Dynamics of hard-sphere suspension using Dynamic Light Scattering and X-Ray Photon Correlation Spectroscopy: dynamics and scaling of the Intermediate Scattering Function

Intermediate Scattering Functions (ISF's) are measured for colloidal hard sphere systems using both Dynamic Light Scattering (DLS) and X-ray Photon Correlation Spectroscopy (XPCS). We compare the techniques, and discuss the advantages and disadvantages of each. Both techniques agree in the overlapping range of scattering vectors. We investigate the scaling behaviour found by Segre and Pusey [1] but challenged by Lurio et al. [2]. We observe a scaling behaviour over several decades in time but not in the long time regime. Moreover, we do not observe long time diffusive regimes at scattering vectors away from the peak of the structure factor and so question the existence of a long time diffusion coefficients at these scattering vectors.Comment: 21 pages, 11 figure

Defying jet-gas alignment in two radio galaxies at z~2 with extended light profiles: Similarities to brightest cluster galaxies

We report the detection of extended warm ionized gas in two powerful high-redshift radio galaxies, NVSS J210626-314003 at z=2.10 and TXS 2353-003 at z=1.49, that does not appear to be associated with the radio jets. This is contrary to what would be expected from the alignment effect, a characteristic feature of distant, powerful radio galaxies at z> 0.6. The gas also has smaller velocity gradients and line widths than most other high-z radio galaxies with similar data. Both galaxies are part of a systematic study of 50 high-redshift radio galaxies with SINFONI, and are the only two that are characterized by the presence of high surface-brightness gas not associated with the jet axis and by the absence of such gas aligned with the jet. Both galaxies are spatially resolved with ISAAC broadband imaging covering the rest-frame R band, and have extended wings that cannot be attributed to line contamination. We argue that the gas and stellar properties of these galaxies are more akin to gas-rich brightest cluster galaxies in cool-core clusters than the general population of high-redshift radio galaxies at z>2. In support of this interpretation, one of our sources, TXS 2353-003, for which we have H\alpha\ narrowband imaging, is associated with an overdensity of candidate H\alpha\ emitters by a factor of 8 relative to the field at z=1.5. We discuss possible scenarios of the evolutionary state of these galaxies and the nature of their emission line gas within the context of cyclical AGN feedback.Comment: A&A in pres

TWO DIFFERENT TYPES OF PHOTOCHEMISTRY IN PHYCOERYTHROCYANIN α-SUBUNIT

The photochemical activities of phycoerythrocyanin α-subunits from Mastigocladus laminosus separated by isoelectric focusing were tested by irradiating at 500, 550, 577 and 600 nm. Two types of photoreversible photochromic responses have been characterized by absorption and absorption difference spectroscopy. Type I is the well-known absorption shift from 571 to 506 nm. Type II is a new response characterized by a line-broadening of the 570 nm absorption

Numerical Linked-Cluster Approach to Quantum Lattice Models

We present a novel algorithm that allows one to obtain temperature dependent properties of quantum lattice models in the thermodynamic limit from exact diagonalization of small clusters. Our Numerical Linked Cluster (NLC) approach provides a systematic framework to assess finite-size effects and is valid for any quantum lattice model. Unlike high temperature expansions (HTE), which have a finite radius of convergence in inverse temperature, these calculations are accurate at all temperatures provided the range of correlations is finite. We illustrate the power of our approach studying spin models on {\it kagom\'e}, triangular, and square lattices.Comment: 4 pages, 5 figures, published versio

Trustworthy Software : lessons from `goto fail' & Heartbleed bugs

In the first four months of 2014, two major vulnerabilities were announced affecting operation of the Transport Layer Security (TLS) protocol, which is used by applications to secure Internet communications. The `goto fail' bug affected Apple's iOS and OS X software and the `Heartbleed' bug affected versions of the OpenSSL software. Whilst the Apple bug was serious because it affected a wide range of Apple products, the Heartbleed bug was of greater significance due to widespread use of the OpenSSL library. This paper considers the lessons to be learned from these incidents. It examines how the use of the Trustworthy Software Framework (TSF) developed by the authors could have helped to reduce the risk of a major bugs like `goto fail' and Heartbleed. It also examines the responsibilities of developers where they use third party libraries and the need for appropriate due diligence. The paper also makes recommendations about how incidents like this should be handled to avoid confusing and contradictory messages being given

Modified Debye-Huckel Electron Shielding and Penetration Factor

Screened potential, modified by non standard electron cloud distributions responsible for the shielding effect on fusion of reacting nuclei in astrophysical plasmas, is derived. The case of clouds with depleted tails in space coordinates is discussed. The modified screened potential is obtained both from statistical mechanics arguments based on fluctuations of the inverse of the Debye-Huckel radius and from the solution of a Bernoulli equation used in generalized statistical mechanics. Plots and tables useful in evaluating penetration probability at any energy are provided.Comment: 9 pages, 3 figures, 3 table

A natural Finsler--Laplace operator

We give a new definition of a Laplace operator for Finsler metric as an average with regard to an angle measure of the second directional derivatives. This definition uses a dynamical approach due to Foulon that does not require the use of connections nor local coordinates. We show using 1-parameter families of Katok--Ziller metrics that this Finsler--Laplace operator admits explicit representations and computations of spectral data.Comment: 25 pages, v2: minor modifications, changed the introductio

Numerical Linked-Cluster Algorithms. I. Spin systems on square, triangular, and kagome lattices

We discuss recently introduced numerical linked-cluster (NLC) algorithms that allow one to obtain temperature-dependent properties of quantum lattice models, in the thermodynamic limit, from exact diagonalization of finite clusters. We present studies of thermodynamic observables for spin models on square, triangular, and kagome lattices. Results for several choices of clusters and extrapolations methods, that accelerate the convergence of NLC, are presented. We also include a comparison of NLC results with those obtained from exact analytical expressions (where available), high-temperature expansions (HTE), exact diagonalization (ED) of finite periodic systems, and quantum Monte Carlo simulations.For many models and properties NLC results are substantially more accurate than HTE and ED.Comment: 14 pages, 16 figures, as publishe