Comparing critical speed modelling approaches and exploring relationships with match-play variables in elite male youth soccer players.

Background: A novel bi-exponential method has emerged to estimate critical speed (CS) and D-prime (D') from a 3-min all-out test (3MT). Objectives: To compare CS analysis methods to determine whether parameter estimations were interchangeable. Reference values and relationships with key soccer match-play variables were explored. Methods: Thirteen elite male youth (14-15 years old) players completed a 30 m shuttle run 3MT to estimate CS, D', rate of speed decline time constant, maximal speed (S max), time to S max (t max), and fatigue index (FI), using the traditional method and bi-exponential model on average (Bi-ExpAverage) and max speed settings (Bi-ExpMax-Speed). High-speed running (HSR) and sprinting distances and counts, and the number of accelerations were collected from two matches. Magnitude-based inferences (p < 0.05) with smallest worthwhile change of 0.2 effect sizes were used to analyse differences. Pearson's and Spearman's correlation coefficients were used to measure associations between CS model variables and match-play parameters. Results: There were significant differences between the traditional method and both bi-exponential models for CS and D', as well as between the bi-exponential models for all variables except t max. Using the Bi-ExpAverage model, strong correlations (r = 0.70-0.73; p < 0.05) were observed for D' and FI with the number of standardised and individualised HSRs, respectively. With the Bi-ExpMax-Speed model, there were strong correlations (r/ρ = 0.64-0.68; p < 0.05) between D' and the number of standardised HSRs and sprints, and the number of individualised sprints. Conclusion: There is a lack of interchangeability between analysis methods. It appears that D' and FI from the bi-exponential models could be associated with high-intensity actions in soccer match-play.

Acceptability of a new practice development for radiographers focussed on reducing 'never events' related to nasogastric feeding tubes in adult patients.

INTRODUCTION: Ascertain if a new practice development designed to reduce 'never events' from feeding through misplaced nasogastric tubes (NGT) in a large teaching hospital Trust was acceptable to a large radiography workforce. METHODS: Despite National Patient Safety Agency guidance advising on safe practice for confirming position of NGTs a number of 'never events' still occur nationally due to misinterpretation of the check X-ray. A new practice development for radiographers included providing an immediate comment and removal of misplaced NGTs at the time of the check X-ray examination. Success of the new system was partly assessed using qualitative and quantitative measures of radiographer opinion of the training and different aspects of the system. RESULTS: There was a significant improvement in radiographers' level of confidence in image interpretation after training (58/98 positive responses before, 89/98 positive after training) and after five months of experience at undertaking the role (96/98 positive) (p < 0.01). There was increased confidence in NGT removal post training and with five months of experience (16/95 positive before training, 67/96 positive after and 81/95 positive with five months of experience). 97/98 (99%) of radiographers agreed the new system benefits patients, 93/98 (95%) believed it a positive step for the radiography profession. CONCLUSION: Evaluation of this new practice development has shown it was embraced by radiographers and is a workable and potentially cost-effective solution in addressing real time image interpretation issues that were evident from previous 'never events'. Large scale implementation of this system across the NHS Radiography workforce should be considered.

Radiographer workforce role expansion to improve patient safety related to nasogastric tube placement for feeding in adults.

AIM: To determine whether the active involvement of radiographers in nasogastric tube (NGT) management at a large multisite healthcare institution can contribute to risk reduction regarding feeding through misplaced NGTs. MATERIALS AND METHODS: Despite national guidance in the National Health Service advising on safe practice to confirm NGT position, a number of "never events" (feeding through misplaced NGT) continue to occur due to misinterpretation of the check radiograph. Practice change was introduced, including all plain film radiographers providing contemporaneous comments on NGT position on the check radiograph. The success of the system was assessed to determine the accuracy of radiographer comments against the reference standard of the radiologist report to see whether the system has helped reduce the number of "never events". RESULTS: During the first 27 months post-implementation, 4,675 check NGT radiography examinations were analysed. Two hundred and twenty-seven examinations were excluded due to absent or incomplete radiographer comments. The accuracy of the radiographer comments was 98.5% (95% confidence interval [CI]: 97.7-99.5%), sensitivity 97.4% (95% CI: 96.3-98.3%), specificity 98.9% (95% CI: 98.5-99.2%), positive predictive value 96.8% (95% CI: 95.6-97.7%), and negative predictive value 99.1% (95% CI: 98.8-99.4%). CONCLUSION: After focused training, radiographer comments are a safe, sustainable, and workable solution offering an effective solution for image misinterpretation issues relating to NGT "never events". This should be considered for wider implementation in healthcare.

