986 resultados para Locally Nilpotent Derivations


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Disproportionately little attention has been paid to the dry season trade-off between rice and (inland capture) fish production on the floodplains of Bangladesh, compared to the same trade-off during the flood season. As the rural economy grows increasingly dominated by dry-season irrigated rice production, and floodplain land and water come under ever-increasing pressure during the dry winter months, there is an urgent need to focus attention on these dry months that are so critical to the survival and propagation of the floodplain resident fish, and to the poor people that depend on these fish for their livelihood. This article examines three important dry-season natural resource constraints to floodplain livelihoods in Bangladesh, and finds a common factor at the heart of all three: rice cultivation on lands at low and very low elevations. The article articulates the system interlinkages that bind these constraints and the long-run trend towards irrigated rice cropping on lower-lying lands, and suggests a management approach based on locally tailored strategies to arrest this trend. Apart from its direct relevance to the floodplains of Bangladesh, which support more than 100 million people, these lessons have relevance for river floodplain systems elsewhere in the developing world, notably the Mekong Delta.

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A longitudinal study of sero-conversion of youngstock to the tick-borne pathogens Theileria parva, T mutans, Anaplasma marginale, Babesia bigemina and B. bovis was conducted over two years on smallholder dairy farms in Tanga region, Tanzania. There was evidence of maternal antibodies to all tick-borne pathogens in animals less than 18 weeks of age. Seroprevalence increased as expected with age in animals older than this but seroprevalence profiles underestimated the force of infection due to waning antibody levels between samplings. By the end of the 2-year study, less than 50% of study animals had seroconverted to each of the tick-borne pathogens investigated, consistent with the low levels of tick attachment observed on the study animals. Some associations between seroconversion to tick-borne pathogens, and counts of their known tick vectors on the animals, were identified as expected. However, some were not, suggesting that counts of some tick species may act as an index of rates of attachment of other vector species. Variation in acaricide treatment frequencies was not associated with variations in tick-borne pathogen seroprevalence suggesting that acaricides may be used more frequently than necessary on many farms. Most animals were zero-grazed, a management system associated with a significantly lower likelihood that animals seroconverted to any tick-borne pathogen exceptA. marginale. Seroprevalence varied locally with farm location (particularly for Babesia spp.) but was not well predicted by indices of ecological conditions. Our findings suggest that attempts to achieve a state of 'endemic stability' for tick-bome pathogens may be unreasonable on the smallholder dairy farms studied but reductions in the frequency of use of acaricides may be possible following prospective studies of effects on mortality and morbidity due to tick-bome pathogens. (c) 2005 Elsevier B.V. All rights reserved.

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Purpose - The purpose of this paper is to offer an exploratory case study comparing one Brazilian beef processor's relationships supplying two different distribution channels, an EU importer and an EU retail chain operating in Brazil. Design/methodology/approach - The paper begins with a short review of global value chains and the recent literature on trust. It gives the background to the Brazilian beef chain and presents data obtained through in-depth interviews, annual reports and direct observation with the Brazilian beef processor, the EU importer and the retailer. The interviews were conducted with individual firms, but the analysis places them in a chain context, identifying the links and relationships between the agents of the chains and aiming to describe each distribution channel. Findings - Executive chain governance exercised by the domestic retailer stimulates technical upgrading and transferring of best practices to local. suppliers. Consequently, this kind of relationship results in more trust within the global value chain. Practical implications - There are difficulties and challenges facing this Brazilian beef processor that are party related to the need to comply with increasingly complex and demanding food safety and food quality standards. There is still a gap between practices adopted for the export market and practices adopted locally. The strategies of transnational retailers in offering differentiated beef should be taken in account. Originality/value - The research outlines an interdisciplinary framework able to explain chain relationships and the kind of trust that emerges in relationships between EU importer/retail and a developing country supplier.

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None of the current surveillance streams monitoring the presence of scrapie in Great Britain provide a comprehensive and unbiased estimate of the prevalence of the disease at the holding level. Previous work to estimate the under-ascertainment adjusted prevalence of scrapie in Great Britain applied multiple-list capture-recapture methods. The enforcement of new control measures on scrapie-affected holdings in 2004 has stopped the overlapping between surveillance sources and, hence, the application of multiple-list capture-recapture models. Alternative methods, still under the capture-recapture methodology, relying on repeated entries in one single list have been suggested in these situations. In this article, we apply one-list capture-recapture approaches to data held on the Scrapie Notifications Database to estimate the undetected population of scrapie-affected holdings with clinical disease in Great Britain for the years 2002, 2003, and 2004. For doing so, we develop a new diagnostic tool for indication of heterogeneity as well as a new understanding of the Zelterman and Chao's lower bound estimators to account for potential unobserved heterogeneity. We demonstrate that the Zelterman estimator can be viewed as a maximum likelihood estimator for a special, locally truncated Poisson likelihood equivalent to a binomial likelihood. This understanding allows the extension of the Zelterman approach by means of logistic regression to include observed heterogeneity in the form of covariates-in case studied here, the holding size and country of origin. Our results confirm the presence of substantial unobserved heterogeneity supporting the application of our two estimators. The total scrapie-affected holding population in Great Britain is around 300 holdings per year. None of the covariates appear to inform the model significantly.

