Search results for "CONSTANT"
showing 10 items of 1718 documents
Optical biosensor-based characterization of anti-double-stranded DNA monoclonal antibodies as possible new standards for laboratory tests.
2009
The serum determination of circulating anti-double-stranded (ds)DNA autoantibodies is a routine measure for the laboratory diagnosis of systemic lupus erythematosus. Since available assays differ substantially and no feasible calibrator is available, the aim of this study was to evaluate a recently introduced surface plasmon resonance (SPR) biosensor chip for binding studies between dsDNA and anti-dsDNA autoantibodies and to demonstrate its usefulness for the characterization of new monoclonal antibody (mAb) standards and standardization of assays. We characterized two human and one murine monoclonal anti-dsDNA antibodies by measuring the kinetic on- and off-rates using the biosensor and ca…
Spring constants of capsular tension rings.
2004
Purpose To determine the spring constants of several types of capsular tension rings (CTRs). Setting Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany. Methods Fourteen models of CTRs provided by 9 companies were tested; all were 11.0 mm in diameter. The CTRs were positioned in a special retainer of a material-testing machine and compressed at a constant speed of 10.0 mm per minute. The distance and force values were recorded, and each CTR model was tested 3 times using a new specimen each time. The resulting measurements were used to calculate a mean spring constant for each CTR model. Results All tested CTRs showed linear proportionality between force and compress…
Effects of electrical stimulation pattern on quadriceps isometric force and fatigue in individuals with spinal cord injury
2015
Introduction Variable frequency trains (VFT) or train combinations have been suggested as useful strategies to offset the rapid fatigue induced by constant frequency trains (CFT) during electrical stimulation. However, most studies have been of short duration with limited functional application in those with spinal cord injury (SCI). We therefore tested force and fatigue in response to VFT, CFT, and combined patterns in strength training-like conditions (6-s contractions). Methods Ten SCI individuals underwent either CFT or VFT patterns until target torque was no longer produced and then switched immediately to the other pattern. Results Target torque was reached more times when VFT was use…
Effects of electrical stimulation pattern on quadriceps force production and fatigue
2014
Introduction: Mixed stimulation programs (MIX) that switch from constant frequency trains (CFT) to variable frequency trains have been proposed to offset the rapid fatigue induced by CFT during electrical stimulation. However, this has never been confirmed with long stimulation patterns, such as those used to evoke functional contractions. The purpose of this study was to test the hypothesis that MIX programs were less fatiguing than CFTs in strength training-like conditions (6-s contractions, 30-min). Methods: Thirteen healthy subjects underwent 2 sessions corresponding to MIX and CFT programs. Measurements included maximal voluntary isometric torque and torque evoked by each contraction. …
ECG Analysis for Ventricular Fibrillation Detection Using a Boltzmann Network
2015
Arrhythmias consist on electrical alterations in the heart beat control. They can be identified by means of surface ECG leads. The main goal of this work is to provide a signal classification based on ECG signal waveform in the time-frequency domain especially targeted to Ventricular Fibrillation detection. The use of a classifier based on a Boltzmann network is proposed. However, a previous signal preprocessing is also required so that the Boltzmann network is fed with the appropriate data. In this case, an R-wave detector is used; after that, the Pseudo Wigner-Ville time-frequency distribution is obtained. This distribution is used to train and test the network, which handles it as an ima…
Evaluation of a lattice-Boltzmann method for mercury intrusion porosimetry simulations
2004
We have simulated intrusion of a non-wetting liquid into pores of varying shape and size. Simulations were based on the lattice-Boltzmann method and the Shan–Chen multiphase model. The liquid–solid contact angle for pores with circular cross-section was found to be equal to that for pores with square cross-section, and constant even for small pore sizes if the discretised shape of the circular cross-section was taken into account. For comparison, contact angle was also determined for a liquid column descending in a capillary tube, and the results were found to be consistent. Application of the method to mercury intrusion porosimetry is discussed.
Analytical model for the long- distance tracer-transport in plants
2011
International audience; Recent investigations of long-distance transport in plants using non-invasive tracer techniques such as C radiolabeling monitored by positron emission tomography (PET) combined with magnetic resonance imaging (MRI) revealed the need of dedicated methods to allow a quantitative data analysis and comparison of such experiments. A mechanistic compartmental tracer transport model is presented, defined by a linear system of partial differential equations (PDEs). This model simplifies the complexity of axial transport and lateral exchanges in the transport pathways of plants (e.g. the phloem) by simulating transport and reversible exchange within three compartments using j…
Interaction of methyltin(IV) compounds with carboxylate ligands. Part 1: formation and stability of methyltin(IV)–carboxylate complexes and their rel…
2006
Quantitative data on the stability of mono-, di- and trimethyltin(IV)-carboxylate complexes (acetate, malonate, succinate, malate, oxydiacetate, diethylenetrioxydiacetate, tricarballylate, citrate, butanetetracarboxylate and mellitate) are reported at t=25°C and I → 0 mol l - 1 . Several mononuclear, mixed proton, mixed hydroxo and polynuclear species are formed in these systems. As expected, the stability trend is mono- > di- > trimethyltin(IV) and mono < di < tri < tetra < hexa for the organotin moieties and carboxylate ligands investigated, respectively. Moreover, ligands containing, in addition to carboxylic,-O-and-OH groups show a significantly higher stability with respect to analogou…
Dielectric properties of myoglobin at 10 GHz by microwave cavity perturbation measurements
2010
We report on the temperature dependence, at microwave (mw) frequency, of the imaginary part of the dielectric constant (En) in myoglobin powder samples with different hydration levels (h). The measurements have been performed by the cavity perturbation technique, in the range of temperature 80-345 K. The sample is located inside a glass capillary along the axis of a cylindrical copper cavity, resonating in the TE011 mode at 9.6 GHz, where the mw electric field has a node. By measuring the variation of the quality factor of the resonant cavity, one can extract the imaginary part of the dielectric constant. At temperatures higher than 230 K we observe an evident increase of the dielectric los…
Constant Power Model in Arm Rotation—A New Approach to Hill’s Equation
2014
The purpose of this study was to further develop the constant power model of a previous study and to provide the final solution of Hill’s force-velocity equation. Forearm and whole arm rotations of three different subjects were performed downwards (elbow and shoulder extension) and upwards (elbow and shoulder flexion) with maximum velocity. These arm rotations were recorded with a special camera system and the theoretically derived model of constant maximum power was fitted to the experimentally measured data. The moment of inertia of the arm sectors was calculated using immersion technique for determining accurate values of friction coefficients of elbow and whole arm rotations. The experi…