Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico

Seasonal hypoxia of the northern Gulf of Mexico has been observed for more than 25 years. It is generally accepted that the variation in the areal extent of hypoxia is determined by changes in nutrient addition from the Mississippi River. In this study, we investigate the statistical relation between the hypoxic area and a new variable, the duration of west wind, using the available measurements for the period 1985-2010. Special consideration was paid to the 1993-2010 period, a time when a large shift in the seasonal hypoxia pattern has been reported. When excluding the years in which hurricanes directly impacted the hypoxic area observation, we find that the duration of west wind is correlated with the hypoxic area at r(2) = 0.32 for the 1985-2010 period, and r(2) = 0.52 for the 1993-2010 period. Multilinear regressions using both wind duration and May-June nitrate loading improve the statistical relationships for both periods to r(2) = 0.69 and 0.74 for the long and short time periods, respectively. Mechanistically, the statistical relationships reflect the movement and changes in horizontal river plume position associated with the wind and the influence of stratification on the hypoxic area. Citation: Feng, Y., S. F. DiMarco, and G. A. Jackson (2012), Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico, Geophys. Res. Lett., 39, L09601, doi:10.1029/2012GL051192

Formation of artificial granules for proving gelation as the main mechanism of aerobic granulation in biological wastewater treatment

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Trimaximal neutrino mixing from vacuum alignment in A4 and S4 models

Recent T2K results indicate a sizeable reactor angle theta_13 which would rule out exact tri-bimaximal lepton mixing. We study the vacuum alignment of the Altarelli-Feruglio A4 family symmetry model including additional flavons in the 1' and 1" representations and show that it leads to trimaximal mixing in which the second column of the lepton mixing matrix consists of the column vector (1,1,1)^T/sqrt{3}, with a potentially large reactor angle. In order to limit the reactor angle and control the higher order corrections, we propose a renormalisable S4 model in which the 1' and 1" flavons of A4 are unified into a doublet of S4 which is spontaneously broken to A4 by a flavon which enters the neutrino sector at higher order. We study the vacuum alignment in the S4 model and show that it predicts accurate trimaximal mixing with approximate tri-bimaximal mixing, leading to a new mixing sum rule testable in future neutrino experiments. Both A4 and S4 models preserve form dominance and hence predict zero leptogenesis, up to renormalisation group corrections.Comment: 24 pages, 2 figures, version to be published in JHE

Ontogeny of 2-[ 125I]iodomelatonin binding sites in the chicken (Gallus domesticus) kidney and spleen

To understand the possible role of melatonin receptors in the development of renal and immune functions, age-related variations of 2-[ 125I]iodomelatonin binding sites in the chicken kidney and spleen were investigated by radioreceptor assay. Chickens at embryonic day 20, as well as 2 days, 9 days, 2 weeks, 6 weeks, 12 weeks, and 16 weeks after hatching, were kept under a 12 h light : 12 h dark photoperiod and killed at the middle of the light period. Binding sites for 2-[ 125I]iodomelatonin in membrane preparations of the chicken kidney and spleen were present on embryonic day 20. The maximum binding densities (B(max)) in the kidney increased to a peak between 9 days and 2 weeks of age, then progressively decreased. B(max) values of 2-[ 125I]iodomelatonin binding sites in the chicken spleen were lower than in the kidney. The peak density in the chicken spleen was recorded at day 2 after hatching and decreased significantly after 6 weeks of age. There were no significant differences in binding affinities (K(d)) in kidney and spleen of chicken in the different age groups studied. The unity of Hill coefficients of 2-[ 125I]iodomelatonin binding sites of the chicken kidney and spleen in all age groups tested suggested that only a single class of binding sites was present in these tissues during development. It is proposed that the developmental changes in 2-[ 125I]iodomelatonin binding sites in the chicken kidney and spleen may be pertinent to the development of diurnal rhythms of kidney functions and the post-pubertal decline in immune functions of the chicken.published_or_final_versio

Accelerating exhaustive pairwise metagenomic comparisons

In this manuscript, we present an optimized and parallel version of our previous work IMSAME, an exhaustive gapped aligner for the pairwise and accurate comparison of metagenomes. Parallelization strategies are applied to take advantage of modern multiprocessor architectures. In addition, sequential optimizations in CPU time and memory consumption are provided. These algorithmic and computational enhancements enable IMSAME to calculate near optimal alignments which are used to directly assess similarity between metagenomes without requiring reference databases. We show that the overall efficiency of the parallel implementation is superior to 80% while retaining scalability as the number of parallel cores used increases. Moreover, we also show thats equential optimizations yield up to 8x speedup for scenarios with larger data.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Surface Morphology Evolution of GaAs by Low Energy Ion Sputtering

Low energy Ar+ion sputtering, typically below 1,200 eV, of GaAs at normal beam incident angle is investigated. Surface morphology development with respect to varying energy is analyzed and discussed. Dot-like patterns in the nanometer scale are obtained above 600 eV. As the energy approaches upper eV range regular dots have evolved. The energy dependent dot evolution is evaluated based on solutions of the isotropic Kuramoto-Sivashinsky equation. The results are in agreement with the theoretical model which describes a power law dependency of the characteristic wavelength on ion energy in the ion-induced diffusion regime