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Context: Pregnant tissues express corticotropin-releasing factor (CRF), a peptide modulating fetal and placental ACTH and cortisol secretion. These actions are modulated by the locally expressed CRF-binding protein (CRF-BP). Objective: The objective of the study was to determine whether CRF, CRF-BP, ACTH, and cortisol concentrations change in amniotic fluid and umbilical cord plasma in the presence of intraamniotic infection/inflammation (IAI) in women with spontaneous labor at term. Design: This was a cross-sectional study. Setting: The study was conducted at a tertiary referral center for obstetric care. Patients: Patients included women in active labor at term with (n = 39) and without (controls; n = 78) IAI. Main Outcome Measures: Amniotic fluid and umbilical cord plasma concentrations of CRF, CRF-BP, ACTH, and cortisol measured by RIA and immunoradiometric assays were measured. Results: In patients with IAI, amniotic fluid CRF (0.97 +/- 0.18 ng/ml) and CRF-BP (33.06 +/- 5.54 nmol/liter) concentrations were significantly (P < 0.001) higher than in controls (CRF: 0.32 +/- 0.04 ng/ml; CRF-BP: 14.69 +/- 2.79 ml). The umbilical cord plasma CRF and CRF-BP concentrations were significantly (P < 0.001 for all) higher in women with IAI than in controls (CRF: 2.96 +/- 0.35 ng/ml vs. 0.38 +/- 0.18 ng/ml; CRF-BP: 152.12 +/- 5.94 nmol/liter vs. 106.9 +/- 5.97 nmol/liter). In contrast, amniotic fluid and umbilical cord plasma ACTH and cortisol concentrations did not differ between groups. Conclusions: Amniotic fluid and umbilical cord plasma CRF and CRF-BP concentrations are increased in women with spontaneous labor at term and IAI. CRF-BP may modulate CRF actions on ACTH and cortisol secretion, playing a pivotal role in limiting the inflammatory process and thus avoiding an overactivation of the fetal/placental hypothalamus-pituitary-adrenal axis at birth.

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Forecasting the effects of stressors on the dynamics of natural populations requires assessment of the joint effects of a stressor and population density on the population response. The effects can be depicted as a contour map in which the population response, here assessed by Population growth rate, varies with stress and density in the same way that the height of land above sea level varies with latitude and longitude. We present the first complete map of this type using as our model Folsomia candida exposed to five different concentrations of the widespread anthelmintic veterinary medicine ivermectin in replicated microcosm experiments lasting 49 days. The concentrations of ivermectin in yeast were 0.0, 6.8 28.83 66.4 and 210.0 mg/L wet weight. Increasing density and chemical concentration both significantly reduced the population growth rate of Folsomia candida, in part through effects on food consumption and fecundity. The interaction between density and ivermectin concentration was "less-than-additive," implying that at high density populations were able to compensate for the effects of the chemical. This result demonstrates that regulatory protocols carried out at low density (as in most past experiments) may seriously overestimate effects in the field, where densities are locally high and populations are resource limited (e.g., in feces of livestock treated with ivermectin).

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Aluminium salts are used as the active antiperspirant agent in underarm cosmetics, but the effects of widespread, long term and increasing use remain unknown, especially in relation to the breast, which is a local area of application. Clinical studies showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast together with reports of genomic instability in outer quadrants of the breast provide supporting evidence for a role for locally applied cosmetic chemicals in the development of breast cancer. Aluminium is known to have a genotoxic profile, capable of causing both DNA alterations and epigenetic effects, and this would be consistent with a potential role in breast cancer if such effects occurred in breast cells. Oestrogen is a well established influence in breast cancer and its action, dependent on intracellular receptors which function as ligand-activated zinc finger transcription factors, suggests one possible point of interference from aluminium. Results reported here demonstrate that aluminium in the form of aluminium chloride or aluminium chlorhydrate can interfere with the function of oestrogen receptors of MCF7 human breast cancer cells both in terms of ligand binding and in terms of oestrogen-regulated reporter gene expression. This adds aluminium to the increasing list of metals capable of interfering with oestrogen action and termed metal I oestrogens. Further studies are now needed to identify the molecular basis of this action, the longer term effects of aluminium exposure and whether aluminium can cause aberrations to other signalling pathways in breast cells. Given the wide exposure of the human population to antiperspirants, it will be important to establish dermal absorption in the local area of the breast and whether long term low level absorption could play a role in the increasing incidence of breast cancer. (c) 2005 Elsevier Inc. All rights reserved.

