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  • 1970-1974  (645)
  • 1965-1969  (64)
  • 1850-1859
  • Engineering  (521)
  • Electron Microscopy
  • 1
    ISSN: 1434-4726
    Keywords: Spiral ganglion and Organ of Corti ; Electron Microscopy ; Influence of Different Fixatives and Fixation Methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das Ganglion spirale und Cortische Organ des Meerschweinchens wurden nach Osmium- und kombinierter Glutaraldehyd-Osmiumfixation sowie Anwendung verschiedener Fixationsmethoden elektronenmikroskopisch untersucht. Die Strukturen des Cortischen Organs wurden hierbei nicht wesentlich beeinflußt. Am Ganglion spirale ergaben sich Unterschiede im Aufbau der Myelinhüllen der Ganglienzellen. Es wird diskutiert, daß es sich beim semikompakten Myelin um ein Artefakt der Osmiumfixation handelt und daß Glutaraldehyd den Aufbau der Myelinhüllen im Bereich der Spiralganglienzellen naturgetreuer wiedergibt als Osmium.
    Notes: Summary We have been examining with the electron microscope the spiral ganglion and the organ of corti in guinea pigs, using osmium and a combined glutaraldehyde-osmiumfixation together with various fixation techniques. The structures of the organ of corti were not considerably effected. Differences in the structure of the myelin sheets of ganglion cells were found in the spiral ganglion. Presumably the semicompact myelin represents an artefakt after osmium-fixation, glutaraldehyde being able to demonstrate clearer the structure of the myelin sheets on spiral ganglion cells compared to osmium.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 16 (1974), S. 109-127 
    ISSN: 1432-0827
    Keywords: Dentinogenesis ; Diphosphonates ; Calcification ; Collagen ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of high doses of ethylene-1-hydroxy-1,1-diphosphonate (EHDP) were investigated at the light microscopic and subcellular level. The administration of EHDP at a concentration of 7.5–10 mg P/kg body weight/day over a short period of time resulted in complete inhibition of crystal formation in predentin and pre-enamel. An increased predentin width was observed and within newly-formed predentin areas the formation ofcollagen fibrils was grossly disturbed. In addition, fine precipitates appeared in the ground substance. The presence of unusual thread-like elements within specific bodies in the cytoplasm of the odontoblastic processes may be indicative of an interference by EHDP in e.g. the synthesis of precollagen. The possibility of an inhibition by EHDP of the extracellular aggregation of collagen molecules is also discussed. EHDP further inhibited crystal formation within dentinal globules. Functioning ameloblasts were grossly affected in EHDP-treated rats, and it is suggested that this is related to an inhibition of crystal formation in pre-enamel.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 364 (1974), S. 111-127 
    ISSN: 1432-2307
    Keywords: Electron Microscopy ; Coronary Arteries ; Atherosclerosis ; Aging ; Smooth Muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The coronary arteries were studied by electron microscopy in normal rats weighing 65 to 535 gm; fixation was accomplished by perfusion for 20 min at 110–130 mm Hg. In rats of all ages (but especially in the oldest) the arterial wall contained deposits of abnormal intercellular material, consisting of granules, vesicles, myelin figures and other debris. These deposits were present in the intima and media, but rare in the adventitia; there was suggestive evidence that medial cells phagocytized some of the material. The adventitia was characterized by 1–4 layers of cells with extremely thin protoplasmic expansions wrapped around the vessel (“veil cells”) and containing lysosome-like bodies as well as phagosomes. These findings, taken as a whole, suggest the following sequence of events. During normal life, the media produces cellular debris, by cell death as well as by fragmentation of cellular processes; part of these debris are phagocytized by smooth muscle cells, part diffuse outward to the adventitia where they are taken up by specialized cells (the “veil cells”). However, due to relative inadequacy of phagocytosis in the media, the debris continue to accumulate and form intercellular deposits that increase with age. It is possible that this natural phenomenon may by itself set a maximal limit to the life-span of the arterial wall.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 363 (1974), S. 249-258 
    ISSN: 1432-2307
    Keywords: Hypertensin (Angiotensin) ; Catecholamins ; So-Called Epinephrine Myocarditis ; Rat Heart ; Optical Microscopy ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pathomorpliological comparative studies on structural damage to rat cardiac muscle following administration of hypertensin and arterenol, with and without pretreatment with reserpine to empty the catecholamine reserves were performed. The question is whether and to what degree angiotensin induced cardiac damage, which is viewed microscopically as the so-called epinephrine myocarditis, can be regarded as an indirect catecholamine effect. The following could be deduced: 1. Hypertensin causes a damage pattern similar to that of arterenol as seen under the light microscope and corresponds to the so-called epinephrine myocarditis. 2. The electron microscope demonstrates definite differences in the pattern of damage to the myocardium: hypertensin affects primarily the mitochondria, while arterenol affects the myofibrils. 3. Hypertensin and arterenol damage mainly the subendocardial tissue of the left heart: hypertensin affects more the region of the base of the left ventricle, arterenol more the region of the left ventricle apex. 4. Pretreatment with reserpine blocks the damaging effects of hypertensin in the rat heart for 12 hours. After 24 hours the full picture of the damage pattern has reappeared. Arterenol is lethal to animals pretreated with reserpine. 5. The pathogenesis of the damaging effects of hypertensin on rat cardiac muscle is discussed.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 27 (1974), S. 201-213 
    ISSN: 1432-0533
    Keywords: Infantile Neuroaxonal Dystrophy ; Spheroids ; Perikaryon ; Electron Microscopy ; Membranous Profiles ; Dense Bodies ; Protein Syntheses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electron microscopic findings of a cortical biopsy from a four-year-old child suffering from muscular weakness and psychomotor retardation are presented. Morphological evidence obtained in this study suggests a unique pathogenetic mechanism underlying INAD. The spheroids appear to be caused by an accumulation of a macromolecular substance synthesized in the neuron and transported to the nerve endings. The abnormal substance initially takes the form of an amorphous material, it eventually aggregates into highly characteristic angulated membranous profiles. The selective involvement of the nerve endings, synapses and motor end plates in this disease suggests a derangement of the metabolic pathway in the synthesis or packaging of the neurotransmitters or their receptors.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 30 (1974), S. 271-276 
    ISSN: 1432-0533
    Keywords: Intracranial Teratoma ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A massive congenital benign teratoma grossly replacing the cerebral hemispheres has been examined by light and electron microscopy. The tumor contained tissues derived from all three germ layers. The cerebellum showed morphological features suggesting a state of maturation equivalent to that of 20 to 25 weeks of gestation. The tumor is discussed in the light of present theories on the pathogenesis of teratomas.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 27 (1974), S. 43-53 
    ISSN: 1432-0533
    Keywords: Oncocytes ; Adenohypophysis ; Pituitary Adenoma ; Secretory Granules ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A light and electron microscopic study was undertaken on 3 surgically removed non-tumorous adenohypophyses and 16 pituitary adenomas. Numerous oncocytes have been found in 2 non-tumorous adenohypophyses and in 6 pituitary adenomas including 1 chromophobe adenoma which was composed almost exclusively of oncocytes. Thus, it seems that the occurrence of oncocytes in the anterior pituitary cannot be considered a rare finding. The distinctive feature of oncocytes is the abundance of mitochondria in their cytoplasm. This alteration can be so extensive that the entire cytoplasm is filled with mitochondria leaving only a small area for the remaining cytoplasmic organelles. Oncocytes arise from adenohypophysial cells. This transformation is gradual and is not restricted to one particular cell type. In the early phases of development of oncocytes the secretory granules are well preserved. Thus, hormone secretion is presumably maintained. It seems conceivable, however, that in the more advanced phases of evolution of oncocytes, when the secretory granules decrease in number, hormone production is diminished or stopped. Further investigations are, however, required to elucidate in detail the functional activity of oncocytes. It remains to be established whether mitochondrial accumulation is principally due to increased formation or delayed breakdown. As some mitochondria show signs indicating division it appears that multiplication of mitochondria is the underlying mechanism resulting in their significant increase. However, the possibility cannot be excluded that the life span of mitochondria is prolonged and mitochondrial longevity plays an important role in causing transformation of adenohypophysiocytes into oncocytes.
