Showing papers by "Linköping University published in 1975"

Relationship of the relativistic Compton cross section to the momentum distribution of bound electron states

Abstract: An approximate relativistic treatment of the differential cross section for Compton scattering against bound electron states is discussed. A simple relationship between the cross section and the Compton profile is found. On contrast to previous work this relationship is valid for all scattering angles.

Vestibular and somatosensory inflow to the vestibular projection area in the post cruciate dimple region of the gat cerebral cortex

Abstract: In anesthetized cats 251 cells within the cortical vestibular projection area, adjacent to the post-cruciate dimple, were analyzed as to their input characteristics employing extracellular recording techniques. The post cruciate dimple vestibular field, which is located in area 3a, has a high degree of convergence between vestibular and peripheral somatosensory input. The latter is not restricted to muscle afferents but includes cutaneous modalities. The functional significance of this vestibular cortical projection field is discussed.

Lecithin:cholesterol acyl transfer in plasma of normal persons in relation to lipid and lipoprotein concentration.

Abstract: Information concerning variation in the lecithin :cholesterol acyl transfer (LCAT) rate in normal persons is scanty. We have therefore analyzed the LCAT rate and the lipid and lipoprotein concentrations in the plasma of healthy normolipidemic persons 20–60 years of age, 40 men and 40 women, 10 per decade and sex. Interindividual variation in molar LCAT rate was 57–130 μmol 1−1. h−1 (mean ± 2 S. D.) with no sex difference. Intraindi-vidual variation of molar LCAT rate studied in 8 women and 9 men was shown to be greater than expected from methodological error and was not explainable by the small changes in plasma lipid concentration during the observation period. In the women the molar LCAT rate was lower during the preovulatory phase of the menstrual cycle than during the postovulatory phase. There were positive correlations between the molar LCAT rate and most of the lipid parameters in plasma. By partial correlation analysis a positive correlation was shown between LCAT rate and triglyceride concentrati...

Evaluation of an in vitro assay of lecithin:cholesterol acyl transfer rate in plasma.

Abstract: Crucial and previously criticized points in a slightly modified version of the Stokke-Norum assay of fractional lecithin:cholesterol acyl transfer (LACT) rate in plasma were studied. LCAT activity in the albumin added to the assay medium and negative influence of remaining organic solvent were important sources of error that it was necessary to eliminate. The assumption of equilibration of labeled cholesterol among lipoproteins in vitro was supported experimentally. Addition of isolated chylomicrons had no influence on initial LACT rate. Incubation time was decreased to 20 minutes to obtain a better estimate of initial LCAT rate in normals. Using gas-liquid chromatography to determine unesterified cholesterol concentration, the precision of measurement of molar LCAT rate was 5.2 per cent (coefficient of variation). Molar LCAT rate in healthy males 20-60 years of age was 56-130 mumol-1(-1)-h-1 (mean +/- 2 S.D.) and compared well with reports from other laboratories and in vivo measurements. At present this methodology is considered to be suitable for studies of LCAT and cholesterol turnover in different metabolic situations and clinical materials.

Demonstration of oligoclonal immunoglobulin g in guillain-barré syndrome

Abstract: Elevated concentrations in CSF of the immunoglobulins G, A, and M, when expressed as a percentage of the total protein concentration of CSF, were demonstrated during the initial phase of the course of the disease in a patient with Guillain-Barre syndrome (GBS). A slight elevation of the relative concentrations of IgG and IGM in CSF were also registered later in the course of the disease, at the time when the patient's neurological symptoms were in regression. Multiple discrete IgG bands were demonstrated by agarose electrophoresis in serum and in CSF during the first 2 weeks after onset of the neurological symptoms, and also after week 2 and still during week 12 after onset. The finding of transient oligoclonal IgG in a parient with GBS may suggest stimulation with e.g. viral antigen.

Effects on breathing mechanics and gas exchange of different inspiratory gas flow patterns during anaesthesia.

