8,581 research outputs found

    MSAT an alternative choice?

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    A number of potential applications are described of MSAT that use the unique properties of this transportation mechanism. Emphasis is placed on the market introduction strategy for the North American system

    The genetic architecture underlying the evolution of a rare piscivorous life history form in brown trout after secondary contact and strong introgression

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    Identifying the genetic basis underlying phenotypic divergence and reproductive isolation is a longstanding problem in evolutionary biology. Genetic signals of adaptation and reproductive isolation are often confounded by a wide range of factors, such as variation in demographic history or genomic features. Brown trout ( ) in the Loch Maree catchment, Scotland, exhibit reproductively isolated divergent life history morphs, including a rare piscivorous (ferox) life history form displaying larger body size, greater longevity and delayed maturation compared to sympatric benthivorous brown trout. Using a dataset of 16,066 SNPs, we analyzed the evolutionary history and genetic architecture underlying this divergence. We found that ferox trout and benthivorous brown trout most likely evolved after recent secondary contact of two distinct glacial lineages, and identified 33 genomic outlier windows across the genome, of which several have most likely formed through selection. We further identified twelve candidate genes and biological pathways related to growth, development and immune response potentially underpinning the observed phenotypic differences. The identification of clear genomic signals divergent between life history phenotypes and potentially linked to reproductive isolation, through size assortative mating, as well as the identification of the underlying demographic history, highlights the power of genomic studies of young species pairs for understanding the factors shaping genetic differentiation

    Potential Anti-cancer and Anti-bacterial Activities of Philippine Echinoderm Extracts

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    In high-throughput search for bioactive compounds under resource-limited settings from Philippine echinoderms, the aqueous, methanol, chloroform and hexane extracts of seven Philippine echinoderms namely Holothuria nobilis (sea cucumber), Bohadscia marmorata (sea cucumber), Stichopus chloronatus (sea cucumber), Holothuria axiologa (sea cucumber), Linckia laevigata (starfish), Oreaster nodusus (starfish) and Ophiocoma ochoenleinii (brittle star) were screened for antitumor and antibacterial activity. Antitumor activity was determined using brine shrimp lethality assay while antibacterial assay was performed using turbidimetric method. Both assays utilized 96-well microtiter plates to facilitate speed and ease in screening. The chloroform extract of H. nobilis gave a positive result on antitumor activity while almost all sample extracts showed antibacterial activity against E. coli

    Progress Toward Accurate Measurements of Power Consumptions of DBD Plasma Actuators

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    The accurate measurement of power consumption by Dielectric Barrier Discharge (DBD) plasma actuators is a challenge due to the characteristics of the actuator current signal. Micro-discharges generate high-amplitude, high-frequency current spike transients superimposed on a low-amplitude, low-frequency current. We have used a high-speed digital oscilloscope to measure the actuator power consumption using the Shunt Resistor method and the Monitor Capacitor method. The measurements were performed simultaneously and compared to each other in a time-accurate manner. It was found that low signal-to-noise ratios of the oscilloscopes used, in combination with the high dynamic range of the current spikes, make the Shunt Resistor method inaccurate. An innovative, nonlinear signal compression circuit was applied to the actuator current signal and yielded excellent agreement between the two methods. The paper describes the issues and challenges associated with performing accurate power measurements. It provides insights into the two methods including new insight into the Lissajous curve of the Monitor Capacitor method. Extension to a broad range of parameters and further development of the compression hardware will be performed in future work

    Progress Toward Accurate Measurement of Dielectric Barrier Discharge Plasma Actuator Power

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    The accurate measurement of power consumption by dielectric barrier discharge plasma actuators is a challenge due to the characteristics of the actuator current signal. Microdischarges generate high-amplitude, high-frequency current spike transients superimposed on a low-amplitude, low-frequency current. A high-speed digital oscilloscope was used to measure the actuator power consumption using the shunt resistor method and the monitor capacitor method. The measurements were performed simultaneously and compared to each other in a time-accurate manner. It was found that low signal-to-noise ratios of the oscilloscopes used, in combination with the high dynamic range of the current spikes, make the shunt resistor method inaccurate. An innovative, nonlinear signal compression circuit was applied to the actuator current signal and yielded excellent agreement between the two methods. The paper describes the issues and challenges associated with performing accurate power measurements. It provides insights into the two methods including new insight into the Lissajous curve of the monitor capacitor method. Extension to a broad range of parameters and further development of the compression hardware will be performed in future work

    Manganese in Texas Soils and its Relation to Crops.

