Crystal Plasticity Simulations of Haynes 230, an Analysis of Single Crystal and Polycrystalline Experiments

none4siThe behavior of a Ni-based superalloy, Haynes 230, was investigated at macro and micro scale level by means of a Crystal Plasticity (CP) model implemented in an open source Finite Element code, Warp3D. Single Crystal and polycrystalline specimens have been experimentally characterized with Digital Image Correlation (DIC) to identify the local strain field evolution. The results of single crystal’s tensile tests were used to obtain an estimation of the constitutive model parameters. Then a polycrystalline model, reproducing a tensile test with loading/unloading steps, was created starting from the microstructural data obtained with EBSD (electron back-scatter diffraction), which allowed the identification of grains geometry and orientations. The polycrystalline simulations were used to verify the prediction of the CP model over the experiment. The results of this study show that the comparison between experiments and numerical analysis is in good agreement on both global and local scale levels.noneLuccarelli, Pietro Giovanni; Foletti, Stefano; Pataky, Garrett; Sehitoglu, HuseyinLuccarelli, PIETRO GIOVANNI; Foletti, Stefano; Pataky, Garrett; Sehitoglu, Huseyi

Recurrent nonconvulsive status epilepticus in a patient with coffin-lowry syndrome

Coffin-Lowry syndrome (CLS) is a rare neurodevelopmental condition caused by heterogeneous mutations in the RPS6KA3 gene on the X chromosome, leading to severe intellectual disability and dysmorphism in men, while women are carriers and only weakly affected. CLS is well known for stimulus-induced drop episodes; however, epilepsy is not commonly reported in this condition. We report on a CLS patient presenting with recurrent episodes of nonconvulsive status epilepticus (NCSE) with generalized epileptic activity, for which investigations did not find any other cause than the patient's genetic condition. This case underlines that the possibility of nonconvulsive epileptic seizures and status epilepticus should, therefore, be considered in those patients. The treatable diagnosis of NCSE may easily be overlooked, as symptoms can be unspecific

Near-tip closure and cyclic plasticity in Ni-based single crystals

Fatigue crack growth was investigated in a 001 oriented single crystal specimen, made of a Ni-based superalloy, Haynes 230. Crack propagation was characterized with digital image correlation: crack closure, measured by analyzing the relative displacements of crack flanks, showed closure levels much lower than polycrystal alloys. Reversed plastic zones were calculated from regressed stress intensity factor ranges and compared to the strain field measured at the crack tip. Experimental results were compared to those provided by a numerical model, which considered both crack propagation and single crystal anisotropic behavior, in terms of crack opening levels and crack tip cyclic plastic zones. Results of the numerical simulations were in good agreement with the experiments

Stimulation électrique intracrânienne dans le traitement de l’épilepsie

La stimulation électrique intracérébrale (ou Deep Brain Stimulation, DBS) a été initiée en 1912. Actuellement elle est évaluée comme une possibilité de traitement des épilepsies pharmaco-résistantes, non-opérables. Nous résumons les résultats de différentes études de la DBS appliquée à différentes structures cérébrales. En particulier, la stimulation du lobe temporal mésial apparaît prometteur. Dans notre centre Genève-Lausanne, ce traitement a été conduit chez des patients choisis et montre de bons résultats. D’autres études sont nécessaires pour optimiser les paramètres de stimulation pour chaque syndrome épileptique.Die intrakranielle Hirnstimulation (oder Deep Brain Stimulation, DBS) wurde schon 1912 beschrieben und wird heute als mögliche Therapie der pharmakoresistenten Epilepsien untersucht. Resultate von Studien zur intrakraniellen Hirnstimulation in den diversen Hirnstrukturen werden berichtet. Vor allem die Stimulation der mesialen Temporallappenstrukturen scheint gute Erfolge zu erzielen. In unserem Zentrum Genf-Lausanne ist die Therapie bei ausgesuchten Patienten mit gutem Erfolg durchgeführt worden. Weitere Studien sind notwendig zur Optimierung der Stimulusparameter und zur besseren Definition der Patientenpopulation.The electric intracerebral stimulation (or deep brain stimulation, DBS) has been described already in 1912. Nowadays DBS is evaluated as a possible treatment of non-operable pharmacologically intractable epilepsy. We summarize the results of the different DBS studies in various brain structures. In particular, stimulation of the mesial temporal lobe structures appears to be successful. In our Geneva-Lausanne centre, this treatment was carried out in selected patients, with good results. Further studies are needed in order to optimize the stimulus parameters and to better define the patient population