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  • 8
    ISSN: 1432-0533
    Keywords: Progressive Multifocal Leukoencephalopathy ; Hirano Bodies ; Papova Virus ; Paramyxovirus-like ; Nuclear Bodies ; Electron Microscopy ; Neurofibrillary Tangles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have identified three structures that have not previously been reported in electron microscopic examinations of brain from patients with PML: 1. coiled nuclear bodies that may possibly represent tubular paramyxovirus nucleocapsids, 2. Hirano bodies and 3. Neurofibrillary tangles. The paramyxovirus-like material is interesting in view of reports of a transition between nuclear bodies and tubular paramyxovirus nucleocapsids and because of a possible interaction between syncytiogenic paramyxoviruses and Papova viruses in the pathogenesis of SSPE and PML. A study of the Hirano bodies in this case, taken in conjunction with the findings of others leads us to believe that these structures are formed from an overgrowth of neurofilaments. The presence of tangled masses of neurofilaments in the processes of neurons also seen in the present case is consistent with this hypothesis.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 28 (1974), S. 93-103 
    ISSN: 1432-0533
    Keywords: Hexachlorophene Intoxication ; Toxic Encephalopathy ; Optic Nerve Necrosis ; Cerebral Edema ; Status Spongiosus ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This is the first report of neuropathologic findings following oral ingestion of hexachlorophene in the human. The patient was a 7 year old boy who accidentally ingested 45 ml (approx.) of pHisoHex (hexachlorophene).Toxic reactions included nausea, vomiting, anorexia, diarrhea, decrease in visual acuity, blurred vision blindness, somnolence and disorientation. He developed cardiac arrhythmia, fever, isoelectric EEG and finally respiratory and cardiac arrest 61 h after admission. Autopsy findings showed interstitial myocarditis, pneumonitis and acute bronchiolitis. The brain was edematous. Light microscopy revealed mild diffuse vacuolization of white matter, occasional neuronal degeneration, most prominent on deepest layers of the visual cortex. Disintegration of myelin sheaths and necrosis of axon cylinders were present throughoutoptic pathways. Electron microscopy revealed large, empty extracellular and intramyelinic spaces formed by splitting and separation of the myelin lamellae. These changes are known to occur in experimental animals intoxicated with hexachlorophene, triethyltin, isonicotinic acid hydrazide and cuprizone. However, with respect to hexachlorophene, the localization of lesions to be optic pathways appears to be dependent upon an oral route of administration.
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  • 10
    ISSN: 1432-0533
    Keywords: Neuroaxonal Dystrophy ; Infantile Autonomi Nervous System ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The autonomic nervous system is studied by electron microscopy for the first time in two siblings born of North African consanguineous parents and affected by infantile neuroaxonal dystrophy. The changes already reported in dystrophic axons of the central and peripheral nervous system, are seen in the myenteric plexus of rectum mucosa. The authors stress the diffuse involvement of the nervous tissue in this degenerative disorder of still unknown nature.
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  • 11
    ISSN: 1432-0533
    Keywords: Craniopharyngioma ; Tissue Culture ; Electron Microscopy ; Enzyme Histochemistry ; Keratine ; Enamel ; Rosenthal Fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electron optical and enzyme histochemical investigations carried out on four craniopharyngiomas and their tissue cultures demonstrated that the tumour elements are keratinizing epithelial cells, plenty of tonofilaments, glycogen granules, mitochondria and desmosomes. Their ultrastructural and histochemical characteristics are the same in every part of the tumour (solid; cystic; “adamantinoma-like”). In the keratinizing cells, the reactions for non-specific esterases were high positive. The ultrastructural characteristics of the tumour cells grownin vitro are the same as thosein situ; the cells remain attached to one another by desmosomes and retain their capacity to produce keratine. This therefore seems to be a primary characteristic of the tumour cells and not a secondary dysmetabolic disturbance. Calcium was found onlyin situ. That the tumour cells may produce enamelin situ seems to be possible, but it could not be confirmed with certainty. The glial proliferation which is always presentin situ, is reactive and not neoplastic; thein vitro new built cell colonies consist only of epithelial elements.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 29 (1974), S. 45-55 
    ISSN: 1432-0533
    Keywords: Experimental Neural Tumours ; Ethylnitrosourea ; Electron Microscopy ; Lysosomes ; Acid Phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A single intravenous injection of 30 mg of N-ethyl-N-nitrosourea per kg of body weight was administered to pregnant BD-IX rats on the 15th day of gestation. The neural tumours which developed in 97.5% of the offspring were gliomas and schwannomas. The demonstration of acid phosphatase in the neoplastic and reacting cells of these tumours was carried out at fine structural level. The enzyme activity was localised in lysosomes and in the innermost cisternae of the Golgi complexes. High acid phosphatase activity was related not only to degeneration, necrosis and phagocytosis but also to cellular differentiation and anaplasia.
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  • 13
    ISSN: 1432-0533
    Keywords: Steele-Richardson-Olszewski Syndrome ; Progressive Supranuclear Palsy ; Neurofibrillary Tangles ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The neurofibrillary tangles found in the neurons of a case of Steele-Richardson-Olszewski syndrome were studied by electron microscopy. Both the flame-shaped and globose type of tangles were present. The neurofibrillary tangles were composed of bundles of straight tubules measuring approximately 150 Å in diameter. This ultrastructural appearance of the tangles in Steele-Richardson-Olszewski syndrome is different from the appearance of tangles found in other neurological disorders and is probably indicative of intraneuronal accumulation of a new type of fibrous protein.
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  • 14
    ISSN: 1432-0533
    Keywords: Polyneuropathy Associated with Adie's Syndrome ; Sural Nerve ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The sural nerve of a woman of 35 with chronic polyneuropathy and Adie's syndrome was examined by electron microscopy. Myelinated nerve fibres were absent and there was marked reduction in the number of unmyelinated fibres. Onion bulb formation was not observed. Collagen fibres occupied the intercellular spaces.
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  • 15
    ISSN: 1432-0533
    Keywords: Experimental Neural Tumours ; Ethylnitrosourea ; Electron Microscopy ; Thiamine Pyrophosphatase ; Adenosine Triphosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structural localisation of thiamine pyrophosphatase and adenosine triphosphatase was carried out in gliomas and schwannomas induced transplacentally by N-ethyl-N-nitrosourea. The activity of thiamine pyrophosphatase was observed in the Golgi complexes and appeared to be directly related to cellular differentiation and reactive changes. The Mg2+-dependent adenosine triphosphatase was localised at the cell membrane, in the pinocytotic vesicles of various cells and in the basement membrane of some capillaries. This enzyme, showing high activity in differentiated cells, indicated the activity of membrane-bound cellular transport.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 29 (1974), S. 211-222 
    ISSN: 1432-0533
    Keywords: Experimental Gliomas ; Ethylnitrosourea ; Electron Microscopy ; Virus-like Particles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two unusual, intracytoplasmic structures, resembling viruses, are described in experimental gliomas which were induced transplacentally on the 15th day of gestation in BD-IX rats by a single intravenous injection of 30 mg of N-ethyl-N-nitrosourea per kg of body weight. These structures are tubules within the lumen of the endoplasmic reticulum and large coated vesicles in the Golgi region. The tubules are of indeterminate length and have inner and outer walls of 9–11 nm and 20–22 nm respectively. The large coated vesicles are 80–90 nm in diameter and their outer surface is covered by regular, equidistant spikes of 12–15 nm in length. The vesicles are closely related to the Golgi complexes, from which they appear to originate. The intracisternal tubules and large coated vesicles share certain morphological features both with viruses and with normal cell organelles. The origin and significance of these structures are discussed.
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  • 17
    Electronic Resource
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    Springer
    Acta neuropathologica 30 (1974), S. 315-328 
    ISSN: 1432-0533
    Keywords: Human Adenovirus Type 12 ; Sprague-Dawley Rats ; Intracerebral Inoculation ; Medulloepitheliomatous Neoplasm ; Giant Tumor Cells ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Solid medullary brain and spinal cord neoplasms developed in all 10 offspring of an outbred Sprague-Dawley rat, between 37 and 99 days after a single postnatal (within 24 hrs) inoculation of 0.05 ml of human adenovirus type 12, 103.5–104.5 TCID50 HeLa cells/0.1 ml in the left frontal lobe. Seven rats developed multicentric neoplasms in both hemispheres and in peri-aqueductal areas of the brain stem, one of which was associated with an incipient spinal cord tumor in the sacral segment. One rat developed a solid tumor involving the right parieto-occipital region. The remaining two cases were solid spinal cord tumors arising from the dorsal half of the thoracolumbar segments. The remarkably uniform microscopic appearance was designated as a counterpart of human embryonic neuronal neoplasms. Characteristic neuronal and multinucleated giant cells emerged throughout the tumor tissue with argentaffine, neurofibril-like cytoplasmic expansions and a unique cilium (a 9+0 pattern of tubules) associated with a pair of centrioles. This cilium morphology was also a hallmark of the majority of tumor cells that formed characteristic pseudorosettes. The occasional emergence of two sets of cilia and centrioles in monstrous cells suggested probable modes of cytogenesis in relation to cessation of abnormal cell division.
