1,473 research outputs found

    A study of abundance of planktonic organisms in Lekan-Are Lake, Ogun State, Nigeria

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    A study of the plankton abundance in the shore, surface and bottom of Lake Lekan-Are Abeokuta, Ogun State, Nigeria was carried out between January 2007 and August 2008 at three stations along the entire stretch of the lake. The numerical abundance of the plankton in this lake was investigated. There were marked seasonal variations in the zooplankton and phytoplankton of the lake. Four major groups of phytoplankton were identified Baccilariophyceae (diatoms), Chlorophyceae (green algae) and Cyanophyceae (blue green). The green algae dominated the phytoplankton constituting 63.3% in the surface and 54.8% in the bottom zone of the lake. The phytoplankton density was at its peak in sunny months of January to early June that coincided with the period of high temperature. The three major groups of zooplankton observed in the lake were Cladocera, Copepoda and Rotifera. The Copepoda dominated the three habitats 83.37% (shore), 82.73% (surface) and 80.26% (bottom). Copepoda also dominated at the three stations of the lake. The  seasonality of zooplankton followed a similar pattern with that of the phytoplankton reaching a peak between February and May.Keywords: Numerical abundance, plankton Lekan Area, Nigeri

    Safety of benzodiazepines and opioids in interstitial lung disease: A national prospective study

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    Copyright ©ERS 2018 Safety concerns are a barrier to prescribing benzodiazepines (BDZs) and opioids in interstitial lung disease (ILD). We therefore examined the association of BDZs and opioids on risk of admission to hospital and death. We conducted a population-based longitudinal cohort study of fibrotic ILD patients starting long-term oxygen therapy in Sweden between October 2005 and December 2014. Effects of BDZs and opioids on rates of admission to hospital and mortality were analysed using Fine-Gray and Cox regression while adjusting for potential confounders. We included 1603 patients (61% females). BDZs were used by 196 (12%) patients and opioids were used by 254 (15%) patients. There was no association between BDZs and increased admission. Treatment with high- versus low-dose BDZs was associated with increased mortality (subdistribution hazard ratio (SHR) 1.46, 95% CI 1.08-1.98 versus 1.13, 95% CI 0.92-1.38). Opioids showed no association with increased admission. Neither low-dose opioids (30 mg·day −1 oral morphine equivalent) (SHR 1.18, 95% CI 0.96-1.45) nor high-dose opioids (>30 mg·day −1 oral morphine equivalent) (SHR 1.11, 95% CI 0.89-1.39) showed association with increased mortality. This first ever study to examine associations between BDZ and opioid use and harm in ILD supports the use of opioids and low-dose BDZs in severely ill patients with respiratory compromise

    Techno-economic packaging of palm wine preservation and bottling technology for entrepreneurs

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    The study was carried out to investigate the economic viability of setting up a small scale palm wine bottling factory with a view to providing investment data to guide entrepreneurs in making investment decisions. The economic evaluation was based on a factory capacity of 750,000 bottles (60cl) per annum with production commencing in year one at 75% capacity utilization. Production cost estimate varies between N37.85/bottle (60cl) in the first year and N35.37/bottle (60cl) in the fifth year. The annual netprofits are N8, 460,430.00 and N12, 025,710.00 in years one and five respectively. Projected cash flow is positive in year one i.e. N5,329,960.00 while the projected balance sheet shows that the net worth of theproject is N19,904,010.00 in year one and N41,887,370.00 in year five. Payback period, discounted payback period and profitability index are 1.4 years, 3.3 years and 1.5 respectively. The breakeven point in year one is 48.1% or a breakeven sales volume of N16, 236,312.35.00.  The Return on Investment (ROI) and Return on Equity (ROE) in year one are 57.5% and 86.1% respectively. Capital Turnover Ratio (CTR) varies between 2.3 and 2.9 within the first five years. Internal Rate of Return (IRR) is above 45%. The Net Present Value (NPV) at 25% is estimated at N3, 143,100.00. The Debt Service Coverage Ratio (DSCR) increases gradually from 1.33 to 2.75 between the first and the fifth year

    Voltage-gated sodium channels as targets for pyrethroid insecticides

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    The pyrethroid insecticides are a very successful group of compounds that have been used extensively for the control of arthropod pests of agricultural crops and vectors of animal and human disease. Unfortunately, this has led to the development of resistance to the compounds in many species. The mode of action of pyrethroids is known to be via interactions with the voltage-gated sodium channel. Understanding how binding to the channel is affected by amino acid substitutions that give rise to resistance has helped to elucidate the mode of action of the compounds and the molecular basis of their selectivity for insects vs mammals and between insects and other arthropods. Modelling of the channel/pyrethroid interactions, coupled with the ability to express mutant channels in oocytes and study function, has led to knowledge of both how the channels function and potentially how to design novel insecticides with greater species selectivity

    Dynamics of Collective Decoherence and Thermalization

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    We analyze the dynamics of N interacting spins (quantum register) collectively coupled to a thermal environment. Each spin experiences the same environment interaction, consisting of an energy conserving and an energy exchange part. We find the decay rates of the reduced density matrix elements in the energy basis. We show that if the spins do not interact among each other, then the fastest decay rates of off-diagonal matrix elements induced by the energy conserving interaction is of order N^2, while that one induced by the energy exchange interaction is of the order N only. Moreover, the diagonal matrix elements approach their limiting values at a rate independent of N. For a general spin system the decay rates depend in a rather complicated (but explicit) way on the size N and the interaction between the spins. Our method is based on a dynamical quantum resonance theory valid for small, fixed values of the couplings. We do not make Markov-, Born- or weak coupling (van Hove) approximations

    Quantum gates with neutral atoms: Controlling collisional interactions in time dependent traps

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    We theoretically study specific schemes for performing a fundamental two-qubit quantum gate via controlled atomic collisions by switching microscopic potentials. In particular we calculate the fidelity of a gate operation for a configuration where a potential barrier between two atoms is instantaneously removed and restored after a certain time. Possible implementations could be based on microtraps created by magnetic and electric fields, or potentials induced by laser light.Comment: 10 pages, 3 figure

    Glucocorticoids, master modulators of the thymic catecholaminergic system?

