839 research outputs found

    Response of \u3cem\u3eArachis pintoi\u3c/em\u3e to Grazing Intensity When Associated with Different Grasses

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    Lack of legume persistence is one of the main reasons for poor utilisation of grass-legume pastures in the tropics. Arachis pintoi (forage peanut) is currently the most promising forage legume for the humid tropics, mainly because of good persistence under grazing (Grof, 1985; Fisher & Cruz, 1995). The objective of this work was to show how two accessions of A. pintoi react to increasing herbage allowance levels when associated with two different grasses

    Restoration of tropical seagrass beds using wild bird fertilization and sediment regrading

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    Shallow water seagrass meadows are frequently damaged by recreational and commercial vessels. Severe injury occurs where propeller scarring, hull groundings and mooring anchors uproot entire plants, excavate sediments, and modify the biophysical properties of the substrate. In climax tropical seagrass communities dominated by Thalassia testudinum (turtlegrass), natural recovery in these disturbances can take several years to decades, and in some environmental conditions may not occur at all. During the recovery period, important ecological services provided by seagrasses are absent or substantially diminished and injured meadows can degrade further in response to natural disturbances, e.g. strong currents and severe storms. To determine if we could accelerate rehabilitation and prevent further degradation of injured turtlegrass meadows, we evaluated a restoration method called “modified compressed succession” using the fast-growing, opportunistic species Halodule wrightii to temporarily substitute ecological services for the slower-growing, climax species T. testudinum. In three experiments we showed statistically significant increases in density and coverage rates of H. wrightii transplants fertilized by wild bird feces as compared to unfertilized treatments. In one experiment, we further demonstrated that regrading excavated injuries with sediment-filled biodegradable tubes in combination with wild bird fertilization and H. wrightii transplants also accelerated seagrass recovery. Specific recommendations are presented for the best practical application of this restoration method in the calcium carbonate-based sediments of south Florida and the wider Caribbean region

    Enabling remote design and troubleshooting experiments using the ilab shared architecture

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    12th Biennial International Conference on Engineering, Construction, and Operations in Challenging Environments; and Fourth NASA/ARO/ASCE Workshop on Granular Materials in Lunar and Martian Exploration Honolulu, Hawaii, United States March 14-17, 2010The MIT iLab Project is dedicated to the goal of increasing laboratory experimentation opportunities for engineering students worldwide. Since its inception in 1998, the project has furthered this goal through the development of individual remote laboratories, or iLabs, as well as a distributed software infrastructure designed to streamline the implementation and sharing of remote laboratories. iLabs are designed to complement traditional, hands-on laboratories by providing practical educational experiences where they would not otherwise be available. Such remote labs, developed and hosted by MIT and other institutions within the iLab Consortium, have been successfully used by instructors at schools across the educational spectrum and around the world. While certainly valuable, many of the original experiments available through the iLab platform provide a limited experience in that they are observational in nature. They only provide students the ability to study the behavior of a pre-defined system under test. Such labs have proven to be valuable additions to engineering curricula, but do not have the flexibility that is inherent in a traditional laboratory experience. To address this, the MIT iLab Project has begun focusing on the development of iLabs that provide students with the ability to design or troubleshoot experimental systems. Through two particular remote labs, focusing on electronic control system analysis and basic electronics test and measurement respectively, the project is designing remote labs that provide a more flexible learning experience for students and are more attractive to instructors in a broad set of disciplines.National Science Foundation (U.S.) (award 0702735)Singapore-MIT Alliance for Research and Technology CenterMicrosoft CorporationCarnegie Corporation of New YorkMaricopa County Community College District. Maricopa Advanced Technology Education Cente

    Energy democracy: A digital future?

