5,109 research outputs found

    The Limits of Information: Measuring Differences Between Local and Distance Group Attitudes Toward Distance Learning

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    Because of the imperative of attaining advanced education in the emerging global service economy, and the difficulties involved in traveling to distant classrooms, universities are investing heavily in interactive video and other types of distance learning. While we admit the necessity to investigate these modes of instructional delivery, we also call for a fair but critical investigation of what these technologies take away from the classroom experience. We performed a quasi-experimental study to investigate just that. Students in a local and distance class taught simultaneously by one instructor were asked for their perceptions about the experience. In the main, the perceptions of students in the Distance setting were generally less favorable than their Local setting counterparts. Implications of our findings are discussed

    Escarabajos tigre (Coleoptera: Cicindelidae) de Colombia

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    En el presente artículo se registran 19 géneros y 93 especies para Colombia, doce de las cuales corresponden a nuevos registros (Cuadro 1). Esto corresponde al 61% de losgéneros y 17% de las especies neotropicales de cicindélidos. La mayoría de las especies se distribuyen en tierras bajas (menores a 1000 m). Algunas se encuentran en altitudes mayores a 2000 m. Unas pocas especies ocupan un amplio rango geogråfico, altitudinal y ecológico, hallåndose en gran parte del territorio y en distintos habitats

    Neotropical tiger beetles (Coleoptera: Cicindelidae): checklist and biogeography

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    The Imprinted Retrotransposon-Like Gene PEG11 (RTL1) Is Expressed as a Full-Length Protein in Skeletal Muscle from Callipyge Sheep

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    peer-reviewedMembers of the Ty3-Gypsy retrotransposon family are rare in mammalian genomes despite their abundance in invertebrates and some vertebrates. These elements contain a gag-pol-like structure characteristic of retroviruses but have lost their ability to retrotranspose into the mammalian genome and are thought to be inactive relics of ancient retrotransposition events. One of these retrotransposon-like elements, PEG11 (also called RTL1) is located at the distal end of ovine chromosome 18 within an imprinted gene cluster that is highly conserved in placental mammals. The region contains several conserved imprinted genes including BEGAIN, DLK1, DAT, GTL2 (MEG3), PEG11 (RTL1), PEG11as, MEG8, MIRG and DIO3. An intergenic point mutation between DLK1 and GTL2 causes muscle hypertrophy in callipyge sheep and is associated with large changes in expression of the genes linked in cis between DLK1 and MEG8. It has been suggested that over-expression of DLK1 is the effector of the callipyge phenotype; however, PEG11 gene expression is also strongly correlated with the emergence of the muscling phenotype as a function of genotype, muscle type and developmental stage. To date, there has been no direct evidence that PEG11 encodes a protein, especially as its anti-sense transcript (PEG11as) contains six miRNA that cause cleavage of the PEG11 transcript. Using immunological and mass spectrometry approaches we have directly identified the full-length PEG11 protein from postnatal nuclear preparations of callipyge skeletal muscle and conclude that its over-expression may be involved in inducing muscle hypertrophy. The developmental expression pattern of the PEG11 gene is consistent with the callipyge mutation causing recapitulation of the normal fetal-like gene expression program during postnatal development. Analysis of the PEG11 sequence indicates strong conservation of the regions encoding the antisense microRNA and in at least two cases these correspond with structural or functional domains of the protein suggesting co-evolution of the sense and antisense genes

    Ariel - Volume 10 Number 5

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    Executive Editors Madalyn Schaefgen David Reich Business Manager David Reich News Editors Medical College Edward Zurad CAHS John Guardiani World Mark Zwanger Features Editors Meg Trexler Jim O\u27Brien Editorials Editor Jeffrey Banyas Photography and Sports Editor Stuart Singer Commons Editor Brenda Peterso

    Ionic and electronic properties of the topological insulator Bi2_2Te2_2Se investigated using ÎČ\beta-detected nuclear magnetic relaxation and resonance of 8^8Li

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    We report measurements on the high temperature ionic and low temperature electronic properties of the 3D topological insulator Bi2_2Te2_2Se using ion-implanted 8^8Li ÎČ\beta-detected nuclear magnetic relaxation and resonance. With implantation energies in the range 5-28 keV, the probes penetrate beyond the expected range of the topological surface state, but are still within 250 nm of the surface. At temperatures above ~150 K, spin-lattice relaxation measurements reveal isolated 8^8Li+^{+} diffusion with an activation energy EA=0.185(8)E_{A} = 0.185(8) eV and attempt frequency τ0−1=8(3)×1011\tau_{0}^{-1} = 8(3) \times 10^{11} s−1^{-1} for atomic site-to-site hopping. At lower temperature, we find a linear Korringa-like relaxation mechanism with a field dependent slope and intercept, which is accompanied by an anomalous field dependence to the resonance shift. We suggest that these may be related to a strong contribution from orbital currents or the magnetic freezeout of charge carriers in this heavily compensated semiconductor, but that conventional theories are unable to account for the extent of the field dependence. Conventional NMR of the stable host nuclei may help elucidate their origin.Comment: 17 pages, 12 figures, submitted to Phys. Rev.
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