Carbyne forms of carbon: do they exist?

Almost 15 years have passed since carbynes entered the literature as new forms of elemental carbon. They recently attracted attention as possible interstellar dust constituents and as carriers of presolar noble gases in meteorites. Their existence and that of the related mineral chaoite are questioned, and a reevaluation of previous data is suggested.     

Is it time for a metagenomic basis of therapeutics?

The trillions of microbes associated with the human body are a key part of a comprehensive view of pharmacology. A mechanistic understanding of how the gut microbiota directly and indirectly affects drug metabolism is beginning to emerge.     

Is nanotechnology dangerous?

As co-founder and chief scientist of Sun Microsystems, Bill Joy can match technophile credentials with anybody on the planet. So when he argued that research into nanotechnology and other fields should be stopped before it wipes out humanity, humanity took notice. But most researchers think he's overstating the case.     

Lipid-like material as the source of the uncharacterized organic carbon in the ocean?

The composition and formation mechanisms of the uncharacterized fraction of oceanic particulate organic carbon (POC) are not well understood. We isolated biologically important compound classes and the acid-insoluble fraction, a proxy of the uncharacterized fraction, from sinking POC in the deep Northeast Pacific and measured carbon isotope ratios to constrain the source(s) of the uncharacterized fraction. Stable carbon and radiocarbon isotope signatures of the acid-insoluble fraction were similar to those of the lipid fraction, implying that the acid-insoluble fraction might be composed of selectively accumulated lipid-like macromolecules.     

Is face processing species-specific during the first year of life?

Between 6 and 10 months of age, the infant's ability to discriminate among native speech sounds improves, whereas the same ability to discriminate among foreign speech sounds decreases. Our study aimed to determine whether this perceptual narrowing is unique to language or might also apply to face processing. We tested discrimination of human and monkey faces by 6-month-olds, 9-month-olds, and adults, using the visual paired-comparison procedure. Only the youngest group showed discrimination between individuals of both species; older infants and adults only showed evidence of discrimination of their own species. These results suggest that the "perceptual narrowing" phenomenon may represent a more general change in neural networks involved in early cognition.     

Is the fragility of a liquid embedded in the properties of its glass?

When a liquid is cooled below its melting temperature, it usually crystallizes. However, if the quenching rate is fast enough, the system may remain in a disordered state, progressively losing its fluidity upon further cooling. When the time needed for the rearrangement of the local atomic structure reaches approximately 100 seconds, the system becomes "solid" for any practical purpose, and this defines the glass transition temperature Tg. Approaching this transition from the liquid side, different systems show qualitatively different temperature dependencies of the viscosity, and accordingly they have been classified by introducing the concept of "fragility." We report experimental observations that relate the microscopic properties of the glassy phase to the fragility. We find that the vibrational properties of the glass well below Tg are correlated with the fragility value. Consequently, we extend the fragility concept to the glassy state and indicate how to determine the fragility uniquely from glass properties well below Tg.