Classical Experimental Methods Research Articles

Grafting characterization of natural rubber latex particles: wet-STEM imaging contributions

Natural rubber latexes investigated in this study have been chemically modified by seeded emulsion polymerization. Depending on the water affinity of the monomer involved (MMA or DMAEMA), the expected result was the grafting of the corresponding polymer inside or on the surface of the latex particles. The present article focuses on the grafting characterization of these modified natural rubber latexes. In this purpose, non-imaging classical experimental methods such as dynamic light scattering and nuclear magnetic resonance have been completed by microscopy techniques, including transmission imaging in scanning electron microscopy (SEM) and a recent imaging mode called wet-STEM. It consists in transmission imaging in an Environmental SEM operating in the wet-mode, allowing transmission observations of particles suspended in a liquid layer with good resolution and contrast. In the present study, we have adopted a comparative characterization approach between a nongrafted natural rubber latex and two grafted ones. Such an approach indeed contributes to highlight the particles morphology resulting from chemical modification using either MMA or DMAEMA. Transmission images in SEM of thin foils are relatively well interpreted and are completed with wet-STEM images of latexes in their native state, bringing important contributions for grafting characterization.

Acupuncture Powered by Energy Techniques–22nd International Symposium on Acupuncture & Electro‐Therapeutics

The 22nd International Symposium on Acupuncture and Electro-Therapeutics is the annual meeting and the main scientific event of research and teaching activity of the International College of Acupuncture & ElectroTherapeutics Research. The meeting is organized by Professor Yoshiaki Omura, Founder and Director of the College, Director of Medical Research in the Heart Disease Research Foundation. The Symposium is supported by the International College of Acupuncture & Electro-Therapeutics Research, by its official journal published by Cognizant Communication Corporation and by the Heart Disease Research Foundation. The International College of Acupuncture & ElectroTherapeutics Research is a non-profit international medical society dedicated to scientific investigation and to education of physicians and other health care professionals on the latest research findings and practical methods in acupuncture and related techniques. Scientific presentations at 22nd International Symposium on Acupuncture & Electro-Therapeutics addressed a multitude of topics relevant to physicians and scientists interested in acupuncture and related techniques. Presentations on advances in acupuncture research using the methods of basic science included the classical pharmacological experimental approach, structural and ultra-structural histological methods followed by clinical reports on the evaluation and treatment of a wide variety of diseases using acupuncture. The Symposium was focused primarily on body acupuncture according to the traditional Chinese meridian system, ear acupuncture and diagnostic techniques combining Traditional Chinese Medicine (TCM) concepts with the modern scientific approach. The program consisted of various types of presentations: lectures, workshops, liveand videopresentations of patients, and live demonstrations of diagnostic and treatment techniques. The 4-day Symposium attracted researchers from Australia, Brazil, Canada, China, Germany, Japan, Korea, Russia, Serbia, Tibet, Turkey and USA. The intensive program was scheduled from 09:00 a.m. until 10:00 p.m. every day.

Bayesian cross-entropy methodology for optimal design of validation experiments

An important concern in the design of validation experiments is how to incorporate the mathematical model in the design in order to allow conclusive comparisons of model prediction with experimental output in model assessment. The classical experimental design methods are more suitable for phenomena discovery and may result in a subjective, expensive, time-consuming and ineffective design that may adversely impact these comparisons. In this paper, an integrated Bayesian cross-entropy methodology is proposed to perform the optimal design of validation experiments incorporating the computational model. The expected cross entropy, an information-theoretic distance between the distributions of model prediction and experimental observation, is defined as a utility function to measure the similarity of two distributions. A simulated annealing algorithm is used to find optimal values of input variables through minimizing or maximizing the expected cross entropy. The measured data after testing with the optimum input values are used to update the distribution of the experimental output using Bayes theorem. The procedure is repeated to adaptively design the required number of experiments for model assessment, each time ensuring that the experiment provides effective comparison for validation. The methodology is illustrated for the optimal design of validation experiments for a three-leg bolted joint structure and a composite helicopter rotor hub component.

