The crystal structure of rathite-I

Die Kristallstruktur von Rathit-I wurde mittels dreidimensionaler Intensitätsdaten bestimmt. Vier Formeleinheiten (Pb,Tl)3As4(As,Ag)S10 sind in der Einheitszelle der Symmetrie Ρ 21/a mit a = 25,16 Å, 6 = 7,94 Å, c = 8,47 Å, β = 100° 28' enthalten. Die wahre Symmetrie von Rathit-I ist möglicherweise triklin. Die Lösung lieferten die Ähnlichkeit der Struktur mit derjenigen von Rathit-III und spezielle Verhältnisse der Röntgendiagramme. Von drei unabhängigen Pb(Tl)-Atomen sind zwei von neun S-Atomen umgeben, das andere von sieben. Die As-Atome weisen trigonal-pyramidale Koordination durch die S-Atome auf. Von einem As-Atom wird angenommen, daß es statistisch von zwei verschiedenen trigonal -pyramidalen S-Koordinationen umgeben wird. Ein anderes As-Atom ist teilweise durch Ag ersetzt. Die Struktur besteht aus zweierlei Schichten parallel zu (100). Die erste Art hat die Zusammensetzung (Pb,Tl)S3 und besteht aus den Koordinationspolyedern um die Pb(Tl)-Atome mit Neuner-Koordination. Die zweite Art ist aus Pb(Tl)-, As(Ag)- und S-Atomen zusammengesetzt, welche ein deformiertes PbS-Gitter bilden. Trigonale As-S3-Pyramiden sind zu Ketten endlicher Länge vereinig

A study of nuclei of astrophysical interest in the continuum shell model

We present here the first application of realistic shell model (SM) including coupling between many-particle (quasi-)bound states and the continuum of one-particle scattering states to the spectroscopy of 8B and to the calculation of astrophysical factors in the reaction 7Be(p,gamma)8B.Comment: 9 pages incl. 3 figures, LaTeX with iopart class and epsf. Invited talk at the Int. Workshop on Physics with Radioactive Nuclear Beams, Jan. 12-17, 1998, Puri, India. Shortened version will be published in proceedings to apear as a separate J. Phys. G volum

The method of fundamental solutions for problems in static thermo-elasticity with incomplete boundary data

An inverse problem in static thermo-elasticity is investigated. The aim is to reconstruct the unspecified boundary data, as well as the temperature and displacement inside a body from over-specified boundary data measured on an accessible portion of its boundary. The problem is linear but ill-posed. The uniqueness of the solution is established but the continuous dependence on the input data is violated. In order to reconstruct a stable and accurate solution, the method of fundamental solutions is combined with Tikhonov regularization where the regularization parameter is selected based on the L-curve criterion. Numerical results are presented in both two and three dimensions showing the feasibility and ease of implementation of the proposed technique

35. How often medical literature may be a source of incorrect clinical decision?

Change in clinical practice results mainly from positive randomized trials (superiority of tested method confirmed by significant result of statistical test). However, the rate of false positive trials might be high among all positive trials – even 30%–50%. This percentage depends mainly on the rate of trials with a real difference in efficacy between tested methods; in lesser extend it depends on a level of type II error (a number of patients in a trial). The probable high rate of false positive trials among all positive trials indicates that a risk of undertaking of incorrect clinical decision based on literature may be also high. In addition, this risk is increased due to publication bias. Therefore, confirmatory trials are often necessary. The other issue, which might be a source of incorrect clinical decision, is lack of data enabling an assessment of generalizability of trial results: 1. a number of eligible but not enrolled patients and the reasons for treatment outside trial; 2. a comparison of a characteristic of patients on trial with a characteristic of eligible, but not enrolled patients; 3. a comparison of results of treatment of patients on trial with results of treatment of eligible, but not enrolled patients 4. data of referral pattern and information on the source population, from which patients were selected

A collaborative platform for integrating and optimising Computational Fluid Dynamics analysis requests

A Virtual Integration Platform (VIP) is described which provides support for the integration of Computer-Aided Design (CAD) and Computational Fluid Dynamics (CFD) analysis tools into an environment that supports the use of these tools in a distributed collaborative manner. The VIP has evolved through previous EU research conducted within the VRShips-ROPAX 2000 (VRShips) project and the current version discussed here was developed predominantly within the VIRTUE project but also within the SAFEDOR project. The VIP is described with respect to the support it provides to designers and analysts in coordinating and optimising CFD analysis requests. Two case studies are provided that illustrate the application of the VIP within HSVA: the use of a panel code for the evaluation of geometry variations in order to improve propeller efficiency; and, the use of a dedicated maritime RANS code (FreSCo) to improve the wake distribution for the VIRTUE tanker. A discussion is included detailing the background, application and results from the use of the VIP within these two case studies as well as how the platform was of benefit during the development and a consideration of how it can benefit HSVA in the future

Canonical form of Hamiltonian matrices

On the basis of shell model simulations, it is conjectured that the Lanczos construction at fixed quantum numbers defines---within fluctuations and behaviour very near the origin---smooth canonical matrices whose forms depend on the rank of the Hamiltonian, dimensionality of the vector space, and second and third moments. A framework emerges that amounts to a general Anderson model capable of dealing with ground state properties and strength functions. The smooth forms imply binomial level densities. A simplified approach to canonical thermodynamics is proposed.Comment: 4 pages 6 figure

Dynamics of thermoelastic thin plates: A comparison of four theories

Four distinct theories describing the flexural motion of thermoelastic thin plates are compared. The theories are due to Chadwick, Lagnese and Lions, Simmonds, and Norris. Chadwick's theory requires a 3D spatial equation for the temperature but is considered the most accurate as the others are derivable from it by different approximations. Attention is given to the damping of flexural waves. Analytical and quantitative comparisons indicate that the Lagnese and Lions model with a 2D temperature equation captures the essential features of the thermoelastic damping, but contains systematic inaccuracies. These are attributable to the approximation for the first moment of the temperature used in deriving the Lagnese and Lions equation. Simmonds' model with an explicit formula for temperature in terms of plate deflection is the simplest of all but is accurate only at low frequency, where the damping is linearly proportional to the frequency. It is shown that the Norris model, which is almost as simple as Simmond's, is as accurate as the more precise but involved theory of Chadwick.Comment: 2 figures, 1 tabl