Spectroscopic diagnostics of dust formation and evolution in classical nova ejecta

A fraction of classical novae form dust during the early stages of their outbursts. The classical CO nova V5668 Sgr (Nova Sgr. 2015b) underwent a deep photometric minimum about 100 days after outburst that was covered across the spectrum. A similar event was observed for an earlier CO nova, V705 Cas (Nova Cas 1993) and a less optically significant event for the more recent CO nova V339 Del (Nova Del 2013). This study provides a "compare and contrast" of these events to better understand the very dynamical event of dust formation. We show the effect of dust formation on multiwavelength high resolution line profiles in the interval 1200\AA\ - 9200\AA\ using a biconical ballistic structure that has been applied in our previous studies of the ejecta. We find that both V5668 Sgr and V339 Del can be modeled using a grey opacity for the dust, indicating fairly large grains (at least 0.1 micron) and that the persistent asymmetries of the line profiles in late time spectra, up to 650 days after the event for V5668 Sgr and 866 days for V339 Del, point to the survival of the dust well into the transparent, nebular stage of the ejecta evolution. This is a general method for assessing the properties of dust forming novae well after the infrared is completely transparent in the ejecta.Comment: 15 pages 14 figures, accepted for publication in A&A, 2018 June 2

Hierarchical structuring of Cultural Heritage objects within large aggregations

Huge amounts of cultural content have been digitised and are available through digital libraries and aggregators like Europeana.eu. However, it is not easy for a user to have an overall picture of what is available nor to find related objects. We propose a method for hier- archically structuring cultural objects at different similarity levels. We describe a fast, scalable clustering algorithm with an automated field selection method for finding semantic clusters. We report a qualitative evaluation on the cluster categories based on records from the UK and a quantitative one on the results from the complete Europeana dataset.Comment: The paper has been published in the proceedings of the TPDL conference, see http://tpdl2013.info. For the final version see http://link.springer.com/chapter/10.1007%2F978-3-642-40501-3_2

The spectroscopic evolution of the γ\gamma-ray emitting classical nova Nova Mon 2012. I. Implications for the ONe subclass of classical novae

Nova Mon 2012 was the first classical nova to be detected as a high energy $\gamma$-ray transient, by Fermi-LAT, before its optical discovery. We study a time sequence of high resolution optical echelle spectra (Nordic Optical Telescope) and contemporaneous NOT, STIS UV, and CHIRON echelle spectra (Nov 20/21/22). We use [O III] and H$\beta$ line fluxs to constrain the properties of the ejecta. We derive the structure from the optical and UV line profiles and compare our measured line fluxes for with predictions using Cloudy with abundances from other ONe novae. Mon 2012 is confirmed as an ONe nova. We find E(B-V)=0.85$\pm$0.05 and hydrogen column density $\approx 5\times 10^{21}$ cm$^{-2}$. The corrected continuum luminosity is nearly the same in the entire observed energy range as V1974 Cyg, V382 Mon, and Nova LMC 2000 at the same epoch after outburst. The distance, about 3.6 kpc, is quite similar to V1974 Cyg. The line profiles can be modeled using an axisymmetric bipolar geometry for the ejecta with various inclinations of the axis to the line of sight, 60 \le i \le 80 degrees, an opening angle of \approx$70 deg, inner radius$\Delta R/R(t)\approx 0.4$for permitted lines and less filled for forbidden lines. The filling factor$f\approx 0.1-0.3$implying M(ejecta)$\leq 6\times 10^{-5}$M$_\odot$. The ONe novae appear to comprise a single physical class with bipolar high mass ejecta, similarly enhanced abundances, and a common spectroscopic evolution within a narrow range of luminosities. The detected$\gamma$-ray emission may be a generic phenomenon, common to all ONe novae, possibly to all classical novae, and connected with acceleration and emission processes within the ejecta (abstract severely truncated).Comment: Submitted to A&A 9/1/2013; Accepted 27/2/2013 (in press

The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. II.The optically thin phase and the structure of the ejecta in recurrent novae

