922017 research outputs found
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Evaluation of two-year recall of self-reported pesticide exposure among Ugandan smallholder farmers
No full textObjectives: To evaluate smallholder farmers’ recall of pesticide use and exposure determinants over a two-year period in a low-income country context. Methods: The Pesticide Use in Tropical Settings (PESTROP) study in Uganda consists of 302 smallholder farmers who were interviewed in 2017. In the same season in 2019, these farmers were re-questioned concerning pesticide use (e.g., use of active ingredients) and exposure information (e.g., crops, personal protective equipment [PPE], hygienic behaviours) they had previously provided. The extent of recall bias was assessed by comparing responses at follow-up in 2019 with practices and behaviours reported from the baseline interview in 2017.Results: An 84% (n=255) follow-up response rate was attained. We found instances of better recall (e.g., overall agreement >70% and Area Under the Curve (AUC) values >0.7) for the use of some active ingredients, commonly used PPE items, and washing clothes after application, whereas only 13.3% could correctly recall their three major crops. We observed a trend where more individuals reported the use of active ingredients, while fewer reported the use of PPE items, two years later. In general, we found better agreement in the recall of years working with pesticides compared to hours per day or days per week in the field, with no apparent systematic over or under reporting by demographic characteristics. Conclusions: While some of these findings provide consistency with those from high-income countries, more research is needed on recall in poorly educated agriculture communities in low- and middle-income settings to confirm these results
Investigating the shared genetic architecture of uterine leiomyoma and breast cancer: a genome-wide cross-trait analysis
No full textLittle is known regarding the shared genetic architecture or causality underlying the phenotypic association observed for uterine leiomyoma (UL) and breast cancer (BC). Leveraging summary statistics from the hitherto largest genome-wide association study (GWAS) conducted in each trait, we investigated the genetic overlap and causal associations of UL with BC overall, as well as with its subtypes defined by the status of estrogen receptor (ER). We observed a positive genetic correlation between UL and BC overall (r_g = 0.09, P = 6.00×10-3), which was consistent in ER+ subtype (r_g = 0.06, P = 0.01) but not in ER subtype (r_g = 0.06, P = 0.08). Partitioning the whole genome into 1,703 independent regions, local genetic correlation was identified at 22q13.1 for UL with BC overall and with ER+ subtype. Significant genetic correlation was further discovered in 9 out of 14 functional categories, with the highest estimates observed in coding, H3K9ac, and repressed regions. Cross-trait meta-analysis identified 9 novel loci shared between UL and BC. Mendelian randomization demonstrated a significantly increased risk of BC overall (OR = 1.09, 95% CI = 1.01-1.18) and ER+ subtype (OR = 1.09, 95% CI = 1.01-1.17) for genetic liability to UL. No reverse causality was found. Our comprehensive genome-wide cross-trait analysis demonstrates a shared genetic basis, pleiotropic loci, as well as a putative causal relationship between UL and BC, highlighting an intrinsic link underlying these two complex female diseases
Sodium-glucose cotransporter 1 inhibition and gout: Mendelian randomization study
No full textObjective. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) reduce serum urate, but their efficacy depends on renal function which is often impaired in patients with gout. SGLT1 is primarily expressed in the small intestine and its inhibition may be a more suitable target for gout. We aimed to investigate the association of genetically proxied SGLT1i with gout risk, serum urate levels and cardiovascular safety using Mendelian randomization (MR).Methods. Leveraging data from a genome-wide association study of 344,182 individuals in the UK Biobank, we identified a missense variant in the SLC5A1 gene that associated with glycated haemoglobin (HbA1c) to proxy SGLT1i. Outcome genetic data comprised 13,179 gout cases and 750,634 controls, 457,690 individuals for serum urate levels, and up to 977,323 individuals for cardiovascular safety outcomes. We applied the Wald ratio method and investigated potential genetic confounding using colocalization.Results. The rs17683430 missense variant was selected to instrument SGLT1i. Genetically proxied SGLT1i was associated with 75% reduction in gout risk (OR 0.25; 95%CI 0.06, 0.99; p=0.048) and 32.0μmol/L reduction in serum urate (95%CI -56.7, -7.3; p=0.01), per 6.7mmol/mol reduction in HbA1c. SGLT1i was associated with increased levels of low-density lipoprotein cholesterol (0.37mmol/L; 95%CI 0.17, 0.56; p=0.0002) but not coronary heart disease, stroke, or chronic kidney disease. Colocalization did not suggest that the results are attributable to genetic confounding.Conclusion. SGLT1 inhibition may represent a novel therapeutic option for preventing gout in patients with or without comorbid diabetes. Randomised trials are needed to formally investigate efficacy and safety.Keywords: Sodium-glucose cotransporter, gout, urate, cholesterol, SGLT1, glycated haemoglobin, diabetes.<br/
Comparing the Utility and Disclosure Risk of Synthetic Data with Samples of Microdata
No full textMost statistical agencies release randomly selected samples of Census microdata, usually with sample fractions under 10% and with other forms of statistical disclosure control (SDC) applied. An alternative to SDC is data synthesis, which has been attracting growing interest, yet there is no clear consensus on how to measure the associated utility and disclosure risk of the data. The ability to produce synthetic Census microdata, where the utility and associated risks are clearly understood, could mean that more timely and wider-ranging access to microdata would be possible. This paper follows on from previous work by the authors which mapped synthetic Census data on a risk-utility (R-U) map. The paper presents a framework to measure the utility and disclosure risk of synthetic data by comparing it to samples of the original data of varying sample fractions, thereby identifying the sample fraction which has equivalent utility and risk to the synthetic data. Three commonly used data synthesis packages are compared with some interesting results. Further work is needed in several directions but the methodology looks very promising.</p
