750 research outputs found

    Assessing and monitoring student progress in e-learning environments

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    E-learning has emerged as a form of pedagogy and as a delivery system with broad implications for meeting personnel needs nationally in special education. At present, it is important to make investments in research and development to ensure that this new pedagogy becomes fully developed and is appropriately applied. Assessment and monitoring of student progress in e-learning environments is an important element of this new form of pedagogy that requires research attention to maximize the effectiveness of e-learning when applied to teacher education. The authors draw upon their personal online teaching experience in addressing strategies for assessing student performance and using electronic portfolios in e-learning environments, both presented as integral aspects of e-learning instructional process. Perspectives from the literature and lessons learned from the authors’ own experience are shared.peerreviewe

    Transcriptional impairment of β-catenin/E-cadherin complex is not associated with β-catenin mutations in colorectal carcinomas

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    We report the absence of β-catenin mutations in 63 sporadic colorectal carcinomas (SCRCs) with demonstrated decreased β-catenin and E-cadherin mRNA expression and E-cadherin protein expression in a subset of carcinomas examined, suggesting that β-catenin mutations are an extremely rare phenomenon in SCRCs and are not responsible for the transcriptional impairment of the β-catenin/E-cadherin adhesion complex observed in these tumours

    Lung Toxicity of Ambient Particulate Matter from Southeastern U.S. Sites with Different Contributing Sources: Relationships between Composition and Effects

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    BACKGROUND: Exposure to air pollution and, more specifically, particulate matter (PM) is associated with adverse health effects. However, the specific PM characteristics responsible for biological effects have not been defined. OBJECTIVES: In this project we examined the composition, sources, and relative toxicity of samples of PM with aerodynamic diameter ≥2.5 μm (PM(2.5)) collected from sites within the Southeastern Aerosol Research and Characterization (SEARCH) air monitoring network during two seasons. These sites represent four areas with differing sources of PM(2.5), including local urban versus regional sources, urban areas with different contributions of transportation and industrial sources, and a site influenced by Gulf of Mexico weather patterns. METHODS: We collected samples from each site during the winter and summer of 2004 for toxicity testing and for chemical analysis and chemical mass balance–based source apportionment. We also collected PM(2.5) downwind of a series of prescribed forest burns. We assessed the toxicity of the samples by instillation into rat lungs and assessed general toxicity, acute cytotoxicity, and inflammation. Statistical dose–response modeling techniques were used to rank the relative toxicity and compare the seasonal differences at each site. Projection-to-latent-surfaces (PLS) techniques examined the relationships among sources, chemical composition, and toxicologic end points. RESULTS AND CONCLUSIONS: Urban sites with high contributions from vehicles and industry were most toxic

    Overexpression of CD97 in Intestinal Epithelial Cells of Transgenic Mice Attenuates Colitis by Strengthening Adherens Junctions

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    The adhesion G-protein-coupled receptor CD97 is present in normal colonic enterocytes but overexpressed in colorectal carcinoma. To investigate the function of CD97 in colorectal carcinogenesis, transgenic Tg(villin-CD97) mice overexpressing CD97 in enterocytes were generated and subjected to azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis-associated tumorigenesis. Unexpectedly, we found a CD97 cDNA copy number-dependent reduction of DSS-induced colitis in Tg compared to wild-type (WT) mice that was confirmed by applying a simple DSS protocol. Ultrastructural analysis revealed that overexpression of CD97 strengthened lateral cell-cell contacts between enterocytes, which, in contrast, were weakened in CD97 knockout (Ko) mice. Transepithelial resistance was not altered in Tg and Ko mice, indicating that tight junctions were not affected. In Tg murine and normal human colonic enterocytes as well as in colorectal cell lines CD97 was localized preferentially in E-cadherin-based adherens junctions. CD97 overexpression upregulated membrane-bound but not cytoplasmic or nuclear β-catenin and reduced phospho-β-catenin, labeled for degradation. This was associated with inactivation of glycogen synthase kinase-3β (GSK-3β) and activation of Akt. In summary, CD97 increases the structural integrity of enterocytic adherens junctions by increasing and stabilizing junctional β-catenin, thereby regulating intestinal epithelial strength and attenuating experimental colitis

    Group evaluations as self-group distancing:Ingroup typicality moderates evaluative intergroup bias in stigmatized groups

