Study of the factors determining the mobility of ions in the polypyrrole films doped with aromatic sulfonate anions

The electrochemical redox behavior of the polypyrrole (PPy) films doped with benzenesulfonate (BS), p-toluenesulfonate (pTS) and naphtalene-1,5-disulfonate (NDS) was investigated by cyclic voltammetry, the chemical composition of the films was determined by XDS, the surface morphology was characterized by AFM, and the interactions between pyrrole oligomers and the anions were modeled with quantum chemical methods. It is the first detailed comparative study of the properties of these interesting systems with two complementing interactions (electrostatic and aromatic stacking). It was shown than these relatively similar aromatic sulfonate anions have rather different behavior in PPy films. The results showed that the redoxactivity of polypyrrole films doped with sulfonate ions increases in the sequence pTS < BS < NDS. The comparison of voltammograms measured in the presence of different anions with PPy films synthesized in the same solution show that the PPy/pTS films have the most densely packed and the PPy/NDS films the least densely packed structure of the three. The mobility of ions in these films is mainly determined by the packing of the films, which in turn partly depends on the interactions between the dopant-anion and polymer chains.     

Variational formulation of open-ended coaxial line in contact withlayered biological medium

An open-ended coaxial probe designed to measure layered biological media is analyzed with a new method. The probe is considered as an electrostatic circuit element whose capacitance is solved using a stationary functional. The fundamental transverse electric and magnetic field (TEM)-mode and the series of evanescent wavemodes in the coaxial cable are used as basis functions. The field outside the probe is solved using a Hankel transform. The capacitance is calculated for homogeneous materials and two-layer structures and the results are compared with values measured with a phantom model. The method can be easily extended for structures with an arbitrary number of layers. A practical approximation for two-layer cases, originally developed to take into account the effect of subcutaneous fat in skin measurements, is presented and its validity for different combinations of dielectric constants and the thickness of the first layer is demonstrated. The static approximation limits the frequency range, but it covers biological measurements up to 500 MHz. The developed method is accurate and easy to adopt in practice     

Human gallbladder mucosal function: effects on intraluminal fluid and lipid composition in health and disease

OBJECTIVES: Fructose-1,6-diphosphate is a glycolytic intermediate that has been shown experimentally to cross the cell membrane and lead to increased glycolytic flux. Because glycolysis is an important energy source for myocardium during early reperfusion, we sought to determine the effects of fructose-1,6-diphosphate on recovery of postischemic contractile function. METHODS: Langendorff-perfused rabbit hearts were infused with fructose-1,6-diphosphate (5 and 10 mmol/L, n = 5 per group) in a nonischemic model. In a second group of hearts subjected to 35 minutes of ischemia at 37 degrees C followed by reperfusion (n = 6 per group), a 5 mmol/L concentration of fructose-1,6-diphosphate was infused during the first 30 minutes of reperfusion. We measured contractile function, glucose uptake, lactate production, and adenosine triphosphate and phosphocreatine levels by phosphorus 31-nuclear magnetic resonance spectroscopy. RESULTS: In the nonischemic hearts, fructose-1,6-diphosphate resulted in a dose-dependent increase in glucose uptake, adenosine triphosphate, phosphocreatine, and inorganic phosphate levels. During the infusion of fructose-1,6-diphosphate, developed pressure and extracellular calcium levels decreased. Developed pressure was restored to near control values by normalizing extracellular calcium. In the ischemia/reperfusion model, after 60 minutes of reperfusion the hearts that received fructose-1,6-diphosphate during the first 30 minutes of reperfusion had higher developed pressures (83 +/- 2 vs 70 +/- 4 mm Hg, p < 0.05), lower diastolic pressures (7 +/- 1 vs 12 +/- 2 mm Hg, p < 0.05), and higher phosphocreatine levels than control untreated hearts. Glucose uptake was also greater after ischemia in the hearts treated with fructose-1,6-diphosphate. CONCLUSIONS: We conclude that fructose-1,6-diphosphate, when given during early reperfusion, significantly improves recovery of both diastolic and systolic function in association with increased glucose uptake and higher phosphocreatine levels during reperfusion.     

