Extracting the resonance parameters from experimental data on scattering of charged particles

A new parametrization of the multi-channel S-matrix is used to fit scattering data and then to locate the resonances as its poles. The S-matrix is written in terms of the corresponding "in" and "out" Jost matrices which are expanded in the Taylor series of the collision energy E around an appropriately chosen energy E0. In order to do this, the Jost matrices are written in a semi-analytic form where all the factors (involving the channel momenta and Sommerfeld parameters) responsible for their "bad behaviour" (i.e. responsible for the multi-valuedness of the Jost matrices and for branching of the Riemann surface of the energy) are given explicitly. The remaining unknown factors in the Jost matrices are analytic and single-valued functions of the variable E and are defined on a simple energy plane. The expansion is done for these analytic functions and the expansion coefficients are used as the fitting parameters. The method is tested on a two-channel model, using a set of artificially generated data points with typical error bars and a typical random noise in the positions of the points.Comment: 15 pages, 7 figures, 2 table

The Structure of Differential Invariants and Differential Cut Elimination

The biggest challenge in hybrid systems verification is the handling of differential equations. Because computable closed-form solutions only exist for very simple differential equations, proof certificates have been proposed for more scalable verification. Search procedures for these proof certificates are still rather ad-hoc, though, because the problem structure is only understood poorly. We investigate differential invariants, which define an induction principle for differential equations and which can be checked for invariance along a differential equation just by using their differential structure, without having to solve them. We study the structural properties of differential invariants. To analyze trade-offs for proof search complexity, we identify more than a dozen relations between several classes of differential invariants and compare their deductive power. As our main results, we analyze the deductive power of differential cuts and the deductive power of differential invariants with auxiliary differential variables. We refute the differential cut elimination hypothesis and show that, unlike standard cuts, differential cuts are fundamental proof principles that strictly increase the deductive power. We also prove that the deductive power increases further when adding auxiliary differential variables to the dynamics

Health promotion research: dilemmas and challenges

OBJECTIVE—To analyse dilemmas and challenges in health promotion research, and to generate ideas for future development.
METHOD—The analysis is based on authors' experiences in working in the field of research and action in health promotion and on experiences of others as found in literature.
RESULTS—The assumptions underlying scientific research as based in the biomedical design are difficult to meet in community-based health promotion research. Dilemmas are identified in relation to the possibility of defining the independent and dependent variables beforehand and the intermingling of these variables (the intervention and outcome dilemma), the difficulty in quantifying the desired outcomes (the number dilemma), and the problem of diffusion of the programme to the control group (the control group dilemma).
CONCLUSION—Research in health promotion has specific reasons to reconsider the approach towards research, the selection of outcome variables, and research techniques. Strategies and methods to make activities and their outcomes clear are discussed and criteria to judge confidence and applicability of research findings are presented.


Keywords: health promotion research; research dilemmas; research challenge

Het WAP onder de loep

De gemeente Rotterdam heeft de ambitie om effectief vraaggericht te werken. Daartoe zijn WijkActiePlannen (WAP) opgesteld waarin concrete wijkgerichte doelstellingen zijn opgenomen. De doelstellingen zijn als het goed is, gebaseerd op de behoeften van de wijkbewoners, maar is dat ook zo? Om een antwoord te geven op die vraag heeft de gemeente Rotterdam aan de Erasmus Universiteit Rotterdam gevraagd om een onderzoeker het veld in te sturen. De opdracht van de onderzoeker is om de behoeften van bewoners vast te leggen en om te kijken of die behoeften ook in de doelstellingen van het WAP zijn vertaald. Uit het onderzoek blijkt dat het WAP van Schiebroek Zuid goed in staat is om een groot aantal van de heersende problemen in cijfers te laten zien: armoede, schooluitval, criminaliteit en werkloosheid. Deze cijfers hebben echter een oorzaak die niet altijd goed achterhaald wordt waardoor bepaalde aanpakken niet het meest efficiënt en/of effectief zijn. Door te vragen naar de behoeften van bewoners is een rijker beeld ontstaan over de oorzaken en gevolgen van de heersende problemen. Het rijke beeld biedt aanknopingspunten om anders over wijkgericht na te denken zodat de effectiviteit kan worden vergroot