Solvation of Drugs as a Key for Understanding Partitioning and Passive Transport Exemplified by NSAIDs

Passive transport properties of drug molecules are of utmost importance for their pharmacological and biopharmaceutical effectiveness. Diffusion in different media and through lipid bilayers is in many cases the rate-determining step for the distribution in the body. In the present review an attempt is made to demonstrate the importance of solvation of drug molecules for the diffusion and partition/distribution in phases of different lipophilicity. Different approaches known in the literature to describe solvation of compounds with flexible conformation are discussed as well as the experimental methods to directly measure the energy of solvation. NSAIDs are chosen as an example of a class of drugs of different molecular structures that have already been studied thoroughly in many aspects, and a set of aliphatic alcohols can be used as a model for compartments of different lipophilic/hydrophilic properties. Thermodynamic characteristics of solvation of the drug molecules yielded by independent classical experimental methods (Gibbs energy, enthalpic and entropic terms of Gibbs energy) are studied in order to better understand diffusion and distribution properties. Correlations between in-vitro-data (partition coefficient, enthalpy of solvation) with biopharmaceutically relevant characteristics (plasma half-life) are also discussed.

A Parametric Equation Relating Resistivity to Capillary Pressure for Omani Sandstone

Capillary pressure and resistivity are important parameters that are mostly used in reservoir and petrophysical characterization. Capillary pressure data remain difficult to obtain and classical experimental methods used are questionable and not very adequate. One major drawback in running capillary pressure experiments is the use of fluids other than formation fluids. Another resides in the difficulty to measure capillary pressure at representative reservoir conditions. One more drawback, to name a few, is the experiments time which remains very prolonged, especially when the formation to be characterized is tight because the fluid drainage can take up months if not more. To overcome the intrinsic difficulties of having representative data, an empirical equation relating resistivity to capillary pressure was developed. In this work, twenty-five core plugs of Omani sandstone have been used in an attempt to come up with a representative correlation.

Elaborating the Differential in Differential Psychology

The methods of differential psychology have contributed importantly to the current state of behavioral science, but their limitations continue to be well - publicized in the "experimental versus correlational" literature. The argument developed here is that the value of these methods has been constrained as much by the phenomena to which they are applied as by underlying flaws that render them inferior to classical experimental methods. Some applications of differential methods to alternative phenomena are examined that promise to broaden significantly the contribution that differential methods can make to our understanding of behavior and behavior change.

Spectrometry of the LET with track etched detectors—correlation with proportional counter measured spectra

A spectrometer of the linear energy transfer (LET) based on the chemically etched polyallyldiglycolcarbonate (PADC) track etched detector was developed. The LET spectra are determined through the measurements of track parameters, it covers LET range between 10 and 700 keV/ μm in tissue. A combined experimental and theoretical approach allowed the estimation of the critical dimensions of the sensitive volume necessary for developing a track to several nm. It seemed interesting to us to compare the LET spectra obtained by this method with the microdosimetric spectra available on the basis of a classical experimental microdosimetry method, a tissue equivalent proportional counter, for which the critical dimensions simulated are of the order of a few μm. Both methods of experimental microdosimetry were compared in the high energy radiation reference fields and on the subsonic aircraft board. It was found out that the microdosimetric distributions are similar; some differences are, nevertheless, observed. Further studies with the goal to explain them are outlined.

Prediction of Activity Coefficients in Low-Molecular-Weight Paraffins from Gas Chromatographic Data

It is shown that gas-liquid partition coefficients measured by gas chromatography on nonvolatile paraffin stationary phases at high temperatures allow estimation of gas-liquid partition coefficients of solutes at ambient temperatures in volatile alkanes as solvents. Extrapolation to low temperatures was successful by use of the Kirchhoff equation for the description of the temperature dependence of the standard chemical potential of the solute related to its molal Henry coefficient. A new equation is proposed for the prediction of partition data in low-molecular-weight paraffins. It was derived by using the Flory-Huggins model as a guide, and it combines theory with experiment. It is proposed to accept a combinatorial entropy term determined by experiment as a solute property. The necessary experimental information consists of a set of gas chromatographic data measured at at least four temperatures on two pure, high-molecular-weight paraffins. Molal Henry coefficients extrapolated to low-molecular-weight solvents allowed calculation of activity coefficients. Predicted and measured data agreed within ± 20%. The reproducibility of activity coefficients by classical experimental methods is of the same order of magnitude.

