OPTIMIZATION OF OVERHEAD IRRIGATION IN RELATION TO IRRIGATION WATER USE EFFICIENCY IN THE LOUISIANA NURSERY INDUSTRY

Irrigation efficiency is an essential component of nursery production in the United States. To increase productivity of Louisiana growers, a series of studies were conducted to evaluate current nursery water practices. The objectives were to determine current irrigation practices; evaluate actual water usage; and compare nursery media for water utilization. A mailed survey determined that the majority of growers used can yard production (63%), overhead irrigation (79%), had no irrigation manager (82%) and did not collect/reuse water(61%); 50% do not test/calibrate their irrigation system. Based on this information, five nurseries using overhead irrigation were selected to determine water application and the attributes of their potting media. These results indicated that overall, less water was being applied than perceived; localized irrigation was highly variable within a nursery and even within a single production yard. Irrigation within all nurseries averaged 0.29”/A of water and had a range of 0.37”/A. Within a single nursery a range from 0.17 to 0.53”/A was found between three different can yards. Within a single yard a range of 1.0”/A difference (0.5 to 1.5”) was found. Water holding capacity (WHC) for all evaluated nurseries were tested and determined that only 17% of nurseries fell within the target range of 45-65% WHC. Another 17% fell within 10% and the remaining 66% were greater than 10% from the target WHC. This information was used to evaluate water stress on two crops, Lantana x \u27Monine\u27 Spreading Sunshine® and Plectranthus scutellarioides \u27Alabama\u27, using three watering equivalents for acre inches: a low (0.5”) and standard (1.0”) and high (2.0”) watering treatment. This was conducted for 42 days and resulted in no significant differences in biomass for roots or shoots in coleus. However, lantana shoot biomass in the high water allocation was found to be statistically less than normal and low application for root biomass in the lower irrigation application where shown to be statistically lower than the 1.0 and 2.0 applications. Market quality decreased for 0.5 and 2.0 applications

Development of the Australian Ageing Semantic Differential AASD), a novel instrument for measurement of medical student attitudes towards older people

Attitudes of Australian medical students towards older people are important, as they can influence clinical practice. Initially I aimed to measure student attitude change after curriculum innovation. Literature review of Australian medical student attitudes revealed a gap for a valid, contemporary measure, inspiring the AASD. Review of international measures of student attitude identified semantic differential as the preferred instrument-type. A qualitative study of 151 medical students at the Universities of Wollongong (UOW) and Sydney (USYD) produced opposite word pairs for the AASD. The AASD was piloted at the University of New South Wales (UNSW), (n=140, response rate 77%). Removal of a redundant item pair resulted in a 19-item instrument (Cronbach’s α = 0.84). An AASD survey of New South Wales (NSW) medical students (n=321, response rate 72.6%) at UNSW, USYD, and UOW revealed: 1) A four-factor solution on exploratory factor analysis (Instrumentality (I), Personal Appeal (PA), Experience (E) and Sociability (S)), 2) No sequencing bias, 3) Cronbach’s α = 0.86, and 4) A positive mean AASD score (73.2/114), positive mean scores for three factors (PA, E and S) and negative mean I score. Female students had a significantly higher mean E score. Confirmatory factor analysis (CFA) demonstrated adequacy of fit for AASD survey data from outside NSW to our four-factor model. Melbourne University, University of Western Australia and University of Adelaide students (n=188, response rate 79%) had a mean AASD score (72.8/114) comparable to NSW data. The AASD is a reliable and generalisable instrument for measurement of Australian medical student attitudes towards older people, with face and structural validity. Deeper knowledge, within four factors of attitude, may be obtained from future medical education research employing the AASD

Suppression of allergic airway inflammation by helminth-induced regulatory T cells

Allergic diseases mediated by T helper type (Th) 2 cell immune responses are rising dramatically in most developed countries. Exaggerated Th2 cell reactivity could result, for example, from diminished exposure to Th1 cell–inducing microbial infections. Epidemiological studies, however, indicate that Th2 cell–stimulating helminth parasites may also counteract allergies, possibly by generating regulatory T cells which suppress both Th1 and Th2 arms of immunity. We therefore tested the ability of the Th2 cell–inducing gastrointestinal nematode Heligmosomoides polygyrus to influence experimentally induced airway allergy to ovalbumin and the house dust mite allergen Der p 1. Inflammatory cell infiltrates in the lung were suppressed in infected mice compared with uninfected controls. Suppression was reversed in mice treated with antibodies to CD25. Most notably, suppression was transferable with mesenteric lymph node cells (MLNC) from infected animals to uninfected sensitized mice, demonstrating that the effector phase was targeted. MLNC from infected animals contained elevated numbers of CD4(+)CD25(+)Foxp3(+) T cells, higher TGF-β expression, and produced strong interleukin (IL)-10 responses to parasite antigen. However, MLNC from IL-10–deficient animals transferred suppression to sensitized hosts, indicating that IL-10 is not the primary modulator of the allergic response. Suppression was associated with CD4(+) T cells from MLNC, with the CD4(+)CD25(+) marker defining the most active population. These data support the contention that helminth infections elicit a regulatory T cell population able to down-regulate allergen induced lung pathology in vivo

