533 research outputs found

    A Subsurface Irrigated, Controlled Traffic, No- Tillage System

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    A subsurface trickle irrigation system was protected from damage for 21 months through use of a controlled traffic pattern and no-till agriculture. During this period, seven successive vegetable crops were grown without disturbing the irrigation system. Subsequent inspection of the system indicated that this combination of techniques would enable it to operate for periods greater than two years at acceptable levels without replacement. The experiment was conducted on two soils, a light volcanic ash soil and a heavy alluvial soil with less favorable physical properties, to assess the general applicability of the results. Natural soil compaction over a 16-month period showed no significant effect on yields. Severe compaction imposed by tractor traffic resulted in a decrease in lettuce root weight of one-half, yet it had no significant effect on crop yield. Emitter plugging increased from an average of 23% in the non-compacted plots to 36% in the compacted plots with similar results in both shallow and deep (13 and 28 cm) lateral line placement. Plugging did not significantly reduce crop yields. Water movement along the trickle line and the intermittent nature of plugging may have reduced the influence of plugging on lettuce yields. The results from these experiments indicate that for shallow-rooted, short duration, transplanted vegetable crops, such as lettuce and cabbage, acceptable yields can be obtained without extensive tillage if water and nutrients are adequately supplied. Phosphorus fertilizer distributed through the trickle system was immobilized within 10 cm or less of the emitters. Because transplanted seedlings were placed directly over the emitters, this "banding" effect was more efficient than broadcast applications at similar rates in supplying nutrients to the first crop of lettuce. The results of this research suggest that economy in time and expense may be achieved with a no-till, controlled traffic, subsurface trickle irrigation system. This method permits vegetable growers and others to exploit the benefits of reduced tillage, optimum soil-water conditions, and distribution of fertilizers through the irrigation system. In addition, phosphorus use efficiency may be increased by transplanting over the emitters. With this approach, growers can minimize the cost of lateral line repair and eliminate the cost of removing or replacing trickle laterals for each harvest cycle

    Report of the panel on lithospheric structure and evolution, section 3

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    The panel concluded that NASA can contribute to developing a refined understanding of the compositional, structural, and thermal differences between continental and oceanic lithosphere through a vigorous program in solid Earth science with the following objectives: determine the most fundamental geophysical property of the planet; determine the global gravity field to an accuracy of a few milliGals at wavelengths of 100 km or less; determine the global lithospheric magnetic field to a few nanoTeslas at a wavelength of 100 km; determine how the lithosphere has evolved to its present state via acquiring geologic remote sensing data over all the continents

    Phase Transitions in Chemisorbed Systems

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    Contains reports on six research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003

    Processing and Transmission of Information

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    Contains research objectives and reports on two research projects.National Aeronautics and Space Administration under Grant NsG-334Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 36-039-AMC-03200(E)National Science Foundation (Grant GP-2495)National Aeronautics and Space Administration (Grant NsG-496

    Genetic parameters estimated at receiving for circulating cortisol, immunoglobulin G, interleukin 8, and incidence of bovine respiratory disease in feedlot beef steers

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    Citation: Cockrum, R. R., Speidel, S. E., Salak-Johnson, J. L., Chase, C. C. L., Peel, R. K., Weaber, R. L., . . . Enns, R. M. (2016). Genetic parameters estimated at receiving for circulating cortisol, immunoglobulin G, interleukin 8, and incidence of bovine respiratory disease in feedlot beef steers. Journal of Animal Science, 94(7), 2770-2778. doi:10.2527/jas2015-0222Bovine respiratory disease complex (i.e., shipping fever and bacterial bronchopneumonia) is a multifaceted respiratory illness influenced by numerous environmental factors and microorganisms. Bovine respiratory disease (BRD) is just one component of BRD complex. Because BRD is moderately heritable, it may be possible to reduce the incidence of BRD through genetic selection. The objectives of this study were to determine the heritability and associative genetic relationships among immune system traits (i.e., cortisol, total IgG, IgG isotypes, and IL-8) in cattle monitored for BRD incidence. At an average of 83 d after weaning (219 d age and mean = 221.7 kg [SD 4.34]), crossbred Bos taurus steer calves (n = 2,869) were received at a commercial feedlot in southeastern Colorado over a 2-yr period. At receiving, jugular blood samples were collected at 212 (yr 1) and 226 d (yr 2) of age for immune trait analyses. The BRD phenotype was defined as a binomial variable (0 = no and 1 = yes) and compared with immune system traits measured at receiving (prior to illness onset). An animal identified as BRD positive exhibited ? 2 clinical signs (i.e., eye or nasal discharge, cough, lethargy, rapid breathing, acute interstitial pneumonia, or acute upper respiratory syndrome and/or a rectal temperature > 39.7°C). Heritability and genetic correlation estimates for categorical variable BRD, cortisol, IgG, IgG1, IgG2, and IL-8 were estimated from a sire model using ASREML. Heritability estimates were low to moderate for BRD (0.17 ± 0.08), cortisol (0.13 ± 0.05), IgG (0.15 ± 0.05), IgG1 (0.11 ± 0.05), IgG2 (0.24 ± 0.06), and IL-8 (0.30 ± 0.06). A moderate negative genetic correlation was determined between BRD and cortisol (rg = ?0.19 ± 0.32). Moderate positive correlations were found between BRD with IgG (0.42 ± 0.28), IgG1 (0.36 ± 0.32), and IL-8 (rg = 0.26 ± 0.26). Variation in the BRD phenotype and immune system traits suggested herd health improvement may be achieved through genetic selection. © 2016 American Society of Animal Science. All rights reserved

