Selenium cycling in volcanic environments: the role of soils as reactive interfaces

Selenium (Se) is an element with important health implications that is emitted in significant amounts from volcanoes. Attracted by the fertility of volcanic soils, around 10% of the world population lives within 100 km of an active volcano. Nevertheless, the behaviour of Se in volcanic environments is poorly understood. Therefore, the main aim of this thesis is to investigate the role of soils in the Se cycling in volcanic environments. Prior to the geochemical studies, precise and accurate methods for the determination of Se contents, speciation and isotopic signatures were developed. Afterwards, a combination of field studies and lab controlled experiments were performed with soils from two contrasting European volcanic settings: Mount Etna in Sicily (Italy) and Mount Teide in Tenerife (Spain). The results showed a strong link between Se behaviour and soil development, indicating that Se mobility in volcanic soils is controlled by sorption processes and soil mineralogy.

Mechanism of action of cyclic antimicrobial peptides

This PhD thesis is the result of the combination of experimental and computational techniques with the aim of understanding the mechanism of action of de novo cyclic decapeptides with high antimicrobial activity. By experimental techniques the influence of the replacement of the phenylalanine for tryptophan residue in their antimicrobial activity was tested and the stability in human serum was also analyzed, in order to evaluate their potential therapeutic application as antitumor agents. On the other hand, the interaction amongst the peptide BPC194 c(KKLKKFKKLQ), the best candidate from the whole library of cyclic peptides, and a model anionic membrane was simulated. The results showed a structure-function relationship derived from the stable conformation of the peptides involved in the membrane permeabilization. As a result, a rational design was performed being BPC490 the peptide with best antimicrobial activity compared with the best active peptide from the original library.

Laughing in the mechanism : du choix du silence comme élément autobiographique dans le poème ''Agrippa'' de William Gibson (1992)

Le silence est une composante fondamentale de la création artistique, aussi bien dans le domaine musical qu’au cinéma. La notion de silence atteint toutefois un espace limite dans le domaine littéraire, comme le note Gilles Deleuze en évoquant le « silence dans les mots », la « limite asyntaxique » qui n’est pas « extérieure au langage » dans la poésie d’Antonin Artaud ; cette même notion devenant plus problématique encore dans le domaine de l’autobiographie, traditionnellement informative. Nous posons tout d’abord la question de savoir comment l’auteur, se racontant lui-même, sa vie, son parcours, peut choisir de ne donner à lire qu’un silence plus ou moins long, et sembler ainsi renoncer à sa tâche, pour ensuite étudier le poème « Agrippa—A Book of the Dead » (1992) de l’écrivain américain William Gibson (né en 1948). Inspiré par la découverte d’un album de photos appartenant à son père, l’auteur y évoque les souvenirs de son enfance en Virginie. La singularité d’« Agrippa » réside surtout dans les mécanismes mis en oeuvre lors de sa lecture : à l’origine seulement disponible sur disquette, un programme d’ « encryption » ou « bombe logique » efface le texte au fur et à mesure que l’ordinateur le déchiffre, afin de n’être lu qu’une fois seulement, laissant la place au vide, au silence. Nous proposons ici d’étudier le poème « Agrippa » en démontrant comment la disparition progressive du texte a, dans le travail d’écriture de Gibson, une portée originale. L’objectif de l’étude est de montrer que Gibson se sert du poème pour proposer une révolution littéraire où l’art « quitte le cadre », où « le mot écrit quitte la page » de façon concrète et effective pour soumettre au lecteur un questionnement, esthétique, philosophique, voire théologique fécond – Maurice Blanchot arguant que Dieu communique « seulement par son silence ».

