Additional Physical Effects Research Articles

Quantum Field Theory and Dense Measurement

We show, using quantum field theory, that performing a large number of identical repetitions of the same measurement does not only preserve the initial state of the wave function (the Zeno effect), but also produces additional physical effects. We first demonstrate that a Zeno type effect can emerges also in the framework of quantum field theory, that is, as a quantum field phenomenon. We also derive a Zeno type effect from quantum field theory for the general case in which the initial and final states are different. The basic physical entities dealt with in this work are not the conventional once-perfomed physical processes, but their $n$ times repetition where $n$ tends to infinity. We show that the presence of these repetitions entails the presence of additional excited state energies, and the absence of them entails the absence of these excited energies. We also show that in the presence of these repetitions the Schroedinger equation may be derived from the functional generalization of quantum mechanics.

Hybrid Monte Carlo Method for Simulation of Two-Component Aerosol Coagulation and Phase Segregation

The paper presents the development of a hybrid Monte Carlo (MC) method for the simulation of the simultaneous coagulation and phase segregation of an immiscible two-component binary aerosol. The model is intended to qualitatively model our prior studies of the synthesis of mixed metal oxides for which phase-segregated domains have been observed in molten nanodroplets. In our previous works ( J. Aerosol Sci. 32, 1479 (2001); Chem. Eng. Sci. 56, 5763 (2001); submitted for publication) we developed sectional and monodisperse models where the internal state of the aerosol particles was described. These methods have certain limitations and it is difficult to include additional physical effects into the framework. Our new approach combines both constant volume and constant number Monte Carlo methods. Similar to our previous models, we assume that the phase segregation is kinetically controlled. The MC approach allows us to compute the mean number of enclosures (minor phase) per droplet, average enclosure volume, and the width of the enclosure size distribution. The results show that asymptotic behavior of enclosure distribution exists that is independent of initial conditions, which is very close to the continuum self-preserving distribution. Temperature is a key parameter because it allows for a significant change in the internal transport rate within each droplet. In particular, increasing the temperature significantly enhances the Brownian coagulation rate and lowers the number of enclosures per droplet. As a result, the MC results indicate that the growth of the minor phase can be moderated quite dramatically by small changes in system temperature. These results serve to illustrate the utility of this synthesis approach to the controlled growth of nanoparticles through the use of a majority matrix to slow down the encounter frequency of the minor phase and therefore its particle size.

Molecular weight distribution dependent kernels in generalized mixing rules

In this article a model is proposed for the kernel in the generalized mixing rule recently formulated by Anderssen and Mead [Anderssen, R. S. and D. W. Mead, J. Non-Newtonian Fluid Mech. 76, 299–306 (1998)]. In order to derive such a model, it is necessary to take into account the rheological significance of the kernel in terms of the relaxation behavior of the individual polymers involved. This naturally leads to examining how additional physical effects, which depend on the molecular weight distribution, can be included in the mixing rule. The advantage of this approach is that, without changing the generality of the Anderssen and Mead (1998) rule, the choice of the kernel can be used to enhance the physical and rheological significance of their mixing rule.

Electron beam sensitivity of butyl acrylate copolymers: effects of composition on reactivity

Partial transesterification of poly(butyl acrylate) (PBuA) was developed and used as a novel method for obtaining acrylate copolymers possessing the same distribution of the degree of polymerization (DP) as that of the parent PBuA and bearing various organofunctional side groups with olefinic unsaturations or heteroatoms. The series of copolymers exposed to accelerated electron beams exhibited radiation sensitivity expectedly dependent on chemical composition. The copolymer reactivity was examined and quantified by applying the Charlesby-Pinner formalism to the gel fraction content as a function of the absorbed dose. The modifications of reactivity for small variations of the copolymer composition were determined by comparing the values of radiochemical yields for scission G(S) and for crosslinking G(X) of the slightly modified polymers with that of the parent homopolymer. The resulting differential contributions of infinitesimal amounts of functional comonomer units are discussed in terms of intrinsic chemical reactivity. Additional physical effects are also invoked for higher contents in the comonomer that induce variations of polymer segments mobility in the bulk state.

Optical Effects of Ink Spread and Penetration on Halftones Printed by Thermal Ink Jet

A probability-based model of halftone imaging, which was developed in previous work to describe the Yule–Nielsen effect, is shown in the current work to be easily modified to account for additional physical and optical effects in halftone imaging. In particular, the effects of ink spread and ink penetration on the optics of halftone imaging with an ink-jet printer is modeled. The modified probability model was found to fit the experimental data quite well. However, the model appears to overcompensate for the scattering associated with ink penetration into paper.

