Longpath DOAS tomography on a motorway exhaust gas plume: numerical studies and application to data from the BAB II campaign

International audienceThis paper presents a procedure for performing and optimizing inversions for DOAS tomography and its application to measurement data. DOAS tomography is a new technique to determine 2- and 3-dimensional concentration fields of air pollutants or other trace gases by combining differential optical absorption spectroscopy (DOAS) with tomographic inversion techniques. Due to the limited amount of measured data, the resulting concentration fields are sensitive to the inversion process. Therefore detailed error estimations are needed to determine the quality of the reconstruction. In this paper we compare different row acting methods for the inversion, present a procedure for optimizing the parameters of the reconstruction process and propose a way to estimate the error-fields by numerical studies. The procedure was applied to data from the motorway emission campaign BAB II. Two dimensional NO2 cross sections at right angles to the motorway could be reconstructed qualitatively well at different meteorological situations. Additionally we present error fields for the reconstructions which show the problems and skills of the used measurement setup. Numerical studies on an improved setup for future motorway campaigns show, that DOAS tomography is able to produce high quality concentration maps

Biogeochemistry of Norwegian cold-water coral reef sediments

Cold-water coral ecosystems may constitute a geologically significant fraction (>1%) of global carbonate production (Lindberg and Mienert, 2005). Thriving cold-water coral reefs are also considered to be hot-spots of diversity and biomass production. Nevertheless, the impacts of these ecosystems on the adjacent sediment and associated geochemical processes including carbonate preservation are poorly understood.Here we present the first data quantifying the biogeochemical processes in modern (post-glacial) cold-water coral reef sediments. This work integrates organoclastic sulfate reduction rates, multi-element pore-water profiles and solid-phase analyses of gravity cores (8 sites at two reefs) retrieved during R/V Polarstern expedition ARKXXII/1a to the mid-Norwegian cold-water coral reefs in June 2007.The reef sediments are comprised of coral fragments embedded in loose silt or clay and biogenic debris (of 0,5 to 3,2 m thickness). The base of the coral-bearing reef sediments consists of highly compacted glacial clays. High carbonate contents (up to 75 %) and low organic carbon contents (~0,5 %) characterize the reef sediments. Porewater Ca2+, Mg2+ and Sr2+ profiles indicate that on-going carbonate precipitation dominates any carbonate dissolution. Overall microbial activity in these sediments is low; measured sulfate reduction rates are less than 1 nmol S cm-3 d-1. Pore-water analyses reveal elevated Fe2+ and Mn2+ concentrations suggesting that Fe and Mn reduction occurs. This may be the result of sulfide reacting with the available reactive iron pool to form Fe-sulfides indicated by the absence of sulfide in the pore water. Fe and Mn reduction may also be attributed to dissimilatory microbial metal reduction. Iron reduction linked to microbial sulfate reduction may enhance diagenetic carbonate precipitation and coral preservation in these sediments as suggested for the older coldwater coral mound systems drilled in IODP Expedition 307 (Ferdelman et al., 2006). Extremely low methane concentrations (<0,5 µM) were found at all depths and sites along the Norwegian margin. This argues against a linkage between coral reef distribution and the appearance of hydrocarbon seepage as formulated by Hovland et al. (1998)

Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf

Cold-water coral ecosystems are considered hot-spots of biodiversity and biomass production and may be a regionally important contributor to carbonate production. The impact of these ecosystems on biogeochemical processes and carbonate preservation in associated sediments were studied at Røst Reef and Traenadjupet Reef, two modern (post-glacial) cold-water coral reefs on the Mid-Norwegian shelf. Sulfate and iron reduction as well as carbonate dissolution and precipitation were investigated by combining pore-water geochemical profiles, steady state modeling, as well as solid phase analyses and sulfate reduction rate measurements on gravity cores of up to 3.25 m length. Low extents of sulfate depletion and dissolved inorganic carbon (DIC) production, combined with sulfate reduction rates not exceeding 3 nmol S cm−3 d−1, suggested that overall anaerobic carbon mineralization in the sediments was low. These data showed that the coral fragment-bearing siliciclastic sediments were effectively decoupled from the productive pelagic ecosystem by the complex reef surface framework. Organic matter being mineralized by sulfate reduction was calculated to consist of 57% carbon bound in CH2O groups and 43% carbon in -CH2- groups. Methane concentrations were below 1 μM, and failed to support the hypothesis of a linkage between the distribution of cold-water coral reefs and the presence of hydrocarbon seepage. Reductive iron oxide dissolution linked to microbial sulfate reduction buffered the pore-water carbonate system and inhibited acid-driven coral skeleton dissolution. A large pool of reactive iron was available leading to the formation of iron sulfide minerals. Constant pore-water Ca2+, Mg2+ and Sr2+ concentrations in most cores and decreasing Ca2+ and Sr2+ concentrations with depth in core 23–18 GC indicated diagenetic carbonate precipitation. This was consistent with the excellent preservation of buried coral fragments

