621 research outputs found

    Guide to the Networked Minds Social Presence Inventory v. 1.2

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    This document introduces the Networked\ud Minds Social Presence Inventory. The\ud inventory is a self-report measure of social\ud presence, which is commonly defined as the\ud sense of being together with another in a\ud mediated environment. The guidelines\ud provide background on the use of the social\ud presence scales in studies of users’ social\ud communication and interaction with other\ud humans or with artificially intelligent agents\ud in virtual environments

    Internal Consistency and Reliability of the Networked Minds\ud Measure of Social Presence

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    This study sought to develop and test a measure\ud of social presence. Based on review of current\ud definitions and measures, a synthesis of the\ud theoretical construct that meets the criteria and\ud dimensions [1] is proposed for a broad successful\ud measure of social presence. An experiment was\ud conducted to test the internal consistency and\ud criterion validity of the measures as determined by\ud theory, specifically the ability of the measure to\ud distinguish levels of social presence that almost all\ud theories suggest exist between (1) face-to-face\ud interaction and mediated interaction, and (2)\ud different levels of mediated interaction

    Networked Minds Social Presence Inventory:\ud |(Scales only, Version 1.2)\ud Measures of co-presence, social presence,\ud subjective symmetry, and intersubjective symmetry

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    This document includes all the items that comprise the Networked Minds Social Presence Inventory. For more information on the scale, please consult the Guide to the Networked Minds Inventory on this repository

    Advanced Process Analytical Technology in combination with process modeling for endpoint and model parameter determination in lyophilization process design and optimization

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    Lyophilization is widely used in the preservation of thermolabile products. The main shortcoming is the long processing time. Lyophilization processes are mostly based on a recipe that is not changed, but, with the Quality by Design (QbD) approach and use of Process Analytical Technology (PAT), the process duration can be optimized for maximum productivity while ensuring product safety. In this work, an advanced PAT approach is used for the endpoint determination of primary drying. Manometric temperature measurement (MTM) and comparative pressure measurement are used to determine the endpoint of the batch while a modeling approach is outlined that is able to calculate the endpoint of every vial in the batch. This approach can be used for process development, control and optimization

    Emerging PAT for freeze-drying processes for advanced process control

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    Lyophilization is a widely used drying operation, but long processing times are a major drawback. Most lyophilization processes are conducted by a recipe that is not changed or optimized after implementation. With the regulatory demanded quality by design (QbD) approach, the process can be controlled inside an optimal range, ensuring safe process conditions. Process analytical technology (PAT) is crucial because it allows real-time monitoring and is part of a control strategy. In this work, emerging PAT (manometric temperature measurement (MTM), comparative pressure measurement, heat flux sensors, and ice ruler) are used for measurements during the freeze-drying process, and their potential for implementation inside a control strategy is outlined

    Effect of the freezing step on primary drying experiments and simulation of lyophilization processes

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    Lyophilization is a widely used preservation method for thermosensitive products. It consists of three process steps: freezing, primary and secondary drying. One of the major drawbacks is the long processing time. The main optimization effort was put into the primary drying phase since it is usually the longest phase. However, the freezing step is of immense importance for process efficiency and product quality. The lack of control during freezing comprises a challenge for process design and tech transfer. In this study, four different freezing steps (shelf-ramped freezing with and without holding step, precooled shelves and an ice fog method for controlled nucleation) are used and their impact on primary drying experiments and simulations is shown. Only the ice fog method is able to control the nucleation temperature leading to low dry layer resistances with low deviations. During the primary drying simulations, the control of the nucleation temperature drastically increases the precision and accuracy of the product temperature prediction. For optimal primary drying design and model predictive control, the nucleation temperature is strongly recommended to be controlled inside a Process Analytical Technology (PAT) concept to achieve reliable and reproducible process conditions

    Model-based product temperature and endpoint determination in primary drying of lyophilization processes

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    Lyophilization process design still relies mainly on empirical studies with high experimental loads. In the regulatory demanded Quality by Design approach, process modeling is a key aspect. It allows process design, optimization and process control to ensure a safe process and product quality. A modeling approach is outlined that is able to predict the primary drying endpoint and temperature profile of distinct vials. Model parameters are determined by a reproducible determination concept. Simulated results are validated with a fractional factorial Design of Experiments (DoE) in pilot scale. The model shows higher accuracy and precision than the experiments and similar parameter interactions for both the endpoint and temperature determination. This approach can now be used to explore the primary design space in lyophilization process design. This paper proposes a distinct method for endpoint determination and product temperature prediction by a modeling approach based on Velardi et al. combined with a distinct model parameter determination according to Wegiel et al. and Tang et al

