3,207 research outputs found
Water-Conserving Attitudes and Landscape Choices in New Mexico
Water Conservation, Residential Landscape, Urban Water Use, Municipal Water Program, Resource /Energy Economics and Policy, Q25, Q48,
YIELD RESPONSE AND PRODUCTION RISK: AN ANALYSIS OF INTEGRATED PEST MANAGEMENT IN COTTON
Production uncertainty is commonly believed to be an impediment to the adoption of less pesticide-intensive methods in agriculture such as integrated pest management (IPM). To investigate the effects of pest control inputs on yields and yield variability, data from a cross-section of San Joaquin Valley cotton producers were analyzed in a heteroskedastic production model. The results suggest that yields are increasing with soil quality, crop rotation, frequency of field monitoring, and the use of independent pest control advisors. Yield variability was not found to be significantly affected by production inputs, including pesticides and IPM practices with the exception of frequent contact with extension farm advisors which was found to contribute to reduced yield variability.Production Economics, Risk and Uncertainty,
DSN advanced receiver: Breadboard description and test results
A breadboard Advanced Receiver for use in the Deep Space Network was designed, built, and tested in the laboratory. Field testing was also performed during Voyager Uranus encounter at DSS-13. The development of the breadboard is intended to lead towards implementation of the new receiver throughout the network. The receiver is described on a functional level and then in terms of more specific hardware and software architecture. The results of performance tests in the laboratory and in the field are given. Finally, there is a discussion of suggested improvements for the next phase of development
A Quantitative Risk Assessment of the Human Health Impacts Due to Macrolide Use in Swine
We used a retrospective modeling approach instead of the traditional farm to fork model; back calculating (Cm) the number of human macrolide resistant C. coli mfections caused by eating contaminated pork, due to specific macrolide use in swine. We used the estimated number of culture confirmed human infections (Ct). As a measure of human health risk, we then calculated the expected number among the (Cm) cases that experience an adverse treatment outcome (prolonged illness) due to macrolide resistance, using estimates for fluoroquinolone. We divided the model into Release, Exposure and Consequence assessment sections according to FDA guidance 152 and utilized @Risk software with 20,000 iterations for simulation. The results show the human health risks are negligible. For example, the predicted annual risk, for preventton and growth promotion uses is only 1 in 92 million per U.S. resident, with a 5% chance it could be as high as 1 in 52 million. Our model focuses on the impact of resistance on human treatment. It assumes that macrolide resistance C. coli infection reduces treatment efficacy. However, it is possible that risks less than our estimates
Optimized tracking of RF carriers with phase noise, including Pioneer 10 results
The ability to track very weak signals from distant spacecraft is limited by the phase instabilities of the received signal and of the local oscillator employed by the receiver. These instabilities ultimately limit the minimum loop bandwidth that can be used in a phase-coherent receiver, and hence limit the ratio of received carrier power to noise spectral density which can be tracked phase coherently. A method is presented for near real time estimation of the received carrier phase and additive noise spectrum, and optimization of the phase locked loop bandwidth. The method was used with the breadboard Deep Space Network (DSN) Advanced Receiver to optimize tracking of very weak signals from the Pioneer 10 spacecraft, which is now more distant that the edge of the solar system. Tracking with bandwidths of 0.1 Hz to 1.0 Hz reduces tracking signal threshold and increases carrier loop signal to noise ratio (SNR) by 5 dB to 15 dB compared to the 3 Hz bandwidth of the receivers now used operationally in the DSN. This will enable the DSN to track Pioneer 10 until its power sources fails near the end of the century
Determination of the wind response of Saturn 5 by statistical methods, volume 1
Statistical analysis of Saturn 5 launch vehicle wind response - Vol.
Anomalous Fermi Liquid Behavior of Overdoped High-Tc Superconductors
According to a generic temperature vs. carrier-doping (T-p) phase diagram of
high-temperature superconductors it has been proposed that as doping increases
to the overdoped region they approach gradually a conventional (canonical)
Fermi Liquid. However, Hall effect measurements in several systems reported by
different authors show a still strong \emph{T}-dependence in overdoped samples.
We report here electrical transport measurements of
Y_{1-x}Ca_{x}Ba_{2}Cu_{3}O_{7-delta} thin films presenting a temperature
dependence of the Hall constant, R_H, which does not present a gradual
transition towards the T-independent behavior of a canonical Fermi Liquid.
Instead, the T-dependence passes by a minimum near optimal doping and then
increases again in the overdoped region. We discuss the theoretical predictions
from two representative Fermi Liquid models and show that they can not give a
satisfactory explanation to our data. We conclude that this region of the phase
diagram in YBCO, as in most HTSC, is not a canonical Fermi Liquid, therefore we
call it Anomalous Fermi Liquid.Comment: 9 pages, 12 figures, to be published in Phys. Rev.
Universal and unique features of kinesin motors: Insights from a comparison of fungal and animal conventional kinesins
Kinesins are microtubule motors that use the energy derived from the hydrolysis of ATP to move unidirectionally along microtubules, The founding member of this still growing superfamily is conventional kinesin, a dimeric motor that moves processively towards the plus end of microtubules, Within the family of conventional kinesins, two groups can be distinguished to date, one derived from animal species, and one originating from filamentous fungi. So far no conventional kinesin has been reported from plant cells. Fungal and animal conventional kinesins differ in several respects, both in terms of their primary sequence and their physiological properties. Thus all fungal conventional kinesins move at velocities that are 4-5 times higher than those of animal conventional kinesins, and all of them appear to lack associated light chains. Both groups of motors are characterized by a number of group-specific sequence features which are considered here with respect to their functional importance. Animal and fungal conventional kinesins also share a number of sequence characteristics which point to common principles of motor function. The overall domain organization is remarkably similar. A C-terminal sequence motif common to all kinesins, which constitutes the only region of high homology outside the motor domain, suggests common principles of cargo association in both groups of motors. Consideration of the differences of, and similarities between, fungal and animal kinesins offers novel possibilities for experimentation (e.g., by constructing chimeras) that can be expected to contribute to our understanding of motor function
Submicrosecond comparison of international clock synchronization by VLBI and the NTS satellite
The intercontinental clock synchronization capabilities of Very Long Baseline Interferometry (VLBI) and the Navigation Technology Satellite (NTS) were compared using both methods to synchronize the Cesium clocks at the NASA Deep Space Net complexes at Madrid, Spain and Goldstone, California. Verification of the accuracy of both systems was examined. The VLBI experiments used the Wideband VLBI Data Acquisition System developed at the NASA Jet Propulsion Laboratory. The NTS Satellites were designed and built by the Naval Research Laboratory used with NTS Timing Receivers developed by the Goddard Space Flight Center. The two methods agreed at about the one-half microsecond level
- …