Chemical characterisation of deep profile Ferrosols under sugarcane in wet tropical northern Queensland

The chemical properties of deep profile samples ( up to 12 m) of Ferrosols from northern Queensland were investigated to provide an understanding of the accumulation of nitrate ( NO3) within these soil profiles. The influence of other cations and anions present in the soil solution or on the exchange and the charge chemistry of the profiles were examined with respect to the NO3 accumulations. The major ions in the soil solution were Na, NO3, and chloride ( Cl). Distinct regions of anion accumulation were observed; SO4 accumulated in the upper profile of all cores, whereas NO3 and Cl accumulations were restricted to the lower profile of cores with appreciable AEC (> 1 cmol(c)/kg). Gaines-Thomas selectivity coefficients were used to indicate exchange preference for cations and anions, and are as follows: Al > Ca similar to Mg > K > Na and sulfate (SO4) > Cl similar to NO3. The selectivity of SO4 increased and the extractable SO4 decreased in the lower profile of all cores. This has important implications for the adsorption of NO3 and Cl. The NO3 and Cl accumulations were shown to correspond to a region of low SO4 occupancy of the exchange sites in the lower profile. Along with the high SO4 selectivity, this suggests that SO4 may control the positioning of the NO3 accumulations. It was concluded that the NO3 accumulations were relatively stable under current management practices, although the reduction in NO3 inputs would likely see the gradual replacement of NO3 with Cl as a result of their comparable selectivity for exchange sites.

Comparison of gelation profile of yoghurts during fermentation measured by RVA and ultrasonic spectroscopy

The gelation profile of yoghurts from conventionally treated (85 degrees C/30 min) and UHT treated (143 degrees C/6s) milks at 16, 18, and 20% total solids was analyzed during fermentation for 4 hrs using the invasive Rapid Visco Analyzer (RVA) and the non-invasive ultrasonic spectroscope. The viscosity measured by the RVA and the ultrasonic velocity measured by the ultrasonic spectroscope exhibited similar sigmoid trends with respect to fermentation time. The ultrasonic spectroscope detected the onset of gelation of yoghurt milk earlier (by an average of 52 min) than did the RVA, indicating a higher sensitivity of ultrasonic spectroscopy. The delay of gelation time of UHT-treated yoghurt milk as compared to conventionally treated yoghurt milk was detected by both techniques. A non-significant ( P > 0.05) effect of solids content in the yoghurt milks on their gelation time was also observed by both instruments.

Comparison of beam theory and finite-element analysis with in vivo bone strain data from the alligator cranium

The mechanical behavior of the vertebrate skull is often modeled using free-body analysis of simple geometric structures and, more recently, finite-element (FE) analysis. In this study, we compare experimentally collected in vivo bone strain orientations and magnitudes from the cranium of the American alligator with those extrapolated from a beam model and extracted from an FE model. The strain magnitudes predicted from beam and FE skull models bear little similarity to relative and absolute strain magnitudes recorded during in vivo biting experiments. However, quantitative differences between principal strain orientations extracted from the FE skull model and recorded during the in vivo experiments were smaller, and both generally matched expectations from the beam model. The differences in strain magnitude between the data sets may be attributable to the level of resolution of the models, the material properties used in the FE model, and the loading conditions (i.e., external forces and constraints). This study indicates that FE models and modeling of skulls as simple engineering structures may give a preliminary idea of how these structures are loaded, but whenever possible, modeling results should be verified with either in vitro or preferably in vivo testing, especially if precise knowledge of strain magnitudes is desired. (c) 2005 Wiley-Liss, Inc.