    Genetic relationships among temperament, immune function, and carcass merit

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    Cattle producers historically have selected for docile temperaments simply for management convenience because calmer animals are conducive to safe environments for their peers as well as their handlers. As many producers would acknowledge, there seems to be a relationship between temperament and health, and calmer cattle tend to frequent the working chute for treatment of disease less often. Positive correlations have been found in cattle between temperament traits (chute scores, pen scores, and chute exit velocities) and cortisol concentration in the blood, suggesting that more excitable cattle are easily stressed (Curley et al., 2006; Cooke et al., 2009). In addition, Curley et al. (2007) found that easily excitable animals sustain elevated cortisol concentrations for a longer duration and had greater pituitary and adrenal responses following a stressor than calm cattle. Temperamental cattle have significantly higher mean temperament responses at all points (Oliphint, 2006). Higher basal serum cortisol concentrations may suggest that easily excitable cattle are chronically stressed (Curley et al., 2007), possibly resulting in a compromised immune system, illness, and decreased fat and protein deposition. Common measures of cattle temperament are pen scores, chute scores, and exit velocities. Temperament appears to be moderately heritable, with estimates ranging from 0.15 to 0.44 (Burrow and Corbet, 2000; Kadel et al., 2006; Schrode and Hammack, 1971; Stricklin et al., 1980; Fordyce et al., 1988). If genetic correlations are found between temperament and production traits or immunological factors, they may aid cattle breeders in producing profitable cattle. Such relationships have been found between exit velocity and hot carcass weight (r = -0.54), exit velocity and marbling score (r = 0.10), exit velocity and yield grade (r = -0.22) (Nkrumah et al., 2007), and post-weaning weight gain and exit velocity (Weaber et al., 2006). Bovine respiratory disease (BRD) susceptibility has been estimated to be lowly heritable (Muggli-Cockett et al., 1992; Snowder et al., 2005, 2006, 2007; Schneider et al., 2008). This study was conducted to further investigate the genetic relationships between cattle temperament measured by chute score and exit velocity, immunological factors, and a range of economically relevant performance traits

    The effect of review writing on learning engagement in channel partner relationship management

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    To develop the knowledge and skill sets of channel partner firms, firms increasingly introduce learning programs as part of their relationship management strategies. Yet, the engagement of channel partners in these programs tends to be low though. The current research, conducted in collaboration with a Fortune 100 information technology company, examines ways to strengthen learning engagement. In accordance with self-regulated learning theory, the authors propose and demonstrate that when channel partners write reviews of a learning module that they attended, beyond providing ratings,they are better able to reflect on the relevance of their learning experience and they are further engaged in learning activities. The audience and focus of these written reviews determine the engagement of the channel partner sales personnel. Therefore, review writing is a valuable, informal mechanism to motivate them. These effects are moderated by characteristics of both the channel partner (learning orientation of the salesperson, identification with the manufacturer) and the relationship with the manufacturer (length and exclusivity)

    Selection on stability across ecological scales

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    Much of the focus in evolutionary biology has been on the adaptive differentiation among organisms. It is equally important to understand the processes that result in similarities of structure among systems. Here, we discuss examples of similarities occurring at different ecological scales, from predator–prey relations (attack rates and handling times) through communities (food-web structures) to ecosystem properties. Selection among systemic configurations or patterns that differ in their intrinsic stability should lead generally to increased representation of relatively stable structures. Such nonadaptive, but selective processes that shape ecological communities offer an enticing mechanism for generating widely observed similarities, and have sparked new interest in stability properties. This nonadaptive systemic selection operates not in opposition to, but in parallel with, adaptive evolution
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