Treatment of atomic and molecular line blanketing by opacity sampling

An opacity sampling (OS) technique for treating the radiative opacity of large numbers of atomic and molecular lines in cool stellar atmospheres is presented. Tests were conducted and results show that the structure of atmospheric models is accurately fixed by the use of 1000 frequency points, and 500 frequency points is often adequate. The effects of atomic and molecular lines are separately studied. A test model computed by using the OS method agrees very well with a model having identical atmospheric parameters computed by the giant line (opacity distribution function) method

Physics Experiments For Online Courses

In 2007 a Faculty Technology Grant was awarded by the Office of the Provost, the Center for Teaching and Learning Excellence, and the Educational Technology Department of Embry-Riddle Aeronautical University (ERAU). The goal of the grant was to develop 8-10 experiments that could be used in an online physics class offered by the University. These experiments, designed to be performed totally online using the Internet, would introduce students to new instructional practices and involve them in an effective way in using the current technology. This paper is about the development of those experiments and how they have recently been incorporated into ERAU\u27s Worldwide curriculum

The Influence of Specimen Thickness on the High Temperature Corrosion Behavior of CMSX-4 during Thermal-Cycling Exposure

CMSX-4 is a single-crystalline Ni-base superalloy designed to be used at very high temperatures and high mechanical loadings. Its excellent corrosion resistance is due to external alumina-scale formation, which however can become less protective under thermal-cycling conditions. The metallic substrate in combination with its superficial oxide scale has to be considered as a composite suffering high stresses. Factors like different coefficients of thermal expansion between oxide and substrate during temperature changes or growing stresses affect the integrity of the oxide scale. This must also be strongly influenced by the thickness of the oxide scale and the substrate as well as the ability to relief such stresses, e.g., by creep deformation. In order to quantify these effects, thin-walled specimens of different thickness (t = 100500 lm) were prepared. Discontinuous measurements of their mass changes were carried out under thermal-cycling conditions at a hot dwell temperature of 1100 C up to 300 thermal cycles. Thin-walled specimens revealed a much lower oxide-spallation rate compared to thick-walled specimens, while thinwalled specimens might show a premature depletion of scale-forming elements. In order to determine which of these competetive factor is more detrimental in terms of a component’s lifetime, the degradation by internal precipitation was studied using scanning electron microscopy (SEM) in combination with energy-dispersive X-ray spectroscopy (EDS). Additionally, a recently developed statistical spallation model was applied to experimental data [D. Poquillon and D. Monceau, Oxidation of Metals, 59, 409–431 (2003)]. The model describes the overall mass change by oxide scale spallation during thermal cycling exposure and is a useful simulation tool for oxide scale spallation processes accounting for variations in the specimen geometry. The evolution of the net-mass change vs. the number of thermal cycles seems to be strongly dependent on the sample thickness

A three-dimensional model for stage I-crack propagation

The propagation of short fatigue cracks is simulated by means of a three-dimensional model. Under loading conditions in the high cycle fatigue regime the growth of these cracks can determine up to 90% of the lifetime of a component. Stage I-cracks often grow on slip bands and exhibit strong interactions with microstructural features such as grain boundaries. Experimental investigations have shown that the crack propagation rate decreases significantly when the crack tip approaches a grain boundary and even a complete stop of crack propagation is possible. In order to consider the real three-dimensional orientation of a slip plane an existing two-dimensional mechanism-based model (Künkler el al., 2008) is extended to simulate the propagation of a three-dimensional surface crack. The crack geometry is modelled using dislocation loops (Hills et al., 1996), which represent the relative displacement between the crack flanks. To describe the propagation of stage Icracks elastic-plastic material behaviour is considered by allowing a plastic deformation due to slip on the active slip plane. The extension of the plastic zone is blocked by the grain boundary. The crack propagation law is based on the range of the crack tip slide displacement, which is obtained from the plastic solution. Behind the grain boundary the shear stress field is evaluated. Results show that a high twist angle between the slip planes causes a significant decrease in the stresses, which can yield a crack stop

Effect of 475 °C embrittlement on the mechanical properties of duplex stainless steel

The binary iron–chromium alloy embrittles in the temperature range of 280–500 °C limiting its applications to temperatures below 280 °C. The embrittlement is caused by the decomposition of the alloy to chromium-rich phase, α′ and iron-rich phase, α. This phenomenon is termed 475 °C embrittlement as the rate of embrittlement is highest at 475 °C. Primarily the investigations on 475 °C embrittlement were confined to binary iron–chromium alloys and ferritic stainless steels. Duplex stainless steel grades contain varying proportions of ferrite and austenite in the microstructure and the ferritic phase is highly alloyed. Moreover, this grade of steel has several variants depending on the alloy composition and processing route. This modifies the precipitation behaviour and the resulting change in mechanical properties in duplex stainless steels when embrittled at 475 °C as compared to binary iron chromium systems. The precipitation behaviour of duplex stainless steel at 475 °C and the effect on tensile, fracture and fatigue behaviour are reviewed in this article

Are marginalized women being left behind? A population based study of institutional births in Rural India

