Microstructural and Corrosion Properties of Cold Rolled Laser Welded UNS S32750 Duplex Stainless Steel

The main goal of this work was to study the effect of plastic deformation on weldability of duplex stainless steel (DSS). It is well known that plastic deformation prior to thermal cycles can enhance secondary phase precipitation in DSS which can lead to significant change of the ferrite-austenite phase ratio. From this point of view one of the most important phase transformation in DSS is the eutectoid decomposition of ferrite. Duplex stainless steels (DSSs) are a category of stainless steels which are employed in all kinds of applications where high strength and excellent corrosion resistance are both required. This favorable combination of properties is provided by their biphasic microstructure, consisting of ferrite and austenite in approximately equal volume fractions. Nevertheless, these materials may suffer from several microstructural transformations if they undergo heat treatments, welding processes or thermal cycles. These transformations modify the balanced phase ratio, compromising the corrosion and mechanical properties of the material. In this paper, the microstructural stability as a consequence of heat history due to welding processes has been investigated for a super duplex stainless steel (SDSS) UNS S32750. During this work, the effects of laser beam welding on cold rolled UNS S32750 SDSS have been investigated. Samples have been cold rolled at different thickness reduction (\u3b5 = 9.6%, 21.1%, 29.6%, 39.4%, 49.5%, and 60.3%) and then welded using Nd:YAG laser. Optical and electronical microscopy, eddy\u2019s current tests, microhardness tests, and critical pitting temperature tests have been performed on the welded samples to analyze the microstructure, ferrite content, hardness, and corrosion resistance. Results show that laser welded joints had a strongly unbalanced microstructure, mostly consisting of ferritic phase (~60%). Ferrite content decreases with increasing distance from the middle of the joint. The heat-affected zone (HAZ) was almost undetectable and no defects or secondary phases have been observed. Both hardness and corrosion susceptibility of the joints increase. Plastic deformation had no effects on microstructure, hardness or corrosion resistance of the joints, but resulted in higher hardness of the base material. Cold rolling process instead, influences the corrosion resistance of the base material

Tremor in motor neuron disease may be central rather than peripheral in origin

BACKGROUND AND PURPOSE: Motor neuron disease (MND) refers to a spectrum of degenerative diseases affecting motor neurons. Recent clinical and post-mortem observations have revealed considerable variability in the phenotype. Rhythmic involuntary oscillations of the hands during action, resembling tremor, can occur in MND, but their pathophysiology has not yet been investigated. METHODS: A total of 120 consecutive patients with MND were screened for tremor. Twelve patients with action tremor and no other movement disorders were found. Ten took part in the study. Tremor was recorded bilaterally using surface electromyography (EMG) and triaxial accelerometer, with and without a variable weight load. Power spectra of rectified EMG and accelerometric signal were calculated. To investigate a possible cerebellar involvement, eyeblink classic conditioning was performed in five patients. RESULTS: Action tremor was present in about 10% of our population. All patients showed distal postural tremor of low amplitude and constant frequency, bilateral with a small degree of asymmetry. Two also showed simple kinetic tremor. A peak at the EMG and accelerometric recordings ranging from 4 to 12 Hz was found in all patients. Loading did not change peak frequency in either the electromyographic or accelerometric power spectra. Compared with healthy volunteers, patients had a smaller number of conditioned responses during eyeblink classic conditioning. CONCLUSIONS: Our data suggest that patients with MND can present with action tremor of a central origin, possibly due to a cerebellar dysfunction. This evidence supports the novel idea of MND as a multisystem neurodegenerative disease and that action tremor can be part of this condition

Lattice QCD with mixed actions

We discuss some of the implications of simulating QCD when the action used for the sea quarks is different from that used for the valence quarks. We present exploratory results for the hadron mass spectrum and pseudoscalar meson decay constants using improved staggered sea quarks and HYP-smeared overlap valence quarks. We propose a method for matching the valence quark mass to the sea quark mass and demonstrate it on UKQCD clover data in the simpler case where the sea and valence actions are the same.Comment: 15 pages, 10 figures some minor modification to text and figures. Accepted for publicatio

Deconstructing Fahr's disease/syndrome of brain calcification in the era of new genes

Introduction There are now a number genes, known to be associated with familial primary brain calcification (PFBC), causing the so called ‘Fahr's’ disease or syndrome. These are SCL20A2, PDGFB, PDGFRB and XPR1. In this systematic review, we analyse the clinical and radiological features reported in genetically confirmed cases with PFBC. We have additionally reviewed pseudohypoparathyroidism which is a close differential diagnosis of PFBC in clinical presentation and is also genetically determined. Methods We performed a Medline search, from 1st Jan 2012 through to 7th November 2016, for publications with confirmed mutations of SCL20A2, PDGFB, PDGFRB, and XPR1 and found twenty papers with 137 eligible cases. A second search was done for publications of cases with Pseudohypoparathyroidism or pseudopseudohypoparathyroidism, and found 18 publications with 20 eligible cases. Results SLC20A2 was the most common gene involved with 75 out of 137 cases included with PFBC (55%) followed by PDGFB (31%) and PDGFRB (11%). Statistically significant correlation was found between the presence of parkinsonism with SLC20A2 mutations, headache in PDGFB and generalised tonic-clonic seizures in patients with pseudohypoparathyroidism. Conclusion We combine statistical analysis and clinical inference to suggest a diagnostic algorithm based on the observations in this study to help with investigation of a patient with neurological features and brain calcification

