Conference Highlights Conference Highlights: The 2001 Annual Meeting of the Mid-Western Educational Research Association

Conference Highlight

Seabird colony effects on soil properties and vegetation zonation patterns on King George Island, Maritime Antarctic

Seabirds are among the most important vectors transferring biogenic compounds from the sea onto land in the polar regions and, consequently, influencing the properties of soil and vegetation. We studied the influence of bird colonies (Adélie penguin Pygoscelis adeliae, gentoo penguin P. papua and giant petrels Macronectes giganteus) on soil properties and plant communities on King George Island, Maritime Antarctic. We designated seven transects, each starting from the colony edge and running to a natural boundary feature, which were divided into contiguous sample plots where we identified specific plant taxa (Prasiola crispa, Deschampsia antarctica, Colobanthus quitensis, Usnea sp.), as well as hydrophilous and xerophilous ecological groups of mosses. Based on percentage contributions of each of these taxa, we distinguished six distinct vegetation zones along the transects, in which we measured physical (moisture, conductivity and pH) and chemical (NO3 −, NO2 −, NH4 +, K+ and PO4 3− content) soil parameters. Our study confirmed that, with increasing distance from bird colonies, the concentration of nutrients and soil conductivity decreased, while pH increased. The vegetation zones were clearly related to this gradient of seabird colony influence and occurred in the same sequence for all three bird species examined, although the largest colony of Adélie penguins had the strongest effect on vegetation. Similarly, the physical and chemical soil properties did not differ significantly between the colonie

Mid-Western Educational Research Association 2001 Annual Meeting Call for Proposals

Call for Proposal

Doctor of Philosophy

dissertationThe chemical composition of cosmic rays is critically important to understanding cosmic ray sources as well as a cosmic ray's propagation through the Galaxy and Universe. Theories explaining the features seen in the cosmic ray spectrum depend strongly on the chemical composition of cosmic rays. Composition has implications for anisotropy studies as atomic nuclei with large atomic number are more susceptible to deflection by Galactic and extragalactic magnetic fields. This work presents a composition analysis using data from the Telescope Array (TA) experiment and uses the point of shower maximum, Xmax, as the marker of a cosmic ray's chemical composition. TA is the largest cosmic ray detector in the Northern Hemisphere and makes use of both ground array as well as nitrogen fluorescence methods for detecting cosmic rays. This analysis combines both ground array and fluorescence data in a hybrid analysis to obtain resolutions of 0.5◦ in reconstructed pointing directions and 20 g/cm2 in reconstructed Xmax. Above 1018.5 eV, measured Xmax distributions using hybrid TA data are compatible with proton MC and exclude iron. However, above 1019.3 eV, the statistical power is limited and the data is compatible either proton or iron MCs. The shapes of the Xmax distributions independent of their means are compared, showing again that the data is compatible with protons and incompatible with iron. However, the statistical power for this measurement is limited above 1018.8 eV

Charakteristiky impaktního poškození a ponárazové pevnosti vláknových plastových kompozitů s různou architekturou skelné výztuže

Fiber-reinforced plastics (FRP) are nowadays used commonly for constructions subjected to impacts of different energies and velocities; therefore, the problem of impact resistance is crucial. This paper presents the results of high-velocity impact tests and post-impact evaluation of damage in glass-fiber-reinforced plastics, depending on the architecture of reinforcing material (different woven fabrics, mat). Composites reinforced with continuous-filament mat, woven roving, roving fabric and twisted-yarn fabric were prepared and subjected to intermediate- and high-velocity impact. After the ballistic impact, damage extent and residual strength, as well as water leakage through the composites, were evaluated. The damage was also investigated under a microscope. The damage extent was confirmed to be linearly dependent on impact energy. The addition of rubber was found to decrease damage extent and increase post-impact residual strength, as well as decrease water leakage rate.Plasty vyztužené vlákny (FRP) jsou v současné době hojně používány pro konstrukce vystavené nárazům o různé energii a rychlosti. Z tohoto důvodu je řešení problematiky odolnosti proti nárazu klíčové. Tento článek prezentuje výsledky vysokorychlostních nárazových zkoušek v případě plastů vyztužených skelnými vlákny v závislosti na architektuře matrice (různé druhy tkanin). Kompozity vyztužené spojitými vlákny s různým zpracováním byly posléze podrobeny nárazovým zkouškám s různou rychlostí indentoru. Po nárazu byl zkoumán rozsah poškození, reziduální pevnost a také intenzita úniku vody skrz poškozenou oblast, která byla dodatkově analyzována s využitím mikroskopu. Zkoušky potvrdily lineární závislost mezi rozsahem poškození a nárazovou energií. Přidáním kaučuku do základní matrice došlo ke zvýšení zbytkové pevnosti kompozitu včetně snížení intenzity úniku vody skrz poškozený kompozit

Precision Power and Its Application to the Selection of Regression Sample Sizes

Because of contradictions among the various methods, sample size selection in multiple regression has been problematic. For example, how does one reconcile the difference between a 15: 1 subject-to-variable rule and a 30: 1 rule? The purpose of this paper is to analyze the advantages and disadvantages of the various methods of selecting sample sizes in regression. A discussion of the importance of cross-validity to prediction studies will be followed by descriptions of the three categories of sample size methods: cross-validation approaches, rules-of-thumb, and statistical power methods. A rationale will then be developed for the application of precision power to multiple regression, leading to the presentation, through multiple examples, of the precision power method for sample size selection in prediction studies

Changes in floristic richness and diversity of phytocoenoses on riparian habitats affected by diverse land-use forms

In many ecological studies the theory prevails that the increased human economic activity can lead to simplification of species composition of phytocoenoses and a decline of their species diversity. However, there are also other views on this issue. Therefore, an attempt was undertaken to verify these contradictory opinions. The research was conducted at three sites characterised by a diversified and intensified land use form (the nature reserve, 50 year-old poplar plantation and a grassland). The results from the nature reserve were compared with the data for 1963-1965 when other plant communities dominated in the reserve. The results of field observations collected in the form of relevés were used to assess the number of species, α-species diversity of phytocoenoses and ß-diversity.The largest number of species was found in the meadow, a fewer species were recorded in the reserve and the fewest in the poplar plantation; whereas the average number of species per relevé and the differences between the sites were minor. The species heterogeneity index varied within the range of 3.11–3.36, whereas the extreme differences were recorded in the reserve between the current results and the results from the 1960s. The studied phytocoenoses differed mostly in ß-diversity. The average index for the poplar plantation was lower than mean values of indices recorded in communities of the riparian forest and meadows. The obtained results support the opinion about non linear correlation between the increased disturbances and the decline of species richness and species diversity in phytocoenoses