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  • 1985-1989  (547)
  • 1975-1979
  • 1890-1899
  • 1986  (547)
  • Engineering General  (497)
  • Electron microscopy
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Materialart
Erscheinungszeitraum
  • 1985-1989  (547)
  • 1975-1979
  • 1890-1899
Jahr
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Histopathology of otitis media with effusion (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 269-273 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Otitis media with effusion ; Electron microscopy ; Human temporal bones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ultrastructural studies of the middle ear mucosa appear to be of significant value in better understanding the pathology of otitis media with effusion (OME). Our present study was undertaken in order to take advantage of the use of electron microscopy in investigating all areas of the middle ear mucosa. Tissues studied were obtained from the fresh postmortem temporal bones of three patients with OME and terminal head and neck malignancies. In the mucoid type of effusion (cases 1 and 2), goblet cells were seen to proliferate and secretory activity was greatly enhanced. In contrast, there was no evidence of secretory cell proliferation in the serous type of effusion. It was noteworthy that accumulated fluid was not homogeneous in the same ear, as exemplified by case 1, in which both mucoid and serous effusions were present. This occurrence was possibly the result of topographic diversity involving the secretory activity of the middle ear.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00464444
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  • 2
    Digitale Medien
    Digitale Medien
    Experimental tympanosclerosis following infection with Streptococcus pyogenes and vitamin D3 intoxication (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 296-303 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Experimental tympanosclerosis ; Induced calcifications ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A rat animal model was used to study the ultrastructure of submucosal calcifications induced in the middle ear following inoculation with Streptococcus pyogenes and high doses of parenteral vitamin D3. The morphological changes present in affected animals resembled the classical picture of tympanosclerosis. While calcification occurred about bacterial remnants and myelin structures, the most important calcification centers were lysosomal and non-lysosomal matrix vesicles in the extracellular spaces. These formed band-like calcifications close to the basal membrane without affecting the epithelial layer. This animal model offers the possibility of studying the effect of various therapeutic regimens in the treatment of the dynamic tympanosclerotic process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00460205
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  • 3
    Digitale Medien
    Digitale Medien
    Heterogeneity of circular mitochondrial DNA molecules from sugar beet with normal and male sterile cytoplasms (1986)
    Springer
    Current genetics 10 (1986), S. 695-700 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Sugar beet ; Cytoplasmic male sterility ; Mitochondrial DNA ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Mitochondrial (mt) DNAs from normal (N) and male sterile (S) cytoplasms of sugar been have been isolated and investigated by electron microscopy. The results showed that mtDNA was composed of a heterogeneous population of circular molecules. Their contour lengths varied from 0.28 to 51 μm, but unlike in the case of maize, a large difference was not observed in the distribution of molecular classes greater than 1.0 μm between N and S cytoplasms of sugar beet. On the other hand, N and S cytoplasms were shown to contain their own characteristic combinations of small circular mtDNA species with lengths between 0.28 μm and 0.6 μm. Mitochondrial DNAs from various sources of male-sterile cytoplasms were analyzed by agarose gel electrophoresis to determine the extent of cytoplasmic variation. Additional low molecular weight DNA bands appeared in all male-sterile lines examined, and as a result, three distinctive banding patterns were recognized. These data are in general agreement with those based upon restriction endonuclease digestion of mt and chloroplast DNAs and the genetic analysis of fertility restoration in test crosses.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00410918
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  • 4
    Digitale Medien
    Digitale Medien
    Alpha-subunit-producing pituitary adenomas (1986)
    Springer
    Virchows Archiv 409 (1986), S. 417-431 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Pituitary neoplasms ; Pituitary hormones ; Immunocytochemistry ; Electron microscopy ; Alpha-subunit ; Acromegaly
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Immunohistological techniques demonstrate the alpha-subunit of glycoprotein hormones in the majority of endocrine-inactive, undifferentiated pituitary adenomas and pituitary oncocytomas. In about one-fifth of endocrine-active adenomas, the alpha-subunit is produced in combination with either adrenocorticotropic hormone or prolactin, and it is found in combination with growth hormone in about half of those adenomas causing acromegaly. Pure alpha-subunit-producing, endocrine-inactive adenomas characteristically have small secretory granules that are destroyed by direct osmium fixation, but are well preserved after prefixation with glutaraldehyde. As only a few atypical prolactinomas show similar secretory granules, and as they display a positive reaction for the alpha-subunit only exceptionally, this ultrastructural feature can serve as a guide to differentiate such adenomas.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00705414
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  • 5
    Digitale Medien
    Digitale Medien
    Frequency and diagnostic value of the virus-like filamentous intranuclear inclusions in giant cell tumor of bone, not associated with Paget's disease (1986)
    Springer
    Virchows Archiv 410 (1986), S. 65-68 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Giant-cell ; Virus-like inclusion ; Intranuclear inclusion ; Giant cell tumour of bone ; Paget's disease of bone ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary This paper deals with the paramyxovirus-like intranuclear inclusions observed in giant cells tumours of bone (GCTB). Twenty-one (49%) of 43 cases of GCTB (1977–1985), either fresh and/ or cultured, show these ultrastructural inclusions. Fifty samples of various bone lesions in which giant cell lesions occurred, including aneurysmal cysts, hyperparathyroidism, osteoblastoma, human and rat osteopetrosis, GCT of tendon sheaths, and non skeletal granuloma were used as controls. These, together with 20 samples of normal bone (osteoclasts) did not contain intranuclear or intracytoplasmic viral inclusions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00710907
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  • 6
    Digitale Medien
    Digitale Medien
    Effects of experimental torsion of the spermatic cord on Leydig cell function in the guinea pig testis: An ultrastructural stereological analysis (1986)
    Springer
    Urological research 14 (1986), S. 253-256 
    Details
    ISSN: 1434-0879
    Schlagwort(e): Guinea pig ; Spermatic cord torsion ; Stereology ; Electron microscopy ; Leydig cell
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary An ultrastructural stereological analysis of Leydig cells of the guinea pig testis was carried out following surgically induced testicular torsion. Morphometric analyses of the Leydig cells of the experimental group of animals revealed an increase in the nucelar and mitochondrial volume and a decrease in the lipid volume, in comparison to those in the Leydig cells of the control group of animals. We believe that these changes in the Leydig cells of the experimental group of animals are indicative of cellular hypertrophy. The possible mechanisms of the Leydig cell hypertrophy in the guinea pig testis following the induction of spermatic cord torsion are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00256568
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  • 7
    Digitale Medien
    Digitale Medien
    Ultrastructural abnormalities in muscular vessels of hyperthyroid patients (1986)
    Springer
    Acta neuropathologica 71 (1986), S. 64-69 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Muscular diseases ; Capillar pathology ; Grave's disease ; Hyperthyroidism ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary an electron microscope study of needle biopsies from the quadriceps muscle was carried out in 11 non=selected patients (ten females and one male), with clinically and laboratory-diagnosed hyperthyroid disease. Alterations of the normal structure of muscle fibres were found in all cases. Changes in capillaries were found in ten patients, and ranged from an increase in basement membrane thickness with reduplication, to total destruction of the capillaries. The importance of the vascular involvement in the muscles of patients with Graves-Basedow disease is stressed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00687963
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  • 8
    Digitale Medien
    Digitale Medien
    Proliferating potential of folliculo-stellate cells in human pituitary adenomas (1986)
    Springer
    Acta neuropathologica 71 (1986), S. 233-242 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Folliculo-stellate cell ; Pituitary adenoma ; Glial fibrillary acidic protein ; S-100 protein ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Folliculo-stellate cells (FS cells) in 40 pituitary adenomas and portions of anterior pituitary adjacent to the tumor in 26 cases were investigated immunohistochemically, using polyclonal antisera to S-100 protein (S-100) and glial fibrillary acidic protein (GFAP). The objective was to clarify the histological behavior of the FS cells. In most pituitary adenomas there were few or no S-100-or GFAP-positive cell, in comparison with numerous positive cells in the parts of the adenohypophyses compressed by adenomas. However, positive FS cells were observed in some types of pituitary adenomas. Growth hormone and prolactin producing adenomas frequently contained significant amounts of FS cells. In non-functioning adenomas, an unique case of FS cell adenoma was present. The adenoma was composed mainly of FS cells and immature glandular cells. The FS cells were sometimes located around follicles containing Periodic acid Schiff-positive material. Therefore, the FS cell adenoma is characterized by S-100- and GFAP-positive FS cells and PAS-positive follicles. In this type of adenoma, FS cells seemed to be the main proliferating component. In parts of the adenohypophyses adjacent to the adenomas, GFAP0-positive FS cells were numerous. In the pathological conditions FS cells may possess the potential of reactive proliferation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688045
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  • 9
    Digitale Medien
    Digitale Medien
    The distribution of Ia antigen in the lesions of rat acute experimental allergic encephalomyelitis (1986)
    Springer
    Acta neuropathologica 70 (1986), S. 149-160 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Ia antigen ; Central nervous system ; Experimental allergic encephalitis ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ia antigen, encoded within the major histocompatibility complex, plays an important role in the activation of T lymphocytes. Since experimental allergic encephalitis is an essentially T cell-mediated disease, Ia antigen in the central nervous system (CNS) may be pathogenetically relevant. The occurrence of Ia antigen in the CNS of normal rats and of rats with experimental allergic encephalitis was studied by light and electron microscope immunocytochemistry using the monoclonal anti-Ia antibodies Ox 4 and Ox 6. In normal, unsensitized animals a distict population of stellate cells in the meninges and some perivascular mononuclear cells in the nervous tissue carried Ia antigen. In rats with experimental allergic encephalitis a dramatic increase of Ia-positive cells was found. In addition to the positive cells found in normal animals, monocytes, macrophages and many lymphocytes in the meningeal perivascular and parenchymal inflammatory infiltrates as well as “activated microglia” stained for Ia antigen. We did not find evidence for Ia expression on endothelial cells, astrocytes or other components of the CNS in either normal or diseased rats.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00691433
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  • 10
    Digitale Medien
    Digitale Medien
    Transplantation of Pacinian corpuscles of the rat into the brain (1986)
    Springer
