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Impact of migrant and returning farmer professionalization on food production diversity
No full textSince the 2000s, there has been an increasing number of returning and migrant farmers across China. In 2012, China initiated a program for fostering professional farmers, which has caused greater changes for farmers and led to an agricultural shift towards commercial production. Migration has been recognized as a crucial factor affecting the diversity of agricultural production. However, scant attention has been paid to how different types of farmers influence agricultural diversification. Therefore, this study examines the influence of migrant farmers, returning farmers, and local non-migrant farmers on food production diversity. This study collected farm-level data on food production and farmers’ characteristics and applied a negative binomial regression model to estimate the impacts of different types of farmers on agricultural development. The results show that farms operated by migrant farmers had a significantly lower level of food production diversity while farms operated by returning farmers had no significant difference in food production diversity, using farms operated by local non-migrant farmers as the reference category. The variation in agricultural production diversity lies in differences in food production purposes, agricultural and market skills, and various risk-related capacities among the different types of farmers. Farm-level production specialization does not necessarily reduce food diversity and agrobiodiversity at the rural community and regional level
SWAT 86 evaluation: Randomised evaluation of pre-notification of trial participants before self-report outcome data collection to improve retention
No full textBackgroundRetention is considered the second highest trial methods priority in the UK after recruitment. There is limited evidence on whether notifying trial participants that a follow-up questionnaire will be sent soon (‘pre-notification’) affects retention. MethodsThis Study Within a Trial (SWAT) evaluated whether sending a pre-notification letter or email around 2 weeks before sending a self-report questionnaire increased retention, in terms of provision of the host trial primary outcome. The SWAT was a randomised, two-arm, parallel-design (1:1 allocation ratio) trial, controlled by ‘no pre-notification letter’. It was embedded within the WORKWELL host trial, which evaluated the impact of job retention vocational rehabilitation on work-related and health-related outcomes of employed people with inflammatory arthritis. The SWAT primary outcome was a valid response for the WORKWELL primary outcome.Results244 trial participants took part in the SWAT. All were included in the analysis. Among those sent a pre-reminder, 100/121 (83%) provided a valid response for the WORKWELL primary outcome, compared to 97/123 (79%) of those not sent a pre-reminder. The estimated adjusted odds ratio was 1.28 (95% confidence interval 0.67 to 2.42), with a risk difference of 3.8% (95%CI -6.1% to 13.6%), favouring the pre-reminder. The estimated intervention cost per additional participant retained was £53.42, and the total cost per additional participant retained was £46.52.ConclusionResearchers may have a small improvement in trial retention by using pre-notification. The cost per additional participant retained is relatively low. However, further evaluations are merited.<br/
Stein's Method Meets Computational Statistics: A Review of Some Recent Developments
No full textStein's method compares probability distributions through the study of a class of linear operators called Stein operators. While mainly studied in probability and used to underpin theoretical statistics, Stein's method has led to significant advances in computational statistics in recent years. The goal of this survey is to bring together some of these recent developments and, in doing so, to stimulate further research into the successful field of Stein's method and statistics. The topics we discuss include tools to benchmark and compare sampling methods such as approximate Markov chain Monte Carlo, deterministic alternatives to sampling methods, control variate techniques, parameter estimation and goodness-of-t testing.<br/
The Effect of Compositional Heterogeneity on the Martensite Start Temperature of a High Strength Steel During Rapid Austenitisation and Cooling
No full textMany low alloy steels are compositionally heterogeneous due to the preferential segregation of alloying elements to the dendritic or interdendritic regions when the steel is first solidified (microsegregation). This segregation is often ignored when using CCT diagrams to predict the phase transformation behaviour of steels, but may be of importance in some industrially-relevant cases. This work focuses on the martensite start temperature (Ms) of Super CMV, a high strength aerospace steel, after rapid austenitisation treatment to various peak temperatures from 900 °C to 1300 °C. It was found that the average Ms temperature increased with increasing peak temperature (and prior austenite grain size) at peak temperatures of 1100°C and above, which is to be expected conventionally. However, at peak temperatures of below 1100°C, the Ms temperature increased with decreasing prior-austenite grain size. It is proposed that this was due to the presence of non-dissolved carbides in these conditions, particularly in enriched bands of material, which deplete the matrix and hence raise Ms
Theoretical study of the stability of the tetradymite-like phases of Sb2S3, Bi2S3, and Sb2Se3
