Transformation completeness properties of SVPC transformation sets

AbstractA set T of permutations of a finite set D is said to be transformation complete if the orbits of 〈T〉, the group generated by T, acting on F(D), the power set of D, are exactly the set of subsets of D having the same cardinality, where the orbit of xϵF(D) is {α(x)|αϵ〈T〉}. This paper studies the transformation completeness properties of suppressed variable permutation and complementation (SVPC) transformations which act on Boolean variables with domain being D = {0, 1}n. An SVPC transformation with r control variables is an identity on the n-cube except on an (n − r)-subcube where the acting is like a variable permutation and complementation (VPC) transformation on n − r variables, 0≤r<n. Let Pnr be the set of all SVPC transformations on n variables with r control variables. It is shown that Pnr is transformation complete for n>r≥1. In particular, it is shown that S2n = 〈Pnn−1〉 = 〈Pnn−2〉 ⊃ 〈Pnn−3〉 = 〈Pnn−4〉 = ⋯ = 〈Pn1〉 = A2n ⊃ 〈Pn0〉, where S2n and A2n are the symmetric group and alternating group of degree 2n, respectively. Pn0, i.e., the VPC transformation group on n variables, is not transformation complete, however. Thus, one control variable is necessary and sufficient to make Pnr transformation complete

A dynamic simulation model for possum and gorse control on a farm woodlot

Managers of farm woodlots in New Zealand are confronted by two major problems: possums and gorse. If these remain uncontrolled then they have a severe impact on the returns from farm woodlots. This paper presents a system dynamics model which has been developed to assist in the analysis of control measures for managing gorse and possums on a farm woodlot in the Makara Valley, Wellington. The model has four main sectors: a tree growth module for radiata pine; a growth module for gorse; a module for the stock of possums present in the habitat; and a module of financial indicators. A number of control experiments are presented which indicate the long term financial and physical consequences of different gorse and possum control measures. The model clearly demonstrates the complex nature of the dynamic behaviour of a system involving biological and environmental factors (ie possums, gorse and trees) and human intervention (in terms of silviculture, and possum and gorse control)

Pharyngeal electrical stimulation for treatment of poststroke dysphagia: individual patient data meta-analysis of randomised controlled trials

Background. Dysphagia after stroke is common, associated independently with poor outcome, and has limited treatment options. Pharyngeal electrical stimulation (PES) is a novel treatment being evaluated for treatment of poststroke dysphagia. Methods. We searched electronically for randomised controlled trials of PES in dysphagic patients within 3 months of stroke. Individual patient data were analysed using regression, adjusted for trial, age, severity, and baseline score. The coprimary outcomes were radiological aspiration (penetration aspiration score, PAS) and clinical dysphagia (dysphagia severity rating scale, DSRS) at 2 weeks; secondary outcomes included functional outcome, death, and length of stay in hospital. Results. Three completed trials were identified: 73 patients, age 72 (12) years, severity (NIHSS) 11 (6), DSRS 6.7 (4.3), mean PAS 4.3 (1.8). Compared with no/sham stimulation, PES was associated with lower PAS, 3.4 (1.7) versus 4.1 (1.7), mean difference −0.9 (), and lower DSRS, 3.5 (3.8) versus 4.9 (4.4), mean difference −1.7 (). Length of stay in hospital tended to be shorter: 50.2 (25.3) versus 71.2 (60.4) days (). Functional outcome and death did not differ between treatment groups. Conclusions. PES was associated with less radiological aspiration and clinical dysphagia and possibly reduced length of stay in hospital across three small trials

Geodesic motions in extraordinary string geometry

The geodesic properties of the extraordinary vacuum string solution in (4+1) dimensions are analyzed by using Hamilton-Jacobi method. The geodesic motions show distinct properties from those of the static one. Especially, any freely falling particle can not arrive at the horizon or singularity. There exist stable null circular orbits and bouncing timelike and null geodesics. To get into the horizon {or singularity}, a particle need to follow a non-geodesic trajectory. We also analyze the orbit precession to show that the precession angle has distinct features for each geometry such as naked singularity, black string, and wormhole.Comment: 15 pages, 11 figure

