Pure Vector Research Articles

Continuous field components at FE-interfaces due to complex magnetic scalar potential

A method is presented which solves the problem of discontinuous magnetic field components at common boundaries of adjacent finite elements. This new approach combines the advantages of using complex variable potential functions for triangular finite elements. As calculated flux quantities deviate from those obtained by a pure scalar potential or vector potential approach, continuous magnetic field components are guaranteed by a new post-processing technique. The method's merits are illustrated by a simple numerical example.

Reconstructing the Wavefunction in Quantum Optics

The problem of reconstructing a wavefunction from probability distributions is re-examined in the context of whether a pure state vector of a single-mode optical field can be reconstructed from the...

RF transition systems for the Triangle Universities Nuclear Laboratory atomic beam polarized ion source

A system of compact radio-frequency transitions, consisting of two medium-field units and a single strong-field unit, has recently been installed and tested in the atomic-beam polarized ion source at the Triangle Universities Nuclear Laboratory. With care and proper tuning, this new system provides deuteron pure vector beam polarizations of p z = ±0.55 and deuteron pure tensor beam polarizations of p zz = +0.90 and p zz = −1.50 as well as proton beam polarizations of p z = ±0.75. In this report, we describe both an earlier system and this new improved version, with emphasis on the problems we experienced and the solutions devised to solve them.

Search for T-violation in K+ decays

In this paper, we analyze the elastic scattering of the muon neutrino (νμ) beam on the polarized proton target (PPT) in a presence of induced couplings, and predict how the existence of relative phases between the complex vector (weak magnetism) and axial (induced pseudoscalar) form factors of the proton with left-chirality νμ affects the azimuthal dependence of the differential cross section. The neutrinos are assumed to be Dirac fermions with non-zero mass and CPT symmetry is conserved. We show that the azimuthal asymmetry of recoil protons depends on the neutrino mass, but contributions are very tiny (∼10−5). Analysis of the differential cross section in the case of pure vector and axial couplings at zero νμ mass limit and zero momentum transfer shows that the T-violating phase βVA generates the T-odd, P-even triple correlation and it could be detected by measuring the asymmetry between the (0,π) and (π,2π) angles. It should be clearly stressed that the considered T-odd observable is not a genuine CP-violating quantity as it can also be produced by the T-invariant contributions due to the final state interactions (FSI). Their magnitude must be precisely estimated and subtracted from the measured observable to extract information on the possible time reversal violation (TRV). We also indicate the possibility of using the PPT in the neutrino telescope.

Nonperturbative solutions and scaling properties of vector and axial-vector electrodynamics in 1+1 dimensions.

We study by nonperturbative techniques a vector and axial-vector theory characterized by a parameter which interpolates between pure vector and chiral Schwinger models. The main results are two ranges in the space of parameters which exhibit acceptable solutions. In the first range we find a free massive and a free massless bosonic excitation and interacting left-right fermions endowed with asymptotic states, which feel however a long range interaction. In the second range the massless bosonic excitation is a negative norm state which can be consistently expunged from the ``physical'' Hilbert space; fermions are confined. An intriguing feature of our model occurs in the first range where we find that fermionic correlators scale at both short and long distances, but with different critical exponents. The infrared limit in the fermonic sector is nothing but a dynamically generated massless Thirring model.

Interpolative BTC image coding with vector quantization

The authors suggest two interpolative block truncation coding (BTC) image coding schemes with vector quantization and median filters as the interpolator. The first scheme is based on quincunx subsampling and the second one on every-other-row-and-every-other-column subsampling. It is shown that the schemes yield a significant reduction in bit rate at only a small performance degradation and, in general, better channel error resisting capabilities, as compared to the absolute moment BTC. The methods are further demonstrated to outperform the corresponding BTC schemes with pure vector quantization at the same bit rate and require minimal computations for the interpolation. >

High-resolution still picture compression

We shall consider the problem of storing, transmitting, and manipulating digital electronic images. Because of the file sizes involved, transmitting images will always consume large amounts of bandwidth, and storing images will always require hefty resources. Because of the large number N of pixels in a high-resolution image, manipulation of digital images is infeasible without low-complexity algorithms, i.e., O(N) or 0( N log(N) ) . Our goal is to describe some new methods which are firmly grounded in harmonic analysis and the mathematical theory of function spaces, which promise to combine effective image compression with low-complexity image processing. We shall take a broad perspective, but we shall also compare specific new algorithms to the state of the art. Roughly speaking, most image compression algorithms split into three parts: invertible transformation, lossy quantization or rank reduction, and entropy coding (or redundancy removal). There are a few algorithms which differ fundamentally from this scheme, e.g., the collage coding algorithm [ 41, or pure vector quantization of the pixels. The former uses a deep observation that pictures of natural objects exhibit self-similarity at different scales; we prefer to avoid relying on this phenomenon, since our images may not be “natural.” The latter uses a complex algorithm to build a superefficient empirical vocabulary to describe an ensemble of images; we prefer to avoid training our algorithm with any sample of images, to avoid the problem of producing a sufficiently large and suitable ensemble. There has emerged an international standard for picture compression, promulgated by the Joint Photo-

Pauli problem for a spin of arbitrary length: A simple method to determine its wave function.

