33 research outputs found

    The initial fusion pore induced by baculovirus GP64 is large and forms quickly.

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    Modeling quality and prestige in applied linguistics journals: A bibliometric and synthetic analysis

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    The importance of academic journals in second language (L2) research is evident on at least two levels. Journals are, first of all, central to the process of disseminating scientific findings. Journals are also critical on a professional level as most L2 researchers must publish articles to advance their careers. However, not all journals are perceived as equal; some may be considered more prestigious or of higher quality and may, therefore, achieve a greater impact on the field. It is therefore necessary that we understand the identity and quality of L2 research journals, yet very little research (e.g., Egbert, 2007; VanPatten & Williams, 2002) has considered these issues to date. The current study sought to explore L2 journal identity and quality, and the relationship between these constructs. In order to do so, a database was compiled based on three different types of sources: (1) a questionnaire eliciting L2 researchers’ perceptions of the quality and prestige of 27 journals that publish L2 research (N = 327); (2) manual coding of different types of articles (e.g., empirical studies, review papers), data (quantitative, qualitative, mixed), research settings, and authorship patterns (K = 2,024) using the same 27 journals; and (3) bibliometric and submission data such as impact factors, citation counts, and acceptance rates. Descriptive statistics were applied to explore overall quality and prestige ratings as well as publication trends found in each journal. The relationships between those patterns and subjective ratings were also examined. In addition, regression models were built to determine the extent to which perceptions of journal quality and prestige could be explained as a function of journal and article features. We discuss the findings of the study in terms of on-going debates concerning publication practices, study quality, impact factors, journal selection, and the “journal culture” in applied linguistics

    Learning in settings with partial feedback and the wavy recency effect of rare events

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    Analyses of human learning reveal a discrepancy between the long- and the short-term effects of outcomes on subsequent choice. The long-term effect is simple: favorable outcomes increase the choice rate of an alternative whereas unfavorable outcomes decrease it. The short-term effects are more complex. Favorable outcomes can decrease the choice rate of the best option. This pattern violates the positive recency assumption that underlies the popular models of learning. The current research tries to clarify the implications of these results. Analysis of wide sets of learning experiments shows that rare positive outcomes have a wavy recency effect. The probability of risky choice after a successful outcome from risk-taking at trial t is initially (at t + 1) relatively high, falls to a minimum at t + 2, then increases for about 15 trials, and then decreases again. Rare negative outcomes trigger a wavy reaction when the feedback is complete, but not under partial feedback. The difference between the effects of rare positive and rare negative outcomes and between full and partial feedback settings can be described as a reflection of an interaction of an effort to discover patterns with two other features of human learning: surprise-triggers-change and the hot stove effect. A similarity-based descriptive model is shown to capture well all these interacting phenomena. In addition, the model outperforms the leading models in capturing the outcomes of data used in the 2010 Technion Prediction Tournament

    Fusion pore conductance: experimental approaches and theoretical algorithms.

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    Time-resolved admittance measurements provide the basis for studies showing that membrane fusion occurs through the formation and widening of an initially small pore, linking two previously separated aqueous compartments. Here we introduce modifications to this method that correct the cell-pipette (source) admittance for attenuation and phase shifts produced by electrophysiological equipment. Two new approaches for setting the right phase angle are discussed. The first uses the displacement of a patch-clamp amplifier C-slow potentiometer for the calculation of phase. This calculation is based on amplitudes of observed and expected (theoretical) changes in the source admittance. The second approach automates the original phase adjustment, the validity of which we prove analytically for certain conditions. The multiple sine wave approach is modified to allow the calculation of target cell membrane parameters and the conductance of the fusion pore. We also show how this technique can be extended for measurements of the resting potential of the first (voltage-clamped) membrane. We introduce an algorithm for calculation of fusion pore conductance despite a concurrent change in the resistance of the clamped membrane. The sensitivity of the capacitance restoration algorithm to phase shift errors is analyzed, and experimental data are used to demonstrate the results of this analysis. Finally, we show how the phase offset can be corrected "off-line" by restoring the shape of the capacitance increment

    A GP64-Null Baculovirus Pseudotyped with Vesicular Stomatitis Virus G Protein

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    The Autographa californica multiple nucleopolyhedrovirus (AcMNPV) GP64 protein is an essential virion protein that is involved in both receptor binding and membrane fusion during viral entry. Genetic studies have shown that GP64-null viruses are unable to move from cell to cell and this results from a defect in the assembly and production of budded virions (BV). To further examine requirements for virion budding, we asked whether a GP64-null baculovirus, vAc(64−), could be pseudotyped by introducing a heterologous viral envelope protein (vesicular stomatitis virus G protein [VSV-G]) into its membrane and whether the resulting virus was infectious. To address this question, we generated a stably transfected insect Sf9 cell line (Sf9(VSV-G)) that inducibly expresses the VSV-G protein upon infection with AcMNPV Sf9(VSV-G) and Sf9 cells were infected with vAc(64−), and cells were monitored for infection and for movement of infection from cell to cell. vAc(64−) formed plaques on Sf9(VSV-G) cells but not on Sf9 cells, and plaques formed on Sf9(VSV-G) cells were observed only after prolonged intervals. Passage and amplification of vAc(64−) on Sf9(VSV-G) cells resulted in pseudotyped virus particles that contained the VSV-G protein. Cell-to-cell propagation of vAc(64−) in the G-expressing cells was delayed in comparison to wild-type (wt) AcMNPV, and growth curves showed that pseudotyped vAc(64−) was generated at titers of approximately 10(6) to 10(7) infectious units (IU)/ml, compared with titers of approximately 10(8) IU/ml for wt AcMNPV. Propagation and amplification of pseudotyped vAc(64−) virions in Sf9(VSV-G) cells suggests that the VSV-G protein may either possess the signals necessary for baculovirus BV assembly and budding at the cell surface or may otherwise facilitate production of infectious baculovirus virions. The functional complementation of GP64-null viruses by VSV-G protein was further demonstrated by identification of a vAc(64−)-derived virus that had acquired the G gene through recombination with Sf9(VSV-G) cellular DNA. GP64-null viruses expressing the VSV-G gene were capable of productive infection, replication, and propagation in Sf9 cells
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