    Acta neuropathologica 69 (1986), S. 314-321 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Pacinian corpuscles ; Transplantation to the brain ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In adult inbred rats of the AVN strain, branches of the crural interosseous nerve were dissected out from donors and transplanted into the brain of recipients, together with a cluster of Pacinian corpuscles, (either into a suction cavity or the cerebral cortex) into a slit 1–2 mm deep. The grafts were fixed and processed for electron microscopy 10 days to 6 months after the operation, and their ultrastructure was examined. Sporadic axons of small diameter grew into the nerve branches of some of the grafts from 11 days onward, and became myelinated during the 2nd month after the operation, but none of the transplanted Pacinian corpuscles became reinnervated. The corpuscles, however, survived denervation and grafting. Most of them retained a well-preserved inner core and an intact capsule, consisting of a normal complement of 29.2±1.0 (mean ±SE) capsular layers (n=8), as did the corpuscles previously examined after denervation in situ. Some of the corpuscles underwent degenerative changes, presumably due to a delayed or restricted revascularization. In this group of corpuscles, the inner core underwent disintegration and was gradually replaced by collagen fibrils, whereas the capsule remained preserved but the number of its layers eventually reduced by 40%. It is assumed that the lack of reinnervation of the grafted Pacinian corpuscles was due to the paucity of regenerating axons, and their failure to form correct projections along those Schwann cell columns connected with the corpuscles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688310
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  • 11
    Digitale Medien
    Digitale Medien
    Intercellular deposits of basement membrane material in active human pituitary adenomas detected by immunostaining for laminin and electron microscopy (1986)
    Springer
    Acta neuropathologica 71 (1986), S. 326-331 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Pituitary adenoma ; Basement membrane ; Laminin ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Thirty-eight human pituitary adenomas (24 endocrine active and 14 endocrine inactive tumors) were studied immunohistochemically for the presence of the basement membrane component, laminin, and ultrastructurally for the presence of basement membrane. Immunoreactivity of laminin delineated staining of epithelial and endothelial basement membranes, the reaction product being confined mostly to the perivascular zones. Moreover, a hitherto undescribed presence of intercellular laminin-positive droplets was observed in ten of the active adenomas (nine patients with hyperprolactinemia and/or acromegalia and one patient with Cushing's syndrome). Concurrently, at the ultrastructural level, bunches of basement membrane-like material intermingled between the adenoma cells were demonstrated in seven of these ten active adenomas. Furthermore, secretory granules were entrapped occasionally in this intercellular matrix, indicating a mutual dependence between excessive hormone extrusion and an increase of “misplaced” deposits of basement membrane components, e.g., laminin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688057
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  • 12
    Digitale Medien
    Digitale Medien
    Astroblastoma revisited: A report of three cases (1986)
    Springer
    Acta neuropathologica 70 (1986), S. 10-16 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Astroblastoma ; Immunohistopathology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The very existence of astroblastoma has been a question of considerable controversy, although there appears now to be sufficient documentation to establish it as a tenable entity. Due to the rarity of this tumor, little information exists in the literature as to its natural history, efficacy of therapy and its pathological and radiological appearance. We report three cases of astroblastoma, describing their natural history, the response to therapeutic interventions and their light microscopic, ultrastructural and immunohistochemical characteristics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00689508
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  • 13
    Digitale Medien
    Digitale Medien
    Ultrastructural localization of S-100 protein in neurofibroma (1986)
    Springer
    Acta neuropathologica 69 (1986), S. 103-110 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Neurofibroma ; von Recklinghausen's disease ; S-100 protein ; Electron microscopy ; Immunoelectron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The nature of the cells in neurofibromas was studied by electron microscopy and immunoelectron-microscopic examination of S-100 protein. Ultrastructurally, all five neurofibromas studied were found to be composed of Schwann cells, perineurial cells, and intermediate cells, which had features of both perineurial cells and fibroblasts. The Schwann cells had complex, branched cytoplasmic processes and a continuous basal lamina. The perineurial cells were distinguishable from Schwann cells by the presence of numerous pinocytotic vesicles, unbranched slender cytoplasmic processes and a discontinuous basal lamina. The intermediate cells had no basal lamina, but were topographically related to Schwann cells and had a similar fine structure to that of perineurial cells. Thus, they seemed to be modified neoplastic perineurial cells. Immunoelectron-microscopic studies showed the presence of cells with and without S-100 protein in the neurofibromas: cells with S-100 protein resembled Schwann cells ultrastructurally, and those without S-100 protein were perineurial and intermediate cells. Some Schwann cells with S-100 protein in one neurofibroma had numerous pinocytotic vesicles characteristic of perineurial cells, suggesting that Schwann cells and perineurial cells, are functional variants of the same cell type. Thus this study showed that neurofibromas were composed of Schwann cells with S-100 protein and perineurial and intermediate cells, including socalled endoneurial fibroblasts, without S-100 protein. Morphological and functional transition seems to occur between Schwann cells and perineurial cells, and between perineurial cells and intermediate cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00687045
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  • 14
    Digitale Medien
    Digitale Medien
    Farber's disease in two siblings, sural nerve and subcutaneous biopsies by light and electron microscopy (1986)
    Springer
    Acta neuropathologica 72 (1986), S. 178-188 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Farber's disease ; Peripheral nerve ; Subcutaneous nodules ; Electron microscopy ; Ceramidase deficiency
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Two siblings born from consanguineous tunisian parents are reported. They showed a severe form of Farber's disease with prominent involvement of the central and peripheral nervous system: low conduction velocity was noticed in both children. Macular cherry red spots were observed in one of them. The diagnosis for the girl investigated was confirmed by evidence of ceramidase deficiency in cultured fibroblasts. Here we report the pathological findings in the subcutaneous nodules using light and electron microscopy (one case), and in sural nerves using morphometric studies (both cases). Varying morphological aspects of intracellular inclusions, depending on the tissues involved, are described and discussed. A review of all cases reported since Farber's first paper in 1952 is given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00685981
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  • 15
    Digitale Medien
    Digitale Medien
    Minisegments of newborn rat optic nerves in vitro: gliogenesis and myelination (1986)
    Springer
    Experimental brain research 65 (1986), S. 189-199 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Rat optic nerve ; Gliogenesis ; Myelination ; In vitro ; In vivo ; Electron microscopy ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The question of whether the development of CNS glial cells requires the presence of axons or not can be studied with in vitro systems. In order to compare the differentiation of glial cells during development in vitro with that in situ, we have selected the optic nerve, which is anatomically as well as histotypically a well defined structure. For the in vitro investigations, small explants, called minisegments, of newborn rat optic nerves were cultivated taking four major conditions into account: (1) the regular size of the minisegments should guarantee a permanent exchange of the culture medium in order to avoid cell death, (2) neither mechanical nor enzymatic dissociation of the tissue were applied, (3) the minisegments were explanted into flasks without substrate for cell adhesion and (4) the minisegments were under constant gyratory agitation. The following in situ results were obtained: optic nerves of newborn rats are morphologically characterized by the presence of naked axons, astrocytes, glial precursors, and the absence of both differentiated oligodendrocytes and myelin. At postnatal day 5 myelin sheaths are still absent. Two weeks after birth, differentiated oligodendrocytes and microglial cells are present and numerous axons are surrounded by compact myelin. The in vitro experiments show the following main results, which were obtained after 14 h, 2 d, 5 d and 14 d in culture: during time in culture, the shape of minisegment of newborn rat optic nerves undergoes drastic changes, which indicate high cellular dynamics. After 14 h in vitro, axonal profiles, cells with pyknotic nuclei as well as clusters of astrocytes and glial precursors are present. After 2 days in culture the axonal profiles disappeared and the number of degenerating cells decreased drastically. Many large cells, probably phagocytes containing inclusions and more cells are differentiated. At the stage of 5 d in vitro 4 major types of cells can be distinguished: differentiated oligodendrocytes, which form compact and loose myelin, astrocytes, large and small glioblasts and phagocytes. Immunoprecipitates for myelin basic protein and/or myelin associated glycoprotein were found in oligodendrocytes, in their processes and associated to the myelin. Processes of some astrocytes showed immunoreactive products of glial fibrillary acidic protein. After two weeks in culture, the minisegments were mostly composed of astrocytes, whereas oligodendrocytes became rare and phagocytes disappeared. It can be concluded that CNS glial cells can attain their structural and immunocytochemical characteristics in the total absence of neuronal cell bodies and axons. However, it can be speculated that neurons (or neuronal factors) could regulate the number of astrocytes and oligodendrocytes and keep these glial cells in a physiological equilibrium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00243842
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  • 16
    Digitale Medien
    Digitale Medien
    A paediatric case of sideroblastic anaemia (1986)
    Springer
    European journal of pediatrics 145 (1986), S. 422-427 
    Details
    ISSN: 1432-1076
    Schlagwort(e): CFU-E ; BFU-E ; Electron microscopy ; Sideroblastic anaemia ; Dyserythropoiesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We examined the morphological and functional characteristics of erythroblasts derived from marrow erythroid progenitor cells grown in a methylcellulose microculture, which were taken from a female child with rate atypical sideroblastic anaemia (SA) partially responsive to pyridoxine. Colony formation was within the normal range in three successive cultures (median values: 82.25 CFU-E and 16.4 BFU-E derived colonies/6.6×104 cells) compared to growth by normal cells (65-315 CFU-E and 9-40 BFU-E). We evaluated in vitro differentiation by biochemical microassay of a cytosol enzyme involved in the haeme pathway: uroporphyrinogen I synthase (UROS). The UROS values in the erythroid colonies from SA marrow were at the lower end of the normal range (median values: 6.7±0.3 and 14.4±3.8 pmol uroporphyrinogen/h in CFU-E and BFU-E-derived colonies respectively versus 17.4±7.3 and 25±7.2 pmol/h in CFU-E and BFU-E colonies from normal subjects. Ultrastructural examination of the SA erythroblasts from non-cultured bone marrow or derived from cultured BFU-E revealed the characteristic deposition of iron in mitochondria around the nucleus of most cells (ringed sideroblasts). However, the majority of cultured cells had marked dyserythropoietic featuress, with a large number of bilobulated or trilobulated crythroblasts, multiple cytoplasmic vacuoles, numerous abnormalities of the nucleus, and excessive membrane material beneath the plasma membrane, all features difficult to observe in non-cultured marrows.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00439253
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  • 17
    Digitale Medien
    Digitale Medien
    Cytomorphological changes in liver cells exposed to allyl and benzyl isothiocyanate and their cysteine and glutathione conjugates (1986)
    Springer
