The pentaquark in K-plus-d total cross section data

An analysis of $K^+$-d total cross section data is undertaken to explore possible effects of the recently observed resonance in the S=+1 hadronic system with mass around 1.55 GeV. It is found that a structure corresponding to the resonance is visible in the data. The width consistent with the observed deviation from background is found to be $0.9\pm 0.3$ MeV and the mass is $1.559\pm 0.003$ GeV/c$^2$ for spin-parity \h^+ and $1.547\pm0.002$\ GeV/c$^2$ for \h^-. The errors are one standard deviation and statistical only. \Comment: 10 pages, 5 figures Replaced to correct references, add and correct text. No change in content. More discussion of errors, increased error on width, corrected one figur

Monte Carlo simulation of baryon and lepton number violating processes at high energies

We report results obtained with the first complete event generator for electroweak baryon and lepton number violating interactions at supercolliders. We find that baryon number violation would be very difficult to establish, but lepton number violation can be seen provided at least a few hundred L violating events are available with good electron or muon identification in the energy range 10 GeV to 1 TeV.Comment: 40 Pages uuencoded LaTeX (20 PostScript figures included), Cavendish-HEP-93/6, CERN-TH.7090/9

Origin and evolution of the Amazonian craton

The Amazonian craton appears to be formed and modifed by processes much like those of the better-known Precambrian cratons, but the major events did not always follow conventional sequences nor did they occur synchronously with those of other cratons. Much of the craton's Archean style continental crust formation, recorded in granite-greenstone and high-grade terranes, occurred in the Early Proterozoic: a period of relative quiescence in many other Precambrian regions. The common Archean to Proterozoic transition in geological style did not occur here, but an analogous change from abundant marine volcanism to dominantly continental sedimentary and eruptive styles occurred later. Amazonian geology is summarized, explaining the evolution of the craton

An intermediate state between the kagome-ice and the fully polarized state in Dy2_2Ti2_2O7_7

Dy$_2$Ti$_2$O$_7$ is at present the cleanest example of a spin-ice material. Previous theoretical and experimental work on the first-order transition between the kagome-ice and the fully polarized state has been taken as a validation for the dipolar spin-ice model. Here we investigate in further depth this phase transition using ac-susceptibility and dc-magnetization, and compare this results with Monte-Carlo simulations and previous magnetization and specific heat measurements. We find signatures of an intermediate state between the kagome-ice and full polarization. This signatures are absent in current theoretical models used to describe spin-ice materials.Comment: 7 pages, 4 figure

Pulping characteristics of Pinus oocarpa grown on Mountain Pine Ridge, Belize

A single sample of Pinus oocarpa from Mountain Pine Ridge, Belize was pulped by the sulphate process. The results of pulping and pulp evaluation, together with chemical analysis of the wood and fibre dimensions are reported. The sample consisted of twenty trees selected at random from a naturally regenerating forest. The average age of the trees was estimated as 30 years with a range of 20 to 46 years. Chemical analysis showed the wood to have an a-cellulose content of 48.9% and a lignin content of 28.7%. The fibres were 3.13 mm long, 49.8 micrometres wide and had walls 6.9 micrometres thick. Pulping by the sulphate process yielded between 38% and 44% of unbleached pulp. These yields were lower than usually found in pines. The pulp had strength characteristics generally similar to those of pulps from Southern Pines of the USA. Compared with pulps obtained from P. caribaea growing in the same area, it was found that P. oocarpa gave lower yields of marginally better pulps

Pulping characteristics of three trees of Pinus caribaea with different densities grown in Jamaica