Dynamical systems theory and extra rates of strain in turbulent flows

Peter Bradshaw has shed considerable light on turbulent flows with extra rates of strain. Here we apply a different approach to two of the flows that Bradshaw studied. We begin with a brief introduction reminding the reader of our application of dynamical systems theory to the flat-plate boundary layer. There we constructed a low-dimensional model that simulated the bursting in the boundary layer, in qualitative agreement with experiment. The bursting frequency responded to modeled polymer additives and flow accelerations by decreasing, resulting in a decreased skin friction, in agreement with experiment. Now we consider the application of this same technique to incompressible turbulent shear flows with streamline curvature in the direction of the mean flow, and to such flows with a transverse strain rate. We show qualitatively how the additional physical effects in these two flows will result in a changed rate of bursting, which will result in a change in the skin friction, likewise in agreement with experiment.

Particle-mesh modelling of drift-wave turbulence

An EPIC (Extended Particle-in-Cell) scheme is developed to model electrostatic drift-wave turbulence in two space dimensions. The efficient inclusion of additional physical effects such as magnetic shear and non-adiabaticity is treated. The algorithm is set out at length together with a numerical stability analysis. Successful simulations of drift-wave interactions are presented: fluctuation level and particle transport are found to be strongly correlated. Finally, arguments favouring the use of EPIC for drift-wave studies are put forward.

GLOMAC : a one dimensional numerical model for steady state low pressure mercury-noble gas discharges

A computer code for describing low pressure mercury-noble gas discharges, with particular application to flourescent lighting, is described. Diffusion equations are formulated for ground and excited states of mercury atoms, and also electrons and molecular mercury ions. All important inelastic process involving mercury atoms and molecules are included. Allowance is also made for the thermal conduction of noble gas temperature. The electron distribution function is computed from an analytic formula, which has been shown to give similar results to those using numerical solutions of the Boltzmann equation. The code runs in a few seconds on a COMPAQ 386 PC or VAX and Micro VAX, andits modular structures enables additional physical effects, such as excitation of noble gas atoms, to be readily included.

Twisted magnetic flux tubes: Effect of small twist

The shape of a magnetic flux tube is investigated when photospheric motion causes small twist at the magnetic footpoints. Using a Fourier-Bessel series expansion, the previous results of Zweibel and Boozer (1985) and Steinolfson and Tajima (1987), when the twist is small, are substantiated. A twisting motion that is restricted to a finite region is investigated. Inside the twisted region, the tube contracts, but in the outer region the field remains straight, except for a slight expansion at the outside of the loop near the footpoints. The amount of twist depends on the radial position and can in fact be larger in the contracted region with the twist decreasing as the tube expands. An axial boundary-layer region is present, as noted by the above authors, through which the field adjusts to the line-tied magnetic footpoint positions. An analysis of the boundary layer shows that the thickness remains constant as the loop-length is increased with the result that the main part of the loop has constant cross-sectional area and can be described by cylindrically-symmetric fields. This new 1-D model predicts the main behaviour of the loop without the need to solve the more complicated 2-D problem directly. It is speculated that the boundary layers will remain even when the twist becomes large and a simple example is presented. A detailed parametric study of different twist profiles shows how the central part of the loop responds. Using the result that the majority of the loop can be described by a constant cross-sectional area, a model for a toroidal loop is presented that models coronal loops in a more realistic manner. The main result from this section is that the coronal loops can only remain in equilibrium if they are confined by an external magnetic field (possibly potential in nature) and not by a gas pressure unless additional physical effects are included.

Unified theories of the pressure broadening and shift of spectral lines. I. General formulation for multipole interactions

General expressions are presented for the line profile produced by an emitting atom embedded in a sea of randomly distributed identical perturbers, on the assumption that the interaction between the emitter and a perturber is of the type 1/Rp, where p>or=3. The motion of each perturber relative to the emitter is treated classically and the trajectory of the perturber is assumed to be a straight line. Results are given for the case in which all emitter-perturber interactions are assumed to be additive; when the emitter is subject to the linear Stark effect, additional results are obtained that do not depend on the assumption of scalar additivity. The profile can be expressed in terms of the Fourier transform of a 'universal' function of a single dimensionless variable that may be evaluated once and for all, since it does not depend explicitly on any particular parameters associated with the spectral line or with the perturbing gas. The properties of this function are studied in detail, and for p>or=4, it is shown that it may be represented very accurately by a semi-empirical analytic function of relatively simple form. It is also shown that certain features of the line profile can depend appreciably on whether or not the correct average over a Maxwellian distribution of velocities of the perturbers is carried out. The use of the semi-empirical universal functions means that profiles can be generated extremely quickly for a particular case, and these can be used as a starting point for a more detailed assessment of the additional physical effects involved that are not included in the present model. Explicit results are given for the cases p=4 and 5; these are relevant to the analysis of the broadening of atomic and molecular lines by molecules.

