1,960 research outputs found

    Influence of crystal structure on charge carrier effective masses in BiFeO3_3

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    Ferroelectric-based photovoltaics have shown great promise as a source of renewable energy, thanks to their in-built charge separation capability, yet their efficiency is often limited by low charge carrier mobilities. In this work, we compare the photovoltaic prospects of various phases of the multiferroic material BiFeO3_3 by evaluating their charge carrier effective masses using first-principles simulations. We identify a tetragonal phase with the promising combination of a large spontaneous polarisation and relatively light charge carriers. From a systematic study of the octahedral distortions present in BiFeO3_3, we explain the relationship between structure and effective masses in terms of the changes to the orbital character and overlap at the band edges that result from changes in the geometry. The findings in this study provide some design principles to engineer desired effective masses in BiFeO3_3 and similar materials through manipulation of their crystal structures in experimentally accessible ways.Comment: 12 pages, 10 figure

    Does brand attachment protect consumer–brand relationships after brand misconduct in retail banking?

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    Purpose This research aims to examine the role of consumers' brand trust and attachment on advocacy intention before and after the occurrence of brand misconduct in retail banking. In addition, the influence of brand attachment on consumers' willingness to switch, advocate for and forgive brands is examined in a post-misconduct scenario. Design/methodology/approach Data were collected through a self-administered online survey questionnaire. A total of 304 valid and usable responses from Australian participants were analysed using IBM SPSS 27.0. Findings The findings reveal that brand attachment mediates the positive relationship between trust and advocacy intention. Furthermore, brand attachment (1) dilutes consumers' switching intention and (2) strengthens their willingness to forgive the bank after misconduct. Practical implications Results suggest that retail banks should create strong brand attachments with their consumers. In addition to brand trust, brand attachment will generate greater advocacy intention among consumers. Moreover, practitioners in retail banking can leverage brand attachment to mitigate the negative impact of brand misconduct. Originality/value To the best of the authors' knowledge, this study is the first to examine the impact of brand attachment on the consumer–bank relationship within the context of brand misconduct. The study is also unique in its analysis of the mediating role of brand attachment between brand trust and advocacy. This research further adds to the current literature by suggesting that strong and positive customer connections to the brand facilitate communication and marketing efforts after brand misconduct and that these are effective in maintaining consumer-bank relationship.©2023 Emerald Publishing Limited. This manuscript version is made available under the Creative Commons Attribution–NonCommercial 4.0 International (CC BY–NC 4.0) license, https://creativecommons.org/licenses/by-nc/4.0/fi=vertaisarvioitu|en=peerReviewed

    A silent speech system based on permanent magnet articulography and direct synthesis

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    In this paper we present a silent speech interface (SSI) system aimed at restoring speech communication for individuals who have lost their voice due to laryngectomy or diseases affecting the vocal folds. In the proposed system, articulatory data captured from the lips and tongue using permanent magnet articulography (PMA) are converted into audible speech using a speaker-dependent transformation learned from simultaneous recordings of PMA and audio signals acquired before laryngectomy. The transformation is represented using a mixture of factor analysers, which is a generative model that allows us to efficiently model non-linear behaviour and perform dimensionality reduction at the same time. The learned transformation is then deployed during normal usage of the SSI to restore the acoustic speech signal associated with the captured PMA data. The proposed system is evaluated using objective quality measures and listening tests on two databases containing PMA and audio recordings for normal speakers. Results show that it is possible to reconstruct speech from articulator movements captured by an unobtrusive technique without an intermediate recognition step. The SSI is capable of producing speech of sufficient intelligibility and naturalness that the speaker is clearly identifiable, but problems remain in scaling up the process to function consistently for phonetically rich vocabularies

    DC Leakage behavior and Conduction Mechanism in (BiFeO3)m(SrTiO3)m Superlattices

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    Leakage current behavior of (BiFeO3)m(SrTiO3)m superlattice structures was studied and analyzed at different temperatures (303-473K) in the light of various models. While bulk limited Poole-Frenkel emission was observed to dominate the leakage current in the temperature range of 303 - 383 K, the space charge limited conduction was observed up to 473 K. With a Poole-Frenkel emission type of conduction, the activation energy range of 0.06 - 0.2 eV was calculated. The physical parameters, calculated from the analysis correlates with the intrinsic properties. The analysis of leakage current facilitates, interface engineering of heterostructures for device applications.Comment: Submitted to Applied Physics Letter

    Integrating user-centred design in the development of a silent speech interface based on permanent magnetic articulography

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    Abstract: A new wearable silent speech interface (SSI) based on Permanent Magnetic Articulography (PMA) was developed with the involvement of end users in the design process. Hence, desirable features such as appearance, port-ability, ease of use and light weight were integrated into the prototype. The aim of this paper is to address the challenges faced and the design considerations addressed during the development. Evaluation on both hardware and speech recognition performances are presented here. The new prototype shows a com-parable performance with its predecessor in terms of speech recognition accuracy (i.e. ~95% of word accuracy and ~75% of sequence accuracy), but significantly improved appearance, portability and hardware features in terms of min-iaturization and cost

