Evaluation of maize cultivars for their susceptibility towards mycotoxigenic fungi under storage conditions

Maize cultivation comprises the largest area of farmland in South Africa and it is the largest food crop consumed by the majority of its population. However, this food crop is frequently associated with mycotoxin contamination. Mycotoxigenic fungi that are regularly found in South African maize were selected and evaluated against 49 commercially produced maize cultivars for their ability to infest maize during storage. Four of these fungi, known to contaminate maize in the field included Fusarium graminearum, Fusarium verticillioides, Phoma sorghina and Stenocarpella maydis. The other five species included storage fungi such as Aspergillus flavus, Aspergillus ochraceus, Eurotium repens, Penicillium islandicum and Rhizopus oryzae. A unique method of inoculation was carried out where each maize cultivar was serially inoculated with each of the fungi. Results showed that four maize cultivars had a slower rate of infestation towards the field fungi while three cultivars had a slower rate of infestation towards the storage fungi. Only one of the maize cultivars, PAN 6146, showed an overall slower infestation rate for both field and storage fungi.     

Formalizing dimension and response violations of local independence in the unidimensional Rasch model

Local independence in the Rasch model can be violated in two generic ways that are generally not distinguished clearly in the literature. In this paper we distinguish between a violation of unidimensionality, which we call trait dependence, and a specific violation of statistical independence, which we call response dependence, both of which violate local independence. Distinct algebraic formulations for trait and response dependence are developed as violations of the dichotomous Rasch model, data are simulated with varying degrees of dependence according to these formulations, and then analysed according to the Rasch model assuming no violations. Relative to the case of no violation it is shown that trait and response dependence result in opposite effects on the unit of scale as manifested in the range and standard deviation of the scale and the standard deviation of person locations. In the case of trait dependence the scale is reduced; in the case of response dependence it is increased. Again, relative to the case of no violation, the two violations also have opposite effects on the person separation index (analogous to Cronbach's alpha reliability index of traditional test theory in value and construction): it decreases for data with trait dependence; it increases for data with response dependence. A standard way of accounting for dependence is to combine the dependent items into a higher-order polytomous item. This typically results in a decreased person separation index index and Cronbach's alpha, compared with analysing items as discrete, independent items. This occurs irrespective of the kind of dependence in the data, and so further contributes to the two violations not being distinguished clearly. In an attempt to begin to distinguish between them statistically this paper articulates the opposite effects of these two violations in the dichotomous Rasch model.     

GNSS accuracy enhancement based on pseudo range error estimation in an urban propagation environment

For new ITS applications, positioning solutions will require to be more accurate and available. The most common technique used today is composed of a GPS receiver, sometimes aided by other sensors. GPS, and GNSS in general, suffer from masking effects and propagation disturbances in urban areas that cause biases on pseudo range measurements. Mitigation solutions sometimes propose to detect and exclude outliers but in land transportation applications, such a decision reduces dramatically the service availability and thus, the interest of satellite-based solutions. In order to optimize the use the satellites received, we propose a new positioning algorithm based on signals only with pseudo range error modeling in association with an adapted filtering process. The model and the filter have been validated with simulation data performed along an urban bus line and have shown that both positioning error and availability can be improved. Along the trajectory tested, the mean accuracy has been reduced from 5.3 m with a classical filter to 2.6 m with our algorithm with 89% of the points more accurate than 5 m instead of 64% before.     

Transonic,thermodilution, or ionic dialysance to manage vascular access: Which method is best?

Regularly monitoring blood flow through a vascular access (Qa) can predict a dysfunction and dramatically reduce the number of thromboses. The aim of our study was to compare two integrated access flow devices, thermodilution (Qa‐BTM: BTM®, Fresenius Medical Care, Bad Homburg, Germany) and ionic dialysance (Qa‐ID: OCM®, Fresenius Medical Care, Bad Homburg, Germany), with the “gold standard” saline dilution (Qa‐T: Transonic®, Systems Inc., Ithaca, NY, USA). Measurements were performed sequentially and were repeated in the first 90 minutes of a single dialysis session in 24 long‐term hemodialysis patients with a vascular access. Bland–Altman, linear regression (r²), and intraclass correlation coefficients (ICC) assessed reproducibility, correlations, and concordance between the techniques. Average access flow for Qa‐T was 1549 (± 844) mL/minute, Qa‐BTM was 1530 (± 856) mL/minute (P = NS), and Qa‐ID was 1619 (± 1085) mL/minute (P = NS). Respectively, ICC, (r²), and bias were 0.99, (0.98), and ?19 mL/minute for Qa‐BTM, and 0.75, (0.65), and +69 mL/minute for Qa‐ID. The limits of agreement were ?287 to +250 mL/minute for Qa‐BTM and ?1647 to +1785 mL/minute for Qa‐ID. Reproducibility of thermodilution and ionic dialysance, expressed as relative differences, was not significantly different from saline dilution. Recirculation, measured by saline dilution, was 0% (0–4%), the same as the 0% measured by thermodilution, with correct placement of bloodlines and corrected for cardiopulmonary recirculation. The integrated access flow measurement devices, thermodilution and ionic dialysance, are reasonable alternatives to using saline dilution to measure Qa: Thermodilution showed better precision and correlation. They are reliable, make monitoring of vascular access easier, incur no extra costs, and use no additional consumables.     

Pharmacokinetics of triptorelin after intravenous bolus administration in healthy males and in males with renal or hepatic insufficiency

PURPOSE: The aim of the present study was to validate a simple MRI-procedure for semiquantitative assessment of regional cerebral blood flow. MATERIALS AND METHODS: Unilateral cerebral ischaemia (30 minutes) in the territory of the middle cerebral artery was induced in 14 anesthetised rates. The MRI-experiment consisted in an intravenous bolus injection of gadolinium-DTPA, recording of the cerebral contrast kinetics with a T2*-weighted pulse sequence, and measurement of the maximal concentration change at a chosen reference point of time. To measure perfusion quantitatively, a microsphere technique, an accepted reference technique was used. With both methods a perfusion index related to the contralateral side was calculated. RESULTS: In all cases decreased perfusion was detected by the MRI technique. The perfusion indices correlated with a coefficient of correlation of r = 0.89 (p < 0.001). CONCLUSION: The results demonstrate that contrast-enhanced MRI with bolus injection can be implemented with clinical potential as a semiquantitative instrument for the assessment of cerebral perfusion. Regional cerebral blood volume and collateral blood flow may interfere with the estimate of blood flow.