Occultation of the radio source 2019+ 098 (3C411) by comet 1983e (Sugano-Saigusa-Fujikawa)

We planned and observed with Ooty Radio Telescope the occultation with Comet 1983e Sugano-Saigusa-Fujikawa of the extragalactic radio source 2019+098 = 3C411. The results are presented formally for the first time, along with a brief account of other cometary occultations and general background of planning, execution and interpretation of such observations which will be useful for other future observers. The occultation occurred at 07:52 IST on 12th June 1983. It amounted to 25% peak to peak fluctuation in the flux density of the radio source. The rough predicted occultation time was 07:24 IST. We interpret the results after refining the occultation time to allow for various effects

The spectra and energies of classical double radio lobes

We compare two temporal properties of classical double radio sources: i) radiative lifetimes of synchrotron-emitting particles and ii) dynamical source ages. We discuss how these can be quite discrepant from one another, rendering use of the traditional spectral ageing method inappropriate: we contend that spectral ages give meaningful estimates of dynamical ages only when these ages are << 10^7 years. In juxtaposing the fleeting radiative lifetimes with source ages which are significantly longer, a refinement of the paradigm for radio source evolution is required. The changing spectra along lobes are explained, not predominantly by synchrotron ageing but, by gentle gradients in a magnetic field mediated by a low-gamma matrix which illuminates an energy-distribution of particles, controlled largely by classical synchrotron loss in the high magnetic field of the hotspot. The energy in the particles is an order of magnitude higher than that inferred from the minimum-energy estimate, implying that the jet-power is of the same order as the accretion luminosity produced by the quasar central engine. This refined paradigm points to a resolution of the findings of Rudnick et al (1994) and Katz-Stone & Rudnick (1994) that both the Jaffe-Perola and Kardashev-Pacholczyk model spectra are invariably poor descriptions of the curved spectral shape of lobe emission, and indeed that for Cygnus A all regions of the lobes are characterised by a `universal spectrum'. [abridged]Comment: LaTeX, 4 figures. To appear in A

From Clock Synchronization to Dark Matter as a Relativistic Inertial Effect

Lecture at BOSS2011 on relativistic metrology, on clock synchronization, relativistic dynamics and non-inertial frames in Minkowski spacetime, on relativistic atomic physics, on ADM canonical tetrad gravity in asymptotically Minkowskian spacetimes, on the York canonical basis identifying the inertial (gauge) and tidal degrees of freedom of the gravitational field, on the Post-Minkowskian linearization in 3-orthogonal gauges, on the Post-Newtonian limit of matter Hamilton equations, on the possibility to interpret dark matter as a relativistic inertial effect connected with relativistic metrology (i.e. clock synchronization) in Einstein GR.Comment: 90 pages. Lecture at BOSS201

Theory of point defect energetics: A review

285-293The energetics of point defects provide the controlling factor in determining the atomistic mechanisms in a wide range of solid state processes. We present here a pedagogical overview of the development of the continuum, quasi-lattice and lattice theories for different classes of point defects and materials. Varied approaches were followed in the past in modelling the relevant perfect crystals for interatomic forces for nonionic solids and model potentials for ionic materials. The earliest continuum approaches are those of Eshelby and Jost for treating point defects as elastic and dielectric singularities. These were followed by semicontinuum Mott-Littleton techniques and the Kanzaki defect force techniques in application to charged and neutral defect species. However the importance of a correct assessment of the dielectric polarization and the anharmonicity of the forces in the evaluation of the enthalpies and volumes have been well documented. Numerical computations of the enthalpies are seen to be sensitive to the choice of potential parameters and polarization models to varying degrees. While the theoretical picture is relatively clear in the case of the simpler materials with a near-ideal pure disorder, materials with mixed type of point defect disorders call for a more challenging simulation of defect environments which among other things should take into account the strong inhomogeneities of defect fields. The paper gives an overview of the evolution covering the highlights of these developments.</span

Infrared spectroscopy of the benzylium-like (and tropylium-like) isomers formed in the -H dissociative ionization of methylated PAHs

Dataset for article "Infrared spectroscopy of the benzylium-like (and tropylium-like) isomers formed in the --H dissociative ionization of methylated PAHs". DOI: 10.1016/j.jms.2022.111620 - folder Experimental contains - folder Fig2_IRPDspectra containing - with IRPD spectra data of all three species (Fig. 2) - folder Fig3_Depletion containing - the saturation depletion measurements on six bands (Fig. 3) - folder FigS1_MassSpectra containing - the mass spectra of all three species in Trap ON/OFF modes (Fig. S1) - folder Theoretical contains - .log files for each considered species - e.g.: folder C11H9+ contains folders for the - NapC7+ - NapC7+Ne - NapCH2+ - NapCH2+Ne These contain all .log files needed to reproduce Figs. 4, 5, 6 of the main mansucript and Figs. S3, S4, S5, S6, S7, S8, S9 of the supplementary material - folder Fig7_EnergyProfile containing - all minima and transition states for the computed energy profile (doublet spin state surface) for the H loss from NapCH3+ leading to NapCH2+ and NapC7+ (Fig. 7) Copyright: Creative Commons Attribution 4.0 International Open Acces