    Archives of toxicology 59 (1986), S. 103-110 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Cytotoxicity ; Cell morphology ; RL-4 hepatocyte ; Electron microscopy ; In vitro study ; Allyl isothiocyanate ; Benzyl isothiocyanate ; Tert-butylhydroperoxide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Since allyl isothiocyanate has been reported to be a bladder carcinogen and benzyl isothiocyanate is a known anti-carcinogen, it is important to know the mode of their cytotoxic action. This was investigated in a RL-4 hepatocyte cell line by studying the morphological effects of increasing concentrations of the isothiocyanates and their glutathione and cysteine conjugates. These effects were compared with those induced by tert-butylhydroperoxide which supposedly has its primary effect upon the cytosolic glutathione status and thus upon the integrity of Ca2+-sequestrating mitochondria. The results agree with the previously postulated role of conjugation in the exposure of cells to isothiocyanates: Conjugates show effects similar to those produced by the free parent compounds because conjugates release free isothiocyanates in aqueous solution. The cytomorphological effects increase in a more or less dose-dependent manner with increasing concentrations of isothiocyanate or exposure time. Probably due to increased exposure, suspended RL-4 cells are more sensitive to the toxic action than cells growing on a substrate. No qualitative differences were found between the effects of allyl and benzyl isothiocyanate, indicating that their different effects in vivo are perhaps related to organ-specific differences in equilibrium between the conjugated and unconjugated forms of the test substances. The first cytomorphological effects of isothiocyanates consist of surface blebbing (zeiosis) and swelling of dictyosomal cisternae. At higher concentrations swelling extends to vesicles of endoplasmic reticulum. Mitochondria are not affected until the cells reach the necrotic phase of injury. In contrast, tert-butylhydroperoxide causes mitochondrial damage in an early pase of toxic injury. The cellular symptoms suggest that the primary target of isothiocyanates is in the plasma membrane and the cellular membrane system, affecting the monovalent cation and water balance of the cell organelles rather than the Ca2+ homeostasis as in cells exposed to tert-butylhydroperoxide. Differences in lipophilicity may be at the basis of this differenc in primary action.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00286732
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  • 18
    Digitale Medien
    Digitale Medien
    An electron microscopic study of cerebral vasospasm with resultant myonecrosis in cases of subarachnoid haemorrhage, meningitis and trans-sylvian surgery (1986)
    Springer
    Journal of neurology 233 (1986), S. 348-357 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Cerebral vasospasm ; Myonecrosis ; Myofilament ; Calcium ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Electron microscopic data on the development of myonecrosis following cerebral vasospasm associated with subarachnoid haemorrhage, meningitis and trans-sylvian surgery are presented. The basic feature of myonecrosis was dissolution of myofilaments with resultant fine granular or filamentous material. The disintegrating cytoplasm often contained numerous glycogen granules, dense bodies, autophagic vacuoles and myelin-like membranous bodies. A well-developed sarcoplasmic reticulum was preserved despite myofilament dissolution, while mitochondria showed marked sweling. The nuclei showed either dilution of chromatin or pyknotic change. The basal lamina was remarkably thickened and maintained an irregular outline of the necrotic smooth muscle cells. Enlarged intercellular space contained abundant cellular debris, vesicular structures and connective tissue fibres. The pathogenesis of these changes is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00313921
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  • 19
    Digitale Medien
    Digitale Medien
    A three dimensional model of the photosynthetic membranes of Ectothiorhodospira halochloris (1986)
    Springer
    Archives of microbiology 146 (1986), S. 267-274 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Photosynthesis ; Membrane structure ; Electron microscopy ; Ectothiorhodospira ; Serial thin sectioning ; Three dimensional reconstruction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous “bridges”. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00403228
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  • 20
    Digitale Medien
    Digitale Medien
    Role of relA mutation in the survival of amino acid-starved Escherichia coli (1986)
    Springer
    Archives of microbiology 143 (1986), S. 400-402 
    Details
    ISSN: 1432-072X
    Schlagwort(e): E. coli relA +/relA ; Starvation survival ; Guanosine tetraphosphate ; Electron microscopy ; Glycogen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Amino acid-starved cells of Escherichia coli relA +, which contain a large number of glycogen particles, are able to survive in phosphate buffer for a longer time period than their relaxed counterparts. With regard to NH 4 + starvation differences in the survival of both strains were not found. NH 4 + starved cells of E. coli relA are able to synthesize glycogen but amino acid-starved cells of the relA strain are not. We suggest that the synthesis of glycogen triggered by guanosine tetraphosphate during amino acid starvation is responsible for the prolonged viability of the E. coli relA + strain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00412809
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  • 21
    Digitale Medien
    Digitale Medien
    Bradyrhizobium japonicum mutants defective in root-nodule bacteroid development and nitrogen fixation (1986)
    Springer
    Archives of microbiology 144 (1986), S. 355-366 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Bradyrhizobium ; Electron microscopy ; Mutants ; Nitrogen fixation ; Nodulation ; Soybean ; Symbiosis ; Transposon Tn5
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genome of the slow-growing Bradyrhizobium japonicum (strain 110) was mutagenized with transposon Tn5. A total of 1623 kanamycin/streptomycin resistant derivatives were screened in soybean infection tests for nodulation (Nod) and symbiotic nitrogen fixation (Fix). In this report we describe 14 strains possessing a stable, reproducible Nod+Fix- phenotype. These strains were also grown under microaerobic culture conditions to test them for free-living nitrogen fixation activity (Nif). In addition to strains having reduced Fix and Nif activities, there were also strains that had reduced symbiotic Fix activity but were Nif+ ex planta. Analysis of the genomic structure revealed that the majority of the strains had a single Tn5 insertion without any further apparent physical alteration. A few strains had additional insertions (by Tn5 or IS50), or a deletion, or had cointegrated part of the vector used for Tn5 mutagenesis. One of the insertions was found in a known nif gene (nifD) whereas all other mutations seem to affect different, hitherto unknown genes or operons. Several mutant strains had an altered nodulation phenotype, inducing numerous, small, widely distributed nodules. Light and electron microscopy revealed that most of these mutants were defective in different stages of bacteroid development and/or bacteroid persistence. The protein patterns of the mutants were inspected by two-dimensional gel electrophoresis after labelling microaerobic cultures with l-(35S)methionine. Of particular interest were mutants lacking a group of proteins the synthesis of which was known to be under oxygen control. Such strains can be regarded as potential regulatory mutants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00409885
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  • 22
    Digitale Medien
    Digitale Medien
    Pathogenesis of pulmonary fibrosis induced by chrysotile asbestos (1986)
    Springer
    Virchows Archiv 408 (1986), S. 329-346 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Pulmonary fibrosis ; Asbestosis ; Chrysotile ; Macrophages ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A single instillation of 1 mg chrysotile B with a fiber length between 0.05 and 0.2 µm in 0.1 ml tricaprylin was made via a polyvinyl catheter into the lower lobe of the right lung of 120 six-week-old Wistar rats under anesthesia. The animals were killed at intervals between five minutes and two years. The lower lobes of the right lung were investigated by light and electron microscopy. The process of pulmonary fibrosis induced by asbestos can be subdivided into four phases: these are the phase of phagocytosis (five to 15 min), the phase of granuloma formation (between one and two weeks), the phase of septal fibrosis (between two and six months) and finally the scar stage (after one year). After instillation of small asbestos fibers into the alveoli, a major proportion of these fibers is phagocytosed by alveolar macrophages after five minutes and leaves the lungs via the airways. A proportion of the fibers penetrates through the alveolar wall (mostly conveyed by type I pneumocytes) and reaches the interstitium of the lungs. There, the fibers are taken up by pulmonary tissue macrophages and giant cells. Within the phagolysosomes, the fibers are broken down into fragments less than 0.01 µm in length. Type II pneumocytes produce surfactant in excess. These cells become necrotic, tubular myelin and lamellar bodies pass into the alveoli and into the interstitium. Surfactant is phagocytosed by resident macrophages. These macrophages phages can break down. Besides asbestos and surfactant, mediators of fibrillogenesis are released. Macrophages following up from blood monocytes ingest surfactant and asbestos. This process is perpetuated up to complete scarring. After two years, small asbestos fibers less than 0.01 µm long are present in fibroblasts and pleural mesothelia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00707692
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  • 23
    Digitale Medien
    Digitale Medien
    Diversity of Vicia faba circular mtDNA in whole plants and suspension cultures (1986)
    Springer
    Theoretical and applied genetics 72 (1986), S. 541-547 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Mitochondrial DNA of plants ; Electron microscopy ; Suspension culture ; Vicia faba
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A comparative analysis of the Vicia faba mitochondrial genome in whole plants and in longterm suspension culture has been conducted. Restriction fragment patterns of the mtDNA isolated from these two sources were notably different. Electronmicroscopic analysis also revealed significant differences. Large circular mtDNA patterns shifted from a 37–80 kb subpopulation, which was predominant in whole plants, to 18–34 kb subpopulations although in both classes notable quantities of circular molecules of 80 to 120 kb and more were also found. Both in whole plant and suspension culture cells very large circular DNAs were observed. Some of them had lengths nearly 290 kb and could be considered as evidence of the existence of master chromosomes. The minicircular DNA population was also altered. In the suspension culture we observed a notable increase of percentage of minicircles with sizes near 1 kb. Simultaneously, the percentage of minicircles with sizes near 3.5–10 kb significantly increased in suspension culture cells. In addition, a new peak (10–12 kb) of minicircles appeared. Copy number alterations for some sequences homologous to CCC1A, CCC1B and CCC2 (Negruk et al. 1982, 1985) were shown. Southern hybridization revealed the existence of a family of minicircles having sizes 1.4–2 kb with predominance of CCC1A, CCC1B and CCC2. The copy numbers of CCC1B and some minor minicircles was changed in the suspension culture when compared with the whole plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00289538
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  • 24
    Digitale Medien
    Digitale Medien
    Lipokeratinocytes of the epidermis of a cetacean (Phocena phocena) (1986)
    Springer
    Cell & tissue research 244 (1986), S. 385-394 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cetaceans ; Lamellar bodies ; Epidermal lipids ; Permeability barrier ; Electron microscopy ; Phocena phocena
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Biochemical and ultrastructural analysis of epidermis from the porpoise, Phocena phocena, revealed certain similarities and differences between cetaceans and terrestrial mammals. The predominant cell of cetacean epidermis, not found in normal terrestrial mammals, is a lipoker-atinocyte, which elaborates not only keratin filaments, but also two types of lipid organelles: first, lamellar bodies, morphologically identical to those of terrestrial mammals, are elaborated in great abundance in all suprabasal epidermal layers, forming intercellular lipid bilayers in the stratum corneum interstices: and second, non-membrane-bounded droplets appear and persist in all epidermal layers. Although the porpoise lipokeratinocyte morpologically resembles the sebokeratocyte of avians in certain respects, nonmembrane-bounded lipid droplets are not released into the intercorneocyte space as they are in avian stratum corneum. Whereas phospholipid/neutral lipid gradients are similar in porpoise and terrestrial mammals, PAS-positive glycoconjugates, specifically glycosphingolipids, are retained in porpoise stratum corneum, but lost from these layers in terrestrials. The novel, non-polar acylglucosyl-ceramides, which also are lost during cornification in terrestrial mammals, are retained in porpoise stratum corneum. The lipid components of porpoise lipokeratinocytes appear to subserve not only barrier function in a hypertonic milieu, but also underlie the unique buoyancy, streamlining, insulatory, and caloric properties exhibited as adaptations to the cetacean habitat.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219214
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  • 25
    Digitale Medien
    Digitale Medien
    Collagen remodeling during decidualization in the mouse (1986)
    Springer
