Automethylation of G9a and its implication in wider substrate specificity and HP1 binding.

Methylation of lysine residues on histones participates in transcriptional gene regulation. Lysine 9 methylation of histone H3 is a transcriptional repression signal, mediated by a family of SET domain containing AdoMet-dependent enzymes. G9a methyltransferase is a euchromatic histone H3 lysine 9 methyltransferase. Here, G9a is shown to methylate other cellular proteins, apart from histone H3, including automethylation of K239 residue. Automethylation of G9a did not impair or activate the enzymatic activity in vitro. The automethylation motif of G9a flanking target K239 (ARKT) has similarity with histone H3 lysine 9 regions (ARKS), and is identical to amino acids residues in EuHMT (ARKT) and mAM (ARKT). Under steady-state kinetic assay conditions, full-length G9a methylates peptides representing ARKS/T motif of H3, G9a, mAM and EuHMT efficiently. Automethylation of G9a at ARKT motif creates a binding site for HP1 class of protein and mutation of lysine in the motif impairs this binding. In COS-7 cells GFP fusion of the wild-type G9a co-localized with HP1alpha and HP1gamma isoforms whereas the G9a mutant with K239A displayed poor co-localization. Thus, apart from transcriptional repression and regulatory roles of lysine methylation, the non-histone protein methylation may create binding sites for cellular protein-protein interactions

Studying the Variation of the Fine Structure Constant Using Emission Line Multiplets

As an extension of the method by Bahcall et al. (2004) to investigate the time dependence of the fine structure constant, we describe an approach based on new observations of forbidden line multiplets from different ionic species. We obtain optical spectra of fine structure transitions in [Ne III], [Ne V], [O III], [OI], and [SII] multiplets from a sample of 14 Seyfert 1.5 galaxies in the low-z range 0.035 < z < 0.281. Each source and each multiplet is independently analyzed to ascertain possible errors. Averaging over our sample, we obtain a conservative value alpha^2(t)/\alpha^2(0) = 1.0030+-0.0014. However, our sample is limited in size and our fitting technique simplistic as we primarily intend to illustrate the scope and strengths of emission line studies of the time variation of the fine structure constant. The approach can be further extended and generalized to a "many-multiplet emission line method" analogous in principle to the corresponding method using absorption lines. With that aim, we note that the theoretical limits on emission line ratios of selected ions are precisely known, and provide well constrained selection criteria. We also discuss several other forbidden and allowed lines that may constitute the basis for a more rigorous study using high-resolution instruments on the next generation of 8 m class telescopes.Comment: 20 pages, 4 figures, sumbitted to A

Bianchi Type-II String Cosmological Models in Normal Gauge for Lyra's Manifold with Constant Deceleration Parameter

The present study deals with a spatially homogeneous and anisotropic Bianchi-II cosmological models representing massive strings in normal gauge for Lyra's manifold by applying the variation law for generalized Hubble's parameter that yields a constant value of deceleration parameter. The variation law for Hubble's parameter generates two types of solutions for the average scale factor, one is of power-law type and other is of the exponential form. Using these two forms, Einstein's modified field equations are solved separately that correspond to expanding singular and non-singular models of the universe respectively. The energy-momentum tensor for such string as formulated by Letelier (1983) is used to construct massive string cosmological models for which we assume that the expansion ($\theta$) in the model is proportional to the component $\sigma^{1}_{~1}$ of the shear tensor $\sigma^{j}_{i}$. This condition leads to $A = (BC)^{m}$, where A, B and C are the metric coefficients and m is proportionality constant. Our models are in accelerating phase which is consistent to the recent observations. It has been found that the displacement vector $\beta$ behaves like cosmological term $\Lambda$ in the normal gauge treatment and the solutions are consistent with recent observations of SNe Ia. It has been found that massive strings dominate in the decelerating universe whereas strings dominate in the accelerating universe. Some physical and geometric behaviour of these models are also discussed.Comment: 24 pages, 10 figure

Highly Excited Core Resonances in Photoionization of Fe XVII : Implications for Plasma Opacities

