Finite departure from convective quasi-equilibrium: periodic cycle and discharge-recharge mechanism

A simple self–contained theory is proposed for describing life cycles of convective systems as a discharge–recharge process. A closed description is derived for the dynamics of an ensemble of convective plumes based on an energy cycle. The system consists of prognostic equations for the cloud work function and the convective kinetic energy. The system can be closed by intro ducing a functional relationship between the convective kinetic energy and the cloud–base mass flux. The behaviour of this system is considered under a bulk simplification. Previous cloud–resolving mo delling as well as bulk statistical theories for ensemble convective systems suggest that a plausible relationship would be to assume that the convective kinetic energy is linearly proportional to the cloud–base mass flux. As a result, the system reduces to a nonlinear dynamical system with two dependent variables, the cloud–base mass flux and the cloud work function. The fully nonlinear solution of this system always represents a periodic cycle regardless of the initial condition under constant large–scale forcing. Importantly, the inclusion of energy dissipation in this model does not in itself lead the system to an equilibrium.

Synthesis, X-ray crystal structure and catalytic activity of the manganese(II) complex [Mn(bdoa)(H2O)3](bdoaH2 =benzene-1,2-dioxyacetic acid)

Benzene-1,2-dioxyacetic acid (bdoaH2) reacts with Mn(CH3CO2)2·4H2O in an ethanol-water mixture to give the manganese(II) complex [Mn(bdoa)(H2O)3]. The X-ray crystal structure of the complex shows the metal to be pseudo seven-coordinate. The quadridentate bdoa2− dicar☐ylate ligand forms an essentially planar girdle around the metal, being strongly bondedtransoid by a car☐ylate oxygen atom from each of the two car☐ylate moieties (mean MnO 2.199A˚) and also weakly chelated by the two internal ether oxygen atoms (mean MnO 2.413A˚). The coordination sphere about the manganese is completed by three water molecules (mean MnO 2.146A˚) lying in a meridional plane orthogonal to that of the bdoa2− ligand. Magnetic, conductivity and voltammetry data for the complex are given, and its use as a catalyst for the disproportionisation of H2O2 is described.

Structures, reactivity, and catalytic activity of dithiolato-bridged heterobimetallic MRh (M = Pt, Pd) complexes

Heterobimetallic complexes [(P−P)Pt(μ-S−S)Rh(cod)]ClO4 (P−P = (PPh3)2, Ph2P(CH2)3PPh2 (dppp), and Ph2P(CH2)4PPh2 (dppb); S−S = -S(CH2)2S- (EDT), -S(CH2)3S- (PDT), -S(CH2)4S- (BDT), cod = 1,5-cyclooctadiene) reacted with CO to form the carbonyl complexes [(P−P)Pt(μ-S−S)Rh(CO)2]ClO4 and then with PR3 ligands to give [(P−P)Pt(μ-S−S)Rh(CO)(PR3)]ClO4. The binuclear framework of these cod complexes was maintained in the reactions reported. The cod complexes were tested as catalyst precursors in the hydroformylation of styrene. HPNMR in situ studies showed that mononuclear species formed under catalytic conditions.

Binuclear and polymeric manganese(II) salicylate complexes: synthesis, crystal structure and catalytic activity of [Mn2(Hsal)4(H2O)4] and [{Mn2(sal)2(Hsal)(H2O)-(H3O)(py)4•2py}n](H2sal = salicylic acid, py = pyridine)

The two air-stable manganese(II) salicylate complexes [Mn2(Hsal)4(H2O)4]1 and polymeric [{Mn2(sal)2(Hsal)(H2O)(H3O)(py)4·2py}n]2(H2sal = salicylic acid and py = pyridine) have been synthesised easily, and their crystal structures determined. Both contain unsymmetrically bridging salicylate ligands. In the presence of added pyridine 1 and 2 vigorously catalyse the disproportionation of H2O2.

The Clean Development Mechanism as ethical development? Reconciling emissions trading and local development

This paper examines the ethics of the Clean Development Mechanism (CDM) in its architecture, processes and outcomes and its potential to allocate resources to the poor as ‘ethical development’. Two specific examples of CDM projects help us to explore some of the quandaries that seem to be quickly defining operating procedure for the CDM in its efforts to bring entitlementsto the poor. The paper concludes with reflections on the normative and social complications of the CDM and closes with three key areas of further investigation.

