The composition of sedimentary organic matter in relation to the dynamic features of the mangrove-fringed coast in French Guiana.

The sedimentary organic matter content of a series of 2-m-deep cores was examined in relation to the evolution of mangrove forest, on the basis of geochemical analyses and optical observations. Avicennia-dominated forest deposits, developing along the highly dynamic coastline of French Guiana, were collected in five stations based on stage of forest evolution. The sedimentary organic matter in the upper sediment of the youngest mangrove swamp is mainly derived from algal mats with low carbon:nitrogen ratios (C:N ratio, from 6 to 8) and typical greyish amorphous organic flakes as observed in optical studies. Indeed, rare young Avicennia trees are present, and effectively, geochemical parameters do not give evidence of a litter made up of higher plant debris, these rare debris being probably exported by the tides. A slight increase with depth in the first decimetres of both total organic carbon (TOC) content and C:N ratio results from the development of the radial cable root-system of the pioneer Avicennia germinans. Early diagenetic conditions of this young forest are rather controlled by dominant suboxic processes, as suggested by high Eh values (range, 200–400 mV) and local anoxic processes (occurrence of pyrite) in micro-environments: this is mainly due to the oxygen available by roots and crab bioturbation. The organic content of the senescent mangrove sediment is mainly derived from higher plant debris in the uppermost 30 cm, as indicated by relatively high C:N ratios and the predominance of ligno-cellulosic debris. The strong decrease in hydrogen index values results from the degradation of the higher plant debris, losing hydrogen bounds through decay processes. Moderately acidic pH values, low Ehs and the presence of pyrite framboids point towards the reducing decay processes in surficial layers of the senescent mangrove mediated by sulphate-reducing bacteria. Whatever the stage of evolution of the forest, the geochemical characteristics of the sediment below 30 cm are those of the shoreface one, with opaque refractory debris derived from the Amazon river detritus discharge. The sediment collected from dead mangrove forests, subsequently recolonized by pioneer mangroves, contains organic markers, which predate recolonization, recording previous phases of erosion and accretion

Organic composition and environmental conditions in mangrove sediments : a key for reconstructing the evolution of theFrench Guiana coast.

Le littoral guyanais présente une dynamique sédimentaire remarquable résultant du système dispersif amazonien. Une mangrove, essentiellement composée d'Avicennia germinans, se développe sur les bancs de vase. Ceux-ci migrent rapidement vers le NO et limitent la durée de vie de la mangrove. Les lambeaux de forêt résiduels ont pu être datés par analyse d'images Spot successives (Véga, 2000). Les mesures des paramètres physico-chimiques, les données Rock-Eval ainsi que des observations et comptages pétrographiques ont permis d'identifier deux systèmes de fonctionnement de la mangrove : les forêts jeunes (< 9ans), caractérisées par un export tidal important, et la forêt sénescente où l'exportation tidale est limitée. La composition organique du sédiment des mangroves jeunes provient principalement des mattes microbiennes et en quantité moindre du système racinaire de la mangrove. Les mécanismes de dégradation sont des processus suboxiques résultant de l'activité du système racinaire des Avicennia. La composition organique du sédiment de la forêt sénescente provient principalement de débris de végétaux supérieurs, les processus de dégradations sont de type anaérobie

Conference on Ferrimagnetism, 11-12 October, 1954

The eighteen papers which were presented at the conference on ferrimagnetism at the U. S. Naval Ordnance Laboratory, 11-12 October 1954, are summarized. Pertinent discussions are also included

Inhibition of Neuraminidase Inhibitor-Resistant Influenza Virus by DAS181, a Novel Sialidase Fusion Protein

Antiviral drug resistance for influenza therapies remains a concern due to the high prevalence of H1N1 2009 seasonal influenza isolates which display H274Y associated oseltamivir-resistance. Furthermore, the emergence of novel H1N1 raises the potential that additional reassortments can occur, resulting in drug resistant virus. Thus, additional antiviral approaches are urgently needed. DAS181 (Fludase®), a sialidase fusion protein, has been shown to have inhibitory activity against a large number of seasonal influenza strains and a highly pathogenic avian influenza (HPAI) strain (H5N1). Here, we examine the in vitro activity of DAS181 against a panel of 2009 oseltamivir-resistant seasonal H1N1 clinical isolates. The activity of DAS181 against nine 2009, two 2007, and two 2004 clinical isolates of seasonal IFV H1N1 was examined using plaque number reduction assay on MDCK cells. DAS181 strongly inhibited all tested isolates. EC50 values remained constant against isolates from 2004, 2007, and 2009, suggesting that there was no change in DAS181 sensitivity over time. As expected, all 2007 and 2009 isolates were resistant to oseltamivir, consistent with the identification of the H274Y mutation in the NA gene of all these isolates. Interestingly, several of the 2007 and 2009 isolates also exhibited reduced sensitivity to zanamivir, and accompanying HA mutations near the sialic acid binding site were observed. DAS181 inhibits IFV that is resistant to NAIs. Thus, DAS181 may offer an alternative therapeutic option for seasonal or pandemic IFVs that become resistant to currently available antiviral drugs

Selection and assembly of indigenous bacteria and methanogens from spent metalworking fluids and their potential as a starting culture in a fluidized bed reactor

