Extensive and Intimate Association of the Cytoskeleton with Forming Silica in Diatoms: Control over Patterning on the Meso- and Micro-Scale

BACKGROUND: The diatom cell wall, called the frustule, is predominantly made out of silica, in many cases with highly ordered nano- and micro-scale features. Frustules are built intracellularly inside a special compartment, the silica deposition vesicle, or SDV. Molecules such as proteins (silaffins and silacidins) and long chain polyamines have been isolated from the silica and shown to be involved in the control of the silica polymerization. However, we are still unable to explain or reproduce in vitro the complexity of structures formed by diatoms. METHODS/PRINCIPAL FINDING: In this study, using fluorescence microscopy, scanning electron microscopy, and atomic force microscopy, we were able to compare and correlate microtubules and microfilaments with silica structure formed in diversely structured diatom species. The high degree of correlation between silica structure and actin indicates that actin is a major element in the control of the silica morphogenesis at the meso and microscale. Microtubules appear to be involved in the spatial positioning on the mesoscale and strengthening of the SDV. CONCLUSIONS/SIGNIFICANCE: These results reveal the importance of top down control over positioning of and within the SDV during diatom wall formation and open a new perspective for the study of the mechanism of frustule patterning as well as for the understanding of the control of membrane dynamics by the cytoskeleton

Carrier-mediated magnetoelectricity in complex oxide heterostructures

While tremendous success has been achieved to date in creating both single phase and composite magnetoelectric materials, the quintessential electric-field control of magnetism remains elusive. In this work, we demonstrate a linear magnetoelectric effect which arises from a novel carrier-mediated mechanism, and is a universal feature of the interface between a dielectric and a spin-polarized metal. Using first-principles density functional calculations, we illustrate this effect at the SrRuO$_3$/SrTiO$_3$ interface and describe its origin. To formally quantify the magnetic response of such an interface to an applied electric field, we introduce and define the concept of spin capacitance. In addition to its magnetoelectric and spin capacitive behavior, the interface displays a spatial coexistence of magnetism and dielectric polarization suggesting a route to a new type of interfacial multiferroic

