Multidisciplinary Applications of Detached-Eddy Simulation to Separated Flows at High Reynolds Numbers

We focus on multidisciplinary applications of detached-eddy simulation (DES), principally flight mechanics and aeroelasticity. Specifically, the lateral instability (known as abrupt wing stall) of the preproduction F/A-18E is reproduced using DES, including the unsteady shock motion. The presence of low frequency pressure oscillations due to shock motion in the current simulations and the experiments motivated a full aircraft calculation, which showed low frequency high-magnitude rolling moments that could be a significant contributor to the abrupt wing stall phenomenon. DES is also applied to the F-18 high angle of attack research vehicle (HARV) at a moderate angle of attack to reproduce the vortex breakdown leading to vertical stabilizer buffet. Unsteady tail loads are compared to flight test data. This work lays the foundation for future deforming grid calculations to reproduce the aero-elastic tail buffet seen in flight test. Solution based grid adaption is used on unstructured grids in both cases to improve the resolution in the separated region. Previous DoD Challenge work has demonstrated the unique ability of the DES turbulence treatment to accurately and efficiently predict flows with massive separation at flight Reynolds numbers. DES calculations have been performed using the Cobalt code and on unstructured grids, an approach that can deal with complete configurations with very few compromises. A broad range of flows has been examined in previous Challenge work, including aircraft forebodies, airfoil sections, a missile afterbody, vortex breakdown on a delta wing, and the F-16 and F-15E at high angles-of-attack. All DES predictions exhibited a moderate to significant improvement over results obtained using traditional Reynolds-averaged models and often excellent agreement with experimental/flight-test data. DES combines the efficiency of a Reynolds-averaged turbulence model near the wall with the fidelity of Large-Eddy Simulation (LES) in separated regions. Since it uses Large-Eddy Simulation in the separated regions, it is capable of predicting the unsteady motions associated with separated flows. The development and demonstration of improved methods for the prediction of flight mechanics and aeroelasticity in this Challenge is expected to reduce the acquisition cost of future military aircraft

Algorithm for normal random numbers

We propose a simple algorithm for generating normally distributed pseudo random numbers. The algorithm simulates N molecules that exchange energy among themselves following a simple stochastic rule. We prove that the system is ergodic, and that a Maxwell like distribution that may be used as a source of normally distributed random deviates follows when N tends to infinity. The algorithm passes various performance tests, including Monte Carlo simulation of a finite 2D Ising model using Wolff's algorithm. It only requires four simple lines of computer code, and is approximately ten times faster than the Box-Muller algorithm.Comment: 5 pages, 3 encapsulated Postscript Figures. Submitted to Phys.Rev.Letters. For related work, see http://pipe.unizar.es/~jf

Dew-worms in white nights: High-latitude light constrains earthworm (Lumbricus terrestris) behaviour at the soil surface

Soil is an effective barrier to light penetration that limits the direct influence of light on belowground organisms. Variation in aboveground light conditions, however, is important to soil-dwelling animals that are periodically active on the soil surface. A prime example is the earthworm Lumbricus terrestris L. (the dew-worm), an ecosystem engineer that emerges nocturnally on the soil surface. In the summer, the northernmost populations of L. terrestris are exposed to a time interval with no daily dark period. During a two-week period preceding the summer solstice, we studied the constraints that boreal night illumination imposes on L. terrestris surface activity by comparing their behaviour under ambient light with artificially-induced darkness. Looking for evidence of geographical divergence in light response, we compared the behaviour of native L. terrestris (Jokioinen, S–W Finland; 60°48′N) with two markedly more southern populations, from Preston (Lancashire, UK; 53°47′N) and Coshocton (Ohio, USA; 40°22′N) where the nights have a period of darkness throughout the year (total latitudinal range ca. 2300 km). Under ambient light conditions, L. terrestris emergence on the soil surface was diminished by half compared with the darkened treatment and it peaked at the darkest period of the night. Also mating rate decreased considerably under ambient light. The native dew-worms were generally the most active under ambient light. They emerged earlier in the evening and ceased their activity later in the morning than dew-worms from the two more southerly populations. The differences in behaviour were, however, significant mainly between native and UK dew-worms. In the darkened treatment, the behaviour of the three earthworm origins did not differ. Under the experimental conditions light condition was the dominant environmental factor controlling surface activity, but elevated night-time air temperature and humidity also encouraged dew-worm emergence without discernible differences among geographical origins. Our results show, that in boreal summer, the high level of night illumination strongly limits soil-surface activity of dew-worms. Considering the important regulatory role of L. terrestris in many ecosystem processes, this can have significant corollaries in dew-worm impacts on the environment. Although evidence for geographical differentiation in behaviour was obtained, the results point to phenotypic flexibility in L. terrestris light response

