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This study concerns the intelligibility of speech under various periodic switching operations. In diphasic speech the signal is separated into successive segments which are reversed in phase. The intelligibility of this speech was found to be high for switching frequencies below about 100 cps; in the intermediate audio-frequency region the intelligibility fails to very low values. Throughout this intermediate frequency region, the intelligibility of diphasic speech is markedly less than that of interrupted speech. Some explanation for this difference is found in the Fourier expansion for the two cases. In interrupted speech the original spectrum is retained, but in diphasic speech terms for the spectrum in its normal form do not appear. It was experimentally observed that throughout the intermediate frequency region binaural diphasic speech, in which the signal is switched alternately from one ear to the other, is more intelligible than monaural diphasic speech or interrupted speech. [ABSTRACT FROM AUTHOR]

The lipids of different developmental stages of Culex pipiens fatigans, vector of bancroftian filariasis, have been investigated. The phospholipid composition of the developmental stages and of the subcellular fractions of fourth instar larvae of the insects were analyzed. The composition of fatty acids and their positional distribution have also been examined in the major phospholipids of the larvae. The insect eggs contained higher amounts of lipids than larvae suggesting that they were utilized during embryogenesis. Phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) comprised over 75% of the insect phospholipids. Of these, PE was present in the greatest amounts during all stages of growth and in the subcellular fractions of larvae. An ethanolamine containing sphingolipid was found as a component of the phospholipids of the insects. About 50% of the lipids of the larvae were localized in the cell debris and nuclei fraction which also contained most of the lysolipids of the insects. As in other Diptera 16∶0, 16∶1 and 18∶1 were the major fatty acids present in the insect lipids of which the fatty acid found in greatest amounts was 16∶1. Similar to the phospholipids of animal species, saturated fatty acids were predominantly linked to the 1 position of the major phospholipids of the insects while the unsaturated fatty acids were in higher amounts at the 2 position. [ABSTRACT FROM AUTHOR]

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