4,433 research outputs found

    Reform of Preservice Science Education: An Example from a State-Supported University

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    The ongoing movement to reform the teaching and learning of mathematics and science began as an effort targeting grades K-12. This movement, however, also has signiïŹcant implications for institutions of higher education, especially in the area of teacher preparation. Northeast Louisiana University has utilized an extensive system of support, including vital National Science Foundation funding, to redesign its science curriculum for elementary education majors. Four courses featuring the content areas of biology, chemistry, geosciences, and physics and integrated with respect to content and methodology were collaboratively developed by education and science faculty. and were approved as requirements for all preservice majors. Preliminary evaluation results with respect to students’ content knowledge and attitude are favorable. Ongoing efforts include the development of activities designed to further integrate the courses with respect to content and the execution of focused evaluative studies to reïŹ‚ect the degree of implementation of the reform practices that have been modeled by the university faculty

    Studies on the Bryophytes of Southern Manitoba. II. Collections from the Winnipeg Area

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    Fifty-five taxa of bryophytes are reported for the area of Winnipeg, Manitoba. Frullania inflata, Brachythecium acuminatum, Encalypta ciliata, and Tortella inclinata are new records for the province.The field work in this study was supported in part by Grant No. 140-118 from the University of Winnipeg

    Studies on the Bryophytes of Southern Manitoba. V. Collections from Whiteshell Provincial Park

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    One hundred and twenty-nine taxa of bryophytes were collected in the western part of Whiteshell Provincial Park, Manitoba. The following eight taxa have not previously been recorded for the province: Frullania bolanderi, Lophozia excisa, L. hatcheri, Porella platyphylloidea, Anomodon rostratus, Grimmia donniana, G. unicolor, and Hygroamblystegium fluviatile var. orthocladum."The field work for this study was supported in part by Grant Number 140-118 from the University of Winnipeg.

    FISH OTOLITHS FROM THE LATE MAASTRICHTIAN KEMP CLAY (TEXAS, USA) AND THE EARLY DANIAN CLAYTON FORMATION (ARKANSAS, USA) AND AN ASSESSMENT OF EXTINCTION AND SURVIVAL OF TELEOST LINEAGES ACROSS THE K-PG BOUNDARY BASED ON OTOLITHS

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    Otolith assemblages have rarely been studied across the K-Pg boundary. The late Maastrichtian Kemp Clay of northeastern Texas and the Fox Hills Formation of North Dakota, and the early Danian Clayton Formation of Arkansas therefore offer new insights into how teleost fishes managed across the K-Pg boundary as reconstructed from their otoliths. The Kemp Clay contains 25 species, with 6 new species and 2 in open nomenclature and the Fox Hills Formation contains 4 species including 1 new species. The two otolith associations constitute the Western Interior Seaway (WIS) community. It contains the earliest unambiguous representatives of the Gadiformes (cods and hakes) and the Heterenchelyidae (mud eels). The WIS community differs significantly from other Maastrichtian otolith assemblages previously studied from Mississippi and Maryland, which constitute the Appalachian community, with only 4 shared species (similarity percentage of 7.3%) between both communities. The difference is interpreted to be related to cold-water influence in the WIS community, which may have still been connected to the Arctic Basin, and to the depostional environment (muddy bottom) in the Kemp Clay.             The Kemp Clay is unusually rich in taxa that survived the end-Cretaceous extinction event and are still present in the Danian of the Clayton Formation, or, as the case may be, in the Danian and Selandian of the boreal northern European community known from Denmark. Approximately 54% of all otolith-based teleost species identified from the Maastrichtian WIS community survived the K-Pg boundary event (versus 11-12% in other communities) and 73% of the genera (versus 40-50% in other communities). The early Danian Clayton Formation contains an impoverished inherited association with 14 species, of which 11 are survivors from late Maastrichtian times, 1 species is new, and 2 remain in open nomenclature. This compares to a significantly higher degree of newly evolved species in only slightly younger faunas from the middle to late Danian and Selandian of Europe indicating an initially slow pace of recovery.             The observed differences in survival and the composition of survived and extinct taxa are discussed in the light of the ongoing discussions concerning the consequences and effects that led to the end-Cretaceous extinction event commonly thought to have been caused by a large meteorite impact. In our assessment, an ‘impact winter’ could have had a major influence on the live cycle of tropical to subtropical fishes while perturbations in the pelagic food web or ocean surface acidification might have had a minor and more selective effect. Overall, teleost fishes were significantly affected by the end-Cretaceous mass extinction, but to a much lesser extent than in many other biota. This study provides more evidence of the importance of Late Cretaceous otolith assemblages in the USA for interpreting teleostean evolution.             The newly described taxa are: Elopothrissus carsonsloani n. sp., Pythonichthys arkansasensis n. sp., Congrophichthus transterminus n. gen., n. sp., Rhynchoconger brettwoodwardi n. sp., Palaeogadus weltoni n. sp., Dakotaichthys hogansoni n. gen., n. sp., and Ampheristus americanus n. sp

    Learning from non-linear ecosystem dynamics is vital for achieving land degradation neutrality

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    Land Degradation Neutrality is one of the Sustainable Development Goal targets, requiring on-going degradation to be balanced by restoration and sustainable land management. However, restoration and efforts to prevent degradation have often failed to deliver expected benefits, despite enormous investments. Better acknowledging the close relationships between climate, land management and non-linear ecosystem dynamics can help restoration activities to meet their intended goals, while supporting climate change adaptation and mitigation. This paper is the first to link ecological theory of non-linear ecosystem dynamics to Land Degradation Neutrality offering essential insights into appropriate timings, climate-induced windows of opportunities and risks, and the financial viability of investments. These novel insights are pre-requisites for meaningful operationalisation and monitoring of progress towards Land Degradation Neutrality

    A numerical study of interactions and stellar bars

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    For several decades it has been known that stellar bars in disc galaxies can be triggered by interactions, or by internal processes such as dynamical instabilities. In this work, we explore the differences between these two mechanisms using numerical simulations. We perform two groups of simulations based on isolated galaxies, one group in which a bar develops naturally, and another group in which the bar could not develop in isolation. The rest of the simulations recreate 1:1 coplanar fly-by interactions computed with the impulse approximation. The orbits we use for the interactions represent the fly-bys in groups or clusters of different masses accordingly to the velocity of the encounter. In the analysis we focus on bars' amplitude, size, pattern speed and their rotation parameter, R=RCR/Rbar{\cal R}=R_{CR}/R_{bar}. The latter is used to define fast (R1.4{\cal R}1.4). Compared with equivalent isolated galaxies we find that bars affected or triggered by interactions: (i) remain in the slow regime for longer; (ii) are more boxy in face-on views; (iii) they host kinematically hotter discs. Within this set of simulations we do not see strong differences between retrograde or prograde fly-bys. We also show that slow interactions can trigger bar formation.Comment: 12 pages, 7 figures. Accepted for publication in MNRA
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