Governing the clean development mechanism: global rhetoric versus local realities in carbon sequestration projects

Global agreements have proliferated in the past ten years. One of these is the Kyoto Protocol, which contains provisions for emissions reductions by trading carbon through the Clean Development Mechanism (CDM). The CDM is a market-based instrument that allows companies in Annex I countries to offset their greenhouse gas emissions through energy and tree offset projects in the global South. I set out to examine the governance challenges posed by the institutional design of carbon sequestration projects under the CDM. I examine three global narratives associated with the design of CDM forest projects, specifically North – South knowledge politics, green developmentalism, and community participation, and subsequently assess how these narratives match with local practices in two projects in Latin America. Findings suggest that governance problems are operating at multiple levels and that the rhetoric of global carbon actors often asserts these schemes in one light, while the rhetoric of those who are immediately involved locally may be different. I also stress the alarmist’s discourse that blames local people for the problems of environmental change. The case studies illustrate the need for vertical communication and interaction and nested governance arrangements as well as horizontal arrangements. I conclude that the global framing of forests as offsets requires better integration of local relationships to forests and their management and more effective institutions at multiple levels to link the very local to the very large scale when dealing with carbon sequestration in the CDM.

Molecular dynamics simulation insight into the mechanism of phenol adsorption at low coverages from aqueous solutions on microporous carbons

MD simulation studies showing the influence of porosity and carbon surface oxidation on phenol adsorption from aqueous solutions on carbons are reported. Based on a realistic model of activated carbon, three carbon structures with gradually changed microporosity were created. Next, a different number of surface oxygen groups was introduced. The pores with diameters around 0.6 nm are optimal for phenol adsorption and after the introduction of surface oxygen functionalities, adsorption of phenol decreases (in accordance with experimental data) for all studied models. This decrease is caused by a pore blocking effect due to the saturation of surface oxygen groups by highly hydrogen-bounded water molecules.

Analysis of the intermediate housing market mechanism in the UK

Government policies have backed intermediate housing market mechanisms like shared equity, intermediate rented and shared ownership (SO) as potential routes for some households, who are otherwise squeezed between the social housing and the private market. The rhetoric deployed around such housing has regularly contained claims about its social progressiveness and role in facilitating socio-economic mobility, centring on a claim that SO schemes can encourage people to move from rented accommodation through a shared equity phase and into full owner-occupation. SO has been justified on the grounds of it being transitional state, rather than a permanent tenure. However SO buyers may be laden with economic cost-benefit structures that do not stack up evenly and as a consequence there may be little realistic prospect of ever reaching a preferred outcome. Such behaviours have received little empirical attention as yet despite, the SO model arguably offers a sub-optimal solution towards homeownership, or in terms of wider quality of life. Given the paucity of rigorous empirical work on this issue, this paper delineates the evidence so far and sets out a research agenda. Our analysis is based on a large dataset of new shared owners, observing an information base that spans the past decade. We then set out an agenda to further examine the behaviours of the SO occupants and to examine the implications for future public policy based on existing literature and our outline findings. This paper is particularly opportune at a time of economic uncertainty and an overriding ‘austerity’ drive in public funding in the UK, through which SO schemes have enjoyed support uninterruptedly thus far.

Unpacking the mechanism by which corporate responsibility impacts stakeholder relationships

Most research on corporate responsibility (CR) has investigated CR from the perspective of organizations, often focusing on how organizations define, manage and implement CR to gain benefits or competitive advantage. The benefits of CR for organizations are, however, often said to be achieved through increased support of stakeholders. Despite this, limited attention has been given to understanding CR from the perspective of stakeholders and, in particular, the mechanism by which CR drives stakeholder support. This study addresses this deficit. Building on advances in the application of psychological theories to the field of management, the research develops and empirically tests a theoretical model of how CR-related experiences and beliefs drive stakeholder trust and positive intent. The research is conducted with customers (n = 708) and employees (n = 359) of a service organization in the UK that introduced a range of CR-related activities into their business. The findings contribute to literature by empirically demonstrating (a) the impact of CR-related experiences on the development of beliefs about, and trust towards, the organization; (b) the importance of ‘others-related’ CR experiences even in the presence of ‘self-related’ CR experiences; and (c) the role of beliefs as partial mediators in how experiences of CR, both ‘self-related’ and ‘others-related’, translate into trust and positive intent.

