Impact of High Crop Prices on Environmental Quality: A Case of Iowa and the Conservation Reserve Program, 2007

Growing demand for corn due to the expansion of ethanol has increased concerns that environmentally sensitive lands retired from agricultural production into the Conservation Reserve Program (CRP) will be cropped again. Iowa produces more ethanol than any other state in the United States, and it also produces the most corn. Thus, an examination of the impacts of higher crop prices on CRP land in Iowa can give insight into what we might expect nationally in the years ahead if crop prices remain high. We construct CRP land supply curves for various corn prices and then estimate the environmental impacts of cropping CRP land through the Environmental Policy Integrated Climate (EPIC) model. EPIC provides edge-of-field estimates of soil erosion, nutrient loss, and carbon sequestration. We find that incremental impacts increase dramatically as higher corn prices bring into production more and more environmentally fragile land. Maintaining current levels of environmental quality will require substantially higher spending levels. Even allowing for the cost savings that would accrue as CRP land leaves the program, a change in targeting strategies will likely be required to ensure that the most sensitive land does not leave the program.

Independent Living Program, Vol. 1, 2007

The Iowa Department for the Blind is the state agency that serves Iowans with vision loss. Services are free, confidential and available statewide. "There are no limitations to what you can do with training and a positive attitude." (All quotes in this newsletter are from former training participants). At the Iowa Department for the Blind, we believe in a positive approach to blindness. Vision loss alone should not prevent anyone from being independent. For this reason, we offer a wide variety of opportunities to obtain the skills necessary for independence.

A randomized concave programming method for choice network revenue management

Models incorporating more realistic models of customer behavior, as customers choosing froman offer set, have recently become popular in assortment optimization and revenue management.The dynamic program for these models is intractable and approximated by a deterministiclinear program called the CDLP which has an exponential number of columns. However, whenthe segment consideration sets overlap, the CDLP is difficult to solve. Column generationhas been proposed but finding an entering column has been shown to be NP-hard. In thispaper we propose a new approach called SDCP to solving CDLP based on segments and theirconsideration sets. SDCP is a relaxation of CDLP and hence forms a looser upper bound onthe dynamic program but coincides with CDLP for the case of non-overlapping segments. Ifthe number of elements in a consideration set for a segment is not very large (SDCP) can beapplied to any discrete-choice model of consumer behavior. We tighten the SDCP bound by(i) simulations, called the randomized concave programming (RCP) method, and (ii) by addingcuts to a recent compact formulation of the problem for a latent multinomial-choice model ofdemand (SBLP+). This latter approach turns out to be very effective, essentially obtainingCDLP value, and excellent revenue performance in simulations, even for overlapping segments.By formulating the problem as a separation problem, we give insight into why CDLP is easyfor the MNL with non-overlapping considerations sets and why generalizations of MNL posedifficulties. We perform numerical simulations to determine the revenue performance of all themethods on reference data sets in the literature.

Iowa's Beach Monitoring Program, 2005

This monthly report from the Iowa Department of Transportation is about the water quality management of Iowa's rivers, streams and lakes.

Iowa's Wetland Monitoring Program, 2005

This monthly report from the Iowa Department of Transportation is about the water quality management of Iowa's rivers, streams and lakes.

Iowa Beach Monitoring Program, 2007

This monthly report from the Iowa Department of Transportation is about the water quality management of Iowa's rivers, streams and lakes.

A-1 Monthly Public Assistance Statistical Report Family Investment Program, June 2007

A-1 - Monthly Public Assistance Statistical Report Family Investment Program - June 2007

A-1 Monthly Public Assistance Statistical Report Family Investment Program, July 2007

A-1 - Monthly Public Assistance Statistical Report Family Investment Program - July 2007

A-1a Supplemental Security Income Program, July 2007

A-1a - SUPPLEMENTAL SECURITY INCOME PROGRAM - July 2007

A-1 Monthly Public Assistance Statistical Report Family Investment Program, August 2007

A-1 - Monthly Public Assistance Statistical Report Family Investment Program - August 2007

F-1 Food Assistance Program State Summary, July 2007

The Food Assistance Monthly Participation Report is a monthly summary of Food Assistance program participation, Statewide and for each Iowa county. Breakouts are reported for participants also in the FIP program, those only receiving Food Assistance, and those that are receiving economic assistance under other programs (primarily Medicaid). This report may also be known as the F-1 Report.

F-1 Food Assistance Program State Summary, August 2007

The Food Assistance Monthly Participation Report is a monthly summary of Food Assistance program participation, Statewide and for each Iowa county. Breakouts are reported for participants also in the FIP program, those only receiving Food Assistance, and those that are receiving economic assistance under other programs (primarily Medicaid). This report may also be known as the F-1 Report.

A-1a Supplemental Security Income Program, August 2007

A-1a - SUPPLEMENTAL SECURITY INCOME PROGRAM - August 2007

A tractable consideration set structure for network revenue management

Models incorporating more realistic models of customer behavior, as customers choosing from an offerset, have recently become popular in assortment optimization and revenue management. The dynamicprogram for these models is intractable and approximated by a deterministic linear program called theCDLP which has an exponential number of columns. When there are products that are being consideredfor purchase by more than one customer segment, CDLP is difficult to solve since column generationis known to be NP-hard. However, recent research indicates that a formulation based on segments withcuts imposing consistency (SDCP+) is tractable and approximates the CDLP value very closely. In thispaper we investigate the structure of the consideration sets that make the two formulations exactly equal.We show that if the segment consideration sets follow a tree structure, CDLP = SDCP+. We give acounterexample to show that cycles can induce a gap between the CDLP and the SDCP+ relaxation.We derive two classes of valid inequalities called flow and synchronization inequalities to further improve(SDCP+), based on cycles in the consideration set structure. We give a numeric study showing theperformance of these cycle-based cuts.