Stark broadening data for spectral lines of rare-earth elements: Nb III

The electron-impact widths for 15 doubly charged Nb ion lines have been theoretically determined by using the modified semiempirical method. Using the obtained results, we considered the influence of the electron-impact mechanism on line shapes in spectra of chemically peculiar stars and white dwarfs.Comment: 10 pages, 2 figures, 1 table, accepted in Advances in Space Researc

Emission Lines in X-ray Spectra of Clusters of Galaxies

Emission lines in X-ray spectra of clusters of galaxies reveal the presence of heavy elements in the diffuse hot plasma (the Intra Cluster Medium, or ICM) in virial equilibrium in the dark matter potential well. The relatively simple physical state of the ICM allows us to estimate, with good accuracy, its thermodynamical properties and chemical abundances. These measures put strong constraints on the interaction processes between the galaxies and the surrounding medium, and have significant impact on models of galaxy formation as well. This field is rapidly evolving thanks to the X-ray satellites Chandra and XMM-Newton. Among the most relevant progresses in the last years, we briefly discuss the nature of cool cores and the measure of the Iron abundance in high redshift clusters. Future X-ray missions with bolometers promise to provide a substantial step forward to a more comprehensive understanding of the complex physics of the ICM.Comment: 8 pages, 3 figures, Proceedings of the VI Serbian Conference on Spectral Line Shapes in Astrophysics, Sremski Karlovci, Serbia June 11-15 200

Radial Dependence of Extinction in Parent Galaxies of Supernovae

The problem of extinction is the most important issue to be dealt with in the process of obtaining true absolute magnitudes of core-collapse supernovae (SNe). The plane-parallel model which gives absorption dependent on galaxy inclination, widely used in the past, was shown not to describe extinction adequately. We try to apply an alternative model which introduces radial ependence of extinction. A certain trend of dimmer SNe with decreasing radius from the center of a galaxy was found, for a chosen sample of stripped-envelope SNe.Comment: 4 pages, 1 table, 2 figures, 6th SCSLSA Pro

Alkali Line Profiles in Degenerate Dwarfs

Ultracool stellar atmospheres show absorption by alkali resonance lines severely broadened by collisions with neutral perturbers. In the coolest and densest atmospheres, such as those of T dwarfs, Na I and K I broadened by molecular hydrogen and helium can come to dominate the entire optical spectrum. Their profiles have been successfully modelled with accurate interaction potentials in the adiabatic theory, computing line profiles from the first few orders of a density expansion of the autocorrelation function. The line shapes in the emergent spectrum also depend on the distribution of absorbers as a function of depth, which can be modelled with improved accuracy by new models of dust condensation and settling. The far red K I wings of the latest T dwarfs still show missing opacity in these models, a phenomenon similar to what has been found for the Na I line profiles observed in extremely cool, metal-rich white dwarfs. We show that the line profile in both cases is strongly determined by multiple-perturber interactions at short distances and can no longer be reproduced by a density expansion, but requires calculation of the full profile in a unified theory. Including such line profiles in stellar atmosphere codes will further improve models for the coolest and densest dwarfs as well as for the deeper atmosphere layers of substellar objects in general.Comment: VI Serbian Conference on Spectral Line Shapes in Astrophysics; to be published by the American Institute of Physics, eds. Milan S. Dimitrijevic and Luka C. Popovic; 6 pages, 6 figure

Growth Response and Serum Biochemistry of Growing Rabbits Fed Graded Levels of Baobab (Adansonia digitata L.) Seed Kernel Meal

The study was conducted for fifty-six (56) days to investigate the effects of feeding baobab seed kernel meal on growth and serum biochemical indices of grower rabbits. Five isonitrogenous, isocaloric and isofibrous rabbit grower diets were formulated to contain 0, 2.5, 5.0, 7.5 and 10.0% baobab seed kernel meal. Twenty (20) cross bred grower rabbits with mean initial live weight of 916±233.04 grams were randomly distributed to five treatments, each replicated four times in a completely randomized design. Final weight, weight gain, feed intake, feed conversion ratio and protein efficiency ratio were not significantly (P>0.05) different. Serum biochemical indices showed that albumin and alanine aminotransferase values were significantly (P<0.05) elevated by additional inclusion of baobab seed kernel. However, this elevation was not out of normal range reported for healthy rabbits. Creatinine was significantly (P<0.05) reduced at up to 5.0% baobab seed kernel inclusion level, but elevated at higher levels of inclusion. Serum biochemistry values for the experimental groups were within normal range, implying healthy nutrition. Baobab seed kernel meal can be fed to grower rabbits up to 10.0% of the diet without deleterious effect on growth and serum biochemistry.Key Words: Grower rabbits, baobab seed kernel, growth, serum biochemistr

Using genotype abundance to improve phylogenetic inference

Modern biological techniques enable very dense genetic sampling of unfolding evolutionary histories, and thus frequently sample some genotypes multiple times. This motivates strategies to incorporate genotype abundance information in phylogenetic inference. In this paper, we synthesize a stochastic process model with standard sequence-based phylogenetic optimality, and show that tree estimation is substantially improved by doing so. Our method is validated with extensive simulations and an experimental single-cell lineage tracing study of germinal center B cell receptor affinity maturation

Properties and characterization of ALD grown dielectric oxides for MIS structures

We report on an extensive structural and electrical characterization of under-gate dielectric oxide insulators Al2O3 and HfO2 grown by Atomic Layer Deposition (ALD). We elaborate the ALD growth window for these oxides, finding that the 40-100 nm thick layers of both oxides exhibit fine surface flatness and required amorphous structure. These layers constitute a base for further metallic gate evaporation to complete the Metal-Insulator-Semiconductor structure. Our best devices survive energizing up to ~3 MV/cm at 77 K with the leakage current staying below the state-of-the-art level of 1 nA. At these conditions the displaced charge corresponds to a change of the sheet carrier density of 3 \times 1013 cm-2, what promises an effective modulation of the micromagnetic properties in diluted ferromagnetic semiconductors.Comment: 8 pages, 5 figures, 14 reference

Existence and Non-Existence of Doubly Heavy Tetraquark Bound States

In this work we investigate the existence of bound states for doubly heavy tetraquark systems Q¯Q¯′qq′ in a full lattice-QCD computation, where heavy bottom quarks are treated in the framework of non-relativistic QCD. We focus on three systems with quark content b¯b¯ud, b¯b¯us and b¯c¯ud. We show evidence for the existence of b¯b¯ud and b¯b¯us bound states, while no binding appears to be present for b¯c¯ud. For the bound four-quark states we also discuss the importance of various creation operators and give an estimate of the meson-meson and diquark-antidiquark percentages

Faceted wrinkling by contracting a curved boundary

Single-mode deformations of two-dimensional materials, such as the Miura-ori fold, are important to the design of deployable structures because of their robustness, but usually require careful pre-patterning of the material. Here, we show that inward contraction of a curved boundary produces a novel single-mode deformation without any pre-patterning. Using finite-element simulations of the contraction of a thin circular annular sheet, we show that these sheets wrinkle into a structure with negligible stretching energy, in which the contracted boundary forms spontaneous facets. We construct a strictly isometric wrinkled surface formed of triangles and cones that matches geometric and energy features closely, suggesting that this class of partly-faceted wrinkled deformations is isometric. Isometry favours the restriction of such deformations to a robust low-bending energy channel that avoids stretching. This class of buckling also offers a novel way to manipulate sheet morphology via boundary forces. Finally, it serves as a minimal model for illustrating the strong constraints imposed by geometry in elastic pattern formation.Comment: V3. Double column. 6 pages, 5 figures + S