Showing papers by "Linköping University published in 1973"

A Parallel Picture Processing Machine

Abstract: A parallel picture processing machine (PPM) is presented. The proposed machine can perform local operations of both logical and arithmetical character on three by three neighborhoods of digitized pictures. It is essentially a two-dimensional machine but in a restricted sense it can be regarded as three-dimensional. The instruction repertoire is thoroughly discussed and several program examples are presented. In thelast section the implementation of the machine is described and v various tradeoffs between speed and economy are discussed. A dynamically programmable microprogram store is shown to give great freedom in program design.

Urinary excretion of nortriptyline and five of its metabolites in man after single and multiple oral doses

Abstract: The urinary excretion of nortriptyline (NT) and five of its metabolites was studied by quantitative gas chromatography in 22 twins and 7 unrelated healthy subjects after single (1 mg/kg) and multiple oral doses (0.4 mg/kg t.i.d.) of NT hydrochloride. A mean recovery of 62% of the dose was found after both single and multiple doses. The metabolite pattern in the urine was qualitatively and quantitatively identical in the two regimes, but there were marked variations in the pattern of metabolites between individuals. The disappearance rate of NT from the plasma was mainly determined by the metabolism of NT to 10-hydroxynortriptyline, which varied considerably between individuals. The data suggest that in certain rapid NT metabolizers, the upper limit for the overall clearance of NT from the plasma (if extrahepatic metabolism is assumed to be negligible) might be set by the blood flow through the liver.

A new high order method of regula falsi type for computing a root of an equation

Abstract: A hybrid method of order five (eight) which uses three (four) function evaluations per step is presented together with an algorithm which ensures global convergence. The method is compared with its closest competitors (among globally convergent methods which do not use derivatives) in a series of numerical examples. An ALGOL procedure of the method is included.

Prediction of steady-state plasma levels of nortriptyline from single oral dose kinetics: a study in twins.

Abstract: Five identical (monozygotic) and 6 fraternal (dizygotic) sets of healthy twins between 47 and 53 years of age were given a single oral dose of nortriptyline (NT) hydrochloride 1 mg/kg. The plasma half-life, the apparent volume of distribution, and the plasma clearance of NT were estimated for each subject as well as the urinary excretion rate of conjugated and unconjugated 10-hydroxynortriptyline (10-OH-NT). “Steady-state” plasma levels predicted from the reciprocal single dose plasma clearance rate of NT agreed well with those observed in a previous study of the same twins 2 years previously. In the present study, there was a 5-fold range of the plasma half-lives and 2-fold variation in the apparent volume of distribution of NT (assuming complete availability on oral administration). No correlation was found between the plasma half-life and the apparent volume of distribution. Analysis of variance showed that most of the variability between persons in plasma half-life, apparent volume of distribution and conjugation of 10-OH-NT was genetically determined. The plasma half-life and apparent volume of distribution may contribute independently to the total interindividual variability of the “steady-state” plasma level of NT.

The availability of orally administered nortriptyline

Abstract: The availability of an orally administered drug may be defined as the fraction of the total dose that enters the blood. Three healthy subjects were given identical doses of nortriptyline hydrochloride (NT-HCl) by the oral and intramuscular routes. The availability was assessed by comparing the total areas under the NT plasma concentration-time curves produced by the two methods of administration. The concentrations of NT in plasma and blood were determined by gas chromatography — mass spectrometry and were found to be almost identical. The observed availability of NT in these subjects ranged between 56 and 70% (mean 64%). The availability predicted from the parenteral plasma levels (assuming an average hepatic blood flow of 1.7 l/min) differed from the observed availability in one subject, perhaps because of the known variation in liver blood flow between individuals. The gastrointestinal absorption of NT-HCl was complete, since the recovery of the main metabolite, 10-hydroxynortriptyline, was the same after the two routes of administration. Pharmacokinetic analysis of the data showed that there might exist interindividual differences in the apparent volume of distribution of NT, (Vd)β. There was no apparent relationship between the variations in availability of NT and “steady-state” plasma levels or the disposition plasma half-lives of the drug. The calculated (Vd)β and (t 1/2)β of NT for each subject were in good agreement with those obtained from a previous study of single oral does of NT.

Vestibular and auditory cortical projection in the guinea pig (Cavia porcellus).

