4,594 research outputs found
Testing and validating the CERES-wheat (Crop Estimation through Resource and Environment Synthesis-wheat) model in diverse environments
CERES-Wheat is a computer simulation model of the growth, development, and yield of spring and winter wheat. It was designed to be used in any location throughout the world where wheat can be grown. The model is written in Fortran 77, operates on a daily time stop, and runs on a range of computer systems from microcomputers to mainframes. Two versions of the model were developed: one, CERES-Wheat, assumes nitrogen to be nonlimiting; in the other, CERES-Wheat-N, the effects of nitrogen deficiency are simulated. The report provides the comparisons of simulations and measurements of about 350 wheat data sets collected from throughout the world
M-1 injector development - Philosophy and implementation
Subscale and full scale test firings of M-1 injector to improve combustion efficienc
An Economic analysis of the potential for precision farming in UK cereal production
The results from alternative spatial nitrogen application studies are analysed in economic terms and compared to the costs of precision farming hardware, software and other services for cereal crops in the UK. At current prices, the benefits of variable rate application of nitrogen exceed the returns from a uniform application by an average of £22 ha−1 The cost of the precision farming systems range from £5 to £18 ha−1 depending upon the system chosen for an area of 250 ha. The benefits outweigh the associated costs for cereal farms in excess of 80 ha for the lowest price system to 200–300 ha for the more sophisticated systems. The scale of benefits obtained depends upon the magnitude of the response to the treatment and the proportion of the field that will respond. To be cost effective, a farmed area of 250 ha of cereals, where 30% of the area will respond to variable treatment, requires an increase in crop yield in the responsive areas of between 0·25 and 1.00 t ha−1 (at £65 t−1) for the basic and most expensive precision farming systems, respectively
Inducible and combinatorial gene manipulation in mouse brain
We have deployed recombinant adeno-associated viruses equipped with
tetracycline-controlled genetic switches to manipulate gene expression in
mouse brain. Here, we show a combinatorial genetic approach for inducible,
cell type-specific gene expression and Cre/loxP mediated gene recombination in
different brain regions. Our chemical-genetic approach will help to
investigate ‘when’, ‘where’, and ‘how’ gene(s) control neuronal circuit
dynamics, and organize, for example, sensory signal processing, learning and
memory, and behavior
CAIRNS: The Cluster And Infall Region Nearby Survey III. Environmental Dependence of H-alpha Properties of Galaxies
We investigate the environmental dependence of star formation in cluster
virial regions and infall regions as part of CAIRNS (Cluster And Infall Region
Nearby Survey), a large spectroscopic survey of the infall regions surrounding
nine nearby rich clusters of galaxies. Our long-slit spectroscopy yields
estimates of star formation rates in environments from cluster cores to the
general large-scale structure. The fraction of galaxies with current star
formation in their inner disks as traced by H-alpha emission increases with
distance from the cluster and converges to the ``field'' value only at 2-3
virial radii, in agreement with other investigations. However, among galaxies
with significant current star formation (EW[Ha]geq2\AA), there is no difference
in the distribution of EW[Ha] inside and outside the virial radius. This
surprising result, first seen by Carter et al., suggests that (1) star
formation is truncated on either very short timescales or only at moderate and
high redshifts or (2) that projection effects contaminate the measurement. The
number density profiles of star-forming and non-star-forming galaxies indicate
that, among galaxies projected inside the virial radius, at least half of the
former and 20% of the latter are ``infall interlopers,'' galaxies in the infall
region but outside the virial region. The kinematics of star-forming galaxies
in the infall region closely match those of absorption-dominated galaxies. This
result shows that the star forming galaxies in the infall regions are not
interlopers from the field and excludes one model of the backsplash scenario of
galaxy transformation. Finally, we quantify systematic uncertainties in
estimating the global star formation in galaxies from their inner disks.Comment: 25 pages, 21 figures, accepted for publication in A
Levels and sources of volatile organic compounds in homes of children with asthma