    Cell & tissue research 244 (1986), S. 443-448 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Collagen ; Uterus ; Decidua ; Mouse ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An ultrastructural study of the features and distribution of collagen fibrils was performed in the endometrium of virgin and pregnant (2nd to 11th day) mice. Collagen-containing structures were observed in the cytoplasm of fibroblasts on the 2nd day of pregnancy. Treatment of tissues with lanthanum nitrate established that these structures were intracytoplasmic. Their association with lysosome-like bodies suggested the occurrence of intracellular digestion of collagen, probably connected with remodeling of the endometrial stroma prior to decidualization. On the 4th day of pregnancy, very few collagen fibrils were present in the intercellular space. From the 6th day of pregnancy onwards, “thick” collagen fibrils were observed between decidual cells. The diameter of these fibrils measured up to 300 nm whereas the fibrils present in the endometrium of virgin mice measured 40–68 nm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219220
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  • 26
    Digitale Medien
    Digitale Medien
    Culture of intramural cardiac ganglia of the newborn guinea-pig (1986)
    Springer
    Cell & tissue research 244 (1986), S. 605-612 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Heart innervation ; Tissue culture ; Autonomic ganglia ; Non-neuronal cells ; Cell interrelationships ; Electron microscopy ; Guinea-pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The present study describes the ultrastructure of non-neuronal cells and their interrelationships with intracardiac neurones present in cultures dissociated atria and interatrial septum from newborn guinea-pig. When compared with the in situ preparation, most of these features in culture were similar to those observed in situ, but some differences were also apparent. Both mature and immature Schwann cells were observed in culture, and as in situ, the latter were closely associated with intracardiac neurones, whilst the former were more widely separated. The ultrastructure of satellite cells was more variable in culture than in situ: three general types were distinguished on the basis of their 10-nm filament content. This variation could be due to conditions of culture. Interstitial cells were present in culture and closely resembled those described in situ, although there was less space between cultured interstitial cells and their associated cells. Many fibroblasts, some myoblasts and a few mast cells were also found in the culture preparations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00212540
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  • 27
    Digitale Medien
    Digitale Medien
    Culture of intramural cardiac ganglia of the newborn guinea-pig (1986)
    Springer
    Cell & tissue research 244 (1986), S. 595-604 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Heart innervation ; Tissue culture ; Autonomic ganglia ; Neurones ; Small granule-containing cells ; Electron microscopy ; Guinea-pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of cultured intrinsic neurones and SIF (small intensely fluorescent) cells dissociated from the atria and interatrial septum of newborn guinea-pig heart has been studied for the first time and compared with these cells in situ. Mononucleate and binucleate neuronal somata and their processes were observed in the culture preparation; their ultrastructure was similar to that of neurones in intracardiac ganglia observed in situ. The number of neurites associated with neuronal cell bodies increased after the first week in culture. A subpopulation of intracardiac neurones showed abnormalities in culture, comparable to the changes previously described in neurones of the monkey heart after unilateral vagotomy in situ. Small granule-containing cells were observed in culture, corresponding to those described in the heart in situ. One type of large process in the culture preparation containing densely packed mitochondria has not been seen in situ, suggesting that changes in cell ultrastructure due to the conditions of culture cannot be discounted. However, the ultrastructure of the cultured cells was, for the most part, consistent with that of the same cell type in situ, indicating that the culture preparation may be a useful model for investigation of the roles and interactions of intramural neurones in the heart, which are inaccessible for such studies in situ.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00212539
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  • 28
    Digitale Medien
    Digitale Medien
    Morphological evidence for the existence of a more complex cytoskeleton in Amoeba proteus (1986)
    Springer
    Cell & tissue research 246 (1986), S. 163-168 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cytoskeletal organization ; Filaments ; Triton extraction ; Replica technique ; Electron microscopy ; Amoeba proteus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Various stabilization and extraction procedures were tested to demonstrate the ultrastructural organization of the cytoskeleton in normal, locomoting Amoeba proteus. Most reliable results were obtained after careful fixation in glutaraldehyde/lysine followed by prolonged extraction in a polyethylene glycol/Triton X-100 solution. Before dehydration in a graded series of ethanol and critical-point drying, the amoebae were split by the sandwich-technique, i.e., by mechanical cleavage of cells mounted between two poly-L-lysine-coated glass slides. Platinum-carbon replicas as well as thin sections prepared from such cell fragments revealed a cytoskeleton composed of at least four different types of filaments: (1) 5–7-nm filaments organized as a more or less ordered cortical network at the internal face of the plasma membrane and probably representing F-actin; (2) 10–12-nm filaments running separately or slightly aggregated through the cytoplasm and probably representing intermediate filaments; (3) 24–26-nm filaments forming a loose network and probably representing microtubules; and (4) 2–4-nm filaments as connecting elements between the other cytoskeleton constituents. Whereas microfilaments are responsible for protoplasmic streaming and other motile phenomena, the function of intermediate filaments and cytoplasmic microtubules in amoebae is still obscure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00219013
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  • 29
    Digitale Medien
    Digitale Medien
    Structure and development of the surface coat of erythrocytic merozoites of Plasmodium knowlesi (1986)
    Springer
    Cell & tissue research 245 (1986), S. 281-290 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Electron microscopy ; Malaria parasites ; Merozoites ; Surface coat ; Maturation ; Plasmodium knowlesi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The surface of extracellular merozoites of P. knowlesi is covered with a coat 15–20 nm thick, made up of clusters of filaments standing erect on the plasma membrane. Filaments have stems 2 nm thick, the peripheral ends of which are complex, branching or ending in long trailing threads. Coat filaments occur on the surface of the parasite in regular rows at an early schizont stage, and persist until well after merozoite release. They are sensitive to trypsin and papain, and bind ethanolic phosphotungstate, indicating a proteinaceous nature. They are also removed by exposure to phosphate-buffered saline. Filaments bear negative charges, binding cationised ferritin throughout the depth of the coat and staining with ruthenium red. They cover the whole merozoite surface and mediate intercellular adhesion at distances of 15–150 nm, membrane to membrane. It is suggested that these filaments correspond to a major merozoite surface protein, and are important in the initial capture of red cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00213933
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  • 30
    Digitale Medien
    Digitale Medien
    Nephridial innervation in the leech Hirudo medicinalis L. (1986)
    Springer
    Cell & tissue research 245 (1986), S. 397-404 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Leech ; Nephridium ; Innervation ; Electron microscopy ; Cobalt filling ; Hirudo medicinalis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The main organs for salt and water homeostasis in the medicinal leech, the nephridia, were found to be densely innervated by a single branch of the corresponding median anterior segmental nerve. The projections of two different neurons into the nephridia are described: 1. Dendritic projections of the previously identified, afferent ‘nephridial nerve cell’, a possible salt receptor, lie between the urine forming cells and the blood vessels supplying the nephridium without making any contact. 2. Projections of an unidentified neuron which contains dense-core vesicles (85 nm) as well as smaller clear vesicles (45 nm) contact the primary urine forming canaliculus cells. The neurosecretory role of these neurons is considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00213947
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  • 31
    Digitale Medien
    Digitale Medien
    The coxo-trochanteral muscle receptor organ of locusts (1986)
    Springer
    Cell & tissue research 243 (1986), S. 517-524 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Muscle receptor organ ; Electron microscopy ; Tubular body ; Mechanosensory transduction ; Locust, Locusta migratoria migratorioides (R.&F.)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The coxo-trochanteral muscle receptor organ of the hind leg of the locust Locusta migratoria migratorioides (R.&F.) has been investigated by use of scanning and transmission electron microscopy with special emphasis on its distal attachment site. The overall morphology of the receptor muscle, the sensory neuron and its dendrites was found to share many common features with other arthropod sense organs of that type with two important differences: (1) the connective tissue segment (= intercalated tendon) is extremely short compared to that of other muscle receptor organs; (2) the naked dendritic terminals of the non-ciliated, multipolar sensory neuron of the organ contain clusters of microtubules, interconnected by an amorphous matrix, that resemble the tubular bodies of ciliated, epithelial receptor cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218058
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  • 32
    Digitale Medien
    Digitale Medien
    The hypothalamo-hypophysial system of the frog Rana temporaria (1986)
    Springer
    Cell & tissue research 243 (1986), S. 649-654 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Median eminence ; Peptidergic projections ; Aminergic projections ; Electron microscopy ; Autoradiography ; Frog (Rana temporaria)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The median eminence (ME) of the adult frog, Rana temporaria, was studied by means of electron microscopy including quantitative electron-microscopic autoradiography. In frogs captured in May and June numerous peptidergic neurosecretory fibres extending via the internal zone to the pars nervosa display large swellings containing few granules, mitochondria, neurotubules and cisternae of the smooth endoplasmic reticulum. In addition, few secretory globules up to 1.5 μm in diameter occur in these varicosities. In animals collected during the autumn period many of these neurosecretory swellings filled with neurosecretory granules and polymorphic inclusions resemble Herring bodies. Three types of granule-containing neurosecretory fibres were observed in the external zone (EZ) of the ME of adult R. temporaria. Peptidergic A1- and A2-type fibres are characterized by granules 150–220 nm and 100–160 nm in diameter, respectively. Monoaminergic fibres of type B with granules approximately 100 nm in diameter represent ∼ 50% of all neurosecretory elements in the EZ of the frog ME; ∼12% of the total number of granule-bearing axons in the EZ actively taking up radiolabelled 5-hydroxytryptophan are thought to be serotoninergic terminals. Neurosecretory terminals of all types and glial vascular endfeet establish direct contacts with the perivascular space of the primary portal capillaries. Some neurosecretory terminals are separated from the lumen of the third ventricle by a thin cytoplasmic lamella of tanycytes. The possible physiological significance of this structural pattern is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218074
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  • 33
    Digitale Medien
    Digitale Medien
    An ultrastructural study of embryonic chick retinal neurons in culture (1986)
    Springer
