Fitting functions for dark matter density profiles

We present a unified parameterization of the fitting functions suitable for density profiles of dark matter haloes or elliptical galaxies. A notable feature is that the classical Einasto profile appears naturally as the continuous limiting case of the cored subfamily amongst the double power-law profiles of Zhao (1996). Based on this, we also argue that there is basically no qualitative difference between halo models well-fitted by the Einasto profile and the standard NFW model. This may even be the case quantitatively unless the resolutions of simulations and the precisions of fittings are sufficiently high to make meaningful distinction possible.Comment: 13 pages (6 pages main text + 5 pages appendices + 2 pages full tables) including 5 figures and 7 tables. submitted to MNRA

Exploring the rationale of enlightened shareholder value in the realm of UK company law – the path dependence perspective

Despite conventional beliefs in the predominance of shareholder value, a broader agenda of stakeholder consideration has been advocated in the UK by the recently-introduced ESV principle – the overriding corporate objective in the new company law regime. In this paper, the efficiency of this principle in terms of stakeholder enhancement is challenged through an interdisciplinary analysis. Through a critical review of the ESV principle, it is discovered that stakeholder enhancement practices in the context of the 2006 company law regime are still for the fundamental goal of shareholder value maximisation, and that their enlightened impact has been fairly limited in practice. Furthermore, by revisiting the interrelationships between UK economic, political and cultural factors with the predominance objective of shareholder value maximisation in the Companies Act 2006, it is discovered that the enlightened effect of this new approach in the company law regime is in fact impeded by strong, persistent forces deriving from shareholder-oriented particulars. Providing insight into the future direction of corporate governance practice, the paper concludes the rationale behind the shareholder-oriented ESV principle, and further suggests the continuing predominance of shareholder value in UK corporate governance

Ferromagnetic Type-II Weyl Semimetal in Pyrite Chromium Dioxide

Magnetic topological materials have recently drawn significant importance and interest, due to their topologically nontrivial electronic structure within spontaneous magnetic moments and band inversion. Based on first-principles calculations, we propose that chromium dioxide, in its ferromagnetic pyrite structure, can realize one pair of type-II Weyl points between the $N$th and $(N+1)$th bands, where $N$ is the total number of valence electrons per unit cell. Other Weyl points between the $(N-1)$th and $N$th bands also appear close to the Fermi level due to the complex topological electronic band structure. The symmetry analysis elucidates that the Weyl points arise from a triply-degenerate point splitting due to the mirror reflection symmetry broken in the presence of spin-orbital coupling, which is equivalent to an applied magnetic field along the direction of magnetization. The Weyl points located on the magnetic axis are protected by the three-fold rotational symmetry. The corresponding Fermi arcs projected on both (001) and (110) surfaces are calculated as well and observed clearly. This finding opens a wide range of possible experimental realizations of type-II Weyl fermions in a system with time-reversal breaking.Comment: 8 pages, 5 figure

Newly discovered brown dwarfs not seen in microlensing time scale frequency distribution?

The 2-Micron All Sky Survey (2MASS) (Skrutskie et al. 1997) and the DEep Near Infrared Survey of the southern sky (DENIS) (Epchtein et al. 1997) have revealed a heretofore unknown population of free brown dwarfs that has extended the local mass function down to as small as 0.01M_sun (Reid et al. 1999). If this local proportion of brown dwarfs extends throughout the Galaxy---in particular in the Galactic bulge---one expects an increase in the predicted fraction of short time scale microlensing events in directions toward the Galactic bulge. Zhao et al.(1996) have indicated that a mass function with 30-60% of the lens mass in brown dwarfs is not consistent with empirical microlensing data. Here we show that even the much lower mass fraction (~ 10%) of brown dwarfs inferred from the new discoveries appears inconsistent with the data. The added brown dwarfs do indeed increase the expected number of short time scale events, but they appear to drive the peak in the time scale frequency distribution to time scales smaller than that observed, and do not otherwise match the observed distribution. A reasonably good match to the empirical data (Alcock et al. 1996) is obtained by increasing the fraction of stars in the range 0.08<m<0.7M_sun considerably above that deduced from several star counts. However, all inferences from microlensing about the appropriate stellar mass function must be qualified by the meagerness of the microlensing data and the uncertainties in the Galactic model.Comment: 5 pages, 1 figure. PS file using aas2pp4.sty. To appear in ApJ Letter

Nonequilibrium spin-transfer torque in SFNFS junctions

We report theoretical results for the nonequilibrium spin current and spin-transfer torque in voltage-biased SFNFS Josephson structures. The subharmonic gap structures and high voltage asymptotic behaviors of the dc and ac components of the spin current are analyzed and related to the spin-dependent inelastic scattering of quasiparticles at both F layers.Comment: minor changes, published versio

Infinite-Dimensional Lie Algebras of Generalized Block Type

This paper investigates a class of infinite-dimensional Lie algebras over a field of characteristic 0 which are called here Lie algebras of generalized Block type, and which generalize a class of Lie algebras originally defined by Richard Block. Under certain natural restrictions, this class of Lie algebras is shown to break into five subclasses. One of these subclasses contains all generalized Cartan type K Lie algebras and some Lie algebras of generalized Cartan type H, and a second one is the class of Lie algebras type L, which were previously defined and studied elsewhere by the authors. The other three types are hybrids of the first two types, and are new