953 research outputs found

    A Multi-Sensory Approach to Teaching Spelling to Learning Disabled Children

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    Problem Learning disabled children are receiving increasing attention, for despite an intelligence quotient within the normal range, they are not achieving in school as well as their peers. The reasons offered for this phenomenon seem to relate to perceptual problems. Specific learning disabilities occur in reading, arithmetic, spelling, handwriting and other motor coordination areas. This study investigates the effect of a multi-sensory method of teaching spelling to learning disabled children using sandpaper letters to utilize the tactile and kinesthetic sensory modalities. Method Unfamiliar spelling words were taught to 40 learning disabled children, 38 boys and 2 girls. The children were matched by age. One group was taught traditionally and the other group was taught using sandpaper letters. The pretest and post test were scored and an analysis of covariance and a regression analysis of the independent variables was performed on the data. An analysis was also made on the types of errors the children made. Results An analysis of the data showed that the experimental group did not do any better than the control group nor were particular types of errors helped significantly by the experimental method. Conclusions Although the experimental group did not do significantly better than the control group, it would be premature to conclude that adding a tactile, kinesthetic element to teaching spelling is worthless. Many factors could have had an influence on the experiment. Further studies are needed to make a judgment of the applicability of this remedial method

    Molecular construction of HIV-gp120 discontinuous epitope mimics by assembly of cyclic peptides on an orthogonal alkyne functionalized TAC-scaffold

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    Mimics of discontinuous epitopes of for example bacterial or viral proteins may have considerable potential for the development of synthetic vaccines, especially if conserved epitopes can be mimicked. However, due to the structural complexity and size of discontinuous epitopes molecular construction of these mimics remains challeging. We present here a convergent route for the assembly of discontinuous epitope mimics by successive azide alkyne cycloaddition on an orthogonal alkyne functionalized scaffold. Here the synthesis of mimics of the HIV gp120 discontinuous epitope that interacts with the CD4 receptor is described. The resulting protein mimics are capable of inhibition of the gp120–CD4 interaction. The route is convergent, robust and should be applicable to other discontinuous epitopes

    Immobilization by surface conjugation of cyclic peptides for effective mimicry of the HCV-envelope E2 protein as a strategy toward synthetic vaccines

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    Mimicry of the binding interface of antibody-antigen interactions using peptide-based modulators (i.e. epitope mimics) has promising applications for vaccine design. These epitope mimics can be synthesized in a streamlined and straightforward fashion, thereby allowing for high-throughput analysis. The design of epitope mimics is highly influenced by their spatial configuration and structural conformation. It is widely assumed that for proper mimicry sufficient conformational constraints have to be implemented. This paper describes the synthesis of bromide derivatives functional-ized with a flexible TEG linker equipped with a thiol-moiety that could be used to support cyclic or linear peptides. The cyclic and linear epitope mimics were covalently conjugated via the free thiol-moiety on maleimide-activated plate sur-faces. The resulting covalent, uniform, and oriented coated surface of cyclic or linear epitope mimics were subjected to an ELISA to investigate the effect of peptide cyclization with respect to mimicry of an antigen-antibody interaction of the HCV E2 glycoprotein. To our knowledge, the benefit of cyclized peptides over linear peptides has been clearly demon-strated here for the first time. Cyclic epitope mimics, and not the linear epitope mimics, demonstrated specificity towards their monoclonal antibodies HC84.1 and V3.2, respectively. The described strategy for the construction of epitope mimics shows potential for high-throughput screening of key-binding residues by simply changing the amino-acid sequences within synthetic peptides. In this way, leucine-438 has been identified as a key-binding residue for binding monoclonal antibody V3.2

    Modeling group-specific interviewer effects on survey participation using separate coding for random slopes in multilevel models

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    Despite its importance in terms of survey participation, the literature is sparse on how face-to-face interviewers differentially affect specific groups of sample units. In this paper, we demonstrate how an alternative parametrization of the random components in multilevel models, so-called separate coding, delivers valuable insights into differential interviewer effects for specific groups of sample members. At the example of a face-to-face recruitment interview for a probability-based online panel, we detect small interviewer effects regarding survey participation for non-Internet households, whereas we find sizable interviewer effects for Internet households. Based on the proposed variance decomposition, we derive practical guidance for survey practitioners to address such differential interviewer effects

    Modelling Group-Specific Interviewer Effects on Nonresponse Using Separate Coding for Random Slopes in Multilevel Models

