Market work and household production in Brazil

This thesis is composed of three papers in which the research questions are related to the double burden that accrues to Brazilian women. The first and second papers address this issue by looking at expenditure decisions about home production. The first paper examines whether the expenditure decisions about production goods, such as white appliances, relative to entertainment goods, such as TVs, are the outcome of a bargaining process between husbands and wives. The second paper looks at the demand for maid services and for production durable goods, examining the extent to which other household members substitute for maid services and durable goods in home production. The third paper addresses the effects of Brazilian women's double burden on their labor market participation by examining whether the occupational choice of Brazilian women is affected by their gender roles and whether entry into other occupations that are not identified as female occupations has become easier since the introduction of anti-discrimination laws in the labor market. The first paper combines two Brazilian data sets: a Brazilian household expenditure survey, Pesquisa de Orçamento Familiares (POF), and a Brazilian household survey, Pesquisa Nacional Por Amostra de Domicílios (PNAD). The results of the first paper indicate that the decision about durable goods ownership is the outcome of a bargaining process between husband and wife. The test on the coefficients of the marriage market variable and the indicators of households in which only the wife and households in which only the husband makes expenditure decisions corroborate the expectations about wives' preferences for production goods. The same data sets as the first paper are used in the second paper. The finding of the second paper indicates that if the marriage market is favorable to women, that is if the ratio of women to men goes from 1.07 to 0.96, the increment in the household probability of owning at least one maid's substitute durable goods is equivalent to 24% the impact of moving a household up one income quintile. Moreover, the results indicate that daughters' time substitutes for wives' time and maid services in home production. Parents may want daughters trained in home production to be able to perform their future role as wives. However, this training comes at a cost to daughters' investment in formal education, narrowing their future career options. The data used in the third paper come from a Brazilian household survey, Pesquisa Nacional Por Amostra de Domicílios (PNAD). Gender roles are responsible for women to choose female-dominated occupations, married women are 1.14 times more likely to work in female-dominated occupations and having a child six years and older increases on average by 12% the probability that women work in female-dominated occupations instead of genderintegrated occupations in 2001. However, it becomes easier for all types of women to enter into male-dominated and gender-integrated occupations in 2001 compared to 1981.

Integrated micro fuel cells with on-board hydride reactors and autonomous control schemes

Miniaturization of power generators to the MEMS scale, based on the hydrogen-air fuel cell, is the object of this research. The micro fuel cell approach has been adopted for advantages of both high power and energy densities. On-board hydrogen production/storage and an efficient control scheme that facilitates integration with a fuel cell membrane electrode assembly (MEA) are key elements for micro energy conversion. Millimeter-scale reactors (ca. 10 µL) have been developed, for hydrogen production through hydrolysis of CaH2 and LiAlH4, to yield volumetric energy densities of the order of 200 Whr/L. Passive microfluidic control schemes have been implemented in order to facilitate delivery, self-regulation, and at the same time eliminate bulky auxiliaries that run on parasitic power. One technique uses surface tension to pump water in a microchannel for hydrolysis and is self-regulated, based on load, by back pressure from accumulated hydrogen acting on a gas-liquid microvalve. This control scheme improves uniformity of power delivery during long periods of lower power demand, with fast switching to mass transport regime on the order of seconds, thus providing peak power density of up to 391.85 W/L. Another method takes advantage of water recovery by backward transport through the MEA, of water vapor that is generated at the cathode half-cell reaction. This regulation-free scheme increases available reactor volume to yield energy density of 313 Whr/L, and provides peak power density of 104 W/L. Prototype devices have been tested for a range of duty periods from 2-24 hours, with multiple switching of power demand in order to establish operation across multiple regimes. Issues identified as critical to the realization of the integrated power MEMS include effects of water transport and byproduct hydrate swelling on hydrogen production in the micro reactor, and ambient relative humidity on fuel cell performance.