Global distribution patterns and niche modelling of the invasive Kalanchoe × houghtonii (Crassulaceae).

Invasive alien species are currently considered one of the main threats to global biodiversity. One of the most rapidly expanding invasive plants in recent times is Kalanchoe × houghtonii (Crassulaceae), an artificial hybrid created in the 1930s in the United States by experimental crossings between K. daigremontiana and K.

Electron fluctuation induced resonance broadening in nano electromechanical systems: the origin of shear force in vacuum.

This article presents a study of the poorly understood "shear-force" used in an important class of near-field instruments that use mechanical resonance feedback detection. In the case of a metallic probe near a metallic surface in vacuum, we show that in the 10-60 nm range there is no such a thing as a shear-force in the sense of the nonconservative friction force. Fluctuations of the oscillator resonance frequency, likely induced by local charge variations, could account for the reported effects in the literature without introducing a dissipative force.

Growing a carbon nanotube atom by atom: "and yet it does turn".

We use field emission microscopy (FEM) to observe directly the growths of individual carbon nanotubes (CNTs) from the nucleation stage and discover that the CNTs often rotate axially during growth, thus supporting a recently proposed "screw-dislocation-like" (SDL) model. One particularly revealing case is emphasized here in which the CNT turned approximately 180 times during its 11 min growth. Even more remarkable is the frame-by-frame analysis of the video which shows that the rotation proceeds by discrete steps with about approximately 24 per rotation, half the number of atoms on the circumferences of common single wall carbon nanotubes (SWNTs).

[The N-terminal pro-brain natriuretic peptide (NT-proBNP) assay with the Stratus CS analyzer].

Background: NT-proBNP is an efficient biomarker for the evaluation, management and prognosis of patients with heart failure.

Methods: We evaluated the analytical performance of the NT-proBNP immunoenzymatic assay with the Stratus CS semi-automated analyzer in two hospital laboratories. The characteristics assessed included imprecision, functional sensitivity, linearity/recovery, interferences study, high-dose hook effect and a comparison of Acute Care(TM) pPBNP (on Stratus)CS) versus PBNP (on Dimension HM) results on patient heparinized plasma samples.

Effect of mutagen-induced cell lethality on the dose response of germline mutations.

Molecular tests for mutations require a sample of tissue from which DNA is extracted, to determine the presence or absence of one or more mutations per sample. To ensure mutation fixation each sample must consist of an equal number of cells that have had one or more DNA replications. In an in vivo test, surviving stem cells compensate to give the same number of cells per sample, leaving as the only evidence for stem cell lethality the increase in mutants of clonal origin because the mutant clone developed from a population of fewer stem cells.