The elemental composition of the Sun II. The iron group elements Sc to Ni

We redetermine the abundances of all iron group nuclei in the Sun, based on neutral and singly-ionised lines of Sc, Ti, V, Mn, Fe, Co and Ni in the solar spectrum. We employ a realistic 3D hydrodynamic model solar atmosphere, corrections for departures from local thermodynamic equilibrium (NLTE), stringent line selection procedures and high quality observational data. We have scoured the literature for the best quality oscillator strengths, hyperfine constants and isotopic separations available for our chosen lines. We find $\log \epsilon_\mathrm{Sc}=3.16\pm0.04$, $\log \epsilon_\mathrm{Ti}=4.93\pm0.04$, $\log \epsilon_\mathrm{V}=3.89\pm0.08$, $\log \epsilon_\mathrm{Cr}=5.62\pm0.04$, $\log \epsilon_\mathrm{Mn}=5.42\pm0.04$, $\log \epsilon_\mathrm{Fe}=7.47\pm0.04$, $\log \epsilon_\mathrm{Co}=4.93\pm0.05$ and $\log \epsilon_\mathrm{Ni}=6.20\pm0.04$. Our uncertainties factor in both statistical and systematic errors (the latter estimated for possible errors in the model atmospheres and NLTE line formation). The new abundances are generally in good agreement with the CI meteoritic abundances but with some notable exceptions. This analysis constitutes both a full exposition and a slight update of the preliminary results we presented in Asplund, Grevesse, Sauval & Scott (arXiv:0909.0948), including full line lists and details of all input data we employed.Comment: 10 figures, 24 pages + 10 online-only pages of tables. v2. Matches version accepted by A&

The elemental composition of the Sun III. The heavy elements Cu to Th

We re-evaluate the abundances of the elements in the Sun from copper ($Z=29$) to thorium ($Z=90$). Our results are mostly based on neutral and singly-ionised lines in the solar spectrum. We use the latest 3D hydrodynamic solar model atmosphere, and in a few cases also correct for departures from local thermodynamic equilibrium (LTE) using non-LTE (NLTE) calculations performed in 1D. In order to minimise statistical and systematic uncertainties, we make stringent line selections, employ the highest-quality observational data and carefully assess oscillator strengths, hyperfine constants and isotopic separations available in the literature, for every line included in our analysis. Our results are typically in good agreement with the abundances in the most pristine meteorites, but there are some interesting exceptions. This analysis constitutes both a full exposition and a slight update of the relevant parts of the preliminary results we presented in Asplund, Grevesse, Sauval & Scott (arXiv:0909.0948), including full line lists and details of all input data that we have employed.Comment: 5 figures, 18 pages + 6 online-only pages of tables. v2. Matches version accepted by A&

Transformation of Magnaporthe grisea to phosphinothricin resistance using the bar gene from Streptomyces hygroscopicus

Three transformation systems have been reported for the rice blast fungus Magnaporthe grisea (Parsons et al. 1987 Proc. Natl. Acad. Sci. USA 84:4161-4165; Daboussi et al. 1989 Curr. Genet. 15:453-456; Leung et al. 1990 Curr. Genet. 17:409-411). Among these three selection systems, only hygromycin B resistance provides a dominant selection that can be used for any wild type strain. A second dominant selection marker is needed to transform strains that are already hygromycin B resistant

Tourism: the untapped goldmine in the Gold Coast

Purpose – This study examines the economic impact of international tourism and currency valuation in the West African country of Ghana. Previously known as the Gold Coast due to its vast gold reserves, Ghana is a developing economy with a sharply devalued currency and a heavy reliance on imports. Design – The paper shows that Ghana’s weak currency can be leveraged to boost international tourism and with that, economic growth. This view of tourism-led growth is in part supported by evidence in which tourism receipts are a major source of foreign exchange earnings for a number of developing economies. Methodology – The relationship between economic growth, tourism receipts, and currency valuation is examined using a vector error correction model. This approach offers an opportunity to not only confirm the existence of a dynamic relationship among the time series but also, the existence of causality both in the short- and long-run. Findings – Cointegration tests confirm the existence of a long-run relationship among the variables. Both tourism and exchange rate are found to positively impact economic growth. Also, there is a long-run causality from exchange rate to tourism receipts. Originality – This is the first empirical study that demonstrates the existence of causality between currency valuation and tourism using data from Sub-Saharan Africa, a region with abundant natural resources but one that remains significantly underdeveloped