Fundamental spray and combustion measurements of soy methyl-ester biodiesel

Although biodiesel has begun to penetrate the fuel market, its effect on injection processes, combustion and emission formation under diesel engine conditions remains somewhat unclear. Typical exhaust measurements from engines running biodiesel indicate that particulate matter, carbon monoxide and unburnt hydrocarbons are decreased, whereas nitrogen oxide emissions tend to be increased. However, these observations are the result of complex interactions between physical and chemical processes occurring in the combustion chamber, for which understanding is still needed. To characterize and decouple the physical and chemical influences of biodiesel on spray mixing, ignition, combustion and soot formation, a soy methyl-ester (SME) biodiesel is injected into a constant-volume combustion facility under diesel-like operating conditions. A range of optical diagnostics is performed, comparing biodiesel to a conventional #2 diesel at the same injection and ambient conditions. Schlieren high-speed imaging shows virtually the same vapour-phase penetration for the two fuels, while simultaneous Mie-scatter imaging shows that the maximum liquid-phase penetration of biodiesel is higher than diesel. Differences in the liquid-phase penetration are expected because of the different boiling-point temperatures of the two fuels. However, the different liquid-phase penetration does not affect overall mixing rate and downstream vapour-phase penetration because each fuel spray has similar momentum and spreading angle. For the biodiesel and diesel samples used in this study, the ignition delay and lift-off length are only slightly less for biodiesel compared to diesel, consistent with the fuel cetane number (51 for biodiesel, 46 for diesel). Because of the similarity in lift-off length, the differences in equivalence ratio distribution at the lift-off length are mainly affected by the oxygen content of the fuels. For biodiesel, the equivalence ratio is reduced, which, along with the fuel molecular structure and oxygen content, significantly affects soot formation downstream. Spatially resolved soot volume fraction measurements obtained by combining line-of-sight laser extinction measurements with planar laser-induced incandescence imaging show that the soot concentration can be reduced by an order of magnitude for biodiesel. These integrated measurements of spray mixing, combustion and quantitative soot concentration provide new validation data for the development of computational fluid dynamics spray, combustion and soot formation models suitable for the latest biofuels.This work was supported by the Spanish Ministry of Science and Innovation for Jean-Guillaume Nerva's visiting research, through the OPTICOMB project [TRA2007-67961-C03-01].Nerva, J.; Genzale, CL.; Kook, S.; García Oliver, JM.; Pickett, LM. (2013). Fundamental spray and combustion measurements of soy methyl-ester biodiesel. International Journal of Engine Research. 14(4):373-390. https://doi.org/10.1177/1468087412456688S373390144(2009). World Energy Outlook 2009. World Energy Outlook. doi:10.1787/weo-2009-enMonyem, A., & H. Van Gerpen, J. (2001). The effect of biodiesel oxidation on engine performance and emissions. Biomass and Bioenergy, 20(4), 317-325. doi:10.1016/s0961-9534(00)00095-7LAPUERTA, M., ARMAS, O., & RODRIGUEZFERNANDEZ, J. (2008). Effect of biodiesel fuels on diesel engine emissions. Progress in Energy and Combustion Science, 34(2), 198-223. doi:10.1016/j.pecs.2007.07.001Fisher, B. T., Knothe, G., & Mueller, C. J. (2010). Liquid-Phase Penetration under Unsteady In-Cylinder Conditions: Soy- and Cuphea-Derived Biodiesel Fuels Versus Conventional Diesel. Energy & Fuels, 24(9), 5163-5180. doi:10.1021/ef100594pFang, T., Lin, Y.-C., Foong, T. M., & Lee, C. (2009). Biodiesel combustion in an optical HSDI diesel engine under low load premixed combustion conditions. Fuel, 88(11), 2154-2162. doi:10.1016/j.fuel.2009.02.033Pastor, J. V., García-Oliver, J. M., Nerva, J.-G., & Giménez, B. (2011). Fuel effect on the liquid-phase penetration of an evaporating spray under transient diesel-like conditions. Fuel, 90(11), 3369-3381. doi:10.1016/j.fuel.2011.05.006Fisher, B. T., & Mueller, C. J. (2010). Liquid penetration length of heptamethylnonane and trimethylpentane under unsteady in-cylinder conditions. Fuel, 89(10), 2673-2696. doi:10.1016/j.fuel.2010.04.024Kim, H. J., Park, S. H., Suh, H. K., & Lee, C. S. (2009). Atomization and Evaporation Characteristics of Biodiesel and Dimethyl Ether Compared to Diesel Fuel in a High-Pressure Injection System. Energy & Fuels, 23(3), 1734-1742. doi:10.1021/ef800811gSuh, H. K., Roh, H. G., & Lee, C. S. (2008). Spray and Combustion Characteristics of Biodiesel∕Diesel Blended Fuel in a Direct Injection Common-Rail Diesel Engine. Journal of Engineering for Gas Turbines and Power, 130(3). doi:10.1115/1.2835354Pickett, L. M., & Siebers, D. L. (2006). Soot Formation in Diesel Fuel Jets Near the Lift-Off Length. International Journal of Engine Research, 7(2), 103-130. doi:10.1243/146808705x57793Pickett, L. M., Kook, S., Persson, H., & Andersson, Ö. (2009). Diesel fuel jet lift-off stabilization in the presence of laser-induced plasma ignition. Proceedings of the Combustion Institute, 32(2), 2793-2800. doi:10.1016/j.proci.2008.06.082Yoo, C. S., Richardson, E. S., Sankaran, R., & Chen, J. H. (2011). A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow. Proceedings of the Combustion Institute, 33(1), 1619-1627. doi:10.1016/j.proci.2010.06.147Pastor, J. V., Payri, R., Gimeno, J., & Nerva, J. G. (2009). Experimental Study on RME Blends: Liquid-Phase Fuel Penetration, Chemiluminescence, and Soot Luminosity in Diesel-Like Conditions. Energy & Fuels, 23(12), 5899-5915. doi:10.1021/ef9007328Benajes, J., Molina, S., Novella, R., & Amorim, R. (2010). Study on Low Temperature Combustion for Light-Duty Diesel Engines. Energy & Fuels, 24(1), 355-364. doi:10.1021/ef900832cPickett, L. M., & Siebers, D. L. (2002). An investigation of diesel soot formation processes using micro-orifices. Proceedings of the Combustion Institute, 29(1), 655-662. doi:10.1016/s1540-7489(02)80084-0Siebers, D. L., & Pickett, L. M. (2004). Injection Pressure and Orifice Diameter Effects on Soot in DI Diesel Fuel Jets. Thermo- and Fluid Dynamic Processes in Diesel Engines 2, 109-132. doi:10.1007/978-3-662-10502-3_7Pickett, L. M., & Siebers, D. L. (2004). Soot in diesel fuel jets: effects of ambient temperature, ambient density, and injection pressure. Combustion and Flame, 138(1-2), 114-135. doi:10.1016/j.combustflame.2004.04.006Cheng, A. S., Upatnieks, A., & Mueller, C. J. (2006). Investigation of the impact of biodiesel fuelling on NOx emissions using an optical direct injection diesel engine. International Journal of Engine Research, 7(4), 297-318. doi:10.1243/14680874jer05005Cheng, A. S. (Ed), Upatnieks, A., & Mueller, C. J. (2007). Investigation of Fuel Effects on Dilute, Mixing-Controlled Combustion in an Optical Direct-Injection Diesel Engine. Energy & Fuels, 21(4), 1989-2002. doi:10.1021/ef0606456Klein-Douwel, R. J. H., Donkerbroek, A. J., van Vliet, A. P., Boot, M. D., Somers, L. M. T., Baert, R. S. G., … ter Meulen, J. J. (2009). Soot and chemiluminescence in diesel combustion of bio-derived, oxygenated and reference fuels. Proceedings of the Combustion Institute, 32(2), 2817-2825. doi:10.1016/j.proci.2008.06.140Fang, T., & Lee, C. F. (2009). Bio-diesel effects on combustion processes in an HSDI diesel engine using advanced injection strategies. Proceedings of the Combustion Institute, 32(2), 2785-2792. doi:10.1016/j.proci.2008.07.031Payri, F., Pastor, J. V., Nerva, J.-G., & Garcia-Oliver, J. M. (2011). Lift-Off Length and KL Extinction Measurements of Biodiesel and Fischer-Tropsch Fuels under Quasi-Steady Diesel Engine Conditions. SAE International Journal of Engines, 4(2), 2278-2297. doi:10.4271/2011-24-0037Kook, S., & Pickett, L. M. (2012). Liquid length and vapor penetration of conventional, Fischer–Tropsch, coal-derived, and surrogate fuel sprays at high-temperature and high-pressure ambient conditions. Fuel, 93, 539-548. doi:10.1016/j.fuel.2011.10.004Settles, G. S. (2001). Schlieren and Shadowgraph Techniques. doi:10.1007/978-3-642-56640-0Pickett, L. M., Manin, J., Genzale, C. L., Siebers, D. L., Musculus, M. P. B., & Idicheria, C. A. (2011). Relationship Between Diesel Fuel Spray Vapor Penetration/Dispersion and Local Fuel Mixture Fraction. SAE International Journal of Engines, 4(1), 764-799. doi:10.4271/2011-01-0686MUSCULUS, M., & PICKETT, L. (2005). Diagnostic considerations for optical laser-extinction measurements of soot in high-pressure transient combustion environments. Combustion and Flame, 141(4), 371-391. doi:10.1016/j.combustflame.2005.01.013Williams, T. C., Shaddix, C. R., Jensen, K. A., & Suo-Anttila, J. M. (2007). Measurement of the dimensionless extinction coefficient of soot within laminar diffusion flames. International Journal of Heat and Mass Transfer, 50(7-8), 1616-1630. doi:10.1016/j.ijheatmasstransfer.2006.08.024Kook, S., & Pickett, L. M. (2011). Soot volume fraction and morphology of conventional and surrogate jet fuel sprays at 1000-K and 6.7-MPa ambient conditions. Proceedings of the Combustion Institute, 33(2), 2911-2918. doi:10.1016/j.proci.2010.05.073De Francqueville, L., Bruneaux, G., & Thirouard, B. (2010). Soot Volume Fraction Measurements in a Gasoline Direct Injection Engine by Combined Laser Induced Incandescence and Laser Extinction Method. SAE International Journal of Engines, 3(1), 163-182. doi:10.4271/2010-01-0346Musculus, M. P. B., & Kattke, K. (2009). Entrainment Waves in Diesel Jets. SAE International Journal of Engines, 2(1), 1170-1193. doi:10.4271/2009-01-1355Desantes, J. M., Pastor, J. V., García-Oliver, J. M., & Pastor, J. M. (2009). A 1D model for the description of mixing-controlled reacting diesel sprays. Combustion and Flame, 156(1), 234-249. doi:10.1016/j.combustflame.2008.10.008Idicheria, C. A., & Pickett, L. M. (2011). Ignition, soot formation, and end-of-combustion transients in diesel combustion under high-EGR conditions. International Journal of Engine Research, 12(4), 376-392. doi:10.1177/1468087411399505Aizawa, T., & Kosaka, H. (2008). Investigation of early soot formation process in a diesel spray flame via excitation—emission matrix using a multi-wavelength laser source. International Journal of Engine Research, 9(1), 79-97. doi:10.1243/14680874jer01407Bruneaux, G. (2008). Combustion structure of free and wall-impinging diesel jets by simultaneous laser-induced fluorescence of formaldehyde, poly-aromatic hydrocarbons, and hydroxides. 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Does involvement in a cohort study improve health and affect health inequalities? A natural experiment

