Keystone XL Pipeline Project: Key Issues

[Excerpt] This report describes the Keystone XL Project as it is proposed in the 2012 Presidential Permit application and the process that the State Department is obligated to complete to issue or deny that application. To the extent that they may affect the State Department’s decision to issue or deny the current permit application, this report discusses selected issues related to the project proposed in 2008 and issues that have arisen since the State Department denied the initial permit application in 2012. This report also summarizes key arguments that have been raised, both for and against the pipeline, by the pipeline’s developers, state and federal agencies, environmental groups, private property owners, and other stakeholders. Finally, the report discusses the constitutional basis for the State Department’s authority to issue a Presidential Permit, and opponents’ possible challenges to this authority

Child support enforcement for teenage fathers: Problems and prospects

The NLSY data indicate that about 7.3 percent of teenage males become fathers and that very few of these fathers live with their children. Father absence and the concurrent increase in female-headed households are closely associated with the impoverishment of children. Most absent teen fathers never come into contact with the child support enforcement program, and the extent to which they financially support their children informally is not well understood. While the income of absent teen fathers is low in the teen years, it increases over time, as does the potential for collecting child support. Nevertheless, men who were absent teen fathers earn less in early adulthood than men who deferred parenting until age twenty or later and teen fathers who lived with their children. Early establishment of paternity and greater standardization in the treatment of adolescent fathers by the child support enforcement program are recommended. Further, the substantial and persistent income deficit experienced by adolescent fathers who live apart from their children raises an interesting dilemma. While children may benefit financially and psychosocially from living with two parents, the lower income of men who were absent teenage fathers may make them poor marital prospects. This raises doubts about the recent recommendations of some scholars that we should bring back the shotgun wedding.

Another factor to consider in choosing a child support guideline: Errors in child support calculations

In an effort to standardize the calculation of monthly child support awards, the federal government requires states to use preestablished formulas to determine the amount of awards. However, because of human error, differences in the experience and training of the officials making the calculations, and the extent to which computers are used to calculate the awards, the formulas do not always yield the same result. In fact, the discrepancy between the amount calculated by an individual child support official and the approved amount as calculated by the state in which that official works can be quite large, on the order of several hundred dollars. Adopting simpler formulas will reduce errors; this should be a priority even if child support officials use computers to calculate award amounts (computers can reduce errors but will not eliminate them, particularly in the case of complex formulas). Efforts to further the training and education of personnel who calculate awards would also help, and child support offices should revise their formulas to cover high-income cases.

Geometry of Keplerian disk systems and bounds on masses of their components

We investigate accreting disk systems with polytropic gas in Keplerian motion. Numerical data and partial analytic results show that the self-gravitation of the disk speeds up its rotation -- its rotational frequency is larger than that given by the well known strictly Keplerian formula that takes into account the central mass only. Thus determination of central mass in systems with massive disks requires great care -- the strictly Keplerian formula yields only an upper bound. The effect of self-gravity depends on geometric aspects of disk configurations. Disk systems with a small (circa $10^{-4}$) ratio of the innermost radius to the outermost disk radius have the central mass close to the upper limit, but if this ratio is of the order of unity then the central mass can be smaller by many orders of magnitude from this bound.Comment: 20 pages, 10 figure

Estimating masses of Keplerian disk systems: the case of AGN in NGC 4258

The Keplerian motion of accretion disks in Active Galactic Nuclei (AGN) is usually believed to be generated by a heavy central mass. We investigate accreting disk systems with polytropic gas in Keplerian rotation and obtain a phenomenological formula that relates the Keplerian angular frequency to the ratio of disk and central masses. Central mass approaches the Keplerian value, if the inner boundary of a disk is close to the minimal stable orbit of a black hole. These results are applied to NGC 4258, the unique AGN with a finely measured Keplerian rotation curve of the central disk, with the conclusion that its rotation curve is, in fact, determined by the central black hole. The mass of the accretion disk exceeds 100 solar masses.Comment: 7 pages, 2 figures, to appear in Acta Phys. Pol.

General-relativistic rotation: self-gravitating fluid tori in motion around black holes

We obtain from the first principles a general-relativistic Keplerian rotation law for self-gravitating disks around spinning black holes. This is an extension of a former rotation law that was designed mainly for toroids around spin-less black holes. We integrate numerically axial stationary Einstein equations with self-gravitating disks around spinless or spinning black holes; that includes the first ever integration of the Keplerian selfgravitating tori. This construction can be used for the description of tight black hole-torus systems produced during coalescences of two neutron stars or modelling of compact active galactic nuclei.Comment: Matches published versio

Molecular markers and HPV detection in the diagnosis of lower genital tract lesions

Meijer, C.J.L.M. [Promotor]Quint, W.G.V. [Copromotor

Self-gravitating magnetised tori around black holes in general relativity

We investigate stationary, self-gravitating, magnetised disks (or tori) around black holes. The models are obtained by numerically solving the coupled system of the Einstein equations and the equations of ideal general-relativistic magnetohydrodynamics. The mathematical formulation and numerical aspects of our approach are similar to those reported in previous works modeling stationary self-gravitating perfect-fluid tori, but the inclusion of magnetic fields represents a new ingredient. Following previous studies of purely hydrodynamical configurations, we construct our models assuming Keplerian rotation in the disks and both spinning and spinless black holes. We focus on the case of a toroidal distribution of the magnetic field and build a large set of models corresponding to a wide range of values of the magnetisation parameter, starting with weakly magnetised disks and ending at configurations in which the magnetic pressure dominates over the thermal one. In all our models, the magnetic field affects the equilibrium structure of the torus mainly due to the magnetic pressure. In particular, an increasing contribution of the magnetic field shifts the location of the maximum of the rest-mass density towards inner regions of the disk. The total mass of the system and the angular momentum are affected by the magnetic field in a complex way, that depends on the black hole spin and the location of the inner radius of the disk. The non-linear dynamical stability of the solutions presented in this paper will be reported elsewhere.Comment: 17 pages, 5 figures, 1 tabl