Etude de la variation interlaboratoire du test de dépistage prénatal des défauts de fermeture du tube neural [Interlaboratory variation in the prenatal screening test for neural tube closing defects].

Early detection of neural-tude defects is possible by determining Alpha-fetoprotein (AFP) in maternal serum. 16'685 pregnant women were observed. Three methods for the determination of the "normal" range are compared. The first one, already used in similar studies, makes use of a constant multiple of the median. The other two ones make use of robust estimates of location and scale. Their comparison shows the interest of the robust methods to reduce the interlaboratory variability.

Analysis and spatial modeling of the indoor radon Swiss data

The present research deals with an important public health threat, which is the pollution created by radon gas accumulation inside dwellings. The spatial modeling of indoor radon in Switzerland is particularly complex and challenging because of many influencing factors that should be taken into account. Indoor radon data analysis must be addressed from both a statistical and a spatial point of view. As a multivariate process, it was important at first to define the influence of each factor. In particular, it was important to define the influence of geology as being closely associated to indoor radon. This association was indeed observed for the Swiss data but not probed to be the sole determinant for the spatial modeling. The statistical analysis of data, both at univariate and multivariate level, was followed by an exploratory spatial analysis. Many tools proposed in the literature were tested and adapted, including fractality, declustering and moving windows methods. The use of Quan-tité Morisita Index (QMI) as a procedure to evaluate data clustering in function of the radon level was proposed. The existing methods of declustering were revised and applied in an attempt to approach the global histogram parameters. The exploratory phase comes along with the definition of multiple scales of interest for indoor radon mapping in Switzerland. The analysis was done with a top-to-down resolution approach, from regional to local lev¬els in order to find the appropriate scales for modeling. In this sense, data partition was optimized in order to cope with stationary conditions of geostatistical models. Common methods of spatial modeling such as Κ Nearest Neighbors (KNN), variography and General Regression Neural Networks (GRNN) were proposed as exploratory tools. In the following section, different spatial interpolation methods were applied for a par-ticular dataset. A bottom to top method complexity approach was adopted and the results were analyzed together in order to find common definitions of continuity and neighborhood parameters. Additionally, a data filter based on cross-validation was tested with the purpose of reducing noise at local scale (the CVMF). At the end of the chapter, a series of test for data consistency and methods robustness were performed. This lead to conclude about the importance of data splitting and the limitation of generalization methods for reproducing statistical distributions. The last section was dedicated to modeling methods with probabilistic interpretations. Data transformation and simulations thus allowed the use of multigaussian models and helped take the indoor radon pollution data uncertainty into consideration. The catego-rization transform was presented as a solution for extreme values modeling through clas-sification. Simulation scenarios were proposed, including an alternative proposal for the reproduction of the global histogram based on the sampling domain. The sequential Gaussian simulation (SGS) was presented as the method giving the most complete information, while classification performed in a more robust way. An error measure was defined in relation to the decision function for data classification hardening. Within the classification methods, probabilistic neural networks (PNN) show to be better adapted for modeling of high threshold categorization and for automation. Support vector machines (SVM) on the contrary performed well under balanced category conditions. In general, it was concluded that a particular prediction or estimation method is not better under all conditions of scale and neighborhood definitions. Simulations should be the basis, while other methods can provide complementary information to accomplish an efficient indoor radon decision making.

Etude de validation du "Michigan alcoholism screening test" (MAST) en langue française

Le but de cette étude est de répondre aux 3 questions suivantes: - 1) Le test de MAST est-il applicable, dans sa traduction française, à la population d'un service de médecine interne d'un hôpital universitaire en Suisse romande ? - 2) Le test de MAST apporte-t-il des résultats concordants avec le diagnostic clinique d'une part, et avec les résultats tirés de la littérature d'autre part ? - 3) De quelles façons peut-on définir et choisir deux valeurs critiques du test afin d'optimaliser l'utilisation du test de MAST dans l'étude comparative projetée ? ANNEXE: Traduction littérale en langue française du : "Michigan Alcoholism Screening Test" (MAST); etc.

