Evaluation of dissipation kinetic models to describe trifluralin degradation in soil and assessing the uncertainty of the half-life estimate.

In Australia, trifluralin is one of the commonly used herbicides to manage annual grasses and some broadleaf weeds. However, it may have some ecosystem impacts such as high toxicity to terrestrial and aquatic life, so it is vital to monitor the degradation of trifluralin for a considerable period for environmental safety. For risk assessment purposes, it is necessary to estimate the half-life of trifluralin, which is often evaluated using derived mathematical dissipation models. In the literature, bi-exponential (BEXP) and gamma models were suggested for modelling the dissipation of trifluralin in soil. Both models provide the half-life estimate without discussing the uncertainty of the estimate, which is a shortcoming in the literature. In this paper, we used simulation to illustrate the importance of estimate's uncertainty (standard error) and demonstrated a method to compute the standard error for the half-life estimate mathematically for kinetic dissipation models. Later, we evaluated the performance of the two suggested models using statistical indices. The computation of the half-life and the standard error of the half-life estimate were discussed. This allows us to describe the inference of the half-life parameter and determine whether the half-life estimates are significantly different against the co-variate (moisture) levels. We demonstrated the method to calculate the standard error of the half-life of trifluralin, which allows us to determine the statistical difference between the estimates. In this study, we found that the half-life of trifluralin in soil tends to increase with increasing moisture levels, and the half-life of trifluralin in soil with 100% moisture level is significantly greater than 40% and 70% moisture levels. Our findings suggest that soil moisture levels should be carefully considered before trifluralin application to minimize the non-target environmental damage.

Computation of standard error for half-life estimation using various dissipation models for regulatory purposes.

Ecosystem including food chain may be modified over time because of the continued use of pesticides, piscicides including the use of veterinary antibiotics (VA) in agricultural, aquaculture and animal production. Regulatory authorities including government agencies have implemented various standard regulations across different parts of the world on the use of these products and monitoring the levels of these compounds in aquatic and soil environment has become an important aspect. Estimation of the half-life and reporting these values for regulatory authorities are paramount to safeguard human health and the environment. This was often determined based on the choice of best mathematical models, which is mainly dependent on the data quality. However, reporting the uncertainties associated with the estimation of standard errors is hitherto neglected. In this paper, we introduce a method how to compute the standard error of the half-life algebraically. Later, we provided some examples how to determine the standard error of the half-life numerically using previously published data and new data set, where appropriated mathematical models for the data have been also developed. The findings obtained in this study would allow one to gain information on the range of confidence interval for the half-life of compounds in soil or other media.

Genome-Wide Association Analyses Track Genomic Regions for Resistance to Ascochyta rabiei in Australian Chickpea Breeding Germplasm.

Ascochyta blight (AB), caused by a necrotrophic fungus, Ascochyta rabiei (syn. Phoma rabiei) has the potential to destroy the chickpea industry worldwide, due to limited sources of genetic resistance in the cultivated gene pool, high evolutionary potential of the pathogen and challenges with integrated disease management. Therefore, the deployment of stable genetic resistance in new cultivars could provide an effective disease control strategy. To investigate the genetic basis of AB resistance, genotyping-by-sequencing based DArTseq-single nucleotide polymorphism (SNP) marker data along with phenotypic data of 251 advanced breeding lines and chickpea cultivars were used to perform genome-wide association (GWAS) analysis. Host resistance was evaluated seven weeks after sowing using two highly aggressive single spore isolates (F17191-1 and TR9571) of A. rabiei. GWAS analyses based on single-locus and multi-locus mixed models and haplotyping trend regression identified twenty-six genomic regions on Ca1, Ca4, and Ca6 that showed significant association with resistance to AB. Two haplotype blocks (HB) on chromosome Ca1; HB5 (992178-1108145 bp), and HB8 (1886221-1976301 bp) were associated with resistance against both isolates. Nine HB on the chromosome, Ca4, spanning a large genomic region (14.9-56.6 Mbp) were also associated with resistance, confirming the role of this chromosome in providing resistance to AB. Furthermore, trait-marker associations in two F3 derived populations for resistance to TR9571 isolate at the seedling stage under glasshouse conditions were also validated. Eighty-nine significantly associated SNPs were located within candidate genes, including genes encoding for serine/threonine-protein kinase, Myb protein, quinone oxidoreductase, and calmodulin-binding protein all of which are implicated in disease resistance. Taken together, this study identifies valuable sources of genetic resistance, SNP markers and candidate genes underlying genomic regions associated with AB resistance which may enable chickpea breeding programs to make genetic gains via marker-assisted/genomic selection strategies.

