3,059 research outputs found

    Development and the Yucatec Maya in Quintana Roo: some successes and failures

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    Maya agriculture is currently outperforming alternatives across the Yucatán Peninsula, while changing to incorporate new ideas that fit with its basic commitment to shifting agriculture based on maize as the staple and over 100 minor crops. Considerable research over the last 60 years has shown the reasons for agricultural resilience, which include thorough understanding of the Yucatán environment and use of a range of resources and techniques that allow fine-tuning in particular situations while remaining flexible overall. Development efforts have usually failed in this environment, which has shallow and fragile soils and suffers from frequent droughts, typhoons, and pest outbreaks. The predictor of development success is usually supply and demand: where there is a market, the Maya will work to develop supply capability; where there is no market, traditional subsistence methods are better than the introductions. Government or international help is, however, needed to help develop markets and to provide expert knowledge of how to mobilize for them and connect to them. When this has been done, some important successes have followed. A current problem is the international subsidy economy. Neoliberalism in the Maya context involves a reduction of government help to local and small-scale enterprises while large-scale multinational firms are given enormous direct and indirect subsidies by their home governments and by commodity-producing nations. The resulting unfair competition is a block on development. Actual free markets—in the sense of local grassroots enterprise being given something like a level playing field—could be an improvement. Key words: Maya; neoliberalism; Indigenous agricultural knowledge; access to market

    Environmentally stable reactive alloy powders and method of making same

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    Apparatus and method for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloyants needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment

    Method of making bonded or sintered permanent magnets

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    An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density

    Method of making permanent magnets

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    A method for making an isotropic permanent magnet comprises atomizing a melt of a rare earth-transition metal alloy (e.g., an Nd--Fe--B alloy enriched in Nd and B) under conditions to produce protectively coated, rapidly solidified, generally spherical alloy particles wherein a majority of the particles are produced/size classified within a given size fraction (e.g., 5 to 40 microns diameter) exhibiting optimum as-atomized magnetic properties and subjecting the particles to concurrent elevated temperature and elevated isotropic pressure for a time effective to yield a densified, magnetically isotropic magnet compact having enhanced magnetic properties and mechanical properties.</p

    Method of making bonded or sintered permanent magnets

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    An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density

    Paleolimnological Evidence of Terrestrial and Lacustrine Environmental Change in Response to European Settlement of the Red River Valley, Manitoba and North Dakota

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    Limnological and terrestrial changes in three floodplain lakes are correlated with settlement of the Red River valley in Manitoba and North Dakota. Distinctive pollen, diatom and thecamoebian assemblages provide proxy evidence of the ecological changes from pre- to post-settlement periods in Horseshoe Lake, Lake Louise and Salt Lake. In the pre-settlement period (Zone I), prior to ~1812, grass and Quercus pollen dominate and are indicative of a tall grass prairie-oak riparian forest ecosystem. Diatom and thecamoebian assemblages suggest oligo- to mesotrophic limnological conditions, and more brackish water than presently occurs in Horseshoe Lake. The onset of the post-settlement period (Zone II) corresponds to distinctive terrestrial and limnological changes. A sharp decline in Quercus at the base of this zone correlates with documented regional riparian deforestation, whereas the increase in the weed taxa Salsola, Brassica, Rumex and Ambrosia is associated with the introduction of European agricultural practices and cereal grasses. Diatom and thecamoebian assemblages indicate progressive floodplain lake eutrophication, as well as increased salinity in Salt Lake. Salt Lake is the most brackish lake and supports the brackish-water foraminifera Trochammina macrescens cf. polystoma. Increased erosion and run off in the watershed has caused a more than twofold increase in lake basin sedimentation between the pre-settlement and post-settlement periods.Cette étude établit une corrélation entre les changements limnologiques et terrestres dans la plaine d’inondation de trois lacs et le peuplement de la vallée de la rivière Rouge au Manitoba et dans le Dakota du Nord. Divers assemblages polliniques, de diatomées et de thécamoébiens mettent en évidence de façon indirecte des changements écologiques entre les périodes pré- et post-peuplement aux alentours des lacs Horseshoe, Louise et Salt. Dans la période antérieure au peuplement (Zone I), soit avant 1812, la domination de la signature pollinique des graminées et du chêne indique un écosystème forestier riverain composé de graminées de haute taille et de chênes. Quant aux assemblages de diatomées et de thécamoébiens, ils permettent de penser à des conditions limnologiques d’oligo à mésotrophiques et des eaux plus saumâtres à cette période qu’actuellement dans le lac Horseshoe. La période post-peuplement (Zone II) correspond à des changements terrestres et limnologiques spécifiques. Le déclin marqué du chêne à la base de cette zone correspond en effet à la déforestation des rives de cette région, telle qu’attestée dans les documents, tandis que les taxons Salsola, Brassica, Rumex et Ambrosia correspondent à l’instauration de pratiques agricoles européennes et la culture des céréales. Les assemblages de diatomées et de thécamoébiens indiquent aussi une eutrophisation progressive de la plaine inondable de même que l’augmentation de la salinité du lac Salt, ce dernier étant le plus salé des trois lacs. Il accueille des foraminifères d’eaux saumâtres du genre Trochammina macrescens cf. polystoma. L’accroissement de l’érosion et du ruissellement dans le bassin-versant a quadruplé la sédimentation entre les périodes pré- et post-peuplement