    Alterations at the peptidyl transferase centre of the ribosome induced by the synergistic action of the streptogramins dalfopristin and quinupristin

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    BACKGROUND: The bacterial ribosome is a primary target of several classes of antibiotics. Investigation of the structure of the ribosomal subunits in complex with different antibiotics can reveal the mode of inhibition of ribosomal protein synthesis. Analysis of the interactions between antibiotics and the ribosome permits investigation of the specific effect of modifications leading to antimicrobial resistances. Streptogramins are unique among the ribosome-targeting antibiotics because they consist of two components, streptogramins A and B, which act synergistically. Each compound alone exhibits a weak bacteriostatic activity, whereas the combination can act bactericidal. The streptogramins A display a prolonged activity that even persists after removal of the drug. However, the mode of activity of the streptogramins has not yet been fully elucidated, despite a plethora of biochemical and structural data. RESULTS: The investigation of the crystal structure of the 50S ribosomal subunit from Deinococcus radiodurans in complex with the clinically relevant streptogramins quinupristin and dalfopristin reveals their unique inhibitory mechanism. Quinupristin, a streptogramin B compound, binds in the ribosomal exit tunnel in a similar manner and position as the macrolides, suggesting a similar inhibitory mechanism, namely blockage of the ribosomal tunnel. Dalfopristin, the corresponding streptogramin A compound, binds close to quinupristin directly within the peptidyl transferase centre affecting both A- and P-site occupation by tRNA molecules. CONCLUSIONS: The crystal structure indicates that the synergistic effect derives from direct interaction between both compounds and shared contacts with a single nucleotide, A2062. Upon binding of the streptogramins, the peptidyl transferase centre undergoes a significant conformational transition, which leads to a stable, non-productive orientation of the universally conserved U2585. Mutations of this rRNA base are known to yield dominant lethal phenotypes. It seems, therefore, plausible to conclude that the conformational change within the peptidyl transferase centre is mainly responsible for the bactericidal activity of the streptogramins and the post-antibiotic inhibition of protein synthesis

    Evaluation of the dynamic core of the PALM model system 6.0 in a neutrally stratified urban environment: comparison between LES and wind-tunnel experiments

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    We demonstrate the capability of the PALM model system version 6.0 to simulate neutrally stratified urban boundary layers. Our simulation uses the real-world building configuration of the HafenCity area in Hamburg, Germany. Using PALM's virtual measurement module, we compare simulation results to wind-tunnel measurements of a downscaled replica of the study area. Wind-tunnel measurements of mean wind speed agree within 5 % on average while the wind direction deviates by approximately 4∘. Turbulence statistics similarly agree. However, larger differences between measurements and simulation arise in the vicinity of surfaces where building geometry is insufficiently resolved. We discuss how to minimize these differences by improving the grid layout and give tips for setup preparation. Also, we discuss how existing and upcoming features of PALM like the grid nesting and immersed boundary condition help improve the simulation results.publishedVersio

    Evaluation of the dynamic core of the PALM model system 6.0 in a neutrally stratified urban environment: Comparison between les and wind-tunnel experiments

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    We demonstrate the capability of the PALM model system version 6.0 to simulate neutrally stratified urban boundary layers. Our simulation uses the real-world building configuration of the HafenCity area in Hamburg, Germany. Using PALM's virtual measurement module, we compare simulation results to wind-tunnel measurements of a downscaled replica of the study area. Wind-tunnel measurements of mean wind speed agree within 5% on average while the wind direction deviates by approximately 4 °. Turbulence statistics similarly agree. However, larger differences between measurements and simulation arise in the vicinity of surfaces where building geometry is insufficiently resolved. We discuss how to minimize these differences by improving the grid layout and give tips for setup preparation. Also, we discuss how existing and upcoming features of PALM like the grid nesting and immersed boundary condition help improve the simulation results. © 2021 Tobias Gronemeier et al
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