Showing papers by "Linköping University published in 1980"
TL;DR: It is shown that skeletons can be produced by simple procedures and since these are based on Euclidean distances it is assumed that they are superior to skeletons based on d4−, d8−, and even octagonal metrics.
1,777 citations
TL;DR: The study shows that the Doppler signal is formed essentially by heterodyne mixing of light beams backscattered in static structures and moving red cells.
Abstract: An instrument for measurement of tissue blood flow based on the laser Doppler principle was evaluated using a fluid model. A unique and linear relationship between flowmeter response and flux of red cells was demonstrated with red cell velocities and volume fractions within the normal physiological range of the microcirculatory network of the skin. Different degrees of oxygenation proved to influence the Doppler signal only to a minor extent. The study also shows that the Doppler signal is formed essentially by heterodyne mixing of light beams backscattered in static structures and moving red cells.
1,141 citations
TL;DR: A new instrument for measurement of regional tissue blood flow based on the laser Doppler principle is reported and a differential detector technique is introduced that reduces common-mode noise to a negligible level, without influencing the blood flow related signal.
Abstract: A new instrument for measurement of regional tissue blood flow based on the laser Doppler principle is reported. The theoretical background of light beating spectroscopy is discussed and a detection technique which makes possible the suppression of the adverse effects of laser-mode interference and wide-band beam amplitude noise is described. Instead of using a single square-law photodetector a differential detector technique is introduced that reduces common-mode noise to a negligible level, without influencing the blood flow related signal. The new instrument has proved to be highly stable and sensitive. Continuous recordings of tissue blood flow can be performed in the laboratory as well as at the bedside.
638 citations
TL;DR: The IDB distribution as mentioned in this paper is motivated by mixtures of a set of IFR distributions but can also be given a competing risk interpretation, and the asymptotic gain from classifying failures into two categories is illustrated.
Abstract: A distribution with one scale and two shape parameters is studied. The distribution can describe increasing (I), decreasing (D), constant and bathtub-shaped (B) failure rates. This motivates the working name, IDB distribution. The IDB distribution is motivated by mixtures of a set of IFR distributions but can also be given a competing risk interpretation. For mixed distributions a more general result on the initial slope of the failure rate is given. Asymptotic results for the ML estimation of survival probabilities are given, and when possible compared with ML estimation based on the Weibull, Rayleigh and exponential distributions. Also, the asymptotic gain from classifying failures into two categories is illustrated. One application to real data is given.
244 citations
TL;DR: In this article, it was observed that the line shapes of core levels in photoelectron spectroscopy of Ti, Th, and Ce and some of their intermetallic compounds and lanthanide oxides are directly related to the degree of localization of screening orbitals.
Abstract: It is observed that the line shapes of core levels in photoelectron spectroscopy of Ti, Th, and Ce and some of their intermetallic compounds and lanthanide oxides are directly related to the degree of localization of screening orbitals.
211 citations
01 Jan 1980
TL;DR: In this paper, a general class of parameter estimation methods for stochastic dynamical systems is studied and the class contains the least squares method, output-error methods, the maximum likelihood method and several other techniques.
Abstract: A general class of parameter estimation methods for stochastic dynamical systems is studied. The class contains the least squares method, output-error methods, the maximum likelihood method and several other techniques. It is shown that the class of estimates so obtained are asymptotically normal and expressions for the resulting asymptotic covariance matrices are given. The regularity conditions that are imposed to obtain these results, are fairly weak. It is, for example, not assumed that the true system can be described within the chosen model set, and, as a consequence, the results in this paper form a part of the so-called approximate modeling approach to system identification. It is also noteworthy that arbitrary feedback from observed system outputs to observed system inputs is allowed and stationarity is not required
162 citations
TL;DR: The present magnetic threshold curves show a close resemblance to corresponding curves obtained by electric stimulation at various frequencies provided the electric thresholds are divided by the a.c. frequency.
Abstract: Low-frequency and transient magnetic fields of moderate flux densities are known to generate visual phenomena, so-called magnetophosphenes. In the present study, time-variable very low frequency (10–50 Hz) electromagnetic fields of moderate flux density (0–40 mT) were used to induce magnetophosphenes. The threshold values for these phosphenes were determined as a function of the frequency of the magnetic field both in normal subjects and colour defective ones. Maximum sensitivity occurred at a frequency of approximately 20–30 Hz, and with broad-spectrum light the threshold flux density was 10–12 mT. The threshola values were found to be dependent upon the intensity and the spectral distribution of the background light. Sensitivity decreased during dark adaptation. In certain respects deutans differed from subjects with normal colour vision. Possible mechanisms for generation of magnetophosphenes are discussed. The present magnetic threshold curves show a close resemblance to corresponding curves obtained by electric stimulation at various frequencies provided the electric thresholds are divided by the a.c. frequency. These problems are under current investigation in our laboratory. This is in full agreement with the assumption that the fluctuating magnetic field affects retinal neurons by inducing currents which polarise synaptic terminals.
