Adsorption energy and spin state of first-row transition metals adsorbed on MgO(100)

Slab and cluster model spin-polarized calculations have been carried out to study various properties of isolated first-row transition metal atoms adsorbed on the anionic sites of the regular MgO(100) surface. The calculated adsorption energies follow the trend of the metal cohesive energies, indicating that the changes in the metal-support and metal-metal interactions along the series are dominated by atomic properties. In all cases, except for Ni at the generalized gradient approximation level, the number of unpaired electron is maintained as in the isolated metal atom. The energy required to change the atomic state from high to low spin has been computed using the PW91 and B3LYP density-functional-theory-based methods. PW91 fails to predict the proper ground state of V and Ni, but the results for the isolated and adsorbed atom are consistent within the method. B3LYP properly predicts the ground state of all first-row transition atom the high- to low-spin transition considered is comparable to experiment. In all cases, the interaction with the surface results in a reduced high- to low-spin transition energy

Origin of molecular oxygen in Comet 67P/Churyumov-Gerasimenko

Molecular oxygen has been detected in the coma of comet 67P/Churyumov-Gerasimenko with abundances in the 1-10% range by the ROSINA-DFMS instrument on board the Rosetta spacecraft. Here we find that the radiolysis of icy grains in low-density environments such as the presolar cloud may induce the production of large amounts of molecular oxygen. We also show that molecular oxygen can be efficiently trapped in clathrates formed in the protosolar nebula, and that its incorporation as crystalline ice is highly implausible because this would imply much larger abundances of Ar and N2 than those observed in the coma. Assuming that radiolysis has been the only O2 production mechanism at work, we conclude that the formation of comet 67P/Churyumov-Gerasimenko is possible in a dense and early protosolar nebula in the framework of two extreme scenarios: (1) agglomeration from pristine amorphous icy grains/particles formed in ISM and (2) agglomeration from clathrates that formed during the disk's cooling. The former scenario is found consistent with the strong correlation between O2 and H2O observed in 67P/C-G's coma while the latter scenario requires that clathrates formed from ISM icy grains that crystallized when entering the protosolar nebula.Comment: The Astrophysical Journal Letters, in pres

Introduction to the special issue: after trust

“Trust” has long been seen as critical to the success and durability of trading networks, and conceptualised as a positive moral sentiment that is embedded in shared kinship, ethnicity or friendship, or in shared frameworks of morality. Other recent studies of business communities suggest that the ability to work in settings characterised by pervasive mistrust is a key factor in the development of commercial acumen and determining success. This Special Issue argues that the focus on trust and mistrust, and the underlying concern with ethics and morality, obscure equally critical aspects that inform the durability of trading networks. It offers ethnographic accounts of different inter-Asian trading networks active in the city of Yiwu. One of China’s most dynamic and diverse ‘international trade cities’, Yiwu is home to the largest wholesale market of small commodities in the world, and attracts traders and merchants from across the planet; over 12,000 foreign traders are also resident in the city. The collected articles analyse the durability of these networks in relation to broader geopolitical processes and contexts, arguing that success often depends on the ability to negotiate geopolitical shifts and the faultlines of political identity. The articles trace traders’ efforts to create institutions that allow them to withstand geopolitical transformations. They also document the ability of trading networks to operate flexibly across different social fields, showing that resilience often depends on the ability to navigate and profit from shifting relations between economic, political and familial domains

Crossing Eurasia: trans-regional Afghan trading networks in China and beyond

An expanding body of literature in the field of Central Asian studies has brought attention to the problems of considering the region's complex dynamics through the lens of its nation-states. Comparatively less attention has been paid to the role played by trans-regional circulations in connecting parts of Central Asia to the wider world. This paper situates ethnographic work on trans-regional networks of Afghan traders in China, Central Asia, Russia, Ukraine and the UK in relation to the literature on trans-regional connections and circulation societies. Ethnographically it demonstrates the multi-polar nature of these trans-regional networks, and the importance of trading nodes, especially the Chinese city of Yiwu, to their formation and ongoing vitality