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The aim of this study was to analyze the function and expression of tachykinins, tachykinin receptors, and neprilysin (NEP) in the mouse uterus. A previous study showed that the uterotonic effects of substance P (SP), neurokinin A (NKA), and neurokinin B (NKB) in estrogen-treated mice were mainly mediated by the tachykinin NK, receptor. In the present work, further contractility studies were undertaken to determine the nature of the receptors mediating responses to tachykinins in uteri of late pregnant mice. Endpoint and real-time quantitative RTPCR were used to analyze the expression of the genes that encode the tachykinins SP/NKA, NKB, and hemokinin-1 (HK-1) (Tac1, Tac2, and Tac4); and the genes that encode tachykinin NK1 (Tacr1), NK2 (Tacr2), and NK3 (Tacr3) receptors in uteri from pregnant and nonpregnant mice. The data show that the mRNAs of tachykinins (particularly NKB and HK-1), tachykinin receptors, and NEP are locally expressed in the mouse uterus, and their expression changes during the estrous cycle and during pregnancy. The tachykinin INK, receptor is the predominant tachykinin receptor in the nonpregnant and early pregnant mouse and may mediate tachykinin-induced uterine contractions in the nonpregnant mouse. The tachykinin NK, receptor is predominant in the late pregnant mouse and is the main receptor mediating uterotonic responses to tachykinins at late pregnancy. The tachykinin NK, receptor is expressed in considerable amounts only in uteri from nonpregnant diestrous animals, and its physiological significance remains to be clarified.

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Development of external genitalia in mammalian embryos requires tight coordination of a complex series of morphogenetic events involving outgrowth, proximodistal and dorsoventral patterning, and epithelial tubulogenesis. Hypospadias is a congenital defect of the external genitalia that results from failure of urethral tube closure. Although this is the second most common birth defect in humans, affecting one in every 250 children, the molecular mechanisms that regulate morphogenesis of the mammalian urethra are poorly understood. We report that mice lacking the IIIb isoform of fibroblast growth factor receptor 2 (Fgfr2) exhibit severe hypospadias. Urethral signaling regions, as indicated by Shh and Fgf8 expression, are established in Fgfr2-IIIb null mice; however, cell proliferation arrests prematurely and maturation of the urethral epithelium is disrupted. Fgfr2-IIIb(-/-) mutants fail to maintain the progenitor cell population required for uroepithelial renewal during tubular morphogenesis. In addition, we show that antagonism of the androgen receptor (AR) leads to loss of Fgfr2-IIIb and Fgf10 expression in the urethra, and an associated hypospadias phenotype, suggesting that these genes are downstream targets of AR during external genital development. Genitourinary defects resulting from disruption of AR activity, by either genetic or environmental factors, may therefore involve negative regulation of the Fgfr2 pathway. This represents the first example of how the developing genitourinary system integrates cues from systemically circulating steroid hormones with a locally expressed growth factor pathway.

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It is contended that competitiveness is better understood as a discourse rather than as a characteristic that is supposedly possessed. The discourse of competitiveness derives its legitimacy from the enterprise culture that came to dominance during the 1980s. Current popularized theories of competitiveness are constituent parts of this broader discourse, which has had significant material implications for the UK construction sector. The dominant discourse of competitiveness amongst contracting firms is shaped by the need to achieve structural flexibility to cope with fluctuations in demand. Fashionable espoused improvement recipes such as total quality management, business process re-engineering, and lean construction legitimize and reinforce the material manifestations of the enterprise culture. In consequence, the UK industry is characterized by a plethora of hollowed-out firms that have failed to invest in their human capital. While the adopted model may be rational for individual firms, the systemic effect across the sector as a whole equates to a form of anorexia. However, the discourse of competitiveness is by no means monolithic and continues to be contested locally. There have also been numerous counter-discourses that have been mobilized in response to the undesirable externalities of unbridled enterprise. Currently, important counter-discourses promote the ideas of sustainability and corporate social responsibility.

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The UK government is currently attempting to encourage consumers to buy more locally produced food. It is hoped that this will provide economic, environmental and social benefits to local areas, leading to more sustainable patterns of consumption. This qualitative study looks at the views and behaviour of consumers towards local foods with a particular focus on the barriers that prevent greater uptake of local produce. In total, four focus groups (n = 33) were conducted. Content analysis identified six relevant themes in relation to local, national and imported foods. These were cost, lifestyle, food quality, consumer ethnocentrism, choice and farmers. Overall, although participants reported buying few local products currently, there was widespread enthusiasm across socio-economic groups for local foods, with participants perceiving them as being of a higher quality than imported foods. They also generally endorsed the idea of supporting local farmers and their own national economy. The main barriers preventing participants from buying more local products were price and inconvenience. The results are discussed in relation to developing future strategies for encouraging people to buy more local food products. (c) 2007 Elsevier Ltd. All rights reserved.