Role of hydrodynamic factors in controlling the formation and location of unconformity-related uranium deposits: insights from reactive-flow modeling

The role of hydrodynamic factors in controlling the formation and location of unconformity-related uranium (URU) deposits in sedimentary basins during tectonically quiet periods is investigated. A number of reactive-flow modeling experiments at the deposit scale were carried out by assigning different dip angles and directions to a fault and various permeabilities to hydrostratigraphic units). The results show that the fault dip angle and direction, and permeability of the hydrostratigraphic units govern the convection pattern, temperature distribution, and uranium mineralization. Avertical fault results in uranium mineralization at the bottom of the fault within the basement, while a dipping fault leads to precipitation of uraninite below the unconformity either away from or along the plane of the fault, depending on the fault permeability. A more permeable fault causes uraninite precipitates along the fault plane,whereas a less permeable one gives rise to the precipitation of uraninite away from it. No economic ore mineralization can form when either very low or very high permeabilities are assigned to the sandstone or basement suggesting that these units seem to have an optimal window of permeability for the formation of uranium deposits. Physicochemical parameters also exert an additional control in both the location and grade of URU deposits. These results indicate that the difference in size and grade of different URU deposits may result from variation in fluid flow pattern and physicochemical conditions, caused by the change in structural features and hydraulic properties of the stratigraphic units involved

Spectrum and antibiotic sensitivity of bacteria contaminating the upper gut in patients with malabsorption syndrome from the tropics

BACKGROUND: Various causes of malabsorption syndrome (MAS) are associated with intestinal stasis that may cause small intestinal bacterial overgrowth (SIBO). Frequency, nature and antibiotic sensitivity of SIBO in patients with MAS are not well understood. METHODS: Jejunal aspirates of 50 consecutive patients with MAS were cultured for bacteria and colony counts and antibiotic sensitivity were performed. Twelve patients with irritable bowel syndrome were studied as controls. RESULTS: Culture revealed growth of bacteria in 34/50 (68%) patients with MAS and 3/12 controls (p < 0.05). Colony counts ranged from 3 × 10(2 )to 10(15 )(median 10(5)) in MAS and 100 to 1000 (median 700) CFU/ml in controls (p 0.003). 21/50 (42%) patients had counts ≥10(5 )CFU/ml in MAS and none of controls (p < 0.05). Aerobes were isolated in 34/34 and anaerobe in 1/34. Commonest Gram positive and negative bacteria were Streptococcus species and Escherichia coli respectively. The isolated bacteria were more often sensitive to quinolones than to tetracycline (ciprofloxacin: 39/47 and norfloxacin: 34/47 vs. tetracycline 19/47, <0.01), ampicillin, erythromycin and co-trimoxazole (21/44, 14/22 and 24/47 respectively vs. tetracycline, p = ns). CONCLUSIONS: SIBO is common in patients with MAS due to various causes and quinolones may be the preferred treatment. This needs to be proved further by a randomized controlled trial

Big Food, Food Systems, and Global Health

In an article that forms part of the PLoS Medicine series on Big Food, guest editors David Stuckler and Marion Nestle lay out why more examination of the food industry is necessary, and offer three competing views on how public health professionals might engage with Big Food

Ordering theories: typologies and conceptual frameworks for sociotechnical change

What theories or concepts are most useful at explaining socio technical change? How can – or cannot – these be integrated? To provide an answer, this study presents the results from 35 semi-structured research interviews with social science experts who also shared more than two hundred articles, reports and books on the topic of the acceptance, adoption, use, or diffusion of technology. This material led to the identification of 96 theories and conceptual approaches spanning 22 identified disciplines. The article begins by explaining its research terms and methods before honing in on a combination of fourteen theories deemed most relevant and useful by the material. These are: Sociotechnical Transitions, Social Practice Theory, Discourse Theory, Domestication Theory, Large Technical Systems, Social Construction of Technology, Sociotechnical Imaginaries, Actor-Network Theory, Social Justice Theory, Sociology of Expectations, Sustainable Development, Values Beliefs Norms Theory, Lifestyle Theory, and the Unified Theory of Acceptance and Use of Technology. It then positions these theories in terms of two distinct typologies. Theories can be placed into five general categories of being centered on agency, structure, meaning, relations or norms. They can also be classified based on their assumptions and goals rooted in functionalism, interpretivism, humanism or conflict. The article lays out tips for research methodology before concluding with insights about technology itself, analytical processes associated with technology, and the framing and communication of results. An interdisciplinary theoretical and conceptual inventory has much to offer students, analysts and scholars wanting to study technological change and society

Bowel management for the treatment of pediatric fecal incontinence

Fecal incontinence is a devastating underestimated problem, affecting a large number of individuals all over the world. Most of the available literature relates to the management of adults. The treatments proposed are not uniformly successful and have little application in the pediatric population. This paper presents the experience of 30 years, implementing a bowel management program, for the treatment of fecal incontinence in over 700 pediatric patients, with a success rate of 95%. The main characteristics of the program include the identification of the characteristics of the colon of each patient; finding the specific type of enema that will clean that colon and the radiological monitoring of the process

Index-based approach for estimating vulnerability of Arctic biota to oil spills

Risk of an Arctic oil spill has become a global matter of concern. Climate change induced opening of shipping routes increases the Arctic maritime traffic which exposes the area to negative impacts of potential maritime accidents. Still, quantitative analyses of the likely environmental impacts of such accidents are scarce, and our understanding of the uncertainties related to both accidents and their consequences is poor. There is an obvious need for analysis tools that allow us to systematically analyze the impacts of oil spills on Arctic species, so the risks can be taken into account when new sea routes or previously unexploited oil reserves are utilized. In this paper, an index‐based approach is developed to study exposure potential (described via probability of becoming exposed to spilled oil) and sensitivity (described via oil‐induced mortality and recovery) of Arctic biota in the face of an oil spill. First, a conceptual model presenting the relevant variables that contribute to exposure potential and sensitivity of key Arctic marine functional groups was built. Second, based on an extensive literature review, a probabilistic estimate was assigned for each variable, and the variables were combined to an index representing the overall vulnerability of Arctic biota. The resulting index can be used to compare the relative risk between functional groups and accident scenarios. Results indicate that birds have the highest vulnerability to spilled oil, and seals and whales the lowest. Polar bears’ vulnerability varies greatly between seasons, while ice seals’ vulnerability remains the same in every accident scenario. Exposure potential of most groups depends strongly on type of oil, whereas their sensitivity contains less variation.Peer reviewe

A Proposed Smart Market for Impervious Cover Runoff under Rainfall Uncertainty

Damage caused from stormwater runoff is becoming more frequent and occurring in places that were previously free of these problems. In order to reduce this problem, authorities have looked at different mechanisms for controlling and minimising the costs of floods. This paper proposes a smart market (SM) for runoff from impervious cover to reduce the mitigation and prevention costs for damages in the catchment. As rainfall events are uncertain, the SM must incorporate this stochasticity into the model formulation. Two stage stochastic programming (TSSP) with recourse is proposed to deal with uncertainty of rainfall events. The recourse actions or penalties would be priced according to the cost of damage or mitigation at different places in the catchment. The market would allow hedging against a range of rainfall events until an established maximum rainfall event, and above it, penalties for more extreme events. We expect the proposed SM would encourage users to internalize the expected costs of their runoff and cost of flooding. In addition, as the SM reduces transaction costs, there will be efficient allocation outcomes at minimum cost for society. The clearing prices and allocations would be based on auction bids, desirable environmental standards and the expected cost of flooding