Magnetic properties of Al, V, Mn, and Ru impurities in Fe–Co alloys

Theoretical studies on the magnetic properties of impurities in Fe–Co alloys have been carried out using a molecular-orbital approach within a gradient corrected density functional formalism. The defected alloy is modeled by a large cluster and the calculations on the ordered alloy are used to show that a cluster containing 67 atoms can provide quantitative information on the local magnetic moment. It is found that although bulk Al, V, and Ru are nonmagnetic, all the impurities carry finite moments. While Al and V impurities couple antiferromagnetically, Ru impurities couple ferromagnetically to the host sites. It is shown that the observed composition dependence of the rate of increase of magnetic moment of FexCo1−x alloys upon addition of Mn impurities is due to the change in the magnetic moment of Mn impurities with composition. The reasons for this change and the possibility of stabilizing a higher Mn moment at all concentrations are discussed

Creep Analysis of a Variable Thickness Rotating FGM Disc using Tresca Criterion

The study investigates steady-state creep in a rotating Al-SiCp disc having different thickness profiles and reinforcement (SiCp) gradients. The disc material is assumed to creep according to threshold-stress based law and yield following Tresca criterion. The stresses and strain rates in the disc are estimated by solving the disc equilibrium equation along with creep constitutive equations. It was observed that on increasing the disc thickness gradient, the radial stress decreases towards the inner radius but increases towards the outer radius, whereas the tangential stress decreases over the entire radius. With the increase in SiCp gradient in the FGM disc, the radial stress increases significantly throughout, however, the tangential stress increases towards the inner radius but decreases towards the outer radius. The strain rates in the disc reduce significantly over the entire disc radius and become relatively uniform with the increase in either disc thickness gradient or reinforcement gradient. Thus, the composite disc having higher thickness and higher reinforcement gradients exhibits lesser distortion.Defence Science Journal, Vol. 65, No. 2, March 2015, pp.163-170, DOI:http://dx.doi.org/10.14429/dsj.65.804

The Impact of Observed Trauma on Parents in a PICU

© 2016 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies. Objective: To explore parents' experiences of observed trauma, defined as traumatic events, unrelated to their own child, that parents/carers witness while in a PICU. Design: Exploratory qualitative study. Setting: Nineteen-bed mixed surgical/medical PICU in a tertiary university-affiliated children's hospital. Participants: Parents of 11 children, screened from a total sample of 100 children admitted to the PICU for greater than 48 hours. Interventions: Face-to-face screening interviews were conducted with parents following their child's discharge from PICU. Parents who reported observed trauma were interviewed a second time to explore their experiences. Measurements and Main Results: Two questionnaires were designed, one to screen for observed trauma and a second one to guide semistructured interviews. Of 100 parents who participated in a structured screening interview, 19% reported observed trauma. Of the 19 parents, 11 completed the second interview. Significant themes included: involuntary exposure; privacy and confidentiality; empathy for children and their families; reflection and personal growth; and staff communication. Conclusions: Observed trauma is not uncommon in the PICU. The results suggest that timely support may alleviate the short-term negative impact. Furthermore, some parents have reported positive aspects to their experience

Optimization of fins fitted phase change material equipped solar photovoltaic under various working circumstances

This is the final version. Available on open access from Elsevier via the DOI in this recordData availability: in support of open access research, all underlying article materials (such as data, samples or models) can be accessed upon request via email to the corresponding author.The present work aims at the optimization of fins fitted phase change material equipped photovoltaic system under different working circumstances for proper power enhancement. Setup has been modelled and the best deepness of fins fitted phase change material enclosure has been computed for a range of daily collective solar flux at photovoltaic panel surface, wind pace, wind azimuth, surroundings temperature, melting point, successive fins distance, fins deepness and fins width in order to analyse the influence of working circumstances. It is shown that the change in wind pace from 0.2 m/s to 6 m/s results in reduction of best deepness of phase change material enclosure from 5.2 cm to 3.7 cm, 5.6 cm to 4.0 cm, 5.8 cm to 4.2 cm, 5.9 cm to 4.3 cm and 5.9 cm to 4.3 cm for successive fins distance of 1 m, 1/2 m, 1/3 m, 1/4 m and 1/5 m respectively for daily collective solar flux at photovoltaic panel as 5000Wh/m2. The change in wind azimuth from 0° to 75° results in increment in the best deepness of enclosure from 3.9 cm to 4.8 cm, 4.3 cm to 5.2 cm, 4.5 cm to 5.4 cm, 4.6 cm to 5.5 cm and 4.6 cm to 5.5 cm for respective fins distances. The power production is increased from 125 W/m2 to 137 W/m2, 140 W/m2, 142 W/m2, 143 W/m2 and 143 W/m2 with fins width of 0 mm, 0.5 mm, 1 mm, 2 mm and 4 mm respectively.Engineering and Physical Sciences Research Council (EPSRC