    Cell & tissue research 245 (1986), S. 563-577 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Chick retina ; Tissue culture ; Electron microscopy ; Development, ontogenetic ; Differentiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The differentiation of cells and synapses in explants of 9-day-old chick embryo retina has been studied by light and electron microscopy over a period of 35 days in vitro, and samples of retina from the 9-day chick foetus were directly fixed and prepared for study. At the time of explantation the retinae were poorly differentiated and no lamination was apparent. From day 14 onwards, (i) outer and inner nuclear layers (ONL, INL) separated by a layer of neuropil corresponding to the outer plexiform layer (OPL) and (ii) a layer of scattered large ganglion cells separated from the INL by a zone of neuropil resembling the inner plexiform layer (IPL) were apparent, and (iii) a well-differentiated outer limiting membrane was established close to the surface of the explants. In the oldest cultures some development of photoreceptor outer segments occurred but a distinct optic nerve fibre layer did not form. Although cell identification presented problems even in the oldest cultures, the major retinal cell types described in vivo could be identified. Photoreceptor cells developed pedicles in the OPL which became filled with synaptic vesicles and synaptic ribbons and established ribbon synapses (including triads) with and were commonly invaginated by processes from horizontal and bipolar cells. Processes of bipolar cells in the IPL formed simple and dyad synapses. At least two types of presynaptic amacrine cells were also identified in the INL, one of which contained large numbers of dense-core vesicles. The ganglion cells, though sparse, were large and well differentiated. These findings show that all the major neuronal types of the retina are capable of developing and differentiating in vitro, lagging behind the time-table of development and differentiation in vivo by approximately 7 days, but resulting in a histotypically organised retina with synaptic neuropil showing many similarities to the corresponding neuropil in vivo.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218558
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  • 34
    Digitale Medien
    Digitale Medien
    Embryonic cholinesterase activity during morphogenesis of the mouse genital tract (1986)
    Springer
    Cell & tissue research 244 (1986), S. 153-164 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cholinesterase ; Genital tract ; Mesenchyme ; Histochemistry ; Electron microscopy ; Mouse embryo
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the genital tract of male and female mouse embryos cholinesterase activity is described that is independent from innervation. The enzyme activity is localized in the mesenchyme at the junction of Wolffian and Müllerian ducts with the urogenital sinus. During male development prostate buds and vesicular glands grow out into the cholinesterase-active mesenchyme. During female development the active mesenchyme participates in the downgrowth of the vaginal anlage. Ultrastructurally the cholinesterase activity is localized in the perinuclear cisterna and in smooth endoplasmic reticulum of the mesenchymal cells. The enzyme activity disappears with definitive differentiation of the tissue. The embryonic cholinesterase is a component of a primitive muscarinic system. Its relation to the morphogenetic action of testosterone and its possible general functions are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218393
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  • 35
    Digitale Medien
    Digitale Medien
    Cytoplasmic virus-like particles associated with the nucleolus in wheat, similar to “S bodies” and retroposon particles (1986)
    Springer
    Protoplasma 133 (1986), S. 160-164 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Cytoplasm ; Electron microscopy ; Nucleolus ; Virus-like particles ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Wheat roots from germinating seedlings of Chinese spring wheatTriticum aestivum grown for 36 hours at 20°C were examined by conventional thin-section electron microscopy. Virus-like particles were seen inside a large cytoplasmic intrusion into the nucleus having the appearence of a nucleolar vacuole. The particles were isometric and about 50 nm in diameter with a membrane-like coat and a small core. The cytoplasmic intrusion was bounded by nuclear envelope with pores apparent where it abutted nucleoplasm. The particles are similar to previously reported solitary particles “S bodies” from a range of plants but are also similar in size and morphology to the retroposon particles associated with copia like elements in other organisms. The position of the virus-like particles in the young wheat roots is discussed in relation to interactions with components of the cell skeleton.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01304631
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  • 36
    Digitale Medien
    Digitale Medien
    Influence of culture medium pH on charasome development and chloride transport inChara corallina (1986)
    Springer
    Protoplasma 130 (1986), S. 5-11 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Chara corallina ; Charasome development ; Chloride transport ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Internodal cells ofChara, grown in culture either at pH 5.7, 6.5 or 7.5, were studied to determine their chloride influx capability, the quantitative aspects of charasome morphology and the degree to which these two parameters could be correlated. In cells grown at pH 5.7 the charasomes were relatively small, were widely spaced on the plasma membrane, and contributed only a 0.6% increase to the surface area of the plasma membrane in the acid region of the cell. In contrast, the charasome membrane surface area of cells grown at pH 7.5 had increased × 19, the density of charasomes on the cell surface increased × 42, thus producing a × 3.57 increase in the acid region plasma membrane surface area. Chloride influx in cells grown at pH 7.5 was × 8.7–12.7 greater than in cells grown at pH 5.7. Cells that had been starved of chloride exhibited a × 2.4 average increase in the rate of chloride influx. Our observations establish the existence of a positive correlation between the rate of chloride influx and the increase in membrane surface area due to charasomes, although other factors, such as the effect of pH on transport-related enzymes, and the effect of charasome structure on chemical equilibria, may also be of importance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01283326
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  • 37
    Digitale Medien
    Digitale Medien
    The effects of raised phosphate level on the energy metabolism, contractile function, and fine structure of oxygenated and oxygen-deficient myocardium (1986)
    Springer
    Heart and vessels 2 (1986), S. 6-14 
    Details
    ISSN: 1615-2573
    Schlagwort(e): Inorganic phosphate ; Normoxia/anoxia ; ATP ; Glycogen ; Cardiac function ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The possible role of inorganic phosphate (Pi) in depressing the contractility of oxygen-deficient myocardium was investigated by examining the effects of 30 mM Pi on the cardiac function and myocardial biochemistry and fine structure in normoxic and anoxic Langendorff-perfused isolated rat hearts. In normoxia, the intracellular Pi level increased three-fold, the ATP content remained normal, and there was moderate loss of glycogen only. Contractile performance (as assessed from systolic pressure recordings) was significantly depressed, as was the heart rate for the first 10 min. The myocardial fine structure showed persistent glycogen, marked relaxation of myofibrils, and a higher incidence of vacuolation than in hearts with normal Pi. In anoxia, the intracellular Pi level was comparable with that of the perfusate and both ATP and glycogen were severely depleted. Contractile performance and heart beat ceased completely at 15 min, although in anoxic controls both persisted at low levels for at least 25 min. In anoxia, Pi also depressed coronary flow rate. In the inner half of the ventricular wall of oxygen-depleted hearts, where flow became reduced after 15 or more min, Pi markedly reduced the formation of intramitochondrial densities and augmented mitochondrial swelling and ischaemic contracture, which extended out through the mid-myocardium. In the outer half of the wall, where flow remained high, it promoted severe dilatation of the sarcoplasmic reticulum vesicles and undifferentiated regions of the intercalated discs. The observed effects in normoxia are probably attributable at least in part to the lowering of the free Ca2+ concentration of the perfusate by the increased Pi level. The effects in anoxia may be related chiefly to the critical reduction of available intracellular Ca2+ and the more rapid and extensive development of ischaemic contracture.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02060238
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  • 38
    Digitale Medien
    Digitale Medien
    In vivo homologous recombination intermediates of yeast mitochondrial DNA analyzed by electron microscopy (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 421-428 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Recombination intermediates ; Mitochondrial DNA ; Electron microscopy ; Saccharomyces cerevisiae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary To study the structure of in vivo mitochondrial DNA recombination intermediates in Saccharomyces cerevisiae, we used a deletion mutant of the wild type mitochondrial genome. The mtDNA of this petite is composed of a direct tandem repetition of an ∼4,600 pb monomer repeat unit with a unique HhaI restriction enzyme site per repeat. The structure of native mtDNA isolated from log phase cells, and mtDNA crosslinked in vivo with trioxsalen plus UVA irradiation, was studied by electron microscopy. Both populations contained crossed strand “Holliday” type recombination intermediates. Digestion of both non-crosslinked and crosslinked and mtDNA with the enzyme HhaI released X and H shaped structures composed of two monomers. Electron microscopic analysis revealed that these structures had pairs of equal length arms as required for homologous recombination intermediates and that junctions could occur at points along the entire monomer length. The percentage of recombining monomers in both non-crosslinked and trioxsalen crosslinked mtDNA was calculated by quantitative analysis of all the structures present in an HhaI digest. The relationship between these values and the apparent dispersive replication of mtDNA in density-shift experiments and mtDNA fragility during isolation is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00333272
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  • 39
    Digitale Medien
    Digitale Medien
    Electron microscopic localization of hydrogenase genes on the megaplasmid pHG 1 in Alcaligenes eutrophus (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 476-480 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Hydrogen bacterium ; Hydrogenase genes ; Megaplasmid pHG1 ; Localization ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Plasmids carrying hydrogenase genes in Alcaligenes eutrophus wild type H 16 and in two transposon Tn5 —induced mutants have been investigated by electron microscopy. Besides the pHG1 megaplasmid (458±27 kb) carrying genes coding for structural and regulatory properties of hydrogenases, small plasmids of unknown significance have been detected. The sizes of EcoRI fragments obtained from pHG1 were measured from electron micrographs. They were significantly different from sizes determined previously by agarose gel electrophoresis. Plasmid pHG1 isolated from the wild type H 16 was shown to contain two inverted repeats (IR 16-1 and IR 16-2) with sizes similar to known transposons. From electron microscopic hybridization studies, it was deduced that the sites of insertion of Tn5 into a regulation gene on pHG1 for both soluble and membrane-bound hydrogenase, and of Tn5-Mob into the gene coding for structural properties of the soluble hydrogenase, are about 67.2 kb apart. One of the inverted repeats (IR 16-1) was localized in between these sites.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00333280
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  • 40
    Digitale Medien
    Digitale Medien
    Abnormal mucociliary function in a mucocoele of the maxillary antrum (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 207-210 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Maxillary sinus mucocoele ; Mucociliary system ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We have examined the mucociliary function present in a mucocoele of the maxillary antrum and have found certain abnormalities in the tissues studied. Our findings also indicate that the mucocoele's intrinsic pathology is too complex to be improved by any conservative treatment and justifies its surgical removal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00470623
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  • 41
    Digitale Medien
    Digitale Medien
    An experimental study of auditory dysfunction associated with hyperlipoproteinemia (1986)
    Springer
    European archives of oto-rhino-laryngology and head & neck 243 (1986), S. 242-245 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Hyperlipoproteinemia ; Auditory dysfunction ; Cochlea ; Histochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We sought to clarify whether or not hyperlipoproteinemia induces auditory dysfunction. In so doing, we studied the general states and cochlear pathologies of guinea pigs after the administration of a hyperlipid diet for 3 months. Serum biochemistries indicated marked elevations of cholesterol, high density lipoprotein (HDL)-cholesterol and low density lipoprotein (LDL) levels. An increased auditory threshold varying from 10 to 20 dB was observed in 40% of the guinea pigs using auditory brainstem responses. Histochemical study of the inner ear revealed variations in lipid metabolism and partial disorders of the outer hair cells. Electron microscopic observations showed vacuolar and parenchymal protrusions on the surfaces of the stria vascularis and Corti's organ, and vacuolar degeneration was seen around the capillary vessels of the vascular stria. Our data has shown that the auditory dysfunction present in the inner ear was less marked than were the morphological changes seen. Our findings suggest that other factors besides hyperlipoproteinemia are involved in the development of severe auditory damage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00464438
