Ultrashort-range, high-frequency communication by female mice shapes social interactions.

Animals engage in complex social encounters that influence social groups and resource allocation. During these encounters, acoustic signals, used at both short and long ranges, play pivotal roles in regulating the behavior of conspecifics. Mice, for instance, emit ultrasonic vocalizations, signals above the range of human hearing, during close-range social interactions. How these signals shape behavior, however, is unknown due to the difficulty in discerning which mouse in a group is vocalizing. To overcome this impediment, we used an eight-channel microphone array system to determine which mouse emitted individual vocal signals during 30 minutes of unrestrained social interaction between a female and a single male or female conspecific. Females modulated both the timing and context of vocal emission based upon their social partner. Compared to opposite-sex pairings, females in same-sex pairs vocalized when closer to a social partner and later in the 30 minutes of social engagement. Remarkably, we found that female mice exhibited no immediate changes in acceleration (movement) to male-emitted vocal signals. Both males and females, in contrast, modulated their behavior following female-emitted vocal signals in a context-dependent manner. Thus, our results suggest female vocal signals function as a means of ultrashort-range communication that shapes mouse social behavior.

A rapidly-reversible absorptive and emissive vapochromic Pt(II) pincer-based chemical sensor.

Selective, robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring. Here we design a Pt(II) pincer-type material with selective absorptive and emissive responses to methanol and water. The yellow anhydrous form converts reversibly on a subsecond timescale to a red hydrate in the presence of parts-per-thousand levels of atmospheric water vapour. Exposure to methanol induces a similarly-rapid and reversible colour change to a blue methanol solvate. Stable smart coatings on glass demonstrate robust switching over 104 cycles, and flexible microporous polymer membranes incorporating microcrystals of the complex show identical vapochromic behaviour. The rapid vapochromic response can be rationalised from the crystal structure, and in combination with quantum-chemical modelling, we provide a complete microscopic picture of the switching mechanism. We discuss how this multiscale design approach can be used to obtain new compounds with tailored VOC selectivity and spectral responses.

Carbon dioxide binary crystals via the thermal decomposition of RDX at high pressure.

A carbon dioxide and nitrous oxide solid solution has been captured in a diamond anvil cell following the thermal decomposition of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) at high temperatures and pressures. This is the first time a carbon dioxide binary solid has been observed at high pressure. This observation has stimulated low temperature crystallographic studies of this binary system using recently developed gas absorption apparatus and computational modelling.

Non-equilibrium cobalt(iii) "click" capsules.

Cobalt(iii) tetrahedral capsules have been prepared using an assembly-followed-by-oxidation protocol from a cobalt(ii) precursor and a readily derivatizable pyridyl-triazole ligand system. Experiments designed to probe the constitutional dynamics show that these architectures are in a non-equilibrium state. A preliminary investigation into the host-guest chemistry of a water-soluble derivative shows it can bind and differentiate a range of different neutral organic molecules. The stability of this ensemble also permits the study of guest-binding at high salt concentrations.

What is the prognosis of mild normocytic anaemia in older people?

BACKGROUND: There is reduced survival for people with all types of anaemia and it has been shown that there is a low yield from investigations for older people with normocytic anaemia. However, the longer-term outcomes of people with mild normocytic anaemia are not known. AIMS: To determine the 5-year prognosis of older people with mild normocytic anaemia, compared with non-anaemic controls. METHODS: This was a prospective cohort study, with some retrospective data collection, comparing 52 people aged > or =65 years (haemoglobin 100-119 g/L; mean cell volume 80-99 fL) without an obvious cause at presentation with 52 non-anaemic controls. The incidence of death, new malignancies and significant illnesses was compared between the two groups, 5 years later. RESULTS: Anaemic patients were less likely to be living at home at baseline. Although survival was lower for the anaemic group at all follow-up times, these differences were not significantly different. Over 5 years, there were no significant differences between groups in the types of problems that developed. CONCLUSIONS: A mild normocytic anaemia in older people, in the absence of an obvious cause, is not associated with significant differences in outcomes but is associated with poorer independence and a trend to lower survival. We suggest it may therefore be a marker of frailty in older people.

Person-to-person transmission of Giardia lamblia in day-care nurseries.

In an outbreak of giardiasis at two day-care nurseries in metropolitan Toranto Giardia lamblia appeared to be transmitted person to person. No common source of infection could be found. The proportions of children infected in the two nurseries were 39% and 17%; infection was spread to 7% and 23% of their household contacts. Of the infected children and household contacts 26% and 30% respectively of those for whom detailed information could be obtained were symptomatic. Canadian children were more likely to be infected and symptomatic than were immigrant children attending the nurseries. The most susceptible ages for infection were 1 to 3 years. The results of this study suggest that all children in day-care nurseries who are infected with G. lamblia should be treated, regardless of whether they are symptomatic.