Use of latent profile analysis to identify eating disorder phenotypes in an adult Australian twin cohort

Context: The relationships among the different eating disorders that exist in the community are poorly understood, especially for residual disorders in which bingeing or purging occurs in the absence of other behaviors. Objective: To examine a community sample for the number of mutually exclusive weight and eating profiles. Design: Data regarding lifetime eating disorder symptoms and weight range were submitted to a latent profile analysis. Profiles were compared regarding personality, current eating and weight, retrospectively reported life events, and lifetime depressive psychopathology. Setting: Longitudinal study among female twins from the Australian Twin Registry in whom eating was assessed by a telephone interview. Participants: A community sample of 1002 twins (individuals) who had participated in earlier waves of data collection. Main Outcome Measures: Number and clinical character of latent profiles. Results: The best fit was a 5-profile solution with women who were (1) of normal weight with few lifetime eating disorders (4.3%), (2) overweight (10.6% had a lifetime eating disorder), (3) underweight and generally had no eating disorders except for 5.3% who had restricting anorexia nervosa, (4) of low to normal weight (89.0% had a lifetime eating disorder), and (5) obese (37.0% had a lifetime eating disorder). Each profile contained more than 1 type of lifetime eating disorder except for the third profile. Women in the first and third profiles had the best functioning, with women in the fourth and fifth profiles having similarly poorer functioning. The women in the fourth group had a symptom profile distinctive from the other 4 groups in terms of severity; they were also more likely to have had lifetime major depression and suicidality. Conclusion: Lifetime weight ranges and the severity of eating disorder symptoms affected clustering more than the type of eating disorder symptom.

Urinary arsenic speciation and porphyrins in C57B1/6J mice chronically exposed to low doses of sodium arsenate

Arsenic has been classified as a human carcinogen based on epidemiological data however the mechanism of its carcinogenicity is still unclear. Urinary biomarkers for chronic arsenic exposure would be valuable as an early warning indicator for timely interventions. In this study, young female C57BI/6J mice were given drinking water containing 0, 100, 250 and 500 mug As-v/L as sodium arsenate ad libitum for 12 months. Urine was collected bimonthly for urinary arsenic methylation assay and porphyrin analysis. All detectable arsenic species showed strong linear correlation with administered dosage and the arsenic methylation patterns were similar in all three treatment groups. No significant changes of methylation patterns were observed over time for either the control or test groups. Urinary coproporphyrin III was significantly increased in the 8th month in 250 and 500 mug/L groups and remained significantly dose-related after 10 and 12 months. Coproporphyrin I also showed a significant dose-response relationship after 12 months. Our results confirm that urinary arsenic is a useful biomarker for internal dose. The alteration of porphyrin profile suggests that arsenic can affect the heme metabolism and this may occur prior to the onset of arsenic induced carcinogenesis. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

The effect of ionic strength variation and anion competition on the development of nitrate accumulations in variable charge subsoils

The leaching of N fertilisers has led to the formation of nitrate (NO3) accumulations in deep subsoils (>5 m depth) of the Johnstone River catchment. This paper outlines the chemical mechanism by which these NO3 accumulations are formed and maintained. This was achieved via a series of column experiments designed to investigate NO3 leaching in relation to the soil charge chemistry and the competition of anions for exchange sites. The presence of variable charge minerals has led to the formation positive surface charge within these profiles. An increase in the soil solution ionic strength accompanying the fertiliser leaching front acts to increase the positive (and negative) charge density, thus providing adsorption sites for NO3. A decrease in the soil solution ionic strength occurs after the fertiliser pulse moves past a point in the profile, due to dilution with incoming rainwater. Nitrate is then released from the exchange back into the soil solution, thus buffering the decrease in the soil solution ionic strength. Since NO3 was adsorbed throughout the profile in this experiment it does not effectively explain the situation occurring in the field. Previous observations of the sulfate (SO4) profile distribution indicated that large SO4 accumulations in the upper profile may influence the NO3 distribution through competition for adsorption sites. A subsequent experiment investigating the effect of SO4 additions on NO3 leaching showed that NO3 adsorption was minimal in the upper profile. Adsorption of NO3 did occur, though only in the region of the profile where SO4 occupancy was low, i.e. in the lower profile. Therefore, the formation of the NO3 accumulations is dependent on the variable charge mineralogy, the variation of charge density with soil solution ionic strength, and the effects of SO4 competition for adsorption sites.

