Rapid detection of Staphylococcus aureus strains with reduced susceptibility to vancomycin by isothermal microcalorimetry.

Methicillin-resistant Staphylococcus aureus (MRSA) usually harbors a vancomycin-susceptible phenotype (VSSA) but can exhibit reduced vancomycin susceptibility phenotypes that can be heterogeneous-intermediate (hVISA), intermediate (VISA), or fully resistant (VRSA). Current detection techniques (e.g., Etest and population analysis profiles [PAPs]) are slow and time-consuming. We investigated the potential of microcalorimetry to detect reduced susceptibilities to vancomycin in MRSA strains. Representative MSSA, VSSA, hVISA, VISA, and VRSA reference strains, as well as clinical isolates, were used. PAPs were performed by standard methods. Microcalorimetry was performed by inoculating 5 × 10(7) CFU of overnight cultures into 3-ml vials of brain heart infusion broth supplemented with increasing concentrations of vancomycin, and growth-related heat production was measured at 37°C. For the reference strains, no heat production was detected in the VSSA isolates at vancomycin concentrations of >3 μg/ml during the 72 h of incubation. The hVISA and VISA strains showed heat production with concentration-proportional delays of up to 6 μg/ml in 48 h and up to 12 μg/ml in 72 h, respectively. The VRSA strain showed heat production at concentrations up to 16 μg/ml in 12 h. The testing of clinical strains indicated an excellent negative predictive value, allowing us to rule out a decreased vancomycin susceptibility phenotype in <8 h of incubation. Sequential isolates from a patient undergoing vancomycin therapy showed evolving microcalorimetric profiles up to a VISA phenotype. Microcalorimetry was able to detect strains with reduced susceptibilities to vancomycin in <8 h. The measurement of bacterial heat production might represent a simple and rapid method for the detection of reduced susceptibilities to vancomycin in MRSA strains.

Improvement of cardiovascular risk prediction: time to review current knowledge, debates, and fundamentals on how to assess test characteristics.

Cardiovascular risk assessment might be improved with the addition of emerging, new tests derived from atherosclerosis imaging, laboratory tests or functional tests. This article reviews relative risk, odds ratios, receiver-operating curves, posttest risk calculations based on likelihood ratios, the net reclassification improvement and integrated discrimination. This serves to determine whether a new test has an added clinical value on top of conventional risk testing and how this can be verified statistically. Two clinically meaningful examples serve to illustrate novel approaches. This work serves as a review and basic work for the development of new guidelines on cardiovascular risk prediction, taking into account emerging tests, to be proposed by members of the 'Taskforce on Vascular Risk Prediction' under the auspices of the Working Group 'Swiss Atherosclerosis' of the Swiss Society of Cardiology in the future.

Designing and testing of a sensor based on a magnetoresistive manganese perovskite thick film

In this paper we report on the growth of thick films of magnetoresistive La2/3Sr1/3MnO3 by using spray and screen printing techniques on various substrates (Al2O3 and ZrO2). The growth conditions are explored in order to optimize the microstructure of the films. The films display a room-temperature magnetoresistance of 0.0012%/Oe in the 1 kOe field region. A magnetic sensor is described and tested.

HIV testing in Switzerland.

OBJECTIVES: To obtain information about the prevalence of, reasons for, and adequacy of HIV testing in the general population in Switzerland in 1992. DESIGN: Telephone survey (n = 2800). RESULTS: Some 47% of the sample underwent one HIV test performed through blood donation (24%), voluntary testing (17%) or both (6%). Of the sample, 46% considered themselves well or very well informed about the HIV test. Patients reported unsystematic pre-test screening by doctors for the main HIV risks. People having been in situations of potential exposure to risk were more likely to have had the test than others. Overall, 85% of those HIV-tested had a relevant, generally risk-related reason for having it performed. CONCLUSIONS: HIV testing is widespread in Switzerland. Testing is mostly performed for relevant reasons. Pre-test counselling is poor and an opportunity for prevention is thus lost.