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  • 18
    Electronic Resource
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    Springer
    Acta neuropathologica 30 (1974), S. 33-41 
    ISSN: 1432-0533
    Keywords: Organic Mercury Compound ; Late Pathological Changes in Peripheral Nerves ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Wistar strain of male rats of 100–110 g were used, 5 for an experimental and 5 for control group. 1 mg of organic mercury (methyl methylmercuric sulfide: CH3HgSCH3) was given by mouth each day for 10 days (total dose 9–10 mg) to the experimental group. 600 days afterwards the experimental and control rats were killed. Only the peripheral nerves showed changes, small myelinated nerve fibres with thick myelin sheaths in groups. Around these fibres occurred extremely small myelinated nerve fibres and isolated large unmyelinated fibres, and appeared to be regenerated fibres. Destruction of myelin sheaths and cavity formation in the axons were observed in these fibres. The changes in the axons were remarkable at the nodes of Ranvier.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 30 (1974), S. 11-24 
    ISSN: 1432-0533
    Keywords: Ataxia ; Rabbit ; Degeneration ; Cochlear Nuclei ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This hereditary animal ataxia is selective in its sites of involvement within the nervous system, which include principally the central cerebellar, vestibular and cochlear nuclei. Ultrastructural detail has been described for central cerebellar and vestibular nuclei. Herein the cochlear complex of 18 rabbits with this ataxic condition (ax/ax from the strain AX of the Jackson Laboratory) have been examined. The gene is a lethal one, but the animals were used before they became moribund and between 7 and 57 days after the onset of symptoms. By light microscopy nine cell types (Osen, 1969a, b; 1970) have been identified in the cochlear nuclei of the cat. That distribution can also be identified in electron micrographs of rabbit cochlear nuclei, providing there is a singular opportunity to compare cellular vulnerabilities within the ataxic condition, and establish the principal features of associated neuropil alterations. The cochlear nuclei, cerebellar cortex and central nuclei, and the vestibular nuclei, arise from the ependyma of the rhombic lip of the fourth ventricle, making them close allies in their genetic origins. Pathological alterations were evident in scattered neurons from all nuclear sources by 7–15 days following symptom onset. At 15 days the number of altered neurons evident in electronmicrographs had increased markedly, cells becoming involved at a more rapid pace than those already affected could be removed. Much glycogen is evident from 7 days onwards in both neuropil and neurons. It occurs in considerable amounts in astrocytic processes and less abundantly in endbulbs and somata. By 20 to 25 days spongioform changes in neuropil are prominent, and thereafter the extracellular spaces coalesce to produce a lacunar appearance showing little glycogen. It would appear, therefore, that all neuron types, the endbulbs, and the astrocytic processes are markedly involved simultaneously in the spongioform transformation which features this type of ataxia. Involvement of cochlear nuclei only differs in pathological detail from that found at the other involved sites, and the differences seen relate principally to the architectonics of the nuclei, including size and density of the packing of contained elements.
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  • 20
    Electronic Resource
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    Acta neuropathologica 30 (1974), S. 155-173 
    ISSN: 1432-0533
    Keywords: GM1-Gangliosidosis ; Glycoproteins ; β-Galactosidase ; Lysosomal Disease ; Electron Microscopy ; Genetics of GM1-Gangliosidosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Post-mortem studies on a 6-year old boy with GM1-gangliosidosis, Type II revealed no evidence of accumulation of residual bodies nor of gangliosides or glycoproteins in liver and spleen. In brain tissue the ganglioside GM1 accounted for 70% of the ganglioside fraction and ganglioside-NANA was increased 3.6 fold over controls. In addition, the brain tissue contained large amounts of glycoprotein, glycoprotein derived galactose being increased 2.5 times. The neuronal accumulation of tertiary lysosomes exhibited a characteristic distributional pattern: in general the large neuronal perikarya were more consistently involved with the exception of the motor cells of the cranial nerve nuclei, III, IV, and VI. In addition to characteristic MCB's, the nerve cells contained residual bodies with a granulo-floccular matrix, presumed to represent glycoproteins. The distribution of the mutant gene was studied among 30 blood relatives of the proband at risk and 6 carriers could be ascertained on the basis of a reduced leukocytic β-galactosidase activity. The partly purified enzyme from the patient's liver revealed 20% activity as compared to that of normal controls. All three fractions obtained by DEAE cellulose column chromatography exhibited markedly reduced activity at pH 3.6, but nearly normal activity at pH 6.6. The reduced activity corresponded to the B component of the enzyme as shown by electrophoretic separation. It is pointed out that this case cannot be diagnosed as “generalized gangliosidosis” for the process of ganglioside accumulation was restricted to nervous tissue.
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  • 21
    Electronic Resource
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    Acta neuropathologica 30 (1974), S. 189-196 
    ISSN: 1432-0533
    Keywords: Lafore Bodies ; Polysaccharidosis ; Electron Microscopy ; Epilepsia ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cerebral biopsies of three patients aged 22, 18 and 16 years with myoclonic epilepsy contained Lafory bodies. Two were a brother and sister of consanguineous parents. The Lafora bodies occurred in most neurons but not in glial cells. The ultrastructure of these bodies showed a fibrillar and granular material in the perikaryon and neuropile. In some neurons small Lafora bodies were delimited by a double membrane, suggesting that in early phases they have a membrene which disappears when they become more developed. Other non-specific neuron alterations are described. One of the cases presented in the liver PAS positive bodies of a structure different from the Lafora bodies.
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  • 22
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    Acta neuropathologica 27 (1974), S. 1-10 
    ISSN: 1432-0533
    Keywords: Leprosy ; Lepromatous ; Axonal Bacillation ; Schwann Cells ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary M. leprae bacilli in nerves of 3 patients with lepromatous leprosy were found in the axoplasm of myelinated and unmyelinated nerve fibers. Axonal bacillation occurred in as much as 2% of myelinated axons. Bacilli within Schwann cells were a more common finding in lepromatous leprosy that intra-axonal bacilli. Intra-axonal bacillation probably represents a late stage phenomenon in lepromatous leprosy. Intra-axonal bacilli may contribute to the dissemination of leprosy by migration of bacilli within the axon, and may contribute directly to nerve fiber destruction.
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  • 23
    Electronic Resource
    Electronic Resource
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    Acta neuropathologica 27 (1974), S. 69-82 
    ISSN: 1432-0533
    Keywords: Chronic Nerve Compression ; Median Nerve ; Guinea-Pig ; Electron Microscopy ; Degeneration ; Regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In guinea-pigs with chronic median nerve compression at the wrist the electron microscopic changes at level of the lesion and both proximal and distal to it have been studied. At the level of the lesion in animals with prolonged motor latency there was a loss of large myelinated fibres. Remaining large fibres had disproportionately thin myelin sheaths or were demyelinated. Regenerating clusters containing myelinated fibres were present. Evidence of degeneration and regeneration of unmyelinated fibres was present in the more severely affected nerves of this group. Distal to the wrist myelinated fibre density recovered, with regenerating clusters and many axons having disproportionately thin myelin sheaths. Midforearm and upper arm levels were normal. In nerves in which no muscle response to electrical stimulation could be recorded in the palm, a few fibres devoid of myelin remained at the wrist. Immediately proximal to it myelinated fibres were rare, the main feature being Schwann cells containing axons devoid of myelin some of which were degenerating. Degeneration of myelinating fibres within regenerating clusters was seen. At the mid-forearm level large myelinated fibres were reduced and increased numbers of regenerating clusters were seen. Evidence of regeneration of unmyelinated fibres was found. The upper arm was normal.
