A compactness result for Fano manifolds and K\"ahler Ricci flows

We obtain a compactness result for Fano manifolds and K\"ahler Ricci flows. Comparing to the more general Riemannian versions by Anderson and Hamilton, in this Fano case, the curvature assumption is much weaker and is preserved by the K\"ahler Ricci flows. One assumption is the boundedness of the Ricci potential and the other is the smallness of Perelman's entropy. As one application, we obtain a new local regularity criteria and structure result for K\"ahler Ricci flows. The proof is based on a H\"older estimate for the gradient of harmonic functions, which may be of independent interest

Isoperimetric inequality under K\"ahler Ricci flow

Let ({\M}, g(t)) be a K\"ahler Ricci flow with positive first Chern class. We prove a uniform isoperimetric inequality for all time. In the process we also prove a Cheng-Yau type log gradient bound for positive harmonic functions on ({\M}, g(t)), and a Poincar\'e inequality without assuming the Ricci curvature is bounded from below.Comment: final version, to appear in Am. J. Mat

A Political Economy of the Immigrant Assimilation: Internal Dynamics

Within immigrant society different groups wish to help the migrants in different ways – immigrant societies are multi-layered and multi-dimensional. We examine the situation where there exists a foundation that has resources and that wishes to help the migrants. To do so they need migrant groups to invest effort in helping their country-folk. Migrant groups compete against one another by helping their country-folk and to win grants from the foundation. We develop a model that considers how such a competition affects the resources invested by the groups’ supporters and how beneficial it is to immigrants. We consider two alternative rewards systems for supporters – absolute and relative ranking – in achieving their goals.

Migration and Culture

Culture is not new to the study of migration. It has lurked beneath the surface for some time, occasionally protruding openly into the discussion, usually under some pseudonym. The authors bring culture into the open. They are concerned with how culture manifests itself in the migration process for three groups of actors: the migrants, those remaining in the sending areas, and people already living in the recipient locations. The topics vary widely. What unites the authors is an understanding that though actors behave differently, within a group there are economically important shared beliefs (customs, values, attitudes, etc.), which we commonly refer to as culture. Culture and identify play a central role in our understanding of migration as an economic phenomenon; but what about them matters? Properly, we should be looking at the determinants of identity and the determinants of culture (prices and incomes, broadly defined). But this is not what is done. Usually identity and culture appear in economics articles as a black box. Here we try to begin to break open the black box.

Migration and Culture

Culture is not new to the study of migration. It has lurked beneath the surface for some time, occasionally protruding openly into the discussion, usually under some pseudonym. The authors bring culture into the open. They are concerned with how culture manifests itself in the migration process for three groups of actors: the migrants, those remaining in the sending areas, and people already living in the recipient locations. The topics vary widely. What unites the authors is an understanding that though actors behave differently, within a group there are economically important shared beliefs (customs, values, attitudes, etc.), which we commonly refer to as culture. Culture and identify play a central role in our understanding of migration as an economic phenomenon; but what about them matters? Properly, we should be looking at the determinants of identity and the determinants of culture (prices and incomes, broadly defined). But this is not what is done. Usually identity and culture appear in economics articles as a black box. Here we try to begin to break open the black box.migration, culture

Poverty and Governance: The Contest for Aid

Countries compete with one another for funds distributed by nongovernment organizations (NGOs). We examine the competition over poverty and governance conducted by a NGO in the allocation of its funds among potential recipient countries. The NGO in its decisionmaking process also takes into account the initial conditions of each potential recipient, including the current quality of governance and wealth (poverty). For example, all else equal, the poorer country will have a higher probability of obtaining funds; or, the better the applicant?s governance, the greater are its gains. Moreover, the maximum aid a country can obtain depends on its wealth. Investment in good governance, the wealth/poverty status of the applicant, and its current quality of governance will in conjunction determine the funds potential recipients can expect to obtain. We also consider recent changes in the levels of these factors in our attempt to understand the roles these factors play in the competition for aid, and the outcome for the quality of governance.nongovernment organizations, NGOs, aid, competition

Ethnicity, Assimilation and Harassment in the Labor Market

We often observe minority ethnic groups at a disadvantage relative to the majority. Why is this and what can be done about it? Efforts made to assimilate, and time, are two elements working to bring the minority into line with the majority. A third element, the degree to which the majority welcomes the minority, also plays a role. We develop a simple theoretical model useful for examining the consequences for assimilation and harassment of growth in the minority population, time, and the role of political institutions. Over time, conflicts develop within the minority group as members exhibit different interests in assimilating and in maintaining their cultural identity. We discuss how this affects the minority’s position over time and the influence of public policy.networks, harassment, contracts, assimilation, ethnicity, market structure

A Political Economy of the Immigrant Assimilation: Internal Dynamics

Within immigrant society different groups wish to help the migrants in different ways – immigrant societies are multi-layered and multi-dimensional. We examine the situation where there exists a foundation that has resources and that wishes to help the migrants. To do so they need migrant groups to invest effort in helping their country-folk. Migrant groups compete against one another by helping their country-folk and to win grants from the foundation. We develop a model that considers how such a competition affects the resources in-vested by the groups’ supporters and how beneficial it is to immigrants. We consider two alternative rewards systems for supporters – absolute and relative ranking – in achieving their goals.