Polyploid measles virus with hexameric genome length

Particles of most virus species accurately package a single genome, but there are indications that the pleomorphic particles of parainfluenza viruses incorporate multiple genomes. We characterized a stable measles virus mutant that efficiently packages at least two genomes. The first genome is recombinant and codes for a defective attachment protein with an appended domain interfering with fusion-support function. The second has one adenosine insertion in a purine run that interrupts translation of the appended domain and restores function. In that genome, a one base deletion in a different purine run abolishes polymerase synthesis, but restores hexameric genome length, thus ensuring accurate RNA encapsidation, which is necessary for efficient replication. Thus, the two genomes are complementary. The infection kinetics of this mutant indicate that packaging of multiple genomes does not negatively affect growth. We also show that polyploid particles are produced in standard infections at no expense to infectivity. Our results illustrate how the particles of parainfluenza viruses efficiently accommodate cargoes of different volume, and suggest a mechanism by which segmented genomes may have evolved.

Gender influences the detection of spatial working memory deficits in bipolar disorder.

Objective: Despite evidence that gender may influence neurocognitive functioning, few studies have examined its effects in bipolar disorder (BD) a priori. The aim of this study was to examine how gender influences executive-type functions, which are potentially useful as endophenotypes for BD. Methods: The performance of 26 euthymic patients(12 males, 14 females) with DSM-IV BD (20 BD type I and six BD type II) was compared to that of 26 controls (12 males, 14 females) on tests of executive function. Controls were matched to patients on an individual basis for sex, age and premorbid IQ. Tests assessed spatial working memory (SWM), planning, attentional set-shifting and verbal fluency. Results: Overall, patients showed deficits in SWM strategy (p < 0.001) and made more SWM errors relative to controls (p < 0.001). These deficits were more apparent in male-only comparisons (both p < 0.001) than in female-only comparisons (both p < 0.05). When examined in isolation, male controls were significantly better at performing the SWM task than female controls (both p < 0.05). This pattern was not observed in the patient cohort: male patients had poorer strategy scores than female patients (p < 0.05), but made a similar number of SWM errors. Conclusions: These findings provide evidence that gender can influence the detection of SWM deficits in the euthymic phase of BD, as the sex-related disequilibrium in SWM identified in healthy controls was disrupted in BD. © 2008 The Authors Journal compilation © 2008 Blackwell Munksgaard.

Surface plasmon polariton propagation length: A direct comparison using photon scanning tunneling microscopy and attenuated total reflection

The propagation of surface plasmon polaritons (SPP's) is studied using a photon scanning tunneling microscope (PSTM) and conventional attenuated total reflection (ATR). The PSTM experiment uses localized (focused beam) launching or SPP's at a wavelength of 632.8 nm. Propagation of the SPP is observed as an exponentially decaying tail beyond the launch site acid the 1/e propagation length is measured directly for a series of Ag films of different thicknesses. The ATR measurements are used to characterize the thin film optical and thickness parameters, revealing, notably, the presence of a contaminating adlayer of Ag2S of typical dielectric function, 8.7 + i2.7, and thickness 1-2 nm. Values of the SPP propagation length, based on the ATR- derived film parameters used in the four-media implicit SPP dispersion relation, show very good agreement with those based on the PSTM images for the case of undercoupled or optimally coupled SPP modes. The observed propagation lengths are quantitatively analyzed taking explicit account of additional intrinsic damping due to the growth of the Ag2S layer and of reradiation of the SPP back into the prism outside the launch site. Finally, the PSTM images show excellent SPP beam confinement in the original propagation direction.

Effect of plasma scale length on multi-MeV proton production by intense laser pulses

The influence of the plasma density scale length on the production of MeV protons from thin foil targets irradiated at I lambda (2) = 5 x 10(19) Wcm(-2) has been studied. With an unperturbed foil, protons with energy >20 MeV were formed in an exponential energy spectrum with a temperature of 2.5 +/- 0.3 MeV. When a plasma with a scale length of 100 mum was preformed on the back of the foil, the maximum proton energy was reduced to