The problem of determining a pure state vector from measurements is investigated for a quantum spin of arbitrary length. Generically, only a finite number of wave functions is compatible with the intensities of the spin components in two different spatial directions, measured by a Stern-Gerlach apparatus. The remaining ambiguity can be resolved by one additional well-defined measurement. This method combines efficiency with simplicity: only a small number of quantities have to be measured and the experimental setup is elementary. Other approaches to determine state vectors from measurements, also known as the ‘‘Pauli problem,’’ are reviewed for both spin and particle systems.

Remanent magnetism and ductile deformation in an experimentally deformed magnetite-bearing limestone

A limestone with pseudo-single-domain (PSD) pure magnetite is given an isothermal remanent magnetization (IRM). Samples are deformed triaxially at 200 MPa (2 kbar) confining pressure at room temperature and at a strain-rate of 10 −5 s −1. The limestone deforms in a ductile manner by twinning to produce sufficiently homogeneously strained specimens up to about 20% shortening. The uniform, saturation IRM rotates away from the shortening axis, approximately by an amount expected for the homogeneous strain of a non-material line marker. Hydrostatic compaction alone shows that this is time-dependent and compatible with progressive damage of the ferrimagnetic grains. Strain produces an increase in coercivity of the magnetite, an increase in its saturation remanence, and an increase in its anisotropy of magnetization (with respect to IRM). These observations are compatible with reduction in effective grain size and change of shape of magnetite. Experimental deformation reduces the intensity of magnetisation, chiefly by the removal of low-coercivity components of remanence when there is a pure IRM vector.

Correlation functions and the Goldstone picture for the hierarchical classical vector model at low temperatures in three or more dimensions

Low-temperature properties of the one-and two-point correlation functions are obtained for the pure state classical vector model in a hierarchical formulation. We consider theZ d lattice model (d⩾3) where the single-site spin variableφeR v has a density proportional to $$e^{ - \lambda (\phi ^2 - 1)^2 } $$ for largeλ⩽∞. We obtain the pure state one- and two-point functions by introducing a uniform magnetic field which goes to zero as the volume goes to infinity. Using renormalization group methods, we generate a sequence of effective actions and spin variable and determine the spontaneous magnetization (one-point function parallel to the field). We confirm the Goldstone picture by showing that the truncated two-point function has the canonical massless decay ∣x−y∣−(d−2) x,yeZd in the directions perpendicular to the field. We show a faster decay in the parallel direction and for larged that the decay is ∣x-y∣−(d+2).

The 2-μm plasmid as a nonselectable, stable, high copy number yeast vector

The endogenous 2-μm plasmid of Saccharomyces cerevisiae has been used extensively for the construction of yeast cloning and expression plasmids because it is a native yeast plasmid that is able to be maintained stably in cells at high copy number. Almost invariably, these plasmid constructs, containing some or all 2-μm sequences, exhibit copy number levels lower than 2-μm and are maintained stably only under selective conditions. We were interested in determining if there was a means by which 2-μm could be utilized for vector construction, without forfeiting either copy number or nonselective stability. We identified sites in the 2-μm plasmid that could be used for the insertion of genetic sequences without disrupting 2-μm coding elements and then assessed subsequent plasmid constructs for stability and copy number in vivo. We demonstrate the utility of a previously described 2-μm recombination chimera, pBH-2L, for the manipulation and transformation of 2-μm as a pure yeast plasmid vector. We show that the HpaI site near the STB element in the 2-μm plasmid can be utilized to clone yeast DNA of at least 3.9 kb with no loss of plasmid stability. Additionally, the copy number of these constructs is as high as levels reported for the endogenous 2-μm.