Laboratory-based simulation of freezing profiles of beef trim for Escherichia coli O157 survival determinations

This study was undertaken to develop a simple laboratory-based method for simulating the freezing profiles of beef trim so that their effect on E. coli 0157 survival could be better assessed. A commercially available apparatus of the type used for freezing embryos, together with an associated temperature logger and software, was used for this purpose with a -80 degrees C freezer as a heat sink. Four typical beef trim freezing profiles, of different starting temperatures or lengths, were selected and modelled as straight lines for ease of manipulation. A further theoretical profile with an extended freezing plateau was also developed. The laboratory-based setup worked well and the modelled freezing profiles fitted closely to the original data. No change in numbers of any of the strains was apparent for the three simulated profiles of different lengths starting at 25 degrees C. Slight but significant (P < 0.05) decreases in numbers (similar to 0.2 log cfu g(-1)) of all strains were apparent for a profile starting at 12 degrees C. A theoretical version of this profile with a freezing plateau phase extended from 11 h to 17 h resulted in significant (P < 0.05) decreases in numbers (similar to 1.2 log cfu g(-1)) of all strains. Results indicated possible avenues for future research in controlling this pathogen. The method developed in this study proved a useful and cost-effective way for simulating freezing profiles of beef trim. (c) 2005 Elsevier B.V. All rights reserved.

How many glomerular profiles must be measured to obtain reliable estimates of mean glomerular areas in human renal biopsies?

The objective of this study was to investigate the number of glomerular profiles that are required for accurate estimates of mean profile area in a renal biopsy series. Slides from 384 renal biopsies from one center were reviewed. They contained a median of seven glomerular profiles or of four profiles without sclerosis. Profile areas were measured using stereologic point counting. The true individual mean for each biopsy was calculated and the true population mean for groups of biopsies derived. Individual and population random sample means then were calculated from a random sampling of profiles in each biopsy and were compared with true means for the same biopsies. The effect on the true population means of the entire group of biopsies was also assessed, as the minimum number of glomerular profiles that were required for inclusion was changed. In a single biopsy, random sampling of >= 10 profiles without exclusions and of eight profiles or more without sclerosis reliably estimated the true mean areas. In a group of 30 biopsies, random sampling of five or more glomeruli per biopsy reliably estimated the true population mean. In the aggregate series, inclusion of all 384 biopsies produced the most robust true population mean; the reliability of the estimates decreased as the numbers of eligible biopsies diminished with increasing requisite minimum numbers of profiles per biopsy. We conclude that, while >= 10 profiles might be needed for reliable area estimates in a single biopsy, far fewer profiles per biopsy can suffice when groups of biopsies are studied. In analyses of groups of biopsies, all available biopsies should be used without consideration of the number of glomerular profiles in each. Stipulation of a specific minimum number of glomeruli in each biopsy for inclusion reduces the power of analyses because fewer biopsies are available for evaluation.

Dating paleochannel iron ore by (U-Th)/He analysis of supergene goethite, Hamersley province, Australia

(U-Th)/He dating of late-stage authigenic goethite, combined with corrections for diffusive loss of He-4 by the He-4/He-3 methodology, reveals strong correlation between a sample's age and its depth in ferruginized channel sediments from the Yandicoogina deposit, Western Australia. Corrected ages, ranging from ca. 18 Ma near the surface to ca. 5 Ma at the bottom of the profile, indicate that ferruginization of the aggraded channels becomes progressively younger with depth. This trend is consistent with goethite precipitation at the groundwater-atmosphere interface during water table drawdown driven by the aridification of Western Australia during the Neogene. The results demonstrate that the (U-Th)/He system is ideal for dating goethite if diffusive loss corrections are applied. The approach is suitable for dating weathering reactions on Earth and should also be suitable for dating Fe oxyhydroxides in the Martian regolith.

ASRIS: the database

The Australian Soil Resources Information System (ASRIS) database compiles the best publicly available information available across Commonwealth, State, and Territory agencies into a national database of soil profile data, digital soil and land resources maps, and climate, terrain, and lithology datasets. These datasets are described in detail in this paper. Most datasets are thematic grids that cover the intensively used agricultural zones in Australia.