Quantifying surface modification events from scanning force microscopy images.

Scanning force microscopy (SFM) is widely used to monitor surfaces and surface modification processes. Some surface modification processes involve the addition (or removal) of discrete entities to (or from) a surface in circumstances where the absolute number of entities is related to some aspect of the process. A two-dimensional surface characterisation parameter - the surface area ratio (SAR) - was previously developed as a means of quantifying such modification and can be readily obtained from SFM images. Simulations have shown that the SAR parameter is superior for quantification purposes to conventional surface roughness parameters such as roughness average S(a), the area equivalent of R(a). Key features of SAR are as follows: its linear dependence with coverage; dependence of linearity slope on coverage mechanism; and its independence from the form, waviness or roughness of the underlying surface. A further advantage of this method is its simplicity given that the SAR parameter is readily obtained from SFM images. Simulations of adsorption onto flat surfaces have been validated using SFM images of polystyrene spheres adsorbed onto mica.

Time-resolved XANES speciation studies of chromium on soils during simulated contamination.

Time-resolved synchrotron X-ray absorption near edge structure (XANES) spectroscopy was used to study changes of chromium speciation in soils upon soil-water interaction. The time resolution was 30-45 min. In a flow-column apparatus operated near the synchrotron beamline, two different types of soil were treated with potassium-dichromate solution, and soil samples were taken and directly analysed by XANES. The results provide insight into different equilibrium times of a few hours, depending on the type of soil. The XANES speciation analyses, based on a model comprising insoluble Cr(III) and Cr(VI) compounds, show how the fate of Cr species on soils can be followed close to real-time. Since the method allowed the soils to be investigated close to real-time, sampling in the field and preservation before analysis were made redundant. This study benefits the development of corresponding in situ remediation techniques.

Improving immunoassays based on the analysis of scanning force microscopy images.

Scanning force microscopy has been demonstrated to be an effective binding event detection step for immunoassays. In its simplest form--analysing small area images--the detection limit of the scanning force microscopic immunoassay (SFMIA) has been shown to be comparable to existing techniques. In the present work, we have examined how the performance of image analysis-based SFMIA can be improved. Firstly, we have used a surface analysis parameter that increases linearly with the concentration of binding events. This parameter--the surface area ratio--is the ratio of the surface area after antigen binding to the surface area of the original biospecific surface. With this parameter, SFMIA images can be rapidly analysed and converted into assay units. Secondly, we have demonstrated that by using silicon wafer supports that carry fiducial marks we can relocate to very high accuracy onto the biospecific surfaces and identify the changes due to antigen binding. By relocating in this manner the signal to noise ratio of the technique is enhanced. Thirdly, from simulations we have determined the SFM tip size and image area that optimizes the immunoassay sensitivity.

A method for measuring the size distribution of latex particles by scanning force microscopy.

