21 research outputs found

    Field-Scale Electrical Conductivity Mapping for Delineating Soil Condition

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    Traditional sampling methods are inadequate for assessing the interrelated physical, chemical, and biological soil properties responsible for variations in agronomic yield and ecological potentials across a landscape. Recent advances in computers, global positioning systems, and large-scale sensors offer new opportunities for mapping heterogeneous patterns in soil condition. We evaluated field-scale apparent electrical conductivity (ECa) mapping for delineating soil properties correlated with productivity and ecological properties. A contiguous section of farmland (250 ha), managed as eight fields in a no-till winter wheat (Triticum aestivum L.)–corn (Zea mays L.)–millet (Panicum miliaceum L.)–fallow rotation, was ECa mapped (≈0- to 30-cm depth). A geo-referenced soil-sampling scheme separated each field into four ECa classes that were sampled (0- to 7.5- and 7.5- to 30-cm depths) in triplicate. Soil physical parameters (bulk density, moisture content, and percentage clay), chemical parameters (total and particulate organic matter [POM], total C and N, extract- able P, laboratory-measured electrical conductivity [EC1:1], and pH), biological parameters (microbial biomass C [MBC] and N [MBN], and potentially mineralizable N), and surface residue mass were significantly different among ECa classes (P ≤ 0.06) at one or both depths (0–7.5 and 0–30 cm). Bulk density, percentage clay, EC1:1, and pH were positively correlated with ECa; all other soil parameters and surface residue mass were negatively correlated. Field-scale ECa classification delimits distinct zones of soil condition, providing an effective basis for soil sampling. Potential uses include assessing temporal impacts of management on soil condition and managing spatial variation in soil-condition and yield-potential through precision agriculture and site-specific management

    Preparing surgery house officers for their teaching role

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    The medical education literature was reviewed in four categories: (1) general studies of house officer teaching, (2) perceptions of the house officer's teaching role, (3) assessing and improving resident teaching skills, and (4) the teaching role of surgery residents. An agenda for research and development related to surgery resident teaching skills was proposed based on four research questions: (1) What types of teaching skills are most appropriate for surgery residents? (2) How do faculty and student expectations of resident teaching influence surgery resident teaching? (3) What type of intervention is most successful in improving surgery resident teaching skills? (4) What are other outcomes of improved surgery resident teaching besides resident and learner satisfaction? This important teaching role should be more formally and widely acknowledged by surgery faculty, and appropriate teaching skill improvement activities should be provided for all surgery house officers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29405/1/0000478.pd
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