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  • 24
    ISSN: 1432-0533
    Keywords: Myxopapillary Ependymoma ; Tissue and Organ Culture ; Electron Microscopy ; Basement Membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Explants of a myxopapillary ependymoma were grown on collagen-coated coverslips and in organ culture systems using gelfoam sponge matrices and Millipore filter platforms. The tumor cultured on collagen-coated coverslips initially exhibited the cytologic features of simple uni- and bipolar glial cells and later developed an epithelial-like pattern. Delicate branching of argyrophilic cell processes was demonstrated in Bodian preparations. In organ cultures, the tumor architecture was well preserved for approximately 4 weeks, and mitotic figures were present. Invasion of the sponge foam matrix was seen. Later cultures demonstrated progressive perivascular sclerosis and hyalinization. By electron microscopy, the tumor cells in organ culture systems retained the major fine structural characteristics of the original neoplasm up to 27 daysin vitro. The most striking feature in the late stages was the extensive increase and reduplication of basement membrane material, which appeared related to the increase of collagen fibrils in the extracellular space.
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  • 25
    Electronic Resource
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    Acta neuropathologica 27 (1974), S. 247-256 
    ISSN: 1432-0533
    Keywords: Werdnig-Hoffmann's Disease ; Electron Microscopy ; Muscle Biopsy ; Myotube-like Cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An ultrastructural study was carried out on muscle biopsies of 7 children with Werdnig-Hoffmann's disease. The muscle fibres were classified into 3 categories: 1. Muscle cells of normal diameter without any distinct or only slight changes. 2. Small muscle cells with a large central nucleus with the appearance of myoblast at a later stage of development. 3. Cells resembling myotubes containing in a common basement membrane two to four cells at different stages of maturation. Myoblast and myotube-like cells seemed to resemble foetal muscle fibres. Such fibres appear to represent an arrest in maturation rather than muscle atrophy.
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  • 26
    ISSN: 1432-0533
    Keywords: Jimpy Mouse ; Electron Microscopy ; Mouse Mutant ; Myelination ; Axonal Growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A quantitative study of the myelination and axonal growth in the corpus callosum and posterior columns of the spinal cord in the Jimpy mouse gave the following results: The reduction in the number of myelinated fibers is much more important in regions with late myelination, e.g. corpus callosum and pyramidal tracts than in the previously myelinated fascicles of Goll and Burdach. There is an important delay in the increase in volume of axons particularly within the structures of late myelination. The importance of the lacking axonal growth in relation to myelination is discussed.
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  • 27
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    Acta neuropathologica 30 (1974), S. 73-84 
    ISSN: 1432-0533
    Keywords: GM1 Gangliosidosis ; Friesian Calves ; Inborn Metabolic Error ; Histochemistry ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Histoenzymic and ultrastructural alterations in the brains of seven calves with GM1 gangliosidosis are described. A decreased oxidative enzyme activity in neurons was accompanied by an increase in acid phosphatase activity. Membranous cytoplasmic bodies were present in neurons and glia. The periodicity of the membranes was about 5.5 to 6.0 nm. Electron-dense, membrane-bound inclusions were present in perithelial cells. The lesions were compared with those of gangliosidoses in other species.
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  • 28
    ISSN: 1432-0533
    Keywords: Aseptic Meningitis ; Atheromatous Material ; Hypersensitivity ; Electron Microscopy ; Macrophages ; Pia-Arachnoid ; Granuloma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 500 mg of sterile pooled human atheromatous material was injected into the cisterna magna of 6 mongrel dogs. Repeated cisternal punctures were done at various intervals until sacrifice from 1 day to 28 days following injection. CSF was obtained for cell count, sugar, protein and analysis in the Technicon 6/60 which measured 14 additional chemical and enzymatic variables. All 6 animals showed a prompt cerebrospinal fluid (CSF) pleocytosis which largely subsided during the first 2 weeks after injection. Increased CSF protein content developed more slowly, but was more prolonged than the pleocytosis. There was a variable decrease in CSF sugar and increase in CSF lactate dehydrogenase, calcium and inorganic phosphorous. Light and electron microscopic studies showed an intense acute inflammatory reaction with marked phagocytosis of the foregin material, probably by arachnoidal cells and moderate edematous changes in the astrocytic processes at the site of injection. During the first 2 weeks after the injection the inflammatory reaction became chronic and the edematous changes in the medulla subsided.
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  • 29
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    Acta neuropathologica 30 (1974), S. 175-181 
    ISSN: 1432-0533
    Keywords: Reacting Astrocytes ; Phagocytosis ; Experimental Gliomas ; Ethylnitrosourea ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structure of reacting astrocytes in experimental gliomas has been described. These tumours were induced transplacentally by 30 mg of N-ethyl-N-nitrosourea per kg of body weight injected into the tail vein of pregnant BD-IX rats on the 15th day of gestation. In tumour-bearing animals astrocytes undergo striking morphological changes and show increased mitotic activity. Reacting astrocytes around gliomas display large, eccentric, irregular nuclei and the abundant cytoplasm contains an increased number of cell organelles. The most dramatic increase is in glial filaments: these form thick bundles at the periphery of the cells and in the processes which are frequently seen around demyelinated axons. Reacting astrocytes engulf and break down myelin sheaths: their remnants, lamellar inclusion bodies and lipid droplets, are present in the cytoplasm. Extravasated erythrocytes are also surrounded by and digested in reacting astrocytes. Numerous lysosomes could provide the necessary enzymes for the phagocytic activity of these cells.
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  • 30
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    Archives of microbiology 98 (1974), S. 271-274 
    ISSN: 1432-072X
    Keywords: Proteus vulgaris ; Bacteriocin ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The intracellular development of a bacteriocin in a strain of Proteus vulgaris was investigated. Particles which resemble the bacteriocin make their appearance in the cell after 60 min induction with mitomycin C. At this stage they appear as broad bands of tightly-packed phage tail-like structures. With longer periods of induction the bands are disrupted to liberate individual phage tail-like particles.
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  • 31
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    Archives of microbiology 98 (1974), S. 311-329 
    ISSN: 1432-072X
    Keywords: Dictyostelium discoideum ; Inorganic Polyphosphate ; Electron Microscopy ; Enzymes ; Polyphosphate Metabolism ; Cellular Slime Mold ; Polyphosphatase ; Polyphosphate-ADP-Phosphotransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The concentration of inorganic polyphosphates in Dictyostelium discoideum was low in the amoebae. A ca 5-fold increase took place during the early stages of multicellular development and was followed by a decrease during the intermediate stages. Electron micrographs showed the presence of electron dense material in all parts of the differentiating cells. The substance was most frequently observed in various types of vacuoles. Two enzymes of polyphosphate metabolism were identified and studied in cell-free extracts: a polyphosphatase and a polyphosphate-ADP-phosphotransferase. No polyphosphate-glucose-phosphotransferase or polyphosphate-AMP-phosphotransferase activities were observed in the extracts. The specific activity of the polyphosphatase, pH optimum 7.6, was ca 30 nmol Pi·min-1·mg protein-1 at all stages of development. The enzyme activity was not inhibited by 0.01 M orthophosphate. The polyphosphate-ADP-phosphotransferase, pH optimum ca 7.7, was studied in the direction of ATP. The enzyme specific activities were very low, about 0.2 nmol P·min-1·mg protein-1, and rather constant during differentiation. The enzyme activity was inhibited by orthophosphate and by excess ADP. It was concluded that the polyphosphate-ADP-phosphotransferase did not contribute significantly to the formation of ATP during multicellular development, and that polyphosphate did not act as a phosphagen in the differentiating cellular slime mold. It was suggested that polyphosphate served as a phosphate store and as a means of regulating the intracellular orthophosphate concentration during development.
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  • 32
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    Archives of microbiology 97 (1974), S. 27-38 
    ISSN: 1432-072X
    Keywords: Mass Mating ; Electron Microscopy ; Cell Fusion ; Membrane Structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The process of mating reaction of Saccharomyces cerevisiae was studied by electron microscopy. Prior to the dissolution of the part of the cell walls separating the conjugating pair of cells, the thinning of the electron transparent layer of the cell wall occurs at the part toward which the nuclei are migrating. After the dissolution of the cell walls of the conjugating cells, the cell membranes become associated with each other, then to be broken and rejoined. The first diploid bud emerges from about the middle of the zygote. The morphological changes during the mating reaction are discussed in relation to the biochemical changes so far known.
