The Raman and infrared spectra for the C 4 ,C S ,C 12 and C 16 carboxylic acid series were obtained at liquid nitrogen temperatures, in the 2900 cm ~ 1 spectral region and were compared to spectra for selected branched and straight chain alkane systems. For hexadecanoic acid-d J the Fermi resonance interaction between the CD J symmetric stretching mode and the overtone level of the CD 3 asymmetric deformation vibration was examined as a function of physical state. In this example of a negative Fermi resonance perturbation, in which the lower frequency overtone component is more intense than the higher frequency fundamental, the coupling increases as the system passes from either the matrix isolated species or solution phase to the polycrystalline state. The spectra of the carboxylic acid series, as well as the spectra of 2,2,4-trimethyl pentane and n -octane, suggest that in the 2900 cm ~ 1 region an analogous Fermi resonance coupling exists between the CH 3 symmetric stretching vibration at -2938 cm~l and the 2871 cm~l overtone transition of the CH J asymmetric deformation. Unfortunately, the 2930-2940 cm-1 region for the solid systems is further complicated by transitions attributed to crystal interactions. Although the Fermi interaction for the methyl group has been recognized in the simpler halomethane system, for example, it has not been previously discussed in the more general context of significantly larger branched and straight chain molecules. Comparisons of the carboxylic acid spectra in the 2900 cm~l region have also led to assignments for the a-CH 2 (adjacent to the carbonyl group) and the w-CH 2 (adjacent to the methyl group) C-H stretching modes.

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Under laboratory conditions, in water without particulate matter, pyrethroid insecticides have a high toxicity to fish and some aquatic invertebrates. The pyrethroids are of very low water solubility/high lipophilicity, and therefore are rapidly and strongly adsorbed to particulate material. In the adsorbed state their bioavailability to aquatic organisms is greatly reduced. Consequently, under field conditions the aquatic impact of these insecticides is likely to be much less than might be predicted by laboratory acute or chronic toxicity test data. Over the past 10 years a large number of aquatic field studies have been carried out with pyrethroids, in natural farm ponds, streams and lakes and also in mesocosms (experimental ponds and enclosures). Recent investigations, to meet the requirements of the United States Environmental Protection Agency, have been most extensive. These studies, done in replicated experimental ponds of at least 0‐04 ha, each require at least 20 man‐years of effort. Following agricultural applications of the pyrethroid insecticides, spray‐drift or run‐off may cause minor effects upon some aquatic organisms. Algae, microorganisms, annelids, gastropods and fish are all unaffected, but some impact may occur upon certain zoo‐plankton and on aquatic stages of insects. However, with products for which realistic field studies have been reported, the effects are mostly transient and are unlikely to cause adverse changes in the populations or productivity of aquatic ecosystems.

Phase compensated optical fiber links enable high accuracy atomic clocks separated by thousands of kilometers to be compared with unprecedented statistical resolution. By searching for a daily variation of the frequency difference between four strontium optical lattice clocks in different locations throughout Europe connected by such links, we improve upon previous tests of time dilation predicted by special relativity. We obtain a constraint on the Robertson-Mansouri-Sexl parameter |α| 1.1 × 10 −8 quantifying a violation of time dilation, thus improving by a factor of around two the best known constraint obtained with Ives-Stilwell type experiments, and by two orders of magnitude the best constraint obtained by comparing atomic clocks. This work is the first of a new generation of tests of fundamental physics using optical clocks and fiber links. As clocks improve, and as fiber links are routinely operated, we expect that the tests initiated in this paper will improve by orders of magnitude in the near future.