Comparison of Two Year Classes of Hybrid Grass Carp and Grass Carp for Aquatic Plant Control

Two year classes of grass carp and F, hybrids resulting from bighead carp male x grass carp female were compared at various stocking densities for aquatic plant control. One and two year old grass carp exhibited higher survival rates and better growth rates than the same age hybrid grass carp. The presence of grass carp or hybrid grass carp decreased both Secchi disc transparencies and dissolved oxygen values. Grass carp had a greater negative effect upon these measurements because they removed the vegetation quicker than the hybrid grass carp. These apparent detrimental effects on water quality are necessary trade-offs for vegetation removal by any method. Grass carp and hybrid grass carp utilized Chara sp., Potamogeton pectinatus, Hydrodicton sp., Rhizoclonia sp., and Pithophora sp. Two year old hybrid grass carp required approximately twice as much time as the same age grass carp to eliminate dense growths of the vegetation listed above. One year old hybrid grass carp were slightly less effective than one year old grass carp at controlling these same plant species. However, it was extremely difficult for one or two year old hybrid grass carp to totally eliminate dense growths of these plant species except at high stocking densities. The use of mean vegetation heights to indirectly measure total plant biomass was unacceptable whenever unpreferred floating plant species were present. The hybrid grass carp appeared to be a poor alternative biological control for nuisance aquatic vegetation when compared directly to the grass carp

Mesoscale modelling of polyelectrolyte electrophoresis

The electrophoretic behaviour of flexible polyelectrolyte chains ranging from single monomers up to long fragments of hundred repeat units is studied by a mesoscopic simulation approach. Abstracting from the atomistic details of the polyelectrolyte and the fluid, a coarse-grained molecular dynamics model connected to a mesoscopic fluid described by the Lattice Boltzmann approach is used to investigate free-solution electrophoresis. Our study demonstrates the importance of hydrodynamic interactions for the electrophoretic motion of polyelectrolytes and quantifies the influence of surrounding ions. The length-dependence of the electrophoretic mobility can be understood by evaluating the scaling behavior of the effective charge and the effective friction. The perfect agreement of our results with experimental measurements shows that all chemical details and fluid structure can be safely neglected, and a suitable coarse-grained approach can yield an accurate description of the physics of the problem, provided that electrostatic and hydrodynamic interactions between all entities in the system, i.e., the polyelectrolyte, dissociated counterions, additional salt and the solvent, are properly accounted for. Our model is able to bridge the single molecule regime of a few nm up to macromolecules with contour lengths of more than 100 nm, a length scale that is currently not accessible to atomistic simulations.Comment: 23 pages, 9 figures, to be presented at Faraday Discussion 14

Environmental impacts of grazed clover/grass pastures

peer-reviwedGrazed clover/grass pastures are important for animal production systems and the clover component is critical for its contribution to N inputs via biological fixation of atmospheric N2. The resource efficiency and environmental emissions for clover/grass pastures can differ from that of N-fertilised grass-only pastures. Fixation of N2 by clover uses photosynthetically- fixed carbon, whereas fertiliser N production consumes fossil fuels and has net greenhouse gas (GHG) emissions. Clover has a higher phosphorus (P) requirement than grass and where extra P fertiliser is used for clover/grass pastures the risk of P loss to waterways is greater than for grass-only pastures. Nitrogen leaching from grazed pasture increases exponentially with increased N inputs and urinary-N contributes 70 to 90% of total N leaching. However, the few studies comparing clover/grass and N-fertilised grass-only pastures at similar total N inputs indicated similar N leaching losses. Nitrous oxide emissions from grazed pastures due to N-cycling of excreta are similar for clover/grass and N-fertilised grass-only pastures at similar total N inputs. However, grass-only pasture requires the application of N fertiliser, which will result in additional specific losses that don’t occur from clover-fixed N. Thus, total N2O emissions are generally higher for N-fertilised grass pastures than for clover/grass pastures. A summary of various whole-system and life cycle assessment analyses for dairy farms from various countries indicated that at similar total N inputs, clover/grass pasture systems can be more efficient than N-fertilised grass systems per kilogram of milk produced from an energy use and GHG perspective whereas results for nutrient losses to waterways were mixed and appear to be similar for both pasture types. In practice, other management practices on farm, such as crop integration, supplementary feeding strategy and winter management, can have a larger overall effect on environmental emissions than whether the N input is derived from fertiliser N or from N2 fixation

A 64-point Fourier transform chip for high-speed wireless LAN application using OFDM

In this article, we present a novel fixed-point 16-bit word-width 64-point FFT/IFFT processor developed primarily for the application in the OFDM based IEEE 802.11a Wireless LAN (WLAN) baseband processor. The 64-point FFT is realized by decomposing it into a 2-D structure of 8-point FFTs. This approach reduces the number of required complex multiplications compared to the conventional radix-2 64-point FFT algorithm. The complex multiplication operations are realized using shift-and-add operations. Thus, the processor does not use any 2-input digital multiplier. It also does not need any RAM or ROM for internal storage of coefficients. The proposed 64-point FFT/IFFT processor has been fabricated and tested successfully using our in-house 0.25 ?m BiCMOS technology. The core area of this chip is 6.8 mm2. The average dynamic power consumption is 41 mW @ 20 MHz operating frequency and 1.8 V supply voltage. The processor completes one parallel-to-parallel (i. e., when all input data are available in parallel and all output data are generated in parallel) 64-point FFT computation in 23 cycles. These features show that though it has been developed primarily for application in the IEEE 802.11a standard, it can be used for any application that requires fast operation as well as low power consumption

Detection of Airborne Allegen Phl p5 and its Correlation with Poaceae Pollen Counts in Evora, South Portugal