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  • 33
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    Archives of microbiology 99 (1974), S. 281-294 
    ISSN: 1432-072X
    Keywords: Spirochete ; Artemia ; Brine Shrimp ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. A spirochete which occurs in tissues of the brine shrimp,Artemia salina, was studied by light microscopy and transmission electron microscopy. A total of seven infected shrimps were encountered. 2. Under darkfield illumination, most spirochete cells inArtemia blood were 6–13 μ long and 0.3–0.4 μ wide. Coiling was variable and often irregular. 3. When tissues of the maxillary gland (kidney) and nearby organs were examined by electron microscopy, spirochete cells were found in both extracellular and intracellular locations. These microbes possessed the ultrastructural features typical of members of the Order Spirochaetales: a) a slender protoplasmic cylinder (0.18 μ average diameter), b) axial fibrils (150 A average diameter), and c) an outer envelope or sheath (approximately 75 A thick). 4. Counts made of the number of axial fibrils evident in transverse sections of spirochete cells were consistent with the hypothesis that this spirochete has a 1-2-1 arrangement of axial fibrils. 5. Non-spiral forms were observed in the haemocoel and in the lumen of the maxillary gland.
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  • 34
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    Lung 150 (1974), S. 185-189 
    ISSN: 1432-1750
    Keywords: Paraquat Poisoning ; Morphology ; Electron Microscopy ; Light Microscopy ; Letal Course ; Human Lung ; Lung Fibrosis ; Proliferative Alterations ; Degenerative Alterations ; Pathogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Morphological alterations in the lungs of 3 cases of paraquat intoxication with prolonged lethal course (10, 11, and 25 days) are reported. Combined light-and electronmicroscopic studies reveal that 10 and 11 days after the ingestion of paraquat the endothelium of the occassionally congested capillaries is intact. The basal membranes have only scarce alterations. They are sometimes naked because of shadding of both types of pneumocytes with severe alterations, e.g. lipid accumulation in the cytoplasm. In the vast alveolar edema, red blood cells, some round cells, strands of fibrin, and lamellar cell debris are seen. There are also varying amounts of polymorphnuclear leucocytes and alveolar macrophages with many phagolysosomes and cytosegresomes. Fibroblasts with lipid droplets between the extensive RER form varying amounts of collagen fibrils in the alveolar and sometimes in the very edematous interstitial space. Sometimes surrounded by collagenous material, they thus devoured by macrophages. 25 days after paraquat intoxication a severe alveolar fibrosis, focal interstitial fibrosis, and areas with atelectasis are found. Due to artificial respiration and changed ventilation mechanics, there were large areas with hemorrhage and a honeycomb-like structure of the remaining lung parenchyma. The pathogenesis of the degenerative and proliferative lung alterations is briefly discussed.
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    Archives of microbiology 100 (1974), S. 145-162 
    ISSN: 1432-072X
    Keywords: Complex Flagella ; Fine Structure ; Electron Microscopy ; Optical Diffraction ; Flagellin ; Flagellar Motion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Zellen von Rhizobium lupini H 13-3 besitzen 5–10 peritrich inserierte komplexe Geißeln, deren Feinstruktur durch Hochauflösungs-Elektronenmikroskopie und lichtoptische Diffraktion analysiert wurde. Das Geißelfilament hat einen Durchmesser von 160 Å und besteht aus einem zylindrischen Kern (Durchmesser ca. 110 Å), der fest von drei Bändern einer helikalen Scheide umgeben ist. Die Scheidenbänder sind 49 Å breit, durch 49 Å-Intervalle voneinander getrennt und haben eine Steigung von 31°. Die komplexen Geißelfilamente bestehen aus einem 43 000-Dalton-Protein, das den Kern und die helikale Scheide aufbaut. Beide gehen übergangslos aus dem proximalen Geißelhaken hervor, der einen Durchmesser von 150 Å und eine Länge von 600 bis 800 Å hat. Die Diffraktionsanalyse des Geißelhakens zeigte eine helikale Grundanordnung von globulären Untereinheiten, die ein Oberflächengitter von 5 parallelen Schrauben (Steigung 29° bzw. 33°) bilden, von denen jede fast 11 Untereinheiten pro Helixungang trägt. Die komplexen Geißeln von R. lupini H 13-3 und Pseudomonas rhodos [Schmitt et al.: J. Bact. 117, 844–857 (1974)] sind ein neuer Typ von Bakteriengeißeln. Sie zeigen deutliche Übereinstimmung in der Feinstruktur, der festen Verbindung von helikaler Scheide und Geißelhaken sowie in der Fragilität ihrer Filamente; sie unterscheiden sich deutlich im Molekulargewicht der Flagellinmonomeren (43 000 bzw. 55 000). Zellen von R. lupini H 13-3 führen schnelle, vibrierende Translationsbewegungen aus. Mögliche Mechanismen der Bewegung komplexer Geißeln werden diskutiert.
    Notes: Abstract Cells of Rhizobium lupini H 13-3 possess 5 to 10 peritrichously inserted complex flagella, which were analyzed by high resolution electron microscopy and by optical diffraction. The flagellar filament has a diameter of 160 Å; it consists of a cylindrical core (diameter approximately 110 Å) surrounded by three close-fitting bands of a helical sheath. The helical bands are 49 Å wide, separated by axial intervals, 49 Å wide, and run at an angle of 31°. Complex filaments consist of a 43 000-dalton protein representing the core and the helical sheath. These originate from the proximal hook, which has a diameter of 150 Å and a length of 600 to 800 Å. The diffraction analysis of the hook showed a helical arrangement of globular subunits forming a surface of 5 parallel “small-scale” helices (pitch-angles 29° and 33°, respectively), each carrying almost 11 subunits per period. The complex flagella of R. lupini H 13-3 and Pseudomonas rhodos [Schmitt, et al.: J. Bact. 117, 844–857 (1974)] represent a novel type of bacterial flagella. There is agreement in their fine structures, in the intimate connection of the helical sheath and the core, and in the fragility of their filaments. Thery are clearly distinguished by the molecular weights of their flagellin monomers (43 000 and 55 000, respectively). Cells of R. lupini H 13-3 show fast, vibrating, translational motions. Possible mechanisms of complex flagellar motion are discussed.
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    Archives of microbiology 100 (1974), S. 307-328 
    ISSN: 1432-072X
    Keywords: Citrate Lyase ; Subunit Structure ; Electron Microscopy ; Reaction Inactivation ; Rhodopseudomonas gelatinosa ; Phototrophic Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Citrate lyase (EC 4.1.3.6) from Rhodopseudomonas gelatinosa has been purified to homogeneity by protamine sulfate fractionation, chromatography on DEAE-Cellulose and gel filtration. The final enzyme preparation had a specific activity of 138 units per mg of protein and was purified 43-fold over the crude extract. Analysis of citrate lyase by sedimentation equilibrium experiments and gel filtration gave molecular weights of 530000 and 560000, respectively. 2. Electron microscopic investigations of negatively stained enzyme molecules and image analysis showed that citrate lyase is composed of six large and six small subunits; they are arranged in two hexagonal rings lying face to face, each containing, in alternating sequence, three large and three small subunits. The enzyme molecule is 160 Å in diameter and about 100 Å thick. 3. Treatment with sodium dodecylsulfate and mercaptoethanol dissociated citrate lyase into three proteins. Protein III (small subunit) had a molecular weight of 30000 and contained the pantothenate; protein II (large subunit) had a molecular weight of 61000; protein I (M r =97000) was probably an aggregate of II and III. 4. Based on the results obtained a model of citrate lyase was constructed. 5. Purified citrate lyase was obtained from R. gelatinosa in a deacetylated and largely oxidized form. The enzyme was activated by reduction with dithiothreitol (3 mM) and subsequent acetylation with acetic anhydride (1.75 mM). 6. The enzyme was subject to reaction inactivation, the extent of which depended on the concentration of Mg2+.
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  • 37
    ISSN: 1432-072X
    Keywords: Bdellovibrio bacteriovorus ; Spirillum serpens ; Freeze Fracture ; Electron Microscopy ; Ultrastructure ; Membrane Damage ; Organismic Associations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The freeze-fracture technique and electron microscopy have been used to demonstrate that localized damage is inflicted upon the cytoplasmic membrane of Spirillum serpens VHL within 20 to 30 min after the start of its association with Bdellovibrio bacteriovorus 109D. This damage is not observed in uninfected Spirillum cells, nor in infected cells within the first 10 min. This damage takes the form of a “blister” which, when viewed stereoscopically in electron micrographs, is seen to project toward the interior of the Spirillum cell. Shortly after its formation, the blister becomes elaborated into a series of ridges which may assume forms ranging from an elaborate spiral to a series of loops or knots. The formation of a blister is shown to involve both the inner and outer leaves of the membrane bilayer, and evidence is presented to indicate that the blister site corresponds to the site of attachment of the Bdellovibrio cell. The hypothesis is proposed that this ultrastructural damage is the cytological basis for the controlled and localized leakage through the cytoplasmic membrane into the periplasmic space of the Spirillum cell at locations adjacent to the Bdellovibrio cell. It is suggested that this localized membrane damage may be the ultrastructural basis for the high efficiency with which bdellowvibrios are known to incorporate cytoplasmic materials from the other bacteria in whose periplasmic spaces they develop.
