Stormwater-Pavement Interface in Cold Climates

This project relates to “managing stormwater runoff in cold climates” and addresses the feasibility of low-impact development at a regional demonstration site in eastern Washington. The studies relate to seven large permeable pavement systems. The findings for similar climates and soils are as follows: The draindown times for retention in Palouse or similar clay soils may handle many typical storms. On average, every square foot of a permeable pavement system installed also receives run-on from another square foot of impermeable pavement, doubling its impact on both stormwater quantity reduction and stormwater quality improvement. Most of the clogged sections on various applications were downslope of other areas. Permeable pavements installed in areas targeted for additional stormwater quantity control and quality improvement may be feasible. On average, the cleaning for installations is less frequent than annually. Power washing plus vacuuming appears to be an effective method for pervious concrete. Surface distress was usually where vehicles turned, or from placement activities. Preliminary studies on various surface treatments on pervious concrete show promise for added safety benefits under wintry conditions. Both detention-type and retention-type permeable pavement systems appear to have little negative impact on neighboring soils in the winter under the study conditions. However, further research is needed for different designs of retention-type systems to ensure that water volumes in the aggregate storage bed do not allow for sufficient water flow into neighboring soils that might result in ice lens formation or other negative impacts

Robust Transitivity in Hamiltonian Dynamics

A goal of this work is to study the dynamics in the complement of KAM tori with focus on non-local robust transitivity. We introduce $C^r$ open sets ($r=1, 2, ..., \infty$) of symplectic diffeomorphisms and Hamiltonian systems, exhibiting "large" robustly transitive sets. We show that the $C^\infty$ closure of such open sets contains a variety of systems, including so-called a priori unstable integrable systems. In addition, the existence of ergodic measures with large support is obtained for all those systems. A main ingredient of the proof is a combination of studying minimal dynamics of symplectic iterated function systems and a new tool in Hamiltonian dynamics which we call symplectic blender.Comment: 52 pages, 3 figure

Bundled Payment vs. Fee-for-Service: Impact of Payment Scheme on Performance

Healthcare reimbursements in the United States have been traditionally based on a fee-for-service (FFS) scheme, providing incentives for high volume of care, rather than efficient care. The new healthcare legislation tests new payment models that remove such incentives, such as the bundled payment (BP) system. We consider a population of patients (beneficiaries). The provider may reject patients based on the patient’s cost profile and selects the treatment intensity based on a risk-averse utility function. Treatment may result in success or failure, where failure means that unforeseen complications require further care. Our interest is in analyzing the effect of different payment schemes on outcomes such as the presence and extent of patient selection, the treatment intensity, the provider’s utility and financial risk, and the total system payoff. Our results confirm that FFS provides incentives for excessive treatment intensity and results in suboptimal system payoff. We show that BP could lead to suboptimal patient selection and treatment levels that may be lower or higher than desirable for the system, with a high level of financial risk for the provider. We also find that the performance of BP is extremely sensitive to the bundled payment value and to the provider’s risk aversion. The performance of both BP and FFS degrades when the provider becomes more risk averse. We design two payment systems, hybrid payment and stop-loss mechanisms, that alleviate the shortcomings of FFS and BP and may induce system optimum decisions in a complementary manner. This paper was accepted by Serguei Netessine, operations management

Prime ends rotation numbers and periodic points

We study the problem of existence of a periodic point in the boundary of an invariant domain for a surface homeomorphism. In the area-preserving setting, a complete classification is given in terms of rationality of Carath\'eordory's prime ends rotation number, similar to Poincar\'e's theory for circle homeomorphisms. In particular, we prove the converse of a classic result of Cartwright and Littlewood. This has a number of consequences for generic area preserving surface diffeomorphisms. For instance, we extend previous results of J. Mather on the boundary of invariant open sets for $C^r$-generic area preserving diffeomorphisms. Most results are proved in a general context, for homeomorphisms of arbitrary surfaces with a weak nonwandering-type hypothesis. This allows us to prove a conjecture of R. Walker about co-basin boundaries, and it also has applications in holomorphic dynamics.Comment: 50 pages, 15 figure