A benchmark test for a quantitative assessment of simple neuron models

Several methods and algorithms have recently been proposed that allow for the systematic evaluation of simple neuron models from intracellular or extracellular recordings. Models built in this way generate good quantitative predictions of the future activity of neurons under temporally structured current injection. It is, however, difficult to compare the advantages of various models and algorithms since each model is designed for a different set of data. Here, we report about one of the first attempts to establish a benchmark test that permits a systematic comparison of methods and performances in predicting the activity of rat cortical pyramidal neurons. We present early submissions to the benchmark test and discuss implications for the design of future tests and simple neurons models

Iowa Pore Index Test, MLR-80-2, 1980

The objective of the investigation was the development of a test that would readily identify the potential of an aggregate to cause D-cracking because of its susceptivity to critical saturation. A Press-Ur-Meter was modified by replacing the air chamber with a one-inch diameter plastic tube calibrated in milli-. It was concluded that the pore index was sufficiently reliable to determine the D-cracking potential of limestone aggregates in all but a few cases where marginal results were obtained. Consistently poor or good results were always in agreement with established service records or concrete durability testing. In those instances where marginal results are obtained, the results of concrete durability testing should be considered when making the final determination of the D-cracking susceptibility of the aggregate in question. The following applications for the pore index test have been recommended for consideration: concrete durability testing be discontinued in the evaluation process of new aggregate sources with pore index results between 0-20 (Class 2 durability) and over 35 (Class 1) durability; composite aggregates with intermediate pore index results of 20-35 be tested on each stone type to facilitate the possible removal of low durability stone from the production process; and additional investigation should be made to evaluate the possibility of using the test to monitor and upgrade the acceptance of aggregate from sources associated with D-cracking.

Evaluation of the Argentine Nondestructive Test for Determining Concrete Compressive Strength, R-269 and MLR-75-2, 1975

The compressive strength of concrete is an important factor in the design of concrete structures and pavements. To assure the quality of the concrete placed at the project, concrete compressive cylinders are made at the jobsite. These cylinders undergo a destructive test to determine their compressive strength. However, the determination of concrete compressive strength of the concrete actually in the structure or pavement is frequently desirable. For this reason, a nondestructive test of the concrete is required. A nondestructive test of concrete compressive strength should be economical, easily performed by field personnel, and capable of producing accurate, reproducible results. The nondestructive test should be capable of detecting the extent of poor concrete in a pavement or structure due to improper handling, placement, or variations in mixing or materials.

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.

Construction Automation Using Pen-Based Computers, HR-368, 1996

The Iowa Department of Transportation is committed to improved management systems, which in turn has led to increased automation to record and manage construction data. A possible improvement to the current data management system can be found with pen-based computers. Pen-based computers coupled with user friendly software are now to the point where an individual's handwriting can be captured and converted to typed text to be used for data collection. It would appear pen-based computers are sufficiently advanced to be used by construction inspectors to record daily project data. The objective of this research was to determine: (1) if pen-based computers are durable enough to allow maintenance-free operation for field work during Iowa's construction season; and (2) if pen-based computers can be used effectively by inspectors with little computer experience. The pen-based computer's handwriting recognition was not fast or accurate enough to be successfully utilized. The IBM Thinkpad with the pen pointing device did prove useful for working in Windows' graphical environment. The pen was used for pointing, selecting and scrolling in the Windows applications because of its intuitive nature.

