The Interaction of He with a ½<111>{110} Edge Dislocation in W and Mo

The positions of the metal atoms around a ½<111>{110} edge dislocation in Mo and W are calculated using the Wilson—Johnson potentials. The boundary conditions are given by anisotropic elasticity theory. The He—metal potential, also developed by Wilson and Johnson, is used to calculate the position with maximum energy gain for a He-atom

Clustering of Helium Atoms at a ½<111>{110} Edge Dislocation in α—Iron

Atomistic calculations on a ½<111>{110} edge dislocation show a restricted tendency of clustering of helium atom along this dislocation. Clusters with up to 4 helium atoms have been studied. A cluster with 3 helium proved to be most stable

The genetic architecture of the human cerebral cortex

INTRODUCTION The cerebral cortex underlies our complex cognitive capabilities. Variations in human cortical surface area and thickness are associated with neurological, psychological, and behavioral traits and can be measured in vivo by magnetic resonance imaging (MRI). Studies in model organisms have identified genes that influence cortical structure, but little is known about common genetic variants that affect human cortical structure. RATIONALE To identify genetic variants associated with human cortical structure at both global and regional levels, we conducted a genome-wide association meta-analysis of brain MRI data from 51,665 individuals across 60 cohorts. We analyzed the surface area and average thickness of the whole cortex and 34 cortical regions with known functional specializations. RESULTS We identified 306 nominally genome-wide significant loci (P < 5 × 10−8) associated with cortical structure in a discovery sample of 33,992 participants of European ancestry. Of the 299 loci for which replication data were available, 241 loci influencing surface area and 14 influencing thickness remained significant after replication, with 199 loci passing multiple testing correction (P < 8.3 × 10−10; 187 influencing surface area and 12 influencing thickness). Common genetic variants explained 34% (SE = 3%) of the variation in total surface area and 26% (SE = 2%) in average thickness; surface area and thickness showed a negative genetic correlation (rG = −0.32, SE = 0.05, P = 6.5 × 10−12), which suggests that genetic influences have opposing effects on surface area and thickness. Bioinformatic analyses showed that total surface area is influenced by genetic variants that alter gene regulatory activity in neural progenitor cells during fetal development. By contrast, average thickness is influenced by active regulatory elements in adult brain samples, which may reflect processes that occur after mid-fetal development, such as myelination, branching, or pruning. When considered together, these results support the radial unit hypothesis that different developmental mechanisms promote surface area expansion and increases in thickness. To identify specific genetic influences on individual cortical regions, we controlled for global measures (total surface area or average thickness) in the regional analyses. After multiple testing correction, we identified 175 loci that influence regional surface area and 10 that influence regional thickness. Loci that affect regional surface area cluster near genes involved in the Wnt signaling pathway, which is known to influence areal identity. We observed significant positive genetic correlations and evidence of bidirectional causation of total surface area with both general cognitive functioning and educational attainment. We found additional positive genetic correlations between total surface area and Parkinson’s disease but did not find evidence of causation. Negative genetic correlations were evident between total surface area and insomnia, attention deficit hyperactivity disorder, depressive symptoms, major depressive disorder, and neuroticism. CONCLUSION This large-scale collaborative work enhances our understanding of the genetic architecture of the human cerebral cortex and its regional patterning. The highly polygenic architecture of the cortex suggests that distinct genes are involved in the development of specific cortical areas. Moreover, we find evidence that brain structure is a key phenotype along the causal pathway that leads from genetic variation to differences in general cognitive function

Comparison between measured and calculated stationary thermal neutron spectra in heterogeneous systems

Applied Science

Vacancy production in molybdenum by low energy light ion bombardment: Computer simulation

info:eu-repo/semantics/publishe

Clinical Presentation, Management, and Outcomes of Idiopathic Pain in Percutaneous Bone-anchored Hearing Implants

Item does not contain fulltextOBJECTIVE: To identify clinical features and investigate treatment outcomes of patients with idiopathic pain related to a percutaneous bone-anchored hearing implant (BAHI) and to propose management recommendations. STUDY DESIGN: Retrospective chart analysis. SETTING: Tertiary referral center. PATIENTS: The clinical data of 14 patients who were treated for idiopathic pain around their percutaneous BAHI between May 2007 and February 2018 at our tertiary referral center were reviewed. MAIN OUTCOME MEASURES: Pain after treatment and implant loss. RESULTS: All 14 patients received treatment with oral antibiotics. Nine patients received oral antibiotic combination therapy for 4 weeks, whereafter pain resolved in 4. Out of the five other patients, receiving either antibiotic monotherapy or shortened antibiotic combination therapy, pain resolved in two. In case of persistent pain (57.1%) after initial treatment, other pain management therapies were attempted, however all with only limited effect. Six patients (42.8%) underwent elective removal of the implant. In two patients spontaneous implant loss occurred. In two of the four patients who underwent reimplantation, pain relapsed. In one of these, pain resolved after the removal of the new implant. In the other patient, pain persisted, despite abutment removal. With exception of this latter patient, all other 13 patients were pain free at the latest follow-up. Cone beam computed tomography did not offer additional information regarding diagnosis or treatment. CONCLUSION: Idiopathic pain in BAHI is a rare but bothersome symptom which can result in implant removal. After oral antibiotic combination treatment, symptoms resolved in approximately 40% of patients. Therefore, we think conservative treatment with these antibiotics before implant removal surgery, is worth considering

Cascade Annealing of Tungsten Implanted with 5 keV Noble Gas Atoms: A Computer Simulation

The trapping of vacancies by implanted atoms is calculated. After low energy implantation (5 keV) of tungsten with heavy noble gas atoms most of the implanted atoms are in substitutional position with one or two vacancies closer than two lattice units. Under the influence of the lattice distortion around the implanted atoms the vacancies follow a preferential migration path towards the implant during annealing. With lattice relaxation simulations migration energies close to the implanted atom are calculated. Monte Carlo theory is applied to obtain trapping probabilities as a function of implant-vacancy separation and temperature. An estimate of the initial implant-vacancy separation follows from collision cascade calculations. The results show that nearby vacancies are trapped by the implanted atoms.

Binding of Helium to Metallic Impurities in Tungsten; Experiments and Computer Simulations

A W(100) single crystal was implanted with low doses Ag, Cu, Mn, Cr, Al or In. Subsequent heating to 1600 K removed all vacancies and left the implants in substitutional positions. Low energy He was injected, and binding of He to the substitutional impurities was observed. Binding energies were found as high as 1.25 eV for one He atom. Pair potential calculations were performed; the calculated binding energies correspond reasonably with the measured ones.