Improving clustering performance using multipath component distance

The problem of identifying clusters from MIMO measurement data is addressed. Conventionally, visual inspection has been used for cluster identification, but this approach is impractical for a large amount of measurement data. For automatic clustering, the multipath component distance (MCD) is used to calculate the distance between individual multipath components estimated by a channel parameter estimator, such as SAGE. This distance is implemented in the well-known KMeans clustering algorithm. To demonstrate the effectiveness of the choice made, the performance of the MCD and the Euclidean distance were compared by clustering synthetic data generated by the 3GPP spatial channel model (SCM). Using the MCD significantly improved clustering performance     

Culture of Helicobacter pylori from gastric biopsies transported in biopsy urease test tubes

Gastric biopsy specimens of 57 consecutively observed dyspeptic patients were studied for the presence of Helicobacter pylori by histological examination, biopsy urease test (BUT) and culture. For culture, biopsy samples were transported in both Stuart media and BUT tubes. All 15 isolates could be cultured from both Stuart and BUT tubes. Thus, if the main reason for culture of Helicobacter pylori is for antimicrobial susceptibility testing, only positive BUT tubes need to be submitted. This would reduce both the expense and the number of biopsies needed.     

FAST LINEAR ESTIMATION METHODS FOR VECTOR AUTOREGRESSIVE MOVING-AVERAGE MODELS

Abstract. Three linear methods for estimating parameter values of vector auto-regressive moving-average (VARMA) models which are in general at least an order of magnitude faster than maximum likelihood estimation are developed in this paper. Simulation results for different model structures with varying numbers of component series and observations suggest that the accuracy of these procedures is in most cases comparable with maximum likelihood estimation. Procedures for estimating parameter standard error are also discussed and used for identification of nonzero elements in the VARMA polynomial structures. These methods can also be used to establish the order of the VARMA structure. We note, however, that the primary purpose of these estimates is to generate initial estimates for the nonzero parameters in order to reduce subsequent computational time of more efficient estimation procedures such as exact maximum likelihood.     

Long-term follow-up of the clinical relevance of short outer dynein arms in human nasal cilia

A high-performance liquid chromatographic (HPLC) procedure for quantitating ketoprofen in isopropyl myristate (IPM), a compound widely used as a receptor medium in drug diffusion studies of topical aqueous-based formulations, is developed. Previously reported HPLC assays for ketoprofen in IPM have employed relatively complex and tedious methods for purifying the IPM prior to injection onto the HPLC column. The present assay method utilizes a direct injection of the IPM-based sample onto a new reversed-phase ODS column and employs ultraviolet detection at 265 nm. Propyl paraben is employed as the internal standard. The mobile phase consists of acetonitrile-methanol-water (36:54:10, v/v/v) at a flow rate of 1.2 mL/min. The calibration curves are linear (correlation coefficient r > or = 0.988) over concentration ranges of 0.625-10 micrograms/mL and 6.25-100 micrograms/mL. The within-day and between-day precision exhibit coefficients of variation of 1.3-3.3%, and the accuracy (reported as relative error of the mean) varies from -1.9% to 0.6%. The retention times for ketoprofen and propyl paraben are approximately 2.3 and 3.3 min, respectively. The total run time per sample is approximately 7 min. The minimum quantitatable concentration is approximately 0.625 microgram/mL. The assay is stability-indicating, rapid, reproducible, sensitive, and readily adaptable for assaying other non-steroidal anti-inflammatory drugs.     

Expert Identity construct in analysing prerequisites for expertise development: a case study of nuclear power plant operators’ on-the-job training

This article discusses how shifting the focus of research to the emotional side of human actions and cognition could create new perspectives on the problem of how to support the human operator in the control of rare disturbances. A new construct, Expert Identity, is described. A qualitative study of the specific problems with changing the operator generation at a nuclear power plant is presented. The results indicate that the current identity of the trainees is more or less still one of the trainees. The conceived demands of operator work and the perceived learning opportunities are characterised by a dichotomy: disturbances or other exceptional situations emerge as different from daily work. The key challenge and motive for the trainees in the development of expertise is to achieve not only an adequate degree of competence but also to construct confidence in being able to cope with potential disturbance situations.

Comparison of entropy and complexity measures for the assessment of depth of sedation

Entropy and complexity of the electroencephalogram (EEG) have recently been proposed as measures of depth of anesthesia and sedation. Using surrogate data of predefined spectrum and probability distribution we show that the various algorithms used for the calculation of entropy and complexity actually measure different properties of the signal. The tested methods, Shannon entropy (ShEn), spectral entropy, approximate entropy (ApEn), Lempel-Ziv complexity (LZC), and Higuchi fractal dimension (HFD) are then applied to the EEG signal recorded during sedation in the intensive care unit (ICU). It is shown that the applied measures behave in a different manner when compared to clinical depth of sedation score--the Ramsay score. ShEn tends to increase while the other tested measures decrease with deepening sedation. ApEn, LZC, and HFD are highly sensitive to the presence of high-frequency components in the EEG signal.