Persistence of atrazine and trifluralin in a clay loam soil undergoing different temperature and moisture conditions.

Dissipation kinetics of atrazine and trifluralin in a clay loam soil was investigated in a laboratory incubation experiment under different temperature and moisture conditions. The soil was spiked with diluted atrazine and trifluralin concentrations at 4.50 and 4.25 mg/kg soil, respectively, the moisture content adjusted to 40, 70, and 100% of field capacity (FC) and then incubated in three climatic chambers at 10, 20, and 30 °C. For each of the herbicides, soil samples were collected at 0, 7, 21, 42, 70, and 105 days and analysed by Gas Chromatography-Electron Capture Detector (GC-ECD). A stochastic gamma model was used to model the dissipation of herbicides from the clay loam soil by incorporating environmental factors as covariates to determine half-life and days to complete dissipation. Results showed that temperature played a greater role on atrazine persistence than soil moisture; while the interaction effect of temperature and moisture was significant on the persistence of trifluralin over time. Atrazine dissipated more rapidly at 30 °C compared to 10 and 20 °C, with a half-life of 7.50 days and 326.23 days to reach complete dissipation. Rapid loss of trifluralin was observed at 70% moisture content when incubated at 30 °C, with a half-life of 5.80 days and 182.01 days to complete dissipation. It was observed that the half-life of both herbicides tended to double with every 10 °C decreases of temperature over the range tested. The model indicated that both atrazine and trifluralin have the potential to persist in clay loam soil for several years at temperature ≤20 °C; which could potentially affect following crops in rotation.

Unexpected increases in soil carbon eventually fell in low rainfall farming systems.

Understanding the drivers of soil organic carbon (SOC) change over time and confidence to predict changes in SOC are essential to the development and long-term viability of SOC trading schemes. This study investigated temporal changes in total SOC, total nitrogen (N), and carbon (C) fractions (particulate organic carbon - POC, resistant organic carbon - ROC and humus organic carbon - HOC) over a 16-year period for four contrasting farming systems in a low rainfall environment (424 mm) at Condobolin, Australia. The farming systems were 1) conventional tillage mixed farming (CT); 2) reduced tillage mixed farming (RT); 3) continuous cropping (CC); and 4) perennial pasture (PP). The SOC dynamics were also modelled using APSIM C and N modules, to determine the accuracy of this model. Results are presented in the context of land managers participating in Australian climate change mitigation schemes. There was an increase in SOC for all farming systems over the first 12 years (total organic C, TOC% at 0-10 cm increased from 1.33% to 1.77%), which was predominately in the POC% fraction (POC% at 0-10 cm increased from 0.14% to 0.5%). Between 2012 and 2015, there was a decrease in SOC back to starting levels (TOC = 1.22% POC = 0.12% at 0-10 cm) in all systems. The PP system had higher TOC%, POC% and HOC% levels on average and higher SOC stocks to 30 cm depth at the final measurement in 2015 (PP = 30.43 t C ha-1; cropping systems = 23.71 t C ha-1), compared to the other farming systems. There was a decrease in TN% over time in all farming systems except PP. The average C:N increased from 14.1 in 1999 to 19.7 in 2012, after which time the SOC levels decreased and C:N dropped back to 15.8. The temporal change in SOC was not able to be represented by the AusFarm model. There are three important conclusions for policy development: 1) monitoring temporal changes in SOC over 12 years did not indicate long-term sequestration, required to assure "permanence" in SOC trading (i.e. 25-100 years) due to the susceptibility of POC to degradation; 2) without monitoring SOC in reference land uses (e.g. CT cropping system as a control in this experiment) it is not possible to determine the net carbon sequestration, and therefore the true climate change mitigation value; and 3) modelling SOC using AusFarm/APSIM, does not fully represent the temporal dynamics of SOC in this low rainfall environment.

