Simulation of failure of air plasma sprayed thermal barrier coating due to interfacial and bulk cracks using surface-based cohesive interaction and extended finite element method

This article describes a method of predicting the failure of a thermal barrier coating system due to interfacial cracks and cracks within bulk coatings. The interfacial crack is modelled by applying cohesive interfaces where the thermally grown oxide is bonded to the ceramic thermal barrier coating. Initiation and propagation of arbitrary cracks within coatings are modelled using the extended finite element method. Two sets of parametric studies were carried out, concentrating on the effect of thickness of the oxide layer and that of initial cracks within the ceramic coating on the growth of coating cracks and the subsequent failures. These studies have shown that a thicker oxide layer creates higher tensile residual stresses during cooling from high temperature, leading to longer coating cracks. Initial cracks parallel to the oxide interface accelerate coating spallation, and simulation of this process is presented in this article. By contrast, segmented cracks prevent growth of parallel cracks which can lead to spallation

The contemporaneous tectonic events of the Indian Ocean and neighbouring areas

About 140 m. y. ago, the Indian Ocean opened and the Indian plate began drifting northward. With this event began the evolution of the tectonic and magmatic pattern of the present-day Indian Ocean and its related structures. This paper deals with the temporal-tectonic coherences during the evolution of the Indian Ocean itself, of the Indian plate, the Himalayas, the Iran fold belt and the entire Afro-Arabian rift system. The authors themselves have worked in some of these areas and have also used and interpreted the voluminous and valuable literature concerning this region. During the last 140 m. y., there have been various culminations of tectonic activity which affected contemporaneously the different areas or structures of the described region. 80 to 75 m. y. ago, corresponding with magnetic anomaly 32, there was a strong acceleration of the northward drifting Indian plate. At the same time, a culmination of ophiolitic eruptions (or an intensified sea floor spreading) occurred in the Tethys region, that is along the present-day Himalayas, Karakorum, Makran, Oman, Zagros Mountains and Taurides in southern Turkey. 70 to 53 m. y. ago, following the acceleration of the Indian plate, the Indian and the Arabian plates first made contact with Asia resulting in a strong folding in Iran and the first folding phase in parts of the Karakorum and Himalayas. It is significant that the two independently moving plates contacted Asia at the same time. Intensified movements of plates combined with subduction of the continental crust of Arabia and India under Asia along the Indus suture line and the Zagros crush zone also occurred about 36, 25 and 10 m. y. ago and later. These movements corresponded with important orogenetic phases in the Himalayas and the Iran fold belt. At the same time, within the Red Sea and the Gulf of Aden an intensified sea floor spreading was in progress. The graben rifting of the East African Rift system also corresponded in time with these movements. The initial taphrogenetic phase occurred in the Afar rift 23 to 25 m. y. ago and in the Gregory Rift 10 m. y. ago. Thus, different and independent structures around the Indian Ocean showed culminations of tectonic events at the same time. The described region is extensive enough to obtain, by comparison of the varying structures, a first synopsis of temporal-tectonic activities showing how the earth's crust is influenced by contemporaneous tectonic events. Mainly, the contemporaneity of the tectonic events suggests a common origin of these dissimilar structures. Doubtless, the movements have their roots in the mantle or even in parts of the earth's core. A preliminary comparison of the tectonic culminations in the described region with those in other parts of the earth show, in the sense of Stille (1924, 1940), approximately similar periods of tectonic culminations as, for example, east and west of the Atlantic Ocean. But, in regard to the ideas of the new global tectonics, it is too early to draw any conclusions from so distant and different structures and it would be premature to speak of a contemporaneity of the global tectonics

Repetitive spinal motor neuron discharges following single transcranial magnetic stimulation: relation to dexterity

Transcranial magnetic stimulation allows to study the properties of the human corticospinal tract non-invasively. After a single transcranial magnetic stimulus, spinal motor neurons (MNs) sometimes fire not just once, but repetitively. The biological significance of such repetitive MN discharges (repMNDs) is unknown. To study the relation of repMNDs to other measures of cortico-muscular excitability and to physiological measures of the skill for finely tuned precision movements, we used a previously described quadruple stimulation (QuadS) technique (Z'Graggen et al. 2005) to quantify the amount of repMNDs in abductor digiti minimi muscles (ADMs) on both sides of 20 right-handed healthy subjects. Skillfulness for finger precision movements of both hands was assessed using a finger tapping task. In 16 subjects, a follow-up examination was performed after training of either precision movements (n=8) or force (n=8) of the left ADM. The size of the QuadS response (amplitude and area ratios) was greater in the dominant right hand than in the left hand (QuadS amplitude ratio: 47.1±18.1 versus 37.7±22.0%, Wilcoxon test: P<0.05; QuadS area ratio: 49.7±16.2% versus 36.9±23.0%, Wilcoxon test: P<0.05), pointing to a greater amount of repMNDs. Moreover, the QuadS amplitude and area increased significantly after finger precision training, but not after force training. This increase of repMNDs correlated significantly with the increase in performance in the finger tapping task. Our results demonstrate that repMNDs are related to handedness and therefore probably reflect supraspinal excitability differences. The increase of repMNDs after skills training but not after force training supports the hypothesis of a supraspinal origin of repMND

