Multidisciplinary Design Optimization of an Extreme Aspect Ration HALE UAV

Development of High Altitude Long Endurance (HALE) aircraft systems is part of a vision for a low cost communications/surveillance capability. Applications of a multi payload aircraft operating for extended periods at stratospheric altitudes span military and civil genres and support battlefield operations, communications, atmospheric or agricultural monitoring, surveillance, and other disciplines that may currently require satellite-based infrastructure. The central goal of this research was the development of a multidisciplinary tool for analysis, design, and optimization of HALE UAVs, facilitating the study of a novel configuration concept. Applying design ideas stemming from a unique WWII-era project, a pinned wing HALE aircraft would employ self-supporting wing segments assembled into one overall flying wing. When wrapped in an optimization routine, the integrated design environment shows potential for a 17.3% reduction in weight when wing thickness to chord ratio, aspect ratio, wing loading, and power to weight ratio are included as optimizer-controlled design variables. Investigation of applying the sustained day/night mission requirement and improved technology factors to the design shows that there are potential benefits associated with a segmented or pinned wing. As expected, wing structural weight is reduced, but benefits diminish as higher numbers of wing segments are considered. For an aircraft consisting of six wing segments, a maximum of 14.2% reduction in gross weight over an advanced technology optimal baseline is predicted

Frequent Premature Atrial Contractions Are Associated With Poorer Cognitive Function in the Atherosclerosis Risk in Communities (ARIC) Study

Objective: To evaluate the association of premature atrial contraction (PAC) frequency with cognitive test scores and prevalence of dementia or mild cognitive impairment (MCI). Materials and Methods: We conducted a cross-sectional analysis using Atherosclerosis Risk in Communities study visit 6 (January 1, 2016, through December 31, 2017) data. We included 2163 participants without atrial fibrillation (AF) (age mean ± SD, 79±4 years; 1273 (58.9%) female; and 604 (27.97.0% Black) who underwent cognitive testing and wore a leadless, ambulatory electrocardiogram monitor for 14 days. We categorized PAC frequency based on the percent of beats: less than 1%, minimal; 1% to <5%, occasional; greater than or equal to 5%, frequent. We derived cognitive domain-specific factor scores (memory, executive function, language, and global z-score). Dementia and MCI were adjudicated. Results: During a mean analyzable time of 12.6±2.6 days, 339 (15.7%) had occasional PACs and 107 (4.9%) had frequent PACs. Individuals with frequent PACs (vs minimal) had lower executive function factor scores by 0.30 (95% CI, -0.46 to -0.14) and lower global factor scores by 0.20 (95% CI, -0.33 to -0.07) after multivariable adjustment. Individuals with frequent PACs (vs minimal) had higher odds of prevalent dementia or MCI after multivariable adjustment (odds ratio, 1.74; 95% CI, 1.09 to 2.79). These associations were unchanged with additional adjustment for stroke. Conclusion: In community-dwelling older adults without AF, frequent PACs were cross-sectionally associated with lower executive and global cognitive function and greater prevalence of dementia or MCI, independently of stroke. Our findings lend support to the notion that atrial cardiomyopathy may be a driver of AF-related outcomes. Further research to confirm these associations prospectively and to elucidate underlying mechanisms is warranted

Genome-wide association and Mendelian randomisation analysis provide insights into the pathogenesis of heart failure

Heart failure (HF) is a leading cause of morbidity and mortality worldwide. A small proportion of HF cases are attributable to monogenic cardiomyopathies and existing genome-wide association studies (GWAS) have yielded only limited insights, leaving the observed heritability of HF largely unexplained. We report results from a GWAS meta-analysis of HF comprising 47,309 cases and 930,014 controls. Twelve independent variants at 11 genomic loci are associated with HF, all of which demonstrate one or more associations with coronary artery disease (CAD), atrial fibrillation, or reduced left ventricular function, suggesting shared genetic aetiology. Functional analysis of non-CAD-associated loci implicate genes involved in cardiac development (MYOZ1, SYNPO2L), protein homoeostasis (BAG3), and cellular senescence (CDKN1A). Mendelian randomisation analysis supports causal roles for several HF risk factors, and demonstrates CAD-independent effects for atrial fibrillation, body mass index, and hypertension. These findings extend our knowledge of the pathways underlying HF and may inform new therapeutic strategies

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

The impact of combinatorial stress on the growth dynamics and metabolome of 'Burkholderia mesoacidophila' demonstrates the complexity of tolerance mechanisms

Aims: The recently sequenced Burkholderia mesoacidophila (previously Pseudomonas mesoacidophila) is a soil organism and as such will be exposed to multiple concurrent stresses in the natural environment. The combinatorial stress potentially experienced by microbes in soil has not been investigated in detail. Methods and Results: The impact of combinatorial stress on growth was investigated using tripartite variables—temperature, nutritional environment and either osmotic or oxidative stress. In nutritionally stringent conditions, increasing diamide concentration had no effect on growth while increasing H2O2 concentration reduced both growth rate and maximum density. Metabolomic studies with oxidative stress revealed specific (unidentified) metabolites associated with diamide tolerance, and an overwhelming dominance of sugars and sugar alcohols in nutritionally stringent conditions with and without the additional stressor. Conclusions: Combinatorial stress tolerance is complex. Temperature had the greatest independent impact on growth, while the impact of the nutritional environment played a key role in oxidative stress tolerance. In nutritionally stringent conditions, the metabolome suggested different tolerance mechanisms for different types of oxidative stress. Significance and Impact of the Study: This work demonstrates the specificity of the stress response, and the need to consider multiple environmental factors to meaningfully investigate tolerance. Both environmental and clinical settings subject bacteria to combinatorial stress and this should be considered in the design of further studies