GWAS hints at pleiotropic roles for FLOWERING LOCUS T in flowering time and yield-related traits in canola.

BACKGROUND: Transition to flowering at the right time is critical for local adaptation and to maximize grain yield in crops. Canola is an important oilseed crop with extensive variation in flowering time among varieties. However, our understanding of underlying genes and their role in canola productivity is limited. RESULTS: We report our analyses of a diverse GWAS panel (300-368 accessions) of canola and identify SNPs that are significantly associated with variation in flowering time and response to photoperiod across multiple locations. We show that several of these associations map in the vicinity of FLOWERING LOCUS T (FT) paralogs and its known transcriptional regulators. Complementary QTL and eQTL mapping studies, conducted in an Australian doubled haploid population, also detected consistent genomic regions close to the FT paralogs associated with flowering time and yield-related traits. FT sequences vary between accessions. Expression levels of FT in plants grown in field (or under controlled environment cabinets) correlated with flowering time. We show that markers linked to the FT paralogs display association with variation in multiple traits including flowering time, plant emergence, shoot biomass and grain yield. CONCLUSIONS: Our findings suggest that FT paralogs not only control flowering time but also modulate yield-related productivity traits in canola.

Ultrasound Elastographic Measurement of Sciatic Nerve Displacement and Shear Strain During Active and Passive Knee Extension.

There is current need for objective measures of sciatic nerve mobility in patients with sciatic-type pain. The objective of the study was to assess the feasibility and reliability of ultrasound elastography to quantify sciatic nerve displacement and shear strain at the sciatic nerve-hamstring muscle interface during active and passive knee extension-flexion exercises performed while sitting in healthy people. Ultrasound elastography showed excellent intrarater within-session reliability for assessing sciatic nerve displacement and sciatic nerve-hamstring muscle interface shear strain during active knee extension-flexion exercises. These findings will inform similar future work conducted in patients with sciatic-type pain.

Use of a functional mobility measure to predict discharge destinations for patients admitted to an older adult rehabilitation ward: A feasibility study.

OBJECTIVE: To investigate whether the discharge destination for older adults can be predicted using functional mobility as measured by the Modified Elderly Mobility Scale (MEMS), associated with demographic and primary reason for admission variables. METHODS: A retrospective cohort population audit of 257 patients admitted and discharged from four tertiary older adult rehabilitation wards in a three-month period. A number of predictor variables were considered alongside the discharge destination. RESULTS: Multinomial statistical modelling established that MEMS prior to (P < 0.001), MEMS on completion (P = 0.009) of rehabilitation physiotherapy and primary reason for admission (P = 0.002) were significant variables to predict discharge destination. The model correctly predicted 71% of observed patient discharge destinations. CONCLUSION: The MEMS in conjunction with primary reason for admission was able to predict discharge destination with 71% accuracy in a heterogeneous population of older adults following rehabilitation.

Trend Analysis of 20 Years of FIM Road Racing Grand Prix Motorcycle World Championship.

