Improved Log(gf) Values for Lines of Ti I and Abundance Determinations in the Photospheres of the Sun and Metal-Poor Star HD 84937 (Accurate Transition Probabilities for Ti I)

New atomic transition probability measurements for 948 lines of Ti I are reported. Branching fractions from Fourier transform spectra and from spectra recorded using a 3 m echelle spectrometer are combined with published radiative lifetimes from laser-induced fluorescence measurements to determine these transition probabilities. Generally good agreement is found in comparisons to the NIST Atomic Spectra Database. The new Ti I data are applied to re-determine the Ti abundance in the photospheres of the Sun and metal-poor star HD 84937 using many lines covering a range of wavelength and excitation potential to explore possible non-local thermal equilibrium effects. The variation of relative Ti/Fe abundance with metallicity in metal-poor stars observed in earlier studies is supported in this study.NSF AST-1211055, AST-0908978, AST-1211585NSF REU grant AST-1004881ESO Science Archive Facility 073.D-0024, 266.D-5655NASA NAS 5-26555Astronom

Mn L2,3_{2,3} edge resonant x-ray scattering in manganites: Influence of the magnetic state

We present an analysis of the dependence of the resonant orbital order and magnetic scattering spectra on the spin configuration. We consider an arbitrary spin direction with respect to the local crystal field axis, thus lowering significantly the local symmetry. To evaluate the atomic scattering in this case, we generalized the Hannon-Trammel formula and implemented it inside the framework of atomic multiplet calculations in a crystal field. For an illustration, we calculate the magnetic and orbital scattering in the CE phase of \lsmo in the cases when the spins are aligned with the crystal lattice vector ${\vec a}$ (or equivalently ${\vec b}$) and when they are rotated in the $ab$-plane by 45$^{\circ}$ with respect to this axis. Magnetic spectra differ for the two cases. For the orbital scattering, we show that for the former configuration there is a non negligible $\sigma \to \sigma'$ ($\pi \to \pi'$) scattering component, which vanishes in the 45$^\circ$ case, while the $\sigma \to \pi'$ ($\pi \to \sigma'$) components are similar in the two cases. From the consideration of two 90$^\circ$ spin canted structures, we conclude there is a significant dependence of the orbital scattering spectra on the spin arrangement. Recent experiments detected a sudden decrease of the orbital scattering intensity upon increasing the temperature above the N\' eel temperature in \lsmo. We discuss this behavior considering the effect of different types of misorientations of the spins on the orbital scattering spectrum.Comment: 8 figures. In the revised version, we added a note, a reference, and a few minor changes in Figure 1 and the text. Accepted in Physical Review

Recombination in polymer-fullerene bulk heterojunction solar cells

Recombination of photogenerated charge carriers in polymer bulk heterojunction (BHJ) solar cells reduces the short circuit current (Jsc) and the fill factor (FF). Identifying the mechanism of recombination is, therefore, fundamentally important for increasing the power conversion efficiency. Light intensity and temperature dependent current-voltage measurements on polymer BHJ cells made from a variety of different semiconducting polymers and fullerenes show that the recombination kinetics are voltage dependent and evolve from first order recombination at short circuit to bimolecular recombination at open circuit as a result of increasing the voltage-dependent charge carrier density in the cell. The "missing 0.3V" inferred from comparison of the band gaps of the bulk heterojunction materials and the measured open circuit voltage at room temperature results from the temperature dependence of the quasi-Fermi-levels in the polymer and fullerene domains - a conclusion based upon the fundamental statistics of Fermions.Comment: Accepted for publication in Physical Review B. http://prb.aps.org/accepted/B/6b07cO3aHe71bd1b149e1425e58bf2868cda2384d?ajax=1&height=500&width=50

Making automation pay - cost & throughput trade-offs in the manufacture of large composite components

The automation of complex manufacturing operations can provide significant savings over manual processes, and there remains much scope for increasing automation in the production of large scale structural composites. However the relationships between driving variables are complex, and the achievable throughput rate and corresponding cost for a given design are often not apparent. The deposition rate, number of machines required and unit production rates needed are interrelated and consequently the optimum unit cost is difficult to predict. A detailed study of the costs involved for a series of composite wing cover panels with different manufacturing requirements was undertaken. Panels were sized to account for manufacturing requirements and structural load requirements allowing both manual and automated lay-up procedures to influence design. It was discovered that the introduction of automated tape lay-up can significantly reduce material unit cost, and improve material utilisation, however higher production rates are needed to see this benefit

Improved V II log(gfgf) Values, Hyperfine Structure Constants, and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937

New experimental absolute atomic transition probabilities are reported for 203 lines of V II. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions are normalized with radiative lifetime measurements to determine the new transition probabilities. Generally good agreement is found between this work and previously reported V II transition probabilities. Use of two spectrometers, independent radiometric calibration methods, and independent data analysis routines enables a reduction in systematic uncertainties, in particular those due to optical depth errors. In addition, new hyperfine structure constants are measured for selected levels by least squares fitting line profiles in the FTS spectra. The new V II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to determine new, more accurate V abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. Very good agreement is found between our new solar photospheric V abundance, log {\epsilon}(V) = 3.95 from 15 V II lines, and the solar-system meteoritic value. In HD 84937, we derive [V/H] = -2.08 from 68 lines, leading to a value of [V/Fe] = 0.24.Comment: 32 pages, 7 tables (3 machine-readable), 8 figures; accepted for publication in ApJ