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  • 42
    Digitale Medien
    Digitale Medien
    A different view of the assumed stress hybrid method (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 11-16 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A somewhat unconventional, yet simple, derivation of the assumed stress hybrid formulation is presented in which its relationship with displacement and stress-based finite element models is demonstrated. This gives insight into the hybrid method and shows that it represents a least energy fit of an equilibrium stress field to a displacement model strain field. By this means the attributes of both fields may be exploited in extending the analysis scope of hybrid models.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220103
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  • 43
    Digitale Medien
    Digitale Medien
    A new nine node degenerated shell element with enhanced membrane and shear interpolation (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 73-92 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A new nine node degenerated shell element is presented in this paper. In the formulation of the new element, an enhanced interpolation of the transverse shear strains in the natural co-ordinate system is used to overcome the shear locking problem, and an enhanced interpolation of the membrane strains in the local Cartesian co-ordinate system is applied to avoid membrane locking behaviour. It is shown that the resulting element has the requisite number of zero eigenvalues and associated rigid body modes. The element does not exhibit membrane or shear locking for large span/thickness ratios. To illustrate the good performance of the new element some examples are presented including comparisons with the behaviour of the selectively integrated Lagrangian degenerated shell elements.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220107
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  • 44
    Digitale Medien
    Digitale Medien
    A study on the linear elastic stability of Mindlin plates (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 117-132 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The debate on the performance of Lagrangian and Serendipity elements in Mindlin's plate theory has been going on for quite some time. Limited published results for static and vibration analysis based on exact integration demonstrated a drastic deterioration in accuracy as the thickness of the plate decreases, and reduced/selective integration schemes have been suggested to improve their performance. Appreciable improvement for Lagrangian elements has been recorded, but it is only marginal for the Serendipity elements. On the strength of such observations one would then be tempted to rule out the exact integration schemes and Serendipity elements.In this paper, the above problem is reviewed for stability analysis of plates. Two elements are chosen from each family, one representing the higher order and the other the lower order element. Contrary to published results, all elements can attain very accurate solutions independent of the integration schemes for a sufficiently restrained plate, although in general the Serendipity elements will require a more refined mesh than the Lagrangian ones. However, for loosely restrained plates, the solution failed when integration is performed by reduced/selective schemes. The failure marks the limitation of the reduced/selective schemes which have somehow introduced spurious modes into the system, but on the other hand it is ironical that these spurious modes in fact contribute to the improvement of performance of the restrained cases. Therefore, one can equally improve the Serendipity elements by a selective scheme which can introduce additional zero modes. A scheme based on (5 × 5) integration points for flexural stiffness and (3 × 3) integration points for shear stiffness improved the 17SE (Serendipity elements) remarkably. However, because of the lack of bounds in most cases, the use of reduced/selected schemes is still not recommended. Finally, this paper also proposed an approximate formulation of the geometric stiffness matrices to replace the full formulation. Such an approximate formulation reduces the number of variables considerably in the eigenvalue search and can still give reasonably accurate results for thin plates with a/t 〉 15.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220109
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  • 45
    Digitale Medien
    Digitale Medien
    Ultimate load behaviour of reinforced concrete plates and shells under dynamic transient loading (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 189-208 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper considers a layered thick shell finite element procedure for determining the dynamic transient nonlinear response of plates and shells. The degenerated three-dimensional isoparametric shell element with independent rotational and translational degrees-of-freedom is employed and a layered formulation is adopted to represent the steel reinforcement and to simulate progressive concrete cracking through the thickness. The dynamic yielding function is assumed to be a function of the current strain rate, in addition to being total plastic strain or work dependent. The concrete model also simulates both compressive crushing and tensile cracking behaviours and an implicit Newmark algorithm is employed for time integration of the equations of motion. Several numerical examples are presented for both slab and shell structures and the results obtained compared with those from other sources wherever available.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220114
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  • 46
    Digitale Medien
    Digitale Medien
    Program structure and architecture for a finite element machine (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 241-248 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Superproblems in finite elements require either general-purpose or special-purpose computing machines whose capabilities are very much greater than those currently existing. The advantage of the latter type of machine is that it can be highly optimized for the particular class of problem for which it is designed and can, in principle, for a given generation of hardware, be designed to operate at a higher speed than a corresponding general-purpose computer. The Parallel Finite Element Machine (PARFEM) investigated at the University of Calgary has an architecture based on the finite element computational algorithms and employs a combination of parallel and vector processing. The overall architecture and program structure is described and the major design considerations outlined.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220118
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  • 47
    Digitale Medien
    Digitale Medien
    Preface (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. i 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220202
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  • 48
    Digitale Medien
    Digitale Medien
    An inverse method for the design of axisymmetric optimal diffusers (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 377-394 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An inverse inviscid-boundary-layer interaction scheme is presented for the optimal design of axisymmetric ducts for subsonic, rotational flows. Distribution of the shape factor H on the duct wall, giving minimum total pressure loss and maximum static pressure rise, is used as boundary condition for the inverse integral boundary-layer solution, to obtain the velocity and displacement thickness distributions on the wall. Vector addition of the inviscid core radius, derived from the solution of the inverse inviscid flow equations, and the displacement thickness produces the desired duct shape.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220207
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  • 49
    Digitale Medien
    Digitale Medien
    A natural formulation for the solution of two-dimensional or axisymmetric inverse problems (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 451-463 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220211
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  • 50
    Digitale Medien
    Digitale Medien
    Computer simulation of crash phenomena (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 497-519 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The paper summarizes preliminary work on crash analysis25-27 performed on an extended finite element model as provided by the nonlinear LARSTRAN program package at ICA. The essential methodology is evolved along the natural finite element approach. Also overviewed are solution techniques for the nonlinear equations of motion. The application of a simple folding mechanism is indicated and crashworthiness computations of car structures are described.
    Zusätzliches Material: 23 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220303
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  • 51
    Digitale Medien
    Digitale Medien
    Shallow water problems: A general explicit formulation (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 547-574 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: We present in this paper a general formulation for shallow water equations which is capable of solving problems of induced harbour oscillation, tidal flow, tsunami propagation, dispersion of pollutant, etc.The shallow water equations are written in a novel fully conservative form. The solution algorithm is based on an explicit time integration procedure which exploits the conservative properties of the governing equations and incorporates accurate treatment of convective terms without introduction of artificial damping. Its accuracy and low cost of computation make it attractive vis-à-vis existing procedures.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220305
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  • 52
    Digitale Medien
    Digitale Medien
    Thickness effects of CCT specimens (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 623-635 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: First, the three-dimensional elasto-plastic analyses of 1CT and 18 mm thick CCT specimens are carried out by using the finite element method, and the thickness effects of both specimens are studied. In elastic states, there is no significant difference between the CT and CCT specimen in the distribution of the J-integral along the straight or curved crack front. However, in elasto-plastic states, quite the contrary tendency is obtained in the distributions of J x and COD along the curved crack front for both specimens. Secondly, elasto-plastic analyses are carried out for CCT specimens of four kinds of thickness (B = 200, 18, 6 and 4 mm). The distributions of the J-integral along the crack front are obtained and compared. Finally, the availability of the JR value is examined, which is evaluated from the load versus displacement curve by using Rice's formula.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220308
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  • 53
    Digitale Medien
    Digitale Medien
    The patch test - a condition for assessing FEM convergence (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 39-62 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper discusses various forms of the Irons patch test and shows again that its satisfaction is a necessary convergence condition being equivalent to consistency, Further, it is shown that the test can be applied for verification of stability requirements, thus providing also a sufficient condition of convergence. The patch test is useful in testing the order of asymptotic convergence and the satisfaction of the test gives a guide for development of certain incompatible element forms.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220105
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  • 54
    Digitale Medien
    Digitale Medien
    TRUNC for shells - an element possibly to the taste of Bruce Irons (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 93-115 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: In his delightful and original textbook,18 Bruce Irons introduces the chapter of plate bending with the remark ‘History of disasters, but the pioneering days are past’. This is certainly true. On the other hand, we learn in the same context from Irons: ‘We believe that the world has not yet exhausted the older formulations.’ In this paper we present a review of theoretical aspects of the plate-bending triangle TRUNC (Reference 4), together with extensive tests in linear statics, dynamics, buckling and nonlinear large deformations both for plates and shells. The unconventional TRUNC model is based on the patch test, which was originated by Irons.1 In spite of its limited theoretical foundation, the performance of this element on a fairly broad field of applications appears at least from the practical point of view very satisfactory.