Europe's single supervisory mechanism and the long journey towards banking union. Bruegel Policy Contribution 2012/16, 4 October 2012

Problems in the banking system are at the core of the current crisis. The establishment of a banking union is a necessary (though not sufficient) condition for eventual crisis resolution that respects the integrity of the euro. The European Commission’s proposal for the establishment of a Single Supervisory Mechanism and related reform of the European Banking Authority (EBA) do not and cannot create a fully-fledged banking union, but represent a broadly adequate step on the basis of the leaders’ declaration of 29 June 2012 and of the decision to use Article 127(6) of the treaty as legal basis. The proposal rightly endows the European Central Bank (ECB) with broad authority over banks within the supervisory mechanism’s geographical perimeter; however, the status of non-euro area member states willing to participate in this mechanism, and the governance and decision-making processes of the ECB in this respect, call for further elaboration. Further adjustments are also desirable in the proposed reform of the EBA, even though they must probably retain a stopgap character pending the more substantial review planned in 2014.

The Future of the Clean Development Mechanism. Note on the report “A Call to Action” of the High-Level Panel on CDM Policy Dialogue. CEPS Special Report No. 71, 20 November 2012

The clean development mechanism (CDM) has been through a long and complex growing process since it was approved as part of the Kyoto Protocol. It was designed within the framework of the UNFCCC and the Kyoto Protocol, and reflected the political and economic realities of that time. To ensure its continued effectiveness in contributing to future global climate action and to reflect on how best to position the CDM to respond to future challenges, a high-level panel (HLP) was formed at the Durban climate change conference in 2011. Following extensive consultations, the panel published its report in September 2012. Through this Special Report, the CEPS Carbon Market Forum offers its reflections on findings and recommendations of the HLP, as well as, by extension, its own views on the future of the CDM. In the context of the latter, it explores the following questions: Is there a need for an instrument such as the CDM in the future? What ‘demand’ can it fill? In the roles identified under the first question, what can be done to adapt it and also continue to increase its efficacy?

Reactive Halogens in the Marine Boundary Layer (RHaMBLe): the tropical North Atlantic experiments

The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth, UK was used to characterise the spatial distribution of boundary layer components likely to play a role in reactive halogen chemistry. Measurements onboard the ARSF Dornier aircraft were used to allow the observations to be interpreted in the context of their vertical distribution and to confirm the interpretation of atmospheric structure in the vicinity of the Cape Verde islands. Long-term ground-based measurements at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente were supplemented by long-term measurements of reactive halogen species and characterisation of additional trace gas and aerosol species during the intensive experimental period. This paper presents a summary of the measurements made within the RHaMBLe remote experiments and discusses them in their meteorological and chemical context as determined from these three platforms and from additional meteorological analyses. Air always arrived at the CVAO from the North East with a range of air mass origins (European, Atlantic and North American continental). Trace gases were present at stable and fairly low concentrations with the exception of a slight increase in some anthropogenic components in air of North American origin, though NOx mixing ratios during this period remained below 20 pptv. Consistency with these air mass classifications is observed in the time series of soluble gas and aerosol composition measurements, with additional identification of periods of slightly elevated dust concentrations consistent with the trajectories passing over the African continent. The CVAO is shown to be broadly representative of the wider North Atlantic marine boundary layer; measurements of NO, O3 and black carbon from the ship are consistent with a clean Northern Hemisphere marine background. Aerosol composition measurements do not indicate elevated organic material associated with clean marine air. Closer to the African coast, black carbon and NO levels start to increase, indicating greater anthropogenic influence. Lower ozone in this region is possibly associated with the increased levels of measured halocarbons, associated with the nutrient rich waters of the Mauritanian upwelling. Bromide and chloride deficits in coarse mode aerosol at both the CVAO and on D319 and the continuous abundance of inorganic gaseous halogen species at CVAO indicate significant reactive cycling of halogens. Aircraft measurements of O3 and CO show that surface measurements are representative of the entire boundary layer in the vicinity both in diurnal variability and absolute levels. Above the inversion layer similar diurnal behaviour in O3 and CO is observed at lower mixing ratios in the air that had originated from south of Cape Verde, possibly from within the ITCZ. ECMWF calculations on two days indicate very different boundary layer depths and aircraft flights over the ship replicate this, giving confidence in the calculated boundary layer depth.

