Calls for transformative change and participatory modes of knowledge production demand researchers to assume new roles. This paper synthesizes the literature on knowledge co‐production and researcher ...roles to explore challenges for researchers involved in transdisciplinary environmental management projects. Our research methods combine a scoping review and reflections on personal experiences with three transdisciplinary projects. To conceptualize researcher roles in transdisciplinary knowledge co‐production, we distinguish between three spaces: knowledge, formal policy, and stakeholder. Knowledge co‐production requires collaboration between actors from different spaces and integration of diverse knowledge sources and types. Depending on whether researchers adopt knowledge‐oriented, change‐oriented or intermediating roles, they will experience different challenges. When researchers combine knowledge development with change‐oriented and/or intermediating roles, they encounter new challenges, such as, maintaining independence or objectivity. To assist researchers in transdisciplinary projects, we conclude with a checklist of four elements to reflect upon: orientation, norms and values, expectations and resources.
Many communities in the Midwestern United States obtain their drinking water from shallow alluvial wells that are vulnerable to contamination by NO3-N from the surrounding agricultural landscape. The ...objective of this research was to assess cropping systems with the potential to produce a reasonable return for farmers while simultaneously reducing the risk of NO3-N movement into these shallow aquifers. From 2009 to 2013 we conducted a field experiment in northwest Iowa in which we evaluated five cropping systems for residual (late fall) soil NO3-N content and profitability. Soil samples were taken annually from the top 30 cm of the soil profile in June and August, and from the top 180 cm in November (late fall). The November samples were divided into 30 cm increments for analysis. Average residual NO3-N content in the top 180 cm of the soil profile following the 2010 to 2013 cropping years was 134 kg ha-1 for continuous maize (Zea mays L.) with a cereal rye (Secale cereale L.) cover crop, 18 kg ha-1 for perennial grass, 60 kg ha-1 for a three year oat (Avena sativa L.)-alfalfa (Medicago sativa L.)-maize rotation, 85 kg ha-1 for a two year oat/red clover (Trifolium pratense L.)-maize rotation, and 90 kg ha-1 for a three year soybean (Glycine max (L.) Merr.)-winter wheat (Triticum aestivum L.)-maize rotation. However, residual NO3-N in the 90 to 180 cm increment of the soil profile was not significantly higher in the oat-alfalfa-maize cropping system than the perennial grass system. For 2010 to 2013, average profit ($ ha-1 yr-1) was 531 for continuous corn, 347 for soybean-winter wheat-maize, 264 for oat-alfalfa-maize, 140 for oat/red clover-maize, and -384 (loss) for perennial grass. Considering both residual soil NO3-N and profitability data, the oat-alfalfa-maize rotation performed the best in this setting. However, given current economic pressures widespread adoption is likely to require changes in public policy.
Many reports used terms such as "efficiency" or "sustainability" without providing a clear definition of what was meant in their specific reports. Because these words often have multiple meanings ...depending on context and the system components used and how they are measured, precise definitions are essential. Lack of tables often leads to repetitive written summaries of data, e.g. ratings of several indicators, farm by farm, becomes tedious and difficult to grasp, when a simple summary table of the same indicators across farms could be quickly viewed and understood. Since this is an Agroecosystems Analysis course that is based to great extent on biological and ecological dimensions of the farms, precise mechanistic and engineering-type diagrams showing simple cause and effect relationships may be less appropriate than those that illustrate interactions, complexity, and multiple factors that impact the sustainable workings of a farm.
Field experiments were conducted to determine the effect of a short-term spring-seeded smother plant on corn development and weed control. Yellow mustard was managed to provide interference durations ...of 2,4,6, or 8 wk, and maximum height of 10 or 20 cm. Three yellow mustard planting patterns and eight seeding rates were evaluated during 1989 and 1990 at St. Paul and Rosemount, MN. Yellow mustard seeded at 2120 seeds m−2 with an interference duration of 4 wk and a maximum height of 10 cm decreased corn yield 17% and reduced weed dry weight 4 wk after yellow mustard emergence an average of 66%. Yellow mustard with a 2-wk interference duration did not reduce weed dry weight. Yellow mustard seeded at 2120 seeds m−2 with a 6- or 8-wk life cycle and 10-cm height reduced weed dry weight at the end of the interference period an average of 82% but delayed corn silk emergence an average of 5.3 d and reduced average grain yield 19%. Increasing yellow mustard height from 10 to 20 cm delayed corn silk emergence and reduced grain yield but did not decrease weed dry weight. Yellow mustard with an interference duration of 4 wk and a maximum height of 10 cm, seeded over the corn row at 530 seeds m−2, reduced weed dry weight 4 wk after mustard emergence an average of 51%, and resulted in an average corn grain yield reduction of 4%, compared with corn grown in monoculture averaged over weedy and weed-free treatments. These results suggest that it may be possible to develop spring-seeded smother plants that reduce weed biomass up to 80% but have only a small impact on corn yield.
We describe the clinical course of an infant who presented with severe fetal anemia and fetal hydrops following congenital parvovirus B19 infection before 16 gestational weeks. The fetus was treated ...by cordocentesis and intrauterine transfusion at 18 weeks.
