Influence of statistical experimental errors on amplitude correlations in resonance spectroscopy

Measurements taken at Triangle Universities on a running sequence of 53d-wave resonances in⁴⁵Sc strongly suggest that the reduced partial width amplitudes have a probability distribution which is not a multivariate Gaussian. We investigate whether this result could be caused by experimental statistical errors and find strong indications that this might indeed be the case.     

Über ein bei den Clifford'schen Flächen bestehendes Analogon des Satzes von Dandelin

Ohne ZusammenfassungMit 4 Textabbildungen     

Particle size investigations of a multistep synthesis of PVA coated superparamagnetic nanoparticles

Nanoscaled particles showing superparamagnetic behavior have been intensively studied in the past years for various applications. Nevertheless, the lack of well-defined particles remains an important problem. One of the major challenges is still the large-scale synthesis of particles with a narrow size distribution. The aim of this work is to synthesize and characterize ferrofluids throughout a multistep synthesis. The iron oxide nanoparticles are first obtained by classical coprecipitation in water, followed by a thermochemical treatment and centrifugation to obtain well-dispersed primary nanoparticles. Finally polyvinyl alcohol is grafted onto the particles to ensure colloidal stability of the ferrofluid at neutral pH. The different synthesis steps and intermediate and side products are described. A model is proposed for the stabilization mechanism.     

Decay studies of <Superscript>214-216</Superscript>Ac by α- γ- γ-coincidences

The -decay fine structure of ²¹⁴Ac, ²¹⁵Ac and ²¹⁶Ac has been studied using the --coincidence technique. The nuclei were produced by ²⁰⁹Bi( ¹²C, xn)^221-xAc-reactions. Evaporation residues were separated in-flight from the primary beam using the velocity filter SHIP at GSI, Darmstadt. The separated nuclei were implanted into a position-sensitive 16-strip PIPS Si detector and their subsequent decays were measured. In these studies new and improved decay data for ^214-216Ac were obtained.     

Projective Limits of Finite-Dimensional Lie Groups

For a topological group G we define N to be the set of all normalsubgroups modulo which G is a finite-dimensional Lie group.Call G a pro-Lie group if, firstly, G is complete, secondly,N is a filter basis, and thirdly, every identity neighborhoodof G contains some member of N. It is easy to see that everypro-Lie group G is a projective limit of the projective systemof all quotients of G modulo subgroups from N. The converseimplication emerges as a difficult proposition, but it is shownhere that any projective limit of finite-dimensional Lie groupsis a pro-Lie group. It is also shown that a closed subgroupof a pro-Lie group is a pro-Lie group, and that for any closednormal subgroup N of a pro-Lie group G, for any one parametersubgroup Y : R G/N there is a one parameter subgroup X : R G such that X(t) N = Y(t) for any real number t. The categoryof all pro-Lie groups and continuous group homomorphisms betweenthem is closed under the formation of all limits in the categoryof topological groups and the Lie algebra functor on the categoryof pro-Lie groups preserves all limits and quotients. 2000 MathematicsSubject Classification 22E65, 22D05, 22E20, 22A05, 54B35.     

Mean first passage time for nuclear fission and the emission of light particles

The concept of a mean first passage time is used to study the time lapse over which a fissioning system may emit light particles. The influence of the "transient" and "saddle to scission times" on this emission are critically examined. It is argued that within the limits of Kramers's picture of fission no enhancement over that given by his rate formula needs to be considered.     

Characterization of PEI-coated superparamagnetic iron oxide nanoparticles for transfection: Size distribution,colloidal properties and DNA interaction

Superparamagnetic iron oxide nanoparticles (SPIONs) were coated with polyethylenimine. Here, we briefly describe the synthesis as well as DNA:PEI:SPION complexes and the characterization of the compounds according to their particle size, ζ-potential, morphology, DNA complexing ability, magnetic sedimentation, and colloidal stability. PEI coating of SPIONs led to colloidally stable beads even in high salt concentrations over a wide pH range. DNA plasmids and PCR products encoding for green fluorescent protein were associated with the described beads. The complexes were added to cells and exposed to permanent and pulsating magnetic fields. Presence of these magnetic fields significantly increased the transfection efficiency.