A design thinking approach to evaluating interprofessional education

The complex challenge of evaluating the impact of interprofessional education (IPE) on patient and community health outcomes is well documented. Recently, at the Radcliffe Institute for Advanced Study in the United States, leaders in health professions education met to help generate a direction for future IPE evaluation research. Participants followed the stages of design thinking, a process for human-centred problem solving, to reach consensus on recommendations. The group concluded that future studies should focus on measuring an intermediate step between learning activities and patient outcomes. Specifically, knowing how IPE-prepared students and preceptors influence the organisational culture of a clinical site as well as how the culture of clinical sites influences learners' attitudes about collaborative practice will demonstrate the value of educational interventions. With a mixed methods approach and an appreciation for context, researchers will be able to identify the factors that foster effective collaborative practice and, by extension, promote patient-centred care

Modeling terahertz heating effects on water

We apply Kirchhoff's heat equation to model the influence of a CW terahertz beam on a sample of water, which is assumed to be static. We develop a generalized model, which easily can be applied to other liquids and solids by changing the material constants. If the terahertz light source is focused down to a spot with a diameter of 0.5 mm, we find that the steady-state temperature increase per milliwatt of transmitted power is 1.8?C/mW. A quantum cascade laser can produce a CW beam in the order of several milliwatts and this motivates the need to estimate the effect of beam power on the sample temperature. For THz time domain systems, we indicate how to use our model as a worst-case approximation based on the beam average power. It turns out that THz pulses created from photoconductive antennas give a negligible increase in temperature. As biotissue contains a high water content, this leads to a discussion of worst-case predictions for THz heating of the human body in order to motivate future detailed study. An open source Matlab implementation of our model is freely available for use at www.eleceng.adelaide.edu.au/thz.Torben T. L. Kristensen, Withawat Withayachumnankul, Peter U. Jepsen and Derek Abbot

Reciprocal learning and chronic care model implementation in primary care: results from a new scale of learning in primary care

<p>Abstract</p> <p>Background</p> <p>Efforts to improve the care of patients with chronic disease in primary care settings have been mixed. Application of a complex adaptive systems framework suggests that this may be because implementation efforts often focus on education or decision support of individual providers, and not on the dynamic system as a whole. We believe that learning among clinic group members is a particularly important attribute of a primary care clinic that has not yet been well-studied in the health care literature, but may be related to the ability of primary care practices to improve the care they deliver.</p> <p>To better understand learning in primary care settings by developing a scale of learning in primary care clinics based on the literature related to learning across disciplines, and to examine the association between scale responses and chronic care model implementation as measured by the Assessment of Chronic Illness Care (ACIC) scale.</p> <p>Methods</p> <p>Development of a scale of learning in primary care setting and administration of the learning and ACIC scales to primary care clinic members as part of the baseline assessment in the ABC Intervention Study. All clinic clinicians and staff in forty small primary care clinics in South Texas participated in the survey.</p> <p>Results</p> <p>We developed a twenty-two item learning scale, and identified a five-item subscale measuring the construct of reciprocal learning (Cronbach alpha 0.79). Reciprocal learning was significantly associated with ACIC total and sub-scale scores, even after adjustment for clustering effects.</p> <p>Conclusions</p> <p>Reciprocal learning appears to be an important attribute of learning in primary care clinics, and its presence relates to the degree of chronic care model implementation. Interventions to improve reciprocal learning among clinic members may lead to improved care of patients with chronic disease and may be relevant to improving overall clinic performance.</p

Microsporidia::Why Make Nucleotides if You Can Steal Them?

Microsporidia are strict obligate intracellular parasites that infect a wide range of eukaryotes including humans and economically important fish and insects. Surviving and flourishing inside another eukaryotic cell is a very specialised lifestyle that requires evolutionary innovation. Genome sequence analyses show that microsporidia have lost most of the genes needed for making primary metabolites, such as amino acids and nucleotides, and also that they have only a limited capacity for making adenosine triphosphate (ATP). Since microsporidia cannot grow and replicate without the enormous amounts of energy and nucleotide building blocks needed for protein, DNA, and RNA biosynthesis, they must have evolved ways of stealing these substrates from the infected host cell. Providing they can do this, genome analyses suggest that microsporidia have the enzyme repertoire needed to use and regenerate the imported nucleotides efficiently. Recent functional studies suggest that a critical innovation for adapting to intracellular life was the acquisition by lateral gene transfer of nucleotide transport (NTT) proteins that are now present in multiple copies in all microsporidian genomes. These proteins are expressed on the parasite surface and allow microsporidia to steal ATP and other purine nucleotides for energy and biosynthesis from their host. However, it remains unclear how other essential metabolites, such as pyrimidine nucleotides, are acquired. Transcriptomic and experimental studies suggest that microsporidia might manipulate host cell metabolism and cell biological processes to promote nucleotide synthesis and to maximise the potential for ATP and nucleotide import. In this review, we summarise recent genomic and functional data relating to how microsporidia exploit their hosts for energy and building blocks needed for growth and nucleic acid metabolism and we identify some remaining outstanding questions