Reaction, Levy Flights, and Quenched Disorder

We consider the A + A --> emptyset reaction, where the transport of the particles is given by Levy flights in a quenched random potential. With a common literature model of the disorder, the random potential can only increase the rate of reaction. With a model of the disorder that obeys detailed balance, however, the rate of reaction initially increases and then decreases as a function of the disorder strength. The physical behavior obtained with this second model is in accord with that for reactive turbulent flow, indicating that Levy flight statistics can model aspects of turbulent fluid transport.Comment: 6 pages, 5 pages. Phys. Rev. E. 65 (2002) 011109--1-

Dephasing of Electrons on Helium by Collisions with Gas Atoms

The damping of quantum effects in the transport properties of electrons deposited on a surface of liquid helium is studied. It is found that due to vertical motion of the helium vapour atoms the interference of paths of duration $t$ is damped by a factor $\exp - (t/\tau_v)^3$. An expression is derived for the weak-localization lineshape in the case that damping occurs by a combination of processes with this type of cubic exponential damping and processes with a simple exponential damping factor.Comment: 7 pages, 2 figures, Revte

Lattice Boltzmann for Binary Fluids with Suspended Colloids

A new description of the binary fluid problem via the lattice Boltzmann method is presented which highlights the use of the moments in constructing two equilibrium distribution functions. This offers a number of benefits, including better isotropy, and a more natural route to the inclusion of multiple relaxation times for the binary fluid problem. In addition, the implementation of solid colloidal particles suspended in the binary mixture is addressed, which extends the solid-fluid boundary conditions for mass and momentum to include a single conserved compositional order parameter. A number of simple benchmark problems involving a single particle at or near a fluid-fluid interface are undertaken and show good agreement with available theoretical or numerical results.Comment: 10 pages, 4 figures, ICMMES 200

Anomalous Flux Flow Resistivity in Two Gap Superconductor MgB_2

The flux flow resistivity associated with purely viscous motion of vortices in high-quality MgB_2 was measured by microwave surface impedance. Flux flow resistivity exhibits unusual field dependence with strong enhancement at low field, which is markedly different to conventional s-wave superconductors. A crossover field which separates two distinct flux flow regimes having different flux flow resistivity slopes was clearly observed in H//ab-plane. The unusual H-dependence indicates that two very differently sized superconducting gaps in MgB_2 manifest in the vortex dynamics and almost equally contribute to energy dissipation. The carrier scattering rate in two different bands is also discussed with the present results, compared to heat capacity and thermal conductivity results.Comment: 4 pages, 3figure

Downhole well log and core montages from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

This paper is not subject to U.S. copyright. The definitive version was published in Marine and Petroleum Geology 28 (2011): 561-577, doi:10.1016/j.marpetgeo.2010.03.016.The BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well was an integral part of an ongoing project to determine the future energy resource potential of gas hydrates on the Alaska North Slope. As part of this effort, the Mount Elbert well included an advanced downhole geophysical logging program. Because gas hydrate is unstable at ground surface pressure and temperature conditions, a major emphasis was placed on the downhole-logging program to determine the occurrence of gas hydrates and the in-situ physical properties of the sediments. In support of this effort, well-log and core data montages have been compiled which include downhole log and core-data obtained from the gas-hydrate-bearing sedimentary section in the Mount Elbert well. Also shown are numerous reservoir parameters, including gas-hydrate saturation and sediment porosity log traces calculated from available downhole well log and core data

Thermodynamics of the half-filled Kondo lattice model around the atomic limit

We present a perturbation theory for studying thermodynamic properties of the Kondo spin liquid phase of the half-filled Kondo lattice model. The grand partition function is derived to calculate chemical potential, spin and charge susceptibilities and specific heat. The treatment is applicable to the model with strong couplings in any dimensions (one, two and three dimensions). The chemical potential equals zero at any temperatures, satisfying the requirement of the particle-hole symmetry. Thermally activated behaviors of the spin(charge) susceptibility due to the spin(quasiparticle) gap can be seen and the two-peak structure of the specific heat is obtained. The same treatment to the periodic Anderson model around atomic limit is also briefly discussed.Comment: 5 pages, 3 figures, to appear in Phys. Rev.