61,907 research outputs found

    Stationary device produces homogeneous mixture of fluids

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    Stationary device produces a homogeneous mixture of two or more one-phase or two-phase fluids. The device contains two concentric flow guides with helical passageways through which the fluids are forced into turbulent flow by the system pressure differential

    Organic barley producers' desired qualities for crop improvement

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    Barley fits well into many different organic farming systems. It can be grown as either a winter or spring annual crop in many temperate regions. Barley can be used for food, malting, or animal feed, providing growers with diverse marketing opportunities. Despite its advantages, many organic farmers in the USA have not adopted barley as a regular crop in their rotation. Researchers surveyed organic barley producers to discover what they considered to be the main obstacles to growing barley. The primary obstacles identified were limited markets and price. Breeding and development of high-quality barley suitable for organic systems and specialty markets may be a way to expand markets and secure a better price. Farmers identified yield as the most important agronomic trait of interest, but other traits such as nutritional quality were also highly ranked. Naked (hull-less) barley bred for multi-use quality is a possible alternative that allows organic farmers to sell into multiple markets. Most respondents expressed interest in the development of such varieties suitable for organic farming conditions. The researchers conducted follow-up interviews to obtain detailed information on how barley is used in organic farming systems, production practices, costs of production, and what traits farmers would like to see breeders focus on

    Improving Barley for Organic Producers: What Do Organic Producers Want?

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    Researchers surveyed organic barley producers in order to find out how many acres they are growing, what varieties they grow, what markets they are growing barley for, whether they receive a price premium for organic barley, whether they are growing or would be interested in growing multi-use naked barley, what production challenges they face, and what traits they would like to see improved

    The DAWN Project evaluation 2007

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    Effective String Theory of Vortices and Regge Trajectories

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    Starting from a field theory containing classical vortex solutions, we obtain an effective string theory of these vortices as a path integral over the two transverse degrees of freedom of the string. We carry out a semiclassical expansion of this effective theory, and use it to obtain corrections to Regge trajectories due to string fluctuations.Comment: 27 pages, revtex, 3 figures, corrected an error with the cutoff in appendix E (was previously D), added more discussion of Fig. 3, moved some material in section 9 to a new appendi

    The turing model comes of molecular age

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    Molecular analysis of hair follicle formation provide evidence to support the most well-known mathematical model for biological pattern formation

    Comment on ``Intermittent Synchronization in a Pair of Coupled Chaotic Pendula"

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    The main aim of this comment is to emphasize that the conditional Lyapunov exponents play an important role in distinguishing between intermittent and persistent synchronization, when the analytic criteria for asymptotic stability are not uniformly obeyed.Comment: 2 pages, RevTeX 4, 1 EPS figur

    Making use of geometrical invariants in black hole collisions

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    We consider curvature invariants in the context of black hole collision simulations. In particular, we propose a simple and elegant combination of the Weyl invariants I and J, the {\sl speciality index} S{\cal S}. In the context of black hole perturbations S\cal S provides a measure of the size of the distortions from an ideal Kerr black hole spacetime. Explicit calculations in well-known examples of axisymmetric black hole collisions demonstrate that this quantity may serve as a useful tool for predicting in which cases perturbative dynamics provide an accurate estimate of the radiation waveform and energy. This makes S{\cal S} particularly suited to studying the transition from nonlinear to linear dynamics and for invariant interpretation of numerical results.Comment: 4 pages, 3 eps figures, Revte

    The Chemical Evolution of the Universe I: High Column Density Absorbers

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    We construct a simple, robust model of the chemical evolution of galaxies from high to low redshift, and apply it to published observations of damped Lyman-alpha quasar absorption line systems (DLAs). The elementary model assumes quiescent star formation and isolated galaxies (no interactions, mergers or gas flows). We consider the influence of dust and chemical gradients in the galaxies, and hence explore the selection effects in quasar surveys. We fit individual DLA systems to predict some observable properties of the absorbing galaxies, and also indicate the expected redshift behaviour of chemical element ratios involving nucleosynthetic time delays. Despite its simplicity, our `monolithic collapse' model gives a good account of the distribution and evolution of the metallicity and column density of DLAs, and of the evolution of the global star formation rate and gas density below redshifts z 3. However, from the comparison of DLA observations with our model, it is clear that star formation rates at higher redshifts (z>3) are enhanced. Galaxy interactions and mergers, and gas flows very probably play a major role.Comment: 36 pages, 11 figures; accepted by MNRA

    The impact of scatterometer wind data on global weather forecasting

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    The impact of SEASAT-A scatterometer (SASS) winds on coarse resolution atmospheric model forecasts was assessed. The scatterometer provides high resolution winds, but each wind can have up to four possible directions. One wind direction is correct; the remainder are ambiguous or "aliases'. In general, the effect of objectively dealiased-SASS data was found to be negligible in the Northern Hemisphere. In the Southern Hemisphere, the impact was larger and primarily beneficial when vertical temperature profile radiometer (VTPR) data was excluded. However, the inclusion of VTPR data eliminates the positive impact, indicating some redundancy between the two data sets
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