Possible new avenues in epilepsy treatement: the stimulation techniques. Deep brain stimulation, vagal nerve stimulation, transcranial magnetic stimulation

Stimulation techniques have been extensively explored as new treatments for epilepsy, and their efficacy is still being investigated, albeit several approaches appear to be very promising. Vagal nerve stimulation (VNS) has been a well established palliative therapy for almost 20 years, however, complete seizure control is rarely obtained. Its favourable effect on mood has been noted in several studies, and VNS was FDA-approved for the treatment of major depression in 2005. Intracerebral electrical stimulation is currently being evaluated as a potential treatment for patients with drug-resistant focal epilepsy in whom surgery cannot be offered. We summarise the results of various studies applying deep brain stimulation (DBS) to different brain structures, particularly to the mesial temporal lobe. From these studies, it appears that the efficiency of DBS to reduce epileptic seizures is demonstrated in a sufficiently large patient population but the exact determinants (physical parameters, syndromes) of its success (or its absence) remain unknown. Repetitive Transcranial Magnetic Stimulation (rTMS) has been investigated as an antiepileptic treatment in patients with focal seizure onset by several groups, however, the clinical success is variable and in most studies rather low

Dilated cardiomyopathy and impaired cardiac hypertrophic response to angiotensin II in mice lacking FGF-2

FGF-2 has been implicated in the cardiac response to hypertrophic stimuli. Angiotensin II (Ang II) contributes to maintain elevated blood pressure in hypertensive individuals and exerts direct trophic effects on cardiac cells. However, the role of FGF-2 in Ang II–induced cardiac hypertrophy has not been established. Therefore, mice deficient in FGF-2 expression were studied using a model of Ang II–dependent hypertension and cardiac hypertrophy. Echocardiographic measurements show the presence of dilated cardiomyopathy in normotensive mice lacking FGF-2. Moreover, hypertensive mice without FGF-2 developed no compensatory cardiac hypertrophy. In wild-type mice, hypertrophy was associated with a stimulation of the c-Jun N-terminal kinase, the extracellular signal regulated kinase, and the p38 kinase pathways. In contrast, mitogen-activated protein kinase (MAPK) activation was markedly attenuated in FGF-2–deficient mice. In vitro, FGF-2 of fibroblast origin was demonstrated to be essential in the paracrine stimulation of MAPK activation in cardiomyocytes. Indeed, fibroblasts lacking FGF-2 expression have a defective capacity for releasing growth factors to induce hypertrophic responses in cardiomyocytes. Therefore, these results identify the cardiac fibroblast population as a primary integrator of hypertrophic stimuli in the heart, and suggest that FGF-2 is a crucial mediator of cardiac hypertrophy via autocrine/paracrine actions on cardiac cells

Substitutability and Protectionism: Latin America's Trade Policy and Imports from China and India

This article examines the trade policy response of Latin American governments to the rapid growth of Chinese and Indian exports in world markets. To explain more protection in sectors where a large share of imports originates in China and India, the "protection for sale" model is extended to allow for region-specific degrees of substitutability between domestic and imported varieties of a good. The results suggest that more protection toward Chinese and Indian goods can be explained by the higher substitutability of Chinese and Indian goods with domestic varieties. The data support the model, which performs better than the original protection for sale framework in explaining Latin America's structure of protection. Copyright The Author 2010. Published by Oxford University Press on behalf of the International Bank for Reconstruction and Development / the world bank . All rights reserved. For permissions, please e-mail: [email protected]., Oxford University Press.