Structural analysis of small-scale 3D printed composite tidal turbine blades

\ua9 2024 The AuthorsThe existing research literature lacks comprehensive investigations into assessing the structural performance of marine renewable energy conversion devices, particularly 3D printed turbine blades, which often rely solely on computational modelling without experimental validation methods and/or established mechanical characterization techniques. This leads to significant uncertainty regarding the performance of 3D printed turbine blades manufactured by additive manufacturing technology. This study aims to fill this gap by proposing a procedure for evaluating the structural integrity of commercial small-scale tidal turbine blade (5 KW) manufactured using fused filament fabrication 3D printing with a linear infill pattern. This is achieved by developing a combined experimental, hydrodynamic, and finite element approach with the view to inspect the micro-mechanical properties of representative volume elements of 3D printed microstructures using homogenization technique. The results of mechanical testing and hydrodynamic modelling are used to create a finite element model of the 3D printed blade, allowing for stress and failure analysis. Findings indicate that while integrating 3D printed materials into blade design via 3D printing technology is feasible, the choice of materials is limited to high stiffness composite filaments. Finally, experimental validation of numerical results, particularly full field strain distribution maps obtained by digital image correlation technique for flexural testing and laboratory-scale 3D printed blade, confirms the accuracy of the finite element results. Finite element-based homogenization techniques provide valuable insights into potential failure modes in 3D printed tidal turbine blades. However, the expedited calculation of orthotropic properties through finite element analysis proves to be a faster mechanical characterization method compared to experimental approaches. The proposed methodology in this study facilitates quicker iterative design of 3D printed blades, thereby reducing the need for repeated experiments and ultimately lowering manufacturing costs

Mechanical Properties of End-crosslinked Entangled Polymer Networks using Sliplink Brownian Dynamics Simulations

The mechanical properties of a polymeric network containing both crosslinks and sliplinks (entanglements) are studied using a multi-chain Brownian dynamics simulation. We coarse-grain at the level of chain segments connecting consecutive nodes (cross- or sliplinks), with particular attention to the Gaussian statistics of the network. Affine displacement of nodes is not imposed: their displacement as well as sliding of monomers through sliplinks is governed by force balances. The simulation results of stress in uniaxial extension and the full stress tensor in simple shear including the (non-zero) second normal stress difference are presented for monodisperse chains with up to 18 entanglements between two crosslinks. The cases of two different force laws of the subchains (Gaussian chains and chains with finite extensibility) for two different numbers of monomers in a subchain (no = 50 and no = 100) are examined. It is shown that the additivity assumption of slip- and crosslink contribution holds for sufficiently long chains with two or more entanglements, and that it can be used to construct the strain response of a network of infinitely long chains. An important consequence is that the contribution of sliplinks to the small-strain shear modulus is about ⅔ of the contribution of a crosslink

Comparaison de quelques caractéristiques biologiques entre Dinarmus basalis Rond. (Hymenoptera: Pteromalidae) élevé soit sur son hôte habituel Callosobruchus maculatus F. (Coleoptera: Bruchidae) soit sur Acanthoscelides macrophthalmus Schaef. ou Bruchidius lineatopygus Pic. identifiés comme hôtes de substitution

Comparison of some Biological Characteristics between Dinarmus basalis Rond. (Hymenoptera: Pteromalidae) Reared either on his Habitual Host Callosobruchus maculatus F. (Coleoptera: Bruchidae) or on Acanthoscelides macrophthalmus Schaef. and Bruchidius lineatopygus Pic. Identified as Substitution Hosts. In this study, we have measured some biological parameters of Dinarmus basalis Rond. (Hymenoptera: Pteromalidae) when this parasitoid grows on three hosts: Callosobruchus maculatus F. (usual host), Acanthoscelides macrophthalma Schaef. and Bruchidius lineatopygus Pic. (substitution hosts). The results of this comparative study in no choice situation show that, life duration and development duration of this parasitoid are identical in laboratory conditions. By contrast, the female fecundity, the sexual rate and the parasitism rate of D. basalis are different according to the hosts presented. Although such differences appear to be small between C. maculatus and A. macrophthalmus. In presence of these two species, the number of eggs laid by the female of D. basalis is respectively 61 ± 5.24 and 54 ± 5.60, the sexual rate 37.63 ± 2.13% and 41.73 ± 3.69% and the parasitism rate 85.46 ± 2.61% and 76.48 ± 5.90%. This indicates that these two Bruchids can be used as hosts to D. basalis for a mass production. In presence of B. lineatopygus, the fecundity and the parasitism rate of D. basalis female are very low and the sexual rate more favourable of the males. This situation is unfavourable for a parasitoid production. When D. basalis females are placed in choice situation with equal number of the hosts nowely C. maculatus and A. macrophthalmus, the parasitism rate obtained, is higher for C. maculatus that of A. macrophthalmus. This parasitism rate remains high for C. maculatus even when the other host A. macrophthalmus is twice the number of C. maculatus. Thus the parasitoid seems to have a preference for his natural host. However, A. macrophthalmus can still be used in production unit of D. basalis