Do the mildly superluminal VLBI knots exclude ultrarelativistic blazar jets?

We compute the effective values of apparent transverse velocity and flux boosting factors for the VLBI radio knots of blazar jets, by integrating over the angular distributions of these quantities across the widths of jets with finite opening angles but constant velocities. For high bulk Lorentz factors (Gamma > 10) variations across the jet can be quite large if the opening angle, omega, is even a few degrees on sub-parsec scales. The resulting apparent speeds are often much lower than those obtained from the usual analyses that ignore the finite jet opening angles. We can thus reconcile the usually observed subluminal or mildly superluminal speeds with the very high (>~ 20) Gamma factors, required by the inverse Compton origin and rapid variability of TeV fluxes, as well as by intraday radio variability. Thus it is possible to associate the VLBI radio knots directly with shocks in the ultra-relativistic main jet flow, without invoking very rapid jet deceleration on parsec scales, or extremely unlikely viewing angles.Comment: 10 pages, 1 figure, to appear in ApJ Letters, Nov. 10 2004 issu

Micro-Raman and Raman Imaging studies of glassy material produced by continuous wave (CW) CO2 laser irradiation of lime/pozzolan mortar

ICCC 2015, Beijing, China, 13~16 October 2015; http://iccc2015.csp.escience.cn/dct/page/1This work describes the distribution of the portlandite over the surface of the lime/pozzolan mortar and the mineral composition of the glassy material formed when the mortar was irradiated with continuous-wave-CO2 (CW-CO2) laser. Both Micro-Raman and Raman mapping have been used for structural studies. Lime/pozzolan/sand 1/1/2 mortars, 5 years at room temperature, were irradiated with CW-CO2 laser (Synrad Firestar t80, Mukilteo, WA) operating at a wavelength of 10.591 ¿m, 10P(20) CO2 laser line. Laser output: 8W, 18W and 38W (Synrad PW-250 (Mukilteo, WA)). The laser beam was focused by means of a NaCl lens of 10 cm focal length and the irradiation time was 5 seconds. Raman spectra were collected with a Raman Spectrometer (Renishaw Invia) equipped with a CCD camera, using 532 nm (Nd:YAG) excitation line. The laser on the sample was 5 mW and the integration time was 10 seconds. For mapping measurements, an area of 80 ¿m x 80 ¿m was chosen in the internal part of the glass. The step size was 5 ¿m with an individual grid size of 25 ¿m2. Glazing, vaporization and spalling process can produce over an irradiated surface with a high power laser beam. When the power density of the irradiating laser beam is high enough to raise the temperature beyond the glass transition, a glassy surface layer is formed. However, if surface temperatures are below that melting point, the vaporization of water can be produce over the material surface. Due to the small diffusivity of water vapour, its transport is hindered and an overpressure is attained. Hydraulic building materials have about 4-10% bounded water, after irradiation with the CW-CO2 laser, water vapour spread out in a vaporization front reacting with the CaO present in the sample and producing Ca(OH)2, besides a glassy surface.Peer Reviewe

Optical-NIR spectroscopy of the puzzling gamma-ray source 3FGL 1603.9-4903/PMN J1603-4904 with X-shooter

The Fermi/LAT instrument has detected about two thousands Extragalactic High Energy (E > 100 MeV) gamma-ray sources. One of the brightest is 3FGL 1603.9-4903, associated to the radio source PMN J1603-4904. Its nature is not yet clear, it could be either a very peculiar BL Lac or a CSO (Compact Symmetric Object) radio source, considered as the early stage of a radio galaxy. The latter, if confirmed, would be the first detection in gamma-rays for this class of objects. Recently a redshift z=0.18 +/- 0.01 has been claimed on the basis of the detection of a single X-ray line at 5.44 +/- 0.05 keV interpreted as a 6.4 keV (rest frame) fluorescent line. We aim to investigate the nature of 3FGL 1603.9-4903/PMN J1603-4904 using optical to NIR spectroscopy. We observed PMN J1603-4904 with the UV-NIR VLT/X-shooter spectrograph for two hours. We extracted spectra in the VIS and NIR range that we calibrated in flux and corrected for telluric absorption and we systematically searched for absorption and emission features. The source was detected starting from ~6300 Ang down to 24000 Ang with an intensity comparable to the one of its 2MASS counterpart and a mostly featureless spectrum. The continuum lacks absorption features and thus is non-stellar in origin and likely non-thermal. On top of this spectrum we detected three emission lines that we interpret as the Halpha-[NII] complex, the [SII] 6716,6731 doublet and the [SIII] 9530 line, obtaining a redshift estimate of z= 0.2321 +/- 0.0004. The equivalent width of the Halpha-[NII] complex implies that PMN J1603-4904 does not follow the observational definition of BL Lac, the line ratios suggest that a LINER/Seyfert nucleus is powering the emission. This new redshift measurement implies that the X-ray line previously detected should be interpreted as a 6.7 keV line which is very peculiar.Comment: Published in Astronomy and Astrophysic