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  • 38
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    Cell & tissue research 150 (1974), S. 167-178 
    ISSN: 1432-0878
    Keywords: Pigment cell ; Red hair ; Sunburn ; Man ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pigment cells of human red hair (pheomelanocytes) are never connected to keratinocytes by desmosomes or other defined cell junctions. In the dendritic processes of pheomelanocytes, thin filaments, about 50–80 Å in diameter, and microtubuli can be observed. Early prepheomelanosomes contain loosely arranged filaments. With the onset of pheomelanogenesis dense material is deposited on the filaments. Distinction between late prepheomelanosomes and pheomelanosomes is not clearly possible, because of the disorganized appearance of the content. Furthermore, the content of pheomelanosomes sometimes seems to be disintegrated. By means of the DOPA reaction, tyrosinase activity is shown to be present in: a) prepheomelanosomes, b) large cisternae apposed at one side of dictyosomes, c) small cisternae of the smooth endoplasmic reticulum, and d) coated and uncoated vesicles. The results suggest that red pigment granules are formed in a manner similar to that of melanin granules. It is further assumed that an inadequate stability of pheomelanoprotein accounts for the inability of red-haired people to develop effective protection against ultraviolet light.
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  • 39
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 45-54 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper deals with a finite element formulation and solution of the boundary value problem of a concentrated force acting on a semi-infinite micropolar solid. A stiffness matrix is derived for a flat micropolar rectangular element in a plane state and use is made of this element to solve the case of the semi-infinite micropolar solid both in a state of plane stress and plane strain. An immediate application of the plane strain case is the important practical problem of a long line load acting on a soil mass which may be simulated as a micropolar body.
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  • 40
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 111-117 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper presents an extension to the Matrix Transfer Method which gives quadratic convergence to a natural frequency from within a range on either side.The method is described and illustrated by application to: 1A torsional vibration problem, and2A lumped mass beam vibration problem.
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  • 41
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 139-165 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A finite element formulation is presented for the equations governing the steady thermohydrodynamic behaviour of liquid lubricated bearings. This formulation permits application of the iterative solution scheme to bearings of arbitrary geometry.A generalized Reynolds equation resulting from the combination of the mass and momentum conservation equations is cast into variational form and used to derive general finite element equations. The method of weighted residuals with Galerkin's criterion is used to generate finite element matrix equations for the thermal energy equation. In addition to the finite element formulation, a discussion of appropriate finite difference techniques is also given for problems without complex geometry.As an example, the formulations are applied to obtain numerical solutions for a three-dimensional sector thrust bearing operating in the thermohydrodynamic regime. Pressure, velocity and temperature distributions are give, and the thermohydrodynamic solutions are compared with the results of classical isothermal theory.
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  • 42
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 203-209 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Additional Material: 8 Ill.
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  • 43
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 215-225 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The development of a general quadratic multilayer plate element is presented for the analysis of arbitrarily layered curved plates. In the formulation, each layer of the multilayer plate can have different orthotropic properties and can deform locally. Examples of bending problems are presented which demonstrate the applicability of the formulation.
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  • 44
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 249-269 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A structural optimization problem is considered in which the design requirements include restrictions on the strength, stability, frequency and flutter characteristics of the structure. One of the central concerns of this phase of the work has been to overcome the problems inherent in analysing the dynamic and aeroelastic behaviour of structures with many degrees of freedom. The multiweb delta wing structure under supersonic flight conditions is the model upon which this exploratory study is based. The finite element idealization, with three different kinds of elements, is used to model the wing structure. The constant stress triangular plate elements, the rectangular shear panels and the pin-jointed bar elements are used to represent, respectively, the cover skins, webs and stringers of the wing structure. The design problem is formulated as a minimum weight optimization problem and is solved by using non-linear programming techniques. Computationally efficient schemes are developed for the necessary derivatives of the behaviour constraints. Numerical examples are presented to illustrate the feasibility and the computational effectiveness of the method.
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  • 45
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 311-321 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Additional Material: 2 Ill.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 209-212 
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    Keywords: Engineering ; Engineering General
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  • 47
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 214-214 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 48
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 277-288 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: It is shown how the stress field due to any prescribed continuous distribution of dislocation dipoles can be determined. This technique then forms the basis of a general method of solution of elasto-plastic material problems. The presentation is limited to situations which conform to either plane stress or strain conditions. Some results are obtained for relatively simple geometrical and loading configurations and compared with classical plasticity solutions. Finally, the method is applied to the problem of a circular hole in a finite strip under tension.
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  • 49
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 295-310 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Through the use of complex series representations and the properties of adjoint differential operators, a semi-analytical finite element procedure is developed which can analyse the steady state and transient temperature fields of thermally anisotropic axisymmetric bodies with complete circumferential properties. Due to its generality, the procedure can handle arbitrary laminate construction with possible meridional and radial variations in locally or globally thermally anisotropic materials. In this respect, the procedure developed herein supercedes the classical semi-analytical treatment which is limited to specially orthotropic materials. Furthermore, in contrast with the classical procedure, the present treatment reveals several important effects of material anisotropy which are entirely missed by the specially orthotropic assumption.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 395-401 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Physical reasoning makes it possible to use artificial parameters with numerical quadrature in order to obtain approximate solutions for the Fredholm integral equations associated with radiative heat transfer calculations. With the aid of such parameters, decisions can be made concerning the applicability and usefulness of the numerical quadrature technique.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 430-431 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 439-440 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 8 (1974) 
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 481-494 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A finite element weighted residual process has been used to solve transient linear and non-linear two-dimensional heat conduction problems. Rectangular prisms in a space-time domain were used as the finite elements. The weighting function was equal to the shape function defining the dependent variable approximation. The results are compared in tables with analytical, as well as other numerical data. The finite element method compared favourably with these results. It was found to be stable, convergent to the exact solution, easily programmed, and computationally fast. Finally, the method does not require constant parameters over the entire solution domain.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 503-511 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This paper deals with solving the two-dimensional variational problem for plate bending by the Ritz method using bicubic fundamental splines. It is a piecewise polynomial method, very adaptable to practical numerical computation, and can be an alternative for the well-known Finite Element Method1.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 821-845 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The visco-plastic model of material behaviour is of much practical interest in its own right and initial strain techniques for its solution have been developed and proved efficient. More important however is the fact that the visco-plastic model can be used to generate plasticity solutions in a simple manner when stationary conditions are reached and, at the other extreme, can reproduce standard creep phenomena. Used in this sense it allows the treatment of non-associated plasticity and strain softening situations which present difficulties in conventional plasticity approaches. A standard programme thus allows the treatment of a wide range of materially non-linear problems.The paper discusses various applications of the new general formulation and introduces certain numerical information on solution stability.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 803-809 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The elastoplastic deformation of spherical shells of uniform thickness acted upon by external pressure is investigated in this paper. A deformation theory of plasticity is combined with the classical elasticity equations and a solution is obtained by the method of successive elastic solutions. A logarithmic effective stress-effective plastic strain diagram is used to determine the volume change for thick polypropylene spheres under the action of external pressure. These results are compared with previously published experimental volume changes in polypropylene spheres. This comparison shows that the predicted volume changes are similar to the experimental results.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 913-914 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 917-918 
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 212-212 
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 271-276 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The fitting of a function y =\documentclass{article}\pagestyle{empty}\begin{document}$ \sum\nolimits_{i = 1}^n {A_i {\rm{e}}^{\lambda ix}} $\end{document} to experimental data is considered. Integral equations are developed which have the functions \documentclass{article}\pagestyle{empty}\begin{document}$ \sum\nolimits_{i = 1}^n {A_i {\rm{e}}^{\lambda ix}} $\end{document} as their solutions for n = 1, 2, 3, These integral equations are used to find the frequencies λi. Examples are worked out to illustrate the method. The method is shown to be capable of extension to other functions.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 289-294 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: To obtain meshes of reasonable form there have to be made some restrictions in the application of automatic mesh generation schemes using ‘isoparametric’ co-ordinates. In this present paper it will be shown that such restrictions exist for plane meshes. The results figured here are also valid for three-dimensional meshes.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 341-358 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A least square based finite element algorithm is developed for some elasto-static problems. In the formulation both stresses and displacements appear as simultaneous variables. In two dimensional (plane) analysis, parabolie isoparametric elements are used. Considerable improvement of performance is obtained with a numerical integration based on 2 × 2 Gauss point distribution over more accurate integration schemes. Reasons for this are presented.The formulation is extended in the section ‘General least square formulation’ to beams and plates with a similar success of ‘reduced’ integration.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 323-339 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A finite strip method is presented for determining the initial buckling stresses of any structure consisting of a series of thin flat isotropic plates rigidly connected together at their longitudinal edges. Each plate may be subjected to a combination of longitudinal and transverse compression, longitudinal in-plane bending, and shear, and it is assumed that the buckling mode, of whatever type, is sinusoidal in the longitudinal direction. Due to the presence of shear, the perturbation forces and displacements which occur at the edges of component plates during buckling are out of phase, and this is accounted for by defining their magnitudes in terms of complex quantities. Stiffness matrices relating the amplitudes of these forces and displacements are derived using an approximate method based upon assumed displacement functions across the width of the plate. It is shown how the method can be used to calculate natural frequencies of prismatic structures, and finally an indication of the accuracy of the method is given together with some illustrative results.