PURPOSE: The technological advancements in motorcycle road racing have ensured the evolution of motorcycle performance; however, it is unknown whether these advancements have resulted in increased speed and therefore risk. To better understand the top level of this sport and inform future regulations, performance-related strategies, and safety procedures, this study aimed to (1) analyze and describe how the performance characteristics of the top class of the Fédération Internationale de Motocyclisme Grand Prix motorcycle world championship (GPWC) have changed with time and (2) quantify potential interactions between performance data (ie, crashes, speed, and environmental conditions). METHODS: Variables such as top 10 riders' speed of racing, crashes, starting position of winner, participants, and environmental conditions were collected from official race reports from 1997 to 2016. Data standardization was also ensured by including only dry competitions in the analysis. RESULTS: The mean racing speed ranged from a minimum of 155 (7.27) km·h-1 (year 2000) to a maximum of 165 (6.48) km·h-1 (year 2015). Linear mixed-model analysis revealed that the variables year and class significantly influenced changes in mean speed (faster racing). Per race, 12-14% of starters (95% confidence interval) suffered a crash. No significant associations were found between crashes and mean speed, ground temperature, air temperature, or air humidity. CONCLUSIONS: The speed of dry racing of the top class of the GPWC has increased over a 20-y span. Motorcycle circuit racing riders should consider the importance of being prepared to cope with crashing events to minimize chances of injury.

Categorisation of foot complaints in systemic lupus erythematosus (SLE) from a New Zealand cohort.

BACKGROUND: Foot complaints have been shown to be common in systemic lupus erythematosus (SLE) and heterogeneous in nature. We aimed to categorize self-reported foot complaints in people with SLE and foot symptoms. METHODS: A self-administered validated questionnaire was posted to 406 people with SLE attending adult rheumatology clinics across three health boards in Auckland, New Zealand. In addition to foot pain, vascular complaints, dermatological lesions and neurological symptoms were included in the analysis. Pairwise correlations among the variables were undertaken followed by factor analysis to identify and categorise associations between reported foot complaints. RESULTS: From the questionnaires returned, 93 full datasets were analysed. Participants' were predominantly female (n = 87, 93.7%), with mean (SD) age of 50.4 (14.3) years and a mean (SD) disease duration of 13.1 (11) years. Three categories of foot complaint were determined: 'foot pain', 'skin disorders' and 'vascular insufficiency'. These three groups provided the best fit (0.91) to describe the wide range of foot complaints reported by those with SLE. Factor analysis for foot pain demonstrated a high positive loading for the inter-correlation of foot pain in past month (0.83), foot pain today (0.71), intermittent claudication (0.71), numbness (0.62), loss of balance (0.81), swelling (0.59), foot joint pain (0.77), arch pain (0.68) and tendon pain (0.77). Skin disorders demonstrated a very high positive loading for 3 factors skin rash (0.82), blistering skin rash (0.95) and foot ulceration (0.88). In vascular insufficiency a high positive loading for cold feet (0.83), chilblains (0.76) and Raynaud's phenomenon (0.70). CONCLUSIONS: This work suggests people with SLE report three independent categories of foot complaints; foot pain, skin disorders or vascular insufficiency.

Participant Recruitment and Engagement in Automated eHealth Trial Registration: Challenges and Opportunities for Recruiting Women Who Experience Violence.

