The complex relation between production and scattering amplitudes

The unitarity relation, Im(A)=T* A, is derived for a three-body production amplitude, A, that consists of a complex linear combination of elements of the two-body scattering amplitude, T. We conclude that the unitarity relation does not impose a realness condition on the coefficients in the expansion of, A, in terms of, T.Comment: 4 pages plain LaTe

Transdifferentiation of blood-derived human adult endothelial progenitor cells into functionally active cardiomyocytes

Background - Further to promoting angiogenesis, cell therapy may be an approach for cardiac regeneration. Recent studies suggest that progenitor cells can transdifferentiate into other lineages. However, the transdifferentiation potential of endothelial progenitor cells (EPCs) is unknown

Persistence at the onset of spatiotemporal intermittency in coupled map lattices

We study persistence in coupled circle map lattices at the onset of spatiotemporal intermittency, an onset which marks a continuous transition, in the universality class of directed percolation, to a unique absorbing state. We obtain a local persistence exponent of theta_l = 1.49 +- 0.02 at this transition, a value which closely matches values for theta_l obtained in stochastic models of directed percolation. This result constitutes suggestive evidence for the universality of persistence exponents at the directed percolation transition. Given that many experimental systems are modelled accurately by coupled map lattices, experimental measurements of this persistence exponent may be feasible.Comment: 7 pages, Latex, 6 Postscript figures, Europhysics Letters (to appear

Relativistic three-particle scattering equations

We derive a set of relativistic three-particle scattering equations in the three-particle c.m. frame employing a relativistic three-particle propagator suggested long ago by Ahmadzadeh and Tjon in the c.m. frame of a two-particle subsystem. We make the coordinate transformation of this propagator from the c.m. frame of the two-particle subsystem to the three-particle c.m. frame. We also point out that some numerical applications of the Ahmadzadeh and Tjon propagator to the three-nucleon problem use unnecessary nonrelativistic approximations which do not simplify the computational task, but violate constraints of relativistic unitarity and/or covariance.Comment: 5pages, text and one ps figure (in revtex) include

Differentiating between hospitals according to the “maturity” of quality improvement systems: a new classification scheme in a sample of European hospitals

Aim: This study, part of the Methods of Assessing Response to Quality Improvement Strategies (MARQuIS) research project focusing on cross-border patients in Europe, investigated quality policies and improvement in healthcare systems across the European Union (EU). The aim was to develop a classification scheme for the level of quality improvement (maturity) in EU hospitals, in order to evaluate hospitals according to the maturity of their quality improvement activities. Methods: A web-based questionnaire survey designed to measure quality improvement in EU hospitals was used as the basis for the classification scheme. Items included for the development of an evaluation tool-the maturity index-were considered important contributors to quality improvement. The four-stage quality cycle (plan, do, check and act) was used to determine the level of maturity of the various items. Psychometric properties of the classification scheme were assessed, and validation analyses were performed. Results: A total of 389 hospitals participated in a questionnaire survey; response rates varied by country. For a final sample of 349 hospitals, it was possible to construct a quality improvement maturity index which consisted of seven domains and 113 items. The results of independent analyses sustained the validity of the index, which was useful in differentiating between hospitals in the research sample according to the maturity of their quality improvement system (defined as the total of all quality improvement activities). Discussion: Further research is recommended to develop an instrument which for use in the future as a practical tool to evaluate the maturity of hospital quality improvement systems

Application of quality improvement strategies in 389 European hospitals: results of the MARQuIS project

Context: This study was part of the Methods of Assessing Response to Quality Improvement Strategies (MARQuIS) research project investigating the impact of quality improvement strategies on hospital care in various countries of the European Union (EU), in relation to specific needs of cross-border patients. Aim: This paper describes how EU hospitals have applied seven quality improvement strategies previously defined by the MARQuIS study: organisational quality management programmes; systems for obtaining patients' views; patient safety systems; audit and internal assessment of clinical standards; clinical and practice guidelines; performance indicators; and external assessment. Methods: A web-based questionnaire was used to survey acute care hospitals in eight EU countries. The reported findings were later validated via on-site survey and site visits in a sample of the participating hospitals. Data collection took place from April to August 2006. Results: 389 hospitals participated in the survey; response rates varied per country. All seven quality improvement strategies were widely used in European countries. Activities related to external assessment were the most broadly applied across Europe, and activities related to patient involvement were the least widely implemented. No one country implemented all quality strategies at all hospitals. There were no differences between participating hospitals in western and eastern European countries regarding the application of quality improvement strategies. Conclusions: Implementation varied per country and per quality improvement strategy, leaving considerable scope for progress in quality improvements. The results may contribute to benchmarking activities in European countries, and point to further areas of research to explore the relationship between the application of quality improvement strategies and actual hospital performanc

Linear conductance in Coulomb-blockade quantum dots in the presence of interactions and spin

We discuss the calculation of the linear conductance through a Coulomb-blockade quantum dot in the presence of interactions beyond the charging energy. In the limit where the temperature is large compared with a typical tunneling width, we use a rate-equations approach to describe the transitions between the corresponding many-body states. We discuss both the elastic and rapid-thermalization limits, where the rate of inelastic scattering in the dot is either small or large compared with the elastic transition rate, respectively. In the elastic limit, we find several cases where a closed solution for the conductance is possible, including the case of a constant exchange interaction. In the rapid-thermalization limit, a closed solution is possible in the general case. We show that the corresponding expressions for the linear conductance simplify for a Hamiltonian that is invariant under spin rotations.Comment: 11 pages, no figures, revtex