970 research outputs found

    Content-Based Instruction (CBI) for the Social Future: A Recommendation for Critical Content-Based Language Instruction (CCBI)

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    In this article, we seek to reconceptualize content-based instruction (CBI) curricula and practices from a critical perspective. Further, we propose developing criticality as an essential component of CBI, advocating for an approach we call critical content-based instruction (CCBI). While the importance of CBI has long been recognized, previous discussions predominantly focused on its effectiveness for language learning (and content learning to a lesser degree), and overlooked its fundamental linkage and relevance to broader educational missions. In order to fully maximize the potential of CBI and envision language education as integral to the advancement of society, we argue that a critical approach to CBI should be considered. First, we lay out how CBI came to be and how it has been treated in language pedagogy. We believe CBI is indeed a suitable forum for introducing and implementing a critical perspective because of its original contribution of broadening language education to meet societal needs. Second, we provide an overview of recent discourse surrounding world language education. Based on these reviews, we lastly and most importantly delineate directions for CCBI by presenting examples and possible challenges

    Inconsistency in the Standard of Care–Toward Evidence-Based Management of Exertional Heat Stroke

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    Tokyo 2020 Summer Olympics are projected to experience environmental heat stress that surpasses the environmental conditions observed in the Atlanta (1996), Athens (2004), Beijing (2008), and Rio (2016) Summer Olympics. This raises particular concerns for athletes who will likely to be exposed to extreme heat during the competitions. Therefore, in mass-participation event during warm season, it is vital for the hosting organization to build preparedness and resilience against heat, including appropriate treatment, and management strategies for exertional heat stroke (EHS). However, despite the existing literature regarding the evidence-based management of EHS, rectal thermometry and whole-body cold-water immersion are not readily accepted by medical professionals outside of the sports, and military medicine professionals. Current Japanese medical standard is no exception in falling behind on evidence-based management of EHS. Therefore, the first aim of this paper is to elucidate the inconsistency between the standard of care provided in Japan for EHS and what has been accepted as the gold standard by the scientific literature. The second aim of this paper is to provide optimal EHS management strategies that should be implemented at the Tokyo 2020 Summer Olympics from organizational level to maximize the safety of athletes and to improve organizational resilience to heat. The risk of extreme heat is often neglected until a catastrophic incidence occurs. It is vital for the Japanese medical leadership and athletic communities to re-examine the current EHS management strategies and implement evidence-based countermeasure for EHS to expand the application of scientific knowledge

    Cold CO Gas in Protoplanetary Disks

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    In a disk around DM Tau, previous observation of 13CO (J=2-1 and 1-0 transitions) derived the 13CO gas temperature of \sim 13-20K, which is lower than the sublimation temperature of CO (20 K). We argue that the existence of such cold CO can be explained by a vertical mixing of disk material. As the gas is transported from a warm layer to a cold layer, CO is depleted onto dust grains with a timescale of \sim 10^3 yr. Because of the steep temperature gradient in the vertical direction, an observable amount of CO is still in the gas phase when the fluid parcel reaches the layer of \sim 13 K. Apparent temperature of CO decreases as the maximum grain size increases from micron-size to mm-size.Comment: 11 pages, 2 figures, accepted to ApJ

    Molecular Evolution in Collapsing Prestellar Cores III: Contraction of A Bonnor-Ebert Sphere

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    The gravitational collapse of a spherical cloud core is investigated by numerical calculations. The initial conditions of the core lie close to the critical Bonnor-Ebert sphere with a central density of \sim 10^4 cm^{-3} in one model (alpha=1.1), while gravity overwhelms pressure in the other (alpha=4.0), where alpha is the internal gravity-to-pressure ratio. The alpha=1.1 model shows reasonable agreement with the observed velocity field in prestellar cores. Molecular distributions in cores are calculated by solving a chemical reaction network that includes both gas-phase and grain-surface reactions. When the central density of the core reaches 10^5 cm^{-3}, carbon-bearing species are significantly depleted in the central region of the alpha=1.1 model, while the depletion is only marginal in the other model. The two different approaches encompass the observed variations of molecular distributions in different prestellar cores, suggesting that molecular distributions can be probes of contraction or accumulation time scales of cores. The central enhancement of the NH3/N2H+ ratio, which is observed in some prestellar cores, can be reproduced under certain conditions by adopting recently measured branching fractions for N2H+ recombination. Various molecular species, such as CH3OH and CO2, are produced by grain-surface reactions. The ice composition depends sensitively on the assumed temperature. Multi-deuterated species are included in our most recent gas-grain chemical network. The deuterated isotopomers of H3+ are useful as probes of the central regions of evolved cores, in which gas-phase species with heavy elements are strongly depleted. At 10 K, our model can reproduce the observed abundance ratio of ND3/NH3, but underestimates the isotopic ratios of deuterated to normal methanol.Comment: 38 pages, 9 figure

    Multi-component optical solitary waves

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    We discuss several novel types of multi-component (temporal and spatial) envelope solitary waves that appear in fiber and waveguide nonlinear optics. In particular, we describe multi-channel solitary waves in bit-parallel-wavelength fiber transmission systems for high performance computer networks, multi-colour parametric spatial solitary waves due to cascaded nonlinearities of quadratic materials, and quasiperiodic envelope solitons due to quasi-phase-matching in Fibonacci optical superlattices.Comment: 12 pages, 11 figures; To be published in: Proceedings of the Dynamics Days Asia-Pacific: First International Conference on Nonlinear Science (Hong-Kong, 13-16 July, 1999), Editor: Bambi Hu (Elsevier Publishers, 2000

