An experimental study of nitrogen flux in llamas: is N preferentially excreted?

Nitrogen isotope analysis is now commonly used to investigate the diets, and to a lesser extent, the environments of ancient populations. These studies assume that mammals are predictably enriched in ¹⁵N over their food, and concomitantly, that ¹⁵N becomes increasingly concentrated as one moves up the food chain. The literature commonly states that this ¹⁵N-enrichment of mammalian tissues is due to preferential excretion of light nitrogen (¹⁴N), but there are few data to support this assertion. To address the gap, we conducted two nitrogen flux trials in which four llamas (Lama glama) were fed high- and low-protein diets. The ratios of fecal nitrogen loss to urinary nitrogen loss were 0.30 and 0.88 on the high- and low-protein diets respectively. Feces were enriched in ¹⁵N by approximately +3‰ on both diets, whereas urinary nitrogen was depleted in ¹⁵N (−2.1‰) on the low-protein diet, but not significantly different from intake δ¹⁵N on the high-protein diet. Most importantly, there was no statistically significant difference between dietary and total excreta δ¹⁵N on either diet. Given these data and theoretical considerations, we argue that the nitrogen influx and efflux of adult mammals at steady state should be isotopically commensurate. However, during growth, diet change, thermal or nutritional stress, animals may not be at steady state and fractionation between intake and excreta δ¹⁵N may occur.     

Octavia Hill Women Housing Managers in South Africa: femininity and urban government

Women trained in a system of housing management developed by Octavia Hill in Victorian England were employed in South Africa's Coloured and European townships from the mid-1930s. They were also involved in training South African women in this tradition which emphasized the mutual responsibilities of landlords and tenants and rested upon the formation of trusting relationships or friendships between women housing managers and the tenants. Octavia Hill's followers worked hard to make a place for women in the field of housing management and claimed that their femininity gave them special expertise in this area, especially in terms of training housewives in domestic skills and in building up the relations of trust required by Octavia Hill's system. This paper describes the implementation of this system of management in South Africa and considers the implications of the role of women in housing management for our thinking about the gendered character of the state. My main argument is that rather than being a precedent for the value of incorporating femininity and women into the state, Octavia Hill's management tradition had already incorporated both historically masculine and historically feminine practices. In so far as she and her followers (and perhaps other female reformers) played a role in shaping the nature of the state, then it could be argued the state reflected a mediation of masculinity and femininity rather than a dominant masculinity and a subordinated or segregated femininity.