213 research outputs found
Fumonisins in Corn
This NebFact discusses the causes and occurrences of fumonisin in corn
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Reply to Comments on ‘Production of polar cap electron density patches by transient magnetopause reconnections’
Temporal and Spatial Distribution of Finfish Bycatch in the U.S. Atlantic Bottom Longline Shark Fishery
Bycatch in U.S. fisheries has become an increasingly important issue to both fisheries managers and the public, owing to the wide range of marine resources that can be involved. From 2002 to 2006, the Commercial Shark Fishery Observer Program (CSFOP) and the Shark Bottom Longline Observer Program (SBLOP) collected data on catch and bycatch caught on randomly selected vessels of the U.S. Atlantic shark bottom longline fishery. Three subregions (eastern Gulf of Mexico, South Atlantic, Mid-Atlantic
Bight), five years (2002–06), four hook types (small, medium, large, and other), seven depth ranges (300 m), and eight broad taxonomic categories (e.g.
Selachimorpha, Batoidea, Serranidae, etc.) were used in the analyses. Results indicated that the majority of bycatch (number) was caught in the eastern Gulf of Mexico and that the Selachimorpha taxon category made up over 90% of the total bycatch. The factors year followed by depth were the
most common significant factors affecting bycatch
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Implications of the altitude of transient 630-nm dayside auroral emissions
The altitude from which transient 630-nm (“red line”) light is emitted in transient dayside auroral breakup events is discussed. Theoretically, the emissions should normally originate from approximately 250 to 550 km. Because the luminosity in dayside breakup events moves in a way that is consistent with newly opened field lines, they have been interpreted as the ionospheric signatures of transient reconnection at the dayside magnetopause. For this model the importance of these events for convection can be assessed from the rate of change of their area. The area derived from analysis of images from an all-sky camera and meridian scans from a photometer, however, depends on the square of the assumed emission altitude. From field line mapping, it is shown for both a westward and an eastward moving event, that the main 557.7-nm emission comes from the edge of the 630 nm transient, where a flux transfer event model would place the upward field-aligned current (on the poleward and equatorward edge, respectively). The observing geometry for the two cases presented is such that this is true, irrespective of the 630-nm emission altitude. From comparisons with the European incoherent scatter radar data for the westward (interplanetary magnetic field By > 0) event on January 12, 1988, the 630-nm emission appears to emanate from an altitude of 250 km, and to be accompanied by some 557.7-nm “green-line” emission. However, for a large, eastward moving event observed on January 9, 1989, there is evidence that the emission altitude is considerably greater and, in this case, the only 557.7-nm emission is that on the equatorward edge of the event, consistent with a higher altitude 630-nm excitation source. Assuming an emission altitude of 250 km for this event yields a reconnection voltage of >50 kV during the reconnection burst but a contribution to the convection voltage of >15 kV. However, from the motion of the event we infer that the luminosity peaks at an altitude in the range of 400 and 500 km, and for the top of this range the reconnection and average convection voltages would be increased to >200 kV and >60 kV, respectively. (These are all minimum estimates because the event extends in longitude beyond the field-of-view of the camera). Hence the higher-emission altitude has a highly significant implication, namely that the reconnection bursts which cause the dayside breakup events could explain most of the voltage placed across the magnetosphere and polar cap by the solar wind flow. Analysis of the plasma density and temperatures during the event on January 9, 1989, predicts the required thermal excitation of significant 630-nm intensities at altitudes of 400-500 km
Processing gapping: Parallelism and grammatical constraints
This study aims to test two hypotheses about the online processing of Gapping: whether the parser inserts an ellipsis site in an incremental fashion in certain coordinated structures (the Incremental Ellipsis Hypothesis), or whether ellipsis is a late and dispreferred option (the Ellipsis as a Last Resort Hypothesis). We employ two offline acceptability rating experiments and a sentence fragment completion experiment to investigate to what extent the distribution of Gapping is controlled by grammatical and extra-grammatical constraints. Furthermore, an eye-tracking while reading experiment demonstrated that the parser inserts an ellipsis site incrementally but only when grammatical and extra- grammatical constraints allow for the insertion of the ellipsis site. This study shows that incremental building of the Gapping structure follows from the parser’s general preference to keep the structure of the two conjuncts maximally parallel in a coordination structure as well as from grammatical restrictions on the distribution of Gapping such as the Coordination Constraint
ALTERNATE LINER DEMONSTRATION (ALD) FOR CCR SURFACE IMPOUNDMENT
Alternate Liner Demonstration (ALD) for CCR Surface Impoundment Authors Mr. John Seymour - United States - Geosyntec Consultants, Inc. Mr. Mike Coram - United States - Geosyntec Consultants, Inc. Dr. Clinton Carlson - United States - Geosyntec Consultants, Inc. Mr. Isaiah Vaught - United States - Geosyntec Consultants, Inc. Mr. Jesse Varsho - United States - Geosyntec Consultants, Inc. Abstract An alternate liner demonstration was prepared for a large (300+ acres) CCR surface impoundment (SI) in accordance with the Coal Combustion Residuals (CCR) Rule [40CFR257.71(d)]. The SI had a natural glacial clay bottom liner and compacted clay side liner (containment berm). This presentation focuses on the field and laboratory testing and groundwater modeling completed as a part of the ALD Package [40CFR257.71(d)(1)(ii)] to demonstrate “…no reasonable probability that the continued operation of the surface impoundment will result in adverse effects to human health or the environment”. To meet the rule requirements, existing data was supplemented with the following new work was competed: 95 cone penetration test probes to depths of 75 ft, with 70 pore pressure dissipation tests confirmed by 9 continuously-sampled sonic soil borings drilled down 75 ft to bedrock, 5 CCR pore water sample analyses from in the SI, 24 undisturbed samples of the soil liner materials in the containment berm and underlying soils down to bedrock, located approximately 25 ft below the bottom liner. Hydraulic conductivity compatibility testing using pore water (permeant) was conducted on 16 samples for 21 months with no degradation of hydraulic conductivity. Groundwater flow modeling was conducted using the data from the field and laboratory testing that demonstrated migration of constituents in pore water would not exceed the groundwater quality standards when they reached the uppermost aquifer, meeting the CCR Rule criterion
