The biomechanical effects of the inclusion of a torque absorber and type of knee units on trans-femoral amputee gait

This paper reports on a pilot study investigating the effects on the gait of two transfemoral amputees of to the inclusion of a torque absorber (TA) and its location relative to the knee unit. Both subjects carried out gait tests with a prosthesis with no TA with, a TA proximal to the knee unit and with a TA distal to the knee unit. Three-dimensional gait analysis was carried out to establish the kinematic and kinetic gait parameters of both the prosthetic and sound side. It was found that the TA did not significantly affect the sagittal kinetic and kinematic parameters of the sound or the prosthetic side. However, for one subject the axial rotation of the socket relative to the foot was significantly greater with the TA. It was concluded that by using the methodology of this pilot study, it is possible to investigate the rotations in the transverse plane within the prosthetic limb and pelvis. Further, including a TA may reduce the relative motion between the stump and the socket and therefore may decrease skin breakdown due to diminished shear force

Inhomogeneous Quantum Walks

We study a natural construction of a general class of inhomogeneous quantum walks (namely walks whose transition probabilities depend on position). Within the class we analyze walks that are periodic in position and show that, depending on the period, such walks can be bounded or unbounded in time; in the latter case we analyze the asymptotic speed. We compare the construction to others in the existing literature. As an example we give a quantum version of a non-irreducible classical walk: the Polya Urn.Comment: 11 page

Automated injection of slurry samples in flow-injection analysis

Two types of injectors are described for introducing solid samples as slurries in flow analysis systems. A time-based and a volume-based injector based on multitube solenoid pinch valves were built, both can be characterized as hydrodynamic injectors. Reproducibility of the injections of dispersed solids ( 150 ¿m) was tested with several concentrations of slurry samples up to 30 mg/ml; the injected volume was 1 ml. For both injectors dye and slurry samples could be injected with good precision (relative standard deviation for the peak area less than 2%). Peak detection was performed turbidimetrically. Data analysis and operation of the injectors were automated. The usual peristaltic pumps in flow analysis are normally not capable of handling slurries of the type investigated, therefore a valveless piston pump was used instead

Normal mere exposure effect with impaired recognition in Alzheimer’s disease.

We investigated the mere exposure effect and the explicit memory in Alzheimer’s disease (AD) patients and elderly control subjects, using unfamiliar faces. During the exposure phase, the subjects estimated the age of briefly flashed faces. The mere exposure effect was examined by presenting pairs of faces (old and new) and asking participants to select the face they liked. The participants were then presented with a forced-choice explicit recognition task. Controls subjects exhibited above-chance preference and recognition scores for old faces. The AD patients also showed the mere exposure effect but no explicit recognition. These results suggest that the processes involved in the mere exposure effect are preserved in AD patients despite their impaired explicit recognition. The results are discussed in terms of Seamon et al.’s proposal (1995) that processes involved in the mere exposure effect are equivalent to those subserving perceptual priming. These processes would depend on extrastriate areas which are relatively preserved in AD patients

A generalized approach for the calculation and automation of potentiometric titrations Part 2. Redox Titrations

The very fast calculation procedure described earlier is applied to calculate the titration curves of complicated redox systems. The theory is extended slightly to cover inhomogeneous redox systems. Titrations of iodine or 2,6-dichloroindophenol with ascorbic acid are described. It is shown that correspondence between theory and practice is good as long as the relevant stability constants and redox potentials are known with sufficient accuracy

A generalized approach for the calculation and automation of potentiometric titrations Part 1. Acid-Base Titrations

Fast and accurate calculation procedures for pH and redox potentials are required for optimum control of automatic titrations. The procedure suggested is based on a three-dimensional titration curve V = f(pH, redox potential). All possible interactions between species in the solution, e.g., changes in activity coefficients and influences of redox potential on pH variations, are taken into account. The number of titrant additions can be reduced considerably without loss of precision, by using the fact that the pH of a protolyte or mixture of protolytes at some fraction titrated does not depend strongly on the actual concentration

Processing of signals from an ion-elective electrode array by a neural network

Neural network software is described for processing the signals of arrays of ion-selective electrodes. The performance of the software was tested in the simultaneous determination of calcium and copper(II) ions in binary mixtures of copper(II) nitrate and calcium chloride and the simultaneous determination of potassium, calcium, nitrate and chloride in mixtures of potassium and calcium chlorides and ammonium nitrate. The measurements for the Ca2+/Cu2+ determinations were done with a pH-glass electrode and calcium and copper ion-selective electrodes; results were accurate to ±8%. For the K+/Ca2+NO−3/Cl− determinations, the measurements were made with the relevant ion-selective electrodes and a glass electrode; the mean relative error was ±6%, and for the worst cases the error did not exceed 20%