Field Crops Research

Downy brome (Bromus tectorum L.) is a problematic weed for the conventional fallow/winter wheat (F/W) production system in the low precipitation-region (\u3c 350mm yr−1) of the Pacific Northwest. A 4-yr field experiment was conducted to determine if incorporating spring barley (B, Hordeum vulgare L.) or spring carinata (C, Brassica carinata A. Braun) into 3-yr crop rotations with W would benefit weed management. The experimental design was a split-plot with four replications where each phase was present every year for the following rotations: 1) F/W, 2) F/W/B, and 3) F/W/C. Reduced tillage, consisting of a single undercutting operation with a wide-blade sweep, and herbicides were used to control weeds during the fallow period. The seeded plots were subdivided in three different weed management areas: a weed-free area where weeds were pulled by hand, a weedy area with no weed control and a general area where weeds were chemically controlled. Weed density and cover per species and W yield were evaluated in each rotation. Grass cover and density after one and two complete cropping cycles were significantly higher in F/W than in F/W/B and F/W/C. Reduction in density and cover of total weeds was found after two cycles. However, differences in community biodiversity were only found between F/W, and F/W/B or F/W/C in 2017. Winter wheat plots of F/W had more downy brome than F/ W/B or F/W/C indicating the greater capacity of the latter to control this weed. In 2018, the 3-yr rotation with barley had greater winter wheat grain yield compared with F/W when weeds were not present though weeds were more competitive in F/W/B. Intensifying the F/W cropping system into a 3-yr crop rotation of W followed by spring barley or spring carinata may reduce weed infestations of winter annual grasses that are difficult to control in W and the most competitive due to larger similarities in their life cycle with this crop

Hubungan Sikap dan Motivasi Belajar dengan Prestasi Belajar IPS Terpadu Siswa Kelas VIII

The research aims to find out (1) the relationship between students learning attitude and achievement, (2) the relationship between students learning motivation and achievement, (3) the relationship between students learning attitude and achievement in Integrated Social Studies at 8th grade of SMPN 2 Raman Utara, Lampung Timur, academic year 2015-2016. The research was conducted quantitatively whose research population was the students of 8th grade of SMPN 2 Raman Utara. Research sampling was taken through proportional random sampling with 51 sample. Data was analyzed by Spearman coefficient correlation and multiple correlation. Results of the research show that (1) there is positive relationship between students learning attitude and achievement, (2) there is positive relationship between students learning motivation and achievement, (3) there is positive relationship between students learning attitude, motivation, and achievement in Integrated Social Studies at 8th grade of SMPN 2 N Raman Utara, Lampung Timur, academic year 2015-2016.Penelitian ini bertujuan untuk mengetahui (1) hubungan sikap dengan prestasi belajar, (2) hubungan motivasi dengan prestasi belajar, (3) hubungan sikap dan motivasi dengan prestasi belajar pada mata pelajaran IPS Terpadu siswa kelas VIII di SMPN 2 Raman Utara Lampung Timur tahun ajaran 2015/2016. Jenis penelitian ini adalah penelitian kuantitatif. Populasi penelitian adalah siswa kelas VIII di SMPN 2 Raman Utara. Teknik pengambilan sampel penelitian menggunakan proportional random sampling, dengan jumlam sampel sebanyak 51 siswa. Analisis data penelitian menggunakan koefisien korelasi Spearman dan korelasi ganda. Hasil penelitian menunjukkan bahwa (1) ada hubungan positif antara sikap dengan prestasi belajar,(2) ada hubungan positif antara motivasi dengan prestasi belajar, (3) ada hubungan positif antara sikap dan motivasi belajar dengan prestasi belajar IPS Terpadu siswa kelas VIII di SMPN 2 Raman Utara Lampung Timur tahun ajaran 2015/2016

The Szego Kernel for Non-Pseudoconvex Domains in C\u3csup\u3e2\u3c/sup\u3e

There are many operators associated with a domain Ω ⊂ ℂn with smooth boundary ∂Ω. There are two closely related projections that are of particular interest. The Bergman projection B is the orthogonal projection of L2(Ω) onto the closed subspace L2(Ω)∩O(Ω), where O(Ω)is the space of all holomorphic functions on Ω. The Szeg� projection S is the orthogonal projection of L2(∂Ω) onto the space H2(Ω) of boundary values of elements of O(Ω). These projection operators have integral representations B[f](z) = ∫Ω,f(w)B(z,w)dw, S[f](z) = ∫∂Ω,f(w)S(z,w)do(w). The distributions B and S are known respectively as the Bergman and Szeg� kernels. In an attempt to prove that B and S are bounded operators on Lp, 1 \u3c p \u3c ∞, many authors have obtained size estimates for the kernels B and S for pseudoconvex domains in ℂn. In this thesis, we restrict our attention to the Szeg� kernel for a large class of domains of the form 1 Such a domain fails to be pseudoconvex precisely when b is not convex on all of R. In an influential paper, Nagel, Rosay, Stein, and Wainger obtain size estimates for both kernels and sharp mapping properties for their respective operators in the convex setting. Consequently, if b is a convex polynomial, the Szeg� kernel S is absolutely convergent off the diagonal only. Carracino proves that the Szeg� kernel has singularities on and off the diagonal for a specific non-smooth, {non-convex piecewise defined quadratic b. Her results are novel since very little is known for the Szeg� kernel for non-pseudoconvex domains 2. I take b to be an arbitrary even-degree polynomial with positive leading coefficient and identify the set in 3 on which the Szeg� kernel is absolutely convergent. For a polynomial b, we will see that the Szeg� kernel is smooth off the diagonal if and only if b is convex. These results provide an incremental step toward proving the projection S is bounded on 4, for a large class of non-pseudoconvex domains Ω

Surgery of spline-type and molecular frames

We prove a result about producing new frames for general spline-type spaces by piecing together portions of known frames. Using spline-type spaces as models for the range of certain integral transforms, we obtain results for time-frequency decompositions and sampling.Comment: 34 pages. Corrected typo

Categorification of some level two representations of sl(n)

We categorify representations of quantum sl(n) whose highest weight is twice a fundamental weight.Comment: 22 pages, 13 eps figure

Nonlinear Matroid Optimization and Experimental Design

We study the problem of optimizing nonlinear objective functions over matroids presented by oracles or explicitly. Such functions can be interpreted as the balancing of multi-criteria optimization. We provide a combinatorial polynomial time algorithm for arbitrary oracle-presented matroids, that makes repeated use of matroid intersection, and an algebraic algorithm for vectorial matroids. Our work is partly motivated by applications to minimum-aberration model-fitting in experimental design in statistics, which we discuss and demonstrate in detail