Abstract: Ten patients without known cardiac or respiratory disease were investigated with breathing mechanics and gas exchange studies during anaesthesia and artificial ventilation. The effects of three different inspiratory gas flow patterns, namely, accelerating, constant and decelerating flows were studied. A decelerating flow resulted in an increase of total compliance when compared to an accelerating or a constant flow. However, at the same time, there was an increase in physiological dead space and a decrease in alveolar ventilation with a decelerating flow compared to an accelerating flow. These results seem to indicate an improved gas distribution in the greater airways with a decelerating flow pattern, but when the total effects of gas exchange were judged, the greatest benefits were with an accelerating flow. ZUSAMMENFASSUNG An 10 Patienten ohne nachgewiesen Storungen der Herz- oder Lungenfunktion wurden in universeller Anaesthesie, bei Kunstlicher Beatmung, Untersuchungen des Gasaustausches undder Atmungsmechanik vogenommen. Wahrend der Inspirationsphase wurde die Wirkung dreier charakteristischer Formen der Gasstromung getestet: akzelerierende, konstante und dezeleriercnde Stromung. Dezelerierende Gasflow resultierete in enicm Anwachsen der Gesamtcompliance im Vergleich mit akzelerierender oder knostanter Stromung. Gleichzeitig erfolgte jedoch auch eine Vergrosserung des pysiologischen Totraumes und ein Abfall der alveolaren Ventilation bei Anwendung dezelerienden Gasstromes im Vergleich mit akzelerierendem. Dese Ergebnisse scheinen auf eine bessere Gasdistribution in den grosseren Luftwegen bei dezelerierender Stromung hinzudeuten, bei Betrachtung der Gesamtwirkung auf den Gasaustausch erwes eine akzelerierende Stromungscharakteristik sich jeodch als vorteilhafter.

Effects on breathing mechanics and gas exchange of different inspiratory gas flow patterns in patients undergoing respirator treatment.

Abstract: In order to investigate the importance of different inspiratory gas flow patterns in respirator treatment, eight intensive care patients were studied with breathing mechanics and five patients also with gas exchange studies. Three different inspiratory gas flow patterns were tested in randomized sequences namely, accelerating, constant and decelerating flow. All three flow patterns were generated by the same respirator. No end-inspiratory pause was used. The results point to a favourable effect on breathing mechanics of a decelerating and a constant flow when compared with an accelerating flow type. However, when the total effects on gas distribution and lung perfusion were evaluated in the gas exchange studies, no significant differences were seen between the three flow patterns. ZUSAMMENFASSUNG An 8 Patienten einer Intensivpflegestation wurden atmungsmechanische und bei 5 dieser 8 Patienten ausserdem Gasaustauschuntersuchungen ausgegfuhrt, um die Bedetung vershiedener Gasflowcharakteristica bei kunstlicher Beatumng wahrend der Inspiration zu erforschen. Drei verschiedene Arten der Gasstromung wurden wahrend der Innspiration in wikklurlicher Reihenfolge getestet: akzelerierende, konstante, und dezelerierende Stromung. Alledrei Stromungsarten urden mit dem gleichen Respirator erzeugt. Eine endinspiratorische Pause kam nicht zur Anwendung. Die Ergebnizsse deuten auf einen gunstigen Effekt von dezelerierenden und konstantem Flow auf die Atmungsmechanik hin. Bei der Bewertung der Gesamtwirkung dieser Flowcharakteristika auf die Gasverteilung und die Lungendurchblutung and Hand der Untersuchungen des Gasaustausches zeigte sich jedoch kein Unterschied zeischen den drei Stromungsarten.

Positional alcoholic nystagmus (PAN) in man following repeated alcohol doses.

Abstract: Flourens (1842), in animal experiments, and Joffroy & Servaux (1897), in man, showed that among other symptoms alcoholic intoxication brought about a nystagmus. Barany (1911) and Barany & Rothfeld (1913) found that this nystagmus was influenced by the position of the head of the test subject. Clinical observations regarding alcoholic nystagmus were made by Frenzel (1939), Plenkers (1943) and Walter (1954).This investigation was supported by the Swedish Medical Research Council, Project 25X-36-03.

Anisotropic Compton Scattering in LiF

Abstract: Both experimental measurement and theoretical calculations of the Compton profiles of LiF indicate a significant anisotropy in the electron momentum distribution whereas published x-ray structure-factor data indicate a lack of anisotropy in the charge density. In this paper we show that momentum distributions can be orders of magnitude more sensitive to anisotropy in the electron distributions than x-ray structure factors, at least in materials where the overlap of the wave functions is small.