    Quasiperiodic Envelope Solitons

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    We analyse nonlinear wave propagation and cascaded self-focusing due to second-harmonic generation in Fibbonacci optical superlattices and introduce a novel concept of nonlinear physics, the quasiperiodic soliton, which describes spatially localized self-trapping of a quasiperiodic wave. We point out a link between the quasiperiodic soliton and partially incoherent spatial solitary waves recently generated experimentally.Comment: Submitted to PRL. 4 pages with 5 figure

    Molecular Evolution in Collapsing Prestellar Cores

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    We have investigated the evolution and distribution of molecules in collapsing prestellar cores via numerical chemical models, adopting the Larson-Penston solution and its delayed analogues to study collapse. Molecular abundances and distributions in a collapsing core are determined by the balance among the dynamical, chemical and adsorption time scales. When the central density n_H of a prestellar core with the Larson-Penston flow rises to 3 10^6 cm^{-3}, the CCS and CO column densities are calculated to show central holes of radius 7000 AU and 4000 AU, respectively, while the column density of N2H+ is centrally peaked. These predictions are consistent with observations of L1544. If the dynamical time scale of the core is larger than that of the Larson-Penston solution owing to magnetic fields, rotation, or turbulence, the column densities of CO and CCS are smaller, and their holes are larger than in the Larson-Penston core with the same central gas density. On the other hand, N2H+ and NH3 are more abundant in the more slowly collapsing core. Therefore, molecular distributions can probe the collapse time scale of prestellar cores. Deuterium fractionation has also been studied via numerical calculations. The deuterium fraction in molecules increases as a core evolves and molecular depletion onto grains proceeds. When the central density of the core is n_H=3 10^6 cm^{-3}, the ratio DCO+/HCO+ at the center is in the range 0.06-0.27, depending on the collapse time scale and adsorption energy; this range is in reasonable agreement with the observed value in L1544.Comment: 21 pages, 17 figure

    Biological Differences Between Ovarian Cancer-associated Fibroblasts and Contralateral Normal Ovary-derived Mesenchymal Stem Cells

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    Background/Aim: The aim of this study was to clarify the biological differences between ovarian cancerassociated fibroblasts (OCa-CAFs) and normal ovary-derived mesenchymal stem cells (NO-MSCs). Materials and Methods: Surgically resected ovarian cancer and contralateral normal ovarian tissue samples were cut into small pieces for culture as “explants”. The number of outgrown cells, their proliferative kinetics, and expression levels of cell surface markers of CAFs, as well as three miRNAs in OCa-CAFs and NO-MSCs were compared directly. Differentially expressed genes between both groups were also investigated. Results: Comparable numbers of outgrown cells were harvested from both groups. Significantly higher expression of α-smooth muscle actin and miR-142 was found in OCa-CAFs, which decreased significantly during ex vivo cell expansion. A total of 21 differentially expressed genes were identified between both groups. Conclusion: OCa-CAFs showed different biological properties in direct comparison with NO-MSCs, which might play major roles in the pathogenesis of ovarian cancer

    Evolution of Molecular Abundance in Protoplanetary Disks

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    We investigate the evolution of molecular abundance in quiescent protoplanetary disks which are presumed to be around weak-line T Tauri stars. In the region of surface density less than 10210^2 g cm−2^{-2} (distance from the star ≳10\gtrsim 10 AU in the minimum- mass solar nebula), cosmic rays are barely attenuated even in the midplane of the disk and produce chemically active ions such as He+^+ and H3+_{3}^+. Through reactions with these ions CO and N2_2 are finally transformed into CO2_2, NH3_3, and HCN. In the region where the temperature is low enough for these products to freeze onto grains, considerable amount of carbon and nitrogen is locked up in the ice mantle and is depleted from the gas phase in a time scale â‰Č3×106\lesssim 3\times 10^6 yr. Oxidized (CO2_2) ice and reduced (NH3_3 and hydrocarbon) ice naturally coexist in this part of the disk. The molecular abundance both in the gas phase and in ice mantle varies significantly with the distance from the central star.Comment: 7 pages latex file (using aas2pp4.sty), 3 figures (ps file), to appear in the Astrophysical Journal Letter

    A ferromagnetic Eu–Pt surface compound grown below hexagonal boron nitride

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    One of the fundamental applications for monolayer-thick 2D materials is their use as protective layers of metal surfaces and in situ intercalated reactive materials in ambient conditions. Here we investigate the structural, electronic, and magnetic properties, as well as the chemical stability in air of a very reactive metal, Europium, after intercalation between a hexagonal boron nitride (hBN) layer and a Pt substrate. We demonstrate that Eu intercalation leads to a hBN-covered ferromagnetic EuPt2 surface alloy with divalent Eu2+ atoms at the interface. We expose the system to ambient conditions and find a partial conservation of the di-valent signal and hence the Eu–Pt interface. The use of a curved Pt substrate allows us to explore the changes in the Eu valence state and the ambient pressure protection at different substrate planes. The interfacial EuPt2 surface alloy formation remains the same, but the resistance of the protecting hBN layer to ambient conditions is reduced, likely due to a rougher surface and a more discontinuous hBN coating
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