A dynamic discrete dislocation plasticity method for the simulation of plastic relaxation under shock loading

In this article, it is demonstrated that current methods of modelling plasticity as the collective motion of discrete dislocations, such as two-dimensional discrete dislocation plasticity (DDP), are unsuitable for the simulation of very high strain rate processes (106 s-1 or more) such as plastic relaxation during shock loading. Current DDP models treat dislocations quasi-statically, ignoring the time-dependent nature of the elastic fields of dislocations. It is shown that this assumption introduces unphysical artefacts into the system when simulating plasticity resulting from shock loading. This deficiency can be overcome only by formulating a fully time-dependent elastodynamic description of the elastic fields of discrete dislocations. Building on the work of Markenscoff & Clifton, the fundamental time-dependent solutions for the injection and non-uniform motion of straight edge dislocations are presented. The numerical implementation of these solutions for a single moving dislocation and for two annihilating dislocations in an infinite plane are presented. The application of these solutions in a two-dimensional model of timedependent plasticity during shock loading is outlined here and will be presented in detail elsewhere. © 2013 The Author(s) Published by the Royal Society. All rights reserved

Calculations of time-dependent observables in non-Hermitian quantum mechanics: The problem and a possible solution

The solutions of the time independent Schrodinger equation for non-Hermitian (NH) Hamiltonians have been extensively studied and calculated in many different fields of physics by using L^2 methods that originally have been developed for the calculations of bound states. The existing non-Hermitian formalism breaks down when dealing with wavepackets(WP). An open question is how time dependent expectation values can be calculated when the Hamiltonian is NH ? Using the F-product formalism, which was recently proposed, [J. Phys. Chem., 107, 7181 (2003)] we calculate the time dependent expectation values of different observable quantities for a simple well known study test case model Hamiltonian. We carry out a comparison between these results with those obtained from conventional(i.e., Hermitian) quantum mechanics (QM) calculations. The remarkable agreement between these results emphasizes the fact that in the NH-QM, unlike standard QM, there is no need to split the entire space into two regions; i.e., the interaction region and its surrounding. Our results open a door for a type of WP propagation calculations within the NH-QM formalism that until now were impossible.Comment: 20 pages, 5 Postscript figures. To be Published in Physical Review

B-cell populations discriminate between pediatric- and adult-onset multiple sclerosis

Objective: To comparatively assess the B-cell composition in blood and CSF of patients with pediatric-onset multiple sclerosis (pedMS) and adult-onset multiple sclerosis (adMS). / Methods: In this cross-sectional study, we obtained blood and CSF samples from 25 patients with pedMS (8–18 years) and 40 patients with adMS (23–65 years) and blood specimens from 66 controls (1–55 years). By using multicolor flow cytometry, we identified naive, transitional, isotype class-switched memory, nonswitched memory, and double-negative memory B-cell subsets as well as plasmablasts (PB) and terminally differentiated plasma cells (PC). Flow cytometric data were compared to concentrations of B-cell-specific cytokines in serum and CSF as determined by ELISA. / Results: Frequencies of circulating naive B-cells decreased with higher age in controls but not in patients with multiple sclerosis (MS). B-cell patterns in CSF differed between pedMS and adMS with an acute relapse: in pedMS-derived CSF samples, high frequencies of nonswitched memory B cells and PB were present, whereas class-switched memory B cells and PC dominated in the CSF of patients with adMS. In pedMS, PB were also elevated in the periphery. Accumulation of PB in the CSF correlated with high intrathecal CXCL-13 levels and augmented intrathecal synthesis of immunoglobulin G and immunoglobulin M. / Conclusions: We demonstrate distinct changes in intrathecal B-cell homeostasis in patients with pedMS during active disease, which differ from those in adults by an expansion of plasmablasts in blood and CSF and similarly occur in prototypic autoantibody-driven autoimmune disorders. This emphasizes the particular importance of activated B-lymphocyte subsets for disease progression in the earliest clinical stages of MS

Educational recommendations for the conduct, content and format of EULAR musculoskeletal ultrasound Teaching the Teachers Courses

To produce educational guidelines for the conduct, content and format of theoretical and practical teaching at EULAR musculoskeletal ultrasound (MSUS) Teaching the Teachers (TTT) Courses

Entanglement transfer from dissociated molecules to photons

We introduce and study the concept of a reversible transfer of the quantum state of two internally-translationally entangled fragments, formed by molecular dissociation, to a photon pair. The transfer is based on intracavity stimulated Raman adiabatic passage and it requires a combination of processes whose principles are well established.Comment: 5 pages, 3 figure