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    To enhance response among underrepresented groups and hence, to increase response rates and to decrease potential nonresponse bias survey practitioners often use interviewers in population surveys (Heerwegh, 2009). While interviewers tend to increase overall response rates in surveys (see Heerwegh, 2009), research on the determinants of nonresponse have also identified human interviewers as one reason for variations in response rates (see for examples Couper & Groves, 1992; Durrant, Groves, Staetsky, & Steele, 2010; Durrant & Steele, 2009; Hox & de Leeuw, 2002; Loosveldt & Beullens, 2014; West & Blom, 2016). In addition, research on interviewer effects indicates that interviewers introduce nonresponse bias, if interviewers systematically differ in their success in obtaining response from specific respondent groups (see West, Kreuter, & Jaenichen, 2013; West & Olson, 2010). Therefore, interviewers might be a source of selective nonresponse in surveys. Interviewers might also differentially contribute to selective nonresponse in surveys and hence, potential nonresponse bias, when interviewer effects are correlated with characteristics of the approached sample units (for an example see Loosveldt & Beullens, 2014). Multilevel models including dummies in the random part of the model to distinguish between respondent groups are commonly used to investigate whether interviewer effects on nonresponse differ across specific respondent groups (see Loosveldt & Beullens, 2014). When dummy coding, which is also referred to as contrast coding (Jones, 2013), are included as random components in multilevel models for interviewers effects, the obtained variance estimates indicate to what extent the contrast between respondent groups varies across interviewers. Yet, such parameterization does not directly yield insight on the size of interviewer effects for specific respondent groups. Surveys with large imbalances among respondent groups gain from an investigation of the variation of interviewer effect sizes on nonresponse, as one gains insights on whether the interviewer effect size is the same for specific respondent groups. The importance of the interviewer effect size for specific groups of respondents lies in its prediction of the effectiveness of interviewer-related fieldwork strategies (for examples on liking, matching, or prioritizing respondents with interviewers see Durrant et al., 2010; Peytchev, Riley, Rosen, Murphy, & Lindblad, 2010; Pickery & Loosveldt, 2002, 2004) and thus, a effective mitigation of potential nonresponse bias. Consequently, understanding group-specific interviewer effect sizes can aide the efficiency of respondent recruitment, because we then understand why some interviewer-related fieldwork strategies have great impact on some respondent group’s participation while other strategies have little effect. To obtain information on differences in interviewer effect size, we propose to use an alternative coding strategy, so-called separate coding in multilevel models with random slopes (for examples see Jones, 2013; Verbeke & Molenberghs, 2000, ch. 12.1). In case of separate coding, every variable represents a direct estimate of the interviewer effects for specific respondent groups (rather than the contrast with a reference category). Investigating nonresponse during the recruitment of a probability-based online panel separately for persons with and without prior internet access (data used from the German Internet Panel, see Blom et al., 2017), we detect that the size of the interviewer effect differs between the two respondent groups. While we discover no interviewer effects on nonresponse for persons without internet access (offliners), we find sizable interviewer effects for persons with internet access (onliners). In addition, we identify interviewer characteristics that explain this group-specific nonresponse. Our results demonstrate that the implementation of interviewer-related fieldwork strategies might help to increase response rates among onliners, as for onliners the interviewer effect size was relatively large compared to the interviewer effect size for offliners

    Ontwikkelingen schurftherkenning fruit

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    In het EU-FP6 ISAFruit-project wordt een Crop Adapted Spray Application-systeem voor precisiegewasbescherming in de fruitteelt ontwikkeld. Het systeem garandeert een veilige toediening van gewasbeschermingsmiddelen in boomgaarden afgestemd op de grootte van de boom en de geldende weersomstandigheden. Het systeem wordt beschreve

    Flexible operation of CSIRO's post-combustion CO2 capture pilot plant at the AGL Loy Yang power station

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    Flexible operation has the potential to significantly improve the economic viability of post-combustion CO2 capture (PCC). However, the impact of disturbances from flexible operation of the PCC process is unclear. The purpose of this study was to investigate the effects of flexible operation in a PCC pilot plant by implementing step-changes for improved dynamic data reliability. The flexible operation campaign was conducted at the CSIRO PCC pilot plant at AGL Loy Yang using monoethanolamine (MEA) absorbent. The pilot plant was operated under a broad range of transient conditions (changing flue gas flow, liquid absorbent flow and steam pressure) to capture the dynamics of a PCC process during flexible operation. The study demonstrated that the dynamics of flue gas flow rate was faster than absorbent flow rate. The greatest CO2 removal% was achieved at the lowest flue gas flow rate or at the highest absorbent flow rate; however, the latter provided improved energy efficiency. The steam pressure parameter could adjust the temperature of all columns simultaneously which can be used to compensate for effects from ambient conditions or heat losses. These results verify the technical feasibility of flexible PCC operation and provide a suitable dataset for dynamic model validation

    Blocking entry of hepatitis B and D viruses to hepatocytes as a novel immunotherapy for treating chronic infections

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    Background. Chronic hepatitis B and D virus (HBV/HDV) infections can cause cancer. Current HBV therapy using nucleoside analogues (NAs) is life-long and reduces but does not eliminate the risk of cancer. A hallmark of chronic hepatitis B is a dysfunctional HBV-specific T-cell response. We therefore designed an immunotherapy driven by naive healthy T cells specific for the HDV antigen (HDAg) to bypass the need for HBV-specific T cells in order to prime PreS1-specific T cells and PreS1 antibodies blocking HBV entry. Methods. Ten combinations of PreS1 and/or HDAg sequences were evaluated for induction of PreS1 antibodies and HBV- and HDV-specific T cells in vitro and in vivo. Neutralization of HBV by PreS1-specific murine and rabbit antibodies was evaluated in cell culture, and rabbit anti-PreS1 were tested for neutralization of HBV in mice repopulated with human hepatocytes. Results. The best vaccine candidate induced T cells to PreS1 and HDAg, and PreS1 antibodies blocking HBV entry in vitro. Importantly, adoptive transfer of PreS1 antibodies prevented, or modulated, HBV infection after a subsequent challenge in humanized mice. Conclusions. We here describe a novel immunotherapy for chronic HBV/HDV that targets viral entry to complement NAs and coming therapies inhibiting viral maturation

    Why Do European Venture Capital Companies Syndicate?

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    Financial theory, resource-based theory and access to deal flow are used to explain syndication practices among European venture capital (VC) firms. The desire to share risk and increase portfolio diversification is a more important motive for syndication than the desire to access additional intangible resources or deal flow. Access to resources is, however, more important for non-lead than for lead investors. When resource-based motives are more important, the propensity to syndicate increases. Syndication intensity is higher for young VC firms and for VC firms, specialised in a specific investment stage. Finally, syndication strategies are similar across European countries, but differ from North American strategies
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