5,026 research outputs found

    Effects of pH on Growth of Salvinia molesta Mitchell

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    Growth of giant salvinia ( Salvinia molesta Mitchell) under different pH regimes was examined at the Lewisville Aquatic Ecosystem Research Facility (LAERF) in Lewisville, Texas.(PDF has 5 pages.

    Farmers’ Behaviour towards Utilisation of Jatropha Curcas for Environmental Mitigation in Oyo State, Nigeria

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    The dysfunctional environment caused by soil erosion, wind erosion, deforestation, desertification, issues of flood was due to the effect of greenhouse gases emanating as a result of various activities of man and industries. Consequently, this has prompted the exploitation of Jatropha curcas for mitigating the environment. Therefore, this study was carried out to examine farmers’ behaviour towards utilisation of Jatropha curcas for mitigation of environment in the study area. A multistage sampling procedure was used in selecting 120 farmers from 217 trained Jatropha farmers across Ido and Akinyele Local Government Areas in Oyo State. The data was analysed using frequencies, percentages, mean scores, and pearson product moment correlation. The result for the study showed that majority of the respondents had mean age of 44.4± 10.8 with majority also being male (66.7%) and formal education (91.7%). The result revealed that there was significant relationship between socio-economic characteristics of the respondents and farmers’ behaviour towards utilization of Jatropha curcas for environmental mitigation. There was correlation between farmers’ awareness on cultivation of Jatropha curcas and their behavior towards utilisation of Jatropha curcas for environmental mitigation (r = 0.399**, p < 0.05). The respondents’ attitude was significantly related to their behavior towards utilization of Jatropha curcas for environmental mitigation (r = - 0.182*, p < 0.05). The study showed that awareness and attitude of farmers strongly influence their behaviour towards utilization of Jatropha curcas for environmental mitigation. The implication of this study is to ensure that the environment becomes free of hazards and degradation which affect survival of the ecosystem and biodiversity. Hence, government should join in the advocacy to open continuous channels of communication on the importance of Jatropha to motivate farmers to having right behaviour towards utilization of Jatropha curcas as a measure to mitigate the environment. Keywords: Behaviour, utilisation, Jatropha curcas, farmers, mitigation, environmen

    Approaching the Ground State of Frustrated A-site Spinels: A Combined Magnetization and Polarized Neutron Scattering Study

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    We re-investigate the magnetically frustrated, {\it diamond-lattice-antiferromagnet} spinels FeAl2_2O4_4 and MnAl2_2O4_4 using magnetization measurements and diffuse scattering of polarized neutrons. In FeAl2_2O4_4, macroscopic measurements evidence a "cusp" in zero field-cooled susceptibility around 13~K. Dynamic magnetic susceptibility and {\it memory effect} experiments provide results that do not conform with a canonical spin-glass scenario in this material. Through polarized neutron scattering studies, absence of long-range magnetic order down to 4~K is confirmed in FeAl2_2O4_4. By modeling the powder averaged differential magnetic neutron scattering cross-section, we estimate that the spin-spin correlations in this compound extend up to the third nearest-neighbour shell. The estimated value of the Land\'{e} gg factor points towards orbital contributions from Fe2+^{2+}. This is also supported by a Curie-Weiss analysis of the magnetic susceptibility. MnAl2_2O4_4, on the contrary, undergoes a magnetic phase transition into a long-range ordered state below \approx 40~K, which is confirmed by macroscopic measurements and polarized neutron diffraction. However, the polarized neutron studies reveal the existence of prominent spin-fluctuations co-existing with long-range antiferromagnetic order. The magnetic diffuse intensity suggests a similar short range order as in FeAl2_2O4_4. Results of the present work supports the importance of spin-spin correlations in understanding magnetic response of frustrated magnets like AA-site spinels which have predominant short-range spin correlations reminiscent of the "spin liquid" state.Comment: 10 pages, 10 figures, double-column, accepted in Phys. Rev. B, 201

    Exercise training for chronic heart failure (ExTraMATCH II): individual participant data meta-analysis of randomised controlled trials

