257 research outputs found

    The use of air induction nozzles for herbicide application to sugar beet.

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    End of Project ReportTrials were carried out over a three-year period in Oak Park to compare airinduction with conventional nozzles for weed control in sugar beet. Two makes of low-drift nozzle (Bubble Jet and DriftBETA) were compared with conventional fans. All nozzles were used at a pressure of 3 bar. Two sizes (015 and 03) of each type of nozzle were used, to allow volumes of 110 and 220 litres per hectare to be applied. These nozzles were used to apply two-spray programmes to sugar-beet crops. In four of the weed control trials, tank mixes of products with some residual action (Progress, Goltix, Venzar and Debut) were used. In the other two trials, a contact-only spray (Betanal E) was used. The aim was to see how the nozzles behaved with contact-only sprays as well as those with more complex modes of action. Spray drift was also measured with the size 03 nozzles. Spray drift reductions from 37% to 64% were measured when the air-induction nozzles were compared with conventional fans. In general, the tank mix programme gave better weed control than the contact-only treatments. Within programmes, differences between the application methods were significant in two trials. In both of these, the conventional nozzles gave the best results. Looking at the mean results of the tank-mix trials, two trends were suggested: higher water volumes gave slightly better weed control, and the effect of the coarser sprays was slight. With the contact-only sprays, the decline in performance with the coarser sprays was more emphatic, and the lower volumes appeared to give slightly better control. It is concluded that in calm conditions conventional fan or cone nozzles should continue to be used, but that air-induction nozzles are a valuable fall-back when it is necessary to spray in a moderate breeze. In these situations, and with the normal tank-mix programmes, small nozzle sizes applying very low volumes should be avoided. Makes of air-induction nozzle which give very coarse spray should also be avoided

    Charge Dynamics in the Planar t-J Model

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    The finite-temperature optical conductivity σ(ω)\sigma(\omega) in the planar tJt-J model is analysed using recently introduced numerical method based on the Lanczos diagonalization of small systems (up to 20 sites), as well as by analytical approaches, including the method of frequency moments and the retraceable-path approximation. Results for a dynamical mobility of a single hole at elevated temperatures T>tT>t reveal a Gaussian-like μ(ω)\mu(\omega) spectra, however with a nonanalytical behavior at low ω\omega. In the single hole response a difference between the ferromagnetic (J=0) and the antiferromagnetic (J>0J>0) polaron shows up at T<JT<J. At larger dopings numerical results in studied systems are consistent with the thermodynamical behavior for T>T0.1 tT>T^*\ge 0.1~t. σ(ω)\sigma(\omega) spectra show a non-Drude falloff at large frequencies. In particular for `optimum' doping nh0.2n_h \sim 0.2 we obtain in the low-ω,T\omega,T regime the relaxation rate τ10.6(ω+ξT)\tau^{-1} \sim 0.6 (\omega+\xi T) with ξ3\xi \sim 3, being consistent with the marginal Fermi liquid concept and experiments. Within the same regime we reproduce the nearly linear variation of dc resistivity ρ\rho with TT. This behavior is weakly dependent on JJ, provided that J<tJ<t.Comment: 21 pages of text plus 17 figures, postscrip

    Pseudoexon activation increases phenotype severity in a Becker muscular dystrophy patient

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    We report a dystrophinopathy patient with an in-frame deletion of DMD exons 45–47, and therefore a genetic diagnosis of Becker muscular dystrophy, who presented with a more severe than expected phenotype. Analysis of the patient DMD mRNA revealed an 82 bp pseudoexon, derived from intron 44, that disrupts the reading frame and is expected to yield a nonfunctional dystrophin. Since the sequence of the pseudoexon and canonical splice sites does not differ from the reference sequence, we concluded that the genomic rearrangement promoted recognition of the pseudoexon, causing a severe dystrophic phenotype. We characterized the deletion breakpoints and identified motifs that might influence selection of the pseudoexon. We concluded that the donor splice site was strengthened by juxtaposition of intron 47, and loss of intron 44 silencer elements, normally located downstream of the pseudoexon donor splice site, further enhanced pseudoexon selection and inclusion in the DMD transcript in this patient

    Extent and Causes of Chesapeake Bay Warming

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    Coastal environments such as the Chesapeake Bay have long been impacted by eutrophication stressors resulting from human activities, and these impacts are now being compounded by global warming trends. However, there are few studies documenting long-term estuarine temperature change and the relative contributions of rivers, the atmosphere, and the ocean. In this study, Chesapeake Bay warming, since 1985, is quantified using a combination of cruise observations and model outputs, and the relative contributions to that warming are estimated via numerical sensitivity experiments with a watershed–estuarine modeling system. Throughout the Bay’s main stem, similar warming rates are found at the surface and bottom between the late 1980s and late 2010s (0.02 +/- 0.02C/year, mean +/- 1 standard error), with elevated summer rates (0.04 +/- 0.01C/year) and lower rates of winter warming (0.01 +/- 0.01C/year). Most (~85%) of this estuarine warming is driven by atmospheric effects. The secondary influence of ocean warming increases with proximity to the Bay mouth, where it accounts for more than half of summer warming in bottom waters. Sea level rise has slightly reduced summer warming, and the influence of riverine warming has been limited to the heads of tidal tributaries. Future rates of warming in Chesapeake Bay will depend not only on global atmospheric trends, but also on regional circulation patterns in mid-Atlantic waters, which are currently warming faster than the atmosphere. Supporting model data available at: https://doi.org/10.25773/c774-a36
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