Structure and function of natural sulphide-oxidizing microbial mats under dynamic input of light and chemical energy

We studied the interaction between phototrophic and chemolithoautotrophic sulphide-oxidizing microorganisms in natural microbial mats forming in sulphidic streams. The structure of these mats varied between two end-members: one characterized by a layer dominated by large sulphur-oxidizing bacteria (SOB; mostly Beggiatoa-like) on top of a cyanobacterial layer (B/C mats) and the other with an inverted structure (C/B mats). C/B mats formed where the availability of oxygen from the water column was limited (<5 mu M). Aerobic chemolithotrophic activity of the SOB depended entirely on oxygen produced locally by cyanobacteria during high light conditions. In contrast, B/C mats formed at locations where oxygen in the water column was comparatively abundant (445 mu M) and continuously present. Here SOB were independent of the photosynthetic activity of cyanobacteria and outcompeted the cyanobacteria in the uppermost layer of the mat where energy sources for both functional groups were concentrated. Outcompetition of photosynthetic microbes in the presence of light was facilitated by the decoupling of aerobic chemolithotrophy and oxygenic phototrophy. Remarkably, the B/C mats conserved much less energy than the C/B mats, although similar amounts of light and chemical energy were available. Thus ecosystems do not necessarily develop towards optimal energy usage. Our data suggest that, when two independent sources of energy are available, the structure and activity of microbial communities is primarily determined by the continuous rather than the intermittent energy source, even if the time-integrated energy flux of the intermittent energy source is greater

Technical report on chemical sensors performance

The report will present an overview of sensors that are useful for the study of seeps, and present a detailed comparison of commercial and prototype CO2 and pH sensors. CO2 sensors: 1) Severinghaus CO2 sensors (Microelectrodes ltd), 2) the HydroC-­‐CO2 logger sensor (CONTROS GmbH), 3) the “GasPro-­‐pCO2” (developed by the team coordinated by Prof. S. Lombardi; Sapienza -­‐ University of Rome-­‐CERI), 4) the MuFo (Multifiber Optode logger, developed in this project in a collaboration between Prof. I. Klimant University Graz and the MPI-­‐MM). pH sensors: 1) glass electrodes Microelectrodes ltd), 2) optodes (developed in this project in a collaboration between Prof. I. Klimant University Graz and the MPI-­‐MM), 3) SeaFET (ion-­‐selective field-­‐effect transistor, Satlantic)

Using stories to assist storytelling in a pastoral setting: Four female pastors in dialogue with Mary Magdalene

Sometimes we need a source of encouragement for restoring our own lives, to help us re-create ourselves. Using text as narrative texts opens up a multitude of possibilities in the work with clients in therapy. The story of Mary Magdalene told in John 20:11–18 is considered to be a healing story. This article aims to retell the story of her encounter with the resurrected Jesus, using the Gospel of Mary as an enlightening intertext. Because the story of Mary Magdalene’s encounter with Jesus is used as a healing story, the basic principles of transformative narrative theory are considered tobe useful in the analysis of this text. Mary Magdalene’s story is then discussed with three female pastors of the Netherdutch Reformed Church of Africa. The research opened up a discussion about spirituality. This article would be incomplete without reflecting on the spirituality stories of the group of co-researchers

the enforcement of socio-economic rights

In recent years the South African legislature has made a very bold attempt to improve the socio-economic conditions of citizens. Amongst others, the Social Assistance Act 59 of 1992 provides for monthly payments to citizens under certain prescribed conditions. In situations where other legislation does not provide a remedy for those unable to care for themselves the Constitution provides for justiciable socio-economic rights. Unfortunately legislative rights alone have proved insufficient and all too frequently the constitutional values and aspirations of human dignity and equality have had a ‘hollow ring’. The most obvious reason for this failure of delivery on the part of the government is of course a shortage of financial resources. Another reason has been a simple disregard for the terms of legislation and court orders by organs of the state and state employees. The authors are of the view that in order to avoid such a dire result, the courts, given their broadly framed constitutional powers, should be adventurous in crafting means to ensure that their orders are properly implemented and adhered to. This article explores the role that courts can play in ensuring proper implementation of both the terms of social security legislation as well as the implementation of court orders with reference to well-fare judgments in the Eastern-Cape

A Killing Disease Epidemic Among Displaced Sudanese Population Identified as Visceral Leishmaniasis.

A fatal disease epidemic affected the Bentiu area in southern Sudan and led to a mass migration of the Nuer tribe searching for treatment. The initially available information revealed a high mortality rate due to a possible occurrence of tuberculosis, malaria, enteric fever or visceral leishmaniasis (VL). Serological screening of 53 of the most severely affected patients in an enzyme-linked immunosorbent assay (ELISA) or an improved direct agglutination test (DAT) revealed positivity for VL. In 39 of those patients, diagnosis was confirmed by identification of Leishmania donovani amastigotes in lymph node or bone-marrow aspirates. In a total of 2714 patients observed, 1195 (44.0%) had clinical symptoms suggesting VL: DAT positive titers (1:3200-greater than or equal to 1:12800) were obtained in 654 (24.1%), of whom 325 were confirmed parasitologically. Forty-two VL cases died before or during treatment, giving a mortality rate of 6.4%. Among the intercurrent infections diagnosed in the VL population (654), respiratory involvements (31.7%) and malaria (10.7%) were most prevalent. With the exception of four (0.6%), all other VL patients (509) responded readily to sodium stibogluconate. The factors initiating the outbreak are discussed. Malnutrition and nomadic movements to potential VL endemic areas appeared to be the most important. HIV infection as a possible predisposition seemed remote considering the clinical and epidemiological similarity to VL occurring in East Africa, adequate humoral response in DAT, and immediate positive response to specific anti-Leishmania chemotherapy

Calcaneal fractures in children

Eight patients with 9 calcaneal fractures were reviewed. Of the fractures 6 were intra articular and 3 extra-articular but in children this distinction appears to have little relevance to treatment or prognosis. While these fractures are relatively uncommon in children, clinical suspicion is important in making the diagnosis, since the presentation may be subtle. The overall prognosis in children is excellent

High-Resolution Dynamics of Hydrogen Peroxide on the Surface of Scleractinian Corals in Relation to Photosynthesis and Feeding

We developed and used a microsensor to measure fast (<1 s) dynamics of hydrogen peroxide (H2O2) on the polyp tissue of two scleractinian coral species (Stylophora pistillata and Pocillopora damicornis) under manipulations of illumination, photosynthesis, and feeding activity. Our real-time tracking of H2O2 concentrations on the coral tissue revealed rapid changes with peaks of up to 60 mu M. We observed bursts of H2O2 release, lasting seconds to minutes, with rapid increase and decrease of surficial H2O2 levels at rates up to 15 mu M s(-1). We found that the H2O2 levels on the polyp surface are enhanced by oxygenic photosynthesis and feeding, whereas H2O2 bursts occurred randomly, independently from photosynthesis. Feeding resulted in a threefold increase of baseline H2O2 levels and was accompanied by H2O2 bursts, suggesting that the coral host is the source of the bursts. Our study reveals that H2O2 levels at the surface of coral polyps are much higher and more dynamic than previously reported, and that bursts are a regular feature of the H2O2 dynamics in the coral holobiont