Baryon production in the string fragmentation picture

An improved version of the “pop-corn” model for baryon production in quark and gluon jets is presented. With a reduced number of parameters the model reproduces well both production rates for different baryon species and baryon momentum distributions. Predictions are presented for a set of baryon-antibaryon correlations.     

Untersuchung von Mehl- und Backwaren

Ohne Zusammenfassung     

Well‐Defined Palladium Nanoparticles Supported on Siliceous Mesocellular Foam as Heterogeneous Catalysts for the Oxidation of Water

Herein, we describe the use of Pd nanoparticles immobilized on an amino‐functionalized siliceous mesocellular foam for the catalytic oxidation of H₂O. The Pd nanocatalyst proved to be capable of mediating the four‐electron oxidation of H₂O to O₂, both chemically and photochemically. The Pd nanocatalyst is easy to prepare and shows high chemical stability, low leaching, and recyclability. Together with its promising catalytic activity, these features make the Pd nanocatalyst of potential interest for future sustainable solar‐fuel production.     

Composite risers for deep-water offshore technology: Problems and prospects. 1. Metal-composite riser

Prospects for the application of advanced composites in the offshore technology of oil production are considered. The use of composites in vertical pipelines-risers seems to be the most efficient. The operating loads are studied and the attendant problems are formulated. A comparative analysis of the characteristics of metal, composite, and metal-composite deep-water risers is presented. A technique is developed for designing multilayered risers, taking into account the action of internal and external pressures, gravity, and the axial tensile force created by tensioners, as well as the residual technological stresses due to the difference in coefficients of thermal expansion, physical-chemical shrinkage, and force winding. Numerical estimations are given for a two-layered riser with an inner metal layer of steel, titanium, or aluminum alloys and a composite layer of glass- or carbon-fiber plastics formed by circumferential winding. It is shown that the technological stresses substantially affect the characteristics of the riser.Institute of Polymer Mechanics, Latvian Academy of Sciences, Riga, LV-1006, Latvia. Trondheim Technical University, Norway. Translated from Mekhanika Kompozitnykh Materialov, Vol. 33, No. 5, pp. 577–591, September–October, 1997.     

A microscopic description of inelastic 12C scattering from 208Pb

Heavy-ion inelastic scattering is described microscopically by using an effective nucleon-nucleon interaction and RPA hole-particle wave functions. The relative cross sections for different multipoles can be sensitive to the range of the interaction. The strength is determined by fitting elastic scattering. The model is used to analyze 98 MeV ¹²C ions exciting ²⁰⁸Pb. The range required is shorter than that for the bare interaction between nucleons. Collective model fits are also presented for comparison.     

Stable convergence acceleration using Laplace transforms

Summary We consider the general class of power series where the terms may be expressed as the Laplace transforms of known functions. The sum of the series can then be evaluated efficiently and accurately by means of quadrature schemes, recently published by Frank Stenger. The method works also far outside the region of convergence as will be illustrated by numerical examples.Dedicated to Professor Lothar Collatz on the occasion of his 75th birthday     

A quark parton model for hadronic fragmentation distributions

The one-particle inclusive distributions in the fragmentation regions in hadronic interactions are described in a parameter free way by a simple additative quark parton model by means of the quark fragmentation functions measured in leptoproduction. We interpret the result so that while the main interaction in hadronic collisions is due to the wee partons almost all the momenta is carried by one of the valence quarks yielding fragmentation region distributions similar to the ones in leptoproduction.     

A general model for jet fragmentation

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 corelations in rapidity. These parameters can be given an appealing interpretation in terms of the expected area and perimeter dependence of Wilson loop integrals.