Reactions of Nb2 and Nb3 with CO, D2, N2, and O2 : reconciling experimental kinetics with density functional theory-calculated reaction profiles

 Calculated energy profiles for the reactions of neutral Nb₂ and Nb₃ metal clusters with CO, D₂, N₂, and O₂ are presented. In each reaction path, both a physisorption energy minimum, where the reactant remains intact, and a chemisorption energy minimum, where the reactant has dissociated, are calculated and linked by saddle points. We calculate branching ratios for the forward (dissociative) and reverse reactions which we compare with the experimental kinetic data. It is found that a combination of average thermal energies and barrier heights leads to wide variation in branching ratios which compares favourably to previously determined experimental reaction rates.

The current status of greenhouse gas reporting by Chinese companies: a test of legitimacy theory

Purpose – The purpose of this paper is to investigate the factors driving greenhouse gas reporting by Chinese companies.
Design/methodology/approach – Content analysis of annual reports and corporate social responsibility (CSR) reports for the year 2010 of the top 100 A-share companies listed on Shanghai Stock Exchange was conducted to investigate the extent of greenhouse gas reporting. Multiple regression analysis was performed to determine the factors driving these companies’ greenhouse gas reporting.
Findings – It was found that most Chinese companies reported neutral and good news. The results also indicate larger companies operating in an industry which has higher level of carbon dioxide emissions tend to have higher levels of greenhouse gas disclosures, consistent with the expectation of legitimacy theory. However, profitability and overseas listing were not significantly related to greenhouse gas reporting. This is consistent with the findings of previous literature. Finally, contrary to expectations, state-owned companies report less greenhouse gas information than private companies.
Originality/value – The paper contributes towards theory development by testing legitimacy theory in the context of greenhouse gas reporting by Chinese companies and contributes to existing literature on greenhouse gas reporting by focussing on the large emerging economy of China. The practical contribution of the paper rests in the area of accounting practice. The results outline the dearth in greenhouse gas reporting by Chinese companies, suggesting there needs to be future development of accounting standards in this area.

Expected shannon entropy and shannon differentiation between subpopulations for neutral genes under the finite island model

Shannon entropy H and related measures are increasingly used in molecular ecology and population genetics because (1) unlike measures based on heterozygosity or allele number, these measures weigh alleles in proportion to their population fraction, thus capturing a previously-ignored aspect of allele frequency distributions that may be important in many applications; (2) these measures connect directly to the rich predictive mathematics of information theory; (3) Shannon entropy is completely additive and has an explicitly hierarchical nature; and (4) Shannon entropy-based differentiation measures obey strong monotonicity properties that heterozygosity-based measures lack. We derive simple new expressions for the expected values of the Shannon entropy of the equilibrium allele distribution at a neutral locus in a single isolated population under two models of mutation: the infinite allele model and the stepwise mutation model. Surprisingly, this complex stochastic system for each model has an entropy expressable as a simple combination of well-known mathematical functions. Moreover, entropy- and heterozygosity-based measures for each model are linked by simple relationships that are shown by simulations to be approximately valid even far from equilibrium. We also identify a bridge between the two models of mutation. We apply our approach to subdivided populations which follow the finite island model, obtaining the Shannon entropy of the equilibrium allele distributions of the subpopulations and of the total population. We also derive the expected mutual information and normalized mutual information ("Shannon differentiation") between subpopulations at equilibrium, and identify the model parameters that determine them. We apply our measures to data from the common starling (Sturnus vulgaris) in Australia. Our measures provide a test for neutrality that is robust to violations of equilibrium assumptions, as verified on real world data from starlings.

A succession of theories : purging redundancy from disturbance theory

The topics of succession and post-disturbance ecosystem recovery have a long and convoluted history. There is extensive redundancy within this body of theory, which has resulted in confusion, and the links among theories have not been adequately drawn. This review aims to distil the unique ideas from the array of theory related to ecosystem change in response to disturbance. This will help to reduce redundancy, and improve communication and understanding between researchers. We first outline the broad range of concepts that have developed over the past century to describe community change in response to disturbance. The body of work spans overlapping succession concepts presented by Clements in 1916, Egler in 1954, and Connell and Slatyer in 1977. Other theories describing community change include state and transition models, biological legacy theory, and the application of functional traits to predict responses to disturbance. Second, we identify areas of overlap of these theories, in addition to highlighting the conceptual and taxonomic limitations of each. In aligning each of these theories with one another, the limited scope and relative inflexibility of some theories becomes apparent, and redundancy becomes explicit. We identify a set of unique concepts to describe the range of mechanisms driving ecosystem responses to disturbance. We present a schematic model of our proposed synthesis which brings together the range of unique mechanisms that were identified in our review. The model describes five main mechanisms of transition away from a post-disturbance community: (i) pulse events with rapid state shifts; (ii) stochastic community drift; (iii) facilitation; (iv) competition; and (v) the influence of the initial composition of a post-disturbance community. In addition, stabilising processes such as biological legacies, inhibition or continuing disturbance may prevent a transition between community types. Integrating these six mechanisms with the functional trait approach is likely to improve the predictive capacity of disturbance theory. Finally, we complement our discussion of theory with a case study which emphasises that many post-disturbance theories apply simultaneously to the same ecosystem. Using the well-studied mountain ash (Eucalyptus regnans) forests of south-eastern Australia, we illustrate phenomena that align with six of the theories described in our model of rationalised disturbance theory. We encourage further work to improve our schematic model, increase coverage of disturbance-related theory, and to show how the model may link to, or integrate with, other domains of ecological theory.

Curriculum as colour and curves: a synthesis of Black theory, design and creativity realised as critical curriculum writing

This article looks to three inspirational Black women, bell hooks, Stacey McBride-Irby and Patricia Williams, in the pursuit of radical curriculum. While today curriculum is critiqued as racialised, gendered, sexualised and classed, the formats of curriculum documents such as text books, units of work and lesson plans have changed little. These documents are often conceived as linear sequences of steps leading to outcomes, and their voices are distanced and ‘neutral’. Drawing on a doctoral study of curriculum design in Australia, this article embraces a different approach by opening up a unit of work on girls’ popular culture to hooks’ invocations to teach to transgress, so that curriculum might be experienced as colour and curves, rather than a monochrome route to a pre-determined end point. Through this, along with hooks, I invite teachers to live pedagogy, rather than to deliver it.

Curriculum as colour and curves: a synthesis of black theory, design and creativity realised as critical curriculum writing

This article looks to three inspirational Black women, bell hooks, Stacey McBride-Irby and Patricia Williams, in the pursuit of radical curriculum. While today curriculum is critiqued as racialized, gendered, sexualised and classed, the formats of curriculum documents such as text books, units of work and lesson plans have changed little. These documents are often conceived as linear sequences of steps leading to outcomes, and their voices are distanced and “neutral”. Drawing on a doctoral study of curriculum design in Australia, this article embraces a different approach by opening up a unit of work on girls’ popular culture to hooks’ invocations to teach to transgress, so that curriculum might be experienced as colour and curves, rather than a monochrome route to a pre-determined end point. Through this, along with hooks, I invite teachers to live pedagogy, rather than to deliver it.