Forming super-Mercuries: The role of stellar abundances

Super-Mercuries, rocky exoplanets with bulk iron mass fraction of more than 60 per cent, appear to be preferentially hosted by stars with higher iron mass fraction than the Earth. It is unclear whether these iron-rich planets can form in the disc, or if giant impacts are necessary. Here we investigate the formation of super-Mercuries in their natal protoplanetary discs by taking into account their host stars' abundances (Fe, Mg, Si, S). We employ a disc evolution model which includes the growth, drift, evaporation and recondensation of pebbles to compute the pebble iron mass fraction. The recondensation of outward-drifting iron vapour near the iron evaporation front is the key mechanism that facilitates an increase in the pebble iron mass fraction. We also simulate the growth of planetary seeds around the iron evaporation front using a planet formation model which includes pebble accretion and planet migration, and compute the final composition of the planets. Our simulations are able to reproduce the observed iron compositions of the super-Mercuries provided that all the iron in the disc are locked in pure Fe grains and that the disc viscosity is low. The combined effects of slow orbital migration of planets and long retention time of iron vapour in low-viscosity discs makes it easier to form iron-rich planets. Furthermore, we find that decreasing the stellar Mg/Si ratio results in an increase in the iron mass fraction of the planet due to a reduction in the abundance of Mg2SiO4, which has a very similar condensation temperature as iron, in the disc. Our results thus imply that super-Mercuries are more likely to form around stars with low Mg/Si, in agreement with observational data.Comment: 9 pages, 6 figures, accepted for publication in A&

Evidence for Allelopathic Activity of Mikania micrantha H.B.K. on Three Weed Species

Laboratory, greenhouse and field studies were conducted to determine the allelopathic potential of Mikania micrantha H.B.K. on the germination and growth of three weed species, A.systasia gangetica (L.) T. Anders., Chrysopogon aciculatus (Ritz.) Trin and Paspalum conjugatum Berg. Germination and fresh weight of all three weeds decreased progressively when exposed to increasing concentrations of aqueous leaf or root extract of Mikania. The phytotoxic effect of root extract on the radicle elongation of the test species was greater than that of leaf extract. The dry weight and rate of emergence of the bioassay species used were affected when Mikania debris (leaf or root) were placed on soil surfaces or incorporated into the soil. P. conjugatum emergence was strongly affected when Mikania (root orleaf) was incorporated into the soil. Soil collectedfrom the field where Mikania had been growing had no effecton the final germination of the three weed species. However, dry weights of A. gangetica and P. conjugatum were significantly reduced when grown in the Mikanilt-infested so

Global Diversity and Phylogeny of the Asteroidea (Echinodermata)

Members of the Asteroidea (phylum Echinodermata), popularly known as starfish or sea stars, are ecologically important and diverse members of marine ecosystems in all of the world's oceans. We present a comprehensive overview of diversity and phylogeny as they have figured into the evolution of the Asteroidea from Paleozoic to the living fauna. Living post-Paleozoic asteroids, the Neoasteroidea, are morphologically separate from those in the Paleozoic. Early Paleozoic asteroid faunas were diverse and displayed morphology that foreshadowed later living taxa. Preservation presents significant difficulties, but fossil occurrence and current accounts suggests a diverse Paleozoic fauna, which underwent extinction around the Permian-Triassic interval was followed by re-diversification of at least one surviving lineage. Ongoing phylogenetic classification debates include the status of the Paxillosida and the Concentricycloidea. Fossil and molecular evidence has been and continues to be part of the ongoing evolution of asteroid phylogenetic research. The modern lineages of asteroids include the Valvatacea, the Forcipulatacea, the Spinlosida, and the Velatida. We present an overview of diversity in these taxa, as well as brief notes on broader significance, ecology, and functional morphology of each. Although much asteroid taxonomy is stable, many new taxa remain to be discovered with many new species currently awaiting description. The Goniasteridae is currently one of the most diverse families within the Asteroidea. New data from molecular phylogenetics and the advent of global biodiversity databases, such as the World Asteroidea Database (http://www.marinespecies.org/Asteroidea/) present important new springboards for understanding the global biodiversity and evolution of asteroids

Critical appraisal of bepotastine in the treatment of ocular itching associated with allergic conjunctivitis

Bepotastine besilate 1.5% solution is an H1-antihistamine recently approved by the Food and Drug Administration for the topical treatment of ocular itching associated with allergic conjunctivitis. Several clinical studies have demonstrated its safety as well as its efficacy versus placebo. This review finds that bepotastine besilate 1.5% solution is a suitable alternative to other agents within the class of H1-antihistamines, but there are no clinical trial data to suggest that it holds any specific advantages over other agents

Close-in ice lines and the super-stellar C/O ratio in discs around very low-mass stars

