2,842 research outputs found
Legislation for business: is it fit for public consumption?
‘We are convinced that a central problem of the legislative process is that far too many bills are introduced into Parliament in a state that is recognised — even,we suspect, by Ministers — to be less than perfect.’ In short, ‘... bills are too often introduced to Parliament \'half-baked\' and with a lot of the detail insufficiently thought out ...’. I would not mind were Parliament a competent cook, able to complete a process started by government. Were that so, our elected representatives would enhance the democratic process by the part they played in turning out the final product. But the heat of parliamentary debate is rarely sufficient: what enters Parliament half-baked usually emerges half-baked, or worse. ‘The weight and extent of the criticisms received is perhaps the most notable feature of our enquiry.’ Criticism of legislation is as old as legislation itself. King Edward the Sixth wished that ‘the superfluous and tedious statutes were brought into one sum together, and made more plain and short, to the intent that men might better understand them’. But ‘half-baked’ does not just refer to a failure to achieve simplicity or clarity in legislation; it refers to the failure of legislation to achieve its purpose of converting the aims and objectives of government policy into practical rules to regulate our lives in a sophisticated society.
Budgetary reform: the impact of a December Budget on the Finance Bill and the development of tax legislation
This paper considers the Government’s proposals for reforming the budgetary process from the perspective of its impact on the Finance Bill and the development of tax legislation. The paper is divided into three parts. First, it summarises briefly what the White Paper has to say on the subject of the Budget tax proposals, the Finance Bill and tax administration. Thereafter, it considers the implications that a change to a December Budget will have on the Finance Bill process. Finally, the paper looks at possible ways of reforming the system by which tax legislation is developed and enacted.
Three-Dimensional Simulations of Magnetized Thin Accretion Disks around Black Holes: Stress in the Plunging Region
We describe three-dimensional general relativistic magnetohydrodynamic
simulations of a geometrically thin accretion disk around a non-spinning black
hole. The disk has a thickness over the radial range
. In steady state, the specific angular momentum profile of the
inflowing magnetized gas deviates by less than 2% from that of the standard
thin disk model of
Novikov & Thorne (1973). Also, the magnetic torque at the radius of the
innermost stable circular orbit (ISCO) is only of the inward flux of
angular momentum at this radius. Both results indicate that magnetic coupling
across the ISCO is relatively unimportant for geometrically thin disks.Comment: 4 pages, 4 figures, ApJL accepte
Can Nonlinear Hydromagnetic Waves Support a Self-Gravitating Cloud?
Using self-consistent magnetohydrodynamic (MHD) simulations, we explore the
hypothesis that nonlinear MHD waves dominate the internal dynamics of galactic
molecular clouds. We employ an isothermal equation of state and allow for
self-gravity. We adopt ``slab-symmetry,'' which permits motions
and fields perpendicular to the mean field, but permits gradients
only parallel to the mean field. The Alfv\'en speed exceeds the sound
speed by a factor . We simulate the free decay of a spectrum of
Alfv\'en waves, with and without self-gravity. We also perform simulations with
and without self-gravity that include small-scale stochastic forcing.
Our major results are as follows: (1) We confirm that fluctuating transverse
fields inhibit the mean-field collapse of clouds when the energy in Alfv\'en-
like disturbances remains comparable to the cloud's gravitational binding
energy. (2) We characterize the turbulent energy spectrum and density structure
in magnetically-dominated clouds. The spectra evolve to approximately
with ,
i.e. approximately consistent with a ``linewidth-size'' relation . The simulations show large density contrasts, with high
density regions confined in part by the fluctuating magnetic fields. (3) We
evaluate the input power required to offset dissipation through shocks, as a
function of , the velocity dispersion , and the scale
of the forcing. In equilibrium, the volume dissipation rate is
, for a cloud of
linear size and density . (4) Somewhat speculatively, we apply our
results to a ``typical'' molecular cloud. The mechanical power input requiredComment: Accepted for publication in Ap.J. 47 pages, 13 postscript figures.
Report also available at http://cfa-www.harvard.edu/~gammie/MHD.p
Dependence of inner accretion disk stress on parameters: the Schwarzschild case
We explore the parameter dependence of inner disk stress in black hole
accretion by contrasting the results of a number of simulations, all employing
3-d general relativistic MHD in a Schwarzschild spacetime. Five of these
simulations were performed with the intrinsically conservative code HARM3D,
which allows careful regulation of the disk aspect ratio, H/R; our simulations
span a range in H/R from 0.06 to 0.17. We contrast these simulations with two
previously reported simulations in a Schwarzschild spacetime in order to
investigate possible dependence of the inner disk stress on magnetic topology.
In all cases, much care was devoted to technical issues: ensuring adequate
resolution and azimuthal extent, and averaging only over those time-periods
when the accretion flow is in approximate inflow equilibrium. We find that the
time-averaged radial-dependence of fluid-frame electromagnetic stress is almost
completely independent of both disk thickness and poloidal magnetic topology.
It rises smoothly inward at all radii (exhibiting no feature associated with
the ISCO) until just outside the event horizon, where the stress plummets to
zero. Reynolds stress can also be significant near the ISCO and in the plunging
region; the magnitude of this stress, however, depends on both disk thickness
and magnetic topology. The two stresses combine to make the net angular
momentum accreted per unit rest-mass 7-15% less than the angular momentum of
the ISCO.Comment: Accepted for publication in ApJ, 52 pages, 38 figures, AASTEX.
High-resolution versions can be found at the following links:
http://ccrg.rit.edu/~scn/papers/schwarzstress.ps,
http://ccrg.rit.edu/~scn/papers/schwarzstress.pd
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