild and may influence the occurrence of TDC. In the wild, lake trout fry have access to zooplankton immediately following hatching; previous studies found that wild fry begin feeding before complete yolk-sac absorption. However, hatchery-raised fry are not provided with food until after yolk-sac absorption, long after the development of TDC. Zooplankton are a potential source of dietary thiamine for wild fry in the early life stages that has not previously been considered in the occurrence of thiamine deficiency. We postulated that wild-hatched fry could mitigate thiamine deficiency through early feeding on natural prey. Specifically, we hypothesized 1) feeding should increase thiamine concentrations relative to unfed fry and 2) feeding should increase survival relative to unfed fry. Feeding experiments were conducted on lake trout fry reared from eggs collected from Lake Champlain in 2014 and Cayuga Lake in 2015. A fully crossed experimental design was used to determine the effect of early feeding by lake trout fry in thiamine replete and thiamine deplete treatments before and after feeding. Overall, thiamine concentrations and survival did not significantly differ between fed and unfed fry. Thiamine concentrations increased from egg stage to hatching in both years, suggesting a potential source of thiamine, which had not previously been considered, was available to the lake trout eggs during development.Natural ResourcesMaster of Science (MS
Plant Functional Group Composition Modifies the Effects of Precipitation Change on Grassland Ecosystem Function
No full textTemperate grassland ecosystems face a future of precipitation change, which can alter community composition and ecosystem functions through reduced soil moisture and waterlogging. There is evidence that functionally diverse plant communities contain a wider range of water use and resource capture strategies, resulting in greater resistance of ecosystem function to precipitation change. To investigate this interaction between composition and precipitation change we performed a field experiment for three years in successional grassland in southern England. This consisted of two treatments. The first, precipitation change, simulated end of century predictions, and consisted of a summer drought phase alongside winter rainfall addition. The second, functional group identity, divided the plant community into three groups based on their functional traits- broadly described as perennials, caespitose grasses and annuals- and removed these groups in a factorial design. Ecosystem functions related to C, N and water cycling were measured regularly. Effects of functional groupidentity were apparent, with the dominant trend being that process rates were higher under control conditions where a range of perennial species were present. E.g. litter decomposition rates were significantly higher in plots containing several perennial species, the group with the highest average leaf N content. Process rates were also very strongly affected by the precipitation change treatmentwhen perennial plant species were dominant, but not where the community contained a high abundance of annual species and caespitose grasses. This contrasting response could be attributable to differing rooting patterns (shallower structures under annual plants, and deeper roots under perennials) and faster nutrient uptake in annuals compared to perennials. Our results indicate that precipitation change will have a smaller effect on key process rates in grasslandscontaining a range of perennial and annual species, and that maintaining the presence of key functional groups should be a crucial consideration in future grassland management. © 2013 Fry et al
Long-term warming and vegetation change have no impact on microbial resistance to drought, but destabilise microbial communities and microbially-mediated functions
No full textClimate change presents multiple stresses to ecosystems that operate over different timescales, such as long-term warming and short-term drought. It is well established that soil microbial communities are highly responsive to individual stresses, but how they respond combined warming and drought, and how factors such as vegetation change moderate responses, remains uncertain. Here we tested whether long-term passive warming modifies the resistance (amplitude of response) and resilience (degree and duration of recovery) of soil microbial communities to short-term drought. We also tested whether warming effects on microbial resilience to drought are moderated by vegetation composition, and specifically the presence of ericaceous dwarf shrubs, the dominant vegetation type of peatland. This was tested using soil from a nine-year warming and vegetation manipulation experiment established on blanket peatland in northern England. We completed a subsequent laboratory study designed to quantify resistance and resilience of microbial communities and microbial-mediated functions to drought. Neither long-term warming nor shrub removal impacted the resistance of microbial communities to drought. However, resilience of bacterial diversity to drought was decreased by warming (fold change 0.38) and shrub removal (fold change 0.27). Notably the interaction between warming and shrub removal resulted in higher resilience of bacterial diversity than individual treatments (fold change 0.58; warming x shrub removal: p = 0.008). Further, warming and shrub removal individually increased the diversity of fungal communities, and reduced resilience of fungal diversity to drought (fold change of warmed against unwarmed 0.11, shrub removal against control 0.39, combination against control 0.59; warming x shrub removal p = 0.006). Warming also strongly decreased resilience, but not resistance, of nitrogen-based functions to drought, although shrub removal dampened this effect. Our findings demonstrate potential for long-term warming and vegetation change to modify microbial responses to extreme drought events, with implications for peatland carbon and nitrogen cycling under future climate scenarios
Looking Inside the Black Box of "Attendance at Services": New Measures for Exploring an Old Dimension in Religion and Health Research
No full textResearch in religion and health has spurred new interest in measuring religiousness. Measurement efforts have focused on subjective facets of religiousness such as spirituality and beliefs, and less attention has been paid to congregate aspects, beyond the single item measuring attendance at services. We evaluate some new measures for religious experiences occurring during congregational worship services. Respondents (N=576) were religiously-diverse community dwelling adults interviewed prior to cardiac surgery. Exploratory factor analysis of the new items with a pool of standard items yielded a readily interpretable solution, involving seven correlated but distinct factors and one index variable, with high levels of internal consistency. We describe religious affiliation and demographic differences in these measures. Attendance at religious services provides multifaceted physical, emotional, social, and spiritual experiences that may promote physical health through multiple pathways.This research was supported by grants from the National Institute on Aging (AG15160 and AG16750, Richard Contrada, PI).Published 2009 in International Journal for the Psychology of Religion at http://www.informaworld.com/smpp/content~db=all~content=a907482564~frm=titlelin
Gilchrist, Ellen Louise, 1935-2024 (SC 1336)
Full text linkFinding aid only for Manuscript Small Collection 1336. Letter written to Kentucky author Ellen L. Gilchrist from Paula Quinn, WKU journalism professor, after a scheduled interview did not materialize. Gilchrist\u27s response is handwritten on the letter. Includes newspaper clipping about Gilchrist\u27s presentation at WKU, and Quinn\u27s explanatory letters, 2001
Design of an Immersion Vaccine Against Aeromonad Septicemia in Perch (Perca fluviatilis L.).