118 citations
TL;DR: A modified technique of isoelectric focusing on thin‐layer polyacrylamide gel followed by immunofixation with monospecific antisera was used to identify individual cerebrospinal fluid and serum proteins and to define the oligoclonal reaction observed in multiple sclerosis.
Abstract: A modified technique of isoelectric focusing on thin-layer polyacrylamide gel followed by immunofixation with monospecific antisera was used to identify individual cerebrospinal fluid (CSF) and serum proteins and to define the oligoclonal reaction observed in multiple sclerosis (MS). "Normal" IgG gave about 20 to 30 bands at pH 3.5 to 9.5, IgA about 10 bands at pH 3.5 to 6.4, beta-trace protein a smear at pH 3.5 to 8.5, and gamma-trace protein 1 or 2 bands at pH 8.0, 9.5 or both. Up to 11 oligoclonal IgG bands migrating between pH 6.5 and 9.5 were found in CSF from 26 of 27 consecutive patients with MS and also in 20 of the corresponding sera, although at lower numbers and concentrations. In 26 patients, 1 or more of the bands corresponding to normal polyclonal IgG were stronger in CSF than in serum. These data support the hypothesis that two colonies of lymphocytes are activated intrathecally, one of them synthesizing oligoclonal and the other polyclonal IgG. Up to 11 mostly faint bands of free light chains, predominantly of lambda type and migrating between pH 3.5 and 9.5, were found in 8 of 9 CSF specimens from patients with MS.
105 citations
TL;DR: Comparisons between the phosphene types would increase knowledge of the mechanism of the interaction between magnetic fields and electric current, respectively, and excitable tissue, and deviations between the curves may be due to the generation of different current paths in electrical and magnetic stimulation, respectively.
Abstract: The purpose of this study was to compare the threshold values for magnetophosphenes and electrophosphenes under identical experimental conditions. Such comparisons between the phosphene types would increase our knowledge of the mechanism of the interaction between magnetic fields and electric current, respectively, and excitable tissue.
70 citations
TL;DR: In this article, the influence of light scattering on photoacoustic signals is treated and the theoretical and experimental results are compared based on a model in which the photons diffuse through the sample.
Abstract: The influence of light scattering on photoacoustic signals is treated. Theoretical and experimental results are compared. The theoretical results are based on a model in which the photons diffuse through the sample. An equation governing the diffusion process is solved with appropriate boundary conditions. This gives the distribution of photons in the sample. The photoacoustic signal is then calculated and the result is compared with the result for nonscattering samples, giving the influence of the light scattering. The experimental results are obtained by measuring the photoacoustic signal for both scattering and nonscattering samples. The experimental and theoretical results are in good agreement. The differences are mainly due to the incompleteness of the original diffusion theory. An improved theory incorporating internal reflection at the sample surface is also analyzed. The paper illustrates the effects of light scattering on photoacoustic signals. It also shows how to estimate theoretically the photoacoustic signal from a light‐scattering sample.
69 citations
TL;DR: Observations suggest that over and above the smoking and asbestos exposure, heredity may be an important predisposing factor in the genesis of this tumor.
Abstract: A family with a remarkable aggregation of malignant mesothelioma is described. The father, 3 brothers, and a sister all died of the condition. The family and epidemiologic histories are reviewed. Random occupational asbestos exposure in the building industry probably occurred in 4 of the 5 cases. All of the patients were smokers. There is a low incidence of malignant mesothelioma in the area where they resided. These observations suggest that over and above the smoking and asbestos exposure, heredity may be an important predisposing factor in the genesis of this tumor.
TL;DR: The amount of water evaporated from the skin was studied in 10 healthy newborn infants from their first minute of life, while being taken care of in the delivery room, and in 11 infants treated in incubators from their 30th min of life.