Precision Farming Protocols. Part 2. Comparison of Sampling Approaches for Precision Phosphorus Management
Research is needed to compare the different techniques for developing site‐specific phosphorus (P) recommendations on a field‐wide basis. The objective of this study was to determine the impact different techniques for developing site‐specific P recommendation maps on yield and profitability. Enterprise analysis combined with a crop simulation model and detailed field characterization was used to estimate the value of spatial P information in a system where N was not limiting. The systems evaluated were continuous corn (Zea mays) and corn and soybean (Gfycine max) rotations where sampling and fertilizer applications were applied annually and semi‐annually, respectively. The sampling techniques tested were: (i) an unfertilized P control; (ii) whole field; (iii) whole field plus historic information (feedlot); (iv) landscape positions; (v) soil type; (vi) soil type plus historic information (feedlot); and (vii) 90‐m grid sampling. The finding of this study were based on soil samples collected from a 30 by 30‐m grid. The value of the spatial information was dependent on the crops response to P, the accuracy of the different sampling techniques, crop rotation, and the length of time between sampling dates. All of the sampling techniques produced different application maps. The recommendation map based on a single composite sample under fertilized 56.5% of the field. Increasing the sampling density reduced the percentage of under‐fertilized land. If corn had a low P response, then simulation/enterprise analysis indicated that applying P did not increased profits. For all scenarios tested: (i) the soil type + historic sampling approach had higher potential profits than the 90 m grid sampling approach; and (ii) there was no economic benefit associated with the 90‐m grid sampling. However, if research shows that amortization of sampling and analysis costs over 3 or 4 years is appropriate, then it may be possible to derive economic benefit from a 90‐m grid sampling. For a corn/soybean rotation, where fertilizer was applied when corn was planted and N and P was not applied to soybeans, enterprise/ simulation analysis (2.8 Mg ha‐1 soybean yield goal and a moderate P model) showed that soil + historic sampling approach increased profitability $3.74 ha‐1 when compared to the uniform P treatment
Effects of Supplementing High Levels of Cu, Co, Mn, and Zn After Calving on Productivity of Two-Year-Old Cows
When cow management, health and nutrition are adequate. supplementation of trace minerals at high levels is not beneficial and may in fact be detrimental to reproductive performance
Use of high intensity reflective sheeting in lieu of external lighting of overhead roadway signs
Overhead guide sign lighting has been used by many agencies to improve visibility. However, the availability of newer and more efficient retroreflective materials has created a new challenge for state transportation agencies going through sign sheeting upgrade programs and considering the need for using sign lighting, as there is no existing answer regarding whether upgraded sign sheeting itself can meet drivers’ nighttime visibility demands without external sign lighting. The purpose of the paper is to investigate whether high intensity reflective sheeting can be used to replace overhead guide sign lighting. The conclusion of the study provided a guidance for agencies to adopt their current sign lighting policy. A luminance computation model is used in the paper to calculate overhead guide sign legend luminance under various situations, including different sign lighting technologies, different geometrics and overhead guide sign locations, and different amounts of sign dirt and sign aging. By comparing the calculated luminance of a specific overhead guide sign at a specific situation with the legibility luminance levels required by older drivers, sign lighting needs are assessed. In addition, a life-cycle cost spreadsheet is developed and used to calculate the cost of replacing the current sign sheeting with high reflective sheeting and the cost of installing/upgrading sign lighting. Eventually, the most cost effective approach to maintain overhead guide luminance is discussed.
First published online 16 January 201
Defining Yield Goals and Management Zones to Minimize Yield and Nitrogen and Phosphorus Fertilizer Recommendation Errors
Three general approaches (minimize soil nutrient variability, yield, and fertilizer recommendation errors) have been used to assess nutrient management zone boundaries. The objective of this study was to determine the influence of different approaches to define management zones and yield goals on minimizing yield variability and fertilizer recommendation errors. This study used soil nutrient and yield information collected from two east-central South Dakota fields between 1995 and 2000. The crop rotation was corn (Zea mays L.) followed by soybean [Glycine max (L.) Merr.]. The four management zone delineation approaches tested were to: (i) sample areas impacted by old homesteads separately from the rest of the field; (ii) separate the field into grid cells; (iii) use geographic information systems or cluster analysis of apparent electrical conductivity, elevation, aspect, and connectedness to identify zones; and (iv) use the Order 1 soil survey. South Dakota fertilizer N and P recommendations were used to calculate fertilizer requirements. This study showed that management zones based on a 4-ha grid cell and an Order 1 soil survey had lower within-zone yield variability than the other methods tested. The best approaches for minimizing recommendation errors were nutrient specific. Nitrogen and P recommendations were improved using multiple years of yield monitor data to develop landscape-specific yield goals, sampling old homesteads separately from the rest of the field, and grid cell soil sampling to fine-tune N and P recommendations
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