Characterization of dust emission from alluvial sources using aircraft observations and high-resolution modeling

International audienceWe investigate mineral dust emission from alluvial sediments within the upland region in northern Mauritania in the vicinity of a decaying nocturnal low-level jet (LLJ). For the first time, the impact of valleys that are embedded in a rather homogeneous surrounding is investigated with regard to their role as dust source. Measures for local atmospheric dust burden were retrieved from airborne observations, satellite observations, and model simulations and analyzed in order to provide complementary information at different horizontal scales. Observations by the LEANDRE Nouvelle Generation backscatter lidar system flying aboard the French Falcon 20 aircraft were taken along five parallel flight legs perpendicular to the orientation of the main valley system dominating the topography of the study area. Results from a comparison of lidar-derived extinction coefficients with topography and aerial photographs confirm the relevance of (1) alluvial sediments at the valley bottoms as a dust source, and (2) the break-down of the nocturnal LLJ as a trigger for dust emission in this region. An evaluation of the AROME regional model, forecasting dust at high resolution (5 km grid), points toward an under-representation of alluvial dust sources in this region. This is also evident from simulations by the MesoNH research model. Although MesoNH simulations show higher dust loadings than AROME, which are more comparable to the observations, both models underestimate the dust concentrations within the boundary layer compared to lidar observations. A sensitivity study on the impact of horizontal grid spacing (5 km versus 1 km) highlights the importance of spatial resolution on simulated dust loadings

Quantum optical time-of-arrival model in three dimensions

We investigate the three-dimensional formulation of a recently proposed operational arrival-time model. It is shown that within typical conditions for optical transitions the results of the simple one-dimensional version are generally valid. Differences that may occur are consequences of Doppler and momentum-transfer effects. Ways to minimize these are discussed.Comment: 14 pages, 5 figure

A rare combination of an endocrine tumour of the common bile duct and a follicular lymphoma of the ampulla of Vater: a case report and review of the literature

Carcinoid tumours of the common bile duct represent an extremely rare entity. Similarly, primary follicular lymphomas of the ampulla of Vater constitute an infrequent neoplasia. Herein, we report the first case of a synchronous development of a carcinoid tumour of the common bile duct and an ampullary follicular lymphoma that was treated surgically with a Whipple's procedure, due to inability to establish definitive preoperative diagnosis despite the extensive diagnostic investigation

Advances in understanding mineral dust and boundary layer processes over the Sahara from Fennec aircraft observations

International audienceThe Fennec climate program aims to improve understanding of the Saharan climate system through a synergy of observations and modelling. We present a description of the Fennec airborne observations during 2011 and 2012 over the remote Sahara (Mauritania and Mali) and the advances in the understanding of mineral dust and boundary layer processes they have provided. Aircraft instrumentation aboard the UK FAAM BAe146 and French SAFIRE Falcon 20 is described, with specific focus on instrumentation specially developed and relevant to Saharan meteorology and dust. Flight locations, aims and associated meteorology are described. Examples and applications of aircraft measurements from the Fennec flights are presented, highlighting new scientific results delivered using a synergy of different instruments and aircraft. These include: (1) the first airborne measurement of dust particles sized up to 300 microns and associated dust fluxes in the Saharan atmospheric boundary layer (SABL), (2) dust uplift from the breakdown of the nocturnal low-level jet before becoming visible in SEVIRI satellite imagery, (3) vertical profiles of the unique vertical structure of turbulent fluxes in the SABL, (4) in-situ observations of processes in SABL clouds showing dust acting as CCN and IN at −15 °C, (5) dual-aircraft observations of the SABL dynamics, thermodynamics and composition in the Saharan heat low region (SHL), (6) airborne observations of a dust storm associated with a cold-pool (haboob) issued from deep convection over the Atlas, (7) the first airborne chemical composition measurements of dust in the SHL region with differing composition, sources (determined using Lagrangian backward trajectory calculations) and absorption properties between 2011 and 2012, (8) coincident ozone and dust surface area measurements suggest coarser particles provide a route for ozone depletion, (9) discrepancies between airborne coarse mode size distributions and AERONET sunphotometer retrievals under light dust loadings. These results provide insights into boundary layer and dust processes in the SHL region – a region of substantial global climatic importance