    Zusätzliches Material: 23 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220108
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  • 55
    Digitale Medien
    Digitale Medien
    Relations between incompatible displacement model and hybrid stress model (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 173-181 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An examination of the variational formulations confirms the similarity between the incompatible displacement model and the assumed stress hybrid model that was pointed out by Irons in 1972. But the basic differences between the two are also identified. For 8-node solid elements the assumed stress terms obtained through a rational procedure also agree with those deduced by Irons purely from his physical insight.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220112
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  • 56
    Digitale Medien
    Digitale Medien
    A study of the efficiency of iterative methods for linear problems in structural mechanics (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 209-218 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The efficiency of iterative methods in linear structural mechanics is studied. The efficiency concerns the calculation time, the numerical accuracy and the core storage needed. We state that iterative methods are effective in connection with hierarchical improvement of a primary approximation. Three iterative methods are studied: the conjugate gradient method preconditioned by a modified incomplete factorization matrix, the same method preconditioned by a matrix obtained from natural factors on elemental level, and a Jacobi integration preconditioned by viscous relaxation split in an element-by-element way. We make comparisons with direct methods, Gaussian elimination and factorization by use of natural factors.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220115
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  • 57
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    Digitale Medien
    Optimization in computer aided design, Ed. J. S. Gero, (Proceedings of I.F.I.P. Conference, Lyon, 1983), North Holland, Elsevier Science Publishers, 1985 (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 169-169 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230113
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  • 58
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    Digitale Medien
    Conference diary (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 170-171 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230115
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  • 59
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    Digitale Medien
    Differentiating matrices for arbitrarily spaced grid points (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 209-218 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Differentiating matrices allow the numerical differentiation of functions defined at points of a discrete grid. Previous derivations of these matrices have been restricted to grids with uniformly spaced points, and the resulting derivative approximations have lacked precision, especially at endpoints. The present work derives differentiating matrices on grids with arbitrarily spaced points. It is shown that high accuracy can be achieved through use of differentiating matrices on non-uniform grids through the expedient of including ‘near- boundary’ points. Use of the differentiating matrix as an operator in the solution of problems involving ordinary differential equations is also considered.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230205
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  • 60
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    Digitale Medien
    Conference diary (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 350-351 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230216
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  • 61
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    Digitale Medien
    A total Lagrangian formulation for the geometrically nonlinear analysis of structures using finite elements. Part II: Arches, frames and axisymmetric shells (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 253-274 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230209
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  • 62
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    Digitale Medien
    Structural optimization: A new dual method using mixed variables (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 409-428 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A new and powerful mathematical programming method is described, which is capable of solving a broad class of structural optimization problems. The method employs mixed direct/reciprocal design variables in order to get conservative, first-order approximations to the objective function and to the constraints. By this approach the primary optimization problem is replaced with a sequence of explicit subproblems. Each subproblem being convex and separable, it can be efficiently solved by using a dual formulation. An attractive feature of the new method lies in its inherent tendency to generate a sequence of steadily improving feasible designs. Examples of application to real-life aerospace structures are offered to demonstrate the power and generality of the approach presented.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230307
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  • 63
    Digitale Medien
    Digitale Medien
    Conference diary (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 523-524 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230314
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  • 64
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    Digitale Medien
    Masthead (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230401
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  • 65
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    Digitale Medien
    Nozzle design using an iterative Dirichlet approach (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 481-494 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220213
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  • 66
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    Digitale Medien
    Preface (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. i 
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    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220302
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  • 67
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    Digitale Medien
    Hydrostatic loading and stability analysis of structures with large displacements (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 575-595 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A method for the computation of hydrostatic forces on cable, truss, beam, plate and shell type structures is presented. A general large displacement formulation is assumed which allows for displacements and rotations of unlimited size. Equilibrating forces for nodal points as well as incremental force-displacement relationships are given. Various ways of making the geometric load matrix symmetric for incremental analysis is discussed. Alternative strategies for the incremental-iterative solution is also treated. A method for the determination of the hydrostatic stability of floating structures is suggested. Metacentres and centres of buoyancy for rotations about principal axes in the water plane are automatically computed. The paper presents three examples of applications: a pipe which is partially submerged, a full overturning of a floating space frame and, finally, a hydrostatic stability analysis of a ship.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220306
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  • 68
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    Digitale Medien
    A new triangular discrete Kirchhoff plate/shell element (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 453-470 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: We present a new 6-node triangular bending element (called DKTP) based on a discrete Kirchhoff model. A corresponding new flat-shell element, DLTP, having quadratic variation of in-plane displacement is also presented. This element has 6 degrees-of-freedom (u, v, w, θx, θy, θz) at each corner node and 3 degrees-of-freedom (u, v, w) at each mid-side node. Detailed numerical experimentation is presented to demonstrate the efficiency and reliability of these elements.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230310
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  • 69
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    Digitale Medien
    Finite layer analysis of layered elastic materials using a flexibility approach. Part 2 - Circular and rectangular loadings (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 959-978 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The finite layer techniques introduced in Part 1 of this paper are extended to allow the analysis of circular or general loadings applied to horizontally layered anisotropic materials. The analysis is considerably simplified through the use of Hankel transforms (circular loadings) and double Fourier transformations (general loadings).Once again an exact flexibility matrix is found for each finite layer, and it is shown that this flexibility matrix has precisely the same form whether the loading is a strip, circular or general loading. The flexibility matrix has the advantage of not becoming singular for incompressible materials as is the case for the stiffness matrices used in a conventional finite strip analysis.Examples are given of the behaviour of circular and general (rectangular) loadings applied to multilayered anisotropic materials. It is also shown by means of an example, that the method is extremely useful for analysis of problems involving incompressible materials.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230515
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  • 70
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    Digitale Medien
    Advanced boundary element analysis of two- and three-dimensional problems of elasto-plasticity (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 985-1002 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An advanced formulation of the boundary element method has been developed for inelastic analysis based on an initial stress approach. The iterative solution algorithm makes use of an accelerated initial stress approach in which the past history of initial stresses are used to obtain an initial estimate for the current increment. In the present analysis the geometry and functions are represented by higher order (quadratic) shape functions to model complex geometries and rapid functional variations accurately. The methods of numerical integration of the kernels, particularly the singular type, are substantially improved by devising suitable automatic sub-segmentation routines that incorporate the recent developments in mapping procedures. The formulations have been implemented for two-dimensional plane stress, plane strain and three-dimensional elasto-plasticity problems.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230602
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  • 71
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    Digitale Medien
    Hybrid finite difference/finite element solution method development for non-linear superconducting magnet and electrical circuit breakdown transient analysis (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1003-1022 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The problem of non-linear superconducting magnet and electrical protection circuit system transients is formulated. To enable studying the effects of coil normalization transients, coil distortion (due to imbalanced magnetic forces), internal coil arcs and shorts, and other normal and off-normal circuit element responses, the following capabilities are included: temporal, voltage and current-dependent voltage sources, current sources, resistors, capacitors and inductors. The concept of self-mutual inductance, and the form of the associated inductance matrix, is discussed for internally shorted coils. This is a Kirchhoff's voltage loop law and Kirchhoff's current node law formulation. The non-linear integrodifferential equation set is solved via a unique hybrid finite difference/integral finite element technique.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230603
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  • 72
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    Digitale Medien
    Incomplete factorization for finite element methods (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1101-1109 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An incomplete factorization iterative scheme with ORTHOMIN acceleration is evaluated for three-dimensional finite element applications. Both heat conduction and combined heat and fluid flow are investigated. Computational efficiency is investigated for both linear (8 node) and quadratic (27 node) elements as well as for various degrees of LU Decomposition. The factorization schemes worked well with both types of elements, and a variable factorization scheme, which distributes the level of factorization, performed well on difficult heat and fluid flow problems.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230608
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  • 73
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    Digitale Medien
    Boundary value techniques for finite element solutions of the diffusion-convection equation (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1145-1159 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: In this paper, the formulation of six-point and nine-point finite element equations for the solution of the diffusion-convection equation is presented. The six-point equation requires the solution of a tridiagonal system of equations and the nine-point centred equation is treated as a solution of a boundary value problem which leads to a large linear system of equations.Some numerical experiments are presented and the comparison with existing methods is included.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230611
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  • 74
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    Digitale Medien
    Developments in boundary element methods 3, P. K. Banerjee and S. Mukherjee (eds), Elsevier Applied Science Publishers, London and New York, 1984. No. of pages: 313 (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1195-1196 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230614
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  • 75
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    Digitale Medien
    A field-consistent two-noded curved axisymmetric shell element (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1245-1261 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The efficiency of a field-consistent two-noded linear curved axisymmetric shear-flexible shell element is shown to be due to the removal of both shear and membrane locking. Typical applications illustrate how the field-consistent representation dramatically improves performance, and allows greater flexibility in tailoring element design to satisfy specific problem needs.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230705
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  • 76
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    Digitale Medien
    Dynamic optimization of framed structures with variable layout (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1273-1294 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The paper presents a solution to the problem of dynamic optimization of framed structures for which the design variables are not only the sizes of the members but also the positions of the joints. The optimal design obtained is the least weight design which satisfies a specific frequency requirement plus upper and lower bounds on the design variables. The design algorithm is an iterative solution of the Kuhn-Tucker optimality criterion. The procedure is to modify an initial design to first obtain the desired fundamental frequency and then, while this frequency is held constant, to minimize the weight.The most important features of the algorithm are (a) a small number of design iterations is needed to reach an optimal or near-optimal design, (b) structural elements with a wide variety of size-stiffness may be used.The design procedure is illustrated with some numerical examples. The results show that the method is rapidly convergent and the optimized configurations are determined in a small number of redesign cycles. The procedure has been completely automated in a computer program on the HP 45 desk-top computer.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230707
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  • 77
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    Digitale Medien
    Reduction method for the non-linear analysis of symmetric anisotropic panels (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1329-1341 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Reduction method and computational procedures are presented for reducing the size of the analysis model and the number of degrees of freedom used in predicting the non-linear response of symmetric anisotropic panels. The two key elements of the method are (a) operator splitting, or decomposition of the characteristic arrays of the finite element model into sums of orthotropic and non-orthotropic contributions, (b) application of a reduction method through the successive use of the finite element method and the classical Rayleigh-Ritz technique. The finite element method is first used to generate a small number of global approximation vectors (or modes). Then the amplitudes of these modes are computed by using the classical Rayleigh-Ritz technique.The global approximation vectors are selected to be those commonly used in single (or multiple) parameter perturbation techniques, namely a non-linear solution corresponding to zero non-orthotropic arrays and a number of its derivatives with respect to an anisotropic tracing parameter (and possibly, to a load or arc-length parameter in the solution space). The size of the analysis model used in generating the global approximation vectors is identical to that of the corresponding orthotropic structure.The effectiveness of the proposed reduction method is demonstrated by means of a numerical example, and its potential for solving quasi-symmetric non-linear problems of anisotropic panels is discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230710
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  • 78
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    Digitale Medien
    Spatial discretization of hyperbolic equations with periodic solutions (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1395-1406 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: We investigate the Cauchy problem for hyperbolic equations for which the frequencies of the main Fourier components in the solution are located in a given frequency interval. Difference formulae for the spatial derivatives are constructed that are tuned to the given intervals of frequencies. Numerical examples illustrating these special discretizations are given both for linear and non-linear problems.