The elemental composition of the Sun I. The intermediate mass elements Na to Ca

The composition of the Sun is an essential piece of reference data for astronomy, cosmology, astroparticle, space and geo-physics. This article, dealing with the intermediate-mass elements Na to Ca, is the first in a series describing the comprehensive re-determination of the solar composition. In this series we severely scrutinise all ingredients of the analysis across all elements, to obtain the most accurate, homogeneous and reliable results possible. We employ a highly realistic 3D hydrodynamic solar photospheric model, which has successfully passed an arsenal of observational diagnostics. To quantify systematic errors, we repeat the analysis with three 1D hydrostatic model atmospheres (MARCS, MISS and Holweger & M\"{u}ller 1974) and a horizontally and temporally-averaged version of the 3D model ($\langle$3D$\rangle$). We account for departures from LTE wherever possible. We have scoured the literature for the best transition probabilities, partition functions, hyperfine and other data, and stringently checked all observed profiles for blends. Our final 3D+NLTE abundances are: $\log\epsilon_{\mathrm{Na}}=6.21\pm0.04$, $\log\epsilon_{\mathrm{Mg}}=7.59\pm0.04$, $\log\epsilon_{\mathrm{Al}}=6.43\pm0.04$, $\log\epsilon_{\mathrm{Si}}=7.51\pm0.03$, $\log\epsilon_{\mathrm{P}}=5.41\pm0.03$, $\log \epsilon_{\mathrm{S}}=7.13\pm0.03$, $\log\epsilon_{\mathrm{K}}=5.04\pm0.05$ and $\log\epsilon_{\mathrm{Ca}}=6.32\pm0.03$. The uncertainties include both statistical and systematic errors. Our results are systematically smaller than most previous ones with the 1D semi-empirical Holweger & M\"uller model. The $\langle$3D$\rangle$ model returns abundances very similar to the full 3D calculations. This analysis provides a complete description and a slight update of the Na to Ca results presented in Asplund, Grevesse, Sauval & Scott (arXiv:0909.0948), with full details of all lines and input data.Comment: 7 figures, 14 pages + 5 online-only pages of tables and an appendix. v2. Matches version accepted by A&

The elemental composition of the Sun III. The heavy elements Cu to Th

We re-evaluate the abundances of the elements in the Sun from copper (Z = 29) to thorium (Z = 90). Our results are mostly based on neutral and singly-ionised lines in the solar spectrum. We use the latest 3D hydrodynamic solar model atmosphere, and in a few cases also correct for departures from local thermodynamic equilibrium (LTE) using non-LTE (NLTE) calculations performed in 1D. In order to minimise statistical and systematic uncertainties, we make stringent line selections, employ the highest-quality observational data and carefully assess oscillator strengths, hyperfine constants and isotopic separations available in the literature, for every line included in our analysis. Our results are typically in good agreement with the abundances in the most pristine meteorites, but there are some interesting exceptions. This analysis constitutes both a full exposition and a slight update of the relevant parts of the preliminary results we presented in Asplund et al. (2009, ARA&A, 47, 481), including full line lists and details of all input data that we have employed

Layout of Graphs with Bounded Tree-Width

A \emph{queue layout} of a graph consists of a total order of the vertices, and a partition of the edges into \emph{queues}, such that no two edges in the same queue are nested. The minimum number of queues in a queue layout of a graph is its \emph{queue-number}. A \emph{three-dimensional (straight-line grid) drawing} of a graph represents the vertices by points in $\mathbb{Z}^3$ and the edges by non-crossing line-segments. This paper contributes three main results: (1) It is proved that the minimum volume of a certain type of three-dimensional drawing of a graph $G$ is closely related to the queue-number of $G$. In particular, if $G$ is an $n$-vertex member of a proper minor-closed family of graphs (such as a planar graph), then $G$ has a $O(1)\times O(1)\times O(n)$ drawing if and only if $G$ has O(1) queue-number. (2) It is proved that queue-number is bounded by tree-width, thus resolving an open problem due to Ganley and Heath (2001), and disproving a conjecture of Pemmaraju (1992). This result provides renewed hope for the positive resolution of a number of open problems in the theory of queue layouts. (3) It is proved that graphs of bounded tree-width have three-dimensional drawings with O(n) volume. This is the most general family of graphs known to admit three-dimensional drawings with O(n) volume. The proofs depend upon our results regarding \emph{track layouts} and \emph{tree-partitions} of graphs, which may be of independent interest.Comment: This is a revised version of a journal paper submitted in October 2002. This paper incorporates the following conference papers: (1) Dujmovic', Morin & Wood. Path-width and three-dimensional straight-line grid drawings of graphs (GD'02), LNCS 2528:42-53, Springer, 2002. (2) Wood. Queue layouts, tree-width, and three-dimensional graph drawing (FSTTCS'02), LNCS 2556:348--359, Springer, 2002. (3) Dujmovic' & Wood. Tree-partitions of $k$-trees with applications in graph layout (WG '03), LNCS 2880:205-217, 200

Changes in Teachers’ Adaptive Expertise in an Engineering Professional Development Course

Although the consensus seems to be that high-school-level introductory engineering courses should focus on design, this creates a problem for teacher training. Traditionally, math and science teachers are trained to teach and assess factual knowledge and closed-ended problemsolving techniques specific to a particular discipline, which is unsuited for teaching design skills for open-ended problems that may involve multiple engineering disciplines. Instead, engineering teacher training should use the more fluid framework of adaptive expertise which values the ability to apply knowledge in innovative ways as well as recall facts and solve problems using conventional techniques. In this study, we examined a 6-week program to train math/science teachers to teach high school design engineering. For each curriculum unit, we had a pre-posttest to assess the teachers’ factual knowledge and ability to solve typical problems (termed ‘‘efficiency’’) and their ability to apply their knowledge to reason through open-ended problems (termed ‘‘innovation’’). In addition, we conducted a pre-posttest to see whether teachers’ attitudes and beliefs related to adaptive expertise changed over the course of the program