Recent advances in global electric circuit coupling between the space environment and the troposphere

The global atmospheric electric circuit is driven by thunderstorms and electrified rain/shower clouds and is also influenced by energetic charged particles from space. The global circuit maintains the ionosphere as an equipotential at∼+250 kV with respect to the good conducting Earth (both land and oceans). Its “load” is the fair weather atmosphere and semi-fair weather atmosphere at large distances from the disturbed weather “generator” regions. The main solar-terrestrial (or space weather) influence on the global circuit arises from spatially and temporally varying fluxes of galactic cosmic rays (GCRs) and energetic electrons precipitating from the magnetosphere. All components of the circuit exhibit much variability in both space and time. Global circuit variations between solar maximum and solar minimum are considered together with Forbush decrease and solar flare effects. The variability in ion concentration and vertical current flow are considered in terms of radiative effects in the troposphere, through infra-red absorption, and cloud effects, in particular possible cloud microphysical effects from charging at layer cloud edges. The paper identifies future research areas in relation to Task Group 4 of the Climate and Weather of the Sun-Earth System (CAWSES-II) programme.

Systematic structural studies of iron superoxide dismutases from human parasites and a statistical coupling analysis of metal binding specificity

Superoxide dismutases (SODs) are a crucial class of enzymes in the combat against intracellular free radical damage. They eliminate superoxide radicals by converting them into hydrogen peroxide and oxygen. In spite of their very different life cycles and infection strategies, the human parasites Plasmodium falciparum, Trypanosoma cruzi and Trypanosoma brucei are known to be sensitive to oxidative stress. Thus the parasite Fe-SODs have become attractive targets for novel drug development. Here we report the crystal structures of FeSODs from the trypanosomes T. brucei at 2.0 angstrom and T. cruzi at 1.9 angstrom resolution, and that from P. falciparum at a higher resolution (2.0 angstrom) to that previously reported. The homodimeric enzymes are compared to the related human MnSOD with particular attention to structural aspects which are relevant for drug design. Although the structures possess a very similar overall fold, differences between the enzymes at the entrance to the channel which leads to the active site could be identified. These lead to a slightly broader and more positively charged cavity in the parasite enzymes. Furthermore, a statistical coupling analysis (SCA) for the whole Fe/MnSOD family reveals different patterns of residue coupling for Mn and Fe SODs, as well as for the dimeric and tetrameric states. In both cases, the statistically coupled residues lie adjacent to the conserved core surrounding the metal center and may be expected to be responsible for its fine tuning, leading to metal ion specificity.

The human side of project management - an investigation of critical chain concepts in the Argentinean Project Environment

The global marketplace is rapidly intensifying. Longer product sales lives, greater profit margins or simply survival, is dependent on management¿s ability to create and lead change. Project Management has become an important competency, combined with other business practices to adapt to the trend of changing conditions. Critical Chain is a relatively new project methodology, elaborated by Eliyahu Goldratt in order to complete projects faster, make more efficient use of resources and securing the project deliverables. The methodology is based on the assumption that traditional project techniques such as CPM and PERT, do not recognize critical human behavior. The methodology claims that many project failures are a direct result of how safety is built into the task delivery times, and then wasted by human behavior such as Student Syndrome, Parkinson Law and Multitasking. However, there has been little or no previous research regarding this topic in the Argentine marketplace. This study intended to investigate to what extent the human behavior concepts of critical chain project management are present, by performing in-depth interviews with Argentine project stakeholders. It appears that the four human behavior concepts are present in Argentina and that the majority of Argentine companies are yet to apply project management techniques.

Interactions between environment, wild animals and human leptospirosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relations between population, resources and environment in Latin America, specially with relation to human settlement: preliminary version

Includes bibliography

Coupling between upper ocean layer variability and size-fractionated phytoplankton in a non-nutrient-limited environment