The pulping characteristics of three trees of Pinus caribaea var hondurensis with different densities grown in Jamaica were determined using the sulphate method. Ten trees, ten years old, had been selected at random from a single plantation in Jamaica and the first, fifth and ninth in order of density were pulped to assess the differences in pulping characteristics that might be due to density. Two digestions, one with 17.5% active alkali, one with 20% were made on each tree using otherwise identical conditions. At both alkali doses yields of pulp increased with increasing density of the wood and, unexpectedly, the Kappa numbers of the pulps from the medium density wood were higher than those of either of the others. The breaking lengths and bursting strengths decreased and the bulk increased with increasing density. When compared at equal digestion conditions, the tearing strengths increased but to a peak with medium density. This was influenced by the higher Kappa numbers of the pulps from medium density wood and, when compared at equal Kappa numbers, the tearing strength showed a marked increase as the wood density increased from low to medium, and a smaller increase as it increased from medium to high density. The same trends held in the case of bleached pulps. Because of the limited scale of this trial and the fact that the medium density sample yielded pulps with Kappa numbers completely out of line with the pulps from the other two samples, it is not possible to draw firm conclusions about the relationship between density and pulping characteristics, or the merit of density for predicting the quality of pulp. However, in this and in earlier similar work (Tropical Products Institute Report L25) it appears that low density trees can have the economic disadvantage of not only higher handling costs but also lower pulp yields per bone dry ton, and the technical disadvantage of giving the lowest tearing strength although with somewhat higher bonding strengths. The choice between medium and highest density is obscure. The conclusion might be different with trees at a different age and site conditions because both these affect the general level of pulp strength and they also affect the relationship between bonding and tearing strength

Optical bistability involving planar metamaterial with broken structural symmetry

We report on a bistable light transmission through a planar metamaterial composed of a metal pattern of weakly asymmetric elements placed on a nonlinear substrate. Such structure bears the Fano-like sharp resonance response of a trapped-mode excitation. The feedback required for bistability is provided by the coupling between the strong antiphased trapped-mode-resonance currents excited on the metal elements and the intensity of inner field in the nonlinear substrate.Comment: 4 pages, 4 figure

Pulping characteristics of Eucalyptus saligna/grandis growing in Uganda

Three samples of Eucalyptus saligna/grandis grown in Uganda were examined to determine wood density, chemical composition, fibre dimensions, and pulping characteristics by the sulphate process. The samples were of 9-year-old trees and 17-year-old trees from the Kajansi Forest Reserve, and 11-year-old trees from Nagojje Forest Reserve. The differences in wood density, chemical composition.and fibre dimensions were small and unlikely to be significant in commerical production, but there were indications that both age of sample and growing conditions affect wood density, fibre dimensions and the strength characteristics of pulp. All three samples when pulped by the sulphate process yielded more than 50% of a bleachable pulp with good strength characteristics. Pulp from the 9-year-old sample from Kajansi had the highest bonding strength; that from the 17-year-old sample from Kajansi the highest tearing strength; that from the 11-year-old sample from Nagojje was weakest in all respects. The pulps could be bleached by a four-stage process of successive applications of chlorine, sodium hydroxide, sodium hypochlorite and chlorine dioxide to yield pulps with satisfactory brightness (86, Mg0=1 00) and with strength properties only a little lower than those of unbleached pulps

Elastic Scattering of Pions From the Three-nucleon System

We examine the scattering of charged pions from the trinucleon system at a pion energy of 180 MeV. The motivation for this study is the structure seen in the experimental angular distribution of back-angle scattering for pi+ 3He and pi- 3H but for neither pi- 3He nor pi+ 3H. We consider the addition of a double spin flip term to an optical model treatment and find that, though the contribution of this term is non-negligible at large angles for pi+ 3He and pi- 3H, it does not reproduce the structure seen in the experiment.Comment: 15 pages + 5 figure

Convex Functions and Spacetime Geometry

Convexity and convex functions play an important role in theoretical physics. To initiate a study of the possible uses of convex functions in General Relativity, we discuss the consequences of a spacetime $(M,g_{\mu \nu})$ or an initial data set $(\Sigma, h_{ij}, K_{ij})$ admitting a suitably defined convex function. We show how the existence of a convex function on a spacetime places restrictions on the properties of the spacetime geometry.Comment: 26 pages, latex, 7 figures, improved version. some claims removed, references adde