1,735 research outputs found
Drainage water management impact on farm profitability
The representative farm planning model that is used for the 2005 Purdue University Top Farmer Crop Workshop base case was extended to include managed drainage activities in order to evaluate the impact of drainage management time on farm operations. The analysis considered two alternative enterprises: rotation corn soybeans with and without controlled drainage activities. The baseline solution assumed that controlled drainage has 10% higher average yields than free flowing drainage, one drainage control structure is needed each 20 acres, and all drainage management work was done on good field days. The results suggest that the baseline optimal solution was rotation corn-soybeans with controlled drainage where 1,500 acres were cultivated with corn following soybeans and 1,500 acres with soybeans following corn. Compared to the enterprise without controlled drainage, the annual returns to resources were 10% and 7.9% higher with and without EQIP subsidy respectively. Time opportunity cost for the managed drainage activities in each time period in the baseline solution was zero except for Dec. 6 Apr. 21 period when its value was 675,505. Increasing labor available by one more hour would increase the profits by 28.06 (Apr 22 Apr 25), 229.48 (May 3 May 9), 28.07 (Nov. 1 Nov 14 and Nov 15-Dec 5). In the baseline scenario the yield advantage threshold for profitability of managed drainage was 2.3% and 4.5% with and without EQIP subsidy respectively.Farm Management,
Evaluation of thallium-201 scanning for detection of latent coronary artery disease
The use of thallium imaging as a noninvasive method to accurately screen shuttle passengers for latent coronary artery disease was investigated. All radionuclide procedures were performed using an Anger type camera with a high resolution collimator. A minimum of 200,000 counts were collected for each image using a 20% window centered on the 69-83 keV X-rays. For the images obtained following injection with the patient at rest, the testing was begun 10 minutes after injection. Injections of TT during exercise were made at a point near the termination of the treadmill procedure as determined by either the appearance of ST segment changes on the electrocardiogram consistant with subendocardial ischemia, the appearance of angina-like chest pain in the patient or fatigue in the patient which required cessation of the test. The severity of heart disease was based on the medical history, physical exam, exercise electrocardiograms, chest X-rays and the coronary arteriogram
SPATIOTEMPORAL MODELING OF AGRICULTURAL YIELD MONITOR DATA1
This paper shows that spatial panel data models can be successfully applied to an econometric analysis of farm-scale precision agriculture data. The application focuses on the estimation of the effect of controlled drainage water management equipment on corn yields. Using field-level precision agriculture data and spatial panel techniques, the yield response equation is estimated using the spatial autoregressive error random effects model with temporal heterogeneity, incorporating spatial dependence in the error term, while controlling for the topography, weather and the controlled drainage treatment. Controlling for random effects allows for the disentanglement of the effects of spatial dependence from spatial heterogeneity and omitted variables, and thus, to properly investigate the yield response. The results show that controlled drainage has a statistically significant effect on corn yields. The effect is generally positive but varies widely from year to year and field-to-field. For the two years of data controlled drainage was linked to a 2.2% increase in field average yield, but that varied from a -2.6% to a +6.5%. Evaluated at mean elevation and slope in the east part of the field, controlled drainage is associated with 10 bu/a increase and a 0.6 bu/a decrease in yields in 2005 and 2006, respectively. In the West part of the field, controlled drainage is associated with a 11 bu/a increase in 2006 and 2.81 bu/a decrease in 2005.Manufactured Housing; corn, drainage, precision agriculture, spatial panel model
Aristelliger praesignis (Jamaican Croaking Lizard). Maximum Size.
This article is available as on open access publication downloadable from the Society for the Study of Amphibians and Reptiles website https://ssarherps.org/herpetological-review-pdfs/. The attached file is the published pdf
Stochastic Feedback and the Regulation of Biological Rhythms
We propose a general approach to the question of how biological rhythms
spontaneously self-regulate, based on the concept of ``stochastic feedback''.
