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.     

Gene expression profiling in a mouse model of infantile neuronal ceroid lipofuscinosis reveals upregulation of immediate early genes and mediators of the inflammatory response

Background  

The infantile form of neuronal ceroid lipofuscinosis (also known as infantile Batten disease) is caused by hereditary deficiency of a lysosomal enzyme, palmitoyl-protein thioesterase-1 (PPT1), and is characterized by severe cortical degeneration with blindness and cognitive and motor dysfunction. The PPT1-deficient knockout mouse recapitulates the key features of the disorder, including seizures and death by 7–9 months of age. In the current study, we compared gene expression profiles of whole brain from PPT1 knockout and normal mice at 3, 5 and 8 months of age to identify temporal changes in molecular pathways implicated in disease pathogenesis.     

Experimental and computational study of the low-density plasma in the outer regions of a theta pinch

The time evolution of the electron density has been measured in the outer regions of a fast theta pinch by means of a Mach-Zehnder interferometer. The results show that the electron density outside the central plasma column is relatively high, i.e. between 1 and 5×10¹⁴ cm^?3. A comparison of these measurements with theoretical calculations leads to the conclusion that the pinch must be unstable during the implosion phase.     

The new isotopes247Md,243Fm,239Cf,and investigation of the evaporation residues from fusion of206Pb,208Pb,and209Bi with40Ar

The evaporation residues produced in heavy ion fusion reactions between⁴⁰Ar and²⁰⁶Pb,²⁰⁸Pb, and²⁰⁹Bi, respectively, were investigated. They were separated in-flight using a velocity filter (SHIP) and identified after implantation into an array of position sensitive surface barrier detectors by measuring their decay characteristics. Three newα-emitting isotopes were found:²⁴⁷Md,²⁴³Fm, and²³⁹Cf.²⁴⁷Md was identified by correlation to its known daughter decay²⁴³Es, and²⁴³Fm and²³⁹Cf were observed as correlated decays. Moreover, all previously known deexcitation channels, characterized by spontaneous fission or byα decay, could be observed for the first time in one experimental setup. Our results for formation cross sections and decay characteristics are in agreement with known data.     

Quantummechanical treatment of the penetration through a two-dimensional fission barrier

The collective Hamiltonian is idealized by making a harmonic approximation for the motion perpendicular to the fission path. This is done within a properly defined set of coordinates. The frequency for the transverse oscillations depends on the fission coordinate which leads to a coupling between the two degrees of freedom. Its influence is discussed within the language of scattering theory. Using the Born approximation, formulas for the transmission amplitudes are deduced. These formulas are applied to a simple example. All calculations are done analytically, taking into account the variation of the inertia for the fission mode.     

ϱ0 and f production in π+p interactions

Inclusive ?⁰ and f(1270) production are analysed in π⁺p collisions at 8, 16 and 23 GeV/c. The ?⁰ cross section increases with energy such that the ?⁰/π^? ratio remains constant. Emphasis is laid on cross sections as a function of the transverse momentum and of the Feynman x variable. The ?⁰'s can be attributed to two sources: some ?⁰'s are centrally produced, but there is a pronounced forward peak. The distribution of leptons coming from ?⁰ decay is discussed.