Article on Richard Wallis talk @ Ebooks 2013 conference, UCL. Richard Wallis (formerly Talis; now Tech. evangelist @ OCLC and consultant) – “Linked Data for Ebook Discovery”.

This article is a review of a conference presentation by Richard Wallis about “Linked Data” attended by Gopal Dutta in May 2013. Wallis is advocating a new method of cataloguing which he believes would better enable searching for ebooks. The article may be of interest to anyone who is curious about the intersection between Google, cataloguing and ebooks

Regularization of the spectral singularity in PT\mathcal{PT}-symmetric systems by all order nonlinearities: Nonreciprocity and optical isolation

Spectral singularities are ubiquitous with PT-symmetry leading to infinite transmission and reflection coefficients. Such infinities imply the divergence of the fields in the medium thereby breaking the very assumption of the linearity of the medium used to obtain such singularities. We identify saturable nonlinearity retaining contributions from all orders of the field to limit the infinite growth and regularize the spectral singularity. We present explicit numerical results to demonstrate regularization. The all order nonlinear PT-symmetric device is shown to exhibit very effective isolation or optical diode action, since transmission through such a system is nonreciprocal. In contrast, a linear system or a system with Kerr nonlinearity is known to have only reciprocal transmission. Further we demonstrate optical bistability for such a system with high contrast.Comment: 5 pages, 5 figure

Radiative proton capture cross sections in the mass range 40−5540-55

Proton capture cross sections in the energy range of astrophysical interest for mass region 40-54 have been calculated in the Hauser-Feshbach formalism with reaction code TALYS1.6. The density dependent M3Y effective nucleon-nucleon interaction folded with target radial matter densities from relativistic mean field approach is used to obtain the semi-microscopic optical potential. A definite normalization of potential-well depths has been used over the entire mass region. The $(p,\gamma)$ rates of some reactions, important in the astrophysical scenario, are calculated using the potential in the relevant mass region.Comment: 9 pages, 6 figures, accepted for publication in the journal Physical Review

Signature of strong atom-cavity interaction on critical coupling

We study a critically coupled cavity doped with resonant atoms with metamaterial slabs as mirrors. We show how resonant atom-cavity interaction can lead to a splitting of the critical coupling dip. The results are explained in terms of the frequency and lifetime splitting of the coupled system.Comment: 8 pages, 5 figure