We continue our study of the physical properties of the recurrent nova T Pyx, focussing on the structure of the ejecta in the nebular stage of expansion during the 2011 outburst. The nova was observed contemporaneously with the Nordic Optical Telescope (NOT), at high resolution spectroscopic resolution (R ~ 65000) on 2011 Oct. 11 and 2012 Apr. 8 (without absolute flux calibration), and with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope, at high resolution (R ~ 30000) on 2011 Oct. 10 and 2012 Mar. 28 (absolute fluxes). We use standard plasma diagnostics (e.g. [O III] and [N II] line ratios and the H$\beta$ line fluxes) to constrain electron densities and temperatures. Using Monte Carlo modeling of the ejecta, we derive the structure and filling factor from comparisons to the optical and ultraviolet line profiles. The ejecta can be modeled using an axisymmetric conical -- bipolar -- geometry with a low inclination of the axis to the line of sight, i=15+/-5 degrees, compatible with published results from high angular resolution optical spectro-interferometry. The structure is similar to that observed in the other short orbital period recurrent novae during their nebular stages. We show that the electron density scales as $t^{-3}$ as expected from a ballistically ejected constant mass shell; there is no need to invoke a continuing mass outflow following the eruption. The derived mass for the ejecta with filling factor f ~ 3%, M_ej ~ 2E-6$M_sun is similar to that obtained for other recurrent nova ejecta but inconsistent with the previously reported extended optically thick epoch of the explosion. We suggest that the system underwent a common envelope phase following the explosion that produced the recombination event. Implications for the dynamics of the recurrent novae are discussed. (truncated)Comment: accepted for publication in A&A (10 Nov. 2012), 10 pgs, 16 fig

Laser and radiofrequency ablations for benign and malignant thyroid tumors

A growing body of evidence is being published regarding the safety and efficacy of minimally invasive image-guided ablation techniques. While clinical applications of these techniques are increasing, international societies have started to publish treatment guidelines and to make efforts to standardize both terminology and reporting criteria for image-guided thyroid ablations. Laser ablation and radiofrequency ablation (RFA) are among the most common ablation techniques either for benign and malignant thyroid nodules. Unlike laser ablation and RFA in the treatment of benign thyroid nodules, where safety and efficacy have been widely demonstrated, evidence regarding local tumor control of thyroid malignancies is still limited. However, preliminary results are encouraging and image-guided thermal ablation techniques can be considered a valid alternative to surgery for the treatment of benign thyroid nodules and recurrent thyroid cancers. This review evaluates the basic concept of RFA and laser ablations, their techniques, clinical outcomes, and complications based on the suggestions of several society guidelines. Multidisciplinary collaboration remains critical to identify patients which may benefit from minimally invasive image-guided thermal ablations, especially if surgery or radioiodine therapy are not feasible options

Age spread in Galactic star forming region W3 Main

We present near-infrared JHKs imaging as well as K-band multi-object spectroscopy of the massive stellar content of W3 Main using LUCI at the LBT. We confirm 13 OB stars by their absorption line spectra in W3 Main and spectral types between O5V and B4V have been found. Three massive Young Stellar Objects are identified by their emission line spectra and near-infrared excess. From our spectrophotometric analysis of the massive stars and the nature of their surrounding HII regions we derive the evolutionary sequence of W3 Main and we find an age spread of 2-3 Myr.Comment: 4 pages, 2 figures, To appear in conference proceedings of "370 years of Astronomy in Utrecht

Resistance traits and AFLP characterization of diploid primitive tuber-bearing potatoes.

ISSN: 0925-986

Experimental evidence of s-wave superconductivity in bulk CaC6_{6}

The temperature dependence of the in-plane magnetic penetration depth, $\lambda_{ab}(T)$, has been measured in a c-axis oriented polycrystalline CaC$_{6}$ bulk sample using a high-resolution mutual inductance technique. A clear exponential behavior of $\lambda_{ab}(T)$ has been observed at low temperatures, strongly suggesting isotropic s-wave pairing. Data fit using the standard BCS theory yields $\lambda_{ab}(0)=(720\pm 80)$ Angstroem and $\Delta(0)=(1.79\pm 0.08)$ meV. The ratio $2\Delta(0)/k_{_B}T_{c}=(3.6\pm 0.2)$ gives indication for a conventional weakly coupled superconductor.Comment: To appear in Phys. Rev. Let

Optimized Realization of Bayesian Networks in Reduced Normal Form using Latent Variable Model

Bayesian networks in their Factor Graph Reduced Normal Form (FGrn) are a powerful paradigm for implementing inference graphs. Unfortunately, the computational and memory costs of these networks may be considerable, even for relatively small networks, and this is one of the main reasons why these structures have often been underused in practice. In this work, through a detailed algorithmic and structural analysis, various solutions for cost reduction are proposed. An online version of the classic batch learning algorithm is also analyzed, showing very similar results (in an unsupervised context); which is essential even if multilevel structures are to be built. The solutions proposed, together with the possible online learning algorithm, are included in a C++ library that is quite efficient, especially if compared to the direct use of the well-known sum-product and Maximum Likelihood (ML) algorithms. The results are discussed with particular reference to a Latent Variable Model (LVM) structure.Comment: 20 pages, 8 figure