The origin of the elevated C/O ratios in discs around late M dwarfs compared to discs around solar-type stars is not well understood. Here we endeavour to reproduce the observed differences in the disc C/O ratios as a function of stellar mass using a viscosity-driven disc evolution model and study the corresponding atmospheric composition of planets that grow inside the water-ice line in these discs. We carried out simulations using a coupled disc evolution and planet formation code that includes pebble drift and evaporation. We used a chemical partitioning model for the dust composition in the disc midplane. Inside the water-ice line, the disc's C/O ratio initially decreases to sub-stellar due to the inward drift and evaporation of water-ice-rich pebbles before increasing again to super-stellar values due to the inward diffusion of carbon-rich vapour. We show that this process is more efficient for very low-mass stars compared to solar-type stars due to the closer-in ice lines and shorter disc viscous timescales. In high-viscosity discs, the transition from sub-stellar to super-stellar takes place faster due to the fast inward advection of carbon-rich gas. Our results suggest that planets accreting their atmospheres early (when the disc C/O is still sub-stellar) will have low atmospheric C/O ratios, while planets that accrete their atmospheres late (when the disc C/O has become super-stellar) can obtain high C/O ratios. Our model predictions are consistent with observations, under the assumption that all stars have the same metallicity and chemical composition, and that the vertical mixing timescales in the inner disc are much shorter than the radial advection timescales. This further strengthens the case for considering stellar abundances alongside disc evolution in future studies that aim to link planet (atmospheric) composition to disc composition.Comment: Accepted for publication in A&

The intersection of gender and race/ethnicity in smoking behaviors among menthol and non-menthol smokers in the United States

To determine whether menthol is related to initiation, quantity or quitting, we examined differences in smoking behaviors among menthol and non-menthol smokers, stratified by gender and race/ethnicity, and adjusting for age, income and educational attainment.Cross-sectional, using data from the 2005 National Health Interview Survey and Cancer Control Supplement.United States.Black, Hispanic and white women and men aged 25–64 years.For each group, we examined (i) proportion of menthol smokers (comparing current and former smokers); (ii) age of initiation, cigarettes smoked per day and quit attempt in the past year (comparing menthol and non-menthol current smokers); and (iii) time since quitting (comparing menthol and non-menthol former smokers). We calculated predicted values for each demographic group, adjusting for age, income and educational attainment.After adjusting for age, income and education, black (compared with Hispanic and white) and female (compared with male) smokers were more likely to choose menthol cigarettes. There was only one statistically significant difference in age of initiation, cigarettes smoked per day, quit attempts or time since quitting between menthol and non-menthol smokers: white women who smoked menthol cigarettes reported longer cessation compared with those who smoked non-menthol cigarettes.The results do not support the hypothesis that menthol smokers initiate earlier, smoke more or have a harder time quitting compared with non-menthol smokers. A menthol additive and the marketing of it, given the clear demographic preferences demonstrated here, however, may be responsible for enticing the groups least likely to smoke into this addictive behavior.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79098/1/j.1360-0443.2010.03191.x.pd

Barriers to self-monitoring of blood glucose among adults with diabetes in an HMO: A cross sectional study

BACKGROUND: Recent studies suggest that patients at greatest risk for diabetes complications are least likely to self-monitor blood glucose. However, these studies rely on self-reports of monitoring, an unreliable measure of actual behavior. The purpose of the current study was to examine the relationship between patient characteristics and self-monitoring in a large health maintenance organization (HMO) using test strips as objective measures of self-monitoring practice. METHODS: This cross-sectional study included 4,565 continuously enrolled adult managed care patients in eastern Massachusetts with diabetes. Any self-monitoring was defined as filling at least one prescription for self-monitoring test strips during the study period (10/1/92–9/30/93). Regular SMBG among test strip users was defined as testing an average of once per day for those using insulin and every other day for those using oral sulfonylureas only. Measures of health status, demographic data, and neighborhood socioeconomic status were obtained from automated medical records and 1990 census tract data. RESULTS: In multivariate analyses, lower neighborhood socioeconomic status, older age, fewer HbA1c tests, and fewer physician visits were associated with lower rates of self-monitoring. Obesity and fewer comorbidities were also associated with lower rates of self-monitoring among insulin-managed patients, while black race and high glycemic level (HbA1c>10) were associated with less frequent monitoring. For patients taking oral sulfonylureas, higher dose of diabetes medications was associated with initiation of self-monitoring and HbA1c lab testing was associated with more frequent testing. CONCLUSIONS: Managed care organizations may face the greatest challenges in changing the self-monitoring behavior of patients at greatest risk for poor health outcomes (i.e., the elderly, minorities, and people living in low socioeconomic status neighborhoods)

Design of a pulse power supply unit for micro-ECM

Electrochemical micro-machining (μECM) requires a particular pulse power supply unit (PSU) to be developed in order to achieve desired machining performance. This paper summarises the development of a pulse PSU meeting the requirements of μECM. The pulse power supply provides tens of nanosecond pulse duration, positive and negative bias voltages and a polarity switching functionality. It fulfils the needs for tool preparation with reversed pulsed ECM on the machine. Moreover, the PSU is equipped with an ultrafast overcurrent protection which prevents the tool electrode from being damaged in case of short circuits. The developed pulse PSU was used to fabricate micro-tools out of 170 μm WC-Co alloy shafts via micro-electrochemical turning and drill deep holes via μECM in a disk made of 18NiCr6. The electrolyte used for both processes was a mixture of sulphuric acid and NaNO3 aqueous solutions.The research reported in this paper is supported by the European Commission within the project “Minimizing Defects in Micro-Manufacturing Applications (MIDEMMA)” (FP7-2011-NMP-ICT-FoF-285614

Polycrystalline Yttrium Aluminum Garnet Fibers from Colloidal Sols

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66320/1/j.1151-2916.1995.tb08626.x.pd