Transient temperature measurements and modeling of IGBT's under short circuit

This paper discusses the estimation of possible device destruction inside power converters in order to predict failures by means of simulation. The study of insulated gate bipolar transistor (IGBT) thermal destruction under short circuits is investigated. An easy experimental method is presented to estimate the temperature decay in the device from the saturation current response at low gate-to-source voltage during the cooling phase. A comparison with other classical experimental methods is given. Three one-dimensional thermal models are also studied: the first is a thermal equivalent circuit represented by series of resistance-capacitance cells; the second treats the discretized heat-diffusion equation; and the third is an analytical model developed by building an internal approximation of the heat-diffusion problem. It is shown that the critical temperature of the device just before destruction is larger than the intrinsic temperature, which is the temperature at which the semiconductor becomes intrinsic. The estimated critical temperature is above 1050 K, so it is much higher than the intrinsic temperature (/spl sim/550 K). The latter value is underestimated when multidimensional phenomena are not taken into account. The study is completed by results showing the threshold voltage and the saturation current degradation when the IGBT is submitted to a stress (repetitive short circuit).

Experimental Evidence on the Impacts of Computer-Assisted Instruction in the Job Corps Program

This article describes the results of a computer-assisted instruction (CAI) demonstration project that was conducted in 10 Job Corps centers nationwide. The demonstration used classical experimental methods to determine the effectiveness of CAI, with students randomly assigned to a treatment group in which they spent about one fourth to one third of their class time on the computer as a supplement to the regular self-paced education program or to a control group in which CAI was not available in their education classes. The results indicate that the effects of CAI on learning gains after about 60 hours of classroom instruction are very small on average and not significantly different from zero at conventional levels. However, there is some evidence that centers that allowed their experimental students to have sufficient access to CAI and students that used CAI more intensively did experience additional learning gains relative to the control group. Qualitative information obtained from students, teachers, and education supervisors suggest that CAI may be useful in motivating students and supports the potential educational benefits of CAI.

Randomization by group in studying the effect of drug information in primary care.

Drug information is a technology which is rarely evaluated. Practical and ethical considerations limit the use of a classical experimental method (a randomized controlled trial) in studying the effect of drug information in primary care. An alternative approach, randomization by group, is preferable for several reasons: it avoids contamination of the control group; the effect of information can be evaluated in the natural working environment; and the impact of information is increased via diffusion. This article describes the selection of a control group, the Hawthorne effect and 'blindness' in information experiments. Sample size tables and power calculations are presented when randomization by group is used. The study power is influenced by the number of health centres and the variance between them. The number of doctors per health centre plays a less important role, and the number of patients is relatively unimportant. There is also a need to use qualitative methods to prepare information and to understand factors influencing change of behaviour among prescribers.

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.

Optimization of quantitative X-ray phase analysis by Monte Carlo methods

Present methods for quantitative X-ray phase analysis make extensive use of multilinear regression. Practical application of these methods compels workers to make a choice among many different sets of experimental conditions such as the number, identity and relative concentration of the phases in the synthetic mixtures used for the solution of the regression problem; the number and extent of the angular regions within which X-ray intensities are to be measured; and so on. There are as yet no general criteria for this selection, and classical statistical experimental methods, even such effective ones as SIMPLEX, are very time consuming. In the present work a Monte Carlo method is proposed for optimization of the reproducibility and detection limit for a completely general quantitative X-ray phase analysis. A system of three computer programs to this end is developed and applied to X-ray phase analysis of laterites, illustrating the choice of a set of performing conditions among 20 of them.

The case for evaluating training programs with randomized trials

This brief paper presents the reasons why I have come to conclude that the evaluation of the economic benefits of training programs will be greatly enhanced by the use of classical experimental methods where control and experimental groups are selected by random assignment (randomized trials). A simple comparison of earnings between control and experimental groups subsequent to participation in the experimental program then provides a simple and credible estimate of program success (or failure). The principal reason why randomized trials should be used in this field is that too much of the non-experimental estimation of the effects of training programs seems dependent on elements of model specification that cannot he subjected to powerful statistical tests.

Finite element method applied to characterization of piezoelectric ceramics

Finite element computation of piezoelectric transducers requires the knowledge of elastic, piezoelectric, and dielectric coefficients of ceramics. These constants are generally not available from the manufacturer, and even, variations up to 20% can be expected in the worse cases. The classical experimental method, proposed by Mason, is based on admittance measurements and a complete determination of all the materials properties requires five resonator geometries. An interesting method, based on an adjustment of first modes of ceramic rings with a finite element code, is described. It has three advantages over the Mason method. First, it does not require particular resonator geometries; second, the experimental method is summed up on a simple impedance measurement of the whole ceramics; and third, the adjustment is unaffected by local nonhomogeneity of materials. In this paper, the whole method is developed. Then experimental and numerical results are compared for several ceramics.

