Classical Laboratory Methods Research Articles

Cardiovascular variability is/is not an index of autonomic control of circulation

To the Editor : As repeatedly underlined in this debate, neural cardiovascular (CV) regulation is characterized by a complex interaction between central and reflex mechanisms, with the contribution of other important factors such as respiratory frequency and depth. It would therefore be unrealistic

Diagnosis of Streptococcus pneumoniae meningitis by polymerase chain reaction amplification of the gene for pneumolysin

Diagnosis of bacterial meningitis has long been based on classical methods of Gram stain, serological tests, and culture of cerebrospinal fluid (CSF). The performance of these methods, especially culture and direct smear is thwarted by failure to detect bacteria following administration of antimicrobial agents and reluctance to performance lumbar punctures at admission. Indeed, patients with meningitis frequently receive antibiotics orally or by injection before the diagnosis is suspected or established Thus an alternative method has become necessary to help clinicians and epidemiologists to management and control of bacterial meningitis. We evaluate the application of a polymerase chain reaction-based (PCR) assay for amplification of pneumolysin gene (ply) to diagnosis of Streptococcus pneumoniae meningitis. The PCR assay sensitivity for CSF was 96% (95% confidence interval, CI, 90-99%) compared to a sensitivity of 59% for culture (95% CI 49-69%), 66% for Gram stain (95% CI 56-74%), and 78% for latex agglutination test (95% CI 69-86%); PCR specificity was 100% (95% CI 83-100%). PCR results were available within 4 h of the start of the assay. This molecular approach proved to be reliable and useful to identify this bacterium compared with other classical laboratory methods for identification of bacterial meningitis pathogens.

Near Infrared Spectroscopy Estimation of Feeding Value of Forage Perennial Grasses in Breeding Programmes by Global and Specific Calibrations. Estimation of Chemical Composition and Digestibility

Near infrared (NIR) spectral analysis with a NIRSystems 6500 monochromator was applied to evaluate accuracy of predictive models for forage quality in clone breeding processes of the original Bulgarian varieties over different cuts and years. The varieties were the perennial grasses: Dactylis glomerata L., Festuca arundinacea Schreb. and Bromus inermis Leyss. Global calibrations for the 418 perennial grass samples and specific calibrations for each single grass species and internal cross-validations were performed by the PLS regression method. The effect of different spectral data pre-treatments was investigated on the residual standard errors of the NIR predictive models. Among 60 calibration equations, the model with the lowest SECV value was retained for each parameter in each database. No particular data pre-treatment was really better than the other ones. Generally, the best results of the global calibrations were obtained with SNVD and MSC. For the specific calibrations, SNVD and WMSC were the best treatments. In both cases, the first or second derivatives were needed after the first pre-treatment. Chemical composition and in vitro enzymatic digestibility of clones were predicted with accuracy similar to that of classical laboratory methods. For the cell wall component contents, the standard errors of cross-validation SECV(%DM) ranged from 0.49 for ADL ( Festuca) to 2.02 for NDF ( Dactylis). The digestibilities of dry and organic matter, IVDMD and IVOMD, were estimated with SECVs from 2.6 to 3.0%, the relative intake, from 0.06 to 0.09 rel% body weight and the relative feeding value, from 4.39 to 5.64 rel%. The global calibration models offer an acceptable accuracy for the estimation of the cell wall nutrient contents, the digestibility and the nutritive value. The standard errors of prediction of specific single species calibrations with smaller numbers of terms were lower in 60% of the cases than those obtained from the best global calibrations with higher numbers of terms. On average, SECVs from specific calibrations are better than those from global calibrations, but the differences are quite small, and for the prediction of totally new samples (new crops, another year), the global calibrations will detect less outlier samples. Even with very high variability between cuts and years, NIR spectroscopy is able via ANOVA GL Models to sort clones on their feeding value and to provide relevant information for the breeding programmes.