Abstract: Isolated electrical stimulation of the vestibular nerve in the guineapig yielded surface positive evoked potentials within the rostral portion of the SI forelimb field. The locus of negative field potential reversal in deeper cortical layers was small. The vestibular field is distinct from those of the auditory and facial nerves. Comparative aspects of vestibular cortical location are discussed. The auditory field corresponds with that of other rodents.

A fast algorithm for optimum linear predictors

Abstract: An algorithm is given for calculation of the time-varying-coefficients of the linear least squares predictors for stationary processes. The algorithm requires an order of magnitude fewer arithmetic operations than the best of the earlier known algorithms.

Different flow patterns and their effect on gas distribution in a lung model study.

Abstract: A two-compartment lung model was ventilated with three different inspiratory flow patterns. Gas distribution to the two lung compartments, maximum insufflation pressure, inspiratory gas flow and total inspiratory work were measured using accelerating, constant and decelerating gas flow, with and without an end-inspiratory pause. Respiratory frequency, minute volume and the degree of tracheal stenosis were varied. A decelerating flow resulted in the most even distribution, and constant flow was superior to accelerating flow. An improvement in distribution was seen with a low respiratory frequency and a small minute volume. Maximum insufflation pressure was lower with constant and decelerating flow in the high and low obstructive groups, respectively. Inspiratory gas flow and power were at their lowest with a constant flow pattern. Inspiratory work varied only slightly and inconsistently among the three flow types. ZUSAMMENFASSUNG Ein zwei-abteiliges Lungenmodell wurde mit drei verschiedenen inspiratorischen “Flow”-Arten ventiliert. Die Gasverteilung in den beiden Lungenabteilungen, der maximale Insufflationsdruck, der inspiratorische Gas-“Flow” und die gesamte Einatmungsarbeit wurden unter akzelerierendem, konstantem und dezelerierendem Gasstrom mit und ohne endinspiratorischer Pause gemessen. Die gleichmassigste Gasverteilung resultierte aus einem dezelerierenden “Flow”. Der konstante Gasstrom war diesbezuglich noch dem akzelerierenden uberlegen. Eine Verbesserung der Gasverteilung wurde bei niedriger Frequenz und einem kleinen Minuten-Beatmungsvolumen gesehen. Der maximale Insufflationsdruck war bei konstantem und dezelerierendem “Flow” niedriger und zwar sowohl bei hohen als auch bei niedrigen Obstruktionen. Inspiratorischer Gasstrom und Atemarbeit waren am niedrigsten bei konstantem “Flow”. Die inspiratorische Arbeit variierte nur geringfugig und inkonstant zwischen den drei Beatmungstypen.

Disintegration of cells and protein recovery

Abstract: In order to prepare intracellular substances from microorganisms the barrier of the cell envelope has to be disrupted. Since this barrier is usually very resistant, the methods available for the preparation of substances with unstable activity are restricted due to the inactivation occasioned by some disintegration processes. Some methods, usually applying physico-mechanical shearing stress, are inherently well suited to disintegrate cells to release unstable substances. In other cases, when more inert substances like e.g. nutrients are prepared from microbes, denaturing treatments like cell envelope disruption by heating followed by enzymatic dissolution of the protoplasm may be advantageous. Some recent results with disintegration by freeze-pressing are described. Procedures giving selective release of certain cell constituents and ways to influence the yield qualitatively are also reported.

Surgical treatment of hydronephrosis by the Anderson-Hynes method.

Abstract: During the period 1959–1968, 23 patients underwent surgery by the Anderson-Hynes technique for hydronephrosis. In 18 patients no mechanical cause of the disease was found, and 16 of these patients were followed up over a long period of time. The results, evaluated from subjective symptoms, occurrence of urinary tract infection and prolonged urography, were good.

Contact between a curved viscoelastic beam and a rigid plane

Abstract: The following problem has been analysed by the theory of small deflections of bending. A circularly curved beam of Maxwell material is pressed against a rigid horizontal plane by two constant and concentrated forces P, each acting on one end of the beam.Before loading there is contact only at the mid-point of the beam. As load is applied the Maxwellian beam behaves like a Hookean beam. If the load P is below a critical value Pc, there is contact only at the mid-point, but if the load exceeds this value, linear contact is formed along a certain length 2λ° of the beam.At the time t the beam will rise from the support over a distance of 2λ° (t) if the load P exceeds Pc, while if P is less than Pc there will be a similar deflection only after a critical time tc. The contact pressure is two concentrated forces, acting on each contact point.Expressions for the deflections w(O,t) and w(L, t) of the centre and the ends of the beam are also derived and are compared with corresponding expressions for a Hook...