222 research outputs found

    Row spacing and planting date effect on yield and growth responses of soybeans

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    In field experiments during 1987-1990, cotton plants were grown under 8 different levels of nitrogen application to assess the impact of nitrogen fertilization on the fruiting and yield distribution of cotton within the plant (Boquet et al. 1993).lr.dividual boll weights and average seedcotton yield were determined at each fruiting site fur each main-stem node along the plant. Various models of dependence and independence are possible to explain and account for the dependencies of the yields among the sites and nodes of the plant. Here we investigate models of total yield per node and yield per node adjusted for the number of sites using several models for the spatial dependence among the nodes. Typical univariate models would either assume a simple homogeneous error structure or a compound symmetry error structure among the nodes, leading to the split-plot-type models. A multivariate unstructured approach ignores obvious spatial dependencies among the nodes. Spatial models and ante-dependence models permit a parsimonious summary of the error structure and are compared with the compound symmetry and multivariate models

    Residue management in double-crop systems: Impact on soybean growth and yield

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    Double-crop soybeans [Glycine max(L.) Merr.] have the potential to be a productive and profitable system. However, due to delayed planting, double-crop soybeans frequently experience lower yields and higher stress. Because planting is a major production constraint, a critical practice is the management of previous wheat residue. Trials were established in 2012, 2013, and 2014 in Saint Joseph, LA, and in 2013 and 2014 in Winnsboro, LA. The four residue management treatments investigated included conventionally tilled, planted into burned residue, planted into mowed residue, and planted into standing wheat residue. Vegetative and reproductive growth parameters, as well as yield, were used to evaluate the influence of residue management on productivity. Overall, residue management did not have a significant impact on early season growth parameters, except for plant height in 2012 at St. Joseph; however, it did significantly influence yield at both locations. In Saint Joseph in 2012, yields from planting into wheat residue were significantly lower than burned and mowed plots (1.2 compared with 2.8 and 2.7 Mg ha-1, respectively), and tilled treatments yielded significantly less than all three nontilled treatments in 2013 and 2014. In Winnsboro, planting into residue left on the soil surface resulted in significantly higher yields than when residue was removed. Overall, leaving residue on the soil surface provided stable yields across years and locations; however, not managing the residue can result in diminished yields. Therefore, practices such as mowing of wheat residue prior to planting provide an alternative to traditional no-till planting.Peer reviewedPlant and Soil Science

    Properties of Graphene: A Theoretical Perspective

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    In this review, we provide an in-depth description of the physics of monolayer and bilayer graphene from a theorist's perspective. We discuss the physical properties of graphene in an external magnetic field, reflecting the chiral nature of the quasiparticles near the Dirac point with a Landau level at zero energy. We address the unique integer quantum Hall effects, the role of electron correlations, and the recent observation of the fractional quantum Hall effect in the monolayer graphene. The quantum Hall effect in bilayer graphene is fundamentally different from that of a monolayer, reflecting the unique band structure of this system. The theory of transport in the absence of an external magnetic field is discussed in detail, along with the role of disorder studied in various theoretical models. We highlight the differences and similarities between monolayer and bilayer graphene, and focus on thermodynamic properties such as the compressibility, the plasmon spectra, the weak localization correction, quantum Hall effect, and optical properties. Confinement of electrons in graphene is nontrivial due to Klein tunneling. We review various theoretical and experimental studies of quantum confined structures made from graphene. The band structure of graphene nanoribbons and the role of the sublattice symmetry, edge geometry and the size of the nanoribbon on the electronic and magnetic properties are very active areas of research, and a detailed review of these topics is presented. Also, the effects of substrate interactions, adsorbed atoms, lattice defects and doping on the band structure of finite-sized graphene systems are discussed. We also include a brief description of graphane -- gapped material obtained from graphene by attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic

    Joint Arthroplasties other than the Hip in Solid Organ Transplant Recipients

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    Transplantation Surgery has undergone a great development during the last thirty years and the survival of solid organ recipients has increased dramatically. Osteo-articular diseases such as osteoporosis, fractures, avascular bone necrosis and osteoarthritis are relatively common in these patients and joint arthroplasty may be required. The outcome of hip arthroplasty in patients with osteonecrosis of the femoral head after renal transplantation has been studied and documented by many researchers. However, the results of joint arthroplasties other than the hip in solid organs recipients were only infrequently reported in the literature. A systematic review of the English literature was conducted in order to investigate the outcome of joint arthroplasties other than the hip in kidney, liver or heart transplant recipients. Nine pertinent articles including 51 knee arthroplasties, 8 shoulder arthroplasties and 1 ankle arthroplasty were found. These articles reported well to excellent results with a complication rate and spectrum comparable with those reported in nontransplant patients

    A critical discussion of the physics of wood–water interactions

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