Prediction of Thermal Behavior of Pervious Concrete Pavements in Winter

Because application of pervious concrete pavement (PCPs) has extended to cold-climate regions of the United States, the safety and mobility of PCP installations during the winter season need to be maintained. Timely application of salt, anti-icing, and deicing agents for ice/snow control is most effective in providing sufficient surface friction when done at a suitable pavement surface temperature. The aim of this project was to determine the thermal properties of PCP during the winter season, and to develop a theoretical model to predict PCP surface temperature. The project included a laboratory and a field component. In the laboratory, thermal conductivity of pervious concrete was determined. A linear relationship was established between thermal conductivity and porosity for pervious concrete specimens. In the field, the pavement temperature in a PCP sidewalk installation at Washington State University was monitored via in-pavement instrumentation. Based on the field data, the Enhanced Integrated Climatic Model (EICM) was developed and validated for the site, using PCP thermal properties and local climatic data. The EICM-predicted PCP surface temperature during the winter season agreed well with the field temperature. Overall, the predicted number of days that the pavement surface fell below 32°F agreed well with the number based on field data for 85% of the days. Therefore, the developed model is useful in identifying those days to apply deicer agents. Finally, a regression model using climatic indices was developed for PCP surface temperature prediction in the absence of a more advanced temperature model

Central Corneal Thickness in Highly Myopic Eyes: Inter-device Agreement of Ultrasonic Pachymetry, Pentacam and Orbscan II Before and After Photorefractive Keratectomy

Purpose To determine inter-device agreement for central corneal thickness (CCT) measurement among ultrasound pachymetry, rotating Scheimpflug imaging (Pentacam, Oculus, Wetzlar, Germany), and scanning slit corneal topography (Orbscan II, Bausch & Lomb, Rochester, NY, USA) in highly myopic eyes before and after photorefractive keratectomy (PRK). Methods: This prospective comparative study included 61 eyes of 32 patients with high myopia who underwent PRK. Six month postoperative CCT values were compared to preoperative values in 27 patients (51 eyes) who completed the follow up period. To determine the level of agreement, Pentacam and Orbscan II readings were compared to ultrasonic pachymetry measurements as the gold standard method. Results: Mean CCT measurements with ultrasound, Pentacam, and Orbscan II before PRK were 557µm, 556µm, and 564µm, respectively; and 451µm, 447µm, and 438µm 6 months after surgery in the same order. Preoperatively, the 95% limits of agreement (LoA) with ultrasound measurements were -20μm to 17μm for Pentacam and -21μm to 33μm for Orbscan II. Six months postoperatively, the 95% LoA were -30μm to 23μm for Pentacam and -69μm to 43μm for Orbscan II. Conclusion: Preoperatively, CCT measurements were higher with Orbscan II as compared to ultrasound. Postoperatively, both Pentacam and Orbscan II measurements were lower than those obtained with ultrasound, but Pentacam had better agreement. The use of ultrasound, as the gold standard method, or Pentacam both appear to be preferable over Orbscan II among patients with high myopia

Recycled Glass Fiber Reinforced Polymer Composites Incorporated in Mortar for Improved Mechanical Performance

Glass fiber reinforced polymer (GFRP) recycled from retired wind turbines was implemented in mortar as a volumetric replacement of sand during the two phases of this study. In Phase I, the mechanically refined GFRP particle sizes were sieved for four size groups to find the optimum size. In Phase II, the select GFRP size group was incorporated at three different volumetric replacements of sand to identify the optimum replacement content. The mixtures were tested for compressive strength, flexural strength, toughness, and the potential for alkali-silicate reaction. Incorporation of GFRP in mortar proves promising in improving flexural strength and toughness in fiber-like shapes and 1–3% volumetric fractions

Testing for Consistency in Tourists' Willingness to Pay for New Nature Reserves in the Gulf of Morbihan (France)

In this paper, we develop an empirical test of consistency in contingent willingness to pay (WTP) responses, which is based on the following a priori expectation. In economics, when an individual considers paying for public goods, his decision to pay, and his WTP are based on utility-maximising behaviour. Accordingly, supposing other factors are identical, if individual A expresses greater interest in paying for public goods in general than individual B, that is because A receives more benefits from the use and/or the non-use of these goods than B. Continuing with this logic, if both individuals are asked about their WTP for a precise public good, A should logically be more likely to pay and should be willing to pay more than B. Thus, the test consists in measuring the degree to which people are likely to give money for public goods in general, and including it as a covariate in WTP models for the specific public good. If this covariate is significantly positive, then WTP responses are considered consistent. If this is not the case, then future research might focus on motives behind inconsistent WTP responses. To assess the robustness of the test, we consider 3 situations 1) the covariate is exogenous 2) it is endogenous and uncorrelated with the choice to pay or not for the specific good 3) it is endogenous and correlated with this choice. Using a contingent valuation study estimating tourists’ willingness to pay for future nature reserves in the Gulf of Morbihan, we find that WTP responses are consistent in all situations considered.contingent valuation, consistency, endogeneity, Consumer/Household Economics, Resource /Energy Economics and Policy, C24, D12, Q26,