858 research outputs found

    Water for Power Generation: What\u27s the Value

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    Teachers\u27 Perceptions of Barriers, Strategies, and Professional Development in Addressing Reading Deficiencies Displayed by Struggling Pre-Kindergarten-Second Grade Readers

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    The purpose of the study was focused on examining perceptions of a sample of primary level rural Minnesota teachers of the common reading deficiencies displayed by struggling preschool through second grade readers, barriers experienced in delivering reading instruction to struggling readers, and strategies determined to be most effective in addressing reading deficiencies displayed by struggling readers. Furthermore, the study examined the types of staff development Minnesota teachers and their principals identified as most valuable in addressing reading deficiencies among preschool through second grade students. The study employed a mixed methodology, which included the use of a closed-ended response survey and interviews. According to Morse (2005), “mixed method research consists of designs that are either primarily qualitative or quantitative and that incorporate strategies of the other method (either qualitative or quantitative) into the same research project” (p. 583). The main conclusions from this study supports existing research. Research supports the necessity to identify struggling readers early in their literacy development. Flynn, Zheng, and Swanson (2012) stated, “it is widely known that early intervention is the key component to remediating reading difficulties, as well as, decreasing the risk of future reading acquisition problems” (p. 21). The study of Teachers’ Perceptions of Barriers, Strategies, and Professional Development in Addressing Reading Deficiencies Displayed by Struggling Pre-Kindergarten-Second Grade Readers supports the need for early identification of literacy deficiencies displayed by struggling readers. It also supports the need for identifying perceived barriers impacting the delivery of quality instruction, teaching strategies to address reading deficiencies of struggling readers, and available professional development or related reading strategies to improve literacy instruction

    Identification of a novel phosphorylation site in hepatitis C virus NS5A

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    Hepatitis C virus (HCV) NS5A protein is phosphorylated on multiple residues; however, despite extensive study, the precise identity of these sites has not been determined unambiguously. In this study, we have used a combination of immunoprecipitation and mass spectrometry to identify these phosphorylation sites. This analysis revealed the presence of a major phosphorylated residue within NS5A from the genotype 1b Con1 isolate – serine 249 (serine 2221 in polyprotein numbering). However, mutation of this residue (or the corresponding threonine in the JFH-1 isolate) to either a phosphomimetic (aspartate) or a phosphoablative (alanine) residue resulted in no phenotype. We conclude that phosphorylation of this residue, in the context of a highly culture-adapted HCV genome, does not play a role in either viral RNA replication or virus assembly. It is possible that it might be important in an aspect of virus biology that is not recapitulated faithfully in the Huh-7 cell-culture system

    Titration Calorimetry Standards and the Precision of Isothermal Titration Calorimetry Data

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    Current Isothermal Titration Calorimetry (ITC) data in the literature have relatively high errors in the measured enthalpies of protein-ligand binding reactions. There is a need for universal validation standards for titration calorimeters. Several inorganic salt co-precipitation and buffer protonation reactions have been suggested as possible enthalpy standards. The performances of several commercial calorimeters, including the VP-ITC, ITC200, and Nano ITC-III, were validated using these suggested standard reactions

    An arctic low-energy house as experimental setup for studies of heat dynamics of buildings

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    AbstractThis paper addresses the difficulties in pinpointing reasons for unexpectedly high energy consumption in construction, and in low-energy houses especially. Statistical methods are applied to improve the insight into the energy performance and heat dynamics of a building based on consumption records and weather data. Dynamical methods separate influences from outdoor temperature, solar radiation, and wind on the energy consumption in the building. The studied building is a low-energy house in Sisimiut, Greenland. Weather conditions like large temperature differences between indoors and outdoors throughout long winters, strong winds, and very different circumstances regarding solar radiation compared to areas where low-energy houses are usually built, make the location very interesting for modeling and testing purposes. In 2011 new measurement equipment was installed in the house, which will be used to develop more detailed models of the heat dynamics and energy performance in relation to different meteorological variables, heating systems, and user behavior. This type of models is known as a graybox model and is been introduced in this paper

    Complete replication of hepatitis C virus in cell culture.

