3,217 research outputs found

    Enhancement and suppression effects resulting from information structuring in sentences

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    Information structuring through the use of cleft sentences increases the processing efficiency of references to elements within the scope of focus. Furthermore, there is evidence that putting certain types of emphasis on individual words not only enhances their subsequent processing, but also protects these words from becoming suppressed in the wake of subsequent information, suggesting mechanisms of enhancement and suppression. In Experiment 1, we showed that clefted constructions facilitate the integration of subsequent sentences that make reference to elements within the scope of focus, and that they decrease the efficiency with reference to elements outside of the scope of focus. In Experiment 2, using an auditory text-change-detection paradigm, we showed that focus has similar effects on the strength of memory representations. These results add to the evidence for enhancement and suppression as mechanisms of sentence processing and clarify that the effects occur within sentences having a marked focus structure

    Laboratory and observational study of the interrelation of the carbonaceous component of interstellar dust and solar system materials

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    By studying the chemical and isotopic composition of interstellar ice and dust, one gains insight into the composition and chemical evolution of the solid bodies in the solar nebula and the nature of the material subsequently brought into the inner part of the solar system by comets and meteorites. It is now possible to spectroscopically probe the composition of interstellar ice and dust in the mid-infrared, the spectral range which is most diagnostic of fundamental molecular vibrations. We can compare these spectra of various astronomical objects (including the diffuse and dense interstellar medium, comets, and the icy outer planets and their satellites) with the spectra of analogs we produce in the laboratory under conditions which mimic those in these different objects. In this way one can determine the composition and abundances of the major constituents of the various ices and place general constraints on the types of organics coating the grains in the diffuse interstellar medium. In particular we have shown the ices in the dense clouds contain H2O, CH3OH, CO, perhaps some NH3 and H2CO, we well as nitriles and ketones or esters. Furthermore, by studying the photochemistry of these ice analogs in the laboratory, one gains insight into the chemistry which takes place in interstellar/precometary ices. Chemical and spectroscopic studies of photolyzed analogs (including deuterated species) are now underway. The results of some of these studies will be presented and implications for the evolution of the biogenic elements in interstellar dust and comets will be discussed

    GWAS for Fusarium Head Blight Related Traits in Winter Wheat (\u3cem\u3eTriticum Aestivum\u3c/em\u3e L.) in an Artificially Warmed Treatment

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    Global temperature increases will affect Fusarium head blight (FHB) levels in wheat (Triticum aestivum L.). A pressing question is whether current sources of resistance will be effective in a warmer environment. We evaluated phenotypic response to disease in 238 soft winter wheat breeding lines and cultivars grown in 2015–2016 and 2016–2017 under control and warmed (+3 °C) conditions. Warming was achieved with heating cables buried 3 cm in the rhizosphere. We measured heading date, plant height, yield, FHB rating, Fusarium damaged kernels (FDK), deoxynivalenol (DON), leaf blotch rating, powdery mildew rating and leaf rust rating. There were significant (p \u3c 0.01) differences among genotypes for all traits measured. Genome-wide association study (GWAS) identified 19 and 10 significant SNPs in the control and warmed treatments, respectively. FDK and DON levels were often significantly (p \u3c 0.05) higher in warmed than in control when we contrasted alleles at important quantitative trait locus (QTL) such as Fhb1, Rht-B1 and D1 and all vernalization and photoperiod loci. Increased rhizosphere temperature resulted in a significantly (p \u3c 0.01) earlier heading date (~3.5 days) both years of the study. Rank correlation between warmed and control treatments was moderate (r = 0.56). Though encouraging, it indicates that selection for performance under warming should be carried out in a warmed environment

    What is the initiation step of the Grubbs-Hoveyda olefin metathesis catalyst?