Background While India has made significant progress in reducing maternal mortality, attaining further declines will require increased skilled birth attendance and institutional delivery among marginalized and difficult to reach populations. Methods A population-based survey was carried out among 16 randomly selected rural villages in rural Mysore District in Karnataka, India between August and September 2008. All households in selected villages were enumerated and women with children 6 years of age or younger underwent an interviewer-administered questionnaire on antenatal care and institutional delivery. Results Institutional deliveries in rural areas of Mysore District increased from 51% to 70% between 2002 and 2008. While increasing numbers of women were accessing antenatal care and delivering in hospitals, large disparities were found in uptake of these services among different castes. Mothers belonging to general castes were almost twice as likely to have an institutional birth as compared to scheduled castes and tribes. Mothers belonging to other backward caste or general castes had 1.8 times higher odds (95% CI: 1.21, 2.89) of having an institutional delivery as compared to scheduled castes and tribes. In multivariable analysis, which adjusted for inter- and intra-village variance, Below Poverty Line status, caste, and receiving antenatal care were all associated with institutional delivery. Conclusion The results of the study suggest that while the Indian Government has made significant progress in increasing antenatal care and institutional deliveries among rural populations, further success in lowering maternal mortality will likely hinge on the success of NRHM programs focused on serving marginalized groups. Health interventions which target SC/ST may also have to address both perceived and actual stigma and discrimination, in addition to providing needed services. Strategies for overcoming these barriers may include sensitization of healthcare workers, targeted health education and outreach, and culturally appropriate community-level interventions. Addressing the needs of these communities will be critical to achieving Millennium Development Goal Five by 2015

Environmental effects on arsenosugars and arsenolipids in Ectocarpus (Phaeophyta)

We thank Gillian Milne, of the Aberdeen Microscopy Facility, University of Aberdeen, for help in preparing and viewing the samples through TEM and Ingo Maier, from the Universita¨t Konstanz, for kindly providing us with an optimised processing schedule for the fixation of Ectocarpus for TEM. We also express our gratitude to Dawn Shewring for her help with algal culturing. A´ . H. Petursdo´ttir thanks the Icelandic research fund (grant reference 130542–051), the SORSAS award and The College of Physical Sciences at Aberdeen University for financial support. F. C. Ku¨pper also received funding from the MASTS (The Marine Alliance for Science and Technology for Scotland) pooling initiative and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.Peer reviewedPublisher PD

Microwave radiometric observations near 19.35, 92 and 183 GHz of precipitation in tropical storm Cora

Observations of rain cells in the remains of a decaying tropical storm were made by Airborne Microwave Radiometers at 19.35,92 and three frequencies near 183 GHz. Extremely low brightness temperatures, as low as 140 K were noted in the 92 and 183 GHz observations. These can be accounted for by the ice often associated with raindrop formation. Further, 183 GHz observations can be interpreted in terms of the height of the ice. The brightness temperatures observed suggest the presence of precipitation sized ice as high as 9 km or more

Are marginalized women being left behind? A population-based study of institutional deliveries in Karnataka, India

<p>Abstract</p> <p>Background</p> <p>While India has made significant progress in reducing maternal mortality, attaining further declines will require increased skilled birth attendance and institutional delivery among marginalized and difficult to reach populations.</p> <p>Methods</p> <p>A population-based survey was carried out among 16 randomly selected rural villages in rural Mysore District in Karnataka, India between August and September 2008. All households in selected villages were enumerated and women with children 6 years of age or younger underwent an interviewer-administered questionnaire on antenatal care and institutional delivery.</p> <p>Results</p> <p>Institutional deliveries in rural areas of Mysore District increased from 51% to 70% between 2002 and 2008. While increasing numbers of women were accessing antenatal care and delivering in hospitals, large disparities were found in uptake of these services among different castes. Mothers belonging to general castes were almost twice as likely to have an institutional birth as compared to scheduled castes and tribes. Mothers belonging to other backward caste or general castes had 1.8 times higher odds (95% CI: 1.21, 2.89) of having an institutional delivery as compared to scheduled castes and tribes. In multivariable analysis, which adjusted for inter- and intra-village variance, Below Poverty Line status, caste, and receiving antenatal care were all associated with institutional delivery.</p> <p>Conclusion</p> <p>The results of the study suggest that while the Indian Government has made significant progress in increasing antenatal care and institutional deliveries among rural populations, further success in lowering maternal mortality will likely hinge on the success of NRHM programs focused on serving marginalized groups. Health interventions which target SC/ST may also have to address both perceived and actual stigma and discrimination, in addition to providing needed services. Strategies for overcoming these barriers may include sensitization of healthcare workers, targeted health education and outreach, and culturally appropriate community-level interventions. Addressing the needs of these communities will be critical to achieving Millennium Development Goal Five by 2015.</p

Rain observations in tropical storm Cora

Passive microwave observations were made in tropical storm Cora at 19.35 and 94GHz. These observations suggest that 94GHz is appropriate for mapping the extent of rain over either land or ocean backgrounds and that some rainfall intensity measurement is also possible