Discrete Nodal Domain Theorems

We give a detailed proof for two discrete analogues of Courant's Nodal Domain Theorem

Metastable States in High Order Short-Range Spin Glasses

The mean number of metastable states in higher order short-range spin glasses is estimated analytically using a variational method introduced by Tanaka and Edwards for very large coordination numbers. For lattices with small connectivities, numerical simulations do not show any significant dependence on the relative positions of the interacting spins on the lattice, indicating thus that these systems can be described by a few macroscopic parameters. As an extremely anisotropic model we consider the low autocorrelated binary spin model and we show through numerical simulations that its landscape has an exceptionally large number of local optima

Qualification model spacecraft tests for DEMP, SGEMP, and ESD effects

The development of a satellite design demonstration test program is described. The test approach is comprehensive in that it includes the effects from electrostatic discharge (ESD), system generated electromagnetic pulse (SGEMP), as well as dispersed electromagnetic pulses (DEMP). The comprehensive test concept is based on the similarity of the satellite's response to several environments

Covariant spectator theory of np scattering: Phase shifts obtained from precision fits to data below 350 MeV

Using the covariant spectator theory (CST), we present two one boson exchange kernels that have been successfully adjusted to fit the 2007 world np data (containing 3788 data) below 350 MeV. One model (which we designate WJC-1) has 27 parameters and fits with a chi2/N = 1.06. The other model (designated WJC-2) has only 15 parameters and fits with a chi2/N = 1.12. Both of these models also reproduce the experimental triton binding energy without introducing additional irreducible three-nucleon forces. One result of this work is a new phase shift analysis, updated for all data until 2006, which is useful even if one does not work within the CST. In carrying out these fits we have reviewed the entire data base, adding new data not previously used in other high precision fits and restoring some data omitted in previous fits. A full discussion and evaluation of the 2007 data base is presented.Comment: 43 pages, 27 figures, and 13 table

Application of the Covariant Spectator Theory to the study of heavy and heavy-light mesons

As an application of the Covariant Spectator Theory (CST) we calculate the spectrum of heavy-light and heavy-heavy mesons using covariant versions of a linear confining potential, a one- gluon exchange, and a constant interaction. The CST equations possess the correct one-body limit and are therefore well-suited to describe mesons in which one quark is much heavier than the other. We find a good fit to the mass spectrum of heavy-light and heavy-heavy mesons with just three parameters (apart from the quark masses). Remarkably, the fit parameters are nearly unchanged when we fit to experimental pseudoscalar states only or to the whole spectrum. Because pseudoscalar states are insensitive to spin-orbit interactions and do not determine spin-spin interactions separately from central interactions, this result suggests that it is the covariance of the kernel that correctly predicts the spin-dependent quark-antiquark interaction

A covariant constituent-quark formalism for mesons

Using the framework of the Covariant Spectator Theory (CST) [1] we are developing a covariant model formulated in Minkowski space to study mesonic structure and spectra. Treating mesons as effective $q\bar{q}$ states, we focused in [2] on the nonrelativistic bound-state problem in momentum space with a linear confining potential. Although integrable, this kernel has singularities which are difficult to handle numerically. In [2] we reformulate it into a form in which all singularities are explicitely removed. The resulting equations are then easier to solve and yield accurate and stable solutions. In the present work, the same method is applied to the relativistic case, improving upon the results of the one-channel spectator equation (1CSE) given in [3].Comment: 6 pages, 5 figures, Presented at EEF70, Workshop on Unquenched Hadron Spectroscopy: Non-Perturbative Models and Methods of QCD vs. Experimen

Relativistic phenomenology of meson spectra with a covariant quark model in Minkowski space

In this work, we perform a covariant treatment of quark-antiquark systems. We calculate the spectra and wave functions using a formalism based on the Covariant Spectator Theory (CST). Our results not only reproduce very well the experimental data with a very small set of global parameters, but they also allow a direct test of the predictive power of covariant kernels

Protection of personal information Act No. 4 of 2013: Implications for biobanks

The Protection of Personal Information Act (POPIA) No. 4 of 2013 is the first comprehensive data-protection regulation to be passed in South Africa (SA). Its objectives include giving effect to the constitutional right to privacy by regulating the way in which personal information must be processed, balancing the right to privacy against other rights, and establishing an Information Regulator to ensure that the rights protected by POPIA are respected. POPIA will have an impact on health research, including biobanks. As sharing of samples and data is a central feature of biobanks, POPIA could change the way in which data are obtained, shared and exported. In particular, the provisions regarding data minimisation, requirements pertaining to the transfer of data abroad, consent provisions and identification of the 'responsible person' will impact the operation of biobanks in SA. With POPIA soon to come into force, it is now time to consider its implications for biobanks in SA

Mind the Gap? : An Intensive Longitudinal Study of Between-Person and Within-Person Intention-Behavior Relations

Acknowledgments This work was supported by the University of Konstanz, Germany. The first author was supported by a fellowship of the Swiss National Science Foundation (Fellowship P2ZHP1_155103).Peer reviewedPostprin

Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory

We propose a model for the quark-antiquark interaction in Minkowski space using the Covariant Spectator Theory. We show that with an equal-weighted scalar-pseudoscalar structure for the confining part of our interaction kernel the axial-vector Ward-Takahashi identity is preserved and our model complies with the Adler-zero constraint for pi-pi-scattering imposed by chiral symmetry.Comment: 4 pages, 2 figures; 21st International Conference on Few-Body Problems in Physics, May 18 - 22, 2015, Chicago, US