Does reactive surface area depend on grain size? Results from pH 3, 25 circle C far-from-equilibrium flow-through dissolution experiments on anorthite and biotite

Laboratory determined mineral weathering rates need to be normalised to allow their extrapolation to natural systems. The principle normalisation terms used in the literature are mass, and geometric- and BET specific surface area (SSA). The purpose of this study was to determine how dissolution rates normalised to these terms vary with grain size. Different size fractions of anorthite and biotite ranging from 180-150 to 20-10 mu m were dissolved in pH 3, HCl at 25 degrees C in flow through reactors under far from equilibrium conditions. Steady state dissolution rates after 5376 h (anorthite) and 4992 h (biotite) were calculated from Si concentrations and were normalised to initial- and final- mass and geometric-, geometric edge- (biotite), and BET SSA. For anorthite, rates normalised to initial- and final-BET SSA ranged from 0.33 to 2.77 X 10(-10) mol(feldspar) m(-2) s(-1), rates normalised to initial- and final-geometric SSA ranged from 5.74 to 8.88 X 10(-10) mol(feldspar) m(-2) s(-1) and rates normalised to initial- and final-mass ranged from 0.11 to 1.65 mol(feldspar) g(-1) s(-1). For biotite, rates normalised to initial- and final-BET SSA ranged from 1.02 to 2.03 X 10(-12) mol(biotite) m(-2) s(-1), rates normalised to initial- and final-geometric SSA ranged from 3.26 to 16.21 X 10(-12) mol(biotite) m(-2) s(-1), rates normalised to initial- and final-geometric edge SSA ranged from 59.46 to 111.32 x 10(-12) mol(biotite) m(-2) s(-1) and rates normalised to initial- and final-mass ranged from 0.81 to 6.93 X 10(-12) mol(biotite) g(-1) s(-1). For all normalising terms rates varied significantly (p <= 0.05) with grain size. The normalising terms which gave least variation in dissolution rate between grain sizes for anorthite were initial BET SSA and initial- and final-geometric SSA. This is consistent with: (1) dissolution being dominated by the slower dissolving but area dominant non-etched surfaces of the grains and, (2) the walls of etch pits and other dissolution features being relatively unreactive. These steady state normalised dissolution rates are likely to be constant with time. Normalisation to final BET SSA did not give constant ratios across grain size due to a non-uniform distribution of dissolution features. After dissolution coarser grains had a greater density of dissolution features with BET-measurable but unreactive wall surface area than the finer grains. The normalising term which gave the least variation in dissolution rates between grain sizes for biotite was initial BET SSA. Initial- and final-geometric edge SSA and final BET SSA gave the next least varied rates. The basal surfaces dissolved sufficiently rapidly to influence bulk dissolution rate and prevent geometric edge SSA normalised dissolution rates showing the least variation. Simple modelling indicated that biotite grain edges dissolved 71-132 times faster than basal surfaces. In this experiment, initial BET SSA best integrated the different areas and reactivities of the edge and basal surfaces of biotite. Steady state dissolution rates are likely to vary with time as dissolution alters the ratio of edge to basal surface area. Therefore they would be more properly termed pseudo-steady state rates, only appearing constant because the time period over which they were measured (1512 h) was less than the time period over wich they would change significantly. (c) 2006 Elsevier Inc. All rights reserved.

Reactive crisis management in construction projects

Patterns of communication and behaviour emerge within a construction project in response to a construction crisis. This paper investigates, within a grounded theory framework, the nature of these patterns, the sociological and psychological forces which shape them and their relationship with crisis management efficiency. A grounded theory is presented in four parts. The first part conceives a construction crisis as a period of social instability, arising from conflicting interest groups, seeking to exercise power in the pursuit of social structures which suit their political and economic interests. The second part sees a construction crisis as a de-sensitizing phenomenon which results in a period of behavioural instability and conflict which is self-perpetuating. The third part cites social structure as an important influence upon construction crisis management efficiency, in determining the efficiency of information flow, and the level of uncertainty between those affected. The fourth part points to the in-built defence mechanisms which construction crises have and to three managerial ironies which make construction crisis management difficult.