    Trypanosome diversity in wildlife species from the Serengeti and Luangwa Valley ecosystems

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    &lt;p&gt;Background: The importance of wildlife as reservoirs of African trypanosomes pathogenic to man and livestock is well recognised. While new species of trypanosomes and their variants have been identified in tsetse populations, our knowledge of trypanosome species that are circulating in wildlife populations and their genetic diversity is limited.&lt;/p&gt; &lt;p&gt;Methodology/Principal Findings: Molecular phylogenetic methods were used to examine the genetic diversity and species composition of trypanosomes circulating in wildlife from two ecosystems that exhibit high host species diversity: the Serengeti in Tanzania and the Luangwa Valley in Zambia. Phylogenetic relationships were assessed by alignment of partial 18S, 5.8S and 28S trypanosomal nuclear ribosomal DNA array sequences within the Trypanosomatidae and using ITS1, 5.8S and ITS2 for more detailed analysis of the T. vivax clade. In addition to Trypanosoma brucei, T. congolense, T. simiae, T. simiae (Tsavo), T. godfreyi and T. theileri, three variants of T. vivax were identified from three different wildlife species within one ecosystem, including sequences from trypanosomes from a giraffe and a waterbuck that differed from all published sequences and from each other, and did not amplify with conventional primers for T. vivax.&lt;/p&gt; &lt;p&gt;Conclusions/Significance: Wildlife carries a wide range of trypanosome species. The failure of the diverse T. vivax in this study to amplify with conventional primers suggests that T. vivax may have been under-diagnosed in Tanzania. Since conventional species-specific primers may not amplify all trypanosomes of interest, the use of ITS PCR primers followed by sequencing is a valuable approach to investigate diversity of trypanosome infections in wildlife; amplification of sequences outside the T. brucei clade raises concerns regarding ITS primer specificity for wildlife samples if sequence confirmation is not also undertaken.&lt;/p&gt

    Managing Opportunities and Challenges of Co-Authorship

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    Research with the largest impact on practice and science is often conducted by teams with diverse substantive, clinical, and methodological expertise. Team and interdisciplinary research has created authorship groups with varied expertise and expectations. Co-authorship among team members presents many opportunities and challenges. Intentional planning, clear expectations, sensitivity to differing disciplinary perspectives, attention to power differentials, effective communication, timelines, attention to published guidelines, and documentation of progress will contribute to successful co-authorship. Both novice and seasoned authors will find the strategies identified by the Western Journal of Nursing Research Editorial Board useful for building positive co-authorship experiences

    Science Librarian Internship as a Way to Get Started in EScience

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    The Science Bibliographers’ Group of Boston College first proposed the creation of a paid science librarian internship position in Summer 2008. Since then, the three interns hired over time have gained exposure to a wide variety of activities undertaken by science librarians, and, at the same time, have significantly furthered the Library’s understanding of, and participation in, eScience. In addition to important contributions in reference and collection development activities, intern contributions have included an environmental scan/best practices review of relevant eScience initiatives, design of an eScience brochure, development of a faculty survey to gauge interest in library data management, and a capstone presentation on eScience for all library staff. Building upon that work, the Science Bibliographers’ Group developed a Vision Statement and Action Plans for eScience. Our current intern is working closely with members of the group on the creation of a LibGuide focused on data management and, concurrently, develop-ment of curricular materials for data management workshops to be implemented during the 2011/12 academic year. Ideally, these increased efforts in eScience-related work will result in an enhanced profile for eScience on the Boston College campus, and, ultimately, creation of a new, eScience-focused position in the Boston College Libraries. An internship program can provide current knowledge and skills to educate and support a university research library through the early learning stage of developing an eSciences program, while simultaneously providing a valuable hands-on learning experience for a potential science librarian
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