12,373 research outputs found

    Interactive Planetary Visualization and Analysis with NASA's Solar System Treks Portals

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    NASA's Solar System Trek online portals provide web-based suites of interactive visualization and analysis tools enabling mission planners, planetary scientists, students, and the general public to explore planetary surfaces as seen through the eyes of many different instruments aboard a wide range of spacecraft. The portals present a vast collection of mapped data products from past and current missions for a growing number of planetary bodies. As web-based toolsets, the portals do not require users to purchase or install any software beyond current web browsers. The interactive and immersive capabilities of these portals are being used for site selection and analysis by NASA and a number of its international partners, supporting upcoming missions. They are also being used by formal and informal educators, students from elementary through university levels of study, and members of the public who are engaged in the excitement of solar system exploration. This presentation will provide an overview of the Solar System Treks and highlight many of the exciting new additions to the project implemented this past year

    Titan Trek and IcyMoons Trek: Two New Online NASA Visualization and Analysis Portals for Saturn's Moons

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    Saturns moons are the focus of two new online visualization and analysis tools produced by NASA. The Solar System Treks family of online portals provides a suite of interactive visualization and analysis tools. These enable mission planners, lunar scientists, engineers, students, and the general public to access mapped data products from past and current missions for a growing number of planetary bodies. They integrate data from a variety of instruments aboard a number of missions. This presentation will introduce two new portals in the Solar System Trek suite. Titan Trek highlights Saturns largest moon, and IcyMoons Trek features a number of Saturns other moons as studied by the Cassini mission

    Field Induced Magnetic Ordering and Single-ion Anisotropy in the Quasi-1D Haldane Chain Compound SrNi2V2O8: A Single Crystal investigation

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    Field-induced magnetic ordering in the Haldane chain compound SrNi2_{2}V2_{2}O8_{8} and effect of anisotropy have been investigated using single crystals. Static susceptibility, inelastic neutron scattering, high-field magnetization, and low temperature heat-capacity studies confirm a non-magnetic spin-singlet ground state and a gap between the singlet ground state and triplet excited states. The intra-chain exchange interaction is estimated to be J∼8.9±J \sim 8.9{\pm}0.1 meV. Splitting of the dispersions into two modes with minimum energies 1.57 and 2.58 meV confirms the existence of single-ion anisotropy D(Sz)2D(S^z){^2}. The value of {\it D} is estimated to be −0.51±0.01-0.51{\pm}0.01 meV and the easy axis is found to be along the crystallographic {\it c}-axis. Field-induced magnetic ordering has been found with two critical fields [μ0Hc⊥c=12.0±\mu_0H_c^{\perp c} = 12.0{\pm}0.2 T and μ0Hc∥c=20.8±\mu_0H_c^{\parallel c} = 20.8{\pm}0.5 T at 4.2 K]. Field-induced three-dimensional magnetic ordering above the critical fields is evident from the heat-capacity, susceptibility, and high-field magnetization study. The Phase diagram in the {\it H-T} plane has been obtained from the high-field magnetization. The observed results are discussed in the light of theoretical predictions as well as earlier experimental reports on Haldane chain compounds

    Mars Trek: An Interactive Web Portal for Current and Future Missions to Mars

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    NASA's Mars Trek (https://marstrek.jpl.nasa.gov) provides a web-based Portal and a suite of interactive visualization and analysis tools to enable mission planners, lunar scientists, and engineers to access mapped data products from past and current missions to Mars. During the past year, the capabilities and data served by Mars Trek have been significantly expanded beyond its original design as a public outreach tool. At the request of NASA's Science Mission Directorate and Human Exploration Operations Mission Directorate, Mars Trek's technology and capabilities are now being extended to support site selection and analysis activities for the first human missions to Mars

    Towards practice-based studies of HRM: an actor-network and communities of practice informed approach

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    HRM may have become co-terminus with the new managerialism in the rhetorical orthodoxies of the HRM textbooks and other platforms for its professional claims. However, we have detailed case-study data showing that HR practices can be much more complicated, nuanced and indeed resistive toward management within organizational settings. Our study is based on ethnographic research, informed by actor-network theory and community of practice theory conducted by one of the authors over an 18-month period. Using actor-network theory in a descriptive and critical way, we analyse practices of managerial resistance, enrolment and counter-enrolment through which an unofficial network of managers used a formal HRM practice to successfully counteract the official strategy of the firm, which was to close parts of a production site. As a consequence, this network of middle managers effectively changed top management strategy and did so through official HRM practices, coupled with other actor-network building processes, arguably for the ultimate benefit of the organization, though against the initial views of the top management. The research reported here, may be characterized as a situated study of HRM-in-practice and we draw conclusions which problematize the concept of HRM in contemporary management literature

    Understanding the introduction and use of a mobile device-supported health information system in Nigeria

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    Copyright @ 2014 The Authors.This paper presents an in-depth analysis of efforts to introduce a mobile health information system in Nigeria as part of a development initiative aimed at improving maternal and child health. Specifically, it examines the use of mobile devices to facilitate maternal health information accessibility and exchange among health practitioners in order to reducing maternal, newborn and child mortality. Further, it also looks at the challenges raised while introducing mobile devices into work practices in the healthcare sector. The study adopts a case study approach, relying on semi-structured interviews and document analysis as its main methods for collecting data. The specific case examined is a mobile phone-based information system introduced to support a national government effort in Nigeria, known as the midwives service scheme. The findings of this study show that this integrated approach of using mobile phones to support (health) information systems has vast potential; for instance increasing the timeliness of (health) data available to stakeholders for monitoring and planning purposes. However, we also find that over time, attaining the potential of development efforts such as this remains difficult as initiatives involving the use of mobile devices is not just about getting the technical aspect right. It is equally dependent on deep seated social-cultural influences such as poor political and financial commitment. These two mutually reinforcing influences have been identified in this study as significant impediments to efforts of this kind. Therefore, this paper argues for, first a strong political commitment across all levels of government whereby their words are backed with action. Second it is important that the government maintains financial integrity by releasing the funds budgeted to support the smooth running of these efforts, for such initiatives to thrive and ultimately contribute to development

    Climatic versus biotic constraints on carbon and water fluxes in seasonally drought-affected ponderosa pine ecosystems

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    We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS (50%), and intermediate at the YS (<20%). In the young, developing stand, interannual variation in leaf area has larger effects on fluxes than climate, although leaf area is a function of climate in that climate can interact with age-related shifts in carbon allocation and affect whole-tree hydraulic conductance. Older forests, with well-established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE

    STEM Engagement with NASA's Solar System Treks Portals for Lunar and Planetary Mapping and Modeling

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    This presentation will provide an overview of the uses and capabilities of NASA's Solar System Treks family of online mapping and modeling portals. While also designed to support mission planning and scientific research, this presentation will focus on the Science, Technology, Engineering, and Math (STEM) engagement and public outreach capabilities of these web based suites of data visualization and analysis tools

    Coexistence Curve Singularities at Critical End Points

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    We report an extensive Monte Carlo study of critical end point behaviour in a symmetrical binary fluid mixture. On the basis of general scaling arguments, singular behaviour is predicted in the diameter of the liquid-gas coexistence curve as the critical end point is approached. The simulation results show clear evidence for this singularity, as well as confirming a previously predicted singularity in the coexistence chemical potential. Both singularities should be detectable experimentally.Comment: 9 pages Revtex, 3 figures. To appear in Phys. Rev. Let
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