Land and landlessness among rural-to-rural migrants in Nepal's Terai region.

"Nepal has been experiencing a permanent rural-to-rural migration of households from the central hill zone to the Terai region. Migrant households, due to the structure of the Terai economy, are impelled to acquire control of land for subsistence agriculture by squatting, purchasing, or receiving a grant. A household's ability to maximize subsistence opportunities is partly a function of the means by which land is acquired and whether land is acquired at all. Factors which determine the chances of acquiring land reflect the role of institutional rigidities such as the distribution of wealth and the caste structure, state-imposed land reform policies, and such household characteristics as family size and risk aversion. A multinomial logit model is used to empirically assess the importance of these elements in the outcomes of migrant households' resource acquisition decisions."

Joint hormonal and sensory stimulation modulate neuronal number in adult canary brains.

Treatment of adult female canaries with testosterone (T) causes them to produce male-typical vocalizations and results in striking growth of brain nuclei that control song behavior (Nottebohm, 1980). The song-control nucleus HVc (caudal nucleus of the ventral hyperstriatum) contains cells that concentrate testosterone or its metabolites, suggesting that steroid hormones may induce the growth of HVc directly by regulating the expression of specific genes in those HVc neurons that have steroid receptors. However, we have previously provided evidence that is inconsistent with the idea that steroids promote growth of HVc solely via a direct action on hormone receptors: testosterone treatment of deafened adult females results in very little growth of HVc, relative to T-treated hearing birds (Bottjer et al., 1986b). Thus, birds in the former group undergo very little overall growth of HVc despite high circulating levels of hormone. We show here that the slightly increased size of HVc in T-treated deaf birds is attributable to an increase in neuronal spacing; the greatly increased size of HVc in T-treated hearing birds is due to an increase in neuronal number as well as spacing. There was virtually no increase in number of HVc neurons in T-treated deafened birds relative to control groups, whereas T-treated hearing birds showed a marked increase in neuron number. The song-control nucleus RA (robust nucleus of the archistriatum), which receives direct afferent input from HVc, also increases in size in response to testosterone treatment. However, the volume of RA increases in both hearing and deafened birds; this increase is primarily due to an increase in neuronal spacing as well as a small increase in neuron number. These results demonstrate that the number of neurons in a specific vocal-control nucleus (HVc) can change dramatically in adult canaries and suggest that some synergistic action of hormonal and sensory stimulation is necessary to induce such a change.