Evaluating 'Prefer not to say' Around Sensitive Disclosures

As people's offline and online lives become increasingly entwined, the sensitivity of personal information disclosed online is increasing. Disclosures often occur through structured disclosure fields (e.g., drop-down lists). Prior research suggests these fields may limit privacy, with non-disclosing users being presumed to be hiding undesirable information. We investigated this around HIV status disclosure in online dating apps used by men who have sex with men. Our online study asked participants (N=183) to rate profiles where HIV status was either disclosed or undisclosed. We tested three designs for displaying undisclosed fields. Visibility of undisclosed fields had a significant effect on the way profiles were rated, and other profile information (e.g., ethnicity) could affect inferences that develop around undisclosed information. Our research highlights complexities around designing for non-disclosure and questions the voluntary nature of these fields. Further work is outlined to ensure disclosure control is appropriately implemented around online sensitive information disclosures

Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: Data linkage study of 11 million Australians

Objective To assess the cancer risk in children and adolescents following exposure to low dose ionising radiation from diagnostic computed tomography (CT) scans. Design Population based, cohort, data linkage study in Australia. Cohort members 10.9 million people identified from Australian Medicare records, aged 0-19 years on 1 January 1985 or born between 1 January 1985 and 31 December 2005; all exposures to CT scans funded by Medicare during 1985-2005 were identified for this cohort. Cancers diagnosed in cohort members up to 31 December 2007 were obtained through linkage to national cancer records. Main outcome Cancer incidence rates in individuals exposed to a CT scan more than one year before any cancer diagnosis, compared with cancer incidence rates in unexposed individuals. Results 60 674 cancers were recorded, including 3150 in 680 211 people exposed to a CT scan at least one year before any cancer diagnosis. The mean duration of follow-up after exposure was 9.5 years. Overall cancer incidence was 24% greater for exposed than for unexposed people, after accounting for age, sex, and year of birth (incidence rate ratio (IRR) 1.24 (95% confidence interval 1.20 to 1.29); P<0.001). We saw a dose-response relation, and the IRR increased by 0.16 (0.13 to 0.19) for each additional CT scan. The IRR was greater after exposure at younger ages (P<0.001 for trend). At 1-4, 5-9, 10-14, and 15 or more years since first exposure, IRRs were 1.35 (1.25 to 1.45), 1.25 (1.17 to 1.34), 1.14 (1.06 to 1.22), and 1.24 (1.14 to 1.34), respectively. The IRR increased significantly for many types of solid cancer (digestive organs, melanoma, soft tissue, female genital, urinary tract, brain, and thyroid); leukaemia, myelodysplasia, and some other lymphoid cancers. There was an excess of 608 cancers in people exposed to CT scans (147 brain, 356 other solid, 48 leukaemia or myelodysplasia, and 57 other lymphoid). The absolute excess incidence rate for all cancers combined was 9.38 per 100 000 person years at risk, as of 31 December 2007. The average effective radiation dose per scan was estimated as 4.5 mSv. Conclusions The increased incidence of cancer after CT scan exposure in this cohort was mostly due to irradiation. Because the cancer excess was still continuing at the end of follow-up, the eventual lifetime risk from CT scans cannot yet be determined. Radiation doses from contemporary CT scans are likely to be lower than those in 1985-2005, but some increase in cancer risk is still likely from current scans. Future CT scans should be limited to situations where there is a definite clinical indication, with every scan optimised to provide a diagnostic CT image at the lowest possible radiation dose

