Richard Hillestad

Reverse convex programming

Reverse convex programs generally have disconnected feasible regions. Basic solutions are defined and properties of the latter and of the convex hull of the feasible region are derived. Solution procedures are discussed and a cutting plane algorithm is developed.

Families of models that cross levels of resolution: issues for design, calibration and management

This review paper summarizes an ARPA-sponsored project to study variable-resolution modeling (VRM) and the connection of models across levels of resolution. We describe work introducing basic concepts, highlighting a design approach called integrated hierarchical variable-resolution modeling (IHVR), exploring mathematically some long-standing issues of aggregation in ground-combat modeling, and experimenting with cross-organizational efforts to develop and compare models created with different techniques and perspectives. We also describe highlights of a conference held in May, 1992 and touch briefly on some subsequent work. Despite the substantial progress, we conclude that the VRM problem is central, difficult, and greatly under invested. It should be approached as a matter of military science rather than technology, although we discuss new software tools that can be quite valuable.

Linear programs with an additional reverse convex constraint

A constraintg(x)⩾0 is said to be a reverse convex constraint if the functiong is continuous and strictly quasi-convex. The feasible regions for linear programs with an additional reverse convex constraint are generally non-convex and disconnected. It is shown that the convex hull of the feasible region is a convex polytope and, as a result, there is an optimal solution on an edge of the polytope defined by only the linear constraints. The only possible edges which can contain such an optimal solution are characterized in relation to the best feasible vertex of the polytope defined by only the linear constraints. This characterization then provides a finite algorithm for finding a globally optimal solution.

Cutting Some Trees to See the Forest: On Aggregation and Disaggregation in Combat Models

Most models of air and land combat use schemes of aggregation and disaggregation in representing combat systems, in spatial configuration, and in depicting progress of a battle. For example, the use of firepower «scores» is an extreme case of aggregation of weapons into a single measure. Combining like systems into weapons categories, partial aggregation, is a common approach to representing a large number of aircraft or ground weapons types. This article explores different approaches to aggregation and what is known theoretically about aggregation and disaggregation in combat models of the Lanchester type commonly called «square law» in two dimensions. It defines requirements for consistency between aggregate and higher-dimensioned models of this type. Some important conclusions are that aggregation should take into account the specific capabilities of the opponent (raising concern about many «scored» approaches which attempt to evaluate force components in isolation), and that partial aggregation (grouping «like» systems) and disaggregation of previously aggregated results can only be done consistently when certain restrictions on the relative attrition capabilities of weapons systems hold. When this is the case, specific weightings for the force resources can be determined for the partial aggregations

Crossed Wires: How Yesterday’s Privacy Rules Might Undercut Tomorrow’s Nationwide Health Information Network

More than a decade after passage of the Health Insurance Portability and Accountability Act (HIPAA), concerns about the privacy and security of personal health information remain a major policy issue. Now, the emergence of the Nationwide Health Information Network (NHIN) presents deeper underlying privacy challenges, which will require renewed attention from policymakers as federal and state privacy rules need to be revisited. This is necessary because the current framework of privacy laws is not well suited for regulating a transformed health care system, where computer networks supersede conventional communications media.

Aggregation, disaggregation, and the challenge of crossing levels of resolution when designing and connecting models

Virtual reality will sometimes require consistent simulated information at different levels of resolution. It will also require connecting models coherently that were designed independently. Basic concepts of variable-resolution modeling (VRM) are introduced, and a design approach involving hierarchical model processes and objects is described. Even in attempting to connect existing models, this approach can clarify the ideal, after which one can make integrated model adaptations rather than fixing connection problems sequentially. Experiments to improve the methods used in developing phenomenologically subtle variable-resolution models are described. How a mathematical analysis shed considerable light on a long-standing debate within the military modeling community is also described. An experiment with cross-organizational model comparisons that revealed subtle aggregation problems and may have been a prototype for what should be routine open discussion of models in circumstances where results can be reproduced or contradicted is discussed.<<ETX>>

Assessing the Preparedness of the U.S. Health Care System Infrastructure for an Alzheimer's Treatment

lzheimer’s disease is a progressive neurodegenerative disorder that leads to cognitive decline, dementia, and premature death. It exacts substantial burden on patients and on their families and caregivers, as well as on broader society (Alzheimer’s Association, undated). As the risk of developing Alzheimer’s disease increases with age, the burden of dementia will surge in industrialized countries with their graying populations. In the United States, for example, an estimated 5.5 million patients live with Alzheimer’s-related dementia today, a number that is projected to increase to 11.6 million by 2040 (Hebert et al., 2013). So far, no disease-modifying treatment is available, but a large number of drugs in development and promising early-stage results from clinical trials provide hope that one or more therapies may become available in a few years. Results from earlier clinical trials have led to the hypothesis that Alzheimer’s dementia must be prevented rather than cured because no drug has been able so far to reverse manifest dementia. Thus, current trials screen patients for signs of early-stage memory loss and/or loss of thinking skills and for so-called mild cognitive impairment (MCI), conduct tests for Alzheimer’s disease pathology, and then treat patients with the goal of halting or slowing progression of the disease. If this new paradigm bears out in late-stage clinical trials, an important health systems challenge will arise. We estimate that 13.8 million individuals in the United States today live with MCI due to any cause and that this number will grow as the population ages. Most have never been tested for Alzheimer’s disease pathology because of the lack of disease-modifying treatments. This substantial number of existing (or prevalent) cases would have to be screened, diagnosed, and then potentially treated as quickly as posC O R P O R A T I O N

When Alzheimer's Drugs Arrive, How Prepared Will We Be to Meet Demand? An Assessment of U.S. Healthcare Infrastructure

Because no drug has thus far been shown to reverse established Alzheimer’s dementia, halting progression in early stages of the disease is the most likely pathway for treatment. There is hope that one or more drug therapies, including infused drugs, may become available by 2020. At that point, a complex patient journey will start—sending those over the age of 55 on a four-part path, involving various specialists with multiple appointments at different facilities, to: