Tracking ocean wave spectrum from SAR images

An end to end algorithm for recovery of ocean wave spectral peaks from Synthetic Aperture Radar (SAR) images is described. Current approaches allow precisions of 1 percent in wave number, and 0.6 deg in direction

Registration of WS4U and WS8U Switchgrass Germplasms

Two upland switchgrass (Panicum virgatum L.) germplasm pools, WS4U (Reg. no. GP-92, PI 639191) and WS8U (Reg. no. GP-93, PI 639192), were released cooperatively on 18 July 2002 by the University of Wisconsin, University of Nebraska, and the USDA-ARS, Lincoln, NE. These germplasms were developed as source material to be used in developing cultivars with increased biomass yield and geographic adaptation for bioenergy production in USDA hardiness zones 3 and 4 in the northern USA and similar geographic regions of southern Canada. WS4U is a tetraploid (2n = 4x = 36) and WS8U is an octoploid (2n = 8x = 72)

A prototype system for observing the Atlantic Meridional Overturning Circulation - scientific basis, measurement and risk mitigation strategies, and first results

The Atlantic Meridional Overturning Circulation (MOC) carries up to one quarter of the global northward heat transport in the Subtropical North Atlantic. A system monitoring the strength of the MOC volume transport has been operating since April 2004. The core of this system is an array of moored sensors measuring density, bottom pressure and ocean currents. A strategy to mitigate risks of possible partial failures of the array is presented, relying on backup and complementary measurements. The MOC is decomposed into five components, making use of the continuous moored observations, and of cable measurements across the Straits of Florida, and wind stress data. The components compensate for each other, indicating that the system is working reliably. The year-long average strength of the MOC is 18.7±5.6 Sv, with wind-driven and density-inferred transports contributing equally to the variability. Numerical simulations suggest that the surprisingly fast density changes at the western boundary are partially linked to westward propagating planetary wave

Effect of micro-organism and particle size on fermentation of sorghum and maize for poultry feed

A study was conducted to investigate the effect of particle size and micro-organism on fermentation of sorghum and maize for poultry feed. Sorghum (Sorghum bicolour L. Moench) and maize were milled in a hammer mill and separated into coarse, medium, fine and very fine particles sizes with a stack of sieves of apertures 2.5 mm, 850 μm and 500 μm, from the first to the last sieve and ending in a pan with the very fine particles. Samples were weighed into 100 g sachets and irradiated using 60Co at 25 kGy γ-radiation. Grains were fermented with sterile distilled water for 24 h at a ratio of 1 feed:1.4 water and inoculated with 0.01 ml of an overnight culture of De Man, Rogosa and Sharpe (MRS) broth containing Pediococcus acidilactici (PA1) or Lactobacillus plantarum (SLP) (ca 109 cfu/ml). The medium was incubated at 30°C simultaneously with a control treatment without lactic acid bacteria (LAB). Subsamples were collected aseptically at the beginning of the fermentation (0 h) and at 4, 8, 24 h after fermentation for pH, sugar and organic acids analysis. Significant reductions in the pH of maize and sorghum for LAB treatments (PA1 and SLP) were evident after 8 hours of fermentation. Twenty four hour lactic acid concentrations from coarse particle size fermentations were not significantly different from concentrations in the medium and fine particle size fermentations. The choice of LAB did not affect the concentration of lactic acid for any particle size. However, acetic acid production from fermentation with PA1 was significantly higher (P<0.01) than the concentration obtained with SLP. Results suggest that moderate grain processing may be enough to permit production of biosafe levels of lactic acid in fermented feed for poultry birds.Keywords: Fermentation, lactic acid bacteria, maize, particle size, sorghum African Journal of Biotechnology Vol. 12(26), pp. 4147-415