No full textThe production of an immersion vaccine and the vaccination procedure to immunize fry of perch (Perca fluviatilis L.) against pathogenic Aeromonas sobria that harbor a type III secretion system is described. The vaccine, based on chemically inactivated A. sobria, enables rapid vaccination of a large number of fish by immersion of fry in an aqueous vaccine suspension during 5 min, giving them high protection during fattening under open water conditions in a freshwater lake for at least 4 months
Ecosystem functions are resistant to extreme changes to rainfall regimes in a mesotrophic grassland
Full text linkMajor changes to rainfall regimes are predicted for the future but the effect of such changes on terrestrial ecosystem function is largely unknown. We created a rainfall manipulation experiment to investigate the effects of extreme changes in rainfall regimes on ecosystem functioning in a grassland system. We applied two rainfall regimes; a prolonged drought treatment (30 % reduction over spring and summer) and drought/downpour treatment (long periods of no rainfall interspersed with downpours), with an ambient control. Both rainfall manipulations included increased winter rainfall. We measured plant community composition, CO2 fluxes and soil nutrient availability. Plant species richness and cover were lower in the drought/downpour treatment, and showed little recovery after the treatment ceased. Ecosystem processes were less affected, possibly due to winter rainfall additions buffering reduced summer rainfall, which saw relatively small soil moisture changes. However, soil extractable P and ecosystem respiration were significantly higher in rainfall change treatments than in the control. This grassland appears fairly resistant, in the short term, to even the more extreme rainfall changes that are predicted for the region, although prolonged study is needed to measure longer-term impacts. Differences in ecosystem responses between the two treatments emphasise the variety of ecosystem responses to changes in both the size and frequency of rainfall events. Given that model predictions are inconsistent there is therefore a need to assess ecosystem function under a range of potential climate change scenarios
Outsourcing and Skill Imports: Foreign High-Skilled Workers on H-1B and L-1 Visas in the United States
Full text linkThis working paper looks in detail at the H-1B and L-1 visa programs for temporary employment in the United States. Based on official data from the US Citizenship and Immigration Services and the US Department of State, H-1B and L-1 visa issuance rapidly increased in the late 1990s, followed by a marked slowdown after 2001. This points to the highly cyclical nature of both visa programs. Indian nationals and immigrants working in computer-related occupations dominate the H1-B and L-1 population in the United States, but these two groups are also found to be the most cyclical segment, with very large declines in inflows after 2001. The total population of H-1B visaholders in 2003 is estimated to range between 387,000 and 746,000, of which 160,000 to 306,000 were Indian nationals. As all data on H-1B/L-1 visaholders are gross numbers and gross jobs data for comparable categories are absent, the extent of the impact of these visa programs on the US labor market cannot be gauged precisely. A broad range of US industries and educational institutions are found to be employing H-1B recipients, with the IT industry being the dominant sector. Evidence of aggressive wage-cost cutting, including paying H-1B recipients only the legally mandated 95 percent of the prevailing US wage, is found among some H-1B employers, although no systematic abuse of the system is present.Outsourcing, offshoring, high-skilled labor, immigration, H1B/L-1 visas
Using Geographical Information System (GIS)-based watershed characteristics to predict stream visual assessment scores
No full textThe Stream Visual Assessment Protocol (SVAP) was designed as a cost-effective measurement of stream condition that can be used by non-scientific individuals with minimal training. It is intended as a preliminary assessment to determine problem areas where further study is needed. Although the SVAP is a simple assessment, resources are still required to train staff and volunteers on the protocol and to spend days in the field collecting data. However, if existing data can be used to obtain comparable stream health information without requiring field work, the cost associated with these resources can be reduced. This research investigated whether models can be created using previously collected SVAP data and GIS-based watershed characteristics to evaluate stream conditions to eliminate field work.
Using GIS, characteristics such as basin area and stream size were calculated for the areas draining into SVAP assessment locations. Digital data was used to determine characteristics based on land use/cover and soils. Statistical models were created using SVAP data from the Ramapo watershed in northeastern New Jersey. Models significant at α = 0.10 or lower were applied to the Wanaque watershed to determine whether the SVAP scores can be predicted in another location. While the regression models generally explained a high amount of variance in the Ramapo SVAP scores, the SVAP scores for Wanaque could not be accurately predicted from the test models.M.S.Includes bibliographical references (p. 34-36)
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