Two Signatures For A New Blood-Based Test For Colorectal Cancer Screening

Background: Detection rates for adenoma and early colorectal cancer (CRC) are unsatisfactory due to low compliance towards invasive screening procedures such as colonoscopy. There is a large unmet screening need calling for an accurate, non-invasive and cost-effective test to screen for early neoplastic and pre-neoplastic lesions. Our goal is to identify effective biomarker combinations to develop a screening test aimed at detecting precancerous lesions and early CRC stages, based on a multigene assay performed on peripheral blood mononuclear cells (PBMC).Methods: A pilot study was conducted on 92 subjects. Colonoscopy revealed 21 CRC, 30 adenomas larger than 1 cm and 41 healthy controls. A panel of 103 biomarkers was selected by two approaches: a candidate gene approach based on literature review and whole transcriptome analysis of a subset of this cohort by Illumina TAG profiling. Blood samples were taken from each patient and PBMC purified. Total RNA was extracted and the 103 biomarkers were tested by multiplex RT-qPCR on the cohort. Different univariate and multivariate statistical methods were applied on the PCR data and 60 biomarkers, with significant p-value (< 0.01) for most of the methods, were selected.Results: The 60 biomarkers are involved in several different biological functions, such as cell adhesion, cell motility, cell signaling, cell proliferation, development and cancer. Two distinct molecular signatures derived from the biomarker combinations were established based on penalized logistic regression to separate patients without lesion from those with CRC or adenoma. These signatures were validated using bootstrapping method, leading to a separation of patients without lesion from those with CRC (Se 67%, Sp 93%, AUC 0.87) and from those with adenoma larger than 1cm (Se 63%, Sp 83%, AUC 0.77). In addition, the organ and disease specificity of these signatures was confirmed by means of patients with other cancer types and inflammatory bowel diseases.Conclusions: The two defined biomarker combinations effectively detect the presence of CRC and adenomas larger than 1 cm with high sensitivity and specificity. A prospective, multicentric, pivotal study is underway in order to validate these results in a larger cohort.

Development of a Conductometric Test for Frost Resistance of Concrete, HR-272, 1988

Research is described that was aimed at developing a test method which can be reasonably and rapidly performed in the laboratory and in the field to predict, with a high degree of certainty, the behavior of concrete subjected to the action of alternate freezing and thawing. The conductometric evaluation of concrete durability was explored with 3 different test methods: conductometric evaluation of the resistance of concrete to rapid freezing and thawing; conductomtric evaluation of the resistance of concrete to natural freezing and thawing, and conductometric evaluation of the pore size distribution of concrete and its correlation to concrete durability. The study showed that conductance could be used as a viable method for determining the durability of portland cement concrete. This would also allow the continuous monitoring of concrete durability without the removal twice per week from the freeze/thaw chamber. Recommendations for the continued development of these test methods are also included.

Test result-based sampling: an efficient design for estimating the accuracy of patient safety indicators.

OBJECTIVE: Accuracy studies of Patient Safety Indicators (PSIs) are critical but limited by the large samples required due to low occurrence of most events. We tested a sampling design based on test results (verification-biased sampling [VBS]) that minimizes the number of subjects to be verified. METHODS: We considered 3 real PSIs, whose rates were calculated using 3 years of discharge data from a university hospital and a hypothetical screen of very rare events. Sample size estimates, based on the expected sensitivity and precision, were compared across 4 study designs: random and VBS, with and without constraints on the size of the population to be screened. RESULTS: Over sensitivities ranging from 0.3 to 0.7 and PSI prevalence levels ranging from 0.02 to 0.2, the optimal VBS strategy makes it possible to reduce sample size by up to 60% in comparison with simple random sampling. For PSI prevalence levels below 1%, the minimal sample size required was still over 5000. CONCLUSIONS: Verification-biased sampling permits substantial savings in the required sample size for PSI validation studies. However, sample sizes still need to be very large for many of the rarer PSIs.

Innovative Leak Test for Pavement Joint Seals, Progress Report, HR-318, 1993

Premature failure of concrete pavement contraction joint seals is an ongoing and costly problem for the Iowa Department of Transportation. Several joint seal test sections consisting of variations in sawing methods, joint cleaning techniques, sealant installation, and sealant types have been established over the past few years. Laboratory analysis and field inspections were done as a part of the tests, and core samples were taken for laboratory adhesion pull tests. Such methods often cover specifically small areas and may not expose hidden failures. Some tests are also labor-intensive and destructive, especially that of coring. An innovative, nondestructive, broad coverage joint seal tester that yields quick results has been designed and developed for evaluation of pavement joint seal performance. The Iowa vacuum joint seal tester (IA-VAC) applies a low vacuum above a joint seal that has been spray-covered with a foaming water solution. Any unsealed area or leak that exists along the joint will become quickly and clearly visible by the development of bubbles at the leak point. By analyzing the results from the IA-VAC tests, information on the number and types of leaks can be obtained; such information will help identify the source of the problem and direct efforts toward a solution.