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    There is evidence that the major mediators of stress, i.e., catecholamines and glucocorticoids, play an important role in modulating thymopoiesis and consequently immune responses. Furthermore, there are data suggesting that glucocorticoids influence catecholamine action. Therefore, to assess the putative relevance of glucocorticoid-catecholamine interplay in the modulation of thymopoiesis we analyzed thymocyte differentiation/maturation in non-adrenalectomized and andrenalectomized rats subjected to treatment with propranolol (0.4 mg.100 g body weight(-1).day(-1)) for 4 days. The effects of beta-adrenoceptor blockade on thymopoiesis in non-adrenalectomized rats differed not only quantitatively but also qualitatively from those in adrenalectomized rats. In adrenalectomized rats, besides a more efficient thymopoiesis [judged by a more pronounced increase in the relative proportion of the most mature single-positive TCR alpha beta(high) thymocytes as revealed by two-way ANOVA; for CD4(+)CD8(-)F (1,20) = 10.92, P lt 0.01; for CD4(-)CD8(+)F (1,20) = 7.47, P lt 0.05], a skewed thymocyte maturation towards the CD4(-)CD8(+) phenotype, and consequently a diminished CD4(+)CD8(-)/CD4(-)CD8(+) mature TCR alpha beta(high) thymocyte ratio (3.41 +/- 0.21 in non-adrenalectomized rats vs 2.90 +/- 0.31 in adrenalectomized rats, P lt 0.05) were found. Therefore, we assumed that catecholaminergic modulation of thymopoiesis exhibits a substantial degree of glucocorticoid-dependent plasticity. Given that glucocorticoids, apart from catecholamine synthesis, influence adrenoceptor expression, we also hypothesized that the lack of adrenal glucocorticoids affected not only beta-adrenoceptor- but also alpha-adrenoceptor-mediated modulation of thymopoiesis

    P450 gene duplication and divergence led to the evolution of dual novel functions and insecticide cross-resistance in the brown planthopper Nilaparvata lugens

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    This is the final version. Available on open access from Public Library of Science via the DOI in this recordData Availability: All relevant data are within the manuscript and its Supporting Information files.The sustainable control of many highly damaging insect crop pests and disease vectors is threatened by the evolution of insecticide resistance. As a consequence, strategies have been developed that aim to prevent or delay resistance development by rotating or mixing insecticides with different modes of action (MoA). However, these approaches can be compromised by the emergence of mechanisms that confer cross-resistance to insecticides with different MoA. Despite the applied importance of cross-resistance, its evolutionary underpinnings remain poorly understood. Here we reveal how a single gene evolved the capacity to detoxify two structurally unrelated insecticides with different MoA. Using transgenic approaches we demonstrate that a specific variant of the cytochrome P450 CYP6ER1, previously shown to confer resistance to the neonicotinoid imidacloprid in the brown planthopper, N. lugens, also confers cross-resistance to the phenylpyrazole ethiprole. CYP6ER1 is duplicated in resistant strains, and we show that while the acquisition of mutations in two encoded substrate recognition sites (SRS) of one of the parologs led to resistance to imidacloprid, a different set of mutations, outside of known SRS, are primarily responsible for resistance to ethiprole. Epistatic interactions between these mutations and their genetic background suggest that the evolution of dual resistance from the same gene copy involved functional trade-offs in respect to CYP6ER1 catalytic activity for ethiprole versus imidacloprid. Surprisingly, the mutations leading to ethiprole and imidacloprid resistance do not confer the ability to detoxify the insecticide fipronil, another phenylpyrazole with close structural similarity to ethiprole. Taken together, these findings reveal how gene duplication and divergence can lead to the evolution of multiple novel functions from a single gene. From an applied perspective they also demonstrate how cross-resistance to structurally unrelated insecticides can evolve, and illustrate the difficulty in predicting cross-resistance profiles mediated by metabolic mechanisms.European Union Horizon 2020Medical Research Council (MRC

    Novel mutations in the voltage-gated sodium channel of pyrethroid-resistant Varroa destructor populations from the Southeastern USA

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    The parasitic mite Varroa destructor has a significant worldwide impact on bee colony health. In the absence of control measures, parasitized colonies invariably collapse within 3 years. The synthetic pyrethroids tau-fluvalinate and flumethrin have proven very effective at managing this mite within apiaries, but intensive control programs based mainly on one active ingredient have led to many reports of pyrethroid resistance. In Europe, a modification of leucine to valine at position 925 (L925V) of the V. destructor voltage-gated sodium channel was correlated with resistance, the mutation being found at high frequency exclusively in hives with a recent history of pyrethroid treatment. Here, we identify two novel mutations, L925M and L925I, in tau-fluvalinate resistant V. destructor collected at seven sites across Florida and Georgia in the Southeastern region of the USA. Using a multiplexed TaqMan® allelic discrimination assay, these mutations were found to be present in 98% of the mites surviving tau-fluvalinate treatment. The mutations were also found in 45% of the non-treated mites, suggesting a high potential for resistance evolution if selection pressure is applied. The results from a more extensive monitoring programme, using the Taqman® assay described here, would clearly help beekeepers with their decision making as to when to include or exclude pyrethroid control products and thereby facilitate more effective mite management programmes
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