Audit report on the Iowa Turkey Marketing Council for the years ended December 31, 2006 and 2005

Audit report on the Iowa Turkey Marketing Council for the years ended December 31, 2006 and 2005

Audit report on Clinton County, Iowa for the year ended June 30, 2006

Audit report on Clinton County, Iowa for the year ended June 30, 2006

Audit report on the Dubuque County Fair Association for the year ended September 30, 2006

Audit report on the Dubuque County Fair Association for the year ended September 30, 2006

Audit report on the City of Schleswig, Iowa for the year ended June 30, 2006

Audit report on the City of Schleswig, Iowa for the year ended June 30, 2006

Reaudit report on the Des Moines Independent Community School District for the period July 1, 2004 through June 30, 2005

Reaudit report on the Des Moines Independent Community School District for the period July 1, 2004 through June 30, 2005

Audit report on the North Iowa Juvenile Detention Services Commission for the year ended June 30, 2007

Audit report on the North Iowa Juvenile Detention Services Commission for the year ended June 30, 2007

Aggregate fluctuations and the network structure of intersectoral trade

This paper analyzes the flow of intermediate inputs across sectors by adopting a network perspective on sectoral interactions. I apply these tools to show how fluctuationsin aggregate economic activity can be obtained from independent shocks to individualsectors. First, I characterize the network structure of input trade in the U.S. On thedemand side, a typical sector relies on a small number of key inputs and sectors arehomogeneous in this respect. However, in their role as input-suppliers sectors do differ:many specialized input suppliers coexist alongside general purpose sectors functioningas hubs to the economy. I then develop a model of intersectoral linkages that can reproduce these connectivity features. In a standard multisector setup, I use this modelto provide analytical expressions linking aggregate volatility to the network structureof input trade. I show that the presence of sectoral hubs - by coupling productiondecisions across sectors - leads to fluctuations in aggregates.

Audit report on the Central Iowa Juvenile Detention Center in Eldora, Iowa for the year ended June 30, 2007

Audit report on the Central Iowa Juvenile Detention Center in Eldora, Iowa for the year ended June 30, 2007

On certain greedoid polyhedra, partially indexable scheduling problems and extended restless bandit allocation indices

We present a polyhedral framework for establishing general structural properties on optimal solutions of stochastic scheduling problems, where multiple job classes vie for service resources: the existence of an optimal priority policy in a given family, characterized by a greedoid(whose feasible class subsets may receive higher priority), where optimal priorities are determined by class-ranking indices, under restricted linear performance objectives (partial indexability). This framework extends that of Bertsimas and Niño-Mora (1996), which explained the optimality of priority-index policies under all linear objectives (general indexability). We show that, if performance measures satisfy partial conservation laws (with respect to the greedoid), which extend previous generalized conservation laws, then theproblem admits a strong LP relaxation over a so-called extended greedoid polytope, which has strong structural and algorithmic properties. We present an adaptive-greedy algorithm (which extends Klimov's) taking as input the linear objective coefficients, which (1) determines whether the optimal LP solution is achievable by a policy in the given family; and (2) if so, computes a set of class-ranking indices that characterize optimal priority policies in the family. In the special case of project scheduling, we show that, under additional conditions, the optimal indices can be computed separately for each project (index decomposition). We further apply the framework to the important restless bandit model (two-action Markov decision chains), obtaining new index policies, that extend Whittle's (1988), and simple sufficient conditions for their validity. These results highlight the power of polyhedral methods (the so-called achievable region approach) in dynamic and stochastic optimization.

Audit report on the Rural Iowa Waste Management Association for the year ended June 30, 2007

Audit report on the Rural Iowa Waste Management Association for the year ended June 30, 2007

Audit report on the Black Hawk County Criminal Justice Information System (CJIS) for the year ended June 30, 2007

Audit report on the Black Hawk County Criminal Justice Information System (CJIS) for the year ended June 30, 2007

Audit report on the Iowa Corn Promotion Board for the years ended August 31, 2007 and 2006.

Audit report on the Iowa Corn Promotion Board for the years ended August 31, 2007 and 2006.

Audit report on the Iowa County Treasurers Egovernment Alliance (the Alliance) for the period from October 1, 2006 (inception) through June 30, 2007

Audit report on the Iowa County Treasurers Egovernment Alliance (the Alliance) for the period from October 1, 2006 (inception) through June 30, 2007

Audit report on the Heart of Iowa Regional Transit Agency, Des Moines, for the year ended June 30, 2007

Audit report on the Heart of Iowa Regional Transit Agency, Des Moines, for the year ended June 30, 2007

Audit report on the Northeast Iowa Schools Insurance Trust for the year ended June 30, 2007

Audit report on the Northeast Iowa Schools Insurance Trust for the year ended June 30, 2007