BACKGROUND: Automated eHealth Web-based research trials offer people an accessible, confidential opportunity to engage in research that matters to them. eHealth trials may be particularly useful for sensitive issues when seeking health care may be accompanied by shame and mistrust. Yet little is known about people's early engagement with eHealth trials, from recruitment to preintervention autoregistration processes. A recent randomized controlled trial that tested the effectiveness of an eHealth safety decision aid for New Zealand women in the general population who experienced intimate partner violence (isafe) provided the opportunity to examine recruitment and preintervention participant engagement with a fully automated Web-based registration process. The trial aimed to recruit 340 women within 24 months. OBJECTIVE: The objective of our study was to examine participant preintervention engagement and recruitment efficiency for the isafe trial, and to analyze dropout through the registration pathway, from recruitment to eligibility screening and consent, to completion of baseline measures. METHODS: In this case study, data collection sources included the trial recruitment log, Google Analytics reports, registration and program metadata, and costs. Analysis included a qualitative narrative of the recruitment experience and descriptive statistics of preintervention participant engagement and dropout rates. A Koyck model investigated the relationship between Web-based online marketing website advertisements (ads) and participant accrual. RESULTS: The isafe trial was launched on September 17, 2012. Placement of ads in an online classified advertising platform increased the average number of recruited participants per month from 2 to 25. Over the 23-month recruitment period, the registration website recorded 4176 unique visitors. Among 1003 women meeting eligibility criteria, 51.55% (517) consented to participate; among the 501 women who enrolled (consented, validated, and randomized), 412 (82.2%) were accrued (completed baseline assessments). The majority (n=52, 58%) of the 89 women who dropped out between enrollment and accrual never logged in to the allocated isafe website. Of every 4 accrued women, 3 (314/412, 76.2%) identified the classified ad as their referral source, followed by friends and family (52/412, 12.6%). Women recruited through a friend or relative were more likely to self-identify as indigenous Maori and live in the highest-deprivation areas. Ads increased the accrual rate by a factor of 74 (95% CI 49-112). CONCLUSIONS: Print advertisements, website links, and networking were costly and inefficient methods for recruiting participants to a Web-based eHealth trial. Researchers are advised to limit their recruitment efforts to Web-based online marketplace and classified advertising platforms, as in the isafe case, or to social media. Online classified advertising in "Jobs-Other-volunteers" successfully recruited a diverse sample of women experiencing intimate partner violence. Preintervention recruitment data provide critical information to inform future research and critical analysis of Web-based eHealth trials. CLINICALTRIAL: Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12612000708853; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12612000708853 (Archived by WebCite at http://www.webcitation/6lMGuVXdK).

Patterns of foot complaints in systemic lupus erythematosus: a cross sectional survey.

BACKGROUND: Foot complaints are common in inflammatory arthropathies such as rheumatoid arthritis and cause considerable disability. However, little is published about the nature and extent of foot complaints in systemic lupus erythematosus (SLE). We aimed to explore foot complaints among people with (SLE) and to evaluate the associations between foot pain and self-reported activities of daily living and well-being. METHODS: We developed and tested a new 40-item item self-administered questionnaire, using a five-stage development process utilising patient involvement throughout to ensure face and content validity. The self-administered instrument was posted to 406 people with SLE attending adult rheumatology clinics across three health boards in Auckland, New Zealand. The questionnaire enquired about symptoms of foot pain, extra-articular features, anatomical distribution of symptoms according to validated foot-mannequins and the impact of foot symptoms on activities of daily living and well-being. RESULTS: In total, 406 questionnaires were posted, with 131 responses (response rate 32 %). We found 89 % were women, mean (SD) age 51 (15) years, mean (SD) diagnosis 12.5 (11.1) years. Overall, 77 % of those responding to the questionnaire reported foot pain during their SLE, with 45 % reporting current foot pain. All regions of the feet were affected, with the hindfoot (32 %) and ankles (30 %) most troublesome. The most common self-reported extra-articular foot complaints were cold feet, swelling and numbness. Almost two-thirds (61 %) reported foot pain adversely affected their lives; foot pain prevented sleeping in 36 % and had a negative effect on emotions for 33 %. Only 33 % of participants had seen a podiatrist. Significant association was found between foot pain and standing longer than 15 min (p < 0.001), walking (p < 0.001), climbing stairs (p < 0.001) and going shopping (p < 0.001). Pain was the primary symptom to affect quality of life (47/100). CONCLUSION: Foot complaints in SLE are heterogeneous in nature, and may have a substantial negative impact on patient well-being. Foot complaints need to be addressed to reduce the burden of SLE and our findings support the need for wider access to specific foot care services.

Using gamma distribution to determine half-life of rotenone, applied in freshwater.

