Sökresultat

A variational approach, based on a discrete representation of the chain, is used to calculate free energy and conformational properties in polyelectrolytes. The true bond and Coulomb potentials are approximated by a trial isotropic harmonic energy containing force constants between all monomer-pairs as variational parameters. By a judicious choice of representation and the use of incremental matri

A deterministic algorithm for calculating polymer properties is presented. It is based on a variational approach where the bond and Coulomb potentials are approximated by a quadratic trial energy. The parameters which describe average atom positions and Gaussian fluctuations, are the solutions of matrix equations. By a judicious choice of parameter representations and the use of incremental matrix

A recently suggested geometrical embedding of Bethe-type lattices (branched polymers) in the hyperbolic plane [R. Mosseri and J. F. Sadoc, J. Phys. Lett. 43, L249 (1982); J. A. de Miranda-Neto and F. Moraes, J. Phys. I. France 2, 1657 (1992)] is shown to be only a special case of a whole continuum of possible realizations that preserve some of the symmetries of the Bethe lattice. The properties of

The Apollonian tiling of the plane into circles is analyzed with respect to its group properties. The relevant group, which is noncompact and discrete, is found to be identical to the symmetry group of a particular geometric tree graph in hyperbolic three-space. A linear recursive method to compute the radii is obtained. Certain modifications of the problem are investigated, and relations to other

We use the cooling method and the lattice approximation to study the form and properties of the minimum action configurations for the SU(2) Yang-Mills theory on a space-time torous with twist k=m=(1, 1, 1).

We analyze the finite size effects for the source method in pure lattice gauge theory at weak coupling. They are found to be strongly suppressed by twisting the boundary conditions, for SU(3) by typically an order of magnitude.

We compute the energy levels of an SU(2) Yang-Mills field in perturbation theory to order g2, for a box of finite size and symmetric twist m=(1, 1, 1). A cubic-invariant spectrum results, with almost degenerate E++ and T2 ++ levels. Various suggestions for further MC measurements are made.

A construction that relates circle maps of mutually reciprocal winding number, belonging to the same criticality class, is presented. It is explicitly invariant under smooth conjugations of either map, and displays a series of remarkable properties, in spite of its simplicity.

We discuss the Langevin equation for a complex Boltzmann distribution, allowing for modifications of the process. The relation between the two different time development operators involved is analyzed, with emphasis on their spectra.

In this paper the Poisson bracket algebra for the open massless relativistic string in the one-space-and one-time-dimensional case is considered. In order to characterize the orbit of the system the directrix function, i.e., the orbit of one of the endpoints of the string, is used. It turns out that the Poisson bracket algebra is of a very simple form in terms of the parameters of the directrix fu

We present a general condition on quark fragmentation which gives a hadron distribution satisfying Lorentz invariance and causality. The hadronization can be described as an iterative cascade process, symmetric with respect to iteration from the quark and the antiquark ends. The possible particle distributions are strongly restricted, with few free parameters related to the total multiplicity and

The aim of this study was to investigate the gut microbiota in preschool children with and without overweight and obesity. Twenty overweight or obese children and twenty children with body mass index within the normal range (age: 4-5 years) were recruited from the south of Sweden. The gut microbiota was accessed by quantitative polymerase chain reactions and terminal restriction fragment length po

Ulcerative colitis (UC) is characterized bychronic inflammation of the colonic mucosa. Administrationof dextran sulfate sodium (DSS) to animals is a frequentlyused model to mimic human colitis. Deregulationof the immune response to the enteric microflora orpathogens as well as increased intestinal permeability havebeen proposed as disease-driving mechanisms. To enlargethe understanding of the path

The diffusion of new three-dimensional (3D) visualization platforms together with the development of new tools for query and analysis of 3D information has provided archaeologists with the opportunity to define new investigation strategies based on the use of 3D geo-referenced libraries to simulate and interpret, at the trowel's edge, evidence and finds retrieved during the excavation. Employing a

Partially premixed combustion (PPC) is a low temperature, direct-injection combustion concept that has shown to give promising emission levels and efficiencies over a wide operating range. In this concept, high EGR ratios, high octane-number fuels and early injection timings are used to slow down the auto-ignition reactions and to enhance the fuel and are mixing before the start of combustion. A d

Reducing the prevalence of mastitis caused by Staphylococcus aureus (S. aureus) is essential to improve animal health and reduce economic losses for farmers. The clinical outcome of acute mastitis and risk of progression to persistent mastitis can, at least to some extent, be related to genetic variants of the strain causing the infection. In the present study we have used microarrays to investiga

Solar influences on climate variability are one of the most controversially discussed topics in climate research. We analyze solar forcing of flood frequency in central Europe during spring and summer on interannual to multi-centennial timescales, integrating daily discharge data of the River Ammer (southern Germany) back to AD1926 (∼solar cycles 16-23) and the 5500-year flood layer record from va

CD44 is a cell surface adhesion molecule and its principal ligand is hyaluronic acid (HA), a key component of the brain’s extracellular matrix. CD44 levels are decreased in the cerebrospinal fluid (CSF) of depressed individuals, and the CD44 gene has been identified in genome wide association study as a possible risk gene in suicidal behavior. In order to define the pathobiological mechanisms by w

Object: To present population-based and age related incidence of surgery and clinical outcome for adult patients operated for hydrocephalus, registered in the Swedish Hydrocephalus Quality Registry (SHQR). Methods: All patients registered in SHQR during 2004–2011 were included. Data on age, gender, type of hydrocephalus and type of surgery were extracted as well as three months outcome for patient