Diversify or focus: spending to combat infectious diseases when budgets are tight

We consider a health authority seeking to allocate annual budgets optimally over time to minimize the discounted social cost of infection(s) evolving in a finite set of R >= 2 groups. This optimization problem is challenging, since as is well known, the standard epidemiological model describing the spread of disease (SIS) contains a nonconvexity. Standard continuous-time optimal control is of little help, since a phase diagram is needed to address the nonconvexity and this diagram is 2R dimensional (a costate and state variable for each of the R groups). Standard discrete-time dynamic programming cannot be used either, since the minimized cost function is neither concave nor convex globally. We modify the standard dynamic programming algorithm and show how familiar, elementary arguments can be used to reach conclusions about the optimal policy with any finite number of groups. We show that under certain conditions it is optimal to focus the entire annual budget on one of the R groups at a time rather than divide it among several groups, as is often done in practice; faced with two identical groups whose only difference is their starting level of infection, it is optimal to focus on the group with fewer sick people. We also show that under certain conditions it remains optimal to focus on one group when faced with a wealth constraint instead of an annual budget.public health spending; nonconvexity; dynamic programming

Molecular biology on a microfluidic chip

We have developed microfluidic chips for automating molecular biology processes such as gene ligation and gene transformation from nanolitre sample volumes with parallel architecture. Unlike conventional tube methods with cumbersome pipetting procedures, all processes, including metering of samples, ligation and transformation, were carried out in the microfluidic chips through pneumatic control of the nanofluid. The microfluidic devices presented here offer an illustration of some of the basic physics that arises when trying to miniaturize and automate biological techniques

Experimentally validated quantitative linear model for the device physics of elastomeric microfluidic valves

A systematic experimental study and theoretical modeling of the device physics of polydimethylsiloxane “pushdown” microfluidic valves are presented. The phase space is charted by 1587 dimension combinations and encompasses 45–295 µm lateral dimensions, 16–39 µm membrane thickness, and 1–28 psi closing pressure. Three linear models are developed and tested against the empirical data, and then combined into a fourth-power-polynomial superposition. The experimentally validated final model offers a useful quantitative prediction for a valve's properties as a function of its dimensions. Typical valves (80–150 µm width) are shown to behave like thin springs

TB101: The Relevance of Option Value in Benefit-Cost Analysis

This publication represents a review and a critical re-evaluation of the literature dealing with option value. This literature is rich and dynamic and provides a fascinating sequence of articles, comments, and rebuttals. Reevaluation of the concept requires a rather comprehensive review of this literature, which is something that has not been provided to date. The literature review is also important because the work of some authors has been systematically overlooked in the course of the debate. As a result of this oversight, the original formulation of the concept continues to be cited in the literature even though its practical significance is doubtful.https://digitalcommons.library.umaine.edu/aes_techbulletin/1085/thumbnail.jp

B793: Estimation of the Cost of Providing Publicly-Supported Outdoor Recreational Facilities in Maine

Federal, state and local government agencies have historically played a significant role in providing outdoor recreational facilities for public use. Public agencies provide campgrounds, picnic areas, hiking trails, access to swimming and boating sites, interpretive facilities and programs, and numerous other types of recreational facilities. Until recently, very little attention was devoted to the costs associated with the provision of these facilities. Public funds were allocated to the construction and operation of the facilities without much concern for the economic consequences of these actions. However, during the last decade several studies have documented the cost of providing publicly supplied outdoor recreational facilities and some of the consequences. These studies have analyzed a wide range of facilities managed by state and federal agencies. The objective of this project is to measure the cost of providing various outdoor recreational facilities in Maine. The project was initiated in the Spring of 1981 following a meeting of personnel from several of the public agencies that provide recreational services and facilities. Several concerns were voiced at that meeting, including the need to revise user fees, uncertainty regarding the level of future agency funding, lack of information about provision costs, the need to document provision costs for legislative bodies, and questions regarding whether users should pay a larger share of the costs of providing the recreational facilities. A cost of provision study of a wide range of public recreational facilities seemed to be a first step in addressing many of these concerns. A cooperative agreement was written in which the Department of Agricultural and Resource Economics at the University of Maine at Orono would perform the study with funding provided by the U.S. Forest Service. Agencies participating in the study include the Maine Bureau of Parks and Recreation, Baxter State Park, Evans Notch Ranger District of the White Mountains National Forest, and Acadia National Park. The actual facilities included in the study are shown in Figure 1.https://digitalcommons.library.umaine.edu/aes_bulletin/1124/thumbnail.jp

Parallel Picoliter RT-PCR Assays Using Microfluidics

The development of microfluidic tools for high-throughput nucleic acid analysis has become a burgeoning area of research in the post-genome era. Here, we have developed a microfluidic chip to perform 72 parallel 450-pL RT-PCRs. We took advantage of Taqman hydrolysis probe chemistry to detect RNA templates as low as 34 copies. The device and method presented here may enable highly parallel single cell gene expression analysis

Scaling properties of a low-actuation pressure microfluidic valve

Using basic physical arguments, we present a design and method for the fabrication of microfluidic valves using multilayer soft lithography. These on-off valves have extremely low actuation pressures and can be used to fabricate active functions, such as pumps and mixers in integrated microfluidic chips. We characterized the performance of the valves by measuring both the actuation pressure and flow resistance over a wide range of design parameters, and compared them to both finite element simulations and alternative valve geometries

Isolating the effects of visual imagery on prospective memory

Two experiments investigated the role of visual imagery in prospective memory (PM). In experiment 1, 140 participants completed a general knowledge quiz which included a PM task of writing a letter ‘X’ next to any questions that referred to space. Participants either visualised themselves performing this task, verbalised an implementation intention about the task, did both, or did neither. Performance on the PM task was enhanced in both conditions involving visual imagery but not by implementation intentions alone. In experiment 2, 120 participants imagined themselves writing a letter ‘X’ next to questions about space, or in a bizarre imagery condition imagined themselves drawing an alien next to those questions. Relative to the control condition, PM was significantly enhanced when participants imagined writing a letter ‘X’ next to the target questions, but not by the bizarre imagery task. The findings indicate that the robust effects of imagery observed in retrospective memory also extend to PM