Het WAP onder de loep

De gemeente Rotterdam heeft de ambitie om effectief vraaggericht te werken. Daartoe zijn WijkActiePlannen (WAP) opgesteld waarin concrete wijkgerichte doelstellingen zijn opgenomen. De doelstellingen zijn als het goed is, gebaseerd op de behoeften van de wijkbewoners, maar is dat ook zo? Om een antwoord te geven op die vraag heeft de gemeente Rotterdam aan de Erasmus Universiteit Rotterdam gevraagd om een onderzoeker het veld in te sturen. De opdracht van de onderzoeker is om de behoeften van bewoners vast te leggen en om te kijken of die behoeften ook in de doelstellingen van het WAP zijn vertaald. Uit het onderzoek blijkt dat het WAP van Schiebroek Zuid goed in staat is om een groot aantal van de heersende problemen in cijfers te laten zien: armoede, schooluitval, criminaliteit en werkloosheid. Deze cijfers hebben echter een oorzaak die niet altijd goed achterhaald wordt waardoor bepaalde aanpakken niet het meest efficiënt en/of effectief zijn. Door te vragen naar de behoeften van bewoners is een rijker beeld ontstaan over de oorzaken en gevolgen van de heersende problemen. Het rijke beeld biedt aanknopingspunten om anders over wijkgericht na te denken zodat de effectiviteit kan worden vergroot

Membrane targeting of cGMP-dependent protein kinase is required for cystic fibrosis transmembrane conductance regulator Cl- channel activation

A recently cloned isoform of cGMP-dependent protein kinase (cGK), designated type II, was implicated as the mediator of cGMP-provoked intestinal Cl- secretion based on its localization in the apical membrane of enterocytes and on its capacity to activate cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels. In contrast, the soluble type I cGK was unable to activate CFTR in intact cells, although both cGK I and cGK II could phosphorylate CFTR in vitro. To investigate the molecular basis for the cGK II isotype specificity of CFTR channel gating, we expressed cGK II or cGK I mutants possessing different membrane binding properties by using adenoviral vectors in a CFTR-transfected intestinal cell line, and we examined the ability of cGMP to phosphorylate and activate the Cl- channel. Mutation of the cGK II N-terminal myristoylation site (Gly2 --> Ala) reduced cGK II membrane binding and severely impaired cGK II activation of CFTR. Conversely, a chimeric protein, in which the N-terminal membrane-anchoring domain of cGK II was fused to the N terminus of cGK Ibeta, acquired the ability to associate with the membrane and activate the CFTR Cl- channel. The potency order of cGK constructs for activation of CFTR (cGK II > membrane-bound cGK I chimer >> nonmyristoylated cGK II > cGK Ibeta) correlated with the extent of 32P incorporation into CFTR observed in parallel measurements. These results strongly support the concept that membrane targeting of cGK is a major determinant of CFTR Cl- channel activation in intact cells

Modelling Clock Synchronization in the Chess gMAC WSN Protocol

We present a detailled timed automata model of the clock synchronization algorithm that is currently being used in a wireless sensor network (WSN) that has been developed by the Dutch company Chess. Using the Uppaal model checker, we establish that in certain cases a static, fully synchronized network may eventually become unsynchronized if the current algorithm is used, even in a setting with infinitesimal clock drifts

Heat-stable enterotoxin receptor/guanylyl cyclase C is an oligomer consisting of functionally distinct subunits, which are non-covalently linked in the intestine

Guanylyl cyclase (GC) C is a heat-stable enterotoxin (STa) receptor with a monomeric M(r) of approximately 140,000. We calculated from its hydrodynamic parameters that an active GC-C complex has a M(r) of 393,000, suggesting that GC-C is a trimer under native conditions. Both trimeric and dimeric GC-C complexes were detected by 125I-STa binding and SDS-polyacrylamide gel electrophoresis under non-reducing conditions. The GC activity and STa binding from intestinal brush border membranes comigrated in gel filtration and velocity sedimentation with recombinant GC-C. However, 125I-STa cross-linking demonstrated that STa receptors with molecular masses of 52 and 74 kDa are non-covalently attached to GC in the intestine. Radiation inactivation revealed different functional sizes for basal GC activity, STa-stimulated GC activity, and STa binding (59, 210-240, and 32-52 kDa, respectively). At low radiation doses, basal GC activity was stimulated, suggesting that GC-C is inhibited by a relatively large, probably internal structure. These results suggest that STa may activate GC-C by promoting monomer-monomer interaction (internal "dimerization") within a homotrimeric GC-C complex, and that GC-C is proteolytically modified in the brush border membrane but retains its function