Mitochondria as a Potential Antifungal Target for Isocyanide Compounds

The discovery of antibiotics and antifungals greatly impacted medicine and human health, allowing the effective treatment of infections that were previously deadly. However, due to routine and sometimes excessive usage of these compounds, the development of antimicrobial resistance has created a need for new antibiotic and antifungal compounds. Isocyanide compounds have been shown to have antibacterial, antifungal, and anti-cancer properties, but very little is known about their biochemical effects. Our research aims to understand the mechanism of action of isocyanide compounds. We have conducted a genetic screen of a Saccharomyces gene-deletion (“knockout”) collection on media containing an easily synthesized model isocyanide compound, para-nitrophenyl isocyanide (p-NPIC). This allowed us to identify genes which, when deleted, render the mutant strains resistant or hypersensitive to the compound. Based on our genetic screen for hypersensitive mutants, we hypothesize that the isocyanides impact mitochondrial function, specifically altering the function of the Cu++-containing respiratory complex, Cytochrome C Oxidase (Complex IV). Our findings provide new information on the mechanism(s) of action of this class of antimicrobials and will help guide the development of new molecules based on lead-compounds such as p-NPIC

Role of Peptide Backbone Conformation on Biological Activity of Chemotactic Peptides

To investigate the role of peptide backbone conformation on the biological activity of chemotactic peptides, we synthesized a unique analog of N-formyl-Met-Leu-Phe-OH incorporating the C α,α disubstituted residue, dipropylglycine (Dpg) in place of Leu. The conformation of the stereochemically constrained Dpg analog was examined in the crystalline state by x-ray diffraction and in solution using NMR, IR, and CD methods. The secretagogue activity of the peptide on human neutrophils was determined and compared with that of a stereochemically constrained, folded type II β-turn analog incorporating 1-aminocyclohexanecarboxylic acid (Ac6c) at position 2 (f-Met- Ac6c -Phe-OMe), the parent peptide (f-Met-Leu-Phe-OH) and its methyl ester derivative (f-Met-Leu-Phe-OMe). In the solid state, the Dpg analog adopts an extended β-sheet-like structure with an intramolecular hydrogen bond between the NH and CO groups of the Dpg residue, thereby forming a fully extended (C5) conformation at position 2. The ϕ and ψ values for Met and Phe residues are significantly lower than the values expected for an ideal antiparallel beta conformation causing a twist in the extended backbone both at the N and C termini. Nuclear magnetic resonance studies suggest the presence of a significant population of the peptide molecules in an extended antiparallel β conformation and the involvement of Dpg NH in a C5 intramolecular hydrogen bond in solutions of deuterated chloroform and deuterated dimethyl sulfoxide. IR studies provide evidence for the presence of an intramolecular hydrogen bond in the molecule and the antiparallel extended conformation in chloroform solution. CD spectra in methanol, trifluoroethanol, and trimethyl phosphate indicate that the Dpg peptide shows slight conformational flexibility, whereas the folded Ac6c analog is quite rigid. The extended Dpg peptide consistently shows the highest activity in human peripheral blood neutrophils, being approximately 8 and 16 times more active than the parent peptide and the folded Ac6c analog, respectively. However, the finding that all four peptides have ED50 (the molar concentration of peptide to induce half-maximal enzyme release) values in the 10(-8)-10(-9) M range suggests that an induced fit mechanism may indeed be important in this ligand-receptor interaction. Moreover, it is also possible that alterations in the backbone conformation at the tripeptide level may not significantly alter the side chain topography and/or the accessibility of key functional groups important for interaction with the receptor

Quantifying uncertainty in pest risk maps and assessments : adopting a risk-averse decision maker’s perspective

Pest risk maps are important decision support tools when devising strategies to minimize introductions of invasive organisms and mitigate their impacts. When possible management responses to an invader include costly or socially sensitive activities, decision-makers tend to follow a more certain (i.e., risk-averse) course of action. We presented a new mapping technique that assesses pest invasion risk from the perspective of a risk-averse decision maker. We demonstrated the method by evaluating the likelihood that an invasive forest pest will be transported to one of the U.S. states or Canadian provinces in infested firewood by visitors to U.S. federal campgrounds. We tested the impact of the risk aversion assumption using distributions of plausible pest arrival scenarios generated with a geographically explicit model developed from data documenting camper travel across the study area. Next, we prioritized regions of high and low pest arrival risk via application of two stochastic ordering techniques that employed, respectively, first- and second-degree stochastic dominance rules, the latter of which incorporated the notion of risk aversion. We then identified regions in the study area where the pest risk value changed considerably after incorporating risk aversion. While both methods identified similar areas of highest and lowest risk, they differed in how they demarcated moderate-risk areas. In general, the second-order stochastic dominance method assigned lower risk rankings to moderate-risk areas. Overall, this new method offers a better strategy to deal with the uncertainty typically associated with risk assessments and provides a tractable way to incorporate decisionmaking preferences into final risk estimates, and thus helps to better align these estimates with particular decision-making scenarios about a pest organism of concern. Incorporation of risk aversion also helps prioritize the set of locations to target for inspections and outreach activities, which can be costly. Our results are especially important and useful given the huge number of camping trips that occur each year in the United States and Canada

Leading Transportation Indicators: Forecasting Waterborne Commerce Statistics Using Lock Performance Data

This paper develops and applies a forecasting model for transportation data based on the leading economic indicators literature. The specific application is to forecast river tonnages. Waterborne commerce data reflect tonnages of commodities moved on various rivers and in various directions. They are released after the Lock Performance Monitoring System data which reflect tonnages moving through specific locks. The model presented here forecasts waterborne commerce data from lock performance data. The results suggest that even a very simple model can provide precise forecasts

MODELLING THE COEFFICIENT OF VARIATION IN FACTORIAL EXPERIMENTS

The coefficient of variation (CV) has long been used as a measure of the relative consistency of sample data. However, little attention has been paid to using the CV to make conclusions about the relative consistency of the population(s) from which the data are drawn, particularly when the data are observed in the context of a designed factorial experiment. This research focused on using three approximations to the exact distribution of the sample CV of normally distributed data (McKay\u27s, David\u27s, and Iglewicz and Myers\u27) in the context of the generalized linear model to develop a method for detecting main effects and interactions among factors when the population characteristic of interest is the CV