Evaluation of the performance of different atmospheric chemical transport models and inter-comparison of nitrogen and sulphur deposition estimates for the UK

An evaluation has been made of a number of contrasting atmospheric chemical transport models, of varying complexity, applied to estimate sulphur and nitrogen deposition in the UK. The models were evaluated by comparison with annually averaged measurements of gas, aerosol and precipitation concentrations from the national monitoring networks. The models were evaluated in relation to performance criteria. They were generally able to satisfy a criterion of ‘fitness for purpose’ that at least 50% of modelled concentrations should be within a factor of two of measured values. The second criterion, that the magnitude of the normalised mean bias should be less than 20%, was not always satisfied. Considering known uncertainties in measurement techniques, this criterion may be too strict. Overall, simpler models were able to give a good representation of measured gas concentrations whilst the use of dynamic meteorology, and complex photo-chemical reactions resulted in a generally better representation of measured aerosol and precipitation concentrations by more complex models. The models were compared graphically by plotting maps and cross-country transects of wet and dry deposition as well as calculating budgets of total wet and dry deposition to the UK for sulphur, oxidised nitrogen and reduced nitrogen. The total deposition to the UK varied by ±22–36% amongst the different models depending on the deposition component. At a local scale estimates of both dry and wet deposition for individual 5 km × 5 km model grid squares were found to vary between the different models by up to a factor of 4.This work was funded by the Department for the Environment, Food and Rural Affairs. Additional support was provided by the Joint Environmental Program, the Natural Environment Research Council and the Environment Agency.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.atmosenv.2015.08.00

Earliest rock fabric formed in the Solar System preserved in a chondrule rim

Rock fabrics – the preferred orientation of grains – provide a window into the history of rock formation, deformation and compaction. Chondritic meteorites are among the oldest materials in the Solar System1 and their fabrics should record a range of processes occurring in the nebula and in asteroids, but due to abundant fine-grained material these samples have largely resisted traditional in situ fabric analysis. Here we use high resolution electron backscatter diffraction to map the orientation of sub-micrometre grains in the Allende CV carbonaceous chondrite: the matrix material that is interstitial to the mm-sized spherical chondrules that give chondrites their name, and fine-grained rims which surround those chondrules. Although Allende matrix exhibits a bulk uniaxial fabric relating to a significant compressive event in the parent asteroid, we find that fine-grained rims preserve a spherically symmetric fabric centred on the chondrule. We define a method that quantitatively relates fabric intensity to net compression, and reconstruct an initial porosity for the rims of 70-80% - a value very close to model estimates for the earliest uncompacted aggregates2,3. We conclude that the chondrule rim textures formed in a nebula setting and may therefore be the first rock fabric to have formed in the Solar System

Knowledge, perceptions and myths regarding infertility among selected adult population in Pakistan: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>The reported prevalence of infertility in Pakistan is approximately 22% with 4% primary and 18% secondary infertility. Infertility is not only a medical but also a social problem in our society as cultural customs and perceived religious dictums may equate infertility with failure on a personal, interpersonal, or social level. It is imperative that people have adequate knowledge about infertility so couples can seek timely medical care and misconceptions can be rectified.</p> <p>We aim to assess the knowledge, perception and myths regarding infertility and suggest ways to improve it.</p> <p>Methods</p> <p>A cross-sectional survey was carried out by interviewing a sample of 447 adults who were accompanying the patients at two tertiary care hospitals in Karachi, Pakistan. They were interviewed one-on-one with the help of a pretested questionnaire drafted by the team after a thorough literature review and in consultation with infertility specialists.</p> <p>Results</p> <p>The correct knowledge of infertility was found to be limited amongst the participants. Only 25% correctly identified when infertility is pathological and only 46% knew about the fertile period in women's cycle. People are misinformed that use of IUCD (53%) and OCPs (61%) may cause infertility. Beliefs in evil forces and supernatural powers as a cause of infertility are still prevalent especially amongst people with lower level of education. Seeking alternative treatment for infertility remains a popular option for 28% of the participant as a primary preference and 75% as a secondary preference. IVF remains an unfamiliar (78%) and an unacceptable option (55%).</p> <p>Conclusions</p> <p>Knowledge about infertility is limited in the population and a lot of misconceptions and myths are prevalent in the society. Alternative medicine is a popular option for seeking infertility treatment. The cultural and religious perspective about assisted reproductive technologies is unclear, which has resulted in its reduced acceptability.</p

Predation and the Maintenance of Color Polymorphism in a Habitat Specialist Squamate

Multiple studies have addressed the mechanisms maintaining polymorphism within a population. However, several examples exist where species inhabiting diverse habitats exhibit local population-specific polymorphism. Numerous explanations have been proposed for the maintenance of geographic variation in color patterns. For example, spatial variation in patterns of selection or limited gene flow can cause entire populations to become fixed for a single morph, resulting in separate populations of the same species exhibiting separate and distinct color morphs. The mottled rock rattlesnake (Crotalus lepidus lepidus) is a montane species that exhibits among-population color polymorphism that correlates with substrate color. Habitat substrate in the eastern part of its range is composed primarily of light colored limestone and snakes have light dorsal coloration, whereas in the western region the substrate is primarily dark and snakes exhibit dark dorsal coloration. We hypothesized that predation on high contrast color and blotched patterns maintain these distinct color morphs. To test this we performed a predation experiment in the wild by deploying model snakes at 12 sites evenly distributed within each of the two regions where the different morphs are found. We employed a 2×2 factorial design that included two color and two blotched treatments. Our results showed that models contrasting with substrate coloration suffered significantly more avian attacks relative to models mimicking substrates. Predation attempts on blotched models were similar in each substrate type. These results support the hypothesis that color pattern is maintained by selective predation

A latent growth curve model to estimate electronic screen use patterns amongst adolescents aged 10 to 17 years

Background: High quality, longitudinal data describing young people's screen use across a number of distinct forms of screen activity is missing from the literature. This study tracked multiple screen use activities (passive screen use, gaming, social networking, web searching) amongst 10- to 17-year-old adolescents across 24 months. Methods: This study tracked the screen use of 1948 Australian students in Grade 5 (n = 636), Grade 7 (n = 672), and Grade 9 (n = 640) for 24 months. At approximately six-month intervals, students reported their total screen time as well as time spent on social networking, passive screen use, gaming, and web use. Patterns of screen use were determined using latent growth curve modelling. Results: In the Grades 7 and 9 cohorts, girls generally reported more screen use than boys (by approximately one hour a day), though all cohorts of boys reported more gaming. The different forms of screen use were remarkably stable, though specific cohorts showed change for certain forms of screen activity. Conclusion: These results highlight the diverse nature of adolescent screen use and emphasise the need to consider both grade and sex in future research and policy

The Prevalence and Drug Sensitivity of Tuberculosis among Patients Dying in Hospital in KwaZulu-Natal, South Africa: A Postmortem Study

A postmortem study by Ted Cohen and colleagues reveals a huge toll of tuberculosis among patients dying in hospitals in KwaZulu-Natal, South Africa