[EN] We describe the coupling between upper ocean layer variability and size-fractionated phytoplankton distribution in the non-nutrient-limited Bransfield Strait region (BS) of Antarctica. For this purpose we use hydrographic and size-fractionated chlorophyll a data from a transect that crossed 2 fronts and an eddy, together with data from 3 stations located in a deeply mixed region, the Antarctic Sound (AS). In the BS transect, small phytoplankton (<20 μm equivalent spherical diameter [ESD]) accounted for 80% of total chl a and their distribution appeared to be linked to cross-frontal variability. On the deepening upper mixed layer (UML) sides of both fronts we observed a deep subducting column-like structure of small phytoplankton biomass. On the shoaling UML sides of both fronts, where there were signs of restratification, we observed a local shallow maximum of small phytoplankton biomass. We propose that this observed phytoplankton distribution may be a response to the development of frontal vertical circulation cells. In the deep, turbulent environment of the AS, larger phytoplankton (>20 μm ESD) accounted for 80% of total chl a. The proportion of large phytoplankton increases as the depth of the upper mixed layer (ZUML), and the corresponding rate of vertical mixing, increases. We hypothesize that this change in phytoplankton composition with varying ZUML is related to the competition for light, and results from modification of the light regime caused by vertical mixing.

Climate Change and International Law. Exploring the Linkages Between Human Rights, Environment, Trade and Investment

Mapping the relevant principles and norms of international law, the paper discusses scientific evidence and identifies current legal foundations of climate change mitigation adaptation and communication in international environmental law, human rights protection and international trade regulation in WTO law. It briefly discusses the evolution and architecture of relevant multilateral environmental agreements, in particular the UN Framework Convention on Climate Change. It discusses the potential role of human rights in identifying pertinent goals and values of mitigation and adaptation and eventually turns to principles and rules of international trade regulation and investment protection which are likely to be of crucial importance should the advent of a new multilateral agreement fail to materialize. The economic and legal relevance of rules on tariffs, border tax adjustment and subsidies, services and intellectual property and investment law are discussed in relation to the production, supply and use of energy. Moreover, lessons from trade negotiations may be drawn for negotiations of future environmental instruments. The paper offers a survey of the main interacting areas of public international law and discusses the intricate interaction of all these components informing climate change mitigation, adaptation and communication in international law in light of an emerging doctrine of multilayered governance. It seeks to contribute to greater coherence of what today is highly fragmented and rarely discussed in an overall context. The paper argues that trade regulation will be of critical importance in assessing domestic policies and potential trade remedies offer powerful incentives for all nations alike to participate in a multilateral framework defining appropriate goals and principles.

Book Review of “Human Behaviour and the Social Environment: Models, Metaphors, and Maps for Applying Theoretical Perspectives to Practice”. 640 pages, Thomson Brooks/Cole, 2007, by James A. Forte

This voluminous book which draws on almost 1000 references provides an important theoretical base for practice. After an informative introduction about models, maps and metaphors, Forte provides an impressive presentation of several perspectives for use in practice; applied ecological theory, applied system theory, applied biology, applied cognitive science, applied psychodynamic theory, applied behaviourism, applied symbolic interactionism, applied social role theory, applied economic theory, and applied critical theory. Finally he completes his book with a chapter on “Multi theory practice and routes to integration.”

Listeria monocytogenes infection in ruminants: Is there a link to the environment, food and human health? A review.

Listeria (L.) monocytogenes is widely distributed in the environment, but also has the ability to cause serious invasive disease in ruminants and humans. This review provides an overview of listeriosis in ruminants and discusses our insufficient understanding of reservoirs and possible cycling ofL. monocytogenes between animal and human hosts, food and the environment. It indicates gaps in our knowledge of the role of genetic subtypes in L. monocytogenes ecology and virulence as well as risk factors, in vivo diagnostics and pathogenesis of listeriosis in ruminants. Filling these gaps will contribute to improving the control of L. monocytogenes and enhancing disease prevention. As the prevalence of listeriosis in ruminants in Switzerland is likely to be underestimated, propositions concerning improvement options for surveillance of listeriosis in ruminants are provided.

Dynamic gamma frequency feedback coupling between higher and lower order visual cortices underlies perceptual completion in humans

