Theoretical Investigation of The X-Ray Stark Effect in Small Molecules

We have studied the Stark effect in the soft x-ray region for various small molecules by calculating the field-dependent x-ray absorption spectra. This effect is explained in terms of the response of molecular orbitals (core and valence), the molecular dipole moment, and the molecular geometry to the applied electric field. A number of consistent trends are observed linking the computed shifts in absorption energies and intensities with specific features of the molecular electronic structure. We find that both the virtual molecular orbitals (valence and/or Rydberg) as well as the core orbitals contribute to observed trends in a complementary fashion. This initial study highlights the potential impact of x-ray Stark spectroscopy as a tool to study electronic structure and environmental perturbations at a sub-molecular scale.Comment: 33 pages, 9 figures, 7 tables, supporting information files availabl

A comparison of theoretical line intensity ratios for Ni XII with extreme ultraviolet observations from the JET tokamak

Recent R-matrix calculations of electron impact excitation rates in Ni XII are used to derive the emission line ratios R1 = I (154.17 Å)/I (152.15 Å), R2 = I (152.95 Å)/I (152.15 Å) and R3 = I (160.55 Å)/I (152.15 Å). This is the first time (to our knowledge) that theoretical emission line ratios have been calculated for this ion. The ratios are found to be insensitive to changes in the adopted electron density (Ne) when Ne >= 5 × 10^11 cm−3, typical of laboratory plasmas. However, they do vary with electron temperature (Te), with for example R1 and R3 changing by factors of 1.3 and 1.8, respectively, between Te = 10^5 and 10^6 K. A comparison of the theoretical line ratios with measurements from the Joint European Torus (JET) tokamak reveals very good agreement between theory and observation for R1, with an average discrepancy of only 7%. Agreement between the calculated and experimental ratios for R2 and R3 is less satisfactory, with average differences of 30 and 33%, respectively. These probably arise from errors in the JET instrument calibration curve. However, the discrepancies are smaller than the uncertainties in the R2 and R3 measurements. Our results, in particular for R1, provide experimental support for the accuracy of the Ni XII line ratio calculations, and hence for the atomic data adopted in their derivation

Public perceptions of drinking water: A postal survey of residents with private water supplies

Background: In Canada, the legal responsibility for the condition of private water supplies, including private wells and cisterns, rests with their owners. However, there are reports that Canadians test these water supplies intermittently and that treatment of such water is uncommon. An estimated 45% of all waterborne outbreaks in Canada involve non-municipal systems. An understanding of the perceptions and needs of Canadians served by private water supplies is essential, as it would enable public health professionals to better target public education and drinking water policy. The purpose of this study was to investigate the public perceptions of private water supplies in the City of Hamilton, Ontario (Canada), with the intent of informing public education and outreach strategies within the population. Methods: A cross-sectional postal survey of 246 residences with private water supplies was conducted in May 2004. Questions pertained to the perceptions of water quality and alternative water sources, water testing behaviours and the self-identified need for further information. Results: Private wells, cisterns or both, were the source of household water for 71%, 16% and 13% of respondents, respectively. Although respondents rated their water quality highly, 80% also had concerns with its safety. The most common concerns pertained to bacterial and chemical contamination of their water supply and its potential negative effect on health. Approximately 56% and 61% of respondents used in-home treatment devices and bottled water within their homes, respectively, mainly due to perceived improvements in the safety and aesthetic qualities compared to regular tap water. Testing of private water supplies was performed infrequently: 8% of respondents tested at a frequency that meets current provincial guidelines. Two-thirds of respondents wanted more information on various topics related to private water supplies. Flyers and newspapers were the two media reported most likely to be used. Conclusion: Although respondents rated their water quality highly, the majority had concerns regarding the water from their private supply, and the use of bottled water and water treatment devices was extensive. The results of this study suggest important lines of inquiry and provide support and input for public education programs, particularly those related to private water testing, in this population

Universal Design for Learning with Elementary Science

Universal design for learning (UDL) continues to be a topic of interest as teachers search for instructional strategies and activities to differentiate the general curriculum. This differentiation should provide access to and successful engagement with the curriculum for all students, including learners who have unique educational needs. Described here is an elementary science lesson on temperature planned and implemented using the principles of UDL. This example is offered that so that teachers may be encouraged to plan and implement instruction by using UDL principles in meeting diverse student learning goals

(Dis)Solving the Differences: A Physical Science Lesson Using Universal Design

Universal design for learning (UDL) holds promise for teachers who are struggling with creating lessons that allow all students access to and engagement with the general science curriculum. In this article, the authors demonstrate how a secondary physical science lesson about solubility and concentration can be designed for diverse learners’ needs by implementing UDL concepts. The lesson plan serves as an example of UDL in providing appropriate instruction that supports access to the general physical science curriculum for all learners

The Trouble with Textbooks

Some of these dilemmas are under close scrutiny. According to the American Association for the Advancement of Science (AAAS), 12 of the most popular middle school science textbooks used across the nation are riddled with errors and do not have an acceptable level of accuracy (AAAS, 2000a). In addition to this alarming information, the AAAS review of the 10 most popular high school biology text-books found numerous facts, but little to explain the underlying scientific importance of the facts. The evaluators rated all 10 textbooks poor in "demonstrating use of knowledge" and "encouraging students to reflect on their own learning" (Hoff, 2000).These reports about textbooks present serious dilemmas for most science teachers who believe that textbooks play a major role in middle level and secondary science instruction. Previous studies report that most science teachers use science textbooks for most of their instructional time (Lumpe and Beck, 1996). Using a single comprehensive science textbook has been the norm for many years, and this is unhkely to change given the current state and structure of education systems and textbook publishing. So what can effective science teachers do to overcome the obstacles of inadequate textbooks? They can first fa-miliarize themselves with the problem and with the circumstances that have led us to this point, and second, take steps to correct textbook inadequacies in the classroom

Risk Factors for Fecal Incontinence in Older Women

To estimate the prevalence of fecal incontinence (FI) in older women, and examine associations between potential risk factors and prevalent FI