1,100 research outputs found

    Appropriate technology for sustainable food security:

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    CONTENTS: Brief 1. Overview / Per Pinstrup-Andersen Brief 2. Farmer-Based Agro-Ecological Technology / Jules Pretty Brief 3. Conventional Research-Based Technology / Prabhu Pingali Brief 4. Modern Biotechnology / Calestous Juma Brief 5. Modern Technology for African Agriculture / Jennifer Thomson Brief 6. Information and Communcations Technologies / Nuimuddin Chowdhury Brief 7. GIS, GPS, and Remote Sensing / Uwe Deichmann and Stanley Wood Brief 8. Alternative Energy Sources / R. K. Pachauri and Pooja Mehrotra Brief 9. Food Irradiation / Morton SatinTechnology., Technological innovations., Food security., Sustainability.,

    Where is the Target? An Examination of the Conceptions of Student Engagement within a School Community

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    In 2017, the Kansas State Department of Education (KSDE) launched an ambitious school redesign project. High Plains High School (pseudonym) was among the schools selected for redesign, and as part of their plan, High Plains High School (HPHS) faculty and staff administered a survey to students. Survey results indicated approximately 38% of students felt “disengaged” at school. HPHS administrators found these results worthy of study, in an attempt to understand how students, faculty, and families were conceptualizing school engagement. Results indicate that each constituency tended toward differing concepts of what it means to be engaged in the classroom. Implications include the need for teacher educators to more deeply address preservice students’ understanding of engagement, as well as a shift to a conceptual understanding of student engagement that is more agentic. Results could catalyze changes in educator preparation programs to improve candidates’ understanding of engagement and its role in student success

    A second order cone formulation of continuous CTA model

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    The final publication is available at link.springer.comIn this paper we consider a minimum distance Controlled Tabular Adjustment (CTA) model for statistical disclosure limitation (control) of tabular data. The goal of the CTA model is to find the closest safe table to some original tabular data set that contains sensitive information. The measure of closeness is usually measured using l1 or l2 norm; with each measure having its advantages and disadvantages. Recently, in [4] a regularization of the l1 -CTA using Pseudo-Huber func- tion was introduced in an attempt to combine positive characteristics of both l1 -CTA and l2 -CTA. All three models can be solved using appro- priate versions of Interior-Point Methods (IPM). It is known that IPM in general works better on well structured problems such as conic op- timization problems, thus, reformulation of these CTA models as conic optimization problem may be advantageous. We present reformulation of Pseudo-Huber-CTA, and l1 -CTA as Second-Order Cone (SOC) op- timization problems and test the validity of the approach on the small example of two-dimensional tabular data set.Peer ReviewedPostprint (author's final draft

    A combination of chitooligosaccharide and lipochitooligosaccharide recognition promotes arbuscular mycorrhizal associations in Medicago truncatula.

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    Plants associate with beneficial arbuscular mycorrhizal fungi facilitating nutrient acquisition. Arbuscular mycorrhizal fungi produce chitooligosaccharides (COs) and lipo-chitooligosaccharides (LCOs), that promote symbiosis signalling with resultant oscillations in nuclear-associated calcium. The activation of symbiosis signalling must be balanced with activation of immunity signalling, which in fungal interactions is promoted by COs resulting from the chitinaceous fungal cell wall. Here we demonstrate that COs ranging from CO4-CO8 can induce symbiosis signalling in Medicago truncatula. CO perception is a function of the receptor-like kinases MtCERK1 and LYR4, that activate both immunity and symbiosis signalling. A combination of LCOs and COs act synergistically to enhance symbiosis signalling and suppress immunity signalling and receptors involved in both CO and LCO perception are necessary for mycorrhizal establishment. We conclude that LCOs, when present in a mix with COs, drive a symbiotic outcome and this mix of signals is essential for arbuscular mycorrhizal establishment

    Progress toward developing the TMT adaptive optical systems and their components

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    Atmospheric turbulence compensation via adaptive optics (AO) will be essential for achieving most objectives of the TMT science case. The performance requirements for the initial implementation of the observatory's facility AO system include diffraction-limited performance in the near IR with 50 per cent sky coverage at the galactic pole. This capability will be achieved via an order 60x60 multi-conjugate AO system (NFIRAOS) with two deformable mirrors optically conjugate to ranges of 0 and 12 km, six high-order wavefront sensors observing laser guide stars in the mesospheric sodium layer, and up to three low-order, IR, natural guide star wavefront sensors located within each client instrument. The associated laser guide star facility (LGSF) will consist of 3 50W class, solid state, sum frequency lasers, conventional beam transport optics, and a launch telescope located behind the TMT secondary mirror. In this paper, we report on the progress made in designing, modeling, and validating these systems and their components over the last two years. This includes work on the overall layout and detailed opto-mechanical designs of NFIRAOS and the LGSF; reliable wavefront sensing methods for use with elongated and time-varying sodium laser guide stars; developing and validating a robust tip/tilt control architecture and its components; computationally efficient algorithms for very high order wavefront control; detailed AO system modeling and performance optimization incorporating all of these effects; and a range of supporting lab/field tests and component prototyping activities at TMT partners. Further details may be found in the additional papers on each of the above topics

    Inhomogeneous superconductivity in organic conductors: role of disorder and magnetic field

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    Several experimental studies have shown the presence of spatially inhomogeneous phase coexistence of superconducting and non superconducting domains in low dimensional organic superconductors. The superconducting properties of these systems are found to be strongly dependent on the amount of disorder introduced in the sample regardless of its origin. The suppression of the superconducting transition temperature TcT_c shows clear discrepancy with the result expected from the Abrikosov-Gor'kov law giving the behavior of TcT_c with impurities. Based on the time dependent Ginzburg-Landau theory, we derive a model to account for the striking feature of TcT_c in organic superconductors for different types of disorder by considering the segregated texture of the system. We show that the calculated TcT_c quantitatively agrees with experiments. We also focus on the role of superconducting fluctuations on the upper critical fields Hc2H_{c2} of layered superconductors showing slab structure where superconducting domains are sandwiched by non-superconducting regions. We found that Hc2H_{c2} may be strongly enhanced by such fluctuations.Comment: to appear in Journal of Physics: Condensed Matte
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