Greater aortic inflammation and calcification in abdominal aortic aneurysmal disease than atherosclerosis: a prospective matched cohort study

Funder: British Heart Foundation; FundRef: http://dx.doi.org/10.13039/501100000274Objective: Using combined positron emission tomography and CT (PET-CT), we measured aortic inflammation and calcification in patients with abdominal aortic aneurysms (AAA), and compared them with matched controls with atherosclerosis. Methods: We prospectively recruited 63 patients (mean age 76.1±6.8 years) with asymptomatic aneurysm disease (mean size 4.33±0.73 cm) and 19 age-and-sex-matched patients with confirmed atherosclerosis but no aneurysm. Inflammation and calcification were assessed using combined 18F-FDG PET-CT and quantified using tissue-to-background ratios (TBRs) and Agatston scores. Results: In patients with AAA, 18F-FDG uptake was higher within the aneurysm than in other regions of the aorta (mean TBRmax2.23±0.46 vs 2.12±0.46, p=0.02). Compared with atherosclerotic control subjects, both aneurysmal and non-aneurysmal aortae showed higher 18F-FDG accumulation (total aorta mean TBRmax2.16±0.51 vs 1.70±0.22, p=0.001; AAA mean TBRmax2.23±0.45 vs 1.68±0.21, p<0.0001). Aneurysms containing intraluminal thrombus demonstrated lower 18F-FDG uptake within their walls than those without (mean TBRmax2.14±0.43 vs 2.43±0.45, p=0.018), with thrombus itself showing low tracer uptake (mean TBRmax thrombus 1.30±0.48 vs aneurysm wall 2.23±0.46, p<0.0001). Calcification in the aneurysmal segment was higher than both non-aneurysmal segments in patients with aneurysm (Agatston 4918 (2901–8008) vs 1017 (139–2226), p<0.0001) and equivalent regions in control patients (442 (304-920) vs 166 (80-374) Agatston units per cm, p=0.0042). Conclusions: The entire aorta is more inflamed in patients with aneurysm than in those with atherosclerosis, perhaps suggesting a generalised inflammatory aortopathy in patients with aneurysm. Calcification was prominent within the aneurysmal sac, with the remainder of the aorta being relatively spared. The presence of intraluminal thrombus, itself metabolically relatively inert, was associated with lower levels of inflammation in the adjacent aneurysmal wall

Tunable fractional quantum Hall phases in bilayer graphene

Symmetry-breaking in a quantum system often leads to complex emergent behavior. In bilayer graphene (BLG), an electric field applied perpendicular to the basal plane breaks the inversion symmetry of the lattice, opening a band gap at the charge neutrality point. In a quantizing magnetic field, electron interactions can cause spontaneous symmetry-breaking within the spin and valley degrees of freedom, resulting in quantum Hall effect (QHE) states with complex order. Here, we report fractional QHE states in BLG that show phase transitions that can be tuned by a transverse electric field. This result provides a model platform with which to study the role of symmetry-breaking in emergent states with topological order

Factors that influence the intra-articular rupture pattern of the ACL graft following single-bundle reconstruction