Many volatile organic compounds ( VOC s) are classified as known or possible carcinogens, irritants, and toxicants, and VOC exposure has been associated with the onset and exacerbation of asthma. This study characterizes VOC levels in 126 homes of children with asthma in Detroit, Michigan, USA. The total target VOC concentration ranged from 14 to 2274 μ g/m 3 (mean = 150 μ g/m 3 ; median = 91 μ g/m 3 ); 56 VOC s were quantified; and d ‐limonene, toluene, p , m ‐xylene, and ethyl acetate had the highest concentrations. Based on the potential for adverse health effects, priority VOC s included naphthalene, benzene, 1,4‐dichlorobenzene, isopropylbenzene, ethylbenzene, styrene, chloroform, 1,2‐dichloroethane, tetrachloroethene, and trichloroethylene. Concentrations varied mostly due to between‐residence and seasonal variation. Identified emission sources included cigarette smoking, solvent‐related emissions, renovations, household products, and pesticides. The effect of nearby traffic on indoor VOC levels was not distinguished. While concentrations in the Detroit homes were lower than levels found in other North American studies, many homes had elevated VOC levels, including compounds that are known health hazards. Thus, the identification and control of VOC sources are important and prudent, especially for vulnerable individuals. Actions and policies to reduce VOC exposures, for example, sales restrictions, improved product labeling, and consumer education, are recommended.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108002/1/ina12086.pd
Understanding the contribution of target repetition and target expectation to the emergence of the prevalence effect in visual search
Behavior in visual search tasks is influenced by the proportion of trials on which a target is presented (the target prevalence). Previous research has found that when target prevalence is low (2% prevalence), participants tend to miss targets, compared with higher prevalence levels (e.g., 50% prevalence). There is an ongoing debate regarding the relative contribution of target repetition and the expectation that a target will occur in the emergence of prevalence effects. In order to disentangle these two factors, we went beyond previous studies by directly manipulating participants’ expectations regarding how likely a target was to appear on a given trial. This we achieved without using cues or feedback. Our results indicated both target repetition and target expectation contribute to the emergence of the prevalence effect
Dual-Target Cost in Visual Search for Multiple Unfamiliar Faces.
The efficiency of visual search for one (single-target) and either of two (dual-target) unfamiliar faces was explored to understand the manifestations of capacity and guidance limitations in face search. The visual similarity of distractor faces to target faces was manipulated using morphing (Experiments 1 and 2) and multidimensional scaling (Experiment 3). A dual-target cost was found in all experiments, evidenced by slower and less accurate search in dual- than single-target conditions. The dual-target cost was unequal across the targets, with performance being maintained on one target and reduced on the other, which we label "preferred" and "non-preferred" respectively. We calculated the capacity for each target face and show reduced capacity for representing the non-preferred target face. However, results show that the capacity for the non-preferred target can be increased when the dual-target condition is conducted after participants complete the single-target conditions. Analyses of eye movements revealed evidence for weak guidance of fixations in single-target search, and when searching for the preferred target in dual-target search. Overall, the experiments show dual-target search for faces is capacity- and guidance-limited, leading to superior search for 1 face over the other in dual-target search. However, learning faces individually may improve capacity with the second face. (PsycINFO Database Recor
Multiaperture Photometry of Galaxies in the Coma Cluster
We present a set of photometry for 745 band selected
objects in a region centered on the core of the Coma
cluster. This includes 516 galaxies and is at least 80% complete to H=16, with
a spectroscopically complete sample of 111 cluster members (nearly all with
morphological classification) for . For each object we present total
\cite{kron80} magnitudes and aperture photometry. As an example, we use these
data to derive color-magnitude relations for Coma early-type galaxies, measure
the intrinsic scatter of these relations and its dependence on galaxy mass, and
address the issue of color gradients. We find that the color gradients are mild
and that the intrinsic scatter about the color-magnitude relation is small
( mag in and less than in , or ).
There is no evidence that the intrinsic scatter varies with galaxy luminosity,
suggesting that the cluster red sequence is established at early epochs over a
range of in stellar mass.Comment: 41 pages, 5 figures, 18 data tables attached to source files or
available on request from R. De propris. Accepted for publication in
Astrophysical Journal Supplement Serie
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