Limits on the12C to13C isotopic ratio in two white dwarfs

A search for the molecular12C13C isotopic bands in two white dwarfs is described. Spectroscopic observations of the two carbon band white dwarfs, BPM 27606 (=2153-51) andL 879-14 (=0435-08) have been obtained. These data have a resolution slightly better than 2 A, higher than usually employed for white dwarfs and cover the Δv=1 vibrational swan bands of the C2 molecule where the isotopic shift is of order 8 A. The isotopic bands have not been detected. However, upper limits to the12C:13C abundance ratio derived from the data yield12C:13C>40 for BPM 27606 and12C:13C>8 for L879-14. If these ratios are representative of the material in the interiors of the carbon band white dwarfs and taking the low upper limits on the N and O abundances relative to C, this is consistent with the carbon having been formed by the 3α process and not having undergone any subsequent mixing with H-rich material. In addition, the C2 vibrational bandheads are blueshifted, most probably by pressure shifts. This shows that the employment of higher resolutions reveals additional physical effects in the spectra of the carbon band white dwarfs that may become important for interpreting the cool end of the helium rich white dwarf sequence.

A review of theories of mechanisms of induced seismicity

Theories of the physical processes leading to the stimulation of seismic activity by underground explosions, fluid injection, and reservoir impoundment are summarized. In all cases, the materials must be pre-stressed to a substantial fraction of their breaking strength in order for seismicity to be induced. Stress concentrations due to the presence of old faults or to inhomogeneities in the material properties play an important role in localizing induced seismicity. For the few cases for which data are available, the stimulation of earthquakes by fluid injection in bore holes is adequately explained by a Coulomb-Mohr failure criterion and the concept of effective pressure in a water-filled porous mechanism. Reservoir-related earthquakes are most likely due to the same mechanism, but, in view of the low injection pressures, additional physical or chemical effects of the water on the materials may play an important role. There may be a weakening of the materials in old fault zones by the introduction of water or static fatigue in silicate rocks due to stress corrosion.

The expansion of a low-density solar corona: A one-fluid model with magnetically modified thermal conductivity

A one-fluid model of the coronal expansion, including the reduction in radial heat conduction produced by a spiral interplanetary magnetic field, is extended to the low coronal densities that may occur in the regions of open diverging magnetic field lines, or ‘coronal holes,’ that are regarded as probable sources of the solar wind. At such densities, the ‘cutoff’ in heat conduction at very large heliocentric distances (where the magnetic field becomes nearly azimuthal) has a profound effect on the nature of the expansion. The corona becomes nearly isothermal out to the distance where the flow of plasma dominates the transport of energy. This outward extension of high coronal temperatures leads to large solar wind speeds, approaching those given by Parker's original isothermal model as the coronal density becomes vanishingly small. The model predicts expansion speeds as high as 500 km s−1, with densities in agreement with those observed near the orbit of earth, for a reasonable set of coronal densities and temperatures (e.g., with coronal temperatures no higher than 2.1×106 °K). However, the temperatures (or pressures) predicted at the orbit of earth are substantially higher than those observed; this deficiency of the model could only be removed by incorporation of additional physical effects or processes.

Application of an objective method for measuring the action of "antidepressant" medications.

Most investigations of "antidepressant" medications have depended on clinical assessment of the symptom. This study undertook to apply an objective measure of depression to determine the effectiveness of nialamide, as representative of monoamine oxidase inhibitors, in a state hospital population. The results showed that both ward behaviour and depression improved significantly more in a high dosage group than for the low dosage and control groups but at the risk of additional behavioral and physical side effects. It was concluded that the measure of depression employed has merit and that nialamide used watchfully in high doses represents a worthwhile contribution for the treatment of the depressed or apathetic patient.

Solid-State Physical Phenomena and Effects Part II

This is the second in a series of four articles designed to provide ready information to workers in the field of molecular electronics. Fifteen additional solid-state phenomena and physical effects are described. Each of these phenomena belongs to a group whose effects depend either upon the transport of electrons and holes or upon the band structure of the material.

Solid-State Physical Phenomena and Effects: Part I

This is the second in a series of four articles designed to provide ready information to workers in the field of molecular electronics. Fifteen additional solid-state phenomena and physical effects are described. Each of these phenomena belongs to a group whose effects depend either upon the transport of electrons and holes or upon the band structure of the material.