892 research outputs found

    Self supporting Nanodiamond gels: Elucidating colloidal interactions through rheology

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    While ND represents a promising class of nanofiller due to its high surface area, superior mechanical strength, optical transparency, tailorable surface functionality and biocompatibility, much remains unknown about the behavior of ND dispersions and their responses to various processing conditions. We hypothesize that controlling interactions in ND dispersions will lead to highly functional systems with tunable modulus and shear response. Steady and dynamic rheology techniques are thus employed to systematically investigate nanodiamonds dispersed in model polar and non-polar media and examine the microstructure and concomitant rheological behavior. We find that low concentrations of ND form gels almost instantaneously in a non-polar media, the strength of which follow a power-law behavior. In contrast, ND’s in polar media show a time-dependent behavior with the modulus increasing with time. We attribute the difference in behavior to variations in inter-particle interactions as well as the interaction of the ND with the media. Large steady and oscillatory strains are applied to ND colloidal gels to investigate the role of shear in gel microstructure breakdown and recovery. For colloidal gels in non-polar medium, the incomplete recovery of elastic modulus at high strain amplitudes indicates dominance of particle-particle interactions; however, in polar media the complete recovery of elastic modulus even at high strain amplitudes indicates dominance of particle-solvent interactions. These results taken together provide a platform to develop self-supporting gels with tunable properties in terms of ND concentration, and solvent ty

    The Effects of Continuous Improvement Practices Using State Value-Added Data for Reading Educator Program Enhancement

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    Louisiana’s value-added evaluation of teacher preparation programs has provided a salient impetus for program improvement; however, due to the nature of the assessment, teacher preparation programs need to use additional sources of data to identify actionable responses to the value-added results. This paper describes one teacher preparation program’s approach to continuous program improvement in reading education and describes some of the limitations and benefits of value-added assessment results for that purpose

    Gendered nationalism : the gender gap in support for the Scottish National Party

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    Recent major surveys of the Scottish electorate and of Scottish National Party (SNP) members have revealed a distinct gender gap in support for the party. Men are markedly more likely than women to vote for the SNP and they comprise more than two-thirds of its membership. In this article, we use data from those surveys to test various possible explanations for the disproportionately male support for the SNP. While popular accounts have focused on the gendered appeal of recent leaders and on the party’s fluctuating efforts at achieving gender equality in its parliamentary representation, we find much stronger support for a different explanation. Women are less inclined to support and to join the SNP because they are markedly less supportive of its central objective of independence for Scotland. Since men and women barely differ in their reported national identities, the origins of this gender gap in support for independence presents a puzzle for further research

    Framing Scientific Analyses for Risk Management of Environmental Hazards by Communities: Case Studies with Seafood Safety Issues

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    Risk management provides a context for addressing environmental health hazards. Critical to this approach is the identification of key opportunities for participation. We applied a framework based on the National Research Council’s (NRC) analytic–deliberative risk management dialogue model that illustrates two main iterative processes: informing and framing. The informing process involves conveying information from analyses of risk issues, often scientific, to all parties so they can participate in deliberation. In the framing process, ideas and concerns from stakeholder deliberations help determine what and how scientific analyses will be carried out. There are few activities through which affected parties can convey their ideas from deliberative processes for framing scientific analyses. The absence of participation results in one-way communication. The analytic–deliberative dialogue, as envisioned by the NRC and promoted by the National Institute of Environmental Health Sciences (NIEHS), underscores the importance of two-way communication. In this article we present case studies of three groups—an Asian and Pacific Islander community coalition and two Native American Tribes—active in framing scientific analyses of health risks related to contaminated seafood. Contacts with these organizations were established or enhanced through a regional NIEHS town meeting. The reasons for concern, participation, approaches, and funding sources were different for each group. Benefits from their activities include increased community involvement and ownership, better focusing of analytical processes, and improved accuracy and appropriateness of risk management. These examples present a spectrum of options for increasing community involvement in framing analyses and highlight the need for increased support of such activities

    Core binding factors are necessary for natural killer cell development, and cooperate with Notch signaling during T cell specification

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    CBF{beta} is the non-DNA binding subunit of the core binding factors (CBFs). Mice with reduced CBF{beta} levels display profound, early defects in T but not B cell development. Here we show that CBF{beta} is also required at very early stages of natural killer (NK) cell development. We also demonstrate that T cell development aborts during specification, as the expression of Gata3 and Tcf7, which encode key regulators of T lineage specification, is substantially reduced, as are functional thymic progenitors. Constitutively active Notch or IL-7 signaling cannot restore T cell expansion or differentiation of CBF{beta} insufficient cells, nor can overexpression of Runx1 or CBF{beta} overcome a lack of Notch signaling. Therefore the ability of the prethymic cell to respond appropriately to Notch is dependent on CBF{beta}, and both signals converge to activate the T cell developmental program

    Bridging Alone: Religious Conservatism, Marital Homogamy, and Voluntary Association Membership

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    This study characterizes social insularity of religiously conservative American married couples by examining patterns of voluntary associationmembership. Constructing a dataset of 3938 marital dyads from the second wave of the National Survey of Families and Households, the author investigates whether conservative religious homogamy encourages membership in religious voluntary groups and discourages membership in secular voluntary groups. Results indicate that couples’ shared affiliation with conservative denominations, paired with beliefs in biblical authority and inerrancy, increases the likelihood of religious group membership for husbands and wives and reduces the likelihood of secular group membership for wives, but not for husbands. The social insularity of conservative religious groups appears to be reinforced by homogamy—particularly by wives who share faith with husbands
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