Quantum key distribution and 1 Gbit/s data encryption over a single fibre

We perform quantum key distribution (QKD) in the presence of 4 classical channels in a C-band dense wavelength division multiplexing (DWDM) configuration using a commercial QKD system. The classical channels are used for key distillation and 1 Gbps encrypted communication, rendering the entire system independent from any other communication channel than a single dedicated fibre. We successfully distil secret keys over fibre spans of up to 50 km. The separation between quantum channel and nearest classical channel is only 200 GHz, while the classical channels are all separated by 100 GHz. In addition to that we discuss possible improvements and alternative configurations, for instance whether it is advantageous to choose the quantum channel at 1310 nm or to opt for a pure C-band configuration.Comment: 9 pages, 7 figure

Comparing families of dynamic causal models

Mathematical models of scientific data can be formally compared using Bayesian model evidence. Previous applications in the biological sciences have mainly focussed on model selection in which one first selects the model with the highest evidence and then makes inferences based on the parameters of that model. This “best model” approach is very useful but can become brittle if there are a large number of models to compare, and if different subjects use different models. To overcome this shortcoming we propose the combination of two further approaches: (i) family level inference and (ii) Bayesian model averaging within families. Family level inference removes uncertainty about aspects of model structure other than the characteristic of interest. For example: What are the inputs to the system? Is processing serial or parallel? Is it linear or nonlinear? Is it mediated by a single, crucial connection? We apply Bayesian model averaging within families to provide inferences about parameters that are independent of further assumptions about model structure. We illustrate the methods using Dynamic Causal Models of brain imaging data

Green turtles highlight connectivity across a regional marine protected area network in west Africa

Networks of marine protected areas (MPAs) are invaluable for the protection of species with high dispersal capacity, yet connectivity within networks is poorly understood. We demonstrate the connectivity within the regional MPA network in West Africa (RAMPAO), mediated by the largest green turtle population in the eastern Atlantic Ocean. We equipped with satellite tags 45 female green turtles nesting in the Bijagó s Archipelago, Guinea-Bissau, and tracked them during internesting, migration, and foraging to quantify the degree of coverage the RAMPAO network provides during each of these critical periods. During the internesting period, turtles were largely concentrated around the nesting islands, with a mean of 94.8% (SD 0.1%, range: 46% - 100%, n = 40 turtles) of tracking positions falling within MPA limits. Among the 35 turtles successfully tracked into the foraging period, we identified variable migratory strategies, with 12 turtles remaining near-resident at distances of 40-90 km from breeding sites, 10 turtles migrating 300-400 km to The Gambia and Senegal, and 13 turtles traveling >1000 km to northern Mauritania. Of the 35 foraging turtles, 26 used MPAs, with a mean of 78.0% (SD 34.8%, range: 3.7% - 100%) of their tracking positions falling within the limits of RAMPAO MPAs, across Guinea-Bissau, Senegal and Mauritania. Migration corridors with high concentrations of passing turtles were mostly located nearshore, and 21% of these high passage areas fell within the MPA network. Overall, we found that this population connects five RAMPAO MPAs, yet some foraging sites (e.g., in the Bijagó s) and important migration areas (e.g., Cap-Vert peninsula) described here are currently unprotected. These results are relevant to any considerations of MPA extension or establishment within the regional network, which would contribute towards meeting the Convention on Biological Diversity targets for national marine protected area estate coverage. By documenting biological connectivity across RAMPAO, this study represents an important example of the relevance of international protected area networks for green turtle conservation and for wider conservation action at a regional scale.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Nonmonotonic d_{x^2-y^2} Superconducting Order Parameter in Nd_{2-x}Ce_xCuO_4

Low energy polarized electronic Raman scattering of the electron doped superconductor Nd_1.85Ce_0.15CuO_4 (T_c=22 K) has revealed a nonmonotonic d_{x^2-y^2} superconducting order parameter. It has a maximum gap of 4.4 k_BT_c at Fermi surface intersections with antiferromagnetic Brillouin zone (the ``hot spots'') and a smaller gap of 3.3 k_BT_c at fermionic Brillouin zone boundaries. The gap enhancement in the vicinity of the ``hot spots'' emphasizes role of antiferromagnetic fluctuations and similarity in the origin of superconductivity for electron- and hole-doped cuprates.Comment: 4 pages, 4 figure