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    Outgroup favoritism among members of stigmatized groups can be seen as a form of self-group distancing. We examined how intergroup evaluations in stigmatized groups vary as a function of ingroup typicality. In Studies 1 and 2, Black participants (N = 125,915;N = 766) more strongly preferred light-skinned or White relative to dark-skinned or Black individuals the lighter their own skin tone. In Study 3, overweight participants (N = 147,540) more strongly preferred normal-weight relative to overweight individuals the lower their own body weight. In Study 4, participants with disabilities (N = 35,058) more strongly preferred non-disabled relative to disabled individuals the less visible they judged their own disability. Relationships between ingroup typicality and intergroup evaluations were at least partially mediated by ingroup identification (Studies 2 and 3). A meta-analysis across studies yielded an average effect size ofr= .12. Furthermore, higher ingroup typicality was related to both ingroup and outgroup evaluations. We discuss ingroup typicality as an individual constraint to self-group distancing among stigmatized group members and its relation to intergroup evaluations

    Comprehensive Analysis of Transcript Start Sites in Ly49 Genes Reveals an Unexpected Relationship with Gene Function and a Lack Of Upstream Promoters

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    Comprehensive analysis of the transcription start sites of the Ly49 genes of C57BL/6 mice using the oligo-capping 5′-RACE technique revealed that the genes encoding the “missing self” inhibitory receptors, Ly49A, C, G, and I, were transcribed from multiple broad regions in exon 1, in the intron1/exon2 region, and upstream of exon -1b. Ly49E was also transcribed in this manner, and uniquely showed a transcriptional shift from exon1 to exon 2 when NK cells were activated in vitro with IL2. Remarkably, a large proportion of Ly49E transcripts was then initiated from downstream of the translational start codon. By contrast, the genes encoding Ly49B and Q in myeloid cells, the activating Ly49D and H receptors in NK cells, and Ly49F in activated T cells, were predominantly transcribed from a conserved site in a pyrimidine-rich region upstream of exon 1. An ∼200 bp fragment from upstream of the Ly49B start site displayed tissue-specific promoter activity in dendritic cell lines, but the corresponding upstream fragments from all other Ly49 genes lacked detectable tissue-specific promoter activity. In particular, none displayed any significant activity in a newly developed adult NK cell line that expressed multiple Ly49 receptors. Similarly, no promoter activity could be found in fragments upstream of intron1/exon2. Collectively, these findings reveal a previously unrecognized relationship between the pattern of transcription and the expression/function of Ly49 receptors, and indicate that transcription of the Ly49 genes expressed in lymphoid cells is achieved in a manner that does not require classical upstream promoters

    Multi-Particle Collision Dynamics -- a Particle-Based Mesoscale Simulation Approach to the Hydrodynamics of Complex Fluids

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    In this review, we describe and analyze a mesoscale simulation method for fluid flow, which was introduced by Malevanets and Kapral in 1999, and is now called multi-particle collision dynamics (MPC) or stochastic rotation dynamics (SRD). The method consists of alternating streaming and collision steps in an ensemble of point particles. The multi-particle collisions are performed by grouping particles in collision cells, and mass, momentum, and energy are locally conserved. This simulation technique captures both full hydrodynamic interactions and thermal fluctuations. The first part of the review begins with a description of several widely used MPC algorithms and then discusses important features of the original SRD algorithm and frequently used variations. Two complementary approaches for deriving the hydrodynamic equations and evaluating the transport coefficients are reviewed. It is then shown how MPC algorithms can be generalized to model non-ideal fluids, and binary mixtures with a consolute point. The importance of angular-momentum conservation for systems like phase-separated liquids with different viscosities is discussed. The second part of the review describes a number of recent applications of MPC algorithms to study colloid and polymer dynamics, the behavior of vesicles and cells in hydrodynamic flows, and the dynamics of viscoelastic fluids

    Non-Equilibrium Evolution Thermodynamics Theory

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    Alternative approach for description of the non-equilibrium phenomena arising in solids at a severe external loading is analyzed. The approach is based on the new form of kinetic equations in terms of the internal and modified free energy. It is illustrated by a model example of a solid with vacancies, for which there is a complete statistical ground. The approach is applied to the description of important practical problem - the formation of fine-grained structure of metals during their treatment by methods of severe plastic deformation. In the framework of two-level two-mode effective internal energy potential model the strengthening curves unified for the whole of deformation range and containing the Hall-Petch and linear strengthening sections are calculated.Comment: 7 pages, 1 figur

    An ontological framework for cooperative games

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    Social intelligence is an emerging property of a system composed of agents that consists of the ability of this system to conceive, design, implement and execute strategies to solve problems and thus achieve a collective state of the system that is concurrently satisfactory for all and each one of the agents that compose it. In order to make decisions when dealing with complex problems related to social systems and take advantage of social intelligence, cooperative games theory constitutes the standard theoretical framework. In the present work, an ontological framework for cooperative games modeling and simulation is presented
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