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    37 p

    Time-delayed feedback control in astrodynamics

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    In this paper we present time-delayed feedback control (TDFC) for the purpose of autonomously driving trajectories of nonlinear systems into periodic orbits. As the generation of periodic orbits is a major component of many problems in astodynamics we propose this method as a useful tool in such applications. To motivate the use of this method we apply it to a number of well known problems in the astrodynamics literature. Firstly, TDFC is applied to control in the chaotic attitude motion of an asymmetric satellite in an elliptical orbit. Secondly, we apply TDFC to the problem of maintaining a spacecraft in a periodic orbit about a body with large ellipticity (such as an asteroid) and finally, we apply TDFC to eliminate the drift between two satellites in low Earth orbits to ensure their relative motion is bounded

    Direct Hopf Bifurcation in Parametric Resonance of Hybridized Waves

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    We study parametric resonance of interacting waves having the same wave vector and frequency. In addition to the well-known period-doubling instability we show that under certain conditions the instability is caused by a Hopf bifurcation leading to quasiperiodic traveling waves. It occurs, for example, if the group velocities of both waves have different signs and the damping is weak. The dynamics above the threshold is briefly discussed. Examples concerning ferromagnetic spin waves and surface waves of ferro fluids are discussed.Comment: Appears in Phys. Rev. Lett., RevTeX file and three postscript figures. Packaged using the 'uufiles' utility, 33 k

    Imbibition in mesoporous silica: rheological concepts and experiments on water and a liquid crystal

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    We present, along with some fundamental concepts regarding imbibition of liquids in porous hosts, an experimental, gravimetric study on the capillarity-driven invasion dynamics of water and of the rod-like liquid crystal octyloxycyanobiphenyl (8OCB) in networks of pores a few nanometers across in monolithic silica glass (Vycor). We observe, in agreement with theoretical predictions, square root of time invasion dynamics and a sticky velocity boundary condition for both liquids investigated. Temperature-dependent spontaneous imbibition experiments on 8OCB reveal the existence of a paranematic phase due to the molecular alignment induced by the pore walls even at temperatures well beyond the clearing point. The ever present velocity gradient in the pores is likely to further enhance this ordering phenomenon and prevent any layering in molecular stacks, eventually resulting in a suppression of the smectic phase in favor of the nematic phase.Comment: 18 pages, 8 figure

    TRIGLYCERIDES AND CHOLESTEROL SERUM LEVELS IN PERUVIAN PASO HORSES UNDER TWO REARING SYSTEMS

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    El objetivo del presente estudio fue comparar los niveles de triglicéridos (TG), colesterol total (CT) y fraccionado en caballos peruanos de paso (CPP) de la Región Lambayeque. Se analizaron sueros de 50 CPP (25 sedentarios, 25 activos). Los TG y CT se determinaron con el uso de kits comerciales, mientras que las lipoproteínas HDL-C y LDL-C se determinaron después de precipitación selectiva con polímeros precipitantes selectivos (sulfato de dextrán, Mg++). Las VLDL-C se calcularon restando al CT los valores de HDL-C + LDL-C. Los niveles promedio fueron de 25.69 mg/dl para TG, 108.71 mg/dl para CT, 66.55 mg/dl para HDL-C, 21.38 mg/dl para LDL-C, y 20.78 mg/dl para VLDLC. Los valores séricos de HDL-C en CPP activos fueron estadísticamente superiores que en los sedentarios (p<0.01), en tanto que los valores de TG fueron inferiores en caballos castrados en comparación con las yeguas (p<0.05). Los CPP sedentarios tuvieron niveles menores de HDL-C que los activos, aunque estos últimos tienen menor riesgo aterogénico; sin embargo, tanto caballos activos como sedentarios son poco susceptibles a sufrir hipertrigliceridemia.The objective of the study was to compare the level of triglycerides (TG), totalcholesterol (TC) and its fractions (VLDC-C, LDL-C and HDL-C) in blood serum of PeruvianPaso Horses (CPP) in the Lambayeque Region. Serum of 50 CPP animals (25 sedentaryand 25 active) were analyzed. TG and TC levels were determined using commercial kits,whereas HDL-C and LDL-C were determined using selective polymer precipitants (dextransulphate, Mg++). VLDL-C was calculated by subtracting HDL-C + LDL-C values from TClevels. Mean values were 25.69 mg/dl for TG, 108.71 mg/dl for TC, 66.55 mg/dl for HDL-C,21.38 mg/dl for LDL-C, and 20.78 mg/dl for VLDL-C. HDL-C serum values in active CPPanimals were statistically higher than in sedentary horses (p<0.01), whereas TG values were statistically lower in castrated horses as compared to mares (p<0.05). Sedentary horses registered lower levels of HDL-C as compared with active animals, but the latter have lesser atherogenic risk; however, both active and sedentary horses have low susceptibility to get hypertrigliceridemia
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