4,699 research outputs found

    Ronald Reagan, Jesse Unruh and the California Gubernatorial Race, 1970

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    This essay examines the 1970 gubernatorial race in California between incumbent Ronald Reagan and powerful California legislator Jesse Unruh. Most of the scholarship on this particular subject tends to revolve around Reagan\u27s first campaign for governor, but neglects his re-election campaign. Although Unruh would lose the campaign, he narrowed Reagan\u27s win significantly. This study examines the candidates themselves, the issues facing California at the time, strategies used by each camp, and possible reasons why voters strayed from Reagan to the Unruh camp, and the final outcome of the race

    Surveying the Scope of the SU(2)_L Scalar Septet Sector

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    Extending the Standard Model by adding a scalar field transforming as a septet under SU(2)LSU(2)_L preserves the ρ\rho parameter at tree level and can satisfy experimental constraints on the electroweak parameters SS and TT. This work presents the first fully general phenomenological study of such an extension. We examine constraints on the septet model couplings based on electroweak and Higgs observables, and use LHC searches for new physics to bound the mass of the septet to be above 400\sim 400 GeV at a 95%95\% CL.Comment: pdfLateX, 17 pages, 6 figures, reference added. Version published in JHE

    Optimal parallel solution of sparse triangular systems

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    A method for the parallel solution of triangular sets of equations is described that is appropriate when there are many right-handed sides. By preprocessing, the method can reduce the number of parallel steps required to solve Lx = b compared to parallel forward or backsolve. Applications are to iterative solvers with triangular preconditioners, to structural analysis, or to power systems applications, where there may be many right-handed sides (not all available a priori). The inverse of L is represented as a product of sparse triangular factors. The problem is to find a factored representation of this inverse of L with the smallest number of factors (or partitions), subject to the requirement that no new nonzero elements be created in the formation of these inverse factors. A method from an earlier reference is shown to solve this problem. This method is improved upon by constructing a permutation of the rows and columns of L that preserves triangularity and allow for the best possible such partition. A number of practical examples and algorithmic details are presented. The parallelism attainable is illustrated by means of elimination trees and clique trees

    Effects of Corn and Selected Weed Species on Feeding Behavior of the Stalk Borer, \u3ci\u3ePapaipema Nebris\u3c/i\u3e (Lepidoptera: Noctuidae)

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    Experiments were conducted in an outdoor insectary to examine behavioral interactions between fifth instar stalk borers, Papaiperna nebris, and potential host plant species. Plants tested included 6- and 8-leaf stage corn, Zea mays, and ten weed species (six broadleaf and four grass) commonly associated with corn production in southern Wisconsin. Broadleaf plants found to be acceptable hosts included Ambrosia trifida, Arnaranthus retroflexus, Rumex crispus, and Chenopodium album; Asclepias syriaca and Abutilon theophrasti were not acceptable as host plants. Corn and the other grass species (Agropyron repens, Bromus inermis, Dactylis glomerata, and Setaria faberi) were found to be acceptable hosts. All acceptable plants also supported larval development to the pupal stage, though on 6-leaf stage corn and the small-stemmed grasses the majority of larvae dispersed before completing development. Larvae developing on corn, A. triftda, and A. retroflexus pupated within the plant stem, whereas larvae developing on the other plants pupated in the soil near the plant on which they fed. Stalk borer larvae required substantially less time to bore into corn stalks than into the stems of the broadleaf plants. In a limited preference experiment, corn was clearly preferred as a host plant over the three broadleaf and one small-stemmed grass species tested

    Direct AC Generation from Solar Cell Arrays

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    Results of the investigation of the performance of solar cells when directly coupled to a conventional three-phase power network are presented. This approach dissociates the electricity production problem from the electric energy storage problem. Extensive studies of the required power inverter are performed. Preliminary simulation results indicate that ac power outputs of better than 90% of the optimum cell power output can be easily achieved by means of a suitably controlled inverter, thereby justifying the elimination of dc loads or local dc electric energy storage devices. It is also shown that the controlling policy for the inverter must depend on the operating conditions of the system, such as cell temperature, solar intensity and power system voltage variations, otherwise the performance of the inverter can deteriorate quite dramatically

    Cancer modeling: from optimal cell renewal to immunotherapy

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    Cancer is a disease caused by mutations in normal cells. According to the National Cancer Institute, in 2016, an estimated 1.6 million people were diagnosed and approximately 0.5 million people died from the disease in the United States. There are many factors that shape cancer at the cellular and organismal level, including genetic, immunological, and environmental components. In this thesis, we show how mathematical modeling can be used to provide insight into some of the key mechanisms underlying cancer dynamics. First, we use mathematical modeling to investigate optimal homeostatic cell renewal in tissues such as the small intestine with an emphasis on division patterns and tissue architecture. We find that the division patterns that delay the accumulation of mutations are strictly associated with the population sizes of the tissue. In particular, patterns with long chains of differentiation delay the time to observe a second-hit mutant, which is important given that for many cancers two mutations are enough to initiate a tumor. We also investigated homeostatic cell renewal under a selective pressure and find that hierarchically organized tissues act as suppressors of selection; we find that an architecture with a small number of stem cells and larger pools of transit amplifying cells and mature differentiated cells, together with long chains of differentiation, form a robust evolutionary strategy to delay the time to observe a second-hit mutant when mutations acquire a fitness advantage or disadvantage. We also formulate a model of the immune response to cancer in the presence of costimulatory and inhibitory signals. We demonstrate that the coordination of such signals is crucial to initiate an effective immune response, and while immunotherapy has become a promising cancer treatment over the past decade, these results offer some explanations for why it can fail

    Temperature dependence of the nonlocal voltage in an Fe/GaAs electrical spin injection device

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    The nonlocal spin resistance is measured as a function of temperature in a Fe/GaAs spin-injection device. For nonannealed samples that show minority-spin injection, the spin resistance is observed up to room temperature and decays exponentially with temperature at a rate of 0.018\,K1^{-1}. Post-growth annealing at 440\,K increases the spin signal at low temperatures, but the decay rate also increases to 0.030\,K1^{-1}. From measurements of the diffusion constant and the spin lifetime in the GaAs channel, we conclude that sample annealing modifies the temperature dependence of the spin transfer efficiency at injection and detection contacts. Surprisingly, the spin transfer efficiency increases in samples that exhibit minority-spin injection.Comment: 10 pages, 4 figure
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