Contribution of Microbe-Mediated Processes in Nitrogen Cycle to Attain Environmental Equilibrium

Nitrogen (N), the most important element, is required by all living organisms for the synthesis of complex organic molecules like amino acids, proteins, lipids etc. Nitrogen cycle is considered to be the most complex yet arguably important cycle next to carbon cycle. Nitrogen cycle includes oxic and anoxic reactions like organic N mineralization, ammonia assimilation, nitrification denitrification, anaerobic ammonium oxidation (anammox), dissimilatory nitrate reduction to ammonium (DNRA), comammox, codenitrification etc. Nitrogen cycling is one of the most crucial processes required for the recycling of essential chemical requirements on the planet. Soil microorganisms not only improve N-cycle balance but also pave the way for sustainable agricultural practices, leading to improved soil properties and crop productivity as most plants are opportunistic in the uptake of soluble or available forms of N from soil. Microbial N transformations are influenced by plants to improve their nutrition and vice versa. Diverse microorganisms, versatile metabolic activities, and varied biotic and abiotic conditions may result in the shift in the equilibrium state of different N-cycling processes. This chapter is an overview of the mechanisms and genes involved in the diverse microorganisms associated in the operation of nitrogen cycle and the roles of such microorganisms in different agroecosystems

Superior Vena Cava Obstruction in Small-cell Lung Cancer

PURPOSE: To identify prognostic or treatment factors influencing the response of superior vena cava obstruction (SVCO), time to SVCO recurrence, and overall survival of SCLC patients with SVCO at presentation; and to assess the role of retreatment in patients with SVCO at recurrent or persistent disease. METHODS AND MATERIALS: Between January 1983 and November 1993, 76 consecutive patients who had small-cell lung cancer (SCLC) with SVCO were treated in our institution. Analysis was done according to the disease status at diagnosis of SVCO. The first analysis concerned a group of 50 patients who had SVCO at initial presentation. The second analysis concerned a group who had SVCO as a manifestation of persistent or recurrent disease. RESULTS: In the first analysis, 93% had significant improvement in symptoms of SVCO after chemotherapy and 94% after mediastinal radiation. Response is almost universal despite a wide range of radiation fractionation and total dose used. Seventy percent remained SVCO-free before death. Thirty percent developed recurrence of SVCO symptoms 1-16 months (median 8) after the start of initial treatment. Those who received combined chemotherapy and radiation had a longer time to SVCO recurrence (p = 0.018) compared to those who received chemotherapy alone. This effect is mainly seen in limited-stage patients. The presence of SVCO recurrence tends to have an adverse effect on the overall survival (p = 0.077) irrespective of the time when the recurrences occurred (p = 0.296). The median survival of this whole group of 50 patients in the first analysis was 9.5 months, and the 2-year survival was 10%. Stage was strongly predictive of survival (p \u3c 0.001). Sixteen percent (3 of 19) of the patients with limited-stage diseases were long-term survivors (two patients survived 35 months and one survived 70 months). The early mortality from SVCO was 2%. In the second analysis, 85% had previously been treated with chemotherapy alone. The response rate of SVCO in the analysable patients (n = 39) was 77%. There was no significant difference in the response rate of SVCO to treatment comparing patients treated by chemotherapy first or mediastinal radiation first (p = 0.653), but most patients [82% (32 of 39)] received radiation as the initially treatment of SVCO. Ninety-three percent (38 of 41) received mediastinal radiation as a part of their ultimate retreatment regimen, and 68% (28 of 41) received mediastinal radiation as their sole retreatment regimen. Thirty-two percent (13 of 41) received chemotherapy as a part of their ultimate retreatment regimen, and only 7% received chemotherapy alone as their sole retreatment regimen. Eighty-three percent (25 of 30) of those whose SVCO responded remained free of SVCO before death, with a median survival of 3 months after recurrent or persistent disease documented. CONCLUSION: Chemotherapy or mediastinal radiation is very effective as an initial treatment in SCLC patients with SVCO at presentation and at recurrent or persistent disease. There is no obvious need to use big radiation fraction sizes for the first few radiation treatment as was previously believed. In patients with recurrent or persistent SCLC with SVCO, especially in those who previously received chemotherapy only, we have more experience in incorporating mediastinal radiation as a major component of the palliative regimen with highly effective and durable palliation achieved