27,043 research outputs found
Five-year financial analysis of two commercial farms converting to organic: 2000-2005
The financial performance including input and output costs were analysed for two commercial Scottish farms converting to organic production. A comparative analysis for a five year period is provided using data from the Scottish Farm Accounts scheme, and demonstrates that both conversions had positive financial outcomes. Both farms applied strategic changes to their businesses
Prevalence, Incidence, and Spatial Dependence of Soybean mosaic virus in Iowa
The prevalence of soybean fields with plants infected with Soybean mosaic virus (SMV) in Iowa is assumed to be random, because the primary source of the virus is SMV-infected seed. Data collected from 2,500 soybean fields sampled over a 3-year period as part of the Iowa Soybean Disease Survey (2005 to 2007) were used to evaluate this assumption. SMV was first detected in early June of each year but counties in which it was first detected varied among years. Prevalence at the county scale at end of season was 32.3, 27.3, and 89.9% in 2005, 2006, and 2007, respectively. End-of-season incidence of SMV within SMV-positive counties was 1.5 to 25.0, 1.7 to 24, and 1.8 to 58% in 2005, 2006, and 2007, respectively. The number of fields in which plants infected with SMV were detected increased at the linear rate of approximately one new field every 2 days in 2007, compared with one new field every 22 days (2005) and 21 days (2006), with coefficients of determination (R2) of 93.2 to 96.8% using the linear model. Weak spatial dependence for end-of-season SMV incidence was detected using Moran\u27s Index, indicating that the risk for SMV incidence at the county scale within Iowa at the end of the growing season is not random
Probabilistic models of information retrieval based on measuring the divergence from randomness
We introduce and create a framework for deriving probabilistic models of Information Retrieval. The models are nonparametric models of IR obtained in the language model approach. We derive term-weighting models by measuring the divergence of the actual term distribution from that obtained under a random process. Among the random processes we study the binomial distribution and Bose--Einstein statistics. We define two types of term frequency normalization for tuning term weights in the document--query matching process. The first normalization assumes that documents have the same length and measures the information gain with the observed term once it has been accepted as a good descriptor of the observed document. The second normalization is related to the document length and to other statistics. These two normalization methods are applied to the basic models in succession to obtain weighting formulae. Results show that our framework produces different nonparametric models forming baseline alternatives to the standard tf-idf model
Hybrid functional calculations of the Al impurity in silica: Hole localization and electron paramagnetic resonance parameters
We performed first-principle calculations based on the supercell and cluster
approaches to investigate the neutral Al impurity in smoky quartz. Electron
paramagnetic resonance measurements suggest that the oxygens around the Al
center undergo a polaronic distortion which localizes the hole being on one of
the four oxygen atoms. We find that the screened exchange hybrid functional
successfully describes this localization and improves on standard local density
approaches or on hybrid functionals that do not include enough exact exchange
such as B3LYP. We find a defect level at about 2.5 eV above the valence band
maximum, corresponding to a localized hole in a O 2p orbital. The calculated
values of the g tensor and the hyperfine splittings are in excellent agreement
with experiment.Comment: 5 pages, 2 figures, 1 tabl
NOS/NGS activities to support development of radio interferometric surveying techniques
National Geodetic Survey activities towards the development of operational geodetic survey systems based on radio interferometry are reviewed. Information about the field procedures, data reduction and analysis, and the results obtained to date is presented
Evaluating the Importance of Stem Canker of Soybean in Iowa
The relative importance of stem canker of soybean in Iowa compared with other soybean diseases present in the state was assessed using data collected from over 3,400 soybean fields sampled in the Iowa Soybean Disease Survey that was conducted from 2005 to 2007. Symptomatic plant tissues from soybean plants with stem canker symptoms were cultured on acidified potato dextrose agar. The prevalence of stem canker on soybean in 2005 in Iowa was 2.6%; the disease was not detected in 2006 and 2007. In 2005, 63 isolates with Diaporthe/Phomopsis characteristics were collected. To identify isolates to fungal species and variety, single-spored isolates were subjected to polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) and sequencing of the internal transcribed spacer (ITS) region. Fourteen isolates were identified as D. phaseolorum var. caulivora (northern stem canker) and 49 as Phomopsis longicolla. To quantify and compare the aggressiveness of D. phaseolorum var. caulivora isolates collected in Iowa, nine isolates were arbitrarily selected for components analysis. Incubation period, rate of lesion expansion, final lesion length, and time to plant death for each isolate were quantified. Significant differences in components of aggressiveness were detected among the nine isolates. Results from this work suggest stem canker is a minor disease of soybean in Iowa
Anisotropy beta functions
The flow of couplings under anisotropic scaling of momenta is computed in
