Native and rare-earth-doped point-defects in b-PbF2 are studied in the framework of the pair-potential approximation coupled with the shell model description of the lattice ions. For the perfect lattice, a new set of potential parameters are obtained which reproduce structure, elastic and dielectric constants of PbF2 very well. The calculated formation energies for native defects suggest that t...

TOI-1695 is a V-mag=13 M-dwarf star from the northern hemisphere at 45$\,$pc Sun, around which 3.134-day periodic transit signal super-Earth candidate was identified in TESS photometry. With depth of 1.3$\,$mmag, radius TOI-1695.01 estimated by pipeline to be 1.82$\,$R$_\oplus$ with an equilibrium temperature $\sim 620\,$K. We successfully detect reflex motion and establish it due planetary com...

The total precession in longitude for a solid-core, rigid Mars model is found to be A^ = — 7!'296 + 0".01\ yr~ \ This precession includes the motion resulting from the extremely longperiod (> 10 000 yr) nutation components that result from changes in Mars' orbit with time. These same very long-period nutation components also contribute a "precession" in latitude of A£ = 0''4255 + 0!'0012 yr" ^ ...

Abstract Orbit-determination programs find the orbit solution that best fits a set of observations by minimizing root mean square residuals fit. For near-Earth asteroids, uncertainty may be compatible with trajectories impact Earth. This paper shows how incorporating condition as an observation in orbit-determination process results robust technique for finding so-called virtual impactors, i.e....

The Sun’s gradual brightening will seriously compromise the Earth’s biosphere within ∼ 109 years. If Earth’s orbit migrates outward, however, the biosphere could remain intact over the entire main-sequence lifetime of the Sun. In this paper, we explore the feasibility of engineering such a migration over a long time period. The basic mechanism uses gravitational assists to (in effect) transfer ...

historical earthquakes play a notable role in engineering seismology. the historical kashan-sialk region, 3 km south of kashan, was surveyed in the viewpoint of historical earthquakes events. several devastating historical earthquakes, occurred in the bc time, identified based on archaeological studies and evidences gathered from field study. in this respect a variety of information, namely tim...

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...

background: mal::::union:::: is the most common complication following distal radius fractures. aim of this study was to evaluate the results of distal radius corrective osteotomy and plate fixation by dorsal approach in the mal::::union::::. methods: in this retrospective study, 14 patients with neglected distal radius mal::::union:::: from 2005 to 2011 were studied. all patients were treated ...

background: mal:::::union::::: is the most common complication following distal radius fractures. aim of this study was to evaluate the results of distal radius corrective osteotomy and plate fixation by dorsal approach in the mal:::::union:::::. methods: in this retrospective study, 14 patients with neglected distal radius mal:::::union::::: from 2005 to 2011 were studied. all patients were tr...