Looking for Validity or Testing It? The Perils of Stepwise Regression, Extreme-Scores Analysis, Heteroscedasticity, and Measurement Error

When researchers introduce a new test they have to demonstrate that it is valid, using unbiased designs and suitable statistical procedures. In this article we use Monte Carlo analyses to highlight how incorrect statistical procedures (i.e., stepwise regression, extreme scores analyses) or ignoring regression assumptions (e.g., heteroscedasticity) contribute to wrong validity estimates. Beyond these demonstrations, and as an example, we re-examined the results reported by Warwick, Nettelbeck, and Ward (2010) concerning the validity of the Ability Emotional Intelligence Measure (AEIM). Warwick et al. used the wrong statistical procedures to conclude that the AEIM was incrementally valid beyond intelligence and personality traits in predicting various outcomes. In our re-analysis, we found that the reliability-corrected multiple correlation of their measures with personality and intelligence was up to .69. Using robust statistical procedures and appropriate controls, we also found that the AEIM did not predict incremental variance in GPA, stress, loneliness, or well-being, demonstrating the importance for testing validity instead of looking for it.

An overall statistic for testing symmetry in social interactions

The present work focuses the attention on the skew-symmetry index as a measure of social reciprocity. This index is based on the correspondence between the amount of behaviour that each individual addresses to its partners and what it receives from them in return. Although the skew-symmetry index enables researchers to describe social groups, statistical inferential tests are required. The main aim of the present study is to propose an overall statistical technique for testing symmetry in experimental conditions, calculating the skew-symmetry statistic (Φ) at group level. Sampling distributions for the skew- symmetry statistic have been estimated by means of a Monte Carlo simulation in order to allow researchers to make statistical decisions. Furthermore, this study will allow researchers to choose the optimal experimental conditions for carrying out their research, as the power of the statistical test has been estimated. This statistical test could be used in experimental social psychology studies in which researchers may control the group size and the number of interactions within dyads.

Correlation between microtensile bond strength data and clinical outcome of Class V restorations.

OBJECTIVE: To determine if the results of resin-dentin microtensile bond strength (µTBS) is correlated with the outcome parameters of clinical studies on non-retentive Class V restorations. METHODS: Resin-dentin µTBS data were obtained from one test center; the in vitro tests were all performed by the same operator. The µTBS testing was performed 8h after bonding and after 6 months of storing the specimens in water. Pre-test failures (PTFs) of specimens were included in the analysis, attributing them a value of 1MPa. Prospective clinical studies on cervical restorations (Class V) with an observation period of at least 18 months were searched in the literature. The clinical outcome variables were retention loss, marginal discoloration and marginal integrity. Furthermore, an index was formulated to be better able to compare the laboratory and clinical results. Estimates of adhesive effects in a linear mixed model were used to summarize the clinical performance of each adhesive between 12 and 36 months. Spearman correlations between these clinical performances and the µTBS values were calculated subsequently. RESULTS: Thirty-six clinical studies with 15 adhesive/restorative systems for which µTBS data were also available were included in the statistical analysis. In general 3-step and 2-step etch-and-rinse systems showed higher bond strength values than the 2-step/3-step self-etching systems, which, however, produced higher values than the 1-step self-etching and the resin modified glass ionomer systems. Prolonged water storage of specimens resulted in a significant decrease of the mean bond strength values in 5 adhesive systems (Wilcoxon, p<0.05). There was a significant correlation between µTBS values both after 8h and 6 months of storage and marginal discoloration (r=0.54 and r=0.67, respectively). However, the same correlation was not found between µTBS values and the retention rate, clinical index or marginal integrity. SIGNIFICANCE: As µTBS data of adhesive systems, especially after water storage for 6 months, showed a good correlation with marginal discoloration in short-term clinical Class V restorations, longitudinal clinical trials should explore whether early marginal staining is predictive for future retention loss in non-carious cervical restorations.

Laboratory Testing of SHRP SPS-2 P.C.C. Mixes, MLR-94-5, 1995

This research evaluated the concrete strength of two mixes which were used in the Polk County project NHS-500-1(3)--10-77 and were developed to meet a contract requirement of 900 psi third-point 28-day flexural strength. Two concrete mixes, the Proposed Mix and the Enhanced Mix, were tested for strength. Based on the experimental results, it was found that the addition of 50 lb of cementitious materials did not significantly increase concrete strength. The requirement of 900 psi 28-day third-point flexural strength (MOR-TPL) was not achieved by this amount of addition of cementitious materials.

Lag-one autocorrelation in short series: Estimation and hypothesis testing

In the first part of the study, nine estimators of the first-order autoregressive parameter are reviewed and a new estimator is proposed. The relationships and discrepancies between the estimators are discussed in order to achieve a clear differentiation. In the second part of the study, the precision in the estimation of autocorrelation is studied. The performance of the ten lag-one autocorrelation estimators is compared in terms of Mean Square Error (combining bias and variance) using data series generated by Monte Carlo simulation. The results show that there is not a single optimal estimator for all conditions, suggesting that the estimator ought to be chosen according to sample size and to the information available of the possible direction of the serial dependence. Additionally, the probability of labelling an actually existing autocorrelation as statistically significant is explored using Monte Carlo sampling. The power estimates obtained are quite similar among the tests associated with the different estimators. These estimates evidence the small probability of detecting autocorrelation in series with less than 20 measurement times.

