Microbial mats in playa lakes and other saline habitats: Early Mars analog?

Microbial mats are cohesive benthic microbial communities which inhabit various Terra (Earth-based) environments including the marine littoral and both permanent and ephemeral (playa) saline lakes. Certain geomorphological features of Mars, such as the Margaritifer Sinus, were interpreted as ancient, dried playa lakes, presumably formed before or during the transition to the present Mars climate. Studies of modern Terran examples suggest that microbial mats on early Mars would have had the capacity to survive and propagate under environmental constraints that would have included irregularly fluctuating regimes of water activity and high ultraviolet flux. Assuming that such microbial communities did indeed inhabit early Mars, their detection during the Mars Rover Sample Return (MRSR) mission depends upon the presence of features diagnostic of the prior existence of these communities or their component microbes or, as an aid to choosing suitable landing, local exploration or sampling sites, geomorphological, sedimentological or chemical features characteristic of their playa lake habitats. Examination of modern Terran playas (e.g., the Lake Eyre basin) shows that these features span several orders of magnitude in size. While stromatolites are commonly centimeter-meter scale features, bioherms or fields of individuals may extend to larger scales. Preservation of organic matter (mats and microbes) would be favored in topographic lows such as channels or ponds of high salinity, particularly those receiving silica-rich groundwaters. These areas are likely to be located near former zones of groundwater emergence and/or where flood channels entered the paleo-playa. Fossil playa systems which may aid in assessing the applicability of this particular Mars analog include the Cambrian Observatory Hill Beds of the Officer Basin and the Eocene Wilkins Peak Member of the Green River Formation

Cost-effectiveness of financial incentives for smoking cessation in pregnancy

No abstract available

Science Section

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An investigation of the accuracy of finite difference methods in the solution of linear elasticity problems

The accuracy of the finite difference method in the solution of linear elasticity problems that involve either a stress discontinuity or a stress singularity is considered. Solutions to three elasticity problems are discussed in detail: a semi-infinite plane subjected to a uniform load over a portion of its boundary; a bimetallic plate under uniform tensile stress; and a long, midplane symmetric, fiber reinforced laminate subjected to uniform axial strain. Finite difference solutions to the three problems are compared with finite element solutions to corresponding problems. For the first problem a comparison with the exact solution is also made. The finite difference formulations for the three problems are based on second order finite difference formulas that provide for variable spacings in two perpendicular directions. Forward and backward difference formulas are used near boundaries where their use eliminates the need for fictitious grid points

Why I'm fighting alcohol industry obstruction of minimum pricing

First paragraph: Exactly a year after minimum alcohol pricing was supposed to have been introduced in Scotland, this week a group of public health professionals including myself registered a protest against the fact that it is still not in place. Access the article on The conversation website: https://theconversation.com/why-im-fighting-alcohol-industry-obstruction-of-minimum-pricing-2512

Smoking during pregnancy and smoking cessation services

The 2008 UK National Smoking Cessation Conference (UKNSSC) included a number of oral and poster presentations on the theme of smoking during pregnancy. This is a challenging area of research and practice and one in which new evidence - both about the effects of smoking in pregnancy and about smoking cessation interventions - is regularly emerging. Papers at UKNSCC explored why few women access support to stop (Felix Naughton), how best to refer women to specialist services (Joan Braithwaite), social marketing approaches (Deborah Richardson and Wendy Dudley) and physical activity for smoking cessation during pregnancy (Michael Ussher). The conference opened with a plenary presentation that explored the extent of smoking during pregnancy and women's accounts of quit attempts, cessation and relapse. It also examined what more could be done to improve access to stop smoking services for pregnant women and increase the proportion of women who quit. This article reviews some of the evidence presented at UKNSSC, focusing in particular on the need for improved identification, referral, engagement and treatment of pregnant smokers

Explainer: what do we know about e-cigarettes?

First paragraph: E-cigarettes are increasingly popular in a number of countries including the UK, while in others such as Norway and Brazil they are banned altogether. Read article on The Conversation website: https://theconversation.com/explainer-what-do-we-know-about-e-cigarettes-2261

E-cigarette use in public places: striking the right balance

First paragraph: The availability, marketing and use of electronic cigarettes or nicotine vapourisers is subject to a range of regulations across different countries, varying from the prohibition of sales and use, to little or no regulation. The most common approach adopted in countries that permit some use of e-cigarettes has been to adapt existing laws or frameworks designed for tobacco products to include e-cigarettes. This can include extending bans on tobacco advertising to e-cigarettes, applying the same age of sale laws or taxing e-cigarettes like tobacco. In some jurisdictions including many Canadian provinces and US states, existing smoke-free public places laws have also been amended to include e-cigarettes, so that vaping is prohibited wherever tobacco cannot be used—including enclosed public places, workplaces and some outdoor areas. But is this the right approach, and is it supported by research evidence

Organic solar cells: electrodes, performance enhancement and degradation mechanisms

In this thesis I focus on a number of aspects associated with the fabrication and characterization of organic photovoltaics. Specifically, my work focuses on evaluating solution processed graphene electrodes for use in organic photovoltaics, improving the performance of indium tin oxide transparent contacts by coating them with Au nanoparticles, and understanding the degradation pathways of Poly(3-hexylthiophene-2,5-diyl): Phenyl-C61-butyric acid methyl ester (P3HT:PCBM) organic solar cells. In my work on graphene electrodes for organic solar cells I worked out a relationship between the sheet resistance and the film transmittance that is useful to optimize such electrodes. Investigation of organic solar cell degradation in a controlled 70-70-70 test (i.e. keeping a device for 70 hours at 70oC under 70% humidity conditions) showed several possible pathways in which the active layer of these photovoltaics degrade. In addition to the typical morphological degradation, a strong increase in paramagnetic defect density in the active layer contributes to their degradation. Formation of paramagnetic defects in P3HT:PCBM layers was attributed by us to the creation of charge transfer complexes between P3HT and oxygen. Our attempts on improving indium tin oxide electrodes for their use in organic photovoltaics included a study of the effects of nucleation of Au-containing molecular nanoclusters. It was discovered that different types of Au nanoparticles with specific properties can be formed by annealing such clusters at different temperatures and under different conditions. This discovery was utilized to fabricate Au nanoparticle layers on indium tin oxide which were then utilized as plasmonic enhancement layers for organic solar cells