971 resultados para Grievance procedures.
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The authors explored whether a testing effect occurs not only for retention of facts but also for application of principles and procedures. For that purpose, 38 high school students either repeatedly studied a text on probability calculations or studied the text, took a test on the content, restudied the text, and finally took the test a second time. Results show that testing not only leads to better retention of facts than restudying, but also to better application of acquired knowledge (i.e., principles and procedures) in high school statistics. In other words, testing seems not only to benefit fact retention, but also positively affects deeper learning.
The neurotoxin β-N-methylamino-L-alanine (BMAA) : Sources, bioaccumulation and extraction procedures
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β-methylamino-L-alanine (BMAA) is a neurotoxin linked to neurodegeneration, which is manifested in the devastating human diseases amyotrophic lateral sclerosis, Alzheimer’s and Parkinson’s disease. This neurotoxin is known to be produced by almost all tested species within the cyanobacterial phylum including free living as well as the symbiotic strains. The global distribution of the BMAA producers ranges from a terrestrial ecosystem on the Island of Guam in the Pacific Ocean to an aquatic ecosystem in Northern Europe, the Baltic Sea, where annually massive surface blooms occur. BMAA had been shown to accumulate in the Baltic Sea food web, with highest levels in the bottom dwelling fish-species as well as in mollusks. One of the aims of this thesis was to test the bottom-dwelling bioaccumulation hypothesis by using a larger number of samples allowing a statistical evaluation. Hence, a large set of fish individuals from the lake Finjasjön, were caught and the BMAA concentrations in different tissues were related to the season of catching, fish gender, total weight and species. The results reveal that fish total weight and fish species were positively correlated with BMAA concentration in the fish brain. Therefore, significantly higher concentrations of BMAA in the brain were detected in plankti-benthivorous fish species and heavier (potentially older) individuals. Another goal was to investigate the potential production of BMAA by other phytoplankton organisms. Therefore, diatom cultures were investigated and confirmed to produce BMAA, even in higher concentrations than cyanobacteria. All diatom cultures studied during this thesis work were show to contain BMAA, as well as one dinoflagellate species. This might imply that the environmental spread of BMAA in aquatic ecosystems is even higher than previously thought. Earlier reports on the concentration of BMAA in different organisms have shown highly variable results and the methods used for quantification have been intensively discussed in the scientific community. In the most recent studies, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has become the instrument of choice, due to its high sensitivity and selectivity. Even so, different studies show quite variable concentrations of BMAA. In this thesis, three of the most common BMAA extraction protocols were evaluated in order to find out if the extraction could be one of the sources of variability. It was found that the method involving precipitation of proteins using trichloroacetic acid gave the best performance, complying with all in-house validation criteria. However, extractions of diatom and cyanobacteria cultures with this validated method and quantified using LC-MS/MS still resulted in variable BMAA concentrations, which suggest that also biological reasons contribute to the discrepancies. The current knowledge on the environmental factors that can induce or reduce BMAA production is still limited. In cyanobacteria, production of BMAA was earlier shown to be negative correlated with nitrogen availability – both in laboratory cultures as well as in natural populations. Based on this observation, it was suggested that in unicellular non-diazotrophic cyanobacteria, BMAA might take part in nitrogen metabolism. In order to find out if BMAA has a similar role in diatoms, BMAA was added to two diatom species in culture, in concentrations corresponding to those earlier found in the diatoms. The results suggest that BMAA might induce a nitrogen starvation signal in diatoms, as was earlier observed in cyanobacteria. However, diatoms recover shortly by the extracellular presence of excreted ammonia. Thus, also in diatoms, BMAA might be involved in the nitrogen balance in the cell.
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Agreed-upon procedures report on the City of Palo, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Blue Grass, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Griswold, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Gilmore City, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Villisca, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the Villisca Municipal Power Plant for the period January 1, 2015 through December 31, 2015
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Agreed-upon procedures report on the City of Atkins, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Walnut, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Hamburg, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Tiffin, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Keota, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Dike, Iowa for the period July 1, 2014 through June 30, 2015
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Agreed-upon procedures report on the City of Dike, Iowa for the period July 1, 2013 through June 30, 2014
