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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 19 (1996), S. 0 
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— A series of low cycle fatigue experiments have been conducted on a 42CrMo steel under tension-torsion loading. Thin-walled tube specimens were used. Low cycle fatigue under various loading paths, including circular and square paths, have been investigated.The plastic work criterion for low cycle fatigue failure has previously been generally accepted, but it is difficult to calculate stress and strain for complex loading paths, especially for non-proportional loading. This present study suggests a simple method for the calculation of the stable cyclic stress and strain values based on a Modified Endochronic Constitutive Theory (MECT) that redefines an intrinsic time scale. The loading path effect under non-proportional loading is also considered when evaluating fatigue life.The results show that the plastic work approach using the MECT method in multiaxial fatigue calculations correlates reasonably well the data and is a reflection of loading path dependence.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-0407
    Keywords: Schlüsselwörter X-chromosomale bulbospinale Neuronopathie ; Kennedy-Syndrom ; Triplet-repeat-Erkrankung ; Androgenrezeptor ; Motoneuronerkrankung ; Key words X-chromosomal recessive bulbospinal neuronopathy ; Kennedy syndrome ; Triplet repeat disease ; Androgen receptor ; Motoneuron disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary X-chromosomal recessive bulbospinal neuronopathy (X-BNS, Kennedy's disease) is an important differential diagnosis of amyotrophic lateral sclerosis. We present the data of ten own patients along with a review of the literature on this uncommon disease which is caused by an expanded CAG-repeat in the androgen receptor gene. This mutation probably affects the transcription regulating activity of the androgen receptor in neurons. Signs and symptoms of X-BSN can be derived from partial insensitivity for androgens and a mixed, mainly motor neuronopathy. The clinical diagnosis is based on: 1. lower motor neuron weakness of bulbar and proximal limb muscles with onset in the third to fifth decade, 2. cramps and pronounced fasciculations, particularly of facial muscles, 3. postural tremor, 4. diminished or absent sensory action potentials inspite of only minor sensory impairment, 5. gynecomastia, and 6. infertility, diabetes mellitus and hyperlipoproteinemia in a minority of cases. Unlike amyotrophic lateral sclerosis, disease progression is slow with barely shortened life expectancy, which should be stressed in patient counselling. Causal treatment is as yet unavailable but several aspects of palliative medicine should be considered.
    Notes: Zusammenfassung Im vorliegenden Artikel wird die X-chromosomal rezessive bulbospinale Neuronopathie (X-BSN, Kennedy-Syndrom) anhand der Beschreibung 10 eigener Patienten und einer Übersicht über die bisherige Literatur vorgestellt. Die Symptome leiten sich von einer motorischen und sensiblen Neuronopathie und einer partiellen Androgeninsensitivität ab. Wegweisend für die Diagnose sind daher: 1. atrophische Paresen, meist ab der 3. bis 5. Dekade, bulbär und proximal betont an den Extremitäten, 2. Muskelkrämpfe und ausgeprägte Faszikulationen, v. a. im Gesicht, 3. Haltetremor der Hände, 4. deutliche Amplitudenreduktion der sensiblen Nervenaktionspotentiale bei nur diskreten klinischen sensiblen Defiziten, 5. Gynäkomastie, 6. gelegentlich Infertilität, Diabetes mellitus und Lipidstoffwechselstörungen. Im Gegensatz zur amyotrophen Lateralsklerose, der wichtigsten Differentialdiagnose, ist die Lebenserwartung aufgrund sehr langsamer Progredienz kaum eingeschränkt. Die Erkrankung beruht auf einer Expansion des CAG-Repeats im Androgenrezeptorgen. Pathogenetisch wird u. a. eine gestörte Funktion des Androgenrezeptors als Transkriptionsfaktor in Nervenzellen diskutiert. Es existieren noch keine kausaltherapeutische Ansätze, jedoch sind zahlreiche palliativmedizinischen Maßnahmen zu bedenken.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica Sinica 12 (1996), S. 368-376 
    ISSN: 1614-3116
    Keywords: nonproportional loading ; multiaxial loading ; ratchetting ; two-surface model ; cyclic hardening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A new superposed rule of Mroz's kinematic hardening rule and Ziegler's kinematic hardening rule based on two-surface model is proposed in the paper. Some experimental results on ratchetting of 2014-T6 aluminum alloy are predicted very well under multiaxial loading. In addition the conformability of the model is discussed for transient cyclic hardening under two kinds of nonproportional cyclic loading paths, i.e. square and rhombic path.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Amyotrophe Lateralsklerose ; Nichtinvasive Beatmung ; Chronische Hypoventilation ; Palliativtherapie ; Key words Amyotrophic lateral sclerosis ; Home mechanical ventilation ; Chronic hypoventilation ; Palliative therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Almost all patients with amyotrophic lateral sclerosis (ALS) experience symptoms of nocturnal hypoventilation during the course of the illness. These symptoms can develop years before death and may severely affect quality of life. Non-invasive intermittent home mechanical ventilation (HMV) via mask is a possible palliative measure for these symptoms, which is not often used in Germany. We report on our experience with HMV in 24 patients with ALS. Our data show a good palliative effect in 17 of 24 treated patients. Severe complications did not occur. The mean ventilation time at present is 14 months. Available options and their consequences need to be discussed in detail with patients and relatives before HMV is initiated.
    Notes: Zusammenfassung Fast alle Patienten mit amyotropher Lateralsklerose (ALS) leiden im Verlauf der Erkrankung an Symptomen der chronischen Hypoventilation. Diese Symptome können Jahre vor dem Tod auftreten und die Lebensqualität erheblich beeinträchtigen. Eine Möglichkeit zur Linderung dieser Beschwerden stellt die nichtinvasive, intermittierende Selbstbeatmung über Maske (ISB) dar. Allerdings findet diese Maßnahme in Deutschland noch wenig Anwendung. Wir berichten über erste Erfahrungen mit der ISB bei 24 Patienten mit ALS. Unsere Daten zeigen eine gute palliative Wirksamkeit der ISB bei 17 von 24 behandelten Patienten. Schwere Komplikationen wurden nicht beobachtet. Die mittlere Beatmungsdauer beträgt derzeit 14 Monate. Voraussetzung für die Einleitung einer ISB ist eine frühzeitige und ausführliche Diskussion möglicher Optionen und deren Konsequenzen mit Patienten und Angehörigen.
    Type of Medium: Electronic Resource
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