No full textWe report a comparative theoretical study of the Pnma and R-3m phases of Sb2S3, Bi2S3, and Sb2Se3 close to ambient pressure. Our enthalpy calculations at 0 K show that at ambient pressure the R-3m (tetradymite-like) phase of Sb2Se3 is energetically more stable than the Pnma phase, contrary to what is observed for Sb2S3 and Bi2S3, and irrespective of the exchange-correlation functional employed in the calculations. The result for Sb2Se3 is in contradiction to experiments where all three compounds are usually grown in the Pnma phase. This result is further confirmed by free-energy calculations taking into account the temperature dependence of the unit-cell volumes and phonon frequencies. Lattice dynamics and elastic tensor calculations further show that both Pnma and R-3m phases of Sb2Se3 are dynamically and mechanically stable at zero applied pressure. Since these results suggest that the formation of the R-3m phase for Sb2Se3 should be feasible at close to ambient conditions, we provide a theoretical crystal structure and simulated Raman and infrared spectra to help in its identification. We also discuss the results of the two published works that have claimed to have synthesized tetradymite-like Sb2Se3. Finally, the stability of the R-3m phase across the three group-15 A2X3 sesquichalcogenides is analysed based on their van der Waals gap and X-X in-plane geometry
Hierarchical zeolites: controllable synthesis, diffusion study and catalysis
No full textHierarchical zeolites refer to zeolitic materials having bi-/multi-modal interconnective pores arranged in order of certain ranks, which improve the molecular diffusion within their frameworks, and hence the performance in their applications such as adsorption and heterogeneous catalysis. Hierarchical zeolites are commonly produced via the ‘top-down’ post-synthetic treatments (such as dealumination and/or desilication) of pre-synthesised zeolites (i.e. the parent zeolites) and the ‘bottom-up’ synthesis-by-design methods (such as soft/hard templating). This review presents the recent advances (from 2001 to 2020) in the strategies of making hierarchical zeolites, with the emphasis on the ‘top-down’ approaches due to their relatively high practicality. Since hierarchical zeolites are proposed to improve intracrystalline diffusion, experimental studies of guest molecules diffusion in hierarchical zeolites is also reviewed. Additionally, catalytic applications of hierarchical zeolites, in comparison with the conventional microporous pristine zeolites, are also commented to highlight the advantages of hierarchical zeolites to improve catalysis.Keywords Hierarchical zeolites; Post-synthetic treatment; Diffusion; Pulsed-field gradient nuclear magnetic resonance (PFG-NMR); Catalysis<br/
Predictors of myocardial fibrosis and response to anti-fibrotic therapy in heart failure with preserved ejection fraction
No full textPurpose: Myocardial fibrosis, measured using magnetic resonance extracellular volume (ECV), associates with adverse outcome in heart failure with preserved ejection fraction (HFpEF). In the PIROUETTE (The Pirfenidone in Patients with Heart Failure and Preserved Left Ventricular Ejection Fraction) trial, the novel anti-fibrotic agent pirfenidone reduced myocardial fibrosis. We sought to identify baseline characteristics that associate with myocardial fibrotic burden, the change in myocardial fibrosis over a year, and predict response to pirfenidone in patients with HFpEF. Methods: Amongst patients enrolled in the PIROUETTE trial (n=107), linear regression models were used to assess the relationship between baseline variables and baseline myocardial ECV, with change in myocardial ECV adjusting for treatment allocation, and to identify variables that modified the pirfenidone treatment effect.Results: Body mass index, left atrial reservoir strain, haemoglobin and aortic distensibility were associated with baseline ECV in stepwise modelling, and systolic blood pressure, and log N-terminal pro B-type natriuretic peptide were associated with baseline ECV in clinically-guided modelling. QRS duration, left ventricular mass and presence of an infarct at baseline were associated with an increase in ECV from baseline to week 52. Whilst QRS duration, presence of an infarct, global longitudinal strain and left atrial strain modified the treatment effect of pirfenidone when considered individually, no variable modified treatment effect on multivariable modelling.Conclusion: Baseline characteristics were identified that associate with myocardial fibrosis and predict change in myocardial fibrosis. No variables that independently modify the treatment effect of pirfenidone were identified (PIROUETTE, NCT02932566). Keywords: Heart failure, myocardial fibrosis, magnetic resonance imaging (MRI), extracellular volume (ECV)<br/
Glucose Treatment Targets in Pregnancy - A Review of Evidence and Guidelines
No full textBackgroundMaternal diabetes mellitus during pregnancy is associated with an increased risk of pregnancy complications for both the mother and the fetus. One of the most prevalent complications is pathological fetal growth, and particularly infants are born large for gestational age (LGA), which leads to problematic deliveries, including the need for caesarean section, instrumental delivery and further perinatal complications. Glucose monitoring during pregnancy is essential for ensuring appropriate glycaemic control and to reduce these associated risks. The current methods of glucose monitoring include measuring glycosylated haemoglobin (HbA1c), self-monitoring of capillary blood glucose (SMBG), and more recently, continuous glucose monitoring (CGM). Observational studies and randomised controlled trials (RCTs) have assessed the appropriate glycaemic targets for HbA1c, SMBG, and CGM in relation to pregnancy outcomes. ObjectiveIn this review we identify current international guidelines on glycaemic targets and review the supporting evidence. MethodWe performed an extensive literature search on glycaemic targets in pregnancies affected by diabetes and we researched international guidelines from recognised societies.Results and ConclusionThe majority of studies used to define the glucose targets associated with the best pregnancy outcomes, across all modalities, were in women with type 1 diabetes. There were limited studies in women with type 2 diabetes and gestational diabetes. We therefore suggest that further research needs to be conducted on glucose targets and clinical outcomes specifically in these populations where CGM technology offers the greatest potential for monitoring glucose and improving pregnancy outcomes.<br/
