415 research outputs found

    Fresh Marsh Network Modeling for Ecological Continuity

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    Genetic map construction and quantitative trait loci (QTL) mapping for nitrogen use efficiency and its relationship with productivity and quality of the biennial crop Belgian endive (Cichorium intybus L.)

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    A genetic study of the biennial crop Belgian endive (Cichorium intybus) was carried out to examine the effect of nitrogen nutrition during the vegetative phase in the control of the productivity and quality of the chicon (etiolated bud), a crop that grows during the second phase of development (forcing process). A population of 302 recombinant inbred lines (RIL) was obtained from the cross between contrasting lines "NS1" and "NR2". A genetic map was constructed and QTLs of several physiological and agronomical traits were mapped under two levels of nitrogen fertilization during the vegetative phase (N- and N+). The agronomical traits showed high broad sense heritability, whereas the physiological traits were characterized by low broad sense heritability. Nitrogen reserves mobilization during the forcing process was negatively correlated with nitrogen reserves content of the tuberized root and common QTLs were detected for these traits. The chicon productivity and quality were not correlated, but showed one common QTL. This study revealed that chicon productivity and quality were genetically associated with nitrogen reserves mobilization that exerts opposite effects on both traits. Chicon productivity was positively correlated with N reserves mobilization under N- and N+ and a common QTL with the same additive effects was detected for both traits. Chicon quality was negatively correlated with N reserves mobilization under N- and N+ and a common QTL with opposite additive effects was detected for both traits. These results lead to the conclusion that N reserves mobilization is a more effective trait than N reserves content in predicting chicon productivity and quality. Finally, this study revealed agronomical and physiological QTLs utilizable by breeders via marker-assisted selection to aid the optimization of chicon quality under adapted N fertilization

    Modeling of Tide Gate to Improve Fish Passability

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    Tidal gate are hydraulic structures that prevent salt water from entering in freshwater marshes. But they also block fish migration. For a side hinged gate, the migration can be facilitated by maintaining a little opening during all the tide. In this paper, the discharge coefficient of such a gate is evaluated based on numerical and experimental studies. It is found that the experimental discharge coefficients evolve with the difference between upstream and downstream water depths. Using shallow water simulations to estimate energy loss, we derived a model able to predict discharge with reasonable accuracy. An output of the model is the design of a stiffener device that limits salt water intrusion at high tide. Resolving the angular momentum, the optimal stiffener stiffness can be found to maintain opening sufficient for migration, while reducing greatly the volume of salt water intrusion in comparison with a constant block

    Study of Free Surface Flows in Rectangular Channel over Rough Beds

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    This paper presents the results of an experimental and numerical study of fully developed flow in a straight rectangular open channel over rough beds. Conical ribs were placed on the flume bottom to simulate different bed roughness conditions. Acoustic Doppler Velocimetry (ADV) measurements were made to obtain the velocity components profiles as well as the Reynolds stress profiles, at various locations. The experimental results are validated by simulations using an algebraic stress model. These investigations could be useful for researches in the field of sediment transport, bank protection, etc

    Flow over Flexible Vegetated Bed: Evaluation of Analytical Models

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    The development of vegetation in the river bed and in the banks can affect the hydrodynamic conditions and the flow behavior of a watercourse. This can increase the risk of flooding and sediment transport. Therefore, it is important to develop analytical approaches to predict the resistance caused by vegetation and model its effect on the flow. This is the objective of this work which investigates the ability of different analytical models to predict the vertical velocity profile as well as the resistance induced by flexible submerged vegetation in open channels. Then it is possible to select the appropriate model that will be applied in the real case of rivers. The model validation is determined after a comparison between the data measured in the different experiments carried out and those from literature. For dense vegetation, the role of the Reynolds number is emphasized in particular with a model using the Darcy-Brinkman equation in the canopy. With a simple permeability, this model is relevant to estimate friction. However, for larger Reynolds number, models based on the fully turbulent flow assumption provide better results

    Limb-darkening measurements for a cool red giant in microlensing event OGLE 2004-BLG-482