Predictive value of readiness, importance, and confidence in ability to change drinking and smoking.

BACKGROUND: Visual analog scales (VAS) are sometimes used to assess change constructs that are often considered critical for change. Aims of Study: 1.) To determine the association of readiness to change, importance of changing and confidence in ability to change alcohol and tobacco use at baseline with the risk for drinking (more than 21 drinks per week/6 drinks or more on a single occasion more than once per month) and smoking (one or more cigarettes per day) six months later. 2.) To determine the association of readiness, importance and confidence with alcohol (number of drinks/week, number of binge drinking episodes/month) and tobacco (number of cigarettes/day) use at six months. METHODS: This is a secondary analysis of data from a multi-substance brief intervention randomized trial. A sample of 461 Swiss young men was analyzed as a prospective cohort. Participants were assessed at baseline and six months later on alcohol and tobacco use, and at baseline on readiness to change, importance of changing and confidence in ability to change constructs, using visual analog scales ranging from 1-10 for drinking and smoking behaviors. Regression models controlling for receipt of brief intervention were employed for each change construct. The lowest level (1-4) of each scale was the reference group that was compared to the medium (5-7) and high (8-10) levels. RESULTS: Among the 377 subjects reporting unhealthy alcohol use at baseline, mean (SD) readiness, importance and confidence to change drinking scores were 3.9 (3.0), 2.7 (2.2) and 7.2 (3.0), respectively. At follow-up, 108 (29%) reported no unhealthy alcohol use. Readiness was not associated with being risk-free at follow-up, but high importance (OR 2.94; 1.15, 7.50) and high confidence (OR 2.88; 1.46, 5.68) were. Among the 255 smokers at baseline, mean readiness, importance and confidence to change smoking scores were 4.6 (2.6), 5.3 (2.6) and 5.9 (2.7), respectively. At follow-up, 13% (33) reported no longer smoking. Neither readiness nor importance was associated with being a non-smoker, whereas high confidence (OR 3.29; 1.12, 9.62) was. CONCLUSIONS: High confidence in ability to change was associated with favorable outcomes for both drinking and smoking, whereas high importance was associated only with a favorable drinking outcome. This study points to the value of confidence as an important predictor of successful change for both drinking and smoking, and shows the value of importance in predicting successful changes in alcohol use. TRIAL REGISTRATION NUMBER: ISRCTN78822107.

Testing of Old Reinforced Concrete Bridges, HR-390, 1997

The objective of this research project was to service load test a representative sample of old reinforced concrete bridges (some of them historic and some of them scheduled for demolition) with the results being used to create a database so the performance of similar bridges could be predicted. The types of bridges tested included two reinforced concrete open spandrel arches, two reinforced concrete filled spandrel arches, one reinforced concrete slab bridge, and one two span reinforced concrete stringer bridge. The testing of each bridge consisted of applying a static load at various locations on the bridges and monitoring strains and deflections in critical members. The load was applied by means of a tandem axle dump truck with varying magnitudes of load. At each load increment, the truck was stopped at predetermined transverse and longitudinal locations and strain and deflection data were obtained. The strain data obtained were then evaluated in relation to the strain values predicted by traditional analytical procedures and a carrying capacity of the bridges was determined based on the experimental data. The response of a majority of the bridges tested was considerably lower than that predicted by analysis. Thus, the safe load carrying capacities of the bridges were greater than those predicted by the analytical models, and in a few cases, the load carrying capacities were found to be three or four times greater than calculated values. However, the test results of one bridge were lower than those predicted by analysis and thus resulted in the analytical rating being reduced. The results of the testing verified that traditional analytical methods, in most instances, are conservative and that the safe load carrying capacities of a majority of the reinforced concrete bridges are considerably greater than what one would determine on the basis of analytical analysis alone. In extrapolating the results obtained from diagnostic load tests to levels greater than those placed on the bridge during the load test, care must be taken to ensure safe bridge performance at the higher load levels. To extrapolate the load test results from the bridges tested in this investigation, the method developed by Lichtenstein in NCHRP Project 12-28(13)A was used.