Coupling Soybean Cyst Nematode Damage to CROPGRO-Soybean

The soybean cyst nematode (SCN) Heterodera glycines Ichinohe is responsible for substantial economic losses in soybean (Glycine max L. Merr.) production throughout the U.S. Results from past efforts to quantify the severity of crop damage resulting from SCN are often subject to variable experimental conditions resulting from differences in weather, soil type, and cultivar. Because of the difficulty in accounting for these variables, a process–oriented crop growth simulation model was chosen as a platform for studying the dynamics of SCN damage and for transferring knowledge between crop production scenarios. The objective of this study was to develop and evaluate hypotheses for coupling SCN damage to the process–oriented crop growth model CROPGRO–Soybean. A monomolecular function was used to relate daily SCN damage to initial population density of SCN eggs. The equation was incorporated into the crop model in order to test two hypotheses of how SCN damage occurs. The first hypothesis was that SCN reduce daily photosynthesis (Pg), while the second hypothesis was that SCN reduce daily potential root water uptake (RWU). Canopy biomass data collected in 1997 and 1998 from a site in Iowa were used to estimate damage function parameters for two distinct coupling points, one applied to reduce daily photosynthesis (Pg) and the other applied to reduce daily potential root water uptake (RWU). Function parameters were estimated by minimizing the log transformation of root mean square error (RMSE) between predicted and measured canopy biomass collected every 2 weeks during the season in Iowa. Biomass data collected in 1997 and 1998 from an independent site in Missouri were used to validate the SCN damage models. The minimum root mean squared errors (RMSE) of canopy and grain biomass were 0.245 and 0.198 log10(kg ha–1), respectively, for the RWU coupling point, and 0.238 and 0.193 log10(kg ha–1), respectively, for the Pg coupling point at the independent site in Missouri. The damage functions transferred very well to the independent site. Validation showed that the Pg coupling point represented the variability of both canopy and final yield data slightly better than the RWU coupling point

Estimate of the impact of background particles on the X-Ray Microcalorimeter Spectrometer on IXO

We present the results of a study on the impact of particles of galactic (GCR) and solar origin for the X-ray Microcalorimeter Spectrometer (XMS) aboard an astronomical satellite flying in an orbit at the second Lagrangian point (L2). The detailed configuration presented in this paper is the one adopted for the International X-Ray Observatory (IXO) study, however the derived estimates can be considered a conservative limit for ATHENA, that is the IXO redefined mission proposed to ESA. This work is aimed at the estimate of the residual background level expected on the focal plane detector during the mission lifetime, a crucial information in the development of any instrumental configuration that optimizes the XMS scientific performances. We used the Geant4 toolkit, a Monte Carlo based simulator, to investigate the rejection efficiency of the anticoincidence system and assess the residual background on the detector.Comment: 18 pages, 9 figure

Soybean Cyst Nematode Reduces Soybean Yield Without Causing Obvious Aboveground Symptoms

Field experiments were conducted at locations in northern and southern Illinois, central Iowa, and central Missouri from 1997 to 1999 to investigate the effects of Heterodera glycines on soybean growth, development, and yield. A wide range of infestation levels was present at all locations. Two locally adapted cultivars, one resistant to H. glycines, were grown at each location. Cultivars were planted in alternating four-row strips with 76 cm between rows. For each cultivar, 20 1-m-long single-row plots were sampled every 2 weeks starting 4 weeks after planting. Infection by H. glycines reduced plant height and leaf and stem weight on the resistant cultivars in the first 12 weeks after planting, and delayed pod and seed development 12 to 14 weeks after planting. Biomass accumulation was not reduced on the susceptible cultivars until 10 weeks after planting; reduction in pod and seed development occurred throughout the reproductive stages. Susceptible cultivars produced significantly lower yields than resistant cultivars, but the yield reductions were not accompanied by visually detectable symptoms

Supersymmetry and the positron excess in cosmic rays

Recently the HEAT balloon experiment has confirmed an excess of high-energy positrons in cosmic rays. They could come from annihilation of dark matter in the galactic halo. We discuss expectations for the positron signal in cosmic rays from the lightest superpartner. The simplest interpretations are incompatible with the size and shape of the excess if the relic LSPs evolved from thermal equilbrium. Non-thermal histories can describe a sufficient positron rate. Reproducing the energy spectrum is more challenging, but perhaps possible. The resulting light superpartner spectrum is compatible with collider physics, the muon anomalous magnetic moment, Z-pole electroweak data, and other dark matter searches.Comment: 4 pages, 2 figures, references added, minor wording change

A Standard Greenhouse Method for Assessing Soybean Cyst Nematode Resistance in Soybean: SCE08 (Standardized Cyst Evaluation 2008)

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is distributed throughout the soybean [Glycine max (L.) Merr.] production areas of the United States and Canada (Fig. 1) (26). SCN remains the most economically important pathogen of soybean in North America; the most recent estimate of soybean yield reduction in North America due to SCN totaled 34,659,000 metric tons during 2006 (34)

Women’s Long-Term Reactions to Whole-Body Scanning: A Mixed Methods Approach

This study investigated long-term impacts of whole-body scanning. A total of 91 women completed a retrospective online questionnaire. Quantitative data revealed that 31 (34%) reported greater body dissatisfaction since the scan, and only 6 (7%) reported increased satisfaction. Positive change in satisfaction was predicted by current body satisfaction but not by body mass index (BMI) at time of scanning or by age. BMI did not predict satisfaction with the scanner process or likelihood of being rescanned, though a longer gap between scanning and questionnaire completion predicted satisfaction with the process. Inductive thematic analysis of responses to an open-ended question suggested that although women were comfortable being scanned and wanted to see an accurate and objective view of their size and shape, they also felt threatened and vulnerable when seeing their bodies on the printed output. It is concluded that whole-body scanning should be used with caution, particularly with women with existing body concerns

Developing Novel Acoustic Emission Procedures for Failure Prediction of Carbon-Epoxy COPVs and Related Composite Materials

No abstract availabl

The cosmic ray positron excess and neutralino dark matter

Using a new instrument, the HEAT collaboration has confirmed the excess of cosmic ray positrons that they first detected in 1994. We explore the possibility that this excess is due to the annihilation of neutralino dark matter in the galactic halo. We confirm that neutralino annihilation can produce enough positrons to make up the measured excess only if there is an additional enhancement to the signal. We quantify the `boost factor' that is required in the signal for various models in the Minimal Supersymmetric Standard Model parameter space, and study the dependence on various parameters. We find models with a boost factor greater than 30. Such an enhancement in the signal could arise if we live in a clumpy halo. We discuss what part of supersymmetric parameter space is favored (in that it gives the largest positron signal), and the consequences for other direct and indirect searches of supersymmetric dark matter.Comment: 11 pages, 6 figures, matches published version (PRD

Temporal evolution of solar energetic particle spectra

During solar flares and coronal mass ejections, solar energetic par- ticles (SEPs) may be released into the interplanetary medium and near-Earth locations. The energy spectra of SEP events at 1 AU are typically averaged over the entire event or studied in a few snapshots. In this paper we analyze the time evolution of the energy spectra of four large selected SEP events using a large number of snapshots. We use a multi-spacecraft and multi-instrument approach for the observations, obtained over a wide SEP energy range. We find large differences in the spectra at the beginning of the events as measured by different instruments. We show that over time, a wave-like structure is observed traveling through the spectra from the highest energies to the lowest energies, creating an “arch” shape which then straightens into a power law later in the event, after times of the order of 10 hours. We discuss the processes that determine SEP intensities and their role in shaping the spectral time evolution