TEMPORAL COST ANALYSIS OF A NEW DEVELOPMENT IN CONTROLLED ATMOSPHERE STORAGE: THE CASE OF VIDALIA ONIONS

Agribusiness,

NO synthase? Generation of nitric oxide in plants

It has now become well accepted that nitric oxide (NO) has a key role to play in the signalling that takes place in plant cells. However, the sources of NO in plants has been hard to determine and there is considerable debate as to exactly how NO is made by plant cells. In animals nitric oxide synthase (NOS) enzymes have been characterised and such data has been used to inform the studies which have been taking place in plants. However, despite several genomes from higher plants being sequenced, there is no evidence that such species contain NOS sequences. Despite this, a recent search using algal sequences did reveal a NOS-like sequence and such a finding may spark new enthusiasm for the search for a higher plant NOS. However, considerable care needs to be taken in such studies, as the robustness of many of the inhibitors and probes which could be used in such work has been questioned. Here, some of the previous evidence that has been presented for the existence of a plant NOS, along with a discussion of how else plants may produce NO is given

Predictors of PM 2.5 and Radon Concentrations in Residences of Central Kentucky: A Cross Sectional Study

Aim: To measure levels of respirable particles (PM 2.5) and radon in homes in Central Kentucky and assess modifiable risk factors that could reduce the morbidity and mortality of cardiovascular and respiratory disease. Methods: PM 2.5 and radon samples were taken in homes (n=21) in Central Kentucky. An in- home checklist was completed for each home that assessed a variety of potential environmental respiratory exposures. Results: The geometric mean of PM 2.5 for all 21 homes was 8.4 μg/m3 which was well below the EPA air quality standard of 35 μg/m3. Smoking status, burning candles, and general cleanliness were statistically significant (P ≤ 0.05) variables in determining elevated PM 2.5 levels. General cleanliness was determined through assessing the amount of dust, animal hair and clutter. Number of pets was statistically significant (P ≤ 0.10) for PM 2.5 as well. None of the variables assessed for radon were statistically significant. Conclusion: Improving general cleanliness, reducing the number of candles burned, regularly grooming pets, and eliminating smoking in the home could reduce the amount of PM 2.5 in a home. This may be particularly important for people at risk of or who already have a respiratory disease. Prediction of radon levels based on home characteristics may be difficult due to the highly variable levels from home to home. All homeowners, especially those in regions where high levels of radon are known, should test their homes to determine if mitigation is needed. Although more research is needed to look at the association between PM 2.5 exposure and health outcomes in Central Kentucky, there are modifiable factors that may reduce the amount of PM 2.5 in homes

The mobile film van as a communications medium in environmental education

This paper describes an elementary evaluation of a mobile film van as a comnunications medium in the environmental education progranme of the National Parks Board of Bophuthatswana

Modelling the spread of Wolbachia in spatially heterogeneous environments

The endosymbiont Wolbachia infects a large number of insect species and is capable of rapid spread when introduced into a novel host population. The bacteria spread by manipulating their hosts' reproduction, and their dynamics are influenced by the demographic structure of the host population and patterns of contact between individuals. Reaction–diffusion models of the spatial spread of Wolbachia provide a simple analytical description of their spatial dynamics but do not account for significant details of host population dynamics. We develop a metapopulation model describing the spatial dynamics of Wolbachia in an age-structured host insect population regulated by juvenile density-dependent competition. The model produces similar dynamics to the reaction–diffusion model in the limiting case where the host's habitat quality is spatially homogeneous and Wolbachia has a small effect on host fitness. When habitat quality varies spatially, Wolbachia spread is usually much slower, and the conditions necessary for local invasion are strongly affected by immigration of insects from surrounding regions. Spread is most difficult when variation in habitat quality is spatially correlated. The results show that spatial variation in the density-dependent competition experienced by juvenile host insects can strongly affect the spread of Wolbachia infections, which is important to the use of Wolbachia to control insect vectors of human disease and other pests

Soft Manifold Dynamics Behind Negative Thermal Expansion

Minimal models are developed to examine the origin of large negative thermal expansion (NTE) in under-constrained systems. The dynamics of these models reveals how underconstraint can organize a thermodynamically extensive manifold of low-energy modes which not only drives NTE but extends across the Brillioun zone. Mixing of twist and translation in the eigenvectors of these modes, for which in ZrW2O8 there is evidence from infrared and neutron scattering measurements, emerges naturally in our model as a signature of the dynamics of underconstraint.Comment: 5 pages, 3 figure

Inelastic X-ray scattering from valence electrons near absorption edges of FeTe and TiSe2_2

We study resonant inelastic x-ray scattering (RIXS) peaks corresponding to low energy particle-hole excited states of metallic FeTe and semi-metallic TiSe$_2$ for photon incident energy tuned near the $L_{3}$ absorption edge of Fe and Ti respectively. We show that the cross section amplitudes are well described within a renormalization group theory where the effect of the core electrons is captured by effective dielectric functions expressed in terms of the the atomic scattering parameters $f_1$ of Fe and Ti. This method can be used to extract the dynamical structure factor from experimental RIXS spectra in metallic systems.Comment: 6 pages, 4 figure