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    Aims: We present a detailed analysis of OGLE 2004-BLG-482, a relatively high-magnification single-lens microlensing event which exhibits clear extended-source effects. These events are relatively rare, but they potentially contain unique information on the stellar atmosphere properties of their source star, as shown in this study. Methods: Our dense photometric coverage of the overall light curve and a proper microlensing modelling allow us to derive measurements of the OGLE 2004-BLG-482 source star's linear limb-darkening coefficients in three bands, including standard Johnson-Cousins I and R, as well as in a broad clear filter. In particular, we discuss in detail the problems of multi-band and multi-site modelling on the expected precision of our results. We also obtained high-resolution UVES spectra as part of a ToO programme at ESO VLT from which we derive the source star's precise fundamental parameters. Results: From the high-resolution UVES spectra, we find that OGLE 2004-BLG-482's source star is a red giant of MK type a bit later than M3, with Teff = 3667 +/- 150 K, log g = 2.1 +/- 1.0 and an assumed solar metallicity. This is confirmed by an OGLE calibrated colour-magnitude diagram. We then obtain from a detailed microlensing modelling of the light curve linear limb-darkening coefficients that we compare to model-atmosphere predictions available in the literature, and find a very good agreement for the I and R bands. In addition, we perform a similar analysis using an alternative description of limb darkening based on a principal component analysis of ATLAS limb-darkening profiles, and also find a very good agreement between measurements and model predictions.Comment: Accepted in A&

    All-dielectric photonic metamaterials operating beyond the homogenization regime

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    Photonic metamaterials made of graded photonic crystals operating near the bandgap frequency region are proposed for field manipulation around l=1.5ÎŒm. Proof-of-concept structures have been studied using Hamiltonian optics and FDTD simulation, fabricated, and characterized using farfield optical measurements. Experimental results are in good agreement with predictions, showing the interest of graded photonic crystals as an (ultra-low loss) alternative solution to the use of metamaterials combining dielectric and metallic materials with sub-wavelength unit cells

    T cell responses induced by adenoviral vectored vaccines can be adjuvanted by fusion of antigen to the oligomerization domain of C4b-binding protein.

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    Viral vectored vaccines have been shown to induce both T cell and antibody responses in animals and humans. However, the induction of even higher level T cell responses may be crucial in achieving vaccine efficacy against difficult disease targets, especially in humans. Here we investigate the oligomerization domain of the α-chain of C4b-binding protein (C4 bp) as a candidate T cell "molecular adjuvant" when fused to malaria antigens expressed by human adenovirus serotype 5 (AdHu5) vectored vaccines in BALB/c mice. We demonstrate that i) C-terminal fusion of an oligomerization domain can enhance the quantity of antigen-specific CD4(+) and CD8(+) T cell responses induced in mice after only a single immunization of recombinant AdHu5, and that the T cells maintain similar functional cytokine profiles; ii) an adjuvant effect is observed for AdHu5 vectors expressing either the 42 kDa C-terminal domain of Plasmodium yoelii merozoite surface protein 1 (PyMSP1(42)) or the 83 kDa ectodomain of P. falciparum strain 3D7 apical membrane antigen 1 (PfAMA1), but not a candidate 128kDa P. falciparum MSP1 biallelic fusion antigen; iii) following two homologous immunizations of AdHu5 vaccines, antigen-specific T cell responses are further enhanced, however, in both BALB/c mice and New Zealand White rabbits no enhancement of functional antibody responses is observed; and iv) that the T cell adjuvant activity of C4 bp is not dependent on a functional Fc-receptor γ-chain in the host, but is associated with the oligomerization of small (<80 kDa) antigens expressed by recombinant AdHu5. The oligomerization domain of C4 bp can thus adjuvant T cell responses induced by AdHu5 vectors against selected antigens and its clinical utility as well as mechanism of action warrant further investigation

    OGLE-2008-BLG-510: first automated real-time detection of a weak microlensing anomaly - brown dwarf or stellar binary?

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    The microlensing event OGLE-2008-BLG-510 is characterised by an evident asymmetric shape of the peak, promptly detected by the ARTEMiS system in real time. The skewness of the light curve appears to be compatible both with binary-lens and binary-source models, including the possibility that the lens system consists of an M dwarf orbited by a brown dwarf. The detection of this microlensing anomaly and our analysis demonstrates that: 1) automated real-time detection of weak microlensing anomalies with immediate feedback is feasible, efficient, and sensitive, 2) rather common weak features intrinsically come with ambiguities that are not easily resolved from photometric light curves, 3) a modelling approach that finds all features of parameter space rather than just the `favourite model' is required, and 4) the data quality is most crucial, where systematics can be confused with real features, in particular small higher-order effects such as orbital motion signatures. It moreover becomes apparent that events with weak signatures are a silver mine for statistical studies, although not easy to exploit. Clues about the apparent paucity of both brown-dwarf companions and binary-source microlensing events might hide here.Comment: 17 pages with 8 figures, MNRAS submitte
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