On cohomology of invariant submanifolds of Hamiltonian actions

In this note we prove the following theorem: Let $G$ be a compact Lie group acting on a compact symplectic manifold $M$ in a Hamiltonian fashion. If $L$ is an $l$-dimensional closed invariant submanifold of $M$, on which the $G$-action is locally free then the fundamental class $[L]$ is trivial in $H_l(M,{\mathbb Q})$. We also prove similar results for lower homology groups of $L$, in case the group $G$ is a finite product of copies of $S^1$ and SU(2). The key ingredients of the proofs are Kirwan's theorem that Hamiltonian spaces are equivariantly formal and symplectic reduction.Comment: 6 pages, corrected typo

State University No More: Out-of-State Enrollment and the Growing Exclusion of High-Achieving, Low-Income Students at Public Flagship Universities

State flagship universities are facing an identity crisis. Will they continue a historic dedication to economic equity, or will they become instruments of social stratification?Although the admissions practices of private selective colleges are frequently featured in media coverage, public flagship universities enroll seven times as many Pell Grant recipients. However, these "engines of social mobility" are increasingly crowding out high-achieving, low-income students.The Great Recession brought dramatic cuts to higher education appropriations and in response, flagship universities are enrolling more out-of-state students. These students offset university budgets by paying higher tuition but often, they demonstrate lower academic achievement and higher participation in partying

Flux Analysis in Process Models via Causality

We present an approach for flux analysis in process algebra models of biological systems. We perceive flux as the flow of resources in stochastic simulations. We resort to an established correspondence between event structures, a broadly recognised model of concurrency, and state transitions of process models, seen as Petri nets. We show that we can this way extract the causal resource dependencies in simulations between individual state transitions as partial orders of events. We propose transformations on the partial orders that provide means for further analysis, and introduce a software tool, which implements these ideas. By means of an example of a published model of the Rho GTP-binding proteins, we argue that this approach can provide the substitute for flux analysis techniques on ordinary differential equation models within the stochastic setting of process algebras

Demand for International Reserves: A Quantile Regression Approach

I estimate the determinants of the demand for international reserves using quantile regressions. Employing a dataset of 96 developing nations over the period of 1980-1996, I find considerable differences at different points of the conditional distribution of reserves. The ordinary least squares estimates of elasticities that were found to be insignificant in previous studies become statistically significant at various quantiles of the reserve holding distribution. In particular, I find that the coefficients of interest rate differential and volatility of export receipts are significant and have the signs predicted by the traditional reserve models, but only for those nations that hold the highest amount of reserves. In contrast, the flexibility of the exchange rate does not seem to be an important factor for the nations that are located at the tails of the distribution.International reserves; Quantile regression; Demand for reserves; Reserve policy