A methodology has been developed to accurately determine the size distribution of latex particles using the scanning force microscope (SFM). Unlike other workers, who have generally measured the lateral dimensions of monolayers of latex particles using a global quantification method, we have measured the heights of individual latex particles located at the edges of latex monolayers that were immobilised onto mica substrates. In agreement with other work, we noted that the edges of monolayers of latex particles provided stable and reproducible scanning force imaging. Whilst SFM imaging noise, image processing artifacts, tip/sample forces and variations in the mica substrate are sources of measurement error that should not be overlooked, our experience has been that the variation over time of the sensitivity of the Z actuator is the greatest potential uncertainty in determining the heights of latex particles. The methodology that we used requires frequent calibration of the Z actuator of the SFM, typically before and after two or three images, in order to ensure that the uncertainties in the Z sensitivity are known and minimised. This methodology was developed for an SFM instrument that was equipped with open loop piezoelectric actuators following a careful study of the behaviour of those actuators. Using this methodology, we have measured the size distributions of populations of 300-400 latex particles from each of several different latex samples, with the maximum variation in the Z-actuator calibration experienced during the measurement of a sample being less than 2%, often about 1% and occasionally better still. In so doing, we have demonstrated that SFMs equipped with open loop actuators can be used for high confidence quantitative measurements of step heights.

Inhaled nitric oxide prevents pulmonary endothelial dysfunction after mesenteric ischemia-reperfusion.

This study examined the effect of inhaled nitric oxide (NO) on lung neutrophil accumulation and endothelial-dependent and -independent guanosine 3',5'-cyclic monophosphate (cGMP)-mediated mechanisms of pulmonary vasorelaxation after mesenteric ischemia-reperfusion (I/R) in mechanically ventilated rats. Inhaled NO (20 ppm) was administered in two protocols: 1) throughout mesenteric I/R and 2) during mesenteric reperfusion alone. Concentration-response curves were generated (10(-9) to 10(-8) M) for acetylcho-line (ACh), A23187, and sodium nitroprusside (SNP) in isolated pulmonary arterial rings preconstricted with phenylephrine. Lung neutrophil accumulation [myeloperoxidase assay (MPO)] was significantly increased from 2.4 +/- 0.2 units/g lung wt in controls to 10.3 +/- 0.4 after 1 h of superior mesenteric artery occlusion and 2 h of reperfusion. Lung MPO activity was not different from controls in rats receiving inhaled NO either 1) during mesenteric I/R or during mesenteric reperfusion alone. The concentration-response curves demonstrated significant impairment of pulmonary vasorelaxation by endothelial-dependent mechanisms (response to ACh and A23187) but not endothelial-independent pulmonary vasorelaxation (response to SNP) after mesenteric I/R. This pulmonary vasomotor dysfunction was prevented by administration of inhaled NO during either mesenteric I/R or during mesenteric reperfusion alone. We conclude that inhaled NO prevents lung neutrophil accumulation and pulmonary vascular endothelial dysfunction after mesenteric I/R.

Hydroxychloroquine, dosage parameters and retinopathy.

In a study designed to determine the presence of retinopathy in patients taking hydroxychloroquine we compared 82 patients attending a rheumatology clinic who had taken hydroxychloroquine for over 1 year with controls. Outcome measurements included fundoscopy, fundus photography and automated computerized visual fields of the macular area. No patient was found to have retinopathy. No correlation could be found between indices of visual field function and total drug usage, average daily dose, dosage in mg/kg body weight or duration of treatment. Retinopathy is unlikely to occur at dosages of hydroxychloroquine of less than 6.5 mg/kg body weight with under 10 years of treatment. Present guidelines for ophthalmic screening of patients on antimalarial therapy are too rigorous and visual field testing if not of benefit. Further recommendations are made for ophthalmic supervision.

The Eker renal tumor rat. General immune status in relation to a varying tumor burden.

Evidence was obtained that the response of blood lymphocytes to phytohemagglutinin was reduced in some but not all rats with massive hereditary renal tumors (less than 50 mm mean diameter). Erythrocyte-antibody sensitized, complement dependent (EAC) rosette formation by sensitized spleen cells was also depressed in these animals, but plaque forming cell activity was essentially normal. Lesser tumor growth was associated with general cell-mediated and humoral immune responses which were within the range found for non-tumor-bearing syngeneic rats.