    SOXE neofunctionalization and elaboration of the neural crest during chordate evolution

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    During chordate evolution, two genome-wide duplications facilitated acquisition of vertebrate traits, including emergence of neural crest cells (NCCs), in which neofunctionalization of the duplicated genes are thought to have facilitated development of craniofacial structures and the peripheral nervous system. How these duplicated genes evolve and acquire the ability to specify NC and their derivatives are largely unknown. Vertebrate SoxE paralogues, most notably Sox9/10, are essential for NC induction, delamination and lineage specification. In contrast, the basal chordate, amphioxus, has a single SoxE gene and lacks NC-like cells. Here, we test the hypothesis that duplication and divergence of an ancestral SoxE gene may have facilitated elaboration of NC lineages. By using an in vivo expression assay to compare effects of AmphiSoxE and vertebrate Sox9 on NC development, we demonstrate that all SOXE proteins possess similar DNA binding and homodimerization properties and can induce NCCs. However, AmphiSOXE is less efficient than SOX9 in transactivation activity and in the ability to preferentially promote glial over neuronal fate, a difference that lies within the combined properties of amino terminal and transactivation domains. We propose that acquisition of AmphiSoxE expression in the neural plate border led to NCC emergence while duplication and divergence produced advantageous mutations in vertebrate homologues, promoting elaboration of NC traits.published_or_final_versio

    Pigmentation and dermal conservative effects of the astonishing algae Sargassum Polycystum and Padina tenuis on guinea pigs, Human Epidermal Melanocytes (HEM) and Chang cells

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    Background: The preference for a fairer skin-tone has become a common trend among both men and women around the world. In this study, seaweeds Sargassum polycystum and Padina tenuis were investigated for their in vitro and in vivo potentials in working as skin whitening agents.Seaweed has been used as a revolutionary skin repairing agent in both traditional and modern preparations. The high antioxidant content is one of the prime reasons for its potent action. It has been employed in  traditional Chinese and Japanese medicine. For centuries, most medicalpractitioners in the Asian cultures have known seaweed as an organic  source of vitamins, minerals, fatty acids like omega-3 and omega-6 andantioxidants. The present objective of the study was to evaluate the potent dermal protective effect of the two seaweeds Sargassum polycystum and Padina tenuis on human cell lines and guinea pigs.Material and Methods: Seaweeds were extracted with ethanol and further fractionated with hexane, ethyl acetate and water. The extracts were tested for mushroom tyrosinase inhibitory activity, cytotoxicity in human epidermal melanocyte (HEM), and Chang cells. Extracts with potent melanocytotoxicity were formulated into cosmetic cream and tested on guinea pigs in dermal irritation tests and de-pigmentation assessments.Results: Both Sargassum polycystum and Padina tenuis seaweeds showed significant inhibitory effect on mushroom tyrosinase in the concentration tested. SPEt showed most potent cytotoxicity on HEM (IC50 of 36µg/ml), followed by SPHF (65µg/ml), and PTHF (78.5µg/ml). SPHF and SPEt reduced melanin content in skin of guinea pigs when assessed histologically.Conclusion: SPEt, SPHF and PTHF were able to inhibit HEM proliferation in vitro, with SPHF being most potent and did not cause any dermal irritation in guinea pigs. The results obtained indicate that SPHF is a promising  pharmacological or cosmetic agent.Key words: Hyper-pigmentation, Melanogenesis, Padina tenuis,  Sargassum polycystum, Tyrosinase, Whitening effect

    Geospatial modelling of watershed peak flood discharge in Selangor, Malaysia

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    © 2019 by the authors. Conservative peak flood discharge estimation methods such as the rational method do not take into account the soil infiltration of the precipitation, thus leading to inaccurate estimations of peak discharges during storm events. The accuracy of estimated peak flood discharge is crucial in designing a drainage system that has the capacity to channel runoffs during a storm event, especially cloudbursts and in the analysis of flood prevention and mitigation. The aim of this study was to model the peak flood discharges of each sub-watershed in Selangor using a geographic information system (GIS). The geospatial modelling integrated the watershed terrain model, the developed Soil Conservation Service Curve Cumber (SCS-CN) and precipitation to develop an equation for estimation of peak flood discharge. Hydrological Engineering Center-Hydrological Modeling System (HEC-HMS) was used again to simulate the rainfall-runoffbased on the Clark-unit hydrograph to validate the modelled estimation of peak flood discharge. The estimated peak flood discharge showed a coefficient of determination, r2 of 0.9445, when compared with the runoffsimulation of the Clark-unit hydrograph. Both the results of the geospatial modelling and the developed equation suggest that the peak flood discharge of a sub-watershed during a storm event has a positive relationship with the watershed area, precipitation and Curve Number (CN), which takes into account the soil bulk density and land-use of the studied area, Selangor in Malaysia. The findings of the study present a comparable and holistic approach to the estimation of peak flood discharge in a watershed which can be in the absence of a hydrodynamic simulation model
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