We have carried out a series of small scale collisional N-body calculations of single-mass star clusters to investigate the dependence of the lifetime of star clusters on their initial parameters. Our models move through an external galaxy potential with a logarithmic density profile and they are limited by a cut-off radius. In order to find scaling relations between the lifetime of star cluste...

Relations for possible local quasars are studied: the “mass-radius”, “density-mass”, and “radius-density” relations. These relations show clear fragmentation and which is due to the presence of parallel sequences of observations. The cause for this unusual fragmentation is the presence of a term depending on rgr/rq in each respective relation. It seems therefore that fragmentation in these rela...

The stability of a rotating fluid disk to the formation of spiral arms is studied in the tightwinding approximation in the linear regime. The dispersion relation for spirals that was derived by Bertin et al. is shown to contain a new, acoustic instability beyond the Lindblad resonances that depends only on pressure and rotation. In this regime, pressure and gravity exchange roles as drivers and...

BACKGROUND The main purpose of this study was to determine the relationship between serum vitamin D and the status of bone mineral density in patients with low-energy hip and distal radius fracture. METHODS This retrospective case-control study was performed between January 2013 and January 2014. Participants aged 55 years or older were divided to case group including 85 patients with low-ene...

In this paper, we first give a relation between the adjacency spectral radius and the Q-spectral radius of a graph. Then using this result, we further give some new sharp upper bounds on the adjacency spectral radius of a graph in terms of degrees and the average 2-degrees of vertices. Some known results are also obtained.

The study was an attempt to determine the dynamics of heartwood formation and the radial and axial distribution of sapwood and heartwood in stems of European larch (Larix decidua Mill.) representing the dominant stand according to Kraft. Correlations were found between the rate of heartwood formation and the social class of tree position in the stand, the age of trees, forest site type and heig...

Electro-thermo-elastic stress analysis of piezoelectric polymeric thick-walled cylinder reinforced by boronnitride nanotubes (BNNTs) subjected to electro-thermo-mechanical fields is presented in this article. The electro-thermo-elastic properties of piezoelectric fiber reinforced composite (PEFRC) was studied by a modified XY micromechanical model capable of exhibiting full coupling relati...