Extending the double ramification cycle by resolving the Abel-Jacobi map

Over the moduli space of smooth curves, the double ramification cycle can be defined by pulling back the unit section of the universal jacobian along the Abel-Jacobi map. This breaks down over the boundary since the Abel-Jacobi map fails to extend. We construct a `universal' resolution of the Abel-Jacobi map, and thereby extend the double ramification cycle to the whole of the moduli of stable curves. In the non-twisted case, we show that our extension coincides with the cycle constructed by Li, Graber, Vakil via a virtual fundamental class on a space of rubber maps.Comment: 35 pages, 1 figure. v2:Exposition heavily revised (and hopefully improved). Main results unchanged. There was a gap in the proof of lemma 3.14; it is replaced by the construction in lemma 6.1. v3: Extended to include the `k-twisted' case, where one allows powers of the relative dualising sheaf. v4. Final version, to appear in J. Inst. Math. Jussieu. Comments still very welcom

The Brauer-Manin obstruction on Kummer varieties and ranks of twists of abelian varieties

Let r > 0 be an integer. We present a sufficient condition for an abelian variety A over a number field k to have infinitely many quadratic twists of rank at least r, in terms of density properties of rational points on the Kummer variety Km(A^r) of the r-fold product of A with itself. One consequence of our results is the following. Fix an abelian variety A over k, and suppose that for some r > 0 the Brauer-Manin obstruction to weak approximation on the Kummer variety Km(A^r) is the only one. Then A has a quadratic twist of rank at least r. Hence if the Brauer-Manin obstruction is the only one to weak approximation on all Kummer varieties, then ranks of twists of any positive-dimensional abelian variety are unbounded. This relates two significant open questions.Comment: 12 pages; final versio

GENDER AND GRADUATE ECONOMICS EDUCATION IN THE US

This paper reports on the ?ndings of a survey of top economics graduate schools as they relate to women and men. The results provide strong evidence that at these top graduate schools, women graduate students are less integrated in their economic disciplines than are male graduate students. In the second part of the paper, this paper relates those ?ndings to alternative theories as to why this is the case. This paper concludes by suggesting that the emphasis on theoretical studies in the current core of the graduate economics program can be seen as a type of hazing process that seems to have a signi?cant cost since many women (and men) with great creative promise are discouraged from continuing in economics and do not bene?t nearly as much as they would have from more policy-driven core courses.

The Role of Agricultural Colleges and Universities in Rural Development and Lifelong Learning in Asia

The paper expounds on the challenges confronting institutions of higher agricultural education (HAE) in the context of the significant role of education in alleviating poverty, especially in rural areas, and in light of the changing needs of rural areas and economies. Specifically, HAE institutions are called upon to initiate and lead in articulating a vision for the future that serves the needs not only of agriculture but also of all who inhabit the rural areas. They can step beyond their traditional role by merging forces with other stakeholders to enrich and support other levels of education with critical knowledge and information on agriculture and natural resources management (NRM), the latter being crucial in the pursuit of rural development, poverty education, and food security. To perform an active and constructive role in rural development, agricultural universities need to adjust their programs to accommodate new topics, as well as teaching and learning models; forge new partnerships with schools, academia and rural space stakeholders; expand its representation in governance; and hold continuous dialogue with policymakers. Their extension services could include support to education for rural people that encompasses primary, secondary, vocational, and adult education. University-school linkages are perceived to be illustrative of a decentralized, democratic, and community-based response to rural development problems. It is noted that universities can potentially become showcases of local traditions and knowledge, reflecting the regional, cultural, and ethical traditions of their society, as well as global movements and forces. In reinforcing their roles as contributors to a culture of learning and rural development, it is emphasized that HAE institutions need to engage more directly and more effectively in partnerships and dialogue with other local educational institutions and their surrounding communities. Findings of the ongoing IIEP-UNESCO/FAO program of research on HAE institutions in Asia are expected to provide information on how higher education institutions contribute to learning and rural development, and insights on how their strategic role in this field could be strengthened and further developed.higher agricultural education, rural development, Asia, lifelong learning