To respond or not to respond - a personal perspective of intestinal tolerance

For many years, the intestine was one of the poor relations of the immunology world, being a realm inhabited mostly by specialists and those interested in unusual phenomena. However, this has changed dramatically in recent years with the realization of how important the microbiota is in shaping immune function throughout the body, and almost every major immunology institution now includes the intestine as an area of interest. One of the most important aspects of the intestinal immune system is how it discriminates carefully between harmless and harmful antigens, in particular, its ability to generate active tolerance to materials such as commensal bacteria and food proteins. This phenomenon has been recognized for more than 100 years, and it is essential for preventing inflammatory disease in the intestine, but its basis remains enigmatic. Here, I discuss the progress that has been made in understanding oral tolerance during my 40 years in the field and highlight the topics that will be the focus of future research

Maritime Aerosol Network as a component of Aerosol Robotic Network

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): D06204, doi:10.1029/2008JD011257.The paper presents the current status of the Maritime Aerosol Network (MAN), which has been developed as a component of the Aerosol Robotic Network (AERONET). MAN deploys Microtops handheld Sun photometers and utilizes the calibration procedure and data processing (Version 2) traceable to AERONET. A web site dedicated to the MAN activity is described. A brief historical perspective is given to aerosol optical depth (AOD) measurements over the oceans. A short summary of the existing data, collected on board ships of opportunity during the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project is presented. Globally averaged oceanic aerosol optical depth (derived from island-based AERONET measurements) at 500 nm is ∼0.11 and Angstrom parameter (computed within spectral range 440–870 nm) is calculated to be ∼0.6. First results from the cruises contributing to the Maritime Aerosol Network are shown. MAN ship-based aerosol optical depth compares well to simultaneous island and near-coastal AERONET site AOD.The work of Tymon Zielinski was supported by Polish national grant AERONET59

Data-Driven Reconstruction of Sea Surface Turbidity Dynamics with 4dVarNet Neural Scheme Applied To Gappy Satellite Images

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Geometry, fractal dimension and settling velocity of flocs during flooding conditions in the Rhône ROFI

Regions Of Freshwater Influence (ROFI) are of particular interest in a source-to-sink approach in terms of sediment advection, settling, and deposition in the coastal zone. An experiment was carried out in the ROFI of the Rhône River in February 2016 to describe the properties of suspended particulate matter (SPM) during a flood event. A digital holographic camera (LISST-HOLO, 20–2000 μm) was used to estimate the variability of fine sediment floc properties (size, nature and shape) formed in the Rhône mouth. An automatic image toolbox was developed to classify the different constituents of the SPM (as diatoms, bubbles and flocs) and to describe the diversity of floc shapes existing in the material in suspension. We estimated the fractal dimension (DF3D), the aspect ratio (AR) and the settling velocity of flocs (Ws). The estimated DF3D ranged between 2.0 and 2.5 highlights the complexity of floc shape, which was used as a proxy of the flocculation mechanism functioning in the Rhône mouth. Additionally, we performed a sensitivity analysis on the estimate of Ws using different shape-related coefficients (α/β) and primary particle size (dP). The results highlighted the impact of the flocculation of fine sediments on the increase of Ws from 0.01 to 3 mm s−1 when floc sizes increase from 30 to 500 μm. Ws showed a decrease of 41% considering the sphericity of flocs that emphasized the need to consider the floc shape to properly estimate their settling velocity. We showed that an increase of dP from 1 to 12 μm induces a fivefold increase of Ws that showed the need for an adequate system to properly estimate the size of primary particles. These results emphasized the need to take into account such variability in future model of floc dynamics in ROFI to properly estimate plume sinking rate and SPM dynamics

Cross-shelf variability in the Iberian Peninsula Upwelling System : impact of a mesoscale filament

Based on a multidisciplinary survey in the Iberian upwelling during late summer 2007, this paper analysed comparatively the cross-shore variability and offshore transport across the upwelling front and within a mesoscale filament. Along the East-West (EW) sections, transient upwelling pulses bring regularly cold, fresh and nutrient-enriched waters to the surface, triggering intense biological responses. Offshore advection by wind-forced Ekman drift of the successive fronts, interrupted by relaxation periods, drive the variability of the planktonic communities. While the near-shore areas are dominated by relatively small phytoplankton controlled by mesozooplankton grazing, large cells of diatoms appear after a short decay. Although microphytoplankton dominates largely the shelf communities, the species composition varies during the offshore drift with the apparition of dinoflagellates and the gradual development of large zooplankton individuals. The oligotrophic ecosystem characterised by small organisms and low biomass (similar to 80 km offshore) contrasts strongly with the transitional area and the coastal upwelling. The low density waters within the filament and the existence of a pair of opposite rotating eddies at its base and tip promote its generation and rapid seaward extension. The intensified offshore advection of coastal enriched waters considerably increases the area favouring a productive ecosystem (until similar to 160 km off the coast). Cross-shelf variability of bio-physical variables is observed in the filament as along EW sections, although a subsequent homogenisation within the mesoscale structure erases the sharp fronts. Off the shelf within the filament, the chlorophyll a is distinctly organised as a shallow subsurface maximum dominated by nano-phytoplankton. The relative physical isolation of a dynamical food-web in the filament is also promoting nutrient remineralisation under the structure. Finally, we estimate that mesoscale filaments, although being less extended meridionally than the upwelling front itself (similar to 40% of the length of the front) are responsible for a greater offshore transport of chlorophyll (similar to 60% of total cross-shelf exchanges) over the Iberian system. Despite the favourable wind pulses advecting westward the successive upwelling fronts, self-propelled filaments provide permanent offshore transport, even under wind relaxation period, thus playing a major role in cross-shelf exchanges

Tropical Cyclone-Driven Sediment Dynamics Over the Australian North West Shelf

Owing to their strong forcing at the air-sea interface, tropical cyclones are a major driver of hydrodynamics and sediment dynamics of continental shelves, strongly impacting marine habitats and offshore industries. Despite the North West Shelf of Australia being one of the most frequently impacted tropical cyclone regions worldwide, there is limited knowledge of how tropical cyclones influence the sediment dynamics of this shelf region, including the significance of these episodic extreme events to the normal background conditions that occur. Using an extensive 2 year data set of the in situ sediment dynamics and 14 yearlong calibrated satellite ocean-color data set, we demonstrate that alongshore propagating cyclones are responsible for simultaneously generating both strong wave-induced sediment resuspension events and significant southwestward subtidal currents. Over the 2 year study period, two particular cyclones (Iggy and Narelle) dominated the sediment fluxes resulting in a residual southwestward sediment transport over the southern part of the shelf. By analyzing results from a long-term (37 year) wind and wave hindcast, our results suggest that at least 16 tropical cyclones had a strong potential to contribute to that southwestward sediment pathway in a similar way to Iggy and Narelle

DEXMES: A novel cylindrical device for SPM experiments

International audienc

DEXMES: A novel cylindrical device for SPM experiments

International audienc