Innovation Across Cultures: Connecting Leadership, Identification, and Creative Behavior in Organizations

Innovation is considered essential for today's organizations to survive and thrive. Researchers have also stressed the importance of leadership as a driver of followers' innovative work behavior (FIB). Yet, despite a large amount of research, three areas remain understudied: (a) The relative importance of different forms of leadership for FIB; (b) the mechanisms through which leadership impacts FIB; and (c) the degree to which relationships between leadership and FIB are generalizable across cultures. To address these lacunae, we propose an integrated model connecting four types of positive leadership behaviors, two types of identification (as mediating variables), and FIB. We tested our model in a global data set comprising responses of N = 7,225 participants from 23 countries, grouped into nine cultural clusters. Our results indicate that perceived LMX quality was the strongest relative predictor of FIB. Furthermore, the relationships between both perceived LMX quality and identity leadership with FIB were mediated by social identification. The indirect effect of LMX on FIB via social identification was stable across clusters, whereas the indirect effects of the other forms of leadership on FIB via social identification were stronger in countries high versus low on collectivism. Power distance did not influence the relations

Political leaders' identity leadership and civic citizenship behavior:The mediating role of trust in fellow citizens and the moderating role of economic inequality

Identity leadership captures leaders efforts to create and promote a sense of shared group membership (i.e., a sense of “we” and of “us”) among followers. The present research report tests this claim by drawing on data from 26 countries that are part of the Global Identity Leadership Development (GILD) project to examine the relationship between political leaders' identity leadership and civic citizenship behavior (N = 6787). It also examines the contributions of trust and economic inequality to this relationship. Political leaders' identity leadership (PLIL) was positively associated with respondents' people-oriented civic citizenship behaviors (CCB-P) in 20 of 26 countries and civic citizenship behaviors aimed at one's country (CCB-C) in 23 of 26 countries. Mediational analyses also confirmed the indirect effects of PLIL via trust in fellow citizens on both CCB-P (in 25 out of 26 countries) and CCB-C (in all 26 countries). Economic inequality moderated these effects such that the main and indirect effects of trust in one's fellow citizens on CCB-C were stronger in countries with higher economic inequality. This interaction effect was not observed for CCB-P. The study highlights the importance of identity leadership and trust in fellow citizens in promoting civic citizenship behavior, especially in the context of economic inequality.</p

Competences of Mathematics Teachers in Diagnosing Teaching Situations and Offering Feedback to Students:Specificity, Consistency and Reification of Pedagogical and Mathematical Discourses

In the study we report in this chapter, we investigate the competences of mathematics pre- and in-service teachers in diagnosing situations pertaining to mathematics teaching and in offering feedback to the students at the heart of said situations. To this aim we deploy a research design that involves engaging teachers with situation-specific tasks in which we invite participants to: solve a mathematical problem; examine a (fictional yet research-informed) solution proposed by a student in class and a (fictional yet research-informed) teacher response to the student; and, describe the approach they themselves would adopt in this classroom situation. Participants were 23 mathematics graduates enrolled in a post-graduate mathematics education programme, many already in-service teachers. They responded to a task that involved debating the identification of a tangent line at an inflection point of a cubic function through resorting to the formal definition of tangency or the function graph. Analysis of their written responses to the task revealed a great variation in the participants’ diagnosing and addressing of teaching issues – in this case involving the role of visualisation in mathematical reasoning. We describe this variation in terms of a typology of four interrelated characteristics that emerged from the data analysis: consistency between stated beliefs/knowledge and intended practice, specificity of the response to the given classroom situation, reification of pedagogical discourses, and reification of mathematical discourses. We propose that deploying the theoretical construct of these characteristics in tandem with our situation-specific task design can contribute towards the identification – as well as reflection upon and development – of mathematics teachers’ diagnostic competences in teacher education and professional development programmes