Enhancing the catalytic repertoire of nucleic acids: a systematic study of linker length and rigidity

The incorporation of potentially catalytic groups in DNA is of interest for the in vitro selection of novel deoxyribozymes, A series of 10 C5-modified analogues of 2'-deoxyuridine triphosphate have been synthesised that possess side chains of differing flexibility and bearing a primary amino or imidazole functionality, For each series of nucleotide analogues differing degrees of flexibility of the C5 side chain was achieved through the use of alkynyl, alkenyl and alkyl moieties, The imidazole function was conjugated to these CS-amino-modified nucleotides using either imidazole 4-acetic acid or imidazole 4-acrylic acid (urocanic acid), The substrate properties of the nucleotides (fully replacing dTTP) with Taq polymerase during PCR have been investigated in order to evaluate their potential applications for in vitro selection experiments, 5-(3-Aminopropynyl)dUTP and 5-(E-3-aminopropenyl)dUTP and their imidazole 4-acetic acid- and urocanic acid-modified conjugates were found to be substrates, In contrast, C5-amino-modified dUTPs with alkane or Z-alkene linkers and their corresponding conjugates were not substrates, The incorporation of these analogues during PCR has been confirmed by inhibition of restriction enzyme digestion using XbaI and by mass spectrometry of the PCR products.

Mechanism of the Escherichia coli DNA T:G-mismatch endonuclease (Vsr protein) probed with thiophosphate-containing oligodeoxynucleotides

The mechanism of the Escherichia coli DNA T:G mismatch endonuclease (Vsr) has been investigated using oligodeoxynucleotides substituted, at the scissile phosphate, with isomeric phosphorothioates and a 3'-phosphorothiolate. Binding and kinetic data with the phosphorothioates/phosphorothiolate indicate that the two magnesium ions, which constitute essential co-factors, are required to stabilise the extra negative charge developed on the phosphate as the transition state is formed. Additionally one of the magnesium ions serves to activate the leaving group (the non-bridging 3'-oxygen atom of the scissile phosphate) during the hydrolysis reaction. Stereochemical analysis, using the R-p phosphorothioate isomer, indicates that Vsr carries out a hydrolytic reaction with inversion of stereochemistry at phosphorus, compatible with an in-line attack of water and a pentacovalent transition state with trigonal bipyramidal geometry. In conjunction with structures of Vsr bound to its products, these data allow the reconstruction of the enzyme-substrate complex and a comprehensive description of the hydrolysis mechanism. (c) 2005 Elsevier Ltd. All rights reserved.

A mechanism for the effect of tropospheric jet structure on the annular mode-like response to stratospheric forcing

For many climate forcings the dominant response of the extratropical circulation is a latitudinal shift of the tropospheric mid-latitude jets. The magnitude of this response appears to depend on climatological jet latitude in general circulation models (GCMs): lower latitude jets exhibit a larger shift. The reason for this latitude dependence is investigated for a particular forcing, heating of the equatorial stratosphere, which shifts the jet poleward. Spin-up ensembles with a simplified GCM are used to examine the evolution of the response for five different jet structures. These differ in the latitude of the eddy-driven jet, but have similar sub-tropical zonal winds. It is found that lower latitude jets exhibit a larger response due to stronger tropospheric eddy-mean flow feedbacks. A dominant feedback responsible for enhancing the poleward shift is an enhanced equatorward refraction of the eddies, resulting in an increased momentum flux, poleward of the low latitude critical line. The sensitivity of feedback strength to jet structure is associated with differences in the coherence of this behaviour across the spectrum of eddy phase speeds. In the configurations used, the higher latitude jets have a wider range of critical latitude locations. This reduces the coherence of the momentum flux anomalies associated with different phase speeds, with low phase speeds opposing the effect of high phase speeds. This suggests that, for a given sub-tropical zonal wind strength, the latitude of the eddy driven jet affects the feedback through its influence on the width of the region of westerly winds and the range of critical latitudes on the equatorward flank of the jet.

Age related changes in speed and mechanism of adult skeletal muscle stem cell migration

Skeletal muscle undergoes a progressive age-related loss in mass and function. Preservation of muscle mass depends in part on satellite cells, the resident stem cells of skeletal muscle. Reduced satellite cell function may contribute to the age-associated decrease in muscle mass. Here we focused on characterising the effect of age on satellite cell migration. We report that aged satellite cells migrate at less than half the speed of young cells. In addition, aged cells show abnormal membrane extension and retraction characteristics required for amoeboid based cell migration. Aged satellite cells displayed low levels of integrin expression. By deploying a mathematical model approach to investigate mechanism of migration, we have found that young satellite cells move in a random ‘memoryless’ manner whereas old cells demonstrate superdiffusive tendencies. Most importantly, we show that nitric oxide, a key regulator of cell migration, reversed the loss in migration speed and reinstated the unbiased mechanism of movement in aged satellite cells. Finally we found that although Hepatocyte Growth Factor increased the rate of aged satellite cell movement it did not restore the memoryless migration characteristics displayed in young cells. Our study shows that satellite cell migration, a key component of skeletal muscle regeneration, is compromised during aging. However, we propose clinically approved drugs could be used to overcome these detrimental changes.