Removal of Chiral Anomalies in Abelian Gauge Theories

It is shown that chiral anomalies can be removed in abelian gauge theories. After a discussion of the two dimensional case where exact solutions are available we study the four dimensional case. We use perturbation theory, i.e. analyse the triangle Feynman integrals, and determine the general expression for the divergence of the gauge current. It includes the contribution from the triangle diagram with pure vector vertices. This is essential for our argumentation. Then we show that gauges exist for which current conservation holds and the anomaly vanishes. As far as the generating functional is concerned the anomaly is employed first as gauge fixing condition. After rewriting the interaction in a gauge invariant form the gauge fixing condition can be imposed as usual. In our approach the integration over the gauge group remains trivial. By an appropriate choice of the subtraction constant referring to the triangle diagram with pure vector vertices the anomalous contributions can be made to vanish in the final expressions. In this sense the anomaly is completely spurious and a consistent quantization should be possible.

The fifth force charge as a linear combination of baryonic, leptonic (OR B- L) and electric charges

We show how the gauge invariance of the Yukawa couplings responsible for quark and lepton masses restrict possible extra U(1) gauge symmetries, in a way which depends on the Higgs structure of the model considered. Quark family mixing generally requires the extra U(1) quark current to be generation-independent. In one-Higgs-doublet models the extra U(1) generator appears as a linear combination of B, L e, L μ , L τ with the weak hypercharge Y. After mixing with the Z boson the new neutral gauge boson U (massless or light) couples to a pure vector current, associated with the conserved charge Q 5= xB+( y e L e+ y μ L μ + y τ L τ )+ zQ; or, in grand-unified theories, with Q 5∼(B−L)− 4 5 cos 2θQ . No couplings proportional to strangeness, or strongly hyperchange Y s= B+ S, etc., can appear in this framework.

Use of ΦX174 as a shuttle vector for the study of in vivo mammalian mutagenesis

The most promising new techniques for the study of in vivo mammalian mutagenesis make use of transgenenic mice carrying a recoverable vector. Mutation systems in mammals can be based on the selection of altered phenotypes among cells sampled from the whole animal, but they are then limited to the very few cell types in which the marker gene is expressed. Such systems require both in vivo and in vitro cell proliferation for expression and verification of the mutations. To avoid these complications, the study of mutations in most tissues must be based on the detection of genetic alterations in a vector that is independent of the phenotype of the mammalian cell. The vector is only a small portion of the mammalian genome, and may of the procedures for recovering the vector are inhibited by the host DNA. For this reason, partial purification is necessary. The purification is made possible by using vectors which are not cut by restriction enzymes that cut the host DNA to pieces of an average size considerably smaller than the vector. The efficiency for measuring mutation frequencies depends on the number of vectors which can be recovered from a certain amount of DNA and is affected by the number of vectors per mammalian genome and the transfection efficiency of the paritally-purified vector. In order to avoid selection against or for the spontaneous or induced mutations, the transfection efficiency of the vector from the transformed DNA and of the pure vector DNA should be of the same order of magnitude. Differences in the response to mutagens between the mammalian genome and the procaryotic vector may be expected due to the lack of unique mammalian topographical features in the vectors. Any mutation induction which depends preferentially on these unique features of the mammalian genome may not be detected in a shuttle vector system unless the vector has been engineered or specifically designed to include such topographical characters. The shortcoming of short-term tests that use mutagenicity for predicting human carcinogenicity is usually lack of correlation between mutagenesis in the short-term tests and the corresponding results in carcinogenesis bioassays in mammals. One factor which could contribute to the lack of correlation between the short-term test systems and the bioassays is that we are comparing mutations in totally different genes in different organisms. By using the ΦX174 shuttle system, one of the variables may be eliminated. In this system, we can compare mutation rates between different stages of the same target DNA ranging from in vivo in transgenic mice to naked single-stranded DNA. In other words, it may provide the opportunity to study how various organisms respond to the same initial mutagenic damage on a constant target. In order to mimic in vivo mammalian metabolism, liver microsomes are used in many in vitro tests for mutagenicity. In reality, there is no possible way to simulate the complex activation, detoxification and repair systems that occur in vivo. By using a shuttle vector system such as ΦX174 we can hope to elucidate the influence of these factors on mutagenesis. Using these systems, the mutation frequency and the cancer rate can be compared for the same tissue in the same strains of animals. This comparison may bring us closer to understanding the role of mutations in the development of cancer. Only 20–30 compounds have been tested for the induction of transmissible mutations in mammalian germinal tissue, and most of these compounds are strong alkylating agents (Ray et al., 1987). A shuttle vector system based on the detection of mutations in DNA from sperm of exposed animals may provide the method needed for expanding the data base on mammalian germ-cell mutagenesis. Unfortunately, due to the limited amount of DNA available from the female germinal tissue, none of the shuttle vector systems currently envisioned can be applied to enhance the study of mutagenesis in female germinal tissue. The mitotic indices of many mammalian tissues are very low or essentially zero. This is especially true of neurological tissue. It is reasonable to assume that DNA damage occurs in such tissues, is repaired and somtimes misrepaired, and that results in mutations. In order to study mutations in nonmitotic tissue, a shuttle vector system must be designed in such a way that the mutation frequency is determined directly among the DNA molecules isolated from the tissue and that mutation detection does not require expression of the mutant phenotype in mammalian cells in vivo. The ability to determine mutation frequencies in nonmitotic tissues such as the brain may promote a better understanding of the causative events in age-related degenerative diseases of the central nervous system.