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    This is the final version. Available from Elsevier via the DOI in this record. Academic exploration of energy democracy has produced a rich theorization of its foundations that exhibits significant pluralism in response to different geographic, social, ideological and technical contexts. This paper develops the literature by considering how sociotechnical transitions associated with energy system digitalization may affect the theory and praxis of energy democracy. Our analysis draws on three dimensions of energy democracy: popular sovereignty, participatory governance, and civic ownership. Digitalization is shown to both present challenges and new avenues for the exercise and study of energy democracy. Firstly, digitalization simultaneously enables and constrains the exercise of popular sovereignty by diversifying energy citizen roles and complicating accountability. Secondly, digitalization creates new dimensions of risk around skills, knowledge and resource access, which can exclude citizens from participatory governance. Thirdly, digitalization challenges common conceptions of civic ownership by introducing new material-software dependencies and re-defining the assets that underpin the energy system. Finally, digitalization fundamentally changes the nature of decision-making, potentially undermining current understandings of the concept and its democratic function. Further exploration of ‘digital energy democracy’ would hold value for research and practice in the sector.Economic and Social Research Council (ESRC

    Washington Legislation—1941

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    In undertaking to survey the work of the 1941 legislature the aim has not been to attain complete coverage. Space limitations and the time factor have dictated that only certain phases be considered and that brevity rather than complete analysis be the guide. In selecting topics for discussion the aim has been to give attention to those statutes which are likely to be of greatest concern to practicing lawyers. At the outset this meant that virtually all of the largest group of statutes, those dealing with the powers of governmental units, be eliminated. Of the remaining statutes all could not be discussed, or even mentioned, and while the selection has been arbitrary the attempt has been to focus upon those which appear to be of the most general interest. Special regard has been had for statutes affecting judicial procedure, to those of a regulatory character and to social legislation. Because of space and time limitations consideration of some material has necessarily been postponed until the next issue of the Review. Among the statutes which will be discussed in the later issue are those dealing with agriculture, banking, small loans, taxation, trusts, and workmen\u27s compensation. The survey has been a cooperative enterprise by the members of the law faculty of the University of Washington, with the valuable help of members of the student editorial board of the Review. In particular, Dean Falknor was assisted by Mr. Arthur Quigley. Mr. Robert Buck aided Professor O\u27Bryan. Professor Shattuck had the assistance of Mr. Herbert Droker, and Professor Sholley, of Mr. Snyder Jed King and Mr. Bayard Crutcher

    Washington Legislation—1941 (Continued)

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    The survey of selected important enactments of the Twenty-Seventh Legislature of the State of Washington, first installment of which appeared in the April issue of the REVww, is continued and concluded in this issue

    FAST CARS: Engineering a Laser Spectroscopic Technique for Rapid Identification of Bacterial Spores

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    Airborne contaminants, e.g., bacterial spores, are usually analyzed by time consuming microscopic, chemical and biological assays. Current research into real time laser spectroscopic detectors of such contaminants is based on e.g. resonant Raman spectroscopy. The present approach derives from recent experiments in which atoms and molecules are prepared by one (or more) coherent laser(s) and probed by another set of lasers. The connection with previous studies based on "Coherent Anti-Stokes Raman Spectroscopy" (CARS) is to be noted. However generating and utilizing maximally coherent oscillation in macromolecules having an enormous number of degrees of freedom is much more challenging. This extension of the CARS technique is called FAST CARS (Femtosecond Adaptive Spectroscopic Techniques for Coherent Anti-Stokes Raman Spectroscopy), and the present paper proposes and analyses ways in which it could be used to rapidly identify pre-selected molecules in real time.Comment: 43 pages, 21 figures; replacement with references added. Submitted to the Proceedings of National Academy of Science

    A global disorder of imprinting in the human female germ line

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    Imprinted genes are expressed differently depending on whether they are carried by a chromosome of maternal or paternal origin. Correct imprinting is established by germline-specific modifications; failure of this process underlies several inherited human syndromes. All these imprinting control defects are cis-acting, disrupting establishment or maintenance of allele-specific epigenetic modifications across one contiguous segment of the genome. In contrast, we report here an inherited global imprinting defect. This recessive maternal-effect mutation disrupts the specification of imprints at multiple, non-contiguous loci, with the result that genes normally carrying a maternal methylation imprint assume a paternal epigenetic pattern on the maternal allele. The resulting conception is phenotypically indistinguishable from an androgenetic complete hydatidiform mole, in which abnormal extra-embryonic tissue proliferates while development of the embryo is absent or nearly so. This disorder offers a genetic route to the identification of trans-acting oocyte factors that mediate maternal imprint establishment
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