Theoretical study of resonant x-ray emission spectroscopy of Mn films on Ag

We report a theoretical study on resonant x-ray emission spectra (RXES) in the whole energy region of the Mn $L_{2,3}$ white lines for three prototypical Mn/Ag(001) systems: (i) a Mn impurity in Ag, (ii) an adsorbed Mn monolayer on Ag, and (iii) a thick Mn film. The calculated RXES spectra depend strongly on the excitation energy. At $L_3$ excitation, the spectra of all three systems are dominated by the elastic peak. For excitation energies around $L_2$, and between $L_3$ and $L_2$, however, most of the spectral weight comes from inelastic x-ray scattering. The line shape of these inelastic ``satellite'' structures changes considerably between the three considered Mn/Ag systems, a fact that may be attributed to changes in the bonding nature of the Mn-$d$ orbitals. The system-dependence of the RXES spectrum is thus found to be much stronger than that of the corresponding absorption spectrum. Our results suggest that RXES in the Mn $L_{2,3}$ region may be used as a sensitive probe of the local environment of Mn atoms.Comment: 9 pages, 11 figure

Modeling the Performance of the Intermittent Sand Filter

Several models were developed to predict the efficiency of the intermittent sand filter (ISF) in removing algae from wastewater stabilization pond effluent; volatile suspended solids (VSS) was the analytical technique used to identify algal concentrations. The first (ISF model) and second (modified ISF model) models consisted of two distinct portions: a surface algal layer (SAL) component and a sand phase component. In the ISF model, the sand phase component was described in terms of 20 empirical sand filter efficiency terms (20 ^ coefficients); in the modified ISF model, a functional relationship between ^ and filter depth was developed. The modified ISF model was less accurate than the ISF model in predicting filter effluent quality. The third model (simplified ISF model) consisted of a single component (the sand phase). The mass of algae which was deposited to the SAL componenet in the first two models was, instead, forced into the top (2 inch) layer of sand. The functional relationship between the sand phase filter term and filter depth was recalculated and utilized to desribe the decrease in the concentration of algae during the filtration process. The simplified ISF model was comparable to the ISF model in predicting filter effluent quality. The simplified model predicted 85 percent VSS removal for 0.17 mm effective sand size (E\u27) filters and 44 percent VSS removal for 0.40 and 0.68 mm E\u27 filters. The application of the simplified ISF model is subject to limitations of maximum hydraulic loading rates of 0.7 million gallons per acre per day and miximum mass loadings of 49 grams of SS per m^2 per day for 0.17 mm effective size sand. Design curves, in which period of filter operation was described as a function of mass loading, were developed for ISF systems containing 0.17, 0.40, and 0.68 mm E\u27 media. Wastewater stabilization pond effluents having calcium carbonate precipitation problems were included as a special case in this analysis

Enhancing Paternal Engagement in a Coparenting Paradigm

Despite the benefits for children and families of fathers who are involved positively with their children, most parenting programs in the United States and globally focus on and collect evaluation data from mothers almost exclusively. Engaging fathers is still viewed as a complex endeavor that is only somewhat successful. In this article, we summarize what is known about engaging fathers in parenting programs, then argue that programs are most effective when coparenting is the focus early in family formation. We rely on two decades of the Supporting Father Involvement program as an example of an initiative that has been effective at recruiting and retaining fathers and mothers in various cultural and national contexts. When programs are inclusive in content and focus on process, are sensitive to differences within and across families, and recognize parents as experts on their children, they are more successful in recruiting and retaining diverse groups of fathers and families

Coming home upset: Gender, marital satisfaction and the daily spillover of workday experience into couple interactions

This study explored how daily changes in workday pace and end-of-the-workday mood were related to nightly variations in withdrawn and angry marital behavior. For 3 days, 82 husbands and wives from 42 couples completed questionnaires at the end of the workday and at bedtime. More negatively arousing workdays were linked with angrier marital behavior for women and less angry and more withdrawn behavior for men. Daily changes in workday pace predicted fluctuations in women\u27s, but not men\u27s, marital behavior. Several of these workday-marital behavior connections varied by level of marital satisfaction. In contrast to the gender differences in responses to workday stress, no differences were found in typical marital behaviors. These findings suggest that gender differences are enhanced under stress

Coming home upset: Gender, marital satisfaction and the daily spillover of workday experience into couple interactions

This study explored how daily changes in workday pace and end-of-the-workday mood were related to nightly variations in withdrawn and angry marital behavior. For 3 days, 82 husbands and wives from 42 couples completed questionnaires at the end of the workday and at bedtime. More negatively arousing workdays were linked with angrier marital behavior for women and less angry and more withdrawn behavior for men. Daily changes in workday pace predicted fluctuations in women\u27s, but not men\u27s, marital behavior. Several of these workday-marital behavior connections varied by level of marital satisfaction. In contrast to the gender differences in responses to workday stress, no differences were found in typical marital behaviors. These findings suggest that gender differences are enhanced under stress