The infant demonstrated mild unilateral ventriculomegaly on antenatal magnetic resonance imaging, and polymicrogyria and heterotopia on postnatal magnetic resonance imaging.
This adds to the evidence in recent literature of central nervous system damage associated with congenital parvovirus B19 infection.
Using spring-seeded smother plants for weed control could reduce the environmental impact of corn (Zea mays L.) production. Research was conducted to determine whether currently available medic ...(Medicago spp.) cultivars are adapted for use as smother plants in corn. In field experiments in 1992 at Becker and Rosemount, MN, Medicago scutellata (L.) Mill. cv. Sava and Kelson were interseeded with corn at 0, 85, 260, or 775 seeds m-2. In 1993, Sava and Kelson, along with M. polymorpha L. cv. Santiago and M. lupulina L. cv. George, were interseeded with corn at 260 seeds m-2 and N fertilizer was applied at 0, 84 (56 at Rosemount), or 168 kg ha-1. Land equivalent ratios for corn and medic intercrops grown in 1992 were not 1, indicating that corn and medics competed strongly for resources. Medics seeded with corn at a rate high enough to consistently suppress weeds (260 seeds m-2) reduced weed dry weight 14 wk after corn emergence by 69% at Becker and by 41% at Rosemount compared with monoculture corn. The same seeding rate reduced corn grain yield in weed-free plots by 21% at Becker and 15% at Rosemount compared with mono-culture yields. In 1993, medic smother plants reduced weed dry weight more when grown in the 0 kg ha-1 N plots than in the 168 kg ha-1 N plots. Corn yield losses, however, were less severe in the 168 kg ha-1 N treatments than with 0 N. Annual medics managed as smother plants in corn effectively reduced weed biomass; however, additional research is needed to identify medic genotypes and smother plant management systems that reduce corn yields less than those we evaluated, and that provide more consistent weed suppression across environments
Three chapters comprise this project. The first chapter deals with the global picture of energy supply and demand, and concludes that other sources of energy must be developed in the next fifty ...years.
Chapter Two considers a number of alternate sources of energy;
and examines two sources in particular: (i) Hydrogen and its dependence on electricity, and (ii) Nuclear energy used to produce electricity. Certainly, Ontario has a very viable option to produce electricity by means of nuclear energy.
Home heating can, to some extent, be controlled by the individual, and Chapter Three discusses the operation of a heat pump and its feasibility as a heating device for homes in the Southern Ontario climate.
Thesis
Master of Science (Teaching)
This thesis describes experiments to study levels in deformed nuclei of the rare earth region of the chart of nuclides. Two types of experiments were done; γ-ray spectroscopy measurements following ...the (α,2n) reaction on various targets performed at the Notre Dame Nuclear Structure Laboratory to study the 178Hf and 154Gd nuclei and lifetime measurements using ultra-high precision crystal spectrometry and the GRID method performed at the Institut Laue Langevin for 178 Hf, 162Dy and 156Gd nuclei. These studies focused primarily on the excited Kπ = 0+ bands in these nuclei. The (α,2n) γ-ray spectroscopy experiments failed to populate significantly any excited Kπ = 0 + bands. However we were able to extend information on previously observed excitation bands via γ-γ coincidence measurements and DCO ratios. In 178Hf we observed a new excited band. The lifetime measurements were much more successful. The work reported in this thesis makes a significant contribution to the known information on lifetimes of K π = 0+ bands. Lifetimes of 12 levels from excited Kπ = 0+ were measured in three nuclei, 8 in 156Gd, 1 in 162Dy and 4 in 178Hf. The measured lifetimes along with relative γ-ray intensities were used to calculate absolute B(E2) values and provide evidence for the degree of collectivity observed in multiphonon vibrational excitations in several deformed nuclei.
New features of the level structures of {sup 107,108,109}Sn that have been observed following the beta decay of {sup 107,108,109}Sb are reported. The recoiling Sb nuclides were isolated using the ...Fragment Mass Analyzer at the ATLAS accelerator facility. Low-energy levels with strong configuration admixtures of the ({nu}g{sub 7/2}){sub 5/2}{sup 3} are identified in both {sup 107}Sn and {sup 109}Sn.
The avian H7N9 influenza outbreak in 2013 resulted from an unprecedented incidence of influenza transmission to humans from infected poultry. The majority of human H7N9 isolates contained a ...hemagglutinin (HA) mutation (Q226L) that has previously been associated with a switch in receptor specificity from avian-type (NeuAcα2-3Gal) to human-type (NeuAcα2-6Gal), as documented for the avian progenitors of the 1957 (H2N2) and 1968 (H3N2) human influenza pandemic viruses. While this raised concern that the H7N9 virus was adapting to humans, the mutation was not sufficient to switch the receptor specificity of H7N9, and has not resulted in sustained transmission in humans. To determine if the H7 HA was capable of acquiring human-type receptor specificity, we conducted mutation analyses. Remarkably, three amino acid mutations conferred a switch in specificity for human-type receptors that resembled the specificity of the 2009 human H1 pandemic virus, and promoted binding to human trachea epithelial cells.
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