Zipf and Type-Token rules for the English, Spanish, Irish and Latin languages

The Zipf curves of log of frequency against log of rank for a large English corpus of 500 million word tokens, 689,000 word types and for a large Spanish corpus of 16 million word tokens, 139,000 word types are shown to have the usual slope close to –1 for rank less than 5,000, but then for a higher rank they turn to give a slope close to –2. This is apparently mainly due to foreign words and place names. Other Zipf curves for highlyinflected Indo-European languages, Irish and ancient Latin, are also given. Because of the larger number of word types per lemma, they remain flatter than the English curve maintaining a slope of –1 until turning points of about ranks 30,000 for Irish and 10,000 for Latin. A formula which calculates the number of tokens given the number of types is derived in terms of the rank at the turning point, 5,000 for both English and Spanish, 30,000 for Irish and 10,000 for Latin.

Neuropeptide signalling: a repository of targets for novel endectocides?

The only available parasiticides with a spectrum of action that includes a broad range of helminth and arthropod parasites are the macrocyclic lactones. Designated endectocides, these drugs have action against both endoparasitic nematodes and ectoparasitic arthropods. Unfortunately, the discovery of such drugs is exceedingly rare and there is no evidence that novel endectocidal agents will be identified and developed in the short to medium term. However, the discovery of neuropeptides with motor-modulatory activities in both arthropods and helminths, coupled with recent progress in the characterization of invertebrate neuropeptide receptors, has the potential to propel neuropeptide signalling to the forefront of efforts to develop a novel endectocide.