To perceive a coherent environment, incomplete or overlapping visual forms must be integrated into meaningful coherent percepts, a process referred to as ?Gestalt? formation or perceptual completion. Increasing evidence suggests that this process engages oscillatory neuronal activity in a distributed neuronal assembly. A separate line of evidence suggests that Gestalt formation requires top-down feedback from higher order brain regions to early visual cortex. Here we combine magnetoencephalography (MEG) and effective connectivity analysis in the frequency domain to specifically address the effective coupling between sources of oscillatory brain activity during Gestalt formation. We demonstrate that perceptual completion of two-tone ?Mooney? faces induces increased gamma frequency band power (55?71 Hz) in human early visual, fusiform and parietal cortices. Within this distributed neuronal assembly fusiform and parietal gamma oscillators are coupled by forward and backward connectivity during Mooney face perception, indicating reciprocal influences of gamma activity between these higher order visual brain regions. Critically, gamma band oscillations in early visual cortex are modulated by top-down feedback connectivity from both fusiform and parietal cortices. Thus, we provide a mechanistic account of Gestalt perception in which gamma oscillations in feature sensitive and spatial attention-relevant brain regions reciprocally drive one another and convey global stimulus aspects to local processing units at low levels of the sensory hierarchy by top-down feedback. Our data therefore support the notion of inverse hierarchical processing within the visual system underlying awareness of coherent percepts.

CD68+ cells of monocyte/macrophage lineage in the environment of AIDS-associated and classic-sporadic Kaposi sarcoma are singly or doubly infected with human herpesviruses 7 and 6B

Earlier studies have shown that Kaposi sarcomas contain cells infected with human herpesvirus (HHV) 6B, and in current studies we report that both AIDS-associated and classic-sporadic Kaposi sarcoma contain HHV-7 genome sequences detectable by PCR. To determine the distribution of HHV-7-infected cells relative to those infected with HHV-6, sections from paraffin-embedded tissues were allowed to react with antibodies to HHV-7 virion tegument phosphoprotein pp85 and to HHV-6B protein p101. The antibodies are specific for HHV-7 and HHV-6B, respectively, and they retained reactivity for antigens contained in formalin-fixed, paraffin-embedded tissue samples. We report that (i) HHV-7 pp85 was present in 9 of 32 AIDS-associated Kaposi sarcomas, and in 1 of 7 classical-sporadic HIV-negative Kaposi sarcomas; (ii) HHV-7 pp85 was detected primarily in cells bearing the CD68 marker characteristic of the monocyte/macrophage lineage present in or surrounding the Kaposi sarcoma lesions; and (iii) in a number of Kaposi sarcoma specimens, tumor-associated CD68+ monocytes/macrophages expressed simultaneously antigens from both HHV-7 and HHV-6B, and therefore appeared to be doubly infected with the two viruses. CD68+ monocytes/macrophages infected with HHV-7 were readily detectable in Kaposi sarcoma, but virtually absent from other normal or pathological tissues that harbor macrophages. Because all of the available data indicate that HHV-7 infects CD4+ T lymphocytes, these results suggest that the environment of the Kaposi sarcoma (i) attracts circulating peripheral lymphocytes and monocytes, triggers the replication of latent viruses, and thereby increases the local concentration of viruses, (ii) renders CD68+ monocytes/macrophages susceptible to infection with HHV-7, and (iii) the combination of both events enables double infections of cells with both HHV-6B and HHV-7.

Identification and characterization of periplasmic proteins implicated in the adaptation of Helicobacter pylori to the human gastric niche

