New Fe II energy levels from stellar spectra

The spectra of B-type and early A-type stars show numerous unidentified lines in the whole optical range, especially in the 5100 - 5400 A interval. Because Fe II transitions to high energy levels should be observed in this region, we used semiempirical predicted wavelengths and gf-values of Fe II to identify unknown lines. Semiempirical line data for Fe II computed by Kurucz are used to synthesize the spectrum of the slow-rotating, Fe-overabundant CP star HR 6000. We determined a total of 109 new 4f levels for Fe II with energies ranging from 122324 cm^-1 to 128110 cm^-1. They belong to the Fe II subconfigurations 3d^6(^3P)4f (10 levels), 3d^6(^3H)4f (36 levels), 3d^6(^3F)4f (37 levels), and 3d^6(^3G)4f (26 levels). We also found 14 even levels from 4d (3 levels), 5d (7 levels), and 6d (4 levels) configurations. The new levels have allowed us to identify more than 50% of the previously unidentified lines of HR 6000 in the wavelength region 3800-8000 A. Tables listing the new energy levels are given in the paper; tables listing the spectral lines with loggf>/=-1.5 that are transitions to the 4f energy levels are given in the Online Material. These new levels produce 18000 lines throughout the spectrum from the ultraviolet to the infrared.Comment: Paper accepted by A&A for publicatio

Existence and instability of steady states for a triangular cross-diffusion system: a computer-assisted proof

In this paper, we present and apply a computer-assisted method to study steady states of a triangular cross-diffusion system. Our approach consist in an a posteriori validation procedure, that is based on using a fxed point argument around a numerically computed solution, in the spirit of the Newton-Kantorovich theorem. It allows us to prove the existence of various non homogeneous steady states for different parameter values. In some situations, we get as many as 13 coexisting steady states. We also apply the a posteriori validation procedure to study the linear stability of the obtained steady states, proving that many of them are in fact unstable

Motivating Strategies Leaders Employ to Increase Follower Effort

The purpose of this research was to determine which motivating strategies followers desire from their leaders and what motivating strategies are actually displayed by their leaders to increase followers’ effort. Additionally, this research assessed the followers’ level of self-reported extra effort and the amount of extra effort followers perceive their leaders exert. From this data, conclusions were drawn regarding the relationships between followers’ self-reported extra effort and the followers’ perception of their leaders’ extra effort. This quantitative research study was conducted via LinkedIn using Survey Monk ey and is based on Keller’s 42 item ARCS Model (attention, relevance, confidence, and satisfaction). Regression analysis of the survey responses indicated that: 1) Followers perceive their leaders are not displaying the level of motivating strategies desired; 2) The amount of extra effort that followers perceive that their leaders exert is significant in predicting the amount of extra effort that followers exert; and 3) Followers’ perception is that leaders’ extra effort is less than followers’ extra effort. The findings suggest that leaders should be more aware of the motivating strategies that followers desire and demonstrate those strategies since leaders’ extra effort is a significant predictor of followers’ extra effort. Additionally, leaders should also exert the level of effort that they desire from their followers

A study of the apsidal angle and a proof of monotonicity in the logarithmic potential case

This paper concerns the behaviour of the apsidal angle for orbits of central force system with homogenous potential of degree $-2\leq \alpha\leq 1$ and logarithmic potential. We derive a formula for the apsidal angle as a fixed-end points integral and we study the derivative of the apsidal angle with respect to the angular momentum $\ell$. The monotonicity of the apsidal angle as function of $\ell$ is discussed and it is proved in the logarithmic potential case.Comment: 24 pages, 1 figur