theory in 6 dimensions. It is shown that the coupling decreases as
momenta of two of the particles become large, keeping the third momentum fixed,
but at a slower rate than the decrease of the coupling if all three momenta
become large simultaneously. This effect serves as a simple test of effective
theories of high energy scattering, since such theories should reproduce these
deviations from the usual logarithmic scale dependence.Comment: uuencoded ps file, 6 page
Arkansas Cotton Variety Test 2002
The primary aim of the Arkansas Cotton Variety Test is to provide unbiased data regarding the agronomic performance of cotton varieties and advanced breeding lines in the major cotton-growing areas of Arkansas. This information helps seed dealers establish marketing strategies and assists producers in choosing varieties to plant. In this way, the annual test facilitates the inclusion of new, improved genetic material into Arkansas cotton production. Variety adaptation is determined by evaluation of the varieties and lines at four University of Arkansas research stations located near Keiser, Clarkedale, Marianna, and Rohwer. Tests are duplicated in irrigated and non-irrigated culture at the Keiser and Marianna locations. In 2002, 37 entries were evaluated in the main test and 25 were evaluated in the first-year test. This report also includes the Mississippi County Cotton Variety Test (a large-plot, on-farm evaluation of 12 Round-up Ready varieties) and 12 other on-farm cotton variety tests conducted by the University of Arkansas Cooperative Extension Service
Quantification of Temporal and Spatial Dynamics of Bean pod mottle virus at Different Spatial Scales
Bean pod mottle virus (BPMV) is the most prevalent virus infecting soybean (Glycine max) in the United States; however, the temporal and spatial dynamics in BPMV at varying spatial scales has not been elucidated. To quantify the temporal and spatial dynamics of BPMV at a field scale, a quadrat-based method was developed in which six soybean rows, each consisting of 30-cm-long quadrats, were established within soybean cv. NE3001 field plots (i.e., 150 quadrats per plot) in BPMV-inoculated and non-inoculated plots. Quadrats were sampled by selecting the youngest fully expanded leaflet from each of four plants within each quadrat beginning 25 days after planting, and continued at 8- to 11- day intervals until crop senescence. Leaf sap was extracted from each 4-leaflet (bulked) sample (from each quadrat), and tested for presence of the BPMV by ELISA. Quadrat position (plot, row, and quadrat number) and the date of sampling that each quadrat first tested positive for BPMV was recorded and mapped. The rate of BPMV incidence in 2006 ranged from 0.09 to 0.12 logits/day, indicating that BPMV incidence was doubling every 5.3 to 7.7 days in 2006. Doubling times for BPMV incidence in 2007 were slower, ranging from 17.3 to 34.7 days. Analysis of spatial patterns using ordinary runs revealed that BPMV-infected quadrats were predominantly clustered within both BPMV-inoculated and non-inoculated plots throughout both growing seasons. In addition to within field plot studies, a threeyear statewide disease survey (2005-2007) was conducted in Iowa to quantify county and field scale BPMV prevalence and incidence by systematically selecting 30 plants/soybean field (8 to 16 soybean fields per county). Leaf samples were then tested for BPMV by ELISA and county-level BPMV incidence maps were generated using ArcGIS software. End-of-season BPMV prevalence was 39/96 counties in 2005 (40%), 90/99 counties in 2006 (90.1%), and 74/99 counties in 2007 (74.7%). The incidence of BPMV within Iowa counties ranged from 0 to 100% and BPMV incidence significantly increased statewide from north to south. Spatial autocorrelation (dependence) analysis using Moran’s I revealed clustering for BPMV incidence among Iowa counties, indicating that BPMV incidence among counties was not random. The elucidation of the within-field temporal and spatial dynamics of BPMV and the statewide geographic distribution of BPMV in Iowa has important implications with regards to sampling, plant disease forensics, BPMV management, and risk prediction of BPMV
Searching for solar-like oscillations in the delta Scuti star rho Puppis
Despite the shallow convective envelopes of delta Scuti pulsators, solar-like
oscillations are theoretically predicted to be excited in those stars as well.
To search for such stochastic oscillations we organised a spectroscopic
multi-site campaign for the bright, metal-rich delta Sct star rho Puppis. We
obtained a total of 2763 high-resolution spectra using four telescopes. We
discuss the reduction and analysis with the iodine cell technique, developed
for searching for low-amplitude radial velocity variations, in the presence of
high-amplitude variability. Furthermore, we have determined the angular
diameter of rho Puppis to be 1.68 \pm 0.03 mas, translating into a radius of
3.52 \pm 0.07Rsun. Using this value, the frequency of maximum power of possible
solar-like oscillations, is expected at ~43 \pm 2 c/d (498 \pm 23 muHz). The
dominant delta Scuti-type pulsation mode of rho Puppis is known to be the
radial fundamental mode which allows us to determine the mean density of the
star, and therefore an expected large frequency separation of 2.73 c/d (31.6
muHz). We conclude that 1) the radial velocity amplitudes of the delta Scuti
pulsations are different for different spectral lines; 2) we can exclude
solar-like oscillations to be present in rho Puppis with an amplitude per
radial mode larger than 0.5 m/s.Comment: 14 pages, 12 figure, accepted for MNRA
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