Helicobacter pylori è un batterio Gram-negativo in grado di colonizzare la mucosa gastrica umana e persistere per l'intero arco della vita dell'ospite. E' associato a patologie gastrointestinali, quali gastrite cronica, ulcere gastriche e duodenali, adenocarcinomi e linfomi gastrici. Si tratta di uno dei patogeni più diffusi, presente in circa metà della popolazione mondiale, e il solo che si è adattato a vivere nell'ambiente ostile dello stomaco umano. Molteplici sono i fattori di virulenza che permettono al batterio la colonizzazione della nicchia gastrica e contribuiscono, anche attraverso l' induzione di una risposta infiammatoria, a profonde modificazioni dell' omeostasi gastrica. Queste ultime si associano, ad esempio, all'iperproduzione di fattori proinfiammatori, ad alterazioni sia della regolazione della secrezione acida gastrica sia del ciclo cellulare e della morte cellulare programmata (apoptosi) delle cellule epiteliali gastriche, a disordini nel metabolismo del ferro e a carenze di elementi essenziali. Studi sulla diversità genetica di H. pylori osservata in ceppi isolati da varie regioni del mondo, dimostrano che tale batterio ha avuto una coevoluzione col genere umano attraverso la storia, ed è verosimile che H. pylori sia stato un costituente del microbiota gastrico per almeno 50.000 anni. Scopo della tesi è stato quello di identificare e caratterizzare proteine importanti per la colonizzazione e l'adattamento di H. pylori alla nicchia gastrica. In particolare gli sforzi si sono concentrati su due proteine periplasmatiche, la prima coinvolta nella difesa antiossidante (l'enzima catalasi-like, HP0485), e la seconda nel trasporto di nutrienti presenti nell'ambiente dello stomaco all'interno della cellula (la componente solubile di un ABC transporter, HP0298). La strategia utilizzata prevede un'analisi bioinformatica preliminare, l'ottenimento del gene per amplificazione, mediante PCR, dal genoma dell'organismo, la costruzione di un vettore per il clonaggio, l'espressione eterologa in E. coli e la successiva purificazione. La proteina così ottenuta viene caratterizzata mediante diverse tecniche, quali spettroscopia UV, dicroismo circolare, gel filtrazione analitica, spettrometria di massa. Il capitolo 1 contiene un'introduzione generale sul batterio, il capitolo 2 e il capitolo 3 descrivono gli studi relativi alle due proteine e sono entrambi suddivisi in un abstract iniziale, un'introduzione, la presentazione dei risultati, la discussione di questi ultimi, i materiali e i metodi utilizzati. La catalasi-like (HP0485) è una proteina periplasmatica con struttura monomerica, appartenente ad una famiglia di enzimi a funzione per la maggior parte sconosciuta, ma evolutivamente correlati alla ben nota catalasi, attore fondamentale nella difesa di H. pylori, grazie alla sua azione specifica di rimozione dell'acqua ossigenata. HP0485, pur conservando il fold catalasico e il legame al cofattore eme, non può compiere la reazione di dismutazione dell'acqua ossigenata; possiede invece un'attività perossidasica ad ampio spettro, essendo in grado di accoppiare la riduzione del perossido di idrogeno all'ossidazione di diversi substrati. Come la catalasi, lavora ad alte concentrazioni di aqua ossigenata e non arriva a saturazione a concentrazioni molto elevate di questo substrato (200 mM); la velocità di reazione catalizzata rimane lineare anche a questi valori, aspetto che la differenzia dalle perossidasi che vengono in genere inattivate da concentrazioni di perossido di idrogeno superiori a 10-50 mM. Queste caratteristiche di versatilità e robustezza suggeriscono che la catalasi-like abbia un ruolo di scavenger dell'acqua ossigenata e probabilmente anche un'altra funzione connessa al suo secondo substrato, ossia l'ossidazione di composti nello spazio periplasmatico cellulare. Oltre alla caratterizzazione dell'attività è descritta anche la presenza di un ponte disolfuro, conservato nelle catalasi-like periplasmatiche, con un ruolo nell'assemblaggio dell'eme per ottenere un enzima attivo e funzionale. La proteina periplasmatica HP0298, componente di un sistema di trasporto ABC, è classificata come trasportatore di dipeptidi e appartiene a una famiglia di proteine in grado di legare diversi substrati, tra cui di- e oligopeptidi, nichel, eme, glutatione. Benchè tutte associate a trasportatori di membrana batterici, queste proteine presentano un dominio di legame al substrato che risulta essere conservato nei domini extracellulari di recettori specifici di mammifero e uomo. Un esempio sono i recettori ionotropici e metabotropici del sistema nervoso. Per caratterizzare questa proteina è stato messo a punto un protocollo di ligand-fishing accoppiato alla spettrometria di massa. La proteina purificata, avente un tag di istidine, è stata incubata con un estratto cellulare di H. pylori per poter interagire con il suo substrato specifico all'interno dell'ambiente naturale in cui avviene il legame. Il complesso proteina-ligando è stato poi purificato per cromatografia di affinità e analizzato mediante HPLC-MS. L'identificazione dei picchi differenziali tra campioni con la proteina e 5 campioni di controllo ha portato alla caratterizzazione di pentapeptidi particolarmente ricchi in aminoacidi idrofobici e con almeno un residuo carico negativamente. Considerando che H. pylori necessita di alcuni aminoacidi essenziali, per la maggior parte idrofobici, e che lo stomaco umano è particolarmente ricco di peptidi prodotti dalla digestione delle proteine introdotte con il cibo, il ruolo fisiologico di HP0298 potrebbe essere l'internalizzazione di peptidi, con caratteristiche specifiche di lunghezza e composizione, che sono naturalmente presenti nella nicchia gastrica.