Following the use of rotenone to eradicate invasive pest fish, a dynamic first-order kinetic model is usually used to determine the half-life and rate at which rotenone dissipated from the treated waterbody. In this study, we investigate the use of a stochastic gamma model for determining the half-life and rate at which rotenone dissipates from waterbodies. The first-order kinetic and gamma models produced similar values for the half-life (4.45 days and 5.33 days respectively) and days to complete dissipation (51.2 days and 52.48 days respectively). However, the gamma model fitted the data better and was more flexible than the first-order kinetic model, allowing us to use covariates and to predict a possible range for the half-life of rotenone. These benefits are particularly important when examining the influence that different environmental factors have on rotenone dissipation and when trying to predict the rate at which rotenone will dissipate during future operations. We therefore recommend that in future the gamma distribution model is used when calculating the half-life of rotenone in preference to the dynamic first-order kinetics model.

Deriving sulfamethoxazole dissipation endpoints in pasture soils using first order and biphasic kinetic models.

Single first-order (SFO) kinetic model is often used to derive the dissipation endpoints of an organic chemical in soil. This model is used due to its simplicity and requirement by regulatory agencies. However, using the SFO model for all types of decay pattern could lead to under- or overestimation of dissipation endpoints when the deviation from first-order is significant. In this study the performance of three biphasic kinetic models - bi-exponential decay (BEXP), first-order double exponential decay (FODED), and first-order two-compartment (FOTC) models was evaluated using dissipation datasets of sulfamethoxazole (SMO) antibiotic in three different soils under varying concentration, depth, temperature, and sterile conditions. Corresponding 50% (DT50) and 90% (DT90) dissipation times for the antibiotics were numerically obtained and compared against those obtained using the SFO model. The fit of each model to the measured values was evaluated based on an array of statistical measures such as coefficient of determination (R(2)adj), root mean square error (RMSE), chi-square (χ(2)) test at 1% significance, Bayesian Information Criteria (BIC) and % model error. Box-whisker residual plots were also used to compare the performance of each model to the measured datasets. The antibiotic dissipation was successfully predicted by all four models. However, the nonlinear biphasic models improved the goodness-of-fit parameters for all datasets. Deviations from datasets were also often less evident with the biphasic models. The fits of FOTC and FODED models for SMO dissipation datasets were identical in most cases, and were found to be superior to the BEXP model. Among the biphasic models, the FOTC model was found to be the most suitable for obtaining the endpoints and could provide a mechanistic explanation for SMO dissipation in the soils.

Evaluation of four mathematical models to describe dissipation kinetics of 4-n-nonylphenol and bisphenol-A in groundwater-aquifer material slurry.

The performance of four mathematical models (hockey stick, biexponential, first-order double exponential decay, and first-order two-compartment) was evaluated to describe the dissipation kinetics for 4-n-nonylphenol (4-n-NP) and bisphenol-A (BPA) in groundwater-aquifer material slurry under aerobic and anaerobic conditions conducted under controlled laboratory conditions. The fit of each model to the measured values under both conditions was tested using an array of statistical indices to judge the model's ability to fit the measured datasets. Corresponding 50% (DT(50)) and 90% (DT(90)) dissipation values for each compound were numerically obtained and compared against each model. The model derived DT(50) values in groundwater-aquifer material ranged from 1.06 to 1.24 (4-n-NP) and 0.341 to 0.568 days (BPA) under aerobic condition, while they were 2- to 4-fold higher under anoxic condition. DT(90) values for 4-n-NP ranged anywhere between 2.3 and 4.45 days under both conditions, while DT(90) values for BPA ranged from around 1 day to as high as 12 days under both conditions tested. A visual examination of the measured and fitted plots as well as the statistical indices showed that, with the exception of the hockey stick model, the models performed satisfactorily. Despite having only 3 parameters, the biexponential model could describe the dissipation kinetics very well and this was supported by the statistical indices generated for each case.