Morpho-kinematic analysis of the point-symmetric, bipolar planetary nebulae Hb 5 and K 3-17, a pathway to poly-polarity

The kinematics of the bipolar planetary nebulae Hb~5 and K 3-17 are investigated in detail by means of a comprehensive set of spatially resolved high spectral resolution, long-slit spectra. Both objects share particularly interesting characteristics, such as a complex filamentary, rosette-type nucleus, axial point-symmetry and very fast bipolar outflows. The kinematic information of Hb~5 is combined with {\it HST} imagery to construct a detailed 3D model of the nebula using the code SHAPE. The model shows that the large scale lobes are growing in a non-homologous way. The filamentary loops in the core are proven to actually be secondary lobes emerging from what appears to be a randomly punctured, dense, gaseous core and the material that forms the point symmetric structure flows within the lobes with a distinct kinematic pattern and its interaction with the lobes has had a shaping effect on them. Hb~5 and K~3-17 may represent a class of fast evolving planetary nebulae that will develop poly-polar characteristics once the nebular core evolves and expands.Comment: 19 pages, 8 figures. To appear in The Astrophysical Journa

Effect of nitrogen gas in the agglomeration and photoluminescence of Zn-ZnO nanowires after high-temperature annealing

The effect of anti-agglomeration and enhanced photoluminescence after high-temperature annealing of Zn-ZnO nanowires in nitrogen at-mosphere is reported. The Zn-ZnO nanowires were deposited by the hot filament chemical vapor deposition technique and subsequentlyannealed at 1100±C in oxygen or nitrogen atmospheres. It was found that under both annealing atmospheres, the structure of the nanowireswas completely oxidized. Morphological studies suggest that annealing under oxygen-rich atmosphere, grain growth occurs, resulting in acontinuous surface with a micrograin-shaped structure. However, it seems that nitrogen-rich annealing partially prevents complete agglom-eration and longitudinal structures composed by nanometric grains were observed. Although photoluminescence properties of the annealednanowires are improved in both annealing atmospheres, it was observed that the PL spectrum of nanowires annealed in nitrogen showed astronger UV emission than that of the oxygen annealed nanowires

The merger history of massive spheroids since z~1 is size independent

Using a compilation of 379 massive (stellar mass M > 10^{11} M_Sun) spheroid-like galaxies from the near-infrared Palomar/DEEP-2 survey, we have probed, up to z~1, whether the presence of companions depends on the size of the host galaxies. We have explored the presence of companions with mass ratios down to 1:10 and 1:100, with respect to the central massive galaxy, and within a projected distance of 30, 50 and 100 kpc of these objects. We find evidence for these companions being equally distributed around both compact and extended massive spheroids. This finding suggests that, at least since z~1, the merger activity in these objects is rather homogeneous across the whole population and its merger history is not affected for the size of the host galaxy. Our result could indicate that both compact and extended massive spheroid-like galaxies are growing in size at the same rate.Comment: 9 pages, 6 figures, accepted for publication in MNRA

Testing models with non-minimal Higgs sector through the decay t->q+WZ

We study the contribution of charged Higgs boson to the rare decay of the top quark t->q+WZ (q=d,s,b) in models with Higgs sector that includes doublets and triplets. Higgs doublets are needed to couple charged Higgs with quarks, whereas the Higgs triplets are required to generate the non-standard vertex HWZ at tree-level. It is found that within a model that respect the custodial SU(2) symmetry and avoids flavour changing neutral currents by imposing discrete symmetries, the decay mode t->b+WZ, can reach a branching ratio of order 0.0178, whereas the decay modes t->(d,s)+WZ, can reach a similar branching ratio in models where flavour changing neutral currents are suppressed by flavour symmetries.Comment: Typeset using REVTEX and EPSF, 5 pag, 2 figure

PEDESTRIAN PATHFINDING in URBAN ENVIRONMENTS: PRELIMINARY RESULTS

With the rise of urban population, many initiatives are focused upon the smart city concept, in which mobility of citizens arises as one of the main components. Updated and detailed spatial information of outdoor environments is needed to accurate path planning for pedestrians, especially for people with reduced mobility, in which physical barriers should be considered. This work presents a methodology to use point clouds to direct path planning. The starting point is a classified point cloud in which ground elements have been previously classified as roads, sidewalks, crosswalks, curbs and stairs. The remaining points compose the obstacle class. The methodology starts by individualizing ground elements and simplifying them into representative points, which are used as nodes in the graph creation. The region of influence of obstacles is used to refine the graph. Edges of the graph are weighted according to distance between nodes and according to their accessibility for wheelchairs. As a result, we obtain a very accurate graph representing the as-built environment. The methodology has been tested in a couple of real case studies and Dijkstra algorithm was used to pathfinding. The resulting paths represent the optimal according to motor skills and safety