Nuclear magnetic relaxation study of the establishment of order in the ammonium halides

The temperature dependence and thermal hysteresis of proton and deuteron spin—lattice relaxation times at high fields and a study of the recovery of the proton and deuteron magnetizations in ammonium halides are reported. The anomalies occurring near the order—disorder phase transition are related to structural, dielectric and Raman data. The hysteresis effect and the establishment of long range order are shown to be related.     

An improved solid-state perchlorate-selective electrode

A solid-state perchlorate sensitive electrode, based upon a radical-ion salt derived from N-ethylbenzothiazole-2,2'-azine. has been prepared. Its response characteristics and high apparent selectivity for perchlorate over many common anions show marked improvements with respect to similar systems which were studied earlier. The general electrode properties observed suggest that it may be considered an acceptable practical alternative to existing liquid-membrane sensors for perchlorate.     

Learned kin recognition cues in a social bird

In many cooperatively breeding birds, kin selection has an important role in the evolution and maintenance of social behaviour, and 'helpers' can maximize indirect fitness gains by preferentially allocating care to close relatives. Although there is evidence for kin-biased helping behaviour in several species, the mechanism of kin recognition underlying this behaviour is poorly understood. Vocalizations are the most commonly used cues in avian recognition systems, but the effectiveness of vocal signals as reliable recognition cues must depend on how they are acquired. However, there have been no experimental studies of the development of vocal recognition cues in cooperative birds; indeed, the ontogeny of all bird vocalizations other than song is poorly known in any species. Here, we show that cooperatively breeding long-tailed tits (Aegithalos caudatus) can discriminate between kin and non-kin according to the individual-specific characteristics of contact calls, and show experimentally that individuals learn these calls from provisioning adults during the nestling period. Finally, we show that the pattern of cooperative behaviour in this species is consistent with the use of recognition cues learned through association.     

Application of photon-counting in atomic-absorption spectrophotometry

An analysis is given of the statistics of photon-counting as a means of making measurements in atomic-absorption spectrometry. It is concluded that the simple application of Poisson counting statistics may give an over-optimistic estimate of the error, since other sources of error, such as flame flicker and variable nebulization rate, may be more significant.     

Chemiluminescence of nitric oxide: The NO (C2Π−A2Σ+) rate constant

A rocket borne scanning $\text{1}\text{4}$-m spectrometer was used to observe the night airglow between 1900 and 2300 Å at a resolution of 15 Å. An attitude control system oriented the payload horizontally near apogee (150 km) and pointed the field of view to the north and parallel with the terminator. Progressions from the δ(0, v″) and γ(0, 0) band system of nitric oxide were observed. The observations of the δ-bands and γ-bands are consistent with the relative intensities produced in the preassociation of ground state atomic oxygen and nitrogen. An observation of the v′ = 0, ε-band progression is suggested and is consistent with the presence of a resonance fluorescence contribution near apogee. The A²Σ⁺ (upper level of the γ-bands) can only be populated by cascade from the C²π state (upper level of the γ-bands) in the preassociation reaction. In the absence of quenching of the A²Σ⁺ state, the emission rate of the γ-bands can be used as a measure of the C?A transition and thus to deduce the branching ratio to the A²Σ⁺ state. This branching ratio is estimated to be 0.21±0.04.