Abstract Background Evidence suggests that the process of taking part in health research can improve participants\u2019 health, independent of any intended intervention. However, no research has yet explored whether these effects differ across socioeconomic groups. If the effect of mere participation in health research also has a social gradient this could increase health inequalities and bias research results. This study used the Born in Bradford family cohort (BIB) to explore whether simply taking part in BIB had improved participants\u2019 health and, if so, whether this effect was mediated by socioeconomic status. Methods Survey data on self-reported health behaviours were collected between 2007 and 2010 as part of BIB. These were augmented by clinical data on birth weight. Pregnant women on their second pregnancy, joining BIB for the first time formed the control group. Their health was compared to women on their second pregnancy who had both pregnancies within the study, who formed the exposed group. In order to limit the inherent bias in a non-randomised study, propensity score analysis was used, matching on age, ethnicity, education and date of questionnaire. The results were then compared according to mothers' education. Results Of six outcomes tested, only alcohol consumption showed a statistically significant reduction with exposure to BIB (OR: 0.35, 95% CIs 0.13, 0.92). Although effect estimates were larger for women with higher education compared to lower education, these effects were not statistically significant. Conclusions Despite one significant finding, these results overall are insufficient to conclude that simply taking part in BIB affected participants\u2019 health. We recommend that socioeconomic status is considered in future studies testing effects of research participation, and that randomised studies with larger sample sizes are conducted