Infection kinetics and host specificity of Methicillin-resistant Staphylococcus aureus (MRSA) in pigs

In this study, we investigated the colonisation kinetics and host specificity of three different clonal lines of MRSA (ST8, ST9 and ST398). MRSA prevalence on skin, nasal mucosa, conjunctiva, feacal shedding and distribution patterns of MRSA in internal organs in weaning piglets are studied

Occurrence of Livestock-Associated Methicillin-Resistant Staphylococcus aureus in Turkey and Broiler Barns and Contamination of Air and Soil Surfaces in Their Vicinity

The emission of microorganisms, especially resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), from poultry farms is of public interest, and its occurrence and relevance are controversially discussed. So far, there are limited data on this issue. In this study, we investigated the occurrence of livestock-associated (LA)-MRSA inside and outside previously tested MRSA-positive poultry barns in Germany. In total, five turkey and two broiler fattening farms were investigated four and three times, respectively. In a longitudinal study during one fattening period, samples were collected from animals, the animals' environment inside the barn, including the air, and the barns' surroundings, such as ambient air and boot swabs of ground surfaces at different distances from the barn. Moreover, a cross-sectional study was carried out once inside the barns on five turkey and four broiler farms during the last third of the fatting period. In the cross- sectional study, LA-MRSA was detected in the air of most barns (7 of 9, 77.8%), as well as in many samples originating from animals, with detections levels of 50 to 54% in broiler and 62 to 77% in turkey farms. In the longitudinal study, LA-MRSA was found in the ambient air outside two turkey barns and on the ground surface on the downwind side of many (44.4%) turkey and broiler farms. The same spa types of isolates were observed inside and outside the barns. Transmission of MRSA within poultry farms, as well as emission via the airborne route, seems to be possible

A clinical study of motor evoked potentials using a triple stimulation technique

Amplitudes of motor evoked potentials (MEPs) are usually much smaller than those of motor responses to maximal peripheral nerve stimulation, and show marked variation between normal subjects and from one stimulus to another. Consequently, amplitude measurements have low sensitivity to detect central motor conduction failures due to the broad range of normal values. Since these characteristics are mostly due to varying desynchronization of the descending action potentials, causing different degrees of phase cancellation, we applied the recently developed triple stimulation technique (TST) to study corticospinal conduction to 489 abductor digiti minimi muscles of 271 unselected patients referred for possible corticospinal dysfunction. The TST allows resynchronization of the MEP, and thereby a quantification of the proportion of motor units activated by the transcranial stimulus. TST results were compared with those of conventional MEPs. In 212 of 489 sides, abnormal TST responses suggested conduction failure of various degrees. By contrast, conventional MEPs detected conduction failures in only 77 of 489 sides. The TST was therefore 2.75 times more sensitive than conventional MEPs in disclosing corticospinal conduction failures. When the results of the TST and conventional MEPs were combined, 225 sides were abnormal: 145 sides showed central conduction failure, 13 sides central conduction slowing and 67 sides both conduction failure and slowing. It is concluded that the TST is a valuable addition to the study of MEPs, since it improves detection and gives quantitative information on central conduction failure, an abnormality which appears to be much more frequent than conduction slowing. This new technique will be useful in following the natural course and the benefit of treatments in disorders affecting central motor conductio

Primary cervical malignant teratoma with a rib metastasis in an adult: Five-year survival after surgery and chemotherapy: A case report with a review of the literature

We report a case of a man presenting with a cervical malignant teratoma and a chondrosarcomatous rib metastasis. He was alive and free of recurrence five years and 10 months (= 70 months) after resection of the primary mass, followed by chemotherapy and subsequent resection of the rib tumor. This is the 35th patient reported in the literature and the first description in which an ‘adjuvant' or primary chemotherapy was used. Previous patients with a cervical malignant teratoma, reported after lethal outcome, had survivals of one to 22 months (median nine months). In all patients with a preoperative clinical impression of an aggressive, differentiated or undifferentiated malignancy, the definite diagnosis of teratoma could only be made histologically. By analogy to germ cell tumors, the prognosis of malignant teratoma might be improved if complete excision is combined with new, adjuvant chemotherapy protocols for germ cell tumors. Lessons learned from this case are placed in the context of germ cell tumors in general and of non-gonadal malignant teratomas in particula