Abstract: . Hammarlund, K., Nilsson, G. E., oberg, P. A. and Sedin, G. (Department of Paediatrics, University Hospital, Uppsala, and Department of Biomedical Engineering, Linkoping University, Linkoping, Sweden). Transepidermal water loss in newborn infants. V. Evaporation from the skin and heat exchange during the first hours of life. Acta Paediatr Scand, 69:385, 1980.—The amount of water evaporated from the skin was studied in 10 healthy newborn infants from their first minute of life, while being taken care of in the delivery room, and in 11 infants treated in incubators from their 30th min of life. The heat lost by evaporation, radiation and convection was calculated. Evaporation from the skin was very high during the first minutes after birth and was the main cause of heat loss during the first 15–30 min of life. Thereafter the amount of heat lost depended on the conditions under which the infant was nursed. Higher convective and radiative heat losses were found in delivery rooms than in incubators.
TL;DR: A direct method based on an LU decomposition of the rectangular coefficient matrix for the solution of sparse linear least squares problems and a general updating scheme for modifying the solution when extra equations are added is described.
TL;DR: This paper describes a method to solve large sparse maximum entropy problems with linear equality constraints using Newtons and the conjugate gradient method.
Abstract: This paper describes a method to solve large sparse maximum entropy problems with linear equality constraints using Newtons and the conjugate gradient method. A numerical example is given to introduce the reader to possible applications of entropy models and this method. Some experience from large scale problems is also reported.
TL;DR: Atropine, as a premedication, should be given not later than 30 min before induction of anaesthesia, probably because of uptake of atropine by muscarinic cholinergic receptors.
Abstract: SUMMARY The plasma concentrations of atropine following i.v. or i.m. administration to surgical patients were determined by radioimmunoassay. When atropine sulphate 1 mg was given i.v. there was a rapid initial removal of the drug from the circulation in the first 10 min; thereafter the plasma concentration decreased more slowly. Atropine i.m. was rapidly absorbed with peak concentrations occurring at 30 min following injection. The plasma atropine concentration then decreased slowly, probably because of uptake of atropine by muscarinic cholinergic receptors. The chronotropic effect of atropine appeared to correspond to the concentration in plasma following i.m. administration. We conclude that i.m. atropine, as a premedication, should be given not later than 30 min before induction of anaesthesia.
TL;DR: In this paper, a high-performance liquid chromatographic procedure is described for the quantitative determination of epinephrine, norepinephrine, and dopamine in human plasma, which is based on adsorption of the catecholamines to alumina and, after liberation, separation on a microparticulate bonded strong cation exchange resin and amperometric detection, has been optimized to give complete baseline separation of the substances of interest.
TL;DR: Age, sexual maturation and feeding in flying and non‐flying groups are compared and H. brevipalpis is an effective colonizer of ephemeral waters due to its large dispersal capacity and to the fact that the habitat of juveniles differs from that of adults.
Abstract: Populations of two Helophorus species from a Swedish lake were sampled during the ice-free periods of two years. Dispersing beetles were (rapped in light-reflecting glass traps. Both species are univoltine and breed in the spring. The populations of adult H. brevipalpis are largest during the summer when great numbers emerge and migrate. Very few H. strigifrons adults emerge before spring. Its adult populations are largest in the spring, and small numbers of mature individuals fly with mature H. brevipalpis specimens. This is discussed in relation to their habitat utilization: H. sirigifrons inhabits permanent waters only and is dimorphic for flight musculature. H. brevipalpis inhabits both permanent and ephemeral waters and is always equipped with a functioning flight apparatus. H. brevipalpis is an effective colonizer of ephemeral waters due to its large dispersal capacity and to the fact that the habitat of juveniles differs from that of adults.
Age, sexual maturation and feeding in flying and non-flying groups are compared. Food is seldom found in the gut of fliers of either species. In the spring flying H. brevipalpis females have larger oocytes than non-flying ones; flying H. strigifrons females have smaller oocytes than non-fliers. It is possible that the summer migrations of H. brevipalpis favour outbreeding since fliers are sexually immature; spring fliers, being sexually mature, are more efficient as colonizers.
TL;DR: From the results obtained in this study, magnesium oxide in this dosage cannot be recommended for use in treatment of patients with urolithiasis.
Abstract: Fifteen patients with recurrent renal stone formation were treated with 400 mg magnesium oxide daily. Urine composition was analyzed before the start of treatment and after 6–12 months. The urinary excretion of magnesium before and during treatment was 321±120 (mean ±SD) and 409±140 mmol per mol creatinine respectively, a difference that was not statistically significant. Urinary calcium increased from 473±186 to 662±213 mmol per mol creatinine (p<0.05). All patients who increased their excretion of magnesium also increased the urinary output of calcium and, as a result of this, the calcium/magnesium-quotients were unaffected by the treatment. No significant effect was observed on urine oxalate excretion. Serum concentrations of calcium, magnesium and urate all remained at the pre-treatment level. From the results obtained in this study, magnesium oxide in this dosage cannot be recommended for use in treatment of patients with urolithiasis.