    Zusätzliches Material: 10 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230802
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  • 79
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    Digitale Medien
    Numerical solution of constrained non-linear algebraic equations (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1455-1481 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The numerical solution of n non-linear algebraic equations with n unknowns, when any or all of the variables are subjected to constraints, is discussed. Distinction is made between physical and absolute constraints. It is shown, using a set of test problems, that solution of constrained equations does require a special approach. It is found that the step length restricted Newton's method performs best for problems with absolute constraints. Physical constraints can be best handled using a continuation method or penalty functions.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230805
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  • 80
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    Digitale Medien
    A restricted hybrid stress formulation based on a direct finite element method (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1495-1508 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A direct method, which uses stress and displacement modes obtained from the governing equations of a problem, is adopted for finite element formulation. It is shown that this method actually leads to a restricted hybrid stress formulation if the displacement modes are changed to ensure symmetry of the stiffness matrix. Through this direct method, however, the problem of selecting the appropriate number of stress modes in the regular hybrid stress model is bypassed. Only the minimum number of modes that are compatible with the number of nodal degrees-of-freedom of an element is needed in the formulation. Using more modes only leads to a combination of stress modes, and will not improve the order of performance of the element. It is shown through numerical examples that the restricted hybrid stress formulation leads to well-balanced elements.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230807
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  • 81
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    Digitale Medien
    Dynamic response of rigid strip-foundations by a time-domain boundary element method (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1547-1565 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The dynamic response of rigid strip-foundations placed on or embedded in a homogeneous, isotropic, linear elastic half-space under conditions of plane strain to either external forces or obliquely incident seismic waves of arbitrary time variation is numerically obtained. The above mixed boundary-value problems are treated by the time domain boundary element method which is used in a step-by-step timewise fashion to provide the foundation response to a rectangular impulse. Numerical examples are presented in detail to demonstrate the use and importance of the proposed method. The method appears to be more advantageous than frequency domain techniques, because it provides the transient foundation response in a natural and direct way and can form the basis for extension to the non-linear case.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230810
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  • 82
    Digitale Medien
    Digitale Medien
    Announcements (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1582-1582 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230814
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  • 83
    Digitale Medien
    Digitale Medien
    A new efficient approach to the formulation of mixed finite element models for structural analysis (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1629-1641 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A new mixed finite element formulation is developed based on the Hellinger-Reissner principle with independent strain. By dividing the assumed strain into its lower order and higher order parts, the new formulation can be made much more efficient than the conventional mixed formulation. In addition the present new approach provides an alternative way of introducing a stabilization matrix to suppress undesirable kinematic modes.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230905
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  • 84
    Digitale Medien
    Digitale Medien
    Minimum weight design of cylindrical water tanks (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1679-1691 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The paper deals with the minimum weight design of cylindrical water tanks. The design is to conform to BS5337. The design procedure used is a combination of the finite element analysis of structures and a numerical method of optimization. In the design, the internal radius and the height of the tank are fixed and the variation of wall thickness is treated as the unknown of the design. Only piecewise linear variations of thickness are considered. Results of some examples are presented and discussed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230908
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  • 85
    Digitale Medien
    Digitale Medien
    Finite element method for non-linear forced vibrations of circular plates (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1715-1726 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Geometric non-linearities for large amplitude free and forced vibrations of circular plates are investigated. In-plane displacement and in-plane inertia are included in the formulation. The finite element method is used. An harmonic force matrix for non-linear forced vibration analysis is introduced and derived. Various out-of-plane and in-plane boundary conditions are considered. The relations of amplitude and frequency ratio for different boundary conditions and various load conditions are presented.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620230911
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  • 86
    Digitale Medien
    Digitale Medien
    Conforming versus non-conforming boundary elements in three-dimensional elastostatics (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1885-1904 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: In this work, we present a critical comparison of two basic ways of implementing the boundary element method in three-dimensional elastostatics. The first way is by using non-conforming elements, i.e. elements which have the collocation nodes removed from their perimeter. The number of nodes used for the collocation of the boundary tractions and displacements need not coincide with the number of nodes placed along the perimeter of the element for the purpose of describing the geometry. The second way is by placing the collocation nodes along the perimeter of the element, usually in coincidence with the geometry nodes. Thus, interelement continuity of the displacements is obtained. The basic reasons for the use of non-conforming elements in the boundary element method are twofold. First, simplification in the assembly and solution of the system equations and, secondly, easy computation of the ‘free’ and Cauchy principal value terms appearing in the integral equations. The state of the art in the boundary element method, however, has advanced in the last decade to the point where both of the aforementioned reasons are no longer problematic. As will be shown in what follows, conforming elements are able to produce more accurate results than non-conforming ones with substantial economy in the final size of the system equations.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620231008
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  • 87
    Digitale Medien
    Digitale Medien
    Derivation of Lagrangian and Hermitian shape functions for quadrilateral elements (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1939-1958 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper introduces a general theory for the derivation of the shape functions for the quadrilateral family of finite elements. The first section deals with the Lagrangian shape functions for the cases of uniform and boundary-described elements. Two basic procedures are introduced; the first by linear combinations of side-interpolations and the second by superposition. The remainder of the paper introduces a theory for the general uniform Hermitian element of any order. Details for quadrilateral elements, with first order derivatives are explained. All of the shape functions presented here were derived in the interval [0,1].The shape functions, developed by such an engineering approach, have been used successfully in the ABSEA Finite Element System of Cranfield Institute of Technology.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620231011
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  • 88
    Digitale Medien
    Digitale Medien
    Announcements (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 1971-1972 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620231014
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  • 89
    Digitale Medien
    Digitale Medien
    Masthead (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620231201
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  • 90
    Digitale Medien
    Digitale Medien
    Announcement (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. I 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620231202
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  • 91
    Digitale Medien
    Digitale Medien
    Masthead (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220101
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  • 92
    Digitale Medien
    Digitale Medien
    The patch test for elements (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 63-71 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The main purpose of this paper is to emphasize the necessity of convergence tests in general and the patch test in particular. Following a brief introduction, the patch test is described with examples. This, it is hoped, will help to remove any lingering misunderstanding of this very useful convergence test. Some positive contributions of the test in the formulation and improvement of elements are also discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220106
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  • 93
    Digitale Medien
    Digitale Medien
    An assessment of the semiloof shell element (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 133-151 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The semiloof shell element is the final product of years of research by Professor Irons and his colleagues, during which period the three-dimensional quadratic displacement isoparametric elements were successively modified into Ahmad thick shells, then eventually, using discrete Kirchhoff hypotheses, into the thin semiloof shells. The retention of curved sides and midside nodes retains the familiar appearance of the two- and three-dimensional isoparametric families, which enables ease of use with existing pre- and post-processing facilities. The element has been widely adapted and used frequently for elastic analyses of wide-ranging structures. It has also been developed for nonlinear geometric and material behaviour. However, despite the unparalleled generality in performance of this element, some unresolved problem areas still exist, particularly with use of reduced integrating rules. Such problems are highlighted in the paper and rectified where possible. A variety of problems are described to illustrate the above points and other interesting features, such as the treatment of thermal loading, and to emphasize the importance of this contribution to finite element technology by Professor Irons.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220110
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  • 94
    Digitale Medien
    Digitale Medien
    Bruce Irons: A non-conforming engineering scientist to be remembered and rediscovered (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 1-10 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220102
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  • 95
    Digitale Medien
    Digitale Medien
    Implicit modelling and mesh refinement for complex structures (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 17-38 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: When analysing complex structures it is rarely feasible to represent explicitly all the structural features which may contribute significantly to local or global structural performance. This paper presents a variety of methods for representing features which are below the economic analysis scale. Two approaches are described - referred to as implicit stiffness calculation and implicit mesh refinement. The former is essentially approximate and uses relatively simple formulae and computations. The latter involves quite extensive subsidiary calculation, but can lead to numerically exact simulation of fine mesh behaviour in so far as it affects neighbouring structure. Stiffness equivalence principles are stated and a number of computation schemes are presented and illustrated with simple two-dimensional examples.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220104
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  • 96
    Digitale Medien
    Digitale Medien
    A study of the influence of hierarchical nodes on the performance of selected parametric elements (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 153-171 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A number of programs have been developed and tested to enable the routine addition of elements with internal nodes into most finite element packages. A subsequent examination was carried out to assess the effect of those nodes on (a) the accuracy of the displacements and stresses using parametric elements with varying formulation complexities, and (b) the possible additional cost in processing, owing to adequacy of representation. It was found in general that, by including the internal nodes, the representation of both the displacement and the stress fields improved dramatically. It was also found that having hierarchical nodes could lead to a reduction in the processing cost.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220111
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  • 97
    Digitale Medien
    Digitale Medien
    Numerical control of the hourglass instability (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 219-228 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220116
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  • 98
    Digitale Medien
    Digitale Medien
    Modifications to the interpretation of the stresses and strains determined using constant strain triangular elements (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 249-266 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Zusätzliches Material: 28 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220119
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  • 99
    Digitale Medien
    Digitale Medien
    Improved strain interpolation for curved C° elements (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 281-288 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The strain energy of straight beam members derived from the isoparametric shape functions is known to be invariant with respect to the number of integration points as long as they exceed a minimum number. However, this invariant property is generally lost for curved members. For example, the two-point integrated, membrane strain energy of curved beams by employing the quadratic shape functions is different from the three-point integrated one. This paper presents an invariant strain interpolation scheme for quadratic curved beam elements, which can lead to improved membrane representations in curved shell elements, thus resolving the perplexing membrane-bending coupling difficulties in thin shell analysis.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220121
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  • 100
    Digitale Medien
    Digitale Medien
    Analytical tools for systematic transonic design (1986)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 22 (1986), S. 309-326 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Analytical flow models in the near sonic domain of compressible flow are discussed as a supplementary background to elliptic continuation and fictitious gas design methods, to extend shock-free design into choked flow design, shock-wave construction, with the aim of developing new analysis programs and of developing experience for three-dimensional configuration design.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620220203
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