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    This is the author accepted manuscript. The final version is available from NIHR Journals Library via the DOI in this record.Background: Current national and international guidelines on the management of heart failure (HF) recommend exercise-based cardiac rehabilitation (ExCR), but do not differentiate this recommendation according to patient subgroups. Objective(s): (1) to obtain definitive estimates of the impact of ExCR interventions versus control (no exercise intervention) on mortality, hospitalisation, exercise capacity, and health-related quality of life (HRQoL) in HF patients; (2) to determine the differential (subgroup) effects of ExCR in HF patients according to their age, gender, ejection fraction, aetiology, New York Heart Association (NYHA) class, and baseline exercise capacity; (3) to assess whether the change in exercise capacity mediates for the impact of the ExCR on final outcomes (mortality, hospitalisation, and HRQoL) and is an acceptable surrogate endpoint. Design: Individual participant data (IPD) meta-analysis Setting: An international literature review Participants: HF patients in randomised controlled trials (RCTs) of ExCR Interventions: ExCR for at least 3 weeks compared with no exercise control with 6 months follow-up Main outcome measures: mortality (all cause and HF-specific), hospitalisation (all-cause & HF-specific), exercise capacity, and HRQoL Data sources: Individual participant data from eligible RCTs 3 Review methods: RCTs from ExTraMATCH IPD meta-analysis and 2014 Cochrane systematic review of ExCR Results: Out of the 23 eligible RCTs (4,398 patients), 19 RCTs (3,990 patients) contributed data to this IPD meta-analysis. There was a wide variation in exercise programme prescriptions across included studies. Compared with control, there was no statistically significant difference in pooled time to event estimates in favour of ExCR although confidence intervals were wide: all-cause mortality: hazard ratio (HR) 0.83 (95% confidence interval (CI): 0.67 to 1.04), HF-related mortality: HR 0.84 (95% CI: 0.49 to 1.46), all-cause hospitalisation: HR 0.90 (95% CI: 0.76 to 1.06), and HF-related hospitalisation: HR 0.98 (95% CI: 0.72 to 1.35). There was a statistically significant difference in favour of ExCR for exercise capacity and HRQoL. Compared to control, at 12-months follow-up, improvements were seen in the six-minute walk test (6MWT) (mean: 21.0 metres, 95% CI: 1.57 to 40.4, and Minnesota Living with HF Questionnaire score (mean: -5.94, 95% CI: -1.0 to -10.9, lower scores indicate improved HRQoL). No strong evidence for differential intervention effects across patient characteristics was found for any outcomes. Moderate to good levels of correlation (R2 trial>50% & ρ>0.50) between peak oxygen uptake (VO2peak) or 6MWT with mortality and HRQoL were seen. Estimated surrogate threshold effect (STE) was an increase of 1.6 to 4.6 ml/kg/min for VO2peak. Limitations: Lack consistency in how included RCTs defined and collected the outcomes; we were unable to obtain IPD from all includable trials for all outcomes; and we did not seek patient level on exercise adherence. . Conclusions: In comparison to no exercise control, participation in ExCR improves the exercise and HRQoL in HF patients but appears to have no effect on their mortality or hospitalisation. No strong evidence was found of differential intervention effects of ExCR across patient characteristics. VO2peak and 6MWT may be suitable surrogate endpoints for the treatment effect of ExCR on mortality and HRQoL in HF.NIHR Health Technology Assessment programm

    Dietary interventions for maintaining cognitive function in cognitively healthy people in mid life

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    This is the protocol for a review and there is no abstract. The objectives are as follows: In this review we will set out to evaluate the effects of dietary interventions for maintaining cognitive function in cognitively healthy people in mid-life and preventing cognitive decline in late life

    AKAP79 enables calcineurin to directly suppress protein kinase A activity

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    Interplay between the second messengers cAMP and Ca2+ is a hallmark of dynamic cellular processes. A common motif is the opposition of the Ca2+-sensitive phosphatase calcineurin and the major cAMP receptor, protein kinase A (PKA). Calcineurin dephosphorylates sites primed by PKA to bring about changes including synaptic long-term depression (LTD). AKAP79 supports signaling of this type by anchoring PKA and calcineurin in tandem. In this study, we discovered that AKAP79 increases the rate of calcineurin dephosphorylation of type II PKA regulatory subunits by an order of magnitude. Fluorescent PKA activity reporter assays, supported by kinetic modeling, show how AKAP79-enhanced calcineurin activity enables suppression of PKA without altering cAMP levels by increasing PKA catalytic subunit capture rate. Experiments with hippocampal neurons indicate that this mechanism contributes towards LTD. This non-canonical mode of PKA regulation may underlie many other cellular processes

    Validation of Exercise Capacity as a Surrogate Endpoint in Exercise-Based Rehabilitation for Heart Failure: A Meta-Analysis of Randomized Controlled Trials