TL;DR: In occupational health epidemiology, the confounding effects of general risk factors such as smoking and alcohol abuse with regard to cancer and other disorders seem to be rather limited.
Abstract: In occupational health epidemiology, the confounding effects of general risk factors such as smoking and alcohol abuse with regard to cancer and other disorders seem to be rather limited. It is desirable to control such risk factors whenever possible, however, but risk ratios of about two or more can rarely be explained by suggesting uncontrolled confounding. However, various general risk factors might modify the effect of an industrial exposure, a phenomenon that sometimes tends to confuse the discussion of etiologic relationships between exposure and outcome.
TL;DR: The purified carbonic anhydrase appeared homogeneous judging from polyacrylamide gel electrophoresis and gel filtration experiments and the circular dichroism spectrum may indicate a somewhat different structural arrangement of aromatic amino acid residues in this enzyme than in the mammalian carbonicAnhydrases.
TL;DR: In this paper, the work function changes introduced by hydrogen on the surface and at the metal-support interface of a thin Pd-film were studied by simultaneous Kelvin probe and C(V)-measurements.
TL;DR: It was found that correction to between 3 and 7 degrees valgus of the varus/valgus deviation (three-point technique) led to the best subjective ratng of the end result by the patients.
Abstract: As a basis for determining the required correction in high tibial osteotomy a measurement of the laterl angle between the axes of the femur and the tibia on standing films is not sufficiently reliable, because the knee can be maintained in various positions through muscular action. When the three-point technique is applied the medio-lateral instability of the knee joint can be determined and by using the varus/valgus deviation as measured in this way the desired correction can be calculated. For this patient series it was found that correction to between 3 and 7 degrees valgus of the varus/valgus deviation (three-point technique) led to the best subjective ratng of the end result by the patients. To compensate for the expected subjective relapse after the operation another 1 or 2 degrees may be added to the angular change at the operation. To avoid an increase in the instability of the knee a lateral capsule reconstruction should be performed.
TL;DR: Knee joints with varus malalignment were examined preoperatively and overcorrection of the varus deformity using random selection showed significantly better results than the normal-correction group.
Abstract: Seventy-eight knee joints with varus malalignment were examined pre-operatively using three-point measurement. Operation was performed with or without 5° overcorrection of the varus deformity using random selection. the overcorrection group showed significantly better results than the normal-correction group.
TL;DR: Changes in bile lipid composition might explain the higher incidence of gallstones in women treated with estrogens.
TL;DR: In this paper, angle-resolved photoemission measurements were performed on the Cr(110) surface at temperatures below and above the N ¼ eel temperature, and the results were compared with previously calculated band structures, and fairly good agreement was obtained assuming direct transitions.
Abstract: Angle-resolved-photoemission measurements were performed on the Cr(110) surface at temperatures below and above the N\'eel temperature. The results are compared with previously calculated band structures, and for the antiferromagnetic phase fairly good agreement is obtained assuming direct transitions. Differences observed in photoemission spectra recorded below and above the N\'eel temperature are discussed in terms of the magnetic phase transition. For the paramagnetic phase the results could not be fully accounted for by calculated bulk band structures; possible explanations of the observed discrepancies are discussed.
TL;DR: In this paper, the results of electronic structure calculations for YOF are presented, making use of Xα-DVM together with experimental X-ray photoelectron and emission spectra for this compound.
TL;DR: A patient who had raised serum and amniotic fluid alpha‐fetoprotein levels at 16 weeks gestation revealed an apparently normal fetus and amniography displayed a soft tissue tumor in front of the fetus, which turned out to be a placental haemangioma when an apparently healthy girl was born at term.
TL;DR: Removal of the impurities, including the hormonal contaminants of insulin, leads to a slow fall in antibodies to insulin and a much faster disappearance of antibodies against acomponent, proinsulin and pancreatic polypeptide.
