1,632 research outputs found

    Selection indices for the improvement of opaque-2 maize

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    The interrelationships among agronomic, protein quality, and kernel quality characters in opaque-2 maize (Zea mays L.) require consideration of multiple traits in selection. Data from genetic studies in an opaque-2 maize synthetic were utilized to calculate selection indices for use in recurrent selection. Grain yield was considered the only trait having economic value. Restricted indices were used to achieve satisfactory gains in kernel hardness, moisture content and protein content and quality;The most important traits with respect to achieving the specified selection goals were yield, moisture content, kernel hardness, lysine content, kernel weight and the degree of light transmission by kernels. Indices incorporating five traits were the most efficient in that the addition of a sixth trait contributed very little to expected gains. The most effective combinations of traits for the recurrent selection scheme involving S(,1) testing were also the most effective for full-sib testing and S(,2) testing;The degree to which gains predicted for an index were dependent on accurate estimates of the population parameters was considered. Indices having weights that implied reliance on correlated rather than direct selection response were not recommended;Substitution of single plant data for data from replicated progeny tests was considered in connection with each breeding scheme. The possibility of increasing the effective selection intensity, given that resources for replicated testing were fixed, by culling individual plants was investigated, but the disadvantages of utilizing single plant data appeared to outweigh the advantages

    Stellar Polarimetry: Where Are We and Where Are We Going?

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    On the final day of the Stellar Polarimetry conference, participants split up into three "breakout sessions" to discuss the future of the field in the areas of instrumentation, upcoming opportunities, and community priorities. This contribution compiles the major recommendations arising from each breakout session. We hope that the polarimetric community will find these ideas useful as we consider how to maintain the vitality of polarimetry in the coming years.Comment: 7 pages, published in proceedings of "Stellar Polarimetry: From Birth to Death" (Madison, WI, June 2011

    Asymptotic Opening Angles for Colliding-Wind Bow Shocks: the Characteristic-Angle Approximation

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    By considering the advection and interaction of the vector momentum flux in highly supersonic spherically diverging winds, we derive a simple analytic description of the asymptotic opening angle of a wind-collision shock cone, in the approximation that the shocked gas is contained in a cone streaming out along a single characteristic opening angle. Both highly radiative and highly adiabatic limits are treated, and their comparison is the novel result. Analytic closed-form expressions are obtained for the inferred wind momentum ratios as a function of the observed shock opening angle, allowing the conspicuous shape of the asymptotic bow shock to be used as a preliminary constraint on more detailed modeling of the colliding winds. In the process, we explore from a general perspective the limitations in applying to the global shock geometry the so-called Dyson approximation, which asserts a local balance in the perpendicular ram pressure across the shock.Comment: 16 pages, 1 figur

    Asymptotic Freedom and Bound States in Hamiltonian Dynamics

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    We study a model of asymptotically free theories with bound states using the similarity renormalization group for hamiltonians. We find that the renormalized effective hamiltonians can be approximated in a large range of widths by introducing similarity factors and the running coupling constant. This approximation loses accuracy for the small widths on the order of the bound state energy and it is improved by using the expansion in powers of the running coupling constant. The coupling constant for small widths is order 1. The small width effective hamiltonian is projected on a small subset of the effective basis states. The resulting small matrix is diagonalized and the exact bound state energy is obtained with accuracy of the order of 10% using the first three terms in the expansion. We briefly describe options for improving the accuracy.Comment: plain latex file, 15 pages, 6 latex figures 1 page each, 1 tabl

    Physiology of Sporeforming Bacteria Associated with Insects: Radiorespirometric Survey of Carbohydrate Metabolism In the 12 Serotypes of \u3ci\u3eBacillus thuringiensis\u3c/i\u3e

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    Radiorespirometry was used to compare the primary pathways of glucose catabolism in 18 strains of Bacillus thuringiensis representing the 12 established serotypes. Every strain utilizes the Embden-Meyerhof-Pamas pathway almost exclusively; pentose-phosphate pathway participation is minor. The Embden- Meyerhof-Parnas pathway predominates regardless of whether the cells were grown in a minimal medium or one containing yeast extract. The results indicate that the absolute requirement for citrate and related compounds is not a result of defective citrate or glucose transport and metabolism

    Cognitive Function in Patients Undergoing Arthroplasty: The Implications for Informed Consent

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    Obtaining informed consent for an operation is a fundamental daily interaction between orthopaedic surgeon and patient. It is based on a patient's capacity to understand and retain information about the proposed procedure, the potential consequences of having it, and the alternative options available. We used validated tests of memory on 59 patients undergoing lower limb arthroplasty to assess how well they learned and recalled information about their planned procedure. All patients showed an ability to learn new material; however, younger age and higher educational achievement correlated with better performance. These results have serious implications for orthopaedic surgeons discussing planned procedures. They identify groups of patients who may require enhanced methods of communicating the objectives, risks, and alternatives to surgery. Further research is necessary to assess interventions to improve communication prior to surgery

    A comparison of attitudes towards stuttering of non-stuttering preschoolers in the United States and Turkey

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    Background and objectives: Extensive research documents ubiquitous negative attitudes towards stuttering, but when and how they develop is unclear. This non-experimental, comparative study examined US and Turkish preschoolers to explore the origin of stuttering attitudes cross-culturally. Method: The authors compared stuttering attitudes of 28 US and 31 Turkish non-stuttering preschoolers on English and Turkish versions of experimental prototypes of the newly developed Public Opinion Survey on Human Attributes–Stuttering/Child (POSHA–S/Child). Children first watched a short video of two stuttering avatar characters and then answered oral questions about stuttering. Parents completed a demographic questionnaire. Differences in the US and Turkish POSHA–S/Child means were calculated using the Mann–Whitney U test. Results: Attitudes of the US and Turkish children were remarkably similar. Children rated most of the items negatively but also rated some items as neutral or positive. They held relatively more negative attitudes towards traits and personalities of children who stutter yet relatively more positive attitudes towards stuttering children’s potential. Conclusion: Stuttering attitudes in children appear to be partly independent of culture
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