The number of revision anterior cruciate ligament (ACL) surgeries performed annually continues to rise. The purpose of this study was to determine the most common rupture pattern in ACL revision cases after previous single-bundle reconstruction. The second aim was to determine the relationship between rupture pattern and patient-specific factors (age, gender, time between the initial ACL reconstruction and re-injury, and etiology/mechanism of failure) and surgical factors (graft type, tunnel angle). This was a cohort study of 60 patients that underwent revision ACL surgery after previous single-bundle ACL reconstruction. Three sports medicine-trained orthopedic surgeons reviewed the arthroscopic videos and determined the rupture pattern of the grafts. The rupture pattern was then correlated to the above-mentioned factors. The inter-observer agreement had a kappa of 0.7. The most common rupture pattern after previous single-bundle ACL reconstruction is elongation of the graft. This is different from the native ACL, which displays more proximal ruptures. With the use of autograft tissue and after a longer period of time, the rupture pattern in revision surgery is more similar to that of the native ACL. The most common rupture pattern after previous single-bundle reconstruction was elongation of the graft. Factors that influenced the rupture pattern were months between ACL reconstruction and re-injury and graft type. Cohort study, Level I

1993 Progress Reports

The 1993 Progress Reports which contain Blueberry Tax Supported Weed Management and Pruning Project Reports, and CSRS Supported Weed Management and Pruning Project Reports, pertain to and report on research conducted in 1992. They were prepared for the Maine Wild Blueberry Commission and the University of Maine Wild Blueberry Advisory Committee by researchers at the University of Maine, Orono. Projects in this report include: Progress Reports 1. Effects of Irrigation on Low bush Blueberry Yield and Quality 2. Economics of Investing in Irrigation for Lowbush Blueberries 3. Diammonium Phosphate Study 4. Phosphorus Dose/Response Curve 5. Winter Injury Protection by Potassium 6. Multiple Cropping of Wild Stands 7. Effect of Boron on Lowbush Blueberry Fruit Set and Yield 8.Determination of Pesticide Residue Levels in Freshly Harvested and Processed Lowbush Blueberries 9. Effects of Calcium Salts and Citric Acids on the Quality of Canned Lowbush Blueberries- missing 10. Investigation of PreProcess Changes- missing 11. The Effect of Fertilization and Irrigation on Blueberry Fruit Control - missing 12. Pollination Ecology of Lowbush Blueberry in Maine 13. Control of Secondary Blueberry Pests 14. Control of Blueberry Maggot 15. Biology and Action Thresholds of Secondary Blueberry Pests 16. Cold-Hardiness of Native Lowbush Blueberries 17. Design, Fabrication, and Testing of an Experimental Sterilizer for Blueberry Fields 18. Canned Product Quality - Heat Resistant Molds 19. Sanitation for Disease Control Blueberry Tax Supported Weed Management and Pruning Project Reports 20. Evaluation of Postemergence Applications of Tribenuron Methyl for Bunchberry Control 21. Comparison of Poast and Select for Suppression of Bunchgrass 22. Effect of Time of Fall Pruning on Growth and Productivity of Blueberries. and Evaluation of Infrared Burner to Prune Blueberries 23. Evaluation of Velpar impregnated DAP for weed control 24. Thresholds of Dogbane and Bracken Fern for Mechanical and Chemical Control in Lowbush Blueberry Fields 25. Effect of Time and Rate of Application of Clopyralid for Control of Vetch in Lowbush Blueberries 26. Hexazinone Ground Water Survey 27. Composting Blueberry Processing Waste 28. Hexazinone Movement in a Blueberry Soil in Maine CSRS Supported Weed Management and Pruning Project Reports 29. Evaluation of the Suitability of Remote Sensing to Evaluate Plant Cover in Lowbush Blueberry Fields 30. Obstruction Removal in Lowbush Blueberry Fields 31. Evaluation of Pressurized Rope Wick Wick Master Wiper for Treating Weeds Growing Above Lowbush Blueberries 32. Evaluation of Infrared Burner for Weed Control 33. Blueberry Extension Education Program Base Miscellaneous 34. Comparison of N, NP, and NPK Fertilizers to Correct Nitrogen and Phosphorus Deficienc