This paper examines the efficacy of FelderSilverman's learning styles and Mayer's generative theory of multimedia learning for adaptive hypermedia using three different modes of presentations-verbal, visual, and multimediain history and engineering disciplines. Six modules in history and engineering were designed in verbal, visual and multimedia modes. Hundred and four undergraduate students of the Indian Institute of Technology Kharagpur participated and completed the six modules. The performance in each module was assessed on the basis of recall, recognition, comprehension, and transfer of learning. Based on Inventory of Learning Styles, learners were categorized in visual-verbal and sequential-global dimensions. The verbal, neutral, and visual learners and the sequential, neutral, and global learners did not differ in performance across disciplines. Learners' performance in visual mode for history and in multimedia mode for engineering was found to be superior to other modes. High academic achievers performed better for recognition and comprehension dimensions in history, and recognition dimension in engineering than low academic achievers. Irrespective of learning styles or academic achievements students preferred and found more appropriate visual and multimedia modes over verbal mode of learning. We believe that the null results for learning styles suggest their limited usability for adaptive hypermedia. Similarly, Mayer's multimedia learning cannot be recommended as the most effective mode of learning for all disciplines. We suggest that adaptivity according to disciplines is an important area that needs to be explored.

Learning styles theories suggest that people learn differently, an important consideration for adaptive hypermedia learning platforms. Since on such platforms, mode of delivery of course material -visual, verbal or multimedia -plays an important role, this study considers learning styles in the context of adaptive hypermedia with the aim to identify if providing material according to one's learning style enhances performance. While some studies report positive results, others find no correlation between the two. Here, we examine the efficacy of learning styles, especially the visual-verbal dimension of Felder-Silverman model, in a controlled e-learning environment by testing the effectiveness of visual, verbal as well as multimedia modules for history and engineering on 268 engineering undergraduates identified on the basis of visual, verbal and mixed orientations. Contrary to expectations, results indicated no relation between learning styles and performance in modules based on different sensory preferences. However, students did show discipline-based better performance in multimedia and visual modes than in verbal mode. They also preferred multimedia and visual modes over verbal. This corroborates earlier findings -the efficacy of learning styles remains unconfirmed.

Phagosome-lysosome fusion in innate immune cells like macrophages and neutrophils marshal an essential role in eliminating intracellular microorganisms. In microbe-challenged macrophages, phagosome-lysosome fusion occurs 4 to 6 h after the phagocytic uptake of the microbe. However, live pathogenic mycobacteria hinder the transfer of phagosomes to lysosomes, up to 20 h post-phagocytic uptake. This period is required to evade pro-inflammatory response and upregulate the acid-stress tolerant proteins. The exact sequence of events through which mycobacteria retards phagolysosome formation remains an enigma. The macrophage coat protein Coronin1(Cor1) is recruited and retained by mycobacteria on the phagosome membrane to retard its maturation by hindering the access of phagosome maturation factors. Mycobacteria-infected macrophages exhibit an increased cAMP level, and based on receptor stimulus, Cor1 expressing cells show a higher level of cAMP than non-Cor1 expressing cells. Here we have shown that infection of bone marrow-derived macrophages with H37Rv causes a Cor1 dependent rise of intracellular cAMP levels at the vicinity of the phagosomes. This increased cAMP fuels cytoskeletal protein Cofilin1 to depolymerize F-actin around the mycobacteria-containing phagosome. Owing to reduced F-actin levels, the movement of the phagosome toward the lysosomes is hindered, thus contributing to the retarded phagosome maturation process. Additionally, Cor1 mediated upregulation of Cofilin1 also contributes to the prevention of phagosomal acidification, which further aids in the retardation of phagosome maturation. Overall, our study provides first-hand information on Cor1 mediated retardation of phagosome maturation, which can be utilized in developing novel peptidomimetics as part of host-directed therapeutics against tuberculosis.

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