We illustrate this approach by considering the neuroautonomic regulation of the
heart rate. The model generates complex dynamics and successfully accounts for
key characteristics of cardiac variability, including the power spectrum,
the functional form and scaling of the distribution of variations, and
correlations in the Fourier phases. Our results suggest that in healthy systems
the control mechanisms operate to drive the system away from extreme values
while not allowing it to settle down to a constant output.Comment: 15 pages, latex2e using rotate and epsf, with 4 ps figures. Submitted
to PR
Measurements of proton induced reaction cross sections on 120Te for the astrophysical p-process
The total cross sections for the 120Te(p,gamma)121I and 120Te(p,n)120I
reactions have been measured by the activation method in the effective
center-of-mass energies between 2.47 MeV and 7.93 MeV. The targets were
prepared by evaporation of 99.4 % isotopically enriched 120Te on Aluminum and
Carbon backing foils, and bombarded with proton beams provided by the FN tandem
accelerator at the University of Notre Dame. The cross sections and factors
were deduced from the observed gamma ray activity, which was detected off-line
by two Clover HPGe detectors mounted in close geometry. The results are
presented and compared with the predictions of statistical model calculations
using the codes NON-SMOKER and TALYS.Comment: 17 pages, 5 figures, 5 tables, regular articl
Cross section measurement of N 14 ( p , γ ) O 15 in the CNO cycle
Background: The CNO cycle is the main energy source in stars more massive than our sun; it defines the energy production and the cycle time that lead to the lifetime of massive stars, and it is an important tool for the determination of the age of globular clusters. In our sun about 1.6% of the total solar neutrino flux comes from the CNO cycle. The largest uncertainty in the prediction of this CNO flux from the standard solar model comes from the uncertainty in the ^{14}\mathrm{N}(p,\ensuremath{\gamma})^{15}\mathrm{O} reaction rate; thus, the determination of the cross section at astrophysical temperatures is of great interest.Purpose: The total cross section of the ^{14}\mathrm{N}(p,\ensuremath{\gamma})^{15}\mathrm{O} reaction has large contributions from the transitions to the excited state and the ground state of . The transition is dominated by radiative direct capture, while the ground state is a complex mixture of direct and resonance capture components and the interferences between them. Recent studies have concentrated on cross-section measurements at very low energies, but broad resonances at higher energy may also play a role. A single measurement has been made that covers a broad higher-energy range but it has large uncertainties stemming from uncorrected summing effects. Furthermore, the extrapolations of the cross section vary significantly depending on the data sets considered. Thus, new direct measurements have been made to improve the previous high-energy studies and to better constrain the extrapolation.Methods: Measurements were performed at the low-energy accelerator facilities of the nuclear science laboratory at the University of Notre Dame. The cross section was measured over the proton energy range from to 3.6 MeV for both the ground state and the transitions at {\ensuremath{\theta}}_{\text{lab}}={0}^{\ensuremath{\circ}}, {45}^{\ensuremath{\circ}}, {90}^{\ensuremath{\circ}}, {135}^{\ensuremath{\circ}}, and {150}^{\ensuremath{\circ}}. Both TiN and implanted- targets were utilized. \ensuremath{\gamma} rays were detected by using an array of high-purity germanium detectors.Results: The excitation function as well as angular distributions of the two transitions were measured. A multichannel -matrix analysis was performed with the present data and is compared with previous measurements. The analysis covers a wide energy range so that the contributions from broad resonances and direct capture can be better constrained.Conclusion: The astrophysical factors of the and the ground-state transitions were extrapolated to low energies with the newly measured differential-cross-section data. Based on the present work, the extrapolations yield {S}_{6.79}(0)=1.29\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.09(\mathrm{syst})\phantom{\rule{4pt}{0ex}}\mathrm{keV}\phantom{\rule{0.16em}{0ex}}\mathrm{b} and {S}_{\text{g.s.}}(0)=0.42\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{stat})\phantom{\rule{4pt}{0ex}}\mathrm{keV}\phantom{\rule{0.16em}{0ex}}\mathrm{b}. While significant improvement and consistency is found in modeling the transition, large inconsistencies in both the -matrix fitting and the low-energy data are reaffirmed for the ground-state transition. Reflecting this, a systematic uncertainty of {}_{\ensuremath{-}0.19}^{+0.09}\phantom{\rule{4pt}{0ex}}\mathrm{keV}\phantom{\rule{0.16em}{0ex}}\mathrm{b} is recommended for the ground-state transition
Analytic Detection Thresholds for Measurements of Linearly Polarized Intensity Using Rotation Measure Synthesis
A fully analytic statistical formalism does not yet exist to describe
radio-wavelength measurements of linearly polarized intensity that are produced
using rotation measure synthesis. In this work we extend the analytic formalism
for standard linear polarization, namely that describing measurements of the
quadrature sum of Stokes Q and U intensities, to the rotation measure synthesis
environment. We derive the probability density function and expectation value
for Faraday-space polarization measurements for both the case where true
underlying polarized emission is present within unresolved Faraday components,
and for the limiting case where no such emission is present. We then derive
relationships to quantify the statistical significance of linear polarization
measurements in terms of standard Gaussian statistics. The formalism developed
in this work will be useful for setting signal-to-noise ratio detection
thresholds for measurements of linear polarization, for the analysis of
polarized sources potentially exhibiting multiple Faraday components, and for
the development of polarization debiasing schemes.Comment: 14 pages, 6 figures, accepted for publication in MNRA
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