A comprehensive study of high-accuracy photoionization cross sections is carried out using the relativistic Breit-Pauli R-matrix (BPRM) method for (hnu + Fe XVII --> Fe XVIII + e). Owing to its importance in high-temperature plasmas the calculations cover a large energy range, particularly the myriad photoexciation-of-core (PEC) resonances including the n = 3 levels not heretofore considered. The calculations employ a close coupling wave function expansion of 60 levels of the core ion Fe XVIII ranging over a wide energy range of nearly 900 eV between the n = 2 and n = 3 levels. Strong coupling effects due to dipole transition arrays 2p^5 --> 2p^4 (3s,3d) manifest themselves as large PEC resonances throughout this range, and enhance the effective photoionization cross sections orders of magnitude above the background. Comparisons with the erstwhile Opacity Project (OP) and other previous calculations shows that the currently available cross sections considerably underestimate the bound-free cross sections. A level-identification scheme is used for spectroscopic designation of the 454 bound fine structure levels of Fe XVII. Level-specific photoionization cross sections are computed for all levels. In addition, partial cross sections for leaving the core ion Fe XVII in the ground state are also obtained. These results should be relevant to modeling of astrophysical and laboratory plasma sources requiring (i) photoionization rates, (ii) extensive non-local-thermodynamic-equilibrium models, (iii) total unified electron-ion recombination rates including radiative and dielectronic recombination, and (iv) plasma opacities. We particularly examine PEC and non-PEC resonance strengths and emphasize their expanded role to incorporate inner-shell excitations for improved opacities, as shown by the computed monochromatic opacity of Fe XVII.Comment: 12 pages, 5 figures, Physical Review A (in press

A study of electric motors for use in liquid and gaseous helium Engineering report no. 3530

Electric motor design and operation in liquid and gaseous helium environment

Gravitational field of domain wall in Lyra geometry

In this paper, we study the domain wall with time dependent displacement vectors based on Lyra geometry in normal gauge i.e. displacement vector $f^*_i = [ \beta (t), 0,0,0]$. The field theoretic energy momentum tensor is considered with zero pressure perpendicular to the wall. We find an exact solutions of Einstein equation for a scalar field $\phi$ with a potential $V(\phi)$ describing the gravitational field of a plane symmetric domain wall. We have seen that the hyper surfaces parallel to the wall ($z = constant$) are three dimensional de-sitter spaces. It is also shown that the gravitational field experienced by test particle is attractive.Comment: 11 pages, 6 figures; Submitted in Astrophysics and Space Science after minor revisio

Dynamic Resource Discovery and Management for Edge Computing Based on SPF for HADR Operations

The Smart City concept tries to inherit the advantages of Internet-of-Things (IoT) into its realm to function alongside the existing legacy systems. One of the most promising aspects of IoT is Edge Computing, which tries to move the computing, traditionally done via a centralized infrastructure like the cloud to the edge of the network. This allows remote deployment of IoT assets closer to the source and application area of information enabling faster response times of action. Smart Cities of future envision using Edge Computing to their advantage for remote and distributed computing. Sieve, Process and Forward (SPF) is an Edge Computing solution for dynamic IoT applications for Smart City scenarios. The military is looking forward to use, as well as develop the SPF platform for its Edge Computing requirements. But currently, the SPF platform does not have the mechanism for remote discovery of edge resources and their management to leverage its potential completely. This paper tries to propose a resource discovery and management architecture and methodology for SPF to support future Human Assistance and Disaster Recovery (HADR) operations in Smart City environments with the vision of enabling interoperability between civilian and military platforms

The impact of technology on the health care services in Gauteng Province, South Africa

Modern technology has enabled global integration with an immense opportunity for sharing knowledge. This paper examines the impact of modern medical technology on the Gauteng medical services. Gauteng is the smallest of the nine provinces in South Africa with the highest population. It produces 33.9% of the GDP of South Africa, equivalent to 10% of that of the entire African continent. Gauteng has the fourth largest economy in Africa after Algeria. Although numerous studies have identified the impact of technology on the medical fraternity, little data and analytical attention has been given to South Africa regarding modern technology, especially its impact on medical tourism. Patients from poor countries lacking modern technology travel to South Africa to benefit from technology that has improved diagnosis and made surgery quick, safe, efficient, and reduced the post-operative recovery to a few days. A multi-case approach was used in this study to explore the benefits of modern technology on the health care services. An in-depth analysis was conducted on two public and two private hospitals, selected because of their location in Gauteng and their bed capacity. A five point Likert questionnaire was administered to the hospital managers, nurses, doctors and medical technologists. In conclusion the paper emphasises the need for improved environmental friendliness by utilising paperless medical records and prescriptions, and recommends upgrading technological acuity of policy makers and healthcare Managers about the impact of Medical Technology in Disease management