Scale invariance ofgA/gVin quark-confining potentials

It is demonstrated that the spin distribution in the nucleon surface determines the value of ${g}_{A}$/${g}_{V}$. This ratio is shown to be scale invariant; it is sensitive to the surface thickness and to the type of quark confinement (Dirac-scalar or -vector) and vanishes for pure vector confinement. A phase transition is found from confinement to deconfinement when the ratio of vector to scalar confinement falls below a critical value (-1.0). Experiments to probe a Dirac-vector component in the (free or bound) nucleon are proposed in the light of the CPT theorem.

1(--)-->0(-+) meson radiative and pionic transitions and mass splittings.

Radiative and pionic transitions between the ground-state pure qq-bar vector and pseudoscalar mesons compatible with observed mass splittings are studied.

The Level Crossing of P States and Lorentz Property of Potential

We analyzed recently discovered level ordering of P states which are different in heavy and light quarkonia. Its implication in Lorentz property of the potential is also studied. It is confirmed that pure vector potential cannot explain the inversion of 11P1 and 13P1 levels, and mixing of scalar potential seems to be necessary, which has been suggested before by the analysis of the fine structure of the heavy quarkonium.

Phase factors, point-splitting regularisation and chiral anomalies

A method is proposed to construct the path-independent form of phase factors pertaining to non-abelian gauge theories. It is found that the original form of the phase factor, as envisaged by Schwinger, is reproduced for a straight path. As an illustration of its use this work is applied, within the framework of point-splitting regularisation, to obtain the familiar axial anomaly in a pure vector gauge theory. Subtleties associated with the treatment of the vector gauge current are also discussed. Finally, the scheme of computations is employed to derive the covariant and consistent anomalies in a non-abelian chiral gauge theory in arbitrary even dimensions.

New algorithm and FORTRAN module to carry out the four-index transformation of atomic and molecular physics wholly in central memory

Abstract This is the first of three companion papers describing a complete and modular library to carry out the four-index transformation of a block [( pq/mrs )] of two-electron integrals involving symmetry-adapted primitive orbitals p, q, r, s and a symmetry-related index m into a block [( ij/klm )] of integrals over symmetry-adapted orthonormal (orbitals i, j, k, l . The index m allows for the unified treatment of atomic and molecular, relativistic and nonrelativistic calculations. A new algorithm based on a generalization of a method by Saunders & van Lenthe [ Mol. Phys. 48, 923 (1983)] for non-symmetry orbitals has been developed. It is here implemented by means of a FORTRAN code, controlled by subroutine C4ITD, requiring all computed quantities to be held in central memory. A non-redundant set of integrals is used throughout. All pertinent sums run only over a limited range determined by a given symmetry. The rate determining steps may be carried out in parallel and are vectorizable within each possible concurrent processor. For 20 non-symmetry orbitals and with 64-bit precision on a VAX-11/780 computer, using a working set of 200 kbytes, subroutine C4ITD takes 48 CPU s. Ninety percent of this time is spent in steps dominated by vector-scalar-multiply-and-add (VSMA) operations carried out at 0.170 mega floating point operations per second, which is 91% of the performance achieved on the same computer by an equivalent mix of pure VSMA operations and vector sizes. C4ITD will be useful in atomic and molecular electronic structure calculations beyond Hartree-Fock.

Accelerating Vector Iteration Methods

This paper describes a technique for accelerating the convergence properties of iterative methods for the solution of large sparse symmetric linear systems that arise from the application of finite element method. The technique is called partial preconditioning process (PPR) and can be combined with pure vector iteration methods, such as the conjugate gradient, the dynamic relaxation, and the Chebyshev semi-iterative methods. The proposed triangular splitting preconditioner combines Evans’ SSOR preconditioner with a drop-off tolerance criterion. The (PPR) is attractive in a FE framework because it is simple and can be implemented at the element level as opposed to incomplete Cholesky preconditioners, which require a sparse assembly. The method, despite its simplicity, is shown to be more efficient on a set of test problems for certain values of the drop-off tolerance parameter than the partial elimination method.