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 403-414 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: By representing the time-dependent material properties by mechanical models, i.e. the generalized Maxwell and/or Voigt (or Kelvin) models, it is possible to formulate a consistent procedure to analyse the effect of material damping on dynamic response. As a continuation of the previous work which concerned the creep and relaxation of viscoelastic materials, the present paper applies this representation to the harmonic response analysis. The harmonic solution can be obtained by decomposing the relevant forces and displacements into real and imaginary parts and it is shown that the modal analysis by an appropriate eigensolution procedure is useful for obtaining the dependence of vibration amplitude on frequencies of sinusoidal external excitations.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 513-519 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Edge displacement of assumed-stress hybrid plate elements are commonly chosen as either linear, quadratic or cubic functions of the edge co-ordinate. The present paper examines the effect of this choice on the acceptability, accuracy, and possible zero energy modes of elements based on a linear stress field. It is concluded that triangular elements may be preferable to quadrilaterals, and that linear edge displacements are not desirable.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 537-545 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The development of a generalized quadrilateral finite element that includes a singular point at a corner node is presented. Inter-element conformability is maintained so that monotone convergence is preserved. The global-local concept of finite elements is used to formulate the complete set of equations. Examples of crack tip singularities are given.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 547-567 
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    Notes: The triangular element is one of the most useful finite difference elements for the potential problems because of its versatility in fitting irregular boundary, in connecting one element type to another, and in changing grid fineness. Such triangular elements find many applications in conduction problems in cartesian co-ordinates. This paper presents a new triangular element for the finite' difference solution of axisymmetric conduction problems in cylindrical co-ordinates. The validity of the proposed triangular element is analyzed, and its workability is demonstrated using three selected examples. Also, an industrial application highlights the advantageous characteristics of the triangular element, and gives a comparison with known results obtained by finite element method.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 569-588 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Basic equations are derived for a comprehensive computer analysis for an equivalent lumped parameter system which simulates a pre-twisted, rotating or non-rotating. Timoshenko beam in coupled bending-bending-torsion vibrations. These equations enable one to develop straightforwardly digital computer programs for studying vibration problems related to compressor or turbine blades in turbomachinery as well as in other structural dynamics applications. The validity of the lumped parameter approach is established through a free vibration study. Good agreement between the present computer results and those obtained theoretically or experimentally by other investigators is demonstrated. In particular, it is found that the natural frequencies obtained in the free vibration study for all beams examined converge from below the exact values at a convergence rate of N-4, where N is the total number of the lumped parameters used in the computer simulation. The rapid rate of convergence shows that the mathematical model used in deriving the basic equations can adequately represent the type of beams under consideration. The known convergence rate also provides an estimate on the accuracy of the computer results, and a means to improve these results by extrapolation.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 659-661 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 662-670 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A unified procedure is presented for the automatic generation of the coefficient matrix of finite difference equations. The method is applicable to the solution of both initial and boundary value problems, to any order of difference equation, and may be used with any arbitrary initial or boundary conditions.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 671-675 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A method of determining the torsional stiffness of a wide range of structural sections, both homogeneous and composite, is presented. Prandtl's stress function along the boundaries of component sections is approximated by finite Fourier series with coefficients chosen to minimize a functional. An example indicates that the stiffness may be determined to acceptable accuracy by the solution of very few equations.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 697-711 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: It is shown how the elasticity equations can be formulated in terms of a general procedure of abstract analysis, called the projective method, for constructing an approximate solution. This allows the many studies of convergence and uniqueness of solutions which have been made in modern mathematics to be applied to the elasticity problem. The abstract formulation also suggests an organizational scheme for generating a computer code. A computer code for hollow or solid cylinders of arbitrary cross section was developed and several numerical examples are presented. The procedure is computationally advantageous for the class of problems under consideration because of the relatively small number of equations that must be solved as compared to the finite element method. The results presented demonstrate the accuracy of the method.
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    International Journal for Numerical Methods in Engineering 8 (1974) 
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 743-770 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The discrete (Legendre) orthogonal polynomials, (DLOP's) are useful for approximation purposes. This set of mth degree polynomials {Pm(K, N)} are orthogonal with unity weight over a uniform discrete interval and are completely determined by the normalization Pm(O, N) = 1. The authors are employing these polynomials as assumed modes in engineering applications of weighted residual methods. Since extensive material on these discrete orthogonal polynomials, and their properties, is not readily available, this paper is designed to unify and summarize the presently available information on the DLOP's and related polynomials. In so doing, many new properties have been derived. These properties, along with sketches of their derivation, are included. Also presented are a representation of the DLOP's as a product of vectors and matrices, and an efficient computational scheme for generating these polynomials.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 783-801 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The patch test is shown to be contained in the variational formulations of the finite element methods at the assembling level, all of which require the vanishing of the virtual work of interface connection loads. By a systematic introduction of stress generating functions, attention is drawn to the fact that any given finite element model can be assembled in two different ways: either by identification of a set of boundary displacements (leading to the direct stiffness method), or by identification of a set of local stress function values (leading to the dual direct flexibility method). Looking at any conjugate couple (generalized displacement-generalized surface traction) at an interface, one is strongly transmitted, the other weakly. Discretization of the zero virtual work condition at an interface of plate bending models, by means of Legendre polynomial expansions, allows a systematic construction of so-called ‘non-conforming’ elements that pass the patch test. They are in fact identified with weakly conforming, but strongly diffusive, hybrids, and the lowest degree element (quadratic) is in fact the Morley constant-moment element. Examples are given for higher degree displacement fields.The case of plate stretching elements can be handled by duality, the difficulties being here associated with the requirements for diffusivity. Non-diffusive elements that pass the zero interface virtual work test can be constructed systematically and are identifiable with weakly diffusive, but strongly conforming, hybrids of the type first proposed by T. H. H. Pian.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 27-43 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Body oriented co-ordinates are defined for three-dimensional regions bounded by six surfaces. From this definition of body oriented co-ordinates, two transformations are derived: 1Body oriented surface co-ordinates to the Cartesian co-ordinates, and2Body oriented co-ordinates for a three-dimensional region to Cartesian co-ordinates.With these transformations a mesh generator is developed based on the principle that the mesh required to describe a region will be calculated according to the placement of the discrete points that describe the boundary edges. This is accomplished with two versions of the mesh generator: the surface generator and the volume generator. The surface generator maps the four boundaries of the surface onto the four boundaries of a unit square. Next, the interior points for the surface mesh are established in the mapped space. Then, using the first transformation, the co-ordinates for the surface nodal points are calculated. Similarly, the volume generator maps the six surfaces of the body onto the surfaces of a unit cube, establishes the interior nodal points in the mapped space, and using the second transformation, calculates the co-ordinates for the interior nodal points.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 359-367 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This paper describes a method of solving electromagnetic induction problems by means of the finite element technique. A variational equation associated with the differential equation for the vector potential is formulated and solved via the concept of finite elements. Sinusoidal driving currents and linear, isotropic, but inhomogeneous media are assumed. A typical example is included in order to illustrate the suggested solution technique.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 369-394 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The mesh generation program described here generates the nodes and the elements for excavated highway slopes, applies boundary conditions, searches for the nodes and the elements in each layer excavated and plots the mesh with the numbering of nodes, elements and material types.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 415-424 
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    Notes: A finite element analysis applicable to elasto-plastic shells of arbitrary shape is presented. Small-deflection behaviour of thin shells subjected to monotonically increasing static loads is considered. The material is assumed to be originally isotropic, following the von Mises yield criterion and the Prandtl-Reuss flow rule. A flat triangular element with twelve degrees of freedom is used in the analysis. Within each element both membrane forces and bending moments are assumed to be constant. Some numerical results are included to illustrate the merits of the element.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 425-429 
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    Notes: A procedure to deal with various boundary conditions in the Rayleigh-Ritz method is discussed herein, namely, the method of artificial parameters. The method is then applied to solve a simple string problem; results obtained compare very nicely with exact solutions.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 431-432 
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 433-437 
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    Notes: One of the first finite elements presented was that by Turner et al.1 Pian2 presented a hybrid plane stress element and Wilson et al.3 presented a non-conforming displacement element. It is shown that the three resulting stiffness matrices are identical.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 461-480 
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    Notes: The concepts and potential advantages of local and global least squares smoothing of discontinuous finite element functions are introduced.The relationship between local smoothing and the ‘reduced’ integration' technique is established.Examples are presented to illustrate the application of the two smoothing techniques to the finite element stresses from several structural analysis problems.The paper concludes with some practical recommendations for discontinuous finite element function smoothing.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 495-501 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: In a two-dimensional space of points on an equilateral triangle grid, a single difference equation holding at each node is found from the finite element formulation of the wave equation for all published polynomial orders of the functional expansion. Assuming homogeneous boundary conditions on any equilateral triangle whose edges and vertices pass through the grid points, the eigensolutions of the difference equation are found exactly and thus provide an excellent test problem for the programmer or engineer. The advantage of the present method over other formulations is that the number of linear operations required to produce the difference equation is minimal.