Waste metalworking fluids (MWFs) are highly biocidal resulting in real difficulties in the, otherwise favoured, bioremediation of these high chemical oxygen deman (COD) wastes anaerobically in bioreactors. We have shown, as a proof of concept, that it is possible to establish an anaerobic starter culture using strains isolated from spent MWFs which are capable of reducing COD or, most significantly, methanogenesis in this biocidal waste stream. Bacterial strains (n=99) and archaeal methanogens (n=28) were isolated from spent MWFs. The most common bacterial strains were Clostridium species (n=45). All methanogens were identified as Methanosarcina mazei. Using a random partitions design(RPD) mesocosm experiment, we found that bacterial diversity and species–species interactions had significant effects on COD reduction but that bacterial composition did not. The RPD study showed similar effects on methanogenesis, except that composition was also significant. We identified bacterial species with positive and negative effects on methane production. A consortium of 16 bacterial species and three methanogens was used to initiate a fluidized bed bioreactor (FBR), in batch mode. COD reduction and methane production were variable, and the reactor was oscillated between continuous and batch feeds. In both microcosm and FBR experiments,periodic inconsistencies in bacterial reduction in fermentative products to formic and acetic acids were identified as a key issue

Patterns of Ecosystem Structure and Wildfire Carbon Combustion Across Six Ecoregions of the North American Boreal Forest

Increases in fire frequency, extent, and severity are expected to strongly impact the structure and function of boreal forest ecosystems. An important function of the boreal forest is its ability to sequester and store carbon (C). Increasing disturbance from wildfires, emitting large amounts of C to the atmosphere, may create a positive feedback to climate warming. Variation in ecosystem structure and function throughout the boreal forest is important for predicting the effects of climate warming and changing fire regimes on C dynamics. In this study, we compiled data on soil characteristics, stand structure, pre-fire C pools, C loss from fire, and the potential drivers of these C metrics from 527 sites distributed across six ecoregions of North America’s western boreal forests. We assessed structural and functional differences between these fire-prone ecoregions using data from 417 recently burned sites (2004–2015) and estimated ecoregion-specific relationships between soil characteristics and depth from 167 of these sites plus an additional 110 sites (27 burned, 83 unburned). We found that northern boreal ecoregions were generally older, stored and emitted proportionally more belowground than aboveground C, and exhibited lower rates of C accumulation over time than southern ecoregions. We present ecoregion-specific estimates of depth-wise soil characteristics that are important for predicting C combustion from fire. As climate continues to warm and disturbance from wildfires increases, the C dynamics of these fire-prone ecoregions are likely to change with significant implications for the global C cycle and its feedbacks to climate change

4D perfusion CT of prostate cancer for image-guided radiotherapy planning: A proof of concept study.

PURPOSE: Advanced forms of prostate cancer (PCa) radiotherapy with either external beam therapy or brachytherapy delivery techniques aim for a focal boost and thus require accurate lesion localization and lesion segmentation for subsequent treatment planning. This study prospectively evaluated dynamic contrast-enhanced computed tomography (DCE-CT) for the detection of prostate cancer lesions in the peripheral zone (PZ) using qualitative and quantitative image analysis compared to multiparametric magnet resonance imaging (mpMRI) of the prostate. METHODS: With local ethics committee approval, 14 patients (mean age, 67 years; range, 57-78 years; PSA, mean 8.1 ng/ml; range, 3.5-26.0) underwent DCE-CT, as well as mpMRI of the prostate, including standard T2, diffusion-weighted imaging (DWI), and DCE-MRI sequences followed by transrectal in-bore MRI-guided prostate biopsy. Maximum intensity projections (MIP) and DCE-CT perfusion parameters (CTP) were compared between healthy and malignant tissue. Two radiologists independently rated image quality and the tumor lesion delineation quality of PCa using a five-point ordinal scale. MIP and CTP were compared using visual grading characteristics (VGC) and receiver operating characteristics (ROC)/area under the curve (AUC) analysis. RESULTS: The PCa detection rate ranged between 57 to 79% for the two readers for DCE-CT and was 92% for DCE-MRI. DCE-CT perfusion parameters in PCa tissue in the PZ were significantly different compared to regular prostate tissue and benign lesions. Image quality and lesion visibility were comparable between DCE-CT and DCE-MRI (VGC: AUC 0.612 and 0.651, p>0.05). CONCLUSION: Our preliminary results suggest that it is feasible to use DCE-CT for identification and visualization, and subsequent segmentation for focal radiotherapy approaches to PCa

Crossing borders to bind proteins—a new concept in protein recognition based on the conjugation of small organic molecules or short peptides to polypeptides from a designed set

A new concept for protein recognition and binding is highlighted. The conjugation of small organic molecules or short peptides to polypeptides from a designed set provides binder molecules that bind proteins with high affinities, and with selectivities that are equal to those of antibodies. The small organic molecules or peptides need to bind the protein targets but only with modest affinities and selectivities, because conjugation to the polypeptides results in molecules with dramatically improved binder performance. The polypeptides are selected from a set of only sixteen sequences designed to bind, in principle, any protein. The small number of polypeptides used to prepare high-affinity binders contrasts sharply with the huge libraries used in binder technologies based on selection or immunization. Also, unlike antibodies and engineered proteins, the polypeptides have unordered three-dimensional structures and adapt to the proteins to which they bind. Binder molecules for the C-reactive protein, human carbonic anhydrase II, acetylcholine esterase, thymidine kinase 1, phosphorylated proteins, the D-dimer, and a number of antibodies are used as examples to demonstrate that affinities are achieved that are higher than those of the small molecules or peptides by as much as four orders of magnitude. Evaluation by pull-down experiments and ELISA-based tests in human serum show selectivities to be equal to those of antibodies. Small organic molecules and peptides are readily available from pools of endogenous ligands, enzyme substrates, inhibitors or products, from screened small molecule libraries, from phage display, and from mRNA display. The technology is an alternative to established binder concepts for applications in drug development, diagnostics, medical imaging, and protein separation