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    Many aspects of the hepatitis C virus (HCV) life cycle have not been reproduced in cell culture, which has slowed research progress on this important human pathogen. Here, we describe a full-length HCV genome that replicates and produces virus particles that are infectious in cell culture (HCVcc). Replication of HCVcc was robust, producing nearly 10(5) infectious units per milliliter within 48 hours. Virus particles were filterable and neutralized with a monoclonal antibody against the viral glycoprotein E2. Viral entry was dependent on cellular expression of a putative HCV receptor, CD81. HCVcc replication was inhibited by interferon-alpha and by several HCV-specific antiviral compounds, suggesting that this in vitro system will aid in the search for improved antivirals

    Neutralizing Antibody-Resistant Hepatitis C Virus Cell-to-Cell Transmission

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    Hepatitis C virus (HCV) can initiate infection by cell-free particle and cell-cell contact-dependent transmission. In this study we use a novel infectious coculture system to examine these alternative modes of infection. Cell-to-cell transmission is relatively resistant to anti-HCV glycoprotein monoclonal anti- bodies and polyclonal immunoglobulin isolated from infected individuals, providing an effective strategy for escaping host humoral immune responses. Chimeric viruses expressing the structural proteins rep- resenting the seven major HCV genotypes demonstrate neutralizing antibody-resistant cell-to-cell trans- mission. HCV entry is a multistep process involving numerous receptors. In this study we demonstrate that, in contrast to earlier reports, CD81 and the tight-junction components claudin-1 and occludin are all essential for both cell-free and cell-to-cell viral transmission. However, scavenger receptor BI (SR-BI) has a more prominent role in cell-to-cell transmission of the virus, with SR-BI-specific antibodies and small-molecule inhibitors showing preferential inhibition of this infection route. These observations highlight the importance of targeting host cell receptors, in particular SR-BI, to control viral infection and spread in the liver

    RegB Kinase Activity Is Controlled in Part by Monitoring the Ratio of Oxidized to Reduced Ubiquinones in the Ubiquinone Pool

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    RegB is a membrane-spanning sensor kinase responsible for redox regulation of a wide variety of metabolic processes in numerous proteobacterial species. Here we show that full-length RegB purified from Escherichia coli membranes contains bound ubiquinone. Four conserved residues in the membrane-spanning domain of RegB are shown to have important roles in ubiquinone binding in vitro and redox sensing in vivo. Isothermal titration calorimetry measurements, coupled with kinase assays under oxidizing and reducing conditions, indicate that RegB weakly binds both oxidized ubiquinone and reduced ubiquinone (ubiquinol) with nearly equal affinity and that oxidized ubiquinone inhibits kinase activity without promoting a redox reaction. We propose a model in which ubiquinone/ubiquinol bound to RegB readily equilibrates with ubiquinones/ubiquinols in the membrane, allowing the kinase activity to be tuned by the redox state of the ubiquinone pool. This noncatalytic role of ubiquinone in controlling RegB activity is distinct from that of other known ubiquinone-binding proteins, which use ubiquinone as an electron donor or acceptor

    The crystal structure of NS5A domain 1 from genotype 1a reveals new clues to the mechanism of action for dimeric HCV inhibitors

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    New direct acting antivirals (DAAs) such as daclatasvir (DCV; BMS-790052), which target NS5A function with picomolar potency, are showing promise in clinical trials. The exact nature of how these compounds have an inhibitory effect on HCV is unknown; however, major resistance mutations appear in the N-terminal region of NS5A that include the amphipathic helix and domain 1. The dimeric symmetry of these compounds suggests that they act on a dimer of NS5A, which is also consistent with the presence of dimers in crystals of NS5A domain 1 from genotype 1b. Genotype 1a HCV is less potently affected by these compounds and resistance mutations have a greater effect than in the 1b genotypes. We have obtained crystals of domain 1 of the important 1a NS5A homologue and intriguingly, our X-ray crystal structure reveals two new dimeric forms of this domain. Furthermore, the high solvent content (75%) makes it ideal for ligand-soaking. Daclatasvir (DCV) shows twofold symmetry suggesting NS5A dimers may be of physiological importance and serve as potential binding sites for DCV. These dimers also allow for new conformations of a NS5A expansive network which could explain its operation on the membranous web. Additionally, sulfates bound in the crystal structure may provide evidence for the previously proposed RNA binding groove, or explain regulation of NS5A domain 2 and 3 function and phosphorylation, by domain 1

    Infrared emission spectrum and potentials of 0u+0_u^+ and 0g+0_g^+ states of Xe2_2 excimers produced by electron impact

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    We present an investigation of the Xe2_{2} excimer emission spectrum observed in the near infrared range about 7800 cm−1^{-1} in pure Xe gas and in an Ar (90%) --Xe (10%) mixture and obtained by exciting the gas with energetic electrons. The Franck--Condon simulation of the spectrum shape suggests that emission stems from a bound--free molecular transition never studied before. The states involved are assigned as the bound (3)0u+(3)0_{u}^{+} state with 6p[1/2]06p [1/2]_{0} atomic limit and the dissociative (1)0g+(1)0_{g}^{+} state with 6s[3/2]16s [3/2]_{1} limit. Comparison with the spectrum simulated by using theoretical potentials shows that the dissociative one does not reproduce correctly the spectrum features.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
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