School Finance Reform: Assessing General Equilibrium Effects

In 1994 the state of Michigan implemented one of the most comprehensive school finance reforms undertaken to date in any of the states. Understanding the effects of the reform is thus of value in informing other potential reform initiatives. In addition, the reform and associated changes in the economic environment provide an opportunity to assess whether a simple general equilibrium model can be of value in framing the study of such reform initiatives. In this paper, we present and use such a model to derive predictions about the effects of the reform on housing prices and neighborhood demographic compositions. Broadly, our analysis implies that the effects of the reform and changes in the economic environment are likely to have been reflected primarily in housing prices and only modestly on neighborhood demographics. We find that evidence for the Detroit metropolitan area from the decade encompassing the reform is largely consistent with the predictions of the model.

A modified theoretical framework to assess implementation fidelity of adaptive public health interventions

Background: One of the major debates in implementation research turns around fidelity and adaptation. Fidelity is the degree to which an intervention is implemented as intended by its developers. It is meant to ensure that the intervention maintains its intended effects. Adaptation is the process of implementers or users bringing changes to the original design of an intervention. Depending on the nature of the modifications brought, adaptation could either be potentially positive or could carry the risk of threatening the theoretical basis of the intervention, resulting in a negative effect on expected outcomes. Adaptive interventions are those for which adaptation is allowed or even encouraged. Classical fidelity dimensions and conceptual frameworks do not address the issue of how to adapt an intervention while still maintaining its effectiveness. Discussion: We support the idea that fidelity and adaptation co-exist and that adaptations can impact either positively or negatively on the intervention's effectiveness. For adaptive interventions, research should answer the question how an adequate fidelity-adaptation balance can be reached. One way to address this issue is by looking systematically at the aspects of an intervention that are being adapted. We conducted fidelity research on the implementation of an empowerment strategy for dengue prevention in Cuba. In view of the adaptive nature of the strategy, we anticipated that the classical fidelity dimensions would be of limited use for assessing adaptations. The typology we used in the assessment-implemented, not-implemented, modified, or added components of the strategy-also had limitations. It did not allow us to answer the question which of the modifications introduced in the strategy contributed to or distracted from outcomes. We confronted our empirical research with existing literature on fidelity, and as a result, considered that the framework for implementation fidelity proposed by Carroll et al. in 2007 could potentially meet our concerns. We propose modifications to the framework to assess both fidelity and adaptation. Summary: The modified Carroll et al.'s framework we propose may permit a comprehensive assessment of the implementation fidelity-adaptation balance required when implementing adaptive interventions, but more empirical research is needed to validate it

Highly turbulent Taylor-Couette flow

The research issues addressed in this mostly experimental thesis concern highly\ud turbulent Taylor-Couette (TC) flow (Re>105, implying Ta>1011). We study it on\ud a fundamental level to aid our understanding of (TC) turbulence and to make predictions towards astrophysical disks, and at a practical level as applications can be found in bubble-induced skin-friction drag reduction on ships. In PART I we introduce the new TC facility of our Physics of Fluids group, called the Twente turbulent Taylor-Couette (T3C) facility. It features two independently rotating cylinders of variable radius ratio with accurate rotation rate and temperature control, torque sensing, bubble injection and it is equipped with several local sensors. It is able to reach Reynolds numbers up to 3:4�106. In PART II we focus on highly turbulent single-phase TC flow. We measure the global torque as a function of the driving parameters and we provide local angular velocity measurements. The results are interpreted as the transport of angular velocity, based on the model proposed by Eckhardt, Grossmann & Lohse (2007). Furthermore, we study the turbulence transport in quasi-Keplerian profiles, mimicking astrophysical disks. In PART III we study the effect of bubbles on highly turbulent TC flow, focusing not only on\ud global drag reduction, but also on the local bubble distribution and angular velocity profiles. We find that drag reduction is a boundary layer effect and that the deformability of bubbles is crucial for strong drag reduction in bubbly turbulent TC flow

Maximum waiting time in heavy-tailed fork-join queues

In this paper, we study the maximum waiting time $\max_{i\leq N}W_i(\cdot)$ in an $N$-server fork-join queue with heavy-tailed services as $N\to\infty$. The service times are the product of two random variables. One random variable has a regularly varying tail probability and is the same among all $N$ servers, and one random variable is Weibull distributed and is independent and identically distributed among all servers. This setup has the physical interpretation that if a job has a large size, then all the subtasks have large sizes, with some variability described by the Weibull-distributed part. We prove that after a temporal and spatial scaling, the maximum waiting time process converges in $D[0,T]$ to the supremum of an extremal process with negative drift. The temporal and spatial scaling are of order $\tilde{L}(b_N)b_N^{\frac{\beta}{(\beta-1)}}$, where $\beta$ is the shape parameter in the regularly varying distribution, $\tilde{L}(x)$ is a slowly varying function, and $(b_N,N\geq 1)$ is a sequence for which holds that $\max_{i\leq N}A_i/b_N\overset{\mathbb{P}}{\longrightarrow}1$, as $N\to\infty$, where $A_i$ are i.i.d.\ Weibull-distributed random variables. Finally, we prove steady-state convergence

Tail asymptotics for the delay in a Brownian fork-join queue

We study the tail behavior of maxi≤Nsups>0Wi(s)+WA(s)−βs as N→∞, with (Wi,i≤N) i.i.d. Brownian motions and WA an independent Brownian motion. This random variable can be seen as the maximum of N mutually dependent Brownian queues, which in turn can be interpreted as the backlog in a Brownian fork-join queue. In previous work, we have shown that this random variable centers around [Formula presented]logN. Here, we analyze the rare event that this random variable reaches the value ([Formula presented]+a)logN, with a>0. It turns out that its probability behaves roughly as a power law with N, where the exponent depends on a. However, there are three regimes, around a critical point a⋆; namely, 0a⋆. The latter regime exhibits a form of asymptotic independence, while the first regime reveals highly irregular behavior with a clear dependence structure among the N suprema, with a nontrivial transition at a=a⋆

Large fork-join queues with nearly deterministic arrival and service times

In this paper, we study an $N$ server fork-join queue with nearly deterministic arrival and service times. Specifically, we present a fluid limit for the maximum queue length as $N\to\infty$. This fluid limit depends on the initial number of tasks. In order to prove these results, we develop extreme value theory and diffusion approximations for the queue lengths.Comment: 36 pages, 15 figure