1,932 research outputs found

    A spherical lamellar grating interferometer for airborne astronomical observations of far infrared objects

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    A lamellar grating has been developed to be used for very far infrared observations on the airborne observatory. The design characteristics and performance during laboratory testing and initial observations of Jupiter at wavelengths between 50 and 500 microns are presented

    The ecology of a migratory moth, Autographa gamma L.

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    Although the Silver Y moth, Autographa gamma, is recognised as one of Britain's commonest migrant insects, little is known of its exact habitat requirements. This study attempts to define these requirements more clearly by assessing foodplant preferences and norms of reaction to environmental parameters under controlled conditions. The high level of polyphagy found in this species is produced by a female oviposition strategy which utilises many hostplants, high larval mobility and an ability to grow to maturity on a wide range of plant species. Selective pressures leading to polyphagy are discussed. Reduced growth rates and adult size were produced by different foodplants, larval density and temperature changes. The size changes are due to a subtle interaction between growth rates and the hormonal control of moulting. The susceptibility to size variation is the price paid for short generation times. Factors affecting adult fecundity were assessed adult food intake was found to be a major influence, providing a mechanical stimulus initiating rapid reproductive maturation, as well as energy which increases egg production. The most suitable habitat for a Silver Y would be a mesic enviromrent with a temperature of about 17.50C and abundant nectar. No Palaearctic or Mediterranean region provides these conditions all year round. As the Silver Y lacks a well-defined developmental arrest and trials showed a poor ability to overwinter in Britain, the moth must continuously track a shifting patchwork of favourable habitats. The spatia-temporal pattern of habi tat changes is discussed in relation to whether true migration (sensu Lack) or dispersal is an appropriate life history tactic. Flight records purporting to demons.trate true migration are shown to be compatible with a random flight direction model and it is concluded that insect species such as the Silver Y are best regarded as nomadic generalists fundamentally different from classic migrants like the Monarch butterfly

    EFFECTS OF HIGH AND LOW MANAGEMENT INTENSITY ON PROFITABILITY FOR THREE WATERMELON GENOTYPES

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    A replicated, small plot study on watermelon [Citrullus lanatus (Thunberg) Matsumura and Nakai] in 1997, 1999, and 2000 revealed that production management intensity affected yields and profitability of watermelon, in Oklahoma. Management intensity was based on a combination of cultural practices and levels of use of production methods. Low intensity management (LM) consisted of use of soil fertilization and weed control. High intensity management (HM) included the same weed control and fertilization as LM but also included use of plastic mulch, drip irrigation, insect pest control, and plant disease control. Cost and return analyses were based on the range of actual prices during the cropping season and the range of yields during the three years. Yields from the seedless triploid genotype 'Gem Dandy' consistently resulted in greater positive net revenue under HM than the diploid open pollinated 'Allsweet' or the hybrid diploid 'Sangria'. Under LM, yields from the seedless triploid also resulted in greater net revenues when conditions were favorable or lost less money than the open pollinated 'Allsweet' or the hybrid diploid 'Sangria' when conditions were unfavorable.Crop Production/Industries,

    Differential effects of nutritional folic acid deficiency and moderate hyperhomocysteinemia on aortic plaque formation and genome-wide DNA methylation in vascular tissue from ApoE-/- mice

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    Low folate intake is associated with vascular disease. Causality has been attributed to hyperhomocysteinemia. However, human intervention trials have failed to show the benefit of homocysteine-lowering therapies. Alternatively, low folate may promote vascular disease by deregulating DNA methylation. We investigated whether folate could alter DNA methylation and atherosclerosis in ApoE null mice. Mice were fed one of six diets (n = 20 per group) for 16 weeks. Basal diets were either control (C; 4% lard) or high fat (HF; 21% lard and cholesterol, 0.15%) with different B-vitamin compositions: (1) folic acid and B-vitamin replete, (2) folic acid deficient (−F), (3) folic acid, B6 and B12 deficient (−F−B). −F diets decreased plasma (up to 85%; P < 0.05), whole blood (up to 70%; P < 0.05), and liver folate (up to 65%; P < 0.05) and hepatic SAM/SAH (up to 80%; P < 0.05). −F−B diets reduced plasma (up to 76%; P < 0.05), whole blood (up to 72%; P < 0.05), and liver B12 (up to 39%; P < 0.05) and hepatic SAM/SAH (up to 90%; P < 0.05). −F increased homocysteine 2-fold, while −F−B increased homocysteine 3.6- and 6.8-fold in the C and HF groups (P < 0.05). Plaque formation was increased 2-fold (P < 0.0001) in mice fed a HF diet. Feeding a HF–F diet increased lesion formation by 17% (P < 0.05). There was no change in 5-methyldeoxycytidine in liver or vascular tissue (aorta, periadventitial tissue and heart). These data suggest that atherogenesis is not associated with genome-wide epigenetic changes in this animal model

    The effect of short-term kaempferol exposure on reactive oxygen levels and integrity of human (HL-60) leukaemic cells

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    AbstractFlavonoids may be a principal contributor to the cancer preventative activity of fruit- and vegetable-rich diets and there is interest in their use as dietary supplements. However, there is potential conflict between the cytoprotective and cytotoxic activities of flavonoids, and their efficacy as anti-cancer agents is unresolved. Here, the integrity and survival of HL-60 promyelocytic leukaemia cells following short-term (90 min) exposure to the dietary abundant flavonoid kaempferol (1–100 μM) is reported. Supplementation initially decreased reactive oxygen levels but, paradoxically, a dose-dependent increase in single-strand DNA breakage occurred. However, there was no increase in oxidised DNA purines or membrane damage. Following a 24-h recovery period in non-kaempferol supplemented media, DNA single-strand breakage had declined and kaempferol exposed and control cultures possessed similar reactive oxygen levels. A reduction in 3H-thymidine incorporation occurred with ≥10 μM kaempferol. One hundred micromolar kaempefrol increased the proportion of cells in G2-M phase, the proportion of cells with a sub-G1 DNA content and enhanced ‘active’ caspase-3 expression but only induced a loss of mitochondrial membrane potential within a minority of cells. The relevance of induced DNA damage within a non-overtly oxidatively stressed environment to the disease preventative and therapeutic use of kaempferol is discussed

    Archaeal abundance in post-mortem ruminal digesta may help predict methane emissions from beef cattle

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    The Rowett Institute of Nutrition and Health and SRUC are funded by the Rural and Environment Science and Analytical Services Division (RESAS) of the Scottish Government. The project was supported by DEFRA and DA funded Agricultural Greenhouse Gas Inventory Research Platform. Our thanks are due to the excellent support staff at the SRUC Beef Research Centre, Edinburgh, also to Graham Horgan of BioSS, Aberdeen, for conducting multivariate analysis.Peer reviewedPublisher PD
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