Relativistic calculations of the lifetimes and hyperfine structure constants in 67^{67}Zn+^{+}

This work presents accurate {\it ab initio} determination of the magnetic dipole (M1) and electric quadrupole (E2) hyperfine structure constants for the ground and a few low-lying excited states in $^{67}$Zn$^{+}$, which is one of the interesting systems in fundamental physics. The coupled-cluster (CC) theory within the relativistic framework has been used here in this calculations. Long standing demands for a relativistic and highly correlated calculations like CC can be able to resolve the disagreements among the lifetime estimations reported previously for a few low-lying states of Zn$^{+}$. The role of different electron correlation effects in the determination of these quantities are discussed and their contributions are presented.Comment: 9 pages, 1 figure. submitted to J. Phys. B Fast Trac

Lithium abundances from the 6104 Å line in cool Pleiades stars

Lithium abundances determined by spectral synthesis from both the 6708 Å resonance line and the 6104 Å subordinate line are reported for 11 Pleiades late-G and early-K stars observed at the William Herschel Telescope. Firm detections of the weak subordinate line are found for four objects, marginal detections for four, and upper limits for the remaining three stars. Some of these spectra were previously analysed by Russell (1996), where he reported that abundances derived from the 6104 Å line were systematically higher than those obtained from the 6708 Å line by 0.2-0.7 dex. He also reported a reduced spread in the 6104 Å line abundances compared with those determined from the 6708 Å feature. Using spectral synthesis we have re-analysed Russell's data, along with our own. Our results do not entirely support Russell's conclusions. We report a ~ 0.7 dex scatter in the abundances from 6708 Å and a scatter at least as large from the 6104 Å line. We find that this is partly explained by our inclusion of a nearby Fe Ii line and careful modelling of damping wings in the strong metal lines close to the 6104 Å feature; neglect of these leads to overestimates of the Li abundance which are most severe in those objects with the weakest 6104 Å lines, thus reducing the abundance scatter. We find a reasonable correlation between the 6104 Å and 6708 Å Li abundances, although four stars have 6104 Å-determined abundances which are significantly larger than the 6708 Å-determined values by up to 0.5 dex, suggesting problems with the homogeneous, 1-dimensional atmospheres being used. We show that these discrepancies can be explained, although probably not uniquely, by the presence of star spots with plausible coverage fractions. The addition of spots does not significantly reduce the apparent scatter in Li abundances, leaving open the possibility that at least some of the spread is caused by real star-to-star differences in pre-main sequence Li depletion

Non-affirmative Theory of Education as a Foundation for Curriculum Studies, Didaktik and Educational Leadership

This chapter presents non-affirmative theory of education as the foundation for a new research program in education, allowing us to bridge educational leadership, curriculum studies and Didaktik. We demonstrate the strengths of this framework by analyzing literature from educational leadership and curriculum theory/didaktik. In contrast to both socialization-oriented explanations locating curriculum and leadership within existing society, and transformation-oriented models viewing education as revolutionary or super-ordinate to society, non-affirmative theory explains the relation between education and politics, economy and culture, respectively, as non-hierarchical. Here critical deliberation and discursive practices mediate between politics, culture, economy and education, driven by individual agency in historically developed cultural and societal institutions. While transformative and socialization models typically result in instrumental notions of leadership and teaching, non-affirmative education theory, previously developed within German and Nordic education, instead views leadership and teaching as relational and hermeneutic, drawing on ontological core concepts of modern education: recognition; summoning to self-activity and Bildsamkeit. Understanding educational leadership, school development and teaching then requires a comparative multi-level approach informed by discursive institutionalism and organization theory, in addition to theorizing leadership and teaching as cultural-historical and critical-hermeneutic activity. Globalisation and contemporary challenges to deliberative democracy also call for rethinking modern nation-state based theorizing of education in a cosmopolitan light. Non-affirmative education theory allows us to understand and promote recognition based democratic citizenship (political, economical and cultural) that respects cultural, ethical and epistemological variations in a globopolitan era. We hope an American-European-Asian comparative dialogue is enhanced by theorizing education with a non-affirmative approach

Endogenous gibberellins in Lolium perenne and influence of defoliation on their contents in elongating leaf bases and in leaf sheats

International audienc

Endogenous gibberellin A1 levels control thermoperiodic stem elongation in Pisum sativum

Gibberellin (GA) is believed to be involved in thermoperiodic stem elongation. With this in mind, we studied the correlation between gibberellin A 1 (GA 1) levels and stem elongation affected by alternating day (DT) and night temperature (NT) in 5 genotypes of Pisum sativum differing in their degree of dwarfism. The endogenous GA content in the tissue of two of the genotypes was determined by combined gas chromatography and mass spectrometry. The wild genotype developed 40 to 50% shorter stems and internodes under a low DT and high NT combination (negative difference (DIF) between DT and NT. DT NT 15.5 21.5 or 14 24°C than under the opposite regime of high DT and low NT (positive DIF. DT NT 22.5 16.5 or 24 14°C). The GA biosynthetic mutants Is and le, and the auxin and brassinosteroid mutang lkb responded in a similar way, but not as strongly as the wild type. The stem length of the GA-insensitive slender mutant (la cry 3) was reduced by only 8% under negative compared to positive DIF. In the wild type endogenous GA levels decreased by 60% from positive to negative DIF in the upper part of the stem. Further, there was a corresponding decrease in the levels of of precursors to GA 1, i.e. GA 53, GA 44, GA 19, and GA 20 while 2̄-hydroxylated GA 20 and GA 1, GA 29 and GA 8, respectively, were unaffected by DIF. A similar increase in the ratios of GA 29 to GA 20 and GA 8 to GA 1 from positive to negative DIF was seen in the stem tissue of the le mutant as in the wild type. The temperature regimes affected the levels of GA 1 and its precursors in combined leaf and petiole samples and in the shoot tip in a similar manner as in the stem tissue. However, the different temperature regimes did not affect the ratio of GA 8/GA 1 in the shoot tip. The results indicate that altered stem elongation of the pea plants in response to diurnal temperature alternations may be mediated by changes in endogenous levels of GA 1. The GA 1 levels may be controlled by an effect of DIF on both biosynthetic and mactivation steps