Abstract: Ninety-two insulin-dependent diabetics (aged 4–20 years, mean±SD: 13±4) with a duration of diabetes from 2 to 17 years (7±3) were transferred from Lente or NPH (5 × crystallised insulin) to Monotard insulin (highly purified insulin). Total serum immunoreactive insulin levels and concentrations of antibodies against insulin, porcine proinsulin, a-component and pancreatic polypeptide were determined prior to [I] and at a mean of 220 [II], 460 [III], 830 [IV], and 1170 [V] days after the change. All but two subjects had insulin antibodies (IgG) at the start, with a mean value of 2864 μU/ml. There was a significant fall in the mean insulin antibody level between [I] and [II] to 2165 μU/ml (p<10-7), followed by an increase between [II] and [III] whereafter a slight decrease was observed being significant between [III] and [IV], as well as between [IV] and [V] (p<0.05); some patients showed a constant fall over the entire period, while others showed fluctuations. Total serum insulin showed a similar pattern, with a mean value of 1141 μU/ml at [I] declining to 522 μU/ml at [V]. The percentage fall between [I] and [V] was greater (54%) than that in the insulin antibodies (30%). Antibodies against acomponent, proinsulin and pancreatic polypeptide were present in 96%, 72% and 41% of the patients respectively before the change in therapy. There was a decline in these antibodies between each sampling (p values between <10-3 and 10-8) and, at the end of the investigation antibodies against a-component were above the detection limit in only 4 patients, and none of the patients showed antibodies against proinsulin or pancreatic polypeptide. Thus, removal of the impurities, including the hormonal contaminants of insulin, leads to a slow fall in antibodies to insulin and a much faster disappearance of antibodies against acomponent, proinsulin and pancreatic polypeptide.
TL;DR: The findings support the assumption that therapeutic failure withβ-blockers in hyperthyroidism may be due to suboptimal treatment, and that individualized dosage of propranolol and metoprolol is necessary.
Abstract: The effects and plasma concentrations of different doses of propranolol and metoprolol were studied in 34 hyperthyroid patients. The initial daily doses were propranolol 160 mg or metoprolol 200 mg. If the resting heart rate remained above 75 beats per min after treatment for 4-7 days, the dose was increased and the patient re-examined after a further 4-7 days. Propranolol (n = 17) caused a reduced heart rate, a decrease in serum 3,3',5-triiodothyronine (T3) and an increase in serum 3,3',5'-triiodothyronine (reverse T3, rT3). In 10 patients, there was no change in T3 or rT3 until the daily dose of propranolol had been increased to 240 or 320 mg. The plasma level of propranolol was significantly correlated with the decrease in T3 and the increase in rT3. Metoprolol (n = 17) caused a reduction in heart rate similar to that following propranolol. However, serum T3 was only slightly reduced even after an increase in dose to 300 or 400 mg, and serum rT3 was not altered. Metoprolol concentrations were not significantly correlated with the fall in T3. It appears that the influence of beta-blockers on T4 conversion is of little importance for the clinical improvement in hyperthyroid patients, and rather it is a consequence of beta 1-adrenergic blockade interfering with the effect of T3. In addition, the findings support the assumption that therapeutic failure with beta-blockers in hyperthyroidism may be due to suboptimal treatment, and that individualized dosage is necessary.
TL;DR: The attitudes towards and motivation for regular physical exercise among juvenile diabetics are estimated by interviewing, giving questionnaires to and using a special attitude test, which reveals more mixed feelings.
Abstract: . Ludvigsson, J., Larsson, Y. and Svensson, P. G. (Department of Pediatrics, University Hospital, Linkoping and Department of Pedagogics, Linkoping University, Sweden). Attitudes towards physical exercise in juvenile diabetics. Acta Paed Scand, Suppl. 283: 106, 1980.—Contrary to our recommendations many juvenile diabetics are inactive and rather negative to physical exercise. We have tried to estimate the attitudes towards and motivation for regular physical exercise among juvenile diabetics by interviewing, giving questionnaires to and using a special attitude test. Different groups have been studied, the largest including 138 diabetics aged 1–21 years with age at onset between 1–16 years (7.3±4.0) and duration of diabetes 1–17 years (5.7±3.6). The results are somewhat divergent comparing different patient groups and when using different methods. Generally teenagers seem to be somewhat more negative. According to direct questions in questionnaires or interviews most patients seem to know that physical exercise is important and very few dislike this part of the treatment. However, the special attitude test reveals more mixed feelings. Many patients mean that it is easy to be theoretically positive, but quite another thing to really exercise regularly. Too often physical exercise becomes a medicine instead of a natural pleasant habit. It is important that the hospital staff inform the patients without nagging, and then support and stimulate the patients, and give them adequate responsibility.