Breaking the superfluid speed limit in a fermionic condensate

Coherent condensates appear as emergent phenomena in many systems. They share the characteristic feature of an energy gap separating the lowest excitations from the condensate ground state. This implies that a scattering object, moving through the system with high enough velocity for the excitation spectrum in the scatterer frame to become gapless, can create excitations at no energy cost, initiating the breakdown of the condensate—the well-known Landau velocity. Whereas, for the neutral fermionic superfluid 3He-B in the T = 0 limit, flow around an oscillating body displays a very clear critical velocity for the onset of dissipation, here we show that for uniform linear motion there is no discontinuity whatsoever in the dissipation as the Landau critical velocity is passed and exceeded. Given the importance of the Landau velocity for our understanding of superfluidity, this result is unexpected, with implications for dissipative effects of moving objects in all coherent condensate systems

Infochemical-tritrophic Interactions of Soybean Aphids-host Plants-natural Enemies and Their Practical Applications in Pest Management

The soybean aphid, Aphis glycines Matsumura, is a newly invasive insect species that seriously threatens U.S. soybean production. This aphid pest has kept haunting many soybean growers by developing large colonies on soybeans in North America since 2000. Since its first appearance inWisconsin, it has spread to over half of US states and southern provinces in Canada. The heavy infestation of this pest whittles soybean growers’ profits and causes hundreds of million dollar losses. The present chapter will mainly describe efforts in studying aphid chemical ecology and sensory physiology for understanding how male aphids find their mates and host plants. It will also cover research efforts to understand host plant associated volatiles being used as cues for overwintering host plant location. In addition, findings on how soybean plant defensive system works against aphid infestation, as well as how those induced plant volatiles are used by aphid’s natural enemies for prey location will be presented. Finally, the use the basic understandings for developing useful tools for soybean aphid practical control will be discussed

Gravitational Waves from Gravitational Collapse

Gravitational wave emission from the gravitational collapse of massive stars has been studied for more than three decades. Current state of the art numerical investigations of collapse include those that use progenitors with realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non--axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with advanced ground--based and future space--based interferometric observatories.Comment: 68 pages including 13 figures; revised version accepted for publication in Living Reviews in Relativity (http://www.livingreviews.org

The regional differences in prevalence, medical expenditures and risk factors for injury in Taiwanese teenagers

