Randomness and differentiability in higher dimensions

We present two theorems concerned with algorithmic randomness and differentiability of functions of several variables. Firstly, we prove an effective form of the Rademacher's Theorem: we show that computable randomness implies differentiability of computable Lipschitz functions of several variables. Secondly, we show that weak 2-randomness is equivalent to differentiability of computable a.e. differentiable functions of several variables.Comment: 19 page

Partial positivity: geometry and cohomology of q-ample line bundles

We give an overview of partial positivity conditions for line bundles, mostly from a cohomological point of view. Although the current work is to a large extent of expository nature, we present some minor improvements over the existing literature and a new result: a Kodaira-type vanishing theorem for effective q-ample Du Bois divisors and log canonical pairs.Comment: v1: 24 pages; v2: 25 pages, minor changes, accepted for publication in the Robfest Proceedings in honor of Rob Lazarsfeld's 60th birthday, London Mathematical Society Lecture Notes Serie

The Politics of Social Policy Reform in the United States: The Clinton and the W. Bush Presidencies Reconsidered

The purpose of this paper is to examine what key reform attempts during the Bill Clinton and George W. Bush presidencies reveal about the wider possibilities for social policy change in the United States. Most particularly, why were Presidents Clinton and Bush able to achieve their goals in some policy realms but so badly defeated in others? As argued, institutional variation from one policy area to another helps answer this question. On the one hand, strong institutional obstacles in the fields of Social Security and health insurance largely explain the defeat of the most ambitious social policy proposal put forward by each president. On the other hand, successful reforms occurred in a comparatively favourable institutional context. Yet, the analysis also suggests that paying close attention to the strategic ideas of political actors as they interact with existing institutions and policy legacies is necessary to fully understand the politics of social policy reform.social policy, Medicare, Social Security, welfare, institutions, United States

Kalman Filtering With Relays Over Wireless Fading Channels

This note studies the use of relays to improve the performance of Kalman filtering over packet dropping links. Packet reception probabilities are governed by time-varying fading channel gains, and the sensor and relay transmit powers. We consider situations with multiple sensors and relays, where each relay can either forward one of the sensors' measurements to the gateway/fusion center, or perform a simple linear network coding operation on some of the sensor measurements. Using an expected error covariance performance measure, we consider optimal and suboptimal methods for finding the best relay configuration, and power control problems for optimizing the Kalman filter performance. Our methods show that significant performance gains can be obtained through the use of relays, network coding and power control, with at least 30-40$\%$ less power consumption for a given expected error covariance specification.Comment: 7 page

Gang Re-engagement Intentions among Incarcerated Serious Juvenile Offenders

Research examining the factors that precipitate gang membership has contributed substantially to our understanding of gangs and gang-related activity, yet we know little about the factors influencing intentions to re-join a gang after having being incarcerated. This study examines the relationship between gang characteristics, number of incarcerated friends, and family characteristics and gang re-engagement intentions, while controlling for ethnicity. Participants were 206 male serious juvenile offenders interviewed as part of the Pathways to Desistance Study. The model explained between 35% and 47% of variance in gang re-engagement intentions. However, only three variables made a unique statistically significant contribution to the model (punishment if gang rules are broken, importance of gang membership, and moral disengagement), with the strongest predictor being importance of gang membership. The results suggest that challenging young offenders’ perceptions about the importance of gang membership might be particularly effective in reducing gang re-engagement intentions after incarceration