Current Algebra of Super WZNW Models

We derive the current algebra of supersymmetric principal chiral models with a Wess-Zumino term. At the critical point one obtains two commuting super Kac-Moody algebra as expected, but in general there are intertwining fields connecting both right and left sectors, analogously to the bosonic case. Moreover, in the present supersymmetric extension we have a quadratic algebra, rather than an affine Lie algebra, due to the mixing between bosonic and fermionic fields since the purely fermionic sector displays a Lie algebra as well.Comment: 13 page

Long-term field metal extraction by pelargonium:phytoextraction efficiency in relation to plant maturity

The long length of periods required for effective soil remediation via phytoextraction constitutes a weak point that reduces its industrial use. However, these calculated periods are mainly based on short-term and/or hydroponic controlled experiments. Moreover, only a few studies concern more than one metal, although soils are scarcely polluted by only one element.In this scientific context, the phytoextraction of metals and metalloids (Pb, Cd, Zn, Cu,and As) by Pelargonium was measured after a long-term field experiment. Both bulk and rhizosphere soils were analyzed in order to determine the mechanisms involved in soil-root transfer. First, a strong increase in lead phytoextraction was observed with plant maturity, significantly reducing the length of the period required for remediation. Rhizosphere Pb, Zn, Cu, Cd, and As accumulation was observed (compared to bulk soil), indicating metal mobilization by the plant, perhaps in relation to root activity. Moreover, metal phytoextraction and translocation were found to be a function of the metals’ nature. These results, taken altogether, suggest that Pelargonium could be used as a multi-metal hyperaccumulator under multi-metal soil contamination conditions, and they also provide an interesting insight for improving field phytoextraction remediation in terms of the length of time required, promoting this biological technique

The economic consequences of marital dissolution for women in the middle years

This article uses longitudinal data from the Panel Study of Income Dynamics to explore how changes in marital status affect the economic status of married women in their middle years. Results demonstrate that when a marriage ends, the economic status of women declines considerably. Components of income change are discussed, with emphasis on the extent to which women can compensate for the loss of a spouse's income through increases in paid labor, by changes in living arrangements, and by the use of public and private transfers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45631/1/11199_2004_Article_BF00287401.pd

Immigration and the school system

This paper presents a tractable model to study the effect of immigration on host countries’ school system and student outcomes. In our model, education quality and student outcomes are determined endogenously by the interaction of parents, schools and policy-makers deciding educational resources. Immigration decisions are based on economic factors, immigration policy, as well as on “parental motivation” (parents’ concerns about their children education achievement). The model yields results that are consistent with central empirical regularities of the school effects of immigration: (1) there is a negative effect of immigrant pupils on native students; (2) the increasing shares of immigrant students are associated with the decline of school resources and quality; (3) the school performance of immigrant children is positively associated with immigration costs; and (4) school achievement increases in parental motivation and those immigrant children with highly motivated parents tend to outperform native children. Importantly, our analysis clarifies under which conditions these empirical regularities take place and emphasizes that the effect of immigration on native pupils is mediated by the way the school system reacts to changes in class composition

Social change and the family: Comparative perspectives from the west, China, and South Asia

This paper examines the influence of social and economic change on family structure and relationships: How do such economic and social transformations as industrialization, urbanization, demographic change, the expansion of education, and the long-term growth of income influence the family? We take a comparative and historical approach, reviewing the experiences of three major sociocultural regions: the West, China, and South Asia. Many of the changes that have occurred in family life have been remarkably similar in the three settings—the separation of the workplace from the home, increased training of children in nonfamilial institutions, the development of living arrangements outside the family household, increased access of children to financial and other productive resources, and increased participation by children in the selection of a mate. While the similarities of family change in diverse cultural settings are striking, specific aspects of change have varied across settings because of significant pre-existing differences in family structure, residential patterns of marriage, autonomy of children, and the role of marriage within kinship systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45661/1/11206_2005_Article_BF01124383.pd

THE MONK PARAKEET IN NEW YORK

Attention was focused on the Monk Parakeet (Myiopsitta monachus) in New York State in 1971 when the first successful breeding record was documented for the state although Monk Parakeets had been noticed in New York and New Jersey since 1968 (Bull, 1971). Since 1971 awareness of the bird’s potential for becoming an established species in New York has spread through several segments of the state’s populace. This awareness has been created primarily through two articles in the magazine published by the New York State Department of Environmental Conservation (DEC), The Conservationist (Trimm, 1972) (Trimm, 1973); several articles in popular magazines, Parade, Yankee, Sports Afield; journals, American Birds and Kingbird; county cooperative extension bulletins and newsletters; and in numerous newspapers throughout the Northeast. The Monk Parakeet is about 12 inches long (Mourning Dove size), weighs about 90 grams, and is native to Argentina and other temperate regions of South America. The bird is pale green with a soft gray forehead and breast, some blue on the flight feathers and a flesh-colored bill. They are gregarious throughout the year. The Monk Parakeet differs from other members of the parrot family in that it builds large communal nests of sticks. Each pair of parakeets has its own private compartment with a downward-pointing tunnel entrance from the inner unlined compartment. The nest is used as sleeping quarters year round and live twigs cut by the bird are continually added to the structure (Bump, 1971). A brief review of the bird’s history in New York shows that the bird remained a mere curiosity until 1972. At that time, because the population seemed to be increasing and because information gleaned from the literature and from those with first-hand experience with the bird in its native haunts of South America indicated that the bird posed a serious potential agricultural problem, several prominent individuals, birding and conservation societies, and state and federal agencies took the position that the bird should be retrieved or removed from the wild