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 429-430 
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 432-432 
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    International Journal for Numerical Methods in Engineering 8 (1974), S. 438-438 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 90
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 443-460 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A number of problems are analysed by the displacement method to assess the stress accuracy at very low compressibilities. ‘Parabolic’ isoparametric elements are used. It is found that the mean stress becomes grossly in error at the centre and edges of each element as the compressibility is reduced whereas the deviatoric stress components do not. All stress components retain good accuracy at the ‘reduced’ integration sampling points (2 × 2 Gauss). ‘Exact’ integration yields a similar stress distribution to ‘reduced’ but the mean stress is grossly in error at the integration points (3 × 3 Gauss). Exceptions, however, occur.These findings are interpreted, and a rule for predetermining whether or not accurate stresses can be obtained at the integrating points is suggested. Thus it is shown that the displacement method is suitable for analysing materials which for practical purposes are incompressible.A procedure is then presented for analysing porous media-both linear and non-linear-by separating the stiffness into ‘effective’ and ‘pore fluid’ components. This allows excess pore pressure to be calculated explicitly. Applications to saturated soils are given which make use of the findings of the first part of the paper.
    Additional Material: 10 Ill.
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  • 91
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 529-536 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The steady state flow problem known in magnetohydrodynamics as Hartmann's flow is converted into variational formulation and is given an approximate solution by means of the spline blended interpolation technique. The equations of motion consist of two coupled potential flow problems with homogeneous boundary conditions. The spline blended interpolation method is reduced here, because of the shape of the domain, to a cartesian product of cardinal splines with trigonometric or ordinary polynomials. ‘Exact’ boundary conditions are presented by the blending technique. The numerical results indicate that high accuracy is possible with relatively few unknowns.
    Additional Material: 4 Ill.
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  • 92
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 613-624 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper presents a generally applicable approach to transient heat conduction problems with non-linear physical properties and boundary conditions. An unconditionally stable central algorithm is used which does not require iteration.Several examples involving phase change (where latent heat effects are incorporated as heat capacity variations) and non-linear radiation boundary conditions are given which show very good accuracy.Simple triangular elements are used throughout but the formulation is generally valid and not restricted to any single type of element.
    Additional Material: 7 Ill.
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  • 93
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 625-631 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A program is demonstrated which apart from linear finite elements in time also includes elements with shape functions of the second and third degree. The algorithm for discretization in the time dimension is described and, using the example of a parabolic time element, the coefficients required to form the global system are given. By various test examples the efficiency of the process is examined by comparison with the customary difference method. Generally, with finite elements in time, the solution has better stability. Comparing the time required for calculation with the accuracy of the solution it would appear that in examining problems where boundary conditions are constant in time, higher order time elements are no improvement over the linear time element. However, for the purpose of reproducing periodic processes, higher order time elements offer an advantage in that one is not limited to linear variations of the boundary conditions within the element. Thus, for example, the temperature curve for parabolic variation of the surface temperature can be reproduced with close approximation by two time elements per period and a shape function of the third degree.
    Additional Material: 6 Ill.
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  • 94
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 676-676 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 95
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 771-781 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The steady two-dimensional, viscous, electrically conducting flow around a circular cylinder is investigated. The flow and magnetic field are uniform and parallel at large distances from the cylinder. The equations and boundary conditions are derived for arbitrary values of R, Rmand β, where R is the Reynolds number, Rm the magnetic Reynolds number and β, the ratio of the square of the Alfvén speed to the square of the main stream speed. Because of the large number of parameters involved, the numerical solution is restricted to R = 40, Rm = 1 and infinity and 0 ≤ β ≤ 4. Also the cylinder is taken to be a perfect conductor, this avoids having to compute the magnetic field within the cylinder.The numerical computations for the non-magnetic case, i.e. β = 0, are presented and are found to be in good agreement with existing results. The effect of increasing the strength of the magnetic field (i.e. increasing β) on the drag coefficient, the size and position of the standing vortex and the increasing effect of the upstream propagation of disturbances are examined.
    Additional Material: 5 Ill.
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  • 96
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 811-820 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: We describe a finite element method for the one-dimensional Stefan problem. The elements are quadrilaterals of the space-time plane which are determined at each time-step in relation with the position of the free boundary. The method appears as a generalization of the classical Crank-Nicolson scheme, since it is identical to this scheme in the case of rectangular elements; it has the advantage of providing a simple and accurate determination of the free boundary. Numerical experiments show that the order of accuracy is equal to 2.
    Additional Material: 2 Ill.
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  • 97
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 865-876 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Based on the least squares error criterion, a class of finite element is formulated for the numerical analysis of steady state viscous boundary layer flow problems. The method is essentially a discrete element-wise minimization of square and weighted residuals which arise from the attempts in approximately satisfying boundary layer equations. An iterative linearization scheme is developed to circumvent the mathematical difficulties posed by the non-linear boundary layer equations. It results in a process of successive least squares minimizations of residual errors arising from satisfying a set of linear differential equations. A mathematical justification for the method is presented. A major feature of the method lies in the linearization approach which renders non-linear differential equations amenable to linear least squares finite element analysis. Another important feature rests on the proposed finite element formulation which preserves the symmetric nature of finite element matrix equations through the use of the least squares error criterion. Numerical examples of viscous flow along a flat plate are presented to demonstrate the applicability of the method as well as to illuminate discussions on the theoretical aspects of the method.
    Additional Material: 8 Ill.
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  • 98
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 917-917 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 99
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 847-864 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A finite beam-column element computer program for the structural failure analysis of proportionally loaded skeletal plane frames is described. The program, which is based on an iterative stiffness approach, provides for non-linear elastic or plastic-non-linear elastic behaviour. Particular attention is given to the incorporation into the analysis of geometrical imperfections, return of elasticity at plastic hinges and negative frame stiffness. The effect of lack-of-fit displacements on the load-deflection path and failure load of frames that carry relatively large axial loads is described in general terms. The theory is developed further through the application of the computer program to two examples which show the necessity for the allowing for the effect of imperfections when designing axially loaded redundant frames.
    Additional Material: 9 Ill.
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  • 100
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This article presents an efficient numerical algorithm a complete listing of the associated computer program, developed for the eigenproblem solution of discrete damped structures, including spinning ones. The numerically stable procedure is based on a combined Sturm sequence and inverse iteration technique, which fully exploits the banded form of the relevant matrices and proves to be most substantially economical when compared to similar existing softwares. Numerical results are presented for representative structures, solved by the present computer program written in FORTRAN V for the JPL UNIVAC 1108 computer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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