Introduction: Airborne pollen of grasses (Poaceae family) is the main aeroallergen in many european countries, namely in Portugal. Their pollen can be found in the air all over the year but higher concentrations are reached in springtime (Mars to June). Exposure to its allergens is deduced from pollen counts of environmental air samples. The aim of this study is to analyse the relationship between these pollen counts and the concentration of allergen Phl p5, through a new sampling technology, developed under an European LIFE/Environment program. Methods: Airborne pollen were monitored with a Hirst-type sampler (Burkard 7-day pollen trap). Simultaneously, daily air samples were collected with a high volumetric cyclone-type sampler (Coriolis ® d by Bertin Technologies, France) and Phl p5 concentration was measured from liquid samples through a “sandwich” ELISA with a kit from Indoor Biotecnologies®. Both samplers were placed side by side on a meteorological platform at the town center of Evora, 17 m above ground level and 320 m above sea level. ELISA analysis were performed on samples collected between the 2th of Mars and 12 th of June 2007, which includes the main pollen season for grasses and Phleum pratense. Results: Pollen counts from both samplers were not correlated, with absolute values higher in Burkard sampler. Phl p5 concentration in air samples followed the same features of cyclone-type sampler but it was quantified even when pollen counts were low or null, particularly in the beginning of pollen season. Several peaks of allergen were detected at the end of March and on the 1st - 2nd of April. Conclusions: Coriolis ® d cyclone sampler allowed the quantification of Poaceae either by pollen counts and by an ELISA assay but further analysis on the efficiency of sampling and its relationship with biophysical parameters are needed. These results suggest that pollen counts may not reflect exposure to Poaceae pollen. Immuno-sampling could provide a better understanding of exposure to airborne pollen allergens, namely out of the pollen season

Preparation and characterization of cogon grass natural fiber as a concrete filler for gamma radiation shielding

Concrete is a combination of cement, fine aggregate, coarse aggregate, and water. Concrete has a high shielding potential against gamma radiation from radioactive source. Concretes having a higher attenuation coefficient may be produced by varying the additives of various specific densities to increase the shielding performance. This study uses a cogon grass fiber, an invasive and unwanted grass due to their ability to grow, and disrupt desirable vegetation efficiently as a reinforcement material mixed into the concrete composite to observe its performance in radiation shielding. Natural fiber is known to have a tolerance to post splitting, high energy absorption and increased fatigue resistance of cement-based composites. Cogon grass fibers are use with different percentages of 0%, 0.5%, 1.0% and 1.5% fiber content with four different thicknesses. In this study, the chemical and physical properties of cogon grass were characterized by the hydrolysis process (Chesson Method) and Atomic Force Microscopy (AFM), respectively. The effect of different percentage of cogon grass fiber in concrete with different thickness to linear attenuation coefficient, the difference of linear attenuation coefficient value between lead concrete and cogon grass fiber concrete and half value layer (HVL) were also investigated. The possibility of using cogon grass natural fiber as a block of concrete for gamma radiation shielding was also evaluated based on the results obtained in this study. The results show that the hemicellulose, cellulose and lignin content of raw cogon grass fiber were 27.60%, 36.62% and 6.11%, respectively. AFM micrograph of cogon grass showed a blocky and rough surface. The calculated linear attenuation coefficient of cogon grass fiber showed an increase with the increase of fiber content and thickness. However, lead concrete showed a higher attenuation coefficient and lower HVL value compared to cogon grass fiber. Despite that, cogon grass fiber concrete may have the potential to be used as shielding material with some improvement

Nutrient Digestibility and Productivity of Bali Cattle Fed Fermented Hymenachne Amplexia­calis Based Rations Supplemented with Leucaena Leucocephala

An experiment was conducted to study the effects of lamtoro (Leucaena leucocephala) leaf supplementation in fermented kumpai grass (Hymenachne amplexia­calis) based rations on the productivity of Bali cattle. Variables measured were dry matter and organic matter intakes, nutrient digestibility (dry matter, organic matter, crude protein, and crude fiber), body weight gain, and feed efficiency. The types of rations were: Ration A= 45% fermented kumpai grass + 40% benggala grass + 15% concentrate + 0% lamtoro leaf, Ration B= 45% fermented kumpai grass + 30% benggala grass + 15% concentrate + 10% lamtoro leaf, Ration C= 45% fermented kumpai grass + 20% benggala grass + 15% concentrate + 20% lamtoro leaf, and Ration D= 45% fermented kumpai grass + 10% benggala grass + 15% concentrate + 30% lamtoro leaf. The supplementation of lamtoro leaf up to 30% into the ration could increase (P<0.05) dry matter and organic matter intakes, and crude protein digestibility. The highest body weight gain and feed efficiency were found in Bali cattle fed ration with 20% lamtoro leaf supplementation. The level of lamtoro leaf supplementation in the ration did not affect the digestibility of dry matter, organic matter, and crude fiber. It was concluded that the supplementation of lamtoro leaf in the ration could increase dry matter, organic matter, and crude protein intakes. Addition of 20% lamtoro leaf gave the best effect on the increased body weight gain and feed efficiency in Bali cattle

Effect of grass mulch application on tubers size and yield of ware potatoes in organic farming

The aim of this experiment was to evaluate influence of mulching on the tuber yield and on the number of ware potatoes. In organic farming grass mulch for potatoes was used in 2008. For the experiments different ways of mulching (grass mulch after planting, grass mulch after second hoeing) were used and compared with bare soil (control variant). The results showed that grass mulching had positive effect on the yield of ware potatoes and some of the yield-forming components. The yield of ware potatoes was significantly higher by 9.3 t/ha in comparison with control variant. The highest number of ware potatoes was found out in the variant with grass mulch after planting