The Effect Of Gravity On Positional Alcohol Nystagmus Phase II In Man

Abstract: On request from the Swedish state authorities for health and civil air transport (Socialstyrelsen and Luft-fartsstyrelsen) experiments were performed in order to establish the duration of the vestibular disturbances after alcohol intake related to rules for aviation safety. It is known that the threshold for provocation of positional alcohol nystagmus (PAN) is lowered under the influence of gravity forces above normal. It has been suggested that PAN II could be provoked by g-loads as late as 48 hours after a small alcohol intake. Our experiments were performed in a human centrifuge with g-values 2 and 3. Whisky (43 vol%, 2.5 cc/kg b.w.) was given in a single dose and blood alcohol analyses were frequently taken. The results show that vestibular disturbances appearing as g-provoked PAN II do not persist for any considerable time. Consequently the present limit of 24 hours' sobriety before flight seems sufficient. Positional nystagmus provoked by g-load even without alcohol intake in the test persons is a n...

Blocking characteristics of etidocaine (Duranest).

Abstract: Initial Maximum Initial hlaximum Bilateral ulnar nerve block by means of standardized technique has been used to evaluate the blocking characteristics of the most commonly used local anaesthetic agents, and the method has been shown to give highly reproducible results (LOFSTROM et al. 1970). I t was, therefore, thought to be of interest to evaluate the new local anaesthetic agent etidocaine and compare its blocking characteristics with other modern local anaesthetics. I n the present study etidocaine 0.5 % was selected as being roughly equipotent to bupivacaine 0.25 %, another local anaesthetic giving a long lasting block. Plain solutions and solutions with adrenaline were compared.

Serum enzyme activity of hydroxybutyric dehydrogenase (HBD) and heat inactivated lactate dehydrogenase (LD) after operations on intracranial aneurysms.

Abstract: The relation between clinical signs of parenchymatous cell damage after brain surgery and the serum activity of the LD-isoenzymes determined either as HBD or as heat inactivated LD, has been studied in 44 patients operated upon for intracranial aneurysms. Seven patients had a post-operative increase of the serum enzyme activity above the upper normal limit. All these showed neurological symptoms as compared to only 14% of those who had a postoperative enzyme level within normal limits. This speaks strongly in favour of a relation between the brain cell damage and the increase of the serum activity of the LD-isoenzyme. Since only 15% of the patients had a pathological enzyme level, it is further suggested that an uncomplicated operation for intracranial aneurysm should not cause an increase of the HBD or heat inactivated LD above the upper normal limit.

Cardiovascular and respiratory effects of the beta-adrenoceptive antagonist sotalol: studies in health, angina pectoris and obstructive lung disease.

Abstract: The cardiovascular and respiratory actions of the adrenergic beta adrenoceptive drug sotalol have been studied in an open, short term trial. Fifteen patients with angina performed standardized orthostatic and exercise tests before and after injection of 20 mg sotalol intravenously. Although there was a significant reduction of heart rate and blood pressure at the time of appearance of angina pectoris and ST-segment depression, there was only a slight and statistically insignificant increase in work before the appearance of angina pectoris, and ischaemic changes in the ECG disappeared more rapidly after work.

Interpolation and extrapolation in nonuniform sampling sequences with average sampling rates below the Nyquist rate

Abstract: Coefficients for interpolation and extrapolation, including average sampling rates below the Nyquist rate, have been derived. The method is applicable for nonuniform patterns obtained through omission of samples in a uniform pattern with a sampling rate slightly higher than the Nyquist rate. The interpolations and extrapolations are valid for band-limited signals, except those theoretical signals that are zero valued at all sampling points.

A randomly generated program for automatic identity checking

Abstract: A method for making secret programs for automatic identity checking with very high demands for security, is described. The consistency of the sequence of digits, which identifies the person, is tested by a sequence of transformations, chosen by means of a stored secret random table. The method has been implemented for a system of unattended cash dispenser terminals, equipped with microprocessors.