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    Density function theory calculations reveal that the Grubbs-Hoveyda olefin metathesis pre-catalyst is activated by the formation of a complex in which the incoming alkene substrate and outgoing alkoxy ligand are both clearly associated with the ruthenium centre. The computed energies for reaction are in good agreement with the experimental values, reported here

    SUPPLY RESPONSE UNDER THE 1996 FARM ACT AND IMPLICATIONS FOR THE U.S. FIELD CROPS SECTOR

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    The 1996 Farm Act gives farmers almost complete planting flexibility, allowing producers to respond to price changes to a greater extent than they had under previous legislation. This study measures supply responsiveness for major field crops to changes in their own prices and in prices for competing crops and indicates significant increases in responsiveness. Relative to 1986-90, the percentage increases in the responsiveness of U.S. plantings of major field crops to a 1-percent change in their own prices are wheat (1.2 percent), corn (41.6 percent), soybeans (13.5 percent), and cotton (7.9 percent). In percentage terms, the increases in the responsiveness generally become greater with respect to competing crops' price changes. The 1996 legislation has the least effect on U.S. wheat acreage, whereas the law may lead to an average increase of 2 million acres during 1996-2005 in soybean acreage, a decline of 1-2 million acres in corn acreage, and an increase of 0.7 million acres in cotton acreage. Overall, the effect of the farm legislation on regional production patterns of major field crops appears to be modest. Corn acreage expansion in the Central and Northern Plains, a long-term trend in this important wheat production region, will slow under the 1996 legislation, while soybean acreage expansion in this region will accelerate. The authors used the Policy Analysis System-Economic Research Service (POLYSYS-ERS) model that was jointly developed by USDA's Economic Research Service and the University of Tennessee's Agricultural Policy Analysis Center to estimate the effects of the 1996 legislation.Supply response, major field crops, acreage price elasticities, normal flex acreage (NFA), 1996 farm legislation., Agricultural and Food Policy, Crop Production/Industries,

    Laboratory simulation of the photoprocessing and warm-up of cometary and pre-cometary ices: Production of complex organic molecules

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    The recent missions to Comet Halley detected large quantities of organic material on grains as well as organic molecules in the gas phase. A possible origin of these materials is the energetic processing of ice mantles on the grains prior to comet formation, either in the pre-solar nebula or the interstellar medium. This process was simulated in the laboratory by depositing interstellar ice analogs (H2O/CH3OH/CO/NH3) on a cold (10 K) substrate with simultaneous UV irradiation. The material evaporating during warm-up of the photolyzed ice as well as the residue remaining at room temperature was analyzed by a number of techniques. It was found that a large number of organic molecules of various complexity are synthesized during the simulation process, stressing the possible significance of UV photolysis for producing the organic Comet material

    Synthesis, Structure, and Activity of Enhanced Initiators for Olefin Metathesis

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    A series of ruthenium olefin metathesis catalysts of the general structure (H_2IMes)(PR_3)(Cl)_2Ru CHPh (H_2IMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) have been prepared; these complexes are readily accessible in two steps from commercially available (H_2IMes)(PCy_3)(Cl)_2Ru CHPh. Their phosphine dissociation rate constants (k_1), relative rates of phosphine reassociation, and relative reaction rates in ring-opening metathesis polymerization (ROMP) and ring-closing metathesis (RCM) have been investigated. The rates of phosphine dissociation (initiation) from these complexes increase with decreasing phosphine donor strength. Complexes containing a triarylphosphine exhibit dramatically improved initiation relative to (H_2IMes)(PCy_3)(Cl)_2Ru CHPh. Conversely, phosphine reassociation shows no direct correlation with phosphine electronics. In general, increased phosphine dissociation leads to faster olefin metathesis reaction rates, which is of direct significance to both organic and polymer metathesis processes

    Triazine Herbicide Exposure and Breast Cancer Incidence: An Ecologic Study of Kentucky Counties

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    The incidence of breast cancer in the United States has steadily increased for the past three decades. Exposure to excess estrogen, in both natural and synthetic forms, has been implicated as a risk factor for the development of this disease. Considerable interest has been focused on organochlorines, such as the triazine herbicides, and their possible role in the initiation or promotion of human breast cancer. To explore this relationship, an ecologic study of Kentucky counties was designed. Exposure to triazines was estimated by use of water contamination data, corn crop production, and pesticide use data. A summary index of triazine herbicide exposure was developed to classify counties into low, medium, or high exposure levels. Data on county breast cancer rates were obtained from the state registry. A Poisson regression analysis was performed, controlling for age, race, age at first live birth, income, and level of education. Results revealed a statistically significant increase in breast cancer risk with medium and high levels of triazine exposure [odds ratio (OR) = 1.14,p\u3c0.0001 and OR = 1.2, p\u3c0.0001, respectively]. The results suggest a relationship between exposure to triazine herbicides and increased breast cancer risk, but conclusions concerning causality cannot be drawn, due to the limitations inherent in ecologic study design
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