Difficult rock comminution and associated geological conditions : Tarkoy, P J; Marconi M Proc Tunnelling '91, London, 14–18 April 1991P195–207. Publ London: Elsevier, 1991

Conditions encountered by the authors on several projects (tunnel boring, blast hole drilling, and large diameter pile socket drilling) were unanticipated, undetectable, and even difficult to identify even after they had been encountered. These conditions have caused failure of mechanical components, low penetration rates, and remarkably high cutter wear . Coincidentally, all projects had one or more geotechnical conditions in common . The difficulties encountered, however, could not be attributed to geotechnical factors measurable by classical laboratory or field methods . The difficulties were not discernible or predictable by conventional exploration, rock mechanics testing, or analysis, prior to tender .

Research in computational epidemiology

The emerging new area referred to as computational science or science done on a computer adds a third dimension to the traditional methods of theoretical and experimental approaches. Counterparts to computational science such as computational linguistice, computational engineering and others arc beginning to take roots. Naturally, new research paths and opportunities in computational epidemiology must also be explored. One of the major challenges in epidemiologic research is the issue of how to realistically and effectively handle complex bioepidemiologic dynamics involving interactions between humans or animals, etiological agents and the multiple array of environmental and socioeconomic determinants which affect these populations. To understand the behavior of such complex biological systems, it is useful to devise computer based simulation models. Computational epidemiologic approaches now provide alternative avenues to classical laboratory and/or field experimental methods. Systems which may be impractical because they are too large, or, not feasible because the cost is too prohibitive can now be simulated realistically. In the past obtaining solutions to biomathematical equations with any degree of complexity was impossible. However, the availability of powerful computers now makes the quantitative analysis of such systems feasible and indeed practical. With this in mind our research at Tuskegee University has focused on: a) Epidemiologic modelling and expert systems, and, b) Hypertext/hypermedia based epidemiologic knowledge management. The case studies for our research involve the bioepidemiologic dynamics of two complex host-parasite systems of trypanosoma and schistosoma. The ultimate goal is to develop resources and methodologies based on computational technology to advance epidemiologic research. The paper will address the methodological issues and findings as well as questions related to configuring an appropriate research workstation for computational epidemiology.

Management of Chemical Cyanos by Oxygen Saturation Readings

Chemical cyanosis is an oxygen transport deficiency produced by exposure to aromatic nitro- or animo-compounds. Evaluation of its severity by methemoglobin determinations defines the problem incompletely and is time consuming. Twenty-nine patients were studied over a five-year period by both methemoglobin level using classical laboratory methods and oxygen saturation level, using a reflection oximeter. The two results were found to bear an inverse linear relationship. Oxygen saturation may be determined easily and rapidly by the reflection oximeter method, and may be used safely as a guide to treatment of chemical cyanosis. No changes would have been made in medical management of any of the patients if the decisions had been made on the basis of the oxygen saturation level of less than 90% rather than the methemoglobin percentage of 10% or more.

Concept Learning and Retention in Mathematics

RECENTLY many experiments have been con ducted in order to investigate the different ways by which children learn mathematical concepts. There is a growing concern as to what methods of instruc tion are most appropriate for children of all levels of mathematical and academic ability. Questions of what can be and what should be taught at the differ ent levels of mathematics education have been raised, and there now seems to be some agreement that children are capable of mastering more mathe matics and more complex mathematics, than was previously possible. One has only to review the findings'of a researcher such as Suppes, and read the reports of well-known mathematicians, psychol ogists, and educators such as those who composed the Cambridge Report, in order to learn of recent advancements and proposals for the future. Some of the recent experiments have been con cerned with how children employ newly learned con cepts in a problem-solving situation. This area of mathematics education is beginning to undergo much experimentation, but as yet, there is not much that can be put together in the form of well-defined pro cedures and widely accepted ideas. Many psychologists and mathematics educators, considering the above concern, have investigated the effectiveness of the use of programed materi als as a means of testing various instructional theo ries. One can find opposing views as to the effec tiveness of such materials in an instructional situ ation, but the least that can be said is that pro gramed materials allow the researcher to more nearly duplicate the normal teaching situations than did the classical laboratory methods.

Some departures from classical laboratory methods in general chemistry

Some departures from classical laboratory methods in general chemistry