BACKGROUND: Injury is the leading cause of death in teenagers worldwide. In Taiwan, people in mountainous areas have a 4 to 8 years shorter life span than the general population. Injury among teenagers is likely a major cause. The objective of this study was to investigate the regional differences in the prevalence, the risk factors, and the medical expenditures for injury among Taiwanese teenagers. METHOD: An equal probability national sample was used. In addition, representative samples from mountainous areas and offshore islands were used. Only those who aged between 12 and 21 years, and signed the consent form permitting us to link their National Health Insurance (NHI) claim data were included in the analysis. Injury-related visits and expenditures in outpatient services were extracted from the NHI data. Logistic regression was used to examine the factors associated with injury. For those who had injury related outpatient visits, mixed model was used to examine the factors associated with medical expenditures accounting for multiple visits by the same individual. RESULTS: The prevalence of nonfatal injury was around 30% of teenagers in Taiwan. It was 10% higher in mountainous areas. Factors associated with injury were those who lived in mountainous areas (adjusted odds ratio [OR]: 1.7; 95%; confidence interval [CI]: 1.3–2.3), males (OR: 1.3; 95%; CI: 1.1–1.6), older teens (18–21 years old), and those with risk behavior were positively associated with injury. These factors were also associated with the number of injury-related outpatient visits. However, teenagers in mountainous areas did not spend more on medical care than those who lived in metropolitan Taiwan. CONCLUSION: Around 30% of the teenagers were injured in a year, not including the dead. Each of the injured spent at least 851.4NTD (~27USD) for outpatient visits. The scope of the problem was not trivial. Hazardous environments and high-risk behaviors were the universal causes. In remote areas, lack of medical resources was another possibility. Empowering local people to design prevention programs according to their needs is recommended

Fitting multilevel models in complex survey data with design weights: Recommendations

Abstract Background Multilevel models (MLM) offer complex survey data analysts a unique approach to understanding individual and contextual determinants of public health. However, little summarized guidance exists with regard to fitting MLM in complex survey data with design weights. Simulation work suggests that analysts should scale design weights using two methods and fit the MLM using unweighted and scaled-weighted data. This article examines the performance of scaled-weighted and unweighted analyses across a variety of MLM and software programs. Methods Using data from the 2005–2006 National Survey of Children with Special Health Care Needs (NS-CSHCN: n = 40,723) that collected data from children clustered within states, I examine the performance of scaling methods across outcome type (categorical vs. continuous), model type (level-1, level-2, or combined), and software (Mplus, MLwiN, and GLLAMM). Results Scaled weighted estimates and standard errors differed slightly from unweighted analyses, agreeing more with each other than with unweighted analyses. However, observed differences were minimal and did not lead to different inferential conclusions. Likewise, results demonstrated minimal differences across software programs, increasing confidence in results and inferential conclusions independent of software choice. Conclusion If including design weights in MLM, analysts should scale the weights and use software that properly includes the scaled weights in the estimation.</p

‘Fish out of water’: a cross-sectional study on the interaction between social and neighbourhood effects on weight management behaviours

Objective: To analyse whether an individual’s neighbourhood influences the uptake of weight management strategies and whether there is an interaction between individual socio-economic status and neighbourhood deprivation. Methodology: Data were collected from the Yorkshire Health Study (2010–2012) for 27 806 individuals on the use of the following weight management strategies: ‘slimming clubs’, ‘healthy eating’, ‘increasing exercise’ and ‘controlling portion size’. A multi-level logistic regression was fit to analyse the use of these strategies, controlling for age, sex, body mass index, education, neighbourhood deprivation and neighbourhood population turnover (a proxy for neighbourhood social capital). A cross-level interaction term was included for education and neighbourhood deprivation. Lower Super Output Area was used as the geographical scale for the areal unit of analysis. Results: Significant neighbourhood effects were observed for use of ‘slimming clubs’, ‘healthy eating’ and ‘increasing exercise’ as weight management strategies, independent of individual- and area-level covariates. A significant interaction between education and neighbourhood deprivation was observed across all strategies, suggesting that as an area becomes more deprived, individuals of the lowest education are more likely not to use any strategy compared with those of the highest education. Conclusions: Neighbourhoods modify/amplify individual disadvantage and social inequalities, with individuals of low education disproportionally affected by deprivation. It is important to include neighbourhood-based explanations in the development of community-based policy interventions to help tackle obesit