The effect of within-crop habitat manipulations on the conservation biological control of aphids in field-grown lettuce

Within-crop habitat manipulations have the potential to increase the biological control of pests in horticultural field crops. Wildflower strips have been shown to increase the abundance of natural enemies, but there is little evidence to date of an impact on pest populations. The aim of this study was to determine whether withincrop wildflower strips can increase the natural regulation of pests in horticultural field crops. Aphid numbers in plots of lettuce grown adjacent to wildflower strips were compared with those in plots grown in the absence of wildflowers. The presence of wildflower strips led to a decrease in aphid numbers on adjacent lettuce plants during June and July, but had less impact in August and September. The decrease in aphid numbers was greatest close to the wildflower strips and, the decrease in aphid numbers declined with increasing distance from the wildflower strips, with little effect at a distance of ten metres. The main natural enemies found in the crop were those that dispersed aerially, which is consistent with data from previous studies on cereal crops. Analysis and interpretation of natural enemy numbers was difficult due to low recovery of natural enemies, and the numbers appeared to follow changes in aphid abundance rather than being directly linked to the presence of wildflower strips. Cutting the wildflower strips, to remove floral resources, had no impact on the reduction in aphid numbers achieved during June and July, but decreased the effect of the wildflower strips during August and September. The results suggest that wildflower strips can lead to increased natural regulation of pest aphids in outdoor lettuce crops, but more research is required to determine how this is mediated by natural enemies and how the impact of wildflower strips on natural pest regulation changes during the growing season

Explosive Event in MON-3 Oxidizer System Resulting from Pressure Transducer Failure

In 2003, a Druck(Registered Trademark) pressure transducer failed catastrophically in a test system circulating nitrogen tetroxide at NASA Johnson Space Center White Sands Test Facility. The cause of the explosion was not immediately obvious since the wetted areas of the pressure transducer were constructed of materials compatible with nitrogen tetroxide. Chemical analysis of the resulting residue and a materials analysis of the diaphragm and its weld zones were used to determine the chain of events that led to the catastrophic failure. Due to excessive dynamic pressure loading in the test system, the diaphragm in the pressure transducer suffered cyclic failure and allowed the silicon oil located behind the isolation diaphragm to mix with the nitrogen tetroxide. The reaction between these two chemicals formed a combination of 2,4-di and 2,4,6-trinitrophenol, which are shock sensitive explosives that caused the failure of the pressure transducer. Further research indicated numerous manufacturers offer similar pressure transducers with silicone oil separated from the test fluid by a thin stainless steel isolation diaphragm. Caution must be exercised when purchasing a pressure transducer for a particular system to avoid costly failures and test system contamination

The Importance Of Female Choice: Evolutionary Perspectives On Constraints, Expressions, And Variations

This chapter introduces the reader to some of the influential perspectives on female mate choice in human evolutionary biology, including parental investment theory. We then present two key theories in evolutionary psychology that have been applied to understand variations in women’s mating preferences and choices: sexual strategies theory and strategic pluralism theory. Although the importance of female choice has gained widespread acceptance in the biological sciences, the influence that female choice has on mating systems can be limited by many factors, such as control over mating decisions by parents and men’s control over women’s sexuality. Despite these constraints on female choice, women are able to exercise their mate preferences through extramarital affairs and influencing parental attempts to arrange marriages.https://digitalcommons.chapman.edu/psychology_books/1015/thumbnail.jp

VLSI implementation of an efficient method for the computation of line spectral frequencies

In speech coding applications using linear predictive techniques, the computation of line spectral frequencies (LSFs) from the predictor coefficients is an extremely computationally intensive task. The unique properties of the symmetric and antisymmetric polynomial roots limit the region which must be searched, however it is still necessary to perform a root-finding algorithm on a high-order polynomial. Certain algorithms have been developed to reduce the complexity of the root finding exercise. One such algorithm, developed by Ramachandran and Kabal, takes advantage of certain properties of the symmetric and antisymmetric polynomials to map the upper portion of the unit circle onto the real interval [-1,1] by converting the polynomials into a Chebyshev polynomial series representation. Because Chebyshev polynomials may be evaluated efficiently using the Clenshaw recurrence formula, far fewer computations are necessary to search the linear region for zero crossings. This work investigates the implementation of the Ramachandran-Kabal algorithm in a VLSI design suitable for integration into larger speech processing systems. An implementation exclusively in VHDL is developed. Simulation of the VHDL design is performed and the post-synthesis results evaluated

Direct readout meteorological satellite data processing with a low-cost, computer-linked system

September, 1974.Includes bibliographical references

Constraining the Nature of X-ray Cavities in Clusters and Galaxies

We present results from an extensive survey of 64 cavities in the X-ray halos of clusters, groups and normal elliptical galaxies. We show that the evolution of the size of the cavities as they rise in the X-ray atmosphere is inconsistent with the standard model of adiabatic expansion of purely hydrodynamic models. We also note that the majority of the observed bubbles should have already been shredded apart by Rayleigh-Taylor and Richtmyer-Meshkov instabilities if they were of purely hydrodynamic nature. Instead we find that the data agrees much better with a model where the cavities are magnetically dominated and inflated by a current-dominated magneto-hydrodynamic jet model, recently developed by Li et al. (2006) and Nakamura et al. (2006). We conduct complex Monte-Carlo simulations of the cavity detection process including incompleteness effects to reproduce the cavity sample's characteristics. We find that the current-dominated model agrees within 1sigma, whereas the other models can be excluded at >5sigma confidence. To bring hydrodynamic models into better agreement, cavities would have to be continuously inflated. However, these assessments are dependent on our correct understanding of the detectability of cavities in X-ray atmospheres, and will await confirmation when automated cavity detection tools become available in the future. Our results have considerable impact on the energy budget associated with active galactic nucleus feedback.Comment: 21 pages, 12 figures, emulateapj, accepted for publication in ApJ, responded to referee's comments and added a new model, conclusions unchange

Mitigating NPD And R&D Risks Via A Portfolio Effect In Country Choice

New Product Development as well as Research and Development projects tend to be inherently risky investments.  Most MNC’s today have great latitude in choosing site and country locations to build or contract Research or Development projects.  MNC R&D risks, corporate wide, can be moderated via a diversification of NPD/R&D projects across multiple cultures and countries.  In fact there is some evidence that R&D global diversification can generate synergies.  (Fast track projects that work around the clock via work being done in three locations each 8 hours off from the other.) Foreign R&D facilities can help serve as outposts to facilitate the entrance into strategic foreign markets. This paper attempts to develop decision methodologies for allocating NPD/R&D globally with the goal of both reducing risks and increasing global competitiveness