Satellite potentials for hypergeometric Natanzon potentials

As a result of the so(2,1) of the hypergeometric Natanzon potential a set of potentials related to the given one is determined. The set arises as a result of the action of the so(2,1) generators.Comment: 9 page

Coaxial Jets and Sheaths in Wide-Angle-Tail Radio Galaxies

We add 20, 6 and 3.6 cm wavelength VLA observations of two WATs, 1231+674 and 1433+553, to existing VLA data at 6 and 20 cm, in order to study the variations of spectral index as a function of position. We apply the spectral tomography process that we introduced in our analysis of 3C67, 3C190 and 3C449. Both spectral tomography and polarization maps indicate that there are two distinct extended components in each source. As in the case of 3C449, we find that each source has a flat spectrum jet surrounded by a steeper spectrum sheath. The steep components tend to be more highly polarized than the flat components. We discuss a number of possibilities for the dynamics of the jet/sheath systems, and the evolution of their relativistic electron populations. While the exact nature of these two coaxial components is still uncertain, their existence requires new models of jets in FR I sources and may also have implications for the dichotomy between FR Is and FR IIs.Comment: 29 text pages plus 13 figures. Scheduled for publication in May 10, 1999 Ap

A Combined Experimental and Theoretical Study into the Performance of Multilayer Vanadium Dioxide Nanocomposites for Energy Saving Applications

In the built environment there is a increasing issue of heat management, with buildings expending significant energy resources to maintain comfortable living temperatures. In many parts of the world, this entails the use of both heating and cooling during daylight hours depending on ambient temperatures. Due to the variation in the desired temperature control classical solutions can become counter productive in their aim of maintaining comfortable temperatures, therefore it is important to employ adaptive solutions that vary their functionality based on circumstance. In recent years vanadium dioxide (VO2) has generated a broad range of interest due to its heat-mediated structural phase transition from a semiconductor to a metal, which occurs at a critical temperature that may be tuned via doping. The phase transition of VO2 significantly modulates its optical properties, with the high temperature metallic state absorbing and reflecting considerably more infrared radiation than the lower temperature monoclinic state due to the presence of free electrons; a window coated with a VO2 film may passively vary its transmission of infrared radiation based on the ambient temperature, in doing so reducing the temperature management energy-load. Here, we present a theoretically optimised design for a thermochromic smart window film based on a multilayer stack of silica, titania and vanadium dioxide (VO2) on a glass substrate and use the simulations to guide the fabrication process. The design makes use of coherent interference within the multi-layered structure to suppress reflection of visible light and improve the reflective component of solar modulation. In doing so, we are able simultaneously improve the visible transmission and solar modulation of the film above what would be possible with a single layer film. Additionally, the use of thin film VO2 also acts to reduce the detrimental transition hysteresis typically seen in small domain sized nanoparticulate VO2 films. The multilayer structure is fabricated via spin coating of sol-gel based precursors and subsequent annealing. After which the structure is optically characterised and results are compared with simulation along with standard single layer VO2 films and other nanoparticulate based VO2 films

Spindle cell carcinoma: Two instances mistaken for vocal polyps

Spindle cell carcinoma is a variant of squamous carcinoma, with behavior that is apparently more aggressive than that of squamous carcinoma and that can produce distant lymphatic metastasis. It was first described by Virchow in 1864 [1], but the origin of the tumor is still not clear. The tumor is biphasic, with an epidermal component and a sarcomatous component involving spindle cells; transition zones between these components can be found [2–5]. In part due to this peculiar and complex nature, the tumor has accumulated various names since it was first described: sarcomatoid tumor, carci- nosarcoma, pleomorphic carcinoma, collision tumor, etc. [2,5,6]

SST-GATE: A dual mirror telescope for the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) will be the world's first open observatory for very high energy gamma-rays. Around a hundred telescopes of different sizes will be used to detect the Cherenkov light that results from gamma-ray induced air showers in the atmosphere. Amongst them, a large number of Small Size Telescopes (SST), with a diameter of about 4 m, will assure an unprecedented coverage of the high energy end of the electromagnetic spectrum (above ~1TeV to beyond 100 TeV) and will open up a new window on the non-thermal sky. Several concepts for the SST design are currently being investigated with the aim of combining a large field of view (~9 degrees) with a good resolution of the shower images, as well as minimizing costs. These include a Davies-Cotton configuration with a Geiger-mode avalanche photodiode (GAPD) based camera, as pioneered by FACT, and a novel and as yet untested design based on the Schwarzschild-Couder configuration, which uses a secondary mirror to reduce the plate-scale and to allow for a wide field of view with a light-weight camera, e.g. using GAPDs or multi-anode photomultipliers. One objective of the GATE (Gamma-ray Telescope Elements) programme is to build one of the first Schwarzschild-Couder prototypes and to evaluate its performance. The construction of the SST-GATE prototype on the campus of the Paris Observatory in Meudon is under way. We report on the current status of the project and provide details of the opto-mechanical design of the prototype, the development of its control software, and simulations of its expected performance.Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223