82 research outputs found

    Synchrotron Radiation Dominates the Extremely Bright GRB 221009A

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    The brightest Gamma-ray burst, GRB 221009A, has spurred numerous theoretical investigations, with particular attention paid to the origins of ultra-high energy TeV photons during the prompt phase. However, analyzing the mechanism of radiation of photons in the \simMeV range has been difficult because the high flux causes pile-up and saturation effects in most GRB detectors. In this letter, we present systematic modeling of the time-resolved spectra of the GRB using unsaturated data obtained from Fermi/GBM (precursor) and SATech-01/GECAM-C (main emission and flare). Our approach incorporates the synchrotron radiation model, which assumes an expanding emission region with relativistic speed and a global magnetic field that decays with radius, and successfully fits such a model to the observational data. Our results indicate that the spectra of the burst are fully in accordance with a synchrotron origin from relativistic electrons accelerated at a large emission radius. The lack of thermal emission in the prompt emission spectra supports a Poynting-flux-dominated jet composition.Comment: 12 pages, 6 figures, 2 tables. Accepted for publication in ApJ

    Rhetoric and reality: Critical perspective on education in a 3D virtual world

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    The emergence of any new educational technology is often accompanied by inflated expectations about its potential for transforming pedagogical practice and improving student learning outcomes. A critique of the rhetoric accompanying the evolution of 3D virtual world education reveals a similar pattern, with the initial hype based more on rhetoric than research demonstrating the extent to which rhetoric matches reality. Addressed are the perceived gaps in the literature through a critique of the rhetoric evident throughout the evolution of the application of virtual worlds in education and the reality based on the reported experiences of experts in the field of educational technology, who are all members of the Australian and New Zealand Virtual Worlds Working Group. The experiences reported highlight a range of effective virtual world collaborative and communicative teaching experiences conducted in members’ institutions. Perspectives vary from those whose reality is the actuation of the initial rhetoric in the early years of virtual world education, to those whose reality is fraught with challenges that belie the rhetoric. Although there are concerns over institutional resistance, restrictions, and outdated processes on the one-hand, and excitement over the rapid emergence of innovation on the other, the prevailing reality seems to be that virtual world education is both persistent and sustainable. Explored are critical perspectives on the rhetoric and reality on the educational uptake and use of virtual worlds in higher education, providing an overview of the current and future directions for learning in virtual worlds

    The outlook of building information modeling for sustainable development

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    As human needs evolve, information technologies and natural environments require a wider perspective of sustainable development, especially when examining the built environment that impacts the central of social-ecological systems. The objectives of the paper are (a) to review the status and development of building information modeling (BIM) in regards to the sustainable development in the built environment, and (b) to develop a future outlook framework that promotes BIM in sustainable development. Seven areas of sustainability were classified to analyze forty-four BIM guidelines and standards. This review examines the use of BIM in sustainable development, focusing primarily on certain areas of sustainability, such as project development, design, and construction. The developed framework describes the need for collaboration with the multiple disciplines for the future adoption and use of BIM for the sustainable development. It also considers the integration between “BIM and green assessment criteria”; and “BIM and renewable energy” to address the shortcomings of the standards and guidelines

    Rhetoric and reality: Critical perspective on education in a 3D virtual world

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    The emergence of any new educational technology is often accompanied by inflated expectations about its potential for transforming pedagogical practice and improving student learning outcomes. A critique of the rhetoric accompanying the evolution of 3D virtual world education reveals a similar pattern, with the initial hype based more on rhetoric than research demonstrating the extent to which rhetoric matches reality. Addressed are the perceived gaps in the literature through a critique of the rhetoric evident throughout the evolution of the application of virtual worlds in education and the reality based on the reported experiences of experts in the field of educational technology, who are all members of the Australian and New Zealand Virtual Worlds Working Group. The experiences reported highlight a range of effective virtual world collaborative and communicative teaching experiences conducted in members’ institutions. Perspectives vary from those whose reality is the actuation of the initial rhetoric in the early years of virtual world education, to those whose reality is fraught with challenges that belie the rhetoric. Although there are concerns over institutional resistance, restrictions, and outdated processes on the one-hand, and excitement over the rapid emergence of innovation on the other, the prevailing reality seems to be that virtual world education is both persistent and sustainable. Explored are critical perspectives on the rhetoric and reality on the educational uptake and use of virtual worlds in higher education, providing an overview of the current and future directions for learning in virtual worlds

    Crystal Structure of Outer Membrane Protein NMB0315 from Neisseria meningitidis

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    NMB0315 is an outer membrane protein of Neisseria meningitidis serogroup B (NMB) and a potential candidate for a broad-spectrum vaccine against meningococcal disease. The crystal structure of NMB0315 was solved by single-wavelength anomalous dispersion (SAD) at a resolution of 2.4 Å and revealed to be a lysostaphin-type peptidase of the M23 metallopeptidase family. The overall structure consists of three well-separated domains and has no similarity to any previously published structure. However, only the topology of the carboxyl-terminal domain is highly conserved among members of this family, and this domain is a zinc-dependent catalytic unit. The amino-terminal domain of the structure blocks the substrate binding pocket in the carboxyl-terminal domain, indicating that the wild-type full-length protein is in an inactive conformational state. Our studies improve the understanding of the catalytic mechanism of M23 metallopeptidases

    Characterizing Acupuncture Stimuli Using Brain Imaging with fMRI - A Systematic Review and Meta-Analysis of the Literature

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    Background The mechanisms of action underlying acupuncture, including acupuncture point specificity, are not well understood. In the previous decade, an increasing number of studies have applied fMRI to investigate brain response to acupuncture stimulation. Our aim was to provide a systematic overview of acupuncture fMRI research considering the following aspects: 1) differences between verum and sham acupuncture, 2) differences due to various methods of acupuncture manipulation, 3) differences between patients and healthy volunteers, 4) differences between different acupuncture points. Methodology/Principal Findings We systematically searched English, Chinese, Korean and Japanese databases for literature published from the earliest available up until September 2009, without any language restrictions. We included all studies using fMRI to investigate the effect of acupuncture on the human brain (at least one group that received needle-based acupuncture). 779 papers were identified, 149 met the inclusion criteria for the descriptive analysis, and 34 were eligible for the meta-analyses. From a descriptive perspective, multiple studies reported that acupuncture modulates activity within specific brain areas, including somatosensory cortices, limbic system, basal ganglia, brain stem, and cerebellum. Meta-analyses for verum acupuncture stimuli confirmed brain activity within many of the regions mentioned above. Differences between verum and sham acupuncture were noted in brain response in middle cingulate, while some heterogeneity was noted for other regions depending on how such meta-analyses were performed, such as sensorimotor cortices, limbic regions, and cerebellum. Conclusions Brain response to acupuncture stimuli encompasses a broad network of regions consistent with not just somatosensory, but also affective and cognitive processing. While the results were heterogeneous, from a descriptive perspective most studies suggest that acupuncture can modulate the activity within specific brain areas, and the evidence based on meta-analyses confirmed some of these results. More high quality studies with more transparent methodology are needed to improve the consistency amongst different studies

    Evaluating the Usability of Virtual Environment by Emplyoing Affective Measures

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