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    This is the final version. Available on open access from Elsevier via the DOI in this recordObjectives: This study sought to validate exercise capacity (EC) as a surrogate for mortality, hospitalization, and health-related quality of life (HRQOL). Background: EC is often used as a primary outcome in exercise-based cardiac rehabilitation (CR) trials of heart failure (HF) via direct cardiorespiratory assessment of maximum oxygen uptake (VO2peak) or through submaximal tests, such as the 6-min walk test (6MWT). Methods: After a systematic review, 31 randomized trials of exercise-based CR compared with no exercise control (4,784 HF patients) were included. Outcomes were pooled using random effects meta-analyses, and inverse variance weighted linear regression equations were fitted to estimate the relationship between the CR on EC and all-cause mortality, hospitalization, and HRQOL. Spearman correlation coefficient (ρ), R2 at trial level, and surrogate threshold effect (STE) were calculated. STE represents the intercept of the prediction band of the regression line with null effect on the final outcome. Results: Exercise-based CR is associated with positive effects on EC measured through VO2peak (+3.10 ml/kg/min; 95% confidence interval [CI]: 2.01 to 4.20) or 6MWT (+41.15 m; 95% CI: 16.68 to 65.63) compared to control. The analyses showed a low level of association between improvements in EC (VO2peak or 6MWT) and mortality and hospitalization. Moderate levels of correlation between EC with HRQOL were seen (e.g., R2 <52%; |ρ| < 0.72). Estimated STE was an increase of 5 ml/kg/min for VO2peak and 80 m for 6MWT to predict a significant improvement in HRQOL. Conclusions: The study results indicate that EC is a poor surrogate endpoint for mortality and hospitalization but has moderate validity as a surrogate for HRQOL. Further research is needed to confirm these findings across other HF interventions.National Institute for Health Research (NIHR)University of Exete

    Jahn-Teller distortions and phase separation in doped manganites

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    A "minimal model" of the Kondo-lattice type is used to describe a competition between the localization and metallicity in doped manganites and related magnetic oxides with Jahn-Teller ions. It is shown that the number of itinerant charge carriers can be significantly lower than that implied by the doping level x. A strong tendency to the phase separation is demonstrated for a wide range of intermediate doping concentrations vanishing at low and high doping. The phase diagram of the model in the x-T plane is constructed. At low temperatures, the system is in a state with a long-range magnetic order: antiferromagnetic (AF), ferromagnetic (FM), or AF-FM phase separated (PS) state. At high temperatures, there can exist two types of the paramagnetic (PM) state with zero and nonzero density of the itinerant electrons. In the intermediate temperature range, the phase diagram includes different kinds of the PS states: AF-FM, FM-PM, and PM with different content of itinerant electrons. The applied magnetic field changes the phase diagram favoring the FM ordering. It is shown that the variation of temperature or magnetic field can induce the metal-insulator transition in a certain range of doping levels.Comment: 14 pages, 7 figures, submitted to Phys. Rev. B.; v.2 contains the changes introduced according to comments of the PRB Referees; in v. 3, some misprints are correcte

    Neural Circuitry of Novelty Salience Processing in Psychosis Risk: Association With Clinical Outcome

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    Psychosis has been proposed to develop from dysfunction in a hippocampal-striatal-midbrain circuit, leading to aberrant salience processing. Here, we used functional magnetic resonance imaging (fMRI) during novelty salience processing to investigate this model in people at clinical high risk (CHR) for psychosis according to their subsequent clinical outcomes. Seventy-six CHR participants as defined using the Comprehensive Assessment of At-Risk Mental States (CAARMS) and 31 healthy controls (HC) were studied while performing a novelty salience fMRI task that engaged an a priori hippocampal-striatal-midbrain circuit of interest. The CHR sample was then followed clinically for a mean of 59.7 months (~5 y), when clinical outcomes were assessed in terms of transition (CHR-T) or non-transition (CHR-NT) to psychosis (CAARMS criteria): during this period, 13 individuals (17%) developed a psychotic disorder (CHR-T) and 63 did not. Functional activation and effective connectivity within a hippocampal-striatal-midbrain circuit were compared between groups. In CHR individuals compared to HC, hippocampal response to novel stimuli was significantly attenuated (P = .041 family-wise error corrected). Dynamic Causal Modelling revealed that stimulus novelty modulated effective connectivity from the hippocampus to the striatum, and from the midbrain to the hippocampus, significantly more in CHR participants than in HC. Conversely, stimulus novelty modulated connectivity from the midbrain to the striatum significantly less in CHR participants than in HC, and less in CHR participants who subsequently developed psychosis than in CHR individuals who did not become psychotic. Our findings are consistent with preclinical evidence implicating hippocampal-striatal-midbrain circuit dysfunction in altered salience processing and the onset of psychosis

    On discretization in time in simulations of particulate flows

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    We propose a time discretization scheme for a class of ordinary differential equations arising in simulations of fluid/particle flows. The scheme is intended to work robustly in the lubrication regime when the distance between two particles immersed in the fluid or between a particle and the wall tends to zero. The idea consists in introducing a small threshold for the particle-wall distance below which the real trajectory of the particle is replaced by an approximated one where the distance is kept equal to the threshold value. The error of this approximation is estimated both theoretically and by numerical experiments. Our time marching scheme can be easily incorporated into a full simulation method where the velocity of the fluid is obtained by a numerical solution to Stokes or Navier-Stokes equations. We also provide a derivation of the asymptotic expansion for the lubrication force (used in our numerical experiments) acting on a disk immersed in a Newtonian fluid and approaching the wall. The method of this derivation is new and can be easily adapted to other cases
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