81 research outputs found

    Post-harvest quality of fresh-marketed tomatoes as a function of harvest periods

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    Losses on tomato business chain start at harvest, a two-months period. At the beginning of the harvest, fruits concentrate at the basal part of the plant, then in the middle, and finally at the top, and undergo changes in diameter and maturity indexes as harvest progresses. The aim of this work was to evaluate the impact of handling at three different periods: (I) 15 days, (II) 30 days, and (III) 45 days after the beginning of harvest. Tomatoes were ordinarily grown and harvested in to bamboo baskets, and transferred to plastics boxes. Fruits were classified according to ripening stage and diameter, and evaluated for mechanical damage and external defects caused by harvesting procedures. The time required for the harvest operation was measured; damage to fruits (%) and weight loss (%), caused either in the field and/or during the harvesting process, were taken into consideration and related to the final quality of fruit after storage for 21 days. The same methodology was used all through the production and harvest cycle. The highest % fruit damage occurred during period II, a longer harvest time than the other two periods. Fruits not submitted to handling showed lower weight loss than handled fruits. Fruits harvested in period II and stored for 21 days showed higher losses due to mechanical injury

    Branch-and-lift algorithm for deterministic global optimization in nonlinear optimal control

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    This paper presents a branch-and-lift algorithm for solving optimal control problems with smooth nonlinear dynamics and potentially nonconvex objective and constraint functionals to guaranteed global optimality. This algorithm features a direct sequential method and builds upon a generic, spatial branch-and-bound algorithm. A new operation, called lifting, is introduced, which refines the control parameterization via a Gram-Schmidt orthogonalization process, while simultaneously eliminating control subregions that are either infeasible or that provably cannot contain any global optima. Conditions are given under which the image of the control parameterization error in the state space contracts exponentially as the parameterization order is increased, thereby making the lifting operation efficient. A computational technique based on ellipsoidal calculus is also developed that satisfies these conditions. The practical applicability of branch-and-lift is illustrated in a numerical example. © 2013 Springer Science+Business Media New York

    Para-infectious brain injury in COVID-19 persists at follow-up despite attenuated cytokine and autoantibody responses

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    To understand neurological complications of COVID-19 better both acutely and for recovery, we measured markers of brain injury, inflammatory mediators, and autoantibodies in 203 hospitalised participants; 111 with acute sera (1–11 days post-admission) and 92 convalescent sera (56 with COVID-19-associated neurological diagnoses). Here we show that compared to 60 uninfected controls, tTau, GFAP, NfL, and UCH-L1 are increased with COVID-19 infection at acute timepoints and NfL and GFAP are significantly higher in participants with neurological complications. Inflammatory mediators (IL-6, IL-12p40, HGF, M-CSF, CCL2, and IL-1RA) are associated with both altered consciousness and markers of brain injury. Autoantibodies are more common in COVID-19 than controls and some (including against MYL7, UCH-L1, and GRIN3B) are more frequent with altered consciousness. Additionally, convalescent participants with neurological complications show elevated GFAP and NfL, unrelated to attenuated systemic inflammatory mediators and to autoantibody responses. Overall, neurological complications of COVID-19 are associated with evidence of neuroglial injury in both acute and late disease and these correlate with dysregulated innate and adaptive immune responses acutely

    Complementary diastereoselectivity in the intermolecular addition of titanium and magnesium naphtholates to asymmetric lactaldehydes

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    Addition of 7-benzyloxy-4,5-dimethoxy-1-naphthol 3 as its triisopropoxytitanium naphtholate to (2R, 1′R or S )-2-(1′-ethoxyethoxy)propanal 4 afforded solely (1S, 2R, 1″R or S )-1-(7′-benzyloxy-4′,5′-dimethoxy-1′-hydroxy-2′-naphthyl)-2-(1″-ethoxyethoxy)propan-1-ol 5, being the erythro product arising from anti addition. Complementary reaction of the naphthol 3 as its bromomagnesium naphtholate with aldehyde 4 gave rise solely to the alternative (1R, 2R, 1″R or S ) diastereomer 6 . The naphthol 3 was prepared through the completely regioselective addition of 2-methoxyfuran 9 to 5-benzyloxy-3-methoxydehydrobenzene 8. This differentially protected bisalkoxybenzyne was conveniently prepared from vanillin

    A metal-mediated diastereoselective synthesis of precursors to the aphid pigment derivatives

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    Chiral compounds 16 and 17, precursors to the aphid insect pigment derivatives, have been prepared in good to high yield, with complete control of the diastereoselectivity at the newly-created chiral centre C-1, through the use of metal phenolates derived from naphthol 3
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