594 research outputs found

    Previous Grass-Lucerne Mixtures Affect Barley Yield and Quality in a Semiarid Location of the Canadian Prairie Region

    Get PDF
    In the semiarid region of the Canadian prairies perennial forages are not rotated with annual crops because previous experiments reported negative impacts (Kilcher and Anderson 1963; Campbell et al. 1990). However, previous research used persistent species while short-lived species could have less adverse effect. Our objective was to compare three grass species in three lucerne mixtures terminated with tillage or herbicide for effects on barley grain, N concentration, and N uptake

    The Dark Side of Galaxy Color: evidence from new SDSS measurements of galaxy clustering and lensing

    Full text link
    The age matching model has recently been shown to predict correctly the luminosity L and g-r color of galaxies residing within dark matter halos. The central tenet of the model is intuitive: older halos tend to host galaxies with older stellar populations. In this paper, we demonstrate that age matching also correctly predicts the g-r color trends exhibited in a wide variety of statistics of the galaxy distribution for stellar mass M* threshold samples. In particular, we present new measurements of the galaxy two-point correlation function and the galaxy-galaxy lensing signal as a function of M* and g-r color from the Sloan Digital Sky Survey, and show that age matching exhibits remarkable agreement with these and other statistics of low-redshift galaxies. In so doing, we also demonstrate good agreement between the galaxy-galaxy lensing observed by SDSS and the signal predicted by abundance matching, a new success of this model. We describe how age matching is a specific example of a larger class of Conditional Abundance Matching models (CAM), a theoretical framework we introduce here for the first time. CAM provides a general formalism to study correlations at fixed mass between any galaxy property and any halo property. The striking success of our simple implementation of CAM provides compelling evidence that this technique has the potential to describe the same set of data as alternative models, but with a dramatic reduction in the required number of parameters. CAM achieves this reduction by exploiting the capability of contemporary N-body simulations to determine dark matter halo properties other than mass alone, which distinguishes our model from conventional approaches to the galaxy-halo connection.Comment: references added, minor adjustments to text and notatio
    corecore