Scaleability of dielectric susceptibility ϵzz with the number of layers and additivity of ferroelectric polarization in van der Waals semiconductors
No full textWe study the dielectric response of few layered crystals of various transition metal dichalcogenides (TMDs) and hexagonal Boron Nitride (hBN). We showed that the out-of-plane polarizability of a multilayer crystal (which characterizes response to the external displacement field) scales linearly with the number of layers, αNL zz = Nα1L zz , independently of the stacking configuration in the film. We also established additivity of ferroelectric polarizations of consecutive interfaces in case when such interfaces have broken inversion symmetry. Then we used the obtained data of monolayer α1L zz to calculate the values of the dielectric susceptibilities for semiconductor TMDs and hBN bulk crystals
Flash Sintering, A Novel Technique for Nuclear Waste Management
No full textMixed uranium plutonium oxide (MOx) pellets are a potential candidate wasteform for plutonium disposition in a GDF. However, to manufacture MOx pellets suitable for disposal, homogenised powder feeds must be densified by a sintering process. This is an energy intensive and time-consuming process. Flash Sintering (FS) is an innovative technique in which an electric field is applied to the sample during the sintering process. It offers a more efficient and robust way to densify ceramic-containing nuclear material for disposal. The FS process requires significantly lower firing temperatures. It may therefore offer safety improvements when immobilising unique or problematic waste streams, due to the retention of volatile but long-lived minor actinides such as americium oxide. These would normally vaporise out of the MOx pellet during the high temperatures and long hold times in conventional sintering.We report the successful application of controlled current rate AC-FS flash sintering on both UO2 and CeO2 surrogate nuclear material for both fuel and waste applications, together with the microstructural evolution of pellets produced using both conventional (CeO2) and FS (CeO2 and UO2). These results demonstrate the possibility of forming different microstructures as a function of current density, in a fraction of conventional processing time. Future opportunities exist for expanding this work to the demonstration of FS on mixed CeO2 and UO2, as well as zirconia and neutron poison-doped materials for waste management applications.<br/
Expensive Optimization with Production-Graph Resource Constraints: A First Look at a New Problem Class
No full textWe consider a new class of expensive, resource-constrained optimization problems (here arising from molecular discovery) where costs are associated with the experiments (or evaluations) to be carried out during the optimization process. In the molecular discovery problem, candidate compounds to be optimized must be synthesized in an iterative process that starts from a set of purchasable items and builds up to larger molecules. To produce target molecules, their required resources are either used from alreadysynthesized items in storage or produced themselves on-demand at an additional cost. Any remaining resources from the production process are stored for reuse for the next evaluations.We model these resource dependencies with a directed acyclic production graph describing the development process from granular purchasableitems to evaluable target compounds. Moreover, we develop several resource-efficient algorithms to address this problem. In particular, we develop resource-aware variants of Random Search heuristics and of Bayesian Optimization and analyze their performance in terms of anytime behavior. The experimental results were obtained from a real-world molecular optimization problem. Our results suggest that algorithms that encourage exploitation by reusing existing resources achieve satisfactory results while using fewer resources overall.CCS CONCEPTS• Theory of computation→Random search heuristics; • Mathematics of computing→Probabilistic algorithms.KEYWORDSmolecular discovery, production costs, resource constraints, expensive optimization<br/
Conversion of glucose to fructose over Sn and Ga-doped zeolite Y in methanol and water media
No full textIn this study, we use zeolite Y as a support for the synthesis of Sn and Ga doped zeolites aimed at the isomerization of glucose to fructose. Though these materials are inactive in water, they are active in methanol and we could ascertain a reaction pathway involving a hydride shift for the interconversion of glucose to fructose and mannose, and a Brønsted acid pathway with the formation of a methyl fructoside intermediate and its hydrolysis to fructose if water was added afterwards. By using characterizations comprising: chemisorption, XPS, XRD, HAADF-STEM and EXAFS; it was possible to demonstrate that a straightforward impregnation protocol for the preparation of our catalysts, led to Sn/Y mainly consisting of small SnO2 clusters on the external surface of the zeolite, whereas Ga/Y consisting of highly dispersed Ga species mostly inside the zeolite pores; and a catalytic activity that appears to be dominated by Brønsted acid sites
Save money to lose money? Implications of opting out of a voluntary audit review for a firm’s cost of debt
No full textAn audit review (AR) is a mechanism used by boards to assess the quality of interim financial reports on a timely basis. In Canada, the AR is voluntary, with listed firms mandated to disclose when they choose not to purchase additional audit verification. Given the relatively low cost of an AR, opting out of it can be regarded as a negative signal, especially in the context of lenders’ sensitivity to downside risk. Using a sample of 7,585 firm-year observations from 1,616 public firms in Canada over the period 2004-2015, we document that firms without a voluntary AR have a higher cost of debt than firms with an AR. Furthermore, after firms opt out of the AR, the increase in the cost of debt is accompanied by a rise in discretionary abnormal accruals and managers’ stock-based compensation. Moreover, no-AR firms are more likely to reduce post-switch private borrowing and have lower equity analyst following. Our study is the first to document that although listed borrowers that opt out of an AR have a higher cost of debt financing, they are concurrently able to engage in more earnings management and grant their managers higher stock-based compensation because of lower external monitoring