The structure of black hole magnetospheres. I. Schwarzschild black holes

We introduce a multipolar scheme for describing the structure of stationary, axisymmetric, force-free black-hole magnetospheres in the ``3+1'' formalism. We focus here on Schwarzschild spacetime, giving a complete classification of the separable solutions of the stream equation. We show a transparent term-by-term analogy of our solutions with the familiar multipoles of flat-space electrodynamics. We discuss electrodynamic processes around disk-fed black holes in which our solutions find natural applications: (a) ``interior'' solutions in studies of the Blandford-Znajek process of extracting the hole's rotational energy, and of the formation of relativistic jets in active galactic nuclei and ``microquasars'', and, (b) ``exterior'' solutions in studies of accretion disk dynamos, disk-driven winds and jets. On the strength of existing numerical studies, we argue that the poloidal field structures found here are also expected to hold with good accuracy for rotating black holes, except for maximum possible rotation rates. We show that the closed-loop exterior solutions found here are not in contradiction with the Macdonald-Thorne theorem, since these solutions, which diverge logarithmically on the hole's horizon $\cal H$, apply only to those regions which exclude $\cal H$.Comment: 6 figures. Accepted for publication by MNRA

The collision of two slowly rotating, initially non boosted, black holes in the close limit

We study the collision of two slowly rotating, initially non boosted, black holes in the close limit. A ``punctures'' modification of the Bowen - York method is used to construct conformally flat initial data appropriate to the problem. We keep only the lowest nontrivial orders capable of giving rise to radiation of both gravitational energy and angular momentum. We show that even with these simplifications an extension to higher orders of the linear Regge-Wheeler-Zerilli black hole perturbation theory, is required to deal with the evolution equations of the leading contributing multipoles. This extension is derived, together with appropriate extensions of the Regge-Wheeler and Zerilli equations. The data is numerically evolved using these equations, to obtain the asymptotic gravitational wave forms and amplitudes. Expressions for the radiated gravitational energy and angular momentum are derived and used together with the results of the numerical evolution to provide quantitative expressions for the relative contribution of different terms, and their significance is analyzed.Comment: revtex, 18 pages, 2 figures. Misprints corrected. To be published in Phys. Rev.

Amplification of Fluctuations in Unstable Systems with Disorder

We study the early-stage kinetics of thermodynamically unstable systems with quenched disorder. We show analytically that the growth of initial fluctuations is amplified by the presence of disorder. This is confirmed by numerical simulations of morphological phase separation (MPS) in thin liquid films and spinodal decomposition (SD) in binary mixtures. We also discuss the experimental implications of our results.Comment: 15 pages, 4 figure

Theoretical calculations of magnetic order and anisotropy energies in molecular magnets

We present theoretical electronic structure calculations on the nature of electronic states and the magnetic coupling in the Mn12O12 free cluster and the Mn12O12(RCOO)16(H2O)4 molecular magnetic crystal. The calculations have been performed with the all-electron full-potential NRLMOL code. We find that the free Mn12O12cluster relaxes to an antiferromagneticcluster with no net moment. However, when coordinated by sixteen HCOO ligands and four H2O groups, as it is in the molecular crystal, we find that the ferrimagnetic ordering and geometrical and magnetic structure observed in the experiments is restored. Local Mn moments for the free and ligandated molecular magnets are presented and compared to experiment. We identify the occupied and unoccupied electronic states that are most responsible for the formation of the large anisotropy barrier and use a recently developed full-space and full-potential method for calculating the spin–orbit coupling interaction and anisotropy energies. Our calculated second-order anisotropy energy is in excellent agreement with experiment

A generalized Pancharatnam geometric phase formula for three level systems

We describe a generalisation of the well known Pancharatnam geometric phase formula for two level systems, to evolution of a three-level system along a geodesic triangle in state space. This is achieved by using a recently developed generalisation of the Poincare sphere method, to represent pure states of a three-level quantum system in a convenient geometrical manner. The construction depends on the properties of the group SU(3)\/ and its generators in the defining representation, and uses geometrical objects and operations in an eight dimensional real Euclidean space. Implications for an n-level system are also discussed.Comment: 12 pages, Revtex, one figure, epsf used for figure insertio

Imaging algorithm for COVID-19: A practical approach

© 2020 Elsevier Inc. The global pandemic of COVID-19 pneumonia caused by the novel coronavirus (SARS-CoV-2) has strained healthcare resources across the world with emerging challenges of mass testing, resource allocation and management. While reverse transcriptase-polymerase chain reaction (RT-PCR) test is the most commonly utilized test and considered the current gold standard for diagnosis, the role of chest imaging has been highlighted by several studies demonstrating high sensitivity of computed tomography (CT). Many have suggested using CT chest as a first-line screening tool for the diagnosis of COVID-19. However, with advancement of laboratory testing and challenges in obtaining a CT scan without significant risk to healthcare providers, the role of imaging in diagnosis has been questioned. Several imaging societies have released consensus statements and guidelines on utilizing imaging resources and optimal reporting. In this review, we highlight the current evidence on various modalities in thoracic imaging for the diagnosis of COVID-19 and describe an algorithm on how to use these resources in an optimal fashion in accordance with the guidelines and statements released by major imaging societies