Relations between integrated intensities in crystal diffraction methods for X-rays and neutrons

In addition to the classical experimental methods of crystal diffraction a number of new methods have become available using the time-of-flight technique for neutrons and energy-dispersive detectors for X- rays. It is shown that there are simple relations between the formulae for the integrated intensities of the different methods, and that the intensity formulae for all the methods can be simply generated, provided that one of them is derived in the usual way. Formulae are given for the powdered crystal and the ideally imperfect crystal in the kinematical approximation as well as for the large perfect crystal in the framework of the dynamical theory.

Frontal sinus disease. I. An historical perspective on research.

AbstractThe surgical approach to frontal sinus disease has been subject to much variation in the past 100 years. The variety of procedures is actually based on very few experiments in which the results are often conflicting.A review of basic research in the pathogenesis and treatment of frontal sinus disease reveals that with the exception of the osteoplastic fat obliteration procedure, the classical experimental method of laboratory evaluation prior to clinical implementation has been, for the most part, ignored. The response to infection of the ciliated sinus mucosa and its role in the further propagation of frontal sinusitis is poorly understood. The conditions under which the sinus mucosa regenerates have not been clearly defined, nor has complete reformation of the mucosa membrane been consistent experimentally or clinically.The presumptive role of the nasofrontal duct in the pathogenesis of frontal sinusitis and mucocele is based solely on inference from clinical material.The variations of frontal osteoplasty each have limitations in reliability and prevention of recurrent disease.The development of a canine frontal sinus model with which to examine several of these problems is discussed.

Endocrinology of the lampreys

The ammocoetes larvae of the modern Petromyzontiformes are slowly growing filter feeders, and the imagines are rapidly growing macrophagous fish parasites. The larvae demonstrate the prototypal metabolism of the Silurian and Devonian Agnatha; the imagines show the typical metabolism of the Gnathostomata. The metamorphosis repeats the period of evolution in which the Gnathostomata arose from the Agnatha. The graduation and differentiation of the metabolism is also expressed in the endocrine system. These principal conditions are varied throughout the environments in the different phases of the life cycle of Petromyzontiformes. After a long larval period in freshwater the young lampreys migrate toward the sea (catadromous migration). Here they start the parasitic feeding period. After some time they cease irreversibly to feed and gather for the spawning migration. After spawning in freshwater they die. During and after metamorphosis the following endocrine organs are increased characteristically: adenohypophysis; endostyle → thyroid; medulla and cortex cells scattered along the kidneys. Only few changes are visible in the hypothalamoneurophypophyseal system and in the islets of Langerhans. Thymus and parathyroids are absent in Petromyzontiformes. Our knowledge is based predominantly on morphological and classical experimental methods. Biochemical and pharmacological studies are as yet rare. Nothing is known of the marine parasitic-feeding period. The following hormones have been identified in lampreys: vasotocin, thyroxine, triiodothyronine, insulin. Vasotocin affects only sodium metabolism; no antidiuretic action could be demonstrated. The presence of steroids is probable. By investigations of the endocrine system of Petromyzontiformes results may be obtained showing the primary function of the vertebrate hormones.

Studies on the effects of treatment with chlorine dioxide on the properties of wheat flour. IV.—The biological properties of untreated, normally treated and overtreated flours

AbstractPrevious studies indicate that no significant nutritional damage to flour protein was incurred by the use of chlorine dioxide, even at ten times the normal level of treatment, and that no abnormal substances were formed.1–3 In confirmation of this previous work, further studies on animals have been made which form the subject of this report.The object of the experiment described in this paper was to apply classical group feeding experimental methods to the comparison of normally and ten times normally chlorine dioxide‐treated flour. Since it was already known1–3 that no significant damage to known nutrients had occurred, the main emphasis was on the possible occurrence of any consistent differences indicative of toxic action. As a further check on this study, a group received the same flour untreated in Generations 0 and 1. All the observations were also compared with standard figures obtained from a much larger group of animals not receiving chlorine dioxide‐treated flour, but otherwise living under similar conditions.