991 resultados para 1471


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Over many millions of years of independent evolution, placental, marsupial and monotreme mammals have diverged conspicuously in physiology, life history and reproductive ecology. The differences in life histories are particularly striking. Compared with placentals, marsupials exhibit shorter pregnancy, smaller size of offspring at birth and longer period of lactation in the pouch. Monotremes also exhibit short pregnancy, but incubate embryos in eggs, followed by a long period of post-hatching lactation. Using a large sample of mammalian species, we show that, remarkably, despite their very different life histories, the scaling of production rates is statistically indistinguishable across mammalian lineages. Apparently all mammals are subject to the same fundamental metabolic constraints on productivity, because they share similar body designs, vascular systems and costs of producing new tissue.

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Dhaka cheese is a semihard artisanal variety originating from Bangladesh where manual curd kneading is a normal stage in its manufacture. Dhaka cheeses were produced with different degrees of curd kneading to quantify the curd manipulation process in terms of pressure and to standardise the length of operation. The effect of manipulation on the composition, rheology, texture and microstructure of fresh cheese was also studied. Manipulation had significant effects (P < 0.05–0.001) on most of the parameters studied. One minute of curd manipulation was found to be sufficient for Dhaka cheesemaking

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This article examines the intertextual relationship between Marguerite Duras' pro-colonialist, propagandist text, L'Empire français (1943), and her seemingly anti-colonialist novel, Un barrage contre le Pacifique (1950). It explores both the transformative and the emulative uses to which descriptive elements, borrowed from the precursor text, are put in the novel's depictions of colonial Indochina. Going against prevalent critical readings of Barrage, the article highlights the ambivalent and ultimately only partial nature of Duras' apparent ideological volte-face

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Skim milk was concentrated by reverse osmosis (RO), nanofiltration (NF) and ultrafiltration (UF) and the retentates were spray-dried. The resulting powders were reconstituted to 25% TS and sterilised to evaluate their heat stability. Reverse osmosis led to maximum retention of calcium, a fall in pH for its retentate and its reconstituted powder. All RO powders produced a weak gel on heating. Some calcium was lost during NF and a greater amount during UF. Their resulting reconstituted powders had a higher pH than those produced by RO. Powders produced by UF showed poor heat stability. Only one powder produced by NF showed good heat stability. This could be improved by addition of stabilisers at appropriate addition rates.

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In a short communication in this issue (Manser et al. 2012), Christopher Miller’s group at the Institute of Psychiatry, King’s College London present an elegant and convincing set of experiments using molecular techniques to show that a brain-enriched membrane-associated protein kinase, lemur tyrosine kinase-2 (LMTK2), is directly phosphorylated by the cyclin-dependent kinase-5/p35 and this event is sufficient for LMTK2 to phosphorylate an abundant protein phosphatase, PP1C. LMTK2 has been little studied to date and, despite its name, is a kinase which phosphorylates serine or threonine residues of protein substrates. The paper adds to the evidence that this enzyme is a potentially important mediator positioned to integrate a number of intracellular signalling pathways relevant to neurodegeneration.

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Background: Seed storage proteins are a major source of dietary protein, and the content of such proteins determines both the quantity and quality of crop yield. Significantly, examination of the protein content in the seeds of crop plants shows a distinct difference between monocots and dicots. Thus, it is expected that there are different evolutionary patterns in the genes underlying protein synthesis in the seeds of these two groups of plants. Results: Gene duplication, evolutionary rate and positive selection of a major gene family of seed storage proteins (the 11S globulin genes), were compared in dicots and monocots. The results, obtained from five species in each group, show more gene duplications, a higher evolutionary rate and positive selections of this gene family in dicots, which are rich in 11S globulins, but not in the monocots. Conclusion: Our findings provide evidence to support the suggestion that gene duplication and an accelerated evolutionary rate may be associated with higher protein synthesis in dicots as compared to monocots.

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This paper probes the public dimensions of the work of the twentieth-century Scottish poet W. S. Graham. It draws upon the public contacts and contexts that Graham's lyrics structure and reconfigure, in texts that have appeared to critics to demonstrate the poet's textual aloneness, his intellectual and geographical banishment. Repeatedly addressing his St Ives community of artists and writers, lovers and companions, Graham's work sets up strategic routes through a succession of publicly-minded verbal engagements. Refusing to allow one passively to listen in to the poet's isolation, the lyrics invite, rebuff, tease, avoid, dally with, and proposition audiences and interlocutors. Graham's poetry speaks from within and without tradition, location and heritage, subtly attuning readers to the politics of its handling of national allegiance, identity, class and patronage.

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We examine the strategies interwar working-class British households used to “smooth” consumption over time and guard against negative contingencies such as illness, unemployment, and death. Newly discovered returns from the U.K. Ministry of Labour's 1937/38 Household Expenditure Survey are used to fully categorize expenditure smoothing via nineteen credit/savings vehicles. We find that households made extensive use of expenditure-smoothing devices. Families' reliance on expenditure-smoothing is shown to be inversely related to household income, while households also used these mechanisms more intensively during expenditure crisis phases of the family life cycle, especially the years immediately after new household formation.

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Background Riluzole is a neuroprotective drug used in the treatment of motor neurone disease. Recent evidence suggests that riluzole can up-regulate the expression and activity of the astrocyte glutamate transporter, GLT-1. Given that regulation of glutamate transport is predicted to be neuroprotective in Parkinson's disease, we tested the effect of riluzole in parkinsonian rats which had received a unilateral 6-hydroxydopamine injection into the median forebrain bundle. Results Rats were treated with intraperitoneal riluzole (4 mg/kg or 8 mg/kg), 1 hour before the lesion then once daily for seven days. Riluzole produced a modest but significant attenuation of dopamine neurone degeneration, assessed by suppression of amphetamine-induced rotations, preservation of tyrosine hydroxylase positive neuronal cell bodies in the substantia nigra pars compacta and attenuation of striatal tyrosine hydroxylase protein loss. Seven days after 6-hydroxydopamine lesion, reactive astrocytosis was observed in the striatum, as determined by increases in expression of glial fibrillary acidic protein, however the glutamate transporter, GLT-1, which is also expressed in astrocytes was not regulated by the lesion. Conclusions The results confirm that riluzole is a neuroprotective agent in a rodent model of parkinson’s disease. Riluzole administration did not regulate GLT-1 levels but significantly reduced GFAP levels, in the lesioned striatum. Riluzole suppression of reactive astrocytosis is an intriguing finding which might contribute to the neuroprotective effects of this drug.

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