7,066 research outputs found
The double-facing foreign relations function of the executive and its self-enforcing obligation to comply with international law
How does the international Rule of Law apply to constrain the conduct of the Executive within a constitutional State that adopts a dualist approach to the reception of international law? This paper argues that, so far from being inconsistent with the concept of the Rule of Law, the Executive within a dualist constitution has a self-enforcing obligation to abide by the obligations of the State under international law. This is not dependent on Parliament’s incorporation of treaty obligations into domestic law. It is the correlative consequence of the allocation to the Executive of the power to conduct foreign relations. The paper develops this argument in response to recent debate in the United Kingdom on whether Ministers have an obligation to comply with international law–a reference that the Government removed from the Ministerial Code. It shows that such an obligation is consistent with both four centuries of the practice of the British State and with principle
Exact evolution of time-reversible symplectic integrators and their phase error for the harmonic oscillator
The evolution of any factorized time-reversible symplectic integrators, when
applied to the harmonic oscillator, can be exactly solved in a closed form. The
resulting modified Hamiltonians demonstrate the convergence of the Lie series
expansions. They are also less distorted than modified Hamiltonian of
non-reversible algorithms. The analytical form for the modified angular
frequency can be used to assess the phase error of any time-reversible
algorithm.Comment: Submitted to Phys. Lett. A, Six Pages two Column
Dynamical Multiple-Timestepping Methods for Overcoming the Half-Period Time Step Barrier
Current molecular dynamic simulations of biomolecules using multiple time
steps to update the slowingly changing force are hampered by an instability
occuring at time step equal to half the period of the fastest vibrating mode.
This has became a critical barrier preventing the long time simulation of
biomolecular dynamics. Attemps to tame this instability by altering the slowly
changing force and efforts to damp out this instability by Langevin dynamics do
not address the fundamental cause of this instability. In this work, we trace
the instability to the non-analytic character of the underlying spectrum and
show that a correct splitting of the Hamiltonian, which render the spectrum
analytic, restores stability. The resulting Hamiltonian dictates that in
additional to updating the momentum due to the slowly changing force, one must
also update the position with a modified mass. Thus multiple-timestepping must
be done dynamically.Comment: 10 pages, 2 figures, submitted to J. Chem. Phy
Effects of Ore dust pollution on the physical and chemical features, and on the Meiofauna and Microfauna, of a sandy beach
Effects of wind-blown iron and manganese ore dust on the upper part of a sandy beach have been investigated. The fine ore dust was found to reduce the porosity and permeability of the sand by clogging the interstices. The presence of ore dust also greatly increased the rate of heating and cooling of beach sand. Further, ore dust, although of negligible solubility, was found to inhibit the action of aerobic bacteria. This is thought to be due to iron and manganese forming oxidation-reduction combinations in the sand. Ore dust appeared, however, to have no effects on the meiofauna
Studies on the Psammolittoral Meiofauna of Algoa Bay, South Africa
As a precursor to a study of the psammolittoral meiofauna of Algoa Bay, the important physical and chemical features of the beaches have been quantified. A sheltered and an exposed beach were selected. It has been found that the sheltered beach has a finer substrate, greater porosity and more chlorophyll a than the exposed beach. However, owing to the smaller sizes of the interstices, the sands of the sheltered beach have a slower drainage, a lower oxygen availibility in the interstitial water and shallower water tables than the sands of the exposed beach
The larval development and population dynamics of Derocheilocaris algoensis (Crustacea, Mystacocarida)
Seven larval stages of Derocheilocaris algoensis have been described and appear to be identical with those of D. typica from North America. This stresses the remarkable conservativeness of this subclass of Crustacea. The population biology of D. algoensis has been studied over 16 months and reproduction has been found to continue throughout the year but to exhibit some distinct peaks. Growth from egg to reproductively active adult appears to take approximately 60 days. The total life-span is approximately eight months, of which the latter six are spent in reproductive activity
Studies on the Psammolittoral meiofauna of Algoa Bay, South Africa II. The distribution, composition and biomass of the Meiofauna and Macrofauna
Two beaches in Algoa Bay, South Africa, have been found to support a relatively rich and varied meio-fauna. Highest numbers were recorded at HW on the sheltered beach (2 250/10 cm1) and the lowest numbers at LW on the same beach (60/10 cm1). On the exposed beach numbers were more uniform but were highest between MW and LW. Distribution of the meiofauna on the sheltered beach was limited mainly by the amounts of available oxygen in the interstitial water while on the exposed beach amounts of available food, and to a lesser extent oxygen, were limiting. The meiofauna of the sheltered beach was dominated by nematodes and that of the exposed beach by Crustacea (harpacticoid cope-pods and mystacocarids). Meiofauna biomass values were highest in winter and lowest in summer. Macrofauna was richer on the exposed beach, mainly due to the sand mussel, Donax serra. Production estimates based on standing crop indicated that the meiofauna may account for 55 percent and 28 per cent of the total secondary production on the sheltered and exposed beaches respectively
Higher Order Effects in the Dielectric Constant of Percolative Metal-Insulator Systems above the Critical Point
The dielectric constant of a conductor-insulator mixture shows a pronounced
maximum above the critical volume concentration. Further experimental evidence
is presented as well as a theoretical consideration based on a phenomenological
equation. Explicit expressions are given for the position of the maximum in
terms of scaling parameters and the (complex) conductances of the conductor and
insulator. In order to fit some of the data, a volume fraction dependent
expression for the conductivity of the more highly conductive component is
introduced.Comment: 4 pages, Latex, 4 postscript (*.epsi) files submitted to Phys Rev.
Quantum Statistical Calculations and Symplectic Corrector Algorithms
The quantum partition function at finite temperature requires computing the
trace of the imaginary time propagator. For numerical and Monte Carlo
calculations, the propagator is usually split into its kinetic and potential
parts. A higher order splitting will result in a higher order convergent
algorithm. At imaginary time, the kinetic energy propagator is usually the
diffusion Greens function. Since diffusion cannot be simulated backward in
time, the splitting must maintain the positivity of all intermediate time
steps. However, since the trace is invariant under similarity transformations
of the propagator, one can use this freedom to "correct" the split propagator
to higher order. This use of similarity transforms classically give rises to
symplectic corrector algorithms. The split propagator is the symplectic kernel
and the similarity transformation is the corrector. This work proves a
generalization of the Sheng-Suzuki theorem: no positive time step propagators
with only kinetic and potential operators can be corrected beyond second order.
Second order forward propagators can have fourth order traces only with the
inclusion of an additional commutator. We give detailed derivations of four
forward correctable second order propagators and their minimal correctors.Comment: 9 pages, no figure, corrected typos, mostly missing right bracket
- …