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Monitoring of the flow of an ice sheet in Antarctica finds that the surface velocity oscillates by as much as 20 per cent every two weeks: the spring-to-neap tidal cycle seems to be the cause. Although the mechanism through which these tides couple to ice flow has yet to be elucidated, these observations caution against the use of velocity measurements over limited periods to infer long-term changes in flow rate.
Optical observations of γ-ray burst (GRB) 060614 (duration ∼100s) rule out the presence of an associated supernova. This would seem to require a new explosive process: either a massive 'collapsar' that powers a GRB without any associated supernova, or a new type of engine, as long-lived as the collapsar but without a massive star.
GRB 060505 and GRB 060614 were not accompanied by supernova emission down to limits hundreds of times fainter than the archetypal SN 1998bw that accompanied GRB 980425, and fainter than any type Ic supernova ever observed.
Deep optical observations of GRB 060614 show no emerging supernova with absolute magnitude brighter than MV = − 13.7. Any supernova associated with GRB 060614 was therefore at least 100 times fainter, at optical wavelengths, than the other supernovae associated with GRBs.
The bright, nearby γ-ray burst (GRB) 060614 does not fit in either of the two duration classes. Its ∼102-s duration groups it with long-duration GRBs, whereas its temporal lag and peak luminosity fall entirely within the short GRB subclass. This opens the door on a new GRB classification scheme that straddles both long and short bursts.
The observation of the radiative decay mode of free neutrons, with measurements that agree with theoretical predictions may provide opportunities for more detailed investigations of the weak interaction processes involved neutron beta decay.
A set of three paralogous bHLH transcription factors is required to promote stomatal development. SPEECHLESS, MUTE and FAMA are sequentially expressed in, and are successively required for, the initiation, proliferation and terminal differentiation of cells in the stomatal lineage.
Toxoplasma gondii causes intracellular infections with disease severity that varies depending on the pathogen strain. A potential mechanism has now been elucidated, whereby the presence of a putative kinase in certain strains results in the activation of distinct host signalling pathways.
Neurons in the monkey lateral prefrontal cortex are activated before a large number of individual complex movements, suggesting that they represent an abstract categorization of motor behaviours, as opposed to the individual sequences themselves. Combined with previous work, this suggests that abstract grouping may be a general property of the prefrontal cortex, perhaps facilitating complex behaviour.